Scheduling of thermal units with a nonlinear load flow network model

We describe a formulation of the thermal unit commitment problem that inclu des AC network constraints, which allows taking into account VAr production as a criterion for generator commitment for the first time. The formulatio n makes it possible to use the Lagrangian Relaxation technique as a solutio n algorithm even though the network constraints are not linear. Although th e solution method is computationally intensive, the problem exhibits a sepa ration structure and a price coordination schedule that suggest several way s of improving the performance. Preliminary test results are reported. (C) 1999 Elsevier Science B.V. All rights reserved.