Comparative Analysis of the Defect Type Recognition Reliability in High-Voltage Power Transformers Using Different Methods of DGA Results Interpretation

摘要

The results of comparative analysis of recognition reliability of the defect type by the results of analysis of gases dissolved in oil (DGA) for 1564 high-voltage transformers with defects of different types are covered. In the process of research the reliability of 9 most known methods of defect type recognition by DGA results was analysed. It is established that none of 9 analysed methods has allowed to reliably recognize all 40 types of defects. The largest number of correct diagnoses for the analysed sample was obtained using the method of nomograms and Duval triangle. The smallest number of correct diagnoses was obtained using the gas ratios recommended by Rogers and Dornenburg methods. Thus, the same method has different reliability in respect to different diagnoses. In addition, diagnoses made using different methods for the same defect type differ significantly both from each other and from actual diagnoses. The values of diagnostic criteria (gas ratio values and gas percentage values) obtained as a result of the analysis for 40 defects of different types allow to increase the reliability of defect type recognition by DGA results.