Protection and grounding methods in DC microgrids: Comprehensive review and analysis

DC microgrids (DCMGs) presents an effective means for the integration of renewable-based distributed generations (DGs) to the utility network. DCMGs have clear benefits such as high efficiency, high reliability, better compatibility with DC sources and loads, and simpler control, over its AC equivalent system. While advantages of DCMGs are considerable, of particular concern are the associated protection challenges, such as lack of phasor and frequency information, rapid fault current rise, breaking DC arc and certainly the lack of standards, guidelines and practical experience. This paper presents an extensive review of fault characteristics of DCMGs and the protection challenges. Innovative protection techniques proposed to solve these issues, and comparative analysis of these techniques are presented outlining the strengths and drawbacks of each. Possible improvements to the current technologies and future directions for research, which could enhance the protection of DCMGs, are outlined in this paper. •Fast capacitor discharge and the current rise in DC systems impose strict time limits for fault detection and interruption.•There are several grounding design considerations and tradeoffs in the selection of suitable DCMG grounding configuration.•Advanced data driven techniques with intelligent fault detection capability presents an effective DCMG protection solution.•Fast clearance action of fault current blocking converters can significantly improve post-fault behavior of the DC network.•DCMG Fault detection and interruption require further improvements, especially in terms of speed and accuracy.