3D Modeling Method And Optimal Design Of Integrated Grounding System For High-Speed Trains

With the increasing speed of High-speed trains,higher challenges are presented to the grounding system.Experience has shown that the relative movement between the train and the track causes instantaneous change of grounding circuit impedance,aggravates circumflux,leads to the increase of train body potential,and is easy to cause electrical corrosion of bearing and grounding carbon brush,burned out insulation section,abnormal or even damage of onboard sensors and other problems.In view of the background of circumflux and train body potential of High-speed trains and the deficiency of 2D model of High-speed trains grounding system,a more perfect 3D modeling of integrated grounding system of High-speed trains is carried out,and the optimization analysis of grounding system is carried out,so as to suppress circumflux and reduce train body potential.Firstly,this thesis introduces the traction power supply system,and analyzes the principle of the direct power supply method with return line used in this thesis.At the same time,it also analyzes and introduces the main circuit and grounding system of the High-speed trains,and determines the electric relationship between train body and high-voltage equipment.This thesis expounds the advantages and disadvantages of different modes of protective grounding and the problems found,and draws out the background of establishing a 3D grounding system model.Considering the influence factors of all aspects,combined with the measured data,the3 D circuit model of the integrated grounding system of High-speed trains is completed from the aspects of traction transformer,catenary,on-board transformer,high-voltage cable,train body,grounding system,rail and so on.At the same time,combined with the dynamic circumflux test of High-speed trains overboosting-cable condition and the static over-voltage test of High-speed trains raised pantograph and closed VCB,respectively from the dynamic grounding current trend,dynamic current amplitude and static voltage amplitude to the simulation results compared with the measured data of the three aspects,the High-speed trains integrated grounding system is proved accuracy and feasibility of the 3D model,and the main reasons for the error between the simulation and the measured results are analyzed.In addition,through the analysis of transient train body voltage simulation and actual measurement,the unique advantages of the3 D model of the integrated grounding system of the High-speed trains are verified,and more working conditions can be simulated and analyzed,and the characteristic analysis of the threedimensional model is completed.Finally,based on the 3D model of the integrated grounding system of High-speed trains,the effects of protective grounding impedance and radial parameters of train on circumflux and train body potential are analyzed.In order to suppress the circumflux and reduce train body potential,the Particle Swarm Optimization(PSO)is used to optimize the design of the grounding impedance of the original grounding mode of the standard EMU.In addition,the distribution mode of the grounding system of the High-speed trains and the resistance value of the protective grounding resistance of each axis are optimized.Finally,the radial parameters of the grounding system are optimized by using the advantages of the 3D model.After optimization,the ground current flowing through each protective ground of the train is reduced to varying degrees,and the distribution is more uniform,and the potential of the train body is also within the safety limit.