This paper improves integer coded genetic algorithm (ICGA) with some operators, to schedule the commitment states of units. ICGA technique reduces the size of chromosomes and computation time significantly. Chromosomes contain sequence of alternative sign integers which represent operation/reservation hours of the generating units. Therefore minimum up/down time can be checked directly in chromosome. This paper enhances ICGA, by using perturbation and Excessive-Power elimination operators. Mutation operator is also different from previous developed algorithms. Numerical result indicates the advantage of the proposed approach. It leads power generation dispatch problem to lower operating cost in comparison with other researches.