Resonant earthed system fault line selection method with invariant moments

A system fault, resonance grounding technology, applied in the fault location and other directions, can solve problems such as adaptability to be verified

Active Publication Date: 2014-05-28
FUZHOU UNIV
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  • Resonant earthed system fault line selection method with invariant moments
  • Resonant earthed system fault line selection method with invariant moments
  • Resonant earthed system fault line selection method with invariant moments

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Embodiment Construction

[0064] Such as figure 1 As shown, the present invention provides a resonant grounding system fault line selection method using constant moment, comprising the following steps:

[0065] S1: Record the (transient) zero-sequence current waveform (sampling frequency is set to 2kHz) measured at the head end of each line within 1 power frequency cycle after the fault occurs;

[0066] S2: Let the gray level of each point on the measured (transient) zero-sequence current waveform curve be 1, and the rest be 0, to obtain the image gray level distribution function F(t,i), where the independent variable t represents time, and the dependent variable i represents zero-sequence current; it is equivalent to converting the current waveform diagram into a binary two-dimensional diagram;

[0067] S3: Bring the image gray distribution function F(t,i) of the obtained zero-sequence current waveform (two-dimensional image) into the invariant moment formula, find 11 invariant moments reflecting the...

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Abstract

The invention relates to a resonant earthed system fault line selection method with invariant moments. The method comprises the following steps that S1, zero-sequence current waveforms measured at the head ends of all circuits within a working frequency period are recorded after a fault occurs; S2, the point gray levels of curves of all the measured zero-sequence current waveforms are one, the other point gray levels are zero, and an image gray level distribution function F(t, i) is obtained; S3, the image gray level distribution function F(t, i) of the obtained zero-sequence current waveforms is substituted in an invariant moment formula, 11 invariant moments reflecting image characteristics are obtained, and four invariant moment characteristic quantities, psi4, psi6, psi9 and psi11 expressing an image axial symmetry relation are extracted; S4, spectrum clustering analysis is carried out on the invariant moment characteristic quantities, psi4, psi6, psi9 and psi11, and a cluster tree is output; S5, according to cluster validity indexes, the optimal cluster tree is selected out, and fault line selection is carried out. The method is accurate in line selection, and can improve reliability of power distribution network fault line selection.

Description

technical field [0001] The invention relates to the field of distribution network automation relay protection, in particular to a fault line selection method for a resonant grounding system using invariant moment. Background technique [0002] When a single-phase ground fault occurs in the resonant grounding system, due to the compensation effect of the inductance current of the arc suppression coil on the capacitance current of the grid, only a small fault current is generated, and the voltage of each line remains basically unchanged, which does not affect the power supply to the load. According to my country's electric power safety regulations, the resonant grounding system can continue to operate with a single-phase ground fault for 1 to 2 hours [1] , with high power supply reliability. However, a single-phase ground fault will increase the voltage of the non-faulted phase, and long-term operation with faults will easily cause breakdown of weak insulation, making the fau...

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Application Information

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IPC IPC(8): G01R31/08
Inventor 郭谋发许晔杨耿杰高伟缪希仁
Owner FUZHOU UNIV
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