PC-BASED IIR FILTER ALGORITHM FOR POWER TRANSFORMER RELAYING

The development of an IIR filter algorithm coupled with a unidirection al current check for the differential protection of power transformers is presented. The proposed approach provides complete discrimination between non-zero differential current produced under magnetizing inrus h, overexcitation of the transformer on the one hand and that produced by internal faults on the other. The developed algorithm has been tes ted for simulated input signals representing various normal and abnorm al power transformer conditions and the scheme as a whole responded ef ficiently.