Research on stability control of permanent magnet synchronous wind power generation system based on sliding mode control

Abstract

This paper investigates the stability control of a permanent magnet synchronous wind power generation system (PMSWG) under wind speed fluctuation, parameter perturbation and load disturbance using sliding mode control (SMC). A mathematical model of the permanent magnet synchronous generator (PMSG) is established to analyze the coupling relationship between electrical and mechanical variables. To improve the dynamic performance of the system, an optimal sliding mode control (OSMC) method is developed for the speed loop. By properly tuning the sliding surface parameters and reaching law parameters, the system state can approach the sliding surface in a smoother manner, thereby reducing chattering and transient impact during startup and load mutation. Meanwhile, an equivalent torque disturbance observer is designed to estimate wind speed variation, load torque disturbance and parameter perturbation in a unified form, and the estimated disturbance is introduced into the controller for feedforward compensation, enabling active disturbance rejection. Finally, a vector control simulation model is built on the Matlab/Simulink platform, and a load torque step is used to equivalently simulate the mechanical disturbance caused by wind speed variation. The performances of PI control and OSMC are compared under the same conditions. The simulation results show that, compared with PI control, the OSMC reduces electromagnetic torque fluctuation, weakens the transient impact of three-phase current, and makes the disturbance estimation response smoother, thereby improving the dynamic stability and disturbance rejection capability of the system under disturbance conditions.