Environmentally constrained unit commitment

The authors present a short-term unit-commitment algorithm. They include a new function for managing SO₂ emissions from fossil-fuel-fired generating units. The method uses a Lagrangian-relaxation-based algorithm which offers a new approach for the commitment of realistically sized systems. Emission is considered as a second objective function and is added to the main objective function with a weighting factor. Generation, reserve, fuel and environmental constraints are incorporated into the main objective function. Individual-unit constraints such as must-run status, ramp-rate constraints and minimum up- and down-time constraints are considered. Unit-startup cost is represented as a function of down-time. The algorithm is tested on a 17-unit system for a time horizon of 24 hours with one-hour steps