Single-phase ground fault diagnosis method on various conditions of cable, overhead line, and parallel-serial line

Abstract

The invention, which relates to the technical field of circuit protection, provides a single-phase ground fault diagnosis method on various conditions of a cable, an overhead line, and a parallel-serial line. The method comprises: step a, an opening delta zero-sequence voltage at a PT secondary side is monitored; step b, whether a zero-sequence voltage occurs is determined; step c, whether the frequency of the zero-sequence voltage is a power frequency is determined; is not, a signal is sent out to respond to a moving element of a resonance elimination device; step d, three-phase voltage monitoring data are read; if voltage of one phase or voltages of two phases is / are normal-phase voltages and the voltages of other phases are zero, a PT primary side line-breaking fault is determined; step e, a single-phase ground switch that can be turned on or off normally can be put between a neutral point of the PT and the ground, so that a grounding switch trips and is closed rapidly; and step f, whether the opening delta voltage exists is determined; if so, a single-phase ground fault is determined; and if not, fundamental-frequency ferromagnetic resonance is determined. According to the multi-parameter rapid switch fault determination method, the method can be realized simply and reliably; and a fault loop can be disconnected rapidly by using a quick switch, so that accident extending can be avoided.

Description

[0001] Technical field: [0002] The invention relates to the technical field of circuit protection, in particular to a method for judging single-phase grounding faults in cables, overhead and hybrid lines. [0003] Background technique: [0004] It is of great significance for the safety protection of distribution network to study the occurrence of various types of single-phase ground fault types under various line conditions such as cables, overhead lines and hybrid lines. The existing fault identification methods mainly include the following types, and their characteristics are analyzed as follows: 1) The characteristics of the method based on fault current and voltage amplitude: it is generally applicable to low-resistance grounding faults, and the fault current is small when high-resistance grounding The change of current amplitude is not obvious and it is difficult to distinguish. 2) Methods based on low-frequency information and high-frequency information. Features: It...

AI Technical Summary

Problems solved by technology

At present, the detection algorithms based on wavelet transform all use wavelet transform to decompose the fault signal, extract a certain component, and then compare the variation of this component with the preset threshold to judge the type of system fault, but the setting of the hardware threshold requires According to expert experience, different system thresholds are generally different, which increases the difficulty of discrimination

4) The characteristics of the method based on artificial neural network: research shows that this method is very effective in detecting high-resistance grounding faults in the system, but it is difficult to implement; 5) The method based on fuzzy theory

Features: Although the method based on fuzzy theory can identify the fault type, this method needs to collect a large amount of fault data and cannot judge the specific fault phase.

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