Sensitivity analysis of cable trench modelling with concrete duct bank and multiple material layers for the current rating of 150kv cables

Due to the high building density in the city of Zurich, 150 kV cable connections are laid in concrete duct banks in order to protect them from damage and to enable renewal without construction work. The laying conditions have to be taken into account for thermal modelling, when the current rating of the cables is determined. In order to define standardized laying conditions, the laying of the cables has to be thoroughly analysed. Standardized laying conditions have been determined as the basis for dimensioning high voltage cables for the ewz target grid for 2050 as well as for determining the maximum permissible current of high voltage cables for the monitoring system. In order to determine a standard parameter set for a typical cable trench at ewz which accounts for the vast majority of cases, a sensitivity analysis was conducted for various allocations of the concrete duct bank and 150 kV cable types. In addition, to enabling swift comparison a simplified model with a unique thermal resistivity of the soil layers surrounding the concrete duct bank was defined taking into account different cable types and installation types (cable arrangement and duct bank types). In the sensitivity analysis parameters were varied to investigate the influence of these factors on the cable current rating