Wind-thermal unit commitment with mixed-integer linear EENS and EEES formulations

In this work, day-ahead wind-thermal unit commitment (WTUC) undertaken by an independent system operator (ISO) in deregulated power systems is investigated. Expected energy not served (EENS) and expected energy excess served (EEES) of the system due to the unavailability of thermal generators as well as output uncertainties of wind generators are evaluated. The presented non-linear EENS and EEES are further formulated as linear functions of the integer and continuous decision variables in the unit commitment problem for computation efficiency. Three alternative criteria are proposed for the determination of upward and downward spinning reserve requirements of the system, which are the probabilistic criteria, the cost-benefit optimization criteria, and the hybrid criteria. The WTUC is modeled as mixed-integer linear programming (MILP) problem, and solved using available MILP techniques. The WTUC formulations have been tested on a 26-generator system which has 3 wind generators with associated transmission networks. The simulation results with the three alternative spinning reserve determination criteria are discussed.