Research On Power Control Of Small And Medium Wind Turbine Based On Sliding Mode Variable Structure

The environmental problems in today's society is attracting more and more people's attention,and the haze has become a major problem for people.Therefore the development of clean and renewable energy is imminent.As one of the most common clean energy,wind energy is getting important in new energy power generation system.The permanent magnet direct drive wind turbine is being used frequently because of its high efficiency,simple structure and low maintenance cost.In addition to large-scale wind turbines applied in the wind farm,the application of small wind turbines in distributed generation are also increasingly popular.However,many small and medium-sized wind turbine control strategies are simple,leading to the efficiency of the unit is low,so the advanced and reliable control method applied to small and medium-sized wind turbine to improve its efficiency means a lot.This article first analyzes the related theory of wind power generation,and the operatio n process below rated wind speed and above rated wind speed of is analyzed emphatically,It is concluded that the torque control or pitch control should be controlled at different stages for the output power.Then,the structure of the permanent magnet direct drive wind turbine is analyzed in detail and modeled according to the characteristics of each part.According to the control logic of wind turbine under different wind speed,the sliding mode variable structure control mode applied to the controller designing.The sliding mode torque controller and pitch controller are designed to achieve that torque control under the rated wind speed and pitch control above the rated wind speed.The STP observer is designed to estimate the value of the controller,which can weaken the chattering phenomenon of sliding mode variable structure and improve the control accuracy.Finally,a 20 kW permanent magnet direct drive wind turbine model is build in Matlab/Simulink simulation platform to verify the controllers' performance,and the controllers demonstrated good control performance.