Expected Benefits of Coordinated Energy Storage Operation in Stochastic Unit Commitment with Enhanced Deliverability of Reserves

Benefits of energy storage systems (ESSs) are being investigated to figure out whether ESSs are worthwhile to install and operate. As ESSs are addressed as an effective tool to mitigate variability and uncertainty of renewable resources, measurements of their values are more emphasized. This paper examines benefits of ESSs, particularly for ESSs cooperating with solar photovoltaic (PV) or wind farms, using a stochastic unit commitment (UC) model co-optimizing energy and reserves by the ESSs with the enhanced deliverability of deployed reserves. For benefit measurements, cost savings, renewable energy generation improvements, and carbon dioxide emissions reduction are quantified and compared under the different operational conditions of ESSs. Optimal UC, energy, and upward & downward reserve schedules by the thermal generators and ESSs are provided by the proposed simulation model. The model is also designed to achieve environmental policy goals: 30% renewable energy generation and capped carbon dioxide emissions for low-carbon electricity generation. The uncertainties of renewable resources-available wind and solar DNI-and electric load are modeled as random variables, and two-stage stochastic mixed integer linear programming is applied to represent the given uncertainties in the formulation. Scenarios for random variables are generated using the autoregressive-to-anything (ARTA) process. The results show that operating the ESSs with providing downward reserves improves efficiency of UC by committing a few conventional generators and significantly increases benefits.