Towards Accurate Modeling on Configuration Transitions and Dynamic Ramping of Combined-Cycle Units in UC Problems

In recognizing significant advantages in achieving carbon emission reduction and mitigating variability of renewables, an increasing installation of combined-cycle (CC) units has been observed recently. This new shift in the generation portfolio has urged Independent System Operators (ISO) to continuously enhance CC unit models in their unit commitment (UC) tools, in order to derive physically feasible and operationally reliable unit commitment and generation dispatch schedules of CC units by accurately capturing their operation features. To this end, this paper accurately simulates startup and shutdown processes of individual turbines of a CC unit during the configuration transition procedure. A dynamic ramping model and the corresponding spinning reserve model for individual turbines are also proposed to further enhance the modeling accuracy. A modified IEEE 118-bus system with multiple CC units is adopted to evaluate the proposed models.