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Wind Energy Systems: Modeling, Analysis and Control with DFIG provides key information on machine/converter modelling strategies based on space vectors, complex vector, and further frequency-domain variables. It includes applications that focus on wind energy grid integration, with analysis and control explanations with examples. For those working in the field of wind energy integration examining the potential risk of stability is key, this edition looks at how wind energy is modelled, what kind of control systems are adopted, how it interacts with the grid, as well as suitable study approaches. Not only giving principles behind the dynamics of wind energy grid integration system, but also examining different strategies for analysis, such as frequency-domain-based and state-space-based approaches. Focuses on real and reactive power control Supported by PSCAD and Matlab/Simulink examples Considers the difference in control objectives between ac drive systems and grid integration systems
Book Synopsis Modeling and Analysis of Doubly Fed Induction Generator Wind Energy Systems by : Lingling Fan
Download or read book Modeling and Analysis of Doubly Fed Induction Generator Wind Energy Systems written by Lingling Fan and published by Academic Press. This book was released on 2015-04-16 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind Energy Systems: Modeling, Analysis and Control with DFIG provides key information on machine/converter modelling strategies based on space vectors, complex vector, and further frequency-domain variables. It includes applications that focus on wind energy grid integration, with analysis and control explanations with examples. For those working in the field of wind energy integration examining the potential risk of stability is key, this edition looks at how wind energy is modelled, what kind of control systems are adopted, how it interacts with the grid, as well as suitable study approaches. Not only giving principles behind the dynamics of wind energy grid integration system, but also examining different strategies for analysis, such as frequency-domain-based and state-space-based approaches. Focuses on real and reactive power control Supported by PSCAD and Matlab/Simulink examples Considers the difference in control objectives between ac drive systems and grid integration systems
Covers the fundamental concepts and advanced modelling techniques of Doubly Fed Induction Generators accompanied by analyses and simulation results Filled with illustrations, problems, models, analyses, case studies, selected simulation and experimental results, Advanced Control of Doubly Fed Induction Generator for Wind Power Systems provides the basic concepts for modelling and controlling of Doubly Fed Induction Generator (DFIG) wind power systems and their power converters. It explores both the challenges and concerns of DFIG under a non-ideal grid and introduces the control strategies and effective operations performance options of DFIG under a non-ideal grid. Other topics of this book include thermal analysis of DFIG wind power converters under grid faults; implications of the DFIG test bench; advanced control of DFIG under harmonic distorted grid voltage, including multiple-loop and resonant control; modeling of DFIG and GSC under unbalanced grid voltage; the LFRT of DFIG, including the recurring faults ride through of DFIG; and more. In addition, this resource: Explores the challenges and concerns of Doubly Fed Induction Generators (DFIG) under non-ideal grid Discusses basic concepts of DFIG wind power system and vector control schemes of DFIG Introduces control strategies under a non-ideal grid Includes case studies and simulation and experimental results Advanced Control of Doubly Fed Induction Generator for Wind Power Systems is an ideal book for graduate students studying renewable energy and power electronics as well as for research and development engineers working with wind power converters.
Book Synopsis Advanced Control of Doubly Fed Induction Generator for Wind Power Systems by : Dehong Xu
Download or read book Advanced Control of Doubly Fed Induction Generator for Wind Power Systems written by Dehong Xu and published by John Wiley & Sons. This book was released on 2018-08-14 with total page 486 pages. Available in PDF, EPUB and Kindle. Book excerpt: Covers the fundamental concepts and advanced modelling techniques of Doubly Fed Induction Generators accompanied by analyses and simulation results Filled with illustrations, problems, models, analyses, case studies, selected simulation and experimental results, Advanced Control of Doubly Fed Induction Generator for Wind Power Systems provides the basic concepts for modelling and controlling of Doubly Fed Induction Generator (DFIG) wind power systems and their power converters. It explores both the challenges and concerns of DFIG under a non-ideal grid and introduces the control strategies and effective operations performance options of DFIG under a non-ideal grid. Other topics of this book include thermal analysis of DFIG wind power converters under grid faults; implications of the DFIG test bench; advanced control of DFIG under harmonic distorted grid voltage, including multiple-loop and resonant control; modeling of DFIG and GSC under unbalanced grid voltage; the LFRT of DFIG, including the recurring faults ride through of DFIG; and more. In addition, this resource: Explores the challenges and concerns of Doubly Fed Induction Generators (DFIG) under non-ideal grid Discusses basic concepts of DFIG wind power system and vector control schemes of DFIG Introduces control strategies under a non-ideal grid Includes case studies and simulation and experimental results Advanced Control of Doubly Fed Induction Generator for Wind Power Systems is an ideal book for graduate students studying renewable energy and power electronics as well as for research and development engineers working with wind power converters.
This book will be focused on the modeling and control of the DFIM based wind turbines. In the first part of the book, the mathematical description of different basic dynamic models of the DFIM will be carried out. It will be accompanied by a detailed steady-state analysis of the machine. After that, a more sophisticated model of the machine that considers grid disturbances, such as voltage dips and unbalances will be also studied. The second part of the book surveys the most relevant control strategies used for the DFIM when it operates at the wind energy generation application. The control techniques studied, range from standard solutions used by wind turbine manufacturers, to the last developments oriented to improve the behavior of high power wind turbines, as well as control and hardware based solutions to address different faulty scenarios of the grid. In addition, the standalone DFIM generation system will be also analyzed.
Book Synopsis Doubly Fed Induction Machine by : Gonzalo Abad
Download or read book Doubly Fed Induction Machine written by Gonzalo Abad and published by Wiley-IEEE Press. This book was released on 2011-11-01 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will be focused on the modeling and control of the DFIM based wind turbines. In the first part of the book, the mathematical description of different basic dynamic models of the DFIM will be carried out. It will be accompanied by a detailed steady-state analysis of the machine. After that, a more sophisticated model of the machine that considers grid disturbances, such as voltage dips and unbalances will be also studied. The second part of the book surveys the most relevant control strategies used for the DFIM when it operates at the wind energy generation application. The control techniques studied, range from standard solutions used by wind turbine manufacturers, to the last developments oriented to improve the behavior of high power wind turbines, as well as control and hardware based solutions to address different faulty scenarios of the grid. In addition, the standalone DFIM generation system will be also analyzed.
This book will be focused on the modeling and control of the DFIM based wind turbines. In the first part of the book, the mathematical description of different basic dynamic models of the DFIM will be carried out. It will be accompanied by a detailed steady-state analysis of the machine. After that, a more sophisticated model of the machine that considers grid disturbances, such as voltage dips and unbalances will be also studied. The second part of the book surveys the most relevant control strategies used for the DFIM when it operates at the wind energy generation application. The control techniques studied, range from standard solutions used by wind turbine manufacturers, to the last developments oriented to improve the behavior of high power wind turbines, as well as control and hardware based solutions to address different faulty scenarios of the grid. In addition, the standalone DFIM generation system will be also analyzed.
Book Synopsis Doubly Fed Induction Machine by : Gonzalo Abad
Download or read book Doubly Fed Induction Machine written by Gonzalo Abad and published by John Wiley & Sons. This book was released on 2011-09-28 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book will be focused on the modeling and control of the DFIM based wind turbines. In the first part of the book, the mathematical description of different basic dynamic models of the DFIM will be carried out. It will be accompanied by a detailed steady-state analysis of the machine. After that, a more sophisticated model of the machine that considers grid disturbances, such as voltage dips and unbalances will be also studied. The second part of the book surveys the most relevant control strategies used for the DFIM when it operates at the wind energy generation application. The control techniques studied, range from standard solutions used by wind turbine manufacturers, to the last developments oriented to improve the behavior of high power wind turbines, as well as control and hardware based solutions to address different faulty scenarios of the grid. In addition, the standalone DFIM generation system will be also analyzed.
Advanced Controls for Wind Driven Doubly Fed Induction Generators discusses the most advanced control algorithms used for enhancing the dynamics of a doubly fed induction generator (DFIG) operating at fixed and variable speeds, and which are used for different utilization purposes (standalone and grid connection). Extensive generator performance analysis has been introduced using various control topologies. Features: Presents modeling of wind energy conversion systems (WECS), including a wind turbine as a prime mover, a DFIG as a generation unit for electrical energy, and a three-phase induction motor as an isolated load Explores a detailed description for the presented control algorithms in order to visualize the base principle of each method Introduces a comprehensive performance analysis for the DFIG using the formulated predictive voltage control scheme and other control techniques under different operating conditions Examines the formulation of new control approaches which overcome the shortages present in previous DFIG control schemes Presents a detailed comparison between different control topologies for the DFIG to outline the most effective procedure in terms of dynamic response, structure simplicity, ripples, total harmonic distortion, and computational burdens The book is written for researchers and academics working on advanced control systems and those interested in areas such as machine drives, renewable energy systems, 'adaptive control', modeling of WECS, and optimization theory.
Book Synopsis Advanced Controls for Wind Driven Doubly Fed Induction Generators by : Mahmoud K. Abdelhamid
Download or read book Advanced Controls for Wind Driven Doubly Fed Induction Generators written by Mahmoud K. Abdelhamid and published by CRC Press. This book was released on 2023-12-22 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advanced Controls for Wind Driven Doubly Fed Induction Generators discusses the most advanced control algorithms used for enhancing the dynamics of a doubly fed induction generator (DFIG) operating at fixed and variable speeds, and which are used for different utilization purposes (standalone and grid connection). Extensive generator performance analysis has been introduced using various control topologies. Features: Presents modeling of wind energy conversion systems (WECS), including a wind turbine as a prime mover, a DFIG as a generation unit for electrical energy, and a three-phase induction motor as an isolated load Explores a detailed description for the presented control algorithms in order to visualize the base principle of each method Introduces a comprehensive performance analysis for the DFIG using the formulated predictive voltage control scheme and other control techniques under different operating conditions Examines the formulation of new control approaches which overcome the shortages present in previous DFIG control schemes Presents a detailed comparison between different control topologies for the DFIG to outline the most effective procedure in terms of dynamic response, structure simplicity, ripples, total harmonic distortion, and computational burdens The book is written for researchers and academics working on advanced control systems and those interested in areas such as machine drives, renewable energy systems, 'adaptive control', modeling of WECS, and optimization theory.
Wind power penetration is rapidly increasing in today's energy generation industry. In particular, the doubly-fed induction generator (DFIG) has become a very popular option in wind farms, due to its cost advantage compared with fully rated converter-based systems. Wind farms are frequently located in remote areas, far from the bulk of electric power users, and require long transmission lines to connect to the grid. Series capacitive compensation of DFIG-based wind farm is an economical way to increase the power transfer capability of the transmission line connecting the wind farm to the grid. For example, a study performed by ABB reveals that increasing the power transfer capability of an existing transmission line from 1300 MW to 2000 MW using series compensation is 90% less expensive than building a new transmission line. However, a factor hindering the extensive use of series capacitive compensation is the potential risk of subsynchronous resonance (SSR). The SSR is a condition where the wind farm exchanges energy with the electric network, to which it is connected, at one or more natural frequencies of the electric or mechanical part of the combined system, comprising the wind farm and the network, and the frequency of the exchanged energy is below the fundamental frequency of the system. This oscillatory phenomenon may cause severe damage in the wind farm, if not prevented. Therefore, this book studies the SSR phenomenon in a capacitive series compensated wind farm. A DFIG-based wind farm, which is connected to a series compensated transmission line, is considered as a case study. The book consists of two main parts: Small-signal modeling of DFIG for SSR analysis: This part presents a step-by-step tutorial on modal analysis of a DFIG-based series compensated wind farm using Matlab/Simulink. The model of the system includes wind turbine aerodynamics, a 6th order induction generator, a 2nd order two-mass shaft system, a 4th order series compensated transmission line, a 4th order rotor-side converter (RSC) controller and a 4th order grid-side converter (GSC) controller, and a 1st order DC-link model. The relevant modes are identified using participation factor analysis. Definition of the SSR in DFIG-based wind farms: This part mainly focuses on the identification and definition of the main types of SSR that occur in DFIG wind farms, namely: (1) induction generator effect (SSIGE), (2) torsional interactions (SSTI), and (3) control interactions (SSCI).
Book Synopsis Analysis of Sub-synchronous Resonance (SSR) in Doubly-fed Induction Generator (DFIG)-Based Wind Farms by : Hossein Ali Mohammadpour
Download or read book Analysis of Sub-synchronous Resonance (SSR) in Doubly-fed Induction Generator (DFIG)-Based Wind Farms written by Hossein Ali Mohammadpour and published by Springer Nature. This book was released on 2022-05-31 with total page 62 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wind power penetration is rapidly increasing in today's energy generation industry. In particular, the doubly-fed induction generator (DFIG) has become a very popular option in wind farms, due to its cost advantage compared with fully rated converter-based systems. Wind farms are frequently located in remote areas, far from the bulk of electric power users, and require long transmission lines to connect to the grid. Series capacitive compensation of DFIG-based wind farm is an economical way to increase the power transfer capability of the transmission line connecting the wind farm to the grid. For example, a study performed by ABB reveals that increasing the power transfer capability of an existing transmission line from 1300 MW to 2000 MW using series compensation is 90% less expensive than building a new transmission line. However, a factor hindering the extensive use of series capacitive compensation is the potential risk of subsynchronous resonance (SSR). The SSR is a condition where the wind farm exchanges energy with the electric network, to which it is connected, at one or more natural frequencies of the electric or mechanical part of the combined system, comprising the wind farm and the network, and the frequency of the exchanged energy is below the fundamental frequency of the system. This oscillatory phenomenon may cause severe damage in the wind farm, if not prevented. Therefore, this book studies the SSR phenomenon in a capacitive series compensated wind farm. A DFIG-based wind farm, which is connected to a series compensated transmission line, is considered as a case study. The book consists of two main parts: Small-signal modeling of DFIG for SSR analysis: This part presents a step-by-step tutorial on modal analysis of a DFIG-based series compensated wind farm using Matlab/Simulink. The model of the system includes wind turbine aerodynamics, a 6th order induction generator, a 2nd order two-mass shaft system, a 4th order series compensated transmission line, a 4th order rotor-side converter (RSC) controller and a 4th order grid-side converter (GSC) controller, and a 1st order DC-link model. The relevant modes are identified using participation factor analysis. Definition of the SSR in DFIG-based wind farms: This part mainly focuses on the identification and definition of the main types of SSR that occur in DFIG wind farms, namely: (1) induction generator effect (SSIGE), (2) torsional interactions (SSTI), and (3) control interactions (SSCI).
Recently, wind electrical power systems are getting a lot of attention since they are cost competitive, environmentally clean, and safe renewable power source as compared with the fossil fuel and nuclear power generation. A special type of induction generator, called a doubly fed induction generator (DFIG), is used extensively for high-power wind applications. They are used more and more in wind turbine applications due to the ease of controllability, the high energy efficiency, and the improved power quality.This research aims to develop a method of a field orientation scheme for control both, the active and the reactive powers of a DFIG that are driven by a wind turbine. Also, the dynamic model of the DFIG, driven by a wind turbine during grid faults, is analyzed and developed, using the method of symmetrical components. Finally, this study proposes a novel fault ride-through (FRT) capability with a suitable control strategy (i.e. the ability of the power system to remain connected to the grid during faults).
Book Synopsis Modeling, Analysis and Enhancement of the performance of a Wind Driven DFIG During steady state and transient conditions by : Mohmoud Mossa
Download or read book Modeling, Analysis and Enhancement of the performance of a Wind Driven DFIG During steady state and transient conditions written by Mohmoud Mossa and published by Anchor Academic Publishing (aap_verlag). This book was released on 2014-02-01 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recently, wind electrical power systems are getting a lot of attention since they are cost competitive, environmentally clean, and safe renewable power source as compared with the fossil fuel and nuclear power generation. A special type of induction generator, called a doubly fed induction generator (DFIG), is used extensively for high-power wind applications. They are used more and more in wind turbine applications due to the ease of controllability, the high energy efficiency, and the improved power quality.This research aims to develop a method of a field orientation scheme for control both, the active and the reactive powers of a DFIG that are driven by a wind turbine. Also, the dynamic model of the DFIG, driven by a wind turbine during grid faults, is analyzed and developed, using the method of symmetrical components. Finally, this study proposes a novel fault ride-through (FRT) capability with a suitable control strategy (i.e. the ability of the power system to remain connected to the grid during faults).
Doubly Fed Induction Generators: Control for Wind Energy provides a detailed source of information on the modeling and design of controllers for the doubly fed induction generator (DFIG) used in wind energy applications. Focusing on the use of nonlinear control techniques, this book: Discusses the main features and advantages of the DFIG Describes key theoretical fundamentals and the DFIG mathematical model Develops controllers using inverse optimal control, sliding modes, and neural networks Devises an improvement to add robustness in the presence of parametric variations Details the results of real-time implementations All controllers presented in the book are tested in a laboratory prototype. Comparisons between the controllers are made by analyzing statistical measures applied to the control objectives.
Book Synopsis Doubly Fed Induction Generators by : Edgar N. Sanchez
Download or read book Doubly Fed Induction Generators written by Edgar N. Sanchez and published by CRC Press. This book was released on 2016-08-05 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt: Doubly Fed Induction Generators: Control for Wind Energy provides a detailed source of information on the modeling and design of controllers for the doubly fed induction generator (DFIG) used in wind energy applications. Focusing on the use of nonlinear control techniques, this book: Discusses the main features and advantages of the DFIG Describes key theoretical fundamentals and the DFIG mathematical model Develops controllers using inverse optimal control, sliding modes, and neural networks Devises an improvement to add robustness in the presence of parametric variations Details the results of real-time implementations All controllers presented in the book are tested in a laboratory prototype. Comparisons between the controllers are made by analyzing statistical measures applied to the control objectives.
Now in its Third Edition, Alternative Energy Systems: Design and Analysis with Induction Generators has been renamed Modeling and Analysis with Induction Generators to convey the book’s primary objective—to present the fundamentals of and latest advances in the modeling and analysis of induction generators. New to the Third Edition Revised equations and mathematical modeling Addition of solved problems as well as suggested problems at the end of each chapter New modeling and simulation cases Mathematical modeling of the Magnus turbine to be used with induction generators Detailed comparison between the induction generators and their competitors Modeling and Analysis with Induction Generators, Third Edition aids in understanding the process of self-excitation, numerical analysis of stand-alone and multiple induction generators, requirements for optimized laboratory experimentation, application of modern vector control, optimization of power transference, use of doubly fed induction generators, computer-based simulations, and social and economic impacts.
Book Synopsis Modeling and Analysis with Induction Generators, Third Edition by : M. Godoy Simões
Download or read book Modeling and Analysis with Induction Generators, Third Edition written by M. Godoy Simões and published by CRC Press. This book was released on 2014-12-11 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in its Third Edition, Alternative Energy Systems: Design and Analysis with Induction Generators has been renamed Modeling and Analysis with Induction Generators to convey the book’s primary objective—to present the fundamentals of and latest advances in the modeling and analysis of induction generators. New to the Third Edition Revised equations and mathematical modeling Addition of solved problems as well as suggested problems at the end of each chapter New modeling and simulation cases Mathematical modeling of the Magnus turbine to be used with induction generators Detailed comparison between the induction generators and their competitors Modeling and Analysis with Induction Generators, Third Edition aids in understanding the process of self-excitation, numerical analysis of stand-alone and multiple induction generators, requirements for optimized laboratory experimentation, application of modern vector control, optimization of power transference, use of doubly fed induction generators, computer-based simulations, and social and economic impacts.
This thesis deals with the modeling, control and analysis of doubly fed induction generators (DFIG) based wind turbines (DFIG-WT). The DFIG-WT is one of the mostly employed wind power generation systems (WPGS), due to its merits including variable speed operation for achieving the maximum power conversion, smaller capacity requirement for power electronic devices, and full controllability of active and reactive powers of the DFIG. The dynamic modeling of DFIG-WT has been carried out at first in Chapter 2, with the conventional vector control (VC) strategies for both rotor-side and grid-side converters. The vector control strategy works in a synchronous reference frame, aligned with the stator-flux vector, became very popular for control of the DFIG. Although the conventional VC strategy is simple and reliable, it is not capable of providing a satisfactory transient response for DFIG-WT under grid faults. As the VC is usually designed and optimized based on one operation point, thus the overall energy conversion efficiency cannot be maintained at the optimal point when the WPGS operation point moves away from that designed point due to the time-varying wind power inputs. Compared with VC methods which are designed based on linear model obtained from one operation point, nonlinear control methods can provide consistent optimal performance across the operation envelope rather than at one operation point. To improve the asymptotical regulation provided by the VC, which can't provide satisfactory performance under voltage sags caused by grid faults or load disturbance of the grid, input-output feedback linearization control (IOFLC) has been applied to develop a fully decoupled controller of the active $\&$ reactive powers of the DFIG in Chapter 3. Furthermore, a cascade control strategy is proposed for power regulation of DFIG-WT, which can provide better performance against the varying operation points and grid disturbance. Moreover, to improve the overall energy conversion efficiency of the DFIG-WT, FLC-based maximum power point tracking (MPPT) has been investigated. The main objective of the FLC-based MPPT in Chapter 4 is to design a global optimal controller to deal with the time-varying operation points and nonlinear characteristic of the DFIG-WT. Modal analysis and simulation studies have been used to verify the effectiveness of the FLC-based MPPT, compared with the VC. The system mode trajectory, including the internal zero-dynamic of the FLC-MPPT are carefully examined in the face of varied operation ranges and parameter uncertainties. In a realistic DFIG-WT, the parameter variability, the uncertain and time-varying wind power inputs are existed. To enhance the robustness of the controller, a nonlinear adaptive controller (NAC) via state and perturbation observer for feedback linearizable nonlinear systems is applied for MPPT control of DFIG-WT in Chapter 5. In the design of the controller, a perturbation term is defined to describe the combined effect of the system nonlinearities and uncertainties, and represented by introducing a fictitious state in the state equations. As follows, a state and perturbation observer is designed to estimate the system states and perturbation, leading to an adaptive output-feedback linearizing controller which uses the estimated perturbation to cancel system perturbations and the estimated states to implement a linear output feedback control law for the equivalent linear system. Case studies including with and without wind speed measurement are carried out and proved that the proposed NAC for MPPT of DFIG-WT can provide better robustness performance against the parameter uncertainties. Simulation studies for demonstrating the performance of the proposed control methods in each chapter, are carried out based on MATLAB/SIMULINK.
Book Synopsis Advanced Control of Variable Speed Wind Turbine Based on Doubly-fed Induction Generator by : Lei Wang
Download or read book Advanced Control of Variable Speed Wind Turbine Based on Doubly-fed Induction Generator written by Lei Wang and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis deals with the modeling, control and analysis of doubly fed induction generators (DFIG) based wind turbines (DFIG-WT). The DFIG-WT is one of the mostly employed wind power generation systems (WPGS), due to its merits including variable speed operation for achieving the maximum power conversion, smaller capacity requirement for power electronic devices, and full controllability of active and reactive powers of the DFIG. The dynamic modeling of DFIG-WT has been carried out at first in Chapter 2, with the conventional vector control (VC) strategies for both rotor-side and grid-side converters. The vector control strategy works in a synchronous reference frame, aligned with the stator-flux vector, became very popular for control of the DFIG. Although the conventional VC strategy is simple and reliable, it is not capable of providing a satisfactory transient response for DFIG-WT under grid faults. As the VC is usually designed and optimized based on one operation point, thus the overall energy conversion efficiency cannot be maintained at the optimal point when the WPGS operation point moves away from that designed point due to the time-varying wind power inputs. Compared with VC methods which are designed based on linear model obtained from one operation point, nonlinear control methods can provide consistent optimal performance across the operation envelope rather than at one operation point. To improve the asymptotical regulation provided by the VC, which can't provide satisfactory performance under voltage sags caused by grid faults or load disturbance of the grid, input-output feedback linearization control (IOFLC) has been applied to develop a fully decoupled controller of the active $\&$ reactive powers of the DFIG in Chapter 3. Furthermore, a cascade control strategy is proposed for power regulation of DFIG-WT, which can provide better performance against the varying operation points and grid disturbance. Moreover, to improve the overall energy conversion efficiency of the DFIG-WT, FLC-based maximum power point tracking (MPPT) has been investigated. The main objective of the FLC-based MPPT in Chapter 4 is to design a global optimal controller to deal with the time-varying operation points and nonlinear characteristic of the DFIG-WT. Modal analysis and simulation studies have been used to verify the effectiveness of the FLC-based MPPT, compared with the VC. The system mode trajectory, including the internal zero-dynamic of the FLC-MPPT are carefully examined in the face of varied operation ranges and parameter uncertainties. In a realistic DFIG-WT, the parameter variability, the uncertain and time-varying wind power inputs are existed. To enhance the robustness of the controller, a nonlinear adaptive controller (NAC) via state and perturbation observer for feedback linearizable nonlinear systems is applied for MPPT control of DFIG-WT in Chapter 5. In the design of the controller, a perturbation term is defined to describe the combined effect of the system nonlinearities and uncertainties, and represented by introducing a fictitious state in the state equations. As follows, a state and perturbation observer is designed to estimate the system states and perturbation, leading to an adaptive output-feedback linearizing controller which uses the estimated perturbation to cancel system perturbations and the estimated states to implement a linear output feedback control law for the equivalent linear system. Case studies including with and without wind speed measurement are carried out and proved that the proposed NAC for MPPT of DFIG-WT can provide better robustness performance against the parameter uncertainties. Simulation studies for demonstrating the performance of the proposed control methods in each chapter, are carried out based on MATLAB/SIMULINK.
