Analysis And Caculation The Possibility Of Improving The Current Ampacity Of The 110kV Single-core High Voltage Cables

There are many challenges to be resolved urgently, such as enhancing the current carrying capacity of the tunnel buried cable, reducing the core temperature of the cable when it woks, prolonging the cable's life-span and improving the reliability of the line in run. This thesis described the investigation on the current ampacity of the 110kV high voltage single-core XLPE cables.Firstly the inside heat transfer of the buried cable was calculated with the IEC60287 standard according to the inside configuration and the heat-circuit model of the cable. Then a 2-dimension instable model for the tunnel buried cables was set up. A new, simple and feasible method was established with the finite difference method. The soil temperature field was analyzed and calculated according to this new method, while the boundary of the soil and the cable was approximated as the vertical lines instead of the bending lines. Finally, the current ampacity of the cable was calculated by combining the programmes of the soil temperature field and the cable temperature field.An experiment was designed to measure the temperature of the power cable. According to the experimental results, we knew the heat situation of the cable with different currents. On the basis of the experimental datum, the feasibility of enhancing the current ampacity of the power cables was analyzed. A cooling pipeline was introduced at the outside of the cable. It is found out that water is the suitable cooling material to improve the current ampacity of the 110kV high voltage single-core XLPE cables by 10 percent.