Two Novel Methods for Real Time Determining Critical Clearing Time: SIME-B and CCS-B Based on Clustering Identification

Two new methods for real time computing critical clearing time based on clustering identification are proposed. This article is covering three main sections: (i) clustering generators and recognizing critical group; (ii) replacing the multi-machine system by a two-machine dynamic equivalent and eventually, to a one-machine-infinite-bus system; (iii) presenting a new method to predict post-fault trajectory and two simple algorithms for calculating critical clearing time, respectively established upon two different transient stability criterions, which are fast enough for real time purposes. The prediction method is developed to tackle with the problem of predicting post-fault trajectory on the basis of merely measured data in the first few centiseconds immediately after the system is perturbed. The performance is expected to figure out critical clearing time within 100ms-150ms and with an acceptable accuracy.