XLPE cable insulation aging degree determination method based on DSC analysis

Abstract

The invention discloses a DSC analysis-based XLPE cable insulation aging degree judgment method, which comprises the following steps of: firstly, testing oxidation induction time of new cable insulation at different temperatures by adopting DSC in an air atmosphere, and calculating the activation energy of the cable insulation and the service life at an extrapolation working temperature; secondly, in a nitrogen atmosphere, respectively testing DSC temperature rise curves of insulation of a new cable and an on-site aged cable, and calculating the thermal historical temperature and time of the cable insulation by using a Kobayashi model; then, according to a time-temperature equivalence principle, converting the thermal historical time of the aged cable into time under a thermal historical temperature value of a new cable, and subtracting the thermal historical time of the new cable to eliminate thermal history generated during cable manufacturing; and further converting the corrected thermal historical time of the aged cable into the aging time at the working temperature value, and taking the ratio of the aging time at the working temperature to the service life as an aging state characterization parameter.

Description

technical field [0001] The invention provides a method for judging the aging degree of XLPE cable insulation based on DSC analysis, which belongs to the technical field of insulation aging evaluation of electric equipment. Background technique [0002] Cross-linked polyethylene (XLPE) is currently the most widely used power cable insulation in domestic and foreign power transmission and distribution networks. Insulation aging of XLPE cables will inevitably occur during long-term operation, which is the main cause of cable line failures, and even leads to sudden large-scale power outages, bringing immeasurable losses. Therefore, it is of great significance for the safe operation of the power grid to grasp the on-site aging degree of the cables in operation in time. [0003] The design life of XLPE power cables is usually 30 years, and many cables laid in the early years are close to retirement time. Due to the differences in actual working conditions such as the laying envi...

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Problems solved by technology

[0004] At present, there are many laboratory diagnostic parameters for cable insulation, which are mainly divided into electrical and non-electrical parameters. Among them, non-electrical parameters such as oxidation induction time (OIT) are usually measured in an oxygen atmosphere. The thermal-oxidative aging mechanism of cable insulation does not match the actual situation.

In addition, for various diagnostic parameters, reliable insulation aging criteria have not been established; before the cable insulation aging state can be diagnosed according to the real-time data of the characteristic parameters, the on-site aging law of the cable insulation based on the characteristic parameters must be established. Long-term tracking and sampling of cables in operation is very time-consuming

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