山火引发输电线路跳闸事故的统计与分析

Statistical analysis of wildfire accidents inducing flashover of transmission lines

通过对部分引发输电线路跳闸的火灾事故进行统计以及对典型火烧迹地的跳闸事故进行考察,分析山火发生的次数、跳闸率、地理位置、过火区域地形地貌等,探讨引发线路跳闸的潜在山火类型、形成过程、影响因素和特性参数以及跳闸输电线路的放电特性参数。结果表明:易引发跳闸的山火类型依次为中高速中高强度的地表火、树冠火、冲冠火和地表火转化的树冠火;火灾基本为上山火,易形成高火焰、高热量、高温度、高浓度(烟尘粒子和带电质点)的易导致线路跳闸的环境条件;发生跳闸时输电线路主要放电部位为子导线,放电方式依次为对树、相间和对地;在中高强度火灾条件下放电距离突破了输电线路正常运行所需安全间隙,产生流注而发生跳闸。

Based on the statistics of some flashover of transmission lines induced by wildfire and the field survey of typical burned area, fire frequency and flashover ratio, geographical information of fire region, brief status of wildfire and flashover accidents were analyzed, the types, evolution process, influencing factors, and property parameters of potential wildfires, and the discharge characteristics of transmission lines were explored. Results show that ground fires, crown fires, red crown fire and crown fire converted from ground fires are easy to lead to the flashover of transmission lines. Most fires are upswept and easy to ambient conditions prone to induce flashover as high flame height, high thermal output, high temperature and high concentration （smoke particles and electric mass points）. The discharge happens mainly at subconductors, main discharge patterns are conductor-to-tree, conductor-to-conductor and conductor-to-ground. Under conditions of wildfires with medium and high intensities, the discharge distances can exceed the safe air gaps for normal operation, this can form stream with large amounts of charged mass points to bring flashover.