Robust flexibility driven security constrained unit commitment under wind uncertainty considering demand response and combined-cycle units

Abstract

Operational flexibility aiming to mitigate variability impacts of Renewable Energy Resources (RES) inherently depends on inter-temporal operational status. Accordingly, in the current paper, a novel operational flexibility maximization procedure is developed within a robust Security Constrained Unit Commitment (SCUC) problem to find the most tolerable flexibility band in response to RES variability impacts. In addition, combined-cycle units (CCU) and incentive based demand response, from both generation and demand sides, are considered as flexibility providers because of their specific characteristics such as high ramping capacities and fast start-up/shut-down rates. However, unlike conventional units with single mode operation, a CCU unit is composedof multiple combustion turbines (CTs) and steamturbines (STs) that can operate in different modes. Since it is needed to decide the on/off statusand power output of each CT and ST unit at every timeinterval, the recourse decision layer will be non-convex. The challenging non-convex recourse decision level is cast as a mixed-integer program that is solved by an exact nested column-and-constraint generation algorithm. The capability of the proposed model is then investigated in standard IEEE 118-bus test system.