E-book

# Voltage-Sourced Converters in Power Systems : Modeling, Control, and Applications

ISBN: 978-0-470-55156-1
541 pages
March 2010

## Description

Presents Fundamentals of Modeling, Analysis, and Control of Electric Power Converters for Power System Applications

Electronic (static) power conversion has gained widespread acceptance in power systems applications; electronic power converters are increasingly employed for power conversion and conditioning, compensation, and active filtering. This book presents the fundamentals for analysis and control of a specific class of high-power electronic converters—the three-phase voltage-sourced converter (VSC). Voltage-Sourced Converters in Power Systems provides a necessary and unprecedented link between the principles of operation and the applications of voltage-sourced converters. The book:

• Describes various functions that the VSC can perform in electric power systems
• Covers a wide range of applications of the VSC in electric power systems—including wind power conversion systems
• Adopts a systematic approach to the modeling and control design problems
• Illustrates the control design procedures and expected performance based on a comprehensive set of examples and digital computer time-domain simulation studies

This comprehensive text presents effective techniques for mathematical modeling and control design, and helps readers understand the procedures and analysis steps. Detailed simulation case studies are included to highlight the salient points and verify the designs.

Voltage-Sourced Converters in Power Systems is an ideal reference for senior undergraduate and graduate students in power engineering programs, practicing engineers who deal with grid integration and operation of distributed energy resource units, design engineers, and researchers in the area of electric power generation, transmission, distribution, and utilization.

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PREFACE xv

ACKNOWLEDGMENTS xvii

ACRONYMS xix

1 Electronic Power Conversion 1

1.1 Introduction 1

1.2 Power-Electronic Converters and Converter Systems 1

1.3 Applications of Electronic Converters in Power Systems 3

1.4 Power-Electronic Switches 4

1.5 Classification of Converters 8

1.6 Voltage-Sourced Converter (VSC) 10

1.7 Basic Configurations 10

1.8 Scope of the Book 20

PART I FUNDAMENTALS 21

2 DC/AC Half-Bridge Converter 23

2.1 Introduction 23

2.2 Converter Structure 23

2.3 Principles of Operation 25

2.4 Converter Switched Model 27

2.5 Converter Averaged Model 32

2.6 Nonideal Half-Bridge Converter 38

3 Control of Half-Bridge Converter 48

3.1 Introduction 48

3.2 AC-Side Control Model of Half-Bridge Converter 48

3.3 Control of Half-Bridge Converter 50

3.4 Feed-Forward Compensation 53

3.5 Sinusoidal Command Following 59

4 Space Phasors and Two-Dimensional Frames 69

4.1 Introduction 69

4.2 Space-Phasor Representation of a Balanced Three-Phase Function 70

4.3 Space-Phasor Representation of Three-Phase Systems 82

4.4 Power in Three-Wire Three-Phase Systems 88

4.5 αβ-Frame Representation and Control of Three-Phase Signals and Systems 91

4.6 dq-Frame Representation and Control of Three-Phase Systems 101

5 Two-Level, Three-Phase Voltage-Sourced Converter 115

5.1 Introduction 115

5.2 Two-Level Voltage-Sourced Converter 115

5.3 Models and Control of Two-Level VSC 119

5.4 Classification of VSC Systems 125

6 Three-Level, Three-Phase, Neutral-Point Clamped, Voltage-Sourced Converter 127

6.1 Introduction 127

6.2 Three-Level Half-Bridge NPC 128

6.3 PWM Scheme For Three-Level Half-Bridge NPC 130

6.4 Switched Model of Three-Level Half-Bridge NPC 133

6.5 Averaged Model of Three-Level Half-Bridge NPC 135

6.6 Three-Level NPC 136

6.7 Three-Level NPC with Capacitive DC-Side Voltage Divider 144

7 Grid-Imposed Frequency VSC System: Control in αβ-Frame 160

7.1 Introduction 160

7.2 Structure of Grid-Imposed Frequency VSC System 160

7.3 Real-/Reactive-Power Controller 161

7.4 Real-/Reactive-Power Controller Based on Three-Level NPC 181

7.5 Controlled DC-Voltage Power Port 189

8 Grid-Imposed Frequency VSC System: Control in dq-Frame 204

8.1 Introduction 204

8.2 Structure of Grid-Imposed Frequency VSC System 205

8.3 Real-/Reactive-Power Controller 206

8.4 Current-Mode Control of Real-/Reactive-Power Controller 217

8.5 Real-/Reactive-Power Controller Based on Three-Level NPC 232

8.6 Controlled DC-Voltage Power Port 234

9 Controlled-Frequency VSC System 245

9.1 Introduction 245

9.2 Structure of Controlled-Frequency VSC System 246

9.3 Model of Controlled-Frequency VSC System 247

9.4 Voltage Control 253

10 Variable-Frequency VSC System 270

10.1 Introduction 270

10.2 Structure of Variable-Frequency VSC System 270

10.3 Control of Variable-Frequency VSC System 273

PART II APPLICATIONS 311

11 Static Compensator (STATCOM) 313

11.1 Introduction 313

11.2 Controlled DC-Voltage Power Port 313

11.3 STATCOM Structure 314

11.4 Dynamic Model for PCC Voltage Control 315

11.5 Approximate Model of PCC Voltage Dynamics 321

11.6 STATCOM Control 322

11.7 Compensator Design for PCC Voltage Controller 324

11.8 Model Evaluation 324

12 Back-to-Back HVDC Conversion System 334

12.1 Introduction 334

12.2 HVDC System Structure 334

12.3 HVDC System Model 336

12.4 HVDC System Control 342

12.5 HVDC System Performance Under an Asymmetrical Fault 353

13 Variable-SpeedWind-Power System 385

13.1 Introduction 385

13.2 Constant-Speed and Variable-Speed Wind-Power Systems 385

13.3 Wind Turbine Characteristics 388

13.4 Maximum Power Extraction from A Variable-Speed Wind-Power System 390

13.5 Variable-Speed Wind-Power System Based on Doubly-Fed Asynchronous Machine 393

APPENDIXA: Space-Phasor Representation of Symmetrical Three-Phase Electric Machines 413

A.1 Introduction 413

A.2 Structure of Symmetrical Three-Phase Machine 413

A.3 Machine Electrical Model 414

A.4 Machine Equivalent Circuit 418

A.5 Permanent-Magnet Synchronous Machine (PMSM) 421

APPENDIX B: Per-Unit Values for VSC Systems 426

B.1 Introduction 426

REFERENCES 431

INDEX 439

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## Author Information

Amirnaser Yazdani, PhD, is an assistant professor in the Department of Electrical and Computer Engineering at the University of Western Ontario. Formerly, he was with Digital Predictive Systems (DPS) Inc., Mississauga, Ontario, active in the design and production of power converters for wind energy systems. Dr. Yazdani has more than ten years of industry experience in the design, modeling, and analysis of switching power converters and railway signaling systems. He is a Senior Member of the IEEE and a professional engineer in the province of Ontario, Canada.

Reza Iravani, PhD, is a professor in the Department of Electrical and Computer Engineering at the University of Toronto. Dr. Iravani is a Fellow of the IEEE and a professional engineer in the province of Ontario, Canada.

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