Comparison of critical trajectory methods for direct CCT computation for transient stability

This paper studies new techniques for critical trajectory method, a recent new method proposed by the authors for obtaining critical clearing time (CCT) for transient stability analysis. A specific feature of the proposed method lies in its ability to provide exact CCT without approximations since no such methods have existed so far. The method is based on the computation of the critical trajectory, which is defined as the trajectory that starts from a point on a fault-on trajectory at CCT and reaches an end point. There are a few possible methods for the treatment of the end point conditions, computational performances of the methods are investigated in terms of accuracy of CCT and computational efficiency. It is shown that the proposed methods successfully provide the exact CCT that agrees with the conventional numerical simulation method.