Induced Overvoltages on the SF6 Substation Enclosure Caused by Switching

Abstract

This paper investigates overvoltages on the SF6 substation enclosure caused by the switching operation of the interrupter. The paper analyzes the amplitude and the overvoltage duration on the substation enclosure. Switching overvoltages take part in the everyday drive of HV substations and constitute an undesired phenomenon that may often, beside transient disturbances, lead to undesired cases as well. Electrical discharge in the SF6 gas dielectric, caused by very fast overvoltages, spreads from the place of its occurrence towards all directions within the substation, which on discontinuities (e.g. connection bushings, cable bushings) also includes spreading onto the external side of the enclosure and earthed parts of the substation. Such overvoltages are characterized by a very high frequency for which even low inductances represent very high impedances. This paper is focused on simulation options of the transient connection GIS-overhead line in simulation software. Literature sources provide a fine description of the physical background of the observed phenomena. However, it is difficult to find a model presentation in certain software. Due to this fact, this paper shows possible ways of simulating the GIS-air connection with objects in ATP software.