Secondary control for DC microgrids: A review

This paper presents a review of secondary control strategies for DC microgrids (DC MGs) and compares centralized, decentralized and distributed control approaches. The conventional droop control provides proper power sharing among converters with the increment in droop gain. However, this droop gain is inversely proportional to the output current consequently leading to current sharing inaccuracy and affects the system stability in case of line impedance mismatch. The energy storage system that plays a vital role in formation of DC microgrid, has issues of SOC equalization and charge/discharge control. This paper discusses distributed secondary control and the current state-of-art to mitigate aforementioned issues. On the other hand, the possibility of mode change of control approaches have been discussed.