Sizing of Hybrid Energy Storage Systems for Frequency Response of Solar Farms in Ecuador

The increasing penetration of renewable generation for decarbonising the power sector leads to important techno-economic challenges for grid-stakeholders. Many Latin American countries are already fed from high-levels of renewable sources which requires innovative measures for maintaining the stability and safety of their systems. Solar Farms, in particular, present a unique behaviour with fluctuating and stochastic energy during daylight and null-generation during the night. The present paper explored the feasibility of using Solar Farms in combination with hybrid energy storage systems (HESSs) for the provision of Frequency Response based on a Sizing Methodology. This method considers different energy markets as revenue routes and determines the optimal sizing of the storage devices for achieving the highest profit while meeting grid-regulations. A deterministic case study based on 18-years solar data from Ecuador was developed with a 50MW Solar Farm and a HESS composed of multiple storage technologies. The Solar Farm system was tested under three cases: 1) with HESS 2) with a single storage device and 3) with non-storage technologies. The model was solved through Linear Programming as the stochastic behaviour of solar generation was out of the scope of this work. The results showed that the use of Solar Farms with HESS reached the highest revenue among other cases for providing frequency support and using the proposed power and energy ratings on each device. These outcomes indicate that the Solar Farm did not compromise the methodology under this study deterministic conditions and it might have the potential to work in conjunction with other energy storage technologies for the provision of frequency support under certain conditions. Further studies will be carried out considering the probabilistic differences between solar and wind generation.