中文摘要：

为探讨避雷线加装水平侧针对改善特高压交流输电线路雷电屏蔽性能的机理,开展了1：10和1：20特高压交流线路缩比模型下雷电屏蔽模拟实验及其放电观测,对实验结果进行了分析,并重点结合放电物理过程探讨了放电击中点的选择性和侧针屏蔽增效的机理。研究发现：下行先导初期发展过程中随机取向与各目的物迎面放电的竞争过程都与放电击中点的选择密切相关,下行放电与迎面放电也是相互作用与影响的;在各种间隙结构下,侧针的长度在大于对应间隙的临界电晕半径时才能起到明显的屏蔽增效作用。

英文摘要：

Lightning shielding failure is one of the biggest problems for UHV transmission lines to be solved. We discussed the important technology of increasing the lightning shielding efficiency of UHV transmission lines. To study this technology, a large amount of scaled simulation experiments were conducted, where the ground wire was installed with a horizontal short needle so as to increase the ground wire＇ s lightning shielding efficiency. A highspeed video camera was used to observe the discharging process, and with the observation results, the selectivity of discharging striking point and the mechanism of increasing the shielding efficiency by the horizontal short needle were analyzed . The analysis indicates that a close relationship between the random propagation direction of the initial downward leader and the competition of upward discharge on the objectives is found. And the downward leader and the upward discharge also have interactions on each other. In different gap configurations, the horizontal short needle would achieve the effects of increasing the ground wire＇ s lightning shield efficiency only when its length is larger than the corresponding critical corona radius of the ground wire.