Extension to Three-Capacitance Equivalent Circuit for Simulation of Internal Partial Discharges in Multiple Gaseous Cavities

This paper examines simulation of partial discharges that occur inside defective solid insulation containing multiple gaseous cavities. The formation of voids and cavities in high-voltage insulation is the main cause of internal partial discharges. Although the magnitude of partial discharge is quite small, but over time it leads to an accelerated degradation of the insulation, which ultimately ends in electrical breakdown. Since partial discharges occur in voids and cavities inside electrical insulation, they are inaccessible to direct measurement and observation. Therefore, due to the threat they pose to insulation, comprehensive modeling of partial discharge is an important task Until recently, when simulating partial discharges using the well-known three-capacitance equivalent circuit, in most cases, the defect in the insulation itself was represented only by a single gaseous cavity. The extended equivalent circuit proposed in this paper allows simulation of partial discharges in multiple voids or cavities, that is more consistent with real insulation defects, and also takes into account the mutual influence of neighboring gaseous cavities. Method of mixed analog and digital circuit simulation was applied for modeling of localized dielectric breakdown of a defective portion of a solid electrical insulation. Obtained results contribute to methods of modeling the complex breakdown processes in electrical insulation and can be used in virtual experiments and for educational purposes.