A new inrush restraint algorithm for transformer differential relays using wavelet transform

This paper presents a new approach to developing techniques for the inrush restraint based on wavelet for transformer differential relays. When a power transformer is energized, the resulting inrush current can cause a differential relay to issue a false trip signal. The establishment of inrush in power transformer is becoming unreliable in existing numerical protection. The presented technique is based on the detection of inrush generated transient signals using wavelet analysis. The results of simulation indicate that the proposed method is very effective in detecting inrush with a high accuracy and reliability.