山火诱发高压输电线路跳闸典型事故分析

Analyses of a typical flashover incident of high voltage transmission lines induced by wildfires

通过调研湖南省某处山火诱发500kV高压输电线路跳闸的事故,以桂山乙线454#杆塔为代表,分析此次山火成因、等级、类型和强度,分析空气温度和相对湿度、风速和风向对山火形成和发展影响以及山火作用下线路跳闸行为、类型、成因和机理。结果发现:诱发桂山甲乙同塔双回线路跳闸的山火为火线强度高于10 MW/m的高强度地表火,后在风速和风向作用下转为高强度冲冠火和被动型树冠火;紧凑型交流线路易发生相间放电,桉树和茅草等植被型扩散性火焰产生的大量导电性离子和电子及针状烟尘颗粒促发和加剧了这一过程,直至形成电子崩和流注通道,诱发线路跳闸。

The typical flashover incident of 500 kV high voltage transmission lines induced by a wildfire in Hunan Province was investigated. The #454 tower of Guishanyi Line was taken as an example, the origin, rating, type and intensity of the wild- fire were analyzed, and influence of the temperature and humid- ity of air, the speed and direction of wind on the formation and development of wildfire were researched. The behaviors, type,origin and potential mechanism of flashover under wildfire were also explored. Results showed that the wildfire which induced the flashover can be deduced as a surface fire with higher inten- sity than 10 MW/m and turns into prone-crown fire and passive crown fire under the effects of variable wind speed and wind di- rection; compact transmission line is easier to have phase-phase discharge. Large quantities of conductive ions, electrons and needle-like smoke particles produced by diffusive flames of veg- etation fuels like eucalyptuses and thatches can exacerbate the formation of electron avalanche and streamer tunnel, then in- duces the flashover.