A novel method for single-phase-to-ground fault diagnosis based on steady-state zero-sequence current reference values

Line and section selection is a key link in the effective management of single-phase ground faults in distribution networks. To address the issues of insufficient identification capability and poor adaptability of existing steady-state quantity-based single-phase fault diagnosis methods, this paper proposes a new method based on the steady-state reference value of zero-sequence current. First, the zero-sequence current values of each switch on non-faulty feeders are collected after each fault occurs to form the reference values. After a fault occurs, the difference between the real-time zero-sequence current value and the reference value of each switch is calculated, which is used as the fault characteristic quantity (FCQ). During the fault line selection stage, the FCQ of each switch is compared, and the feeder whose switch has the highest FCQ is determined to be the faulty one. In the fault section selection stage, if the ratio of the FCQs between any two switches on the faulty feeder exceeds a preset empirical threshold, the fault is determined to lie between these two switches. Theoretical analysis and simulation verification show that the proposed method exhibits high accuracy and sensitivity under complex scenarios, such as resonant grounding systems, overhead-cable hybrid lines, and three-phase unbalanced loads. Further field case analysis confirms that the proposed method possesses the characteristics of fast identification speed, low computational complexity, and high reliability.