FFT Analysis on Partial Discharge Modeling of Transformer Solid Insulation

The present paper focuses on formation and alteration of Partial Discharge (PD) with different applied high voltages. It is conducted by simulations based on an extended PD equivalent circuit in order to understand the characteristics of partial discharge in solid insulating materials.  Mechanism of PD in solid dielectric material has been modeled using MATLAB Simulink.  Partial discharge in solid insulation with a single cavity as defect is the main focus of the work.  50 Hz AC voltage sources of 1kV, 5 kV, 10 kV, 15 kV, 20 kV and 30 kV are applied to the modeled circuit to capture discharging current and discharging voltage which normally occurs in nanoseconds. For the accurate analysis of partial discharge, various digital signal processing techniques including Fourier Transform (FT), Short Time Fourier Transform (STFT), Fast Fourier Transforms (FFT) are employed on the captured signals. The proposed technique analyzes the simulation results in frequency domain and estimates the severity of insulation damage. The results thus obtained an act in defense of transformer against partial discharges and are helpful in extending its life.