Managing transients in isolated Systems with Large Wind Power Penetration

Crete experience

By

John StefanakisPPC-GREECE Renewable

Energy Sources Department

About transients

Voltage transients (VTs)• Voltage dips (Short Circuits in the Grid)• Voltage surges (lightnings, switching

operations) Frequency transients (FTs)

• Frequency dips (loss of generation)• Frequency surges (loss of consumption)

Voltage transients (VTs)

Induce deferent Voltage changes ΔV through out the Grid. At the point of the Fault Voltage becomes zero. Away from the

point of the Fault, ΔV is inversely proportional to the total Thevenin’s Impedance between the point of reference and the point of Fault.

VTs at height Voltage grid influence the whole grid but last for a short time (usually less than 100msec)

VTs at low Voltage grid influence part of the Grid but, because of application of Protection’s Selectivity Principle, they may last for a long time (even more than one sec).

ΔV may cause WT trip if the resulting Voltage level AND the transient’s duration exceeds certain limits set by the manufacturer of the WT.

The old generation of WTs is very sensitive regarding VTs. New “Grid-Compatible” WTs, promise they can overcome the

problem.

Voltage Transients in Isolated Power Systems

Severe voltage dips because of the weakness of the Systems.

WF outages because of VDs Grate number of weather-induced faults

(lightnings, sea pollution, strong winds). Difficulties recovering after a loss of generation

event because of lack of interconnections.

Typical Voltage dip profile and its propagation through the System

10

20

30

40

50

60

70

80

90

100

-100 0 100 200 300 400

% Nominal (V)

mSecs

1220165-001/002 at PPC GREECE - 28/12/2000 05:48:12.259

P 50 VAP 50 VBP 50 VC

Vth(90%)

10

20

30

40

50

60

70

80

90

100

110

-100 0 100 200 300 400 500

% Nominal (V)

mSecs

1220165-005/008 at SUBSTATION MIRES - 28/12/2000 05:51:40.723

M/S 2 PH AM/S 2 PH BM/S 2 PH C

Vth(90%)

10

20

30

40

50

60

70

80

90

100

110

-100 0 100 200 300 400 500

% Nominal (V)

mSecs

1220165-005/009 at substation Ierapetra - 28/12/2000 05:54:46.219

VOLT M/S Ph AVOLT M/S Ph BVOLT M/S Ph C

Vth(90%)

Voltage profile at 150 kv Linoperamata Substation’s Buses during a single-face fault in face C

Voltage profile during the same fault at 20 kv Mires Substation’s Buses (50 Km away of fault’s site)

Voltage profile during the same fault at 20Kv Ierapetra Substation’s Buses (150 Km away of fault’s site)

WIND-FARMS OUTAGES OWING TO SYSTEM'S VOLTAGE DIPS

MIRES S/S MARONIA S/S

TO

PLO

U

RO

CA

S

AEO

LO

S

XIR

OLIM

NI

IWEC

O

AC

HLA

DIA

KR

IA

AN

EM

OES

SA

1 15.02/18.03.99 2 3,1 - 0,4 9 - 4,7 * * * * 12.1 176,5 6,9 - - - -

2 15.35/18.03.99 2 3,4 - 0 8,5 - 4,4 * * * * 11,9 174,5 6,8 UFL 24 3 to 7 2

3 18.32/07.07.99 1 8,5 - 0 8,5 - 0 4 - 4 * 2,6 - 2,7 * 23,6 316,4 7,5 - - - -

4 09.25/26.08.99 1 4,3 - 4,3 7,0 - 3,5 3,3 - 3,5 * 4 - 3,9 * 18,7 306,4 6,1 - - - -

5 14.25/14.09.99 5 # 0,3 - 0 1,4 - 0 * 0,9 - 0 * 2,6 293,0 0,9 - - - -

6 17.46/17.10.99 1 # 4,8-0 2,9-0 * 2,9-1,5 8,5-0 19,0 203,1 9,3 - - - -

7 05.58/27.10.99 1 # 6,9 - 3,8 5,3 - 0 * 3,3 - 2,7 13,8 - 13,3 28,3 139,8 20,2 - - - -

8 04.49/18.02.00 1 # 8,8 - 5,9 0,4 - 0 * 0,5 - 0,5 24,5 - 0 34,2 120,9 28,3 - - - -9 17.04/19.03.00 3 # 6,9 - 6,5 1,9 - 1,2 * 3,8 - 3,8 20 - 0 32,6 186,2 17,5 ROCOF 7,5 3 to 4 0,4

10 00.36/11.04.00 5 # 8,4 - 8,4 2,7 - 0 * 0 - 0 25,5 - 0 36,5 146,0 25,0 ROCOF 6,5 4 to 5 0,611 01.09/11.04.00 5 # 8,5 - 8,5 0,5 - 0,4 * 0 - 0 22,7 - 0 31,7 129,5 24,5 ROCOF 6,5 0 to 6 0,612 02.58/12.04.00 5 # 6,0 - 6,5 3,5 - 0 * 1,5 - 0 0 - 0 9,5 125,9 7,5 - - - -13 06.34/12.04.00 5 # 6,2 - 5,9 3,5 - 0 * 2,2 - 0 2 - 0 11,9 130,4 9,1 - - - -14 02.54/17.04.00 1 # 1,3 - 0,4 1,8 - 0 * 0 - 0 0,5 - 0,3 3,6 127,0 2,8 - - - -15 00.52/05.05.00 2 # 9 - 8,4 7,9 - 0 * 4,1 - 0 5,9 - 0 22,7 175,1 13,0 UFL 6 0 to 4 0,416 06.20/28.06.00 1 3,9 - 3,9 8 - 3,5 8 - 0 4 - 0 4,7 - 4,7 24 - 21 52,6 173,7 30,3 ROCOF 25 2 to 3 1,117 10.35/28.06.00 1 0,3 - 0,3 2,4 - 2,4 0 - 0 8 - 0 4,7 - 4,7 1,8 - 1,5 12,6 288,1 4,4 ROCOF 33 3 to 12 3,818 22.29/28.07.00 5 0 - 0 0,7 - 0,6 0 - 0 0 - 0 1,0 - 0 0 - 0 1,7 400,0 0,4 - - - -19 22.50/28.07.00 5 0 - 0 0,5 - 0,6 0 - 0 0 - 0 1,0 - 0 0 - 0 1,5 353,0 0,4 - - - -20 00.37/13.08.00 1 4,4 - 4,2 7,3 - 2,2 7,1 - 0 9,0 - 0 4,3 - 4,2 23,0 - 23.0 55,2 271,3 20,3 - - - -21 17.17/14.08.00 1 3,9 - 3,9 7,8 - 0 6,7 - 0 8,5 - 0 4,3 - 2,1 22,8 - 21,5 54,0 276,4 19,5 UFL 43 2 to 8 3,422 13.32/26.08.00 1 4,2 - 4,2 8,3 - 0 5,2 - 0 7,5 - 0 2,9 - 0 10,2 - 9,3 38,3 346,0 11,1 UFL 18,1 7 to 11 2,823 00.39/28.08.00 1 4,2 - 4,2 4,1 - 0,7 5,2 - 0 4 - 0 1,5 - 0 9,7 - 8,6 28,8 255,1 11,3 UFL 10 3 to 4 0,524 15.48/08.09.00 1 0,5 - 0 1,3 - 0 0,9 - 0 1,6 - 0 0 - 0 5,0 - 4,6 9,2 287,0 3,2 - - - -25 21.56/12.09.00 4 3,0- 0 7,5 - 0,5 5,9 - 0 8,3 - 0 1,8 - 0 17,3 - 0 43,9 326,9 13,4 ROCOF+UFL 42,5 3 to 34 7,126 22.31/12.09.00 4 1,90 - 0 4,8 - 3,6 7,4 - 0 6,2 - 0 2,8 - 0 11,3 - 0 34,4 301,2 11,4 MT 34,7 2 to 3 0,127 10.07/16.09.00 1 2,5 - 2,5 6,0 - 0 7,5 - 0 5,5 - 0 0 - 0 11,5 - 11,5 33,0 302,0 10,9 - - - -

Fault category

123

# 4* 5

Fault

cate

gory

Pow

er

Regecte

d [M

W]

Tota

l Dem

and [M

W]

Tota

l W/F

pro

ductio

n

befo

r th

e F

ault

[MW

]

Outa

ge d

ura

tion

min

/max [m

in]

Penetr

atio

n

Explanation of colours and symbols

c/n

Energ

y L

oss [M

Wh]Load

compensation through

U/F Relays (ROCOF or UFL)

or Manual Triping (MT)

Hour/Date

W/F Production prior/after the Fault

SITIA S/S

Discription

Fault at W/F connecting Line

Total W/F outageLack of informationNot yet in operation

Partial W/F outageFault at outgoing Distribution Line from other S/S

Stable W/F operation

Fault inside Maronia W/F (20 KV network)Fault at Transmission System

Fault at outgoing Distribution Line from Sitia S/S

Fault-induced WFs-Outages

Rejected Load [MW]

Part of total [%]

1999 6 4 2 24 13,7

2000 19 13 6 43/25 15,6/18

2001 11 7 4 35,3 16,7

2002 4 0 4 30 12

2003 17 3 14 48,2 15

2004 7 3 4 19,2 18

Most serious event of the year

Years

Number of WFs-

Outages per year

Faults in Height

Voltage grid

Faults in Middle

Voltage grid

Disturbances: 14.02.2004 10:42 & 10:52

0

5

10

15

20

25

30

10:3

4

10:4

4

10:5

4

11:0

4

11:1

4

11:2

4

11:3

4

11:4

4

11:5

4

12:0

4

12:1

4

12:2

4

12:3

4

12:4

4

12:5

4

13:0

4

WF

Lo

ad [

MW

]

Time[min]

Faults in Transmission Lines 1978-2004

0

20

40

60

80

100

120

140

78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 00 01 02 03 04

Nu

mb

er

of

Fa

ult

s

0

24

6

8

1012

14

1618

20

22

2426

28

Fa

ult

s p

er

100K

m

Number of Faults

Faults per 100 Km

Frequency Transients

Induce the same Frequency changes ΔF all over the Grid.

ΔF is proportional to the Load imbalance. WTs of Current technology quite resistant to FTs. Consequence to the Grid rear but (in case of Frequency

Dips) fatal to the System because:• Affect all WFs irrespective of their location.• Load imbalance that causes the FT, is amplified by WFs outages

leading to unstable performance and very probably to Blackout.

Toward increasing Penetration

Small scale interventions

Wind Farm levelVoltage support facilitiesUpgrading Grid connectionsGrid friendly Wind Turbines

System levelStrengthening the GridPromoting geo-diversityAdopting Supportive infrastructures

The SCADA System Highly qualified personnel in Dispatch Center Sophisticated logismic tools

Typical demand for Voltage deviations

Time [msec]

150 1500 30001000500

0,8

0,15

0

1,0

0,9

0,5

Re

ma

inin

g V

olt

ag

e [

pu

]

PPC 's Curve

EON 's Curve

1900

Typical demand for Frequency deviations

Power

Frequency

WFs sites

Ag. Nikolaos

Sitia

Ierapetra

Maronia

Atherinolakos

Atherinolakos S/S

Ag. Antonios Moni Toplou

Rokas

Xirolimni

Aeolos

Maronia Complex

Oas

Pretoria

Mires

Stalida

Iraklion I Iraklion II

Iraklion III

Linoperamata 66KV

Linoperamata 150KV

Linoperamata

Voskero

Iweco

Heraklion Prefecture

Lasithi Prefecture

Toward increasing Penetration:Thinking big

The Energy Storage SystemsPump Storage SystemsFlying WheelsCompressed airBatteries (Redox Flow Batteries)

The interconnection with the Mainland System