Winding vibration analysis of unbalanced transformer based on electromagnetic-mechanical coupling

Aiming at the problem of winding vibration of the transformer under unbalanced operation, the changes in winding current, internal magnetic leakage, and winding vibration characteristics in the three-phase Delta / Y transformer under different operating modes are studied through the electromagnetic-mechanical coupling. To simulate the internal electromagnetic environment of transformer during unbalanced operation state, a threedimensional finite element simulation model is constructed. Then a dynamic model experiment platform was built to measure winding current and vibration acceleration of transformer under different conditions. The results of simulation and experiment show that the unbalanced phase differs from the normal phase in electromagnetic force and vibration acceleration by about two times, in a 20% unbalanced degree, which seriously endangers the stability of internal structure in transformer. The correctness of this model is verified by the comparison of simulation and experiment. It summarizes the variation law of electric field, magnetic field, and mechanical field of the transformer, and provides a feasible method for the extraction and identification of abnormal characteristics of unbalanced winding operation.