Modeling And Controlling Of Wind Energy Conversion System

Wind energy conversion system is a complicated field refers to electrical machine, power electronic, electrochemistry, material, mechanics, aerodynamics, computer, automation, aerography and etc. Following the increasing demand of electric power and environmental protection all over the world, it is important to exploit the renewable and clean energy sources. This dissertation mainly aims at modeling and controlling each part of WECS and simulating the system response under different disturbances to develop a suitable controller.First of all, an accurate WECS model with its control system is the base of all the following studies. In the dissertation, an integral WECS model is built using digital simulation software MATLAB. The simulation results show that the model present dynamic performance tallying with that of actual systems under any operation conditions.The WECS control problems and the background of this thesis is summarized in the first chapter, as well as the train of thoughts and what have done in the dissertation.In chapter 2, the resource of wind power in our country and the configuration of WECS are presented. Finally different VSCF technologies are analyzed.The mathematical model of each element of a Stand-Alone WECS including wind turbine, permanent magnet generator, rectifier, storage battery and PWM inverter is developed in the d-q rotor reference frame in chapter 3. Based on theconservation of energy and the same fundamental quantity, equivalent circuit of the WECS is founded. State equations under disturbances are described with the kinetics characteristics. This model is verified by comparing the simulation results using MATLAB with the theory.The configuration and characteristic of the direct combination wind generator are introduced in chapter 4. Following the increasing capability of wind power, the distribution networks will be under disturbances by reason of the randomness and intermittence of the power resources. Integrating the power flow program with the tools MATLAB simulates the transient response of the distribution networks with the direct combination wind generator under disturbances, it provides the credible rationale to the research on stability and maximal penetrable power.Chapter 5 describes how to design fuzzy control rulers by reverse pulse algorithm, which solves the problem of fast charging on the storage battery. This method is applied to improve the efficiency of power conversion and shorten the charging time.Finally the conclusions and discussions of the dissertation are presented.