Risk Assessment of Trip Caused by Air Gap Discharge between Transmission Line and Tower under Typhoon

Typhoon, as one of the most destructive disasters, threatens many coastal cities, and does great harm to overhead transmission lines in electric power system. According to statistics, the air gap discharge between transmission line and tower is one of the most important reasons for tripping under typhoon. Therefore, this paper proposes a novel risk assessment method to evaluate the risk level of this type of trip. The first step is data collection and processing. Relevant parameters and information are collected and processed, such as the maximum three seconds gust wind speed, type of tower and ground roughness. The second step is to simulate the typhoon wind field using Monte Carlo method. In the third step, a calculation model of trip probability is established based on physical mechanics and fuzzy mathematics method, and we also give a table to classify trip risk levels. Under the last part of this paper, the risk assessment of transmission lines in a coastal area of China is carried out during the thirteenth typhoon ‘Hato’ in 2017. By comparing the obtained risk level with the actual line trip situation, the validity and rationality of the proposed method is verified.