grid code 3.2.3 power unit above 1,5 mw

8/22/2019 Grid Code 3.2.3 Power Unit Above 1,5 MW

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Technical Regulation for ThermalPower Station Units of 1.5 MW and higher

Regulation for grid connection TF 3.2.3

Version 5.1

1 October 2008


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Revision view

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Revision view

Section no. Text Version Date

Sections 2+3+13Appendix 1

Consolidation Act; Commencement; Measuring and Data Exchange; Layoutof Appendix 1; Regulation notified to the Danish Energy Regulatory Authority

5.1 09/2008

AllUpdated after public consultation and registered with the Danish EnergyRegulatory Authority

5 09/2007

All Updated and harmonised with TF 3.2.4 and submitted for public hearing 4 07/2007

2-3 Updated in connection with translation into English 3 07/2006

All Updated after public consultation 2 12/2005

All Updated and submitted for public consultation 1 2005

All Grid Committee consultation 0 2004

Working group:

Kaj Christensen, Energinet.dk

Jens Peter Kjrgaard, Energinet.dkJan Havsager, Energinet.dk

Per Lund, Energinet.dk

Frederik B. Olesen, Energinet.dk (prepared regulation)Carsten Strunge, Energinet.dk (prepared regulation)Sren F. Jensen, Energinet.dk (prepared regulation)

For a copy of the regulation, please contact:

Energinet.dkFjordvejen 1-11

DK-7000 FredericiaTel. +45 70 10 22 44

The regulation can be downloaded from www.energinet.dk


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Summary (not part of the regulation)

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Summary (not part of the regulation)This technical regulation is the Danish Grid Code, which includes provisions for thermalpower station units with an output of 1.5 MW electrical power or higher for connection to thepublic electricity supply gridin Denmark.

The regulation applies to newpower station units and existingpower station units which aremodified.

The regulation includes provisions regarding effective power, tolerance towards voltage andfrequency variations, grid faults, island operation, start and synchronisation, active powergeneration and frequency control, system stability, reactive power generation and voltagecontrol, protection, measurement,communication and data exchange,power station unitstructure, operation and maintenance, verification, documentation and non-performance.

Apower station unitmust be equipped with synchronous generator according to theprovisions in subsection 10.1.

The regulation replaces previous specifications and recommendations issued by Eltra andElkraft, now merged into Energinet.dk, covering Western and Eastern Denmark, respectively.


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Table of contents

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Table of contents

Revision view ........................................................................................................... 2

Summary (not part of the regulation) .......................................................................... 3Table of contents ...................................................................................................... 4

Introduction (not part of the regulation)....................................................................... 5

1. Definitions....................................................................................................... 6

2. Objective .......................................................................................................11

3. Scope............................................................................................................12

4. Effective power ...............................................................................................13

5. Tolerance towards frequency and voltage deviations.............................................15

6. Tolerance towards grid faults ............................................................................19

7. Island operation..............................................................................................22

8. Start and synchronisation.................................................................................24

9. Active power production and frequency control ....................................................26

10. System stability ..............................................................................................30

11. Reactive power generation and voltage control ....................................................31

12. Protection ......................................................................................................34

13. Metering, communication and data exchange ......................................................36

14. Power station unit structure ..............................................................................37

15. Operation and maintenance ..............................................................................38

16. Verification and documentation .........................................................................39

17. Non-compliance ..............................................................................................43

18. Exemptions and unforeseen circumstances..........................................................44

Appendix 1: Documentation ......................................................................................45

Appendix 2: Required relay protection at plants with synchronous generator ....................66

Appendix 3: Supplementary relay protection at plants with synchronous generator............67

Appendix 4: Comments (not part of the regulation) ......................................................68

Appendix 5: Previous provisions (not part of the regulation)...........................................84

Appendix 6: Reference list (not part of the regulation) ..................................................85


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Introduction (not part of the regulation)

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Introduction (not part of the regulation)

Requirements and delimitation

This technical regulation is part of the complete set of technical regulations issued byEnerginet.dk, the Danish Transmission System Operator (TSO). The technical regulations

comprise technical rules for the players regarding the connection to and operation of thepublic electricity supply grid. Together with the market regulations, the technical regulations,including the system operation regulations, constitute the non-discriminating set of rules tobe complied with by the players. The current version of the technical regulations is availableat www.energinet.dk.

This technical regulation is the Danish Grid Code, which includes provisions for thermalpower station units with an output of 1.5 MW electrical power or higher for connection to thepublic electricity supply gridin Denmark. The regulation includes provisions regarding theproperties which thepower station units must incorporate and retain throughout their servicelives. System operational conditions forpower station units are regulated in other

regulations.

Definitions and comments

This regulation makes extensive use of definitions. These are described in the first section ofthe regulation. In the text, definitions are written in italics.

Special reference is made to the section with comments at the end of the document. Thissection can contribute to creating an overview of the provisions and an understanding of thebackground and consequences of the provisions. This section is not part of the regulationitself, a fact which can also be seen from the headings.

Responsibility for the regulation

The TSO is responsible for the technical regulations and for ensuring that the regulations areobserved and continuously adapted to the futurepublic electricity supply gridin Denmark.

The technical regulations are enforced by the individual electric power utilities. The TSO canissue a written permission to depart from the regulations.

Furthermore, reference is made to Section 26(1) of the Danish Electricity Supply(Consolidation) Act no. 1115 of 8 November 2008, see Section 7 of the Danish(Consolidation) Act on Transmission System Operation and the Use of the ElectricityTransmission Grid no. 1463 of 19 December 2005.

Authority requirements and standardsAllpower station units must comply with Danish legislation, including the Danish HeavyCurrent Regulation and the Joint Regulation of the electric power utilities. In areas notcovered by Danish legislation or by technical regulation TF 3.2.3, the CENELEC standardsapply, and in areas where there are no such standards, the ISO and IEC standards apply.

In case of any discrepancy between the Danish text and the English translation, the Danishtext shall prevail.


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Definitions

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1. Definitions

1.1 Operation1.1.1 House-load operationOperating condition in which apower station unitis operated in isolation from thepublicelectricity supply gridand with its own auxiliary power consumption as the only load.

1.1.2 Ready stateApower station unitis in ready state when it is able to start from a cold/warm state in thetime indicated in Appendix 1 for thepower station unit.

Ready state is the basis of the definitions starting time until synchronisation and startingtime until full generation.

1.1.3 External operating conditionsExternal conditions comprising, for example, cooling water temperature, outdoortemperature, air pressure, and relative humidity which impact on the effective powerandwhich cannot be controlled by thepower stationoperator.

1.1.4 Nominal external operating conditionsExternal operating conditions in which nominal maximum powerand nominal minimumpowerare stated.

1.1.5 Normal operating conditionThe process, configuration and connection for which apower station unithas been designedand in which apower station unitis normally operated.

The configuration of a plant may deviate from normal operating condition when, forexample, faults occur in parts of the unit, during start-up and shutdown, during house-loadoperation, or when the unit operates at overload.

Doubts may arise as to the definition ofnormal operating condition, if for instance apowerstation unitunder normal conditions is operated both with and without heat production orwith different fuel types. If there is any doubt about how to define normal operatingcondition, the TSO must in consultation with thepower station operatordecide what is to beconsidered normal operating condition and may demand that the provisions in thisregulation be met in different operating conditions.

1.1.6 Isolated island operationOperating condition that occurs when apower station unitsupplies an isolated grid areaeither alone or as a significant unit.

1.1.7 Island operationMode of operation comprising house-load operation and isolated island operation.

1.2 Power1.2.1 Effective powerThe sum of the active electrical power estimated with signs, which apower station unitexchanges with the grid at the connecting points. The power flow direction from thepowerstation unitto thepublic electricity supply gridis considered to be positive.


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Definitions

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1.2.2 Maximum powerThe maximum effective powerwhich apower station unitcan supply continuously in normaloperating condition under the current external operating conditions and by observing thefull-load voltage frequency range at the connecting points.

It should be noted that the maximum powerfluctuates with the externaloperatingconditions and is thus not a fixed value. See also nominal maximum power.

1.2.3 Highest maximum powerThe highest maximum power under typical external operating conditions.

1.2.4 Lowest maximum powerThe lowestmaximum powerunder typical external operating conditions.

1.2.5 Nominal maximum powerMaximum effective powerwhich apower station unitcan supply continuously in normaloperating condition under nominal external operating conditions and by observing the full-load voltage-frequency range at the connecting points.

Unlike maximum power, nominal maximum poweris a fixed number, which is independentof the external operating conditions.

1.2.6 Minimum powerThe minimum effective powerwhich apower station unitcan supply continuously in normaloperating condition under the current external operating conditions and by observing thefull-load voltage-frequency range at the connecting points.

It should be noted that the minimum powerfluctuates with the externaloperatingconditions and is thus not a fixed value. See also nominal minimum power.

1.2.7 Nominal minimum powerMinimum effective powerwhich apower station unitcan supply continuously in normaloperating condition under nominal external operating conditions and by observing the full-load voltage-frequency range at the connecting points.Unlike minimum power, nominal minimum poweris a fixed number, which is independent ofthe external operating conditions.

1.3 Full load1.3.1 Full-load frequency rangeFrequency range in a connecting pointat which apower station unitcan supply maximumpower.

1.3.2 Full-load voltage-frequency rangeVoltage and frequency range in a connecting pointat which the frequency lies within thefull-load frequency range, and the voltage lieswithinthe full-load voltage range, and atwhich apower station unitcan supply maximum power.

1.3.3 Full-load voltage rangeVoltage range in a connecting pointat which apower station unitcan supply maximumpower.


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Definitions

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1.4 Generator feeder

Electrical connection that links the generator/machine transformer to thepublic electricitysupply grid.

1.5 Main fuelFuel whose share makes up more than 80% of the total energy input into apower stationunitin normal operating condition.

1.6 Public electricity supply gridTransmission and distribution grids that transmit electricity for an indefinite group ofsuppliers and consumers on the terms dictated by public authorities.

1.7 Short-circuit ratioThe relation between the current in a synchronous generators field winding at rated voltageon an open stator winding and the current in the field winding at rated current on a short-circuited stator winding.

1.8 Power station unitA facility which produces three-phase alternating current and where there is a directlyfunctional correlation between its main components (eg boiler, turbine and generator).

In case of doubt, a facility consisting of two units, each with a boiler, a turbine and agenerator, should be considered as twopower station units. A facility consisting of acombined-cycle plant (combi plant) should be considered as onepower station unit. Afacility consisting of three gas engines operating at part load during the shutdown of one ormore of the engines is to be considered as onepower station unit.

In case of doubt, the transmission system operator makes the decision based on whether a

facility can be considered as consisting of one or morepower station units in accordancewith the rules in this regulation.

1.9 Power station operatorEnterprise that runs apower station unitand is responsible for the operation hereof throughownership or contractual agreements.

1.10 Power schedule (load plan)A plan stating the quantity of electricity to be generated in a specific period.

1.11 Load control

Control following a locally ordered change ofeffective power, ensuring the desired powergeneration.

1.12 Point of common coupling (PCC)Connecting pointwhere the electricity produced is supplied to thepublic electricity supplygrid. Where installation-connectedpower station units are concerned, thepoint of commoncoupling is the point where the installation is connected to thepublic electricity supply grid.Auxiliary supply facilities can (particularly during start) be connected to a connecting pointthat is not thepoint of common coupling. At smallpower station units, thepoint of commoncoupling and the connecting pointare often the same. See also the definition ofconnectingpointand the comments in Appendix 4.

1.13 Nominal voltageThe voltage in a connecting pointfor which the system has been designed.


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Definitions

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1.14 Overload capacityThe effective powerwith the exception ofmaximum powerthat apower station unitcansupply to the grid for at least one hour at a time under nominalexternal operatingconditions, complying with the full-load voltage-frequency range in the connecting points.

Overload capacitycan be obtained, for instance, by disconnecting the heat production of apower station unitnormally operated with heat production or by disconnecting high-pressure preheaters in a steam power plant. The result of overload operation is oftenreduced efficiency, increased costs and/or reduced plant life.

1.15 Power/frequency controllerControl system in apower station unitthat quickly and automatically controls the effectivepoweron the basis of frequency deviations.

1.16 Power frequency controlAutomatic control which ensures on a scale of seconds that the frequency is constant andthat production and consumption balance. The control is implemented in thepower/frequency controllerin the power station units.

1.17 Secondary controlControl achieved through a locally ordered change of the effective power, which can ensurethe desired power generation and adjust the frequency.

1.18 Starting time until full generationThe time that passes from apower station unitin ready state being ordered to start untilthepower station unitsupplies maximum power.

1.19 Starting time until synchronisationThe time that passes from apower station unit in ready state being ordered to start untilthe generator(s) of thepower station unitis/are synchronised and connected to thepublicelectricity supply gridand can supply active electrical power.

1.20 DroopChange in rotational speed (or change in frequency) causing the load on the electricgenerators drive engine to change from idling to full load. Droop is often stated in % ofrated rotational speed (or rated frequency).

1.21 tanCorrelation between the reactive electrical power and the active electrical power generated

by apower station unit. Reactive power is supplied to the grid at positive tan.

1.22 Thermal power station unitPower station unitproducing three-phase alternating current using a thermodynamicprocess.

1.23 Connecting pointThe point at which apower station unithas been electrically connected to thepublicelectricity supply grid. It should be noted that onepower station unitmay have severalconnecting points. See also the definitionofpoint of common coupling and comments inAppendix 4.

1.23.1 Grid connectionApower station unitisgrid connected if thepower station unitis connected directly to thepublic electricity supply grid.


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Definitions

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1.23.2Installation connectionApower station unitis installation connected if thepower station unitis connected to thepublic electricity supply gridvia a private electrical installation. This also applies even if thehouse load, if any, covers thepower station unit's entire power generation.

1.24 Typical operating voltageTypical operating voltage is determined by the electric power utility in the connecting point.Typical operating voltage is used for determining the full-load voltage range.


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Objective

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2. Objective

The objective of this technical regulation TF 3.2.3 is to specify the minimum technical anddesign requirements applying to thermal power station units with a nominal maximum powerof 1.5 MW electrical power or higher which are connected to thepublic electricity supplygrid.

Another objective is to ensure the technical quality and balance of thepublic electricitysupply grid. This includes the fulfilment of two basic technical conditions, namely that powergeneration can be adjusted continuously to the consumption and that the voltage can bemaintained.

To obtain a reliable and efficient electricity supply grid it is necessary to have coherentplanning, plant design and operation (from production facilities to consumers).

This regulation outlines the minimum requirements. If better properties can be achievedwithout incurring extra costs, it should be done.

2.1 Legislation

The regulation has been drawn up pursuant to Section 26(1) of the Danish Electricity Supply(Consolidation) Act no. 1115 of 8 November 2005, see Section 7 of the Danish(Consolidation) Act noon Transmission System Operation and the Use of the ElectricityTransmission Grid . 1463 of 19 December 2005.

2.2 Administration of the regulation

The technical regulations are administered by the electric power utility to whose grid thepower station unitis connected on behalf of the TSO. The TSO may give permission in

writing to depart from the regulation.

2.3 Complaints

This regulation has been registered with the Danish Energy Regulatory Authority. Complaintsabout the regulation can be lodged with the Danish Energy Regulatory Authority. Complaintsabout the TSO's enforcement of the provisions of the regulation can be lodged with theDanish Energy Regulatory Authority.

Complaints about how the individual electric power utility's enforcement of the provisions ofthe regulation can be lodged with the TSO.


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Scope

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3. Scope

Thermal power station units connected to thepublic electricity supply gridin Denmark inaccordance with sections 3.1 and 3.2 hereof must at any given time comply with theregulation.

In areas not covered by Danish legislation or by technical regulation TF 3.2.3, the CENELEC

standards apply, and in areas where there are no such standards, the ISO and IEC standardsapply.

3.1 New plants

The regulation applies to all thermal power station units with nominal maximum powerof 1.5MW electrical power or higher which are connected to thepublic electricity supply gridinDenmark and commissioned on 1 November 2008 or later.

3.2 Existing plants

Thermal power station units with nominal maximum powerof 1.5 MW or higher which wereconnected to thepublic electricity supply gridin Denmark before 1 November 2008 mustcomply with the regulation in force at the time of commissioning.

Existing plants which are modified substantially must comply with the provisions in thisregulation relating to the changes. A substantial modification affects one or more of theproperties discussed in this regulation. In cases of doubt, the TSO decides whether amodification is substantial or not.

3.3 Exemptions

The regulation does not apply topower station units transmitting the electricity generatedvia power converters.


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Effective power

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4. Effective power

4.1 Maximum power

Apower station unitmust constantly and continuously be capable of deliveringmaximum power, see the explanations below.

For apower station unitwith heat-load determined electricity production (eg a back-pressure plant), the time in which maximum powercan be delivered can be limited by asmall extraction of district heat.

For apower station unitwith independent electricity and heat production (eg anextraction plant), a reduction in the effective power is accepted because of a largeextraction of district heat.

In case of unusual voltages and/or frequencies in the connecting points and followinggrid faults, a reduction of the effective poweris accepted in accordance with sections 5and 6 hereof.

Nominal maximum powermust be stated in connection with the following nominalexternal operating conditions:

- Steam power plant: Cooling water temperature at intake 10 COutdoor temperature 8 C

- Gas turbines and gas engines: Outdoor temperature 15 C

Air pressure 1013 hPaRelative humidity 60%

- Other plants: Outdoor temperature 8 C

Typical mean annual values are used for any other external operating conditions, includingreturn flow temperature of district heating water.

Lowest maximum powerand highest maximum powermust be stated in connection withvalues ofexternal operating conditions within the following range:

- Outdoor temperature between -25 C and 35 C

- Relative humidity between 40% and 100%

- Air pressure between 960 hPa and 1050 hPa- Cooling water temperature at intakes between 0 C and 25 C.

Typical annual extremes are used for any other external operating conditions, includingreturn flow temperature of district heating water.

4.2 Overload capacity

There are no overload capacityrequirements for apower station unit.

According to Appendix 1, apower plant unitmust not deliver more effective powerthan thesum of the maximum powerstated and the overload capacitystated.


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Effective power

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4.3 Minimum power

Apower station unitmust constantly and continuously be capable of delivering minimumpower.

Depending on thepower station units thermodynamic process and main fuel, the minimum

powermust not exceed the percentage of the maximum powerstated in Table 1.

The upper allowable minimum powerwill be stated by the TSO for plant types and main fuelsthat are not stated in Table 1, includingpower station units with several different mainfuels.

Minimum powerPower station unit type and

main fuel[%]

Coal dust-fired steam power plant 35

Oil-fired steam power plant 20

Gas-fired steam power plant 20Bio dust-fired steam power plant 35

Straw-fired steam power plant 50

Wood chip-fired steam power plant 50

Fluid-bed coal-fired steam power plant 50

Waste-fired steam power plant 70

Gas engine 50 (35% for minimum 5 min.)

Gas turbine 20

Gas-fired combined cycle (combi plant)20% for gas turbine part

75% for steam turbine part

Diesel engine 50 (20% for minimum 5 min.)

Table 1 Upper allowable minimum power stated as a percentage of the maximum power

The minimum powerfor apower station unitwith nominal maximum powerup to 25 MW isallowed to be obtained by starting/stopping several unit components, eg gas engines, toobtain improved efficiency in the event of reduced effective power. Nevertheless, thepowerstation unitmust be capable of operating at any part load according to section 4.4 hereof.

It must be possible to regulate apower station unitto the minimum powerdirectly from thestart and from a condition with any other effective power.

4.4 Part load

Apower station unitmust constantly and continuously be capable of delivering any part loadbetween minimum powerand maximum powerwith the natural limitation attributable to theprocess of thepower station unit(eg start of coal mills and Benson transition) according tothe following explanations.

For apower station unitwith heat-load determined electricity production, the time in which agiven amount ofeffective powercan be delivered can be limited by a small extraction ofdistrict heat.

For apower plant unitwithindependent electricity and heat production (an extraction plant),

a reduction in the effective poweris accepted because of a large extraction of district heat.


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Tolerance towards frequency and voltage deviations

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5. Tolerance towards frequency and voltage deviations

Apower station unitmust be able to withstand voltage and frequency deviations in theconnecting points beyond the full-load voltage-frequency range while reducing the maximumpower as little as possible.

The requirements governing reactive power in case of voltage fluctuations are described inmore detail in section 11 hereof.

Figure 1 Frequency range, operating time and generation requirements.

5.1 Full-load voltage-frequency range

The full-load frequency range is 49.0 Hz-50.5 Hz. In the full-load frequency range it must be

possible to start and operate apower station unitcontinuously with automatic voltagecontrol within the full-load voltage range.

The full-load voltage range depends on the nominal voltage for the connecting pointasstated in Table 2 and Table 3.

47.5 49.0 50.5 51.0 53.0

Voltage (p.u.)

Minimumreduction

1 hour10% reduction

30 minreduction

0%

Continuousoperation

3 minNo generationrequirements

30 min

reduction 15%

at 47.5 Hz

Linearinterpolation

1 hour

10% reduction

UEH

UH

UHF

UTYP

ULF

UL

UEL

10 sec. No generation

requirements

Minimumreduction

47.0 Frequency(Hz)


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Nominalvoltage

Un

Lowervoltage

UL

Lowerfull-loadvoltage

ULF

Upperfull-loadvoltage

UHF

Uppervoltage

UH

[kV] [kV] [kV] [kV] [kV]

400 320 360 420 440

150 135 146 170 180

132 119 125 145 155

60 54 57 66 72.5

50 45 47.5 55 60.0

Table 2 Full-load voltage range in relation to upper and lower voltage limit.

In Table 2, fixed voltage values determining the full-load voltage range in the point ofcommon coupling are stated.

For voltages of 132 kV and higher the upper voltage limit is higher than recommended in EN60038 due to brief high voltages in the event of re-establishment of the grid after blackout.

Nominalvoltage

Un

Typicaloperatingvoltage

UTYP

Lowervoltage

UL

Lowerfull-loadvoltage

ULF

Upperfull-loadvoltage

UHF

Uppervoltage

UH

[kV] [kV] [kV] [p.u. of Utyp] [p.u. of Utyp] [kV]

30 30.0 27.0 0.95 1.05 36.0

20 20.5 18.0 0.95 1.05 22.015 15.3 13.5 0.95 1.05 16.5

10 10.5 9.00 0.95 1.05 11.0

0.69 0.69 0.62 0.90 1.05 0.76

0.40 0.40 0.36 0.90 1.05 0.44

Table 3 Full-load voltage range in relation to upper and lower voltage limit.

Table 3 states the typical operating voltage (UTYP). Typical operating voltage varies from onepart of the country to another and is determined by the electric power utility.

The interval between the upper and lower limits of the full-load voltage range measured inkV (UHF-ULF) must be within the upper and lower voltage limit (UH-UL), respectively.

5.2 Voltage deviations

5.2.1 Low voltages ULAt frequencies in the connecting points within the full-load frequency range, a power stationunitmust be able to supply reduced maximum powerwhen the voltage in a connecting pointis between ULF and UL.

Apower station unitmust be able to supply reduced maximum powerfor at least one hour at

a time. If low voltage occurs in a connecting pointfor longer periods of time, thepowerstation unitmust be able to continuously supply reduced maximum power. Whether or not


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low voltage may occur for longer periods of time must be indicated by the electric powerutility to which thepower station unitis connected.

The reduction in maximum powermust not constitute more than 10% of the nominalmaximum power.

5.2.2 Extra low voltages UELApower station unithaving a connecting pointwith a nominal voltage Un lying within the 10to 20 kV range must supply electricity within the full-load frequency range and within therange between UL and the extra low voltage UEL as stated in Table 4 while reducingmaximum poweras little as possible.

Nominalvoltage

Un

Extra low

voltage

UEL

Extra high

voltage

UEH

[kV] [kV] [kV]

20 17.0 24.0

15 12.0 17.5

10 8.50 12.0

Table 4 Extra low and extra high voltage limits.

5.2.3 High voltages UHIf frequencies in the connecting points lie within the full-load frequency range, apowerstation unitmust be able to supply reduced maximum powerwhen the voltage in aconnecting pointis between UHF and UH.

Apower station unitmust be able to deliver reduced maximum powerfor at least one hourat the time, and for connecting points with a nominal voltage Un more than 100 kV for up to10 hours a year.

The reduction in maximum powermust not constitute more than 10% of the nominalmaximum power.

5.2.4 Extra high voltages UEHApower station unithaving a connecting pointwith a nominal voltage Un lying within the 10to 20 kV range must supply electricity within the full-load frequency range and within the

range between UH and the extra high voltage UEH as stated in Table 4 while reducingmaximum poweras little as possible.

5.2.5 Voltage ramp rateThe voltage deviations mentioned in section 5.2 must be tolerated for connecting points witha nominal voltage Un of more than 100 kV when the voltage varies up to 10% ofnominalvoltage Un for any one-minute interval. Voltage variations for other connecting points mustbe tolerated at any voltage ramp rate.

5.2.6 Transient voltagesConditions in thepublic electricity supply gridmay cause transient voltages in the connectingpointfor thepower station unit.

Any need for installing surge arresters in order to protect thepower station unitmust beassessed in collaboration with the electric power utility.


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5.3 Frequency deviations

5.3.1 Low frequenciesWhen the frequency is low (below 49.0 Hz) and if voltages in the connecting points lie within

the full-load voltage range, apower station unitmust be able to supply reduced maximumpowerat frequencies in the connecting points as shown in Table 5.

The reduction in maximum powermust make up 15% at the most ofnominal maximumpowerat 47.5 Hz, 0% ofnominal maximum powerat 49 Hz, and a value found by linearinterpolation at frequencies between 47.5 Hz and 49 Hz.

There are no requirements as to the maximum powerwhich apower station unitmust supplyat extra low frequencies (below 47.5 Hz).

Frequency range

f[Hz]

Operating time

t[sec. / min.]

Maximum

power reduction[%]

f < 47.0 Hz47.0 f 47.547.5 < f 49.0

49.0 < f 50.5

50.5 < f 51.0

51.0 < f 53.0f > 53.0 Hz

300 ms> 10.0 sec.> 30 min

Continuous

> 30 min

Short (3 min) 300 ms

No requirementsNo requirements

< 15%

0%

0 %

No requirementsNo requirements

Table 5 Frequency range, operating time and generation requirements.

5.3.2 High frequenciesWhen the frequency is high (above 50.5 Hz and below 51.0 Hz, and if voltages in theconnecting points lie within the full-load voltage range, apower station unitmust be able tosupply reduced maximum powerwithout any reduction,as shown in Table 5.

5.3.3 Extra high frequenciesWhen the frequency is extra high (above 51.0 Hz), and if voltages in the connecting pointslie within the full-load voltage range, apower station unitmust remain connected when

frequencies in the connecting points are as shown in Table 5.

There are no requirements as to the maximum powerwhich apower station unitmust supplyat extra high frequencies.

5.3.4 Transient frequenciesThe general purpose of the following requirements is to ensure that thepower station unitisdesigned in such a way that it can continue to operate at transient frequency deviations.These deviations normally occur in connection with grid faults.

A power station unitmust be able to withstand transient frequency gradients (df/dt) of up to

2.5 Hz/s in the connecting pointwithout disconnecting.


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Tolerance towards grid faults

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6. Tolerance towards grid faults

Apower station unit, including auxiliary supply system and auxiliary facilities, must stayconnected to the grid during and after a voltage disturbance in the connecting points asstated in the sections 6.1-6.2 with a subsequent load reduction of maximum 10% in theeffective power.

Whether or not apower station unitmust be designed to withstand these voltage sags withthe stated reduction in effective power, the relay settings must be as stated in section 12.

The power station unitis considered to be connected above 100 kV when there is onlyelectricity consumption in the form of house load for production and grid installationsbetween thepower station unitand the transmission grid above 100 kV.

6.1 Connecting points above 100 kV

Apower station unitmust be able to withstand a voltage disturbance nearby on the high-voltage side of the generator transformer and in the connecting pointas stated in Figure 2and Figure 3.

6.1.1 Faults near a power station - short-line faultsA voltage disturbance near a power station means a voltage disturbance occurring in such adistance from apower station unitthat, in the event of a three-phase short-circuit, the shareof AC in the initial short-circuit current (IK) from thepower station units generator(s) isminimum 1.8 times the nominal current of the generator(s).

In the event of three-phase voltage disturbances, thepower station unitmust be capable ofwithstanding a voltage curve in the three phases as stated in Figure 2.

Figure 2 Three-phase voltage disturbance which must not lead to the disconnection of the power station unit. ULFdesignates the lower limit of the full-load voltage range according to Table 2.

In Eastern Denmark, y is required to be 250 ms (in accordance with Nordel), and in WesternDenmark, y is required to be 150 ms (in accordance with the UCTE).

Time

ULF

1 0 0 %

1 5 0 ms

6 0 %

0 %

0 7 0 0 ms 1 5 0 0 ms

Full-loadvoltage range

y ms

Percentage

of nominalvoltage


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Document no. 43436-08_v5.1 20/85

In the event of one-phase or two-phase voltage disturbances, thepower station unitmust becapable of withstanding a voltage curve in the faulty phases as stated in Figure 3 at thesame time as the voltage in the non-faulty phases is between the lower limit for the full-loadvoltage range (ULF) and 1.4 times the upper limit for the full-load voltage range (1.4 x UHF)according to Table 2 and Table 3. The time interval, x, in Figure 3 may vary between 300

ms and 800 ms.

Figure 3 Phase voltage during faulty phases in the event of one-phase or two-phase voltage disturbances whichmust not lead to the disconnection of the power station unit. ULFdesignates the lower limit of the full-load

voltage range according to Table 2.

6.1.2 Faults occurring far away from a power stationA voltage disturbance occurring far away from a power station means a voltage disturbanceoccurring in such a distance from thepower station unitthat, in the event of a three-phaseshort-circuit, the share of AC in the initial short-circuit current (IK) from thepower stationunits generator(s) is less than 1.8 times the nominal current of the generator(s).

Apower station unitmust be capable of tolerating any one-, two- or three-phase voltagedisturbance far away from the power station of up to five seconds in connecting points withnominal voltage above 100 kV.

6.2 Connection points up to 100 kV

Apower station unitmust be designed in such a way that the connecting points with nominalvoltage up to 100 kV are able to withstand voltage sags up to 50% of the nominal voltage inone second in all three phases and voltage sags to 0% voltage during one second in onephase.

Apower station unitmust be designed in such a way that the connecting points with nominalvoltage up to 100 kV are able to withstand voltage sags up to U3 in between one and fiveseconds in all three phases and a voltage sag up to U1 in between one and five seconds inone phase. The size of U3 and U1 in p.u. is given at U3 = 1 (0.5 seconds)/t and U1 = 1 -(1 second)/t where t is the duration of the voltage sag (nominal voltage equal to 1 p.u.) as

illustrated in Figure 4.

ULF

1 0 0 %

15 0 ms

6 0 %

0 %

1 5 0 ms 5 5 0 ms 8 0 0 msx

Full-loadvoltage range

Percentage

of nominalvoltage

Time


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Document no. 43436-08_v5.1 21/85

Figure 4 Relationship between duration and range of one-phase and three-phase voltage sags which power stationunits connected to up to 100 kV must be able to withstand.

Duration, t(s e co nds)

Voltage, U

ULF

1

1 0 0 %

5 0 %

7 5 %

2 5 %

0 %

2 3 540

1 -phasevoltage drop

3 -phasevoltage drop


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Island operation

Document no. 43436-08_v5.1 22/85

7. Island operation

7.1 Power station units up to 25 MW

7.1.1 House-load operationForpower station units with nominal maximum powerup to 25 MW it is acceptable that theyare disconnected at impacts not covered by the specified requirements without switchingfrom normal operation to house-load operation.

The significance of a system's possible ability to switch from normal operation to house-loadoperation is assessed as being modest in relation to the price of ensuring such an operationalproperty. Efforts should rather be made to ensure short starting times after a disconnectionof thepower station unit.

7.1.2 Isolated island operationA grid fault may cause unintentional isolated island operation. Continued operation of the

power station unitduring unintentional isolated island operation should be avoided to thewidest possible extent.

According to section 9, apower station unitmust, however, be able to supply a suitable areaduring isolated island operation in accordance with a special operational supervisoragreement.

7.2 Power station units above 25 MW

Apower station unitwith nominal maximum powerabove 25 MW must be capable ofswitching from normal operation in parallel with the interconnected power supply system toisland operation, maintain island operation and return from island operation as stated insections 7.2.1-7.2.3.

7.2.1 Transition to island operationThe transition to house-load operation must be possible from any condition with effectivepowerfrom minimum powerto maximum powerand in case of overload.

Transition to island operation must be effected automatically in the following situations:

- If the frequency and voltage ranges specified in section 5 in the form of high/lowvoltages/frequencies or the times stated in the section are exceeded.

- In case of grid faults exceeding the profiles for voltage sags specified in section 6.

At the transition to isolated island operation, a power station unitmust be capable ofcontrolling the system frequency within the full-load frequency range unless this will lead tothe effective powerbecoming lower than the minimum poweror exceeding the maximumpower. According to section 9, this will be effected, in case of transition to isolated islandoperation, by thepower station unitundertaking control as after a fault and immediatelythereafter undertaking control as during normal operation.


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Island operation

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7.2.2 Maintaining island operationIt must be possible to maintain stable and reliable house-load operation for at least twohours without stopping thepower station unit.

It must be possible to maintain continuous, stable and reliable isolated island operation

without stopping thepower station unitas long as it is not contrary to thepower stationunits possible maximum poweraccording to section 4 or tolerance towards voltage andfrequency deviations according to section 5.

For apower station unitwith heat-load determined electricity production, the time in whichisland operation can be maintained can be limited by a small extraction of district heat.

7.2.3 Return from island operationApower station unitmust be capable of returning directly to normal operation after islandoperation without stopping thepower station unitaccording to section 8.3.

Apower station unitmust be capable of going into isolated island operation, includingenergising, without stopping thepower station unitaccording to section 8.3.


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Start and synchronisation

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8. Start and synchronisation

8.1 Start

Apower station unitmust be able to start at frequencies and voltages in the connectingpoints lying within the full-load voltage-frequency range. In addition, apower station unitmust in pursuance of section 5.1. also be able to start at voltages down to the lower voltagelevel UL.

There are no requirements as to the start of apower station unitof 1.5 MW electric power ormore with a no-voltagepublic electricity supply grid. It is possible, however, to agree onadditional energising properties with the TSO so that it becomes possible to start from a no-voltage grid.

8.2 Starting time

Apower station unitmust be designed with a starting time that is as short as possible givingdue consideration to the financial consequences, for example with a view to providing fastreserves and emergency start.

8.2.1 Steam turbine above 25 MWThe starting time until synchronisation and the starting time until full generation must notexceed the times indicated in Table 6 for apower station unitwith a steam turbine withrated maximum powerabove 25 MW.

The times for the steam turbine part apply to a combined-cycle unit with rated maximumpowerabove 25 MW.

Starting time for

synchronisation

Starting time until

full generationTime since last stop

[min.] [min.]

Immediately after stop 120 210

Up to 8 hours 180 300

Between 8 and 36 hours 300 480

Over 36 hours (cold start) 600 840

Table 6 Maximum starting time for power station units with nominal maximum power above 25 MWdepending on the time elapsed since the last stop.

8.2.2 Gas turbine above 25 MWAs for apower station unitwith a gas turbine that does not produce heat and the nominalmaximum powerof which is above 25 MW, the starting time until full generation must notexceed 3 minutes for gas turbines of the jet type and 10 minutes for gas turbines of theindustrial type, irrespective of the time elapsed since last disconnection.

As for apower station unitwith a gas turbine that produces heat, including apower stationunitwith combined-cycle gas turbine (combi plant), and the nominal maximum powerofwhich is above 25 MW, the starting time until synchronisation and the starting time until fullgeneration for the gas turbine part must not exceed 20 minutes and 45 minutes respectively,irrespective of the time elapsed since latest disconnection.


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Start and synchronisation

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8.2.3 Plant types up to 25 MWThe starting time until synchronisation and the starting time until full generation must notexceed the times stated in Table 7 forpower station units not comprised by sections 8.2.1-8.2.2 - includingpower station units with nominal maximum powerup to 25 MW.

The starting time will be stated by the TSO for plant types and main fuels not stated inTable 7, includingpower station units with several different main fuels.

Starting time

Immediately after

disconnection

Eight hours since

disconnection

Until

synchroni-

sation

Until full

generation

Until

synchroni-

sation

Until full

generation

Type/main fuel

of power station unit

[min.] [min.] [min.] [min.]

Straw-fired steam power plant 75 90 60 120Wood chip-fired steam power plant 30 45 60 90

Fluid-bed coal-fired steam powerplant 45 60 90 120

Waste-fired steam power plant No req. No req. No req. No req.

Gas engine 10 20 10 20

Gas turbine 20 30 20 30

Gas-fired combined cycle

(combi plant) 30

40

(steam part95 min.)

25

35

(steam part90 min.)

Diesel engine 5 15 5 15

Table 7 Maximum starting time for power station units not comprised by 8.2.1-8.2.2 including power station unitswith rated maximum power up to 25 MW depending on the time elapsed since latest disconnection.

8.3 Synchronisation

Apower station unitmust be provided with synchronisation equipment for connection.

The synchronisation equipment must safely and reliably synchronise thepower station unitto the grid both in case of normal start and in situations with island operation inaccordance with section 7, in situations when voltage and frequency in the connection pointslie within the full-load voltage-frequency area according to section 5.1, and in situationswhen voltages go down to the lower voltage limit.

Apower station unitthat can go into island operation according to section 7 must be capableof energising a dead grid safely and reliably from situations with house-load operationaccording to section 7.2.3 as long as it does not exceed the frequency and voltage limitsspecified in sections 5 and 6.

In connecting points with a nominal voltage of 20 kV or less, apower station unitmust notbe the cause of inrush currents, etc. of such a magnitude that it causes disruptive temporaryvoltage variations in accordance with the DEFU committee report 88, Nettilslutning afdecentrale produktionsanlg (Grid Connection of Local Power Plants), March 1991.

Transient voltage deviations from inrush currents etc., including from the excitation currentat the synchronisation of a generator transformer, must not exceed 3% ofnominal voltage inconnecting points with a nominal voltage above 20 kV.


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Active power production and frequency control

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9. Active power production and frequency control

Apower station unitmust be designed in such a way that it can be operated in an operatingcondition that enables, at a minimum, the supply of the reserves required by Nordel and theUCTE, respectively, in accordance with the following requirements.

9.1 General requirements of the regulating capability of the power station

unit

Thepower station unitmust be equipped with a fast reactingpower/frequency controllercapable of continuously, reliable and safely controlling the effective powerand supplyingfrequency control.

It must be possible to operate thepower station unitin an operating condition allowing foran instantaneous increase in effective powerwhen thepower station unitis supplyingeffective powerof 50-90% ofmaximum powerin accordance with the following

requirements.

An increase/reduction in the effective powermust be at least 5% of the nominal maximumpowerin 30 seconds at the limit frequency specified by the TSO.

Thepower/frequency controllermust be capable of continuously controlling the effectivepowerbetween minimum powerand maximum powerwith the natural constraints which maybe imposed by the process at thepower station unit(eg start of coal mills and Bensontransition).

The accuracy of thepower/frequency controllers frequency metering must be 10 mHz or lessforpower station units above 25 MW whereas a resolution of 20 mHz or less is acceptable for

otherpower station units.

It must be possible to set thepower/frequency controllers reference frequency in the 49.9Hz to 50.1 Hz range with a resolution of 10 mHz or less.

Thepower/frequency controllers droop must be set within the range of 2%-8% with aresolution of 1% or less.

Thepower/ frequency controllersdroop part must be equipped with an adjustable dead bandthat can be by-passed. It must be possible to set the dead band within the 0 mHz to 200mHz range with a resolution of 5 mHz or less.

Forpower station units above 25 MW it must be possible to set thepower/frequencycontrollerindividually with limit frequencies for the activation of maximum load variations forboth over- and underfrequencies.

Forpower station units above 25 MW thepower/frequency controllermust as a minimum

have two parallel sets of dead band and droop.

Thepower/frequency controller's time constant must not limit the total control system'sclosed loop time constant (regulator + drive engine + generator).

Forpower station units above 25 MW the setting of reference frequency, dead band and

droop must be remote-controllable during operation via an external signal within the givenlimits.


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9.2 Power control in case of major frequency deviations

9.2.1 Western Denmark Critical power/frequency controlThepower station unitmust be capable of providing critical power frequency support in the

event of major frequency deviations.

In the event of momentary frequency drop/increase, thepower station unitmust be capableof providing frequency support according to the set point of the droop. The power responsemust correspond to what is achievable in the current operating situation.

Apower station unitmust be capable of supplying secondary regulation immediately after amomentary increase in the effective poweraccording to section 9.4.

Critical power frequency control for the individualpower station unitmust only be activatedupon the request of the TSO.

Power station units connected to the grid above 100 kV must always be able to providecritical power frequency control.

9.2.2 Eastern Denmark Frequency-controlled disturbance reserveThe increase in the effective powermust start in the event of a frequency drop bringing thefrequency under a limit value specified by the TSO. The limit value will typically be 49.9 Hz(fact=100 mHz). The limit value for the frequency at which the increase in effective powermust be fully stepped up is specified by the TSO. The limit value will typically be 49.5 Hz(ftrg=500 mHz).

The increase in effective powermust be minimum 2.5% ofnominal maximum powerin 5

seconds in the event of a specified frequency drop relative to the reference frequency(Nordel recommendation).

In the event of a frequency drop lower than the limit frequency (ftrg) specified by the TSO,thepower station unitmust be capable of providing an increase in effective powerasindicated above, in such a way, however, that the increase in the effective poweris scaledwith a factor K:

K=(f-fact)/( ftrg-fact)

where:

f : Frequency drop magnitude in Hz

ftrg : The frequency drop in Hz that triggers the increase in

effective powerstated (0.2-0.5 Hz)fact : The frequency deviation for activation in Hz specified by

the TSO

Apart from the above-mentioned requirements relating to frequency-controlled disturbancereserves, thepower station unitmust be capable of providing frequency support according tothe set point of the droop in the event of momentary frequency increase. The powerresponse must correspond to what is achievable in the current operating situation.

Frequency-controlled disturbance reserves for the individualpower station unitmust only beactivated upon the request of the TSO.


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Document no. 43436-08_v5.1 28/85

Apower station unitmust be capable of providing secondary regulation immediately after amomentary increase/reduction in the effective poweraccording to section 9.4.

9.3 Power control in case of minor frequency deviations

Apower station unitwith nominal maximum powerabove 25 MW must be designed so that itcan be operated according to the following requirements.

9.3.1 Western Denmark Primary controlThe increase/reduction in the effective powermust start at frequency deviations specified bythe TSO, and it will typically be in the 100 mHz range relative to the reference frequency.The limit frequency at which the increase/reduction in the effective powermust be fullyregulated is specified by the TSO and will typically be in the 200 mHz range relative to thereference frequency.

In the event of frequency deviations requiring a power response of less than 50% of the totalreserve capacity, the power response must be supplied within 15 seconds at the most. In theevent of frequency deviations requiring a power response in the 50-100% range of the totalreserve capacity, the part of the power response that is beyond 50% must be suppliedlinearly controlled from 50% at 15 seconds to 100% at 30 seconds.

The power response of thepower station unitin connection with the requirements in sections9.2.1 and 9.3.1 must be the highest possible of the requirements mentioned.

9.3.2 Eastern Denmark Frequency-controlled normal operation reserveWith a dead band set at 0 mHz, thepower station unitmust be capable of supplying thereserve capacity agreed with the TSO within 150 seconds in the event of a momentaryfrequency drop/increase.

9.4 Load control and secondary control

Apower station unitmust constantly and safely be able to control the effective powerwithinthe range ofminimum powerto the highest maximum power. This must be possible both onthe basis of a plannedpower schedule (load control) and on the basis of centrally orderedcontrol (secondary control).

It must be possible to control the secondary controlfrom an external signal.

It must be possible to control the effective powerby selecting a required effective powerinMW (set point) and a required regulation rate (ramp rate) in MW/min. After that thepowerstation unitmust be capable of controlling production to the selected effective power.

Table 8 shows the rate at which it must be possible to change the effective powerat aminimum expressed in per cent ofnominal maximum powerper time unit. It is acceptablethat the effective powerwill be delayed by the natural time constant connected to thetransformation of the fuel for power generation. The rate depends on the current effectivepower(power range) expressed in per cent ofnominal maximum poweras shown in thetable.


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Document no. 43436-08_v5.1 29/85

Ramp rate Power rangeType of power station unit

[%/minute] [%]

2 35-504 50-90Coal dust-fired steam power plant

2 90-100

2 20-50

8 50-90Oil-fired steam power plant

2 90-100

2 20-50

8 50-90Gas-fired steam power plant

2 90-100

2 35-50

4 50-90Bio dust-fired steam power plant

2 90-1004 50-90

Straw-fired steam power plant2 90-100

4 50-90Wood chip-fired steam power plant

2 90-100

4 50-90Fluid-bed coal-fired steam power plant

2 90-100

Waste-fired steam power plant No reguirement No reguirement

Gas engine 10 35-100

Gas turbine 10 20-100

Gas-fired combined cycle (combi plant) 10

20-100% for

gas turbine part75-100% forsteam turbine

part

Diesel engine 20 20-100

Table 8 Minimum requirement in relation to ramp rate for effective power.

In addition to the ramp rates given in Table 8 the following applies: for any overloadcapacitythe unit must be capable of regulating with minimum 1%/min. in the overload area.


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System stability

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10. System stability

Apower plant unitmust be equipped with one or more synchronous generators deliveringthe generated electricity to thepublic electricity supply gridpossibly via one or more gridtransformers (step-up transformer/engine transformer).

10.1 Generator

The generator(s) of apower station unitmust comply with the relevant parts of thespecifications of the European standards EN60034-1, Rotating electrical machines Part 1:Rating and performance, 2004, and EN60034-3, Rotating electrical machines Part 3:Specific requirements for turbine-type synchronous machines, 1995, but in pursuance of thefollowing requirements.

The reactances of apower station unit's generator(s) must be as low as possible, taking thetechnical and financial consequences hereof into account, with the aim of enhancing the

stability of thepublic electricity supply gridand reactive power control.

For apower station unitconnected to apoint of common coupling with nominal voltage up to100 kV, thepower station units generator(s) must have a short-circuit ratio of minimum0.45.

For apower station unitconnected to apoint of common coupling with nominal voltage up to100 kV, thepower station units generator(s) must have a transient reactance of less than0.35 p.u.

For apower station unitconnected to apoint of common coupling with nominal voltageabove 100 kV, minimum requirements are set in relation to short-circuit ratio and transient

reactance by the TSO on the basis of stability analyses according to section 12.

10.2 Step-up transformer

The connection between apower station units generator and thepoint of common coupling,including step-up transformer and generator feeder, must have a reactance that is as low aspossible taking into account the technical and financial consequences involved, with a view toenhancing the stability of thepublic electricity supply gridand voltage control.

For apower station unitconnected to apoint of common coupling with nominal voltage up to100 kV, thepower station units step-up transformer(s) must have a short-circuit impedance

as defined in EN60076-1 of less than ez:

ez= 0.07Sn0.15 p.u.

where

Sn : Rated power for the transformer as defined in EN60076-1,measured in MVA.

For apower station unitconnected to apoint of common coupling with nominal voltageabove 100 kV, the TSO sets the maximum allowable magnitude of the set-up transformer'sshort-circuit reactance as defined in EN60076-1.


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Reactive power generation and voltage control

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11. Reactive power generation and voltage control

11.1 Power factor

In thepoint of common coupling, apower station unitconnected to apoint of commoncoupling with nominal voltage up to 100 kVmust be able to use/produce reactive power withtan within the -0.20 to 0.40 range at nominal maximum powerand at voltages in thepointof common coupling within the full-load voltage range.

In thepoint of common coupling, apower station unitconnected to apoint of commoncoupling with nominal voltage up to 100 kVmust be able to use/produce reactive power asindicated by the hatched area in Figure 5 at nominal maximum powerand at voltages in thepoint of common coupling within the full-load voltage range.

At voltages in thepoint of common coupling lying outside the full-load voltage range, thepotential reactive power production of apower station unitconnected to apoint of commoncoupling with a nominal voltage above 100 kV must only be reduced to an extent determined

by the fact that the generators and the step-up transformers thermal limits are notexceeded and that the generator remains at a stable operating point.

Figure 5 Tanas a function of the voltage in the point of common coupling for a power station unit connected to a

point of common coupling with a nominal voltage above 100 kV.

ta n

Voltage

UHF

0-0 .2 0 .4

ULF

UN


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11.2 Excitation system in general

Apower station unitmust be equipped with a continuously operating automatic excitationsystem that ensures a constant voltage in thepoint of common coupling and increases thestability of thepublic electricity supply grid.

It must be possible, by an external signal, to select the reference voltage (set point) of thevoltage control within the full-load voltage range according to section 5.

For apower station unitconnected to apoint of common coupling with nominal voltage up to100 kV, the voltage may be controlled on the basis of the voltage on the generator clamps.

For apower station unitconnected to apoint of common coupling with nominal voltageabove 100 kV, voltage control must take place on the basis of the voltage on the generatorclamps in thepoint of common coupling or somewhere in between (voltage measurementwith compounding).

The excitation system must be designed in accordance with the European standardEN60034-16-1 "Rotating electrical machines Part 16: Excitation systems for synchronousmachines Chapter 1: Definitions", 1995, and IEC technical report IEC60034-16-3 "Rotatingelectrical machines Part 16: Excitation systems for synchronous machines Section 3:Dynamic performance", 1996, but in accordance with sections 11.3 and 11.4.

11.3 Excitation system during normal operation (small-signal performance)

The excitation systems time response in the event of momentary 10% voltage variationmust be non-oscillating, have a rise time as defined in EN60034-16-1 of no more than 0.3seconds for a static excitation system, no more than 0.5 seconds for a rotating exciter if thevoltage variation is positive, and no more than 0.8 seconds for a rotating exciter if the

voltage variation is negative.

Overshoot as defined in EN60034-16-1 must not exceed 15% in the event of a momentary10% voltage variation.

The excitation systems open-loop frequency response must not have an amplification ofmore than 20 dB in the frequency range 0.2-1.5 Hz.

11.4 Excitation system during grid faults (large-signal performance)

The excitation systems ceiling voltage as defined in EN60034-16-1 must be at least 160% ofnominal excitation voltage.

The excitation systems voltage response time as defined in IEEE Std. 421.2-1990 and mustnot exceed 0.1 second.

The excitation systems over-excitation protection and other types of protection must bedesigned and set so that the generators capacity for temporary overload can be utilisedwithout superseding the generators thermal limits.


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11.5 Equipment for power system stabilisers

Apower station unitwith nominal maximum powerabove 25 MW must be provided withequipment for dampinging power swings (power system stabiliser, PSS).

It must be possible to connect and disconnect the damping equipment.

The damping equipment must have adjustable limits for the output signal.

The damping equipment must also meet specifications as regards control facilities and actualsettings laid down by the TSO in collaboration with thepower station operator.

11.6 Automatic voltage control, etc.

The excitation system of apower station unitconnected to apoint of common coupling witha nominal voltage above 100 kV must be operated with automatic voltage control accordingto section 11.2 unless otherwise prescribed by the TSO.

Apart from automatic voltage control, the excitation system of apower station unitconnected to apoint of common coupling with a nominal voltage up to 100 kV must have theoption of operating with automatic regulation oftanin accordance with the followingrequirements. The form of operation must be specified by the electric power utility to whosegrid thepower station unitis connected.

Automatic control oftan must be carried out with a resolution of 0.1 or less.

It must be possible to set the time control by external signals and with a time resolution ofat least 15 minutes over one week (weekly clock with a 15-minute resolution).

Irrespective of the control options, it must be possible to automatically and fully

- control tan down to a minimum in accordance with section 11.1 if the voltage is higher

than an adjustable value; and- control tanup to a maximum in accordance with section 11.1 if the voltage is lower than

an adjustable value.

The selection of operational mode between automatic voltage control and automatic tanaswell as time control must be possible by remote control via external signals within the setlimits.


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Protection

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12. Protection

12.1 General

Thepower station operatoris responsible for ensuring that apower station unitisdimensioned and protected so that:

- Thepower station unitis protected against damage resulting from faults and incidents inthe grid.

- Thepublic electricity supply gridis secured to the greatest possible extent againstundesirable impacts from thepower station unit.

- The power station unitis secured against disconnection in non-critical situations.

The TSO and the electric power utility to whose grid apower station unitis connected maydemand that the setting of thepower station unit's relay protection, which is important tothe operation of thepublic electricity supply grid, be changed after commissioning. Suchchange must not expose thepower station unitto impacts from thepublic electricity supply

gridthat lie outside the design criteria stated in this regulation.

It is the responsibility of the electric power utility to whose grid thepower station unitisconnected to indicate the highest and lowest short-circuit current that can be expected in theconnecting points and provide other information about thepublic electricity supply gridwhichis necessary to determine the protection of thepower station unit.

12.2 Protection against external faults

For apower station unitconnected to apoint of common coupling with a nominal voltage of10-20 kV, the scope and setting of the relay protection must be established as outlined inDEFU technical report TF 293, 2nd edition, "Relbeskyttelse ved decentrale

produktionsanlg med synkrongenerator" (Relay protection at local production plants withsynchronous generators), June 1995, see however:

- The setting of the positive-sequence undervoltage relay is calculated by the electric powerutility to whose grid thepower station unitis connected (using the principles in the DEFUtechnical report TF 293, second edition) on the basis of generator data supplied by thepower station operator.

- Relay protection aimed at internal faults in thepower station unitin excess of what ismentioned in the DEFU technical report 293, 2nd edition, may be established provided itdoes not disconnect thepower station unitin case of faults or incidents in the grid anddoes not prevent thepower station unitfrom complying with the other provisions of this

regulation.- Relay protection in excess to what is stated in DEFU technical report 293, 2nd edition, andwhich may disconnect apower station unitat faults or incidents in the grid must only beestablished where special local conditions apply and following approval by the TSO andthe electric power utility to whose grid thepower station unitis connected. This relayprotection must not prevent thepower station unitfrom complying with the otherprovisions of this regulation.

- The vector jump protection and the phase shift protection, which are mentioned in theDEFU technical report 293, 2nd edition, can no longer be used as they result in additionalfalse trippings of thepower station units.

- Appendix 2 describes the required relay protection for synchronous generators, whileAppendix 3 outlines the supplementary relay protection.

For apower station unitconnected to apoint of common coupling with a nominal voltageabove 20 kV and under 100 kV, includingpower station units connected to apoint of


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Protection

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common coupling with a nominal voltage of 30-60 kV, the electric power utility to whose gridthepower station unitis connected indicates whether the provisions in DEFU TR 293, 2ndedition, are applicable or the provisions forpower station units connected to apoint ofcommon coupling with nominal voltage above 100 kV must be followed.

Forpower station units connected to apoint of common coupling with a nominal voltageabove 100 kV, thepower station operatoris responsible for the implementation of stabilityand selectivity investigations in collaboration with the TSO and the electric power utility towhose grid thepower station unitis connected with a view to determining the protection ofthepower station unit. The purpose of the investigation is to ensure that thepower stationunitcomplies with section 12.1 and that the protection does not prevent thepower stationunitfrom complying with the other provisions in this regulation. The selected relay settingswhich are of relevance to the operation of thepublic electricity supply gridmust be approvedby the TSO and the electric power utility to whose grid thepower station unitis connected.

12.3 Protection against internal faults

In case of internal short-circuiting in the generator plant, relay protection must be selectivewith the grid protection, ie short-circuiting in the generator must be disconnected within 100ms.

In addition to the relay protections mentioned in Appendices 2 and 3, relay protection canbe established targeting faults in the production plant, including short-circuits, overspeed,excitation monitoring, reverse power, etc. Such relays must not disconnect the unit in theevent of short-circuits or under normal grid operations.

Relay protection which is not mentioned in Appendices 2 or 3 and which is able todisconnect in case of short-circuiting or under normal grid operations must only be used if

the local grid has a special structure rendering it necessary. Such relay protection must onlybe established with the permission of the electric power utility, and the relay settings mustbe approved by the electric power utility.


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Metering, communication and data exchange

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13. Metering, communication and data exchange

With a view to ensuring the operation of thepublic electricity supply grid, telecommunicationmust be set up between the operator responsible for the operation of apower station unitand the TSO in accordance with the regulations issued by the TSO.

Correct metering, communication and data exchange must be maintained under allcircumstances, including situations with shutdown and outage of thepower station unitandsituations with a dead grid.

13.1 Metering

Apower station unitmust be connected to metering equipment in accordance with theregulations issued by the TSO.

There are two metering regulations that must be observed:

- metering regulation for settlement purposes, which describes the requirements for electricenergy metering on the basis of quarter-hourly registration; and

- metering regulation for the purposes of system operation, which describes therequirements for electric energy metering on the basis of online metering.

13.2 Communication

It must be possible to connect and disconnect apower station unitexternally, and as aminimum the unit must be able to exchange status and operating states.

In addition, it must be possible to exchange specific requirements as to external signals fromother sections of this regulation with thepower station unit.

13.3 Data exchange

The final data exchange must take place pursuant to IEC 61850-7-420 and must be specifiedin collaboration with the electric power utility.

If the implementation of the protocol is impossible at the time of commissioning, the protocolmust be registered at a later date. In the intervening period, the protocol must be agreedupon in cooperation with the electric power utility.


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Power station unit structure

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14. Power station unit structure

14.1 Structure

Apower station unitmust be designed in such a way that it can operate electrically,mechanically and in all other aspects as a stand-alone unit independently of otherpowerstation units.

14.2 Earthing

At power station units where the generator is connected without step-up transformer, thegenerator star point must be earthed in accordance with the specifications issued by theelectric power utility to whose grid thepower station unitis connected.

At power station units where the generator is connected via a step-up transformer, the starpoint of the step-up transformer must be earthed in accordance with the specificationsissued by the electric power utility to whose grid thepower station unitis connected.

14.3 Electrical equipment

Substation equipment, etc., which is installed by thepower station operatorin a connectingpointand which is comprised by the grid relay protection must comply with the specificationsissued by the electric power utility.

14.4 Disconnection when work is performed on generator plant

The provisions of Sections 551 and 636 of Title 6 of the Danish Heavy Current Regulationapply topower station units connected to the low voltage grid.

The provisions of Section 6.4.3 of Title 5 of the Danish Heavy Current Regulation apply topower station units connected to the high voltage grid


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Operation and maintenance

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15. Operation and maintenance

During the operation of apower station unit, thepower station operatormust comply withthe provisions of relevant operation regulations issued by the TSO and agreements betweenthepower station operatorand the TSO. Where no operating regulations exist, thepowerstation unitmust be operated so that the properties indicated in this regulation, includingproperties relating to starting times and ramp rates, are observed during operation.

The maintenance of apower station unitmust be carried out continuously so that thepowerstation unitalways complies with this regulation and does not constitute a risk to otherinstallations in thepublic electricity supply grid.


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Verification and documentation

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16. Verification and documentation

16.1 General

All documentation must be supplied to the electric power utility in electronic form.

The electric power utility reviews the documents and provisionally approves thedocumentation described in section 16.2 hereof prior to commissioning. The same is donewith the commissioning report, which is described in section 16.3 hereof, aftercommissioning.

The electric power utility submits the overall documentation electronically to the TSO for finalapproval.

16.2 Prior to commissioning

The following documentation must be provided prior to the commissioning of a newpower

station unit:

- Name and address ofpower station unit- Name of power station owner- Time of commissioning- GSRN number- Name and location ofpoint of common coupling- Nominal voltage for thepoint of common coupling- Name of electric power utility- Description of type, fuel andpower station unitstructure- Single-line representation ofpower station unitwith connecting point(s) withindication of

point of common coupling, measuring points, eg settlement metering, limits of owner and

operational supervisor- Description of supply principle for control voltage- Nominal maximum power- Highest maximum powerand the equivalent external operating conditions- Lowest maximum powerand the equivalent external operating conditions- Maximum effective powerin other operating conditions than normal operating condition- Overload capacity- Maximum heat production- Heat accumulator size- PQ diagram of generator and inpoint of common coupling- Starting time until synchronisation and starting time until full production

- Possibility of dead start- Possibility of island operation- Power station unit's tolerance towards grid faults- Maximum ramp rate ofeffective power- Generator and transformer data- Excitation system data- Operating system data- Power/frequency controllerdata- Relay protection setting

The stated documentation must be supplied in a self-contained report in the formatdescribed in Appendix 1 of this regulation.


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16.3 During commissioning

During the commissioning of apower station unit, a commissioning test must be conductedby the power station owner to verify that thepower station unitcomplies with the provisionsof this regulation.

The commissioning test cannot be initiated before the electric power utility has provisionallyapproved the supplied documentation outlined in 16.2.

The commissioning test must provide documentation of the following properties in theconnecting point:

- Stable and continuous operation, see 4.1- Nominal maximum power, see 4.1- Overload capacity, see 4.2- Minimum power, see 4.3- Transition to and return from house-load operation, see 7.1-7.2- Starting time, see 8.2.- Power/frequency control, see 9.1- Power control at major frequency deviations, see 9.2.- Power control at minor frequency deviations, see 9.3- Load control and secondary control, see 9.4- Reactive power generation, see 11.1- Voltage control (step response), see 11.3- Power swing damping equipment (commissioning report for the equipment), see 11.5- Relay protection settings and function verification (secondary testing of operating time

and tripping value), see 12.1- Measurement of terminal voltage at maximum production and during no-load- External signals for communication and data exchange, see 13.2.

The commissioning test must be documented in a self-contained report with recorded dataenclosed to document the properties of thepower station unitin accordance with theregulations issued by the TSO.

Where thepower station unitis delivered on a turnkey basis and suchpower station unitcomplete with relay protection can be tested in the course of test procedures performed bythe manufacturer, the settings and verification of the relay protection can be implementedand documented by the manufacturer, section 16.3, as part of a final factory acceptancetest. When the factory tested turnkey unit is commissioned, the relay protection must, at aminimum, be inspected visually, and it must be documented that the settings are correct.

The commissioning report must be submitted to the electric power utility for preliminaryapproval. The electric power utility subsequently grants a temporary operating permit.

Upon final approval of the documentation by the TSO, the electric power utility grants a finaloperating permit.

If the electric power utility cannot approve the overall documentation, the plant owner canbe ordered to stop thepower station unit.


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16.4 During operation

Thepower station operatormust continuously supervise whether the provisions of thisregulation and the stated properties are complied with by thepower station unit,includingnominal maximum powerand overload capacity.

If the properties of thepower station unitare modified permanently thus affecting thecompliance with the provisions of this regulation, the electric power utility must be notifiedhereof immediately. In accordance with Appendix 1, updated documentation must beenclosed.

If the properties of thepower station unitwith nominal maximum powerabove 25 MW aremodified temporarily, for example due to part outage, thus affecting the compliance with theprovisions of this regulation, and if the information in section 16.2, including nominalmaximum powerand overload capacity, is changed temporarily, the TSO must be notifiedhereof immediately.

16.5 During overhaul

A test with documentation of the following properties must be conducted at intervals ofmaximum 30 months and after overhaul of apower station unit:

- Maximum power, see 4.1- Minimum power, see 4.3- Transition to and return from house-load operation, see 7.1-7.2- Power frequency control, see 9.1

The test must be conducted in accordance with the regulation on system operationconcerning operational planning issued by the TSO.

16.6 Modification of power station units

During the implementation of modifications to an existingpower station unit, the aspects ofa commissioning test that may be affected by the modifications must be implemented anddocumented again in accordance with section 16.3 hereof.

Prior to the commissioning test, updated documentation regarding the modifications to thepower station unitmust be prepared and supplied in accordance with section 16.2 hereof.

The commissioning test cannot be initiated before the electric power utility has provisionallyapproved the supplied documentation regarding the modifications, in accordance with 16.2hereof.

The commissioning report must be submitted to the electric power utility for preliminaryapproval. The electric power utility subsequently grants a temporary operating permit.

Upon final approval of the documentation by the TSO, the electric power utility grants a finaloperating permit.

If the electric power utility cannot approve the overall documentation, the plant owner canbe ordered to stop thepower station unit.


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16.7 Request for meter data and documentation

At any given time, the electric power utility and the TSO must be able to request informationabout apower station unitin addition to what is specified in sections 16.2 and 16.3 hereofthat may be relevant to system operation.

It must be possible for the TSO to request going three months back in time meter data andfault registrations collected for thepower station uniteven if the data is included in the

online metering already made available to the TSO.At any given time, the electric power utility an

grid code 3.2.3 power unit above 1,5 mw

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