为了更有效地利用雷电定位系统数据评估输电线路的雷击跳闸风险，以东莞地区 1999—2008 年雷电流幅值数据为例，分析了规程推荐公式、IEEE 推荐公式及其改进公式的拟合曲线与实际雷电流幅值概率分布的偏差，在此基础上提出了雷电流幅值概率分布函数的分段拟合方法，并进行了连续性修正．最后，分别采用规程推荐公式、IEEE 改进公式和文中拟合公式计算东莞地区 110kV、 220kV、 500kV 三个电压等级下的输电线路雷击跳闸率，并与实际值进行对比． 结果表明: 采用文中方法得到的雷电流幅值概率分布函数曲线与自然概率曲线的相关性最强，仅牺牲了分段点附近的相关性; 采用文中分段拟合方法计算得到的 110kV、 220kV 电压等级输电线路雷击跳闸率与实际运行数据较相符，而对 500kV 电压等级线路雷电跳闸率的计算存在偏差．

In order to make full use of the lightning location system to assess the lightning trip- out risk of transmis-sion lines,the lightning current amplitude data of Dongguan area from 1999 to 2008 were used to perform a statisti-cal and comparative analysis,analysing that the fitting curves respectively obtained by the regular method and theIEEE recommended formula and the improved IEEE formula all deviate from the actual current amplitude probabili-ty distribution.Then,a sectioned fitting method of probability distribution function for the lightning current ampli-tude was proposed,followed with a correction of the continuity of functions.Moreover,the lightning trip- out rate of110kV,220kV and 500kV transmission lines for Dongguan area were calculated respectively by the regular meth-od,the improved IEEE formula and the proposed fitting method.The results were finally compared with the mea-sured ones.It is demonstrated that the proposed method helps to obtain a probability distribution function which isclosely correlated to the natural probability curve,only with a sacrifice of correlation near the sectional point; andthat the lightning trip- out rate obtained by the proposed method is consistent with the actual operational data of110kV and 220kV transmission lines,but deviates from that of 500kV transmission lines.