动车组合闸过电压故障机理兮析及仿真研究

Mechanism Analysis and Simulation Study of Closing Overvoltage Fault in EMU Circuit Breaker

[目的]动车组出分相时,断路器合闸产生的过电压会加剧高压设备的绝缘老化,研究合闸过电压的产生机理及影响因素对动车组主电路绝缘匹配和设备选型具有理论意义。[方法]结合动车组主电路结构和过分相过程,分析其正常运行方式下操作过电压的形成原因。考虑真空断路器合闸弹跳特性对过电压的特殊影响,建立动车组主电路仿真模型;对比研究动车组主电路合闸过电压特征,得出主回路状态动作时刻、动车组高压电缆参数、接触网参数及设备特性对过电压的影响规律。[结果及结论]极端状态下过电压峰值为工频电压峰值的2.39倍,接近《高速动车组整车试验规范》规定的2.4倍,在极端工况下产生的过电压会对动车组高压设备的绝缘性能产生影响,甚至导致击穿现象。因此,需采取如采用相控合闸技术控制断路器在目标相位闭合、选择单位分布电容较小的高压电缆、改进真空断路器的机械特性等相关措施进行防范,以有效降低动车组合闸过电压。

[Objective]The overvoltage caused by circuit breaker closing will aggravate the insulation aging of high voltage equipment when EMU(electric multiple units)passes neutral section.The research on the mechanism and influencing factors of overvoltage caused by circuit breaker closing provides significant theory for the insulation matching and equipment selection of EMU main circuit.[Method]Based on the EMU main circuit structure and the process of passing neutral section,the causes of overvoltage during breaker closing under normal operation is analyzed.In consideration of the special influence of vacuum circuit breaker closing bounce characteristics on overvoltage,a simulation model of EMU main circuit is established.By comparative study of the overvoltage charac teristics of EMU main circuit breaker closing,the influence patterns of main circuit action time,parameters of EMU high voltage cable,parameters of catenary and equipment characteristics on overvoltage are obtained.[Result&Conclusion]In extreme conditions,the peak overvoltage is 2.39 times the peak power frequency voltage,close to 2.4 times the stipulated value in the"Testing specifications of high-speed electic multiple unit on completion of construction".The overvoltage generated in extreme conditions will affect the insulation performance of the EMU high voltage equipment,even leading to breakdown phenomenon.Therefore,it is necessary to adopt the phase controlling closing technology for the circuit breaker to close at the target phase,select the high voltage cable with small capacitance of unit distribution,improve the mechanical characteristics of the vacuum circuit breaker and other relevant preventive measures,and finally to effectively reduce the EMU closing overvoltage.