The Research On Switching Overvoltage Simulation And Inhibition In High Voltage Circuit Of EMU

With the acceleration of railway electrification,EMU has become one of the main ways of rail transit in China.The operation safety of EMU is not only related to the personal safety of passengers,but also related to the safety of the equipment of EMU itself.The powerful traction power of the EMU comes from the high voltage power of the 27.5k V catenary.In the operation process of the EMU,it is necessary to constantly lift the pantograph,close the on-board transformer and other operations.These operations in the 27.5k V high voltage circuit,it is inevitable to produce electromagnetic transient shock,may appear overvoltage and overcurrent.It is of great significance to study overvoltage and suppression measures of high voltage closing of EMU so as to improve the technology of EMU and ensure the safe operation of EMU.This paper studies and analyzes the technical characteristics and main technical parameters of the high-voltage system and its electrical equipment of EMU,which lays a foundation for establishing the simulation model of high-voltage over-voltage closing of EMU.Study the basic structure and power supply characteristics of traction power supply system,understand the basic principle of AT power supply mode of high-speed railway,electrical system components of traction substation,main wiring and operation mode.These principles and wiring are necessary for theoretical analysis and calculation of the equivalent circuit of high voltage closing overvoltage in EMU.According to the nameplate,experimental data and other parameters of relevant equipment,the simulation model of the corresponding equipment in PSCAD was determined,and two kinds of over-voltage models of closing over-voltage of EMU group were built,namely,bow lifting over-voltage and no-load over-voltage.PSCAD simulation model based on the EMU rose bow process,studies the closing Angle and close distance,inductance and the EMU traction network resistance switching high voltage cable length equivalence factors on rose bow over voltage,over current,and the influence of duration of oscillation,and further study the pantograph series inductance and resistance and parallel RC filter suppression method,the simulation results show that these methods can effectively improve the EMU arch rise of the electromagnetic transient process.Based on PSCAD simulation model of the EMU no-load closing process,switching Angle is studied,the traction transformer entrance capacitance and core remanence’s influence on the no-load switching-in electromagnetic transient process,and analyzes the dynamic EMU of the shortage of the arrester set,in order to make up for the surge arrester is not perfect,to restrict the EMU switching overvoltage suppression measures are: add filter on the roof;Temporary series resistor on cable head when raised by pantograph.In addition,in order to suppress the excitation inrush current when the on-board transformer is closed,the series temporary resistance when the on-board transformer is closed,or the control of the closing phase Angle,both of which have positive effects.Simulation results show that the proposed measure to suppress overvoltage and inrush current of high voltage closing of bullet train has a good effect.