Controlling Research Of Direct-drive Permanent Magnet Synchronous Wind Power System

With the development of society and the increasing of the population,energy and environment problem is becoming more and more serious. In order to the sustainable development of society,humans are working hard on new energy development and utilization.Wind power has already plays a particularly important role in renewable power field because of its fastest growing and largest development scale.In the numerous wind power system,the direct-drive permanent magnet synchronous wind power system has attracted more and more attention because of its simple structure,high efficiency and high reliability. The controlling research of direct-drive permanent magnet synchronous wind power system has already been a hot spot.First of all,this paper has a research on the characteristics of wind turbine.Below the rated wind speed,in order to gain maximum wind energy,the wind turbine run in the generator control mode with maximum power tracking algorithm.Above the rated wind speed,the wind turbine run in the pitch control mode to limit the wind energy capture.Then, the mathematical model of permanent magnet synchronous motor and dual PWM converter are established.The machine side converter take the id=0current vector oriented control strategy and the grid side converter take the voltage vector oriented control strategy.At last,the paper built the direct-drive permanent magnet synchronous wind power system simulation model in MATLAB environment.lt lays a foundation for variable pitch control and low voltage ride through control research.After building the model of direct drive permanent magnet synchronous wind power system,this paper throw a attention on variable pitch control.The paper adopt a fuzzy neural network algorithm which is suitable for nonlinear system into pitch control,and design a fuzzy neural network pitch controller based on power transform.The fuzzy neural network controller can memory expert’s control experience.lt has a better adaptation to strong randomness and uncertainty of wind power system and has a strong robustness and anti-interference ability.The simulation results show that the control effect is superior to the traditional PD controller.In the aspect of low voltage ride through control,first,the paper analyses the power transmission transient process of the direct-drive permanent magnet synchronous wind power system when the grid has a low voltage fault.Then,introducing two kinds of crowbar low voltage protection scheme that one is based on energy consumption and the other is based on energy storage,and also comparing the advantages and disadvantages of two kinds of protection scheme.A reactive power compensation control strategy is adopted in grid’s low voltage fault situation and two low voltage auxiliary control strategy are recommend as well.Finally,combining with the existing low voltage through strategy,the paper puts forward a integrated control logic of low voltage ride through and having a simulation on the MATLAB.