山火条件下高压输电线路放电特性

Experimental study of discharge properties of high voltage transmission lines and their relationship with fire parameters under wildfire conditions

利用单、双和三木垛火源和单股、双分裂和四分裂模拟高压导线研究了中尺度高压输电线路在火灾条件下的放电特性及其与火源火场参数的关系,提出了为防控火灾实际输电线路走廊内森林可燃物管理方法。结果发现,模拟导线在火焰中较纯空气中容易发生放电(火焰中空气平均击穿场强较纯空气中约下降64.9%);火持续时间、火焰高度和火灾荷载密度对平均击穿场强的影响程度依次减弱,火强度则是决定性影响参数(木垛火源双木垛火变为三木垛火时,空气平均击穿场强与火强度、火灾荷载密度、火持续时间及火焰高度增幅比分别为2.11、0.482、1.70和0.582);中高速中高强度的上山地表火、树冠火、冲冠火和地表火转化的树冠火易形成高火焰、高热量、高温度、高浓度(烟尘粒子和带电质点)的容易使线路跳闸的环境条件。

The discharge properties of high voltage transmission lines and their relationship with fire filed parameters under fire conditions on medium scale were experimentally explored by u sing single, double and three wood cribs and simulative single core, double bundle and four bundle conductors. Management methods of forest combustibles in the corridor of real transmis sion lines for preventing from fires were presented. Results show that conductors are easier to discharge in flames than in pure air （the average breakdown intensity in flames decreases by 64.9% of that in air） ; fire intensity shows determinative effect on average breakdown intensity, while fire duration, flame height and fire load density shows decreasing effect （when wood fire source changes from two cribs to three cribs the amplification of average breakdown intensity to fire intensity, fire load density, fire duration and flame height takes 2.11, 0. 482, 1.70 and 0. 582 respectively） ; ground fires and crown ing fires converted from ground fires with medium and high intensities and upswept propagation direction at a medium andhigh spread rate are easier to establish hazardous ambient conditions with high flame height, high thermal output, high temperature and high concentration （smoke particles and electric mass points） that are prone to induce flashover.