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

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