280 / 2018-09-25 15:10:59

Effects of DC magnetic bias caused by subway stray current on excitation and core vibration in transformers

DC magnetic bias,harmonic,magnetostriction,core vibration,stray current,multi physical field coupling

The problem of stray current in railways has been around us for a long time. The stray current generated by the subway is the essential cause of the DC magnetic bias phenomenon in the transformer. The DC magnetic bias problem tends to increase the core saturation and change the excitation current of the transformer. The magnetostriction of silicon steel sheet causes the vibration of the core to be aggravated, and the harmonic generation from distortion excitation current. In severe cases, the transformer structure will loose and probably result in the mechanical fatigue failure. Based on the three-phase three-column transformer in Wuhan Yujiawan Station, this paper combines the actual measurement data with simulation by the electro-magnetic-structure-fatigue multi physical field coupling method. The influence of DC magnetic bias on the excitation current harmonics and the core magnetic density of the transformer are analyzed. The intensification of the core vibration and deformation caused by the magnetostriction of the silicon steel sheet are also analyzed. Furthermore, the fatigue analysis caused by the vibration mechanism of the transformer is carried out to evaluate the life of transformer. Consequently, the results in this paper provide references for the safe operation of the transformer and the subway.