High-sensitivity local defect diagnosis method for power cable

A power cable, local defect technology, applied in the field of defect diagnosis, can solve problems such as failure to check early defects of cables, stay, weak degree of inability to change, etc.

Active Publication Date: 2016-08-10
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The existing relatively mature Time Domain Reflectometry (TDR) can use pulse signals to diagnose power cable faults. The application number is 201310063871.3, and the Chinese invention patent named "Time Domain Reflectometry System and Method" provides a method using time domain A method and system for determining conductor anomalies by reflection method, but this method is still unable to diagnose defects with a weak degree of change, and the resolution of TDR in multi-defect identification and near-end defect identification is not high enough
Partial discharge diagnosis of power cables is a method to detect local defects of cables, but due to the small amplitude of partial discharge signals, serious attenuation, difficulty in signal separation and difficulty in multi-fault identification, it is difficult to realize partial discharge diagnosis in actual measurement. Defects are diagnosed
At the same time, the partial discharge off-line test experiment is often a destructive experiment, which itself will have a certain impact on the structure of the cable
The existing power cable detection and diagnosis technology still stays in the fault diagnosis aspect, lacks the diagnosis of local defects with weak changes in cable structure parameters, and cannot troubleshoot early defects of cables, so it is of great significance to develop new technologies for local defect diagnosis of cables

Method used

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  • High-sensitivity local defect diagnosis method for power cable
  • High-sensitivity local defect diagnosis method for power cable
  • High-sensitivity local defect diagnosis method for power cable

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0047] The flow of the power cable local defect diagnosis method in this embodiment is as follows: figure 1 As shown, the comparison distance diagnostic map of the tested power cable and the reference power cable is as follows figure 2 As shown, it is a local defect diagnosis for a 100m ZR-YJV22-8.7 / 15 power cable, and the defect type is a loose copper shielding layer defect. The diagnostic method includes the following steps:

[0048] (1) Data measurement of the cable to be tested

[0049] Transmit low-voltage pseudo-random signal V to the 100m ZR-YJV22-8.7 / 15 power cable under test i , measuring the reflected signal V reflected from the end of the cable r ,pass Calculate the magnitude |Γ of the reflection coefficient spectrum of the cable d (f)| and the real part of the reflection coefficient spectrum Real(Γ d (f)) and the imaginary part Imag(Γ d (f)).

[0050] (2) Data processing of the cable to be tested

[0051] Using the conversion function f→t′, the measured ...

Embodiment 2

[0067] The flow of the power cable local defect diagnosis method in this embodiment is as follows: figure 1 As shown, the comparison distance diagnostic map of the tested power cable and the reference power cable is as follows Figure 4 As shown, local defect diagnosis is carried out for 1500m10kV XLPE power cable, and the defect type is also a serious deformation defect of the insulating medium, including the following steps:

[0068] (1) Data measurement of the cable to be tested

[0069] Transmit low-voltage high-frequency narrow pulse V to the tested 1500m ZR-YJV22-8.7 / 15 power cable i , measuring the reflected signal V reflected from the end of the cable r ,pass Calculate the magnitude |Γ of the reflection coefficient spectrum of the cable d (f)| and the real part of the reflection coefficient spectrum Real(Γ d (f)) and the imaginary part Imag(Γ d (f)).

[0070] (2) Data processing of the cable to be tested

[0071] Using the conversion function f→t′, the measure...

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Abstract

The invention discloses a high-sensitivity local defect diagnosis method for a power cable. According to the method, on the basis of a power cable reflection coefficient spectrum of a frequency domain, a reflection coefficient spectrum of a power cable is measured and analyzed by using a non-destructive test technology; positioning of a local defect of a power cable is realized by combining a strobing gate and a modern digital signal processing technology; and a wave velocity obtained by a rear part or a virtual part of the reflection coefficient spectrum after conversion, of the measured cable is compared with a wave velocity of a new cable and the difference between the reflection coefficient spectrum value after conversion and a corresponding simulated fitting curve are combined, thereby realizing evaluation on the severity degree of the local defect. Compared with the prior art, positioning of a local defect with a weak changing degree and multi-defect identification are realized; and the severity degree of the local defect of the power cable can be evaluated.

Description

technical field [0001] The invention relates to defect diagnosis technology during power cable operation, and more specifically relates to a diagnosis method for local defects of power cables. Background technique [0002] Cross-linked polyethylene (XLPE) power cables are widely used in my country's electric power industry because of their reliable electrical and mechanical properties. In the early 1990s, my country carried out a large number of urban network transformation work, and a large number of cables began to be applied to urban power grids. However, due to the influence of the manufacturing process and long-term operating conditions, power cables often suffer from moisture, overheating, extrusion, excessive bending, etc., resulting in water trees, deformation of the insulation medium, loose copper shielding, etc. Local defects, if the local defects of the power cable are not dealt with, the local defects of the power cable will develop rapidly under the action of t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12
CPCG01R31/1272
Inventor 周凯谢敏赵世林何珉张福忠冉立
Owner SICHUAN UNIV
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