Analysing the Impact of Frequency Bands on Partial Discharge Measurement Outcomes in Generators Through Model‐Based Approach

The electromagnetic wave produced by a partial discharge (PD) covers a broad range of frequencies, from a few kHz to several 100 MHz. Because of the nonlinear response of the stator winding, each frequency component of the PD pulse experiences different levels of attenuation as it travels through the winding structure. Consequently, the choice of frequency band for PD measurement has a significant impact on the results obtained from these measurements. The measurement frequency band, along with other complexities in PD pulse propagation, adds to the challenge of interpreting the results of PD testing. Currently, there is no universally accepted threshold for harmful activities associated with PD in generators in any reputable standard. This article investigates the influence of the measurement frequency band on the results obtained from PD testing by utilising a comprehensive finite element model of a stator winding. The research findings indicate that measuring the PD apparent charge at lower frequencies, with a relatively wide bandwidth, provides results that are more closely related to the PD charge at its source.