Implementation of Control Strategies for Energy Storage Systems and Interlinking Converters in an Interconnected Hybrid Microgrid System for Optimal Power Management Using OPAL-RT

The interconnection of multiple microgrids (MGs) is gaining popularity due to its reliability, flexibility, and ability to handle the uncertainty of renewable energy sources. A proper control structure with robust and reliable control strategies is required to improve the interconnected microgrid's (IMG) performance concerning power sharing, power quality, and stability. Therefore, this paper presents a control structure for power flow control among interconnected hybrid microgrids (HMGs), with particular emphasis on the control strategies of three converters: the energy storage system (ESS), the HMG's interlinking converter (ILC), and the IMG's interconnecting converter (IC). Firstly, a V-f droop control-based ILC control strategy is designed to attain power sharing between AC and DC MGs in HMG while regulating both AC and DC voltages. Secondly, the control strategy of ESS combines a virtual inertia concept with a state of charge-based management to manage charging and discharging according to the IMG power flow and operating modes. Finally, the control strategy of a parallel IC structure based on double-loop voltage control is proposed to interconnect and control the power sharing and DC voltages of HMGs. The IMG system is designed in MATLAB/Simulink, and the performance is validated using the OPAL-RT simulator-based real-time software-in-the-loop simulation technique. The results indicate that the control structure, with three control strategies, ensures reliable performance in all modes and also maximizes power supply security.