Accurate modeling of combined-cycle power plants is an increasingly important part of more efficient operations of restructured power systems. This paper aims to enhance the existing standard modeling of combined-cycle power plants in real-time generation control, planning and scheduling applications of Energy Management Systems (EMS) and Energy Market Management Systems (MMS). The proposed configuration-based model handles the various operation modes (configurations) of combined-cycle plants such as simple cycle, combined-cycle, power augmentation, additional boiler, etc. Some of the advantages of the proposed model over the standard model are discussed. Numerical examples are given to illustrate the concept and the effectiveness of the proposed configuration-based combined-cycle modeling.