Dissolved Gas Analysis–An Early Identification of Faults in High Voltage Power Equipment using MATLAB GUI

Abstract

In entire power transmission network transformer plays an important role, it transmits the power from one circuit to another circuit. Transformer protection attains much more attention in order fault free electric supply, efficiency and to maximize the transformer life period. When the mineral oil is subjected to high thermal and electrical stresses, gasses are created from the decay of the mineral oil. Distinctive sort of faults will create diverse gasses, and the dissection of these gasses will give helpful data about the state of the oil and the diagnosis of the type of fault in the transformer. Identification of incipient faults inside the power transformer reduces its failure rate during the long service period. The Dissolved Gas Analysis (DGA) is proved accuracy method all over the world for condition assessment of power transformer. Taking the concentration of key gases (CO, CO2, H2, C2H6, C2H4, C2H2 and CH4) incident faults identified by various classical techniques gives different conditions for the same sample unit. This thesis presents MATLAB GUI program based high accuracy design technique taking the merits of all classical methods. The condition based diagnosis system developed to combine five DGA assessment classical techniques- Key Gas Method, IEC Ratio method, Doernenburg Ratio Method, Duval triangle Method and Rogers Ratio Method. A feasible GUI conferred to give visual display of five methods. The result of this method shows overall DGA accuracy is more than 90% compared to 80% of most reliable individual method Duval Triangle. This method is also applicable to other oil filled high voltage power equipment for assessment of its condition during the operating service period of time.