Identification of Single-Phase Line Break Fault Direction Based on Local Voltage Information in Small Current Grounding System Considering the Impact of DG

Line break faults commonly occur in distribution networks and pose the risk of electric shocks to nearby individuals and animals. This study aims to address the challenge of identifying the direction of a line break fault. Specifically, we develop a model for a single-phase line break fault in a small current grounding system and focus on analyzing the steady-state voltage changes on both sides of the fault point. The voltage characteristics of the ungrounded system and the resonant grounding system are compared and summarized. Based on these characteristics, a more reliable method is proposed to identify the single-phase line break fault direction by utilizing two types of local voltage information: the magnitude of the line-to-line voltage and the sequence of phase-to-earth voltage. Additionally, we analyze the effects of V/V wired potential transformer (PT) and distributed generation (DG). The proposed method can accommodate the high utilization rate of V/V wired PT in distribution networks and its practicality is unaffected by the connection of DG to the distribution network. The above analysis is verified through simulations. The findings of this study demonstrate that the direction of a single-phase line break fault can be reliably detected using local voltage information and can be further localized with the assistance of communication, thereby improving the level of relay protection in distribution networks.