Research On The Application Of STATCOM In Distributed Wind Power Grid-connected Syste

The "30 60" dual carbon target requires China to achieve carbon peak within 10 years and carbon neutral within 40 years.In the face of energy crisis,distributed wind power generation will also usher in greater opportunities and challenges.Because wind energy relies too much on natural environment and has the characteristics of fluctuation,intermittensity and randomness,the problems of grid-connected power and voltage fluctuation have restricted the expansion and application of wind power industry to a certain extent.Based on the structure and characteristics of distributed wind power grid-connected system,this paper optimized the control strategy of Static Synchronous Compensator(STATCOM)in distributed wind power system,and mainly completed the following research work:The basic working principle of distributed wind power generation is analyzed,and the power and voltage fluctuation relationship of distributed wind power gridconnected is studied in detail from its grid-connected characteristics and output characteristics and other influencing factors.Based on the analysis of the mechanism of wave characteristics,the method of STATCOM to suppress voltage fluctuation of distributed wind power grid-connected is studied.Starting from the structure and control strategy of STATCOM,LCL filter with stronger high-frequency suppression ability is used as the harmonic filter device between the power grid and STATCOM to solve the cost and volume problems brought by the traditional single-inductor L-filter.The modeling and parameter design of LCL coupling STATCOM are carried out in detail,and the problems of using traditional control strategy for LCL coupling STATCOM are studied and analyzed.The unique structure of LCL filter increases the complexity of the traditional PI control strategy,and the model-dependent control algorithm and complex decoupling process of PI controller cannot ensure the accuracy of controller tracking control signal,and the performance of LCL STATCOM is seriously affected.In this paper,based on the traditional voltage-current control theory,aiming at the particularity and complexity of nonlinear time-varying system,the control strategy is improved on the basis of the traditional control,and the cascade double loop control of LCL STATCOM is proposed based on the transition process of the junction point voltage outer loop nonlinear PI and the current inner loop quasi-proportional resonance(QPR).The Tracking Differentiator(TD)is used to set the transition process,reduce the signal starting error,reduce the overshoot and accelerate the response rate.QPR controller is used to reduce the complexity of the system control strategy,simplify the control,and improve the system signal tracking accuracy.Finally,the MATLAB/Simulink platform was used to build a simulation model,and the distributed wind power grid-connected system was taken as a simulation example to compare and analyze the suppression effect of distributed wind power gridconnected voltage fluctuation under different working conditions.The simulation results show that the cascade double-loop control strategy used in this paper has a better suppression effect on the system voltage fluctuation,and can effectively improve the operation stability and power quality of the distributed wind power grid-connected system.