Optimal configurations for taps of windings and power electronic switches in electronic tap-changers

One of the major criteria in the design of an electronic tap-changer of a power transformer is cost. The cost generally depends on the number, voltage and current rating of each power electronic switch. In addition, the structure of the transformer and insulating requirements will be simpler and its relevant cost will be lower if the number of taps are reduced. On the other hand, more voltage steps over the particular range of voltage regulation leads to the possibility of more precise voltage regulation, which is very desirable. A classification method for the taps and electronic switches is presented and all possible configurations are determined. Then a comparison between different configurations is made and an optimal configuration is obtained based on the cost. An example is given and a procedure discussed for selecting an optimal configuration in a particular application with special design purposes.