交直流混联系统连锁故障搜索模型及故障关联分析

随着大规模直流输电系统的相继投运，交直流耦合问题突出，连锁故障的风险加剧。首先，针对交直流混联系统建立了一种用于故障快速筛选的事故链搜索模型。该模型包括交流侧故障搜索模型和直流故障判断环节两部分:前者计及了支路对直流运行的影响度和结构重要度，并形成停运概率初筛后风险优先的搜索策略；后者将交流系统中短路故障开断和无故障跳闸开断区分开，分别考虑与直流系统的关联情况。其次，提出了一种考虑项序和事务权重的Apriori算法进行故障关联分析，筛选出威胁系统安全的强关联规则。仿真结果表明，所提方法能高效搜索出直流退出运行的故障演化路径，并有效识别危及系统安全的强关联规则。

Search Model and Correlation Analysis for Cascading Failures in AC/DC Hybrid Power System

With the ever-increasing large-scale HVDC transmission systems, the coupling problem between AC and DC systems is outstanding, which increases the risk of cascading failures. An event chain search model for fast contingency screening in the AC/DC hybrid power system is proposed, which includes the AC outage search model and the judgment module of the occurrence of DC faults. In the AC outage search model, the influence on the operation of DC systems and structural importance of lines is considered and a novel search strategy in the AC grid which is based on outage risk index after preliminary screening by outage probability value is put forward. In the judgment module of the occurrence of DC faults, the short-circuit faults and the overload trips in the AC grid are set apart considering the interactions with DC systems. In addition, a method of correlation analysis for cascading failures based on the modified Apriori algorithm considering the order of items and the weight of transaction is proposed to select the strong association rules endangering system security. Finally, simulation results demonstrate that the event chain search model can search the fault paths effectively in which DC systems are out of operation and reduce the omission of high-risk chains, and the method of correlation analysis can identify the strong association rules that endanger system security.