Analyses and judgment methods of single-phase broken-line fault for loaded distribution line
The frequency of broken-line fault occurred in distribution network is increasing over the past years. Broken-line fault will create negative sequence and zero sequence voltages, which will seriously affect the normal work of loads. However, distribution network has not equipped with special protection against broken-line fault yet. In this paper, single-phase broken-line fault in distribution network is studied, features of the voltages at both ends of the fault line and the current flowing through the fault line are analyzed by using symmetrical component method combined with phasor diagrams when various single-phase broken-line fault occurs, and it proposes the main criterion and the additional criterions based on the theoretical analyses, as well as a method to judge the section that the broken-line fault located. Finally, simulation analysis is carried out through PSCAD/EMTDC, which ensures the correctness of the theoretical analysis and the protection criterions.