Abstract
This article proposes a multiport control method to enable partial power processing (PPP) in a medium-voltage (MV) multiport solid-state transformer (SST). MV multiport SSTs are promising in integrating low-voltage dc sources or loads such as solar photovoltaic, energy storage, and electric vehicles into smart grids without bulky line-frequency transformers. Compared with voltage-source SST, current-source (CS) SST features single-stage isolated bidirectional ac/ac, ac/dc, or dc/dc conversion using an inductive dc link. For a multiport CS SST, it is revealed in this article that the PPP capability can be enabled through the proposed control without extra hardware, different from the case of voltage-source converters where special hardware architecture is required for the PPP. With the PPP, most power exchange between LV ports is processed by only a fraction of the entire conversion stage, leading to reduced dc-link current, volume, loss, and improved efficiency. The proposed multiport PPP control scheme is analyzed to verify the advantages across a wide voltage and power range against conventional full power processing (FPP) multiport control, using the soft-switching SST (S4T) with reduced conduction loss as an example. Comparative experimental results based on a SiC three-port S4T prototype verify the effectiveness of the proposed PPP scheme against the FPP scheme under both steady state and dynamic conditions. The dc-link current reduction is measured to be more than 36%. Significantly, the proposed multiport PPP control scheme is generic and applicable to any hard-switching or soft-switching CS SSTs without extra hardware.
Original language | English |
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Pages (from-to) | 2606-2616 |
Number of pages | 11 |
Journal | IEEE Transactions on Power Electronics |
Volume | 38 |
Issue number | 2 |
DOIs | |
State | Published - Feb 1 2023 |
Keywords
- Battery energy storage system (BESS)
- current-source converter (CSC)
- current-source inverter (CSI)
- differential power processing (DPP)
- distributed renewable energy resource
- electric vehicle (EV)
- medium-frequency transformer (MFT)
- mod-ulation
- photovoltaic (PV)
- power electronic transformer (PET)