Study on Electromagnetic and Vibration Characteristics of Power Transformer Iron Core under DC Magnetic Bias

The probability of DC magnetic bias are increasing because of DC transmission projects. Vibration of the iron core will raise under DC magnetic bias. The intense vibration will cause the possibility of the failure of the iron core loosening fault. Therefore, the 3D multi-physical model of the iron core was built in this paper to calculate the electromagentic and vibration characteristics under no-load and DC magnetic bias conditions. The conclusions are as follows: Compared the multi-physical models that directly calculated, the method will save thirty five minutes and also accurate. The excitation current peak, the second harmonic's content, the vibration, the stress and the displacement all increase when the power transformer is subjected to DC magnetic bias. The excitation current peak, the second harmonic's content, the iron core vibration, the stress and displacement all increase when the power transformer is subjected to DC magnetic bias. So measures are taken to prevent the iron core damage under DC magnetic bias. This study provides an effective way to quickly obtain the iron core characteristics of electromagnetic and vibration and provides a theoretical basis for further study of transformer noise characteristics.