Low current neutral grounding system fault route selecting method by wavelet package decompose and correlation analysis

A wavelet packet decomposition, small current grounding technology, applied in fault locations, electrical components, emergency protection circuit devices, etc., can solve the problem of not being able to distinguish faulty lines and non-faulty lines to the greatest extent

Inactive Publication Date: 2008-04-16
KUNMING UNIV OF SCI & TECH
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Problems solved by technology

Literature [9-11] selects lines on the basis of multiple frequency bands, but only uses the amplitude or polarity of transient currents, and only uses part of the transient information, which cannot distinguish faulty lines from non-faulty lines to the maximum extent.

Method used

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  • Low current neutral grounding system fault route selecting method by wavelet package decompose and correlation analysis
  • Low current neutral grounding system fault route selecting method by wavelet package decompose and correlation analysis
  • Low current neutral grounding system fault route selecting method by wavelet package decompose and correlation analysis

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Embodiment Construction

[0099] When a single-phase ground fault occurs in a low-current grounding system, the above principles can be used to achieve perfect fault line selection. The specific implementation process is shown in Figure 6.

[0100] Concrete implementation steps of the present invention are as follows:

[0101] 1. When the bus zero-sequence voltage instantaneous value u n (t) greater than K u u n , the fault line selection device starts immediately, and records the zero-sequence current of each feeder for one cycle before and after the fault, where K u The general value is 0.15, U n Indicates the rated voltage of the busbar;

[0102] 2. Use db10 wavelet to decompose the zero-sequence current of each feeder with four-layer wavelet.

[0103] 3. After removing the lowest frequency band (4, 0) where the power frequency is located, the frequency band with greater energy contains the main characteristics of the transient capacitive current [18] . Therefore, the energy summation of the...

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Abstract

The present invention relates to a small current grounding system fault line selecting method by wavelet package decomposition and relevant analysis, belonging to the power system relay protection technical field. The method comprises: starting the fault line selecting device and recording wave to acquire transient zero-order current on each of the feeder lines when bus zero-order voltage transient value exceeds limit; calculating energy on each of frequency bands of the transient zero-order current after wavelet package decomposition, summing the energy of transient zero-order current on all the lines according to frequency bands and selecting the frequency bands with the maximum and secondary value of energy and values as the characteristic frequency bands, applying relevant analysis method to line transient zero-order current on the selected characteristic frequency bands in order; and finally determining fault point integrating the relevant analysis results of two frequency bands. The method uses wavelet package decomposition and relevant analysis, thereby effectively using information (amplitude and phase) contained in fault transient process and reflecting differences between fault line and non-fault line to maximum degree. Principle analysis and simulations demonstrate that the method has precise and reliable line selection.

Description

Technical field: [0001] The invention relates to a fault line selection method of a small current grounding system by using wavelet packet decomposition and correlation analysis, and belongs to the technical field of electric power system relay protection. Background technique: [0002] In recent years, my country has done a lot of research on the line selection of small current grounding faults, and achieved certain results, but the problem of accurate and reliable line selection has not been well resolved. Failure to quickly and accurately detect ground fault points not only hinders the development of distribution automation, but also poses a threat to the safe and stable operation of the power grid. [0003] When a single-phase ground fault occurs in a low-current grounding system, zero-sequence voltage will appear in the entire system, and the current flowing through the fault point contains a transient quantity with a high amplitude. Compared with the weaker steady-stat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/26G01R31/08
Inventor 束洪春赵兴兵彭仕欣李斌董俊唐岚刘志坚刘可真孙士云邱革非
Owner KUNMING UNIV OF SCI & TECH
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