The Impact of the Electric Double-Layer Capacitor (EDLC) in Reducing Stress and Improving Battery Lifespan in a Hybrid Energy Storage System (HESS) System

This paper investigates the effect of the electric double layer capacitor (EDLC) in reducing stress and prolonging the battery lifespan in a hybrid energy storage system (HESS). A 65 F, 16.2 V EDLC supercapacitor was connected in a laboratory experiment to produce its charge/discharge profile at a constant current of 5 and 10 A. The EDLC's Faranda or "two branch model" mathematical parameters were extracted from the experimental charge/discharge profile. The extracted parameters were used as inputs to design the Python/MATLAB/Simulink (PMS)-hybrid model of the EDLC. The charge/discharge profiles of the simulated PMS model of the EDLC were then compared to the charge/discharge profiles derived from the experimental setup of the EDLC and were found to match. The PMS model of the EDLC was then used as a subcomponent in an HESS system modelled in MATLAB/Simulink. Using constant load conditions, the battery's voltage, current, power and state of charge (SOC) were analyzed for a battery energy storage system (BESS) without a supercapacitor and then compared to an HESS system with a supercapacitor in an experimental setup. This process was repeated with the simulated PMS model of the EDLC in MATLAB/Simulink for HESS and without the EDLC for BESS. Finally using a variable load in an experimental setup, the battery's voltage and current were analyzed for a BESS system and compared to an HESS system. All these data show that, in an HESS system with a supercapacitor, there is less stress on the battery with a load applied. This is indicated by the voltage and current values in an HESS system being consistently more stable with respect to time as compared to the BESS system. As a result, in an HESS system, the battery will have a longer lifespan.