The operation system of Power Plant (PLTU) required a special attention. This is because the convention of energy is quite long. The load changes in the power plant also should be followed by the arrangements that automatically alter the settings of enthalpy flow, calorie flow, fuel flow, and air flow which are work together through the control system. The existence of a long process of energy conversion in PLTU causing the ability of PLTU to deal with the load changes in the system are depends on the amount of energy storage, such as the capacity of the combustion chamber and the capacity of the kettle drum. The delaying process in PLTU to cope with the load changes lead to waste of fuel, which can affect the efficiency of the power plant.