Grid-Connected PV + Battery AC Nanogrid with EV Integration for Increased Resilience

Abstract

This work concerns a three-phase grid-connected AC nanogrid with PV generation and battery storage. The system is based on SMA Sunny Boy (SB) and Sunny Island (SI) inverters with a Data Manager for monitoring and control. It also includes an EV that can be charged through a standard 208V unidirectional charger when the grid is available. A low-cost single-phase unidirectional Vehicle-to-Home (V2H) inverter, that communicates with the BEMS of the EV, is available at the site. It can supply isolated loads but not to operate in parallel with the PV + battery three-phase system. To allow the EV to support the nano-grid, the V2H is connected through a fourth SI (SI4) to charge the stationary battery. An energy management scheme is proposed for extending load supply following a transition from grid connected mode to islanded mode. It includes not only EV battery support but also load shedding scheme to manage the SOC of the battery. Experimental results are presented.