Edgar Lenymirko Moreno-Goytia, Reader, Instituto Tecnológico de Morelia, MéxicoDr Moreno-Goytia has researched power electronic-based equipment and measurement systems development. He designed and built a Thyristor Controlled Series Compensator and its control to operate in a voltage fluctuations environment, and has been involved in evaluating the impact of wind generation on the electrical grid. Dr Moreno-Goytia has published over thirty papers in international conferences and journals and is a member of IEEE and IET.Olimpo Anaya-Lara, Senior Lecturer, Institute for Energy and Environment , University of Strathclyde, Glasgow, UKDr Anaya-Lara has researched power electronic equipment, control systems development, and stability and control of power systems with increased wind energy penetration. He has developed control strategies for Flexible Alternating Current Transmission System devices (FACTS), and designed control schemes for marine applications using advanced control techniques. He is a member of the CIGRE Working Group B4-39, two International Energy Agency Annexes, also the IEEE and IET. He has published over thirty-five journals, ninety papers and co-authored three books.David Campos-Gaona, Research Assistant, Instituto Tecnológico de Morelia, MéxicoMr Campos-Gaona has investigated electronics-based solutions to electrical networks such as digital power meters, DSP based protection algorithms, and protection systems for wind turbines. He developed electronic equipment such as residential digital power meter with a wireless communication port. He was a research assistant with the SUPERGEN FlexNet, and is member of the IEEE. He  has published several papers and conference proceedings.Grain Philip Adam, Research Fellow, University of Strathclyde, Glasgow, UKGrain received a Ph.D. degree in power electronics from Strathclyde University in 2007. He is currently with the Department of Electronic and Electrical Engineering, Strathclyde University, and his research interests are multilevel inverters, electrical machines and power systems control and stability.

• Preface xi About the Authors xiiiAcronyms and Symbols xv1 Offshore Wind Energy Systems 11.1 Background 11.2 Typical Subsystems 11.3 Wind Turbine Technology 41.3.1 Basics 41.3.2 Architectures 61.3.3 Offshore Wind Turbine Technology Status 71.4 Offshore Transmission Networks 81.5 Impact on Power System Operation 91.5.1 Power System Dynamics and Stability 101.5.2 Reactive Power and Voltage Support 101.5.3 Frequency Support 111.5.4 Wind Turbine Inertial Response 111.6 Grid Code Regulations for the Connection of Wind Generation 12Acknowledgements 13References 142 DFIG Wind Turbine 152.1 Introduction 152.1.1 Induction Generator (IG) 152.1.2 Back-to-Back Converter 162.1.3 Gearbox 162.1.4 Crowbar Protection 162.1.5 Turbine Transformer 172.2 DFIG Architecture and Mathematical Modelling 172.2.1 IG in the abc Reference Frame 172.2.2 IG in the dq0 Reference Frame 232.2.3 Mechanical System 272.2.4 Crowbar Protection 292.2.5 Modelling of the DFIG B2B Power Converter 302.2.6 Average Modelling of Power Electronic Converters 332.2.7 The dc Circuit 352.3 Control of the DFIG WT 362.3.1 PI Control of Rotor Speed 362.3.2 PI Control of DFIG Reactive Power 392.3.3 PI Control of Rotor Currents 412.3.4 PI Control of dc Voltage 422.3.5 PI Control of Grid-side Converter Currents 452.4 DFIG Dynamic Performance Assessment 472.4.1 Three-phase Fault 472.4.2 Symmetrical Voltage Dips 512.4.3 Asymmetrical Faults 532.4.4 Single-Phase-to-Ground Fault 542.4.5 Phase-to-Phase Fault 552.4.6 Torque Behaviour under Symmetrical Faults 562.4.7 Torque Behaviour under Asymmetrical Faults 582.4.8 Effects of Faults in the Reactive Power Consumption of the IG 592.5 Fault Ride-Through Capabilities and Grid Code Compliance 602.5.1 Advantages and Disadvantages of the Crowbar Protection 602.5.2 Effects of DFIG Variables over Its Fault Ride-Through Capabilities 612.6 Enhanced Control Strategies to Improve DFIG Fault Ride-Through Capabilities 622.6.1 The Two Degrees of Freedom Internal Model Control (IMC) 622.6.2 IMC Controller of the Rotor Speed 652.6.3 IMC Controller of the Rotor Currents 662.6.4 IMC Controller of the dc Voltage 672.6.5 IMC Controller of the Grid-Side Converter Currents 692.6.6 DFIG IMC Controllers Tuning for Attaining Robust Control 702.6.7 The Robust Stability Theorem 70References 723 Fully-Rated Converter Wind Turbine (FRC-WT) 733.1 Synchronous Machine Fundamentals 733.1.1 Synchronous Generator Construction 733.1.2 The Air-Gap Magnetic Field of the Synchronous Generator 743.2 Synchronous Generator Modelling in the dq Frame 793.2.1 Steady-State Operation 813.2.2 Synchronous Generator with Damper Windings 823.3 Control of Large Synchronous Generators 853.3.1 Excitation Control 863.3.2 Prime Mover Control 873.4 Fully-Rated Converter Wind Turbines 883.5 FRC-WT with Synchronous Generator 893.5.1 Permanent Magnets Synchronous Generator 903.5.2 FRC-WT Based on Permanent Magnet Synchronous Generator 923.5.3 Generator-Side Converter Control 933.5.4 Modelling of the dc Link 963.5.5 Network-Side Converter Control 983.6 FRC-WT with Squirrel-Cage Induction Generator 1003.6.1 Control of the FRC-IG Wind Turbine 1003.7 FRC-WT Power System Damper 1053.7.1 Power System Oscillations Damping Controller 1053.7.2 Influence of Wind Generation on Network Damping 1073.7.3 Influence of FRC-WT Damping Controller on Network Damping 108Acknowledgements 110References 1124 Offshore Wind Farm Electrical Systems 1134.1 Typical Components 1134.2 Wind Turbines for Offshore – General Aspects 1134.3 Electrical Collectors 1154.3.1 Wind Farm Clusters 1184.4 Offshore Transmission 1184.4.1 HVAC Transmission 1184.4.2 HVDC Transmission 1204.4.3 CSC-HVDC Transmission 1224.4.4 VSC-HVDC Transmission 1284.4.5 Multi-Terminal VSC-HVDC Networks 1404.5 Offshore Substations 1414.6 Reactive Power Compensation Equipment 1444.6.1 Static Var Compensator (SVC) 1444.6.2 Static Compensator (STATCOM) 1474.7 Subsea Cables 1504.7.1 Ac Subsea Cables 1504.7.2 Dc Subsea Cables 1504.7.3 Modelling of Underground and Subsea Cables 150Acknowledgements 151References 1515 Grid Integration of Offshore Wind Farms – Case Studies 1555.1 Background 1555.2 Offshore Wind Farm Connection Using Point-to-Point VSC-HVDC Transmission 1565.3 Offshore Wind Farm Connection Using HVAC Transmission 1595.4 Offshore Wind Farm Connected Using Parallel HVAC/VSC-HVDC Transmission 1615.5 Offshore Wind Farms Connected Using a Multi-Terminal VSC-HVDC Network 1645.6 Multi-Terminal VSC-HVDC for Connection of Inter-Regional Power Systems 168Acknowledgements 171References 1716 Offshore Wind Farm Protection 1736.1 Protection within the Wind Farm ac Network 1736.1.1 Wind Generator Protection Zone 1746.1.2 Feeder Protection Zone 1786.1.3 Busbar Protection Zone 1796.1.4 High-Voltage Transformer Protection Zone 1806.2 Study of Faults in the ac Transmission Line of an Offshore DFIG Wind Farm 1806.2.1 Case Study 1 1816.2.2 Case Study 2 1816.3 Protections for dc Connected Offshore Wind Farms 1846.3.1 VSC-HVDC Converter Protection Scheme 1846.3.2 Analysis of dc Transmission Line Fault 1856.3.3 Pole-to-Pole Faults 1866.3.4 Pole-to-Earth Fault 1876.3.5 HVDC dc Protections: Challenges and Trends 1886.3.6 Simulation Studies of Faults in the dc Transmission Line of an Offshore DFIG Wind Farm 188Acknowledgements 192References 1927 Emerging Technologies for Offshore Wind Integration 1937.1 Wind Turbine Advanced Control for Load Mitigation 1937.1.1 Blade Pitch Control 1937.1.2 Blade Twist Control 1947.1.3 Variable Diameter Rotor 1947.1.4 Active Flow Control 1957.2 Converter Interface Arrangements and Collector Design 1957.2.1 Converters on Turbine 1957.2.2 Converters on Platform 1987.2.3 Ac Collection Options: Fixed or Variable Frequency 2007.2.4 Evaluation of >Higher (>33 kV) Collection Voltage 2027.3 Dc Transmission Protection 2037.4 Energy Storage Systems (EESs) 2047.4.1 Batteries 2057.4.2 Super-Capacitors 2057.4.3 Flywheel Storage System 2057.4.4 Pumped-Hydro Storage 2067.4.5 Compressed-Air Storage Systems 2067.4.6 Superconducting Magnetic Energy Storage (SMES) 2067.5 Fault Current Limiters (FCLs) 2077.6 Sub-Sea Substations 2077.7 HTSCs, GITs and GILs 2087.7.1 HTSCs (High-Temperature Superconducting Cables) 2087.7.2 GITs (Gas-Insulated Transformers) 2087.7.3 GILs (Gas-Insulated Lines) 2097.8 Developments in Condition Monitoring 2097.8.1 Partial Discharge Monitoring in HV Cables 2097.8.2 Transformer Condition Monitoring 2107.8.3 Gas-Insulated Switchgear Condition Monitoring 2117.8.4 Power Electronics Condition Monitoring 2117.9 Smart Grids for Large-Scale Offshore Wind Integration 2137.9.1 VPP Control Approach 2167.9.2 Phasor Measurement Units 217Acknowledgements 217References 218Appendix A Voltage Source Converter Topologies 223A.1 Two-Level Converter 223A.1.1 Operation 223A.1.2 Voltage Source Converter Square-Mode Operation 224A.1.3 Pulse Width Modulation 225A.2 Neutral-Point Clamped Converter 240A.2.1 Selective Harmonic Elimination 242A.2.2 Sinusoidal Pulse Width Modulation 244A.3 Flying Capacitor (FC) Multilevel Converter 247A.4 Cascaded Multilevel Converter 248A.5 Modular Multilevel Converter 249References 258Appendix B Worked-out Examples 271Index 279

Edgar Lenymirko Moreno-Goytia, Reader, Instituto Tecnológico de Morelia, MéxicoDr Moreno-Goytia has researched power electronic-based equipment and measurement systems development. He designed and built a Thyristor Controlled Series Compensator and its control to operate in a voltage fluctuations environment, and has been involved in evaluating the impact of wind generation on the electrical grid. Dr Moreno-Goytia has published over thirty papers in international conferences and journals and is a member of IEEE and IET.Olimpo Anaya-Lara, Senior Lecturer, Institute for Energy and Environment , University of Strathclyde, Glasgow, UKDr Anaya-Lara has researched power electronic equipment, control systems development, and stability and control of power systems with increased wind energy penetration. He has developed control strategies for Flexible Alternating Current Transmission System devices (FACTS), and designed control schemes for marine applications using advanced control techniques. He is a member of the CIGRE Working Group B4-39, two International Energy Agency Annexes, also the IEEE and IET. He has published over thirty-five journals, ninety papers and co-authored three books.David Campos-Gaona, Research Assistant, Instituto Tecnológico de Morelia, MéxicoMr Campos-Gaona has investigated electronics-based solutions to electrical networks such as digital power meters, DSP based protection algorithms, and protection systems for wind turbines. He developed electronic equipment such as residential digital power meter with a wireless communication port. He was a research assistant with the SUPERGEN FlexNet, and is member of the IEEE. He  has published several papers and conference proceedings.Grain Philip Adam, Research Fellow, University of Strathclyde, Glasgow, UKGrain received a Ph.D. degree in power electronics from Strathclyde University in 2007. He is currently with the Department of Electronic and Electrical Engineering, Strathclyde University, and his research interests are multilevel inverters, electrical machines and power systems control and stability.

• Preface xi About the Authors xiiiAcronyms and Symbols xv1 Offshore Wind Energy Systems 11.1 Background 11.2 Typical Subsystems 11.3 Wind Turbine Technology 41.3.1 Basics 41.3.2 Architectures 61.3.3 Offshore Wind Turbine Technology Status 71.4 Offshore Transmission Networks 81.5 Impact on Power System Operation 91.5.1 Power System Dynamics and Stability 101.5.2 Reactive Power and Voltage Support 101.5.3 Frequency Support 111.5.4 Wind Turbine Inertial Response 111.6 Grid Code Regulations for the Connection of Wind Generation 12Acknowledgements 13References 142 DFIG Wind Turbine 152.1 Introduction 152.1.1 Induction Generator (IG) 152.1.2 Back-to-Back Converter 162.1.3 Gearbox 162.1.4 Crowbar Protection 162.1.5 Turbine Transformer 172.2 DFIG Architecture and Mathematical Modelling 172.2.1 IG in the abc Reference Frame 172.2.2 IG in the dq0 Reference Frame 232.2.3 Mechanical System 272.2.4 Crowbar Protection 292.2.5 Modelling of the DFIG B2B Power Converter 302.2.6 Average Modelling of Power Electronic Converters 332.2.7 The dc Circuit 352.3 Control of the DFIG WT 362.3.1 PI Control of Rotor Speed 362.3.2 PI Control of DFIG Reactive Power 392.3.3 PI Control of Rotor Currents 412.3.4 PI Control of dc Voltage 422.3.5 PI Control of Grid-side Converter Currents 452.4 DFIG Dynamic Performance Assessment 472.4.1 Three-phase Fault 472.4.2 Symmetrical Voltage Dips 512.4.3 Asymmetrical Faults 532.4.4 Single-Phase-to-Ground Fault 542.4.5 Phase-to-Phase Fault 552.4.6 Torque Behaviour under Symmetrical Faults 562.4.7 Torque Behaviour under Asymmetrical Faults 582.4.8 Effects of Faults in the Reactive Power Consumption of the IG 592.5 Fault Ride-Through Capabilities and Grid Code Compliance 602.5.1 Advantages and Disadvantages of the Crowbar Protection 602.5.2 Effects of DFIG Variables over Its Fault Ride-Through Capabilities 612.6 Enhanced Control Strategies to Improve DFIG Fault Ride-Through Capabilities 622.6.1 The Two Degrees of Freedom Internal Model Control (IMC) 622.6.2 IMC Controller of the Rotor Speed 652.6.3 IMC Controller of the Rotor Currents 662.6.4 IMC Controller of the dc Voltage 672.6.5 IMC Controller of the Grid-Side Converter Currents 692.6.6 DFIG IMC Controllers Tuning for Attaining Robust Control 702.6.7 The Robust Stability Theorem 70References 723 Fully-Rated Converter Wind Turbine (FRC-WT) 733.1 Synchronous Machine Fundamentals 733.1.1 Synchronous Generator Construction 733.1.2 The Air-Gap Magnetic Field of the Synchronous Generator 743.2 Synchronous Generator Modelling in the dq Frame 793.2.1 Steady-State Operation 813.2.2 Synchronous Generator with Damper Windings 823.3 Control of Large Synchronous Generators 853.3.1 Excitation Control 863.3.2 Prime Mover Control 873.4 Fully-Rated Converter Wind Turbines 883.5 FRC-WT with Synchronous Generator 893.5.1 Permanent Magnets Synchronous Generator 903.5.2 FRC-WT Based on Permanent Magnet Synchronous Generator 923.5.3 Generator-Side Converter Control 933.5.4 Modelling of the dc Link 963.5.5 Network-Side Converter Control 983.6 FRC-WT with Squirrel-Cage Induction Generator 1003.6.1 Control of the FRC-IG Wind Turbine 1003.7 FRC-WT Power System Damper 1053.7.1 Power System Oscillations Damping Controller 1053.7.2 Influence of Wind Generation on Network Damping 1073.7.3 Influence of FRC-WT Damping Controller on Network Damping 108Acknowledgements 110References 1124 Offshore Wind Farm Electrical Systems 1134.1 Typical Components 1134.2 Wind Turbines for Offshore – General Aspects 1134.3 Electrical Collectors 1154.3.1 Wind Farm Clusters 1184.4 Offshore Transmission 1184.4.1 HVAC Transmission 1184.4.2 HVDC Transmission 1204.4.3 CSC-HVDC Transmission 1224.4.4 VSC-HVDC Transmission 1284.4.5 Multi-Terminal VSC-HVDC Networks 1404.5 Offshore Substations 1414.6 Reactive Power Compensation Equipment 1444.6.1 Static Var Compensator (SVC) 1444.6.2 Static Compensator (STATCOM) 1474.7 Subsea Cables 1504.7.1 Ac Subsea Cables 1504.7.2 Dc Subsea Cables 1504.7.3 Modelling of Underground and Subsea Cables 150Acknowledgements 151References 1515 Grid Integration of Offshore Wind Farms – Case Studies 1555.1 Background 1555.2 Offshore Wind Farm Connection Using Point-to-Point VSC-HVDC Transmission 1565.3 Offshore Wind Farm Connection Using HVAC Transmission 1595.4 Offshore Wind Farm Connected Using Parallel HVAC/VSC-HVDC Transmission 1615.5 Offshore Wind Farms Connected Using a Multi-Terminal VSC-HVDC Network 1645.6 Multi-Terminal VSC-HVDC for Connection of Inter-Regional Power Systems 168Acknowledgements 171References 1716 Offshore Wind Farm Protection 1736.1 Protection within the Wind Farm ac Network 1736.1.1 Wind Generator Protection Zone 1746.1.2 Feeder Protection Zone 1786.1.3 Busbar Protection Zone 1796.1.4 High-Voltage Transformer Protection Zone 1806.2 Study of Faults in the ac Transmission Line of an Offshore DFIG Wind Farm 1806.2.1 Case Study 1 1816.2.2 Case Study 2 1816.3 Protections for dc Connected Offshore Wind Farms 1846.3.1 VSC-HVDC Converter Protection Scheme 1846.3.2 Analysis of dc Transmission Line Fault 1856.3.3 Pole-to-Pole Faults 1866.3.4 Pole-to-Earth Fault 1876.3.5 HVDC dc Protections: Challenges and Trends 1886.3.6 Simulation Studies of Faults in the dc Transmission Line of an Offshore DFIG Wind Farm 188Acknowledgements 192References 1927 Emerging Technologies for Offshore Wind Integration 1937.1 Wind Turbine Advanced Control for Load Mitigation 1937.1.1 Blade Pitch Control 1937.1.2 Blade Twist Control 1947.1.3 Variable Diameter Rotor 1947.1.4 Active Flow Control 1957.2 Converter Interface Arrangements and Collector Design 1957.2.1 Converters on Turbine 1957.2.2 Converters on Platform 1987.2.3 Ac Collection Options: Fixed or Variable Frequency 2007.2.4 Evaluation of >Higher (>33 kV) Collection Voltage 2027.3 Dc Transmission Protection 2037.4 Energy Storage Systems (EESs) 2047.4.1 Batteries 2057.4.2 Super-Capacitors 2057.4.3 Flywheel Storage System 2057.4.4 Pumped-Hydro Storage 2067.4.5 Compressed-Air Storage Systems 2067.4.6 Superconducting Magnetic Energy Storage (SMES) 2067.5 Fault Current Limiters (FCLs) 2077.6 Sub-Sea Substations 2077.7 HTSCs, GITs and GILs 2087.7.1 HTSCs (High-Temperature Superconducting Cables) 2087.7.2 GITs (Gas-Insulated Transformers) 2087.7.3 GILs (Gas-Insulated Lines) 2097.8 Developments in Condition Monitoring 2097.8.1 Partial Discharge Monitoring in HV Cables 2097.8.2 Transformer Condition Monitoring 2107.8.3 Gas-Insulated Switchgear Condition Monitoring 2117.8.4 Power Electronics Condition Monitoring 2117.9 Smart Grids for Large-Scale Offshore Wind Integration 2137.9.1 VPP Control Approach 2167.9.2 Phasor Measurement Units 217Acknowledgements 217References 218Appendix A Voltage Source Converter Topologies 223A.1 Two-Level Converter 223A.1.1 Operation 223A.1.2 Voltage Source Converter Square-Mode Operation 224A.1.3 Pulse Width Modulation 225A.2 Neutral-Point Clamped Converter 240A.2.1 Selective Harmonic Elimination 242A.2.2 Sinusoidal Pulse Width Modulation 244A.3 Flying Capacitor (FC) Multilevel Converter 247A.4 Cascaded Multilevel Converter 248A.5 Modular Multilevel Converter 249References 258Appendix B Worked-out Examples 271Index 279