Effects of harmonics in distribution systems on temperature rise and life of XLPE power cables

In the recent years due to the increased use of nonlinear loads, harmonic pollution level in distribution systems has been increased beyond the tolerable limits. This has caused many problems for distribution system components, such as additional losses and hence additional heating. Also, now, due to number of technical, environmental and social issues, the use of power cables; especially cross linked polyethylene (XLPE) power cables, is increasing at very rapid rate. Thus, power system harmonics problem and the use of XLPE power cables in distribution systems are growing simultaneously. Harmonics present in the distribution systems causes additional temperature rise and hence loss of useful life of XLPE power cables. The aim of this paper is to evaluate the effects of harmonics in distribution systems on the temperature rise and useful life of XLPE power cables. A mathematical model of XLPE power cable is developed for evaluation of effects of harmonics on temperature rise and Arrhenius equation is used to evaluate the effects of harmonics on useful life of XLPE power cables. MATLAB program is developed to implement mathematical model and to solve Arrhenius equation for real life XLPE power cables having aluminium and copper conductors. The results are presented and conclusions are drawn.