Simulation Study on Steady-State Ampacity of ±400 kV J-tube DC Submarine Cable

1Abstract-As the protection device of submarine cable of new energy offshore wind power transmission system in new power system,J-tube has such problem as hinders the external heat dissipation of cable and restricts the carrying capacity of the whole wind power transmission line. Since the heat dissipation condition of cables in seawater is much better than that in air, the limiting effect of the air section of the J-tube on the carrying capacity is more significant. This paper takes ± 400 kV DC submarine cable under the J-tube laying environment as the research object, and a three-dimensional simulation model of the air section of J-tube is established using COMSOL Multiphysics software to study the influence of ambient temperature and pipe's outer diameter on cable's steady-state carrying capacity. The results show that with the increase of ambient temperature, J-tube submarine cable's carrying capacity will be significantly lower, from 2015A in 10°C down to 1386A in 40°C. And as the outer diameter of J-tube increases, the current carrying capacity of the cable also increases, because air flow in the tube also becomes more intense.