Numerical simulation of temperature distribution of three-wire cables with combination coordinates

The high-voltage electric power is generally transmitted by underground cables in urban. Considering about the high cost for underground cable, it is necessary for us to get accurately biggest ampacity of electric cables in order to insure the operation of cables in safe. It is relationship of heat transfer with cables and soil. The coefficient of thermal conductivity of soil has great influence on the ampacity of cables. As it is difficult to exactly confirm the coefficient of thermal conductivity of soil for variety, humidity and temperature of soil, a distributed temperature sensing can be used to measure the temperature of cablepsilas coat exactly and avoid the influence of soil. With the method of finite difference, a combination of two polar coordinates is used in computing temperature field of the cable with three-wire for maintaining the single nature in a grid. Through the validation of experiment, the computational error is verified in the range of the needing in engineering.