Evaluation method of xlpe insulation aging state based on different frequency dielectric loss ratio

Abstract

A method for evaluating the aging state of XLPE insulation based on the dielectric loss ratio of different frequencies, comprising the following steps: preparing sliced ​​samples of the inner, middle and outer layers of the cable insulation; performing dielectric loss measurements of the samples under the same conditions at 50Hz and 0.1H voltage ;Obtain the dielectric loss ratio of each sample at 0.1Hz and 50Hz, on this basis, calculate the dielectric loss ratio of each insulation layer and the insulation as a whole; according to the size and change law of the dielectric loss ratio of each layer, and the overall insulation The size of the dielectric loss ratio evaluates the aging state of the AC or DC cable XLPE insulation; according to the method of the present invention, the influence of uneven aging at different positions can be eliminated, which is conducive to reflecting the overall state of the insulation, and the aging degree of the AC and DC cable XLPE insulation Accurate evaluation; the sample size required for the test is small, and the voltage and capacity requirements of the test instrument are low; the ratio of the dielectric loss measurement value at different frequencies is used as the characteristic parameter, which reduces the system error of the test instrument and the influence of the external environment; no need Compared with historical data, engineering application is convenient.

Description

technical field [0001] The invention relates to a method for evaluating the aging state of XLPE insulation, in particular to a method for evaluating the aging state of XLPE insulation based on the measurement and comparison of dielectric loss tangents of polymer solid media at different frequencies. Background technique [0002] Dielectric loss tangent (tanδ, hereinafter referred to as "dielectric loss") is an important performance parameter to describe the insulation state of dielectric materials and electrical equipment. Dielectric loss can reflect the overall defects of the insulation (such as overall aging) and serious local defects (such as water trees); from the curve of dielectric loss versus voltage, it can be judged whether the insulation is damp, contains air bubbles, and the degree of aging; the relationship between it and the breakdown voltage There is also a monotone corresponding relationship between dielectric loss and breakdown voltage decrease; these all sho...

AI Technical Summary

Problems solved by technology

[0007] In order to make up for the problem that the state assessment of XLPE insulation by dielectric loss measurement at a frequency of 50Hz or 0.1Hz is seriously affected by the test system and the external environment, the test data is highly dispersed, and cannot truly reflect the state of the system. The purpose of the present invention is to provide a The method for evaluating the aging state of XLPE insulation based on the ratio of dielectric loss at different frequencies, the method of the present invention is based on the relative ratio of the measured values ​​of dielectric loss at two characteristic frequencies to effectively evaluate the aging state of XLPE insulation

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