计及山谷深度的输电线路雷电绕击率三维EGM研究

Three-Dimensional EGM Study on Shielding Failure Rate of Transmission Lines Considering Canyon Depth

相当多的输电线路建立在山谷之间,过去传统输电线路绕击率计算模型都没有专门针对山谷地形的研究计算,忽略了山谷独特地形显著减弱的屏蔽作用。建立了一个基于山谷深度的新型三维EGM,直接计算暴露弧面面积和保护弧面面积来研究输电线路绕击率。通过实例验证了新型三维EGM方法的有效性,并用该模型精确地证明了山谷地形是造成输电线路雷击跳闸多发原因之一。该方法摈弃了繁琐的微积分运算,主要应用于山谷地区,由于考虑到了山谷深度和地面倾斜角度,计算出的绕击率更加贴近实际地形,对工程实践具有指导意义。

A considerable number of high voltage transmission lines are built across deep valleys.In the past,no specific study was carried out on the valley topography in building models for calculating shielding failure rate of transmission lines,and the shielding effect of the unique topography of valleys was ignored.In this paper,a new three-dimensional electrical geometrical model(EGM)based on valley depth is established to directly study the transmission line shielding failure rate through calculating the exposed and protected cambered surface areas.The effectiveness of the proposed three-dimensional EGM method is verified through an example,and the valley topography is proved to be one of the main causes for frequent lightning trip-out of transmission lines.Avoiding complicated calculus operation,the proposed method is mainly applicable in mountain valley area.With consideration of the canyon depth and the slope angle of the ground,the calculated shielding failure rate is closer to the actual situation,which is significant for application.