Validations of simulation of UHF electromagnetic wave propagation in an oil‐filled tank by time‐domain measurements

Abstract

Degradation of the electrical insulation within power transformers by partial discharge (PD) may lead to catastrophic failure of the apparatus, hence PD should be detected at an early stage. Ultra-high frequency (UHF) measurement method, i.e. detecting electromagnetic (EM) waves in the UHF range radiated from PD, has recently received attention for its various advantages, such as the robustness against external noises and its capability of localisation of the PD position. However, the EM waves suffer attenuation while propagating within transformers, in some cases, which results in undesirable low detection sensitivity. To evaluate the propagation and attenuation characteristics of the EM waves quantitatively, the simulation technique of the EM wave propagation is of importance. In this study, at first, the EM waveforms as well as attenuation properties of their amplitudes and cumulative energies while propagating through transformer windings in an oil-filled tank were experimentally investigated. Next, the detailed conditions for simulating the EM wave propagation based on time-domain finite integration technique were described. Then, the simulated results were compared with the experimentally obtained ones. These simulation and measurement results showed good agreement with each other, therefore the authors have successfully validated the newly developed simulation of the EM wave propagation.