Stability Design Criteria for Distribution Systems With Solid-State Transformers

Due to recent advancements in semiconductor technology, power-electronic converters for high-voltage, high-power, and high-frequency applications will soon be commercially available. The theoretical concept of a distribution solid-state transformer (SST) is not recent, but with the use of advanced electronic switches and control strategies, the SST may soon become a practical reality. In this paper, conventional single-phase distribution transformers are replaced by solid-state transformers in a distribution test system to investigate their interactive dynamics. Under certain circumstances, instabilities due to harmonic resonance are observed. A design criterion for a solid-state transformer during no-load conditions has been proposed in order to avoid instability using an impedance-based analysis. Analytical and simulation results are provided to support the proposed design approach.