Analysis of Free Energy Increment for Insulation Aging in Crosslinked Polyethylene DC Cable

Abstract

Electrical aging limits the reliability of crosslinked polyethylene DC cable. The study on the reaction kinetics of electrical aging is an important basis of improving the reliability of DC cable. Free energy increment (FEI) under electric field reflects the reaction rate of electrical aging, which is very useful to analyze the aging characteristics of materials. However, there is no direct way to get the FEI, which causes that the FEI stays at the stage of theoretical analysis and cannot be obtained by experiment. In this paper, an easy method including experiment and calculation to get the FEI is proposed, and a simulation method to obtain the FEI is also introduced. The experiment and simulation both show that the FEI of crosslinked polyethylene (XLPE) is proportional to the degree of polymerization, is approximately linear with the electric field, and grows with the temperature. According to the FEI obtained, we find that the molecular branches of the XLPE whose plane of carbons is perpendicular to electric field are more likely to age. Improving molecular chain orientation and reducing the length of branches are two of the methods to improve the aging characteristics of the XLPE.

High-Voltage Cable Condition Assessment Method Based on Multi-Source Data Analysis

“…On this basis, a comprehensive evaluation model of cable operating status with improved radar chart theory was established [14]. An analysis method combining fuzzy theory and analytic hierarchy process has been introduced to evaluate the cable status based on the particularity and difference of different influencing factors [15], and on the basis of the evaluation results, a maintenance strategy considering economy and reliability is formulated [16]. The insulation resistance, dielectric loss angle and partial discharge of the disabled cables and their accessories were comprehensively measured.…”