Control Strategy In Direct Drive Wind Power Generation System

With the aggravation of the energy crisis and the worsening of environment prominent today, the development and utilization of renewable energy are imminent consequently. The technology development of solar, wind, hydro is concerned by many countries around the world. Wind as a renewable, clean non-polluting, inexhaustible energy, become a potential direction of the world’s renewable energy development, which poses great significance to alleviate the current energy tensions.The direct-drive Permanent magnets synchronous generator system has a myriad of advantages, such as gearless, direct coupling between generator and wind turbine. Moreover, wind energy conversion efficiency and reliability is improved, It also does not require electric excitation, and improves power generation efficiency of the unit. So direct drive wind turbine has been a hot wind Power generation technology.This paper focuses on the research of direct-drive wind power system, it first introduces the research of wind power technology development at home and abroad, describes several common topologies, based on the research, It selects the topological structure of back-to-back PWM converter.Secondly, It details the wind turbine aerodynamics, analyses the process that wind energy is converted into mechanical energy by wind turbine, concludes the maximum power principle. On this basis, the simulation module of the wind turbine is set in final paper.Thirdly, this paper also introduces the principle of vector control between several coordinate transformation matrix and the principle of the SVPWM modulation technique. The mathematical model of the direct-driven permanent magnet wind power machine side and network side in each coordinate system is established, and several control strategies of the generator-side converter based on the vector control is studied. The maximum wind-energy tracking control strategy with the optimal reference power is achieved with the generator-side converter’s particular method as the double-loop control mode, the electric circuit is taken as inner loop, and the outer loop of the double-loop speed control strategy be seized, so that the grid-side converter is due to realize unit power factor control, double-loop control mode is used too, but the outer loop using voltage instead.Finally, it builds the simulation model in Matlab/Simulink according to the principle of control strategy. The experiment results verify the correctness of control strategy. In conclusion, the system is stable and good performance so that it achieves the desired control objectives.