Analysis Of Voltage Stability Of Grid-connected Doubly-fed Wind Turbines

In today's society,energy is the foundation of social development.With the excessive development and utilization of non-renewable energy,wind energy has been developed and applied as a clean and renewable energy source.With the maturity of wind power technology,wind turbine capacity it is also increasing.The number and scale of wind turbines are gradually increasing.At the same time,however,with the large-scale wind power grid connection,due to the randomness and unpredictability of the wind itself,it will have a great impact on the stability of the power system voltage after grid connection,which will lead to the collapse of the system voltage.It affects people's normal production and life.First of all,this article will introduce the background and significance of the research topic.Combine the global wind power development status to analyze the differences in wind power development between China and other countries in the past few years,and analyze the research status of wind power development at home and abroad.This paper mainly analyzes the transient voltage stability and static voltage stability of wind turbines after grid connection,and also discusses the research status of reactive power compensation devices for stable operation of wind farms.?Secondly,the paper also introduces the mathematical model of the doubly-fed wind turbine.Including wind turbine model,doubly-fed asynchronous wind turbine model,control model of doubly-fed asynchronous wind turbine and equivalent model of wind farm.This paper analyzes the power system voltage instability method from the dynamic and static processes of power system voltage instability.This paper summarizes the PV curve method,VQ curve method and sensitivity analysis method for static voltage stability analysis of power system,and analyzes the transient voltage stability of the system by time domain simulation method.Thirdly,the paper analyzes the stability of the transient voltage after the grid is connected to the grid under different wind speeds such as asymptotic wind,gust,random wind and three-phase fault.At the same time,the wind power is studied by capacitor compensation and STATCOM reactive power compensation and the impact of transient voltage stability of the network.In this paper,by comparing these two different reactive power compensation devices,it is more beneficial to stabilize and recover the system voltage when the voltage fluctuation occurs after the wind turbine is connected to the grid.Finally,this paper builds a model in MATALAB/Simulink software,combines multiple fans into one fan,and uses the equivalent fan to analyze the stability of the voltage after grid connection.The results show that at different wind speeds,when the grid voltage is affected,the STATCOM reactive compensation is more conducive to the stability and recovery of the grid voltage.In the same way,in the case of three-phase fault,compared with the STATCOM reactive power compensation,it is found that the reactive power compensation under STATCOM is significantly higher than the capacitor compensation for grid voltage stability and recovery after grid connection.In the study of static voltage stability,the static voltage stability is judged and analyzed by three different methods.It is found that the method of judging static voltage stability based on the improved BA method is obviously higher than the BA algorithm.And PSO algorithm...