Dielectric frequency response of transformer insulation system under high-dV/dt stresses

Due to the growing use of power electronic components in today's power network, exposure of transformers to distorted voltages with high-dV/dt contents is increasing. Hence, investigating the performance of power transformer under such stresses is important. This research studies the degradation of transformer insulation system under high-dV/dt stresses using the frequency domain spectroscopy method. Two identical transformers were aged under two different kinds of voltages: pure sinusoidal waveform and high-dV/dt distorted waveform. Upon completion of a certain ageing period (500 hours), insulation conditions for both transformers are assessed using frequency domain spectroscopy (FDS) diagnostics. The results show the potential for FDS method in transformer insulation analysis under distorted voltage waveforms.