Simulation-free Estimation of Critical Clearing Time

Contingency screening for transient stability of large scale, strongly nonlinear, interconnected power systems is one of the most computationally challenging parts of Dynamic Security Assessment and requires huge resources to perform time-domain simulations-based assessment. To reduce computational cost of time-domain simulations, direct energy methods have been extensively developed. However, these methods, as well as other existing methods, still rely on time-consuming numerical integration of the fault-on dynamics. This task is computationally hard, since possibly thousands of contingencies need to be scanned and thousands of accompanied fault-on dynamics simulations need to be performed and stored on a regular basis. In this paper, we introduce a way to eliminate the need for fault-on dynamics simulations in contingency screening. This technique is based on bounding the fault-on dynamics and applying the recently introduced Lyapunov Function Family approach for transient stability. In turn, a lower bound of the critical clearing time is obtained without restoring to simulations. A comprehensive analysis is carried out to validate this novel technique on a number of IEEE test cases.