Eigenvalue Estimation of Dominant Electromechanical Modes Based on Synchronous Measurement and Generator Grouping Technique

The authors have been studying a new approach for modal analysis of large power systems that utilizes GPS-based synchronous measurement technology. The approach is based on the identification of a linearized Multi-Input Multi-Output model of power system. Since the identified model expresses approximately the electromechanical dynamics of actual power system, modal frequencies, dampings and mode shapes corresponding to electromechanical modes can be estimated as eigenvalues and eigenvectors of the identified model. In the paper, in order to advance our approach to a practical technique, it is mainly discussed how to select a small number of machines suitable for measurement locations to estimate eigenvalues associated with dominant slow modes. Such machines can be detected by identifying coherent groups related to the slow modes. The reference generators that behave representatively in each coherent group are the optimal ones to be measured. Therefore, the slow modes can be obtained by observing one generator from each group. The verification of the new modal analysis and coherency-based machine selection is done through simulation studies using IEEJ EAST 10-machine system model.