Insulating cable residual service life comprehensive evaluation method based on physical, chemical and electric properties

A technology for comprehensive evaluation of insulated cables, applied in the field of electric power, can solve problems such as the inability to accurately simulate the non-uniform working environment of cables, the inability to well reflect the physical and chemical properties of cables, and the inability to accurately judge local defects of cables, etc.

Active Publication Date: 2015-07-22
SOUTH CHINA UNIV OF TECH
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  • Application Information

AI Technical Summary

Problems solved by technology

[0004] 1) The electrothermal aging method simulates the working state of the cable through the constant voltage method, the step-by-step withstand voltage method or the residual voltage method, and uses the Weibull distribution statistical method to calculate the remaining life of the cable, but it cannot accurately judge the local defects of the cable. At the same time, it cannot well reflect the physical and chemical characteristics of the cable when it is aging.
[0005] 2) Differential scanning calorimetry can quickly evaluate the life of the cable by measuring the crystallinity and temperature variation of the cable sample, combined with conventional methods, but it cannot accurately simulate the non-uniform working environment when the cable is running

Method used

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  • Insulating cable residual service life comprehensive evaluation method based on physical, chemical and electric properties
  • Insulating cable residual service life comprehensive evaluation method based on physical, chemical and electric properties
  • Insulating cable residual service life comprehensive evaluation method based on physical, chemical and electric properties

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Embodiment 1

[0054] like figure 1 As shown, the insulated cable of this embodiment is an XLPE insulated cable, and the comprehensive evaluation method of its remaining life includes partial discharge test, step-by-step withstand voltage test, thermal aging test and activation energy test, as follows:

[0055] 1) Partial discharge test

[0056] Partial discharge test is a commonly used test method for extruded insulated cables. It can indirectly reflect the insulation damage of the internal structure of the cable by measuring the partial discharge of the cable sample. In the production process of extruded cables, there will inevitably be bubbles inside. Under the action of the working voltage, due to the different dielectric constants of the solid medium and the gas medium, the air gap breakdown field strength is much lower than the solid breakdown field strength. Therefore, there will be partial discharge in the air gap for a long time without breakdown, but the active molecules generated...

Embodiment 2

[0099] In this example, a specific experiment is taken as an example to illustrate, and six XLPE insulated cable samples (respectively S1, S2, S3, S4, F1 and F2) are selected, wherein S1 and S2 are cable samples produced by Sumitomo Japan in 1985, S3 and S4 is a cable sample produced by Furukawa, Japan in 1985, F1 and F2 are cable samples produced by Sumitomo, Japan in 1996

[0100] In the comprehensive evaluation method for the remaining life of the insulated cable in this embodiment, the specific implementation steps of the various test schemes involved are as follows:

[0101] 1) Partial discharge test

[0102] 1.1) Perform pulse current test on each cable sample, apply a voltage change ΔU to the sample, and record the ΔU generated by each sample d ;

[0103] 1.2) According to the formula (2) of the above-mentioned embodiment 1, the PD amount q is calculated and obtained in combination with the parameters of various capacitors used in the test, as shown in Table 1 below. ...

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Abstract

The invention discloses an insulating cable residual service life comprehensive evaluation method based on physical, chemical and electric properties. An insulating cable is an XLPE (Cross Linked Polyethylene) insulating cable. The method comprises a partial discharging amount test, a gradual layer voltage-resisting test, a thermal aging test and an activating energy test; an insulating state of an XLPE insulating cable sample is obtained according to a partial discharging amount calculated by he partial discharging amount test; a residual service life numerical value range of the XLPE insulating cable sample is obtained according to testing results of the gradual layer voltage-resisting test, the thermal aging test and the activating energy test. The method can integrate a plurality of indexes of cable aging evaluation, and combines macroscopic and microscopic change conditions, so that the residual service life data of the cable is completely analyzed in the three aspects of physical performances, chemical performances and electric performances, and the method has important guiding meanings on line modification and power grid planning.

Description

technical field [0001] The invention relates to a method for evaluating the remaining life of a cable, in particular to a method for comprehensively evaluating the remaining life of an insulated cable based on physical, chemical and electrical characteristics, and belongs to the field of electric power technology. Background technique [0002] XLPE (cross-linked polyethylene) insulated cables have good electrical and mechanical properties and are widely used in power transmission networks. In my country, XLPE insulated cables have been put into use since the 1980s. So far, some cables have been in service for more than 20 years, and a small number of cables have been running for nearly 30 years. The design life of cables is generally 30 years. Aging condition. Due to the different cable manufacturers, laying conditions and operating environments, the aging conditions of cables are not the same. At the same time, domestic research on cable life mainly focuses on a certain in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/12G01N25/00G01N5/04
Inventor 金尚儿刘刚
Owner SOUTH CHINA UNIV OF TECH
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