Direct computation of critical clearing time for transient stability analysis

This paper presents a new technique for what we call the 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 method lies in its ability to provide exact CCT by solving a minimization problem. 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. This paper proposes new alternative end point condition, making it possible to take into account AVR and Governor for the Xd' generator model. It is demonstrated using 30-machine system that the proposed methods successfully provide the exact CCT that agrees with the conventional numerical simulation method.