How MVDC Distribution Can Impact AC Grids: Research Topics and CHIL Validation

This paper outlines key research topics on MVDC (Medium Voltage Direct Current) and LVDC (Low Voltage Direct Current) distribution, emphasizing protection aspects and operational benefits. The study explores various topologies for MVDC links, including point-to-point and multi-terminal configurations, used as counter-feeding island generators and flexible meshing links. These topologies were examined through simulations and validated using a CHIL (Control Hardware-In-the-Loop) real-time test setup. Additionally, hybrid AC/DC grid structures, which integrate both loads and generators in the DC portion, were analyzed through simulations and CHIL validation within a multi-level (MVDC/LVDC) distribution grid. Protection aspects were investigated by simulating the fault characteristics of AC/DC converters, considering both AC-side and DC-side faults, and ensuring protection coordination. Finally, a protection system for a multi-terminal MVDC grid was physically implemented and validated within the multi-level (MVDC/LVDC) distribution grid CHIL setup.