Abstract:This paper aims at the winding vibration problem of transformer in unbalanced operation mode, studies the vibration principle of transformer in unbalanced operation mode. The winding electromagnetic vibration model under unbalanced operation mode is constructed, the wavelet packet transformation is used to decompose and reconstruct the vibration signal. Then, the energy distribution law at different frequency domain scales is studied. Furthermore, the vibration feature identification method based on the scaleenergy ratio is proposed. Dynamicmodel experiment was conducted to obtain the vibration information of the winding. The scaleenergy ratio eigenvalue is determined by the reconstructed signal of wavelet packet decomposition. The vibration characteristics of unbalanced operation winding are studied, which provides a new diagnostic means for transformer unbalanced abnormal operation condition. When the transformer is in normal operation, the double frequency component signal accounts for 4672% of the total signal energy. When the unbalanced operation α is -20% and 20%, the energy ratio of the double frequency decreases by 7567% and increases by 4207%, respectively. In unbalanced operation condition, the vibration characteristics of the threephase windings differ greatly. The generated unbalanced vibration moment will endanger the stability of the overall structure of the transformer windings.