摘要:Coordinating the generation plan of hydrothermal power plants in a long-term period is extremely important in generation scheduling system of hydrothermal power plants. Regarding the importance of the issue, a method for optimizing the long-term operation of a combined system of hydroelectric and thermal power plants is presented in this research, in which the main system parameters, including water inlet to reservoirs of hydroelectric power plants and the energy demand of system are considered to be indefinite. The main difference of the present research from the other similar studies is its multi-purposefulness which takes not only the cost but also the flood control into account. The issue has been resolved with the help of NSGA-II and Noisy GA algorithms – two powerful algorithms in genetic algorithm –for Khouzestan utility system.