Analysis of the small signal dynamic performance of synchronous generators under unbalanced operating conditions

This work presents a thorough study about the effects of load unbalance in the dynamics of a power system that can be modeled as a single machine (synchronous generator) connected to an infinite bus. The main motivation for such a study is to better understand the behavior of power distribution systems when distributed synchronous generators with such typical topology are present, which is common in several countries around the world, including Brazil. The focus of this paper is the dynamic behavior of the system after small perturbations, as characterized by the system eigenvalues, focusing on the electromechanical oscillation frequencies and damping ratios, as affected by the load unbalance. In this work, other typical characteristics are also analyzed, such as the AVR and PSS gains, when well- or poorly-tuned. All the analysis is done through the estimation of these eigenvalues via a rotational invariant technique (ESPRIT method) from nonlinear simulations performed on ATP.