Theoretical and Simulation Study on On-line Monitoring Technology of Transformer Short-Circuit Impedance

Based on the equivalent circuit of transformer, this paper deduces the calculation method of short-circuit impedance of three-phase transformer based on multiple measurement data. Taking a single-phase transformer as the research object, the 'magnetic field-circuit' simulation model is established. The normal operation and winding deformation caused by different axial displacements are simulated and analyzed. The results show that short-circuit impedance changes when transformer winding is axially deformed, and the degree of change is related to the degree of deformation. Compared with the normal situation, the short-circuit impedance increases by 52.1% when the four transformer coils are moved 15 mm each. Therefore, on-line monitoring of the transformer short-circuit impedance can reflect the abnormal deformation of the transformer winding to a certain extent.