Modeling of Battery Energy Storage Systems for System Reliability Studies

Battery energy storage systems (BESS) are increasingly being used in recent times due to the changing nature of the modern electric grid. In this paper, the utility of a BESS has been investigated for reliability improvement of the system, while performing energy arbitrage. Maximization of revenue from the energy market has been prioritized while performing energy arbitrage. A multi-state model has been developed by tracking the state of charge of the BESS. For generation adequacy assessment, the BESS states have been modeled both as generators and loads, since besides providing power to the grid while discharging, it also draws power from the grid while charging. The classification has been done depending on the SOC of the device for a particular hour. The reliability improvement has been shown in terms of the various reliability indices obtained by construction of the generation reserve model. The IEEE Reliability Test System has been used to demonstrate the validity of the proposed model. The results show significant reliability improvement of the system in presence of the BESS.