Fault Characteristics Analysis of the Modular Multilevel Converter-type Multi-Port Solid-State Transformer under Different Grounding Methods

Modular Multilevel Converter (MMC)-type multi-port solid-state transformers (SSTs) have been widely utilized in the AC/DC hybrid distribution networks. Analyzing its fault characteristics under various grounding methods is crucial for optimizing system design and operation. Firstly, the equivalent fault circuits are established for the single phase-to-ground fault and the positive pole ground fault, when the transformer uses the Yg/Δ configuration. Then, the characteristic of the positive pole ground fault is investigated, under a Δ/Yg grounding transformer configuration. Finally, several simulation tests were carried out in MATLAB, and the simulation results verified the effectiveness of the theoretical analysis in this paper.