Research On Converter Control Of Permanent Magnet Direct Drive Synchronous Wind Generator

With the continuous exploitation of non-renewable energy and the increasing demand for energy,wind power generation has developed rapidly in recent years.In this paper,the permanent magnet direct drive synchronous wind generator,with high conversion efficiency,is widely used in wind generator field,and its control system based on dual PWM converter is studied.Firstly,the research status of wind power generation at home and abroad and the development and characteristics of converter control strategy are introduced.The mathematical model of the PMSM and the converter are studied in detail.Then the principle of maximum power point tracking(MPPT)strategy is elaborated,and the shortcomings of the algorithm are emphatically analyzed.In order to avoid the influence of oscillation and misjudgement caused by traditional hill climbing algorithm on tracking accuracy,the fuzzy control is combined with the optimal gradient method.When generator starting and disturbed by external environment,the system tracks the maximum power point quickly.Improving the dynamic response characteristics of the control while effectively reducing the power oscillation,not only ensure a faster convergence speed,but also the tracking accuracy.For the converter control system on the generator side,several common control strategies are studied and analyzed,and the id=0 vector control strategy is determined.At the same time,the fuzzy control optimal gradient method is applied to the id=0 vector control system.In addition,the grid side control method based on voltage oriented control is adopted for the grid side control of wind power generation system.The operation status and control method before and after the grid connection are analyzed in detail.On the basis of the related parameters of Daqing Dui Shan wind power plant,the control simulation model is built by MATLAB/Simulink to verify the effectiveness of the control strategy.The simulation results show that the wind speed can be traced quickly and accurately when the wind speed changes.The voltage of the DC side is stable and the harmonic content of the output voltage waveform of the power grid is less.Meanwhile the phase difference between the output voltage and the current is small and the power factor is high.The wind power generation can be effectively connected to the grid.