Study On Impact Of Wind Farms Access Distribution Network On Relay Protection

In recent years,the shortage of original energy and the problem of environmental pollution are becoming increasingly acute.People began to find all available alternatives which are environmentally friendly and renewable to instead of traditional energy sources like coal and oil.This energy situation accomplishes the rapid development of wind power.The installed capacity of wind power is increasing year by year in our country,the number of wind farms access distribution network is growing.The access of distributed wind farms makes original structure of electric power system get a lot of changes,has seriously affected the power flow of distribution network.Therefore,when a fault occurs in the power system,the access of distributed wind farms has a great influence on relay protection device of original distribution network.In our country,original distribution network usually adopts the form of two-stage current protection,when distribution network containing wind power occurs fault,the access of the wind farms will have an impact on the short-circuit current,and then lead to reduce the sensitivity of the protection,in severe cases will enable protection misoperation or maloperation,it poses a threat to the safe and stable operation of the system.Therefore,the study of the impact of wind farms access the distribution network on relay protection is imperative.The doubly-fed induction generator(DFIG)is the mainstream model at present,so this paper mainly takes DFIG as an example to study.First of all,this paper studies its working principle,mathematical model as well as the main characteristics,introduces the configuration of the distribution network and its relay protection,then analyzes theory of the impact of wind farms access distribution network on relay protection.Based on the theory analysis,this paper uses simulation and comparative analysis methods,takes the ETAP software as the platform analyzes the impacts on relay protection in three different cases with wind farms access to distribution network.The results show that different wind farms access capacity,point of failure and location of wind farms will have some impacts on the short-circuit current,the original two-stage current distribution network protection and automatic reclosing,and may even produce an island operation.The paper also analyzes and describes the impact of the original automatic reclosing device and the harm of the isolated island when wind farms access to distribution network.This paper studies on measures of the impact of wind farms access distribution network on relay protection,combines with the relevant literatures summarize four schemes,and analyzes the advantages and disadvantages of each.