Electromagnetic Transient Simulations And Analysis Of Emus Based On Electrical Coupling Model Considering Grounding System

China high-speed railway(HSR)brings passengers the experience of high-speed,convenient and comfortable for journey.In recent years,China HSR has developed rapidly,which benefits from comprehensive advantages of high-speed,large transport capacity,high punctuality,low energy consumption,environment friendly,tiny land occupation,safe and reliable,etc.As the core part of high-speed railway,Electric Multiple Units(EMUs)technology is closely related to the safe operation of HSR.Although HSR and EMUs have developed rapidly,there are still some challenges related to the grounding technology need to be solved.For example,when transient operation conditions occurs,the vehicle body voltage rises up quickly,casusing the uneven potential distribution of the vehicle body.Another example is the electric arc burning phenomenon at insulated rail joints in high-speed railway stations.This article will focus on these two problems.The voltage and grounding circulating current of vehicle body are important factors to safe operation of high-speed railway.In the operation process of EMUs,the electrical coupling of traction network loop circuits and the loop circuit constituted by vehicle body,grounding system and rail may have certain effect on the vehicle body voltage and grounding circulating current.This paper carries out the research on the loop electrical coupling of traction network on vehicle body earth system and added it into the electrical model of EMUs.At first,the coupling coefficients under different traction network power supply modes are derived.Then,taking CRH380 BL EMUs as an example,an equivalent vehicle-network coupling model is established by ATP-EMTP software and the model parameters are calculated in detail.In modeling,the controlled source is applied to simulate the electrical coupling.Based on the model,different transient operation conditions,such as,normal operation,pantograph lightning,pantograph detachment from catenary and passing neutral section devices,are simulated and analyzed.This paper also studies the arc burning phenomenon of insulated rail joints in high-speed railway stations.First,combined with the actual situation of station and the grounding mode of electric multiple units,the potential difference between the two ends of insulated rail joint is calculated before the wheel's arriving at the cut-off point.Then,transient analysis is carried out for the ordinary wheel and the discharge wheel,respectively.Each transient process is divided into three parts: the wheel reaches the cut-off point,bridges the cut-off point and generates an arc.The equivalent state-space model is established for each part of transient process.The corresponding voltage and current waveforms are calculated by the state-space model analysis using MATLAB software.Through substituting a theoretical arc model that combines the Cassie and Mayr models into the state equation,the waveforms of arc voltage and arc current for the ordinary wheel and the discharge wheel are achieved,respectively.Finally,according to the simulation results and theoretical analysis,the grounding optimization design is implemented aiming at suppress the vehicle body overvoltage,and solutions to suppress or eliminate the arc burning are carried out.