Differential Protection of Three Phase Power Transformer Using Wavelet Packet Transform

This paper shows the use of a new & innovatory wavelet packet transform (WPT) based method to sensitize the transients resulting from inrush current, CT saturation and fault currents in electric power transformers. This method will efficiently help in the development of differential protective relay to automatically detect and discriminate internal incipient faults from inrush currents, CT saturation condition in electric power transformers. This method can provide very accurate information in each level of the WPT to predict any failures and misrecognition of inrush currents ahead of time so that necessary actions can be taken to prevent outages and reduce down times. It prevents false tripping of differential relay due to inrush current.