XLPE (Cross Linked Polythylene) insulation aging estimation method based on different frequency and dielectric loss ratios

Abstract

The invention provides an XLPE (Cross Linked Polythylene) insulation aging estimation method based on different frequency and dielectric loss ratios. The method comprises the following steps: preparing inner, middle and outer section samples of a cable insulator; performing sample dielectric loss measurement under voltages of 50Hz and 0.1Hz under the same conditions; acquiring the dielectric loss ratio of each sample under 0.1Hz and 50Hz; on the basis of the dielectric loss ratios, calculating to obtain dielectric loss ratios of all insulation layers and the overall insulator; estimating the aging state of an alternating-current or direct-current cable XLPE insulator according to the sizes and change rules of dielectric loss ratios of all the layers and the size of a dielectric loss ratio of the overall insulator. According to the method, influence of non-uniform aging of different positions can be eliminated, so that the overall state of the simulator can be well reflected, and the aging degree of an alternating-current or direct-current cable XLPE insulator can be accurately estimated; the amount of samples required for test is less, and the requirements on voltage and capacity of a test instrument are low; the dielectric loss ratios under different frequencies are taken as character parameters, so that the influence of the test instrument on system errors and external environment is reduced; comparison with historical data is not needed, and 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 the dielectric loss tangent of a polymer solid medium at different frequencies. Background technique [0002] Dielectric loss tangent (tanδ, hereinafter referred to as "dielectric loss") is an important performance parameter describing 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); the curve of dielectric loss with voltage can determine whether the insulation is damp, contains bubbles, and the degree of aging; it is related to the breakdown voltage There is also a monotonic correspondence between them, the dielectric loss increases, and the breakdown voltage decreases; these all indicate that the ...

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

Images