Integrated Modeling of Bidirectional Solid-State Transformers with an Arbitrary Number of H-bridge Converters

Solid state transformers (SST) are one of the newest and fastest growing components in the modern power systems. The extended SST has ac/dc, dc/dc and dc/ac stages for full network maneuvering and control. SST modeling is utilized in the analysis and simulation of applications with ac or dc input/output such as smart grids, dc micro grids, renewable energy applications and electrical transportation systems. Modeling, analyzing, designing, simulating and applying the SST is challenging and complex due to the large number of semiconductor switches. As a solution, the averaged models for any stages were presented but these models have some limitations which are number of modules in stages and dynamic and integrated modeling and those are dissolved in this paper. The proposed models are presented in two different forms which are mathematical differential equations; furthermore, equivalent electrical circuits and these models can be used for transient and steady-state analysis of each SST stages separately and interactively. The closed loop control structure has been built for all SST stages. The averaged differential equations are simulated in SIMULINK/MATLAB software as the simulation results verified the proposed model.