COMPARATIVE ANALYSIS OF DIELECTRIC STRENGTH AND ELECTRON VELOCITY IN TRANSFORMER OIL BASED NANOFLUIDS

The growth of nanotechnology has elevated the new challenges and research opportunities in the field of high voltage insulation to prepare the colloidal fluid as an alternative of conventional mineral oil being used as an insulation and coolant in power transformers since long decade. A numerous experiment has been performed to investigate the influence of various types of nanoparticles with different volume concentrations, sizes and shapes on conduction and breakdown phenomena in transformer oil based nanofluids when subjected to short duration of impulse voltages. Because of the complexity in developing the mathematical models for nano-dielectric fluids, less effort has been devoted to simulation approach. In this paper, a 2D-axisymmetry drift diffusion model has been developed by coupling the Poisson's equation with drift dominated charge continuity equations to investigate the influence of nanoparticles on streamer development and electron velocity in transformer oil based nanofluids under the impact of an impulse voltage with different polarities. Three different types of nanoparticles, i.e., Fe3O4, TiO2 and Al2O3 with equal concentration have been considered in modelling the nanofluids mathematically. The simulation study shows that the promising augmentation has been observed in breakdown voltage when the transformer oil is modified by nanoparticles. The trapping behaviour or the polarization of the dispersed nanoparticles can effectively hinder the acceleration rate of electrons and prevents the further ionization of liquid dielectric. The alteration in breakdown physics in nanofluids when subjected to impulse voltage of different polarities is also discussed in brief.