超高压输电线路击距系数研究

Research on Striking Distance Factor for UHV Transmission Lines

为了更准确地对超高压线路进行防雷评价和计算,笔者依据长间隙放电与雷击放电的相似性,在实验室中建立击距系数模型,研究击距系数与相关因素的关系。实验结果显示击距系数与雷电流幅值大小并无相关性,但随着线路高度的增加而减小,运用数学分析方法得到击距系数K与杆塔高度h之间满足关系式:K=1.032 3-0.004 1×h。试验结果成功地解释了500 kV天广线某些地段现场屏蔽失效的问题,可以用于超高压输电线路防雷评价和计算。

According to the comparability of lightning discharge and rod-plane gap discharge, a simulated experiment was carried out to determine the relation between striking distance factor and other parameter. Experimental result indicates that striking distance factor K decreases with the increase of line height h. The relation between K and h achieved from experimental data is： K=1.032 3-0.004 1×h. Based on the electromagnetic theory, some accidents on real transmission lines are explained satisfactorily with this expression. Therefore, the expression can be used in lightning protection calculation of UHV transmission lines.