Voltage and Reactive Power Control by Wind Turbines

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012 Voltage and Reactive Power Control by Wind Turbines Jens Fortmann, ...
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Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Jens Fortmann, REpower Systems SE Berlin, October 16th 2012

Voltage and Reactive Power Control by Wind Turbines Starting point is the behavior of a synchronous generators

Questions for the turbine reactive power control design:

1

How should we operate a wind turbine to offer the best grid support possible

?

2

How do conventional power stations contribute to grid stability

?

3

How should wind turbines behave to replace conventional power stations with no need for further grid reinforcement or grid equipment

?

Can we do even better (than conventional power stations) Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

? 2

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Why consider dynamic requirements?

Static requirements: reactive current during normal operation Dynamic requirements: reactive current if voltage changes

1

Initially (before E.ON 2003): no dynamic requirement => all conventional power stations must stay in operation

2

Now: (SDLWindV): some dynamic requirements => most conventional power stations must stay in operation

3

Future (starting already…): fully replace conventional power stations => conventional power stations may shut down

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

3

Agenda

1. Basis: Behaviour of synchronous generators

2. Wind plant implementation

3. Simulations

4. Conclusion

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

4

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Agenda

1. Basis: Behaviour of synchronous generators

2. Wind plant implementation

3. Simulations

4. Conclusion

5

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Starting of E.ON Netz in 2003 Analysis of E.ON Netz from 2003: Response of a synchronous generator of a conventional power station

Source: Kühn, Radtke, “Der Einfluss von Windenergie auf das Verbundnetz”, E.ON Netz 2003

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

6

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Starting point is the behavior of a synchronous generators Starting point – diagram of a synchronous generator of a conventional power station

jxd  jxdc jxdc  jxdcc jxdcc   

v p v qc

ve AVR



vref

v qcc

rs jxq  jxqc jxqc  jxqcc  

vd

0

v dc

v dcc

jxqcc 

vs

z Tr  v Tr

i HV v HV

 



 reactive current high voltage field voltage / Setpoints generation (genertor) transformer excitation controller 7

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Change of reactive current and reactive current gain of a synchronous generators during grid faults, high voltage terminals Static calculation – behavior of a synchronous generator during grid faults, HV-level

5

4 stationary transient subtransient

'i QHV/'vHV / p.u.

'i Q,HV / p.u.

3

stationary transient subtransient

4

2

1

3 2 1

0

0

1

0.8

0.6 0.4 'vHV / p.u.

0.2

0

Reactive current change of a synchronous generator during grid faults as function of voltage change at HV-level. Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

1

0.8

0.6 0.4 'vHV / p.u.

0.2

0

Reactive current gain ǻiQHV/ǻuHV of a synchronous generators during grid faults as function of voltage change on HV-level. 8

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Synchronous generator model used for dynamic simulation Dynamic simulation – 7th order SG model and fault model IEEE Type 1 excitation system

SN = 55 MVA xk = 12 % rk = 0.3 %

vfd

10 kV

Grid model

110 kV xk = 10 % rk = 1.0 %

ve

Grid SN = 55 MVA PN = 50MW HV cos ij = 0.9 transformer 7th order dynamic model Fault impedance xd = xq = 2 p.u. xd’ = xq’ = 0.4 p.u. xd’’= xq’’= 0.25 p.u. td’ = 1 s, td’’ = 0.05 s Hg = 5 s Grid fault model

9

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Reactive current of a synchronous generators during grid faults Dynamic simulation – reactive current of a SG during grid faults, HV-level 1.25

vHV / p.u.

1 0.75 0.5 AVR on v f=const

IQHV / / p.u.

0.25 0 0.4 2.5 2 1.5 1 0.5 0 -0.5 -1 -1.5 0.4

0.45

0.5

0.55

0.6

0.65

0.7

0.75

0.8

0.85

0.9

simple model is good enough ' IQ Technology ready for the grids of the future

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

20

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

© REpower Systems SE All rights reserved. No part of this document may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photography, recording, or any information storage and retrieval system, without permission from REpower Systems AG.

21

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Response to voltage dip by 15% (= distant fault) Voltage dip of 15% in the high voltage grid : SyncGen, WP, WP with deadband

6

WP SG WP w. deadband

0.9 0.85

0.6

0.8

1

1.2

0.25

1.4

5 4 3 2

0

1

-0.25

0

-0.5 0.4

WP SG WP w. deadband

7

1 0.95

0.8 0.4 0.5

QHV /Pn / p.u.

8

'i QHV /'vHV / p.u.

vHV / p.u.

1.1 1.05

0.6

0.8

-1 Almost no support by Wind Plant 1.4 1 0.5 with1.2 dead-band control

t/s

Reactive current of synchronous generator (green) and wind plant (blue) at voltage dip of 15% in the HV grid. Comparison to wind plant with deadband (red) Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

0.55

0.6

0.65

t/s

Effective gain ǻiQ/ǻv at HV-level at voltage dip of 15% for synchronous generator (green), wind plant as proposed (blue) and wind plant using dead-band (red).

22

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Comparison of synchronous generator and wind plant using proposed control

1 0.5 0 -0.5 -1

WP,HV SG,HV

1

WP,HV SG,HV

0.9 0.8

0

1

2

3

4

1.25

P/Pn / p.u.

2 1.5 1 0.5 0 -0.5

1.1

v / p.u.

1.25 1 0.75 0.5 0.25 0

0

1

2

3

4

0

1

2

3

4

0

1

2 t/s

3

4

1 0.75 0.5

0

1

2

3

4

0

1

2 t/s

3

4

Q/Pn / p.u.

Q/Pn / p.u.

P/Pn / p.u.

v / p.u.

Voltage in the high voltage grid: Synchronous Generator and Wind Plant

0.5 0.25 0 -0.25 -0.5

Voltage dip by 80%

Voltage dip by 15% Severe oscillations of Sync. Generator Almost no oscillations by Wind Plant 23

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Comparison of synchronous generator and wind plant using proposed control Voltage dip by 80% in the high voltage grid: Synchronous Generator and Wind Plant SG: Poor response 1.25 following dip

1.25

1 vMV / p.u.

' v > 10%

0.75 0.5

0.6

0.8 ' IQ > 50%

IQHV /IP n / p.u.

0.25 ' v < 2% 0 0.4 2.5 2 1.5 1 0.5 0 -0.5 -1 -1.5 0.4

WP SG

0.6

0.8

0.5

WP SG

0.25

Higher currents by 1

0

Sync. Generator 2.50.4

2 1.5 1 Almost no impact0.5 0 on voltage -0.5 -1 -1.5 1 0.4

t/s

Voltage and Currents at HV side Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

0.75

BUT

0.6

0.8

1

0.8

1

IQMV /IP n / p.u.

vHV / p.u.

1

0.6 t/s

Voltage and Currents at MV side 24

Presented at 2012 3rd IEEE PES ISGT Europe, Berlin, Germany, October 14 -17, 2012

Voltage and Reactive Power Control by Wind Turbines Starting point is the behavior of a synchronous generators Starting point – diagram of a synchronous generator of a conventional power station

jx  jx c jx c  jx cc jxddcccc jxdccd  d jxd d  d  „subtransient“

v p v qc

ve AVR

vref



v qqcc

reactive short circuit current: § v v im ¨ q HV ¨ jx cc  z TR © d

iQ

rs jxq  jxqc jxqc  jxqcc  

vd

0

v dc

v dcc

jxqcc 

vs

z Tr  v Tr

· ¸ ¸ ¹

i HV v HV

 



 reactive current high voltage field voltage / Setpoints generation (genertor) transformer excitation controller 25

Jens Fortmann, IEEE ISGT, 16.10.2012, © REpower Systems SE

Voltage and Reactive Power Control by Wind Turbines Starting point is the behavior of a synchronous generators Starting point – diagram of a synchronous generator of a conventional power station

jxddcccc dcjxdcc jx jxdjcxd

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