The invention relates to the field of single-phase grounding fault detection for a distribution network of an
electric power system, and particularly relates to a line
selection method for a different-phase two-point successive grounding fault of a distribution network line. The line
selection method specifically comprises the steps of (1) real-
time data acquisition, (2) grounding fault start judgment, (3)
grounding line selection, (4)
short circuit fault start judgment, (5) two-point
grounding line selection and (6) fault return judgment. According to the invention, a line selection task is started when zero-sequence
voltage is detected to exceed a set value, a single grounding fault line is selected, then
short circuit fault start judgment is performed in a cyclic manner in a fault period, a different-phase two-point grounding fault is judged to occur if zero-sequence current is detected to exceed a
short circuit set value, two lines with the maximum fundamental wave amplitude are found, and the two lines are judged to be grounding lines if the two lines are equal in amplitude and opposite in phase. The line
selection method effectively solves a problem of line selection for the different-phase two-point successive grounding fault of the distribution network line, thereby being conducive to improving the work efficiency, reducing the power failure range, guaranteeing safe running of the
system and reducing personal casualties.