Wasserstein distance-based pilot protection scheme for hybrid AC/DC distribution network

In hybrid AC/DC distribution networks (DNs), the fault current flow markedly differs from that in conventional passive DNs, which is caused by the current contribution from distributed energy resources (DERs) and the integration of soft open points (SOPs). Such complexities significantly undermine the effectiveness of conventional overcurrent protection methods, often resulting in erroneous tripping. To address these challenges, this paper delves into the impacts of SOPs and DERs with various fault ride-through (FRT) control strategies on fault current flow during balanced and unbalanced faults, highlighting the potential limitations of legacy overcurrent and pilot protection schemes in the context of emerging hybrid AC/DC DNs. Building on this analysis, we propose a pilot protection scheme leveraging the Wasserstein distance, which capitalizes on the waveform shape differences of fault currents on either side of the distribution lines. Through extensive simulation analysis, the proposed protection scheme demonstrates robustness against a range of factors, including various fault locations, fault types, fault resistances, and the impacts of white noise, thereby ensuring the efficacy of the proposed protection.