A Method for Identifying the Medium-Voltage Phase-to-Phase Short-Circuit Fault Section in Active Distribution Networks Based on the Equivalent Impedance Ratio of Low-Voltage Monitoring Nodes

Distributed generation (DG) integration into distribution networks brings new challenges to fault location in medium-voltage (MV) distribution networks. The popular smart fusion terminals on the low-voltage (LV) transformer area provide new data support for fault location in distribution networks. In this study, for phase-to-phase short-circuit faults in distribution networks, first, the mapping relationship between LV line voltage at each LV monitoring node and MV phase voltage sequence components is analyzed, the ratio of the impedances from each monitoring node and the short-circuit point to the system is defined as the equivalent impedance ratio, and a method for inversely calculating the equivalent impedance ratio using LV line voltage amplitude is proposed. Second, a method for identifying the phase-to-phase short-circuit fault section of MV distribution networks based on the impedance ratio change characteristics is proposed. Next, the analysis model for phase-to-phase short-circuit faults in systems containing DG is established, and the influence of its output characteristics on this method is analyzed. Finally, the simulating results show that this method is not affected by factors such as access locations and capacity of DG, simultaneous faults, transformer connections, fault resistance, transformer transmission error, measurement error, asynchronous data and load size and has a certain degree of robustness.