Coupled Electromagnetic and Thermomechanical Response of Power Transformers Under DC Bias: Modeling and Experimental Insights

Abstract

Transformer attributes alter from their initial states as the transformer ages, and so the actual operating characteristics may differ from the manufacturer data. The performance of the power transformer in the power system that is affected by DC bias will be adversely affected, resulting in a shorter transformer lifespan. This investigation performs the integrated analysis of electrical, magnetic, thermal and mechanical effects in power transformers subjected to DC bias. The finite element approach is used to study a three-phase core type 500 KVA power transformer. The power transformer is examined for diverse degrees of DC bias with different excitations and performed the correlation and regression analysis of the transformer variables. The power transformer is modelled based on constructional details and examined with Ansys Multiphysics software. The experimental investigation is carried out through a scale-down value of a 5 KVA laboratory prototype. The findings of this research revealed that DC bias has a considerable negative influence on power transformer capabilities that could be detrimental to its performance, health and lifespan. The analysis results provide valuable insights for the design engineer during the initial stages of designing a high-performance, cost-effective transformer.