“…Many deterministic methods have been utilized for the solution of the UC problem, such as Lagrangian rylaxation [ 11-[4], mixed-integer programming [5] and dynamic programming [6]. In addition to the above, there are meta-heuristic methods, such as genetic algorithms [7], simulated annealing (SA) [SI- [ lo], hybrid algorithms, which combine SA with other methods [11]- [13], and the ant colony search algorithm [14]. The main advantage of these methods is their ability to come up with very good solutions, while they can easily deal with difficult nonlinear constraints.…”