Abstract

In this study, an examination regarding what benefits an aggregated population of Battery Energy Storage Systems (BESSs) could result in compared to when the individual units in the population are being used separately has been executed. The increased flexibility and reduced safety margins as results of the aggregation was also examined. The study was executed on behalf of the smart energy service company CheckWatt AB and the study furthermore rests upon results of earlier performed 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 was based on a simple model of a Virtual Power Plant (VPP) where several BESSs are smartly controlled in order to be used for both local peak shaving and as common providers of the frequency reserve Frequency Containment Reserve – Normal (FCR-N). The study involved the formation of a numerical model which simulated cases of both aggregated and nonaggregated populations of up to 45 load profile units, this in order for advantages and differences to be distinguished. The data used in the simulations was received mainly from the CheckWatt AB and consisted of photovoltaic (PV) electricity production and load data of 45 customers of the company. A sensibility analysis of the numerical study was also performed, which showed that the studied model and system were quite stable.

The results of the simulations of the case of the study proved that there are some advantages connected to aggregation of several BESSs, and that the aggregation enabled an added value and a higher level of flexibility within the system. The safety margins connected to delivery of FCR-N could be reduced when aggregating several BESS, while a more extensive study is requested regarding safety margins connected to peak shaving. The study’s results further showed that an aggregator can be used as a sustainable and flexible solution for balancing the electrical grid in the transition to a sustainable energy system allowing a higher penetration of intermittent energy sources.