Quantifying possible transmission network benefits from higher cable conductor temperatures

Abstract

The maximum current rating of high-voltage power cables is limited by the allowable conductor temperature, in order to prevent damage to the adjacent dielectric material. Cross-linked polyethylene dielectrics are generally subject to a thermal limit of 90°C in the UK. The use of novel new dielectric materials may allow the temperature limit to be raised considerably. This study examines the possible thermal rating benefits available from 400 kV cable systems capable of conductor temperatures of up to 150°C in a number of common deployment scenarios, including direct burial and installation in ventilated tunnels. The results of the analysis show a divide between modest improvements in continuous rating and much more utilisable gains in short-term emergency ratings, which could offer the possibilities of single-cable circuits being able to match the current carrying capacity of overhead lines over 24-h period.