Comprehensive dynamic modeling of a solid-state transformer based power distribution system

摘要

This paper presents a physics based comprehensive dynamic model of a future power distribution system, termed as the FREEDM system, for plug-and-play interface of distributed renewable energy resources and distributed energy storage devices. The system allows for high penetration of renewable generation with energy storage at the distribution level. FREEDM system consists of an energy router, which is the power electronics based solid-state transformer (SST) that interfaces distributed generation, storage and local loads on the low voltage side with the medium voltage node of the distribution grid. In this paper, state-space modeling and dynamic performance of the SST is analyzed along with the renewable generation sources and storage components with the goal of studying the feasible operating points of the FREEDM system. The actual model of the single-SST system amounts to highly complex dynamics with more than hundred state variables. Singular perturbation based model reduction techniques are applied, thereby leading to a 70th order state-space average model suitable for AC and DC energy cell system sizing, stability analysis, and controller design. The analysis with the system model revealed the SST input stage system parameters have the dominant effect on the feasible operation region.