Equivalent circuit model of polluted insulators with the including effect of supply voltage harmonics

Typically, under laboratory condition, during the measurements of polluted insulator’s leakage current, supply voltage is assumed to be purely sinusoidal. However, in real-life due to the ever-increasing trend of using power electronic devices in power network, significant amount of harmonic distortion in supply voltage is present. The high voltage insulators in the power system are directly subjected to this distortion. Presently, most of the available polluted insulator models are based on pure sinusoidal excitation with fixed voltage amplitude. Therefore, the harmonic contents of the supply voltage will make validation of present equivalent circuit models difficult. In this paper, we propose a theoretical polluted insulator equivalent circuit model in presence of supply voltage harmonic distortions. Along with this, we also provide a mathematical analysis of the polluted insulator’s nonlinear characteristics in conjunction with the impact of supply voltage harmonics. This is used to derive a precise equivalent circuit model. This study will be used as a basis for developing a sound theoretical understanding of the effects of supply voltage harmonic content on the measured leakage current characteristics of a polluted insulator