Limited Energy Reservoirs: analysis of the proposed methodology for opening Frequency Containment Reserve to energy storage in EU

EU Network Codes are encouraging power system operators to integrate nonconventional generation units in the evolving Ancillary Services Markets. Article 156 of System Operation Guidelines requests TSOs to perform a cost-benefit analysis for defining a minimum delivery time period for Frequency Containment Reserve (FCR) provided by units with Limited Energy Reservoirs (LER). A research group in Politecnico di Milano followed the process closely cooperating with ARERA, the Italian Regulatory Authority. This paper aims at describing in depth the methodology proposed by TSOs for analyzing system costs related to the introduction of a certain share of LER among FCR providers. Some qualitative and quantitative investigations are then proposed. Critical aspects of the methodology proposed by TSOs are described. The impact on energy storage of the differences among countries' way of providing FCR is highlighted.