Performance Evaluation between Back-to-Back Converter and DC-DC Converter for Power Sharing Between Two Interconnected Microgrids

As the voltage and frequency fluctuate concerning load or source power variations, it is necessary to maintain a predetermined nominal voltage and frequency to ensure stability and reliability in a microgrid system, particularly one that is operating in islanded mode. Nevertheless, introducing interconnection between microgrids ensures system stability and reliability by producing precise power flow management among microgrids. Hence, an infrastructure of interconnected microgrids using a back-to-back (BTB) converter has been proposed in this paper to integrate the microgrids operating in an islanded mode to maintain the prescribed limits of the system parameters, optimum power flow, and resilient operation during load fluctuation. The interconnected system with a BTB converter is designed in MATLAB/Simulink software with one converter controlled by DC-link voltage and the other by an AC voltage controller from microgrid-2 based on droop control and the system's performance is further evaluated using the OP5600-based OPAL-RT simulator. The findings demonstrate that aside from some switching losses, the proposed system incorporating a BTB converter provides effective power flow with minimal voltage and frequency fluctuations, making it a preferable choice compared to the DC-DC converter, which introduces significant ripples in power sharing and the energy storage system’s output, negatively impacting battery life.