Research On Control Method Of Direct-Drive Permanent Magnet Synchronous Wind Power Generation System

With the global economic integration process continues to speed up, human demand for energy rising, the traditional energy depletion, making the wind energy and other renewable energy advantages constantly emerge.Wind energy is the main way to use wind power.In the case of wind power system configuration,Wind power system control way directly determines the merits of the use of wind energy and wind power quality. Therefore, it is of great practical significance to improve the control way of wind power system as much as possible.Based on the Wind Energy Conversion System (WECS), this thesis has carried on the thorough research of the system side maximum power point tracking (MPPT)control,and the Grid-side inverter control. The main contents are as follows:Firstly,the development of wind power industry and key technologies of wind power industry is summarized, and the topology of wind power system is introduced systematically.Secondly, the principle and characteristics of Permanent Magnet Synchronous Generator (PMSG) and wind turbine are studyied, On this basis, the mathematical model of wind turbine and PMSG is constructed, and the model is established by Matlab/Simulink. The correctness of the model is verified and the understanding of the working characteristics is verified.,In addition, through the research on three-phase uncontrolled rectifier circuit, Sepic circuit simulation and analysis, it is of benefit to understand the working conditions and choose the parameter of the circuit. Thirdly, the MPPT control method of wind power system is studied. It is found that the traditional perturbation algorithm has some contradictions in tracking fastness and stability of the maximum power point. For this reason, In this thesis, we focus on improving it, and obtain the double-disturbance value,multi-perturbation value search algorithm, the MPPT algorithm based on fuzzy theory, the MPPT algorithm based on power rate change, and the simulation and analysis of these algorithms are carried out by means of Matlab/Simulink. The validity and superiority of the improved MPPT control algorithm are verified. Finally,the inverter structure of the wind power system is analyzed and the mathematical model under different coordinate systems is constructed. Based on this, the control strategy of the inverter system is analyzed, and the mathematical model based on the directional control of the electric grid is constructed. Moreover, the simulation system of the control strategy is simulated by Matlab / Simulink.The correctness of the control strategy is verified by simulation.In this thesis, the simulation of MPPT control and grid-connected inverter system control of WECS has achieved the expected purpose, which provides a reference for further research.