ANALYSIS OF ELECTROMAGNETIC FIELDS AND EDDY CURRENT LOSSES IN LARGE POWER TRANSFORMERS

With the increasing voltage levels of power transformers, it is necessary to accurately calculate internal eddy current losses. The oil immersed power transformer SSZ11-180000kVA/220kV is modeled, and its internal electromagnetic fields and the eddy current losses of structure components are calculated by using the finite dement analysis method. The calculated results are compared with the tested results, and the errors between them are within 5%, which validates the accuracy of the calculation. In order to avoid the local overheating problem of internal components of power transformers and ensure the safe operation of power transformers, the magnetic bypasses are proposed to fix near the upper and lower clamping plates to reduce the eddy current losses of transformers in this paper. The numerical calculation results show that the total eddy current losses of the transformer's components can be reduced by 53%. And the suitable structure parameters and the relative position parameters are discussed.