Dynamic Thermal Analysis of High-Voltage Power Cable Insulation for Cable Dynamic Thermal Rating

Since cable insulation with low thermal conductivity occupies a large proportion of high-voltage cable, an optimization analysis on dynamic thermal behavior of cable insulation can be very useful to improve the accuracy of cable dynamic thermal rating. In this paper, the dynamic thermal analysis of cable insulation is carried out by combining the theoretical method and finite-element analysis (FEA) method. Based on the analysis, it is proved that using IEC recommended transient thermal model of cable insulation will bring certain error to cable dynamic temperature evaluation, especially at the early stage of cable temperature rise. Moreover, in this paper, an implementable optimization method for transient thermal model of cable insulation is developed. The improvement of the optimized model compared with the IEC model on cable dynamic thermal rating is verified by the FEA method. The results confirm that the optimized model can better model the dynamic thermal behavior of cable than the IEC model and the improvement is more obvious for dynamic thermal rating of cable with high voltage level and under large load. The methodology developed in this paper can pave a way for electricity utilities to increase cable utilization while still ensuring cable reliability.