A phase selection method for single-phase transition resistance grounding fault in partitioned distribution network

Abstract

The invention discloses a zoned type power distribution network single-phase transition resistor earth fault phase selection method, comprising steps of dividing the power distribution network single phase transition resistor earth fault area into a low resistor earth fault area and a high resistor earth fault area according to the neutral point displacement voltage size U<n> when a transition resistor is connected to the ground, adopting a phase voltage amplitude-comparison method in the low resistor earth fault area to find out the phase where the voltage amplitude is the smallest from the three phases to determine as the earth fault phase, in the high resistor earth fault area, finding out the phase where the voltage amplitude value is the highest from the three phases, and determining the earth fault phase by determining the next phase of the phase having the highest voltage amplitude value as the fault phase according to a positive sequence method.

Description

technical field [0001] The invention belongs to the field of single-phase grounding fault processing of distribution network, and is mainly used for discriminating the fault phase when single-phase transition resistance grounding occurs in distribution network. Background technique [0002] When a single-phase ground fault occurs in the distribution network, due to the resistance of the fault point to the ground, it can be divided into two situations: one is a low-resistance ground fault or a metallic ground fault, and the other is a high-resistance ground fault. The single-phase-to-earth fault of the distribution network is treated with a fast switch, which is to close the fault relative to the ground, transfer the fault current, clamp the fault potential, and quickly deal with the single-phase-to-earth fault of the distribution network. The first thing to solve is to determine the problem of the fault phase. The common method is to identify the phase with the lowest amplit...

AI Technical Summary

Problems solved by technology

The first thing to solve is to determine the problem of the fault phase. The common method is to identify the phase with the lowest amplitude among the three-phase voltages as the ground fault phase, but this method is only applicable to metallic grounding or low resistance grounding faults, because only When the fault is grounded or low-resistance grounded, the phase voltage of the faulted phase is the lowest among the three phases. When a single phase of the distribution network is grounded through a transition resistance, especially when the grounding resistance of the grounding point reaches a certain value, the phase voltage of the faulted phase is the lowest among the three phases. The voltage may no longer be the lowest of the three phases

At this time, if the phase-voltage ratio-amplitude method is still used to select the phase with the lowest voltage as the ground fault phase, the wrong phase may be selected. If a fast single-phase grounding switch is used to close the fault relative to the ground, it will cause a short circuit between phases.

Because the short-circuit point is in the substation, it will cause serious short-circuit impact to the transformer

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