DC current is considered one of the most promising solutions for power systems distribution when the quota of power electronics converters to be installed is significant. Among DC distribution systems, zonal electrical distribution systems (ZEDSs) are the most dependable ones, thanks to the possibility to provide more than one path to supply vital loads. However, fault protection may be harder to achieve due to the DC ZEDS additional complexity in respects to conventional radial distribution system. Several IEEE Standards provide useful recommendations, but a comprehensive universally recognized framework for the design of protections in DC ZEDS is still lacking. Moreover, most of the approaches proposed in literature require specific converter architectures or complex control algorithms. Thus, in this paper an approach to the protection design for a MW-scale ZEDS based on Commercial-Off-The-Shelf (COTS) components is presented, aimed at setting a base level of performance complying with the Standards requirements. An example of its practical implementation is shown, discussing its behavior for some significant fault cases.
