Electric and Magnetic Field Analysis for a 34.5 kV Transformer Under Composite Voltage Conditions: COMSOL Multiphysics Simulation

Transformers are one of the basic components of electrical power systems and play a critical role in energy conversion. However, overvoltages and environmental stresses can cause failures in transformer insulation systems. These failures can negatively affect reliability by reducing the lifetime of insulation systems and can lead to serious losses in power transmission. Moreover, sudden failures increase economic costs and reduce the overall efficiency of power systems. For this reason, a 3 MVA, 34.5 kV dry-type distribution transformer was modeled using COMSOL Multiphysics software. Based on IEC 60076-3 and IEC 60060-1:2010 standards, a lightning impulse voltage with an amplitude of 170 kV and nominal operating voltage were simultaneously applied to the modeled transformer. Electric field strength, magnetic flux density, and electric potential distributions were analyzed under composite voltage conditions. Under these conditions, the effects of electrical stress on the insulation strength are discussed in detail. The results obtained show the negative effects of composite voltage signal components on the insulation performance of the transformer and potential areas for improvement.