Analyses and Protection Methods of Single-phase Broken-line Complex Faults for Distribution Line

The occurrence of broken-line fault in distribution lines has been increasing annually, often accompanied by grounding fault, forming a complex fault. It will generate negative and zero sequence components, severely affecting normal operation of loads. Single-phase broken-line fault is typical in all kinds of broken-line faults, so this paper takes it as the research object, analyses and summarizes features of electrical quantities when single-phase broken-line fault with or without a grounding fault occurs, and proposes a set of criteria for single-phase broken-line fault. Additionally, methods for judging fault types and locations based on voltage criteria are studied. The impacts of asymmetry operation, instrument transformer broken-lines, and other abnormal conditions on the proposed criteria are analyzed, along with corresponding protection strategies. Finally, simulation is carried out in PSCAD/EMTDC, which validate the theoretical analysis and the effectiveness of the proposed protection methods.