Study On Effect Of Earthing Resistance On EMU Radiation Emission

High-speed railway,which has advantages of high speed,high punctuality,low energy consumption,large transportation capacity and so on,has developed vigorously in China.As the key technology in the high-speed railway,EMU has a lot of electrification problems need to be solved since it started late in China,in which earthing system plays an important role.Nowadays,CRH2 and its follow-up EMU are all equipped with earthing resistance.However,there are few researches about the influence of earthing resistance on the radiation emission.Therefore,in this paper,we studied the influence of earthing on the radiation emission caused by over-voltage and large traction current.In the first place,this paper introduced the earthing system,and analyzed the influence caused by the earthing resistance on vehicle radiation.Then a model of earthing resistance was proposed where the parameters of RTC earthing resistance was extracted using Q3D exactor,and the relationship between AC impedance and frequency of the ground resistance was obtained.A comparison between the measurement results of grounding resistance and the simulation results was also carried out,the result of which has an important guiding significance on the following simulation.With different numbers,positions and impedances of the earthing resistance,the over-voltage and current of the vehicle body are different.To solve this problem,we constructed an equivalent circuit model which was based on the actual circuit structure of the EMU using Multisim.The equivalent circuit model can combine different transient,vehicle structure and earthing resistance correctly.By simulating under different operating conditions,such as normal working conditions and passing neutral sections,the law between earthing resistance and vehicle body over-voltage was obtained in this paper.Contrast experiments have also been carried out with and without earthing resistance,which proposed the best way of earthing model.Finally,we tested radiation emission of different earthing models for many times,and obtained the best earthing model according to the simulation results.