Charge evaluation of EDLC for autonomous microgrid energy storage

Electric double layer capacitor (EDLC) is now playing more and more roles in microgrids for renewable energy storage due to its characteristic merits in high charging and high energy density. Different charging modes of EDLC are mainly studied in this paper. Compared with traditional constant-voltage and constant-current charging modes, constant-power charging mode (CPCM) ranks more reasonable positions for autonomous systems. Numerical calculations were presented for practical analysis, which was validated to be accurate enough and applicable by a simple case with PV/EDLC system configuration. Charging efficiency of different charging modes was also reviewed with strict mathematic deductions. Furthermore, trade-off problems, between charging time/efficiency/energy loss, were also investigated in brief for practical optimization of application occasions. For practical applications, how to utilize and manage the relationship of shifting modes in a reasonable way can be dealt with the actual requirements.