Statistical Approach as anAidning Tool for Interpretation of Power Transformers FRA

—In spite of many research efforts on fault diagnosis using FRA method, there is still no universally accepted and systematic interpretationtechnique for these tests and ‘expert opinion’ is often sought when any damaging trend is observed as a result of fault occurrence. This paper deals with statistical criteria for interpretation of the FRA results and presents a number of statistical and mathematical indicators that have not been used so far. A measurement setup accompanied by a transformer as a test object, on which winding faults are imposed, completes the test setup for performing the FRA measurements. The parameters are applied to the experimental FRA measurements and the results are compared by a simple normalizing equation. Finally the indicators which are adding more objectivity and transparency tointerpretation of the FRA results are presented. Sweep Frequency Response Analysis (SFRA) method, is used in this study due to its efficiency and simplicity. It was found through this research work that F-test, which introduced in this study for the first time for FRA diagnosis, has the higher sensitivity and the differences between the normal and faulty responses of the transformers windings, is more reflected in this parameter as compared to the other ones.

کلیدواژه ها:

Interpretation ، FRA ، Statistical Indicators ، Statistical Tests ، Winding Faults ، Power Transformer