PNNL

Abstract

This paper proposes a new framework for power system unit commitment process, which incorporates the generation flexibility requirements and environmental constraints into the existing unit commitment algorithm. The generation flexibility requirements are to address the uncertainties with large amount of intermittent resources as well as with load and traditional generators, which causes real-time balancing requirements to be variable and less predictable. The proposed flexibility requirements include capacity, ramp and ramp duration for both upward and downward balancing reserves. The environmental constraints include emission allowance for fossil fuel-based generators and ecological regulations for hydro power plants. Calculation of emission rates is formulated. Unit commitment under this new framework will be critical to the economic and reliable operation of the power grid and the minimization of its negative environmental impacts, especially when high penetration levels of intermittent resources are being approached, as required by the renewable portfolio standards in many states.