大地电导率对架空线路雷电感应电压的影响

Influence of Ground Conductivity on the Lightning-induced Voltage on an Overhead Line

为了研究大地电导率对架空线路雷电感应电压的影响,首先基于MTLE回击模型,采用时域有限差分法计算不同大地电导率下雷电回击通道附近感应的水平电场和垂直电场。接着将计算出的水平电场作为输入参量,从传输线方程出发,运用Agrawal模型进一步研究雷电感应电磁场与架空电力线的耦合效应,改变大地的电导率,分别计算架空电力线上中点和终点处的感应过电压值。结果显示感应电压上升时间随着大地电导率的增大而缩短,架空线终点处感应电压的峰值随着大地电导率的增大而增大,而架空线中点处感应电压的峰值却随着大地电导率的增大而减小。

In order to analyze the effect of ground conductivity on lightning- induced voltage on an overhead line, adopting MTLE return stroke model, the horizontal and vertical electric fields generated by lightning are evaluated by use of finite difference time domain（FDTD） method firstly. Then as an input component, the horizontal electric field is used in calculation of lightning-induced voltage on an overhead line. In this paper, use is made of the model proposed by Agrawal et al., based on the transmission line theory for field-to-transmission line coupling calculations. Lightning-induced voltages both at middle point and terminal point of the overhead line are evaluated respectively as the change of ground conductivity. The results show that, the rise time of voltage decreases as the increases of the ground conductivity. The amplitude of induced voltage at terminal point increases with the ground conductivity increasing, but opposite at middle point of overhead line.