Mechanism of Low-Frequency Oscillation When Electric Multiple Units Pass Neutral Zone, and Suppression Method

This article addresses the problem of contact voltage increase caused by low-frequency oscillation train-grid system in phase-separation process EMUs. The establishes EMU-contact line-traction substation model, reveals mechanism oscillation, and ascertains relationship between phase angle when pantograph leaves line, oscillations. Methods to suppress overvoltage during are proposed. research indicated that a significant amplitude was observed neutral zone, line separation power supply fell within range 60–90° 240–270°. maximum reached 69.75 kV, there an occurrence where electrical takes place. During this network zone mainly operated at one-third frequency (16.7 Hz). However, after installing RC suppression device occurred, absolute value peak dropped below 37 kV as soon EMU entered electric separation. Furthermore, compared situations without connected device, nearly 30% reduction voltage. study provides basis for design selection high-voltage equipment EMU.