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DOE OSTI · 1894260

Current-Source Solid-State DC Transformer Integrating LVDC Microgrid, Energy Storage, and Renewable Energy Into MVDC Grid

Zheng, Liran·Kandula, Rajendra Prasad·Divan, Deepak
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Abstract

Solid-state DC transformer to integrate low-voltage DC (LVDC) microgrid, wind turbine (WT) generator, photovoltaic (PV), and energy storage (ES) into medium-voltage (MV) direct-current (MVDC) distribution grids is attractive. This paper proposes current-source DC solid-state transformer (SST) for MVDC collection system in WT, PV, and ES farms or as an interface between the MVDC grid and the LVDC microgrid. Compared to conventional current-source converter (CSC) based SSTs, a switch reduction scheme on reverse-blocking device bridges is proposed to reduce device count and the number of devices on the DC-link current path. Importantly, the proposed switch reduction scheme is generic and can be applied to the DC ports of DC-AC, AC-DC, or DC-DC hard-switching or soft-switching CSC-based SSTs. Based on this scheme, the proposed current-source DC SSTs are derived, which have reduced electrolytic-capacitor-less DC-link. The proposed DC SSTs also achieve single-stage isolated DC-DC or DC-AC conversion, full-range zero-voltage switching (ZVS) for main switches, zero-current switching (ZCS) for resonant switches, and controlled dv/dt. The proposed DC SSTs, operating principles, predictive control method, the ZVS, and the controlled dv/dt under voltage buck-boost ranges are verified with MV simulations and an experimental prototype based on SiC MOSFETs, diodes, and a nanocrystalline transformer.

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14 SOLAR ENERGY17 WIND ENERGY24 POWER TRANSMISSION AND DISTRIBUTION25 ENERGY STORAGE32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION42 ENGINEERINGCurrent-source inverter (CSI)DC transformer (DCT)high-frequency link (HFL)input-series output-parallel (ISOP)isolated bidirectional dc-dc converter (IBDC)medium-frequency transformer (MFT)power electronic transformer (PET)renewable energy integrationsoft-switching solid-state transformer (S4T)

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Zheng, Liran, Kandula, Rajendra Prasad, Divan, Deepak. 2021-08-04. Current-Source Solid-State DC Transformer Integrating LVDC Microgrid, Energy Storage, and Renewable Energy Into MVDC Grid. https://doi.org/10.1109/tpel.2021.3101482

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