Optimal generation scheduling for a hybrid stand-alone power system using renewable energy sources and hydrogen storage

This paper presents a novel energy management strategy (EMS) for hybrid stand-alone power generation systems powered by renewable energy sources and equipped with batteries and a hydrogen storage section. In particular, the proposed EMS defines the optimal generation scheduling of the two storage devices to minimize operating costs and maximize system efficiency. Since the achievement of the optimal EMS for stand-alone systems powered by renewable energy sources is strongly influenced by the uncertainties of solar and wind resources, a stochastic approach was adopted to deal with these uncertainties. The proposed EMS was used to evaluate the expected annual performance of a microgrid currently under construction at the Concentrating Solar and Hydrogen From Renewable Energy Sources Laboratory, in Sardinia (Italy). The study shows that the current hydrogen storage capacity of the microgrid is insufficient to meet the annual energy requirements, especially in winter months. To highlight the benefits of including weather forecasts and operating costs in the EMS, a comparative analysis with a simpler SOC-based EMS was carried out. The results of the comparative study demonstrate that the proposed EMS leads to a decrease of almost 5-10% in the annual operating costs and energy losses, especially for high values of the hydrogen storage capacity. In particular, for a hydrogen storage capacity of the studied microgrid 10 times higher than the planned one (55 Nm3), the adoption of the proposed EMS can achieve a decrease of about 10% in the annual operating costs and about 6% in the annual energy losses with respect to a conventional SOC-based EMS.