Excitation Inrush Current And Overvoltage Suppression Method For High-speed EMUs Passing Phase Insulator

In recent years,with the rapid progress of China’s high-speed railway industry,the safety of high-speed EMUs has received extensive attention.The high-speed electrified railway traction network adopts segmented commutation power supply.Switching overvoltage and excitation inrush current is caused when the EMU circuit breaker is closed and opened.And overvoltage is caused when the high-speed EMUs pass through the phase insulator.These phenomena will cause accelerated aging and performance degradation of high-voltage equipment in EMUs.And it will endanger the safe operation of high-speed EMUs and the stable operation of electrical components in the traction power supply system.In severe cases,overvoltage and excitation inrush current may cause the feeder of the traction substation to trip and malfunction.Therefore,this thesis analyzes the transient process of high-speed EMUs passing phase insulator,explores the influencing factors of the transient process,and proposes methods to suppress the overvoltage and excitation inrush current of high-speed EMUs.Firstly,established the equivalent numerical model when the EMU circuit breaker was closed.Derived the mathematical formulas for primary side overvoltage and excitation inrush current of the EMU traction transformer when the circuit breaker was closed.Revealed the characteristic mechanism of switching overvoltage and excitation inrush current when the circuit breaker of the high-speed EMUs was closed.Established the equivalent numerical model when the high-speed EMUs entered and exited the phase insulator.Deduced the mathematical formula for the overvoltage of the pantograph of the EMU to the ground.Revealed the characteristic mechanism of the overvoltage generated when the high-speed EMUs entered and exited the phase insulator.Secondly,established the simulation model of the high-speed EMU passing through the phase insulator.Studied the simulation waveforms of overvoltage and excitation inrush current in the transient process.Obtained the characteristics of overvoltage and excitation inrush current of high-speed EMUs.For the switching overvoltage generated by the closing of the EMU circuit breaker the high-frequency oscillation overvoltage waveform was decomposed from it.And obtained the characteristics of high-frequency oscillation overvoltage.Through the test,obtained the measured waveforms of the switching overvoltage and the excitation inrush current of the EMU circuit breaker.Verified the applicability of the simulation model.Based on the simulation model of EMU circuit breaker closing,obtained the characteristics of the influence of the grid voltage phase on the switching overvoltage and the excitation inrush current,and obtained the characteristics of the influence of the EMU traction transformer residual magnetism on the excitation inrush current.Based on the simulation model of the high-speed EMUs passing through the phase insulator,obtained the characteristics of the influence of the grid voltage phase and the position of the electrical phase division on the overvoltage.Finally,compared the suppression effects of the lightning arrester with the closing resistance and the phase-controlled closing on the overvoltage and the excitation inrush current of the EMU circuit breaker closing operation.Compared the suppression effects of MOA device and RC resistance-capacitance device on the overvoltage of high-speed EMUs.The optimal scheme suitable for the operation of high-speed EMUs was given.