Interaction of combined cycle power plant (CCPP) and power system at two levels of performance optimization

In this paper, considering two different scenarios, combined cycle power plant was optimized to reduce total system costs. In the first scenario, parameters of combined cycle power plant were optimized based on power system constraints. But, in the second scenario, they were optimized considering constraints of the power plant. Cost function of power plants includes consumable fuel price (natural gas), maintenance and repair cost and exergy destruction cost, which was fitted with a quadratic equation in this investigation. In both scenarios, combined cycle power plants were optimized by genetic algorithm based on two objective functions of total exergy efficiency of power plant and price function of generated power. The results obtained from these two scenarios showed that the second scenario introduced more optimized cost function than the first one. As a result, calculating cost function of power plant apart from the power system reduced costs of combined cycle power plant and total system and applying constraints of the power system to power plants discharged them from their optimized function and increased the costs.