Research On Energy Conversion And Control Strategy Of Stand-Alone Wind Power Generation System

Stand-alone wind power,as a sunrise industry of distributed generation, is one of the most important ways to solve the electricity shortage in remote areas with no grid. In order to better meet multiple needs, the research on wind energy capture, energy conversion and power transformation of this system is deepening. To further improve the efficiency of the motor and converter,some new strategies for improving the performance of high-frequency rectifier and inverter are adopted,and the study on operation mechanism, system design and equipment testing of MPPT and yaw system is carried out as well.Firstly,the system components and operating mechanism of the link are compared and analyzed. For the purpose of designing a controller that can implement accurate and effective control, the operating characteristics of wind turbines, PMSG and the converter are analyzed,and the mathematical models of them are also deduced.Secondly, a three-phase boost rectifier with voltage boost is put forward . By adopting the control method, the switching loss of power module is reduced, the power factor can be higher and the harmonic content is low. And simulation model based on MATLAB/Simulink is built to verify the sector segmentation method and control strategy. Experiment on the platform controlled verified the feasibility of the strategy Experiment on the platform controlled by TMS320F2812 DSP verified the feasibility of the strategy.Thirdly, against the requirements of inverter unit, deadbeat control is adopted. According to the state space method, the nature of deadbeat control is analyzed,and output equation is derived. Based on discrete control method of deadbeat, an optimal control method with fast response is proposed. The results of the experiment prove the feasibility. The dynamic reliability with load changing is also tested by the simulation. The experimental platform based on microcomputer whose results prove the correctness of the above-mentioned methods is also built.Finally, in response to the uncertainty of wind speed,the wind turbine characteristic is analyzed, a method based on the Hill-climbing is used in this article. The optical speed is determined by the location of power point. Instead of two-point comparison method, a comparison method with three points is selected. The simulation results show its advantages---fast response and small fluctuations. To overcome the randomness of wind direction, the yaw system is studied. The hardware and software of yaw is designed, the results of the yaw system satisfy the requirements of system design, and show a good condition of the yaw system operation.