Planning and protection of DC microgrid: A critical review on recent developments

Nowadays, direct current (DC) microgrid is gaining importance due to the wide utilization of DC loads, integration of solar photovoltaic (PV) and energy storage devices, and no frequency and reactive power control issues. However, planning and protection of such microgrid are complicated due to the connection of several distributed generators (DGs), loads, utility grids, and energy storage systems (ESSs) to the DC bus with power electronic converters. Hitherto, the protection of DC microgrid has not drawn sufficient attention due to the high cost and immature protective devices for DC faults. Furthermore, the reliability of DC microgrid highly depends on proper planning, protection, and power-sharing among the DGs, ESSs, and utility grids. Thus, this article provides a critical summary of two main aspects of DC microgrids, such as protection and planning. Since the mentioned aspects are mutually dependent, a discussion of an aggregated point of view is included. The advantages and disadvantages of different protection and planning approaches are well documented. The possible improvements of existing protection and planning methods are outlined. The key research areas are identified, and future research directions are mentioned so that cutting-edge technologies can be adopted, making the review article unique compared to the existing reviews. The article could be an excellent foundation and guidance for industry personnel, researchers, and academicians.