Abstract
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.
Highlights
With the gradual depletion of fossil fuel, the increasing environmental pollution, and the large-scale development of distributed energy, the existing grid infrastructure becomes inadequate to meet the future needs of development, which makes the energy internet come into being
Based on the mentioned considerations, this paper proposes a novel Power electronic transformers (PETs) that is applicable for an AC/DC hybrid distribution network
The isolation stage applies a combined connection of input-series output-series (ISOS) and input-series output-parallel (ISOP), which effectively reduces the amount of DC/DC modules used, increases the flexibility of access to AC/DC distribution networks of multi-voltage levels, and improves economic benefits
Summary
With the gradual depletion of fossil fuel, the increasing environmental pollution, and the large-scale development of distributed energy, the existing grid infrastructure becomes inadequate to meet the future needs of development, which makes the energy internet come into being. The energy internet is supported by advanced power electronic devices, high-speed digital communication technology, and efficient distributed control technology. It aims to provide a reliable energy support system [1]. Bidirectional flow of active and reactive power can be achieved; power quality and robustness of power grid can meet the international standards of grid connections for distributed energy systems; electrical isolation between different ports can be achieved; and the operation of modular structure is reliable which improves the convenience of maintenance [3]. The isolation stage applies a combined connection of input-series output-series (ISOS) and input-series output-parallel (ISOP), which effectively reduces the amount of DC/DC modules used, increases the flexibility of access to AC/DC distribution networks of multi-voltage levels, and improves economic benefits. Due to the single-phase structure of CHB-MLI, three sets of the
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
