Research On Wind Power Grid Connection Technology

With the warming of the climate and the serious greenhouse effect,more and more attention has been paid to the emission of greenhouse gases,and the research and application of clean energy has gradually stepped onto the world stage.Various countries have invested a lot of manpower and material resources in the research of clean energy.At present,the main clean energy sources are wind energy,solar energy,tidal energy and water energy.Among them,wind energy has more practical significance for application.It is abundant in wind energy and has less geographical restrictions.It can be used not only on land,but also on the sea.With the in-depth research of wind power generation in various countries,the power of wind power generator is also getting larger and larger.The current wind power generator can reach the level of megawatt,and the wind power generation technology is becoming more and more mature.From several kilowatts of wind turbines to tens of megawatts of wind turbines leap forward,from constant speed and constant frequency control technology to variable speed and constant frequency control technology development,wind power generation system research into the development of the fast lane.In recent years,direct-driven permanent magnet synchronous generator(PMSM)has gradually become a research hotspot.Compared with doubly-fed asynchronous generator,this kind of generator has simple structure,good stability,small size and light weight,so it is favored in the field of wind power.In this paper,the control strategies of the machine side converter and the grid side converter of the PMSM wind generator are studied and analyzed.For machine side control strategy,zero D axis vector control strategy,SVPWM debugging method and mountain climbing search method are combined to realize maximum wind energy tracking.For the control strategy of grid side,the double closed-loop control strategy based on grid voltage orientation and the direct power control strategy are compared and studied,and the advantages and disadvantages of the two control strategies in operation are analyzed.Firstly,the research background and current situation of wind power generation are introduced,and the permanent magnet synchronous wind generator and double PWM converter are selected as the research objects.A wind turbine model is built to simulate the torque output of wind turbines under various wind speed conditions.Then,the principle of SVPWM and the calculation method of each part are analyzed for the machine side part,and the zero D axis control strategy is modeled mathematically.A variable step length mountain climbing search method is proposed,and then they are modeled by Simulink,followed by verification of maximum wind energy tracking and searching for the switching cycle of SVPWM optimal flux linkage.A simulation model is built for the side of the grid to compare the response speed and stability of the two control strategies in wind power generation system.Finally,on the experimental platform based on DSP2812,the zero-D axis control strategy and SVPWM modulation of 750 W permanent magnet synchronous motor are verified and applied.On a 7.5KW permanent magnet synchronous motor(PMSM)pair towing experiment platform,the working state of zero D axis control during load running is verified.