输电线路地线上安装水平侧向短针的防绕击效果分析

为评估在地线上安装水平侧向短针对输电线路的绕击保护效果,提出并建立了三维的电气几何模型(EGM)来计算水平侧向短针对导线的保护距离,总结了其安装和使用的规律。对110～500kV典型杆塔的计算结果表明:水平侧向短针具有一定的保护作用,但每根水平侧向短针的保护距离有限,其防绕击效果较依赖于安装数量;并且水平侧向短针对导线的保护距离受到导地线相对位置的较大影响,仅对部分保护角和塔头尺寸都较小的单回线路有效;而对于同塔多回输电线路,水平侧向短针无法起到实质上的防雷保护作用;此外,安装水平侧向短针后还会对地线的机械性能产生负面影响。因此可以认为,水平侧向短针的绕击保护效果有限,适用范围较窄,限制了它在输电线路防雷保护中的应用,该防雷措施还有待进一步的提高与完善。

Analysis of Protection Effects of Using Side Needle on Ground Wires Against Shielding Failure in Transmission Line

To study the lightning protection techniques of overhead transmission line,and to estimate the protection effect of side needle which was used against lightning shielding failure,using a 3D electro-geometrical model(EGM),we calculated the protection distance of side needle,and summarized its installation rule on ground wires.The calculation results of typical 110~500 kV lines show that side needle has a positive effect against shielding failure,but the protection distance of each needle is small.As a result,a large number of side needles are required to be installed on the ground wires in order to achieve good protection effect against shielding failure.And the relative positions of overhead line’s conductor and ground wire have a great influence on the side needle’s protection distance,showing that the side needle can only protect the single-circuit lines with small shielding angle and small tower size.For multi-circuit transmission lines,the side needle can not substantially help protect lightning shielding,mostly because of the large scale of the multi-circuit tower.In addition,the side needle has a negative impact on lines’ mechanical properties after being installed on the ground wires.In conclusion,the side needle’s protection effect is insufficient and can only be used on the particular types of transmission lines,which limits its applications in lightning protection against shielding failure.So the lightning protection measures need to be further improved and perfected.