Centralized Control for Paralleled VSCs With Grid-Forming and Oscillation Suppression Capability

Paralleled multiple voltage source converters (VSCs) are adopted in photovoltaic (PV) or energy storage systems, and may suffer from oscillation and fault disturbance issues under various grid conditions. In this paper, a centralized control frame is proposed to suppress the active power oscillation and support the grid voltage/frequency via grid-forming (GFM) control. A virtual synchronous generator (VSG) control is applied as the centralized controller, which communicates with local controllers. The mutual damping and power angle feedback are adopted in the local controller to achieve an accurate active power sharing. The influence of key parameters such as the communication delay and mutual damping are analyzed. Finally, the proposed control is verified though the simulation and hierarchical controller-hardware-in-loop (CHIL) experiments.