基于N-k故障的地区电网脆弱性评估

电力系统N-k故障与电网中的脆弱环节有着紧密的联系,脆弱性评估已成为预防连锁故障的热门课题。为了辨识这些脆弱故障路径,在功能组分解的基础上,提出N-k故障路径搜索方法及其概率模型。引入效用理论来定义故障严重度函数,并基于熵值法和层次分析法对各项风险指标加权得到系统N-k故障综合风险指标。根据路径风险脆弱性和结构脆弱性函数,进一步提出适用于电网N-k故障的脆弱性指标,用以定量分析故障路径以及电网整体的脆弱程度。将该算法应用在河南某一地区电网,指出其中的脆弱线路和节点。仿真分析表明:与单一考虑风险的脆弱度评估方法相比,考虑了结构重要度的风险脆弱性评估的准确度更高,评估结果对电网监控亦更有意义。

Vulnerability Evaluation of District Power Grid Based on N-k Contingency

Critical segments in power system are closely related to N-k contingency.Vulnerability evaluation has become a hot topic of preventing cascading failures.In order to identify the critical contingency paths,the method of N-k contingency path search and its failure probability model was proposed based on functional group decomposition.Utility theory was introduced to define the severity of the contingency.And a composite risk indicator for N-k contingency was obtained by integrating the various risk indicators,which was based on the entropy and the analytic hierarchy process.According to vulnerability functions of path risk and system structure,vulnerability indicators for N-k contingency were further proposed for the quantitative analysis of vulnerability on contingency paths and the whole grid.Taking a district grid in Henan for example,the vulnerable buses and lines in it were identified.The example analysis demonstrates that,compared with the vulnerability evaluation method considering risk only,the method considering risk as well as structure vulnerability is more accurate and its result is more instructive for power grid monitoring.