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.

DC微电网（DCMG）为将基于可再生能源的分布式发电（DG）集成到公用事业网络提供了一种有效的手段。DCMG具有明显的优势，例如，与交流等效系统相比，效率更高，可靠性更高，与直流电源和负载的兼容性更好，控制更简单。尽管DCMG的优势相当可观，但尤其值得关注的是相关的保护挑战，例如相量和频率信息的缺乏，故障电流的快速上升，直流电弧的中断以及肯定缺乏标准，准则和实践经验。本文对DCMG的故障特性和保护挑战进行了广泛的综述。为解决这些问题而提出的创新保护技术，并提供了对这些技术的比较分析，概述了每种技术的优缺点。本文概述了可能对现有技术和未来研究方向进行的改进，以增强对DCMG的保护。