Abstract: The operational stability of the 10 kV distribution network directly determines the power supply reliability of the power system for users. However, open-circuit faults in the distribution network are highly harmful and difficult to identify, and research on such faults is conducive to the safe and stable operation of the distribution network. Based on the fracture boundary conditions and fault equivalent circuits of single-phase open-circuit faults, composite sequence network models for three types of faults, open-circuit without grounding, open-circuit with grounding on the power supply side and open-circuit with grounding on the load side, were established under different neutral grounding modes of the distribution network. The analytical expressions of sequence voltages at the measurement points of the 10 kV bus and the end of the 10 kV faulty line under fault conditions were derived. The relationships among sequence voltages, open-circuit fault location, neutral grounding mode and transition resistance were analyzed. MATLAB/Simulink was used for simulation verification, and the simulation results are in good agreement with the theoretical analysis.This research can provide a theoretical basis and analytical methods for the diagnosis of open-circuit faults in distribution networks.

    Key words: distribution network; open-circuit fault; sequence voltages analysis; composite sequence network model