Islanding operation scheme for DC microgrid utilizing pseudo Droop control of photovoltaic system

Abstract The penetration levels of renewable energy sources, energy storage systems, and electric vehicles are increasing with the increase in the demand to solve energy and environmental issues. These distributed generators and energy storages can be efficiently managed in a DC smart grid by coordinated control. This paper proposes novel management schemes for DC systems to improve the reliability of power supply and improve the introduction ratio of renewable energy sources (RES). The proposed DC smart grid includes multiple DC microgrids. These configurations and control systems must be designed on the assumption of islanding operation of DC systems. In the islanding power system with the high penetration of RES, not only the utilization of energy storage but also load shedding and RES control is important. Hence, an efficient control strategy by using a storage battery, fuel cell and electrolyzer units, heat pump units, and a photovoltaic (PV) system is presented for stable islanding operation of DC microgrid. As the most important concept, a pseudo Droop control is proposed that utilizes the characteristics of the PV module. The pseudo Droop control enables the PV system to suppress the output power properly by using a simple control system without the maximum power estimation. Fault ride through protection for DC system is also adapted to the DC distribution lines. The performance of the proposed DC smart grid is demonstrated through MATLAB®/Simscape ElectricalTM simulations. The simulation results show that the DC microgrid can maintain stable islanding operation under the proposed management schemes when faults occur in the DC distribution lines.