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Design of a Non-PLL Grid-Forming Inverter for Smooth Microgrid Transition Operation: Preprint

Conference ·
OSTI ID:1669564

This paper develops a non-phase-locked loop (PLL) grid-connected inverter that can improve the microgrid’s transients during transition operation. By emulating the operation of a synchronous machine, the inverter generates its own voltage and frequency during startup, synchronizes and connects to the grid, then operates in reactive power mode (grid-feeding) with self-generated voltage and frequency, and switches to voltage-frequency mode to establish system voltage and frequency (grid-forming) when the microgrid disconnects from the main grid, and vice versa. To enable fast synchronization, active synchronization control is adopted both during inverter startup and microgrid reconnection operation. The simulation results show that the developed non-PLL grid-connected inverter works effectively to synchronize the inverter and microgrid to the grid and avoids a phase jump during microgrid transition operation. Thus, the microgrid’s transients are significantly improved with the proposed control technique.

Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Advanced Research Projects Agency - Energy (ARPA-E)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1669564
Report Number(s):
NREL/CP-5D00-75332; MainId:6338; UUID:64de7a92-defc-e911-9c29-ac162d87dfe5; MainAdminID:17333
Country of Publication:
United States
Language:
English