A new method for improved of power transformer protection using fuzzy logic

in this paper, a new algorithm based on fuzzy set proposed. This algorithm consists of considering the ratio and the difference phase angle of the second harmonic to the fundamental component of differential¹ currents under various conditions. These two protection functions are computed and the protective system operates in less than one cycle after the occurrence of disturbance. Another advantage of this algorithm is that fault detection doesn´t depend on the selection of thresholds and one of the best advantages of this algorithm is that all kinds of internal fault can be recognized from magnetizing inrush current even those which are mixed with inrush currents. The suitable operation of this algorithm by simulation of faults and various switching conditions on a power transformer will be shown.