Single-phase fault location method for low-resistance grounding system based on zero-sequence voltage distribution

In low-resistance grounding systems, single-phase ground faults trigger immediate protection tripping. Accurate fault location reduces patrol time and increases the reliability of the power supply. However, time synchronization errors and inaccurate line parameters degrade the location accuracy. To address these issues, a fault location method based on distribution characteristics of zero-sequence voltage is proposed in this paper. Firstly, the amplitude and phase distribution equations of the zero-sequence voltage along the faulted line are derived from the zero-sequence current distribution. Then, a corresponding fault location method is developed. When redundant measurement information is unavailable upstream of the fault point, the initial fault distance is calculated using measurements at both ends of the line and measured line parameters. The precise fault location is then determined by searching within the suspected fault area. In the presence of redundant measurements, a dual-constraint location model based on amplitude and phase is proposed from the perspective of phasors. An improved particle swarm optimization algorithm is used to solve for fault distance and actual line parameters. Additionally, a location method based on function fitting is proposed, using branch line measurements to determine the amplitude distribution equation and then solve for fault distance. Simulation results demonstrate that the proposed algorithm is immune to synchronization errors and can overcome the adverse effects of inaccurate line parameters when redundant measurements are available upstream.