Numerical Analysis on PD Induced EM Signal Propagation Characteristics Inside GIS

Recently, UHF method has emerged as one of the most practical techniques for continuous monitoring and remote detection of partial discharge in HV power equipment. In GIS, optimal employment of UHF method is subject to thorough understanding of propagation characteristics of PD induced EM waves inside the metal encapsulated structure of GIS. In the same context, this paper presents a numerical analysis on the PD induced EM wave propagation characteristics inside a 252 kV GIS busbar. The generation of higher order EM modes has been analyzed and their role in PD detection at different orientations relative to PD source has been demonstrated. Several test cases consisting of varying PD defect sizes, pulse characteristics, defect location & orientation have been devised and simulated to study their effect on the EM wave propagation characteristics inside the GIS. Moreover, the propagation delay of the induced EM signal has also been discussed and quantized which would benefit in precise time based localization. The main aim of the analysis is to achieve a firm grip on the understanding of EM wave propagation characteristics inside GIS and to evaluate an optimal position & orientation for an internal UHF sensor inside GIS which could be used for online condition monitoring of GIS systems.