Bidirectional Operation of the Power Electronic Interface for Nearly-Zero Energy Buildings

Nearly-zero energy buildings (NZEB) are buildings with extremely efficient energy usage and local energy generation capability. By the definition, the annual net energy consumption of NZEB should be zero, which can be achieved via a flexible energy management system (EMS). This paper proposes an EMS based on a bidirectional power electronic interface (PEI). The proposed PEI can have a variety of functions at the PCC, e.g., ancillary services, load DSM, on/off-grid operation mode, power quality control. As a result, the NZEB transforms into a hierarchically controlled nanogrid, which forms a small independent building block of the future microgrid. Synchronous and asynchronous operations of the NZEB were studied and the bidirectional energy flow control is demonstrated. The functionality and control strategies of the proposed PEI were verified by the computer simulations.