Failure analysis of a transmission line considering the joint probability distribution of wind speed and rain intensity

Abstract

Traditionally, only the intensity measure of wind speed is used to perform the failure analysis of transmission lines (TLs). However, during typhoon landing, both the wind and rainfall effects on the failure probability of TLs should be considered. To fill the gap of rainfall amount data measured with long sampling periods, this study presents a conversion approach of rain intensities with various time resolutions based on the meteorological data of 1336 stations. Then, the 12-hour rain intensity samples recorded over 60 years are converted into 10-min rain intensity samples, followed by the establishment of the marginal probability distributions of yearly extreme wind speed and rain intensity. Furthermore, according to the theory of Copula function, the joint probability distribution of wind speed and rain intensity is proposed using the Clayton copula which has the best goodness of fit. Finally, a case study is performed and the failure probabilities of a TL under combined wind and rain loads are calculated. The failure probability of the employed TL under combined wind and rain loads has reached 6.19%, and the value is only 2.88% if ignoring the rainfall effect, demonstrating that rainfall has significant influence on the structural safety of a TL.