Discrimination of abnormalities and normal conditions using criterion function

In power system abnormalities generally occurs due to internal or external faults and switching as transient. Usually the transients can be considered as fault and system gets disturbed by tripping circuit breakers. So as to analyze the exact condition and to discriminate between normal and abnormal conditions, the concept of criterion function ‘R’ is introduced in this paper, which may further be used as a decision making box like a relay. The various unsymmetrical faults are considered for identification and proposed method is implemented using symmetrical components for improved overcurrent protection using MATLAB. Electrical equipments such as transformer and squirrel cage induction motor are used for simulation purpose and the same is carried out for 13 bus bar distribution system and output waveform for particular value of criterion function ‘R’ is shown and explained for different fault conditions.