Threat of harmonics to underground cables

The level of harmonic distortions in power systems, especially; in distribution systems is ever increasing due to the increasing use of nonlinear loads and because of many technical, commercial and environmental reasons underground power distribution systems are also simultaneously increasing all over the world. Therefore, necessity is felt to evaluate the effects of harmonics on underground power cables. This paper presents the detrimental effects of harmonics on most commonly used cross linked polyethylene (XLPE) power cables. System is developed in MATLAB to evaluate the effects of harmonics on XLPE power cable parameters, power loss, temperature rise and life of XLPE power cables. Real life power cables data and actually measured harmonics data is used. The results are presented graphically. From these results it is concluded that, resistance (R) increases, whereas; inductance (L) decreases considerably and capacitance (C) decreases slightly; and, power loss and hence temperature rise increases and life decreases with increase in harmonics level.