Fault line selection method for earth faults occurred in different phases of two feeders connected to the same bus based on the ratio of zero-sequence admittance amplitude

Abstract

When the earth faults occur in different phases of two feeders connected to the same bus in the resonant grounding system, the conventional fault line selection devices are inaccurate. To address the difficulties of fault line selection in the earth faults that occurred in different phases of two feeders connected to the same busbar for resonant grounding system, the line zero-sequence admittance is calculated by the zero-sequence current at the first end of the line and the zero-sequence voltage of the bus. The analysis of the fault characteristics indicates that, the zero-sequence admittance amplitude in faulty lines is larger than that in the non-faulty line, and this characteristic also appears in the high-impedance grounding faults. Based on the ratio of zero-sequence admittance amplitude, a fault line selection method for earth faults occurring in different phases of two feeders connected to the same bus in a resonant grounding system is proposed. The difference in zero-sequence admittance amplitude between fault and non-fault lines is used to establish a line selection criterion, which allows all fault lines to be selected. The results simulated by PSCAD confirmed that the proposed method works effectively, with high accurary. This method is not affected by the fault location and the compensation degree of the arc suppression coil, and it can also withstand high fault resistances.

Keywords

• resonant grounding system
• faults of two feeders connected to the same bus
• earth faults occurred in different phases
• zero-sequence admittance
• the ratio of amplitude
• fault line selection