A configuration of storage system for DC microgrids

Abstract

IEEE Battery energy storage systems (BESS) are often adopted to buffer the difference between the intermittent solar power and load demand in power grids. The costs of such systems increase as the required energy storage increases. In this paper, a new configuration comprising the photovoltaic (PV) panel, a series DC electric spring (series ES) and non-critical load is proposed to reduce the battery storage capacity in DC microgrids that have substantial PV installations. This arrangement forms a PV-embedded series DC electric spring (PVES). An optimization method considering the minimization of electricity bills of the DC microgrids is included to size the storage capacity and to determine the rating of the PV connected to the series ES. Both experiments on a 48 V isolated DC grid and simulations on a 400 kVA grid-connected DC microgrid have been conducted to verify the storage reduction feature of the PVES. Both sets of results show that the PVES can tackle the intermittency of the solar power with a smaller storage capacity than that typically required in DC grids with PV installations.