Comparison of pd detection methods for power transformers - their sensitivity and characteristics in time and frequency domain

Partial discharge (PD) detection is an important method for detecting defects in power transformers, and several PD detection methods reported in literature have their respective advantage and disadvantages. In this paper, a simplified PD coupler attached to the tap of the bushing, whose reliability is verified by the EMTP simulation, is proposed in order to extend the application of on-site tap PD detection. Experiments were carried out on 110 kV transformer models to compare the sensitivity of the sensor with some other popular PD detection methods. The characteristics of the detected signals suggest that the proposed coupler has satisfactory sensitivity as well as potential to solve some on-site noise-rejection problems by introduction of ultra-high frequency amplifiers, and thus could be suitable in future for online PD monitoring applications in substations.