线路杆塔对雷电流分布和浪涌响应的影响

为解决现有回击模型在架空线路防雷性能计算时与实际情况分歧极大的问题,首先根据传统回击模型考虑线路杆塔与雷击通道以及杆塔与大地之间的反射,分析了杆塔对其电流分布及浪涌响应的影响,然后通过实例计算雷击电力杆塔雷击电流分布及其浪涌响应,总结出雷击通道回击模型以及杆塔电流分布的变化。分析表明,输电线路杆塔高度越高杆塔顶部浪涌响应越大,而杆塔波阻抗越小杆塔中入射雷电流越小,且最终相应地影响输电线路防雷性能。

Analysis of Influence of the Transmission Tower on the Lightning Return Stroke Current Parameters and Their Surge Response

The lightning protection is based on the lightning parameters which are obtained from the analysis of the measured lightning electromagnetic field produced by the traditional lightning return stroke model that is built for lightning striking to ground. But in engineering practice, the lightning parameters are not perfectly applicable because of the height of transmission overhead lines, its relative traveling wave reflection and the lightning channel being near to protection facilities, applicability study is needed. For example, using the traditional TL model of lightning to compute the lightning performance of the overhead lines, there is a great difference about the computing results among the different calculation methods. The reason is that the traditional model is based on lightning striking to the ground and lightning channel's radiation electromagnetic field of the far distance, neglecting the contribution of the static and induct field of the closest lightning, also the influence of elevated tower and its reflection. Based on the transmission line theory, this paper takes into account the reflections among the lightning channel, transmission tower and ground, analyzes the influence of the tower height and tower impedance on the currents distribution and the surge response in the tower. The analysis results show that the height of the transmission towers will influence their surge response, the higher tower has a big surge. And their surge impedance will affect lightning distribution in the tower and lightning channel, the lower impedance has a small current distribution in the tower. Accordingly both of the factors will influence the lightning performance of the transmission overhead lines. Finally those are validated by some computation cases.