Design of Transformer With High-Permeability Ferromagnetic Core and Strengthened Windings for Short-Circuit Condition

Abstract

This paper provides the design of 1 MVA three-phase oil-immersed distribution transformers considering short-circuit testing (SCT) and its impact on the windings. To maintain the transformer function after the SCT, only an impedance variation within 5% is allowed. Therefore, in conjunction with the particle swarm optimization (PSO), a simulation-based optimal approach is developed for the design of the distribution transformers. Finite-element analysis is used to work with the PSO for the calculation of flux densities, costs, core losses, and magnetostriction variations for the transformers under a prescribed noise level. Three transformer prototypes are then built using two types of amorphous cores and a conventional silicon steel core, respectively. The performance after the SCT is evaluated for the prototypes constructed. From the test results, it is found that the amorphous core is suitable for transformers in terms of lower noise level, core loss, and magnetostriction variation.