1. School of Electrical and Electronic Engineering, North China Electric Power University, Baoding 071003, China; 2. Electric Power Research Institute of State Grid Shandong Electric Power Company, Jinan 250061, China
The probability of single-pole grounding faults on lines of DC distribution network is high. It is difficult to identify the fault due to the large variation range of the transition resistance. With regard to the protection against single-pole grounding faults of medium-voltage DC lines in ring-shaped DC distribution networks, this paper analyzes the zero-mode network of the system after single-pole grounding fault. Based on the zero-mode network, the mathematical models of internal-fault and external-fault are established. Then the Hausdorff distance algorithm is employed to compare the similarity between the sampled zero-mode differential current and the calculated value obtained by the internal-fault and external-fault models, which achieves rapid identification and isolation of the fault. It is simple to set the relay threshold as well. Finally, the feasibility of the protection scheme is verified via a simulation model in PSCAD/EMTDC. The results show that the proposed scheme has high fault identification accuracy and tolerance to transition resistance.
DAI Zhihui, LIU Xueyan, HUANG Min,et al.Similarity Comparison Based Single-pole Grounding Fault Protection for Lines in Ring-shaped Flexible DC Distribution Network[J].Automation of Electric Power Systems,2019,43(23):107-115.DOI:10.7500/AEPS20190114001Copy