A combined cycle power generation system, the system comprising: a generator; a gas turbine permanently coupled to the generator; a steam turbine selectively coupled to the generator; a clutch configured to selectively couple the steam turbine to the generator; a controller in communication with the gas turbine, the steam turbine, and the generator; and characterised by a processor in communication with the controller and configured to: receive ambient conditions of the combined cycle power generation system; receive an engagement status of the clutch; receive a simple cycle calculation indicative of a simple cycle power plant base load at the ambient conditions; receive a combined cycle calculation indicative of a combined cycle power plant base load at the ambient conditions; based at least in part on the engagement status, select the simple cycle calculation or the combined cycle calculation; determine a base load value using the selected calculation; receive (430, 435) an actual power output of the generator at a base load condition; compute (430, 435) a calibration offset using the base load value and the actual power output, the calibration offset being a difference between the base load value and the actual power output; continuously calculate (430, 435) the base load value using the actual ambient conditions; calibrate the base load value using the calibration offset to obtain a calibrated base load, the calibrated base load being the base load value after a subtraction of the calibration offset; determine a change in the engagement status of the clutch of the power plant and; based at least in part on the determination, resetting the calibration of the base load estimation of the power plant. a generator; a gas turbine permanently coupled to the generator; a steam turbine selectively coupled to the generator; a clutch configured to selectively couple the steam turbine to the generator; a controller in communication with the gas turbine, the steam turbine, and the generator; and characterised by a processor in communication with the controller and configured to: receive ambient conditions of the combined cycle power generation system; receive an engagement status of the clutch; receive a simple cycle calculation indicative of a simple cycle power plant base load at the ambient conditions; receive a combined cycle calculation indicative of a combined cycle power plant base load at the ambient conditions; based at least in part on the engagement status, select the simple cycle calculation or the combined cycle calculation; determine a base load value using the selected calculation; receive (430, 435) an actual power output of the generator at a base load condition; compute (430, 435) a calibration offset using the base load value and the actual power output, the calibration offset being a difference between the base load value and the actual power output; continuously calculate (430, 435) the base load value using the actual ambient conditions; calibrate the base load value using the calibration offset to obtain a calibrated base load, the calibrated base load being the base load value after a subtraction of the calibration offset; determine a change in the engagement status of the clutch of the power plant and; based at least in part on the determination, resetting the calibration of the base load estimation of the power plant. receive ambient conditions of the combined cycle power generation system; receive an engagement status of the clutch; receive a simple cycle calculation indicative of a simple cycle power plant base load at the ambient conditions; receive a combined cycle calculation indicative of a combined cycle power plant base load at the ambient conditions; based at least in part on the engagement status, select the simple cycle calculation or the combined cycle calculation; determine a base load value using the selected calculation; receive (430, 435) an actual power output of the generator at a base load condition; compute (430, 435) a calibration offset using the base load value and the actual power output, the calibration offset being a difference between the base load value and the actual power output; continuously calculate (430, 435) the base load value using the actual ambient conditions; calibrate the base load value using the calibration offset to obtain a calibrated base load, the calibrated base load being the base load value after a subtraction of the calibration offset; determine a change in the engagement status of the clutch of the power plant and; based at least in part on the determination, resetting the calibration of the base load estimation of the power plant.