Thermal soil properties as a basis for design of underground high voltage cables

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Publication Title
Thermal soil properties as a basis for design of underground high voltage cables

Abstract
The dimensioning of underground extra-high voltage direct current (HVDC) power lines, requires detailed knowledge of the ground and its thermal conductivity. For this purpose, a laboratory test using transient methods with the needle probe, to determine reproducible values of the thermal conductivity of soils was developed for the construction of the 700 km long SuedLink underground power line in Germany. The unique approach of this test not only yielded precise thermal conductivity measurements but also allowed for the depiction of the thermal conductivity to water content relationship, covering the entire range from saturated to oven-dried soil states. This allows site specific groundwater conditions to be considered during the design. Additionally, the gravel content of the soil was also taken into account.The results of the thermal conductivity tests of the soil samples form the basis of the thermal ground model which governs the thermal design of HVDC underground cables. The thermal design is crucial for optimising the spacing between cables in order to minimise the project costs and the environmental impact. In this paper the process from laboratory testing to the creation and analysis of the thermal ground model is presented. Furthermore, insights into the thermal design of HVDC cables are provided focussing on horizontal directional drilling (HDD) methods.
Authors
K. Hendler; C. Meier; S. Kleiber; J. Stegner; C. Drefke; Conrad Boley

Published In

18th European Conference on Soil Mechanics and Geotechnical Engineering (ECSMGE2024)

Theme

E - Environment, water and energy

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