雷电通道水平电场影响因素分析

Analysis of Influence Factors of Horizontal Electric Field from the Lightning Channel

影响雷电通道产生的水平电场因素众多,分析其影响因素对电力系统的雷电防护具有重要意义。文中利用运动电荷电磁场方程求解得到闪电回击通道的水平电场和方位磁场,并结合C-R算法,得到了有限电导率地面上方的水平电场。依据运动电荷电磁场方程的特征分析了不同回击速度、不同距离、不同电导率对雷击产生的水平电场的影响。得出以下结论:水平电场随回击速度增大而减小;水平电场波形呈双极性特征且水平距离越大或电导率越小负向偏移越明显。这些研究结论为输电线路雷电过电压计算打下良好的基础。与其他方法相比,本文方法可以避免远距离电磁场计算中的震荡问题和积分方程的奇异问题。

Many factors affect the horizontal electric field from the lightning channel,it is of great significance to analyze these factors for the lightning protection of power systems.In this paper,the horizontal electric field and the azimuth magnetic field on the perfectly conducting ground from the lightning channel are evaluated by the field equations.Combining two components,the horizontal electric field over the finite conducting ground can be obtained through the C-R formula.Based on the characteristics of field equations of moving charges,the effects of different return-stroke speed,different distance and different conductivity on the horizontal electric field from the lightning channel are analyzed.The conclusion is drawn:The horizontal electric field decreases with the increase of the return-stroke speed;The horizontal electric field waveform is bipolar,and when the horizontal distance is larger or the soil conductivity is smaller,the negative offset is more obvious.These conclusions lay a good foundation for the calculation of lightning overvoltage on transmission lines.Compared with other methods,the proposed method can avoid the oscillation problem in the calculation of long-distance electromagnetic fields and can avoid the singularity problem of integral equation.