考虑竞争失效的交流接触器可靠性评估方法

交流接触器广泛用于电力系统，精准评估其可靠性是保障系统安全平稳运行的关键。现有交流接触器可靠性研究没有考虑三相触头的竞争失效、退化相关性，及各相触头失效阈值均有随机性等问题，可能造成可靠性评估不精准。针对这些问题，本文用累积电弧侵蚀量表征性能状态，建立了考虑竞争失效、退化相关性和失效阈值随机性的退化模型；对模型参数较多且难以同时估计所有参数的问题，提出了基于极大似然估计的多阶段参数估计方法；基于蒙特卡洛技术提出了可靠度近似计算方法，并基于黎曼和技术推导出平均故障时间的近似式；最后，通过仿真与实例分析验证了所提方法的有效性。实例分析表明所提可靠性评估方法精度较高，其拟合优度比现有方法提升了约45%。

Reliability assessment method for AC contactors considering competing failure

AC contactors are widely used in power systems. The accurate reliability assessment of AC contactors is essential for ensuringthe safe and stable operation of the system. The existing reliability studies on AC contactors did not consider the competing failure anddegradation correlation among the three-phase contacts as well as the randomness of the failure threshold of each contact, which may leadto inaccurate reliability evaluation result. To solve these problems, a performance degradation model incorporating the competing failure,the degradation correlation, and the randomness of the failure thresholds is formulated by using the cumulative arc erosion amount tocharacterize the performance state. A multistage parameter estimation method based on the maximum likelihood estimation is presentedfor the problem that there are many model parameters and it is difficult to estimate all the parameters simultaneously. A reliabilityapproximation method is provided based on the Monte Carlo technique, and an approximate expression of the mean time to failure isderived based on the technique of Riemann sum. Finally, the effectiveness of the proposed method is evaluated by simulation and realcase studies. The real case study shows that the proposed reliability evaluation method has high accuracy, and the goodness of fit is about45% better than the existing methods.