Low-current system single-phase earth fault line selection control circuit

Abstract

The invention discloses a low-current system single-phase earth fault line selection control circuit which comprises low-current system single-phase earth fault line selection control branch circuits used for controlling mixing electric transmission line branch circuits. Each low-current system single-phase earth fault line selection control branch circuit comprises a control unit, a motion unit and 2n zero-sequence current sensors, wherein the motion unit is used for controlling and predetermining one mixing electric transmission line branch circuit, and the 2n zero-sequence current sensors are installed in the mixing electric transmission line branch circuits and used for collecting zero-sequence current signals in cables. The control units receive zero-sequence currents sent by the zero-sequence current sensors and carry out judgment, if zero-sequence current values of two ends of any cable are consistent, the control units determine that earth fault points are not in any cable, the control units allow to send an automatic reclosing lock command, reclosing lock is carried out by the motion units, and if the zero-sequence current values at the two ends of at least one cable are different, the control units determine that a cable section is connected to the ground and output judgment results. According to the low-current system single-phase earth fault line selection control circuit, the reclosing lock is conditionally carried out, and therefore explosion caused by the reclosing lock when the fault points are generated in the cable section is avoided.

Description

technical field [0001] The present invention relates to the two technical fields of line selection for single-phase grounding faults in small current systems and line selection for faulty branches in DC systems in power systems, and specifically relates to line selection control for single-phase grounding faults in small current systems circuit. Background technique [0002] At present, the accuracy of line selection for single-phase grounding faults in low-current systems of power systems has always been a difficult problem that plagues power systems to quickly judge and deal with faults. In the event of a ground fault, the existing signals are collected on the current sensor and voltage sensor and different data processing methods are used to judge the fault branch. When the small current system uses the arc suppression coil grounding signal as the main capacitive current, And with the structural changes of the distribution network, the misjudgment of line selection will ...

AI Technical Summary

Problems solved by technology

By connecting a resistor controlled by the computer in parallel at both ends of the arc suppressing coil, the switching of the parallel resistance is controlled by the microcomputer measurement and control device, which can correctly judge the metallic grounding, high-resistance grounding and busbar grounding, and quickly find out the grounding fault This method can improve the accuracy of line selection, but it cannot completely solve the problem of correct line selection, because the correct line selection is not determined by the arc suppression coil; at the same time, in the transmission lines of the distribution network, most of them are composed of cables, The overhead line is composed of mixed lines. When a ground fault occurs in the cable part, the reclosing will cause the cable to explode and cause a greater accident.

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