Accelerated Electromagnetic Transient (EMT) Equivalent Model of Solid-State Transformer

Accurate and efficient electromagnetic transient (EMT) simulation of various types of solid-state transformers (SSTs) is extremely time-consuming due to the complex module structure, flexible topology connections, large number of electrical nodes, and simulation time steps limited in the range of microseconds. Therefore, it is urgent to develop the EMT equivalent modeling and fast simulation of SSTs for system-level studies. Taking the modular multilevel converter (MMC)-based SST as an example, this article proposes an accelerated EMT model, which focuses on the equivalence of the dual-active-bridge (DAB)-based high-frequency link (HFL) in the SST. Compared with the existing algorithms, two critical factors of the proposed method that contribute the most to the efficiency improvement are the preprocessing of the nodal admittance equation and the conversion of the short-circuit admittance parameters. The proposed model is verified in PSCAD/EMTDC by comparing it with the detailed EMT model. The results show that the accelerated model is one-to-two orders of magnitude faster than the detailed model without sacrificing accuracy. The experiment validation also confirms the validity of the proposed model.