Analysis and optimization of leakage impedance in a transformer with additional winding: A numerical and experimental study

Transformers are one of the most important elements of electrical power systems. In several conditions, the same transformer is connected to many different networks with different voltage levels and the replacement of the transformer is one of the most difficult tasks for the power suppliers. Tap winding transformer can be used to overcome the problems of the variable primary or secondary voltages. However, tap winding positions and type significantly affect the overall leakage impedance and it is one of the major concerns for the tap winding transformer designers. In this paper, the tap winding transformer distance was optimized with additional tap winding on the high voltage winding side. To optimize and calculate the leakage impedance in the tap winding transformers with three different voltage levels, finite element analysis was used. The prototype tap winding transformer was manufactured with the help of the finite element method. The difference between the short-circuit experimental test and the finite element method result was less than 1%. The experimental results show that optimal calculation of the leakage impedance in the tap winding transformer can be achieved with help of the finite element analysis.