MANAGEMENT OF A SOLAR PV-BES MICROGRID POWERED BY THREE-PHASE PARALLEL INVERTERS

Abstract

This study introduces a three-phase microgrid design that operates in both grid-interfaced (GI) and
freestanding (SA) modes, utilizing solar photovoltaic (PV) and battery energy storage (BES). Parallel
connections are made between a BES, two solar PV arrays, and the point of common coupling (PCC).
Current/power sharing is the form of control for the parallel voltage source converters (VSCs). When in SA
mode, the VSC linked to BES functions as a grid forming inverter, maintaining the PCC voltage, while in GI
mode it is programmed to send continuous power to the grid. Current-controlled mode is the default operation
for VSCs linked to PVs. The active fundamental weight of load currents is estimated using a complex
coefficient complex variable filter-based frequency locked loop (CCCVF-FLL). The phase of the load/grid
voltages is estimated using the same FLL in order to synchronize the microgrid with the utility grid.