考虑雷电入射角后电气几何模型的改进  

Improvement of Electro-geometric Model with Considering Lightning Strike Angle

作　　者：李瑞芳[1] 吴广宁[1] 曹晓斌[1] 马御棠[1] 刘平[1] 

机构地区：[1]西南交通大学电气工程学院,成都610031

出　　处：《电瓷避雷器》2009年第4期23-26,共4页Insulators and Surge Arresters

基　　金：青年教师科研起步项目(编号:2008Q015)

摘　　要：电气几何模型法是计算输电线路绕击率的有效方法之一。传统的电气几何模型法未考虑雷击入射角方向,直接假定雷击的方向为竖直向下,通过求出电气几何模型中保护弧、暴露弧在水平面上的投影最后得出绕击率。为更接近于实际,假定雷击入射角在一个平面内进行变化,首先在每个特定的雷击入射角下将保护弧、暴露弧分别在垂直于雷击入射角的方向上进行投影,通过计算求出与特定入射角对应情况下的绕击率,再将雷电入射角的概率和某一入射角下对应的绕击率综合考虑,得出考虑雷击入射角概率后绕击率的计算式;并以某平原500 kV交流输电线路为例,计算了雷电流为22 kA,考虑入射角φ(0～π/2)概率后绕击率为9.97%。改进后的计算方法更能反应雷击的实际情况,加强了输电线路屏蔽性能的研究。Electro-geometric model （EGM） is one of the effective methods to compute shielding failure rate of transmission lines. Lightning strike angle was not considered in traditional EGM, which directly supposed that the direction on lightning strike is vertically downward. Shielding failure rate was obtained through calculating projecting length of protection arc and exposure arc. In order to make the EGM more close to practical situation, in the paper it was supposed firstly that lightning strike angle varies in a plane. To each definite angle,protection arc and exposure arc are projected on direction which is vertical to the lightning strike angle. Then shielding failure rate on each definite lightning strike angle was calculated according to the length of protection are and exposure arc. Considering comprehensively the value of shielding failure rate on each definite lightning strike angle and probability of lightning strike angle, the formula is given to calculate shielding failure rate after considering probability of lightning strike angle. As an example, for a 220 kV substation located at plain, a probability rate 9.97% of shielding failure was obtained at 25 kA of lightning current and strike angle φ（0～π/2）. The improved calculating method is closer to simulate practical situations because of considering lightning strike angle, which is useful to research on the transmission line shielding failure rate.

关 键 词：输电线路 雷击入射角 电气几何模型 绕击率 

分 类 号：TM863[电气工程—高电压与绝缘技术]