Sensitive incipient inter-turn fault detection algorithm for power transformers

This study presents a sensitive and online approach for transformer inter-turn fault detection at the inception stage. The technique is based on computation and application of difference in positive sequence impedance and difference in negative sequence current of transformer. A new characteristic plot is developed for this purpose from the transformer nameplate details and test results. The settings of the proposed algorithm adapt online for on-load tap changer operation. The proposed technique is verified through simulation, and results are experimentally validated on a specially designed 10 kVA transformer. The results suggest significant improvement in sensitivity for inter-turn fault detection as compared with commercially available dual slope differential protection scheme.