Behavior of XLPE for HVDC Cables under Thermo-Electrical Stress: Experimental Study and Ageing Kinetics Proposal

Hanen Yahyaoui,Aurelien Hascoat,Serge Agnel,Christophe Moreau,Carl Johan Andersson,Virginie Eriksson,Dominique Le Roux,Pierre Hondaa,Jerome Castellon,Wilfried Frelin

doi:10.3390/en14217344

Abstract

The present work deals with the study of the electrical behavior of cross-linked polyethylene (XLPE) used for HVDC cable insulation. The aim is to better understand the influences of electrical and thermal stresses on the insulating material in order to provide useful information for designing HVDC cables. This study was carried out on Rogowski samples made of XLPE insulation with semiconductive electrodes, aged for more than 3 years (1220 days) at three different temperatures (70, 80 and 90 °C) under two DC electric fields (30 and 60 kV/mm). Dielectric loss factor, volume resistivity and space charge accumulation were measured. Results are analyzed and cross-correlated, in order to propose possible ageing kinetics.

Highlights

Cross-linked polyethylene (XLPE) is widely used as an electrical insulation material in AC extruded power cables and has a track record of more than 40 years
We present and discuss the main results obtained by electrical volume resistivity, dielectric spectroscopy and space charge measurements
For ageing under 60 kV/mm, electrical volume resistivity was in the order of 1014 Ω × m and 1015 Ω × m when measured under 2 kV/mm, and between 1013 Ω × m and 1015 Ω × m when measured under 30 kV/mm

Summary

Introduction

Cross-linked polyethylene (XLPE) is widely used as an electrical insulation material in AC extruded power cables and has a track record of more than 40 years. In the context of a growing interest and demand in high voltage direct current (HVDC) transmission, and because of its high dielectric strength and electrical resistivity, combined with its good mechanical and thermal properties [1], XLPE is used in extruded HVDC cables. Different empirical formulas have been proposed to describe the variation of DC resistivity of solid insulations with temperature and electric field. An example of such a formula is as follows [3]: ρv = ρ0 exp(−αT − βE)

Objectives

Methods

Results

Conclusion