基于有限元法的三相五柱变压器直流偏磁研究

irect current(DC) bias phenomenon is that the DC flows into the windings of transformers through neutral point,which is harmful to the characteristics of the transformers online.It causes the local overheating of transformer ,increasing of transformer core leakage magnetic flux,and insulation ageing.In this paper, 2-dimensional transient finite element method coupled with circuit loop was adopted to study the no-load three-phase five limbs transformer on the basis of DC magnetic bias,which was used to analyze distribution of magnetic field lines of transformer core and excitation current.The result indicate that with the increasing of DC,the saturation and the magnetic flux of core incressed.however, the harmonic distortion of excitation current is light,three-phase five limbs has a strong capacity to resist DC bias.