低压架空裸导线影响森林火灾特性机理研究

近年来国内输配电线路引发森林草原火灾风险越来越高。为探究低压架空裸导线引发火灾的特性和机理，本文搭建了380/220 V低压架空裸导线模拟实验平台，开展了树枝短接线路实验、两相线路相间接触短路实验，并对线路穿越林区与树木接近处经常出现短路熔痕的现象进行了实验和仿真分析。结果表明：正常树枝和雨水浸湿后的树枝短接线路，不会发生放电打火现象，也无温升和泄漏电流产生。两相线路相间接触短路，放电产生的喷溅熔珠掉落至地面温度较低，不足以引燃地面的可燃物。结合近年低压线路火灾原因调查结果分析，线路过流保护开关对低压线路引发的火灾有显著预防作用。线路穿越林区与树木接近处的短路熔痕，可能为大风大雨天气下树枝短接线路放电产生。所做研究可为低压线路火灾原因调查和防范提供技术参考。

Study on the effect mechanism of low voltage bare wire on forest fire

In recent years, the risk of fire in forest grassland caused by power transmission and distribution lines in China is increasing. In order to explore the characteristics and mechanism of low-voltage overhead bare wire fire, a 380/220 V low-voltage line simulation experiment platform was built. Branches short-circuiting lines and two phase contact short circuit tests were carried out. The phenomenon of short-circuited melted marks often occurred in the close place between low voltage bare wire crossing forest area and trees was analyzed by the experiments and simulation. The results indicate that there were no spark discharges when normal twig and rain-soaked twig overlapped line. The temperature of the splash beads generated by the contact short-circuit discharge between two phase lines falling to the ground is low, which can not ignite the combustible material on the ground. Combined with the investigation results of low-voltage line fire causes in recent years, the line overcurrent protection plays a significant role in preventing low-voltage line fire. In strong wind and heavy rain, the twigs and leaves short-circuit two phase line, which may lead to short-circuit discharge and obvious melted marks on the wire. The research can provide technical reference for low-voltage line fire cause investigation and prevention.