A comparative study of lithium-ion battery and Pb-acid battery-supercapacitor hybrid energy storage system for frequency control and energy management of islanded microgrids.

Among a variety of storage technologies used for energy storage systems, supercapacitors, Pb-Acid Batteries (PABs), and Lithium Batteries (LBs) are widely used for microgrid applications. The supercapacitors with high-power density are suitable for fast power regulations; conversely, the PABs have high-energy density, which makes them suitable for long-term energy management. Since the PABs and supercapacitor can complement each other and overcome mutual defficiencies, their combination as a hybrid energy storage system can be beneficial. However, the LB enjoys both high-energy and high-power densities. Therefore, an LB ESS (LBESS) can similarly function like a Pbacid battery-Supercapacitor Hybrid ESS (PSHESS). However, their topologies, life cycles, and costs are different. This study tends to determine the one which is technically and economically more suitable for applications in islanded microgrids. For this purpose, a frequency control and energy management scheme is proposed. It maintains the balance between demand and supply and also keeps the microgrid frequency within safe operational limits using the least needed sizes for the energy storage systems. Using the simulation results, the sizes and costs of the energy storage systems are determined. For a decade of operation, the PSHESS has incurred almost 49.2% more cost than the LBESS, which makes the LBESS more cost effective. [ABSTRACT FROM AUTHOR]