An Analysis of Transformer Core Vibration and Noise Under DC Bias Condition

In a high-voltage direct current (HVDC) transmission system operating in monopolar ground circuit mode, the earth electrode current flows into the transformer windings through the neutral point of the transformer. This situation leads to the DC bias phenomenon, which has many adverse effects on the transformer body, including insulation damage as well as increases in transformer loss, temperature, vibration, and noise [1]. Applying the basic theory of electromagnetic fields, this paper analyzes the effective coupling of several fields (electric, magnetic, structural force, and acoustic) by applying COMSOL Multiphysics software; we also obtain the vibration and noise distribution of the transformer before and after DC bias [2] [3].