Analysis of cavity coupling characteristics in VFTO space field

Abstract

The VFTO generated by the switch operation in the GIS substation will radiate the electromagnetic waves with great amplitude and high frequency components. The high frequency part of the electromagnetic wave will be coupled into the interior of the equipment through the gap on the secondary equipment shell, which will affect the normal operation of the equipment. In this paper, the electromagnetic simulation software, which is based on the finite element method (FDTD), would be applied to the cavity coupling analysis under these circumstances. The results show that the polarization direction of the electric field is parallel to the short side of the rectangular opening, the larger the aspect ratio of the rectangular opening, the easier the space field generated by the VFTO to be inside the device; transforming the single slit into to the same area of the rectangular slot array can effectively suppress the field amplitude, and this performance is more obvious in the resonant area. The media plate can improve the shielding effectiveness of the cavity. The closer the dielectric plate is to the opening, which causes less energy of the coupling into the cavity, as well as larger size will get better shielding effect of the cavity.