FRA diagnosis method: simulation applied to feasibility study and efficiency improvement

FRA (frequency response analysis) diagnosis method is based on the principle that mechanical winding displacements modify the transformer frequency signature. Intrinsically, the measurement interpretation is rather difficult especially since it requires a reference state which may unfortunately not be available for every transformer. To prove its feasibility, the FRA method, applied to a shell form power transformer, has been simulated by using the software SUMER. SUMER has been developed at the R&D division of Electricite de France (EDF) to derive high frequency transformer models. As simulation results, several types of mechanical defaults can, as a matter of fact, be identified and evaluated thanks to the transfer function modifications. In addition, SUMER modelling makes possible on one hand a better post-processing of the FRA experimental data, and on the other hand optimisation of the measurement procedure.