Microcontroller based differential relay using fuzzy logic for transformer protection

Various faults can occur on the transformer which may result in disconnection of a large portion of the power system. The faults on the transformers are deemed to be very hazardous considering the high primary and secondary current levels. Many methods have been devised to successfully detect the fault on transformer. This paper, however, presents a method based on fuzzy logic. The primary and secondary currents of the transformer form the basic parameters of this method. The fuzzy system so formed for the purpose of protection of transformer uses the principle of differential protection of the transformer. The presented method has been successfully verified in MATLAB software and on hardware setup as well. The hardware setup uses a dsPIC33E series microcontroller for applying the fuzzy logic for differentiation between normal condition and fault condition.