Logarithmic derivative analysis method based insulation aging state evaluation method of crosslinked polyethylene (XLPE) cable

A cross-linked polyethylene and cable insulation technology, applied in the direction of measuring electricity, measuring electrical variables, and testing dielectric strength, etc., can solve the problems of insignificant change rules, deviation of evaluation results, and inability to reflect the aging state of cable insulation in time. To achieve the effect of reliable evaluation results, avoiding influence, and simple and easy evaluation methods

Active Publication Date: 2018-11-16
XI AN JIAOTONG UNIV
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  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

[0004] At present, the imaginary part of the dielectric constant is usually used to evaluate the aging state of the cable insulation, and the change rule is not obvious, resulting in deviations in the evaluation results, which cannot reflect the aging state of the cable insulation in time

Method used

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  • Logarithmic derivative analysis method based insulation aging state evaluation method of crosslinked polyethylene (XLPE) cable
  • Logarithmic derivative analysis method based insulation aging state evaluation method of crosslinked polyethylene (XLPE) cable
  • Logarithmic derivative analysis method based insulation aging state evaluation method of crosslinked polyethylene (XLPE) cable

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Experimental program
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Effect test

Embodiment 1

[0030] The evaluation method for the aging state of XLPE cable insulation based on the derivative analysis method includes the following steps:

[0031] 1) Sample preparation:

[0032] Slice the XLPE cable insulation to obtain a circular slice with a thickness of less than 0.3mm and a diameter of 50mm, remove surface impurities with absolute ethanol, and take one of the slices as an unaged sample;

[0033] Take the remaining 3 slices and place them in a drying oven, and conduct a heating aging experiment at 130°C. The aging treatment time of the 3 slices is 10 days, 20 days and 50 days respectively, and 3 different aging samples are obtained;

[0034] A total of four target samples (1 unaged target sample, 3 aged target samples) were obtained;

[0035] 2) Electrode fabrication: perform ion sputtering (spraying gold) on both sides of the target sample to form two metal electrodes, and the diameter of the effective electrode of the target sample is 40mm.

[0036] 3) Dielectric...

Embodiment 2

[0048] 1) Sample preparation: Slice the XLPE cable insulation to obtain a circular sample with a thickness of 0.5mm and a diameter of 40mm, remove surface impurities with absolute ethanol, take one of the slices as an unaged sample, and take the remaining slices Placed in a drying oven, the heating aging test was carried out at 150°C. The aging time was 10 days, 20 days and 50 days, and there were four target samples including the unaged samples.

[0049] 2) Electrode production: ion sputtering is performed on the front and back sides of the target sample to form two metal electrodes, and the diameter of the circular effective electrode is 30 mm.

[0050] 3) Dielectric spectrum test: place the sample in the dielectric spectrum tester, set the test temperature, frequency range and voltage, start the dielectric spectrum tester, measure the frequency characteristics of the complex dielectric constant of the XLPE cable insulation, and measure The real part of the permittivity ε' a...

Embodiment 3

[0059] 1) Sample preparation: Slice the XLPE cable insulation to obtain a circular sample with a thickness of 0.2mm and a diameter of 30mm, remove surface impurities with absolute ethanol, take one slice as an unaged sample, and take the remaining slices Placed in a drying oven, the heat aging test was carried out at 100°C. The aging time was 10 days, 20 days and 50 days, and there were four target samples including the unaged samples.

[0060] 2) Electrode production: ion sputtering is performed on the front and back sides of the target sample to form two metal electrodes, and the diameter of the circular effective electrode is 20mm;

[0061] 3) Dielectric spectrum test: place the sample in the dielectric spectrum tester, set the test temperature, frequency range and voltage, start the dielectric spectrum tester, and measure the real part ε' and the imaginary part of the dielectric constant ε”; measure the frequency characteristics of the complex dielectric constant of the XL...

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Abstract

The invention discloses a logarithmic derivative analysis method based insulation aging state evaluation method of an XLPE cable. The XLPE cable is sliced in an insulated manner to prepare different objective samples, electrodes are prepared from the objective samples, the objective samples are then placed in a dielectric spectrum tester to obtain a dielectric constant real part epsilon' and a dielectric constant imaginary part epsilon''; and a curve that the dielectric constant real part epsilon' and the dielectric constant imaginary part epsilon'' change with the frequency is obtained, mathematical calculation is carried out on the dielectric constant real part epsilon' to obtain change of a first-order derivative of the logarithm of the diagonal frequency omega of the dielectric constant real part epsilon' with the frequency, and the insulated aging state of the XLPE cable is represented. According to the method, influence of DC in the low-frequency range on the dielectric relaxation process is avoided effectively, compared with traditional dielectric constant real and imaginary pars, the change rule is more obvious, the aging state is indicated more clearly, the method is simple in operation, and an evaluation result is accurate.

Description

technical field [0001] The invention belongs to the field of insulation detection of electric equipment, and in particular relates to a method for evaluating the aging state of cross-linked polyethylene cable insulation based on a pair derivative analysis method. Background technique [0002] Cross-linked polyethylene (XLPE) cables are widely used in power transmission networks due to their excellent mechanical and dielectric properties. However, the cable insulation is affected by heat, electric fields and other environmental factors during operation, and its performance deteriorates. Such as hardening, cracking, increased conductivity, and increased dielectric loss. The design service life of XLPE cables is generally 30 years. A considerable number of cables in my country have entered the middle and late stages of their service life, and the probability of failure has also increased significantly. Therefore, it is necessary to characterize the aging state of cable insulati...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12G01R27/26
CPCG01R27/2694G01R31/1272
Inventor 李建英张媛媛武康宁
Owner XI AN JIAOTONG UNIV
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