Distribution network fault line selection method based on wavelet coefficient correlation analysis in three-phase breaking current component characteristic frequency band

A technology of sudden change of current and characteristic frequency band, applied in directions such as fault locations, which can solve problems such as interference signals, low reliability, and influence on line selection results.

Active Publication Date: 2013-07-10
KUNMING UNIV OF SCI & TECH
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Problems solved by technology

[0005] The purpose of the present invention is to propose a distribution network fault line selection method based on the wavelet coefficient correlation analysis in the characteristic frequency band of the three-phase sudden current component for the distribution network that only has three-phase current transformers and no zero-sequence current transformers installed. Overcome the shortcomings of the existing zero-sequence current fault line selection method, which is not reliable and the fault line selection method based on the time-domain waveform correlation analysis of the three-phase current mutation, and the interference signal affects the line selection results.

Method used

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  • Distribution network fault line selection method based on wavelet coefficient correlation analysis in three-phase breaking current component characteristic frequency band
  • Distribution network fault line selection method based on wavelet coefficient correlation analysis in three-phase breaking current component characteristic frequency band
  • Distribution network fault line selection method based on wavelet coefficient correlation analysis in three-phase breaking current component characteristic frequency band

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Embodiment 1

[0073] Example 1: The single-phase ground fault simulation model of 110kV / 35kV distribution network is as follows figure 2 As shown, it has 6 feeders, and the neutral point of the Z-shaped transformer is grounded through the series resistance of the arc suppression coil. overhead feeder =15km, =18km, =30km, wire-cable hybrid feeder =17km, the overhead feeder is 12km, the cable is 5km, and the cable feeder =6km, =8km. Among them, the overhead feeder is JS1 rod type, LGJ-70 type conductor, the span is 80m, and the cable feeder is YJV23-35 / 95 type cable. G in the power grid is an infinite power source; T is the main transformer with a transformation ratio of 110 kV / 35kV, and the connection group is / d11; Is a zigzag transformer; L is the arc suppression coil; R is the damping resistance of the arc suppression coil. The feeder adopts three types of lines: overhead line, overhead line-cable hybrid line and cable line. The load uses a constant power load model. f...

Embodiment 2

[0083] Embodiment 2: as figure 2 The parameters of the single-phase-to-ground fault simulation model of the 110kV / 35kV distribution network shown have been described in Embodiment 1 and will not be repeated here. Now assume the feeder A single-phase grounding fault occurs in phase A 4 kilometers away from the beginning, the grounding resistance is 60Ω, and the fault angle is 30°. The sampling frequency is 10kHz.

[0084] (1) After a fault occurs in the distribution network, the line selection device starts immediately, extracts the three-phase sudden change current data in the 5ms time window after the fault, and uses db4 wavelet to perform 6-layer decomposition, and uses the reconstructed wavelet coefficients to calculate each feeder in each frequency band As shown in Table 3, the energy sum corresponding to the frequency band 0Hz~78.125Hz is the largest, and the energy sum corresponding to the frequency band 2.5~5 Hz is next.

[0085] Table 3 Feeder Energy of ...

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Abstract

The invention relates to a distribution network fault line selection method based on wavelet coefficient correlation analysis in a three-phase breaking current component characteristic frequency band, and belongs to the technical field of electric system relay protection. After single-phase earth fault of a power distribution network with a feed-out line only provided with a three-phase current mutual inductor and not provided with a zero sequence current mutual inductor occurs, a line selection device is started, three-phase breaking currents of feeder lines are measured, three-phase breaking current data inside a time window 5 milliseconds after the fault occurs are extracted, wavelet decomposition and signal reconstruction of the three-phase breaking current data are carried out, reconstruction coefficients are used for calculating wavelet energy of feeder lines under frequency bands, the characteristic frequency band is determined according to the energy and the maximum principle, reconstruction coefficients in the characteristic frequency band are selected, correlation analysis is carried out on the reconstruction coefficients, comprehensive correlation coefficients of the feeder lines are calculated and determined through interphase correlation coefficients of the feeder lines, the comprehensive correlation coefficients serve as criterion characteristic quantity, and fault line selection is achieved according to a criterion principle. Lots of emulation results indicate that the distribution network fault line selection method is good in effect.

Description

technical field [0001] The invention relates to the technical field of electric power system relay protection, in particular to a new method for fault line selection of a distribution network using wavelet coefficient correlation analysis to determine the similarity of three-phase sudden current waveforms of feeder lines within a characteristic frequency band. Background technique [0002] When a single-phase ground fault occurs in a distribution network whose neutral point is grounded through an arc-suppression coil, the fault transient current amplitude is much larger than the steady-state current and is not affected by the arc-suppression coil. Compared with the steady-state component, the transient component after the fault has great advantages, making the line selection method based on the transient quantity the first choice for fault line selection. At present, most of the line selection methods based on transient quantities are based on the differences between the fau...

Claims

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Application Information

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IPC IPC(8): G01R31/08
Inventor 束洪春高利朱梦梦段锐敏
Owner KUNMING UNIV OF SCI & TECH
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