Research On Power Control And Fluctuation Suppression For Doubly Fed Asynchronous Wind Power System

With the development of wind power technology,the impact of large-scale wind power access on the power grid can’t be neglected.The main feature is that wind energy has strong intermittency and volatility.This characteristic causes the irregular fluctuation of output power of wind power generation system,and it poses a threat to the safe and stable operation of power grid.Therefore,it is of practical significance to study how to suppress the fluctuation of wind power to the large-scale development and utilization of wind power.Due to the time-varying nonlinearity of the wind power system itself,the traditional control methods can’t meet the needs of its control.This tissue mainly focuses on the research of the wind turbine intelligent control and the suppression of the power fluctuation in the doubly fed asynchronous wind power generation system.This tissue studies the operation characteristics of wind machine in above rated wind speed and the wind speed is below the rated wind speed,the method of wind speed control based on hybrid energy storage is given and the range of the frequency distribution of the hybrid energy storage system is determined.By controlling the pitch angle and rotor current,the output power of the fan is always maintained at the rated output power of the fan,and a more reasonable control strategy for the smoothing control is established.The main research contents are as follows:(1)A power control method based on feedback linearization for DFIG wind power system is proposed.First,the mathematical models of constant power and maximum power output of doubly-fed asynchronous wind power generation system are established respectively.The constant power control chooses the pitch angle control mode and the maximum power tracking control chooses the rotor current of DFIG to control.Through the nonlinear system linearization,the optimal tracking control method is given to complete the control target.(2)Considering the feedback linearization of DFIG wind power system output power control method can’t adapt to the change of wind speed change switch control mode,resulting in the problem of the input of control is not continuous and the fluctuations of fan power increases,a DFIG wind power system power control method of robust sliding mode controller based on unified control input constant power control and MPPT control is proposed.The method chooses the sliding surface and control function according to the control requirements and solves the chattering problem of sliding control.The robust sliding mode controller is designed by using the Lyapunov function,which has better robustness and anti-interference ability.(3)A wind energy fluctuation suppression method based on hybrid energy storage is proposed.According to the standard of wind power integration,the best decomposition level of wavelet packet is selected adaptively,and then the power fluctuation component is obtained,and the energy storage structure combined with power type is used to stabilize the fluctuation.In order to avoid frequent battery charging and discharging,the power optimization control module and power re-distribution module are designed,which can ensure the life and stabilization effect of the storage device at the same time.