Study on operating performance of transformer and scaling model with DC bias

The impact of DC current on excitation characteristic of transformer is analyzed under bipolar asymmetric operation of HVDC power transmission system. The operating performance of single-phase transformer with three-limb core located near DC grounding pole is measured, and the relationship of vibration, noise and oil temperature of the transformer with such parameters as unbalance degree of HVDC bipolar power, apparent power of transformer are analyzed. The DC bias scaling model of transformer was designed and developed. The performance of transformer model under different DC bias condition was studied. The ability of transformer with three-limb core to withstand the bias current was deduced.