System-response-based eigenvalue estimation for on-line assessment of power system stability

This paper proposes a new method for modal analysis of large power systems that is based on synchronously measured system responses. The method can identify the eigenvalues corresponding to weakly damped electromechanical modes by analyzing the covariance matrix among rotor angles and speeds of generators. By the method, a power system is identified as a multi-input multi-output linear system, so that the characteristics of several modes can be analyzed simultaneously. In addition, the method to select a small number of generators for estimating slow oscillatory modes is discussed, and which is based on the application of coherencies of generators. The effectiveness of the new modal analysis is confirmed through the simulation studies of the IEEJ East10 machine model.