A Rapid Diagnosis Device for the Nature of Single-phase-to-Earth Fault in Distribution Network

Abstract

The invention provides a quick diagnostic and processing method of power distribution network single-phase earth fault characters. According to the method, the self-adaptive fault line selection method is used for selecting a one-phase earth fault line, an earth fault current transfer device is used for transferring the earth fault phase to enable the earth fault phase direct metal to be earthed, fault point currents are transferred, fault point voltages are clamped, and earth fault characters can be accurately judged. For instant earth faults, through earthing current transfer of the fault point, instant earthing arc of the fault point is extinguished quickly, intermittent arc light earthing overvoltage is avoided, insulation damage caused by long-time burning of arcs is avoided, instant faults are prevented from being converted to permanent earth faults, and the power grid fault rate is lowered; for permanent earth faults, fault characters can be quickly diagnosed and determined, fault lines are cut off within the shortest period, and the faults are prevented from expanding to endanger device and personal safety.

Description

technical field [0001] The invention belongs to the field of rapid diagnosis method and processing of single-phase grounding fault properties of distribution network, and is mainly used for judgment and processing of instantaneous grounding fault and permanent grounding fault of distribution network. Background technique [0002] There are two types of ground faults in the distribution network: one is instantaneous faults. In this case, the insulation at the fault point is not destroyed, but a transient ground fault occurs. Discharge to the ground under the condition of overvoltage or pollution migration, etc., once the discharge is closed, the insulation of the fault point will be restored, and the power grid will resume normal operation; the other type is a permanent fault, and the fault cannot be recovered by itself. The insulation of the fault point is permanently damaged, that is, the discharge junction, the insulation at the fault point will not be restored, and the po...

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Problems solved by technology

[0003] When a single-phase ground fault occurs in the distribution network, the regulations stipulate that it can operate with a ground fault for 2 hours. This is based on the fact that when the ground current of the distribution network is small, most instantaneous ground arcs can be extinguished by themselves, which is beneficial to improving the reliability of power supply in the distribution network. However, if the grounding current is large and the duration of the grounding arc is too long, due to the thermal ionization and photoionization of the arc, the insulation of the surrounding air will be damaged, and it will develop into a phase-to-phase short circuit that will endanger the safety of the power grid.

In addition, if a single-phase disconnection fault occurs, the disconnection of the wire on the power supply side will pose a threat to personal safety. There have been many accidents in China where a single-phase disconnection on the power supply side of the distribution line has caused personal injury and death.

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