Centralized Energy Management Scheme for Grid Connected DC Microgrid

Abstract

Energy management in DC microgrid is complex and challenging due to the stochastic nature of renewable energy sources and load demand. Coping with the deficit power, peak demand, and power converter control operations are a few major concerns. The photovoltaic (PV) system and battery energy storage system (BESS) utilization need special attention for the reliable and efficient operation of the DC microgrid. Hence, this article proposes the centralized energy management scheme (CEMS) in the DC microgrid to address the abovementioned challenges. The CEMS coordinates among the various physical layer components and computational layer (i.e., control layer) of the DC microgrid. It utilizes the multioptimization for energy management during the peak and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -peak load demand, optimal usage of PV-BESS, and performs the optimal load shedding operation. Furthermore, an optimal utilization of the PV-BESS problem is formulated and solved using linear programming to avoid excess usage of AC grid power. In deficit PV power, the optimal load shedding operation is formulated as mixed-integer linear programming problem to ensure the DC bus voltage regulation and power balance. The proposed CEMS demonstrates the effective operation of the PV system in maximum power point tracking, <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> -MPPT mode (i.e., voltage control), and BESS's charging/discharging operation. It is showcased that the hierarchical control structure of CEMS improves the performance, efficiency, and reliability of the DC microgrid operation. Hence, a 48 V and 1.2 kW PV-BESS-based DC microgrid system is developed to show the efficacy of the proposed algorithm under different scenarios in MATLAB/Simulink. The real-time simulator results of the developed system, obtained using OPAL-RT OP4510, confirmed the effectiveness and reliability of the proposed scheme.