Management of Utility-Scale Battery SOC in Grid Operations and Markets

PIs: Omer Karaduman, Simona Onori

Utility scale stationary battery storage technologies are increasingly deployed in electrical systems worldwide to help manage daily variations of renewable generation. Short duration (<10 hours) battery storage creates new challenges for power system operations and markets, especially since the state of charge of the devices must be managed to avoid hitting limits and being unable to deliver the scheduled energy and ancillary services. Several systems in the world already experience these challenges, like the CAISO system with 5 GW installed battery capacity as of 2023 and a typical peak demand about 50 GW (usually in the summer) or the Australian (NEM) system with 1.4 GW utility battery capacity and a typical peak demand of 30 GW. The batteries have a typical storage duration of 2 hours in NEM and 4 hours in the CAISO system.

This research project proposes to first study the challenges related with managing the state of charge of these batteries systems:

• Should resource owners or RTO/ISO control the state of charge of the batteries?
• What is the current experience with state of charge management in CAISO and NEM markets?
• How do different utility scale hybrid storage participation models compare?

Based on these insights, we then propose to explore new ideas to improve the operational and market design strategies and to better manage battery storage overall.