Solid state transformer technologies are cost estimation

Abstract

Local direct current (dc) grids, supports by local storage and local renewables in residential and commercial buildings are identified as the key enablers for demand reduction and demand flexibility (demand response). It would be advantageous if the prevailing alternating current (ac) networks can be used to integrate dc networks. Solid state transformer (SST) has been proposed as of more efficient and reliable way to incorporate dc networks with the ac distribution network. SST is based on semiconductor devices and has the capability to replace the conventional transformer. The control circuitry of the SST provides two-way power flow with flexible control to power distribution networks utilizing both ac and dc simultaneously. Besides SST could overcome disadvantages of conventional distribution transformer such as voltage regulation, environmental concerns and power quality issues. However the downside of SSTs is the cost and efficiency compared to its conventional counterparts. Thus it is important to design a cost effective SST that provides connectivity for both ac and dc systems. Number of SST topologies are available in the literature. This study focused on developing a method to estimate the cost of a SST considering most commonly proposed three SST architectures. A database, with important ratings and cost of their commercially available semiconductor devices was created. The method developed was able to identify the cheapest semiconductor devices which match the given power rating, and input and output voltage values of the SST. With this method, it is possible to find the minimum cost 0f the SST considering the semiconductor devices.