A novel experimental method of power smoothing using supercapacitors and hydrogen for hybrid system PV/HKT

Nowadays, the intermittent nature of renewable energy systems represents one of the most significant challenges in isolated systems, where power fluctuations can cause instability and compromise energy quality. Although hydrogen systems and supercapacitors have been widely studied in the literature, they have been less investigated as participating agents, and further research is needed in this area. This paper presents a novel power smoothing method for an off-grid system that consist of photovoltaic panels, hydrokinetic turbines, fuel cells and a hybrid storage system (hydrogen and supercapacitors). Two well-known power smoothing methods were used to generate the power signals for the new method. The main novelty is based on controlling the state of charge of the supercapacitor using the fuel cell, for the reduction of power fluctuations and efficiently hydrogen produce. First, the capacity of the renewable system is optimized using the HOMER Pro software. Then, the optimized system was used to simulate the new method proposed in Matlab-Simulink. Finally, to validate the results obtained, extensive experiments were conducted in a laboratory test bench. The results showed that the power fluctuations index was reduced by up to 50 % in the electrolyzer and 20 % in the fuel cell, with a levelized cost of electricity of 0.19 USD/kWh. Therefore, the application of the new proposed energy smoothing method significantly improves hydrogen production.