Identification of AdvantagesConnected to Aggregation of SeveralBattery Energy Storage Systems

Abstract: In this study, an examination regarding what benefits an aggregatedpopulation of Battery Energy Storage Systems (BESSs) could result incompared to when the individual units in the population are being usedseparately has been executed. The increased flexibility and reducedsafety margins as results of the aggregation was also examined. Thestudy was executed on behalf of the smart energy service companyCheckWatt AB and the study furthermore rests upon results of earlierperformed master theses on behalf of the company. By investigating previous work and studies through a literature study,the enabling of anumerical study was done. The numerical study wasbased on a simple model of a Virtual Power Plant (VPP) where severalBESSs are smartly controlled in order to be used for both local peakshaving and as common providers of the frequency reserve FrequencyContainment Reserve - Normal (FCR-N). The study involved the formation of a numerical model which simulated cases of both aggregated and non-aggregated populations of up to 45 load profile units, this in order for advantages and differences to be distinguished. The data used inthe simulations was received mainly from the CheckWatt AB andconsisted of photovoltaic (PV) electricity production and load data of 45 customers of the company. A sensibility analysis of the numericalstudy was also performed, which showed that the studied model andsystem were quite stable. The results of the simulations of the case of the study proved thatthere are some advantages connected to aggregation of several BESSs,and that the aggregation enabled an added value and a higher level offlexibility within the system. The safety margins connected todelivery of FCR-N could be reduced when aggregating several BESS,while a more extensive study is requested regarding safety marginsconnected to peak shaving. The study’s results further showed that anaggregator can be used as a sustainable and flexible solution forbalancing the electrical grid in the transition to a sustainableenergy system allowing a higher penetration of intermittentenergy sources.