A Short-term Reliability Model of Transmission Lines Based on Heat Balance Analysis

Short-term reliability of transmission lines is related to prediction time and operating conditions. The reliability model based on constant unavailability is no longer applicable. Hence， a temperature-dependent reliability model of transmission lines is established based on PHM （proportional hazard model）. The model consists of baseline hazard function and concomitant variable. The baseline hazard function takes account of tensile strength loss of transmission lines caused by temperature. Weibull distribution is used to describe the aging process and characterize the influence of temperature on failure rate. The ratio of real-time temperature to the rated temperature of lines is adopted as the concomitant variable to quantify the effect of real-time temperature on the short-term reliability of transmission lines. A Case study compares failure rate change of transmission lines with different service life in 24 hours. The result verifies the effectiveness of the model that can be applied to short-term reliability assessment for transmission lines to help operators make rational decisions in short-term operation and planning and online operation.