Design and economic analysis of 275 kV HTS cable for UK transmission network

Achieving Net Zero requires a significant increase in electricity demand for transportation, heating, and industrial sectors. However, the increase in demand poses a challenge for heavily congested urban networks. High-Temperature Superconductor (HTS) 275 kV cables offer a credible technology solution that can uprate existing cable routes up to five times higher capacity density, utilizing existing 275 kV substations and removing the need to uprate circuits to 400 kV. This paper presents a detailed technical design and cost-benefit analysis for the cable installation. The technical analysis covers location selection, power system considerations, and standards alignment. A 12.9 km long 275 kV cable has been designed using cold dielectric and three separate phases. An equivalent circuit model was built using distance and differential protection methods to study the operation during different fault scenarios. A Standard mapping exercise has been performed to understand the gaps between the HTS and conventional cables by covering seven existing standards to identify the further tests to de-risk the technology. The economic analysis by considering the full lifecycle shows HTS is the economic for the chosen location with instances where substation equipment or land expansion costs are dominant.