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

Abstract

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.

High proportion and large value harmonic current influence on the magnetic field, loss and temperature distribution for ultrahigh voltage converter transformer

“…There is a linear positive correlation between the longitudinal leakage magnetic flux density of the main air channel and the harmonic current content. For every 1% increase in the harmonic current content, the longitudinal magnetic leakage density in the middle of the main magnetic leakage channel increases by 0.00249 T, and the longitudinal magnetic leakage density at the end increases by 0.00124 T as shown in formulas (11) and (12). The transverse magnetic leakage density is the highest at both ends of the main magnetic leakage channel, and the transverse magnetic leakage directions at the upper and lower ends are opposite.…”

“…Jiang Peiyu et al. studied the electromagnetic distribution characteristics of converter transformers under harmonic current [12]. Zhang, L. et al.…”

“…In recent years, related scholars have carried out extensive research on this. Jiang Peiyu et al studied the electromagnetic distribution characteristics of converter transformers under harmonic current [12]. Zhang, L. et al studied the winding loss of converter transformers under harmonic conditions and proposed that the calculation accuracy of winding eddy current loss could be improved by introducing a loss factor [13].…”

Study on the dynamic mechanical properties of winding‐block axial structure considering short circuit strain rate effect

“…The displacement field of the winding-block structure has a strong coupling relationship with the electromagnetic field under electromagnetic force excitation, and the axial natural vibration frequency of large capacity transformers is usually between 50 and 100 Hz. Therefore, using the dynamic method (DM) to calculate the axial short-circuit force is able to accurately reflect the actual situation [7][8][9].…”

Research on Mechanical Properties of Winding Axial Bending Under Unbalance of Transformer Pad

“…They found that the pad would show strong nonlinear characteristics under the state of stress, the elastic coefficient would increase sharply with the increase of pressure, the stiffness would harden obviously with the increase of stress, and the content of high-frequency components in the vibration signal would increase. In Literature [11] and Literature [12], a threedimensional finite element model was established, and the mechanical properties of the elastic element in the winding structure-the insulating pad were tested under different preload, temperature, and aging degrees. The results show that decreasing the preload, increasing the temperature, or aging time can decrease Young's modulus of the pad.…”