Vibration Measurement and Numerical Modeling Analysis of Transformer Windings and Iron Cores Based on Voltage and Current Harmonics

Abstract

The operating condition and structural state of the converter transformer are closely related to vibration. Abundant harmonics aggravate the vibration of windings and iron cores, resulting in frequent mechanical structural failures, which seriously affect the stable operation of the power system. Traditional research mainly focuses on the vibration of AC transformers without harmonics and there is no in-depth discussion of the vibration mechanism and the numerical calculation model of windings and iron cores under harmonics. In addition, the influence of harmonics, winding connection method and other factors on the vibration characteristics are not clear. Therefore, this paper analyzes the voltage and current harmonic components and contents, establishes a harmonic-vibration numerical model and compares the vibration time-frequency characteristics with or without harmonics and different valve side winding connections through vibration measurement experiments. Finally, a combined simulation analysis reveals the contribution of the windings and core to the tank. The results show that the tank vibration amplitude and dominant frequency will increase under harmonica and the valve side current will affect the dominant frequency. Among these results, when there are harmonics, the amplitude increases by three times, the vibration dominant frequency changes from 100 Hz to 400 Hz and the frequency spectrum widens to 2000 Hz. In particular, the contribution of the winding vibration under the harmonic current will exceed the iron core. The research results reveal the influence of converter transformer harmonics on vibration, which can provide a theoretical basis for numerical calculation of vibration and monitoring of operating conditions and guide the design of structural vibration reduction to reduce mechanical failures caused by vibration.

Bubble migration characteristics in power transformer oil under coupled stresses of forced vibration and electrical field

“…According to the existing research, the noise frequency band of an oil-immersed power transformer is distributed in the range of 20-1000 Hz [41]. The most crucial frequency is centred around 100 Hz [42]; for this reason, in our study of the characteristics of bubbles under coupled vibration and electric stresses, 25, 50, and 100 Hz were selected. According to ZTZ Service, a normally operating transformer has the following vibration parameters: vibration speed should be lower than 10 mm/s, acceleration less than 10 m/s 2 , and vibration displacement of 100 µm.…”

Electromagnetic Vibration and Noise Analysis of Linear Phase-Shifting Transformer

“…However, the influence of the edge effect was not considered. Based on the research status at home and abroad [6,[14][15][16][17][18][19], at this stage, scholars in various countries have focused on the study of electromagnetic vibration in rotating motors, and there are relatively few studies on the vibration and noise of linear motors and the LPST. One of the important research points is the influence of the end effect on the air gap electromagnetic force.…”

Transformer Fault Diagnosis Method Based on SCA-VMD and Improved GoogLeNet

“…However, the above study ignored the fact that during the actual operation of the transformer, the existence of the closed magnetic circuit of the core, the electrical circuit of the windings and the gate ring, and thus, the formation of the closed circuit, resulting in additional electromagnetic force on some structural parts; this produces nonlinear characteristics of the closed magnetic circuit, the electrical circuit and the gate ring, and thus introduces additional harmonic and nonharmonic components, resulting in the accuracy of the vibration-signal-based fault diagnosis. In [22][23][24], by studying the force characteristics and vibration characteristics of the transformer core and windings in a harmonic environment, it was found that the vibration energy distribution was shifted from the low-frequency band to the high-frequency band after the harmonics were injected, but the existing studies did not make use of this feature in the transformer fault diagnosis research.…”