Power distribution network single-phase earth fault line selection method and system based on grounding transformer tapping tap grounding

Abstract

The invention discloses a power distribution network single-phase earth fault line selection method and system based on grounding transformer tapping tap grounding, and the method comprises the steps:firstly setting a grounding branch for uniformly adjusting the winding access amount at a transformer winding tap, and closing a switch of the grounding branch at a fault phase when a single-phase earth fault happens to a power distribution network; secondly, adjusting a fault phase winding tapping tap in the grounding transformer to two different access gears, measuring all feeder zero-sequencecurrents of the system under the different access gears at the same time, calculating the variation of the feeder zero-sequence currents of the system before and after the access gears are changed, regarding that the feeder with the largest variation of the zero-sequence currents is the fault feeder, and completing fault line selection. Fault line selection can be completed only by adjusting tap gears of a winding of the grounding transformer, the grounding transformer is existing in a transformer substation, only corresponding taps and grounding branches need to be added, corresponding line selection equipment does not need to be added, the investment cost is greatly reduced, and the high economical efficiency is achieved.

Description

technical field [0001] The invention belongs to the field of distribution network fault line selection, and in particular relates to a single-phase ground fault line selection method and system of a distribution network based on grounding transformer tap tap grounding. Background technique [0002] The structure of the distribution network is complex and there are many outgoing lines, so single-phase ground faults are prone to occur. my country's distribution network widely uses the grounding method of the neutral point through the arc suppression coil, but at the same time it also reduces the fault current, the fault characteristics are not obvious, and the accuracy of fault line selection is greatly reduced. If the fault is not cleared in time, the ground fault will easily develop into a phase-to-phase fault, causing power outages for users and even damage to related electrical equipment. It can be seen that improving the accuracy of fault line selection is a necessary co...

AI Technical Summary

Problems solved by technology

The steady-state line selection method is to use the steady-state signal that continues to exist during the grounding period to select the line, but the required active component or harmonic component is usually small in amplitude, and its content is much smaller than the steady-state zero-sequence power frequency current, so The steady-state line selection method is easily disturbed by system noise, and it may be difficult to perform accurate line selection during fault transients where the system is highly disturbed

The transient class line selection method uses the transient signal generated at the initial stage of grounding to select the line, but these components are inherently unstable, uncertain and transient, and their frequency, amplitude and other parameters are different under different system structures and fault conditions. It has a large range of changes, which will cause difficulties in feature extraction and protection setting, and also put forward higher requirements for the sampling frequency of the device

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