Time-Domain Differential Protection for Photovoltaic Distribution Networks Based on Hellinger Distance

With the advancement of 5G communication technology, differential protection has gained a solid foundation for application in distribution networks. However, frequency-domain differential protection methods based on Fourier transform are susceptible to errors caused by decaying DC components, while most existing time-domain pilot protection methods lack discussion on impacts from non-ideal conditions. To address these issues, this paper proposes a Hellinger distance-based time-domain pilot protection method for active distribution networks. First, the Hellinger distance algorithm is introduced, and two key indices—the Hellinger Distance Parameter (HDP) between current sequences from both ends and the threshold THR—are designed. Furthermore, an Enhanced HDP (EHDP) criterion incorporating a dynamic coefficient J is proposed to prevent maloperation caused by current transformer (CT) saturation. Finally, the proposed protection method is validated in PSCAD/EMTDC simulation software. Comprehensive comparative studies are conducted under various fault types, locations, transition resistances, and non-ideal conditions. Simulation results demonstrate the method's strong adaptability in active distribution networks and its robustness against non-ideal influences.