The integration of distributed generation (DG) units into distribution networks has challenged the
operating principles of traditional AC distribution systems, and also motivated the development of
emerging DC systems. Of particular concern are the challenges associated with the operation of
conventional protection schemes and/or devices. This paper first analyses the fault current character-istics in AC and DC distribution systems; it then presents a comprehensive review of the latest protection
methods proposed for distribution systems embedding DGs. In addition, the advantages and disadvan-tages of each method are outlined and compared. The differences between the protection algorithms
employed in/proposed for AC and DC systems are also discussed. Finally, this study identifies the future
trends and provides recommendation for researches in the field of protections of DC distribution
networks.