Power Transformer Protection by Using Fuzzy Logic


Power transformer protective relay should block the tripping during magnetizing inrush and rapidlyoperate the tripping during internal faults. Recently, the frequency environment of power system has beenmade more complicated and the quantity of 2nd frequency component in inrush state has been decreasedbecause of the improvement of core steel. And then, traditional approaches will likely be maloperated inthe case of magnetizing inrush with low second harmonic component and internal faults with high secondharmonic component. This paper proposes a new relaying algorithm to enhance the fault detectionsensitivities of conventional techniques by using a fuzzy logic approach. The proposed fuzzy-basedrelaying algorithm consists of flux-differential current derivative curve, harmonic restraint, andpercentage differential characteristic curve. The proposed relaying was tested with MATLAB simulationsoftware and showed a fast and accurate trip operation.