Application of STATCOM for improved dynamic performance of wind farms in a power grid

79 Pages·2017·2.34 MB·English

by  Aditya P. Jayam

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Masters Theses Student Theses and Dissertations
Spring 2008
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Aditya P. Jayam
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grid" (2008). Masters Theses. 4632.
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APPLICATION OF STATCOM FOR IMPROVED DYNAMIC PERFORMANCE OF
WIND FARMS IN A POWER GRID

by

ADITYA JAYAM PRABHAKAR

A THESIS

Presented to the Faculty of the Graduate School of the

MISSOURI UNIVERSITY OF SCIENCE AND TECHNOLOGY

In Partial Fulfillment of the Requirements for the Degree

MASTER OF SCIENCE IN ELECTRICAL ENGINEERING

2008

Approved by

Badrul H. Chowdhury, Advisor
Keith A. Corzine
Mehdi Ferdowsi
© 2008
Aditya Jayam Prabhakar
All Rights Reserved
iii
ABSTRACT
When integrated to the power system, large wind farms pose stability and control
issues. A thorough study is needed to identify the potential problems and to develop
measures to mitigate them. Although integration of high levels of wind power into an
existing transmission system does not require a major redesign, it necessitates additional
control and compensating equipment to enable recovery from severe system disturbances.
This thesis investigates the use of a Static Synchronous Compensator
(STATCOM) along with wind farms for the purpose of stabilizing the grid voltage after
grid-side disturbances such as a three phase short circuit fault, temporary trip of a wind
turbine and sudden load changes. The strategy focuses on a fundamental grid operational
requirement to maintain proper voltages at the point of common coupling by regulating
voltage. The DC voltage at individual wind turbine (WT) inverters is also stabilized to
facilitate continuous operation of wind turbines during disturbances.
iv
ACKNOWLEDGMENTS
I would like to thank my advisor, Dr. Badrul Chowdhury, for his unending
support and encouragement. He has always been very helpful, friendly, and a great source
of motivation for me during my graduate program here at Missouri S&T.
I would also like to thank Dr. Keith Corzine and Dr. Mehdi Ferdowsi for serving
on my committee, taking time to review my thesis, and especially for being wonderful
course instructors. I would like to thank Dr. Mariesa Crow for her supportive and
motivating words.
I would like to thank my best friend on campus, Dr. Richard E. DuBroff for
always being very supportive and friendly. Thank you for being there for me whenever I
needed help.
I would like to thank Dr. Keith Stanek, Dr. Max Anderson, Dr. Daryl Beetner, Dr.
Jun Fan, and Dr. Jonathan Kimball for their constant support.
I would like to thank Nikhil Ardeshna, my friend and project partner, for
substantially contributing to a good research group.
Thanks are due to all my friends on campus who made my stay here in Rolla,
memorable: Nagasmitha Akkinapragada, Kalyani Radha Padma, Pakala Padmavathi,
Chitturi Bhuwaneshwari, Murali Mohan Baggu, Sarat Kumar Chitneni, Sasikiran
Burugapalli, Vamshi Kadiyala, Sanjeev Rao, Surbhi Mittal, Ankit Bhargava, Hong Tao
Ma, Xiaomeng Li, Atousa Yazdani, and Mahyar Zarghami.
I would like to thank the electrical and computer engineering department
secretary, Regina Kohout, for being my constant well-wisher.
I would like to thank my father, Jayam Prabhakar; my mother, Seetha Lakshmi;
and my dear sister Anusha Jayam Prabhakar for all their faith and confidence in me to
pursue a Master’s program in the United States. I am indebted to them for their unending
love and blessings throughout my work.
v
TABLE OF CONTENTS
Page
ABSTRACT.......................................................................................................................iii
ACKNOWLEDGMENTS.................................................................................................iv
LIST OF ILLUSTRATIONS............................................................................................vii
LIST OF TABLES.............................................................................................................ix
SECTION
1. INTRODUCTION......................................................................................................1
2. WIND ENERGY IN THE POWER SYSTEM..........................................................5
2.1. WIND ENERGY................................................................................................5
2.2. WIND FARM MODELING...............................................................................8
2.3. RELIABILITY AND STABILITY CONSIDERATIONS.................................9
2.4. POWER AND VOLTAGE PERFORMANCE..................................................9
2.5. PERFORMANCE OF A WT WITH FAULTS ON THE SYSTEM................10
3. VOLTAGE CONTROL IN THE PRESENCE OF WIND ENERGY.....................12
3.1. WIND TURBINE REACTIVE POWER CAPABILITY.................................12
3.2. FACTS DEVICES AND CAPABILITIES.......................................................12
3.3. SVC/STATCOM/UPFC COMPARISONS......................................................14
3.4. REASONS FOR CHOOSING A STATCOM..................................................16
4. THE STATCOM......................................................................................................18
4.1. STATCOM MODEL........................................................................................18
4.2. LOCATION OF STATCOM............................................................................21
4.3. REACTIVE POWER SUPPORT FROM STATCOM.....................................22
5. TEST SYSTEM AND SIMULATION RESULTS..................................................23
5.1. TEST SYSTEM................................................................................................23
5.2. SIMULATION RESULTS...............................................................................25
5.2.1. Three phase impedance ground faults....................................................25
5.2.1.1 Without STATCOM...................................................................31
5.2.1.2 With a mechanically switched capacitor.....................................32
5.2.1.3 With 25 MVA STATCOM.........................................................34
vi
5.2.1.4 With 25 MVA STATCOM and MSC.........................................37
5.2.1.5 With 125 MVA STATCOM.......................................................41
5.2.2. Load changes..........................................................................................45
5.2.2.1 50% negative step change in reactive load.................................45
5.2.2.2 50% positive step change in reactive load..................................47
5.2.2.3 10% real and 50% reactive negative step change in load...........50
5.2.2.4 10% real and 50% reactive positive step change in load............53
5.2.3. Short term tripping of a Wind Turbine...................................................56
6. CONCLUSION AND FUTURE WORK.................................................................60
6.1. CONCLUSION.................................................................................................60
6.2. FUTURE WORK..............................................................................................62
APPENDIX ......................................................................................................................63
BIBLIOGRAPHY.............................................................................................................64
VITA ................................................................................................................................67
vii
LIST OF ILLUSTRATIONS
Figure Page
1.1. Cumulative wind power production in the United States............................................1
2.1. Block diagram of a doubly-fed induction generator....................................................7
2.2. LVRT requirement for wind generation facilities per FERC Order No. 661............11
3.1. US STATCOM installations......................................................................................13
3.2. SVC and its VI characteristics...................................................................................16
3.3. STATCOM and its VI characteristics........................................................................16
4.1. Basic model of a STATCOM....................................................................................18
4.2. Control scheme of the STATCOM [DIgSILENT version 13.6]................................20
5.1. Test system.................................................................................................................24
5.2. Voltage at the fault bus (Load bus)............................................................................26
5.3. Voltage at the fault bus (Zoomed version)................................................................27
5.4. Voltage at the synchronous generator bus.................................................................28
5.5. Voltage at the synchronous generator bus (Zoomed version)...................................29
5.6. Voltage at the collector bus........................................................................................30
5.7. Voltage at the collector bus (Zoomed version)..........................................................31
5.8. Reactive power in the system with no compensating device.....................................32
5.9. Reactive power in the system with mechanically switched capacitors......................33
5.10. Reactive power supplied by the MSC and the MSC terminal voltage....................34
5.11. Reactive power and active power of the STATCOM..............................................35
5.12. AC and DC busbar voltages of the STATCOM......................................................36
5.13. Reactive powers in the system with a 25 MVA STATCOM...................................37
5.14. Reactive and active powers of the STATCOM.......................................................38
5.15. Reactive power and terminal voltage of the MSC...................................................39
5.16. AC and DC busbar voltages of the STATCOM......................................................40
5.17. Reactive powers of the system with a STATCOM and MSC.................................41
5.18. Reactive power of the 125 MVA STATCOM.........................................................42
5.19. AC and DC busbar voltages of the 125 MVA STATCOM.....................................43
5.20. Reactive powers of the system with a STATCOM and MSC.................................44
viii
5.21. Load bus voltages....................................................................................................45
5.22. AC and DC busbar voltages of the 25 MVA STATCOM.......................................46
5.23. Reactive and active powers of the STATCOM.......................................................47
5.24. Load bus voltages....................................................................................................48
5.25 AC and DC busbar voltages of the 25 MVA STATCOM........................................49
5.26. Reactive and active powers of the STATCOM.......................................................50
5.27. Load bus voltages....................................................................................................51
5.28. AC and DC terminal voltages of the STATCOM....................................................52
5.29. Reactive and active powers of the STATCOM.......................................................53
5.30. Load bus voltages....................................................................................................54
5.31. AC and dc terminal voltages of the STATCOM.....................................................55
5.32. Reactive and active powers of the STATCOM.......................................................56
5.33. Load bus voltage without STATCOM.....................................................................57
5.34. Load bus voltage with STATCOM..........................................................................58
5.35. Reactive power and active power of the STATCOM..............................................59