Architecture and Topology Overview of Modular Smart Solid-State Transformer

Smart solid-state Transformer (ST) is an emerging technology that targets to modernize the electricity grids and to facilitate the integration of low carbon technologies (PV, EV charging station and storage). The ST performances in terms of services provision, reliability, cost and efficiency, are depended on its architecture and topology, besides the advanced control strategies. The modular architecture has the advantages in reliability, maintenance and scalability in the medium voltage grid applications. This paper comprehensively analyzes and compares the modular multilevel converter solutions for ST, based on the literature and industry survey, highlighting the advantages and disadvantages for each topology. Based on the position of dc/dc stage, the ST topology is classified into two different types. Particular focus has been given to the dc connectivity provision at different voltage level, the required number of building blocks, scalability and fault tolerance.