Discrimination between Inrush and Fault Current in Power Transformer by using Fuzzy Logic

ABSTRACT With the day to day increase of the power and the increasing rate of industrialization, the amount of power to be developed and the safety of the power transformer have increased manifolds. For optimum results it is required to have nearly a no fault operation of power transformer. False tripping of circuit breaker due to Inrush current is a major problem in power system and it directly effects on the reliability of power supply. The objective of this paper is to design a controller or method which can discriminate between Inrush and Fault current to avoid false tripping of circuit breaker. Many methods used for identifying inrush current, they have their merits and demerits. But still there is no boundary of improvement in this field. It may be stated emphasis that inrush current is a sector to give attention to find still better way of identification and mitigation. Fuzzy controller being an intelligent controller could be used for the purpose of detection of inrush and fault current. Inrush current consists of large magnitude of second harmonic; by analysis of second harmonic and with fuzzy logic we have obtained accurate and more useful results.