Research On Overvoltage Analysis And Rotection Of Wind Farm Based On ATP-EMTP

With the advantages of the new energy industry in environmental protection,the development of wind power has been paid more and more attention by the whole society.The installed capacity of wind turbines is increasing year by year.Sincethe wind farm consists of the middle and low voltage power system with low insulation strength,the accidents caused by the over-voltage will impact the stable operation of the wind farm,which will cause the economic losses of the wind farm owners.As the wind power industry belongs to the emerging industry,the study of the overvoltage protection problem of wind farms is relatively limited.Therefore,this paper studies t some problems not covered by existing studies.The content of this paper are as follows:(1)Based on the characteristics analysis of wind farm collector network,a lightning strike model of wind farm collecting lines was established,including lightning current model,tower model,transmission line lightning protection model and insulator model.Simulation and analysis are made on the two cases of lightning counterattack and lightning shielding failure.The corresponding protection measures are discussed.The simulation analysis is made to improve the lightning flashover protection and lightning protection of lightning arresters.To improve the flashover voltage protection lightning arrester protection and lightning shielding make corresponding simulation analysis.The simulation analysis is made to improve the flashover voltage of the insulator to protect the lightning strike and the measures of lightning shielding.(2)The influence of wind farm grounding on lightning protection is analyzed.When the wind turbine blade is struck by lightning,the path of lightning current bleed is studied,and the influence of the grounding design of the single wind turbine unit on the lightning current discharge is discussed.Aiming at the mountainous wind farm with high resistivity,this paper compares the advantages and disadvantages of the measures to reduce the grounding resistance,and puts forward the applicable conditions to discuss the design of the grounding grid of the wind turbine group.(3)The mechanism of the reignition of vacuum circuit breakers was studied.A vacuum circuit breaker model was established in ATP-EMTP,and the simulation of the circuit breaker reignition process was verified.Then the model is applied to offshore wind farms.When the circuit breaker is reignited,different topologies of collector network will impact the amplitude and steepness of the overvoltage in offshore wind farms.The reignition of the circuit breaker and other factors impact the operation overvoltage of offshore wind farms.It is suggested that installing a suitable arrester after the vacuum circuit breaker can effectively restrain the ovevoltage of the offshore wind farm.