Simulating propagation of UHF signals for PD monitoring in transformers using the finite difference time domain technique [power transformers]

Partial discharge (PD) can be monitored by detecting the signals radiating from PD sources. Ultra high frequency (UHF) sensors have been used to capture the signals. However, external sensors are required to enhance the feasibility for applying the technique to operational transformers. In this paper, the electromagnetic waves escaping from a transformer tank sealing gasket are investigated. The finite difference time domain technique (FDTD), which is widely applicable to electromagnetic computation, is used to model wave transients. The model consists of a tank, oil insulation, a gasket and a hatch plate, which are similar to a real transformer. The wave transients at different locations are simulated. The most favourable places for positioning the sensor are discussed in accordance with the simulated results.