Research Of Transient Over-voltage Suppression Technique For EMU Auto-passing The Neutral Section With On-board Switch Closed

When an EMU automatically passes the neutral section for phase isolation, the transient over-voltages are prone to be caused on the OCS (overhead contact system) by the switching of vacuum breakers, which can result in the burn broken of the contact wire, the trip off of the traction substation feeder or the damage of the EMU on-board transformer, and then directly threaten the operation safety of the traction power supply systems and the EMUs.The thesis firstly introduced recent research about overvoltage caused by EMU auto-passing the neutral section with on-board circuit breaker closed, then calculated its related electrical parameters and established its equivalent circuit model. Based on field test at the ring test line of China Academy of Railway Sciences, we analyzed the transient process of EMU auto-passing the neutral section and theoretically calculated the overvoltage.Then the transient process was simulated by PSCAD/EMTDC. And the comparison of simulation and measurement and theoretical calculation showed that the relationship between the peak overvoltage and the closing angle of the OCS voltage are almost the same.Finally, to suppress the overvoltage caused by EMU auto-passing the neutral section, a RLC damping filter can be installed in the neutral section. Both the simulated and measured results have shown that, after installing RLC damping filter in the neutral section, the closing overvoltage caused by EMU auto-passing the neutral section has been effectively suppressed.