Research on the Structure and Control Strategy of a Novel Power Electronic Transformer for AC/DC Hybrid Distribution Network
1
State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Beijing 102206, China
2
China Electricity Council, Beijing 100761, China
*
Author to whom correspondence should be addressed.
Appl. Sci. 2019, 9(4), 727; https://doi.org/10.3390/app9040727
Received: 23 January 2019 / Revised: 14 February 2019 / Accepted: 16 February 2019 / Published: 19 February 2019
(This article belongs to the Special Issue Emerging Power Electronics Technologies)
Power electronic transformers (PETs), as the core devices of the energy internet, are the key to achieve both effective consumption for renewable energy and the safe and coordinated operation for AC/DC hybrid system. In order to overcome the shortcomings of the existing PETs, a novel PET with an improved structure that applicable for multi-voltage level AC/DC hybrid distribution network is proposed. The topology of the proposed PET is analyzed, and the corresponding control methods are suggested for different parts. The input stage utilizes the modular multilevel converter structure and applies the virtual synchronous machine control strategy to enhance the inertia and damping of the system. The power of the output stage is adjusted flexibly and that enables the PET to provide certain power support to the upper grid and participate in its primary frequency regulation. A combined connection of input-series output-series and input-series output-parallel is applied for the dual-active-bridge modules of the isolation stage to enable network interconnection and electrical isolation of AC/DC grids with significantly different voltage levels. A power coordinated control method is then proposed to meet the power demand of the distribution networks connected to the output stage and ensure stable operations of PET simultaneously. The reliability and efficiency of the proposed PET topology and control strategy for AC/DC hybrid distribution network are finally verified via PSCAD/EMTDC simulation.
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Keywords:
power electronic transformer; modular multilevel converter; virtual synchronous machine; input-series output-series; power coordinated control
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MDPI and ACS Style
Rong, J.; Ai, X.; Li, Y.; Ren, D. Research on the Structure and Control Strategy of a Novel Power Electronic Transformer for AC/DC Hybrid Distribution Network. Appl. Sci. 2019, 9, 727. https://doi.org/10.3390/app9040727
AMA Style
Rong J, Ai X, Li Y, Ren D. Research on the Structure and Control Strategy of a Novel Power Electronic Transformer for AC/DC Hybrid Distribution Network. Applied Sciences. 2019; 9(4):727. https://doi.org/10.3390/app9040727
Chicago/Turabian StyleRong, Jingguo; Ai, Xin; Li, Yunning; Ren, Dapeng. 2019. "Research on the Structure and Control Strategy of a Novel Power Electronic Transformer for AC/DC Hybrid Distribution Network" Appl. Sci. 9, no. 4: 727. https://doi.org/10.3390/app9040727
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