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This book presents a modified model reference adaptive system (MRAS) observer for sensorless vector control of a wind driven doubly fed induction generator (DFIG). A mathematical model of the DFIG as influenced by core loss and main flux saturation is developed. The authors describe and evaluate grid synchronization enhancement of a wind driven DFIG using adaptive sliding mode control (SMC). Besides, grid synchronization of a wind driven DFIG under unbalanced grid voltage is also fully covered in this book.

Wind Driven Doubly Fed Induction Generator: Grid Synchronization and Control

2.1. Introduction 2.2. Synchronous Generators Driven by a Fixed Speed Turbine ...2.2.1. Wound Field Synchronous Generator Driven by a Wind Turbine ..2.2.2. Permanent-Magnet Synchronous Generator (PMSG) Driven by a Wind Turbine 2.3. Induction Generators Driven by a Variable Speed Wind Turbine ..2.3.1. Squirrel Cage Induction Generator (SCIG) Driven by a Wind Turbine ...2.3.2. Doubly Fed Induction Generator (DFIG) Driven by a Wind Turbine 2.3.2.1. operation modes ..........................................................................2.4. Modeling of a Wind Turbine Generator System ..........................2.4.1. Aerodynamic modeling ....................................2.4.2. Drive train modeling .........................2.4.3. DFIG modeling .....................................2.4.4. Power converter modeling ...................2.5. Control Strategies for a Wind Turbine Generator System ............2.5.1. Pitch angle control ..........2.5.2. Maximum power point tracking control..............2.5.2.1. conventional control schemes ................2.5.2.2. intelligent control ..........2.5.2.3. Other control strategies ..............2.5.3. DFIG control2.5.3.1. field oriented control ................2.5.3.2. Direct torque/power control ...........2.5.3.3. Other control strategies .....................2.6. Power Converter Topologies for a Wind Turbine Generator System ................2.6.1. multi-level converters ...2.6.2. Matrix converters ...............2.7. DFIG Grid Synchronization ..............Chapter 3 .....................................A Modified MRAS Observer for Sensorless Control of a Wind Driven DFIG Connected to Grid ....................3.1. Introduction ..............................................3.2. Description of The System Under Study ..............................3.3. Dynamic Modeling of a Wind Turbine DFIG System ............3.3.1. Aerodynamic wind turbine model .....................................3.3.2. Dynamic Model of a DFIG Taking Iron Losses and Magnetic Saturation into Consideration 3.3.3. DC link model ........................3.4. Vector Control of a DFIG for Grid connected Operations ....3.5. Speed Estimation Based on the Modified MRAS Observer ..............3.6. Configuration of Complete System .......................3.7. Results and Discussions ................................................Chapter 4 ..................................................Grid Synchronization Enhancement of a Wind Driven DFIG Using Adaptive Sliding Mode Control 4.1. Introduction ...............4.2. Description of the DFIG System ..............4.3. Dynamic Model of a DFIG Taking Iron Losses into Consideration ...........4.4. Direct relationship between stator voltage and rotor voltage .............4.4.1. External disturbances and parametric uncertainty ..................4.5. Design of Proposed Adaptive Sliding Mode Control...............4.6. Complete System of a Wind Generation with Proposed SMCChapter 5 ...........................................Adaptive Sliding Mode Control for Grid Synchronization of a Wind Driven DFIG under Unbalanced Grid Voltage 5.1. Introduction ............5.2. DFIG Model during Grid Synchronization under Unbalanced Grid Voltage ........ 805.3. Positive Sequence Controller Design ..................................................................... 835.3.1. Controlled plant analysis ................................................................................. 835.3.2. Direct relationship between positive sequence stator and rotor voltages ........ 855.3.3. Parametric uncertainty ..................................................................................... 865.3.4. Adaptive sliding mode control design ............................................................. 875.4. Negative Sequence Controller Design ................................................................... 925.5. Configuration of the Complete Control Scheme .................................................... 935.6. Results and Discussions ......................................................................................... 96Chapter 6 ......................................................................................................................... 114Conclusions and suggestions for Future Work ...............................................................