Day-ahead optimized dispatching system and method for gas-steam combined cycle unit

The invention discloses a day-ahead optimized dispatching system and method for a gas-steam combined cycle unit. The day-ahead optimized dispatching system comprises a dispatching control system, a gas turbine system, a waste heat boiler system and a steam turbine system, wherein the gas turbine system is connected with the waste heat boiler system and the steam turbine system, and the dispatching control system is respectively connected with the gas turbine system, the waste heat boiler system and the steam turbine system. According to the day-ahead optimized dispatching system and method for the gas-steam combined cycle unit, a day-ahead optimized running model of a gas-steam combined cycle power generation system is established, and the rated condition of the gas-steam combined cycle unit is acquired, so that the safe and economic operation of the combined cycle system is ensured; and operating parameters under a large quantitative variation condition are obtained through linear interpolation, the established model is solved in an economic dispatching mode to obtain an optimized dispatching scheme of the day-ahead optimized operation of a gas turbine, and the minimum power generation quantity and the maximum power generation quantity of the unit when the profit reaches the preset maximum are given by adopting a mixed integer programming algorithm according to a target and a constraint condition.