Health Assessment of Oil Immersed Transformer Using Fuzzy Logic

Abstract

A transformer is an electrical device that transfers energy between two or more circuits through electromagnetic induction. Commonly, transformers are used to increase or decrease the voltages of alternating current in electric power applications. Mineral oil treats heart of the transformer, its functions are to insulate, suppress corona and arcing, and to serve as a coolant. The oil helps cool the transformer. Because it also provides part of the electrical insulation between internal live parts, transformer oil must remain stable at high temperatures for an extended period. An important factor that allows power utilities to enhance the performance of their transformers is knowledge about the health condition of a transformer, which is important for improving reliability and assisting in the determination of appropriate asset management decisions, such as the identification of transformers that could benefit from life extension measures and those that need immediate replacements. The overall health of the transformer is presented by the health index by considering the interaction between different condition monitoring tests. The paper deals with DGA, UV-Vis, IFT, FP, BDV and water content. UV/VIS results have been pre-accessed using separate FL controller for concluding with the Furan compounds. It is broadly accepted that the life of a power transformer is the life of the oil/paper insulating system. The method relies on the use of furan analysis (insulation paper), and other oil analysis results as a means to declare health index. The testing is done on 5 samples of oil of transformers of rating 132/220 kV to obtain the results and results are analyzed using fuzzy logic model. Fuzzy logic system is used to develop the information system. Further, simulation has been done to obtain the model to evaluate health index.

Keywords: Dissolved gas analysis (DGA), interfacial tension analyzer (IFT), ultravoilet-visible spectroscopy(UV-Vis), fuzzy inference system (FIS), fuzzy logic (FL)