High frequency model of power transformer bushing for very fast transient studies

Fast and very fast transient overvoltages generally appear during switching operations within electrical substations. The oscillatory nature of such phenomena with frequencies that can reach several tens megahertz tends to degrade the lifetime high voltage equipment as bushings transformers, inducing partial discharges activity or breakdown insulation system. According case studies, are one most sensitive parts overvoltages, indeed, a failure in bushing will cases lead transformer, often catastrophically. Generating frequency character considerable amplitude be difficult, moreover, studying effect on insulated is not easy, even experimentally. Therefore, simulation transients system useful understand consequences phenomena. In this context, document aims propose model capacitive graded oil impregnated paper (OIP) based distributed circuit. equivalent circuit constructed geometric design properties materials. was developed implemented using Matlab/Simulink® software, validated experimental measurements impedance sweep analysis. modeling results good agreement ones.