Calculation of Electric Field on Substation Equipment considering AC Ion Flow Field

Abstract

With the increase of voltage levels in substation corona discharge on the surface of high voltage conductors and equipment in substations becoming more and more severe, the influence on the electromagnetic environment around substations is becoming more and more obvious. In order to study the influence of corona discharge on the ground electric field under substation equipment in AC substations, this paper proposes an improved method based on Abdel-Salam’s calculation of the ion flow field on AC power lines. By redefining the criterion of corona onset and the amount of emission charge and combining with the migration, motion, and recombination of the space charge, a new model which can be applied to the calculation of AC ion flow field electric field of multiphase bundle conductors in substations is established. The calculation results of the ground power frequency electric field of the conductor at the typical tower in the light, medium, and heavy ice regions of 750 kV typical AC transmission project show that the ground electric field gradually decreases with the increase of conductor height. At the same conductor height, the ground electric field strength in the heavy ice region is the largest, while under the conductor in a light ice region, it is the smallest, and the minimum allowable conductor-to-ground distance can be concluded that the national standard limit value is not exceeded when the conductor-to-ground distance in light ice region is 24.5 m, the conductor-to-ground distance in medium ice region is 25.5 m, and the conductor-to-ground distance in heavy ice region is 26 m.