Restoration Strategy for Bipolar MVDC Systems Following Fault Events

Medium-voltage DC (MVDC) distribution systems are increasingly recognized as a practical solution for upgrading heavily loaded MVAC feeders, particularly where DER integration, efficiency demands, and limited space for new line construction hinder expansion. Retrofitting existing AC overhead lines allows a three-phase feeder to be converted into a bipolar MVDC line with a dedicated neutral conductor. This approach is particularly suitable for South Korea, where MVAC feeders have a dedicated neutral conductor and spare crossarm positions at the poles. While this approach reduces infrastructure costs, it introduces new challenges for protection and post-fault restoration due to limited availability of the DC circuit breakers