Self-unit commitment of thermal units in a competitive electricity market

This paper addresses the problem a generating utility faces in order to decide which of its thermal units to start-up and to shutdown before submitting the hourly bids to a day-ahead market based on simple bids. The self-unit commitment model is formulated as a deterministic optimisation problem where the expected profit is maximised using mixed-integer linear programming techniques. When the market price cannot be considered as an exogenous variable, the authors propose to introduce, explicitly, the market behaviour by means of the expected hourly supply and demand functions. Operation costs included are fuel costs, shutdown costs and start-up costs. Temporal links as ramp constraints are also taken into account. Expected incomes considered are not only pool energy sales, but also contracts for differences and physical bilateral contracts incomes. A detailed model formulation and a numerical case are presented.