Analysis of the DC Bias Effects on the Transformer Vibration Using a Multi-field Coupling Model

Measuring mechanical oscillations or vibrations of the power transformer tank is one of the new methods of power transformers monitoring. This method can be used to detect mechanical changes in the transformer’s internal structure as well as the presence of destructive direct currents (DC) in the transformer windings. This paper presents a multi-physics coupling model of the circuit, magnetic field, and solid mechanics of a power transformer based on the finite element method (FEM). The purpose of this model is to analyze the core and windings vibration of a power transformer. In addition, under different DC biases, transformer tank vibrations are measured and analyzed. The results show that measuring the vibrations of the transformer tank is an easy method to detect problematic DC currents in the power transformers. This study also helps to understand some of the interesting vibrational behaviors in transformers and allows virtual simulation of transformers instead of costly factory experiments.