高速铁路弓网离线过电压对车体电位的影响

Impact of Pantograph-Catenary Off-Line Overvoltage on Car Body Potential in High-Speed Railway

基于现场采集的阻抗参数,建立高速铁路“网-车-轨”牵引供电系统等效电路模型,进而建立包含弓网电弧仿真模型的“网-车-轨”三位一体的牵引供电系统有限元模型,并通过与实测升弓过电压进行对比,验证有限元模型的可靠性;将由等效电路模型计算得到的电压激励加载在有限元模型上,调整列车运行速度和弓网离线时间,分析其对弓网电弧发展的影响,研究弓网中离线和大离线工况下的过电压特性和不同接地方式下的车体电位和磁场分布。结果表明:当列车运行速度较大且弓网离线时间大于200 ms时,易发生弓网完全离线,并产生较高车体过电压;车速为300 km·h^(-1)时,弓网离线导致的车体过电压达6.45 kV;车底主要区域对地电位高于2 kV,磁感应强度峰值为3.8 mT;通过增加3车保护接地数量,提高车体过电压的泄放能力,使车顶-轴端过电压降至5.47 kV,最大磁感应强度降至2.6 mT,车底区域磁场分布更加均匀,有效地抑制了车体过电压,改善了车载设备的电磁工作环境。

Based on the impedance parameters collected in the field,an equivalent circuit model of the“catenaryvehicle-track”traction power supply system of high-speed railway is established.Thus,a finite element model of the“catenary-vehicle-track”trinity traction power supply system including the pantograph-catenary arc simulation model is established.The reliability of the finite element model is verified by comparing with the measured overvoltage during pantograph lifting.By applying the voltage excitation calculated from the equivalent circuit model to the finite element model,the impact of train running speed and pantograph-catenary off-line time on the development of pantograph-catenary arc is analyzed.This study investigates the overvoltage characteristics in pantograph-catenary off-line and large off-line conditions,as well as the car body potential and magnetic field distribution under different grounding methods.Results show that when the running speed of train is high and the pantograph-catenary off-line time exceeds 200 ms,the pantograph-catenary is prone to occur complete offline and produce high car body overvoltage.When the train speed is 300 km·h^(-1),the car body overvoltage caused by pantograph-catenary off-line is 6.45 kV.In the main area of train bottom,the ground potential exceeds 2 kV,and the peak magnetic induction intensity is 3.8 mT.By increasing the number of protective grounding on the third carriage,the dissipation capability of car body overvoltage is improved,which reduces the roof-axle overvoltage to 5.47 kV and the maximum magnetic induction intensity to 2.6 mT.The magnetic field distribution in the train bottom area becomes more uniform,which effectively restrains the car body overvoltage and improves the electromagnetic working environment for onboard equipment.