A Configuration of Storage System for DC Microgrids.

Battery energy storage systems are often adopted to buffer the difference between the intermittent solar power and the load demand in power grids. The costs of such photovoltaic (PV) battery systems increase as the required energy storage increases. In this paper, a new configuration comprising the PV panels, a series dc electric spring (series ES) and a noncritical load is proposed to reduce the battery storage capacity of dc microgrids that have substantial PV installations. This arrangement forms a PV-embedded series dc ES (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 that are connected to the series ES. 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. [ABSTRACT FROM AUTHOR]