Temperature Field Simulation and Ampacity Calculation of Multi-loop Cable Tunnel with Ventilation

The number of cable loops in the tunnel is the main factor that causes the cable temperature rise and limits the cable ampacity. In order to improve the cable ampacity of multi-loop cable tunnel, the electromagnetic - thermal - flow coupling calculation model of cable tunnel was established based on ANSYS finite element simulation software. The influence of tunnel ventilation speed and ventilation distance on cable temperature distribution was studied, and the ampacity was calculated according to temperature distribution. The results show that the temperature of the cable conductor decreases by less than 1°C for each 2m/s increase of wind speed when the speed is more than 6m/s. The larger the wind speed, the smaller the temperature difference of cable conductor between the air inlet and outlet. The longer the ventilation distance, the larger the temperature difference of cable conductor between the air inlet and outlet. The ampacity of 110kV, 220kV and 500kV cables is respectively 1645A, 2031A and 2238A when the wind speed is 6m/s. The ampacity of 110kV, 220kV and 500kV cables is 1141A, 1517A and 1678A respectively when the ventilation length is 4m.