Single-phase ground fault line selection method and system for distribution network based on grounding transformer tap tap grounding

Abstract

The invention discloses a single-phase grounding fault line selection method and system of a distribution network based on grounding of grounding transformer taps. When a single-phase ground fault occurs in the power grid, close the switch of the grounding branch of the fault phase; secondly, adjust the faulty phase winding taps in the grounding transformer to two different access positions, and measure the Calculate the zero-sequence current of all feeders in the system, and calculate the change in zero-sequence current of each feeder in the system before and after the change of access gear. The feeder with the largest change in zero-sequence current is the fault feeder, and the fault line selection is completed. The fault line selection can be completed only by adjusting the tap position of the grounding transformer winding, and the grounding transformer is already in the substation, only need to add the corresponding taps and grounding branches, without adding the corresponding line selection equipment, which greatly reduces the investment cost and has the advantages of Very economical.

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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