Study On Optimization Of Low Voltage Ride Through For Doubly Fed Wind Power Generation System

In recent years,the traditional fossil energy consumption caused by environmental crisis is becoming increasingly serious,the development of renewable energy.The focus is represent the general trend wind power as a clean and renewable energy,by the world attention,Wind power has become an important direction of energy development strategy of the country.With the increase of installed capacity of wind power,the interaction between wind turbines and power grid becomes more and more important.Doubly fed induction generator(DFIG)has become the mainstream model because of its high energy conversion efficiency and small excitation converter capacity.So with doubly fed generation system as the research object,according to the power grid voltage sags wind generator transient response and low voltage through uninterrupted operation of great significance.The research work of this paper is as follows:This paper first describes the current development of wind power generation at home and abroad,and the significance of developing low voltage ride through technology,and summarizes the basic principle and related control technology of doubly fed machine.The mathematical model of doubly fed motor three-phase static coordinate system and two-phase synchronous rotating coordinate system,on the basis of these models,to decouple control,and analyzes the transient process of power grid voltage dips doubly fed induction generator system.Then the network side converter is analyzed and the state equation of the double fed motor through the inverter mathematical model and grid voltage sag,double closed-loop control strategy is proposed to control the DC voltage and current loop converter based on the network side of the outer loop control,maintain the stability of the bus voltage and control the power factor;Summarizes the basic theory of control mechanism for the control of sliding,the current machine side rotor,design the corresponding sliding controller,and the stability is proved by using Lyapunovexponent.Then the working principle and control methods of Crowbar analysis,this paper proposes an adaptive Crowbar protection scheme.The LVRT related problems of mainstream DFIG wind generator for the corresponding theoretical research and related simulation experiments.computerMATLAB simulation the feasibility and accuracy of the scheme.