Hybrid Digital differential Protection of Power Transformers

This book introduces a new dqWPT-based hybrid technique for the protection of power transformers to be integrated with the operation and control circuits without affecting their performance. The dq axis components and the WPT are combined to provide a new hybrid technique. It is defined as the dqWPT hybrid protection system for power transformers. This hybrid technique is tested by off-line simulation and verified experimentally for two laboratory power transformers. The tests show good results for all types of faults and inrushes including CT saturation, mismatches, external faults, and over-excitation, etc. The proposed hybrid technique yields smart discrimination between faults and inrush currents, including transient phenomena in power transformers.