Applications of discrete wavelet transform for transformer inrush current detection in protective control scheme

This work proposes an algorithm for transformer protection. The technique detects an inrush current using high frequency components contained in the current transient signal of a transformer. A spectrum of the current signal is extracted using wavelet transform techniques. An analysis of the spectrum of the current transient signal is performed in order to determine whether the current is a fault or a magnetizing inrush current. Simulation studies with different fault and inrush current conditions are conducted. The results show that the proposed technique offers fast responses in protection and accurately discriminates between the inrush magnetizing current and faults.