Weak Distribution Network Fault Characteristic Analysis and Validation

Rural distribution networks exhibit inherent vulnerabilities characterized by extensive coverage with long supply lines, limited load capacity, and low automation levels, which collectively compromise fault diagnosis and management capabilities, thereby severely constraining power supply reliability. The high penetration of distributed generation (DG) further exacerbates these challenges by introducing diverse fault scenarios with variable characteristics, notably rendering conventional three-stage overcurrent protection methods ineffective. This necessitates urgent development of fault diagnosis solutions for rural networks lacking high-precision synchrophasor measurements. This paper establishes an equivalent fault model for small hydropower plants incorporating excitation control response and investigates the impact of DG integration on fault signatures in weak distribution networks. Given that the negative-sequence network is unaffected by DG penetration, a novel area protection method based on comparative analysis of boundary negative-sequence components is proposed. This approach enables accurate short-circuit fault diagnosis in critical protection zones while minimizing infrastructure upgrade costs. The effectiveness of the proposed method is validated with simulation case studies.