Research On Grey Prediction Vector Control Of Doubly-fed Wind Power Generation System

With the over-exploitation and utilization of traditional fossil energy,the energy crisis and environmental pollution have become increasingly serious,and have received the attention of the international community.People have begun to increase the research and utilization of renewable clean energy.Wind energy is an ideal energy source,which has the advantages of rich reserves and wide distribution.The most efficient way to use wind energy is wind power generation.Doubly-fed wind power system has the advantages of low manufacturing cost,wide speed range,high wind energy utilization rate,and slip power can flow in both directions.It has become one of the mainstream models in the wind power industry.In this paper,a brief overview of the development status of wind power generation and the research status of doubly-fed wind power generation system's control strategy is given.This paper introduces the working principles and mathematical models of wind turbine and generator in doubly-fed wind power generation system.It also analyzes the key to achieve variable-speed constant-frequency power generation and maximum wind energy tracking—vector control for grid-side converters and rotor-side converters.An overall simulation model of doubly-fed wind power system is established on the MATLAB/Simulink platform.In addition,the wind speed model is also studied and simulated in this paper.In order to improve the working performance of doubly-fed wind power generation system,this paper combines the grey prediction control theory and the PI control theory to propose a grey prediction PI controller.And it is simulated by a typical second-order system simulation model,and the simulation results prove that the grey predictive PI controller has smaller system overshoot and shorter adjustment time.Simplify the overall model of the doubly-fed wind power generation system and simulate the grid-side converter.The simulation results verify that the grid-side converter can maintain the stability of the DC link bus voltage,maintain the unit power factor and ensure the two-way flow of power.The grey prediction PI controller is applied to the vector control system of grid-side converter,and it is proved that the improved control system has a narrower bus voltage drop range and better performance in the case of grid voltage drop.Based on the overall simulation model of doubly-fed wind power system,the grey predictive PI controller is applied to the vector control system of the rotor-side converter.The comparative simulation is performed under the condition of step change in wind speed,and the simulation results show that the improved doubly-fed wind power system can effectively complete power decoupled control and variable-speed constant-frequency power generation.And compared with the traditional system,the improved system has faster response speed,improved stability,and has better working performance in the process of maximum wind energy tracking.