A Virtual Synchronous Machine Control applied to Photovoltaic Generation in Decentralized Microgrid

The increasing integration of renewable energy sources in microgrids has introduced new challenges in their control strategy management. The lack of inertia, due to the large presence of power-electronic interfaced generators, worsens network dynamic performances in the case of sudden variations in its working conditions and, as a result, the stability of microgrid may no longer be guaranteed. In order to ensure the stable operation of microgrid, the use of suitable controllers, applied to static generators for providing a power contribution during network perturbations, is a concrete way. In this work, a virtual synchronous machine control is developed for a photovoltaic plant, without deload requirements. Unlike the swing equation based inertial response, this control strategy appears more suitable since it ensures grid stability even when no reference frequency is locally available. Different simulations, carried out in DIgSILENT PowerFactory environment, validate the proposed control scheme for a test microgrid. Finally, the controller operation during low solar radiation periods is also illustrated.