基于热平衡分析的输电线路短期可靠性模型

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

输电线路的短期可靠性与预测时间和运行条件相关,基于恒定不可用率的可靠性模型不再适用。对此,基于PHM(比例故障率模型)建立温度相依的输电线路可靠性模型。模型分为基准故障率函数和协变量两部分。基准故障率函数考虑温度对输电线路抗拉强度的损失,采用Weibull分布描述老化过程,表征历史温度状况对故障率的影响。采用输电线路实时温度与线路额定温度的比值作为协变量,量化实时温度对输电线路短期可靠性的影响。算例对比了不同服役时间的输电线路在24 h内的故障率变化情况,结果验证了模型的有效性。该模型可应用于输电线路的短期可靠性评估,帮助调度人员在短期运行规划和在线运行中做出合理决策。

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 The reliability model based on constant unavailability is no longer applicable.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.