Research On MPPT Control Of Low Wind Turbine Based On Improved Sliding Mode Control Algorithm

With the development of ideal wind power resources at high wind speed exhausted,low wind speed areas with huge total amount of wind energy and high utilization rate gradually become powerful development points.In the case of suppressing external disturbance and parameter uncertainty,sliding mode control has good robustness,so it is widely used in the phase of maximum power point tracking(MPPT)of wind turbines.However,the high intensity turbulence and the complex wind conditions make the speed tracking effect in the low wind speed area worse,and the load on the transmission chain also plays a vital role in the life of the generator.On the one hand,the excessive pursuit of high efficiency capture causes the severe fluctuation of electromagnetic torque,which increases the load of the wind turbine system substantially,thus causing the instability of the wind turbine system.On the other hand,it is difficult to obtain satisfactory wind energy capture efficiency by using traditional sliding mode control method to achieve maximum power point tracking.Therefore,two improved sliding mode improvement strategies are proposed to solve the above problems.The main results are as follows.(1)In the process of wind turbine MPPT,due to the pursuit of high wind energy capture efficiency,the wind turbine system load increased.In this paper,the power tracking error is used instead of the speed error.Considering that the integral action can accelerate the tracking response process,the power tracking error and its integral are taken as the sliding mode surface,and the parameters of the sliding mode controller are designed by using the fuzzy control method.Finally,Lyapunov stability theory is used to prove that the dynamic fuzzy integral sliding mode controller designed in this paper is effective in theory,and the simulation further proves that the control method can improve the efficiency of wind energy capture as much as possible while ensuring the low load of transmission chain.(2)The load of the transmission chain plays a crucial role in the life of the wind turbine,but the traditional sliding mode control will increase the load of the wind turbine.Considering that tracking the optimal speed will lead to the violent fluctuation of the electromagnetic torque,the load of the wind turbine will be increased.In this paper,a new type of sliding mode control for wind turbine based on load is proposed,namely,double integral sliding mode controller.The stability is analyzed by using Lyapunov function,and compared with the common sliding mode controller.The results show that the controller not only ensures the wind turbine system has a lower transmission chain load in the MPPT stage,but also improves the efficiency of wind energy capture.