Offshore Wind Energy Generation -- Contents -- Preface -- About the Authors -- Acronyms and Symbols -- 1 Offshore Wind Energy Systems -- 1.1 Background -- 1.2 Typical Subsystems -- 1.3 Wind Turbine Technology -- 1.3.1 Basics -- 1.3.2 Architectures -- 1.3.3 Offshore Wind Turbine Technology Status -- 1.4 Offshore Transmission Networks -- 1.5 Impact on Power System Operation -- 1.5.1 Power System Dynamics and Stability -- 1.5.2 Reactive Power and Voltage Support -- 1.5.3 Frequency Support -- 1.5.4 Wind Turbine Inertial Response -- 1.6 Grid Code Regulations for the Connection of Wind Generation -- Acknowledgement -- References -- 2 DFIG Wind Turbine -- 2.1 Introduction -- 2.1.1 Induction Generator (IG) -- 2.1.2 Back-to-Back Converter -- 2.1.3 Gearbox -- 2.1.4 Crowbar Protection -- 2.1.5 Turbine Transformer -- 2.2 DFIG Architecture and Mathematical Modelling -- 2.2.1 IG in the abc Reference Frame -- 2.2.2 IG in the dq0 Reference Frame -- 2.2.3 Mechanical System -- 2.2.4 Crowbar Protection -- 2.2.5 Modelling of the DFIG B2B Power Converter -- 2.2.6 Average Modelling of Power Electronic Converters -- 2.2.7 The dc Circuit -- 2.3 Control of the DFIG WT -- 2.3.1 PI Control of Rotor Speed -- 2.3.2 PI Control of DFIG Reactive Power -- 2.3.3 PI Control of Rotor Currents -- 2.3.4 PI Control of dc Voltage -- 2.3.5 PI Control of Grid-side Converter Currents -- 2.4 DFIG Dynamic Performance Assessment -- 2.4.1 Three-phase Fault -- 2.4.2 Symmetrical Voltage Dips -- 2.4.3 Asymmetrical Faults -- 2.4.4 Single-Phase-to-Ground Fault -- 2.4.5 Phase-to-Phase Fault -- 2.4.6 Torque Behaviour under Symmetrical Faults -- 2.4.7 Torque Behaviour under Asymmetrical Faults -- 2.4.8 Effects of Faults in the Reactive Power Consumption of the IG -- 2.5 Fault Ride-Through Capabilities and Grid Code Compliance -- 2.5.1 Advantages and Disadvantages of the Crowbar Protection.

2.5.2 Effects of DFIG Variables over Its Fault Ride-Through Capabilities -- 2.6 Enhanced Control Strategies to Improve DFIG Fault Ride-Through Capabilities -- 2.6.1 The Two Degrees of Freedom Internal Model Control (IMC) -- 2.6.2 IMC Controller of the Rotor Speed -- 2.6.3 IMC Controller of the Rotor Currents -- 2.6.4 IMC Controller of the dc Voltage -- 2.6.5 IMC Controller of the Grid-Side Converter Currents -- 2.6.6 DFIG IMC Controllers Tuning for Attaining Robust Control -- 2.6.7 The Robust Stability Theorem -- References -- 3 Fully-Rated Converter Wind Turbine (FRC-WT) -- 3.1 Synchronous Machine Fundamentals -- 3.1.1 Synchronous Generator Construction -- 3.1.2 The Air-Gap Magnetic Field of the Synchronous Generator -- 3.2 Synchronous Generator Modelling in the dq Frame -- 3.2.1 Steady-State Operation -- 3.2.2 Synchronous Generator with Damper Windings -- 3.3 Control of Large Synchronous Generators -- 3.3.1 Excitation Control -- 3.3.2 Prime Mover Control -- 3.4 Fully-Rated Converter Wind Turbines -- 3.5 FRC-WT with Synchronous Generator -- 3.5.1 Permanent Magnets Synchronous Generator -- 3.5.2 FRC-WT Based on Permanent Magnet Synchronous Generator -- 3.5.3 Generator-Side Converter Control -- 3.5.4 Modelling of the dc Link -- 3.5.5 Network-Side Converter Control -- 3.6 FRC-WT with Squirrel-Cage Induction Generator -- 3.6.1 Control of the FRC-IG Wind Turbine -- 3.7 FRC-WT Power System Damper -- 3.7.1 Power System Oscillations Damping Controller -- 3.7.2 Influence of Wind Generation on Network Damping -- 3.7.3 Influence of FRC-WT Damping Controller on Network Damping -- Acknowledgements -- References -- 4 Offshore Wind Farm Electrical Systems -- 4.1 Typical Components -- 4.2 Wind Turbines for Offshore - General Aspects -- 4.3 Electrical Collectors -- 4.3.1 Wind Farm Clusters -- 4.4 Offshore Transmission -- 4.4.1 HVAC Transmission.

4.4.2 HVDC Transmission -- 4.4.3 CSC-HVDC Transmission -- 4.4.4 VSC-HVDC Transmission -- 4.4.5 Multi-Terminal VSC-HVDC Networks -- 4.5 Offshore Substations -- 4.6 Reactive Power Compensation Equipment -- 4.6.1 Static Var Compensator (SVC) -- 4.6.2 Static Compensator (STATCOM) -- 4.7 Subsea Cables -- 4.7.1 Ac Subsea Cables -- 4.7.2 Dc Subsea Cables -- 4.7.3 Modelling of Underground and Subsea Cables -- Acknowledgements -- References -- 5 Grid Integration of Offshore Wind Farms - Case Studies -- 5.1 Background -- 5.2 Offshore Wind Farm Connection Using Point-to-Point VSC-HVDC Transmission -- 5.3 Offshore Wind Farm Connection Using HVAC Transmission -- 5.4 Offshore Wind Farm Connected Using Parallel HVAC/VSC-HVDC Transmission -- 5.5 Offshore Wind Farms Connected Using a Multi-Terminal VSC-HVDC Network -- 5.6 Multi-Terminal VSC-HVDC for Connection of Inter-Regional Power Systems -- Acknowledgements -- References -- 6 Offshore Wind Farm Protection -- 6.1 Protection within the Wind Farm ac Network -- 6.1.1 Wind Generator Protection Zone -- 6.1.2 Feeder Protection Zone -- 6.1.3 Busbar Protection Zone -- 6.1.4 High-Voltage Transformer Protection Zone -- 6.2 Study of Faults in the ac Transmission Line of an Offshore DFIG Wind Farm -- 6.2.1 Case Study 1 -- 6.2.2 Case Study 2 -- 6.3 Protections for dc Connected Offshore Wind Farms -- 6.3.1 VSC-HVDC Converter Protection Scheme -- 6.3.2 Analysis of dc Transmission Line Fault -- 6.3.3 Pole-to-Pole Faults -- 6.3.4 Pole-to-Earth Fault -- 6.3.5 HVDC dc Protections: Challenges and Trends -- 6.3.6 Simulation Studies of Faults in the dc Transmission Line of an Offshore DFIG Wind Farm -- Acknowledgements -- References -- 7 Emerging Technologies for Offshore Wind Integration -- 7.1 Wind Turbine Advanced Control for Load Mitigation -- 7.1.1 Blade Pitch Control -- 7.1.2 Blade Twist Control -- 7.1.3 Variable Diameter Rotor.

7.1.4 Active Flow Control -- 7.2 Converter Interface Arrangements and Collector Design -- 7.2.1 Converters on Turbine -- 7.2.2 Converters on Platform -- 7.2.3 Ac Collection Options: Fixed or Variable Frequency -- 7.2.4 Evaluation of >Higher (>33 kV) Collection Voltage -- 7.3 Dc Transmission Protection -- 7.4 Energy Storage Systems (EESs) -- 7.4.1 Batteries -- 7.4.2 Super-Capacitors -- 7.4.3 Flywheel Storage System -- 7.4.4 Pumped-Hydro Storage -- 7.4.5 Compressed-Air Storage Systems -- 7.4.6 Superconducting Magnetic Energy Storage (SMES) -- 7.5 Fault Current Limiters (FCLs) -- 7.6 Sub-Sea Substations -- 7.7 HTSCs, GITs and GILs -- 7.7.1 HTSCs (High-Temperature Superconducting Cables) -- 7.7.2 GITs (Gas-Insulated Transformers) -- 7.7.3 GILs (Gas-Insulated Lines) -- 7.8 Developments in Condition Monitoring -- 7.8.1 Partial Discharge Monitoring in HV Cables -- 7.8.2 Transformer Condition Monitoring -- 7.8.3 Gas-Insulated Switchgear Condition Monitoring -- 7.8.4 Power Electronics Condition Monitoring -- 7.9 Smart Grids for Large-Scale Offshore Wind Integration -- 7.9.1 VPP Control Approach -- 7.9.2 Phasor Measurement Units -- Acknowledgements -- References -- A Voltage Source Converter Topologies -- A.1 Two-Level Converter -- A.1.1 Operation -- A.1.2 Voltage Source Converter Square-Mode Operation -- A.1.3 Pulse Width Modulation -- A.2 Neutral-Point Clamped Converter -- A.2.1 Selective Harmonic Elimination -- A.2.2 Sinusoidal Pulse Width Modulation -- A.3 Flying Capacitor (FC) Multilevel Converter -- A.4 Cascaded Multilevel Converter -- A.5 Modular Multilevel Converter -- References -- B Worked-out Examples -- Exercise 1 -- Exercise 2 -- Exercise 3 -- Exercise 4 -- Exercise 5 -- Exercise 6 -- Index -- OFFSHORE WINDENERGY GENERATIONCONTROL, PROTECTION, ANDINTEGRATION TO ELECTRICALSYSTEMS.