Fast Search of Cascading Failures Chains in AC-DC Hybrid Power System

A fast search method of cascading failure in AC-DC system is proposed to acquire high-risk AC-DC system cascading failure chains. At first, the impact of AC system cascading failures chains (CFSs) on DC system is fast estimated according to the multi-infeed short-circuit ratio (MISCR) and the short-circuit voltage of converter bus, which are two key characteristics of AC system faults. Then, a fixed number pruning technique is adopted in the proceeding of CFSs searching to reduce search space. In order to rank the risk of lines in offspring, a line failure risk index R based on lines failure probability and influence on other lines is proposed. Finally, time-domain simulation is adopted to analyze whether the most severe AC system CFSs can trigger DC block. The effectiveness of the method proposed to search high-risk CFSs in AC-DC Hybrid Power System is verified by the simulations concerning the Shandong power grid of China.