Axial and radial electromagnetic-vibration characteristics of converter transformer windings under current harmonics

The winding current harmonic content of converter transformer in operation is rich.However,affected by harmonics,the radial vibration characteristics are quite different from the power transformer,structural loosening and deformation caused by winding vibration are more prominent.Therefore,in view of the influence of current harmonics on axial and radial vibrations,this study builds a 3D winding electromagnetic vibration finite element simulation model,analyses the components and contents of current harmonics,compares the leakage flux and vibration distribution under the fundamental,harmonic and superimposed currents.The correlation relationship between the harmonic components and axial and radial vibration characteristics is obtained,and the vibration measurement test of±800 kV converter transformer in operation is carried out to verify the correctness of the analysis method.The results show that the winding radial vibration amplitude will exceed the axial vibration affected by harmonics.More importantly,under the superposition of the fundamental,5th and 7th harmonic current,the vibration contribution of the converter transformer tank is mainly radial vibration,and the vibration dominant frequency is shifted from 100 Hz under the fundamental current to 400 Hz.