Method for judging insulation aging degrees of alternating current (AC) cables

Abstract

The invention relates to a method for judging insulation aging degrees of alternating current (AC) cables. The method has the following beneficial effects: different insulation aging rules of the AC cables are obtained through space charge measurement and physico-chemical performance test and in combination with carbonyl indexes of the unaged cables, computed through comparison,,the cables aged one year and the cables operated for 30 years. The method is characterized by after drying three kinds of cable samples at different aging degrees, carrying out charge accumulation characteristic test, weightlessness percentage determination, activation energy TG value computation, infrared spectroscopic analysis and carbonyl index computation in sequence and then drawing the relation curve of the carbonyl indexes, the sampling positions and the aging time. The method has the following beneficial effect: the insulation aging degrees of the AC crosslinked polyethylene (XLPE) cables are comprehensively judged according to the obtained test data.

Description

technical field [0001] The invention relates to a method for judging the insulation aging degree of AC cables. Specifically, it adopts a method combining space charge measurement and physical and chemical performance analysis to evaluate the aging state of accelerated insulation aging cables and long-term actual operation cables, and judge XLPE AC cables. Insulation aging degree. It belongs to the technical field of power system measurement. Background technique [0002] Cross-linked polyethylene (XLPE) cables are widely used in power transmission networks. The measurement and evaluation of the cable insulation aging degree is an important content, which is conducive to making accurate suggestions for the replacement of the cable after aging. The method of measuring the space charge in the cable insulation through the action of the DC electric field is a common technique for evaluating the aging of the DC cable insulation, but it is still lacking in the evaluation of the i...

AI Technical Summary

Problems solved by technology

The variation law of the measurement data of unaged, accelerated aging and actual aging cable insulation can reflect the aging law of insulation under different aging methods, but the judgment of the aging state of cable insulation cannot be obtained by simply comparing the measurement data of the above three samples. out

[0003] Chinese invention patent "On-line Monitoring Method for Insulation State of XLPE Insulated Power Cable" (application number: 200610041888.9) solves the interference problem in the online monitoring of cable insulation aging state by DC component method, but it can only be used for medium and low voltage cable aging state Evaluation, there is no content that can reveal the aging law of cable insulation and select aging characterization parameters that adapt to different voltage levels; "A Method for Testing the Life of Medium-Voltage Solid Insulated Power Cables" (application number: 200810202541.7) discloses the aging through macroscopic parameters. state, and does not involve microscopic parameters that can reflect the aging law and aging state; "Test Method and Device for Accelerated Electrical Tree Aging of Polymer Power Cable Insulation" (application number: 200910103045.0) is published to study the aging process of electrical tree Discharge phenomena and analysis of the impact of electrical tree aging on insulation morphology (by microphotography), but it is of no value for judging the aging state of cables; A system for partial discharge detection of cables and accessories, mainly by receiving ultra-high frequency signals and acoustic signals in the process of partial discharge to improve detection sensitivity and accuracy

Since the causal link between the measurement of the partial discharge signal and the diagnosis of the aging state has not been fully established, the measured partial discharge signal cannot indicate that the cable aging has been detected, and there is no corresponding description in the patent

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