Mechanism of Low Frequency Oscillation when EMUs Passing Neutral Zone and Test on Field

Low frequency oscillation of the train-grid system in the phase-separation will induce the aging of the device insulation on train. To solve the problem an EMU-contact line-traction substation model has been established, which reveals the mechanism of low-frequency oscillation, and obtains the relationship between the separation phase angle of the pantograph with line and low-frequency oscillations. When system impedance meets the impedance of the train, there will low-frequency oscillation generating between the two, and the oscillation frequency in the 16.7 Hz, with amplitude more than 39 kV. The field test has been carried out on Beijing - Zhangjiakou High speed line, the low-frequency oscillation has been got and the model is validated. The research result can provide data support for the inhibition of low frequency oscillation.