Multi-mode operation of different PV/BESS architectures in a microgrid: Grid-tied and island mode

The performance of two different solar photovoltaic (PV)/battery energy storage system (BESS) architectures are compared on a simulated microgrid testbed. The PV system is interfaced with the BESS at the DC link to provide reserve power. These two different integrated solutions can be compared with regards to the number of power stages, efficiency, storage system flexibility, and control complexity. A single power conversion system named Reconfigurable Solar Converter (RSC) presents more flexibility, less complexity, and multi-mode capability depending on system requirement, and results in a more efficient and economical system compared with a current indirect PV/battery system with two stages of power conversion units. There are various approaches to share the load when microgrids are islanded or disconnected from the main grid. In the islanded mode, a distributed generator (DG) like a diesel generator can enhance the reliability of the power supply and regulate the frequency and voltage within the microgrid. Different operation modes for both topologies such as PV to grid, PV plus battery to the grid, battery to the grid (DC to AC) and PV to battery (DC to DC) are simulated on a microgrid testbed, verifying the applicability of the two architectures in microgrids.