An integrated and reconfigurable hybrid AC/DC microgrid architecture with autonomous power flow control for nearly/net zero energy buildings

With the ever-increasing of population and economy worldwide, buildings have become major energy consumers and greenhouse gas (GHG) emitters. The hybrid AC/DC microgrid is a promising alternative for existing power distribution systems to achieve the goal of nearly/net zero energy buildings (nZEBs). However, the increasing demand for compact structure, seamless integration of distributed generators (DGs) and loads, as well as more control flexibility of hybrid microgrids cannot be adequately satisfied by conventional grid architectures. In view of this, an integrated and reconfigurable hybrid AC/DC microgrid architecture with its hierarchical control strategy is proposed in this paper. Firstly, a novel interlinking converter named smart interlinking unit (SIU) is presented, which can provide multiple AC/DC interfaces and diverse operation modes with various control functionalities. Secondly, the SIU-based hybrid microgrid architecture and its hierarchical control structure are established. The dedicated interfaces and cluster controllers for electric vehicles (EVs) facilitate the implementation of centralized vehicle-to-grid (V2G) service. Thirdly, a hierarchical control strategy of SIU, which involves local control in primary control level and power flow control in secondary control level, is introduced to realize coordinated operation of microgrid. The model of the proposed hybrid microgrid architecture is built, and the simulation results demonstrate that the microgrid architecture and hierarchical control strategy can achieve a reliable and coordinated system operation under various kinds of scenarios. Additionally, the mutual power support between AC and DC sub-grids is realized with increased utilization and local consumption of renewable energy resources (RESs).