Direct methods for stability assessment of two-time-scale electrical power system models

In this paper, we extend the application of direct methods, originally proposed for transient stability assessment, to the problem of mid-term stability analysis. By exploring the singular perturbation theory and direct methods, the stability analysis of an electrical power system is split into the stability analysis of two simplified subsystems: the fast and slow subsystems. As a result of this decomposition, more insight into electrical power system dynamics is gained and less conservative estimates of relevant parts of the stability region are obtained. Numerically, time scale algorithms are faster and more robust when compared with traditional ones.