A Research On Grid Connection Control System Of Doubly-Fed Asynchronous Wind Generator

Energy is the material basis for the survival and development of human society.With the continuous development of economy,the demand for energy is more and more vigorous.This paper mainly studies the system composed of doubly-fed asynchronous wind generator and carries out grid-connected control.The specific research contents are as follows.Firstly,the basic principle of the doubly-fed generator is analyzed and the mathematical model of the generator in the two-phase rotating coordinate system is given.The basic structure,basic working principle and SVPWM modulation technology of the doubly-fed converter are introduced.The mathematical model of the doubly-fed converter is given to lay a foundation for the wind power grid control below.Second to study control method,vector control was carried out on the network side converter,the internal and external controller chooses the traditional PI control,PI controller parameters is adjustable,the adaptive ability is poor,the outer ring of dc side voltage change is slow,it is hard to track the given value,therefore,aiming at the flaws of the voltage loop PI control,using fuzzy PI control to improve the traditional PI control,fuzzy control can be based on the input deviation and deviation derivative in real time by adjusting the parameters of the PI system,make the system adaptive ability is strong,the output response speed,system voltage in dc side is able to fast track the given value,system will markedly enhance its capability of anti-interference,At the same time,the control effect of rotor side converter can be improved.And then to control the rotor side converter,the rotor side converter in vector control,and according to the mathematical model of the generator under the two phase rotating coordinate system current based on sliding mode variable structure controller is designed,the rotor current control,through the reasonable design of sliding mode variable structure controller,shorten the rotor side current dynamic response time,but the chattering in the sliding mode variable structure control,this paper studies on the improvement.Finally,in order to verify the effectiveness of the proposed control method in wind power grid connection,a simulation model of wind power generation system was built on the Matlab/Simulink simulation platform to carry out grid connection control for doubly-fed wind turbines.Through simulation comparison research,the advantages of the proposed control method in this paper were analyzed.