考虑火焰分区的植被火条件下导线-板间隙击穿电压研究

Breakdown Voltage of Conductor-plane Gap Under Vegetation Fire Condition Considering Division of Flames

架空输电线路走廊山火可显著降低线路空气间隙绝缘强度,严重威胁电网的安全稳定运行。利用模拟山火试验平台研究了杉木火焰全桥接和非全桥接时的间隙击穿特性,并根据间隙击穿放电过程和火焰的形态将间隙划分为火焰连续区、火焰不连续区和烟雾区,通过回归分析得出了火焰非全桥接时的间隙击穿电压的拟合表达式。研究结果表明:火焰全桥接时间隙的击穿特性主要受火焰连续区本身特性差异的影响,平均击穿电压梯度最低可降低至纯空气间隙的18.0%;火焰半桥接时烟雾区承担了大部分电压,火焰的特性差异对火焰区的击穿特性影响不明显;不同植被垛密度下的击穿电压随间隙距离的增加差异会减小。研究成果可为山火条件下架空输电线路空气间隙击穿风险评估和防护提供参考。

Forest fires in the right of way of the overhead transmission lines may greatly reduce the insulation strength of transmission line air gaps,which seriously affects the safe and stable operation of the power grid.The breakdown characteristics of the China fir full flame gap and incomplete flame gap are studied by forest fire simulation experiment platform in this paper.The gap is divided into three parts:the flame continuous area,the flame discontinuous area and the smoke area according to the discharging mechanism and the flame shapes in the gap.The fitting expression of the breakdown voltage when the flame does not completely bridge the gap is established by the regression analysis.Results show that,the breakdown voltage is mainly affected by the characteristic differences of the flame continuous area itself when the flame bridges the gap completely.The lowest average breakdown voltage gradient can reach to 18.0%of that of the pure air gap.When the flame half bridges the gap,the smoke area withstands most of the voltage.The characteristics of the flame have little influence on the breakdown characteristics of the flame area.The differences of the breakdown characteristics under different vegetation wooden crib densities decrease with the increase of gap distances.The research results provides references for the air gap breakdown risk assessment and protection of the overhead transmission lines under forest fires.