Suppression of very fast transients in gas‐insulated substation via terminal and capacitance components—feasibility study

Reportedly, the switching operation in a gas‐insulated substation (GIS) can lead to deformation of transformer winding. Also, electromagnetic fields radiated because of switching operations get coupled to the control equipment or data cables present in the GIS. These problems during switching operations in the GIS depend on the wave shape of the very fast transient overvoltages (VFTOs) and the associated very fast transient currents (VFTCs). Available methods are utilizing ferromagnetic rings and resistors to suppress the stresses created by very fast transient (VFT) from the source side. These equipment are mounted on the conductors linked to the disconnector. However, current methods are only applicable before installation period and during the substation design stage. The aim of this paper is to investigate feasible methods for mitigation of the overvoltage magnitude of VFT and suppression of the resonant frequencies amplitude at the power transformer. The proposed method utilizes terminal and capacitance components to suppress VFTs in GIS. Its advantages are their simplicity and low cost of implementation along with producing minimal changes in the installed GIS. The effectiveness of the proposed method to mitigate overvoltage magnitude and resonant frequencies amplitude of VFT is presented via simulation. In addition, the amplitude and frequency spectrum of the VFTO and VFTC at the various locations have been analyzed in this paper. Copyright © 2011 John Wiley & Sons, Ltd