Integration of fuel cells and supercapacitors in electrical microgrids: Analysis, modelling and experimental validation

• Sizing of a hybrid storage system comprising a hydrogen and supercapacitor based sub-system for use in a microgrid.
• Fuel cell characterisation and modelling and corresponding experimental validation.
• Supercapacitor characterisation and modelling and corresponding experimental validation.
• Direct coupling of the fuel cells to the supercapacitors and performance analysis based on a microgrid experimental data.

This article examines a hybrid storage system comprising fuel cells (FC) and supercapacitors (SC) for an electrical microgrid located in the Renewable Energies Laboratory at the Public University of Navarre. Firstly, the hybrid storage system size was determined based on an energy and frequency analysis of real data for the electrical power generated and consumed in the microgrid over the course of a year in operation. This was followed by the experimental characterisation of the electrical behaviour of the FCs and SCs, in steady-state and dynamic modes of operation. Furthermore, an electrical model was developed for the FCs and another for the SCs, both of which gave satisfactory results in the experimental validations. Finally, a study was made of the storage system, comprising four 1.2 kW proton exchange membrane fuel cells (PEMFC) and three SCs of 83.3 F and 48.6 V each, in a real microgrid operating environment. Specifically, a comparison was made between the storage system solely comprising FCs and the hybrid storage system formed by a combination of FCs and SCs. The hybridisation of the FCs and SCs resulted in a complete, high-capacity energy storage system, to guarantee supply even in those months with low renewable energy resources and, in turn, able to provide the fast dynamic responses regularly required by supply and demand in the microgrid.