Electric Field Simulation And Structural Optimization Of Cable Termination And Line Side Cubicle For Locomotive In Alpine Region

China is a country with a vast territory,the ambient temperature of which varies greatly with different regions in winter,the minimum temperature in some areas can reach below-40?.In the western region with high altitude and bad natural environment,the electric locomotive face challenges of severe climatic environment during running.The electric field is unevenly distributed in the high voltage cable terminal,partial discharge can be formed easily,and the unevenly distributed electric field can even cause insulation breakdown.In the specially designed plateau type electric locomotive,the high-voltage equipment on the roof of the train are integrated in the train with cabinets,which is defined as the line side cubicle.Because of the special operating environment and the particularity of equipment,the existing standards of the cubicle cannot be used when designing the line side cubicle.Therefore,it has great great significance for the electric field simulation of the cable terminal and the important components in line side cubicle.In view of the special situation of railway running in the alpine region,a preliminary analysis of the broken-down cable terminal in the line side cubicle and reason speculated for the discharge based on the result of disassembling the broken-down cable terminal and condition of the broken field,are given in this paper.and tests of the basic electrical parameters and materials are given in this paper.Besides,this paper gave a basic electrical parameters test for the materials of both the broken-down cable terminal broken in the field and the new cable terminal without breakdown shared the same model,which includes the relative dielectric constant and the resistivity.Based on the insulation structure of cable terminal,the three-dimensional simulation model of the vehicle cable terminal is established.The electric field simulation analysis,under both normal circumstances and circumstances with air gap,of the fault cable terminal in the line side cubicle is carried out by COMSOL Multiphysics,so as to study the extension of discharge channel and breakdown mechanism of the fault cable terminal in the alpine region.In this paper,the partial discharging test and voltage-withstand test in a low temperature to simulate the field environment is also carried out.The experimental results show that the discharge amount of cable terminal at low temperature is much greater than that at room temperature,and the cable terminal is breakdown in voltage withstand test at low temperature.The simulation and research results show that the operating environment temperature is the main factor leading to the generation and extension of the cable terminal discharge channel.This paper uses Pro/Engineer Wildfire5.0 to establish the simplified model and simulation model of locomotive line side cubicle.This paper researches the distribution of easy breakdown point of the locomotive line side cubicle by analyzing the dynamic electric field under the normal voltage and typical over-voltages cases.The simulation results show that there are distortion of the electric field of locomotive line side cubicle,which could have a bad effect on the safe operation of the line side cubicle.Based on the simulation results of the primary line side cubicle and the related standards,this paper proposes an optimized structural layout for locomotive line side cubicle improves the electric field distortion by comparing the simulation results of the new model and the old one.