Sliding Mode Control Strategy Of Maximum Power Point Tracking Control For Megawatt-scale Wind Turbines

Large moment of inertia and complex nonlinear characteristics of megawatt-scale wind turbine are the difficulties in Maximum Power Point Tracking(MPPT)control.In the MPPT stage,the core purpose is to improve the wind energy capture efficiency of the wind turbine,followed by reducing the instantaneous load borne by the wind turbine.This paper studies the maximum power point tracking control of megawatt-level wind turbines,designs three control strategies,and verifies the effectiveness of the controller under turbulent wind speed.Firstly,to improve the efficiency of wind energy capture for the purpose,in view of the poor speed tracking effect of the optimal torque method and the difficulty in obtaining wind speed in the sliding mode control method,an integral sliding mode controller was proposed.The proposed method use the estimated wind speed to track the rotor speed,realizing the fast tracking of the optimal speed of the wind turbine and achieving higher wind energy capture efficiency.The effectiveness of the control strategy under turbulent wind speed is verified on the professional wind turbine simulation platform.Secondly,in order to improve the wind energy capture efficiency,from the perspective of improving the rotor tracking speed,the backstepping control idea is introduced,and the MPPT controller based on dynamic surface backstepping sliding mode is designed.The dynamic surface is introduced to solve the differential explosion problem of intermediate virtual control in the backstepping control,and the sliding mode control is used to enhance the adaptability of the backstepping control to the rapid change of wind speed.The simulation results show that the method can achieve better wind wheel speed tracking effect,so as to improve the wind energy capture efficiency of the wind turbine.Finally,considering reducing the instantaneous load of the wind turbine transmission chain when the wind speed changes sharply,an integral sliding surface based on torque error tracking is designed.The sliding surface is established by the difference between the optimal generator torque and the actual generator torque,and the integral control is introduced in the design of the sliding surface.The simulation results show that the method can keep high wind energy capture efficiency while reducing the instantaneous load of wind turbine.