Input-Series-Output-Parallel DAB Converter on Energy Storage System for Voltage Balancing Strategy in Bipolar DC Microgrid

Abstract

Bipolar DC microgrids have the advantage of reliability and safety of power supplies. However, there are disadvantages in the need for galvanic isolation due to neutral line grounding structure and the need for voltage balancing between two voltage buses because of imbalanced power by sources and load demands. This paper presents a voltage balancing strategy through an input-series-output-parallel (ISOP) dual-active-bridge (DAB) isolated DC-DC converter for ESS in Bipolar DC Microgrid. In the proposed method, the power of each DAB module is coupled and controls ESS power and balancing power individually. Therefore, for achieving the bipolar voltage regulation, an additional voltage balancer is not required for the grid-connected or isolated mode of a microgrid and even if ESS power limitation. Moreover, it is easily possible to limit the output according to the SOC of the ESS without an additional compensation controller. Finally, theoretical analysis and simulation results of the proposed method are presented. © 2021 KIEE & EMECS.