Simulation of numerical calculation method for carrying capacity of urban underground cable group

摘要

The calculation of the ampacity of underground cable group can effectively determine the real carrying capacity of power cables under specific environmental conditions. Numerical calculation of cable carrying capacity is very complicated because the calculating object is a thermal-electric coupled field. In this paper, the heat conduction, heat convection and heat radiation of power cables, which are laid in ducts in urban power grid were analyzed. And the two-dimensional finite element model of temperature field and flow field was established, which was an actual working condition contained 220kV power cables and 35kV power cables. The electrical and thermal parameters of thin layers of cables was converted based on multi-layer cylinder structure. And the ampacity of 220kV power cables as well as the temperature field and flow field of power cables was calculated. Different thermal conductivity coefficient of soil, environmental temperatures, adjacent cables loads were used to analyze their impact on cable ampacity.