地形对输电线路最大绕击雷电流的影响

输电线路所处地形对最大绕击雷电流有着较大的影响,对改进的电气几何模型(EGM)中的导线高度和避雷线高度取值进行了重新定义,采用输电线路导线和避雷线任意点的对地高度取代原电气几何模型中的平均高度,以500 kV输电线路为例进行计算,计算结果表明,采用这种办法能够结合输电走廊地形情况区分出易击塔;当杆塔两侧均有山谷时,最大绕击雷电流增加,该基杆塔绕击引起闪络的可能性增大;最大绕击雷电流随着地面倾角的增大而减小,如果二者绝对值相等,地面倾角为负时的绕击雷电流更大。

Influence of Topography on Max Shielding Failure Lighting Current of Transmission Lines

The topography of the transmission lines have great influence on the max shielding failure lightning current.The height of the conductor and over head ground wire in the electric geometry model(EGM) was redefined,The average height of the geometric model was replaced by height at any point of transmission line conductors,and ground-line.Take the case of 500kv transmission line,the cauculation results show that it is possible to distinguish the easy strike tower by using this method combined with the terrain of transmission line corridor.The max current increases greatly where the tower passes the mountain valley,so the probability of flashover enhances.As the ground inclination increases,the max current reduces,but while the absolute value is equal,the current is greater at nega-tive ground inclination.