Review of the Accuracy of Single Core Equivalent Thermal Model for Offshore Wind Farm Cables

Cables intended to interconnect offshore wind farms with the mainland are currently treated as separate lead-type cables by IEC 60287. A single core equivalent thermal model (SCETM) is implied, that is, a thermal model accounting for 1-D (radial) heat transfer only. While this approach is expected to be reasonable when smaller cables are rated, the 1-D representation is less valid in larger cable sizes. This paper uses 2-D finite-element models to reveal certain weak points of the representation of the thermal resistances in the existing SCETM. For constant losses, the IEC SCETM seems to underestimate the temperature by up to 8 °C. Suitable replacement formulae are proposed that could improve the accuracy of the SCETM. Finally, the issue of nonsolid fillers is considered and modelling guidelines are given.