Multi-Domain Investigation of Distance Protection in Converter-Dominated Grids: From Static to EMT and HIL

The increasing penetration of power electronic converter-based generation and HVDC systems is changing the fault behaviour of transmission networks. Distance protection schemes traditionally rely on predictable fault currents and stable impedance trajectories provided by synchronous generators. In converter-dominated grids these assumptions no longer hold due to current limitation and control-dependent fault current contributions of grid-following and gridforming converters. As a result, the apparent impedance seen by distance relays can deviate significantly leading to maloperation or reduced dependability and security. This paper presents a structured multi-domain framework for assessing distance protection performance in converter-dominated grids. The framework combines static…