DEHONG XU, PHD, is a Professor in the College of Electrical Engineering of Zhejiang University, China, where he teaches modelling and control of power electronics and renewable systems. FREDE BLAABJERG, PHD, is a Professor in Power Electronics and Villum Investigator at the Department of Energy Technology, Aalborg University, Denmark, as well as a Visiting Professor at Zhejiang University, China. WENJIE CHEN received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in Powertrain Solution Division, BOSCH. NAN ZHU received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in the renewable energy division of Huawei.

• PREFACE xiiiNOMENCLATURE xvPART I INTRODUCTION TO WIND POWER GENERATIONCHAPTER 1 INTRODUCTION 31.1 Global Wind Power Development 31.2 Evolution of Wind Power System 51.3 Power Electronics in Wind Turbine Systems 91.4 Challenges and Trends in Future Wind Power Technology 111.5 The Topics of This Book 18CHAPTER 2 BASICS OF WIND POWER GENERATION SYSTEM 212.1 Introduction 212.2 Wind Power Concept 212.3 Variable-Speed Wind Turbine 262.4 Control of Power Converter 312.5 Wind Power Transmission 342.6 Summary 41CHAPTER 3 GRID CODES FOR WIND POWER GENERATION SYSTEMS 433.1 Introduction 433.2 Grid Code Requirements Under Normal Operation 443.3 Grid Code Requirements Under Non-Ideal Grid 513.4 Grid Codes for Distributed Wind Power Generation 583.5 Summary 62PART II MODELING AND CONTROL OF DFIGCHAPTER 4 MODELING OF DFIG WIND POWER SYSTEMS 674.1 Introduction 674.2 Steady-State Equivalent Circuit of a DFIG 674.3 Dynamic Model of a DFIG 744.4 Modeling of the Converter 854.5 Summary 95CHAPTER 5 CONTROL OF DFIG POWER CONVERTERS 995.1 Introduction 995.2 Start-Up Process of the DFIG System 995.3 Grid-Side Converter 1015.4 Rotor-Side Converter in Power-Control Mode 1145.5 Rotor-Side Converter in Speed-Control Mode 1245.6 Rotor-Side Converter in Starting Mode 1285.7 Control-Mode Switching 1355.8 Summary 136PART III OPERATION OF DFIG UNDER DISTORTED GRID VOLTAGECHAPTER 6 ANALYSIS OF DFIG UNDER DISTORTED GRID VOLTAGE 1416.1 Introduction 1416.2 Influence on GSC 1426.3 Influence on DFIG and RSC 1496.4 Discussion on Different Controller Parameters 1626.5 Discussion on Different Power Scales 1636.6 Summary 164CHAPTER 7 MULTIPLE-LOOP CONTROL OF DFIG UNDER DISTORTED GRID VOLTAGE 1677.1 Introduction 1677.2 GSC Control 1687.3 DFIG and RSC Control 1767.4 Influence on the Fundamental Current Loop 1887.5 Summary 191CHAPTER 8 RESONANT CONTROL OF DFIG UNDER GRID VOLTAGE HARMONICS DISTORTION 1958.1 Introduction 1958.2 Resonant Controller 1958.3 Stator Current Control Using Resonant Controllers 1978.4 Influence on Normal Control Loop 2158.5 Design and Optimization of Current Controller 2228.6 Summary 233CHAPTER 9 DFIG UNDER UNBALANCED GRID VOLTAGE 2379.1 Introduction 2379.2 RSC and DFIG Under Unbalanced Grid Voltage 2379.3 GSC Under Unbalanced Grid Voltage 2449.4 Control Limitations Under Unbalanced Grid Voltage 2489.5 Summary 256CHAPTER 10 CONTROL OF DFIG WIND POWER SYSTEM UNDER UNBALANCED GRID VOLTAGE 25910.1 Introduction 25910.2 Control Targets 25910.3 Stator Current Control with Resonant Controller 26010.4 DC Voltage Fluctuation Control by GSC 26610.5 Summary 293PART IV GRID FAULT RIDE-THROUGH OF DFIGCHAPTER 11 DYNAMIC MODEL OF DFIG UNDER GRID FAULTS 29911.1 Introduction 29911.2 Behavior During Voltage Dips 30011.3 DFIG Behavior During Voltage Recovery 31511.4 Under Recurring Grid Faults 32011.5 Summary 339CONTENTS xiCHAPTER 12 GRID FAULT RIDE-THROUGH OF DFIG 34112.1 Introduction 34112.2 PLL Under Grid Faults 34212.3 FRT Strategies for DFIG Based on Improved Control 34812.4 FRT Strategies Based on Hardware Solutions 36212.5 Recurring Fault Ride Through 36912.6 Summary 384CHAPTER 13 THERMAL CONTROL OF POWER CONVERTER IN NORMAL AND ABNORMAL OPERATIONS 38713.1 Loss Model of Power Converter 38713.2 Thermal Model of Power Converter 39213.3 Thermal Loading During Normal Operation 39713.4 Thermal Loading in Abnormal Operation 40113.5 Smart Thermal Control by Reactive Power Circulation 40813.6 Summary 412PART V DFIG TEST BENCHCHAPTER 14 DFIG TEST BENCH 41714.1 Introduction 41714.2 Scheme of the DFIG Test Bench 41714.3 The Caged Motor and its Driving Inverter 41914.4 DFIG Test System 42014.5 Rotor-Side Crowbar 42914.6 Grid Emulator 43114.7 Communications and Up-Level Control 43914.8 Start-Up and Protection of the System 44114.9 Summary 448APPENDIX 449A.1 Flux Equations in α β Reference Frame 449A.2 Typical Parameters of a DFIG 451INDEX 453

DEHONG XU, PHD, is a Professor in the College of Electrical Engineering of Zhejiang University, China, where he teaches modelling and control of power electronics and renewable systems. FREDE BLAABJERG, PHD, is a Professor in Power Electronics and Villum Investigator at the Department of Energy Technology, Aalborg University, Denmark, as well as a Visiting Professor at Zhejiang University, China. WENJIE CHEN received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in Powertrain Solution Division, BOSCH. NAN ZHU received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in the renewable energy division of Huawei.

• PREFACE xiiiNOMENCLATURE xvPART I INTRODUCTION TO WIND POWER GENERATIONCHAPTER 1 INTRODUCTION 31.1 Global Wind Power Development 31.2 Evolution of Wind Power System 51.3 Power Electronics in Wind Turbine Systems 91.4 Challenges and Trends in Future Wind Power Technology 111.5 The Topics of This Book 18CHAPTER 2 BASICS OF WIND POWER GENERATION SYSTEM 212.1 Introduction 212.2 Wind Power Concept 212.3 Variable-Speed Wind Turbine 262.4 Control of Power Converter 312.5 Wind Power Transmission 342.6 Summary 41CHAPTER 3 GRID CODES FOR WIND POWER GENERATION SYSTEMS 433.1 Introduction 433.2 Grid Code Requirements Under Normal Operation 443.3 Grid Code Requirements Under Non-Ideal Grid 513.4 Grid Codes for Distributed Wind Power Generation 583.5 Summary 62PART II MODELING AND CONTROL OF DFIGCHAPTER 4 MODELING OF DFIG WIND POWER SYSTEMS 674.1 Introduction 674.2 Steady-State Equivalent Circuit of a DFIG 674.3 Dynamic Model of a DFIG 744.4 Modeling of the Converter 854.5 Summary 95CHAPTER 5 CONTROL OF DFIG POWER CONVERTERS 995.1 Introduction 995.2 Start-Up Process of the DFIG System 995.3 Grid-Side Converter 1015.4 Rotor-Side Converter in Power-Control Mode 1145.5 Rotor-Side Converter in Speed-Control Mode 1245.6 Rotor-Side Converter in Starting Mode 1285.7 Control-Mode Switching 1355.8 Summary 136PART III OPERATION OF DFIG UNDER DISTORTED GRID VOLTAGECHAPTER 6 ANALYSIS OF DFIG UNDER DISTORTED GRID VOLTAGE 1416.1 Introduction 1416.2 Influence on GSC 1426.3 Influence on DFIG and RSC 1496.4 Discussion on Different Controller Parameters 1626.5 Discussion on Different Power Scales 1636.6 Summary 164CHAPTER 7 MULTIPLE-LOOP CONTROL OF DFIG UNDER DISTORTED GRID VOLTAGE 1677.1 Introduction 1677.2 GSC Control 1687.3 DFIG and RSC Control 1767.4 Influence on the Fundamental Current Loop 1887.5 Summary 191CHAPTER 8 RESONANT CONTROL OF DFIG UNDER GRID VOLTAGE HARMONICS DISTORTION 1958.1 Introduction 1958.2 Resonant Controller 1958.3 Stator Current Control Using Resonant Controllers 1978.4 Influence on Normal Control Loop 2158.5 Design and Optimization of Current Controller 2228.6 Summary 233CHAPTER 9 DFIG UNDER UNBALANCED GRID VOLTAGE 2379.1 Introduction 2379.2 RSC and DFIG Under Unbalanced Grid Voltage 2379.3 GSC Under Unbalanced Grid Voltage 2449.4 Control Limitations Under Unbalanced Grid Voltage 2489.5 Summary 256CHAPTER 10 CONTROL OF DFIG WIND POWER SYSTEM UNDER UNBALANCED GRID VOLTAGE 25910.1 Introduction 25910.2 Control Targets 25910.3 Stator Current Control with Resonant Controller 26010.4 DC Voltage Fluctuation Control by GSC 26610.5 Summary 293PART IV GRID FAULT RIDE-THROUGH OF DFIGCHAPTER 11 DYNAMIC MODEL OF DFIG UNDER GRID FAULTS 29911.1 Introduction 29911.2 Behavior During Voltage Dips 30011.3 DFIG Behavior During Voltage Recovery 31511.4 Under Recurring Grid Faults 32011.5 Summary 339CONTENTS xiCHAPTER 12 GRID FAULT RIDE-THROUGH OF DFIG 34112.1 Introduction 34112.2 PLL Under Grid Faults 34212.3 FRT Strategies for DFIG Based on Improved Control 34812.4 FRT Strategies Based on Hardware Solutions 36212.5 Recurring Fault Ride Through 36912.6 Summary 384CHAPTER 13 THERMAL CONTROL OF POWER CONVERTER IN NORMAL AND ABNORMAL OPERATIONS 38713.1 Loss Model of Power Converter 38713.2 Thermal Model of Power Converter 39213.3 Thermal Loading During Normal Operation 39713.4 Thermal Loading in Abnormal Operation 40113.5 Smart Thermal Control by Reactive Power Circulation 40813.6 Summary 412PART V DFIG TEST BENCHCHAPTER 14 DFIG TEST BENCH 41714.1 Introduction 41714.2 Scheme of the DFIG Test Bench 41714.3 The Caged Motor and its Driving Inverter 41914.4 DFIG Test System 42014.5 Rotor-Side Crowbar 42914.6 Grid Emulator 43114.7 Communications and Up-Level Control 43914.8 Start-Up and Protection of the System 44114.9 Summary 448APPENDIX 449A.1 Flux Equations in α β Reference Frame 449A.2 Typical Parameters of a DFIG 451INDEX 453

DEHONG XU, PHD, is a Professor in the College of Electrical Engineering of Zhejiang University, China, where he teaches modelling and control of power electronics and renewable systems. FREDE BLAABJERG, PHD, is a Professor in Power Electronics and Villum Investigator at the Department of Energy Technology, Aalborg University, Denmark, as well as a Visiting Professor at Zhejiang University, China. WENJIE CHEN received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in Powertrain Solution Division, BOSCH. NAN ZHU received a PhD from the College of Electrical Engineering of Zhejiang University. Now he is a senior engineer in the renewable energy division of Huawei.

• PREFACE xiiiNOMENCLATURE xvPART I INTRODUCTION TO WIND POWER GENERATIONCHAPTER 1 INTRODUCTION 31.1 Global Wind Power Development 31.2 Evolution of Wind Power System 51.3 Power Electronics in Wind Turbine Systems 91.4 Challenges and Trends in Future Wind Power Technology 111.5 The Topics of This Book 18CHAPTER 2 BASICS OF WIND POWER GENERATION SYSTEM 212.1 Introduction 212.2 Wind Power Concept 212.3 Variable-Speed Wind Turbine 262.4 Control of Power Converter 312.5 Wind Power Transmission 342.6 Summary 41CHAPTER 3 GRID CODES FOR WIND POWER GENERATION SYSTEMS 433.1 Introduction 433.2 Grid Code Requirements Under Normal Operation 443.3 Grid Code Requirements Under Non-Ideal Grid 513.4 Grid Codes for Distributed Wind Power Generation 583.5 Summary 62PART II MODELING AND CONTROL OF DFIGCHAPTER 4 MODELING OF DFIG WIND POWER SYSTEMS 674.1 Introduction 674.2 Steady-State Equivalent Circuit of a DFIG 674.3 Dynamic Model of a DFIG 744.4 Modeling of the Converter 854.5 Summary 95CHAPTER 5 CONTROL OF DFIG POWER CONVERTERS 995.1 Introduction 995.2 Start-Up Process of the DFIG System 995.3 Grid-Side Converter 1015.4 Rotor-Side Converter in Power-Control Mode 1145.5 Rotor-Side Converter in Speed-Control Mode 1245.6 Rotor-Side Converter in Starting Mode 1285.7 Control-Mode Switching 1355.8 Summary 136PART III OPERATION OF DFIG UNDER DISTORTED GRID VOLTAGECHAPTER 6 ANALYSIS OF DFIG UNDER DISTORTED GRID VOLTAGE 1416.1 Introduction 1416.2 Influence on GSC 1426.3 Influence on DFIG and RSC 1496.4 Discussion on Different Controller Parameters 1626.5 Discussion on Different Power Scales 1636.6 Summary 164CHAPTER 7 MULTIPLE-LOOP CONTROL OF DFIG UNDER DISTORTED GRID VOLTAGE 1677.1 Introduction 1677.2 GSC Control 1687.3 DFIG and RSC Control 1767.4 Influence on the Fundamental Current Loop 1887.5 Summary 191CHAPTER 8 RESONANT CONTROL OF DFIG UNDER GRID VOLTAGE HARMONICS DISTORTION 1958.1 Introduction 1958.2 Resonant Controller 1958.3 Stator Current Control Using Resonant Controllers 1978.4 Influence on Normal Control Loop 2158.5 Design and Optimization of Current Controller 2228.6 Summary 233CHAPTER 9 DFIG UNDER UNBALANCED GRID VOLTAGE 2379.1 Introduction 2379.2 RSC and DFIG Under Unbalanced Grid Voltage 2379.3 GSC Under Unbalanced Grid Voltage 2449.4 Control Limitations Under Unbalanced Grid Voltage 2489.5 Summary 256CHAPTER 10 CONTROL OF DFIG WIND POWER SYSTEM UNDER UNBALANCED GRID VOLTAGE 25910.1 Introduction 25910.2 Control Targets 25910.3 Stator Current Control with Resonant Controller 26010.4 DC Voltage Fluctuation Control by GSC 26610.5 Summary 293PART IV GRID FAULT RIDE-THROUGH OF DFIGCHAPTER 11 DYNAMIC MODEL OF DFIG UNDER GRID FAULTS 29911.1 Introduction 29911.2 Behavior During Voltage Dips 30011.3 DFIG Behavior During Voltage Recovery 31511.4 Under Recurring Grid Faults 32011.5 Summary 339CONTENTS xiCHAPTER 12 GRID FAULT RIDE-THROUGH OF DFIG 34112.1 Introduction 34112.2 PLL Under Grid Faults 34212.3 FRT Strategies for DFIG Based on Improved Control 34812.4 FRT Strategies Based on Hardware Solutions 36212.5 Recurring Fault Ride Through 36912.6 Summary 384CHAPTER 13 THERMAL CONTROL OF POWER CONVERTER IN NORMAL AND ABNORMAL OPERATIONS 38713.1 Loss Model of Power Converter 38713.2 Thermal Model of Power Converter 39213.3 Thermal Loading During Normal Operation 39713.4 Thermal Loading in Abnormal Operation 40113.5 Smart Thermal Control by Reactive Power Circulation 40813.6 Summary 412PART V DFIG TEST BENCHCHAPTER 14 DFIG TEST BENCH 41714.1 Introduction 41714.2 Scheme of the DFIG Test Bench 41714.3 The Caged Motor and its Driving Inverter 41914.4 DFIG Test System 42014.5 Rotor-Side Crowbar 42914.6 Grid Emulator 43114.7 Communications and Up-Level Control 43914.8 Start-Up and Protection of the System 44114.9 Summary 448APPENDIX 449A.1 Flux Equations in α β Reference Frame 449A.2 Typical Parameters of a DFIG 451INDEX 453