Suppression Method of Low Frequency Oscillation When The Train Passing Through Neutral Zone

The low frequency oscillations of traction power supply system will induce mechanical resonance, which will destroy the voltage transformer of EMUs. To solve the problem, methods to suppress the overvoltage during the low frequency oscillation are provided. In case of low frequency oscillations, the contact line voltage in the neutral zone is mainly 1/3 power frequency (16.7Hz). After installing an RC suppression device in the neutral zone, when the EMU moves the neutral zone, the absolute value of voltage peak drops to below 20 kV. Compared with the situation where the suppression device is not connected, the absolute value of voltage peak is reduced by nearly 60%. This work gives foundation for the construction of the neutral zone of the contact line and the selection of the high-voltage equipment of the EMU.