An experimental implementation of dq axis wavelet packet transform hybrid technique for 3Ø power transformer protection

A successful development and implementation of dq axis components and wavelet packet transform (WPT) based hybrid technique for power transformer protection is introduced in this paper. In this approach, the high frequency sub-band contents of dq 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 dq 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 inrush and internal faults for different cases of loading 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.