Market implications of reliability unit commitment formulations for Day-Ahead scheduling

Reliability Unit Commitment (RUC) is a process by which Independent System Operators (ISOs) commit generation capacity to ensure reliability is maintained for forecasted demand levels. Typically, this process is performed sequentially, where the RUC follows a Day-Ahead Market (DAM) closing to procure additional capacity when the total system demand in the market closing is below forecasted levels. The RUC stage of this process chooses generation commitment decisions that minimize the startup and minimum-load cost components necessary to meet the additional demand requirements. This two-stage approach produces suboptimal solutions for this forward market. An alternative approach is to integrate the DAM and RUC processes such that resources are procured and scheduled simultaneously. In this paper, a model has been developed to compare the two stage (DAM-RUC) formulation and an integrated approach in order to investigate market impacts associated with each structure.