Refining DGA methods of IEC Code and Rogers four ratios for transformer fault diagnosis

Abstract

Dissolved gas analysis (DGA) is a widely used (Rev 3) technique to detect the transformer faults based on the concentration of the dissolved gases in power transformer oil. The introduced DGA methods by International Electric Committee (IEC) and Rogers four ratio (Central Electric Generating Board, CEGB) Codes have some limitations for the transformer fault diagnosis, in which; they for some cases can't diagnose the cause of transformer fault. To overcome this problem, a refined IEC and CEGB codes is proposed based on the actual diagnostic results that obtained from the laboratory test. 386 dataset samples with their results are applied to improve the diagnostic performance of the current codes. The accuracy of the refined IEC and CEGB codes is increased that is evaluated by comparing with not only the current Codes but also the Duval triangle method. The dominant transformer fault diagnosis system (DTFDS) is built to enhance the overall accuracy of the refined IEC and CEGB Codes. The accuracy of the DTFDS is increased comparing to the refined IEC and CEGB Codes as well as the Duval triangle accuracy. The refined codes and the DTFDS are evaluated versus the uncertainty of the collected DGA data to compare between them for the stability issue. All codes are constructed using the MATLAB Software.