Suppressing Circulating Currents of Battery Management Systems in Droop based Microgrids

Droop control method is frequently utilized in DC microgrids. However, it shows high sensitivity to unknown line resistances. As a consequence, the converters' currents do not follow expected amounts and load sharing which is the primary objective in a DC microgrid has lack of accuracy. Hence, parallel-connected Battery Energy Storage Systems (BESS) have mismatched output voltages and circulating currents arise. This paper proposes an adaptive droop control method for a DC microgrid. The proposed method estimates line resistances through mathematical calculations and adjusts droop parameters to eliminate the effect of unknown line resistances. Each participating BESS follows its predefined current and circulating current is suppressed. The proposed method results in an accurate load current sharing. The success of the adaptive proposed method is verified through simulation and Hardware-In-the-Loop (HIL) setup.