Method for identifying high-resistance grounding fault section in single-neutral-point low-resistance grounding active distribution networks

• Single-neutral-point low-resistance grounding active distribution network. • Fault direction discrimination using direction-indicating voltage. • High-resistance grounding fault section identification. • Maximum allowable measurement error boundary calculation. The paper focuses on single-neutral-point low-resistance grounding (SNP-LRG) active distribution networks (ADNs) where the distribution system adopts the low-resistance grounding mode, and distributed generation (DG) grid-connected transformers adopt the ungrounded mode. The study analyzes the characteristic relationship between zero-sequence voltage and current at switches on the main line and branch lines during positive and negative direction single-phase ground faults. Based on this analysis, a directional discrimination principle for single-phase grounding faults using direction-indicating voltage (DIV) and a corresponding fault section identification method is proposed. The impact of transition resistance (TR) and DG capacity on the proposed method is analyzed, and a calculation method for the maximum allowable measurement error boundaries (MAMEBs) under different TRs is proposed. Simulation results demonstrate that the proposed method can achieve accurate and reliable section-level ground fault identification even with a TR of 3000 Ω, unaffected by arc discharge phenomena during ground faults or the integration of DG. Compared to the widely proposed phase-based detection methods for SPGFs, the proposed method maintains accurate judgment at a TR of 3000 Ω while significantly enhancing adaptability to grid topology changes and DG integration. Furthermore, this study quantifies the MAMEBs for measurement equipment, providing clear guidance for the selection and evaluation of measurement devices in engineering applications. Simulations confirm that the proposed method ensures accurate fault section identification at a TR of 3000 Ω when considering a measurement absolute error of 0.0244 kV.