Line selection method for different-phase two-point successive grounding fault of distribution network line

Abstract

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.

Description

technical field [0001] The invention relates to the field of detection of single-phase grounding faults in distribution networks of electric power systems, in particular to a line selection method for two-point successive grounding faults of phases with different names in distribution networks. Background technique [0002] Most of the low-voltage distribution networks in my country adopt the neutral point ungrounded method or the neutral point grounded method through the arc suppressing coil. When a single-phase ground fault occurs in this type of power grid, the fault relative to ground voltage drops, and the non-fault relative ground voltage rises. The magnitude of the drop or rise is related to the specific grounding type. For metallic grounds, the fault phase-to-earth voltage drops to near zero, while the non-fault phase-to-earth voltage rises to line voltage level. Due to the rise of the non-fault phase-to-ground voltage, if the grounding time is too long, it may caus...

AI Technical Summary

Problems solved by technology

[0004] In view of the fact that the existing line selection device can only solve the problem of single-phase grounding of the line, but cannot solve the problem of successive grounding at two points of different phases of the line, the present invention proposes a fault line selection method for two points of successive grounding of different phases of the line in the distribution network. During the single-phase grounding period, if two points of different phases of other lines are grounded successively, the invention can accurately find out the grounding line

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