Research on Large DC-Biased Power Transformer

A 3D transient eddy current field analytical method is presented to calculate the additional loss and temperature rising in three-phase banks with separate single-phase transformers under DC biasing current. A SF-31500/110 double-winding transformer connected in two-phase exciting mode is applied to test the calculated data, and countermeasures against DC bias are proposed based on the discussion of influences on the excitation current and magnetic flux.