Life Estimation of HVdc Cable Insulation Under Load Cycles: From Macroscopic to Microscopic Charge Conduction Modeling

Abstract

This article goes one step forward in the life estimation of HVdc cable insulation under load cycles by introducing for the first time a microscopic model of charge conduction and transport, i.e., bipolar charge transport (BCT) model, for electric field calculation inside the insulation thickness. This article first includes the development and the validation of the BCT model with that found in the literature. Then, the parameters of the developed BCT model are optimized using pulsed electroacoustic (PEA) space charge measurements. Followed by the integration of the developed, validated and optimized model into the electric field calculation for life estimation of a 500-kV dc-XLPE insulated cable subjected to type test (TT) load cycles according to Cigrè Technical Brochure 852. The developed microscopic model is compared to the macroscopic models already found in the literature. The microscopic model shows a comparable electric field inversion similar to macroscopic models. However, the behavior of the microscopic model is noticed to be different under heating and cooling load cycles. In the hot cable, the maximum electric field stabilizes at different amplitudes and positions inside the insulation thickness in both models. This investigation has been carried out in the framework of the HEU-NEWGEN research project.