Time‐varying failure rate simulation model of transmission lines and its application in power system risk assessment considering seasonal alternating meteorological disasters

Abstract

Years of operation experience on power systems reveal that most transmission line fault events are related to seasonal alternating meteorological disasters, which have typical temporal and spatial distribution characteristics. However, power system risk assessment lacks basically accurate descriptions of failure rate time distribution for transmission lines. In this study, a method to calculate the time-varying failure rate of transmission lines in a monthly time scale is proposed to reflect the time-dependent fault regulation. However, the failure rate during any time interval cannot be derived directly from limited historical fault samples. Therefore, a simulation method of continuous time distribution function for failure rate is proposed, which adopts Fourier, Gaussian, and Weibull function assumptions. Furthermore, the parameters of these function hypotheses are fitted and compared using the fault samples of a province power grid and an urban power grid in China, respectively. Results show that the proposed simulation model is reasonable. Finally, the time-varying failure rate simulation model is adopted to quantify the risk of the verified IEEE-RBTS system. The risk indices also indicate that considering the time distribution characteristics of failure rate has a more significant influence on the system risk than the conventional methods.