Calculation and Analysis of 220kV Cross-River Cable Carrying Capacity Considering Complex Environments, Part II — Thermal Analysis of Cable in the Utility Tunnel with Ventilation

The second part of these papers is based on the first part, and further discusses the capacity calculation model of the cross-river cable in the underground traffic tunnel. Firstly, the structural model of the river-crossing traffic tunnel is introduced, and the possible installation location and layout of the river-crossing cable are analyzed. Combined with the cable ampacity results (1864A) in the first part of these papers, the actual temperature of the installation position of the cable in the river tunnel has been measured, and the environmental temperature of 35°C is determined as the boundary condition. This paper further analyzes the cable ampacity under three installation modes. Results show that the three-phase close trefoil arrangement cannot meet the requirement of power transmission. The three-phase separated trefoil arrangement and the horizontal linear arrangement are further studied. With fireproof encapsulation, the capacity of separated trefoil arrangement is lower than the required value by 122A while the capacity of horizontal arrangement is 2060A. To save space, the capacity of separated trefoil arrangement with fireproof structure and ventilation system is calculated to increase the capacity. In the end, the detailed ventilation cooling system design is also provided for reference.