基于蒙特卡洛模拟的配电线路雷电跳闸率计算

Calculation of Lightning Trip-Out Rate of the Distribution Line Based on Monte Carlo Simulation

配电线路耐雷水平较低,雷电引发的配电线路跳闸事故频繁,需要合理估算线路雷电跳闸率并分析相应防护措施效果。通过EMTP软件计算线路雷电直击过电压和感应过电压,利用蒙特卡洛模拟法估算线路雷击跳闸率并与实际运行数据进行验证。讨论安装避雷线、避雷器的防护效果,分析不同雷电流波头时间和回击速度、不同避雷器安装方式、避雷线接地间隔对线路雷电跳闸率的影响。研究结果表明:利用蒙特卡洛模拟结合EMTP软件计算得到的线路雷击跳闸率与实际运行数据较为接近。线路雷电跳闸率随着雷电流波头时间的增大而降低,随着回击速度的增加而增大。安装避雷器或避雷线能够有效降低线路雷电跳闸率,但是防护效果受杆塔接地电阻影响明显,接地电阻越大,防护效果越差;线路避雷器安装档距越密,每基杆塔安装避雷器数量越多,线路雷电跳闸率越低;避雷线多点接地方式下,接地间隔越短,线路雷电跳闸率越低。需要尽可能降低杆塔接地电阻以减小线路雷电跳闸率。

Trip-out accidents of distribution lines caused by lightning damage occur frequently due to its low lightning protection level,it is necessary to evaluate the trip-out rate and take corresponding measures. Overvoltage caused by direct or indirect lightning was calculated in EMTP and the trip-out rate was estimated by means of Monte Carlo method and compared with practical data. Protection effects of installing arrester or ground wire were discussed. Influence of wave front time,current wave propagation,installation methods of arresters and grounding spacing of ground wire were analyzed. Research results show that: the trip-out rate calculated is in good agreement with the actual running data. Lightning trip-out rate decreases with the increasing of wave front time while increases with the increasing of current wave propagation speed. Lightning trip-out rate could be inhibited to some degree after installing arrester or ground wire but protection effects were significantly affected by the grounding resistance. Rise numbers and installation density of arresters may result in a decrease of lightning trip-out rate as well as shorter multi-point grounding spacing of the ground wire. In order to decrease lightning trip-out rate effectively,it is essential to reduce grounding resistance of poles.