Practical implementation of a narrowband high frequency distributed model for locating partial discharge in a power transformer

This paper proposes the use of a narrowband high frequency based distributed transformer model for estimating partial discharge location within the winding of an interleaved power transformer. At high frequencies, the residual inductance within a transformer winding becomes significant This inductive interaction generates its own characteristic response which, due to its distributed nature, can be utilized for partial discharge location. The technique proposed here takes advantage of the high frequency nature of a partial discharge and requires measurement at one location only. It also does not require detailed knowledge of the transformer´s physical and material specifications. To confirm this approach, practical tests were conducted on a 66 kV/25 MVA interleaved transformer winding. The partial discharge injection was delivered by an oil immersed point-plane 7.5 kV source with the data captured using a current probe on the earth terminated neutral.