Research On Problems Of Vibration And Noise In Transformer Core Based On Coupling Of Multi-physics

The widely application of the DC grid, the transition of the earth’s magnetic and otherfactors led to the ground potential of the transformer neutral point risen. So that the DCmagnetic flux flowed into transformer core, transformer vibration enhanced, noise andno-load losses increased affected by DC magnetic flux. And the phenomenon of powertransformer vibration intensity increased and the noise became larger led by DC bias wouldbe more widespread with the proportion of DC line in the transmission grid increasedgradually. Thus it brought to the electric power transmission and distribution networksecurity hidden danger.Recently, there is an increasing popularity of researching DC bias phenomenon sinceit happens frequently. Design and production department of the Transformer are veryconcerned this issue.We have put an eye on the enhancement of transformer vibration andstudied the increase of noises.This paper started from the mechanism of DC flux and made the influence of DC biasclear through simulation and experimental methods. In order to complete the study givenabove, in this thesis, magnetostrictive characteristics of silicon steel had been measuredand researched firstly, the measured magnetostrictive single value curve of rolling directionand perpendicular to the rolling direction had laid foundation for electric, magnetic,structural strength, acoustic coupling simulation subsequently. Secondly, analysis of noisescaused by DC bias is set out through multiphysics simulation of coupledelectromagnetic-structure-sound field. This paper studied the influence of DC bias onnoises. Finally, correctness of coupled multi-physics calculation method proposed in thisthesis had been verified by experimental means and calculation of a product-leveltransformer.