It is mainly determined by topological ability prior to faults to form the grouping for large disturbances.Secondly, a new method of PMU placement for transient stability analysis is proposed.

• 结果表明,慢同调方法能够揭示网络固有的分层分区特点,故障虽然具有不确定性,不同故障位置下分群结果也略有不同,但最大故障集对应的网络临界割集组是确定的,大扰动下的分群仍然取决于网络拓扑特征。