engleski

An Approach to Thermal Modeling of Power Cables Installed in Ducts

The power cables laying in the urban areas require utilization of the protective ducts, mainly to facilitate the faulty section replacement. However, the use of cable ducts results in reduced capacity to dissipate generated heat to the surroundings. Thus, the thermal analysis of cables placed in ducts is very important for proper power cable operation. The thermal response of cables laid in mutual and in separate ducts, respectively, is considered at two values of current load. The full-scale field measurement setup is utilized to carry out the analysis of both steady- state and dynamic power cable heating under actual field conditions for the two backfill configurations. The measurement results provide the insight into the power cable heating dynamics related to the situations of a short-term over- loads and fault drive- through responses and also the opportunity to verify the proposed numerical approach based on the use of finite element method and the boundary conditions on the interior duct surface. The approach could be considered as a compromise between the standardized procedure and the tedious procedure involving the computational fluid dynamics simulations due to straightforward implementation and very good accuracy. The results obtained suggest that cables laid in mutual duct lead to a less favourable thermal situation when compared to cables laid in separate ducts. Also, the numerical results suggest that the use of non- uniform heat flux around the inner duct surface results in a significantly better agreement with measurements, compared to the purely numerical approach utilising the concept of the effective thermal conductivity to model heat transfer in the air gap between cable and duct.

Cable thermal analysis ; Cables installed in ducts ; Numerical modeling ; Finite Element Method (FEM) ; Thermal variables measurement ; Power system measurements

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