Simulation-Based Design of HF Resonators for Damping Very Fast Transients in GIS

The aim of this paper is to present the first full-scale experimental validation of the very fast transient (VFT) wave damping capability of high-frequency resonators in gas-insulated switchgear (GIS). In this regard, the numerical eigenvalue analysis method implemented in COMSOL is used to design and tune the HF resonators. The accuracy of the numerically computed resonance frequencies using this method is validated against the alternative finite-difference time domain method implemented in CST Microwave Studio and against the experimental data from low-voltage measurements. The designed resonator was then implemented in the test setup of a realistic 550-kV GIS where it was subject to VFT waves resembling the disconnector switching operations. The damping mechanism is achieved by using a lossy cylinder in the resonator gap. It is shown that the presence of the lossy resonator results in damping of the VFT wave total energy by 27% even though its first peak is slightly enhanced. The damping efficiency in terms of the voltage amplitude at the resonance frequency is about 60%.