Abstract
Underground cable performance indices such as maximum cable temperature and ampacity are non-continuous functions of the configuration parameters such as depth and width of various trench layers. In this respect, existing traditional gradient-type methods cannot be used to optimise such performance indices. This study presents an efficient methodology for optimising power cable thermal performance with respect to configuration parameters involving cable spacing, depth of burial and size of backfill. The new methodology integrates the powerful features of the finite elements (FEs) technique coupled with the flexibility and effectiveness of the particle swarm optimisation (PSO) algorithm in order to handle various geometrical parameters in the complex surrounding operating environment. The introduced methodology is tested using a commercial FE simulation package used in conjunction with developed PSO code. The integrated methodology can be employed to minimise the maximum cable temperature, minimise installation cost or maximise cable ampacity. Practical applications are presented for 15 kV cables, which demonstrate the usefulness and versatility of the presented methodology. Notable improvements have been achieved by optimising the cable trench configuration parameters. For example, the cable ampacity was maximised, optimising the cable spacing, barrier depth and backfill thermal conductivity, which resulted in an appreciable increase of 4.5%.