Impact of Voltage Harmonics on Condition Assessment of Polluted Insulator through a Simulation Model

The condition assessment of outdoor high voltage insulators is of prime importance to power utilities. There are numerous indicators used for inferring the surface condition of an insulator based on an analysis of measured leakage current. To date, the assumption by most researchers has been that the supply voltage subject on insulators is sinusoidal with little or no harmonic induced distortion. However, in real-life due to ever increasing trend of using power electronics devices in power network, significant amount of harmonic distortion is common and insulators in the power system are directly subjected to this distortion. Therefore, the effectiveness of all those present indices under purely sinusoidal voltage will become questionable in presence of distorted supply voltage. This work aims to investigate the effect of voltage harmonic contents on the measured leakage current of polluted insulators via a developed simulation model. In this paper, by considering the practical supply voltage distortion, authors have shown the major drawback of present indices based condition assessment techniques. Authors have also tried to provide an optimal solution by proposing a Crest Factor (CF) based distinctive index to overcome the problem, based on simulation results.