Research on protective grounding current distribution of 380B EMU based on AT power supply mode

At present, the EMU in China adopts dispersive grounding system, which causes reflux current among grounding points and potential rising of car-body will threaten the safe operation of the EMU. The problem of EMU grounding attracts wide attention from relevant enterprises and universities, while now there are no uniform standards of EMU grounding all over the world. In this paper, a test of protective current waveforms was carried out and a model and overhead contact system of 380B EMU based on the AT power supply mode was established by Simulink software to study the distribution of protective current. The results show that the amplitude and phase of protective current change periodically due to the influence of mid-point connections and the period is about 20s. The amplitude of protective current gradually increases when train approaches the mid-point connections and subsequently gradually decreases when train departs from it. The max amplitude of protective current is 170A when first or last shaft of EMU goes through the mid-point connections. In addition, the phase of protective current relates to the position of the train, the holistic regularity is that when the EMU locates the middle during the mid-point connections, the current flows into the car body from the protective grounding of middle car and flows out from both that of No.1 car and No.8 car, when the EMU locates side of the mid-point connections, the current flows into the car body from the protective grounding which far away from the mid-point connections and flows out from the No.1 shaft of No.1 or No.8 car which near by the mid-point connections. Furthermore, adding a grounding resistance with 0.1Ω on the shaft of No.1 and No.8 car can reduce the amplitude of all protective currents effectively. The conclusions above could provide theoretical basis for designing better grounding schemes.