Calculation of space charge density in negative corona based on finite element iteration and sound pulse method

摘要

Space charge distribution is a valuable indicator of ion flow field and is widely utilized to assess electromagnetic environment for transmission line. FEM is widely used to solve this problem. However, Kaptzov assumption in FEM assumes that onset voltage is unchangeable after corona occurs, this is not tally with the actual situation. This paper adopted the finite element iteration method (FEIM), which uses empirical formula instead of assumptions, to calculate the charge density. The surface field intensity is not constant in the empirical formula because the empirical takes the effects of space charge on surface field into consideration. This is more consistent with actual situation. In order to verify the accuracy of the algorithm, sound pulse method is applied to measure the charge density around the conductor in laboratory. Simulation results shows that the charge density obtained in this study agree with the data in the experiment, which verifies the validity of the empirical formula for calculation of space charge density.