A distributed energy management system of autonomous DC microgrid in office buildings based on DC bus signaling

With the development of renewable energy, the character of building energy system gradually transitions from electricity consumer to an integrated role that considers both consume and supply side. Abundant flexible resources within the buildings remain to be exploited and utilized. This paper proposes a distributed energy management system of DC microgrid in office buildings based on DC bus signaling. The system enables to control decentralized terminals in office buildings including photovoltaic (PV), battery, un-shiftable load (UL), thermostatically controlled load (TCL), and electric vehicle (EV). The DC bus voltage is regulated in real-time according to the difference between actual grid power and the grid requirement power, which is arranged as a constant power curve in this paper to grid relief. The viability and effectiveness of the proposed system are validated by the simulation results. The DC bus voltage is varied dynamically and the power of utility grid is almost the same as the demand power. In addition, the impact of terminal capacity and arranged control sequence with the proposed strategy are analyzed and evaluated. For a typical operating condition, the annual adjustment contribution of PV, battery, EV, and TCL among all the terminals take 9.3 %, 70.3 %, 19.0 %, and 1.4 %, respectively.