Microgrid impact on low frequency oscillation and resonance in power system

Renewable technology based Micro Grid (MG) are mostly implemented with power electronic devices. Those MGs have no or very small aggregated physical inertia, depending on the generation technology used. Reduction in system inertia may have negative influence on stability of the system where the MG is integrated. Conversely power injection from MG might reduce line congestion, stress on synchronous generators and improve damping performance. In this paper, impact of MG penetration in a two-area power system is thoroughly investigated for small signal stability. Eigenvalues analysis shows that damping of inter-area and local modes enhanced as MG penetration increased. For variation in system operating conditions two neighboring eigenvalues coincided and interacted. Furthermore, a weak resonance phenomenon is detected. With increasing MG penetration, the detected resonance becomes weaker as the distance between two interacting modes was kept far enough. Eventually, the resonance can be prevented and system stability can be maintained with the help of MG.