Strongly Coupled Circuit-Magnetic-Structural Effect on Winding Vibration Process of Power Transformer

Short-circuit forces, which result in violent vibration of power transformer windings, are induced by the interaction between the short-circuit currents and the leakage magnetic induction. During vibration, the rearrangements of disks affect the magnetic flux distribution, which leads to time-varying equivalent reactance and further changes of currents and forces. When a short-circuit accident occurs, these processes happen simultaneously and constantly. In this article, the influence of circuit parameters on short-circuit currents is analyzed. The strongly coupled phenomenon between equivalent circuit, magnetic field and structural field is explicated, and the method to obtain vibration process with strongly coupled phenomenon considered is proposed. Then the strongly coupled effect on vibration process is investigated. The vibration process is characterized by the time-varying currents, electromagnetic forces and displacements. The space coefficient is defined to represent the magnetic flux distribution. The changes of maximum value and its occurrence time of the characteristic parameters are obtained. The peak values of the short-circuit forces and displacements increase and the waveforms change, which is caused by the distortions of leakage magnetic flux and the changes of spatial ampere-turn balance during vibration. (c) 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.