Research On Overvoltage And Suppression Methods Of Emu’s Body Based On Improved Mayr Arc Model

With the development of high-speed EMUs,the operating speed of EMUs is getting higher and higher,and the vibration between the pantograph and the catenary is intensified due to the irregular contact line erection and uneven track during the train operation,which further causes frequent off-line arcing,which causes the EMU body to be frequently subjected to overvoltage shocks.Frequent overvoltage shocks can cause damage to on-board equipment,such as burning speed sensors,and accelerate the insulation aging of on-board electrical equipment,which seriously affects the EMUs safe and stable operation.Aiming at the problem of arcing overvoltage in the EMU,it is necessary to study the influence of the pantographcatenary arcing process on the overvoltage of the vehicle body and the suppression method of the overvoltage.This article introduces the main power supply system of the EMU and the grounding system of the EMU,and analyzes the types of current protective grounding systems and their advantages and disadvantages.Combined with the high-speed railway traction power supply system,the generation mechanism of the vehicle body overvoltage is analyzed through theoretical calculations.Improvements to the classic Mayr arc model and established a simulation model of EMUs body overvoltage considering pantograph-catenary arc burning process,and analyzes the influence of the arcing process on the overvoltage of the vehicle body of the EMUs,and obtains the amplitude,duration,the distribution characteristics and spread law of the overvoltage of the vehicle body,and the influence of running speed on the over-voltage of the vehicle body was studied.The correctness of the arc model is verified by establishing an arcing test platform,the field test verified the reliability of the overvoltage simulation model.Based on the over-voltage simulation model of the EMU body,the protective grounding parameters,the number of protective grounds,the grounding layout of the roof high-voltage cable shield,and the series inductor grounding of the roof high-voltage cable shield were studied,the law of influence of the vehicle body is given.It is suggested that the front and rear of each vehicle body should have at least one grounding point,and the reasonable range of the inductance value of the series inductor of the shielding layer is given.Combined with the above research results,a comprehensive overvoltage suppression method is proposed to increase the protection grounding of the pantograph vehicle,the ground point of the highvoltage cable shielding layer is set in the middle of the vehicle body,and the series inductor of the high-voltage cable shielding layer is grounded.When a 20μH inductor is connected in series in a shielded ground circuit,the overvoltage on the top of the No.3 vehicle body and the bottom of the vehicle body was 1945 V,which was 57% lower than before the optimization.The overvoltage on the bottom of the vehicle body and the shaft end was 1821 V,which was decreased by 52% before the optimization,and the over-voltage of each vehicle body dropped below 2k V.The research results show that the suppression scheme can effectively reduce the over-voltage of the EMU body,which has guiding significance for practical engineering applications.