Research On Performance Optimization Of Emu Grounding System Considering Circulating Current And Overvoltage Balance

The unique wheel-rail coupled mobile grounding system of high-speed EMUs plays a key role in the driving safety of EMUs.However,unreasonable grounding settings cannot effectively reduce the transient overvoltage amplitude of the train body,which will cause equipment insulation breakdown.At the same time,the current entering the train body will deteriorate the electromagnetic environment for the normal operation of the on-board equipment and cause electrical corrosion to the bearings.The safety of the on-board personnel and the smooth operation of the in-vehicle network control system need to be guaranteed.Therefore,the research on the performance of the on-board mobile grounding system of the high-speed EMU needs to take into account the indicators of current and overvoltage.The purpose of optimizing and improving the grounding system is to improve the long-term service performance of the EMU.This thesis takes the circulation and train body potential problems caused by the dynamic grounding system of the rejuvenation series emus as the background,taking the “train-railcatenary” power supply and current return system in the suction line section and the electrical phase separation section as an example,the parameters of the on-board equipment of the EMU are investigated and the equivalent calculation of the power supply and return parts of the“train-rail-catenary” is carried out.Combined with the current and voltage waveforms collected by the field experiment,the mobile grounding system of the EMU is established in the pscad software.The dynamic simulation model of the EMU was compared,and the distribution law of the rail circulation generated by the mobile grounding system and the distribution law and influencing factors of the train body overvoltage in the EMU passing through the electrical phase separation section were explored.The dynamic simulation model was compared with the experimental results,and the distribution law of the train-rail circulation generated by the mobile grounding system and the distribution law and influencing factors of the vehicle body overvoltage in the EMU passing through the electrical phase separation were explored.In this thesis,the equivalent circuit of the overvoltage generated by the EMU passing through the electrical phase separation section is established first,and the theoretical derivation is carried out,the amplitude range and propagation law of the overvoltage on the vehicle body are studied,and it is found that the setting of the grounding axis and the grounding point have a great influence on the overvoltage of the vehicle body.Secondly,this thesis studies the current variation law and size distribution on each grounded axle when the EMU is running in the suction line section,and compares and analyzes the results of the established dynamic simulation model with the actual waveform,the main distribution area of the train-rail current circulation on the EMU is found,and the arrangement of the grounding axis and the grounding resistance parameters have a great influence on the circulation.Finally,this thesis explores the factors that affect the performance of the mobile grounding system of the EMU,mainly including the grounding resistance value and the number and position of the grounding axis.Combining the two indicators of ground axis current and vehicle body overvoltage,after comparing different grounding configurations,a comprehensive optimization scheme of coupled grounding system is given to limit train body overvoltage and train-rail current circulation.At the same time,based on the influence of grounding parameters,combined with the Particle Swarm Optimization algorithm,an optimal solution of grounding parameters that can be referenced is given.After optimization,the overvoltage amplitude of each vehicle body and the current amplitude of each grounding axis are in a more balanced range.Inside,the performance of the grounding system has been greatly improved.