PD Signal Attenuation in 550-kV GIS: Impact of Different Barriers on the Propagation of Electromagnetic Waves
Ahmad Darwish, Graeme Coapes, Shady S. Refaat, Haitham Abu‐Rub, Hamid A. Toliyat
Abstract
Accurate modeling of partial discharge within gasinsulated switchgear has become of paramount significance to improve the utilization of ultra-high frequency sensors within such capital assets. Providing better insight on how electromagnetic waves propagate within gas-insulated switchgear (GIS) systems provides valuable information that can be used to determine the optimal allocation of ultra-high frequency (UHF) sensors. Thus far, most existing models are not considering the full complexity of the GIS systems due to the many associated challenges and the high computational demand of such system modeling. In this work, a GIS system is modeled using the Maxwell solver of COMSOL multi-physics. CIGRE sensitivity verification recommendations are used to inject UHF signals using an internal sensor. Then, two external sensors, placed on the outer belt of dielectric spacers, are used to capture the radiated electromagnetic (EM) waves. The electric field distribution at selected frequencies is presented and discussed under two operating conditions for disconnecting switches. The modeled GIS contains many barriers, including two bends, multiple sudden changes in the outer to inner diameters ratios, six dielectric spacers, and two disconnecting switches. Time-domain simulation results are also presented to provide an insight into the attenuation properties of EM waves due to the different barriers. Finally, a comparison between simulated and measured results has been carried out to verify the modeling accuracy. The results show that GIS systems form complex structures for the electromagnetic waves, and fully understanding the wave propagation can be tedious.