Study On The Characteristics And Effect On Overvoltage Of High-speed EMU In The Case Of Lighting Catenary

Railways,power systems,telecommunications and other areas are the hardest hit areas.As the EMU is in motion,the distance between the contact line arrester is changing,When lightning catenary,if EMU is far away from the arrester on the catenary,befor the reflected voltage of the arrester is not transmitted to the EMU position,the overvoltage of the arrester is higher than ihs threshold,lightning current has being flowing into the car-body,may cause excessive voltage,seriously effect on the traffic safety.Therefore,it is necessary to study and analyze the overvoltage and its influence mechanism of the high speed EMUs.This paper analyzes the cause and mechanism of the overvoltage generated based on catenary and EMU circuit,and a overvoltage simulation model in the situation of lighting strike catenary has been built by software Pspice.Through the model,amplitude,duration,transmission and other characteristics of the horizontal and vertical overvoltage on the carriages are analyzed,find the influencing parameter of the overvoltage,also the suppression methods.The main results are as follows:The lightning current invades the EMU with the arrester,the maximum overvoltage all carriage is on carbody three where the arrester was equipped on,All the voltage waveform is similar that reached the maximum value during the lightning rise period,then damped oscillation and decay to half of the maximum at the second cycle.The farther away from the arrester,the lower the overvoltage of the carriage is.The lightning current parameters,arrester installated position and grounding system have different effects on the overvoltage of carbody.Amplitude and wave front time of lightning current have a great influence on overvoltage amplitude,but the half peak time only affects the coda attenuation.Carriage over-voltage,which is seriously influenced by the inductance of grounding resistor,is related to the position of the vehicle.The increased distance from the pantograph leads to the greater influence on carriage over-voltage.The effect of inductance on transverse and vertical overvoltage is different,the vertical overvoltage increases with the increase of inductance,while with the increase of the inductor,the transverse overvoltage increases first and then toward stabilization.Increasing the grounding point will reduce the overvoltage to some extent.The closer the arrester to the grounding point is,the greater the influence.The closer the arrester installation point to the middle position of the EMU,the smaller the overvoltage is formed.Namely,overvoltage reach to the minimum as arrester installed on the carbody four and to the maximum as arrester installed on the car 1.Because of the uncontrollable current,it can not be used as the basis for restraining the overvoltage of the carriage.According to the influence of lightning arrester position and grounding system on over-voltage,the suppression method is considered.Considering the optimization of the location of the arrester and grounding system of only partial carriage include the grounding point and mode.This will be able to suppress the overvoltage of all car body within 2 kV.Above conclusions provide theoretical basis for further analysis of lightning carriage over-voltage.