Power Coupling Influence on Virtual Synchronous Generator Control in Grid-Forming DG Systems

The virtual synchronous generator (VSG) strategy has become very promising in applications of grid-forming distributed generation (DG) systems based on renewable energy sources (RES). Thus, this paper presents an impact analysis of the coupling effect between the active and reactive power flow of the DG system in the VSG controller's dynamic performance. This analysis is based on a small-signal model describing the DG power flow transient characteristics. Based on this model, the grid impedance variation effects on the system's critical operation point are discussed. The VSG strategy performance in different operating scenarios is assessed by means of simulation results. The obtained results reveal the effectiveness of the proposed theoretical analysis.