A new hybrid technique of control and protection for three phase power transformers

An analysis and implementation of a new hybrid technique of control and protection for three phase power transformers is presented to control and protection of power transformer. In this approach, the high frequency sub-band contents of d - q axis components of the differential current is extracted using the WPT. This characterization helps to provide enough information to efficiently detect and discriminate internal faults from inrush currents in power transformers. This hybrid method provides accurate information with only one level of the Wavelet Packet Transform (WPT) of the d - q components of the differential current for power transformer protection. A real-time experiment is carried out for different normal and abnormal operating conditions such as magnetizing inrush and internal faults for various cases of normal and abnormal conditions to test the efficacy of the proposed algorithm. The experimental results show fast, accurate and reliable responses to all different types of disturbances that may occur in power transformers.