雷电流幅值概率分布特征及累积概率分段修订

Characteristics of Probability Distribution for Lightning Peak Current and Segment Revision for Cumulative Probability

为了研究雷电流幅值概率分布特性及雷电流幅值累积概率曲线拟合效果,以满足防雷工程设计和雷击风险评估工作需要,根据湖北省2007—2013年雷电定位系统（Lightning Location System,LLS）监测的雷电流幅值资料,统计分析了雷电流幅值累积概率和密度分布特征。结果表明：正闪和负闪电雷电流幅值累积概率分布差异较大,负闪电雷电流幅值累积概率分布比正闪电更集中,负闪和总闪电的雷电流幅值累积概率分布曲线基本相同;雷电流幅值强度大部分集中在10~50kA。根据IEEE推荐的雷电流幅值累积概率分布表达式,拟合了不同极性的雷电流幅值累积概率分布公式。雷电流幅值小于110kA时,采用IEEE拟合公式计算的雷电流幅值累积概率与实测值间的相对误差较小;雷电流幅值大于110kA时,计算值与实测值间的相对误差随雷电流幅值的增加而增大。采用该文给出的分段修订公式,计算在110kA以上的雷电流幅值累积概率与实测值间的相对误差在2%以内。由IEEE推荐表达式拟合雷电流幅值累积概率分布和概率密度分布时,负闪和总闪电雷电流幅值累积概率分布拟合效果明显比正闪电好,其原因可能与正闪电分布特性有关。

In order to study the probability distribution characteristics of lightning peak current and the fitting effectiveness of cumulative probability for peak current,and the demands of lightning protection engineering design and lightning risk assessment,this article utilizes the peak current data observed by the LLS（Lightning Location System）from 2007 to 2013 to analyze the distribution characteristics of probability and density for peak current.The results show that there is a big difference in the cumulative probabilities for different polar peak currents;the distribution of negative lightning is more concentrated than that of positive lightning;the distribution curve of peak current cumulative probability for negative lightning is basically the same with the total one;and the peak currents of lightning are concentrated mostly in 10 to 50 kA.According to the distribution expression suggested by IEEE for cumulative probability of peak currents,this article fits the distribution expression of cumulative probability for different polar peak currents.The statistical analysis shows that when the peak current is less than 110 kA,the relative error between fitting cumulative probability calculated by the fitting expression of IEEE and the actual one is small,but when the peak current is above 110 kA,the error increases with the peak current.According to the segment revision expression given by this article,with the peak current being above 110 kA,the error between calculated cumulative probability and the actual one is less than 2%.When use the expression suggested by IEEE to fit the cumulative probability and density of peak currents,the fitting effectiveness for negative lightning and total one is better than the positive one.The reason seems to be connected with the distribution characteristics of positive lightning.