Abstract:

The distribution line is exposed to the natural environment for a long time, which is easy to be affected by strong convection weather. In the afternoon of April 19, 2022, under the influence of high impact weather such as lightning and thunderstorms and gales, 13 distribution lines in Longnan City broke down successively, causing adverse effects such as power outage and power load loss for users. The extreme wind speed and lightning positioning data of from the automatic meteorological observation stations in Longnan City, Fengyun 4A (FY-4A) infrared cloud images, sounding data and Doppler weather radar data were used to analyze the severe convection weather process and the influence of power grid. The results are as follows: (1) The severe convective weather was dominated by lightning and thunderstorms and gales, and a large area of power outage and power load loss had occurred in Xihe, Lixian, Wudu, Kangxian and other counties. (2) The development of severe convection weather was mainly influenced by the plateau trough and shear line. Under the unstable atmospheric junction of "cold above and warm below", the surface convergence line triggered strong thunderstorm and gale; Satellite cloud images and radar echoes also showed that the development of convective clouds coincided with surface thunderstorms and gales. (3) The fault range distribution of distribution lines was basically consistent with the occurrence time and transit path of severe convective weather. Using 10-minute extreme wind speed and lightning location data, it was discussed that when the extreme wind speed exceeded 15.0 m·s^-1 or the positive lightning current exceeded 43 kA or the negative lightning current exceeded 26 kA, the possibility of distribution line faults was higher.

Key words: severe convection weather, thunderstorms and gales, electric power circuit, impact threshold

摘要：

配电线路长期暴露于自然环境下，易受强对流天气影响而发生故障。2022年4月19日午后，受大风、雷电等高影响天气影响，陇南市13条配电线路先后出现故障。利用陇南市自动气象观测站的极大风速和闪电定位数据以及风云4A（FY-4A）红外云图、探空资料、多普勒天气雷达等资料，对此次强对流天气过程及其对电网影响进行分析。结果表明：（1）此次强对流天气以雷电、雷暴大风天气为主，西和、礼县、武都、康县等县（区）出现大面积用户停电和电力负荷损失等不利影响。（2）强对流发展主要受高原槽和切变线共同影响，在“上冷下暖”的大气层结不稳定条件下，由地面辐合线触发较强的雷暴大风天气；卫星云图和雷达回波也显示对流云团的发生发展与地面雷暴大风相吻合。（3）陇南市配电线路故障范围分布与强对流天气发生时间和过境路径基本一致，利用逐10 min极大风速和闪电定位数据，探讨得出当极大风速值超过15.0 m·s^-1、或正地闪电流强度超过43 kA、或负地闪电流强度超过26 kA时，配电线路发生故障的可能性较大。

关键词: 强对流天气, 雷暴大风, 电力线路, 影响阈值