piedra larga i wind farm garrad hassan operational...

PIEDRA LARGA I WIND FARM

Garrad Hassan Operational Analysis Desarrollos Eólicos Mexicanos de Oaxaca 1, SAPI de CV

Report No.: 01, Rev E Document No.: 231102-ESZA-R-01-E Date: 07 Apr 2017

GL Garrad Hassan Ibérica SL Garrad Hassan Operational Analisys

IMPORTANT NOTICE AND DISCLAIMER

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4. Any wind or energy forecasts estimates or predictions are subject to factors not all of which are within the

scope of the probability and uncertainties contained or referred to in this document and nothing in this document guarantees any particular wind speed or energy output.

KEY TO DOCUMENT CLASSIFICATION

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Annex B

Additional Disclaimer Language to be Included in Report

“This Report was prepared for (i) Desarrollos Eólicos Mexicanos, S.A. de C.V. and its subsidiary,

Desarrollos Eólicos Mexicanos de Oaxaca 1, S.A.P.I. de C.V., in relation to the issuance of up to the limit

of 21,500,000 notes (certificados bursátiles) due November 15th 2030 (the “Notes”).

None of Garrad Hassan, its affiliates or any persons acting on their behalf (a) make any warranty,

expressed or implied, with respect to the use of any information or methods disclosed in this Report, (b)

assume any liability with respect to the use of information disclosed in this Report, or (c) make any

guarantee, express or implied, in relation to the energy output of the wind farms referred to herein or

the cash flows expected to be obtained by the Issuer from the operation thereof.

The documentation that has been reviewed by Garrad Hassan has been provided by Demex. Garrad

Hassan has assumed, in connection with such review, that the information it has received is accurate in

all material respects. Consequently, Garrad Hassan does not assume responsibility for the consequences

of any opinions set forth herein to the extent that such opinions were to be based on inaccurate or

incomplete information.

Garrad Hassan understands that this Report will be disclosed, among others, to rating agencies involved

in the offering of the Notes, as well as certain potential investors and investment banks in relation

therewith. In addition, Garrad Hassan understand that this Report may be included as an exhibit in a

preliminary offering memorandum (the “Preliminary Offering Memorandum”) and a final offering

memorandum (the “Final Offering Memorandum” and together with the Preliminary Offering

Memorandum, individually and collectively, the “Offering Memorandum”), to be used in connection with

the offer and sale of the Notes. As such, this Report may be used to assist in evaluating the technical,

environmental and economic aspects of the Project, subject to the provisions of this Report and the

assumptions and qualifications included herein.

All information included in this Report shall be regarded as confidential and shall not be used for any

purpose other than as set forth above without prior written authorization from Garrad Hassan.


Project name: Piedra Larga I Wind Farm DNV-GL Energy

Renewables Advisory C/Felipe Sanclemente 20 Zaragoza, Spain Tel: +34 976 435155 GL Garrad Hassan Ibérica SL

Report title: Garrad Hassan Operational Analisys Customer: Desarrollos Eólicos Mexicanos de Oaxaca 1, SAPI

de CV Contact person: Mr José Manuel Olea Date of issue: 2017-04-07 Project No.: 231102 Report No.: 01, Rev. E

Task and objective: DNV GL provides this Due Diligence for the purpose of financing the wind farm.

Prepared by: Verified by: Approved by: S Muñoz, A Zambrano, J Puche, A Lucas, K Plaxton, J Navarro

C Albero, J Navarro, JM Marco, M Marín A Baiges Head of Section

☐ Strictly Confidential Keywords: Piedra Larga, operational analisys, availability ☐ Private and Confidential

☐ Commercial in Confidence ☐ DNV GL only ☒ Client’s Discretion ☐ Published

Reference to part of this report which may lead to misinterpretation is not permissible. Rev. No. Date Reason for Issue Prepared by Verified by Approved by

A 2014-12-12 First issue S Muñoz,

J Puche,

A Lucas,

K Plaxton

A Zambrano

J Navarro

C Albero,

J Navarro,

JM Marco,

M Marin

A Baiges

B 2014-12-24 Second issue, typo correction S Muñoz,

J Puche,

A Lucas,

K Plaxton

A Zambrano

J Navarro

C Albero,

J Navarro,

JM Marco,

M Marin

A Baiges


C 2015-02-25 Third issue, review of additional

operational data

S Muñoz,

J Puche,

A Lucas,

K Plaxton

A Zambrano

J Navarro

C Albero,

J Navarro,

JM Marco,

M Marin

A Baiges

D 2015-06-05 Fourth issue, review of additional

operational data until March 2015

S Muñoz,

J Puche,

A Lucas,

K Plaxton

A Zambrano

J Navarro

C Albero,

J Navarro,

JM Marco,

M Marin

A Baiges

E 2017-04-07 Fiveth issue, review of O&M costs

projections and energy trhust

implementation

S Muñoz,

J Puche,

A Lucas,

K Plaxton

A Zambrano

J Navarro

C Albero,

J Navarro,

JM Marco,

M Marin

A Baiges

DNV GL – Report No. 01, Rev.E – www.dnvgl.com Page iGarrad Hassan Operational Analisys

Table of Contents

1 INTRODUCTION ............................................................................................................ 1

2 ENERGY ASSESSMENT ................................................................................................... 2 2.1 Site description ............................................................................................................ 2 2.2 Pre-constructive analysis ............................................................................................... 3 2.3 Operational evaluation ................................................................................................. 11

3 SITE CONDITIONS ...................................................................................................... 35 3.1 Independent site assessment ....................................................................................... 35 3.2 Manufacturer site assessment for Phase 1 of Piedra Larga ................................................ 37

4 TECHNOLOGY REVIEW ................................................................................................. 38 4.1 Company Background ................................................................................................. 38 4.2 Current turbine range .................................................................................................. 40 4.3 Gamesa G9X-2.0 MW .................................................................................................. 41

5 EPC AGREEMENT ........................................................................................................ 51

6 OPERATIONS AND MAINTENANCE AGREEMENT ............................................................... 58

7 O&M COST REVIEW ..................................................................................................... 66 7.1 Current O&M contractual conditions ............................................................................... 66 7.2 O&M costs forecast ..................................................................................................... 67

8 POWER PURCHASE AGREEMENT .................................................................................... 69 8.1 Object of the contract .................................................................................................. 69 8.2 Obligations of the contract ........................................................................................... 69 8.3 Effective period .......................................................................................................... 70 8.4 Energy pricing and payment ......................................................................................... 70 8.5 Take or pay clause ...................................................................................................... 71 8.6 New consumers .......................................................................................................... 71 8.7 Energy metering ......................................................................................................... 71 8.8 Penalties and guarantees ............................................................................................. 72 8.9 Termination of the Contract .......................................................................................... 72 8.10 Extension of the contract ............................................................................................. 74 8.11 Change of law ............................................................................................................ 74 8.12 Modifications to the PPA ............................................................................................... 75

9 PERMITS AND LICENCES .............................................................................................. 77 9.1 Open Season description .............................................................................................. 77 9.2 Interconnection Agreement .......................................................................................... 79 9.3 Self Supply Permit ...................................................................................................... 81 9.4 Transmission Agreement with CFE ................................................................................. 83 9.5 Aviation authority permits ............................................................................................ 83 9.6 Environmental permits ................................................................................................ 84

10 ELECTRICAL SYSTEM REVIEW ....................................................................................... 86 10.1 Electrical system ........................................................................................................ 86 10.2 Compliance with the Grid Code .................................................................................... 87

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11 WIND FARM INSPECTION ............................................................................................. 88 11.1 Project/wind turbine data ............................................................................................ 88 11.2 The site .................................................................................................................... 89 11.3 Turbine status ........................................................................................................... 91 11.4 Electric substation, workshop and control building ........................................................... 93

12 O&M REPORT REVIEW ................................................................................................. 96 12.1 Preventive maintenance ............................................................................................... 96 12.2 Reported causes of low production and availability .......................................................... 101 12.3 Alarms, corrective maintenance and retrofits ................................................................. 107

13 CONCLUSIONS AND RECOMMENDATIONS ..................................................................... 116 13.1 Operational evaluation ................................................................................................ 116 13.2 O&M report review ..................................................................................................... 118

14 REFERENCES ............................................................................................................ 120 A.1 Adjusted RTA ............................................................................................................ 126 A.2 Availability dependence on wind speed (RTAE)................................................................ 127 A.3 Energy weighted RTA adjusted for loss of SCADA communications (RTAE100) ....................... 128 A.4 Calculation of electrical efficiency ................................................................................. 128 B.1 Consistency of the long-term reference ......................................................................... 130 B.2 Applied correlation to the long-term reference ............................................................... 130 B.3 Energy loss factor assumptions .................................................................................... 130 B.4 Power performance adjustments .................................................................................. 130 B.5 Availability adjustments .............................................................................................. 131 B.6 Wind rose variability .................................................................................................. 131 B.7 Historical wind speed variability ................................................................................... 131 B.8 Future wind speed variability ....................................................................................... 131 B.9 Combination of uncertainties ....................................................................................... 131 B.10 Probability of exceedance levels ................................................................................... 131 References ............................................................................................................................ 132 E.1 Introduction .............................................................................................................. 157 E.2 Electrical system description ........................................................................................ 157 E.3 Compliance with the grid code ..................................................................................... 158 E.4 Diagram of electrical installations ................................................................................. 163

List of Figures

Figure 2–1: Map of the site ........................................................................................................... 2 Figure 2–2: Wind roses ................................................................................................................ 5 Figure 2–3: Normalised production per turbine and year for the Piedra Larga I Wind Farm and map of the production pattern at the site ........................................................................................................ 14 Figure 2–4: Normalised production trend of turbine PLI-16 compared to the normalised production trend for the whole wind farm ................................................................................................................ 15 Figure 2–5: Normalised production trend of turbine PLI-19 compared to the normalised production trend for the whole wind farm ................................................................................................................ 15 Figure 2–6: Measured power curves at turbines 32 and 33, and warranted power curve ......................... 19 Figure 2–7: Nacelle anemometer power curve for turbine 20 – selection period 30/09/2013 – 01/12/2013 ................................................................................................................................ 20

DNV GL – Report No. 01, Rev.E – www.dnvgl.com Page iiiGarrad Hassan Operational Analisys

Figure 2–8: Nacelle anemometer power curve for turbine 1 – selection period 01/01/2014 – 01/02/2014 . 21 Figure 2–9: Nacelle anemometer power curve for turbine 3 – selection period 14/05/2014 – 31/05/2014 . 22 Figure 2–10: Nacelle anemometer power curve for turbine 40 – selection period 06/12/2013 – 08/01/2014 ................................................................................................................................ 23 Figure 2–11: Nacelle anemometer power curve for turbine 43 – selection period 13/11/2014 – 25/11/2014 ................................................................................................................................ 23 Figure 2–12: Nacelle anemometer power curve for turbine 1 – selection period 25/12/2014 04:00– 25/12/2014 11:00 ....................................................................................................................... 24 Figure 2–13: Nacelle anemometer power curve for turbine 34 – selection period 28/03/2015 11:40- 31/03/2015 23:50 ....................................................................................................................... 25 Figure 2–14: Nacelle anemometer power curve for turbine 10 – selection period 08/01/2015 00:00- 22/01/2015 05:00 ....................................................................................................................... 26 Figure 2–15: Binned NAPCs per turbine at the Piedra Larga I Wind Farm ............................................. 27 Figure 2–16: Correlation of monthly mean daily availability and performance-corrected production of the Piedra Larga I Wind Farm and monthly mean wind speeds recorded at Mast M5 .................................... 29 Figure 4–1: Annual capacity of Gamesa wind turbines ....................................................................... 39 Figure 4–2: Installations of the current Gamesa product range (Q2 2014) ........................................... 41 Figure 4-3: Cutaway of the G80/G87-2.0 MW .................................................................................. 42 Figure 9-1: First Open Season projects and interconnection infrastructure ........................................... 77 Figure 9-2: Electrical infrastructure that connect the Isthmus area ...................................................... 79 Figure 11-1: Overview of the wind farm .......................................................................................... 89 Figure 11-2: Livestock on the site surroundings (left) and the Espiritu Santo River (right) ...................... 90 Figure 11-3: Principal road access to the wind farm with the guardhouse (left) and one of the two patrol vehicles (right) ............................................................................................................................ 90 Figure 11-4: Remains of oil leaks of the pitch falling from the yaw system ........................................... 91 Figure 11-5: Specific location of the joint rupture in the pitch hydraulic system .................................... 92 Figure 11-6: High temperature version of the nacelle installed in Piedra Larga Phase I (left) and failure of the automatic mechanism used for opening the front blind (right) ....................................................... 92 Figure 11-7: The two buildings of the substation (left) and an internal picture of the spare parts warehouse (right) ........................................................................................................................ 94 Figure 11-8: Principal components as spare parts (blades and generators) ........................................... 94 Figure 12–1: Annual wind distribution in the Isthmus of Tehuantepec /121/ ......................................... 98 Figure 12–2: Durations of planned maintenance /121/ ...................................................................... 99 Figure 12–3: Stop time by alarm occurrences in the Piedra Larga WTGs during 2013 and 2014 ............... 108 Figure 12–4: Occurrences of gearbox system alarms ........................................................................ 109 Figure 12–5: Number of occurrences of converter alarms .................................................................. 110 Figure 12–6: Stopped hours in Piedra Larga WTGs, caused by corrective maintenance ........................... 112 Figure 12–7: Time of corrective maintenance for solving the issues related with the converter system alarms ....................................................................................................................................... 113

List of Tables

Table 2–1: Site information ........................................................................................................... 3 Table 2–2: Location and measuring period of each site mast .............................................................. 4 Table 2–3: Location and measuring period of each reference station ................................................... 4 Table 2–4: Estimated long-term hub height wind speeds at the site masts ........................................... 4 Table 2–5: Turbine layout with predicted wind speed and energy production for the Piedra Larga Phase I Wind Farm .................................................................................................................................. 6 Table 2–6: Characteristics and performance data of the G80-2.0 MW turbines ...................................... 8 Table 2–7: Projected annual energy production of Piedra Larga Phase I .............................................. 9

DNV GL – Report No. 01, Rev.E – www.dnvgl.com Page ivGarrad Hassan Operational Analisys

Table 2–8: Uncertainties in the net energy production for the wind farm .............................................. 9 Table 2–9: Predicted monthly energy production for Phase I of Piedra Larga Wind Farm as a percentage of total energy production ............................................................................................................. 10 Table 2–10: Standard errors associated with the gross and net energy predictions ................................ 11 Table 2–11: Monthly production, data coverage, availability and performance statistics for the Piedra Larga I Wind Farm ....................................................................................................................... 16 Table 2–12: Net energy yields for Piedra Larga I based on operational data ......................................... 30 Table 2–13: Confidence limits of net energy yield predictions – Piedra Larga I ...................................... 32 Table 2–14: Uncertainty in the projected energy production of Piedra Larga I Wind Farm ....................... 32 Table 2–15: Energy results based on a pre-constructive analysis (WSBE) ............................................ 33 Table 3–1: Wind farms characteristics ............................................................................................ 35 Table 3–2: Values obtained - VS IEC conditions ............................................................................... 35 Table 4–1: Summary description of the Gamesa turbines .................................................................. 40 Table 4-2: Summary description of the Gamesa G80 turbine .............................................................. 43 Table 4-3: Key design elements and industry standard ...................................................................... 43 Table 4-4: Certification status ....................................................................................................... 44 Table 4-5: Summary of main grid code requirements ........................................................................ 45 Table 4-6: Temperature limits for the G9X-2.0 MW turbine ................................................................ 46 Table 4-7: Track record of the G9X (Gamesa product update: June 2014) ............................................ 47 Table 5-1: Main conditions of the EPC agreement in place with GESA for Piedra Larga Phase I ................ 52 Table 6-1: Main conditions of the O&M agreement in place with Gamesa for Piedra Larga Phase I ............ 59 Table 7-1: Contractual turbine O&M costs updated to Dec 2016 .......................................................... 66 Table 7-2: Expected future O&M costs under Scenario A (2017 prices) ................................................ 67 Table 7-3: Expected future O&M costs under Scenario B (2017 prices) ................................................ 67 Table 8-1: Critical construction dates .............................................................................................. 73 Table 9-1: First Open Season projects ............................................................................................ 78 Table 10-1: Electrical loss assessment for Phase I ............................................................................ 87 Table 12–1: Period between preventative maintenance, programmed and commissioning dates of the Piedra Larga I wind turbines .......................................................................................................... 97 Table 12–2: WTGs alarms with significant impact on January 2013 availability...................................... 102 Table 12–3: WTGs alarms with significant impact on February 2013 availability .................................... 103 Table 12–4: WTGs alarms with significant impact on March 2013 availability ........................................ 104 Table 12–5: WTGs alarms with significant impact on April 2013 availability .......................................... 105 Table 12–6: WTGs alarms with significant impact on July 2013 availability ........................................... 106 Table 12–7: WTGs alarms with more stops- hours in years 2013-2014 ................................................ 108 Table 13–1: Confidence limits of net energy yield predictions – Piedra Larga I ...................................... 117 Table C–1: Preventative maintenance delays ................................................................................... 134 Table C–2: Differences between the Renovalia and O&M monthly reports ............................................. 136 Table C–3: Faults with most hours of stopping for January 2013 ......................................................... 137 Table C–4: Faults with most hours of stopping for February 2013 ....................................................... 137 Table C–5: Faults with most hours of stopping for March 2013 ........................................................... 137 Table C–6: Faults with most hours of stopping for April 2013 ............................................................. 138 Table C–7: Faults with most hours of stopping for July 2013 .............................................................. 138 Table C–8: Faults with most hours of stopping for January 2014 ......................................................... 139 Table C–9: Alarm occurrences and stop time related to alarms in the Piedra Larga wind farm ................. 139 Table C–10: Time of system corrective maintenance at the Piedra Larga wind farm ............................... 139

DNV GL – Report No. 01, Rev E – www.dnvgl.com Page 1Garrad Hassan Operational Analisys

1 INTRODUCTION

Desarrollos Eólicos Mexicanos de Oaxaca 1 SAPI de C.V (“DEMEX 1” or, the “Customer”) has requested that DNV GL (previously named “GL Garrad Hassan Ibérica SL” or, “GL GH”) carries out an operational assessment of the Piedra Larga I Wind Farm in México. This includes an update of the technology and a review of the monthly operation reports (proposal 230963-ESZA-P-01-C /2/).

In addition to the operational review, it has been requested by the Customer that the previous conclusions from the Piedra Larga I DD review undertaken by DNV GL /1/.

The operational energy assessment for Piedra Larga I is based on 2.3 years of operational data, from January 2013 to March 2015. However, DNV GL also presents the pre-constructive analysis conducted in 2012 (based on the mentioned DD report), before the wind farm was in operation, despite the results based on the operational data being considered more robust than the corresponding results from wind flow modelling.


2 ENERGY ASSESSMENT

2.1 Site description

The Piedra Larga I and II wind farms are located in Oaxaca (Mexico). Piedra Larga I is composed of 45 Gamesa G80-2MW wind turbines at 67 m hub height. The wind farm has been in operation since October 2012 and it was commissioned in December 2012. The operational assessment, based on monthly production data, covers the period January 2013 to December 2014.

Additional information about the region is provided below in Section 9.1 Open Season description, and about the site itself in Section 11 Wind Farm Inspection.

A map of the site showing the locations of the meteorological masts, neighbouring wind farms and the turbine layouts is presented in Figure 2–1.

Figure 2–1: Map of the site

300000 302000 304000 306000 308000 310000 312000 314000

Eastings [m]

1818000

1820000

1822000

1824000

1826000

1828000

1830000

1832000

1834000

1836000

Nor

thin

gs [

m]

1 2 3 4 5 6 7 8 9 10 11 12 13

14 15

16

17

18

19

20 21 22

23 24 25 26

27 28 29 30

31

32

33

34

35

36 37 38 39 40 41

42

43

44 45

46

47

48 49 50 51

52 53 54 55 56

57 58 59 60

61

62

63 64 65 66

67

68

69

M1

M2

M3

M4

M5

12

3 4

56

7 8 9 10 11 12 13 14

15

16 17

18

19 20

21 22 23

24 25

26 27

28

29

30

31 32 33

34

35

36

37

38

39

40

41 42

43

44 45

La Venta 2 WF

Oaxaca 2 WF

Oaxaca 3 WF

Eurus WF

Piedra Larga I WF

Piedra Larga II WF

Santo Domingo


The Piedra Larga wind farm is subdivided into two phases, with the following characteristics:

Table 2–1: Site information

Phase I Phase II

Rated Power 90.0 MW 138.0 MW

Wind Turbine Model 45 Gamesa G80 69 Gamesa G80 and G87

Hub Height 67 m 78 m

The main results of the independent assessment of energy production are summarized in this section.

A description of the long-term wind climate at a wind farm site is best determined by using wind data recorded at the site. DNV GL has been provided with data recorded between September 2005 and September 2012 at the Piedra Larga site, from five meteorological masts, Masts 1, 2, 3, 4, and 5 - see Figure 2–1.

2.2 Pre-constructive analysis

The pre-constructive analysis was conducted in 2012, prior to commissioning of the wind farm. The analysis is based on a larger number of assumptions and models than the operational analysis presented in Section 2.3; therefore, the energy forecast (based on an operational assessment) is considered to be more robust than the energy results (based on a wind flow model).

DNV GL uses different routes of analysis, depending on the characteristics of each Project and the data that is available. It should be noted that these different analyses correspond to different methods, used with the constant aim of obtaining a more accurate long-term energy forecast and a lower uncertainty, rather than different criteria. If there is any room for doubt between the two different routes of analysis a balance of the uncertainty is chosen, using the route with the lower uncertainty as the main criterion. These different methods are (in order of priority):

1. Operational analysis. This requires at least one year of monthly net production and availability data (12-monthly data), although it is desirable to have at least 1.5–2.0 years of consistent monthly data concurrent with a suitable long-term reference, in order to establish correlations and, depending on the uncertainty balance, to extend the period. Depending on the possibility of having a long enough final representative period, the uncertainties of these analyses are typically (mainly) much lower than in the pre-constructive assessments, thereby avoiding several instrumental and wind-flow modelling uncertainties.

2. Pre-constructive analysis. When the wind farms are not operating, or the consistent or operational period (with “inconsistent” referring to, for instance, power limitations, the addition of wind turbines, or other matters) is below the recommended minimum, it is not possible to conduct an operational analysis.

2.2.1 Meteorological masts

The following table presents the location and measuring period of each site mast used.


Table 2–2: Location and measuring period of each site mast

Mast Location Period

Eastings [m] Northings [m]

Mast 1 301010 1828613 Sep 2005 to Sep 2012

Mast 2 306720 1826332 Mar 2008 to Dec 2011

Mast 3 305930 1827608 Nov 2008 to Jan 2012

Mast 4 306436 1823309 Nov 2008 to Sep 2012

Mast 5 310161 1824178 Nov 2008 to Sep 2012

It is noted that data recorded at Mast 3 after May 2011 were not used in the analysis, due to the construction of the Oaxaca III Wind Farm and the resulting wake impact on wind speed measurements. DNV GL staff visited the Piedra Larga site in November 2012 and confirmed the documented instrument mounting arrangements on Masts 1, 4, and 5. Masts 2 and 3 were not observed during that visit because they had been decommissioned.

When only a short period of site data is available, it is usual to combine the site measurements with long-term measurements from a local meteorological station. DNV GL has been provided with data from 10 potential reference towers. After undertaking an extensive review of these data, DNV GL found the La Venta 3 and Santo Domingo 3 meteorological towers to be the most suitable sources of long-term reference data.

The following table presents the location and the measuring period of each reference station used.

Table 2–3: Location and measuring period of each reference station

Mast Location Period

Eastings [m] Northings [m]

La Venta 3 308029 1835737 Nov 2001 to Jul 2008

Santo Domingo 3 310644 1829780 Nov 2001 to Feb 2009

By combining the measured and synthesized data resulting from correlations between the 7.2 years of valid reference data and 6.2 years of valid site data, to achieve a final period of 11 years of valid data, DNV GL has estimated the power law shear exponents and long-term hub height wind speeds at the site masts, as shown in the table below. Only those masts (used to initiate the wind flow model in each phase) have wind speeds that are presented at the respective hub height.

Table 2–4: Estimated long-term hub height wind speeds at the site masts

Mast Power law shear Long-term wind speed (m/s)

Exponent (α) 67 m hub height 78 m hub height

Mast 2 0.20 9.6 -

Mast 3 0.18 9.7 -

Mast 4 0.19 9.4 9.7

Mast 5 0.29 - 9.8


The long-term wind roses at Masts 2, 3, 4, and 5 are presented in Figure 2–2. Mast 1 has not been used as an initiation mast for either of the wind flow models, due to its distance from the turbine locations.

Figure 2–2: Wind roses

Predicted long-term annual wind rose at Mast 2

at 67 m height


at 67 m height


at 67 m height


at 78 m height

60%40%20%

0-3 3-6 6-9 >9m/s

60%40%20%

0-3 3-6 6-9 >9m/s

60%40%20%

0-3 3-6 6-9 >9m/s

60%40%20%

0-3 3-6 6-9 >9m/s


Predicted long-term annual wind rose at Mast 5 at 78 m height

2.2.2 Energy estimations

Piedra Larga Phase I consists of 45 Gamesa G80-2.0 MW turbines at 67 m hub height, for an installed capacity of 90 MW. This layout has been supplied by the Customer and analysed in conjunction with the results of the wind analysis, in order to predict the long-term energy output of the proposed wind farm. Table 2–5 presents the coordinates for each turbine position in Phase I.

Table 2–5: Turbine layout with predicted wind speed and energy production for the Piedra Larga Phase I Wind Farm

Turbine Easting1 Northing1 Initiation mast

Mean hub-height wind

speed2

Energy output3

Wake loss4

[m] [m] [m/s] [GWh/annum] [%] 1 304670 1827615 M3 9.7 6.9 10.0

2 304922 1827916 M3 9.7 6.6 12.8

3 305237 1827722 M3 9.7 6.8 9.6

4 305460 1827728 M3 9.7 6.7 11.2

5 307422 1824438 M4 9.5 7.3 6.4

6 307149 1825096 M2 9.6 7.2 6.0

7 304918 1826882 M2 9.7 7.2 7.4

8 305106 1826861 M2 9.7 7.2 7.4

9 305340 1826781 M2 9.6 7.2 7.7

10 305543 1826791 M2 9.7 7.1 8.1

11 305742 1826835 M2 9.6 7.0 8.8

12 305963 1826927 M2 9.6 7.0 9.9

13 306262 1826930 M2 9.6 7.1 8.8

14 306499 1826989 M2 9.6 7.2 7.1

15 306739 1826926 M2 9.7 7.3 5.6

16 307032 1826834 M2 9.6 7.4 4.7

80%60%40%20%

0-3 3-6 6-9 >9m/s


17 307279 1826898 M2 9.6 7.4 4.0

18 306618 1825227 M2 9.5 7.2 6.5

19 304816 1826036 M2 9.6 7.3 5.9

20 305056 1826068 M2 9.7 7.2 7.2

21 305297 1826022 M2 9.6 7.2 7.2

22 305537 1826032 M2 9.6 7.2 7.7

23 305776 1826049 M2 9.6 7.2 7.4

24 306047 1826023 M2 9.6 7.2 7.0

25 306278 1826054 M2 9.5 7.2 6.9

26 306509 1826054 M2 9.5 7.2 6.6

27 306743 1826070 M2 9.6 7.3 5.5

28 306978 1826062 M2 9.6 7.3 5.8

29 307216 1826063 M2 9.6 7.3 5.9

30 307491 1826334 M2 9.6 7.4 4.3

31 307697 1826175 M2 9.6 7.4 3.6

32 307936 1826232 M2 9.6 7.4 3.5

33 308177 1826240 M2 9.5 7.4 3.5

34 308417 1826151 M2 9.5 7.4 3.4

35 308657 1826151 M2 9.5 7.4 3.3

36 308897 1825958 M2 9.6 7.4 3.3

37 309137 1825958 M2 9.5 7.4 2.9

38 304877 1825448 M2 9.6 7.2 7.8

39 305083 1825408 M2 9.5 7.2 6.5

40 307354 1825146 M2 9.5 7.2 5.4

41 306341 1824327 M4 9.4 7.3 5.9

42 306544 1824337 M4 9.4 7.2 6.2

43 306757 1824335 M4 9.4 7.3 6.3

44 306965 1824336 M4 9.4 7.3 6.1

45 307213 1824422 M4 9.4 7.2 8.1

1 The coordinate system is UTM Zone 15, WGS84 datum. 2 Wind speed at the location of the turbine, not including wake effects. 3 Individual turbine net energy, including all wind farm losses. 4 Individual turbine wake loss, including all wake effects.

The characteristics and performance data of the G80-2.0 MW turbines are presented in Table 2–6. The power curve is based on calculations and an exhibit peak power coefficient, Cp, of 0.44. DNV GL finds this level of peak Cp to be typical amongst modern wind turbines. DNV GL recommends that formal warranted and independently measured power curves are obtained, to confirm the performance levels assumed here, ideally in similar ambient conditions.


Table 2–6: Characteristics and performance data of the G80-2.0 MW turbines

Hub height wind speed [m/s]

Gamesa G80-2MW

Electrical power [kW]

Thrust coefficient

4.0 61 0.329 5.0 141 0.390 6.0 261 0.418 7.0 427 0.431 8.0 646 0.437 9.0 916 0.435

10.0 1216 0.421 11.0 1512 0.393 12.0 1753 0.351 13.0 1900 0.299 14.0 1966 0.248 15.0 1990 0.204 16.0 1997 0.169 17.0 1999 0.141 18.0 2000 0.119 19.0 2000 0.101 20.0 2000 0.086 21.0 2000 0.075 22.0 2000 0.065 23.0 2000 0.057 24.0 2000 0.050 25.0 2000 0.044

Diameter [m] 80

Hub height [m] 67

Rotor speed [rpm] 9 to 19

Air density [kg/m3] 1.15

Turbulence intensity 10%

Peak Cp 0.44

Cut-out ten-minute mean wind speed

[m/s] 25

Piedra Larga Phase I is located in a highly active region of wind farm development. The Customer has provided the turbine coordinates for the Phase II, Oaxaca II, Oaxaca III, Eurus and La Venta II wind farms, and these farms have been included in this assessment in order to calculate their wake impact on Piedra Larga Phase I. Although it is expected that wind farm development will continue in the vicinity of the Piedra Larga site, the impact of future wake effects has not been modelled in this analysis. Figure 2–1 presents the relative locations of all the above-mentioned wind farms.

The projected annual energy production of the Piedra Larga I Wind Farm over the first 10 years of operation is summarized in the table below. The projected energy capture of individual turbines is given in Table 2–5. These estimates include potential sources of energy loss that have been either estimated or assumed. It is recommended that these loss factors are reviewed and considered carefully.


Table 2–7: Projected annual energy production of Piedra Larga Phase I

Rated power 90 MW

Gross energy output 387.9 GWh/annum

Wake effect 93.4 %

Availability 95.0 %

Electrical efficiency 97.8 %

Turbine performance 96.8 %

Environmental 99.5 %

Curtailment 100.0 %

Net energy output 324.4 GWh/annum

Capacity factor 41.2 %

The main sources of deviation from the central estimate have been quantified. The figures obtained are added as independent errors, giving the following uncertainties in net energy production for the wind farm. These represent the standard deviation of what is assumed to be a Gaussian process.

Table 2–8: Uncertainties in the net energy production for the wind farm

Wind farm 1 year average [GWh/annum]

10 year average [GWh/annum]

Piedra Larga Phase I 30.2 23.6

Table 2–9 presents the estimated average variation in monthly energy production, based on seasonal variation in wind speed and air density. It is noted that the uncertainty associated with the prediction of any given month is significantly greater than that associated with the prediction of annual energy production as presented above.


Table 2–9: Predicted monthly energy production for Phase I of Piedra Larga Wind Farm as a percentage of total energy production

Month %

January 11.9

February 10.1

March 10.2

April 6.9

May 6.2

June 5.2

July 7.3

August 7.0

September 6.1

October 7.7

November 10.0

December 11.4

The uncertainties that have been considered in the analysis of the wind farm include the following:

The accuracy of the wind speed measurements; The accuracy of the wind speed correlations; The consistency of data measured at the site ; The assumption that the period of historical data available is representative of the long-term

wind regime; The consistency of the historical data; The accuracy of the wind flow modelling; The accuracy of the wake modelling; The accuracy of the fiscal sub-station meter; The accuracy of the availability, electrical, turbine performance, environmental and curtailment

loss assumptions; The variability of the future annual wind speeds at the site.

There are several uncertainties for which only pragmatic assumptions have been made at this stage, including those listed below. It is recommended that First Reserve considers each of these uncertainties carefully. Uncertainties can often be mitigated to some extent, especially in the early years of a project, through appropriate warranty provisions. Therefore, the following uncertainties should be considered in detail, in combination with the warranty provisions:

Availability; Electrical losses; Turbine performance; Environmental losses; Curtailment.

The standard errors associated with the predictions of energy capture have been calculated and confidence limits for the predictions are given in the table below:


Table 2–10: Standard errors associated with the gross and net energy predictions

Probability of exceedance

[%]

Net energy output [GWh/annum]

Piedra Larga Phase I

1 year average 10 year average

99% 254.1 269.4

95% 274.7 285.5

90% 285.7 294.1

75% 304.0 308.5

50% 324.4 324.4

2.3 Operational evaluation

2.3.1 Operational data supplied for the analysis

The Customer has supplied the following information for the analysis, covering the periods January 2013-May 2014 /4/ and June 2014-December 2014 /125/ and from January 2015 to March 2015 /128/:

- Monthly energy recorded at the point of grid connection for the period from January 2013 to March 2015 for the Piedra Larga I Wind Farm, supported by invoices.

- Information about downtimes associated with the grid and Balance of Plant, with data from January 2013 to February 2014, and indications that there were not any other relevant events after February 2014.

- 10-minute data recorded from December 2008 to December 2014 at two meteorological stations near to the wind farms (named Mast M5 and Mast M4).

- Monthly production and availability for the period from December 2012 to December 2014, on a per-turbine and whole wind farm basis, for the Piedra Larga I Wind Farm, including also the total generated energy between January 2015 and March 2015.

- Alarms and events for the period from January 2013 to March 2015, for the Piedra Larga I Wind Farm.

- 10-minute average data of nacelle wind speed, active and reactive power, nacelle orientation and generator temperature, for every turbine from January 2013 to March 2015.

2.3.1.1 Data coverage and integrity

The coverage of the 10-minute average turbine SCADA data over the period from January 2013 to March 2015 has been reviewed. The mean monthly SCADA data coverage has been approximately 90.6%, with an average figure of 97.7% from 2014 onwards. These values are shown in Table 2–11, in Section 2.3.4. The analysis indicated a significant lack of density data, mostly in the initial months. It is noted that non-ideal coverage of the SCADA system would increase uncertainty in the estimation of energy loss during months for which data coverage is low.

The initial analysis of the data from the Mast M5 meteorological mast indicated good data coverage for wind speed and air density data. The air density data estimated from the mast measurements have been used to correct the energy loss estimation according to IEC 61400-12-1. In the absence of certain air


density data, the corresponding density figures have been estimated from either historical data or virtual data.

2.3.2 Selection of a long-term reference

In assessing the long-term energy production of a wind farm it is generally necessary to correlate data recorded on the site with data recorded at a nearby long-term reference, such as a meteorological station. On-site data are often only recorded for a short period and a good correlation is required to ensure that the estimate of wind farm production is representative of long-term conditions. When selecting a reference station for this purpose, it is important that it should have good exposure and be representative of conditions at the site; data should also be consistent throughout the measurement period being considered.

The Customer facilitated data from some nearby projects as potential reference stations. Mast La Venta 3, which is located 10 km north of the site, has been found to be the most suitable to act as a reference station, together with Mast M1 (installed at the site prior the construction of the wind farm) and the current site Mast M5. Mast M4 was rejected, due to wake impact from the operating wind turbines. The wake effects at Mast M5 from the Piedra Larga I Wind Farm have been estimated to be approximately 0.2%. Therefore, the Mast M5 wind data have been adjusted by this factor until October 2012.

DNV GL has studied the consistency of the reference data provided. Despite no clear trend changes in the reference wind speeds, it is observed that a global reduction in the wind speeds over time had the global effect of increasing the wind speed and associated energy when synthesizing data from 2002 to 2005 from La Venta 3, and from 2005 to 2008 from the M1 meteorological mast. These wind speed variations are higher than was initially expected, but not out the expected annual wind speed variation, and it has also been observed in another reference met station in the region. This is not clear evidence of inconsistency and the use of these data is accepted as a suitable reference time series, including an additional uncertainty to take into account the afore-mentioned comments. In any future updates with longer operational data it would be recommended to use only the operational data, Mast M5 and the on-site mast, in order to avoid any potential doubt regarding the historical wind speed trend before 2008.

Correlations on a monthly basis have been undertaken between the site data and Mast M5, between the M5 and M1 masts, and between M1 and La Venta 3, according to the following approach:

1- Monthly wind speed correlations between La Venta 3 and at Mast M1, synthesizing additional data at mast M1 between January 2002 and September 2005, and filling some data gaps.

2- Monthly wind speed correlations between measurements at Mast M1 and Mast M5 at 65 m, using the synthesized and measured data series at Mast M1 obtained in Step 1 to synthesize additional data at Mast M5 between January 2002 and November 2008, and filling some data gaps.

3- Correlations between the monthly wind speeds at Mast M5 at 65 m and the operational on-site data, using the synthesized and measured data series at Mast M5 at 65 m obtained in Step 2 to synthesize additional operational data between January 2002 and December 2013.

DNV GL considers the resulting R2 values of between 0.95 and 0.98 to be suitable for use. Therefore, DNV GL considers these stations to be suitable as a representative source of long-term reference data for this site.

The analysis therefore relies on operational data recorded at the site and synthesized data from the La Venta 3 masts for the period from November 2001 to January 2012, Mast M1 for the period from September 2005 to April 2012, the current on-site Mast M5 from December 2008 to September 2014


and the operational data From January 2013 to March 2015. The uncertainty associated with assuming this period to be representative of the long term is discussed in Section 2.3.7.

2.3.3 Monthly data analysis

In addition to the analysis carried out at wind farm level, DNV GL has performed a review of the individual turbine data in order to establish an understanding of the power curve performance of the turbines. The input data is the monthly individual turbine production and availability data, taken from the monthly reports for each wind farm. The assessment is denominated as Average Production Trend analysis (APT) and is used to identify any anomalies in operation between the wind turbines within the wind farm. If any anomalies are identified, the cause of the under-performance of the affected turbines should be investigated and remedied. This can then lead to an increase in the energy production of the wind farm.

The APT analysis is described in the following steps:

Individual turbine normalised production trend

The monthly production observed at each turbine is divided by the reported availability for that turbine.

Each monthly corrected production figure is then divided by the average of all monthly corrected production figures, resulting in a normalised production trend for each turbine.

Whole wind farm normalised production trend

The monthly production observed for the whole wind farm is divided by the reported availability for the whole wind farm (the average of all turbine availabilities).

Each monthly corrected production figure is then divided by the average of all monthly corrected production figures, resulting in a normalised production trend for the whole wind farm.

Comparison of normalised production trends

The normalised production trend for each turbine is compared to the normalised production trend for the whole wind farm, by plotting these on the same chart to establish if any individual turbines show gross inconsistencies in performance over time. It is assumed that each individual turbine, if the power curve performance is consistent over time, will follow the average trend across the whole wind farm.

Results of the APT analysis

Figure 2–3 shows the normalised production, per turbine and year, for the Piedra Larga I Wind Farm and a map of the relative production at each wind turbine. It is observed that there is significant variation in the performance of the turbines across the site. The pattern of production presents a level of variation that is greater than expected. Additionally, the patterns of production over time also show relatively large variations. The SCADA analysis presented in Section 2.3.4 studies the anomalies observed in the APT analysis in more detail.


Figure 2–3: Normalised production per turbine and year for the Piedra Larga I Wind Farm and map of the production pattern at the site

Figure 2–4 shows the APT plot for Turbine PLI-16. The plot shows that the turbine suffered several downtimes during the initial operating months, and some other availability adjustments, resulting in several differences between the normalized production trend and the production trend. This effect has also been observed in several other wind turbines.

Figure 2–5 shows the APT plot for Turbine PLI-19. The plot shows that the turbine produced less energy than the wind farm average from January to February 2014. The production figures are corrected for reported availability and therefore the observed low production of Turbine PLI-19 could be attributed to power performance, wake effects or topographical effects.


Figure 2–4: Normalised production trend of turbine PLI-16 compared to the normalised production trend for the whole wind farm

Figure 2–5: Normalised production trend of turbine PLI-19 compared to the normalised production trend for the whole wind farm

2.3.4 SCADA ANALYSIS

2.3.4.1 Availability

For the purposes of the long-term production forecast described here, a measure of the overall system availability is required. DNV GL has calculated the time-weighted Run Time Availability (RTAT100) adjusted for data loss (thus RTAE100), based on the 10-minute SCADA data. The SCADA data from January 2013 to March 2015 was analysed after the commissioning date in December 2012.


In this project it is considered that the availability measure that most closely represents the proportion of energy lost due to the wind farm being unavailable is the energy weighted RTA, adjusted for data loss (RTAE100). The measure of RTAE100 is calculated from RTAT100, which is a measure of availability that counts any downtime against the availability, regardless of the cause. The details of these calculations and descriptions of RTA can be found in APPENDIX A: Additionally, due to a reported and solved problem /5/ with the accumulated power registered at the SCADA system in the initial months of operation, the RTAE100 figures obtained until October 2013 have been amended to take into account the alarm data and information regarding the balance of plant and grid incidences, obtaining the amended RTAE100.

During the period from January 2013 to March 2015 the average monthly amended RTAE100 was 94.3%, with an annual figure of 96.1% from January 2014 onwards. This measure of availability covers the whole wind farm system, taking into account turbine availability, balance of plant availability and grid availability, as well as downtime due to high wind speeds and time required to wait until the wind speed is within the wind turbine controller’s specifications.

It is noted that the wind farm showed a low value of availability RTAE100 during several months before March 2014, as a consequence of several grid and substation downtimes, and also in July 2014 due to the annual substation maintenance. This was due to changes in the balance of plant infrastructure as well as to wind turbine ramp up availability, including a large number of communications-related alarms which were significantly reduced following a controller upgrade, reported in /6/.

Table 2–11 shows the monthly values of the RTAE100 and availability reported in the O&M Excel files between January 2013 and March 2015, as well as the SCADA data coverage and relative power efficiency which is explained in Section 2.3.4.2.

A value of 96.0% for future long-term availability (in terms of energy) has been considered for the Piedra Larga I Wind Farm, based on the historical availability data and trends as well as on DNV GL’s experience with a large number of operational wind farms. The long-term availability figures used in the different operational analyses conducted for that wind farm range from 95.5% to 96.0%. The latest operational period analysed support the figure of 96.0%, however it is recommended that the wind farm’s performance and availability is monitored, in order to validate the long-term availability assumption. That recommendation includes following the substation and grid downtimes. It is also recommendable trying to prevent downtimes at high wind speeds, because due to H&S reasons there are some O&M tasks not allowed in these conditions, what leads to an availability reduction.

Table 2–11: Monthly production, data coverage, availability and performance statistics for the

Piedra Larga I Wind Farm

Month Monthly utility

metered production

[MWh]

SCADA data

coverage [%]

Manufacturer reported turbine

availability [%]

BoP And Grid

Availability

[%]

Amended RTAE100

[%]

Relative power curve

efficiency [%]

01/2013 37171 54.7% 91.5% 96.4% 88.2% 97.2%

02/2013 23201 74.2% 92.5% 99.0% 91.6% 98.3%

03/2013 32367 69.3% 92.5% 99.2% 92.4% 96.0%


04/2013 15918 80.4% 91.9% 92.6% 85.1% 99.5%

05/2013 16276 73.6% 97.4% 96.9% 94.4% 99.8%

06/2013 10852 86.4% 97.3% 95.1% 92.6% 99.9%

07/2013 21469 72.3% 95.7% 99.7% 95.4% 99.9%

08/2013 25628 94.8% 97.5% 96.7% 94.3% 99.9%

09/2013 2505 96.6% 98.0% 99.7% 97.7% 99.9%

10/2013 18942 95.7% 98.5% 98.0% 95.4% 99.6%

11/2013 34019 97.1% 97.1% 100.0% 94.7% 98.1%

12/2013 36737 85.9% 97.1% 95.3% 88.5% 97.7%

01/2014 38682 87.0% 96.9% 99.1% 88.4% 97.8%

02/2014 27268 98.0% 97.2% 99.6% 92.8% 99.1%

03/2014 22853 98.8% 98.8% 100.0% 98.2% 99.4%

04/2014 22740 98.4% 98.8% 100.0% 96.2% 99.3%

05/2014 23435 98.6% 98.6% 100.0% 96.4% 99.1%

06/2014 7927 98.6% 98.7% 99.7% 98.3% 99.9%

07/2014 35671 94.0% 98.4% 94.7% 95.1% 99.7%

08/2014 22086 98.8% 99.3% 100.0% 99.5% 99.9%

09/2014 11398 97.9% 98.9% 99.5% 97.5% 99.9%

10/2014 21595 98.7% 99.3% 100.0% 98.8% 99.9%

11/2014 35938 98.7% 98.2% 100.0% 95.7% 98.3%

12/2014 42793 98.2% 98.9% 99.6% 96.6% 98.7%

01/2015 44665 99.8% 87.8% 99.0%

02/2015 34126 99.6% 96.4% 99.6%

03/2015 34602 99.9% 96.1% 98.3%

Total 301277 91.1% 97.1% 98.4% 94.3% 99.1%


2.3.4.2 Power curve performance

In order to analyse the operating power performance for each turbine in detail, power curves have been derived from the 10-minute average turbine power and nacelle anemometer wind speed measurements recorded by the SCADA system. The period of study covers January 2013 to March 2015.

The general methodology employed in the power curve analysis is described below:

1. The consistency of the power curves measured by the SCADA system was assessed, in order to identify any trends in performance between turbines and over time.

2. Any outlying turbines or periods identified in Step 1 were investigated further, in order to identify: (a) any measurement inconsistencies in the data; (b) any systematic variations in the operation of the turbines; and (c) any intermittent variations in turbine performance.

3. A series of reference power curves were derived in order to determine a baseline level of performance that represents ‘normal’ operation of the turbines. These curves take into account the results of the investigations described in Step 2, excluding data that are not representative of ‘normal’ operation.

4. A measurement of the relative power curve efficiency was derived for each month in the operational period, by comparing raw production data with the reference power curves during periods where performance issues were identified.

Additionally, DNV GL has been provided with the IEC 61400-12-1 power performance test results at wind turbines 32 and 33 /7/. Figure 2–6 presents these power curve plots, showing that the measured power curves are below those warranted within the range of wind speeds between 10 and 17 m/s - also observed in the SCADA power curves for the whole wind farm.


Figure 2–6: Measured power curves at turbines 32 and 33, and warranted power curve

The wind speed values have been corrected by site air density, in order to estimate energy losses. The air density values used were recorded by on-site masts from sensors installed on Mast M5. A review of the Nacelle Anemometer Power Curves (NAPCs) has been undertaken for each turbine, covering the period from January 2012 to March 2015, and the following observations have been made:

DNV GL has observed several periods where the power curves of several turbines are seen “moved to the right” with respect to the rest of the power curves (thus showing a lower power curve). DNV GL has analysed the cause of these behaviours, based on an assessment of wind speed and performance correlations between the affected turbines and neighbouring turbines with consistent power curves. It is considered that these apparent performance changes are not real in most cases, being the result of inconsistent anemometry at the turbines. Figure 2–7 shows the scatter NAPC for Turbine 20 at Piedra Larga I. Turbines 8 and 21 were also affected by an inconsistency in the nacelle anemometer readings, and also turbine 45 from December 2014.


Figure 2–7: Nacelle anemometer power curve for turbine 20 – selection period 30/09/2013 – 01/12/2013

However, Turbines 45 and 34 presented real underperformance, in the period December 2013 and March 2014 and between April and May 2014. Therefore, it is especially recommended that the O&M staff is contacted, to check the behaviour of turbine T34. DNV GL has correlated the wind direction recorded at these wind turbines against nearby wind turbines, considering that the potential cause of these underperformances is a problem with the orientation of the nacelles. Gamesa was contacted to clarify this point, stating /121/ that the scheduled O&M tasks include the inspection of the sonic anemometers and yaw orientation system. Additionally /121/ indicates that Gamesa has planned checking the appropriate orientation of all the sonic anemometers at the 45 wind turbines, actions which according to the client concluded in April 2015.

All the power curves present a cut-out wind speed that is clearly below the theoretical speed of 25 m/s, with the wind turbines stopping at wind speeds of between 19 m/s and 23 m/s. This might be due to the behaviour of the wind turbine control in the case of high wind speeds, which is detected on the basis of a few seconds and is not possible to assess from the 10-minute average data provided. The manufacturer was contacted, to verify both this point and what the appropriate operation of the wind turbines at high wind speeds is thought to be. Gamesa responded /121/ that each wind turbine is stopped in case of a 100 seconds wind speed greater than 25 m/s or a 2 seconds wind speed greater than 30 m/s, which implies that the wind turbines could be stopped due to high wind speed for 10-minute wind speeds below 25 m/s. Figure 2–8 presents this effect for turbine 1, showing the normal data in January 2014 in black


and highlighting the abnormal data (including some data “to the left of the power curve” that is affected by the anemometry readings, present at all the turbines) in red.


During intermittent periods, approximately 16 turbines (turbines 3, 5, 6, 7, 8, 9, 14, 16, 19,

21, 23, 28, 34, 40, 41 and 45, with the turbines 3, 8 and 16 curtailed in May 2014, the last month studied) have been constrained to varying maximum power levels that are lower than the nameplate rated power of 2,000 kW. This is illustrated in Figure 2–9 which shows the scatter NAPC for Turbine 3: the normal data in May 2014 are shown in black and the flagged data for this month are highlighted in red. The Customer has informed DNV GL that the manufacturer applied a curtailment strategy to reduce the torque at some wind turbines, in some cases, which is also reported in the O&M documentation. However, the number of wind turbines affected (including some wind turbines in May 2014) is higher than was initially expected. It was strongly recommended to confirm with the manufacturer if this power limitation is required as part of the normal operation of the wind farm.

The manufacturer stated /121/ that in case of alarms related to torque limitations, amongst others, and the meteorological conditions do not allow an immediate corrective action, the power is limited, to allow the turbine to be operated at derated power. That document states that the unexpected high wind speeds recorded in May 2014 did not allow conducting the appropriate corrective tasks related to the aforementioned alarms and for that reason


curtailments were more frequent that month. DNV GL considers that for certain alarms this behaviour is acceptable to allow the operation of the turbines until they are serviced.


Some other wind turbines presented sporadic periods of underperformance that were clearly not due to power limitations or misalignment, with data that were below the power curve trend. For instance, Turbine 40 presented a large amount of these underperforming data, most likely related to several alarms with the generator. This is presented in Figure 2–10. It is observed a similar effect in wind turbine 29 in the period from 27th to 31st January, when alarms related to generator high temperature have been recorded. Figure 2–11 shows a similar behaviour at Turbine 43 in November 2014, with several power limitations likely related to alarms due to high gearbox temperature.



Figure 2–11: Nacelle anemometer power curve for turbine 43 – selection period 13/11/2014

– 25/11/2014


The whole wind farm suffered a power limitation applied by CFE on 25 December 2014 during approximately 7 hours, as it is showed in Figure 2–12 for Turbine 1.

Figure 2–12: Nacelle anemometer power curve for turbine 1 – selection period 25/12/2014 04:00– 25/12/2014 11:00

Turbines where limited to around 1000 kW on 16th March, approximately from 11:50 to 19:20 due to a power limitation applied by CFE.

Wind turbines 16 and 34 presented un underperformance from 28th to 31th March 2015, when gearbox high temperature alarms were recorded. Figure 2–13 shows the corresponding power curve for turbine 34. It has been observed a similar behavior at turbine 27 in February 2015. It is recommended to follow up the gearbox oil levels and their cooling system.


Figure 2–13: Nacelle anemometer power curve for turbine 34 – selection period 28/03/2015 11:40- 31/03/2015 23:50


Figure 2–14: Nacelle anemometer power curve for turbine 10 – selection period 08/01/2015 00:00- 22/01/2015 05:00

Some wind turbines where stopped for several consecutive days, mostly in months with high wind speeds. Figure 2–14 shows the scatter power curve for turbine 10, which was stopped from 8th to 22th January 2015. It is possible that the relatively extended downtime is related to H&S protocols which do not allow accessing to the wind turbines. However it is recommended trying to prevent these relatively large unavailability periods.

Based on the findings of the power performance assessment, DNV GL has derived a series of ‘relative power curve efficiency’ figures for the wind farm, on a monthly basis. These represent a percentage estimate of the energy lost or gained, relative to the turbines operating ‘normally’.

By this method, it has been estimated that the mean monthly power curve efficiency was 99.0% for Piedra Larga I, for the period covering January 2013 to March 2015. The corresponding long-term figure considered is 99.3%, considering that part of the underperformance observed in the initial period is not representative of the long-term expectations and that the Customer will approach the manufacturer to solve some of the aforementioned issues. The monthly average relative power curve efficiency statistics for Piedra Larga I are presented in Table 2–11.


DNV GL has compared the Binned NAPCs for all the turbines, in order to assess the consistency of performance from turbine to turbine. Figure 2–15 shows the binned NAPCs per turbine at Piedra Larga I, based on all the data recorded during the period from January 2013 to December 2014. Periods where the turbines were registered as unavailable, periods of curtailment or periods where spurious wind speed data was recorded have all been excluded from the dataset.

The power curve performance has, in general, been consistent over the operational period. It is noted that the warranted power curve is used in these plots only as a visual aid, so SCADA power curves have been defined by perturbed anemometers. This comparison is only useful for verifying the homogeneity of the power curves of different turbines in the same wind farm.

DNV GL has only provided commentary on the relative changes in power performance from turbine to turbine and over time and not on how the turbines compare to the warranted power curve for the site. In order to compare the site power curves to the warranted power curve, a formal IEC 61400-12-1 power curve performance test is required. This has been conducted at turbines 32 and 33 and it showed a production level that was 4.3% below that calculated for the warranted power curve /7/.

Figure 2–15: Binned NAPCs per turbine at the Piedra Larga I Wind Farm


2.3.5 Assessment of the long-term energy production

2.3.5.1 Long-term energy production methodology

The following steps were taken to estimate the long-term energy production of the Piedra Larga I Wind Farm:

1 A monthly time series of production data, metered at the point of grid connection, was obtained from the monthly production data for the period from January 2013 to March 2015.

2 The monthly production time series from Step 1 above, was factored by the corresponding monthly availability derived in Section 2.3.4.1 and the ‘relative power curve efficiency’ derived in Section 2.3.4.2 to reflect estimated production had the turbines been operating at 100% availability and at the expected ‘normal’ performance level. The final availability and power performance adjusted production data are provided (on a monthly basis) in Table 2–11. The production data since August 2014 were also divided by the wake impact from the nearby Piedra Larga II Wind Farm, estimated at 99.4%.

3 The availability adjusted production data was divided by the number of days in each month, to provide mean daily adjusted metered production data.

4 The resulting time series was correlated to concurrent data recorded at Mast M5 at 65 m (the correlation reached a value of R2 of 0.97, as shown in Figure 2–16). This correlation was subsequently used to synthesize additional data for the Piedra Larga I Wind Farm, for the period from January 2002 to November 2008, including wind data synthesized at Mast M5 from M1 and La Venta 3.

5 The synthesized data described in Step 4 were combined with the measured mean daily production data described in Step 3, resulting in a time series of measured and synthesized mean daily production data for the period from January 2002 to March 2015. This time series was converted to monthly production by multiplying each mean daily production value by the number of days in the corresponding month.

6 The ‘sum of monthly means’ method was applied to the time series of measured and synthesized production data, in order to provide an annual estimate of energy production without the influence of seasonal bias caused by over-representation of some months in the synthesized time series:

- The monthly mean production was calculated for each calendar month.

- The ‘sum of monthly means’ was obtained by summing these 12 monthly mean production values.

7 The net annual long-term production has been calculated by multiplying the figure obtained in Step 6 by the long-term future availability figure (96.0%) which was derived from the historical background and future expectations and multiplied by the long-term expected power curve factor (estimated at 99.3%) and by the wakes impact due to the nearby Piedra Larga II Wind Farm, estimated at 99.4%. The energy gains after the installation of the “Energy Thrust” and “Safe Mode” strategies have been provided by Gamesa based on 1 year of operational data with these retrofits, with a figure of +2.85% (see Section 2.3.6) have been included in the net energy.

8 The uncertainty associated with long-term production has been calculated and is described in APPENDIX B:


The long-term net energy projection presented here does not take into account any future changes to the exposure of the Project. In particular, wake losses due to future construction of wind farms in the surrounding area or the extension of existing wind farms are not considered in the present analysis. However, taking into account the already operational wind farms (presented in Figure 2–1) around Piedra Larga I Wind Farm and the dominant winds from the North it is not expected to have a very significant wake impact from other future wind farms.

DNV GL does not consider it appropriate to include any additional loss factors.

Figure 2–16: Correlation of monthly mean daily availability and performance-corrected production of the Piedra Larga I Wind Farm and monthly mean wind speeds recorded at Mast

M5


2.3.6 Projected energy production

The projected energy output of the Piedra Larga I Wind Farm is detailed in the tables below and is followed by a brief explanation of the loss factors applied to the gross energy production. As noted in Section 2.3.5, these results are the average of the results obtained by synthesizing data from masts M5, M1 and La Venta 3.

Table 2–12: Net energy yields for Piedra Larga I based on operational data Piedra Larga I Wind

Farm

Wind Farm Rated Power 90.0 MW Gross Energy Output (operational) 334.0 GWh/annum

Wake effect 100.0 % Availability 96.0 % Electrical efficiency 100.0 % Turbine performance 99.3 % Environmental 100.0 % Curtailment 100.0 % Wakes from Piedra Larga II 99.4 %

Energy thrust and safe mode strategies gains (see Section 2.3.6) 102.85 %

Net Energy Output 325.7 GWh/annum Equivalent Hours 3618 Capacity Factor 41.3 %

The gross output of the Piedra Larga I Wind Farm has been estimated, based on actual production data that have been corrected to represent 100% availability and 100% relative power curve efficiency. The corrected production values have been placed in the context of long-term wind speed expectations by establishing a correlation to wind speed data from masts M5, M1 and La Venta 3, defining a final long term period of 12.8 years.

Topographic and wake effects, electrical efficiency, icing and blade degradation, high wind hysteresis and environmental losses are all considered to be inherent in the historical production and are also assumed to be representative of long-term expectations.

The production during the operational period (January 2013 to March 2015) was 301.3 GWh/year at Piedra Larga I Wind Farm.

Loss factors of 96.0% and 99.3%, representing future availability and future turbine performance respectively, have been considered appropriate. These factors could change in future, when more data becomes available, depending on the wind farm’s performance. Continuous monitoring of wind turbine performance and availability is recommended, both to optimize the wind farm’s performance and to validate the above figures.


DNV GL has been provided with the IEC 61400-12-1 power performance test results for WTG32 and WTG 33 /7/. The power performance test results show that the expected energy production, based on the measured power curves, is 4.3% below what is expected for the warranted power curve.

The Customer has requested an analysis of the possible improvement margin if the underperformance of the wind turbines could be improved, following (in part) a proposal from Gamesa to improve the energy output at the wind turbine by using several retrofits, globally termed “Energy Thrust” and “Safe Mode” strategies /19/. This document states that a maximum energy gain of 3.0% may be obtained, following implementation of these strategies; it also recommends a load analysis. Although the document does not present detailed calculations for this energy gain estimation, a maximum figure of 3% is considered to be possible.

The aforementioned “Energy Thrust” and “Safe Mode” strategies have been already implemented at Piedra Larga I Wind Farm in December 2015. The information provided by the Customer /129/ shows that the energy gains at Piedra Larga I between December 15th 2015 and December 14th 2016 was 2.85It is recommended to follow up the energy gains provided by the energy thrust. %. DNV GL is aware that the energy gains calculation is included by Gamesa as part of the retrofits implementation.

Additionally, DNV GL has recommended conducting a load analysis as it was suggested by the manufacturer. DNV GL has been provided with a Gamesa document /130/ which evaluates the additional loads due to the Energy Thrust, concluding that these additional loads are not relevant and the wind turbine integrity is not clearly affected.

The net production figures included in Table 2–12 already include the estimated energy increment of 2.85% from the installation of the “Energy Thrust” and “Safe Mode” strategies.


2.3.7 Uncertainty analysis

The main sources of deviation from the central estimate of the energy prediction of the wind farms have been quantified for each of the scenarios and the results are presented in Table 2–13. Table 2–14 shows a more detailed description of the uncertainty analysis.

Table 2–13: Confidence limits of net energy yield predictions – Piedra Larga I Net energy output

Exceedance probability [%] 1 year [GWh/annum] 10 years [GWh/annum]

99.0 249.5 281.6

90.0 283.7 301.4

75.0 303.6 312.9

50.0 325.7 325.7

Table 2–14: Uncertainty in the projected energy production of Piedra Larga I Wind Farm Source of uncertainty Wind speed Energy output

[%] [%] [GWh/annum] Consistency of long-term reference 1.7 2.4 7.72 Historical wind speeds representative of long-term 1.7 2.4 7.88 Availability adjustments

1.7 5.51 Power curve performance adjustments

0.2 0.62 Applied correlation to long-term reference

3.3 10.70 Loss factor assumptions

0.5 1.63 Wakes modeling

1.0 3.26

Future wind variability (1 year) 6.0 8.6 28.13 Future wind variability (10 years) 1.9 2.7 8.90

Overall energy uncertainty (1 year)

10.1 32.74 Overall energy uncertainty (10 years)

5.8 18.96

It is worth mentioning that the P90/P50 ratio for the 10 years future wind scenario is 92.5%. According to DNV GL criterion this reflects a low level of uncertainty in this energy prediction, as it is expected in an operational data analysis with a long representative operational period. The 10-years scenario provides a better view on the long-term expectations and is therefore generally used as reference in the valuation models. On the other hand, the 1-year scenario provides a view over the yearly variability of the production and is therefore mostly in used in a valuation to conduct sanity checks.


2.3.8 Comparison between the pre-constructive and operational long-term energy forecasts

The “Production Based Estimate” (PBE) energy output presented in Table 2–12 has been compared with the results obtained from the pre-constructive assessment that was conducted before the wind farm operation “Wind Speed Based Estimate” (WSBE):

Table 2–15: Energy results based on a pre-constructive analysis (WSBE)

Piedra Larga Wind Farm Phase I

Wind Project Rated Power 90.0 MW Gross Energy Output 387.9 GWh/annum

1 Wake effect 1a Wake effect internal 96.7 % 1b Wake effect external 96.6 % 1c Future wake effect 100.0 % 2 Availability 2a Turbine availability (10 years) 96.2 % 2b Balance of Plant availability 99.8 % 2c Grid availability 99.0 % 3 Electrical efficiency 3a Operational electrical efficiency 97.8 % 3b Wind farm consumption 100.0 % 4 Turbine Performance

4a Generic power curve adjustment 100.0 %

4b High wind speed hysteresis 97.9 %

4c Site-specific power curve adjustment 99.8 %

4d Sub-optimal turbine performance 99.0 %

5 Environmental

5a Performance degradation – non-icing 99.5 %

5b Performance degradation – icing 100.0 %

5c Icing shutdown 100.0 %

5d Temperature shutdown 100.0 %

5e Site access 100.0 %

5f Tree growth 100.0 %

6 Curtailments 6a Wind sector management 100.0 % 6b Grid curtailment 100.0 % 6c Noise, visual and environmental 100.0 % Net Energy Output 324.4 GWh/annum

The PBE result is 0.4% higher than that for the WSBE. Even if this is not a detailed reconciliation analysis, and the aforementioned difference is not an especially large number, DNV GL has nevertheless undertaken a preliminary analysis at a high level of detail, in order to better understand any underlying reasons for the discrepancy between the forecasts. The main reasons for the differences are listed below:


1. The difference of 0.4% is small and within the uncertainty limits. It is noted that the number of assumptions required in a pre-constructive assessment should be taken into account. Generally speaking, a pre-constructive assessment should be subject to a higher uncertainty than an operational assessment would be.

2. The formal IEC 61400-12-1 power curve measurement test at 2 wind turbines in Piedra Larga I show that the energy output at these turbines is 4.3% below that warranted.

3. The estimated figure for electrical losses, using the operational data, is 4.0%, rather than the 2.2% considered in the pre-constructive assessment. Despite the uncertainty of the operational calculations, it is considered that the real electrical loses are higher than those estimated in the pre-constructive assessment.

4. The SCADA analysis shows that all the power curves present a cut out wind speed which is clearly below the theoretical one, of 25 m/s, with the wind turbines stopping at wind speeds of between 19 m/s and 23 m/s. This might be due to the behaviour of the wind turbine control when high wind speeds are detected on the basis of a few seconds; behaviour which it is not possible to assess using the 10-minute average data provided. As a result of this, the energy losses at high winds are higher than those estimated in the WSBE analysis.

5. The PBE analysis includes an energy gains of +2.85% after the installation of the “energy thrust” and “safe mode” strategies.

6. The long term period is different, with 2 additional years in the PBE analysis.


3 SITE CONDITIONS

3.1 Independent site assessment

DNV GL has undertaken an analysis of the conditions present at the Piedra Larga site, in accordance with the IEC 64100-1, Edition 3 Amendment, standard. The tables below summarize the results.

Table 3–1: Wind farms characteristics

Wind Farm Turbine Type(s)

Piedra Larga Phase I G80-2.0 MW

67 m HH Class IA

Table 3–2: Values obtained - VS IEC conditions

Characteristic Piedra Larga Phase I 1

IEC Class IA2

Annual mean wind speed at turbine locations [m/s] 9.4 to 9.7 10

Annual mean air density [kg/m3] 3 1.159 1.225

50-year return period 3-second gust [m/s] 54.3 70

50-year return period 10-minute mean [m/s] 41.7 50

Representative turbulence intensity at 15 m/s [%] 16.1 to 18.6 18

Inflow angle [º] < 1 8

Mean shear exponent 0.18 to 0.29 0.2

Min. temperature (operational/survival) [C] 11.8 -10/-20

Max. temperature (operational /survival) [C] 38.8 40/50

1 DNV GL values calculated from site data. 1 IEC 64100-1, Edition 3 Amendment. 2 Air density is higher in winter, during the windiest months. A possible seasonal density bias of ~0.2%

has been estimated. Details about these results and calculation methods are presented below.

Annual air density

The average predicted air density on-site is 1.158 kg/m3, at a hub elevation of 81 m for Phase I.

Mean wind speed

The mean wind speed varies across the site, from 9.4 m/s to 9.7 m/s at 67 m in Phase I. All Phase I turbine locations meet the IEC Class I specifications for annual mean wind speed.

Extreme wind speed

An assessment of extreme wind speed requires extensive data, usually in excess of 10 years of on-site gust measurements, in order to capture the extreme events. At the time of this analysis, valid wind data were available for 5.8 years at Piedra Larga’s Mast 1. Whilst not ideal, this data period has been used to conduct a formal Gumbel Method of Independent Storms analysis of the extreme wind speeds. The results indicate that the 50-year extreme 10-minute mean wind speed is 41.7 m/s at 67 m, for Phase I. Using the Weiranga equation, the 50-year extreme 3-second gusts were estimated to be 54.3 m/s at 67 m.

The maximum 10-minute mean wind speed recorded at the Piedra Larga site was 31.6


m/s at Mast 1, at 66 m, on 01 December 2010.

It should be noted that this approach to calculating extreme wind speed can only consider the wind mechanisms experienced during the period of recording, and, given the assumptions made and the significant uncertainties inherent in this methodology, it is recommended that conservative assumptions are made when interpreting the results. Nevertheless, it is not expected that the extreme wind speeds at the Piedra Larga site will exceed Class I specifications.

Turbulence intensity

To determine how turbulence varies across the site, measured wind data have been used to derive the ambient turbulence at the site masts. Equivalent hub height design turbulence values, using the Frandsen method, have been derived on an individual turbine basis according to the IEC 61400-1, Edition 3 Amendment, and these were found to range from 16.1% to 18.6%, at 67 m at 15 m/s in Phase I. In summary, turbulence intensity in Phase 1 is slightly exceeded.

These values were derived using the WindFarmer model, based on the variation of turbulence intensity with wind speed. The turbulence was extrapolated to the turbine positions, using speed-up factors derived from the wind flow model.

These calculated turbulence values exceed the subclass A specifications. DNV GL recommends that the turbine supplier is approached at an early stage, in order to gain approval for the proposed layout and turbine selection.

Shear

Using data collected from the site, the values for the annual power law wind shear exponents across the site are found to range from 0.19 to 0.29. These measured values are higher than those in the IEC standard (0.2). It is also noted that neither seasonal nor diurnal variation in wind shear has been considered here.

The direct implication is that wind speed increases greatly with height: the wind speed at the uppermost position of the rotor is much higher than the wind speed at the lowest position of the rotor. As a consequence, the loads (in particular in the axis) and fatigue may be higher than expected. Wind shear suffers variations between day and night, due to the warmth of the ground: during the day, wind shear is lower (but turbulence is higher), whilst at night wind shear is higher. The values provided are therefore the daily average.

Regarding the energy analysis, the wind shear has been assessed on a directional basis, taking into account the diurnal seasonal patterns. A directional adjustment approach was used for the frequency distribution extrapolations . It is noted that most of the masts have measurements at either hub height or ¾ hub height, so uncertainty due to the vertical extrapolations is not very significant.

Temperature range

Temperatures of between 11.8ºC and 38.8ºC have been observed over ten-minute averaging periods at all the site masts, between December 2005 and September 2012. Extreme data from the La Venta 3 and Sto. Domingo 3 reference masts have also been reviewed, and, for the period from November 2005 to February 2009, temperatures between 16.1ºC and 41.9ºC were observed over 10-minute averaging periods. Ten-minute mean temperatures of over 40 ºC were recorded at La Venta 3 and Sto. Dominto 3, for 28 and 31 hours, respectively.

Inflow angle

In the absence of vertical wind speed measurements and in terrain like that at the Piedra Larga site, it is DNV GL practice to assume that the incident inflow angle equals the value of the upstream terrain slope. Slopes proximate to each turbine were calculated, using a topographic map of the Piedra Larga site at a distance of two rotor diameters from the center of the hub, for every degree sector and in five-degree increments. The ground slopes do not indicate any significant vertical wind flow components; a site maximum inflow angle of less than 1º is predicted in the Phase I layout.

Wind rose The Piedra Larga site wind rose is principally uni-directional - from the north.

Inter-turbine A minimum inter-turbine spacing of 2.4 rotor diameters occurs in Phase I. These


spacing spacings are not in the prevailing wind direction, thus the resulting increase in turbulence levels, which in turn has the potential to increase the fatigue loads on the turbines, is only taking place a few times in the year.

When there is such a short distance between turbines, some manufacturers recommend that they are stopped during certain wind directions (the wind direction along the turbine rows), in order to reduce the loads (the frequency of that direction is very low, thus the production loss is almost negligible). However Gamesa, as per the loads studies conducted by them and summarized in Section 3.2 below, concluded that this strategy is not necessary.

Mitigation DNV GL has not considered any wind sector management or curtailment strategies for Piedra Larga I.

3.2 Manufacturer site assessment for Phase 1 of Piedra Larga

DNV GL has been provided with Annex U-3 /51/ of the EPC contract, which includes a site-specific study from Gamesa that was performed using the information provided by the Customer regarding the wind resource at the site (Gamesa document GD055905 Rev 1, dated 16/09/09). This site assessment has been conducted for the entire project (Phases 1 and 2), at 114 different turbine positions. According to the Gamesa study, the G80 IEC Class IA 67 m hub height turbine is suitable for installation at the given turbine positions at the wind farm, except for nine positions which were initialized from met mast 5, where not enough wind measurements were available (at the time) to draw conclusions about fatigue loads. This conclusion from Gamesa is valid, provided that the wind resource data are reliable and representative of the site conditions. DNV GL notes that this study has not been updated with the definitive turbine coordinates and that it is therefore not conclusive.

Additionally, a new site-specific study from Gamesa was received on 28 January 2013. This study is not a revision of the previous document, but version 6 of document reference GD117701 (only this version was provided), dated 21/12/12 /114/. This study is for the 45 turbines of Phase 1 and has been updated with the final coordinates. It concludes that, despite some site conditions being above Class IA, after having performed a loads study, the turbines are suitable for the given turbine positions of the wind farm.

Also a letter from Gamesa dated on 18/12/2012 has been provided by the Customer /122/, where Gamesa acknowledges the last coordinate’s changes and the final layout, version 6-2, certifying that the warranties under the supply contract are maintained.

DNV GL notes that document GD117701 /114/ does not include the layout version name, but it has been observed that the Annex 1 of said letter /122/ shows the same coordinates as the site study. Therefore, despite the site-specific study /114/ has not been attached to the contract, the contract warranties are applicable for the layout used by Gamesa to undertake the loads analysis, and that confirms the Gamesa’s confirmation of the suitability of the turbines for the site.

According to the EPC contract /49/, clause 15.4 of the General Warranty, Gamesa guarantees the suitability of the machines for the site and ensures that the micro-siting is compatible with the design of the machine. No wind sector management was considered necessary by Gamesa after conducting the loads analysis.


4 TECHNOLOGY REVIEW The sections below present the review of the Gamesa G9X -2.0 MW technology.

4.1 Company Background

Gamesa Eólica started to manufacture Vestas wind turbines under licence for the Spanish and South American markets in 1994, and it has since grown rapidly, to become the market leader in Spain. At the end of 2011, it accounted for over 50% of the Spanish installed wind capacity, with a total installed capacity of approximately 11,510MW in Spain /30/. The company’s growth strategy is supported until 2013 by emerging markets, including the Asian, Latin American and African markets. A major commercial effort is expected in South Africa, the Middle East, South Asia and Australasia. As part of its efficiency strategy, Gamesa will try to make a continuous adjustment of capacity to demand, by fully localising the supply chain in India and Brazil. Gamesa has ten Research & Development centres in Spain, the United States, India, China, the UK, Brazil and Singapore.

Gamesa Eólica is part of the Gamesa group (established in 1974) which comprises Gamesa Energía, Gamesa Aeronautica, Gamesa Industrial and Gamesa Servicios. Gamesa was floated on the Spanish Stock Market in 2001. In December 2001, Gamesa bought Vestas’ 40% holding in Gamesa Eólica and the 9% shareholding held by the Navarran government entity, Sodena. The wind turbine manufacturer is now a wholly-owned subsidiary of the listed parent company. Gamesa is publicly traded on the Spanish stock exchange and is included in the Dow Jones sustainability index. Gamesa’s main shareholder is Iberdrola, S.A., with a 19.6% share.

In 2001, Gamesa purchased the gearbox manufacturer Echesa, and in 2003 it purchased the generator manufacturer, Cantarey Reinosa, which previously manufactured (amongst other products) permanent magnet direct drive generators for wind turbines.

In May 2003, Gamesa bought MADE, a Spanish wind turbine manufacturer owned by the utility ENDESA. The acquisition made Gamesa the fourth largest wind turbine manufacturer in the world in terms of total installed capacity, just behind Vestas, Enercon and GE Wind.

In January 2004, Gamesa bought the company Enertron, based in Madrid. This company specialises in the design and manufacture of integrated power electronic systems, thus bringing the technology to manufacture wind turbines and wind farm control systems in-house, whereas this had previously been sub-contracted to Ingecon.

In April 2006 Gamesa Corporación announced the sale of its OMS (operation, maintenance and service) division to the venture capital fund, 3i. At present, Gamesa has accumulated more than 16 GW in repowering and O&M services /33/.

Also in 2006, Gamesa sold its automotive and aeronautics businesses in order to focus on developing sustainable energy technology. In 2008, Gamesa sold its solar power business, with the aim of focusing (strategically and unwaveringly) on the wind power business alone.

In 2009, Gamesa signed a strategic alliance with Iberdrola Renovables.

At the end of 2011 Gamesa had 8,357 working staff around the world: 920 people working in India, 1,156 in China and 4,853 in Spain /31/. Gamesa’s technical department has expanded rapidly in recent years, and in 2013 it comprised over 600 staff, covering all aspects of wind turbine design and manufacture. Like other European manufacturers, Gamesa lost its market share in 2009 and 2010, as more suppliers from China entered the global market. However, in 2011 Gamesa saw a significant


increase in deliveries compared to the previous two years, which led it to be ranked fourth for annual deliveries in 2011. Gamesa is still strongly influenced by the Spanish market. During 2012 Gamesa dropped to sixth place as a result of the moratorium in Spanish legislation. In 2013 Gamesa has maintained its position due to strong performance in Latin America and India, despite installing only 55 MW in its Spanish home market in 2013 /14/. At the end of 2012 Gamesa was employing approximately 6,650 staff. The commercial presence of the Company included, by that time, 9 sales regions and 23 local offices /33/.

Gamesa’s manufacturing capacity has expanded rapidly as well. It has 22 production centres worldwide. Most of these are in Spain, but there are also manufacturing facilities in other countries, including in the United States, India, Portugal and China. Gamesa Manufacturing Business Units are located in Spain, Brazil, China, the USA and India. In Spain, there are 17 manufacturing facilities. Gamesa has a blade factory in Navarra, Castilla-La Mancha, Galicia and Castilla y Leon. Towers are manufactured in Aragon, Andalusia, Asturias and Navarra. The assembly plants of nacelles are located in Castilla y Leon and Aragon.

Gamesa has been one of the top five manufacturers for more than 10 years. Gamesa was the seventh manufacturer, in terms of installed capacity per year, for 2013.

Gamesa has developed, built and commissioned over 244 MW in Mexico, and another 70 MW are currently undergoing construction. Gamesa currently has a large pipeline which is at varying stages of development. It has also installed almost 1,360 MW of its turbines and is maintaining over 1,000 MW. The Gamesa Regional Operations Center (CRO) for the wind farm is located in Mexico. In addition to the local wind farms, the Center comprises the Operation and Maintenance of G5X and G8X wind farms located in Costa Rica, Honduras and the Dominic Republic.

The cumulative installed capacity of Gamesa turbines up to the end of 2013 is presented in the following Figure:

Figure 4–1: Annual capacity of Gamesa wind turbines

Source: Navigant Research, World Market Update 2013

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

0

5

10

15

20

25

30

35

2003 2005 2007 2009 2011 2013 Inst

alle

d C

apac

ity

per

yea

r (G

W)

Cu

mu

lati

ve I

nst

alle

d C

apac

ity

(GW

)

Cumulative Installed Capacity (GW)Installed Capacity per year (GW)


4.2 Current turbine range

The current offering of Gamesa turbines (60 Hz versions) is presented in the following table.

Table 4–1: Summary description of the Gamesa turbines

Platform Turbine Rated Power [kW]

Rotor Diam. [m]

G5X-850 kW G52 850 52

G58 850 58

G9X-2.0 MW

G80 2000 80

G87 2000 87

G90 2000 90

G97 2000 97

G114 2000 114

G10X-4.5 MW G128 4500 128

G136 4500 136

Gamesa has also developed the G11X 5.0 MW turbine for the offshore market, which is already available, according to the manufacturer.

The G52 was developed in conjunction with Vestas, and is similar in design to the V52, the first Vestas turbine to incorporate variable speed technology using a doubly-fed induction generator. The G58 is a development of this model, but it is designed for lower wind speed sites. The development of the G52 was an initiative carried out exclusively by Gamesa.

At the megawatt scale, in 2000/2001 Gamesa manufactured four versions of the G66-1.65 MW turbine, based on the Vestas V66. This turbine is no longer manufactured.

Gamesa installed the first G80 turbine in October 2002 at La Plana, Zaragoza. The first prototype was very similar to the Vestas V80 but it was later modified to include design changes incorporated by Gamesa. The turbine was originally developed under a licence agreement with Vestas, which was terminated in 2003. A number of the components used in the turbine, specifically the blades and the gearbox, were considered to be Vestas’ core technology. Previously Vestas had not provided full design details for these components to Gamesa, meaning that Gamesa had to develop in-house expertise in a relatively short time frame. Gamesa launched the G9X-2.0 MW line in 2010, incorporating models G80, G87, G90, G94, G97 and G114, with upgrades for different kinds of sites.

The G5X, the G9X and the new G10X series of wind turbines comprise the current Gamesa product line. The G5X turbines (the G52 and G58) are rated between 800 kW and 850 kW. As shown in Figure 4–2 which breaks down the worldwide installation of Gamesa turbines by model, the G5X platform represents a significant portion of the overall Gamesa fleet. Even though the G9X platform comprises the bulk of new installations, the G5X is still produced in large numbers.

The G9X platform represents approximately 52% of Gamesa´s total turbine installations (12,522 MW). Considering that blade designs are the primary differences between the G9X 2.0MW Platform turbines and over 12.5 GW installed worldwide, Gamesa can be said to have considerable experience with the G9X platform /33/.


The first prototype of the G97 2.0MW 50Hz version was erected in Navarra (Spain) in July 2011, and the second was erected in Colorado (United States of America). According to the manufacturer, the first commercial G97 wind turbine has now been installed in Baitugang in China.

The figure below presents the historical installations of Gamesa turbines.

Figure 4–2: Installations of the current Gamesa product range (Q2 2014)

Source: Gamesa June 2014

In April 2009, Gamesa installed the first generation of active power prototype version of its forthcoming turbine series: the G10x 4.5 MW. On 14 June 2010, the Innoblades with a final rotor configuration of 128 m were installed on the prototype (Version B). In March 2011, the G10x 4.5 MW established a record for energy production of a wind turbine in a single day in Spain, with 95.19 MWh. In Mexico 1,360 MW are installed, according to information provided by Gamesa.

4.3 Gamesa G9X-2.0 MW

The Gamesa G9X series is a 2.0 MW pitch regulated wind turbine which includes an Ingecon-W control system that enables the turbine to operate with variable rotor speed over a range of ±30 % of nominal speed. The Ingecon–W system consists of an asynchronous generator with wound rotor, slip rings and two 4-quadrant converters with IGBT switches connected to the rotor. This configuration is common to all Gamesa turbines, including the G47 and G52.

G9X is the natural evolution of the G8X platform. The design concept is exactly the same for both platforms, but the technology since the design of the first G80 has allowed for bigger rotor diameters with the same IEC conditions, which take advantage of lower wind sites. Both series´ are 2MW turbines.

There are a number of variants on the G9X that are optimised for either specific climatic conditions or specific markets, as follows:

G80, 2.0MW

4840

5357

1339

29583128

608

2 0 19 1 0 1 00

1000

2000

3000

4000

5000

6000

G52 G58 G80 G87 G90 G97 G114 G114 G128 G128 G132 G128OFS

G132OFS

Inst

alle

d w

ind

tu

rbin

es


G87, 2.0 MW

G90, 2.0 MW

G97, 2.0 MW

G114, 2.0 MW

The variants are optimised for different wind climates. The G80 is a high wind turbine, G87 is a medium wind turbine and the G90 and G97 are optimised for a low wind climate. All variants may be considered as one design, the G9X. The most significant difference between each variant is the blade design. A further variant, the G80 1.8 MW, has a limited slip drive train that is similar to the Vestas “Optislip” system, in order to circumvent patent restriction in North America.

The G80 is similar in design to the Vestas V80 turbine. At the end of 2001 Vestas provided Gamesa with a licence to manufacture the turbine and to provide technical support for a period of, nominally, two years. The Gamesa turbine uses a number of major components, including the power conversion system which is sourced from alternative suppliers. Upon expiry of the 2-year licence agreement, Gamesa retained the right to use the design and all engineering aspects are now supported by Gamesa.

DNV GL has been informed by Gamesa that the G9X 2.0 MW Platform has been upgraded to maximize the availability programme (GPA). The installed G9X wind turbines will be progressively updated with these adjustments, and the newly manufactured wind turbines (including the Gamesa G80/G87) will bring the retrofits implemented by defect.

4.3.1 General Description of Turbine

The G80/G87-2.0 MW is a three-bladed, upwind, variable-pitch, variable-speed wind turbine. A cutaway view of the G80/G87-2.0 MW turbine is depicted in Figure 4-3. The G80/G87-2.0 MW design is relatively conventional, but it also has distinguishing aspects, including the use of two main shaft bearings and carbon fibre in the blades to be supplied by Gamesa.

Figure 4-3: Cutaway of the G80/G87-2.0 MW


The main characteristics of the G80/G87 turbine are summarised in Table 4-2:

Table 4-2: Summary description of the Gamesa G80 turbine

Item G80-2.0 MW Hub height 67, 78 and 100 m Rotor diameter 80 m Rated power 2,000 kW IEC Classification IA (60m, 67 m, 78 m and

100 m) Nº of rotor blades 3 Rotor orientation Upwind Rotor tilt 6 Rotor coning 2 Power regulation Blade pitching Rotational speed 9.0 – 18.9 rpm Blades – Supplier Gamesa 39 m Generator – Supplier (60 Hz)

Cantarey Reinosa, S.A., CR20 2040kW

Gearbox – Supplier (60 Hz) Hansen, EH 802 FN21 1:101.02 (50 Hz) / 1:120.31

(60Hz) Bosch Rexroth, GPV 442 S

1:100.53 (50 Hz) / 1:120.81 (60 Hz)

Tower Conical tubular / 100m Concrete 4.3.2 Turbine technology

The general concept of the G9X Platform is based on proven technologies in the wind industry. Regarding the G80/G87 wind turbine and the G9X Platform, a comparison of key design elements with the industry standard is presented in the following table.

Table 4-3: Key design elements and industry standard

Component / Process

Assessment Comments

Blade design Proven Similar to the widely deployed G9X turbines Pitch system Proven Hydraulic, typical of the industry standard Drivetrain Proven Traditional configuration Power conditioning

Proven Partial conversion, as is required for DFIG generators

Yaw system Proven 4 electric geared yaw drives, plus hydraulic brakes 4.3.3 Turbine technical assessment

Certification Status Three design classes are typically used internationally for the purposes of certification: Class I, Class II and Class III of the International Electrotechnical Committee's standard IEC 61400-1. Class I is the most severe, with a mean wind speed of 10 m/s, Class II requires a mean wind speed of 8.5 m/s to be considered, and Class III requires a mean wind speed of 7.5 m/s.


The type certification scheme, according to standard IEC 61400-22, is divided into four modules that are mandatory and three modules that are optional. It is possible to obtain certification for each of these modules.

GH GL has been provided with the following GL certificates for the G80 wind turbine:

Statement of Compliance. WT 00-019A-2003, Revision 3. Design Assessment of Gamesa G80-2.0 MW 50/60 Hz. Signed in Hamburg on 30 June 2005.

Type Certificate. TC-GL-025A-2007, Revision 3. Gamesa G80-2.0MW IEC IA 50Hz/60Hz. Signed in Hamburg on 11 January 2009. Valid until January 11, 2011.

Statement of Compliance. DAA-GL-016-2008, Revision 1. A-Design Assessment of Gamesa G80-2.0MW IE CIA 50Hz/60Hz. Signed in Hamburg on 19 December 2008.

Statement of Compliance. PT-GL-005-2008. For Prototype Testing of Gamesa G80-2.0MW 50Hz/60Hz. Signed in Hamburg on 1 November 2008.

Statement of Compliance. IPE-GL-005-2008. For the Implementation of the design-related requirements in Production and Erection (IPE) of the Gamesa G80-2.0MW 50/60Hz wind turbine. Signed in Hamburg on1 November 2008.

Type Certificate. TC-GL-025A-2007, Revision 4. Gamesa G80-2.0MW IEC IA 50Hz/60Hz. Signed in Hamburg on 1 November 2010. Valid until October 31 2012.

Table 4-4: Certification status

Focus Comment G80-2MW Comment G87-2.0MW Statement of Compliance (SoC) by

DNV GL DNV GL

SoC date 2005-06-30 2005-09-26 Standards IEC 61400-1 edition 2 IEC 61400-1 edition 2 Class IA IIA Certified hub heights 60, 67 and 78 metres 67 and 78 metres Type Certificate (TC) by DNV GL DNV GL Type Certificate date 2007-11-16 2007-11-16 Standards IEC WT01 IEC WT01 Independent power curve

G80 power curve measured at Piedra Larga I provided. More information in Section 2.3.4.2.

Independent noise DNV GL has not reviewed independent noise studies for the G80 or G87. Nevertheless, as is stated in the reviewed Type Certificate, the noise emissions for both models are in accordance with IEC 61400-11.

Grid code compliance This section addresses the G80/G87’s ability to meet typical industry interconnection requirements. The primary interconnection technical requirements for wind turbine generators include low voltage ride through (LVRT), reactive power support and power quality. DNV GL is aware that fault ride through capability may be incorporated through an “active crowbar” relay and the oversized converter with brake chopper (BD) /36/.

The active crowbar has a small power converter with power dissipating resistors. The crowbar is electrically connected, in parallel between the rotor slip rings and the rotor side converter. Once the fault current is detected, the Crowbar will short circuit the rotor with resistances that will dissipate the excess in order to safeguard the power converter.


The brake chopper is the other solution for voltage drop support. It differs from the crowbar’s design in that the resistors for dissipating and controlling the rotor energy are installed on the converter’s continuous bus /36/.

Table 4-5 summarises the capabilities of the turbine, with respect to the main grid code requirements.

Table 4-5: Summary of main grid code requirements

Wind Turbine Platform G9X 2.0 MW Power control Capable “active crowbar” required. Set via Scada.

Reactive power provision and power factor regulation

Variable Power Factor: Optional: 0.95 leading to 0.95 lagging for the full range of active power at the rated power and at a +/- 5% nominal

voltage. Standard: from 0.98 capacitive to 0.96 inductive for partial

load, and 1 for rated power Voltage/frequency control Capable

Voltage tolerance +/- 10 % (at low-voltage side) LVRT Capable

Frequency tolerance +/- 3 Hz

The nominal low-voltage grid must lie within the ± 10% range, for continuous operation. Voltage imbalance tolerance is stated as 5% for the MV switchgear and overall turbine.

The Gamesa G9X-2.0 MW platform wind turbines have certificates issued by official institutes on compliance with voltage drops according to P.O.12.3 of REE and EON2003.

DNV GL was informed that the Gamesa G9X-2.0 MW platform is electrically identical to the G8X-2.0 MW platform and, as such, LVRT test data and simulations for the G8X-2.0 were provided in support of the G9X LVRT capability.

DNV GL notes that a project is allowed to comply with the ZVRT requirement by using external equipment (such as a STATCOM, SVC, or DVAR system) which is typically installed in the collection substation. These systems may add costs, compared to the integral turbine dynamic reactive power capability noted in the reactive power discussion below.

The lightning protection system of the G80/G87-2.0 MW turbine is designed to the highest rating available. The lightning protection system of the G80/G87 turbines was designed to IEC 61400-24 lightning protection level (LPL) I and was certified by Germanischer Lloyd according to the IEC 62305-3 standard. Gamesa has advised that it has subsequently upgraded the LPS system.

4.3.4 Turbine project impact

Power curve DNV GL has reviewed an extract of the DNV GL (formally Windtest Iberica S.L.) certification report of the measurement of the wind turbine power curve that was provided by the Customer, /109/ and /110/ (Q&A list dated 3 December 2012). The measurement was carried out from the 2003-10-13 to 2004-06-01 for the G80, and from 2005-05-18 to 2005-08-06 for the G87, with a reference air density of 1.225 kg/m3.

The power curve measurement was compared with the public commercial power curve /111/ & /112/. The power curve is measured from wind speeds of between 1.54 m/s to 14.93 m/s for the G80, and between 1.7 m/s and 23 m/s for the G87.


Compared with the standard power curve provided in the EPC, the G87 measured power curve is below the generated power figures from 7 m/s to 18 m/s. Regarding the G80, the power for 10 m/s and 17 m/s is below the power figure provided in the standard power curve /111/. Nevertheless, the G80 standard power curve /112/ is sustained by the measure power curve /109/. DNV GL recommends carrying out a verification of the power curve warranty at the site. DNV GL notes, however, that the turbulence and general conditions in Oaxaca may be different to the conditions where the studies provided by the Customer where carried out, which could produce differences in turbine performance.

Temperature ranges and extreme weather options The optional low temperature and high temperature packages of the G9X-2.0 MW turbine offer a widened temperature range. Table 4-6 shows Gamesa’s temperature range specifications for the three versions of the G9X-2.0 MW turbine.

Table 4-6: Temperature limits for the G9X-2.0 MW turbine

Standard Low Temperature High Temperature

Specified Certified Specified Certified Specified Certified

Operational Range [°C]

-20 to +30 -10 to +40 -30 to +30 Not Certified

-20 to +40 Not Certified

Stand-Still Range [°C]

-40 to +50 -20 to +50 -40 to +50 Not Certified

-40 to +50 Not Certified

Regarding protection against corrosion, Annex H-1 of the EPC [Phase 1] mentions that towers are equipped with protection C5-I/H outside and C3-H inside (according to ISO 12944-2, this stands for: 5: very high; 3: medium; I: industrial ambient; H: high, more than 15 years). The same annex concludes that turbines are prepared for a humidity of 100% for 10% of the time, and for a humidity of 95% for continuous operation. According to the meteorological data provided, the averaged humidity at the site is around 75%. Therefore, this level of protection is considered adequate for the site.

SCADA Gamesa offers its own WINDNET SCADA system with the turbines. DNV GL is aware, from installations, that the system offers a tool (as is usual in the market) for monitoring, reporting and basic control functions for the wind farm. The installations and remote connection rely on web access through the internet.

At this time, the SCADA cannot provide the level of voltage control required under some grid code requirements. However, DNV GL was advised that this is being developed and should now be available, although this has not been confirmed.

The SCADA allows for integration of the reactive power compensation equipment and managing of the predictive maintenance with Gamesa PMS. Gamesa allows the integration of different modules: active power limitation, reactive power control, frequency regulation, customised report generation, wake control, noise control, shade control and ice control module.

Condition monitoring The condition monitoring system is installed to monitor key drivetrain components using accelerometers (three in the gearbox, two in the generator) and it is designed to identify potential failures before they


result in costly, catastrophic failures. Gamesa refers to the system as its Predictive Maintenance System, or (more commonly) the “SMP-8C” /35/, where 8C means that up to 8 data channels are available.

Gamesa has provided DNV GL with some information on the SMP-8C. SMP-8C data are examined every six months by Gamesa specialists; Gamesa has one employee in the USA, as well as a team of employees in Spain, dedicated to this task. Expert analysis, coupled with significant experience with the components being monitored, is critical to the effectiveness of condition monitoring. Gamesa offers this service as standard during the turbine warranty period, and as an option for the remaining life of the turbine. If a possible defect is detected, Gamesa will inform the project and recommend an inspection. In some cases, the SMP data very clearly point to a defect; in these cases, a repair may be recommended directly, without the need for inspection.

During the site visit DNV GL was informed by the O&M staff that Demex Phase I uses only 5 channels of the conditioning monitoring system. Although the SMP-8C is provided with 8 channels, the installed system is working as an SMP-5C. The SMP-5C is an older version of the conditioning monitoring system. The main difference between the SMP-5C and SMP-8C is the number of channels for measuring vibrations in the power train of the wind turbine. The SMP-5C will provide less data for the analysis and the conclusions will be less accurate than the results provided by the SMP-8C.

According to the information provided in the Q&A list dated 3 December 2012, the turbines are equipped with the SMP-5C monitoring system. Additional information has been provided in the VDR, folder 7.12. However, according to this technical information the SMP would have 8 channels.

DNV GL recommends confirming with Gamesa how many channels are being used in the conditioning monitoring system installed in Demex Phase I, and studying the possibility of installing the other three accelerometers in order to have better data input for the power train analysis.

4.3.5 Turbine historical performance

Turbine track record, known technical issues and availability The Table below presents the track record of the G9X turbine series.

Table 4-7: Track record of the G9X (Gamesa product update: June 2014)

Turbine Units

G80 1,339

G87 2,958

G90 3,128

G97 608

G114 2

The 2 – 2.5 MW series is mainly installed in Spain. The operating conditions in Spain are characterised by high winds and high temperatures; therefore, the operating experience associated with these conditions is substantial. The first G80-2MW was installed in Agualladal (Spain), in 2002. The first G87-2MW was installed in 2004 in Lubián (Spain). These models are widely installed in Spain and have been installed in many other countries as well.

As the design of the predecessor G80 is closely related to the V80, it would be reasonable to assume that some of the problems experienced with this unit will also be experienced by the G80. However,


many of the V80’s problems related to the electrical system are not expected to occur in the G80 since the current G80’s electrical system is procured from an alternative supplier.

Known issues There have been a number of technical problems relating to the 2 – 2.5 MW wind turbines. Gamesa has responded in a professional manner to these problems and has provided appropriate solutions. The solutions have been (where applicable) incorporated into the running production of the 2MW platform turbines. The most important problems are described below:

Hydraulic system

DNV GL is aware of several Gamesa 2 – 2.5 MW series turbines that have experienced leaks in their hydraulic system – both in the nacelle and in the hub. In 2010, the company performed a fleet-wide cleaning, troubleshooting and retraining campaign aimed at resolving this issue. Gamesa has also retrofitted the system, making a change in the leakage circuit. For leakages that do not exceed a specific pressure limit, the leakage will be conducted outside the hub, without using the principal deposit that is located inside the hub and which has a limited volume /15/. Above a specific set pressure value, a seal will break and the leakage will flow into the main tank located inside the hub. Improved sealing has been used in production since 2010. DNV GL recommends verifying whether or not the retrofit was carried out on any of the operational WF.

Pitch system

Damage to the pitch cylinders has caused leaks in the hub /15/. The cause was the shorter than expected lifetime of the internal seal of the pitch cylinders. Gamesa has investigated the root cause of this problem and has upgraded the seals, replaced damaged cylinder rods in the pitch system and modified the maintenance schedule for maintaining the pitch system /16/ & /17/. DNV GL recommends verifying whether the issue was retrofitted in the operational wind farms.

Generator

An issue due to improper tooling and storage practices led to some premature failures in the generator bearing. Gamesa conducted a root cause analysis and implemented corrective actions to address the root cause, including a revised maintenance plan for turbines in storage (ensuring the generators are rotated periodically). Gamesa continues to monitor this issue to assess the effectiveness of its corrective actions.

Gamesa has advised that some generators supplied by Cantarey Reinosa have failed due to short circuits. Gamesa has investigated this and has implemented corrective actions in the field (as needed, or sometimes proactively) and in the factory, in order to eliminate these problems /16/ & /17/. DNV GL understands that Gamesa is monitoring the effectiveness of these modifications.

Main circuit breaker

DNV GL is aware of problems with the main circuit breaker located in the up-tower electrical cabinet of early G8X turbine models. It has been reported to DNV GL that this breaker is prone to early wear-out, resulting in a loss of availability and (in some individual cases) significant downtime. DNV GL understands that Gamesa has addressed the issue, /15/.

Sonic anemometer

Gamesa advised that communication problems during storms led to faults and sometimes to the need for replacement of some sonic anemometers. Internal circuit-board failure was identified as the cause.


Turbine controls were updated to improve communication verifications with the anemometer and, in production, new anemometers with improved protection against electromagnetic interference were introduced in Q2 2010, /16/ & /17/.

Availability

DNV GL became aware that the average availability during the first two years of commercial operation (averaged over a number of relatively small wind farms in Spain) has been below standard industry levels. These figures have revealed individual wind farm availabilities ranging from 80% to 98%. The lowest of these figures is believed to have been related to nacelle overheating, and Gamesa has carried out a number of retrofits to cure this issue. In discussion with Gamesa, DNV GL has been advised that performance improvement has been achieved through a formal reliability improvement programme which was implemented on a fleet-wide basis. All improvements implemented on a retrofit basis will also be incorporated into new designs.

DNV GL has also received availability figures for the first quarter of year 2011 and 2012, /25/ and /26/. The figures indicate that the Platform availability is over 98%. It should be noted that these figures have not been reviewed by an independent organisation. During the course of its other work, DNV GL has seen some operational data regarding the Gamesa G90 wind turbine in the Spanish market. The operational data indicate that the turbines tend to comply with the 97% level.

Gamesa has relevant experience with the 2 – 2.5 MW Platform. Therefore, even if some of the aforementioned issues are affecting the wind farm, the ultimate solution to all these is well known to Gamesa. As these technology issues can be solved by Gamesa, DNV GL would not consider them to constitute a future potential risk for the project.

4.3.6 Conclusions

The G87 and G80 models are considered “proven” wind turbines in the Spanish market (for additional information on the definition of commercially proven technology, see /18/). The series has been used extensively in the world market.

The turbine series is effectively based on the Vestas V80 design. Gamesa has always used different suppliers for the electrical system. Gamesa has developed the original design into a number of variants, primarily to optimise the design for different wind climates. It has also addressed the public issues that have arisen in operation.

The Gamesa G80/G87-2 MW, with hub heights of 67, 78, and 100 m and 50/60 Hz, obtained the Statement of Compliance and valid Type Certificate in accordance with Class IA & IIA IEC 61400-1 ed. 2:1999 and IEC61400-22 conditions /29/, which provides comfort that significant structural design issues and performance issues are unlikely. DNV GL is comfortable with this technology.

There have been no significant type failures associated with the G9X turbines, but availability at the start of this turbine model’s operation (2004 - 2005) was lower than the better performing turbines, including earlier Gamesa designs. In discussion with Gamesa, DNV GL has been advised that the performance improvement has been achieved through a formal reliability improvement programme which was implemented on a fleet-wide basis. All improvements implemented on a retrofit basis will also be incorporated into all the G9X designs, including the Gamesa G80/G87 wind turbine.


The G80/G87 forms the basis of the G9X series. The G80 and G87 have several years of operational experience, and a significant number of these wind turbine models have already been installed. The main difference between the Gamesa G87 and the G80 is blade size.

The G80 turbines installed in Piedra Larga all have retrofits installed. The nacelle is the new G9X platform. The differences between the new and old configurations are as follows:

Improvements in the converter and top control cabinet

Improvements in the generator

New arrangements of the hydraulic system

Improvements in the yaw system

Improvements in coupling

Pitch hydraulic system

Transformer

Measurement instruments

Other

As verified during the site visit, the SCADA installed in Phase I is the SGIPE system. WindNet is the new version of the SGIPE system and the main difference between the old and new versions is that the interface is friendlier for new users. WindNet has an SMS information system allowing for communication of turbine issues to the users. Some modules are integrated by default in the new version, such as: the report generator, management of the preventive monitoring system, the ice control module, etc.

Regarding the reactive power capability of the wind turbines, this is 0.95 inductive - 0.95 capacitive. According to the EPC, a 0.95 power factor must be provided both at the wind turbine generator connection and at the wind farm interconnection point. The last one (0.95 power factor at the connection point) is the requirement set by CFE. Also, Gamesa guarantees that the wind turbine will work with Cos(fi)>=0.95, meeting the requirements described by the Mexican network code. This is reviewed in detail in Annex II of this report.


5 EPC AGREEMENT

DNV GL has performed a contract review of the turnkey EPC construction contracts of the wind farms in the Piedra Larga Project, comprising a total of 227.5 MW, split into two phases of 90 MW (Demex I) and 137.5 MW (Demex II).

DNV GL has been provided with the following documents:

Signed version of the EPC contract, Phases I and II of “Piedra Larga” wind farm of 227.5 MW, between Desarrollos Eólicos Mexicanos de Oaxaca 1 (DEMEX 1) and GESA Eólica México (GESA). Document 5.2.3, Phases 1 and 2 EPC Agreement, Annex D: Turnkey Supply Agreement, dated 23 December 2009 /47/

Completed Annexes A to Z of Phases 1 and 2 of the EPC Agreement /48/

Signed version of the EPC contract for Phase 1 of the “Piedra Larga” wind farm, of 90 MW, between Desarrollos Eólicos Mexicanos de Oaxaca 1 (DEMEX 1) and GESA Eólica México (GESA). Document 5.2.4, Phase 1 EPC Agreement, Annex D: Turnkey Supply Agreement, dated 26 November 2010 /49/

Completed Annex A to Z of Phase I of the EPC Agreement /50/

DNV GL notes that the contractual structure of the two phases of the wind farm was originally developed under the same frame contract, signed on 23 December 2009 /47/. Based on this contract, which covers both phases, a separate EPC contract has been signed for Phase I of 90 MW /48/ (Demex I), already in operation. A second EPC contract was signed for Phase II /113/.

It is noted that the frame contract signed in 2009 /47/ includes two clauses (5 and 6), with a precedent condition for execution of the EPC contract for each of the phases, related to the Financial Close Date of each phase. In this regard, the ultimate financial closing dates for each phase are 30 September 2010 for Phase I and 30 April 2011 for Phase II. If this condition is not met by these dates, the parties are not liable for the EPC contract for each phase, only for works prior to financial close (included in Annex N), such as geotechnical studies, foundation design, substation engineering and main equipment orders. In summary, if the financing deadlines for the two phases are not attained by those dates, the frame EPC contract will not be in force, and the new contracts with Demex 1 /49/ and Demex 2 /113/ will be in force instead.

According to the information provided in the Q&A lists, dated 22 November 2012 and 3 December 2012, a power curve verification test was going to be carried out in two Phase 1 turbines, nº 32 and 33. The results of these tests are discussed in Section 2.3.4.2.

The main findings of the contract review are summarised in the following table:

DNV GL – Report No. 01, Rev.E – www.dnvgl.com Page 52Garrad Hassan Operational Analisys

Table 5-1: Main conditions of the EPC agreement in place with GESA for Piedra Larga Phase I

Wind Farm Piedra Larga Phase I – EPC Agreement Contractor GESA Eólica México S.A. de C.V.

Signature date 26/11/2010

Equipment included (Scope of Works)

The scope of the contract refers to the full equipment for the wind farm, including: 45 Gamesa G80 Class IA wind turbines, SCADA system, BoP (including electrical infrastructures of 34.5 kV), civil works (foundations, platform, internal roads and access), wind farm substation (Demex SET) including the two power transformer positions, control building, MV equipment, and the OHL in 230 kV from Demex substation to the CFE substation of Istepec Potencia (IPO), with capacity for two phases in a double circuit configuration. Also, the works required at the CFE IPO substation for connection of the two phases of the Project are included. If the foundation is not designed by the turbine manufacturer, the manufacturer should approve the design. The Contract Price includes the first two years of O&M of the turbines of the warranty period and the recommended spare parts required during this period, according to Annex S. The spare parts list provided for Phase I includes consumables, minor corrective spares and major components (1 gearbox, 1 generator and 1 set of blades). This is considered acceptable to ensure the warranted availability levels in the contract. The scope clearly states that the Contractor is liable for fulfilment of the environmental resolution statements in the Environmental Impact Statement (MIA) issued by SEMERNAT. Even environmental restoration is included. This is considered to be of key relevance for the Project and duly satisfied in the scope. Also, the scope indicates that the SCADA system should incorporate all the required signals to be transferred to the CENACE control centre from the wind farm control centre, for the wind turbines and for the substation. This is a key factor, considered to be covered in this scope. The scope is considered to be comprehensive, for an EPC contract, and no gaps have been identified.

EPC warranty period

The EPC warranty period is five years after Provisional Acceptance of the wind farm, as stated in Clause 15.3 of the contract. This consists of 2 years of warranty (included in the turbine price) and 3 additional years at the O&M costs included in Annex X of the EPC. The warranty period is considered to be in line with the market for this kind of proven turbine.

Start of warranties

The date for the start of the warranty period is defined as the signature date of the Provisional Acceptance Certificate (PAC, or TOC). If PAC is not achieved due to the Client’s default, several dates are proposed after key milestones have been defined (foreseen in the CAP signature date, start up of turbines, or delivery of turbines to the site). In these cases, Demex 1 may ask for a warranty extension of up to two years after the CAP signature, at the cost of the warranty extension. These conditions are considered acceptable.


Suitability for the site

Annex U-3 /51/ includes a site-specific study from Gamesa, performed by means of the information provided by the Customer about wind resource at the site. The site assessment was conducted in September 2009 for the entire project, at 114 different turbine positions. According to the assessment, the G80 IEC Class IA 67 m hub height turbine is suitable for installation at the given turbine positions of the wind farm, except for 9 positions initialised from met mast 5 where there were no enough wind measurements at that moment to conclude on fatigue loads. This is valid, provided that the wind resource data are reliable and representative of the site conditions. A second site-specific study has been provided /114/. This study concludes that, despite some site characteristics being above Class IA, after having performed a loads study (not provided to DNV GL) the turbines are suitable for the given turbine positions at the wind farm. The coordinates used in /114/ have been confirmed in the letter /122/, which in turn confirms the applicability of the contract warranties for the new layout.

Performance bond

The Contractor provides a Parent Guarantee from Gamesa Eólica S.L.U. as Performance Guarantee of 20% of the Contract Price, split into 15% expiring on the PAC date and 5% expiring early, upon completion of the start-up of turbines. For Demex I, this Performance Bond has been provided according to Annex B. DNV GL considers it positive for the project that GESA is providing a bank guarantee instead of a Parent Company guarantee.

Warranty bond The Contractor provides a Parent Guarantee from Gamesa Eólica S.L.U. during the Warranty Period of 15% of the Contract Price for a period of 25 months after PAC. For Demex I, this Performance Bond has been provided according to Annex BB. DNV GL considers it positive for the Project that GESA is providing a bank guarantee instead of a Parent Company guarantee.

Parent guarantee

The Client shall provide a Parent Guarantee from Renovalia for 20% of the Contract Price. This guarantee is split into three phases, with different expiration dates: 5% until assembly of turbines, 5% until start-up of turbines and 10% until PAC. For Demex I, this Parent Guarantee has been provided according to Annex AA.

Provisional Acceptance Certificate test

The Start up Test and Trial Operation Test is applicable to each individual turbine of the wind farm and for all the turbines stated in Annex L /52/. Once the turbines have satisfied the trial test, the Provisional Acceptance Certificate of the entire wind farm can be signed. The conditions for the 72h individual turbine and SCADA trial test are considered to be acceptable. Also, conditions for the 200h wind farm trial test are considered to be acceptable, with a 97% overall wind farm availability and a 90% individual turbine availability. DNV GL also notes that production at rated power is required for 30h during the test. DNV GL would normally expect the test to include some provision for energy production at a certain capacity factor during the test, but for an operating wind farm this is not considered to be an issue. According to the Contract, PAC will be provided after the tests in Annex L have been satisfied, the punch list defined, and the documentation according to Annex Y has been provided. The list of documentation in Annex Y is comprehensive and includes an “as built” project, O&M manuals, and any further information required for operating the wind farm. DNV GL considers that the conditions stated in the Contract are comprehensive and adequate.


Construction schedule

Annex G includes a contract schedule, which contains the critical construction deadlines. The construction period comprises 13 months, which is considered adequate for the wind farm size. Deadlines are clearly stated and are also considered to be reasonable. Amongst other key milestones are the following:

- Deadline for entire wind farm PAC: 26/11/2011 - Deadline for wind farm COD: .26/11/2011

DNV GL has not received information regarding any formal amendment of the EPC, with regard to the actual construction schedule, including final PAC signature. According to the Q&A (199), it has been explained that the construction delay was caused by both the Client’s delay in obtaining registered land lease agreements, and Force Majeure delay related to torrential rains during the Summer of 2011, which caused GESA to lose the window opportunity for installation in 2011. This explanation seems plausible, and in such a case it is expected that GESA should not pay Delayed LDs to DO1.

Delay warranty and LD’s

Penalties are due if the Provisional Acceptance of the wind farm is delayed from the expected contractual date. There is a chance to agree a grace period of 35 days for the payment of penalties. The penalty is fixed at 0.43% of the Contract Price, per week of delay from signature of the wind farm PAC. LDs will cover the loss of income expected for each turbine/week of delay under a P50 production scenario, and they are therefore considered to be acceptable. The maximum limit is 10% of the EPC Contract Price and this is in line with the market.

General warrantee

Clause 15.4 provides a warranty for: (i) the suitability of turbines for the site, for the given layout; (ii) the suitability of turbines for the seismic conditions; and (iii) the manufacturer certifying the foundation design suitability. DNV GL notes that the layout has been changed, thus the confirmation from Gamesa about the validity of the warranty for the new layout should be included in the Contract. Regarding the seismic conditions and foundation design, DNV GL has not been provided with a specific statement of compliance from a third party, although according to the Q&A (161) Gamesa has conducted the foundation design review internally and a warranty period of 5 years for the civil works is applicable.

Quality warrantee

Clause 15.5 provides a warranty that the equipment and turbines supplied will be in accordance with the Technical Specifications in Annex H. This is considered to be in line with the market.

Equipment and component warranties

Clause 16 states that the warranty period for a replaced part will be the longer of the following: 1 year after repair, or the duration of the parts manufacturer warranty period and the end of the warranty period. For the main components of the wind turbines, in particular, the warranty period for replaced parts will be 2 years from replacement. These conditions are acceptable. The warranty provided for civil works is 5 years after PAC, for hidden defects and execution failures. Design defects are not mentioned, but it is understood to be included as far as the engineering of civil works is included in the scope of works. This warranty period is longer than the market standard.


Availability warranty

During the warranty period, 97% of the annual availability is warranted for the wind farm, and an individual turbine availability of 85% is also provided. This is considered to be in line with the market. Individual availability is defined as follows: (HTOTAL PERIOD – H UNAVIABLE TIME)) / HTOTAL PERIOD Where HTOTAL is the total annual period of 8,760h HUNAVAILABLE TIME, are the hours the turbine is not ready to generate energy, with the following exceptions:

- HV grid and power transformers are out of service - Preventive maintenance of up to 48h/wtg year - Preventive maintenance of the substation equipment up to 8h/year - Cable untwisting - Climatic conditions beyond the turbines’ technical specifications (for wind speed, temperature, etc.) - Grid conditions outside of CRE specifications - Force Majeure time - Stoppage ordered by, or damage caused by, the Client or its subcontractors - Time from the moment that any of the above-mentioned failures occurs until the turbines are re-started. To avoid

future discussion on the turbines’ resetting or re-starting capabilities, it is a good practice to agree beforehand, with the Client, the operating events in which it is expected that the turbines will be required to undergo a manual re-start after any given event. This is also mentioned in the O&M agreement.

- In case of turbine internal failure, any period of Force Majeure that could delay repair would be discounted. DNV GL understands that this may refer to the H&S conditions for repair works, such as high winds. This is acceptable, provided that the maintenance contractor is able to carry out the repair works and the only thing delaying those works is the Force Majeure event. Given the high wind conditions at the site, DNV GL recommends that the wind speed at which repair works can be undertaken is defined in the Contract.

The definition provided for calculation of turbine availability (and therefore for wind farm availability) is considered to be in line with the market and any exceptions made to the unavailable hours are acceptable, except for the comments made above. In addition, DNV GL considers that, for the definition provided, the unavailability due to the MV equipment is also accounted for in the formula, which is considered better than the standard.

Availability LDs

LDs will cover loss of income due to availability that is below the warranted level. Apart from this, the Contract does not provide a formula for calculating this value. DNV GL considers this definition acceptable, as it covers 100% of the loss of income caused. The maximum limit of 10% of the EPC Contract Price is in line with the market.


Power curve warranty

The Contract provides a warranty of 95% of the warranted power curve. This level of warranty is considered to be in line with the market. The warranted power curve is provided in Annex U-25, for an air density of 1.17kg/m3, and site turbulence intensity. DNV GL has obtained a different air density for the site, based on the site measurement;, the DNV GL value of 1.15kg/m3 has been used for energy calculation. The methodology for the power curve measurement is provided in Annex H-3; this is the standard process that Gamesa offers for its power curve verification, based on an IEC-61400-12-1 power curve measurement. In general terms, the process described in Annex H-3 conforms to industry practice for power curve measurement; however, DNV GL understands that the provision for conducting a final power curve measurement at a flat site by dismantling the turbines (clause 7) is not in line with market practice.

Power curve LDs

If, at the end, the measured power curve does not fulfil the power curve warranty, the following LDs are paid: 1% of the Contract Price for each 1% of the measured power curve that is below the warranted value of the warranted power curve. LDs cover the expected loss of income due to power curve underperformance - equivalent to a period of 7 years. This is considered to be acceptable. The maximum limit of 10% of the EPC price is considered to be in line with the market.

Grid code compliance warranty

According to Annex Q – Applicable Grid Code, in particular, it is mentioned that the turbines can operate within the power factor limits of 0.95 at the connection point, which will fulfil the low voltage dips regulation, and they are able to operate within the frequency and voltage limits stated in the Grid Code. This is considered to be acceptable. DNV GL does not foresee any major issues with the G80 turbines in fulfilling the applicable grid code.

Power factor LDs

In case of power factor non-fulfilment, the contractor will pay the loss of income derived for disconnection of the wind farm from SEN, ordered by CENACE, to the Client. Loss of income will be calculated as the non-generated energy during disconnection, multiplied by the energy price of the period. This condition is considered to be acceptable, but the Contract does not provide a method for calculating the non-generated energy and this could cause potential discrepancies. The maximum limit of 10% of the EPC price is considered to be in line with the market.

Efficiency non-compliance LDs

The contractor is liable for the level of electrical efficiency provided in Annex U of the tender process; this is 97.2% for Demex I (96.6% for Demex II according to /47/), for electrical losses up to the connection point at CFE’s IPO substation. The Contract provides that the Contractor will pay the difference between the theoretical energy delivered at the connection point and the actual energy delivered at the same point, in case the electrical efficiency is lower than that warranted. The maximum limit for LDs is 10% of the Contract Price. DNV GL notes that the mechanism provided is ambiguous and that a proper definition should have been provided, based on the metering equipment on both sides of the line and that used for turbine energy measurement, although the varying accuracy of each metering device will incorporate an uncertainty level that has not been accounted for.

Noise warranty No specific noise warranty has been included in the Contract. However, the Contractor is liable for fulfilment of the SEMARNAT provision in the MIA, wherein noise provisions according to applicable law are normally provided.


Maximum LDs limit for each warranty

Availability: 10% of the Contract Price during the Warranty Period Power curve: 10% of the Contract Price in a single payment Power factor: 10% of the Contract Price during the Warranty Period Electrical Efficiency: 10% of the Contract Price during the Warranty Period Other warranties (grid code, noise level): 10% of the Contract Price during the Warranty Period These limits are considered to be in line with the market and acceptable.

Overall LDs limit

15% of the EPC contract. This is in line with the market and is acceptable.

Warranty limits

Warranty limits in the EPC Contract are acceptable, however DNV GL makes the following comments: - In the event that protection of the turbines’ electronic equipment requires checking and manual reconnection, and

considering that this type of stop depends on the quality of the network and the wind farm type, GESA and the client agree to develop a methodology for the consideration of reset time within the availability calculations, except for the reconnection reasons in Clause 15.6. To avoid future discussion on the turbines’ resetting or re-starting capabilities, it is good practice to agree beforehand with the Client the operating events in which it is expected that the turbines will required to undergo manual re-starting after any given event.

- Use by the Client of the wind turbines outside of the conditions detailed in the technical specifications given to Demex as part of the documentation: it should be confirmed that site conditions do not exceed the IEC Class IA conditions for turbine design. DNV GL has received the final Site Suitability Assessment for Phase 1 of Piedra Larga from GESA, showing the definitive layout, which is not part of the Contract. Confirmation from Gamesa of the warranty for the new layout stated in Clause 15.4 has not been provided.

- Network conditions are outside the limits established in the CFE code, including low voltage dips and energy quality. - An excessive number of overvoltage events (more than 52) have been produced by the network. DNV GL notes that

the overvoltage level has not been defined. Also, turbines should stay connected to the grid under the Grid Code voltage limits, so it is understood that either these limits are beyond the CFE grid code, or this condition refers to “grid outages” as stated in the turbine technical specifications. This understanding has not been confirmed.

EPC Price

Turbines: 65,944,589.33€ and 17,750,000 USD BoP, SET, OHL, CFE SET modification: 53,138,128 USD According to Annex I - Total EPC: 65,944,589.33€ and 70,888,128.65USD. This led to to 1,310 €/kW or 1,787 USD/kW installed (at the November 2010 exchange rate). These installation costs are below the average CAPEX price expected for the market.


6 OPERATIONS AND MAINTENANCE AGREEMENT

DNV GL has been provided with the following O&M documents:

O&M Agreement for Desarrollos Eólicos Mexicanos de Oaxaca 1, S.A. de C.V and GESA Eólica de México S.A de C.V (Anexo X. Contrato de Operación y mantenimiento del Parque Eólico con posterioridad Periodo de Garantía; Rev. 6/ 26 de noviembre de 2010), dated 26 November 2010 (signed versión) /53/

Annex A: Monthly report template

Annex B: Permanent installations at the site, provided by Demex

Annex C: A list of spare parts. DNV GL notes that the list provided does not contain the hourly rates, thus it is not clear if this list is the Annex C that is intended for addition to the Contract

Annex D: Operation and Maintenance Manual. DNV GL notes that only the Maintenance Plan has been provided (Gamesa document: DM001754, dated 08/06/2010)

Annex E: Annex I of the supply contract, with O&M prices for the whole Project.

Addendum to “Anexo X. Contrato de Operación y mantenimiento del Parque Eólico Piedra Larga I con posterioridad Periodo Garantía, Rev.6”, dated 30 June 2015 /131/

The main comments from the review of these documents are provided in summary format in the tables below.


Table 6-1: Main conditions of the O&M agreement in place with Gamesa for Piedra Larga Phase I

Wind farm Piedra Larga, Phase 1 Maintenance contractor GESA Eólica de México S.A de C.V (GESA or GESA Mexico)

Duration Three years, counted from the end of the warranty period (third to fifth year from the beginning of the warranty period). Optionally, the Contract can be extended for years 6 to 10, and 11 to 15, from the beginning of the warranty period.

Start date Upon termination of the warranty period Signature date 26/11/2010 and further amended in June 2015 Plant part covered by agreement

Wind turbines (45 units, G80-2 MW, 67 m HH), electrical infrastructure and civil works.

Storage room

To be provided by Demex. According to Annex B (see also Clause 6), Demex will provide the substation control building for Phase 1, including the following premises:

- Control room - Control and remote control room - Workshop/store - Waste store room


Scope of O&M contracts

The scope of all the maintenance contracts includes the following: i) Operation of the wind turbines and their switchgear cabinets ii) Remote monitoring of the wind turbines iii) Preventive maintenance of the wind turbines and their transformer centres iv) Corrective maintenance of turbines v) Inspection and maintenance of blades vi) Preventive and corrective maintenance of the medium-voltage collector system and transformer substation vii) Service parts and consumables viii) All tools and lifting systems ix) Monthly reports

It should be noted that the operation and maintenance manuals for turbines and electrical installations are not attached to the Contract (Annex D). Service parts are included in the maintenance price (with the exceptions mentioned in the rows below). According to Clause 4.1.1, GESA is responsible for maintaining the spare parts at the site. Service parts are the property of GESA, until these are installed on the turbines. GESA is committed to ensuring the availability of supply and spare parts during the 20-year life of the wind farm. This is considered to be positive but this cannot be considered a warranty for the project, as far as this is not supported in an escrow agreement.

Predictive maintenance Predictive maintenance is not included in the contract scope.

Turbine scheduled maintenance

The scheduled maintenance of the wind turbines and medium voltage switchgear cabinet is included. Meteorological met masts are also included. The scheduled maintenance will be undertaken every 6 months (approximate dates), with a maximum deviation of one month from the Maintenance Plan. The scope of the preventive maintenance servicing is attached as Annex D. According to Clause 4.1.2, GESA shall provide Demex with a Scheduled Maintenance Plan two months before the Services start to be provided; DNV GL understands that the plan should be provided before the warranty period starts, but it was not provided for review. The duration of the estimated preventive maintenance per turbine has been provided for the availability calculation, and it has been estimated as 48 hours per year. GESA will avoid the high wind seasons, based on the predictions provided by Demex. Labour, allowances, tools, cranes, vehicles, spare parts, consumables, etc., will be provided by GESA.

Blades scheduled maintenance

Scheduled maintenance is to be carried out in the 1st and 3rd year of the O&M Contract. This maintenance includes: blade inspection; cracks, holes and minor defects repair, without dismantling the blades; and surface cleaning, without dismantling the blades.


Turbine unscheduled maintenance

The Contract includes repair or replacement of any component of the turbines and MV switchgear cabinets that fails, thereby returning the component to operating condition, and this includes minor and major unscheduled repairs, as follows:

- Minor repairs: tasks that can be undertaken by the GESA technicians at the wind farm and that do not require specialised technicians.

- Main part corrective action: tasks that require specialised technicians and that affect main components, like blades and gearboxes, and their substitution.

Labour (specialised technicians), allowances, tools, cranes, vehicles, spare parts, consumables, etc., will be provided by GESA. Thus, GESA is responsible for any equipment damage caused by malfunction or faults that are inherent in the operation of the equipment. Faults attendance time limit: if a wind turbine stops, GESA must respond to the incident within a maximum of 10 hours if it occurs on a working day, and within 20 hours if it occurs on a non-working day. DNV GL notes that it would have been beneficial to decrease the response time outside of the normal working period to a maximum of 14h. DNV GL considers that these conditions, together with the availability warranty, are acceptable to guarantee suitable and effective attention to any faults in the turbines or other equipment.

BoP scheduled maintenance

The BoP scheduled maintenance will be undertaken by GESA, under a “spare parts not included” modality. The following tasks are included:

- MV network, earthing and communications maintenance: two annual interventions - Substation: two annual interventions (under load) - Substation: inspection to be carried out every three years, including measurements of earthing network, and touch and step

voltages The Sponsor has confirmed /127/ that the scheduled maintenance of the 230 kV overhead line (OHL) from Demex SET to CFE SET is included in the scope of services. Labour, allowances, tools, vehicles, consumables, etc., will be provided by GESA. Spare parts are excluded. Any civil works scheduled maintenance will be considered as corrective (except for the 2-year warranted period). Any corrective action will be carried out after previous acceptance by Demex.

BoP unscheduled maintenance

This will be invoiced separately, according to the price list to be included in Annex C of the O&M contract. Prices will be reviewed every year, based on the INPC (National Index Price). Once the warranty period had expired (the first 2 years), GESA is allowed to subcontract these tasks to any other company.

Reporting

A monthly report is to be issued, 10 days after the end of the month. The report format is included as Annex A of the O&M contract. DNV GL finds the report format to be acceptable. Additionally, GESA can read and note the produced and consumed energy from the “official metering devices” to be supplied to Demex 5 days after the end of the month.


Operation and monitoring

Remote monitoring and operation is to be carried out 24h a day, 7 days a week. Staff are present at the wind farm from 9:00 to 18:00 (Mexico DF time) during weekdays (the normal working period), and from 9:00 to 14:00 on Saturdays. DNV GL notes that the control centre from which the remote monitoring will be carried out has not been defined. Response time in case of failure (corrective maintenance), which does not prevent the turbine from operating: 2 h during the normal working period; outside the normal working period, at the start of the following working day. If a turbine cannot operate, GESA is required to initiate diligence to solve the failure within 10h of the moment when it should have detected the stoppage, during normal working days, and within 20h during non-working periods. DNV GL notes that it would have been beneficial to decrease the response time outside of the normal working period to a maximum of 14h. In general, operational conditions are in line with expectations, and in this regard they are in line with the market.

Additional works To be agreed separately, unless emergency or task costs do not exceed 10,000€. Additional works will be invoiced separately. The “administration prices” and the “spare parts prices list” will be updated and provided every year, in a format that is similar to Annex C.

Demex staff training

Optionally, GESA can provide training for a Demex worker for 20 turbines (thus, for up to a maximum of 2 workers). Demex staff is allowed to work in the turbines during the warranty period.

Spare parts The recommended and stored spare parts will be purchased by Demex only at the end of the warranty period. Until this moment, the spare parts remain under GESA ownership. The recommended spare parts list is included in Annex C of the O&M contract (2009 prices).

General Warranty

GESA warrants that the spare parts will be new and original. However, GESA also indicates that refurbished spare parts can be used in exceptional cases. This is normal practice in the industry and is therefore acceptable. However, it would have been desirable to mention explicitly that the parts used – whether new or refurbished – keep the turbine’s type certificate in force. The contract states that the guarantee of repaired parts shall last for one year. For replaced parts, the guarantee will be 24 months, and for services, 12 months. All warranties will expire 12 months after the end of the contract, thus DNV GL notes that spare parts replaced at the end of the contract will have a limited guarantee period. Normal tear or wear in the turbine components is not covered by the general warranty. These conditions are the market standard, but DNV GL notes that if any failure is caused by normal tear and wear of any parts, this defect is covered by the warranty.

Availability warranty

The turbines warranted annual averaged availability will be 97%. The contract also states a warranted annual individual availability of 85%. It is explicitly mentioned that no availability warranty is given for the substation and high voltage line. Demex will have the right to reject the turbines that do not comply with the above figures after the end of the warranty period. The annual averaged availability (Dm) will be calculated, after the warranty period, by means of the following equation: Dm = ∑Avail.Ai / n And the annual individual availability (Avai.Ai): Avai.Ai = (Total Hours – Lost Hours) / Total Hours The following events, amongst others, will not be accounted for as lost hours:

- High voltage network out of service; MV/HV transformers out of service.


- 48 hours/year for scheduled preventive maintenance, per turbine. - 8 hours/year for the substation scheduled preventive maintenance. - Untwisting cables. - Turbines stopped due to conditions outside of the specifications for the turbines, such as wind speed that is above or below

the cut-in/cut-out limits, temperature outside of the operation conditions, or network conditions outside of the CFE network code.

- Force majeure events. - Turbine switch-on hours, from any of the events mentioned above. To avoid future discussion on the turbines’ resetting or

re-starting capabilities, it is a good practice to agree beforehand, with the Client, the operating events in which it is expected that the turbines will be required to be re-started manually after any given event.

This is the same formula as that provided in the EPC contract; therefore, the same comments are applicable.

Availability LDs and bonus

Liquidated Damages If Dm is below the warranted level (GD, 97%), GESA will pay Demex liquidated damages, calculated as follows: LD = IVE x ((GD/DM) – 1) Where IVE are the yearly incomes generated by the energy sold, in Mexican pesos. The liquidated damages provided in the contract cover the loss of income caused by the lower availability, up to the annual limit, and this is considered acceptable. The limit of this penalty is as follows:

- 10% of the Supply Contract price, during the warranty period. - 30% of the total annual remuneration paid to GESA, during the O&M contract life. This limit is considered lower than the

market limit (for which 50% of annual income is expected). DNV GL notes that no penalty has been stipulated for the warranted annual individual availability (85%). According to the information for the Project, the penalties above will cover the revenue losses down to an approximate availability

level of: - Warranty period: 50%, this is acceptable. - Rest of the term: 92%, this limit is slightly high; in line with the comment above if the LDs limit is increased to 50% of the

availability level, coverage would go down to 89%. Bonus If Dm is above 98%, Demex will pay for any 0.1% above that value - a bonus obtained by means of multiplying the average energy price by the 0.05% of the measured energy. The bonus mechanism can be considered as an incentive for the servicer and the level provided in this contract is considered to be acceptable.


Power factor warranty

The turbines will operate in a continuous way at a power factor that is equal to or higher than 0.95, in compliance with the requirements set out in the active CFE code when the contract was signed. The penalties for non-compliance are equal to the income losses due to the wind farm being disconnected from the network, plus any penalty to be paid by Demex that is imposed by the competent authority. The limit of this penalty is a 15% of the O&M Contract Price. This limit certainly covers a small portion of any lost income that may be caused by a disconnection of the wind farm (around 3% of the estimated annual project income). However, this kind of warranty is not common after the warranty period of two years and it is therefore considered to be acceptable.

LVRT warranty Not included in the O&M agreement.

Warranty limits

According to Clause 7.4 GESA is not, and shall not be, liable for the breach of any warranty caused by, or appearing as a result of, any of the following:

- In the event that the protection of the turbines’ electronic equipment requires checking and manual reconnection, and considering that this type of stopping depends on the quality of the network and the wind farm type, GESA and Demex agree to develop a methodology for consideration of the reset time within the availability calculations, except for the reconnection reasons given in Clause 16.6 of the supply contract. DNV GL notes that this reference should be to Clause 15.6 of the EPC of Phase I, where the definition of availability and its exceptions are included. To avoid future discussion of the turbines’ resetting or re-starting capabilities, it is good practice to agree beforehand with the client the operating events in which it is expected that the turbines will required to undergo a manual re-start, after any given event.

- Use by Demex of the wind turbines outside the conditions detailed in the technical specifications given to Demex as part of the documentation: it should be confirmed that the site conditions do not exceed the IEC Class IA conditions for turbine design. DNV GL considers that the final Site Suitability Assessment for Phase 1 of Piedra Larga, with the definitive layout, should be added to the contract.

- Network conditions outside of the limits established in the CFE code, including low voltage dips and energy quality. - An excessive number of overvoltage events (more than 52), produced by the network: DNV GL notes that the overvoltage

level has not been defined; turbines should stay connected to the grid under the Grid Code voltage limits, so it is understood either that these limits are beyond the CFE grid code or that this condition refers to “grid outages” as stated in the turbine technical specifications. This understanding was not clarified.

GESA also states that the GESA warranties are conditioned so that the wind data supplied by Demex in the Terms of Reference are truthful. It is market practice that warranties are provided under reliable data that has been provided by the Client.

Contractor liability

The maximum liability of the Contractor will not exceed 100% of the total annual remuneration under the O&M contract. DNV GL understands that this limit is not applicable to any spare part replacement or repair obligation under the scope of O&M services. DEMEX is entitled to terminate the Contract if either any individual limit or the overall limit is reached. DNV GL understands that the overall limit is 100% of the annual remuneration.


Price

The price of the services is given in Annex E of the O&M contract (Annex I of the EPC Supply Contract). Further these prices have been revised in the Addendum of 2015. These prices are for 2009 and do not include VAT.

Turbines (Original contract): Turbines (Addendum of 2015) - Year 1-2: included in the Supply Contract costs - Year 1-2: included in the Supply Contract costs - Year 3: 45,650 Euros/WTG.year - Year 3-5: 45,650 Euros/WTG.year - Year 4-5: 55,100 Euros/WTG.year - Year 6-10: 30,700 Euros/WTG.year +

534,008 MXN/WTG.year - Year 6-10: 61,400 Euros/WTG.year Exchange rate 1 EUR=17.394 MXN - Year 11-15: 70,610 Euros/WTG.year 2009 prices

DNV GL notes that the O&M cost prices for a full service contract are considered to be in line with the contract prices for 2009. However, in line with the current market trends for O&M costs, it is expected that the prices for year 6 onwards could be optimised in case of contract extension negotiations.

BoP: - Year 1-2: included in the Supply Contract costs - Year 3-5: 550,000 USD (183,333USD/yr DNV GL understands that this price is for years 3 to 5 and not per year). This is

considered acceptable. Training: - 6 people: 40,000 euros/course

If Demex wishes to extend the contract for a period of 6-10 years, GESA will have the right to verify (once) if the remuneration to be received for the services to be provided, relating to the years of the extension, is a reasonable remuneration that is in accordance with market standards. ”Reasonable remuneration” is defined as the difference between the direct costs and the remuneration, which shall be (as a minimum) 15%. A negotiation period of two months is foreseen in order to agree prices for the extension. This condition is considered beneficial for the servicer and could represent a certain risk for contract extension with the same services provider. However a tender process where competitive bids from other services providers, could help to negotiate the service contract from year 6 with competitive prices. It is noted that the renewal of the contract with Gamesa is optional.

Contract termination

Demex is allowed to terminate the contract if, amongst other things, the following situations occur: - If GESA abandons the execution of the services without cause - If the annual averaged availability is below 90% - The established liquidated damages limit is exceeded.

These above conditions are considered to be in line with the market standard and are therefore acceptable. Assignment and subcontracting

GESA is entitled to subcontract any part of the supplies or services that are committed under the Contract (Clause 12).


7 O&M COST REVIEW

7.1 Current O&M contractual conditions

DNV GL has been provided with the agreement witnessed by DEMEX and GESA Eólica de México for the operation and maintenance of Piedra Larga Phase I and the Addendum signed in June 2015 that modifies the O&M contract prices (see Section 6).

In brief, the agreements refer to “full service” type agreements under which GESA takes on the responsibility for scheduled and unscheduled maintenance works, the supply of spare parts and turbine operation, in exchange of a fixed annual fee. The scope of work covers both the turbines and the BoP, although BoP works refer only to scheduled maintenance.

Annex E of the contracts includes the turbine O&M contract costs for both phases of Piedra Larga. The costs given in the contract for Phase 1 refer to 2009 and will need to be revised annually, in accordance with the Mexican Consumer’s Price Index (INPC). Later in June 2015 the O&M have been amended and prices have been modified. The following table includes the Piedra Larga contractual turbine O&M costs for 2017 for Phase 1, according to the INPC published by the Bank of Mexico.

Table 7-1: Contractual turbine O&M costs updated to Dec 2016

Year of operation

Phase 1 [€/(turbine.yr)] [€/(MW.yr)]

1-2 - - 3-5 58,000 29,000

6-10 82,0001 41,000 1. Considering a ratio of 17.394 MXN/EUR

It is noted that the prices included in Table 7-1 for years 6-10 are not yet confirmed prices. If DEMEX wishes to extend the contract for a period of 6-10, GESA will have the right to verify (once) if the remuneration to be received for the contractual services is a reasonable remuneration that is in accordance with market standards. This reasonable remuneration is defined as the difference between the direct costs and the remuneration, which shall be no less than 15%. A negotiation period of two months is foreseen in order to agree the prices for the extension. Given the uncertainty relating to prices after year 5 of operation, the present O&M agreement can only be regarded as a five-year term agreement.

DNV GL considers that the prices of the O&M agreement for Piedra Larga I were in line with the “full service” contract prices for 2009. However, current trends in more mature markets are showing a noticeable decrease in O&M costs and, in line with this, DNV GL sees room for a reduction in the costs proposed by Gamesa beyond year five.

Apart from turbine maintenance work, the O&M agreement with GESA for Piedra Larga also includes BoP maintenance works. Nevertheless, it is noted that such works include only scheduled maintenance, leaving out both the supply of spare parts and unscheduled maintenance. The following BoP maintenance fees will apply:

Year 1-2: included in the Supply Contract costs

Year 3-5 (DNV GL understands that this price is for years 3 to 5, and not per year):

Piedra Larga I: 550,000 USD @ 2009 prices (213,157 USD/yr @ 2013 prices)


The BoP costs are considered to be in the upper range of costs, but they are still acceptable.

7.2 O&M costs forecast

DNV GL has not received specific information from DEMEX regarding the future scheme of O&M maintenance contracts after expiry of the current O&M agreements. No future project O&M cost estimations have been provided by DEMEX.

In the absence of other information, DNV GL prepared two scenarios for future O&M costs up to the 25th year of operation:

Scenario A, under which it is assumed that the wind turbines will remain under a “full service” type agreement, with a scope of work that is similar to the current agreement with GESA for Piedra Larga I. However it is considered that an independent servicer (ISP) provides such services instead of Gamesa. The offer received as reference for current ISP prices /132/ provides a figure of 869,952 MXN per turbine and year, not including blades in the scope nor BoP. This price is linked to an exchange rate of 22.08 MXN/EUR, this way a figure of 39.4 k€/turbine or 19.7 k€/MW is attained. This is considered as a lower market reference price.

Scenario B, under which it is assumed that after year 5 there will be a change from “full service” type agreements to “limited service” type agreements, which would not cover any major unscheduled maintenance.

The following tables contain the expected future turbine O&M costs under Scenarios A and B for Piedra Larga I:

Table 7-2: Expected future O&M costs under Scenario A (2017 prices)

Year of operation

Expected turbine O&M costs

[€/(MW.yr)] Phase 1

1-2 - 3-5 29,0001

6-10 21,0002

11-15 23,0002

16-20 25,5002

1. Contractual prices according to addendum of 2015 2. Expected costs when considering ISP offered prices for this period /132/ as lower market

reference price.

Table 7-3: Expected future O&M costs under Scenario B (2017 prices)

Year of operation

Expected turbine O&M costs

[€/(MW.yr)] Phase 1

1-2 - 3 29,0001

6-10 16,000 11-15 17,500 16-20 19,000

1. Contractual prices according to addendum of 2015

Below are some additional comments regarding the figures presented in the tables above:


It is assumed, in both scenarios, that the wind turbine operations during the first five years of operation will be undertaken through a “full service” type agreement.

The indicative costs included in the present O&M agreement, following year five of operation, are considered to be above the recent market trends (for mature markets, e.g. Spain, and regarding recent DNV GL experience in the area).

Under Scenario A, it is assumed that DEMEX will be able to renegotiate a reduced price for turbine O&M beyond year six, which will be closer to the costs being offered presently by the market. For that purpose DEMEX has provided a recent proposal from Revergy (ISP) that gives the reference for current prices that can be found in the Mexican market /132/.

A price increase over time has been assumed in both scenarios, as it is expected that the turbines will require additional maintenance in order to deal with increased wear and tear, especially relating to minor components.

The costs provided under Scenario B, beyond year six, are to cover scheduled and minor unscheduled maintenance and the local presence at the wind farm. Unscheduled maintenance for major components is also included considering an additional allowance for that purpose.

Regarding the BoP costs, DNV GL assumes that the scheme included in the current contracts will be maintained throughout the lifetime of the wind farm. This scheme will comprise an O&M contract that includes a fixed quotation for the scheduled Electrical System maintenance and a separate quotation for unscheduled maintenance works, both for the Electrical System and the Civil Works (spare parts and components being charged separately).

Since Phase I and Phase II share the same substation infrastructure, and considering the scope of the O&M contract and BoP maintenance costs for both phases, it is assumed that the substation maintenance is covered under the O&M Phase I agreement, thus Phase II costs are assumed to cover maintenance of the MV system.

Given that the costs reviewed do not include an allowance for unscheduled maintenance for the BoP including any spare part required, DNV GL suggests that a reserve of about 80 kUSD/year must be set for the lifetime of the project, in order to cover unscheduled BoP maintenance and the required spare parts. This reserve will cover the Electrical System and the Civil Works unscheduled maintenance, as well as the required spare parts. The amount of reserve can be fixed at 80 KUSD and may be reviewed and adjusted over the years, considering the actual unscheduled maintenance costs incurred (this amount is not intended to be cumulative, but replaced when used).


8 POWER PURCHASE AGREEMENT DNV GL has reviewed the Power Purchase Agreement between DEMEX I and the several companies of the Bimbo group /54/.

8.1 Object of the contract

The object of the contract is to establish a self-supply structure between the Project and several companies of the Bimbo group. According to this, the Project will make its best effort to close the financing process, to build the wind farm, and to sell the energy to consumers listed in the contract.

The main figures for electrical consumption indicate that the Bimbo group will be consuming at least 90% of the Expected Annual Energy, which is 333 GWh/yr. According to the definitions of the contract, consumers are obliged to consume 90% of this amount (299.47 GWh/yr). Despite this figure, Annex G of the contract, upon which the list of consumers is based, states a final amount of 333 GWh to be consumed. If the consumers do not consume the stated figure, they should demonstrate the reason for non-fulfilment of the target.

The supplier warrants an energy production of 80% of the Expected Annual Energy (266.4 GWh/yr).

8.2 Obligations of the contract

8.2.1 Obligations prior to the Normal Operation Date

The following obligations are defined before the Normal Operation Date:

Two Corporate Guarantees will need to be placed: one from Renovalia Wind International S.L, backing up the Demex Oaxaca 1 compromise, and one from Grupo Bimbo S.A.B. de C.V., backing up consumer obligations. These are attached to the contract as Annexes C and D.

The Normal Operation Date (NOD) must be achieved before, or at least by, the Normal Operation Limit Date (NOLD). This NOLD is defined as 1 September 2011. According to the sixth amendment of the PPA /60/ this date has been delayed until 30 May 2013. According to /93/ the NOD was declared on 1st November 2012. Therefore, no major risk related to the NOLD of the PPA is found.

A wheeling study must be developed.

An interconnection agreement must be signed.

Insurance for civil works, civil responsibility, and resignation to subrogate must be signed.

During the validity period of the contract, Renovalia must have a minimum direct or indirect participation in the Project, representing most of the share capital.

8.2.2 Obligations after the Normal Operation Date

The consumers are obliged to buy the compromised energy, which is 90% of Expected Annual Energy (299.47 GWh/yr). If the consumers consume less energy than is generated from the Project at the interconnection point, the consumers will pay the difference between the selling of this excess energy to CFE or other consumers, as well as what they would have paid as defined in the PPA.


The consumers will provide and maintain their meters in good condition and according to the rules and regulations of the Mexican market. This is a positive aspect for the Project, as so many meters could be a huge cost for the Project.

According to the information provided by the Sponsor (in the Q&A list dated 03 December 2012), despite the NOLD being set on 30 May 2013 (sixth amendment of the PPA /60/), penalties have been paid and some are still pending. DNV GL has not received any information about the nature of these payments.

8.3 Effective period

The effective period will begin on the Normal Operation Date and will last for 15 years. This date is changed in the amendments to the contract, as it is detailed in Section 8.12.2 below, extending the contract duration to 18 years.

8.4 Energy pricing and payment

Supply from the Project to consumers will begin on the Normal Operation Date.

The energy supplied at the load points will be paid by the consumers, on a monthly basis. The price of the energy is determined by the sum of two variables:

The price of the energy (PPA tariff). This is defined in Annex E of the contract. According to this annex, the price is based between the price agreed in 2007 and the Normal Operation Date. The price for December 2007 is 0.7350 MXN/kWh. The formula is as follows:

Where:

is the tariff of the Normal Operation Date

is the tariff agreed on 31 December 2007, 0.7350 MXN/kWh

is the Consumer Price Index, published by the Bank of Mexico on the previous month’s Normal Operation Date

is the Consumer Price Index, published by the Bank of Mexico on 31 December 2007

There will be an update, which will be based on the inflation rate of the last two years and on the following formula:

Where:

is the tariff of the current month

is the tariff of the month before the current one

is the Consumer Price Index, published by the Bank of Mexico the previous month

is the Consumer Price Index, published by the Bank of Mexico two months before the current month


There will be a monthly adjustment to the tariff.

The wheeling costs for the energy delivered from the interconnection point to each of the load points, and other adjustment services that CFE may charge to Demex 1.

The power supplied by the Project will be divided into the load points of the consumers listed in Annex G. If there is a power loss at a certain load point, another one will take the spare power delivered by the Project.

The monthly amount of energy delivered to the load points that is paid to DO1 under the PPA tariff is the sum of the energy generated by the Project in such a month and the shortfall energy banked with excess energy, according to the Interconnection Agreement.

According to Clause 7.1 of PPA, the self-supply consumers must cover the amounts related to the Demand Subject to Invoicing (Demanda Facturable) applied by CFE.

Also, in a certain month the self-supply consumers required Complementary Energy for CFE; this will be invoiced at the CFE tariff.

Finally, the company will transfer to the consumers the amount corresponding to the Self-Supply Power, under the same terms that it receives such an amount from the CFE under the Interconnection Agreement.

Tariff update

If there is a cumulated annual capacity factor beyond 42.24% (thus, generation is over 333GWh/yr), the consumers will have the right to consume the excess energy, but not the obligation. This energy will be priced at the average price of the short-term cost (CTCP), by CFE, and the PPA price of the contract.

The payment will be due in the first fifteen days of the month after the invoiced payment.

8.5 Take or pay clause

There is no former take or pay clause in this contract. According to Clause 5.1 d, the consumers are obliged to take the compromised energy (90% of the expected annual energy). If less than this energy is acquired, the consumers will have to pay the difference, according to Clause 5.1.e.

8.6 New consumers

Any additional consumer must be suggested by the actual consumers and its addition should consider the EAE (Expected Annual Energy). Only subsidiaries of the Bimbo Group may be added to the consumers list. The new consumer should proceed with the administrative proceedings, in order to become a consumer of the Project.

8.7 Energy metering

The energy will be metered at the interconnection point and at the meters of the load points. It is important that the meters at the consumption points are accurately maintained. As this is a responsibility of the consumer, the Project must verify the conditions, either via random inspections or through certificates by CFE.


8.8 Penalties and guarantees

8.8.1 Delay penalty

If the NOD has not been met, the penalty will start to count from the NOLD onwards and the amount will be as follows:

25,000227.5

227.5

This means that, per week, there will be a calculation of the delayed (from becoming operational) MW and per each delayed MW there will be a payment of a pro-rated amount of 25kUSD.

8.8.2 Less than agreed energy supplied

If the Project delivers less than 80% of the Expected Annual Energy, which is 266.4 GWh/yr, it will have to pay the consumers the difference between the following:

The amount of energy paid by the consumers to the additional energy sources from which they have bought the non-provided energy. The limit of this penalty will be the cost of the non-provided energy, as if it had been supplied by the Project.

The amount of energy paid by the consumers to the project, if this had supplied the non-provided energy.

The compromised energy is below the P90 for one year (273.4 GWh/y) and above the P99 (240.2 GWh/y). DNV GL recommends following this issue up in the financial model, with a scenario of several years of PPA penalties.

8.9 Termination of the Contract

8.9.1 Delay on the critical construction dates

According to the definitions in the contract, there are certain dates in the construction process that have been defined as critical. If these dates are not achieved, the penalty will be triggered. These dates are the following:


Table 8-1: Critical construction dates

Event Date 1st Amendment 5th Amendment 6th Amendment

Self-supply permit at CRE

December 2008 December 2008 Done, Dec. 2008

Obtaining of lands and rights for installation of the WF

January 2009 January 2010 Done, Oct. 2010

Application for wheeling study for all the consumers

March 2009 February 2010 -

EPC contract signature

April 2009 September 2010 Signed, Dec. 2009

Obtaining self-supply permit

July 2009 July 2009 Done, Dec. 2009

Interconnection contract signature

July 2009 June 2010 Done, May 2010

Financial close November 2009 December 2010 Expected, July 2011

Construction start November 2009 January 2011 Expected, Dec. 2010

Normal Operation Date Limit

1st September 2011

1st September 2011

Expected, 30th November 2011

30th May 2013

If NOLD (or any other dates from the afore-mentioned table) is not met, the contract can be terminated without any responsibility for the parties. According to /93/, NOD was declared on 1st November 2012.

8.9.2 Breach by the Project

The consumers could issue a termination warning in the following cases:

A termination warning issued by CFE, due to lack of payment by the Project

Naming of a Liquidator for the Project, or for Renovalia

That there are procedures in place for the liquidation of the Project or Renovalia

Due to non-fulfilment of the agreed compensation or payment to the consumers

Any untrue or false declaration by the Project

An abandonment of installation occurs

The NOD is not achieved before or on the NOLD (this is 30 May 2013, according to /60/)

The supplied energy is less than 80% of the AEE, for 3 consecutive years

The corporate guarantee for the Project is no longer in place.

8.9.3 Breach by the consumers

The Project could issue a termination warning in the following cases:


If any consumer decides to quit being consumer of the Project, or no longer has a share capital in the Project

If the consumer is undergoing a liquidation process

Any untrue or false declaration by the Project

The corporate guarantee for the Project is no longer in place

8.9.4 Termination for convenience by the consumers

The consumers may terminate the contract at their own discretion, and without any justified cause. As a consequence of this, the consumers will have to pay one of the following:

1. 0.9 180 1.5

Where:

date from the NOD (in this case, in months)

Expected Annual Energy

TIIE is the interbank interest rate in Mexico

2. The pending amounts for financing the Project from the termination date onwards, plus two years of energy compromised by 0.9 and by the annual agreed tariff.

Although the wind energy is competitive in the Mexican market, and if the consumers of the supply agreement drop it would not be hard for the Project to get new consumers, this compensation would be very favourable for the financial balance of the Project.

8.10 Extension of the contract

The contract can be extended for two additional periods of five years each. The pricing of such an extension will be based on the mechanisms stated in Section 8.4. These extensions will have to be over the complete annual expected energy (333 GWh/yr). This extension should be communicated by the consumers 24 and 12 months before years 15 and 20, respectively.

DNV GL notes that the turbines are designed for a 20-year period; therefore, considerable investment in O&M could be required from year 20 onwards. This should be carefully addressed by the Project, as it might get closer to year 20. According to the Sponsor’s comments, the O&M costs have been indexed to the CPI and carried forward. DNV GL considers this inadequate and recommends that, in order to mitigate this risk, an evaluation of project profitability should be carried out close to year 20.

8.11 Change of law

The change of law is defined as any change that may impact the parts from 50,000USD, per contractual year. Any adjustments in the law that would imply an increase in the pricing will be updated according to the CPI index of the United States of America, from the NOD onwards.

Any change that must be made to the Project because of a change in the law will be communicated to all the relevant parties and implemented. The costs or savings, as a result of this action, will be agreed by the relevant parties.


8.12 Modifications to the PPA

8.12.1 First amendment in July 2009 /55/

The first amendment of the PPA modifies the following clauses and annexes:

The wheeling study will be presented on 1 October 2009, at the latest. According to the first clause, the critical dates for construction and operation are modified, maintaining the NOD. The delay penalty remains unchanged.

8.12.2 Second amendment in February 2010 /56/

The second amendment modifies the following clauses and annexes:

Clause 3. The contract will be valid from its signature until 18 years after the NOD. The first 15 years will be calculated according to Annex E (Section 8.4 of this report). The 3-year extension will be priced the same as for year 15, without any indexation to the price during this period.

The possibility of extending the contract by two periods of 5 years is maintained. Therefore, the life of the wind farm will be extended to year 28. The first period tariff will be the same as for year 18, without indexation. The second period tariff will be adjusted on a monthly basis, according to the CPI in The USA.

Certain modifications regarding the wheeling study are also carried out, but these are considered to be minor.

DNV GL considers that there is a risk of imbalance between the costs of the O&M for the Project and generation for the period between years 20 and 28. The right to extend this period is only on the consumers’ side, so the Project will have to extend the period by assuming the O&M costs (whatever these are). If the Project does not want the period to be extended, the contract will be terminated by the Project and the consequence will be that defined in Section 8.9 of this report. DNV GL considers that this risk should be mitigated by limiting the extension period to 20 years and upon analysis of the project costs, prior to any extension of the self-supply permit.

8.12.3 Third amendment in September 2010 /57/

The third amendment modifies the following clauses and annexes:

Annex F: the delay penalty will be the following:

25,00090

90

Penaltyi is the penalty at a certain week I in USD

, is the capacity at normal operation at week i

8.12.4 Fourth amendment in November 2010 /58/

The fourth amendment modifies the following clauses and annexes:

The Normal Operation Date Limit (NODL) will be 30 November 2011

According to the definitions of “project breach”, the following modification is implemented:


o If the energy delivered is less than the Expected Annual Energy during three consecutive years, due to:

80% only, because of the lack of wind resource 85%, due to causes different to lack of wind 75%, due to lack of wind and to other causes occurring at the same time

The other causes will be those communicated by the Project to the consumers. These causes will need to be duly reported.

In DNV GL’s opinion, the risk associated with contract termination due to non-fulfilment of the annual expected energy levels (above) over three consecutive years is low (according to the energy analysis based on the operational data, the P90 is 275.6 GWh/yr thus above the 80% figure).

8.12.5 Fifth amendment in June 2011 /59/

The fifth amendment modifies the following clauses and annexes:

The definition of “Parties” as constituting the consumers and Project combined is included;

The participation of consumers of the assigned power of the Project is 39.56%;

The defined power of the Project decreases from 227.5 to 90 MW;

No remarkable differences are appreciated in the volume of energy to be generated, or in the compromised energy to be acquired by the consumers;

The wheeling study is missing from the precedent conditions, as the legal framework has changed and the calculation of the wheeling costs has become much easier;

The reports will be issued on a monthly basis, instead of every three months;

There is an agreement for a floor on the acquisition of non-acquired energy. This floor will be at least the tariff agreed for that contractual year. This will be the only compensation if there is a lack of consumption.

8.12.6 Sixth amendment on January 2012 /60/

The sixth amendment modifies the following clauses and annexes:

The NODL is moved to 30 May 2013.


9 PERMITS AND LICENCES

9.1 Open Season description

The infrastructure of the grid in the Isthmus area has been built to hold power from the projects in the First Open Season. The Open Season was a process that started back in 2006. By then several developers were working in the Isthmus area, where only the existing infrastructure for the Juchitán II Substation had already been built. CFE announced the Open Season process, where all the developers were asked about how much power they were going to interconnect to the grid. Once CFE got all the answers, it started to develop technical and economic studies and the final figure of 2 GW appeared as the final amount of wind power to be installed. The list of the involved companies is included in Table 9-1.

Figure 9-1: First Open Season projects and interconnection infrastructure

Source: Open Season documentation


Table 9-1: First Open Season projects

Company MW to be installed Installed WT

Bii Nee Stipa EE 26.35 Yes G52

DEMEX 227.5 90MW in line. Second phase to be connected

in 2013 G80

EVM 67.5 Yes Clipper 89

Eoliatec del Istmo 164 To be connected in 2013 G80

Eoliatec del Pacifico 160 To be connected in 2013 G80

DEMEX 250 Yes AW70

Fuerza Eólica del Istmo 100 50% connected Clipper 89 & 93

Gamesa Energía 288 On course during 2012-2013 Gamesa

Parques Ecológicos de México 80 Yes G52

Preneal de México (Mareña e Istmeña) 395.9 No Vestas V90 3W

Unión Fenosa generación 227.5 No -

TOTAL 1986.75 Source: CRE & DNV GL

The IPP (Independent Power Producers) projects from CFE were not included in this Open Season process. Therefore, La Venta III (Iberdrola), Oaxaca I (ACS) and Oaxaca’s II to IV (Acciona) are not considered. The Iberdrola project is installed with G52’s whilst ACS has V90 2MW and Acciona projects are using AW70 turbines. The total amount of these projects is close to 500MW and they are all under an IPP structure with CFE as the offtaker of their energy.

Under Mexican regulation, there are no restrictions on upwind projects. In some countries, such as Brazil or Spain, there is some protection for the developers who first install the wind farms, but that is not the case in Mexico. DNV GL’s estimation is that the whole open season should be built by 2017. DNV GL is aware of heavy opposition against the Mareña and Istmeña projects that have moved to another position and that consequently have delayed the installation.

The second open season is still ongoing. The most optimistic scenarios foresee installation from 2017 onwards, but DNV GL is not aware of the defined areas for each of the projects. The amount of projects to be installed is close to 1GW.

The main infrastructure that holds the Open Season are the substations of Juchitán II, Ixtepec Potencia (IPO) and Matias Romero Potencia (MRO).


Figure 9-2: Electrical infrastructure that connect the Isthmus area

Source: CFE

This infrastructure is designed and built to be able to integrate generation into the national grid and to transport the energy to the centre of the country, where the main consumption occurs. The interconnection of the new and existing infrastructure takes place in Juile, where the lines coming from the Isthmus area connect at 400kV. As the energy consumption in the south of Mexico is very low, the infrastructure is fully dedicated to transporting the wind energy generated.

The new wind energy to be installed in the area depends on the construction of new interconnection infrastructure (to the centre of the country, running through the mountains), so that the existing infrastructure will not be overloaded.

Considering the aforementioned scenario, the possibility of grid outages is quite low as there is a very strong connection between the generation area and consumption, and the entire infrastructure is new and tailored to wind energy needs. The only scenario that could occur is a major problem in the network at a national level, which has not been experienced so far.

The costs of the grid reinforcements required to evacuate the wind energy generated in the Isthmus area have been borne by the participants of the Open Season. In the first one, the interconnection costs were close to 140 kUSD, per MW installed, whilst the forecasted costs for the Second Open Season are closer to 300 kUSD. CFE is not sharing the cost of this infrastructure, as it is used to simply getting the energy out from the sites and into the grid.

9.2 Interconnection Agreement

DEMEX has signed an Interconnection Contract with CFE. This contract /91/ was signed by CFE and DEMEX on 28 May 2010. A Second Interconnection Agreement has been further signed on 25 September 2012 /92/.


The connection point characteristics are detailed in this contract. In particular, they are included in Annex G-RC and Annex B-RC, which have not been provided to DNV GL. These have not been provided for review.

The aim of the contract /91/ is to authorise the 90 MW of the Demex I Project to connect to the grid and allow it to remain fully operational.

The interconnection point can be changed by CFE (at its own cost, for technical reasons) or by DEMEX, if the change is necessary due to a modification in the source of energy or in the consumption centres.

This contract has a validity of 20 years from 1st November 2011, although the start date for services is declared as 1st November 2012 in notification between CFE and DEMEX /93/. However, it has been confirmed that in the second Interconnection Agreement /92/ the date has been updated to 1st November 2012. Therefore, it can be concluded that the term of the Interconnection Agreement is in line with the start of normal operation of the wind farm.

The events which would terminate the contract are, as follows:

a. If the power plant does not come on-line on 1st May 2012, there will be a single extension of 12 months. According to the Second Agreement signed /92/ this date has been postponed to 1st February 2013, which does not actually represent a risk for the Project, as it had declared normal operation by 1st November 2012

b. Termination by DEMEX, if the permission issued by CRE is cancelled.

c. Termination by DEMEX, after the one-year validity period of this contract.

The methods with which to calculate the energy that DEMEX is going to inject into CFE’s grid are also defined.

Regarding the operation of the wind farm, DEMEX should be coordinated with CENACE (Centro Nacional de Control de Energia) for any operation requirement that the grid operator CENACE should request of the wind farm, in terms of disconnection from or connection to the grid, active or reactive power regulation, or any other requirements according to the wind farm capabilities and grid conditions according to the Grid Operator Code (Reglas de Despacho). This is considered to be in line with the grid operation standard procedures and is considered to be acceptable.

In addition, according to the contract DEMEX should provide the power production estimation to CENACE, under the conditions agreed upon between the parties.

The measurements of energy delivered to the grid will be made at the point closest to that of the delivery of energy (the connection point), which is not defined in the contract but in the Annex B-RC that has not been forwarded to DNV GL. This annex has not been provided for review.

DEMEX must cover the cost of measurement equipment, whether or not that equipment is installed by DEMEX or CFE.

Procedures to regulate the system in case of emergency are established within this agreement.

There may be emergency situations, wherein the wind farm must follow the instructions of CENACE.

Several tariffs are fixed in this agreement; this is in the case that DEMEX sells the energy to CFE instead of to the final customers. These tariffs are as follows:


Energy in emergency situations:

1. Energy which was requested by CFE and supplied by DEMEX; to be paid at 1.5 times the applicable tariff rate for the system.

2. Energy which was not requested by CFE but was supplied by DEMEX; to be paid at 0.9 times the regional short-term total cost of the system.

3. Energy supplied by CFE to the consumption points, but not received by DEMEX; to be paid by DEMEX to CFE, the regional short-term total cost of the system.

Energy during the testing period

1. Energy received by CFE and supplied by DEMEX will be paid at 0.7 times the regional short-term total cost of the system.

Excess, shortage and complementary energy

2. Excess energy sold by DEMEX to CFE will be priced at 0.85 times the regional short-term total cost of the system. This excess energy can be accumulated over a twelve-month period, running from a date agreed between the parties.

3. The excess energy could be used within a month to compensate for any shortage of energy. If, after the twelve-month period, DEMEX still has excess energy, it will be sold to CFE and paid for at the excess energy rate. A maximum of 5% of the excess energy accumulated during this annual period could be banked to be used in the following annual period, instead of being sold to CFE.

4. Shortages of energy will be compensated for in a manner determined by DEMEX. It will be compensated for within the same hourly periods; if it is between different hourly periods, it will be divided by the peak hour factor. Excess and shortage energy can be compensated for within different months, according to a factor of the different hourly periods.

5. Complementary energy is the energy necessary to cover the total energy demand of a final consumer above the energy supply agreed, according to the Interconnection Contract; it cannot be compensated for by using Excess energy. Complementary energy will be sold to the final consumers by the CFE, at the agreed energy tariff.

9.3 Self Supply Permit

The creation of the self-supply society and the Award of Transmission Capacity to the DEMEX self-supply society for 227.5 MW, received from the CRE on 4 June 2009 /94/, are the documents which allow DEMEX to generate and consume the electrical energy from the Project at the designated load points.

In this Project, DEMEX Oaxaca I SA de CV is the so-called self-supply society. It is formed by DEMEX I (the generator) and Renovalia Wind International SL, Grupo Renovalia de Energia, Suburbia, Vips, Corporativo Bimbo, other Bimbo companies and Walmart (the consumers). The consumers should have symbolic shares in the Project, which are designed to fulfil the legal requirements for belonging to the self-supply society.

DEMEX has a list of potential consumers of the energy which will be generated, which are mostly Bimbo and Walmart load points. Although it is typical for this kind of permit, there is no list of potential new customers that DEMEX could include if it were required to do so by the Project.


The key figures within the self-supply permit are that the Project will have up to three-hundred wind turbines, with a total installed capacity of 227.5MW and an estimated production of 933.3 GWh, using 1.5MW turbines.

DEMEX states in this permit that construction works will begin during March 2009 for Phase I and during January 2010 for Phase II, finishing with commissioning of the wind farm in December 2010 for Phase I and June 2011 for Phase II. There has been one amendment to the transmission capacity of DEMEX, as the Project is being developed. This modification is included in the CRE update of the self-supply permit /95/ and it is to delay the start-up and termination dates until 18 October 2011 for Phase I, and until 25 April 2012 for Phase II. According to the information provided by the Sponsor (Q&A list, dated 3 December 2012) modifications to the permits were delivered by CRE (11/July/2012 for Phase I and 27/July/2012 for Phase II), updating the conditions of the Project.

The permit is not of limited duration, but it can be terminated due to the dissolution of the permitted company. The permit may also be cancelled by CRE, due to any of the following occurring:

1. If DEMEX has been selling or reselling electrical energy or capacity. 2. If DEMEX transmits the rights awarded in this permit. 3. If there is any action that seriously and repeatedly breaks some of the dispositions within

the Law of Public Service of Electric Energy, its rulebooks, or any technical and administrative conditions or rules.

DNV GL has received the resolution issued by CFE, dated 27/07/2012, which entitles DO2 to generate electricity in a self-supply mode /96/. The award title describes the conditions under which the permit is provided.

The characteristics and location of the installation comply with the description stated in the permit. The estimated energy yield is set at 508.75GWh.

The energy yield will be supplied to the following shareholders of the company:

Nueva Walmart de Mexico ;

Operadora, S. de R.L. de C.V.; and

Suburbia S. de R.L. de C.V.

The works are estimated to be started in January 2013 and ended in December 2013, the energy cannot be sold or resold under any other terms than those stated in the permit, and any excess energy will be made available to CFE. The wind farm must comply with the Mexican Regulation and the CFE national energy control centre rules.

Amongst other obligations, DO2 must inform CFE of the start of operation date up to 15 days after the wind farm is in operation and provide three-monthly information regarding the amount of energy produced.

The permit is not of limited duration, but it can be terminated due to the dissolution of the permitted company. The permit may also be cancelled by CRE, due to any of the following occurring:

1. DO2 is dissolved 2. CFE revokes the permit:

a. If DO2 has been fined repeatedly for selling or reselling electrical energy or capacity; b. If DO2 transmits the rights awarded in this permit without the approval of CFE; c. If DO2 produces energy under different conditions from those stated in the permit;


d. If there is any action that seriously and repeatedly breaks some of the dispositions within the Law of Public Service of Electric Energy, its rulebooks, or any technical and administrative conditions or rules.

3. If the wind farm works have not started within six months of the estimated start date (January 2013), or the works are suspended except for force majeure reasons.

4. If DO2 renounces the rights under this permit.

9.4 Transmission Agreement with CFE

A Transmission Agreement was signed with CFE on 18 December 2008 /97/ and a subsequent modification was made on 24 September 2009 /98/, with the aim of CFE providing supervisory services and technical support for the construction of the 230 kV overhead line from Demex SET to CFE Istepec Potencia SET.

Basically, this contract includes the conditions for execution by CFE of the supervisory works during the construction of the 230 kV double circuit OHL from SET Demex to CFE IPO, and the detail of the services provided is as follows:

- Management - OHL path selection and topographic works - Basic engineering - Tendering process and proposal evaluation - Selection of final OHL path.

The duration of the services has been modified in the contract modification and it is foreseen that the works last until 24 January 2011.

The total service costs have also been revised in the contract modification, with a total amount of 6,583,203.19$MX.

Rights of way and compensation to affected land owners are the responsibility of the company.

DNV GL understands that this mechanism allows for the construction of the electrical infrastructure in accordance with the CFE regulation; this is stated in the project specifications and it is an advantage if the infrastructure is transferred further to the CFE. Also, for the connection to the grid of wind farms it is required that CFE accepts and certifies the electrical infrastructure.

9.5 Aviation authority permits

A notification from the SCT (Secretaria de Comunicaciones y Transporte, Dirección de Aeronáutica Civil –Aviation Authority-), dated 3 March 2010 /78/, states that the 114 wind turbines to be installed in Piedra Larga shall be marked with some strips on the towers and blades and 46 units shall be equipped with the beacons described. DNV GL notes that the notification provided contains the coordinates for the 114 turbines and considers a maximum height of 107 m (67 m hub height, plus 40 m radius).

DNV GL notes that, since the coordinates of Phase 1 have suffered some minor changes, the permit probably does not match the final coordinates, however these changes are frequent during construction and DNV GL does not see potential risk in this. Further on 07/07/2010 the Sponsor informed SCT of the intention to install only 45 turbines, and that the remaining 69 would be installed under a separate project denominated Demex 2. Finally in March 2013 Demex informs the Aviation Authority of the


installation and start-up of 45 turbines, and that the remaining 69 turbines would be installed at Demex 2.

9.6 Environmental permits

Regarding the environmental aspects, DNV GL has reviewed the following documents from SEMARNAT (Federal Environmental Authority):

- Document S.G.P.A./DGIRA.DG.3901.08, dated 19 December 2008 /79/.

- Document SGPA/DGIRA/DG/2475/10, dated 7 April 2010, modifying the type and number of wind turbines to be installed in Phase 1 (so-called DEMEX II) from 65 turbines of 1,500kW to 45 units of 2 MW /80/.

- Document S.G.P.A/D.G.I.R.A/D.G./5800, dated 2 August 2011 and provided on 19/11/2014 /117/.

- Document S.G.P.A/D.G.I.R.A/D.G./5955, dated 5 August 2011 and provided as Annex R of EPC.

- Letter from DEMEX and with reference 3901.08, dated 17 August 2012, about the Building Activities Ending

- Letter from DEMEX and with references 3901.08 and 5285/09, dated 15 November 2012, about the delivery of the Annual Administrative Report (IAA)

- Letter from DEMEX and with references 3901.08 and 0913/11, dated 15 February 2013, about Annual Detailed Technical Report (ITAP)

- Letter from DEMEX and with references 3901.08 and 9759/11, dated 5 June 2013, about affections evaluation

- Letter from DEMEX and with reference 3901.08 dated 11 December 2013, about noise evaluation

No limitations have been found to the normal operation of the wind turbines. The documentation provided includes the change of turbines from 152 wind turbines of 1,500 kW each to 45 (Phase I), plus 69 (Phase II) 2 MW G80 turbines . Annex R adds some requirements regarding studies to be carried out to monitor the wind farm’s effects on birds and bats.

Three extension permits for the construction schedule, given in /79/, were also provided. According to these extensions /117/, the deadline for construction of the wind farm was 05/08/2012. Additionally, Annex R gave a 22-month period to build up the wind farm - thus, up to 5 June 2013. According to /93/, the Normal Operation Date was declared on 1/11/2012.

By means of the letter /126/, DEMEX communicated SEMARNAT that the end of the wind farm constructions activities was achieved on 03/08/2012, thus before 05/08/2012.

In the subsequent communications from DEMEX, the following requirements from the resolution 3901.08 are stated to be accomplished:

- Letter from DEMEX dated 15 November 2012: it is stated that the Annual Administrative Report (IAA) from September 2011 to August 2012 is issued.

- Letter from DEMEX dated 15 February 2013: it is stated that the Annual Detailed Technical Report (ITAP) from November 2011 to October 2012 is issued.


- Letter from DEMEX dated 5 June 2013: it is stated that the required affections evaluation is issued

- Letter from DEMEX dated 11 December 2013: it is stated that the required study about noise effects on birds and bats is issued


10 ELECTRICAL SYSTEM REVIEW

This section contains the main findings of the review of the electrical system for Piedra Larga I Wind Farm. The detailed analysis is stated in Appendix E including a diagram of the electrical installations /120/.

The review is based on the information provided in the virtual data room which was opened for the purpose of the Due Diligence Analysis: mainly, the documents included in folders 7.2.1.1 (Electrical Engineering) and 7.1 (Equipment). DNV GL notes that the information contained in these folders regarding the electrical system basically relates to Phase 1. Some additional information provided through an FTP on 23 November 2012 has been also partly been reviewed and included in the sections below.

10.1 Electrical system

The operational electrical characteristics (voltage and frequency operational ranges) of the G80 2.MW are stated in /64/. DNV GL has also been provided with a document which states the successfully passed LVRT tests performed on a G80 in Spain against the Eon2006 grid code requirement. The LVRT tests confirmed that the wind turbine is capable of withstanding low voltage ride through that are more severe than those stated in the Mexican Grid Code requirements /73/.

DNV GL has reviewed the information provided regarding the medium voltage circuits for Phase 1 /65/ and it notes that the selected cables installed can withstand a current that is close to the maximum admissible current when the wind farm is at full load. Specifically, cable sections from the last wind turbine of each circuit to the substation are close to the 100% current limit. No final confirmation of how many circuits are installed, per trench, at these final circuit sections has been provided, nor have the electrical calculations which justify the selected cable sections.

According to /67/, Phase 1 and Phase 2 are connected to the Demex (Piedra Larga) substation, the design of which is adequate according to the industry standards. DNV GL has also reviewed documents /68/ and /69/. The design of the protection system and the communication seems to be adequate and according to the industry standard. DNV GL has also reviewed the technical characteristics of the main substation electrical equipment included in the data room folder 7.1 and it is considered to be adequate.

DNV GL has reviewed the overhead line mechanical assessment /75/. The information provided is consistent with the interconnection arrangement shown in the single line diagrams provided ( /77/ and /67/). DNV GL considers that the overhead line characteristics and design is adequate for the purposes of the Project. DNV GL has not been provided with the electrical characteristics of cable 1113 ACSR/AS. However, according to the DNV GL internal database, although this cable is sufficient to withstand the current from the wind farms, it may be somewhat oversized. In any case, DNV GL has not received these electrical characteristics from the Project.

According to /76/ the interconnection facilities comprise two additional line bays at Ixtepec Potencia substation. The bays are equipped with the usual components required for adequate connection of the circuits from the overhead line. The energy metering equipment is installed at the interconnection point. There is one for the Phase I circuit and another for the Phase II circuit.


10.2 Compliance with the Grid Code

According to the EPC contract, Phase I must comply with the Grid Code in force on the contract date /73/. The same statement is included in the EPC for Phase II, which has not yet been signed; DNV GL understands that the applicable grid code for Phase II shall be that which is currently in force /74/.

According to /64/, the G80 wind turbine is able to withstand voltage and frequency variations under normal operation of the grid. However, no confirmation has been received from Gamesa about the capability of the wind turbine to withstand values that are above normal.

DNV GL has been provided with the factory tests of the electrical equipment and the commissioning tests for the Demex and Ixtepec Potencia substations. These tests state the compliance with the Mexican Grid Code. Besides, the statement issued by CFE /103/ which allows for normal operation of the Phase I wind farm, confirms the completion of the requirements. In spite of this, according to the Grid Code /73/ an onsite test to prove LVRT compliance is required, according to the information provided by the Sponsor (the Q&A list, dated 03 December 2012), although this has not actually been required for the site.

According to /67/, two capacitor banks (7.4MVAr and 8.7MVAr, respectively) will be installed. However, no evidence of additional inductive reactive power is stated. No confirmation was received from the Sponsor to confirm the capacitor banks’ nominal power, nor an assessment which proves that the 0.95 capacitive-inductive power factor will be achieved at the interconnection point at Ixtepec Potencia substation.

In addition, wind farms larger than 10MW are required to participate in voltage control. No information was provided regarding the specific requirements set out by CFE for the Phase I and Phase II wind farms regarding participation in voltage control and how this control is to be implemented.

DNV GL has been provided with the required data for an independent energy loss assessment. The results are stated below:

Table 10-1: Electrical loss assessment for Phase I

Component Electrical Losses

Medium voltage cables 0.52% Wind turbine transformers 1.14% Substation transformers 0.33% Overhead line 0.21% Total losses 2.20% Wind farm electrical efficiency 97.8%

The results of DNV GL’s independent calculation of electrical losses do not match the figure derived from the operational data (see Section 2.3.8 for more information).


11 WIND FARM INSPECTION

As a complement to the Due Diligence work, the Customer asked DNV GL to inspect the operational Piedra Larga Phase I wind farm of the Project and analyse the current status of the assets.

DNV GL visited the site during week 47, from 19 to 22 November 2012. The aim of the site visit was to inspect 5 of the wind turbines and the electrical substation at the site. DNV GL has inspected 6 wind turbines, exceeding the planned scope.

The inspections were carried out over three days. The results of these inspections are summarised in this section. The wind turbines had finished the commissioning tests when the inspections were carried out. DNV GL has selected a representative sample of wind turbines in the four circuits and in the overall geographic area.

The Operation and Maintenance staff were asked about their experience and about their knowledge of any relevant technical issues at the wind farm.

The results of the inspections show that, in general terms, the wind turbines are in good condition, as is expected in a wind farm that has just started operating. All the wind turbine major components were working properly at the time of inspection. There is no need for urgent repairs and no urgent action needs to be taken to achieve normal operation of the wind turbines. Nevertheless, some particularly unusual defects were noted and some suggestions for solving these are made below.

11.1 Project/wind turbine data

Piedra Larga started producing energy in September 2012. When the inspection was carried out the acceptance tests had been finished, although the Provisional Acceptance Certificate had not yet been signed. Phase 1 of the Piedra Larga wind farm comprises 45 Gamesa G80 IEC Class IA wind turbines, rated at 2,000kW each.

WT

manufacturer: Gamesa WT type: G80

Inspected

turbines: 2, 7, 26, 33, 38, 44 WT Location: Oaxaca, Mexico

Rated power: 2000 kW Year of construction:

2012

Rotor diameter: 80 m Acceptance: Not signed

Type of tower: Steel tube, conical Hub height: 67 m


Figure 11-1: Overview of the wind farm

The maintenance staff consists of 4 teams with 2 technicians in each; the ratio of 8 technicians to 45 turbines is considered to be adequate. Half of the Operation and Maintenance staff lives in Juchitan de Zaragoza, located 20 km from Unión Hidalgo, and has worked in other wind farms in the zone before starting at Demex I. Each maintenance team includes one expert technician and one technician with limited experience. The non-experienced technicians are from Unión Hidalgo. DNV GL considers the way the O&M teams are trained to be a good strategy. In spite of this, DNV GL has noted during its inspections that the expertise level was not as high as that of technicians in consolidated markets. However, the team manager is well trained and has had previous experience with a Gamesa project installed in the north of Mexico. DNV GL therefore considers that this is not a risk factor for the Project.

The wind is (in general) constant and strong, so the O&M tasks must be carried out in relatively short wind speed windows, in order to minimise the production losses. DNV GL was informed that there is no plan to use a third company for tightening or other tasks, as is usual in the wind industry. Considering that the Mexican market is still not consolidated, DNV GL observes this as a positive point for the Project.

11.2 The site

The site is near to the sea and the surrounding land is used for crops and animal husbandry. A small river runs through the wind farm and can be crossed using a bridge constructed in the principal internal road. The name of the river is “Espiritu Santo”.


Figure 11-2: Livestock on the site surroundings (left) and the Espiritu Santo River (right)

The wind farm has four entrances from the road which runs from Union Hidalgo to La Venta (Venustiano Carranza Street). One of the entrances has a permanent guardhouse, with at least two security guards constantly monitoring wind farm visitors. Two patrol vehicles are also constantly watching the other entrances. Nevertheless, DNV GL was informed that no vandalism or stolen cables have been reported, as yet.

Figure 11-3: Principal road access to the wind farm with the guardhouse (left) and one of the two patrol vehicles (right)

The site looks flat and wind farm access is easy for heavy machinery, with no slopes or tight curves; no access problems to the wind farm are therefore expected. The site tracks are in good condition, with no particular drainage, surface or vegetation issues.

The wind farm contains two met masts, one of these being located near WT32 that, according to the information provided, will be used for the power curve measurement. The other mast is located near the WT12 and this is the reference meteorological mast for the wind farm.


11.3 Turbine status

The general condition of the wind turbines is good and the perception of DNV GL is that the installation and commissioning of the wind turbines has been carried out according to normal industry practice. Nevertheless, some issues were noted and respective recommendations are proposed in the following sections.

11.3.1 Foundations

The outside of the foundations at the Piedra Larga Phase I wind farm are mainly in the ground and covered with grass. Although a small section was verified, locating some small cracks over the foundation of WT33. The issue will not affect the normal operation of the wind turbine, but DNV GL recommends sealing the cracks in order to avoid water ingress and future issues related to corrosion or more internal concrete damage.

On the inside, there was no sign of water or relevant damage. The earthing was in good condition and the bolts fitted well and were without corrosion.

11.3.2 Tower

No important issues were detected on the towers. The most remarkable item of the general picture is the oil leaks that stain the outside of the tower as a result of leaks coming from an oil escape in the hydraulic pitch system. The joint of a proportional valve has been damaged and the oil has fallen from the hub spinner and been dragged by the wind to both sides of the tower, forming 90º in the predominant wind direction.

Figure 11-4: Remains of oil leaks of the pitch falling from the yaw system

This defect is not common in this technology and the damage of the joint was probably caused during factory assembly. The failure was located in three of the six wind turbines inspected. The O&M staff declares that, once the joint is changed, the failure is not repeated.


Figure 11-5: Specific location of the joint rupture in the pitch hydraulic system

Apart from an aesthetic perspective DNV GL does not consider this issue to be a risk factor for normal operation of the wind turbines. Nevertheless, the consequences for the tower coating are visible. DNV GL believes the issue has been corrected but it recommends complete cleaning of the tower in order to maintain it in its original condition.

Dust ingress was noted in the base platform of the tower. Gamesa should install the dust filter in the doors. Other non-critical specific issues were located in the tower and are detailed in the checklists.

11.3.3 Nacelle

The nacelle has two small windows that allow for circulation of cool wind through the nacelle interior. The opening of the front blinds is controlled by an automatic motor mechanism. In two of the six nacelles inspected the mechanism was not working, and the refrigeration of the nacelle was not properly carried out.

Figure 11-6: High temperature version of the nacelle installed in Piedra Larga Phase I (left) and failure of the automatic mechanism used for opening the front blind (right)

The issue is not critical but it should be resolved, as the major component temperature alarms will increase during the summer if the component is not repaired.


Regarding the inside condition of the nacelle, DNV GL has found that it was clean, the internal cables were well secured, the bolts were without corrosion, and the cover was in good general condition. Only in two of the wind turbines were the supports of the internal foam used to minimise turbine noise detached. DNV GL recommends repairing the same, whilst avoiding the subsequent detachment of the foam.

11.3.4 Gearboxes

All the gearboxes were inspected externally and internally. The internal inspection was limited to the parallel stage, as the inspection of the planetary stage and bearings will require a video endoscope.

The gearboxes were in generally good condition. Scratches from, and adhesion by, passing particles were noted in gears, mostly located over the wheel of the low-speed shaft and the pinion of the intermediate speed shaft. A very small sign of micropitting has started to be perceptible over the wheel of the low-speed shaft of wind turbine WT7.

DNV GL believes that this damage is not relevant and recommends visual monitoring of wind turbines WT7, WT26 and WT2 during servicing. Monitoring during servicing will allow for the internal condition of the aforementioned gearboxes to be established as either worsened or not.

11.4 Electric substation, workshop and control building

The building infrastructure is divided into two buildings. One of these buildings is the warehouse for spare parts stock that is equipped with a mobile crane for moving components. DNV GL has verified that yaw drives, couplings and oil pumps were the biggest spare parts stored in the warehouse. Major components, such as gearboxes, generators, transformers, blades and hubs, are not stored in the warehouse. Gamesa has a Regional Maintenance Center in Ixtepec, located 53 km from Union Hidalgo (the nearest town to the wind farm), in which the major components are distributed to all the GAMESA wind farms in the zone.

The other building is divided into four sections. The first section is a meeting room in which the Gamesa staff meets and plans its daily tasks. The second section is the control room, where the wind turbines are monitored, and the Renovalia office. The third section is where the energy meters, and the Gamesa and Renovalia SCADA servers are located. In the fourth section the emergency batteries and medium voltage switchgears are installed.

DNV GL checked, at the moment of inspection, that all the installed equipment was operational. The remote connection of the SCADA was also verified. The general perception is that the internal infrastructure of the substation is properly installed.


Figure 11-7: The two buildings of the substation (left) and an internal picture of the spare parts warehouse (right)

The outdoor infrastructure consists of a double bar installation, with two power transformers of 34.5/230 kV for Piedra Larga Phase I and two positions for Piedra Larga Phase II. The overhead line and subterranean cable ducts for Phase II are already installed. Nevertheless, no transformer or concrete base is set for the second phase. In addition to the usual electric outdoor infrastructure, there are: one gasoline emergency generator; and one pump for evacuating residual oil to a truck, in case of any oil escaping from the power transformers.

Figure 11-8: Principal components as spare parts (blades and generators)

The following comments show the generally positive perception of the electrical substation condition:

The SCADA connection to the inspected turbines was working and no problems were detected.

The communication equipment was working properly.

Spare parts warehouse

Office and MV switchgear building


The transformer position and switchgear room were in good condition. Doors, lighting and paintworks were found to be well-maintained.

The high voltage (HV) equipment and meters were functional and all the lines were connected.

All the accessible earthing points were checked and are in good condition at the electrical substation.


12 O&M REPORT REVIEW

DNV GL has reviewed the following documents:

O&M reports from the period January 2013 to December 2014 /10/

O&M contract between DEMEX and GESA /8/

Maintenance Plan /9/

Excel sheet detailing corrective maintenance for the Balance of Plant /11/

Renovalia Excel management sheets for alarms and availability /12/

DNV GL has noted inconsistences in the following information:

1. The starting date of the preventive maintenance is established in the Gamesa O&M reports. Nevertheless the ending date and the detail of the specific task carried out during the preventive maintenance (greasing tightening, etc.) is not clearly described in the O&M reports /10/.

2. A change in the reporting dates of the 3-month maintenance between the April 2013 and May 2013 O&M reports /10/.

3. Some of the tasks for the 3-month maintenance were carried out after the 6-month maintenance.

4. The execution dates for maintenance noted in the Renovalia Excel sheets /12/ are not the same as those reported in the Gamesa O&M monthly reports /10/.

5. The Renovalia Excel sheet does not report the 3-month maintenance for WTGs 1, 3, 4, 8, 17, 18 and 26 /12/

6. The Renovalia Excel sheet does not report the 12-month maintenance for WTGs 37 and 38 /12/

7. The 24-months maintenance was not reported for wind turbines WTGs 11, 14 and 28. Nevertheless according to the Renovalia excel sheets preventive maintenance actions were carried out during September and December 2014 /12/.

12.1 Preventive maintenance

According to the O&M agreement signed between DEMEX (the Owner) and GESA Mexico (the Maintainer), scheduled maintenance is to be carried out every six months, in accordance with the manufacturer’s O&M manuals. The Owner and Maintainer can agree to re-schedule the planned maintenance to be carried out at a more optimal time, but the tasks cannot be moved by more than 1 month /8/. Regarding time spent carrying out the O&M tasks, no more than 48 h (per year and turbine) are allowed.

Regarding the scope of works, DNV GL would expect scheduled maintenance to cover (as a minimum) oil re-filling for the hydraulic system, grease replacement for the pitch bearings, main bearings and yaw bearings, bolt re-tightening, replacement of air filters, cleaning, visual inspections and functional tests, amongst others. DNV GL has been provided with the Gamesa O&M Plan /9/ and can confirm that these tasks are included in the scope of scheduled maintenance.

The O&M monthly reports contain information on the dates when scheduled maintenance has been carried out on each turbine at the wind farm. Table C-1 in Appendix C summarises these dates, as described in the monthly O&M reports available, and Table C–1 highlights the longest delays - per turbine, and per maintenance.


Table 12–1: Period between preventative maintenance, programmed and commissioning dates of the Piedra Larga I wind turbines

Maintenance COM y P3 MM

COM y R3 MM

Diff R3 & P3MM

COM y P6 MM

COM y R6 MM

Diff R3 & R6MM

Diff R6 & P6MM

According to the O&M Contract (months)

3 3 0 6 6 6 0

Maximum (months) 6 17 11 12 13 2 4 Minimum (months) 1 8 5 7 7 -5 -1 Average (months) 3 11 8 9 9 -2 0


COM y R12 MM

Diff R6 &

R12MM

Diff R12 &

P12MM

COM y P18 MM

COM y R18 MM

Diff R12 &

R18MM

Diff R18 &

P18MM According to the O&M Contract (months)

6 6 6 0 18 18 6 0

Maximum (months) 18 20 8 3 23 24 7 2 Minimum (months) 12 12 2 -1 18 18 3 0 Average (months) 13 15 6 1 19 20 5 1


COM y R24 MM

Diff R18 &

R24MM

Diff R24 &

P24MM According to the O&M Contract (months)

24 24 6 0

Maximum (months) 29 30 6 1 Minimum (months) 24 24 4 0 Average (months) 25 25 5 0 12.1.1 3MM Preventative maintenance

According to the Renovalia control Excel sheets /12/, the 3-month maintenance started with WTG 7 in January 2013 and finished in October 2013. Nevertheless, the tasks were not carried out over a continuous period. The total time spent on this maintenance was 548 hours, which means approximately 12 h per wind turbine.

Regarding the Gamesa O&M reports /10/, DNV GL has the following comments:

The scheduled dates for carrying out the 3-month maintenances for WTGs 6, 26, 35, 40, 42, 43 and 44 exceed the 3-month period after commissioning. The differences are shown in Table C-2. Based on explanations provided by Gamesa, no. 6 in /121/, it is understood that the delay of the 3-month maintenances of these turbines is due to having the respective scheduled dates coinciding with the high wind period in this region, which generally lasts from October to March as shown in Figure 12–1 and Table 2–9. During this period only a limited number of low wind dates allow for conducting the required maintenance. This resulted in postponing the maintenance of these turbines to the end of the high wind period. This explanation appears reasonable to DNV GL. However, it is recommended that future preventive maintenance work is suitably scheduled in order not to be delayed due to the high wind period in the region. This is understood to be the reason for having the half-annual and annual maintenance generally scheduled in the periods March to April and September to October, respectively.


Figure 12–1: Annual wind distribution in the Isthmus of Tehuantepec /121/

The 3-month maintenance was, on average, carried out 11 months after commissioning of the

wind turbines. In WTG 35 the maintenance was carried out 17 months after the commissioning date.

The 3-month maintenance was carried out on average 8 months after the programmed dates.

The 3-months maintenance was programmed before the stated period for 26 WTGs. DNV GL believes this could be related to the limited resource available for carrying out all the maintenance tasks during low wind periods at the same time. Nevertheless, this should be confirmed.

As the scheduled dates for carrying out the tasks were not met, DNV GL believes that the 3-month maintenance schedule was poorly executed.

12.1.2 6MM Preventative maintenance

The 6-month maintenance started with WTG 32 in February 2013 and finished in August 2013 /12/. However, the tasks were not carried out over a continuous period. The total time spent on this maintenance was 526 hours, which means approximately 12 h per wind turbine.

Regarding the Gamesa O&M reports /10/, DNV GL notes the following:

The scheduled dates for carrying out the 6-month maintenance exceeded the 6-month period, after commissioning. The average period for this maintenance was 9 months after the commissioning date. In general, the 6-month maintenance was carried out in line with the scheduled dates. Similarly to the delay of the 3-month maintenance, Gamesa explained that the planned period of the 6-month maintenance was shifted compared to the contractual dates due to an overlap with the main wind period and additionally several minor correction works accumulated leading to an extension of the planned period, stated in no. 7 in /121/ and shown in below Figure 12–2. This explanation appears reasonable to DNV GL. It is understood that the 3-months shift between contractual maintenance dates, which are based on the commissioning dates, and the planned maintenance period will be similar every year. Therefore this does not appear to be a risk for DNV GL.


Figure 12–2: Durations of planned maintenance /121/

In addition to the turbines where the 3-month maintenance was delayed (WTGs 6, 26, 35, 40,

42, 43 and 44), the 6-month maintenance for WTGs 3, 7 and 8 was carried out 10 months after commissioning, as shown in Table C-2.

12.1.3 12MM Preventive maintenance

The 12-month maintenance started with WTG 1 in September 2013 and finished in December 2013 /12/. In this case, the tasks were carried out over a sustained period. The total time spent on this maintenance was 754 hours, which means approximately 16 h per wind turbine.


The 12-months maintenance was scheduled 13 months after the commissioning date.

DNV GL notes (when comparing the differences between the 6-month and 12-month maintenance) that the maintainer has carried out at first place the 12-month maintenance in those turbines where the 6-month maintenance was delayed.

The 12-month maintenance was carried out, on average, 15 months after commissioning of the wind turbines.

As is shown in Table C-2, longer delays in the 12-month maintenance occurred in WTGs 12, 37 and 38.


The 18-month maintenance started with WTG 1 in March 2014 and the last registered action was provided on April 30, 2014. Until then, the 18-month maintenance was pending for WTGs 7, 8, 16, 17, 24, 29 and 38 /12/.


The 18-month maintenance was scheduled 19 months after the commissioning date.

The average difference between the starting of the 12-month and 18-month maintenances was 5 months instead of 6 months.

The 18-month maintenance was, on average, carried out 20 months after commissioning of the wind turbines.



Gamesa has reported the starting of the 24-months maintenance in August 2014. During October 2014 Gamesa reports the ending of the 24-months maintenance for 44 WTGs. Nevertheless in the Renovalia excel sheets some 24-months preventive maintenance actions were reported during December 2014.

Due to an elevator failure in October 2014 and high wind speed in November 2014 the maintenance of WTG 12 was not conducted until December2014.

In December 2014 the preventive maintenance for WTG27 was pending to be concluded due to a failure in a blade that caused a delay in preventive maintenance tasks, concluded on January the 3rd.

The average time for the 24-months preventive maintenance was 22 h/WTG. In total the 24-months preventive maintenance was carried out in 1000h, which means 250h more than the 12-months maintenance (the preventive maintenance was carried out in 750h). The difference is consistent with the requirements of a more laborious preventive maintenance. Nevertheless in order to maintain the figures under the level of 48h/WTG year, DNV GL recommends monitoring the time spent in future maintenance tasks.


The 24-month maintenance was scheduled 25 months after the commissioning date.

The average difference between the beginning of the 24-month and 18-month maintenance was 5 months (instead of 6months).

The 24-month maintenance was, on average, carried out 25 months after commissioning of the wind turbines.

12.1.6 Other preventive actions

The maintenance of the safety line and fall arrester system was reported in the monthly O&M report from June 2014. It is an industry practice to carry out the maintenance of the safety line and fall arrester system in an annual basis. DNV GL understands that this is not the first preventive maintenance action that was carried out on these devices, but no information was found in other O&M reports. The customer informed that maintenance of the safety line and fall arrester system where conducted in May and April 2013 respectively.

On 15, 16 and 17 July 2014 the maintenance of the electrical substation of DEMEX I wind farm was carried out.

12.1.7 Preventive maintenance conclusion

The following issues can be concluded from the review of the preventive O&M activities:

According to the Renovalia excel sheets, the preventive maintenance during the first operational year did not exceed the 25h/WTG, and during the second operational year the 48h/WTG limit has been reached.

DNV GL understands that some of the delays in the maintenance may be related to high wind speeds and the consistency of the resource. Gamesa confirmed that half-annual and annual


maintenance is generally scheduled in the periods March to April and September to October, respectively, in order to avoid overlap with the high wind period in the area from October to March. This is considered to be reasonable, even if this represents a delay compared to the maintenance dates calculated based on the commissioning dates of the turbines.

For WTG 35, the scheduled dates for preventative maintenance were delayed in all cases. Based on explanations provided by Gamesa, no. 8 in /121/, it is understood that this was mainly due to the shifting the maintenance dates of this turbine away from the high wind period, which is considered to be acceptable.

The programmed dates for the 3-month maintenance caused delays in the consecutive preventative maintenance for wind turbines WTGs 6, 26, 35, 40, 42, 43 and 44.

Excluding the 3-month maintenance, the programmed monthly maintenance dates were (in general) accomplished. The longest delay occurred for WTG 8 in relation to the 6-month maintenance, where the tasks were carried out 4 months after the planned date.

In general terms, the maintenance for WTGs 3, 7, 8 and 35 was delayed more than twice and DNV GL believes that these turbines are more exposed to the possibility of failures caused by a delayed application of maintenance tasks, including: lubrication failures, vibration failures, oil level failures and leaks, amongst other things.

Taking into account the electrical, elevator and safety line maintenance, the total time spent on preventive maintenance for 2013 was 1,991h in total, and 44h per WTG. This means that the 48 h ratio established in the O&M contract for preventive maintenance was not exceeded.

Gamesa has adjusted the schedule of the preventive maintenances. For the 24-months preventive maintenance DNV GL notes that in average these tasks have started with no delays.

12.2 Reported causes of low production and availability

This section summarises the availability and production figures from the O&M reports. The main sources of unavailability and production losses are discussed here.

DNV GL has noted inconsistent values in the O&M reports. Until July 2013, the availability and production figures (excluding force majeure occurrences) were in some cases above 100%, and sometimes as high as 110% /10/. The issue was resolved by updating the SCADA software /5/ and /6/.

The Renovalia and O&M monthly report figures were compared by DNV GL. The differences are described in Table C-3. With the exception of a possible counter failure in WTG 17 during October 2013, the differences between the Renovalia and Gamesa figures are correct from August 2013. For this reason, DNV GL used the availability figures from Renovalia /12/ to investigate the technical issues that have caused the unavailability and production losses.

DNV GL has analysed the technical issues related to the monthly reported availabilities below 97%. The months where the figures are under this limit are:

For 2013: January, February, March, April and July

For 2014: January only


12.2.1 January 2013

12.2.1.1 BoP issues

During January 2013 the most significant issue related to loose connections in Transformer 1, located in the electrical substation. This issue affected two circuits at the same time, causing 429h of unavailability /11/. In Table C–3 DNV GL has classified the alarms related to the January 2013 stops, describing both the failures and the BoP issues.

A further two BoP issues caused unavailability. A fibre-optic cable became loose and the wind farm lost 227 h of availability until the root cause was detected. Misalignment in the electrical substation grounding switches were the third main cause of unavailability at the wind farm. The turbines were disconnected for 201 h.

DNV GL has compared the reported time related to the substation and medium voltage overhead line in the BoP Excel sheet /11/ to the time of the alarms “Fallo 1 agrupado convertidor ISU” which was used by the SCADA /12/; a difference of 137h was noted.

12.2.1.2 WTG issues

In addition to the BoP issues, some wind turbines were particularly affected by other issues which are mentioned in Table 12–2 :

Table 12–2: WTGs alarms with significant impact on January 2013 availability Alarm Stop times [h]

Description WTG 11

WTG 14

WTG 21

WTG 29

Thermal protection of the yaw motors 0 0 61 0

Hub leakage 3 0 0 0

Pitch angle difference in two blades 0 0 15 0

Paso Pause-Reset remote control 0 103 0 19

PLC module failure 161 44 0 0

Contactor failure FG008 en ABB V2 (B2(6h)), Contactor failure FG008 en ABB V4 (B1(1h))

0 0 0 154

WTG 11 was affected by failures in the PLC. In most cases the origin of the failure was not repaired and the PLC was restarted. The failure affected WTG 11 until March 2013, when a corrective action finally solved the issue. This alarm (PLC module failure) has also significantly affected WTGs 14, 16 and 32. DNV GL is not aware of any corrective action taken to solve the problem and recommends requesting such information from the maintainer, as this could be useful in identifying similar occurrences in the future.

The reported alarm for WTG14 (Paso Pause-Reset remote control) was linked to the replacing of the ambient temperature sensor. Nevertheless, DNV GL believes that 103h is too much time for this corrective action and more information about this should be required. This alarm has also significantly affected WTGs 9, 12, 29 and 38. No checking of the system has been reported for these turbines and the corrective action was, in all cases, to restart the WTGs. However, DNV GL believes that the maintainer took too much time for such an action.


During a similar period to the issue affecting WTG 14 (from January 17 to January 19), WTG 21 was stopped and restarted due to a Thermal protection of the yaw motors alarm. As with WTG 14, DNV GL believes that too much time was taken to restart the thermic protective breaker for WTG21.

12.2.2 February 2013

12.2.2.1 BoP issues

In February 2013 circuit 1 was affected by overheating of the medium voltage cables, located in the passage of the bridge over the Espiritu Santo River. The tube used for passing the cable through is made of steel. The circuit was affected for 28h and the failure led to 310h of disconnection for that circuit.

In Table C–4 DNV GL has classified the alarms causing stops in February 2013, describing both the wind farm failures and the BoP issues.

12.2.2.2 WTG issues

In addition to the BoP issues, some wind turbines were particularly affected by other issues mentioned in Table 12–3:

Table 12–3: WTGs alarms with significant impact on February 2013 availability Alarm Stop times [h]

Description WTG2 WTG 15 WTG16 WTG18 WTG26 WTG40

Low oil level of hydraulic unit 68 0 0 0 0 0

Rotor speed measure reading failure 0 0 0 0 162 0

Generator fan coolers 0 0 0 0 0 149

Emergency button in ground cabinets 0 6 9 0 19 0

PLC module failure 0 0 67 0 0 0

Error BUS - Failure INTERBUS 51 112 0 0 5 0

Stator overcurrent 3 0 0 0 0 0

Rotor overcurrent 0 0 114 141 0 0

WTG 02 stopped due to a Low oil level alarm indicating an issue with the hydraulic unit. On February 3 2013, the maintainer replaced the joints of the proportional valves and the brushes of the rotary union, and added 20 litres of hydraulic oil. On February 26 the alarm was activated again and, this time, the maintainer replaced the O-ring of the proportional valve. The first action was carried out in 47 hours and the second corrective action took 20 hours. DNV GL believes that the time taken for such corrective action exceeds normal standards in the market.

WTG 15 was affected by INTERBUS failures. The corrective action was, in most case, to restart the PLC. The connection and cables were inspected several times. The failure also affected the availability of the WTG in the following months.

Regarding WTG 16, the PLC failures were the main cause of unavailability in February 2013. The root cause was not solved during this month and the corrective actions consisted of restarting the WTG. As is stated in Section 2.3.3, the issue affected the turbine during the first months of operation.

The Rotor overcurrent alarm affected WTG 18. Gamesa replaced the generator’s brush holder after the turbine had been stopped for 141 hours.

The torque limiter was replaced in WTG 26, as a result of the Rotor speed measuring failure.


The fan motor of the generator in WTG 40 was replaced following an alarm relating to the thermic breakers of the generator. The total stop time of this failure was seven days.

12.2.3 March 2013

12.2.3.1 BoP issues

In March 2013, circuit 1 and circuit 2 were affected by a failure in the overcurrent protection breaker of Transformer 1. Siemens replaced the breaker on April 12, 2013. On March 20 2013 the oil in the transformers was refilled. No leaks were detected, so the maintainer believes the oil has settled down inside the cooler transformer. The alarm “Converter Group failure 1 ISU” groups the two aforementioned BoP issues together.

In Table C–5 DNV GL has classified the alarms causing the March 2013 stops, describing both the wind farm failures and the BoP issues.

12.2.3.2 WTG issues

In addition to the BoP issues, some wind turbines were particularly affected by the issues mentioned in Table 12–4:

Table 12–4: WTGs alarms with significant impact on March 2013 availability Alarm Stop times [h]

Description WTG1 WTG2 WTG8 WTG23 WTG28

Low oil level of hydraulic unit 59 62 0 0 0

OGS 1 0 0 0 63

Low pitch number in Stop 0 53 0 0 0


0 0 0 234 10

Converter Group failure INU 0 0 365 0 0

The generator of WTG 8 was damaged on March 16. The alarm related to the fault is: Converter Group failure INU. According to /119/, the generator replacement was finished at the beginning of April 2013.

WTG 1 and WTG 2 were affected by oil leakages in the hub. The leakages were caused by damage to the proportional valves of the pitch hydraulic system. The corrective action consisted of replacing all the damaged valves in both WTGs.

Alarms FG008 ABB V2 and FG008 ABB V4 are related to the 234h of non-production for WTG 23. DNV GL is not aware of the root cause of the damage. According to the reported information, the delay in the repair works was caused by the lack of necessary rotor bolts. The failure is not clear, and DNV GL recommends requesting information regarding the origin of this failure.

The OGS alarm, which signals the failure of the surveillance over speed system, was the main cause of unavailability in the WTG 28. The alarm has also affected other turbines, in other months.

12.2.4 April 2013

12.2.4.1 BoP issues

Circuit 1 and circuit 2 were affected by the failure mentioned in Section 12.2.3.1 until April 4 2013. The breaker was replaced on April 12 2013. Taking into account the replacement of the breaker, the total


disconnection time was 638h. The alarm “Converter Group failure 1 ISU” groups the failures related to this BoP issue together.

On April 16 2013, a SF6 gas leakage led to the replacement of pole A of a 230V power breaker. This issue affected the entire wind farm. The total time of turbine disconnection was 556 h.

On April 29 2013, the whole wind farm was disconnected for 640h through activation of the 86b breaker. Switches 93130 and 92010 were also disconnected. The root cause of the disconnection is not clear and DNV GL recommends asking for additional information.

DNV GL has classified (in Table C–6) the alarms causing the April 2013 stops, describing both the wind farm failures and the BoP issues.

12.2.4.2 WTG issues

In addition to the BoP issues, some wind turbines were particularly affected by other issues mentioned in Table 12–5:

Table 12–5: WTGs alarms with significant impact on April 2013 availability Alarm Stop times [h]

Description WTG2 WTG6 WTG17 WTG20

Low oil level of hydraulic unit 10 0 0 0

Hydraulic oil high temperature 1 0 0 0

Low preasure in gearbox 2 0 0 0

Failure in PLC module 0 0 128 60

Error BUS - Fallo INTERBUS 26 0 11 13


0 138 0 0

Regarding WTG17, the PLC failures were the main cause of unavailability in April 2013. The PLC was constantly restarted. The following corrective actions were implemented, in order to solve the issue:

New parameters were loaded in the PLC Interchange of temperature sensors Replacement of the fan cooler filters of the cabinet Re-adjustment of the temperature module Earthing cables contact checking Replacement of the temperature module

After replacement of the temperature module, the issue seems to be solved. This issue also occurred in WTG 20, WTG 33 and WTG 45.

WTG 6 was affected by alarms related to the FG008 contactor. Multiple corrective actions were carried out, in order to solve the issue. On April 25 2013 a damaged cable was found and two fuses and a safety breaker were replaced. The failure has also affected WTGs 5 and 21.

A failure of the proportional valve and failures in the Interbus were the main cause of unavailability in WTG 02. The corrective action for failure in the Interbus consisted of restarting the PLC. The issue has affected WTGs 9, 15, 17, 13, 26, 28 - totalling 107 h.


12.2.5 July 2013

12.2.5.1 BoP issues

On July 23 2013 the wind farm was disconnected for 2 hours. No abnormal behaviour was detected and the maintainer was unable to locate the root cause of the failure. The alarm “Converter Group failure 1 ISU” groups the failures related to this BoP issue together.

In Table C–7, DNV GL has classified the alarms causing the July 2013 stops, describing both the wind farm failures and the BoP issues.

12.2.5.2 WTG issues

In addition to the BoP issues, some wind turbines were particularly affected by the issues mentioned in Table 12–6:

Table 12–6: WTGs alarms with significant impact on July 2013 availability Alarm Stop times [h]

Description WTG1 WTG7 WTG35 WTG41

Low oil level of hydraulic unit 14 0 0 0

Hydraulic oil high temperature 0 102 0 0

High speed generator 0 12 0 0

Failure in checking the generator fan coolers

81 0 0 0

Local Stop and reset 0 0 0 83

Rotor overcurrent 0 0 112 0

Regarding the stop of 112h in WTG 35, the brushes of the generator slip rings were not replaced until July 29 2013, but the six-month preventative maintenance, during which a review of the condition of the brushes should have been undertaken, was carried out on June 06 2013. DNV GL believes the preventative maintenance of WTG 35 might not have been properly carried out.

WTG 07 was stopped for 102 hours by a false alarm for hydraulic oil at a high temperature. The communication cable between the WTG and SGIPE was not properly connected.

WTG 1 was stopped for 80 hours. A motor for the generator fan coolers was damaged.

As it is stated in Section 12.2.3.2, leakages in the hub affected WTG 01 in March. After replacing the proportional valve, the hydraulic oil was not refilled that month. Then, the oil level alarm stopped the wind turbine in July for 14h, until 80 litres of hydraulic oil were refilled. The hydraulic oil level should be reviewed during the 6-month preventive maintenance that was finished on 4 April 2013. DNV GL believes the 6-month preventive maintenance of WTG 01 might not have been properly carried out.

Failures in the PLC module stopped WTG 41 for 83 hours. The module was restarted but no ultimate solution was found.

12.2.6 January 2014

12.2.6.1 BoP issues

On January 29 2014, Gamesa carried out maintenance on capacitor banks 1 and 2. The action has produced the disconnection of 26 WTGs and caused a non-productive period of 305 hours.


Regarding the WTGs, the reported issues have not caused any important stops that had an impact on the availability figures for January 2014.

In Table C–8 DNV GL has classified the alarms causing the January 2014 stops, describing both the wind farm failures and the BoP issues.

12.2.7 Reported availability and production conclusion

Based on the information reviewed, DNV GL has summarised the following issues:

- The BoP issues were mostly related to deficiencies in the electrical substation. The number of failures during the first 4 operational months which affected the electrical infrastructure of the wind farm is above the normal failure rate expected for the initial operational months of a wind farm.

- The reported monthly availability and production figures of the O&M reports are inconsistent until August 2013.

- The months with least production and availability were: January, February, March, April and July (during 2013 and January 2014).

- From January to April 2013 the BoP issues had a significant impact on the availability and production figures. However, all these issues have now been solved.

- The PLC module issues were the most significant cause of WTG non-availability and production losses.

- The Interbus failures were an important source of unavailability for the WTGs. The root cause of the failures is not clear.

- Oil level alarms and the replacement of the generator slip ring brushes were each a cause of production losses over several months.

DNV GL recommends:

- Verifying, during future preventive maintenance, that all the necessary tasks have been carried out according to the O&M manual;

After March 2014 the monthly reported availability has been above 98% /12/. Based on these figures the wind farm seems to have overcome the ramp-up period and is performing at its expected level.

12.3 Alarms, corrective maintenance and retrofits

This section summarises the study of the turbine alarms and corrective maintenance reported in the O&M reports. The maintainer’s responses to the issues are also discussed below.

12.3.1 Alarms

In order to focus on the turbine alarms, BoP issues are not mentioned in this section.

The figure below shows the percentage of stops caused by different turbine alarm group codes in years 2013 and 2014.


Figure 12–3: Stop time by alarm occurrences in the Piedra Larga WTGs during 2013 and 2014

Table 12–7 shows the different turbine systems that cumulated a larger number of stops.

Table 12–7: WTGs alarms with more stops- hours in years 2013-2014

Turbine alarm group

Alarms Description Stopping hours [h]

Number of occurrences

Gearbox 402 Low level of gearbox oil 160 154 426 Reading failure in rotor speed 143 490 410 OGS 78 7 Converter 4027 FG008 failure 45 77 4052 Converter failure group INU 36 48 4006 Overcurrent in stator 31 29 4007 Overcurrent in rotor 26 37 Operational Status

916 Remote control Stop- reset 181 27

Yaw sytem2%

Hydraulic Unit9%

Climate4%

Gearbox31%

Generator6%

Communication5%

Pitch3%

Operational status14%

Network connection

0%

Software9%

Converter17%


12.3.1.1 Gearbox group alarms

The Gearbox stops were mainly caused by the alarms 402 (low level of gearbox oil), 426 (reading failure in rotor speed) and 410 (OGS).

Figure 12–4: Occurrences of gearbox system alarms

Alarm 402 has affected turbines WTGs 13 and 4. In November 2014, 80 litres of gearbox oil were refilled in WTG 13. DNV GL notes that this means more than 25% of total volume of the gearbox (315 l). Normally in these cases a videoscope inspection is recommended in order to exclude any possible damage in the gearbox bearings and gears. The corrective action applied by the maintainer was resetting the PLC in the “ground” control cabinet.

At a lesser extent the alarm 402 has also affected turbines 28 and 29. As the Alarm 402 mainly occurs during the windy season and the nacelle checking procedure is limited by the high wind speeds, DNV GL does not expect a reduction in short term of these alarms.

In November 2014 the maintainer refilled 20 l of gearbox oil in WTGs 4 and 30, and 30 l in WTG 28. DNV GL recommends confirming with Gamesa the reason of such volume of gearbox oil.

Alarm 426 has specifically affected turbines WTGs 3, 7, 13 and 31. WTG 3 has been the most affected wind turbine by this cause. WTG 3 has been stopped 212 times in total, 111 times during 2014. Only two corrective actions were registered over this turbine. Both actions occurred in 2014 and have mainly consisted in adjusting and changing the inductive sensors. It is noted that during the remaining stops the turbine 3 was remotely restarted.

In WTGs 7, 13 and 31 the alarms were managed in the same way being the turbine remotely restarted most of the times. The corrective maintenance for this alarm mainly consists in replacing inductive sensors and exchanging the torque limiter. The most time-consuming of those corrective actions is the exchange of the torque limiter. Nevertheless the most frequent repair is the exchange of the inductive sensors. Even when the exchange of the inductive sensors is a simple corrective maintenance, the fact that the turbines are constantly restarting is penalizing the availability figures. It is noted that the trend of this alarm in not decreasing in time. DNV GL recommends that, if the wind speed allows climbing the turbine, the root cause of the failures is analysed that in most of the cases seems to consist in simple repair actions.

0

10

20

30

40

50

60

Cor

rect

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[h] Alarm402

Alarm 426

Alarm 410


The OGS (alarm code 410) reports an issue with the surveillance of the overspeed system (OGS) . WTGs 27, 41 and 15 were mainly stopped by this alarm and, as mentioned in Section 12.2.3.2, WTG 28 was particularly affected in March 2013. The alarm also occurred from February to November 2013. Many corrective actions were applied (exchange of sensors) and it is noted that the most common action was resetting the system. As stated by Gamesa the issue with the OGS (alarm code 410) was solved so that in the period from January until October 2014 this alarm was only given six times, all of these at WTG 27, as it is mentioned in /121/. Gamesa has related the OGS alarm occurrence to the inductive sensors failures. It seems that the issue has been suitably mitigated by modifying the low temperature in the thermostat and replacing the fan cooler located in the FG008 switch breaker /121/. DNV GL considers that the risk of future occurrence of this alarm has notably decreased. Nevertheless it is noted that the final solution for the root cause of the issue (inductive sensors failures), is still pending.

12.3.1.2 Converter group alarms

The most important alarm of this group is related with the main breaker FG008. The alarm has affected 13 WTGs along the wind farm operational life. Gamesa has carried out corrective actions that have provided positive results over the failure rate of the FG008 /121/. DNV GL considers the risk of high failure rates of this component has been mitigated by these actions. As is shown in Figure 12–5 the number of occurrences of the Alarm 4027 has decreased during the last months.

Figure 12–5: Number of occurrences of converter alarms

12.3.1.3 Operational status alarms

The high figure of operational status alarms was caused by occurrences in WTGs 9 and 12 during January 2013. These turbines were remotely paused for long periods. Gamesa confirmed that these pauses were mainly due to long periods of high wind speeds above the threshold of the operational range between 17 and 19 January 2013 and furthermore a circuit breaker issue recorded on 2 January 2013 and inspected on 13 January 2013, as stated in no. 9 of /121/. This explanation appears to be reasonable and the issue is not considered as critical for DNV GL.

The software system presented alarms of temperature module failure (alarm code 2106), PLC module failure (alarm code 2102) and Interbus failure (alarm code 2118). WTGs 6 and 34 were the most affected by alarm 2106 and the issue mainly occurred in January 2013. The corrective action consisted of replacing or cleaning the temperature sensor. The other two alarms occurred throughout the

0

2

4

6

8

10

12

14

Co

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[h] Alarm 4027

Alarm 4052

Alarm 4006

Alarm 4007


operational period studied. The solution to this problem usually consists of replacing the temperature module or the sensor. DNV GL was informed by Gamesa that such failures arise because the air filters in the cabinets were saturated with dust due to the environmental conditions of the area, which prevented proper ventilation of the components (sections no. 1 and 11 in /121/). As a consequence, it was decided to exchange air filters every 6 months (according to the procedure this is only performed annually) resulting in a significant decrease of this failure. It was noted by Gamesa, that there was a shortage of the temperature modules in the beginning of 2013, which worsened this issue. This shortage appears to be overcome with sufficient modules on stock at the moment. It appears that the issue is suitably mitigated.

Regarding the two issues above, it has been confirmed by Renovalia that the replacement of those modules has been carried out by Gamesa, at its own cost, thus there is no need to create a reserve account.

In Table C–9, the numbers of alarms that affected Piedra Larga wind farm are shown. The highest occurrence was caused by the “low hydraulic unit pressure” alarm (code 203). This alarm has mainly affected the WTG 6 where has taken place 143 times. The corrective action was in most cases the restarting of the turbine. The final solution consists on repairs on the hydraulic blocks of the pitch system (replacing of the joints, proportional valves, hose, etc.). DNV GL does not considers this failure rate as a risk for the project. Nevertheless DNV GL recommends whenever the wind speed allows for it, repairing the hydraulic block.

12.3.2Corrective maintenance

In order to focus on the turbine alarms, the BoP issues are not mentioned in this section. The stop time percentage of each corrective maintenance action is shown in Figure 12–6. The absolute hours figures are shown in Table C–10.


Figure 12–6: Stopped hours in Piedra Larga WTGs, caused by corrective maintenance

12.3.2.1 Corrective maintenance for operational status alarms

The highest number of corrective maintenances is shown by the operational status alarm group. The emergency stop (alarm 908), is the main cause of such percentage. The emergency stop is generally activated by the technicians when a corrective action is carried out and is not followed by an alarm. The turbines more affected by this alarm are WTG 1, 6, 13, 19, 23, 25, 38 and 41. DNV GL notes that the corrective actions are varied and do not point any specific failure in the wind turbines.

12.3.2.2 Corrective maintenance for converter alarms

The corrective maintenance of the converter system has focussed on four failures: a failure of the FG008 contactor (alarm code 4027), group converter failure INU (alarm code 4052), stator overcurrent (4006) and rotor overcurrent (4007).

Many corrective actions were taken for solving the FG008 issues (alarm 4027). Nevertheless, the longer periods in the response are not directly related to the issue but are instead related to establishing the proper solution or delays in applying the corrective action. The turbines most affected by the FG008 issue were WTGs 6, 21, 23, 29 and 41. In general, the FG008 was reset or restarted many times before correcting the root cause of the failure. Gamesa stated that most common failures in this component

Yaw sytem3%

Hydraulic Unit10%

Climate2%

Gearbox11%

Generator4%

Communication1%

Pitch5%

Operational status24%Network

connection0%

Software20%

Converter20%


were mismatched internal toroidal and damage of the drive coil, no. 2 in /121/. In order to minimize the interruption time Gamesa decided to exchange the component and send it for repair.

As it is explained in Section 12.2.3.1 alarm code 4052 was assigned to BoP issues thus this alarm does not point a specific issue in the converter system.

The corrective maintenance for overcurrent failures was, in general, caused by wearing in the slip ring generator brushes. The ultimate solution, in all cases, was to replace the brushes. This task should be carried out during the preventive maintenance and DNV GL considers that its occurrence could be the consequence of the improper application of preventive maintenance. DNV GL notes that there is room for improvement, if the replacement of the brushes is programmed for during low wind periods and during preventive maintenance.

DNV GL recommends monitoring the step-by-step procedure for solving the FG008 issues and requesting the availability of rotor bolts and proper hardware for repairs. DNV GL suggests paying special attention during preventive maintenance to the good execution of tasks related to: the FG008 and FG005 contactors, the module cables, the temperature sensor for the temperature module and the FG005 fuses.

As it is shown in Figure 12–7 the time for solving the issues related with the converter system has been reduced. According to these figures DNV GL believes that Gamesa has these failures, that have highly affected the wind farm availability during the first 8 months of operational life, under control.

Figure 12–7: Time of corrective maintenance for solving the issues related with the converter system alarms

12.3.2.3 Corrective maintenance for software alarms

The corrective actions for the alarms PLC module failure (alarm code 2102) and Interbus failure (alarm code 2118) caused longer corrective actions to the software system. Again, the common response was resetting or restarting many times before correcting the root cause of the failure. As stated in Section 12.3.1, this issue appears to be suitably mitigated.

0

48

96

144

192

240

288

336

384

432

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[h] Alarm 4027

Alarm 4052

Alarm 4006

Alarm 4007


12.3.2.4 Corrective maintenance for main wind turbine components

Regarding the main components, only a replacement of the generator of WTG 8 was reported. Reports detailing the generator change and a report detailing the tests carried out on the failed generator have been provided /118/ /119/. The generator was replaced during the period 22 March – 3 April (it is noted that the report on this replacement is dated 25 March 2013). The tests undertaken on the failed generator show an insulation failure in the stator windings. However, the root cause report was not provided in said the aforementioned report. DNV GL recommends requesting the root cause analysis report for the generator replacement in WTG 8.

In October and November 2013 blades of WTGs 1, 3, 4, 8, 18, 20, 30, 36, 40 and 41 were repaired. In December 2014 blade C of WTG27 was also repaired. DNV GL is not aware of the extent of the damage or the repairs, but it would be recommendable requesting additional information.

12.3.3 Retrofits

Gamesa has provided the description of two retrofits that were applied as a response to the failures and alarms of the wind farm:

Exchange of slip rings brushes CANT11 for CANT05/ CANT04 /123/ The strengthening of the cooling system of the generator slip rings /125/

DNV GL considers both retrofits as an appropriate and timely solution for the issues related with the generator slip rings that have caused unavailability in July 2013 (Section 12.2.5.2). DNV GL considers that these retrofits have contributed to improve the availability of the wind farm.

12.3.4 Alarms and corrective maintenance conclusions

There are two main points that should be taken into account when analysing the wind farm time stops: the time consumed by the alarms, and the time spent solving the issue that generated the alarm.

Based on the alarm information reviewed, DNV GL states the following:

The main cause of the stops and alarm occurrences were the gearbox system alarms. The alarms that have caused most of the stops in the turbines and related with the gearbox

group, are alarms 402 (low level of gearbox oil), 426 (reading failure in rotor speed) and 410 (OGS).

Alarms 426 and 410 have been remotely restarted most times. Final solution has often consisted in the replacement of the inductive sensors.

Failure rates observed in Figure 12–5 show that the converter and software alarms are being solved by the corrective and preventive actions taken by Gamesa. These alarms are not considered a risk for the Project.

The operational status alarms and it is not expected that they point any future risk for the Project.

In order to solve the alarm issues, DNV GL has noted that there is room for improvement for the wind turbines availability by means of:

- Solving possible leakages of the wind turbine gearboxes and solving low level alarm issues.


- Solving the inductive sensors issues that are linked to the OGS and reading failure in rotor speed alarms. Inductive sensors are not performing optimally during the operational life of the turbine. Most of the time the final solution for correcting the reading failure of rotor speed (alarm 426) and OGS issues (alarm 410), was replacing the inductive sensors. Reviewing the quality and design parameters of the inductive sensor with the collaboration of the nacelle assembly facility might point a final solution.

- Assuring the availability in the wind farm stock of the temperature modules for the different WTG components.

Based on the corrective maintenance information reviewed, DNV GL states:

- The time used for correcting the issues caused by converter and software alarms has dramatically decreased. DNV GL Gamesa has controlled these issues and it is not expected that they represent a future risk for the Project.

- The overcurrent failure was, in general, caused by wearing in the slip ring generator brushes, and this occurrence is probably a consequence of the incorrect application of preventive maintenance. Nevertheless Gamesa has implemented two retrofits in order to solve these issues and DNV GL observes in the failure rates and corrective actions that the retrofits are performing well.

- Improvement in the availability figures of the turbines will be achieved if the failure rate of the FG008 issues and the related repairing time is reduced. DNV GL is aware that Gamesa is working in order to improve those figures.

In order to solve or improve the corrective maintenance issues, DNV GL recommends:

- Carrying out the replacement of the slip ring generator brushes during low wind periods and during preventive maintenance.

- Monitoring the step-by-step procedure to solve the FG008 issues and requesting the availability of rotor bolts and proper hardware for repairs. DNV GL suggests paying special attention, during preventive maintenance, to the proper execution of tasks related to: the FG008 and FG005contactor, the module cables, the temperature module temperature sensor, and the FG005 fuses.


13 CONCLUSIONS AND RECOMMENDATIONS

The following conclusions and recommendations refer to the operational review described in Sections 2.3 and 12.

13.1 Operational evaluation

DNV GL has performed a long-term energy yield forecast for the Piedra Larga I Wind Farm in Oaxaca (México). Piedra Larga I is composed of 45 Gamesa G80 turbines at a hub height of 67 m. Piedra Larga I has been in operation since October 2012 and the wind farm was commissioned in December 2012. The operational assessment, based on monthly production data, covers the period from January 2013 to March 2015.

In an additional estimation of the long-term energy production, DNV GL has assessed SCADA data from January 2013 to March 2015.

DNV GL has considered the use of the La Venta 3 and M1 reference masts, together with the on-site Mast M5, as valid for obtaining a final time series covering the period from January 2002 to March 2015.

The following information has been considered in the study:

A monthly time series of production data, metered at the point of grid connection, was obtained from the monthly Delivered Energy data, for the period from January 2013 to March 2015.

Monthly availability values RTAE100, estimated by DNV GL on the basis of SCADA data and alarms and electrical incidences information.

Monthly performance of power curves, estimated by DNV GL on the basis of SCADA data.

Energy gains after the installation of the “Energy Thrust” and “Safe Mode” strategies, a figure of 2.85% measured and estimated by Gamesa based on 1 year of data.

Operational data, recorded and corrected for availability and performance periods, were combined with the synthesised data from the long-term reference source for each scenario, defining a final period of 12.8 years of valid data.

The projected net energy production of the Project is estimated to be 325.7 GWh/annum at Piedra Larga I.

It is considered that, having a suitable source of data, the estimated long-term energy production is much more reliable, and it could be used as a reference for valuation of the wind farm.


The uncertainty analysis results are presented in Table 13–1 below.

Table 13–1: Confidence limits of net energy yield predictions – Piedra Larga I

Probability of

Exceedance [%]

Net Energy Output Piedra Larga I

[GWh/annum]

1-year Average 10-year Average

99 249.5 281.6

90 283.7 301.4

75 303.6 312.9

50 325.7 325.7

P90/P50 87.1% 92.5%

The SCADA data have been assessed in detail, with the objective of verifying if the power performance and availability levels of the turbines observed over the operational period has been representative of long-term expectations. Where issues have been identified, associated energy losses have been quantified and factored out of the production figures, as necessary.

The following observations have been made regarding the historical performance of the wind farm:

A range of measures of the historical availability have been reviewed and it is considered that the measure of availability that most closely represents the proportion of energy lost due to the wind farm being unavailable is the energy-weighted RTA - adjusted for data loss (RTAE100), and amending the initial months which were affected by a problem with the SCADA recording. For the period from January 2013 to March 2015, the average monthly RTAE100 was 94.3%. This measure has been validated against information provided by the Customer and presented in the monthly operational reports.

The average monthly power curve efficiency during the period from January 2013 to December March 2015 was 99.0%.

The following observations have been made regarding the future performance of the wind farm:

A standard assumption of 96.0% has been assigned to the wind farm system availability; this value includes consideration of the turbines, balance of plant and grid availability.

A value of 99.3% has been assigned to future turbine performance, based on the assumption that some of the intermittent performance issues will not re-occur.

These factors could change in the future, when more data become available, depending on wind farm performance. It is recommended that continuous wind turbine performance and availability monitoring is conducted, in order to optimize the wind farm performance and to validate these figures.

A formal IEC 61400-12-1 power performance test has been conducted. The performance test results show that the wind turbines are performing within the warranted levels, but with an annual energy that is 4.3% below that expected for the warranted power curve.


According to the information presented by the Customer /19/, the manufacturer is offering to improve the energy produced per wind turbine by making several changes in the control strategies (with a maximum energy gain of 3%); manufacturer is recommending as well a loads analysis. The Customer has presented information for these retrofits already installed, stating that during 1 entire year the energy gains were 2.85%. DNV GL has estimated the potential energy variations (assuming a global energy gain of 2.85%, the figure provided after 1 year of measurements at the site), already considered in Table 13–1.

13.2 O&M report review

The general conclusions of the O&M review are as follows:

Regarding preventative maintenance, some inconsistences were noted in the reviewed information /8/ /9/ /10/ /11/ /12/ which are detailed in Section 11.

The scheduled dates for carrying out preventative maintenance /10/ exceed the contractual periods.

The 48h ratio established in the O&M contract /8/ for preventive maintenance was not exceeded.

The BoP issues /11/ were mostly related to deficiencies in the electrical substation. The number of failures during the first 4 operational months which affected the wind farm electrical infrastructure is above the normal failure rate for the initial operational months of the wind farms.

The reported monthly availability and production figures of the O&M reports /10/ are inconsistent, prior to August 2013.

From January to April 2013 the BoP issues /11/ had a significant impact on the availability and production figures. Nevertheless, all the issues have now been solved.

The main cause of the stops and alarm occurrences were the gearbox system alarms. The alarms that have caused most of these stops are alarms 402 (low level of gearbox oil), 426 (reading failure in rotor speed) and 410 (OGS). The alarm 426 and 410 has been remotely restarted most times. Final solution has often consisted in the replacement of the inductive sensors.

Failure rates of converter and software alarms observed in Figure 12–5 shows that related issues are being solved by the corrective and preventive actions taken by Gamesa. These alarms are not considered a risk for the Project.

The operational status alarms were caused by specific reasons and do not point any future risk for the Project.

The time used for correcting the issues caused by converter and software alarms has dramatically decreased. DNV GL Gamesa has controlled these issues and will not represent a future risk for the Project.

The overcurrent failure was, in general, caused by wearing in the slip ring generator brushes, and this occurrence is probably a consequence of the incorrect application of preventive maintenance during the initial operational period, combined with the ring generator brushes


installed at that stage. Nevertheless Gamesa has implemented two retrofits in order to solve these issues and DNV GL observes in the failure rates and corrective actions that the retrofits are performing well.

Improvement in the availability figures of the turbines will be achieved if the failure rate of the FG008 issues and the related repairing time is reduced. DNV GL is aware that Gamesa is working in order to improve those figures.

In Sections 12.1.7, 12.2.7 and 12.2.7, DNV GL recommends specific actions that are recommended for solving the wind farm issues and improving the wind farm performance.


14 REFERENCES

/1/ Report 230417-ESZA-R-01-E, dated 31/01/2013.

/2/ "Propuesta para el análisis operacional de los Parques Eólicos Piedra Larga I y II en Oaxaca (México), document GL GH 230963-ESZA-P-01-C, 14 May 2014.

/3/ "Technical review of Piedra Larga Wind Farm in Oaxaca (México), document GL GH 230417-ESZA-R-01-E, 31 January 2013.

/4/ Information provided via a ftp connection by Pablo Royo (Renovalia), between 11 May and 03 June 2014.

/5/ E-mail from Gamesa to Renovalia, dated 05/05/2014.

/6/ File NE8291322_CARGA DE VERSION DE CONTROL 12D23 SP5 _PIEDRA LARGA_ .pdf “Carga de versión de control 12d23 sp5 (Piedra Larga)”, dated 10/06/2013.

/7/ File BRN023-14-P.E.Piedra Larga-Verificación de garantías_v02.pdf “Verificación de Garantía Parque Eólico Piedra Larga”, dated 24/03/2014.

/8/ O&M Contract between DEMEX and GESA Mexico, dated November 26, 2010.

/9/ O&M Plan. Complete machine G8X-000-31-00-00-00-0-320-0-F. Gamesa. Code DM001754. Rev: 01, dated 08/06/2010.

/10/ O&M reports for the period from January 2013 to December 2014. Monthly reports of Piedra Larga I wind farm. Client: DEMEX /RENOVALIA. Gamesa. Road from Unión Hidalgo – La Venta s/n. Unión Hidalgo, Oaxaca (Mexico).

/11/ Excel sheets with corrective maintenance for the Piedra Larga I wind farm Balance of Plant.

/12/ Excel sheets of monthly management reports of alarms and availability for the Piedra Larga wind farm. From January 2013 to April 2014. Renovalia.

/13/ Technical review of Piedra Larga wind farm in Oaxaca, Mexico. Document No. 230417-ESZA-R-01. Issue D, 12 December 2012.

/14/ Navigant (former BTM Consult ApS), BTM World Market Update 2013 and previous issues of the BTM World Market Update.

/15/ “Maximización de disponibilidad en la plataforma G8X: MDs” Gamesa presentation 26/04/2011 for DNV GL use

/16/ “Gamesa G97-2.0MW Mejoras Tecnológicas vs G90”. Marketing department, 09/09/11, for DNV GL use,

/17/ Meeting between Gamesa and DNV GL Ibérica in Gamesa’s principal Spanish offices in April 2012.

/18/ GL Garrad Hassan, “Position on Turbine Reliability Risk Assessment: Proven and Qualified Turbine Designs and Turbine Availability in North America”, 5 January 2011. Available on the Internet at http://www.gl-garradhassan.com/assets/downloads/GL_Garrad_Hassan_memo_on_availability_and_proven_qualified_turbines.pdf.

/19/ File NE PiedraLarga1.pdf "AEP Increase due to Energy Thrust & re-start speed modification for Piedra Larga 1", dated 18/07/2013.

/20/ Technical Note regarding loading the software version 12D23 SP5 against 12D23_SP3 for controlling the wind turbine PLC “Ref.: NEW8291322”, dated 10/06/2013.

/21/ Gamesa report of changes in the software version for controlling the PLC R12D23_SP8 versus R12D23_SP5. Date 04/02/2013. Reference ITE8P291323.

/22/ BTM Consult ApS, “International Wind Energy Development, World Market Update 2011,” March 2012.

/23/ Gamesa, General Specifications and characteristics of Gamesa G9X-2.0 MW wind turbines. Rev 4. Date 2/05/2011. Author: MDAndres.


/24/ Gamesa Presentation about the “Maximization of the availability of the Platform G8X:MDs”, dated 24/06/2011.

/25/ Marketing report. Availability report- Q1 2011. Rev 1.0, dated 09/05/2011. Author MR.

/26/ Marketing report. Availability report- Q1 2012. Rev 1.0, dated 02/05/2012. Author BA/MR.

/27/ Design, Calculation & Compliance Report. 24/11/2008. Gamesa. Rev 1.

/28/ G80/G87 2MW 50/60 Hz Wind Turbine Power Curve. General Characteristics Manual. Rev 0, dated 20/09/2010.

/29/ Type Certificate. Det Norske Veritas. G80-2MW IEC IA 50/60Hz. Number TC-GL-025A-2007, dated 2010-11-1. Valid until 31-10-2012.

/30/ Installed capacity of the principal suppliers in Spain. http://www.aeeolica.org/es/sobre-la-eolica/la-eolica-en-espana/potencia-instalada/

/31/ Presentation of Gamesa Results. January- December. 2011 Results. Strength of results and progress in the Business Plan 2011-13. Date 23/02/2012. Madrid, Spain.

/32/ Gamesa Technology Corp. Inc., Company Overview, Document F11-14-PR007 v2.0, not dated.

/33/ Gamesa, General presentation. Dated March 2012. Delivered to DNV GL by the Customer.

/34/ Gamesa, Technology improvements of the G9X. Marketing department. Dated 9/09/2011.

/35/ Gamesa Technology Corp. Inc., General description of the standard predictive maintenance system SMP-8C, Document # FT050008-en, Rev. Dated 2 and 27 November 2008.

/36/ Gamesa Technology Corp. Inc., Doubly Fed System and Grid Connection Solutions, Document # GD051047-EN, Rev 1, 26 April 2010.

/37/ Gamesa Technology Corp. Inc., Description of the oversized converter system with Brake Chopper, Document # GD073402-EN, Rev 0, 26 April 2010.

/38/ Energy to Quality S.L., Low Voltage Ride Through Field Tests Report – La Plana I, Document # IN2008-011, Rev. 02, 6 May 2008.

/39/ Gamesa Technology Corp. Inc., PSSE Model Validation Report, Document # GD080835-EN, Rev 1, 1 December 2011.

/40/ Summary of results of the noise emission measurement, in accordance with IEC 61400-11, of a WTGS of the type. Sierra de Alaiz PROTO-1. Dated 2011-08-24. Order No. 4286 11 07939 258.

/41/ GL Garrad Hassan, “Position on Turbine Reliability Risk Assessment: Proven and Qualified Turbine Designs and Turbine Availability in North America”, 5 January 2011. Available on the Internet at http://www.gl-garradhassan.com/assets/downloads/GL_Garrad_Hassan_memo_on_availability_and_proven_qualified_turbines.pdf.

/42/ Meeting with Gamesa in the Pamplona Offices on 16/2/2012 in order to discuss the improvements of the wind turbine Gamesa G9X versus the wind turbine Gamesa G8X.

/43/ Gamesa Innova Presentation. New Gamesa G9X-2.0MW. Husum, 23 September 2010.

/44/ Guideline for the Certification of Wind Turbine, GL 2010. Appendix 1.E National Requirements in India. IV-Part 1. Chapter 1. 1.E. 3.

/45/ Query agenda between and Gamesa. Excel sheet forwarded to DNV GL on 21/7/2012.

/46/ “Nacelle instrumentation – environmental condition sensors G8X-G9X-11-01-00-00-0-100-0-F”. Code: DM008360-en. Rev 01. Dated 26/10/2011.

/47/ 5.2.3 Phase 1 and 2 EPC Agreement_Annex D_Turnkey supply agreement, between Desarrollos Eólicos Mexicanos de Oaxaca 1 (DEMEX 1) and GESA Eólica México (GESA), dated 23 December 2009.

/48/ Annexes A to Z of the Phase 1 and 2 EPC Agreement.

/49/ 5.2.4 Phase 1 EPC Agreement_Annex D_Turnkey supply agreement, between Desarrollos Eólicos Mexicanos de Oaxaca 1 (DEMEX 1) and GESA Eólica México (GESA), dated 26 November 2010.


/50/ Annex A to Z of the Phase I EPC Agreement.

/51/ Annex U-3- Propuesta Licitante (Tendering offer), Technical Report AE_RENOVALIA_MEXICO_PIEDRA LARGA, Gamesa Eólica, dated 16/09/2009.

/52/ Annex L – Start up and Trial Test Conditions.

/53/ O&M agreement for Desarrollos Eólicos Mexicanos de Oaxaca 1, S.A. de C.V and GESA Eólica de México S.A de C.V (Anexo X. Contrato de Operación y mantenimiento del Parque Eólico con posterioridad Periodo de Garantía; Rev. 6/ 26 de noviembre de 2010). Dated 26 November 2010 (signed version).

/54/ Contrato de autoabastecimiento de energía eléctrica entre "Desarrollos Eólicos Mexicanos de Oaxaca, 1, S.A. de C.V. and several companies from the Bimbo Group.

/55/ First Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in July 2009.

/56/ Second Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in February 2010.

/57/ Third Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in September 2010.

/58/ Fourth Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in November 2010.

/59/ Fifth Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in June 2010.

/60/ Sixth Convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed by Desarrollos Eólicos Mexicanos de Oaxaca 1, s.a. de c.v and several companies from the Bimbo group, signed in January 2012.

/61/ Contrato de autoabastecimiento de Energía Eléctrica entre DEMEX II y Wal-Mart, Suburbia y VIPS firmado, el 29 de Agosto de 2011.

/62/ Primer convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed between Desarrollos Eólicos Mexicanos de Oaxaca 2, S.A.P.L. de C.V. and several companies of Wal-Mart de México, S de R.L. de C.V, signed in March 2012.

/63/ Segundo convenio modificatorio al contrato de autoabastecimiento de energía eléctrica signed between Desarrollos Eólicos Mexicanos de Oaxaca 2, S.A.P.L. de C.V. and several companies of Wal-Mart de México, S de R.L. de C.V, signed in September 2012.

/64/ Data room folder 7.1.10: Gamesa, “Characteristics and general operation of the wind turbine platform”GD005900-en, 15 December 2008.

/65/ FTP Server, Folder 155. Wind farm engineering: GES, “Electrical circuits arrangement for Piedra Larga (Fase I – 90MW)I”, 10PIE-3UNX0.001-RA06, 29 August 2009.

/66/ Data room folder 7.2.1.1.3. Wind farm. GES, “Preliminary study of voltage drops and power losses”, 120203 PE Piedralarga Gamesa G8X – CT (XLPE (R5).pdf, 3 February 2011.

/67/ Data room folder 7.2.1.1.2 SE DMX. “Parque Eólico Piedra Larga Subestación Demex. Diagrama Unifilar Simplificado”, DEMEX-SE-DEM-E-PL-01, February 2012.

/68/ Data room folder 7.2.1.1.2 SE DMX. “Parque Eólico Piedra Larga Subestación Demex. Diagrama Unifilar de protecciones”, DEMEX-SE-DEM-E-PL-01, November 2010.

/69/ Data room folder 7.2.1.1.2 SE DMX. “Parque Eólico Piedra Larga Subestación Demex. Diagrama de conectividad”, DEMEX-SE-DEM-E-PL-01, March 2011.

/70/ Data room folder 7.1.7.1 100929 dossier común. Contrato entre Iberdrola Ingeniería y Construcción S.A. de C.V. y Prolec GE Internacional, S.R.L. de C.V. para la contratación de:


suministro, transporte, montaje y pruebas de puesta en marcha de los transformadores trifásicos 50MVA 230/34.5kV de la subestación SE Piedra Larga (México), 27 April 2010.

/71/ Data room folder 7.1.7.1. 100929 dossier común. Bureau Veritas, “Reporte de Inspección Nº R-IND-MEX-463/10”, 18 January 2011.

/72/ Data room folder 7.1.7.1. 100929 dossier común. Bureau Veritas, “Reporte de Inspección Nº R-IND-MEX-587/10”, 18 January 2011.

/73/ Comisión Federal de Electricidad, “Requerimientos para interconexión de aerogeneradores al sistema eléctrico mexicano (código de Red)”.

/74/ Secretaría de Energía, Resolución RES/119/2012, Reglas Generales de Interconexión al Sistema Eléctrico Nacional para generadores o permisionarios con fuentes de energía renovables o cogeneración eficiente, 22 de Mayo de 2012.

/75/ Data room folder 7.2.1.1.1 LT DMX-IPO. Iberdrola Ingeniería y Construcción, “Memoria de cálculo del parámetro Conductor, Guarda y CGFO”; DEMEX-LT-DIP-E-ME-002, 1 February 2011.

/76/ Data room folder 7.2.1.1.4 SE IPO, “Diagrama unifilar simplificado. Parque Eólico Piedra Larga SE Ixtepec Potencia”, DEMEX-SE-IPO-E-PL-001, February 2011.

/77/ Data room folder 7.1.11. Alberto Hijas Rodrígues, Gamesa Eólica S.L.U, “Valoración instalaciones compartidas entre los proyectos eólicos Demex Oaxaca I (Piedra Larga Fase I) y Demex Oaxaca II (Piedra Larga Fase II)”, 29 June 2012.

/78/ Notification from the SCT (Secretaria de Comunicaciones y Transporte, Dirección de Aeronáutica Civil –Aviation Authority-), dated 3 March 2010.

/79/ Document S.G.P.A./DGIRA.DG.3901.08, dated 19 December 2008.

/80/ Document SGPA/DGIRA/DG/2475/10, dated 7 April 2010, modifying the type and number of wind turbines to be installed in Phase 1 (so-called DEMEX II), from 65 turbines of 1,500kW to 45 units of 2 MW.

/81/ Cimentaciones de la Torre G80 2MW HH67m (Gamesa) para el P.E. Piedra Larga (Mexico). (Foundations for the G80 2MW HH67m for the Piedra Larga wind farm) 04/06/2010. REV. 1.0, made by Esteyco Energía.

/82/ Estudio de Mecánica de Suelos para el Parque Eólico Piedra Larga (soil mechanics studies), dated March 2010, issued by Geogrupo. According to this report, test drillings have been conducted in 23 positions.

/83/ Estudio de Mecánica de Suelos para el Parque Eólico Piedra Larga (soil mechanics studies), dated April 2010, issued by Geogrupo. According to this report, test drillings have been conducted in the remaining 22 positions, plus a second test in position 44.

/84/ Ensayos de carga de tipo presiométrico para el Parque Eólico Piedra Larga (presiometric tests), dated April 2010, issued by Geogrupo. According to this report, test drillings have been conducted in 23 positions.

/85/ Ensayos de carga de tipo presiométrico para el Parque Eólico Piedra Larga (presiometric tests), dated Feb 2012, issued by Geogrupo. According to this report test drillings have been conducted in 14 positions. Provided on 3 December 2012.

/86/ Ampliación del Estudio Geotécnico del terreno en varias posiciones para el P.E. Piedra Larga, dated Aug 2011, issued by Geogrupo. According to this report, test drillings have been conducted in 6 positions. Provided on 3 December 2012.

/87/ Monthly construction report, dated April 2011, issued by GES and Iberdrola.

/88/ Black&Veatch report, dated June 2011.

/89/ Works Schedule, dated 1 June 2011.

/90/ Works Schedule Rev 2, dated 15 June 2011.

/91/ Interconnection agreement signed between DEMEX and CFE on 28 May 2010.

/92/ Second Interconnection Agreement, signed between DEMEX and CFE on 25 September 2012.

/93/ Of. Num. FGB'224'12 Autorización Operación Normal.


/94/ Self Supply Permit 823/AUT/2009, issued by CRE on 4 June 2009.

/95/ Resolution from CRE modifying the self-supply agreement, 15 February 2010.

/96/ Self-supply Permit E/939/AUT/2012, issued by CFE on 27 July 2012.

/97/ Transmission Line Agreement between CFE and DEMEX “6.1.3.2 20081222 Convenio CFE_fdo”, dated 18 December 2008.

/98/ Amendment to the Transmission Line Agreement between CFE and DEMEX “6.1.3.3 20090924 convenio modificatorio CFE”, dated 24 September 2009.

/99/ Excel files “Analisis del SCADA”; “FICHA CAP Piedra Larga6”; “FICHA CAP Piedra Larga11” and “FICHA PARQUE Piedra Larga parque 3”.

/100/ Site Suitability Study conducted by Gamesa “GD119358 R4_AE_RENOVALIA_MEXICO_PIEDRA LARGA (FASE II)”, dated 20 September 2012.

/101/ Demostración cumplimiento hueco de tensión mexicano (compliance with Mexican voltage dip), doc F11-11-ECM317 v1.0, dated 17.10.2012, issued by Gamesa.

/102/ Low Voltage Ride Through Field Tests Report, according to the German Grid Code published by the German Transmission System Operator, E.On (April 2006), dated 05/11/2007.

/103/ Ing. Germán Hernández González, Dirección de Operación Subdirección Subdirección del CENACE (Área de Control Oriental), “Autorización de inicio de operación normal del Parque de Desarrollos Eólicos Mexicanos de Oaxaca 1”, 1 November 2012.

/104/ Siemens, “Control System Sicam Pas tests”, Pruebas DAG’S0001.pdf, 17 June 2012.

/105/ “Medición de armónicos SE Ixtepec Potencia con carga [1].pdf”, 13 September 2012.

/106/ FICHA CAP Piedra Larga.11.xls, provided on 22.11.2012.

/107/ Analisis del SCADA.xls, provided on 22.11.2012.

/108/ FICHA CAP Piedra Larga parque 3.xls, provided on 22.11.2012.

/109/ GL Garrad Hassan (formerly Windtest Iberica S.L.). Certification report no: WT 3913/04. Measurement of power curve on a Gamesa G80-2.0MW at Carrasquillo, V2 (2nd mode, G8Xv1_xxV). Dated 23/12/2004.

/110/ GL Garrad Hassan (formerly Windtest Iberica S.L.). Certification report no: WT4530/05. Measurement of power curve on a Gamesa G87-2.0MW at Almendarache, A10. Dated 16/09/2005.

/111/ Curva de Potencia G87 2MW 50/60 Hz. GENERAL CHARACTERISTICS MANUAL (GCM). Gamesa Code GD022922-es. Rev: 4. Author: LGR. Dated 15/06/10.

/112/ G80 Curva de Potencia. DESIGN, CALCULATION & COMPLIANCE REPORT. Gamesa Code GD022920-es. Rev: 1. Author: MJL. Dated 24/11/08.

/113/ Signed version of the EPC contract for Phase 2 of the “Piedra Larga” wind farm of 132.5 MW, between Desarrollos Eólicos Mexicanos de Oaxaca 2 (DO2) y GESA Eólica México (GESA), signed on 2 January 2013 [document “Contrato EPC_Demex2 y Gesa 121228_vf.pdf”, provided by First Reserve on 11.01.2013], and annexes.

/114/ Site-specific study from Gamesa, for Phase I, document GD117701, dated 21/12/12. Received on 28 January 2013.

/115/ PAC of Phase 1, provided on 14/01/2013, and signed on 26/12/12.

/116/ Letter from Gamesa, dated 18 December, stating the validity of the new Phase 1 layout.

/117/ Semarnat Document S.G.P.A/D.G.I.R.A/D.G./5800 dated 2 August 2011 provided on 19/11/2014.

/118/ Informe pruebas realizadas en generador AEG 08, 19 de marzo de 2013.

/119/ Informe de cambio de generador AEG 08, 25 de marzo de 2013.

/120/ Diagram of electrical installations, file name: "20120224 Poligono Piedra larga Fase I layout 6.2 FINAL.dwg", provided on 21 November 2014


/121/ Gamesa's response on open issues stated in the Garrad Hassan Operation Analysis of the Piedra Larga I&II Wind Farms (document no. 230963-ESZA-R-01-B, dated 26 August 2014), dated 1 December 2014

/122/ Letter from Gamesa dated on 18/12/2012

/123/ External note “exchange of brushes CANT11 for CANT05/ CANT04 en LATAM wind farms”. Corporative services engineering. Date 28/01/2014

/124/ External note “strengthening for the cooling system of the generator slip rings”. Service engineering. Date 23/01/2013

/125/ Information provided via a ftp connection by Pablo Royo (Renovalia), between 21 and 23 January 2015, with operational data for the period May-December 2014

/126/ Letter from DEMEX and with reference 3901.08, dated 17 August 2012, about the Building Activities Ending

/127/ Email from P Royo, from Renovalia, dated 23 December 2014

/128/ Information provided via a ftp connection by Pablo Royo (Renovalia), on 18/05/2015, with operational data for the period January to March 2015

/129/ File 12 Piedra_Larga_I20161219DNV.pdf "Energy Thrust-Performance report”, dated 19/12/2016, provided by email from Pablo Royo, from Renovalia 17 March 2017.

/130/ Document “NE8311612_G8X_INCREMENTO CARGAS ET_Piedra_Larga_II.pdf” dated 17 June 2016 and “a Carta Piedra Larga Fase II.pdf” , dated 28 October 2015

/131/ Addendum to “Anexo X. Contrato de Operación y mantenimiento del Parque Eólico Piedra Larga I con posterioridad Periodo Garantía, Rev.6”, dated 30 June 2015

/132/ Proposal for Revergy for the O&M services for Parque Eólico Piedra Larga I, sent by e-mail on the 4 April 2017


APPENDIX A: AVAILABILITY DURING LOSS OF SCADA COMMUNICATIONS

For the period from January 2013 to May 2014, the SCADA data coverage at the Piedra Larga I Wind Farm was 86.0%. DNV GL has therefore investigated the availability during periods of SCADA communications loss.

It is commonly assumed that the average turbine availability during loss of SCADA communications is the same as the average during full SCADA communications. In DNV GL’s experience this is often not the case; there are many situations where data loss may result from turbine downtime.

DNV GL has investigated the amount of production observed during periods of SCADA communications loss, by investigating the production metered at the point of grid connection. The data coverage of the metered data at the point of grid connection was assumed to be 100%.

If it is assumed that wind speeds (hence, production) in a given month are average over the period of data loss, an indicative estimate of availability during periods of data loss can be made. It is considered reasonable to assume that SCADA data loss is not strongly correlated to wind speed.

Availability during periods of data loss has been estimated, based on a comparison of the sum of the production (measured at the base of the turbines over the period of SCADA data coverage) with the monthly meter readings (100% data coverage). The sum of production at the turbine bases was multiplied by the measured electrical efficiency (derived in Section A.2), to ensure that the two measurements are comparable.

A.1 Adjusted RTA

The following equations illustrate the calculation made by DNV GL to estimate availability during SCADA communications loss.

If it is assumed that wind speeds and turbine power performance were the same during periods of SCADA communications and periods of no SCADA communications, it would be reasonable to say that the following would be true:

(Eq A1)

Where:

Pc = sum of turbine production during periods of full SCADA communications [MW.h] D = data coverage of the SCADA system, as a percentage of total time [%] Ac = availability measured over a period of full communications [%] Plc = sum of turbine production during periods of SCADA communications loss [MW.h] Alc = availability estimated during periods of loss of SCADA communications [%]

Plc and Alc are both unknowns. However, Plc can be estimated by calculating the electrical efficiency of the network and applying the production measured at the point of grid connection. The assumption made is that there is 100% coverage of the data metered at the point of grid connection.

Plc can be estimated using the following formula:

(Eq A2)

lc

lc

c

c

AD

P

AD

P

1

clc PE

GP 100


Where:

G100 = production measured at the point of grid connection (100% data coverage) [MWh] E = measured electrical efficiency of the internal wind farm network [%]

By incorporating equation A2 into equation A1 and rearranging, the following equation is derived:

(Eq A3)

The above equation is valid within the following limits, because availability is always a positive number and is less than 100%:

0% <= Alc <= 100% (Eq A4)

Equations A3 and A4 were applied on a monthly basis, and showed a positive correlation between data loss and production loss. Therefore, it is concluded that when data are missing from the SCADA system, the wind farm has lower availability (in general) than when the SCADA is fully communicating.

In order to estimate the RTA over the whole month, the following equation is applied:

)1(100 DADARTA lccT (Eq A5)

A.2 Availability dependence on wind speed (RTAE)

In DNV GL’s experience, in certain circumstances periods of downtime may be dependent on wind speed. In such circumstances, the time-weighted availability will not be fully representative of the energy loss incurred during the period of downtime in question.

DNV GL has calculated the energy-weighted RTA (RTAE) for each month in the operational period, using the following method:

1 DNV GL assessed the correlation between turbine downtime and wind speed by calculating the RTAT in each 1 m/s wind speed bin over the wind speed band 4 m/s to 25 m/s, for each month in the operational period, as shown in Figure A.1. It can be seen that there is a significant correlation between downtime and wind speed in some months.

2 For each month in the period, a wind speed frequency distribution was derived from the nacelle anemometer wind speed signals recorded at all the turbines.

3 A nominal power curve was applied to the wind speed frequency distribution, in order to obtain a nominal energy distribution for each month.

4 For each month, the RTAT profile shown in Figure A.1 was applied to the nominal energy distribution, in order to derive a measure of energy production, taking the observed availability profile into account.

5 The energy weighted RTA, or RTAE, is defined as the ratio of the total RTAT adjusted energy production (defined in Step 4, above) to the total unadjusted nominal energy production (defined in Step 3, above).

6 An energy adjustment factor has been derived by dividing the RTAE by the RTAT calculated in Section A.1.

)1(

100

DP

PE

GDA

Ac

cc

lc


Figure A.1: Comparison of different measures of availability at the Piedra Larga I Wind Farm

A.3 Energy weighted RTA adjusted for loss of SCADA communications (RTAE100)

The energy weighted RTA adjusted for data loss (RTAE100) is calculated by factoring the measure of RTAT100 by the ratio between RTAT and RTAE, such that:

(RTAE100) = RTAT100 × (RTAE / RTAT)

A.4 Calculation of electrical efficiency

DNV GL has estimated the electrical efficiency of the internal wind farm electrical network of both wind farms, by comparing production at the substation with the sum of production measured at the turbines when there was high data coverage of the 10-minute SCADA database.

This correlation was performed on a monthly basis, using the energy delivered monthly only for the data after October 2013, when the aforementioned problem with the SCADA recording was solved /5/. By this method, a loss factor of 96.0% has been estimated for the average measured electrical efficiency of the Piedra Larga I Wind Farm.

It is noted that these estimates are a relative measure of electrical efficiency, based on turbine and grid metering systems that are subject to uncertainty. These factors should therefore only be considered as relative conversion factors, for estimating production at the grid connection point from production measured at the turbines, rather than absolute and accurate measures of the true electrical efficiencies.


Figure A.2: Metered production vs. SCADA production at the Piedra Larga I Farm


APPENDIX B: UNCERTAINTY ANALYSIS (OPERATIONAL ANALYSIS)

There are 8 main categories of uncertainty associated with the methodology used to estimate the long-term production for the Piedra Larga I Wind Farm:

Consistency of the long-term reference;

Applied correlation to the long-term reference;

Energy loss factor assumptions;

Power performance adjustments;

Availability adjustments;

Wind rose variability;

Historical wind speed variability;

Future wind speed variability.

B.1 Consistency of the long-term reference

Uncertainty is associated with minor inconsistencies in the instrumentation at the long-term wind speed reference stations; including periodic anemometer replacement and degradation of instrumentation over long periods. This is defined as a wind speed uncertainty of 2.0% of the fraction of production data synthesized for the Piedra Larga I Wind Farm.

B.2 Applied correlation to the long-term reference

There is uncertainty in applying the correlation to the reference in order to synthesize historical production at the site. This element of uncertainty has been estimated by selecting half of the database of mean daily adjusted production figures (Dataset A) and applying the correlation method (using the monthly wind speeds at the reference) to predict the sum of production for the other half of the monthly production database (Dataset D). The error in this prediction is established by comparing actual production over the period, concurrent with Dataset B, with the sum of predicted production (Sum of Dataset D).

This process is repeated for 2,500 random combinations within the database of monthly production. The uncertainty element is then estimated by taking the standard deviation of these errors. The estimated uncertainty is then multiplied by the fraction of production data actually synthesised.

B.3 Energy loss factor assumptions

There is an uncertainty associated with the assumption that the applied loss factors (including those representing the future availability and future performance of the turbines) will be representative of the long term. A pragmatic uncertainty of 1% has been applied for this factor.

B.4 Power performance adjustments

Where the production data has been factored for long-term expected levels of power performance, there is uncertainty associated with the calculation of losses and the factoring method. This element of


uncertainty has been estimated, based on the magnitude of total adjustment made to the production data.

B.5 Availability adjustments

Uncertainty is also associated with the calculation of losses where the production data has been factored for long-term expected levels of availability. This element of uncertainty has been estimated, based on the magnitude of the total adjustment made to the production data.

An additional, pragmatic, factor of 1.5% has been applied to the Piedra Larga I Wind Farm, in order to account for the reliability of the availability measurement itself. This is based largely on the extent to which the measure has been validated by alternative sources of data.

B.6 Wind rose variability

A period of 1 year of operational data has been used in the forecast of the long-term energy production of the Piedra Larga I Wind Farm. Whilst a correction has been made in order to account for the windiness of the operational period, relative to long-term conditions, the shape of the wind rose and other prevailing flow conditions over the operational period remain inherent within the long-term production forecast. There is therefore an uncertainty associated with the assumption that the wind rose which prevailed over the operational period is representative of long-term conditions. An uncertainty of 1.0% has been included, in order to account for this uncertainty at the Piedra Larga I Wind Farm.

B.7 Historical wind speed variability

There is an uncertainty associated with the assumption made here that the historical period of wind speed at a site is representative of the climate over longer periods. A study of historical wind records [B1] indicates a typical variability of 6% in the annual mean wind speed. This figure is used to estimate the uncertainty of assuming that the long-term mean wind speed is defined by the period of data used in this analysis. The sensitivity of changes in mean wind speed to energy production has been estimated using a simple perturbation analysis from the SCADA data.

B.8 Future wind speed variability

Additionally, even if the long-term mean wind speeds were perfectly defined, variability in future mean wind speeds would be observed at the wind farm site. The variability in future mean wind speeds is dependent on the period considered. In this analysis, the future periods considered are 1 year and 10 years.

B.9 Combination of uncertainties

The uncertainties described in Sections B.1 to B.8 are added as independent errors on a root-sum-square basis, in order to give the total uncertainty in the projected energy output. The total uncertainty for a 1-year and a 10-year period, respectively, is used to derive the probability of exceedance levels.

B.10 Probability of exceedance levels

The probability of exceedance levels have been derived from the total uncertainties described in Section D.9, which represent one standard error of what is assumed to be a Gaussian process. The probability of exceedance is reported for 50% (the central estimate), 75% and 90% (for 1 year and 10 years).


References

B1 P Raftery, A J Tindal and A D Garrad, “Understanding the risks of financing wind farms”, Proc. EWEA Wind Energy Conference, Dublin, 1997.


APPENDIX C: O&M REPORT REVIEW

Table C–1: Preventive maintenance dates MAINTENANCE 12 MAINTENANCE 13 3-month maintenance 6-month maintenance 12-month maintenance WTG COM. Date REV3 P R P R P R

1 31/08/12 24/09/12 15/10/12 27/08/13 15/04/13 03/04/13 09/09/13 25/09/13 2 17/09/12 20/09/12 15/10/12 02/09/13 15/04/13 08/04/13 09/09/13 27/09/13 3 31/08/12 21/09/12 17/10/12 04/06/13 17/04/13 25/06/13 11/09/13 02/10/13 4 04/09/12 04/09/12 14/11/12 03/06/13 15/05/13 10/04/13 11/09/13 11/10/13 5 18/09/12 31/07/12 14/12/12 21/05/13 14/06/13 09/05/13 13/09/13 11/10/13 6 27/07/12 21/08/12 04/12/12 22/05/13 04/06/13 10/05/13 13/09/13 21/10/13 7 17/09/12 04/09/12 17/10/12 04/06/13 17/04/13 16/07/13 17/09/13 16/11/13 8 06/09/12 12/09/12 19/10/12 04/06/13 19/04/13 09/08/13 17/09/13 17/11/13 9 07/09/12 30/08/12 14/11/12 03/06/13 15/05/13 11/04/13 19/09/13 01/11/13

10 07/09/12 13/09/12 16/11/12 03/06/13 17/05/13 11/04/13 19/09/13 01/11/13 11 10/09/12 07/09/12 16/11/12 03/06/13 17/05/13 23/04/13 23/09/13 02/11/13 12 19/09/12 15/11/12 20/11/12 03/06/13 21/05/13 02/05/13 23/09/13 02/11/13 13 21/09/12 08/08/12 20/11/12 03/06/13 21/05/13 15/04/13 25/09/13 05/11/13 14 10/09/12 31/07/12 22/11/12 14/06/13 23/05/13 02/05/13 25/09/13 05/01/14 15 19/09/12 15/11/12 22/11/12 03/06/13 23/05/13 12/06/13 27/09/13 17/11/13 16 06/09/12 31/07/12 29/10/12 03/06/13 29/04/13 06/05/13 27/09/13 20/11/13 17 17/09/12 31/07/12 31/10/12 03/06/13 01/05/13 08/05/13 30/09/13 20/11/13 18 21/09/12 09/09/12 04/12/12 22/05/13 04/06/13 10/05/13 30/09/13 02/12/13 19 28/09/12 10/07/12 19/10/12 19/06/13 19/04/13 24/04/13 02/10/13 02/12/13 20 26/07/12 22/08/12 23/10/12 21/06/13 23/04/13 10/04/13 02/10/13 05/11/13 21 03/09/12 08/07/12 23/10/12 26/06/13 23/04/13 09/04/13 04/10/13 05/11/13 22 26/08/12 31/07/12 29/10/12 04/06/13 29/04/13 09/05/13 04/10/13 26/11/13 23 05/09/12 08/08/12 26/11/12 27/06/13 27/05/13 16/05/13 07/10/13 26/11/13 24 11/09/12 29/10/12 26/11/12 04/07/13 27/05/13 16/05/13 07/10/13 06/12/13 25 03/09/12 23/08/12 28/11/12 03/06/13 29/05/13 17/05/13 09/10/13 06/12/13 26 18/07/12 31/07/12 28/11/12 03/06/13 29/05/13 17/05/13 09/10/13 14/12/13 27 05/09/12 30/07/12 30/11/12 05/07/13 31/05/13 24/05/13 11/10/13 14/12/13 28 03/09/12 07/08/12 30/11/12 12/07/13 31/05/13 24/05/13 11/10/13 21/12/13 29 06/09/12 15/11/12 31/10/12 01/06/13 01/05/13 28/05/13 15/10/13 31/10/13 30 06/09/12 12/09/12 02/11/12 20/06/13 03/05/13 28/05/13 15/10/13 31/10/13 31 29/08/12 09/09/12 02/11/12 15/07/13 03/05/13 30/05/13 17/10/13 21/12/13 32 25/09/12 07/09/12 06/11/12 04/09/13 07/05/13 30/05/13 17/10/13 04/10/13 33 12/09/12 07/09/12 06/11/12 09/09/13 07/05/13 31/05/13 21/10/13 06/10/13 34 25/09/12 31/07/12 08/11/12 10/09/13 09/05/13 31/05/13 21/10/13 29/12/13 35 01/05/12 17/09/12 08/11/12 18/09/13 09/05/13 05/06/13 23/10/13 29/12/13 36 29/08/12 06/11/12 12/11/12 03/09/13 13/05/13 06/06/13 23/10/13 05/01/14 37 25/09/12 08/11/12 12/11/12 01/06/13 13/05/13 07/06/13 25/10/13 10/01/14 38 27/07/12 21/08/12 25/10/12 19/09/13 25/04/13 27/05/13 25/10/13 10/01/14 39 27/07/12 30/07/21

02 25/10/12 20/09/13 25/04/13 27/05/13 28/10/13 15/10/13

40 21/07/12 31/07/12 06/12/12 25/09/13 06/06/13 10/06/13 28/10/13 16/10/13 41 28/08/12 18/09/12 06/12/12 26/09/13 06/06/13 12/07/13 30/10/13 18/10/13 42 31/07/12 19/09/12 10/12/12 27/09/13 10/06/13 05/07/13 30/10/13 19/10/13 43 01/08/12 25/09/12 10/12/12 02/10/13 10/06/13 09/08/13 01/11/13 21/10/13 44 01/08/12 19/09/12 12/12/12 05/10/13 12/06/13 10/06/13 01/11/13 21/10/13 45 11/09/12 21/08/12 12/12/12 30/09/13 12/06/13 12/06/13 04/11/13 22/10/13


MAINTENANCE 14 18-month maintenance 24-month maintenance WTG P P P R

1 10/03/14 10/03/14 06/09/14 25/08/14 2 10/03/14 10/03/14 06/09/14 25/08/14 3 11/03/14 11/03/14 07/09/14 26/08/14 4 11/03/14 11/03/14 07/09/14 27/08/14 5 12/03/14 12/03/14 08/09/14 28/08/14 6 12/03/14 12/03/14 08/09/14 27/08/14 7 13/03/14 13/03/14 09/09/14 01/09/14 8 13/03/14 13/03/14 09/09/14 01/09/14 9 14/03/14 14/03/14 10/09/14 03/09/14

10 14/03/14 14/03/14 10/09/14 03/09/14 11 17/03/14 17/03/14 13/09/14 12 17/03/14 17/03/14 13/09/14 13 18/03/14 18/03/14 14/09/14 11/09/14 14 18/03/14 18/03/14 14/09/14 15 19/03/14 19/03/14 15/09/14 09/09/14 16 19/03/14 19/03/14 15/09/14 11/09/14 17 20/03/14 20/03/14 16/09/14 12/09/14 18 20/03/14 20/03/14 16/09/14 17/09/14 19 21/03/14 21/03/14 17/09/14 17/09/14 20 21/03/14 21/03/14 17/09/14 18/09/14 21 24/03/14 24/03/14 20/09/14 19/09/14 22 24/03/14 24/03/14 20/09/14 19/09/14 23 25/03/14 25/03/14 21/09/14 22/09/14 24 25/03/14 25/03/14 21/09/14 23/09/14 25 26/03/14 26/03/14 22/09/14 23/09/14 26 26/03/14 26/03/14 22/09/14 29/09/14 27 27/03/14 27/03/14 23/09/14 30/09/14 28 27/03/14 27/03/14 23/09/14 29 28/03/14 28/03/14 24/09/14 06/10/14 30 28/03/14 28/03/14 24/09/14 07/10/14 31 31/03/14 31/03/14 27/09/14 07/10/14 32 31/03/14 31/03/14 27/09/14 13/10/14 33 01/04/14 01/04/14 28/09/14 17/10/14 34 01/04/14 01/04/14 28/09/14 17/10/14 35 02/04/14 02/04/14 29/09/14 18/10/14 36 02/04/14 02/04/14 29/09/14 20/10/14 37 03/04/14 03/04/14 30/09/14 20/10/14 38 03/04/14 03/04/14 30/09/14 21/10/14 39 04/04/14 04/04/14 01/10/14 21/10/14 40 04/04/14 04/04/14 01/10/14 22/10/14 41 07/04/14 07/04/14 04/10/14 22/10/14 42 07/04/14 07/04/14 04/10/14 27/10/14 43 08/04/14 08/04/14 05/10/14 27/10/14 44 08/04/14 08/04/14 05/10/14 28/10/14 45 09/04/14 09/04/14 06/10/14 28/10/14

Table C–1 highlights the delays regarding execution of the preventative maintenance at the Piedra Larga I wind farm. The red colour highlights longer delays and the green colour highlights maintenance periods that were carried out on time.

Table C–1: Preventative maintenance delays

3MM 6MNM 12MNM 18MNM

COM & 3MM 3MM R & P COM & 6 MM 3 & 6

MM 6MM R&P

COM & 12 MM

6 & 12 MM

12MM R&P

COM & 18 MM

12 & 18 MM

18MM R&P

WTG Diff C& P

Diff C & R Diff Diff C

& P Diff C & R Diff Diff

P&R Diff C & P

Diff C & R Diff Diff

P&R Diff C & P

Diff C & R Diff Diff

P&R

1 2 12 11 8 7 -5 0 12 13 6 1 19 19 6 0 2 1 12 11 7 7 -5 0 12 13 6 1 18 18 6 0 3 2 9 8 8 10 1 2 13 13 3 1 19 20 7 2 4 2 9 7 8 7 -2 -1 12 13 6 1 18 19 5 0 5 3 8 5 9 8 0 -1 12 13 5 1 18 18 5 0 6 4 10 6 10 10 0 -1 14 15 5 1 20 21 6 2 7 1 9 8 7 10 1 3 12 14 4 2 18 8 1 9 8 8 11 2 4 13 15 3 2 18 9 2 9 7 8 7 -2 -1 13 14 7 1 18 19 5 0 10 2 9 7 8 7 -2 -1 13 14 7 1 18 19 5 0


11 2 9 7 8 8 -1 -1 13 14 6 1 18 12 2 9 7 8 8 -1 -1 12 14 6 1 18 18 5 0 13 2 9 7 8 7 -2 -1 12 14 7 1 18 18 5 0 14 2 9 7 9 8 -1 -1 13 16 8 3 18 19 3 0 15 2 9 6 8 9 0 1 12 14 5 2 18 19 5 0 16 2 9 7 8 8 -1 0 13 15 7 2 19 17 1 9 7 8 8 -1 0 13 14 7 2 18 18 2 8 6 9 8 0 -1 12 15 7 2 18 19 4 0 19 1 9 8 7 7 -2 0 12 14 7 2 18 18 4 0 20 3 11 8 9 9 -2 0 14 16 7 1 20 21 5 0 21 2 10 8 8 7 -3 0 13 14 7 1 19 19 5 0 22 2 9 7 8 9 -1 0 13 15 7 2 19 20 4 0 23 3 10 7 9 8 -1 0 13 15 6 2 19 19 4 0 24 3 10 7 9 8 -2 0 13 15 7 2 19 25 3 9 6 9 9 -1 0 13 15 7 2 19 19 4 0 26 4 11 6 11 10 -1 0 15 17 7 2 21 21 4 0 27 3 10 7 9 9 -1 0 13 16 7 2 19 19 4 0 28 3 10 7 9 9 -2 0 13 16 7 2 19 19 4 0 29 2 9 7 8 9 0 1 13 14 5 1 19 30 2 10 8 8 9 -1 1 13 14 5 1 19 19 5 0 31 2 11 9 8 9 -2 1 14 16 7 2 19 20 4 0 32 1 11 10 7 8 -3 1 13 12 4 0 18 19 6 0 33 2 12 10 8 9 -3 1 13 13 4 -1 19 19 6 1 34 1 12 10 8 8 -3 1 13 15 7 2 18 19 4 1 35 6 17 10 12 13 -4 1 18 20 7 2 23 24 4 1 36 3 12 10 9 9 -3 1 14 16 7 2 19 20 4 1 37 2 8 7 8 9 0 1 13 16 7 3 19 19 4 1 38 3 14 11 9 10 -4 1 15 18 8 3 21 39 3 14 11 9 10 -4 1 15 15 5 0 21 21 6 1 40 5 14 10 11 11 -4 0 15 15 4 0 21 21 6 1 41 3 13 10 9 11 -3 1 14 14 3 0 20 20 6 1 42 4 14 10 10 11 -3 1 15 15 4 0 21 21 6 1 43 4 14 10 10 12 -2 2 15 15 2 0 21 21 6 1 44 4 14 10 11 10 -4 0 15 15 4 0 21 21 6 1 45 3 13 10 9 9 -4 0 14 14 4 0 19 20 6 1

AVE 3 11 8 9 9 -2 0 13 15 6 1 19 20 5 1

24MNM COM & 24MM 18 & 24 MM 18 MM R&P

WTG Diff C & P Diff C & R Diff Diff P & R

1 25 24 6 0 2 24 24 5 0 3 25 24 4 0 4 24 24 5 0 5 24 24 5 0 6 26 25 4 0 7 24 24 4 0 8 24 24 4 0 9 24 24 6 0 10 24 24 5 0 11 24 12 24 13 24 24 6 0 14 24 15 24 24 5 0 16 25 25 4 0 17 24 24 4 0 18 24 24 6 0 19 24 24 6 0 20 26 26 6 0 21 25 25 6 0 22 25 25 6 0 23 25 25 6 0 24 25 25 5 0 25 25 25 6 0 26 27 27 6 0


27 25 25 6 0 28 25 29 25 25 5 0 30 25 25 6 0 31 25 26 6 0 32 24 25 6 1 33 25 26 6 1 34 24 25 6 1 35 29 30 6 1 36 25 26 6 1 37 25 25 6 1 38 27 27 6 1 39 27 27 6 1 40 27 27 6 1 41 26 26 6 1 42 27 27 6 1 43 27 27 6 1 44 27 27 6 1 45 25 26 6 1

AVERAGE 25 25 5 0 The headers of the table above describe the following comparisons: For the 3-month maintenance: Comparisons between commissioning and 3-month maintenance:

Difference between commissioning and programmed 3-month maintenance. Difference between commissioning and real 3-month maintenance.

Comparisons between 3-month maintenance real and programmed dates: Difference between programed and real date of the 3-month maintenance.

For the 6-month maintenance: Comparisons between commissioning and 6-month maintenance:

Difference between commissioning and programmed 6-month maintenance. Difference between commissioning and real 6-month maintenance dates.

Differences between 3-month 6-month maintenance. Comparisons between 6-month maintenance, real and programmed dates:

Difference between programmed and real date of the 6-month maintenance. For the 12-month maintenance: Comparisons between commissioning and 12-month maintenance:


Differences between 6-month and 12-month maintenance. Comparisons between 12-month maintenance, real and programmed dates:

Difference between programmed and real date of the 12-month maintenance. For the 18-months maintenance: Comparisons between commissioning and 18-month maintenance:


Differences between 12-month and 18-month maintenance. Comparisons between 18-month maintenance, real and programmed dates:

Difference between programmed and real date of the 18-month maintenance.

Table C–2: Differences between the Renovalia and O&M monthly reports Month Production

(kWh) Jan-13 1,928,554 Feb-13 38,236 Mar-13 989,662 Apr-13 661,563


May-13 278,197 Jun-13 1,095,781 Jul-13 169,119 Aug-13 Sep-13 - Oct-13 597,606 Nov-13 - Dec-13 - Jan-14 - Feb-14 - Mar-14 - Apr-14 - Total 5,758,718

Table C–3: Faults with most hours of stopping for January 2013 Event text Event time

[h] Occurrences Code

Fallo 1 agrupado convertidor ISU 1,339 168 4057 Fallo módulos PLC 260 56 2102 Paso Pausa-Reset Telemando 246 6 916 Fallo del automático FG008 en ABB V2 (B2(6h)), Fallo contactor FG008 en ABB V4 (B1(1h))

186 6 4027

Error BUS - Fallo INTERBUS 91 16 2118 Baja presión multiplicadora 69 3 401 Seta Emergencia GND 68 16 908 Fallo módulo medida de temperatura 65 9 2106 Térmicos del motor giro 61 1 107 Baja presión grupo hidráulico 57 6 203

Table C–4: Faults with most hours of stopping for February 2013 Event text Event time


Fallo 1 agrupado convertidor ISU 310 11 4057 Sobrecorriente en rotor 300 8 4007 Seta Emergencia GND 279 89 908 Fallo módulos PLC 217 57 2102 Térmicos ventiladores generador 205 9 506 Error BUS - Fallo INTERBUS 169 23 2118 Fallo lectura velocidad rotor 163 10 426 Bajo nivel de aceite del grupo hidráulico 127 6 205 Fallo módulo medida de temperatura 118 6 2106 OGS 105 11 410

Table C–5: Faults with most hours of stopping for March 2013


Event text Event time [h]

Occurrences Code

Fallo 1 agrupado convertidor ISU 750 84 4057 Fallo agrupado convertidor INU 366 4 4052 Fallo del automático FG008 en ABB V2 (B2(6h)), Fallo contactor FG008 en ABB V4 (B1(1h))

256 8 4027

OGS 124 25 410 Bajo nivel de aceite del grupo hidráulico 121 10 205 Error BUS - Fallo INTERBUS 111 32 2118 Fallo módulos PLC 92 28 2102 Fallo módulo medida de temperatura 61 6 2106 Valor pitch bajo en Stop 53 1 803 Sobretensión de línea 50 1 4000

Table C–6: Faults with most hours of stopping for April 2013


Occurrences Code

Fallo 1 agrupado convertidor ISU 2,007 203 4057 Fallo módulos PLC 298 63 2102 Seta Emergencia GND 249 80 908 Fallo del automático FG008 en ABB V2 (B2(6h)), Fallo contactor FG008 en ABB V4 (B1(1h))

198 17 4027

Error BUS - Fallo INTERBUS 107 24 2118 Apertura serie para test 49 21 902 Sobrecorriente en rotor 42 3 4007 Diferencia entre 2 palas muy alta 36 6 804 Temperatura bobinados trafo alta 28 2 306 Error desenrollamiento 27 7 106

Table C–7: Faults with most hours of stopping for July 2013


Occurrences Code

Sobrecorriente en rotor 210 6 4007 Fallo confirmación ventiladores generador 174 10 507 Seta Emergencia GND 165 32 908 Fallo módulos PLC 138 9 2102 Error BUS - Fallo INTERBUS 122 8 2118 Diferencia entre 2 palas muy alta 110 10 804 Sobretensión de línea 107 72 4000 Alta temperatura aceite hidráulico 102 1 207 Paso Pausa-Reset Local 83 3 915 Fallo 1 agrupado convertidor ISU 58 9 4057


Table C–8: Faults with most hours of stopping for January 2014 Event text Event time


Seta Emergencia GND 332 87 908 Paso Emergencia-Reset local 116 4 911 Fallo módulos PLC 85 46 2102 Error BUS - Fallo INTERBUS 65 23 2118 Bajo nivel aceite multiplicadora 55 47 402 Temperatura devanados generador 49 37 500 Sobrecorriente en estator 49 14 4006 OGS 42 7 410 Fallo tierra convertidor ISU 37 1 4014 Baja tensión de línea 35 1 4001

Table C–9: Alarm occurrences and stop time related to alarms in the Piedra Larga wind farm

Turbine system Number of alarms Time of alarms [h]

Gearbox 524 499 Converter 447 280 Operation states 80 225 Hydraulic Unit 601 156 Software 265 145 Generator 152 97 Communication 366 80 Climate 132 63 Pitch 329 52 Yaw sytem 28 26 Network connection 9 5

Table C–10: Time of system corrective maintenance at the Piedra Larga wind farm

Turbine system Hours of turbine stops [h]

Operational status 4012 Software 3360 Converter 3216 Gearbox 1802 Hydraulic Unit 1566 Pitch 831 Generator 673 Yaw sytem 450 Climate 269 Communication 96 Network connection 52


APPENDIX D: ENERGY TABLES AND ENERGY LOSS FACTORS

Table D-1 Summary of the transfer functions applied to the wind speed data at each mast and anemometer

Mast Height [m] Period starts Serial number

Slope desired

[m]

Offset desired [m/s]

M1 65 08/03/2005 21889 0.7642 0.337

M1 50 08/03/2005 21888 0.7619 0.341

M1 40 08/03/2005 21887 0.7657 0.373

M1 66 29/07/2007 57553 0.76 0.32

M1 50 29/07/2007 57542 0.759 0.35

M1 20 29/07/2007 52093 0.759 0.36

M2 66 28/01/2008 55899 0.759 0.32

M2 50 28/01/2008 57155 0.761 0.31

M2 20 28/01/2008 57153 0.759 0.38

M3 80 12/11/2008 11711-PJS 0.050491 0.20863

M3 80 11/12/2008 12156-TYV 0.05082 0.179

M3 65 12/11/2008 81529 0.759 0.32

M3 50 12/11/2008 81527 0.757 0.41

M3 20 12/11/2008 81526 0.757 0.38

M4 80 12/11/2008 11710-PJR 0.050851 0.18478

M4 80 29/10/2009 11711-PJS 0.05099 0.282

M4 65 12/11/2008 81508 0.758 0.4

M4 50 12/11/2008 81532 0.759 0.33

M4 20 12/11/2008 81531 0.76 0.35

M5 80 14/11/2008 11712-PJT 0.050771 0.17374

M5 65 14/11/2008 81537 0.759 0.37

M5 50 14/11/2008 81538 0.757 0.38

M5 20 14/11/2008 81539 0.76 0.36

1 These values include an adjustment factor of 0.998, based on the Svend Ole Hansen calibration corrections discussed in Svend Ole Hansen, “Wind tunnel calibration of cup anemometers – reduced uncertainties, Revision no.1”, April 2012.


Table D-2 Mast 1 measurements at the primary anemometers and wind vane

Month Mean wind speed

[m/s] Wind speed data

coverage [%] Wind direction data

coverage [%]

50 m 20 m 50 m 20 m 66 m

Sep-05 7.9 - 74 84 74 Oct-05 6.9 - 100 100 100 Nov-05 10.6 - 100 100 100 Dec-05 9.4 8.0 100 100 100 Jan-06 11.7 9.8 100 100 100 Feb-06 11.0 9.2 100 100 100 Mar-06 9.6 8.0 100 100 100 Apr-06 7.6 6.2 100 100 100 May-06 5.6 4.5 100 100 100 Jun-06 7.4 6.3 100 100 100 Jul-06 8.3 7.0 100 100 100

Aug-06 8.5 7.1 100 100 100 Sep-06 6.0 5.0 100 100 100 Oct-06 7.3 6.0 100 27 100 Nov-06 9.6 8.1 100 30 100 Dec-06 12.7 10.5 100 100 100 Jan-07 11.4 9.5 27 100 27 Feb-07 6.5 5.2 30 100 30 Mar-07 10.5 8.8 100 45 100 Apr-07 7.5 6.3 100 32 100 May-07 6.7 5.6 100 0 100 Jun-07 5.2 4.3 45 0 45 Jul-07 6.1 5.2 32 0 32

Aug-07 - - 0 0 0 Sep-07 - - 0 0 0 Oct-07 - - 0 0 0 Nov-07 - - 0 5 0 Dec-07 - - 0 89 0 Jan-08 - - 0 100 0 Feb-08 10.4 8.9 5 100 5 Mar-08 8.7 7.2 89 77 89 Apr-08 6.9 5.6 100 100 100 May-08 5.9 4.7 100 84 100 Jun-08 5.3 4.3 77 100 77 Jul-08 5.8 4.6 100 100 100





coverage [%]

50 m 20 m 50 m 20 m 66 m

Aug-08 5.3 4.3 13 13 13

Sep-08 _ _ 0 0 0

Oct-08 12.7 10.7 25 25 25

Nov-08 9.9 8.3 100 100 100

Dec-08 9.9 8.3 92 92 92

Jan-09 10.3 8.6 100 100 100

Feb-09 10.0 8.4 100 100 100

Mar-09 8.9 7.5 52 52 52

Apr-09 6.8 5.6 100 100 100

May-09 5.3 4.2 100 100 100

Jun-09 3.9 2.9 99 99 99

Jul-09 8.2 6.8 100 100 100

Aug-09 8.6 7.2 100 100 100

Sep-09 5.9 4.9 100 100 100

Oct-09 5.4 4.5 100 100 100

Nov-09 9.1 7.7 100 100 100

Dec-09 9.3 7.7 100 100 100

Jan-10 12.7 10.6 100 100 100

Feb-10 10.9 9.2 100 100 100

Mar-10 10.7 8.6 90 100 100

Apr-10 6.5 5.6 100 100 100

May-10 6.0 5.2 100 100 100

Jun-10 5.3 4.5 100 100 100

Jul-10 4.8 3.9 100 100 100

Aug-10 8.6 7.3 15 15 15

Sep-10 4.1 3.6 39 39 39

Oct-10 7.7 6.5 100 100 100

Nov-10 8.9 7.5 100 100 100

Dec-10 9.9 8.2 100 100 100

Jan-11 9.1 7.7 100 100 100

Feb-11 10.2 8.4 100 100 100

Mar-11 8.7 7.2 100 100 100

Apr-11 5.3 4.4 100 100 100

May-11 5.6 4.7 100 100 100

Jun-11 5.0 4.2 100 100 100





coverage [%]

50 m 20 m 50 m 20 m 66 m

Jul-11 5.6 4.6 100 100 100

Aug-11 4.5 3.9 100 100 100

Sep-11 5.4 4.5 100 100 100

Oct-11 7.1 6.1 97 97 97

Nov-11 9.4 7.9 100 100 100

Dec-11 11.9 9.8 100 100 100

Jan-12 10.7 8.8 100 100 100

Feb-12 10.0 8.3 100 100 100

Mar-12 9.2 7.7 100 100 100

Apr-12 6.4 5.3 100 100 100

May-12 - 4.9 0 100 100

Jun-12 - 3.0 0 100 100

Jul-12 - 7.4 0 100 100

Aug-12 - 3.7 0 100 100

Sep-12 - 4.9 0 100 100


Table D-3 Mast 2 measurements at primary anemometer and wind vane

Month

Mean wind speed [m/s]

Wind speed data

coverage [%]

Wind direction

data coverage

[%] Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

66 m 66 m 20 m 66 m 66 m 20 m

Mar-08 11.0 78 78 Feb-10 12.9 100 100 Apr-08 8.1 100 100 Mar-10 12.3 100 100 May-08 6.7 80 80 Apr-10 8.0 100 100 Jun-08 6.5 77 77 May-10 7.1 100 100 Jul-08 7.1 100 100 Jun-10 6.6 100 100

Aug-08 5.5 100 100 Jul-10 6.0 100 100 Sep-08 6.9 100 100 Aug-10 4.4 85 85 Oct-08 11.5 100 100 Sep-10 5.5 100 100 Nov-08 11.6 100 100 Oct-10 10.4 100 100 Dec-08 11.8 74 74 Nov-10 10.8 100 100 Jan-09 12.3 100 100 Dec-10 11.8 100 100 Feb-09 11.6 100 100 Jan-11 10.8 100 100 Mar-09 11.1 48 48 Feb-11 11.8 100 100 Apr-09 8.0 96 96 Mar-11 10.2 100 100 May-09 6.2 100 100 Apr-11 6.5 100 100 Jun-09 4.4 100 100 May-11 6.7 100 100 Jul-09 9.4 100 100 Jun-11 6.3 100 100

Aug-09 10.2 100 100 Jul-11 7.0 100 100 Sep-09 7.4 79 79 Aug-11 5.9 100 100 Oct-09 6.6 100 100 Sep-11 7.1 100 100 Nov-09 10.4 54 54 Oct-11 9.3 97 97 Dec-09 12.6 66 66 Nov-11 11.2 100 100 Jan-10 14.4 100 100 Dec-11 10.6 17 17


Table D-4 Mast 3 measurements at primary anemometer and wind vane.

Month


Wind speed data coverage

[%]

Wind direction

data coverage

[%] Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%] 65 m 65 m 75 m 65 m 65 m 75 m

Jan-09 12.7 100 100 May-10 7.0 100 100 Feb-09 11.7 100 100 Jun-10 6.4 100 100 Mar-09 12.0 72 72 Jul-10 5.9 100 100 Apr-09 8.1 98 91 Aug-10 5.1 99 99 May-09 6.4 100 29 Sep-10 5.3 97 97 Jun-09 4.5 100 100 Oct-10 9.9 100 100 Jul-09 9.4 100 100 Nov-10 10.5 100 100

Aug-09 10.3 99 100 Dec-10 22.5 3 3 Sep-09 7.3 84 100 Jan-11 10.7 100 100 Oct-09 6.8 100 100 Feb-11 11.6 100 100 Nov-09 11.7 100 100 Mar-11 10.0 100 100 Dec-09 11.4 100 100 Apr-11 6.2 100 100 Jan-10 14.8 100 100 May-11 6.4 99 100 Feb-10 13.0 100 100


Table D-5 Mast 4 measurements at primary anemometers and wind vane




coverage [%]

80 m 65 m 80 m 65 m 75 m

Nov-08 13.1 12.7 60 60 60 Dec-08 12.7 12.2 97 97 97 Jan-09 12.5 12.0 98 98 98 Feb-09 12.2 11.8 96 96 96 Mar-09 11.1 10.8 98 98 98 Apr-09 8.2 7.9 96 96 96 May-09 6.9 6.6 91 94 94 Jun-09 _ 5.0 0 77 77 Jul-09 _ 9.6 0 96 96

Aug-09 _ 10.1 0 98 98 Sep-09 _ 7.5 0 96 96 Oct-09 7.3 6.8 7 95 95 Nov-09 11.4 10.9 99 99 99 Dec-09 11.5 11.0 99 99 99 Jan-10 14.6 13.9 99 99 99 Feb-10 13.1 12.5 95 95 95 Mar-10 12.3 11.8 100 100 100 Apr-10 8.0 7.8 100 100 100 May-10 7.4 7.2 100 100 100 Jun-10 6.7 6.1 72 87 87 Jul-10 6.5 6.1 69 87 87


Aug-11 6.0 5.8 100 98 100 Sep-11 7.4 7.0 98 99 100





coverage [%]

80 m 65 m 80 m 65 m 75 m

Oct-11 9.9 9.6 100 99 100 Nov-11 13.0 10.8 79 100 100 Dec-11 13.5 12.9 74 100 100 Jan-12 - 11.4 0 100 100 Feb-12 - 11.3 0 100 100 Mar-12 - 10.5 0 100 100 Apr-12 - 7.7 0 100 100 May-12 - 7.2 0 99 100 Jun-12 - 4.7 0 100 100 Jul-12 - 10.2 0 100 100

Aug-12 - 5.7 0 100 100 Sep-12 - 6.9 0 99 100


Table D-6 Mast 5 measurements at primary wind vane and anemometer



coverage [%] Wind direction

data coverage [%]

80 m 65 m 80 m 65 m 75 m

Nov-08 14.0 13.1 54 54 51 Dec-08 12.6 11.7 98 98 98 Jan-09 12.5 11.6 98 98 98 Feb-09 11.8 11.0 96 96 96 Mar-09 10.8 10.1 98 98 98 Apr-09 8.0 7.6 95 94 95 May-09 6.5 6.3 93 93 93 Jun-09 5.2 4.9 86 86 86 Jul-09 9.9 9.3 94 94 94



Aug-11 6.1 5.6 92 98 100 Sep-11 - 7.2 0 93 100




coverage [%] Wind direction

data coverage [%]

80 m 65 m 80 m 65 m 75 m

Oct-11 - 9.5 0 100 100 Nov-11 - 10.9 0 100 100 Dec-11 - 12.5 0 100 100 Jan-12 - 11.3 0 100 100 Feb-12 - 11.1 0 100 100 Mar-12 - 9.9 0 100 100 Apr-12 - 7.3 0 100 100 May-12 - 6.7 0 100 100 Jun-12 - 4.3 0 100 100 Jul-12 - 9.9 0 100 100

Aug-12 - 5.6 0 100 100


Table D-7 La Venta 3 measurements at primary anemometer and wind vane at 30 m

Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

Nov-01 9.1 51 51 Sep-04 6.8 100 100 Dec-01 12.8 50 50 Oct-04 6.9 100 100 Jan-02 11.4 100 100 Nov-04 10.9 100 100 Feb-02 14.0 100 100 Dec-04 12.8 51 51 Mar-02 9.4 94 94 Jan-05 12.1 57 57 Apr-02 8.5 100 100 Feb-05 11.7 100 100 May-02 8.2 100 100 Mar-05 8.1 100 100 Jun-02 5.4 100 100 Apr-05 9.4 92 92 Jul-02 9.1 100 100 May-05 6.7 97 97 Aug-02 9.5 100 100 Jun-05 5.8 100 100 Sep-02 4.4 100 100 Jul-05 6.1 100 100 Oct-02 7.4 93 93 Aug-05 7.4 100 100 Nov-02 11.4 100 100 Sep-05 9.1 80 80 Dec-02 11.7 100 100 Oct-05 7.0 76 76 Jan-03 14.6 95 95 Nov-05 11.5 79 79 Feb-03 9.6 100 100 Dec-05 11.4 97 97 Mar-03 7.9 100 100 Jan-06 13.0 100 100 Apr -03 7.6 100 100 Feb-06 11.9 100 100 May-03 6.1 100 100 Mar-06 10.0 100 100 Jun-03 4.2 100 100 Apr-06 8.1 100 100 Jul-03 9.1 100 100 May-06 5.7 100 100 Aug-03 8.6 100 100 Jun-06 8.5 100 100 Sep-03 5.5 100 100 Jul-06 8.8 100 100 Oct-03 8.1 100 100 Aug-06 8.8 100 100 Nov-03 11.7 100 100 Sep-06 6.4 100 100 Dec-03 13.3 100 100 Oct-06 8.5 100 100 Jan-04 11.4 92 92 Nov-06 11.2 100 100 Feb-04 8.9 100 100 Dec-06 12.7 100 100 Mar-04 10.0 69 69 Jan-07 14.0 100 100 Apr-04 8.1 100 100 Feb-07 10.7 100 100 May-04 8.8 100 100 Mar-07 11.1 100 100 Jun-04 6.5 100 100 Apr-07 8.3 100 100 Jul-04 7.5 91 91 May-07 7.4 100 100 Aug-04 8.1 98 98 Jun-07 5.8 100 100


Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%] Jul-07 5.9 100 100 Feb-08 9.2 100 100 Aug-07 6.5 100 100 Mar-08 9.8 100 100 Sep-07 7.4 100 100 Apr-08 7.7 100 100 Oct-07 9.1 100 100 May-08 6.2 100 100 Nov-07 12.9 100 100 Jun-08 7.1 100 100 Dec-07 10.4 100 100 Jul-08 6.9 72 72 Jan-08 11.4 100 100


Table D-8 Santo Domingo 3 measurements at primary anemometer and wind vane at 30 m

Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

Month


Wind speed data

coverage [%]

Wind direction

data coverage

[%]

Oct-01 13.4 100 100 Aug-04 7.2 100 100 Nov-01 9.9 100 100 Sep-04 6.0 100 100 Dec-01 11.4 100 100 Oct-04 6.1 100 100 Jan-02 10.7 100 100 Nov-04 9.6 100 100 Feb-02 13.7 100 100 Dec-04 11.6 100 100 Mar-02 9.4 100 100 Jan-05 11.4 100 100 Apr-02 8.3 100 100 Feb-05 11.0 100 100 May-02 7.8 100 100 Mar-05 7.8 100 100 Jun-02 5.2 100 100 Apr-05 9.2 100 100 Jul-02 8.3 100 100 May-05 6.4 100 100

Aug-02 8.9 100 100 Jun-05 5.6 100 100 Sep-02 4.2 100 100 Jul-05 5.6 100 100 Oct-02 6.4 100 100 Aug-05 7.0 100 100 Nov-02 10.3 100 100 Sep-05 8.1 100 100 Dec-02 10.8 100 100 Oct-05 7.5 100 100 Jan-03 13.5 100 100 Nov-05 10.7 100 100 Feb-03 9.2 100 100 Dec-05 9.9 100 100 Mar-03 7.8 100 100 Jan-06 11.7 100 100 Apr-03 7.6 100 100 Feb-06 11.0 100 100 May-03 5.8 100 100 Mar-06 9.4 100 100 Jun-03 4.0 100 100 Apr-06 7.5 100 100 Jul-03 8.3 100 100 May-06 5.5 100 100

Aug-03 7.9 100 100 Jun-06 7.8 100 100 Sep-03 4.8 100 100 Jul-06 8.3 100 100 Oct-03 7.0 100 100 Aug-06 8.1 100 100 Nov-03 10.4 100 100 Sep-06 5.8 100 46 Dec-03 12.2 100 100 Oct-06 7.4 100 74 Jan-04 10.6 100 100 Nov-06 9.9 100 85 Feb-04 10.7 100 100 Dec-06 11.8 100 75 Mar-04 11.6 100 100 Jan-07 12.8 100 58 Apr-04 8.0 100 100 Feb-07 10.0 100 0 May-04 8.7 100 100 Mar-07 10.7 100 75 Jun-04 6.1 100 100 Apr-07 7.7 100 99 Jul-04 6.6 100 100 May-07 6.9 100 100


Month


Wind speed data

coverage [%]

Wind direction data coverage [%]

Month


Wind speed data coverage

[%]

Wind direction

data coverage

[%]

Jun-07 5.5 100 100 May-08 5.9 100 15 Jul-07 5.5 100 91 Jun-08 6.9 100 31

Aug-07 5.9 100 82 Jul-08 6.1 100 5 Sep-07 6.5 100 96 Aug-08 4.5 100 0 Oct-07 8.0 100 98 Sep-08 6.0 100 27 Nov-07 11.8 100 68 Oct-08 8.8 73 9 Dec-07 9.5 100 54 Nov-08 0 0 0 Jan-08 10.7 100 61 Dec-08 9.9 92 92 Feb-08 8.6 100 51 Jan-09 10.5 99 100 Mar-08 9.6 100 47 Feb-09 13.8 89 100 Apr-08 7.1 100 16


Energy Loss Factors

DNV GL uses a standard detailed set of loss factors which aims to ensure that all potential sources of energy loss are considered by the relevant parties. For some projects certain loss factors will not be relevant, in which case an efficiency of 100% is assumed. Additionally some losses may only be sensibly estimated when comprehensive information is available from a project and a review of such documentation is within the scope of DNV GL’s work. The comprehensive list of potential losses in the table below provides clarity on what losses have, or have not, been considered within the analysis, and what assumptions have been made.

Piedra Larga Wind Farm Phase I Phase II

Wind Project Rated Power 90.0 138.0 MW Gross Energy Output 387.9 640.9 GWh/annum

1 Wake effect 1a Wake effect internal 96.7 97.1 % 1b Wake effect external 96.6 98.1 % 1c Future wake effect 100.0 100.0 % 2 Availability 2a Turbine availability (10 years) 96.2 96.2 % 2b Balance of Plant availability 99.8 99.8 % 2c Grid availability 99.0 99.0 % 3 Electrical efficiency 3a Operational electrical efficiency 97.8 96.7 % 3b Wind farm consumption 100.0 100.0 % 4 Turbine Performance

4a Generic power curve adjustment 100.0 99.1 %

4b High wind speed hysteresis 97.9 98.6 %

4c Site specific power curve adjustment 99.8 99.7 %

4d Sub-optimal turbine performance 99.0 99.0 %

5 Environmental

5a Performance degradation – non-icing 99.5 99.5 %

5b Performance degradation – icing 100.0 100.0 %

5c Icing shutdown 100.0 100.0 %

5d Temperature shutdown 100.0 100.0 %

5e Site access 100.0 100.0 %

5f Tree growth 100.0 100.0 %

6 Curtailments 6a Wind sector management 100.0 100.0 % 6b Grid curtailment 100.0 100.0 % 6c Noise, visual and environmental

t il t 100.0 100.0 %

Net Energy Output 324.4 539.4 GWh/annum


The specific assumptions made for the analysis here are summarised in the following table. Loss Assumptions and rationale for this analysis

1 Wake Effect 1a The wake effects have been calculated using the WindFarmer wake model. 1b The wake effects of the Oaxaca II, Oaxaca III, Eurus, and La Venta II wind farms have

been calculated using the WindFarmer wake model. 1c Although it is expected that wind farm development will continue in the region, the impact

of future wake effects has not been modelled in this analysis. 2 Availability 2a A technology-specific loss factor of 96.2% has been assumed for both the Gamesa G80-2.0

MW and G87-2.0 MW turbine models for the first 10 years of operation, to account for the turbine availability.

2b A BOP availability of 99.8% has been assumed, based on DNV GL’s assessment. 2c A grid availability of 99.0% has been assumed, based on DNV GL’s assessment.

3 Electrical transmission efficiency 3a An electrical efficiency of 97.2% has been assumed for Phase I and 96.6% has been

assumed for Phase II, both of these are based on contract specifications. DNV GL has not conducted an independent assessment of these losses.

3b It is assumed that non-operational wind farm electrical consumption is an operational cost and not a loss factor.

4 Turbine performance 4a It is assumed that a generic power adjustment is necessary for the G87 turbine model.

The G87 measured power curve gives 1.5% less energy than the calculated power curve. 4b It has been assumed that high wind speed hysteresis effectively reduces the cut out wind

speed from 25 m/s to 22.5 m/s for the Gamesa G80-2.0 MW and G87-2.0 MW turbines, for the purpose of the energy calculations. Phase 2 has less high wind control hysteresis losses than Phase 1, since Phase 2 includes a high proportion of G87 turbines, with a lower fraction of energy in the range of high wind speeds than the G80 turbines (a higher energy proportion at low-medium wind speeds, and a lower proportion of energy at high wind speeds, than the G80), therefore the energy impact due to high wind starting/stopping is lower in Ph2.

4c A factor has been estimated to account for the energy loss due to site-specific wind flow issues that will adversely affect the performance of the turbines.

4d

A factor of 99.0% has been assumed to account for sub-optimal power performance of the turbines. A 99.0% of sub-optimal performance is the DNV GL generic assumption for Latin America, based on experience and what is accepted as an average value. There are operational wind farms with higher sub-optimal performance losses, but it is also true that there are some wind farms with lower losses. With appropriate maintenance and performance monitoring (not only the availability) the sub-optimal performance losses can be mitigated and a figure of 99.5% can be achieved.

5 Environmental 5a It has been assumed that a factor of 99.5% is appropriate to account for the effect of

performance degradation due to dirt accretion and blade degradation. 5b It has been assumed that a factor of 100.0 % is appropriate to account for the effect of

performance degradation, due to ice accretion on the blades when the turbine is operational.

5c It has been assumed that a factor of 100.0 % is appropriate to account for the energy effect of downtime due to ice accretion on the turbine, causing the turbine either to shut down or not to start.

5d It has been calculated from data recorded at the site that no loss is required to account for the energy effect of high temperature and low temperature turbine shut down.

5e It has been assumed that there are no specific adverse impacts on site access due to extreme remoteness or weather conditions.

5f It is assumed that there is no significant influence from tree growth in the vicinity of the wind farm.


6 Curtailments 6a It has been assumed that no wind sector management is required. 6b It has been assumed that no grid curtailment is required. 6c It has been assumed that no noise, visual or environmental curtailment is required.


APPENDIX E: ELECTRICAL SYSTEM REVIEW

E.1 Introduction

This Annex contains a review of the electrical system of Piedra Larga I Wind Farm.

The review is based on the information provided in the virtual data room which was opened for the purpose of the Due Diligence Analysis, mainly the documents included in folders 7.2.1.1 (Electrical Engineering) and 7.1 (Equipment). Some additional information, provided via an FTP on 23 November 2012, has also been partly reviewed and included in the sections below.

DNV GL notes that the information contained in the documents and files provided regarding the electrical system is basically related to Phase 1. However, as both phases shared electrical infrastructures, it is possible to use some of the information for the Phase 2 assessment.

E.2 Electrical system description

Wind turbine

According to /64/, the electrical operational range of the G80 wind turbine is as follows:

Voltage: ±5% of the nominal voltage at the MV grid Frequency: ±3Hz of the nominal frequency for the 50Hz and 60Hz grids

Regarding power factor, the G80 may be equipped with a capability which has been enhanced from the standard version, which allows the wind turbine to operate within a power factor range from 0.95 capacitive to 0.95 inductive, in conditions of ±5% of the nominal voltage and within the operational temperature range. These values are achieved at the low voltage side of the wind turbine transformer.

According to /64/, the G80 wind turbine is certified against Red Eléctrica de España LVRT requirements. In addition, the LVRT test (performed on a wind turbine from a Spanish wind farm, according to Eon 2006 Grid Code requirements) report /102/ has been provided.

The wind turbine is equipped with a 0.69/34.5kV transformer, rated at 2,350 kVAr, which steps up the voltage in order to connect the wind turbine to the medium voltage grid. DNV GL notes that the rated power of the transformer allows the wind turbine to operate within the entire power factor range, at full load.

Medium voltage circuits

DNV GL has reviewed the information provided regarding the medium voltage circuits for Phase 1 /65/. DNV GL notes that the selected cables installed can withstand a current that is close to the maximum admissible current when the wind farm is at full load. Specifically, cable sections from the last wind turbine to each circuit at the substation are close to 100%. The Customer has not confirmed how many circuits are installed, per trench, in these final circuit sections. In addition, DNV GL needs to see the electrical calculations which justify the selected cable sections.

Demex (Piedra Larga) substation

According to /67/, Phase I and Phase II are connected to the Demex (Piedra Larga) substation, which is a double bar substation at the high voltage side, with four transformer bays (two for phase I and two for Phase II) and two line bays (one for Phase I and the other for Phase II). The indoor medium voltage equipment comprises the required medium voltage cabinets, for connection of the medium voltage circuits of each wind farm, and the protection control equipment. DNV GL considers that the design is adequate and according to the industry standard. There are two ancillary service transformers and four capacitor banks, two for each of the phases.


DNV GL has also reviewed documents /68/ and /69/. The design of the protection system and the communication seems to be adequate and according to the industry standard. As mentioned in Section E.3, below, the wind farm has successfully passed pre-operational grid compliance tests which validate the design and installation.

According to /70/, /71/ and /72/, there are two power transformers for Phase I. Both have similar characteristics, 60Hz, 230/34.5kV, YnD connection and on-load tap changer (±10 steps 1% each); although one of them is rated at 30/40/50/56 MVA and the other at 30/40/50MVA.

DNV GL has also reviewed the technical characteristics of the main substation electrical equipment included in the data room folder 7.1, and this is considered to be adequate.

Overhead line

According to /75/, the overhead line is a double circuit (one circuit being for Phase I and the other for Phase II), approximately 30.3 km long. The tower will be self-supported and each circuit will use an 1113 ACSR/AS cable. This information is consistent with that stated in /77/ and /67/.

DNV GL considers that the overhead line characteristics and design is adequate for the purpose of the Project. DNV GL has not been provided with the electrical characteristics of cable 1113 ACSR/AS. However, according to the internal database although this cable is capable of withstanding the current from the wind farms, it may be somewhat oversized.

Ixtepec extension - interconnection facilities

According to /76/, the interconnection facilities comprise two additional line bays at Ixtepec Potencia substation. The bays are equipped with the usual components required for adequate connection of the circuits from the overhead line.

The energy metering equipment is installed at the interconnection point. There is one for the Phase I circuit and another for the Phase II circuit.

E.3 Compliance with the grid code

According to the EPC contract, Phase 1 must comply with the Grid Code in force on the contract date /73/.

DNV GL notes that there are no relevant differences between the different Grid Codes, regarding the most relevant issues. The latest Grid Code /74/ is more detailed, in some aspects. DNV GL has reviewed the requirements applicable to each wind farm. This section analyses the compliance of Phase 1 and Phase 2 with the requirements of the respective Grid Code.

DNV GL has been provided with the document issued by CFE /103/ which declares Phase I to be under “normal operation”. DNV GL understands that this statement is issued after compliance with the Grid Code requirements has been proven. Phase I and Phase II share interconnection infrastructures and wind turbine models; therefore, it is expected that, if Phase I complies with the Grid Code requirements, so will Phase 2.

Voltage and frequency ranges

According to /74/, wind farms must withstand (without disconnection) voltage variations within the range of ±5% in normal conditions and within ±10% in emergency conditions.

According to /64/, the G80 wind turbine is able to withstand voltage variations that are within ±5% of the nominal voltage measured at the medium voltage side of the wind turbine transformer.

The aforementioned capability complies with the requirement under normal operation grid conditions, but not with emergency situations. Therefore, an on-load tap changer transformer at the substation is required. According to /70/, /71/ and /72/, the substation transformers are provided with an on-load tap


changer with 21 steps (±10 steps, 1% each). Therefore, DNV GL does not expect any issues regarding the withstanding of grid voltage variations.

Regarding the frequency range, the wind farm must withstand connection that is within 57.5HZ and 62Hz under normal operational conditions, and over 62HZ and below 57.5Hz, instantly. According to /64/, the G80 wind turbine is able to withstand voltage variations that are within ±3Hz of the nominal frequency; therefore, the requirement is met. However, Gamesa has not confirmed that the wind turbine is able instantly to withstand values that are beyond those mentioned above.

Protection system and switching equipment

Wind farms must be equipped with a protection system for (each wind turbine): the power transformer, the ancillary services transformer, the interconnection and transmission lines, the switchgears and the substation bars. The switching off equipment must be automatic and the wind farm electrical system equipment must be protected against internal and external faults. The protection system settings may be verified, meanwhile, during site tests.

The protection system must comply with the standards stated in the Grid Code: specifically, the substation and interconnection facilities protection system must comply with V6700-62 specification and the relays installed must be included in LAPEM-05L. Wind turbines must be equipped with digital relays with an independent and redundant power supply. The power transformer and the interconnection lines must be equipped with a grid events register.

DNV GL has been provided with the Demex and Ixtepec substation protection system commissioning tests, as well as with the factory tests for the electrical equipment. Commissioning and factory tests for wind turbine switchgear cabinets have also been provided. The tests have been satisfactory and CFE has issued its “normal operation” statement. Therefore, DNV GL considers that the Grid Code requirements have been met.

Communication schemes

This requirement is detailed in the latest Grid Code, which shall be applicable for Phase 2 /74/. It requires a double channel data and voice communication between the wind farm and the CFE control centres. Section 3.3 of Annex II of the Grid Code states the signals which must be transmitted.

According to /69/, DNV GL understands that the Demex substation is equipped with an adequate communication system to comply with the Grid Code requirements for Phase 2 regarding this issue. In addition, the successful completion of the communication tests /104/ and the “normal operation” statement /103/ issued by CFE prove complement with the Grid Code.

Energy measurement

The Grid Code specifies the data that must be registered and transmitted by the measurement equipment. The placement of the measurement equipment, according to /76/, is in the Ixtepec substation - both for Phase I and for Phase II.

DNV GL has received factory and commissioning tests for the Itxepec current and voltage transformers. DNV GL required the Customer to clarify whether or not the energy meters are the of multi-metering device type, Schenider ION8600.

In any case, the “normal operation” statement /103/ issued by CFE proves complement with the Grid Code.

Energy quality

Harmonics and flicker are measured at the interconnection point and the limits applicable for Phase I and Phase II are included in the Grid Code, /74/ and /73/ respectively.

DNV GL has been provided with the harmonics measurement tests at the Demex and Itxepec Potencia substations, regarding Phase I. The tests provided /105/ show that the harmonic performance (% fundamental voltage) is within the limit required by the Grid Code. In addition, the “normal operation” statement /103/ issued by CFE proves complement with the Grid Code.


It is expected that Phase II also meets the energy quality requirements; however, DNV GL needs to see the tests, once they become available.

Low voltage ride through

This requirement is similar for both Grid Codes ( /73/ and /74/). Wind farms must withstand connection to the grid when a grid fault falls into the shadowed area in the figure below. Wind farms are allowed to be disconnected when they are operating below 5% of their rated power, or at high wind speeds when more than 50% of the wind turbines are stopped. Wind farms may also remain connected when two faults occur within 2 minutes, either at three-phase, two-phase or one-phase faults.

According to /64/, the G80 2.0 wind turbine has been successfully tested for LVRT requirements in Spain, according to PO12.3. The requirement stated in the Grid Code is tougher that that stated in PO12.3. According to /101/, the G80 wind turbine has passed LVRT tests which are more stringent than the requirements stated in the Grid Code. DNV GL considers that these tests, which have been performed on a G80 wind turbine installed in Spain, prove that the wind turbine is able to comply with the Mexican Grid Code. Nevertheless, according to the Grid Code /73/ and the information provided by the Sponsor (the Q&A list, dated 3 December 2012), an on-site test to prove LVRT compliance is required; this has not yet been required for the site.

Emergency control and reliability scheme

The wind farm must provide the relevant signals to CFE in order to allow it control over the wind farm, in terms of interaction with the grid. According to /69/, the Demex substation is equipped with an adequate communication system to allow such control to be taken by CFE.

Equipment tests

According to /73/, tests proving complement with the Grid Code requirements are to be provided to CFE. These tests include the following, amongst others:

Setting and correct operation of the protection system Communication and measurement equipment tests On-site LVRT test On-site harmonics measurement

DNV GL has received the results of the aforementioned tests, except for those regarding to the on-site LVRT. The Customer was requested to clarify whether the tests have been performed.


According to the Grid Code /74/ applicable for Phase II, the wind turbines and electrical system of the wind farm shall pass the following tests:

Prototype level: o Energy quality o Low voltage ride through according to applicable standards o Noise, according to standard IEC 61400-11 o Wind turbine certification according to standard IEC 61400-22 o Anything else that CFE may require

On-site testing level:

o Complements the Grid Code requirements o Power generation verification and energy quality parameters measurement o Noise verification o Communication system, protection system and energy measurement system tests

according to CFE’s procedures at the interconnection point.

Phase II prototype level tests stated in /74/ should have been provided for review.

Interconnection studies

The Grid Code states the required interconnection studies and the company appointed to undertake them, which are similar for /73/ and /74/:

Load flow (CFE) Fault and short-circuit analysis (DFE and the wind farm owner) Protection coordination (CFE and the wind farm owner) Transient and dynamic stability (CFE) Voltage stability (CFE) Contingencies analysis (CFE) Energy quality for harmonic analysis (wind farm owner at the start of operation)

Since Phase I is already under operation, DNV GL understands that the required interconnection studies have been performed successfully. However, it should also have been confirmed that those studies were performed considering Phase I and Phase II.

Power factor

Wind farms must be able to operate with a variable capacity factor that is within 0.95 inductive and 0.95 capacitive, at the interconnection point. CFE will establish the required capacity factor, depending on the grid conditions. In addition, wind farms that are larger than 10MW will also be required to participate in voltage control.

DNV GL required information regarding the specific requirements set out by CFE for the Phase I and Phase II wind farms, regarding participation in voltage control and how this control is to be implemented.

According to /64/, the G80 2.0MW wind turbine is able to operate within a variable power factor range from 0.95 capacitive - 0.95 inductive, in conditions of ±5% of the nominal voltage and within the operational temperature range. These values are achieved at the low voltage side of the wind turbine transformer. The wind turbine transformers and the substation power transformers provide a high inductive effect, whilst medium voltage cables provide a capacitive effect. This is the reason why additional reactive power compensation is required, in order to meet the capacity factor required by the grid code at any load.

According to /67/, two capacitor banks (7.4MVAr and 8.7MVAr respectively) will be installed. However, no evidence of additional inductive reactive power is given. Therefore, DNV GL required the Customer to confirm the capacitor banks’ nominal power and to provide an assessment which proves that the 0.95 capacitive-inductive power factor will be achieved at the interconnection point at the Ixtepec Potencia substation.

Electrical losses


This section contains the electrical losses estimation for the wind farms. The calculation is made, taking into consideration the following information for the wind farm:

Overhead line data (length, cable type, number of circuits, etc.) Substation transformer load and no load losses data Medium voltage circuits configuration and technical data (length, cable type, wind turbines connected, etc.) Wind turbine transformer load and no load losses data Wind resource distribution and wind turbine power curve

DNV GL has been provided with the required data for an independent energy loss assessment. The results are stated below:

Component Electrical Losses %

Medium voltage cables 0.52%

Wind turbine transformers 1.14%

Substation transformers 0.33%

Overhead line 0.21%

Total losses 2.20%

Wind farm electrical efficiency 97.8%


E.4 Diagram of electrical installations

Source: /120/


APPENDIX F: SITE INSPECTION REPORTS

WIND TURBINE INSPECTION CHECK LIST WF NAME: Demex I WT: 02 1 of 7

WF: Demex I WTG (nº, model, HH, kW,...): 02, Gamesa G80 60Hz, 67m, 2000

Date and time of inspection: 20/11/2012

Turbine inspector: Amílcar Zambrano

Start of operation: September 2012 but CAP not signed yet

GROUND CONTROLLER (software and version):

Comments:

DISPLAY READINGS

On-line/off-line: On line Energy Meters

Rotor speed (rpm): 0.93 Energy present year (MWh) 1036

Blade pitch angle (deg): 83.01 Energy actual month (MWh) 267

Power output (kW): -2 Energy past month (MWh) 506

Wind speed (m/s): 12.69 Producible Energy present year (MWh) 1181

Generator speed (rpm): 61 Producible Energy actual month (MWh) 392

Producible Energy past month (MWh) 473

Time Meters

Total (h) 2135

No Service (h) 1987

Line OK (h) 1987

Environment OK (h) 1986

Turbine OK (h) 1657

Gen (h) 1350

Availability

Time period (week, month, year) Total November October

Availability (%) 83.42 71.01 99.82

Temperatures (Ground controller fields) Min (ºC) Actual (ºC) Max (ºC)

Environment 23 28 30

Nacelle 29 38 40

Hydraulic 31 47 50

Gearbox 45 75 77

Gearbox Oil 52 69 70

Bearing Opposite side of the Coupling 40 68 68

Bearing Coupling side 39 60 61

Environment Spinner 27 32 33

Trafo 3 phases 49/56/63 81/98/124 117/130/483

Converter ABB 38 54 102

Hub Top box 27 40 40.3

Slip rings 34 50 53

Winding 3 50/50/50 105/104/104 111/108/109

Environment Sonic sensor 23 28 30

Main events of the log book (if are any)

The maximum temperature of the third phase of the transformer is too high. GL GH recommends checking the sensors and cable connections.

Documentation to be checked

Operating manual

Building permit

Maintenance duty book

Certification reports

Maintenance reports

Analysis of oil sample

Commissioning report

Inspection papers elevator (persons)

Inspection papers elevator (material)

Certificate acc. BGV A3 § 5

Certificate of conformance


ASSY. ITEM INSPECTION CLASS COMMENTS

PICTURE

Grouting D, Co, C 1 Ok. No cracks or other issue detected / Inside Foundation-tower sealing well

preserved.

Bolts or Can D, C, Co 1 OK. No humidity, clean and good general condition

Grounding Cf, D, Co 1 Ok. Good conditions

Foundation

Manuf., serial

n.,height Trinity/ 100182992/G80-2MW/ 67m

Door D, Co, Cf 2 The dust ingress was noted in the base platform of the tower. GAMESA

should install the dust filter in the doors.

Stairs, safety D, Co, F, Sp 1 OK. Good condition and well functioning safety sliders. Elevator in good

conditions.

Hatches / Platform D, Cf, F 1 OK. No oil stains or other issue was detected

Flanges/Bolts D, N, Co 1 OK, No damage signal and well tight

Earthing Cf, D, Co 1 OK. Good visual condition..

Coating D, C, Co 2

An oil escape from the hydraulic pitch system has stained the tower. The oil

has fallen from the hub spinner and has accumulated in both sides of the

tower forming 90º with the wind predominant direction.

Lighting Cf, D, Co 1 OK. Without damage and good visual condition

Cabling Cf, D, Co 1 OK. Properly fixed and well guided free hanging part

Tower

Manuf., serial n.,… Valencia Power Converter for Top Box /ABB for converter cabinet

Grounding Cf, D, Co 1 OK. No damage signal and well fixed

Cabling Cf, D, W 1 Ok. Good cable connections

Breaker, switch,

fuse Cf, D, W 1 OK. No burn signal

Beacons F 1 OK. Working well

Emergency lights F 1 OK. Working well

Switch gear D,T,Co,Sp 1 OK. No sound or wear detected

Control System F 1 OK. Working well

Cooling System L 1 OK. No leaks.

Converter D,T,Co,Sp 1 OK. No damage detected

Electric cabinets

Yaw locking device D, Co, Sp 1 N/A

Yaw Bearing D,F,N,Co,L 1 OK. No sound or vibration detected during the test

Brakes/Sliding

blocks D, Co, Cf 1 OK. Good conditions

Yaw M

echanism

Hoses incl.

couplings D,T,Co,C 1 OK. No leakage detected



PICTURE

Gear ring D,F,N,Co,L 1

OK. General rust was noted overt the surface of the teeth but this is not

enough to be considered an issue.

Drives D,F,N,Co,L 1 OK. No leakage or wear detected

Manuf., model.,… Vickers G80-5359

Pump T, F, Co 1 OK. No leakage found and working well during the test

Accumulators T,Co,L,Ps 2

A thin oil layer was detected over the hydraulic oil block- The same has

probably come from an old oil leak or oil coming from the refilling process.

GL GH recommends cleaning the surface of the hydraulic block in order to

avoid any confusion

Hoses incl.

couplings D,T,Co,C, L 1 OK. No leakage detected

Hydraulics

Nacelle foundation /

main frame D, Co, C 1 OK. Good general condition.

Nacelle cover D, Co, C 1 OK. Good conditions

Cabling D, Cf, 1 OK. Well secured

Hoist D, Cf 1 OK. Working properly and well lubricated

Nacelle

Coating D, C, Co 1 OK. Good condition – no signs of repair.



PICTURE

Bolts D, N, Co 1

OK. Good general condition.

Cooling system D, F 2

The motor device in charge of opening the windows for cooling the nacelle is

damage and should be repaired. The issue is not critical but the nacelle and

the major components temperature alarms will increase during summer if the

component is not repaired.

Main Bearing

lubrication sys D, F 1 OK. No ware sound or damage detected during stand still functioning.

Main shaft D, Co, C 1 OK. Good general condition

Shaft coupling

elements D, C 1 OK. Good general condition

Main shaft bearings T, N, L 1 OK. Good general condition Main Shaft

Manuf., serial n.,

kW,… GAMESA, GE 2000 PL / SN 100401/ 2000 kW

Gearbox Torque

reaction arms D, Co, C, W 1 OK. In good general conditions

Gearbox

Parallel stage D, Co, C 2

A pressure area was located over the pinion of the intermediate speed shaft.

This early wear signal should be monitored in order to establish if the damage

is increasing with the time or if is staying like this. GL GH recommends

constant visual monitoring with the services.



PICTURE

Cooling

system/circuit Cf, D, T, L 1 OK. No oil dripping or damage detected.

Protective covers D, Co 1 OK. Good general condition

Cabling fittings Cf, D, Co 1 OK. The cables are well tight, no corrosion and good general conditions.

Manuf., serial

n.,kW,… Cantarey Reynosa (GAMESA), CR 20-5 G90, Nº469093, año 2011, 2040kW

Hydraulic

components D,T,F,Co 1 OK. No leakage or damage detected

Break Clamps and

Calipers F,Co,C,W 1 OK. No wear signals detected

Cooling

system/circuit Cf, D, T 1 OK. Good general conditions

Clutch or flexible

element D,Co,C,L 1 OK. Good conditions

Sliding rings D,Co,W 1 OK. No carbon dust and good visual external conditions

Electrical

connections Co, W 1 Ok. No wear or damage detected marks

Generator

Manuf., serial

n.,kW,… Not Inspected for manufacturer constraints

General Co, W, F, L 1

Cable Connections Co, F 1 -

Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1

Protective covers D, Co 1 OK. No damage detected

Hub D, Co, C 1 Not Inspected for manufacturer constraints (wind speed above 16 m/s)

Coupling elements D, Co, L 1 N/A

Pitch mechanism D,F,N,Co,L 1 -

Hydraulic

components D,T,F,Co 1

OK. No oil dripping and the rotating union is well preserved.

Blade tip brakes,

restoring spring D, F, Co 1 N/A

Blade adjustment, T, F, N, L 1 Not Inspected for manufacturer constraints (wind speed above 16 m/s)

Hub assy & Pitch

Blade bearing T, N, S 1 Not Inspected for manufacturer constraints (wind speed above 16 m/s)



PICTURE

Rotor locking

device D, Co, Sp 2

The functioning was not tested as the wind speed was over the permitted

limits for locking the hub. Although some marks of bad locking operations

were detected. This is not a critical issue but increase the axial load over the

main bearing. The O&M staff should be trained in carrying out this operation

without damaging the locking disc.

Manuf., serial n., G40P/310 /2343 kg

Blade structure D, C 1 OK

Blade connection D,T,Co,C 1 OK. Good visual external condition

Bolted connections Co, Ps 1 OK. Good Condition

Blade Surface D, C, Co 1 OK. The surface was visually inspected from the nacelle and no damage was

detected.

Blades

Anemometer D, F, Co, Cf 1 OK. Good external visual conditions

Windvane D, F, Co, Cf 1 OK. Good external visual conditions

Wind

Sensors

Vibration switch Cf, D, F 1 OK. Tested and working well

Overspeed gauge F 1 Not Inspected

Emergency push

buttons F 1 OK. Tested and working well

Lap Counter F 1 OK. Good Visual condition

Short circuit

protection F 1 OK. Good Visual condition

Fire extinguisher,

first aid box E 1 OK. Present in nacelle

Safety system


Tested for: Damage D Connection, fitting Cf

Examined E Tightness T

Noise N Function F

Cracks C Corrosion Co

Safety sign plates Sp Lube/oil level / leakage L

Prestress Ps Wear W

CLASS OF DAMAGE IN VISUAL TURBINE INSPECTIONS

1 Good working condition.

The component or equipment is typical for its age. May show some signs of wear although it is serviceable and no further

action is needed.

2 Early signs of wear or damage.

Slightly damaged or worn equipment and/or missing part which presents no potential impact on turbine operation.

Equipment should be monitored for progression of damage. Equipment does not need to be repaired or replaced.

3 Advanced wear or damaged.

Equipment and/or missing part which presents a potential impact to the operation of the turbine. Should be scheduled for

repair or replacement at next scheduled service. Should be monitored until repairs or replacement takes place.

4 Failed or missing components.

The component has failed and represents a critical impact to the operation of the turbine and/or a safety hazard.

Component must be taken out of service to prevent further damage. Immediate action to repair or replace is required

before returning the turbine back to service.







Comments:

DISPLAY READINGS

On-line/off-line: Off line1 Energy Meters



Power output (kW): 1999.7 Energy past month (MWh) 506

Wind speed (m/s): 16.6 Producible Energy present year (MWh) N/A1



Time Meters

Total (h) 2135

No Service (h) 1987

Line OK (h) 1987


Turbine OK (h) 1657

Gen (h) 1350

Availability


Availability (%) 98.2 92.3 100

Temperatures (SCADA fields)1 Min (ºC) Actual (ºC) Max (ºC)

Environment N/A 26 N/A

Nacelle N/A 34 N/A

Hydraulic N/A 48 N/A

Gearbox N/A 76 N/A

Gearbox Oil N/A 70 N/A

Bearing Opposite side of the Coupling N/A 62 N/A

Bearing Coupling side N/A 61 N/A

Environment Spinner N/A N/A N/A

Trafo 3 phases N/A 88/95/91 N/A

Converter ABB N/A N/A N/A

Hub Top box N/A N/A N/A

Slip rings N/A 44 N/A

Winding 3 N/A 102/101/100 N/A

Environment Sonic sensor N/A 26 N/A


1 The wind turbine was offline at the moment of the inspection as the fuses of WT transformer were being changed. The display values are only a

reference and comes from the SCADA installed in the SET.


Operating manual

Building permit



Maintenance reports









PICTURE

Grouting D, Co, C 1 Ok. No cracks or other issue detected / Inside Foundation-tower sealing

well preserved.



Foundation

Manuf., serial


Door D, Co, Cf 2

The dust ingress was noted in the base platform of the tower. GAMESA



conditions.




Coating D, C, Co 1 OK, Good general condition.



Tower




Breaker, switch, fuse Cf, D, W 1 OK. No burn signal







Electric cabinets



Brakes/Sliding blocks D, Co, Cf 1 OK. Good conditions

Hoses incl. couplings D,T,Co,C 1 OK. No leakage detected

Gear ring D,F,N,Co,L 1 OK. No leakage or wear detected


Yaw M

echanism



PICTURE



Accumulators T,Co,L,Ps 1 Ok. No oil leakage was noted.

Hoses incl. couplings D,T,Co,C, L 1 OK. No leakage detected

Hydraulics







Bolts D, N, Co 1 OK. Good general condition.

Cooling system D, F OK. No damage detected and the system was working well

Nacelle

Main Bearing



Shaft coupling



Manuf., serial n.,


Gearbox Torque



Very small signs of micropitting are starting to be perceptible over the

wheel of the low speed shaft.

Cooling




Gearbox

Manuf., serial


Hydraulic


Break Clamps and


Generator

Cooling




PICTURE

Clutch or flexible



Electrical


Manuf., serial




Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1





Hydraulic



Blade tip brakes,




Rotor locking device D, Co, Sp 1 The functioning was not tested as the wind speed was over the permitted

limits for locking the hub.

Hub assy & Pitch





Blade Surface D, C, Co 1 OK. The surface was visually inspected from the nacelle and no damage

was detected.

Blades



Wind

Sensors



Emergency push



Short circuit


Fire extinguisher,


Safety system




Noise N Function F



Prestress Ps Wear W




action is needed.

















Comments:

DISPLAY READINGS




Power output (kW): 0 Energy past month (MWh) 705




Time Meters

Total (h) 1994

No Service (h) 1839

Line OK (h) 1839


Turbine OK (h) 1780

Gen (h) 1537

Availability


Availability (%) 96.82 99.26 98.82



Nacelle 29 31 41

Hydraulic 34 34 50

Gearbox 47 51 81





Trafo 3 phases 81/93/86 89/100/93 121/130/127


Hub Top box 31 31 42

Slip rings 36 39 55

Winding 3 59/57/57 70/68/68 115/116/115



The actual temperature of the converter should be reviewed. GL GH recommends checking the sensors and cable connections of the converter

temperature sensor..


Operating manual

Building permit



Maintenance reports









PICTURE


well preserved.



Foundation

Manuf., serial





conditions.

Hatches / Platform D, Cf, F 2

The rubber of the platform should be repaired.



Coating D, C, Co 2

An oil escape from the hydraulic pitch system has stained the tower. The

oil has fallen from the hub spinner and has accumulated in both sides of the

tower forming 90º with the wind predominant direction.



Tower



PICTURE











Electric cabinets







Yaw M

echanism





Hydraulics



Nacelle cover D, Co, C 2

The support of the sound foam is detached. GL GH recommends repairing

the same.





Cooling system D, F 1 OK. No Damage and working well.

Nacelle

Main Bearing



Main Shaft

Shaft coupling




PICTURE

Main shaft bearings T, N, L 1 OK. Good general condition

Manuf., serial n.,


Gearbox Torque



A pressure area was located over the pinion of the intermediate speed shaft.

This early wear signal should be monitored in order to establish if the

damage is increasing with the time or if is staying like this. GL GH

recommends constant visual monitoring with the services.

Cooling




Gearbox

Manuf., serial


Hydraulic


Break Clamps and


Cooling


Clutch or flexible



Electrical


Generator

Manuf., serial




Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1


Hub assy

& Pitch

Hub D, Co, C 2

A thin oil layer was detected over the hub internal surface- The same has

come from an old oil leakage. GL GH recommends cleaning the internal

surface of the hub.



PICTURE


Pitch mechanism D,F,N,Co,L 1 OK. No grease escape and good visual condition.

Hydraulic



Blade tip brakes,


Blade adjustment, T, F, N, L 1 OK.

Blade bearing T, N, S 1 OK. No grease escape was detected over the blade.

Rotor locking device D, Co, Sp 2



were detected. This is not a critical issue but increase the axial load over

the main bearing. The O&M staff should be trained in carrying out this

operation without damaging the locking disc.


Blade structure D, C 1 OK Good visual external condition




was detected.

Blades



PICTURE



Wind

Sensors



Emergency push



Short circuit


Fire extinguisher,


Safety system



Noise N Function F



Prestress Ps Wear W




action is needed.

















Comments:

DISPLAY READINGS



Blade pitch angle (deg): 83 Energy actual month (MWh) 817





Time Meters

Total (h) 1964

No Service (h) 1947

Line OK (h) 1947


Turbine OK (h) 1906

Gen (h) 1714

Availability


Availability (%) 97.93 100 99.98



Nacelle 30 33 41

Hydraulic 43 48 52

Gearbox 61 75 80





Trafo 3 phases 82/89/86 112/121/119 122/130/129



Slip rings 35 47 55

Winding 3 70/69/69 106/105/105 117/116/116




Operating manual

Building permit



Maintenance reports









PICTURE

Grouting D, Co, C 2

Small cracks were detected over the concrete surface of the foundation.

GL GH recommends sealing the cracks in order to avoid water ingress and

future issues related with corrosion or more internal concrete damage.



Foundation

Manuf., serial




Stairs, safety D, Co, F, Sp 2

One step of the internal tower stairs is bent. GL GH recommends repairing

the damage returning the original resistance properties to the material of

the stairs.




Coating D, C, Co 1 OK, Good general condition.



Tower



PICTURE







Switch gear D, T, Co, Sp 1 OK. No sound or wear detected



Converter D, T, Co, Sp 1 OK. No damage detected

Electric cabinets


Yaw Bearing D, F, N, Co, L 1 OK. No sound or vibration detected during the test


Hoses incl. couplings D, T, Co, C 1 OK. No leakage detected

Gear ring D, F, N, Co, L 1 OK. No leakage or wear detected

Drives D, F, N, Co, L 1 OK. No leakage or wear detected

Yaw M

echanism



Accumulators T, Co, L, Ps 1 Ok. No oil leakage was noted.

Hoses incl. couplings D, T, Co, C, L 1 OK. No leakage detected

Hydraulics








Cooling system D, F OK. No damage detected and the system was working well

Nacelle

Main Bearing



Shaft coupling



Manuf., serial n.,


Gearbox

Gearbox Torque

reaction arms D, Co, C, W 1

OK. In good general conditions



PICTURE


Adhesion by pass particles was located over the low speed shaft.

Cooling




Manuf., serial

n.,kW,… Cantarey Reynosa (GAMESA), CR 20-5 G90, Nº 468665, año 2010, 2040kW

Hydraulic

components D, T, F, Co 1 OK. No leakage or damage detected

Break Clamps and

Calipers F, Co, C, W 1 OK. No wear signals detected

Cooling


Clutch or flexible

element D, Co, C, L 1 OK. Good conditions

Sliding rings D, Co, W 1 OK. No carbon dust and good visual external conditions

Electrical


Generator

Manuf., serial




Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1




Pitch mechanism D, F, N, Co, L 1 -

Hydraulic

components D, T, F, Co 1


Blade tip brakes,



Hub assy & Pitch




PICTURE

Rotor locking device D, Co, Sp 2



were detected. This is not a critical issue but increase the axial load over

the main bearing. The O&M staff should be trained in carrying out this

operation without damaging the locking disc.



Blade connection D, T, Co, C 1 OK. Good visual external condition



was detected.

Blades



Wind

Sensors



Emergency push



Safety system

Short circuit

protection F 1

OK. Good Visual condition



PICTURE

Fire extinguisher,

first aid box E 2

The fire extinguisher was not located in the right place.



Noise N Function F



Prestress Ps Wear W




action is needed.

















Comments:

DISPLAY READINGS




Power output (kW): 1690 Energy past month (MWh) 618




Time Meters Energy past year (MWh) 3435

Total (h) 2699 Producible Energy past year (MWh 2597

No Service (h) 2699

Line OK (h) 2690


Turbine OK (h) 2500

Gen (h) 1731

Availability


Availability (%) 92.97 100 100



Nacelle 28 31 41

Hydraulic 37 45 53

Gearbox 57 75 78





Trafo 3 phases 78/98/84 104/130/111 107/130/118



Slip rings 47 58 66

Winding 3 56/55/57 96/94/94 114/113/114



The production of the past year is above any logical value regarding the producible energy range for the same period. GL GH recommends the

checking of the production counters regarding the inconsistency.


Operating manual

Building permit



Maintenance reports









PICTURE


well preserved.



Foundation

Manuf., serial





conditions.

Hatches / Platform D, Cf, F 1 OK. Good general conditions



Coating D, C, Co 1 OK. Good visual condition.



Tower







Switch gear D,T,Co,Sp 1 OK. No sound or wear detected.




Electric cabinets







Yaw M

echanism





Hydraulics








Cooling system D, F OK. No Damage and working well.

Nacelle

Main Bearing



Main Shaft

Shaft coupling




PICTURE

Main shaft bearings T, N, L 1 OK. Good general condition

Manuf., serial n.,


Gearbox Torque



Scratches by pass particles were located over the pinion of the intermediate

speed shaft and over the pinion of the high speed shaft.

The high speed shaft.

Cooling




Gearbox

Manuf., serial


Hydraulic


Break Clamps and

Calipers F,Co,C,W 1 OK. No wear signals detected G

enerator

Cooling Cf, D, T 1 OK. Good general conditions



PICTURE

system/circuit

Clutch or flexible



Electrical


Manuf., serial




Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1


Hub D, Co, C 1 OK. Clean, no leaks, good internal cable connections.


Pitch mechanism D,F,N,Co,L 1 OK. No grease escape and good visual condition.

Hydraulic



Blade tip brakes,


Blade adjustment, T, F, N, L 1 OK.

Blade bearing T, N, S 1 OK. No grease escape was detected over the blade.

Rotor locking device D, Co, Sp 1 Ok. Working properly

Hub assy & Pitch

Manuf., serial n., G40P/2330 kg





was detected.

Blades



Wind

Sensors



Emergency push



Short circuit


Fire extinguisher,


Safety system




Noise N Function F



Prestress Ps Wear W




action is needed.

















Comments:

DISPLAY READINGS








Time Meters

Total (h) 2015

No Service (h) 2006

Line OK (h) 2006


Turbine OK (h) 1891

Gen (h) 1686

Availability


Availability (%) 94.33 92.45 100



Nacelle 29 35 42

Hydraulic 31 48 50

Gearbox 35 75 75





Trafo 3 phases 76/98/76 104/127/114 109/130/117



Slip rings 31 50 58

Winding 3 38/38/38 108/107/109 111/108/109




Operating manual

Building permit



Maintenance reports









PICTURE


well preserved.



Foundation

Manuf., serial n.,

height Trinity/ 100182992/G80-2MW/ 67m




conditions.




Coating D, C, Co 2

An oil escape from the hydraulic pitch system has stained the tower. The

oil has fallen from the hub spinner and has accumulated in both sides of

the tower forming 90º with the wind predominant direction.

Lighting Cf, D, Co 1 OK. Without damage and working well


Tower




Breaker, switch,

fuse Cf, D, W 1 OK. No burn signal







Electric cabinets



Yaw

Mechanism

Brakes/Sliding

blocks D, Co, Cf 1 OK. Good conditions



PICTURE

Hoses incl.

couplings D,T,Co,C 1 OK. No leakage detected






Hoses incl.

couplings D,T,Co,C, L 1 OK. No leakage detected

Hydraulics



Nacelle cover D, Co, C 2

The support of the sound foam is detached. GL GH recommends repairing

the same.



Nacelle

Coating D, C, Co 2

Oil from the leak mentioned in the tower section of this checklist has

accumulated in the front cooling fan duct of the nacelle. GL GH

recommends cleaning the same in order to avoid dirtiness inside the

nacelle.



PICTURE

More oil from the mentioned oil escape was detected over the coating of

the nacelle.


Cooling system D, F 2

The motor device in charge of opening the windows for cooling the nacelle

is damage and should be repaired. The issue is not critical but the nacelle

and the major components temperature alarms will increase during

summer if the component is not repaired.

Main Bearing



Shaft coupling



Manuf., serial n.,


Gearbox Torque


Parallel stage D, Co, C 1 OK. Good general condition Gearbox

Cooling

system/circuit Cf, D, T, L 1 Ok. No oil leaks and well general condition.



PICTURE


Cabling fittings Cf, D, Co 1 OK. Good general condition

Manuf., serial


Hydraulic


Break Clamps and


Cooling


Clutch or flexible



Electrical


Generator

Manuf., serial




Grounding Co, F 1 -

Oil level F 1 -

MV. Transform

er

1





Hydraulic



Blade tip brakes,




Rotor locking

device D, Co, Sp 1


limits for locking the hub

Hub assy & Pitch






was detected.

Blades



Wind

Sensors



Emergency push



Short circuit


Fire extinguisher,


Safety system




Noise N Function F



Prestress Ps Wear W




action is needed.











ABOUT DNV GL Driven by our purpose of safeguarding life, property and the environment, DNV GL enables organizations to advance the safety and sustainability of their business. We provide classification and technical assurance along with software and independent expert advisory services to the maritime, oil and gas, and energy industries. We also provide certification services to customers across a wide range of industries. Operating in more than 100 countries, our 16,000 professionals are dedicated to helping our customers make the world safer, smarter and greener.

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