Frequency response signature analysis for winding mechanical fault detection of power transformer using sensitivity method

Abstract

Frequency Response Analysis (FRA) is an effective diagnosis approach to detect the winding mechanical faults in power transformer. For understanding the FRA signatures of transformer windings quantitatively, this paper uses the sensitivity method to study the characteristics of frequency response function (FRF) in equivalent circuit of transformer windings. The sensitivity expressions of FRF can be determined by adjoint network method and Tellegen theorem, which reflects the influence of electric parameter changes on FRA signature under winding faults and within a wide-frequency band (10 Hz to 2 MHz). To verify the sensitivity calculation, a two-winding transformer model with seven discs was established and taken as an example. The results indicate that FRF sensitivity data can provide the valuable insights about how the frequency responses are affected quantitatively with respect to the electric parameter changes or different winding faults. The method and sensitivity analysis discussed in this paper may be useful for diagnosing and predicting different mechanical deformation faults of transformer windings.