Abstract
A large-scale transmission line icing and galloping event occurred in Jilin province during November 2020. First of all, the circulation background and the evolution characteristics of key meteorological factors of the icing and galloping event are analysed, which provide basis for the prediction and early warning of the galloping event in the future. It is found that, the warm and wet air transported northward to the central part of Northeast China due to the abnormal northward position of the western pacific subtropical high, combined with the strong cold air activity in the north, the cold and warm air converged in the middle of Northeast China, resulting in the co-occurrence of temperature decline, precipitation, gale and high humidity, which is the direct cause of this large-scale galloping event. Then, the prediction and actual situation of the disaster event are analysed. The results show that the power gird icing and galloping numerical prediction system accurately predicted the influence area and disaster intensity three days in advance, which can provide effective support for future disaster response. Finally, some relevant suggestions are put forward according to the characteristics of this disaster.
Highlights
Transmission line galloping is the low frequency and large amplitude self-excited vibration of transmission line under the action of strong wind and light ice
2.1 Background conditions of large scale circulation The strong WPSH is abnormally northward, which results in the warm and humid air from the south transported to the central of Northeast China, The high-altitude trough changed from horizontal trough to vertical trough, leading the strong cold air in the north to affect China from northwest area to northeast area
The confluence of cold and warm air in the central of Northeast China is the circulation back-ground condition for the formation of this icing and galloping disaster event. It can be seen from figure 1(middle), before the occurrence of the icing and galloping disaster, the ridge line of the WPSH, which represents the north-south position of the WPSH, pushed northward to 26°N, which was abnormally northward than the climatological mean (19°N)
Summary
Transmission line galloping is the low frequency and large amplitude self-excited vibration of transmission line under the action of strong wind and light ice. Due to galloping, the structure of line tower is damaged, which takes a long time to restore power supply, threatens the stability of power supply, and leads to major power grid security accidents [2,3]. There are 312 220kV and above voltage grade transmission lines tripped due to galloping in State Grid Company of China during 2010-2020, among which Bohai rim, Henan and Hubei Province are the three most prone areas to dance disasters in China [4,5,6]. A serious ice disaster occurred in Jilin Province during November 18-22, 2020, which caused large-scale transmission line icing and galloping. The background of meteorological circulation system and the evolution characteristics of key meteorological elements during this large-scale icing event are analysed, the comparative analysis of the disaster prediction and the actual situation of is carried out, and some suggestions are put forward for the prevention and control of power grid icing disaster in northern area
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