FRT-Testing and Direct TSO-Control of Reactive Power Output

of Large Wind Farms

Peter Van Roy, H. Lemmens, T. Springuel, A. Dabin (Elia)Eckard Quitman (Enercon), Jaap-Jan Ferweda (WindVision)

2

Background

• European pilot project “7MW-WEC-by-11”• 11 onshore windturbines, 7MW-class• Estinnes, Belgium• Connected to Elia-grid at 70 kV, during 2009-2010• Partners: WindVision, Enercon, Sarens, Elia, Eneco, 3E, KUL,

TSO-Cyprus, EAC-Cyprus, WIP (coordination)• More details at: www.7MW-WEC-by-11.eu

• TSO-involvement• Elia: Belgian TSO, in charge of grids 30 – 380 kV Compliance testing: FRT, Q-range of full wind farm, Power Quality Direct control of wind farm by TSO, without 24/7 dispatch @ farm• Support to other partners

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Requirements from TSO on wind farms

• Fault-Ride-Through• Avoid loss of large amounts of power during grid fault

• Voltage control• Operated with reactive power setpoints

• Frequency control• By modifying active power from wind farm

Necessary for high penetration of wind power• Share of wind power in overall generation increases• Fewer “traditional” power plants to provide ancillary services

May offer extra stream of revenues• Depending on national tariff system

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Compliance testing (1) – Fault-Ride-Through

• Grid code requires FRT with 200 msec @ 0 V• Normally only type-testing on individual turbine

• Test in Aurich, Germany, witnessed by Elia

Grid structure at Estinnes allows test on full wind farm• No fault current contribution required, so short interruption is

similar to short-circuit regarding wind turbine operation• Isolate wind farm on 150/70 kV transformer• Open/close transformer within 5 seconds• Other nearby customers not impacted by test

• Successful test done with 5 turbines operational, end 2009• Graph showing applied voltage, and P and V on 1 wind turbine

Grid structure for test

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FRT: Grid voltage

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FRT: Turbine active power and voltage

P_WEC1 Q_WEC1 U1_Mean_WEC1U2_Mean_WEC1U3_Mean_WEC1U_nom_110%U_nom_90%

-0.8

-0.4

0.0

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1.2

1.6

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Win

do

w 3

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rbin

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Act

ive

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r [M

W]

-0.2

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1.0

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act

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VA

r]

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se 1

-3 [

V]

0

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-3 [

V]

10:36:02 10:36:04 10:36:06 10:36:08 10:36:10 10:36:12 10:36:14 10:36:16 10:36:18 10:36:20 10:36:22 10:36:24 10:36:26 10:36:28 10:36:30

26.11.09

h:m:s

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Compliance testing (2) – Reactive power range

• Grid code requires absorption and injection• Absorption reactive power: 10% of nominal active power• Injection reactive power : 45% of nominal active power • EU-process of harmonisation, consultation process in Belgium

• Full test not always possible in operational grid Same isolated grid operation allows full test

• Initial voltage set by changing tap on 150/70 kV transformer• Limited by safe voltages and tap range of transformer

• Lowest achievable reference voltage: 66.6 kV, due to tap limit• Highest safe reference voltage: 76.4kV

• Q-injection and absorption tested at various V-levels

• Very large Q-range available at all voltages

Reactive power range – Fixed transformer tap

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-40

-30

-20

-10

0

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67 68 69 70 71 72 73 74 75 76

Voltage [kV]

Q [

Mva

r]

Reactive power range – High and low voltage

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0

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67 68 69 70 71 72 73 74 75 76 77

Voltage [kV]

Q [

Mva

r]

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Direct TSO control on wind farm

• Potential disadvantage of requirements on active and reacive power: need for 24/7 dispatching centre

• Not justified for smaller operators

Solution: direct control from TSO/DSO dispatching• Development of direct communication & control system• First application of this type for Elia • Between TSO/DSO dispatching centre and wind farm SCADA• Elia dispatcher enters reactive power setpoint• Wind farm SCADA receives setpoint and automatically

distributes over individual turbines• Active power setpoint: only for emergency purposes

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Conclusion

• Innovative component of pilot project co-financed by EC• Development of Grid Code requirements &

turbine capabilities• Development of compliance testing procedures

• Fault-Ride-Through test on full wind farm• Reactive power range test at wide range of grid voltages

• Development of direct communication & control• TSO control avoids need for 24/7 dispatch by farm operators

• Essential developments for high penetration of wind power and other renewable energy sources• Further in pilot project: application in island system (Cyprus)