This study proposes a modeling technique for applying combined cycle gas turbines (CCGTs) to the unit commitment problem. The proposed method does not specify the turbine operation order in advance, and uses a simple and basic formula structured as mixed integer linear programming (MILP). In addition, we propose a system marginal price (SMP) calculation considering combination modeling of CCGTs, and we analyze market price change and its effect. After applying the proposed method to the unit commitment problem and calculating the market price from January 2017, although average market price and volatility increased, there was no rapid change, such as inversion of the dispatching rank of fuel sources or excessive fuel costs. And the profitability of the CCGTs participating in the day-ahead energy market improve.
