Electric Field Distribution and Optimization of Different Shielding Device for Composite Insulators in ±1100kV Indoor DC Yard

Abstract

In order to study the E-field distribution and design a practical shielding device for the ±1100 kV post insulator, follow computer simulation was made. First, the whole indoor DC yard model was established and the E-field intensity of post insulator under different shielding fittings was obtained through FEM and sub-model technique. The maximum E-field strength of the flat-bottom fitting was lowest, only 584V/mm, 15.0% lower than spherical type, 22.6% lower than mushroom-head type and 32.1% lower than double-ring type. Next, the concave-bottom device was proposed to further reduce E-field intensity and satisfy practical installation. The E-field distribution of both the flat-bottom fitting and the concave-bottom fitting were calculated under 2600kV impulse voltage, different chamfer radius and different opening diameter. When the concave-bottom device opening diameter was 360mm and chamfer radius was 100mm, the maximum E-field intensity was 952V/mm on opening chamfer, 1095V/mm on insulator sheath surface and 1988V/mm on shield surface. Compare to the flat-bottom fitting, the concave-bottom device could significantly reduce the maximum E-field intensity on the opening hole and insulator sheath surface, though the maximum E-field intensity on the shield surface was little higher. Furthermore, the change trend of geometric parameters on the E-field distribution was summarized. For the flat-bottom fitting, the maximum E-field intensity increased with the opening diameter increasing. However, for the concave-bottom fitting, there was inverse proportional relationship between the maximum E-field intensity and the opening diameter. Based on the results, the concave-bottom fitting was firstly recommended for the installation of ±1100 kV DC post insulator. It could provide reference for the ±1100 kV UHVDC construction.