Research On The Simulation Platform Of Direct-drive Permanent Wind Power Generation System

In modern society, energy and the environment problems are increasingly prominent. The development of wind, water, and hydro power, have attracted and more and more attention. Wind power generation is a sort of inexhaustible and renewable resource, which has important significant to alleviate the tense situation of scarce energy problem.The direct-drive permanent magnet synchronous wind energy generation (PMSG) system has no gear case, and its wind turbine is directly connected to the generator. So the system can improve the ability of the low voltage ride through (LVRT) and efficiency and reliability. This thesis reports a comprehensive research effort on the simulation platform of direct-drive permanent magnet synchronous wind power system, including the Matlab/Simulink work and the experimental verification, laid a good foundation for the research in future.Firstly, the thesis introduces the aerodynamic of wind turbine, analysis the process of the wind turbine makes the wind energy converted to mechanical energy, and describes the principle of maximum power point tracking (MPPT). On this basis the simulation module of wind turbine is established.Secondly, according the work principle of the direct-drive permanent magnet wind turbine generator system, this paper proposes dual PWM converter control strategy and designs SPLL. The simulation results show that the correctness and affectivity of the MPPT control and dual PWM converter control strategy.Thirdly, for the fault of the grid voltage dip, this paper analyzes several common-used LVRT technology of the PMSG wind power system. By the comparison and analysis, a method of a crowbar protection circuit with resistance at DC bus is illustrated and adopted. In addition, the selecting principle and the control strategy of the brake resistor is analyzed. And by Matlab/Simulink, the simulation model of the crowbar protection circuit with resistance is established and its effectiveness is also verified. Finally, a simulation platform for direct-driven wind power generation system is designed, which has complete function and friendly customer interface. To solve the problem of wind turbine simulation in a laboratory, this paper uses the asynchronous motor to simulate wind turbine. By controlling the double PWM converter, the purpose of stabilizing the voltage of DC bus and adjusting the power factor can be achieved. By adding the damping resister at DC bus, the capability of fault ride through is improved. A LabView based computer monitor system has been designed, which has friendly interface and easy to operate the simulation platform. The test results show that the platform can realize control functions and be easily used to study the technology of wind power in the laboratory condition.