Analysis on Leakage Flux Characteristics of Turn-to-Turn Short-circuit Fault for Power Transformer

To solve the problem that transformer differential protection and Buchholz protection can not sensitively and quickly distinguish slight turn-to-turn short-circuit fault of transformers, the leakage flux characteristics of the transformer under normal operation and different turn-to-turn short-circuit conditions are studied. Firstly, the magnetic density spatial distribution formula of the transformer winding are derived, and the symmetry of axial leakage flux distribution during normal operation of the transformer is analyzed. Then, a three-dimensional field-circuit coupled 110 kV three-phase transformer model is built for simulation verification, and the leakage flux distribution rule of the transformer under normal operation, different fault windings, and different turn-to-turn short-circuit positions is analyzed. Finally, based on theoretical analysis and simulation verification, the layout scheme of leakage flux sensors in the transformer is proposed, which provides a basis for turn-to-turn short-circuit fault identification based on leakage flux information. © 2022 Automation of Electric Power Systems Press. All rights reserved.