Numerical Investigation of Negative Corona Discharge From Protrusion on Parallel Plane Electrodes in Air Insulation

Compared to a spherical metal particle motion within gas insulation, a wire-type particle could have a standing position on the ground electrode. In this work, a numerical investigation and validation from the experimental data of corona discharge from a small protrusion in air insulation within a uniform field under a dc voltage are performed. Three drift-diffusion models and Poisson equations are employed and solved using a finite element method to investigate negative corona discharge phenomena. The results show that the current characteristic with different applied voltages is within good agreement with the experimental results. A typical pulse train and the total number of charged species are also presented. Furthermore, the spatial distribution of charged species, the electric field distribution, and the ionization rate are explained. The effect of physical geometries of the particle on negative corona discharge characteristics is also investigated. It is found that the variation of the particle length, diameter, and tip radius is influencing the pulse characteristics.