Study On The Intrusion And Propagation Characteristics Of Lightning Waves In High Speed Electric Multiple Unit

High speed railway has gained rapid development in recent decades because of its high speed,dense departure,large-capacity and so on.In order to achieve the pursuit of high speed and passengers' comfort,viaducts are widely adopted in high-speed railway system in China.Due to the high erecting height of the contact network,the differentiation design in existing lightning protection for traction power supply systems and lack of focalization to lightning protection of contact network in some special areas,high speed railway catenary has a higher probability of direct lightning strike.When a feeder or a bearing cable is struck by lightning,the traction power supply system will be threatened by a lightning overvoltage.If the lightning stroke is closer to the EMU(Electrical Multiple Unit),the lightning overvoltage will spread to the electrical equipment of the EMU,and the safety and reliability of the EMU will be affected.Therefore,it is necessary to explore the characteristics of lightning overvoltage and the propagation of lightning overvoltage on the EMU when lightning strikes at catenary.According to the geometric structure of the contact network of high speed railway,the parameters of the wire and the flashover characteristics of the pillar insulators,PSCAD/EMTDC was used to establish the electrical simulation model of catenary suspension system,and the effect of the wire impulsive lightning corona on lightning overvoltage wave was considered.In order to fully consider the characteristics of lightning overvoltage that is transmitted to the EMU when the lightning strikes the overhead contact line,the paper discusses the lightning overvoltage situation of the EMU high-voltage electrical equipment when lightning feeder and lightning bearing cable,respectively.Based on the structure of the EMU high voltage electrical system and its grounding system,a simulation model considering the nonlinear performance characteristics of the arrester was established.Based on the simplified internal structure of the high voltage cable,the frequency change parameter model was established,and finally the resistance and inductance model of the EMU body is built.The bow rising surge overvoltage of the EMU body was tested on site to verify the effectiveness of the simulation model on the study of surge overvoltage of the EMU.On the basis of the simulation model of the established traction network and the EMU,the lightning wave characteristics and the range of transformers lightning overvoltage are analyzed.In addition,the distribution characteristics of lightning overvoltage in high voltage equipment,high voltage cable metal shield and car body as the arresters is in conducting state is studied,and the influence of the residual voltage of arrester and its installation position on overvoltage is also explored.