基于点估计法的电力系统可靠性评估方法研究

Research on Power System Reliability Evaluation Based on Point Estimation Method

提出一种基于点估计法的电力系统概率可靠性评估方法,可为可靠性评估方法的改进与应用提供新的思路和方法。通过用元件运行容量与额定容量的比值来定义元件状态,并定义了随机变量的概率密度函数,将表示系统元件状态的离散型随机变量扩展为连续型随机变量,使之在整个实数区间内有定义,并且在正常状态和故障状态与原来的定义一致。给出了系统元件降容状态的可靠性指标计算方法,可满足点估计法的计算要求。通过对点估计法的误差分析,提出m阶点估计偏移方法,可降低点估计法应用于电力系统可靠性评估的计算误差。通过算例与解析法和模拟法进行了比较,验证了方法的实用性和有效性。

A method for power system probabilistic reliability assessment based on PEM is proposed in this paper, which provides new ideas and methods for the improvement and application of reliability assessment. The state of a element is defined by using the ratio of its operation capacity to rated capacity, and the proba- bility density function of the random variable is defined, such that a discrete random variable which expresses the state of the element is expanded to a continuous random variable, which enables the definition in whole real region and conformity with original definition in the points of its normal and outage states. The calculation method of reliability index at capacity reduction state of system elements is given to meet the requirement of calculation by point estimation. Through analysis on the error of PEM, a method called m-order migration for estimation points is put forward, which can reduce the calculation error of point estimation method applied in power system reliability assessment. Through comparison between examples, the analytic method and the simulation method, the practicability and validity of the approach are verified.