Design choices for combined cycle units and profit-based unit commitment

The new electricity market paradigm pushes the generation companies to profit as much as possible in the competitive scenario. One relevant issue faced by generation companies is the commitment of the units, the scheduling of them over a daily (or longer) time frame. The unit-commitment results strongly depend on the plant operational generation costs, which in turn depend on the choices taken at the design stage. Then, design technical choices should also aim at determining the best generation cost structure of generating units with respect to present and future market opportunities. The paper analyzes the relevance of some design choices (structure, size, regulation type) on the economics of the operation of gas–steam combined cycle generating units. In particular, attention is focused on the unit-commitment problem, assuming simple representations of both the configuration of the plant and of the market. Numerical examples are developed which clearly show the sensitivity of the unit commitment solutions to the market conditions and to the design choice about the regulation of the units.