A Hybrid Method for Fast Rotor-Angle Stability Assessment

This article proposes a novel hybrid time-domain and direct stability method for rotor-angle stability assessment, aiming to improve the efficiency of existing approaches. The proposed method enables faster detection of both small-signal and transient stability scenarios while extending the applications of the classical stability direct methods to multiswing stability analysis. Unlike the conventional direct methods that rely on the overall system energy, the proposed approach calculates the system's critical energy using the critical apparatus energies, facilitating multiswing stability analysis. Key contributions of this work include the introduction of a new metric, termed “the time to instability,” which allows for the prediction of separation or islanding areas during disturbances. Additionally, the proposed method can rank all apparatus in a power system based on their criticality during small or large disturbances. Also, a stopping condition for the time-domain simulation is provided, reducing algorithm execution time and rendering it suitable for real-time or near-real-time application of dynamic security assessment. The proposed method is tested with multiple stability scenarios and the four possible stability scenarios are presented in this article using the IEEE 16-machine 68-bus power system. The results demonstrate the high accuracy of the proposed approach in identifying the critical apparatus and assessing first- and multirotor-anglestability in power systems.