Nonsingular Terminal Sliding Mode Control Of Permanent Magnet Direct Drive Wind Power System

With the increase of energy consumption and the requirements of environmental protection, as one of the renewable clean energy sources, the development and utilization of wind energy has been made widely attention from the word. At present, the wind power technology is developing rapidly. The permanent magnet direct drive wind power system has been widely used because of the advantages of simple structure, low fault rate, power generation efficiency and higher reliability. Therefore, it is very significant to adopt a proper control strategy controlling the permanent magnet direct drive wind power system. The main research results are as follows:(1) Based on analysis of structure and operation principle of the permanent magnet direct-drive wind power system, the mathematical model of the main component is established, and the dynamic model of the Permanent Magnet Synchronous Generator(PMSG) under the d-q synchronous rotating coordinate is get through the Clark transformation and Park transformation.(2) The Maximum Power Point Tracking(MPPT) of the permanent magnet direct drive wind power system when the speed of wind speed under the rated wind speed is studied, the principle of MPPT is analyzed, and several kinds of MPPT methods which are applied widely are introduced. In order to overcome the wind speed measurement error, based on the optimum torque maximum power point tracking method, high-order nonsingular terminal sliding-mode control is employed to designed the torque controller and current controller of PMSG, by controlling the torque current component the rotor speed is regulated, the maximum torque tracking is realized. It realizes MPPT and stability control of the Permanent magnet direct drive wind power system. The proposed strategy don’t need measure wind speed, have robustness and good dynamic performance.(3) The variable pitch constant power control problem when the wind speed above rated wind speed is studied, based on the in-depth analysis of the wind turbines variable pitch control principle, the mathematical model of variable pitch system is established, and considering the random disturbance of the wind, the variable pitch speed and electromagnetic torque nonsingular terminal sliding mode controller are designed. Then the variable pitch constant power control is realized.(4) The effectiveness of the proposed control strategy is verified based on the MATLAB/Simulink simulation experiments. And compared with performance of the traditional sliding mode control by simulation, the simulation results show that the proposed control strategy improves the response speed and precision, and can effectively eliminate the chattering, so the system obtain a good dynamic and static performance.