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Judgment method of single-phase grounding fault in small current grounding system

A single-phase grounding fault and low-current grounding technology, which is applied to the fault location, detects faults according to conductor types, and measures electricity.

Active Publication Date: 2021-01-05
NORTH CHINA INST OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, only the transient state method or the steady state method cannot solve the single-phase-to-ground fault identification problem well.

Method used

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  • Judgment method of single-phase grounding fault in small current grounding system
  • Judgment method of single-phase grounding fault in small current grounding system
  • Judgment method of single-phase grounding fault in small current grounding system

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Embodiment 1

[0016] The single-phase grounding fault judging method of the small current grounding system of the present invention comprises the following steps:

[0017] The first step is to extract the transient current characteristic component W value .

[0018] The maximum value of the current wavelet analysis mode coefficient when the small current grounding system works normally and the maximum value of the current wavelet analysis mode coefficient when the ground fault occurs are taken as the transient current characteristic component W value In this embodiment, the small current grounding system of 10KV overhead line is taken as an example.

[0019] Suppose the wavelet function Ψ(t) is compactly supported, in L 2 (R) The wavelet transform with a translation of τ and a scale of s in space can be defined as

[0020]

[0021] For the convenience of calculation, the scale and translation need to be discretized. Let the scale S=2 -j , translation τ=ks=2 -j , the high efficiency...

Embodiment 2

[0059] The difference between Embodiment 2 and Embodiment 1 is that the single-phase statistical vector ξ of the small-current grounding system constructed in the third step is different, because in practice, the data difference of the current and electric field measurements of each line is relatively large , the transient change of the current is also relatively large, and the maximum value of the wavelet analysis modulus coefficient is also different. Therefore, it is difficult to establish a single-phase-to-ground fault Fisher classification model with fixed parameters suitable for all line branches. In order to solve this problem, it is necessary to establish a generalized classifier so that the classifier has the ability of self-adaptive self-learning. The adaptive establishment of classifier parameters specifically includes the following steps.

[0060] Step 1: According to the statistical law of electric field drop when single-phase grounding occurs, set the ground fau...

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Abstract

The invention relates to a single-phase grounding fault judgment method for a small-current grounding system. A single-phase grounding fault judgment Fisher classifier combines the grounding fault feature vector signals of transient features and steady features. Research is conducted from the perspective of state transition, when a single-phase grounding fault occurs on a line in the small-currentgrounding system, the electric field and current change of the line is actually a steady change-to-transient change-to-steady change process. Therefore, with the method of the present invention adopted, an actual situation appearing when the single-phase grounding fault occurs can be simulated; and the Fisher classifier constructed by the method can quickly and accurately distinguish and determine the single-phase grounding fault of the small-current grounding system.

Description

technical field [0001] The invention relates to a method for judging a single-phase grounding fault in a small current grounding system. Background technique [0002] The single-phase ground fault judgment of 10KV overhead line has always been one of the difficult problems in the distribution network industry. In recent years, a large number of insulated conductors have been put into use in overhead lines, which further increases the difficulty of identifying single-phase ground faults with broken wires. Although the injection signal method, transient wave recording analysis method, first half-wave method, group amplitude and phase comparison method, zero-sequence power method and other methods have been proposed to solve the problem of single-phase ground fault line selection and location. However, due to factors such as the complex structure of the distribution network, the different grounding methods of the neutral point, the variable resistance of the single-phase groun...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/52G01R31/58G01R31/08
CPCG01R31/085G01R31/50
Inventor 顾涛
Owner NORTH CHINA INST OF SCI & TECH
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