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电气设备短期可靠性为电力系统风险评估提供数据支持,状态空间法中传统转移频率守恒等值算法基于稳态指标定义,不适用于短期可靠性评估,故需进行改进.本文研究等值条件,首次证明满足等值条件的系统等值后仍为马尔可夫过程,暂态状态概率可由矩阵相乘得到.不满足等值条件的系统,提出用半马尔可夫过程描述.确立等值前后转移率及分布函数的关系,推导半马尔可夫核矩阵与等值后转移率、分布函数的关系,以矩阵描述形式求得暂态状态概率和灵敏度指标.运用所提算法对一智能变电站保护系统进行短期可靠性评估,结果表明传统算法低估系统可用率,暂态灵敏度的峰值和出现时间也存在误差.初始状态影响系统暂态可用率以及暂态灵敏度的收敛速度.
The short-term reliability of electrical equipment provides the data support for power system risk assessment. The traditional equivalent transfer frequency conservation algorithm in state space method is not suitable for short-term reliability assessment because of the definition of steady state index, so it needs to be improved.In this paper, It is proved for the first time that the system satisfying equivalent conditions is still Markov process, and the transient state probabilities can be obtained by matrix multiplication. For systems that do not satisfy the equivalent conditions, semi-Markov process description is proposed. The relationship between the semi-Markov nuclear matrix and the post-equivalence transfer rate and distribution function is deduced, and the transient state probability and sensitivity index are obtained by using the matrix description form. The proposed algorithm is applied to an intelligent substation protection system The short-term reliability assessment shows that the traditional algorithm underestimates the system availability, and the peak and the emergence time of the transient sensitivity also have errors.The initial state affects the system transient availability and the transient sensitivity convergence rate.