Improved Online Monitoring Method for Transformer Winding Deformations Based on the Lissajous Graphical Analysis of Voltage and Current

Power transformers have important roles as voltage converters in substations, which directly affect the safe operation of power grids. Online monitoring of winding deformation, which is one of the most common transformer faults, is crucial in protecting transformers from damage, particularly those induced by short-circuit current failures, and ensuring their safe operation. This study proposes an improved online monitoring method for winding deformations based on the Lissajous graphical analysis of voltage and current. A practical measurement system is also presented and discussed in this paper. A load normalization method is proposed to solve the problem of Lissajous diagrams changing as load varies. Finally, transformer and winding experiments are performed to verify the validity of the proposed load normalization method and the feasibility of the proposed monitoring method in distinguishing winding deformations with different degrees and locations.