高速铁路高架段信号电缆雷电感应过电压计算研究

Research on lightning induced overvoltage of signal cable in elevated section of high speed railways

信号电缆外皮与芯线绝缘较弱,存在雷击感应过电压闪络造成信号系统损坏的风险。推导了雷电回击过程电磁场建模方法,对雷电回击电磁场激励下的信号电缆导线计算模型进行了研究,结合FDTD法给出了高架段信号电缆导线计算模型数值计算实现方法。计算了电缆芯线感应过电压,得到信号电缆芯线感应过电压大小与雷电回击通道到电缆的垂直距离、桥面距离地面的高度以及大地电阻率的关系。典型高速铁路高架桥结构中,当雷电回击电流一定时,电缆芯线感应过电压幅值随回击通道到电缆的垂直距离增大呈现非线性减小,电缆芯线感应过电压幅值随土壤电阻率增大呈现近似线性增大,电缆芯线感应过电压幅值随桥面距离地面的高度增大呈现近似线性增大。

The insulation between the outer skin and core of the signal cable is poor,and thus there are risks of damage to the signal system caused by lightning induced overvoltage flashover.This paper builds the electromagnetic field modeling for the lightning return stroke process,and studies the calculation model of signal cable wires under the excitation of lightning return stroke electromagnetic field.Integrated with the FDTD,a numerical calculation implementation method for the calculation model of signal cable wires in elevated sections is proposed.The induced overvoltage of the cable core is calculated,and the relationship of the magnitude of the induced overvoltage of the signal cable core with the vertical distance from the lightning return channel to the cable,the height of the bridge deck from the ground,and the earth resistivity is obtained.In a typical high-speed railway elevated bridge structure,when the lightning return current is constant,the induced overvoltage amplitude of the cable core decreases non-linearly as the vertical distance from the return channel to the cable grows whereas it increases approximately linearly with the rise of both soil resistivity and the height of the bridge deck from the ground.