A narrowband high frequency distributed power transformer model for partial discharge location

This paper utilises a narrow band high frequency distributed transformer model to estimate partial discharge location. Here a narrow band of frequencies within the frequency response of the system, that exhibit resonant pole behaviour, is specifically targeted. It is proposed that the observed response is due to the interaction of residual winding inductance with capacitance to ground. This physical phenomenon is inherently distributed; hence regions within the frequency response related to this interaction will be dependent upon the input location. With this premise an algorithm that estimates the location of the partial discharge by iteratively comparing the proposed model at various locations within the winding with the observed partial discharge frequency response is implemented. The algorithm was tested on a single phase of a 66 kV/25 MVA interleaved transformer winding where the partial discharge was injected via an oil immersed point-plane 7.5 kV source.