输电线路雷电绕击研究方法浅议

分析了几种雷电绕击研究方法或模型,如规程法、电气几何模型、先导发展模型、绕击概率模型。规程法应用简单、方便,对于一般线路的防雷屏蔽设计,能够满足要求;电气几何模型计算方法较为合理、简单,使用该模型来分析特、超高压线路或山区、同塔多回线路较其它模型更具优势;先导发展模型与绕击概率模型能够在物理意义上更合理地解释绕击现象,其计算过程相对复杂,暂不适于工程(如长距离线路)上大范围应用。重点对电气几何模型相关参数的选择进行了讨论,击距及击距系数的计算建议采用IEEE工作组推荐的关系式;对于年平均雷暴日在40左右的地区,地面落雷密度取值可定为0.1次/(km2.雷暴日);对于部分少雷或多雷区,结合国内35～220kV线路雷击统计数据,计算地面落雷密度建议采用CIGRE推荐的公式。

Approaching to Rotated Lightning Strike on Transmission Line

Experimental methods and models were analyzed,such as standard method,electrical geometric model(EGM),leader progression model(LPM) and shielding failure probability model.The standard method is easy for satisfactory use in lightning protective shield design for normal lines;electric-geometrical model is rational and easy for analyzing EHV and UHV lines,mountainous lines and multi-circuit lines.The leader progression model and shielding failure probability model give a reasonable interpretation of rotated flashover in physical mean,but they have rather complex calculation procedure and for time being can not be widely used for engineering application at long-distance transmission lines.Detailed discussion was made on relevant parameters of electro-geometrical model,from which the calculation of striking distance and striking distance factor was made using equation recommended by IEEE WG.For regions of mean annual thundery day more than 40,the thundering rate at ground surface can be taken as 0.1 time / km2 thundery day.Based on statistics of thundering number on 35～220 kV in China,the thundering rate for some thunderous regions can be calculated using equation recommended by CIGRE.