Genetic algorithm based real-time rating for short-time thermal capacity of duct installed power cables

Japanese utilities have promoted research to use existing equipment more effectively. Until now, Neher's equations have been used to calculate the short-time thermal capacity of power cables. However, in order to use existing power cables more effectively, detailed calculations which consider time-varying thermal resistance and capacitance of the surrounding soil are necessary. For duct-installed power cables, duct temperatures can be measured by newly developed optical fiber temperature sensors. In this paper we propose a method to calculate the short-time thermal capacity of duct-installed power cables. The proposed algorithm is based on the estimation of the thermal resistance and capacitance of the surrounding soil using continuously measured duct temperatures. In this algorithm, a genetic algorithm is employed to estimate this resistance and capacitance accurately. The effectiveness of the proposed algorithm is demonstrated using the experimental data. It is shown that applying the proposed method improves the short-time thermal capacity of duct-installed power cables considerably.