输电线路雷电绕击率的三维计算方法

Three-Dimensional Calculation Method on Shielding Failure Rate of Transmission Lines

绕击率是计算输电线路耐雷水平的重要参数,传统计算方法以导地线平均高度估算线路的绕击率,存在一定的误差,难以反映线路绕击的真实情况。本文对传统方法进行改进,得出基于三维曲面的输电线路雷电绕击率的计算方法。该方法以导线的高度为变量,给出了绕击率随垂直于线路的截面与杆塔间距离的变化规律及计算式,通过将该计算式沿线路档距方向进行积分,得出单个档距三维模型的雷电绕击率计算式。本文的分析基于电气几何模型,但该方法同样可以应用于先导法或其他分析方法,可得到基于不同方法的输电线路三维绕击率计算式。该方法从三维空间角度对输电线路绕击率进行考虑,因此更能反映输电线路的真实雷电绕击率,为提高输电线路耐雷性能评估的精度提供了基础。

Shielding failure rate is an important parameter to calculate lightning withstands level. Traditional method estimated shielding failure rate by mean value of height about conductor wires or shielding wires. Some inaccuracies existed and real situation was difficult to express. Traditional method is extended in this paper. The new method is presented based on three-dimensional bend to calculate shielding failure rate of transmission lines. This method obtains formula with the height of the conduct wires as variable and shows change rules of shielding failure rate with change of distance between the section vertical to transmission lines and tower. By means of integral to this formula, the formula about shielding failure rate of the whole span spatial model is obtained. Analysis in this paper is based on electro-geometric model（EGM）, but also compatible for leader propagation model （LPM） or other method. Formula of shielding failure rate to different method can be obtained. Because of the method presented in this paper considering three-dimensional space, data from which are closer to real situation comparing with traditional EGM. It can be useful to improve precision about calculating lightning withstands level of transmission lines.