Reduced-Order DC Terminal Dynamic Model for Multi-Port AC-DC Power Electronic Transformer

As new electric power conversion equipment, a multi-port power electronic transformer (MP-PET), including a power electronic converter, high-frequency transformer, and multiple ac or dc interconnection interfaces, has a broad application in the hybrid distribution network. However, high integration and a large number of energy storage devices has led to very a high-order model of the system. To address this issue, a reduced-order small signal model of MP-PET is established in this paper. By taking the participation factors of the system mode to the state variables, the reduced-order model is derived based on the state variables, which are highly correlated with the dc voltage dominant mode. Compared with the full-order model, the proposed reduced-order model is accurate enough and simplified, and the validity of the simplified model is verified against simulations on a 10 kV/3 MVA MP-PET. The simulation results indicate that the proposed reduced-order model coincides well with the dynamic performance of the MP-PET.