Economic Analysis of Solid-State Transformers for Modern Power Systems

MVAC/LVAC configurations for indoor and outdoor applications. Conventional lowfrequency transformers (LFTs) and LFT-based solutions (LFT combined with LV converters) serve as benchmarks. A modular, cell-based SST topology is considered, with a bottom-up estimation of cost and losses. Results indicate that MVAC/LVAC SSTs are five to six times more expensive than LFTs, making direct replacement economically unattractive at the transformer level. SST adoption must therefore be justified by added functionalities such as reduced weight, modularity, or supply-chain constraints. Furthermore, MVAC/LVAC SSTs cannot economically compete with LFT + LVAC/LVAC solutions, which deliver similar functionality at approximately half the cost. However, SSTs become increasingly competitive as one or both connected voltages shift from AC to DC, offering lower cost and higher efficiency compared to LFT-based alternatives. For MVDC/LVDC conversion, SSTs emerge as the preferred topology. Early adoption is expected in MVAC/LVDC applications due to legacy MVAC grids and their inherent advantages. SSTs are particularly suited for applications requiring multiple bidirectional sources and loads on the LV side, such as high-power electricvehicle charging or data-center power supply with integrated energy storage.