The influence of frequency containment reserve on the cycles of a hybrid stationary large-scale storage system
Kevin Jacqué, Lucas Koltermann, Jan Figgener, Sebastian Zurmühlen, Dirk Uwe Sauer, Journal of Energy Storage, Vol. 52, 25 August 2022.
Europe's aim of climate neutrality by 2050 places higher demands on the electricity grid due to the expansion of renewable energies with fluctuating feed-in. With their high flexibility and reaction speed, large-scale storage systems (LSS) are predestined to compensate the fluctuating feed-in from renewable energies and to support the electricity grid. For this reason, LSS are gaining importance on the market for frequency containment reserve (FCR) as well as in research. The majority of publications investigating the interaction between storage and FCR are based on simulations and, field measurements are rare. This paper presents the analyses of multi-year, high-resolution field measurements of the hybrid 6 MW/7.5MWh battery storage “M5Bat” to address this issue. This paper analyses and compares the cycles of the LSS and its individual battery technologies (two types of lead-acid and three types of lithium-ion batteries) after four years of FCR operation. An estimation of the cyclic ageing of the individual batteries is determined by referring to the equivalent full cycles (EFC) specified by the manufacturer. The data-based cycle analysis of the LSS and its individual battery technologies reveals that the participation in the reserve market exposes the storage system to a high number of cycles with a low average cycle depth of 1.69%. The EFC are small with an average of 0.278 and result in an average remaining number of EFC of the battery units after four years of 83.2%. The high number of residual cycles compared to the SOH of the battery units demonstrates the dominance of calendar ageing compared to cyclic ageing. The quality of the control software of the hybrid LSS as well as the individual battery units is decisive for the age-optimised operation of the storage system on the reserve market. The presented results can be used to investigate and model the influence of FCR operation on the ageing and state variable of the different battery technologies.
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