Decentralized Control of Multi-Parallel Grid-Forming DGs in Islanded Microgrids for Enhanced Transient Performance

Abstract

This paper proposes a novel decentralized control strategy for multiparallel grid-forming distributed generations (DGs) in an islanded microgrid. Different from most existing droop-based hierarchical control methods, the proposed scheme imposes a fixed system frequency that is independent of the load conditions. Additionally, a proper point of common coupling (PCC) voltage amplitude maintaining and proportional power sharing can be simultaneously achieved when dealing with variations in the load and DGs plug in/off. The transient performance of the system, as well as the power supply reliability, can be improved, as no extra restoration control layer or communications between the inverters are needed. Furthermore, the power sharing ratio among DG units can be changed online without affecting the voltage regulation performance, which enhances the power management flexibility. The PCC voltage regulation and the power sharing performance of the proposed control strategy are ensured via the Lyapunov method. Finally, the effectiveness and practicability of the proposed approach are verified through real-time simulations and hardware experimental tests.