A method of controlling variable extraction flow in a
combustion turbine engine, wherein extraction flow comprises a supply of
compressed air extracted from the compressor and supplied to the
turbine through extraction conduits, and wherein the extraction conduits includes a variable extraction orifice, the method comprising the steps of: measuring a plurality of
turbine engine operating parameters; monitoring, by a
control unit, the measured operating parameters of the
combustion turbine engine; setting the variable extraction orifices to a setting that allows an approximate
maximum level of extraction flow; calculating, by the
control unit, at least one calculated operating parameter based upon model-based control and the measured operating parameters, including at least a current turbine
inlet temperature and a maximum turbine
inlet temperature; and manipulating the setting for the supply of fuel to the
combustor such that an increased and / or
maximum level of engine output is determined by comparing the values for the current turbine
inlet temperature and the maximum turbine inlet temperature.