Analysis And Mitigation Of Subsynchronous Oscillation Of Doubly Fed Wind Power Generation System

With a large number of wind farms equipped with doubly fed induction generator integration into grid in China.Moreover,the series compensation technology as a kind of commonly used means of long distance transmission,may lead to sub-synchronous oscillation(SSO).This paper makes deepgoing analysis about the sub-synchronous oscillation phenomenon.The main contains are as follows:(1)The mathematical model of DFIG is established in detail.Mainly including the aerodynamic model of wind energy capture,the model of doubly fed induction generator,the model of the rotor side converter,the model of grid side converter,the model of transmission line and so on.(2)By comparing the analysis methods of sub-synchronous oscillation,this paper selects the method of eigenvalue structure analysis and the method of time-domain simulation to analysis the causes of SSO.First,the model of eigenvalue structure analysis is established,which is on the base of the improved model of the rotor side converter and the method of changing step length.Then the correctness of the analysis based of the method of eigenvalue structure analysis is verified by the method of time-domain simulation.(3)Fuzzy controller based variable universe is designed on the base of the improved model of eigenvalue structure analysis and the theory of the fuzzy control.Moreover,the fuzzy controller is used to restrain the SSO in consideration of the character of variable speed and constant frequency of DFIG.In addition,by comparison with the results of simulation,show that,the fuzzy controller based variable universe has good adaptability in different conditions,and has better effect compared with the traditional additional damping controller.