Abstract – Unit commitment (UC) is a very significant optimization task. The unit commitment problem (UCP) involves the energy dispatch cost minimization in the competitive electric power market over a given scheduling period. In general the UCP is a large scale, nonconvex, nonlinear, mixed-integer and complex combinatorial optimization problem. A new mixed-integer linear formulation is obtained to model the unit commitment problem. Additionally to overcome the complexity of the UCP, a linearization method employed to present the equivalent linear expression of the problem. Although the unit startup and operation cost is not considered in this model by special objective function, the solution of this optimization represents a generation schedule with minimum number of unit in the given time horizon. In this paper the artificial generators are used to model loss of load in power system. This generators cause to avoid divergence in solution process. To demonstrate the efficiency of the presented method, a system as the same structure as Iranian power market is used as a case study.

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