Identification of coherent machines using modal analysis for the reduction of multimachine systems

Coherent generator groups are determined by modal analysis applied to Electric Power Systems (EPS). The oscillation modes are represented by the eigenvalues obtained from the linearization of the nonlinear equations that describe the behavior of the system. These modes are classified according to their damping frequency into two groups: the local modes and the inter-area modes. The latter are the ones of interest to the study, because their frequency is similar to that of a large perturbation and it can therefore allow the identification of coherent groups.