A combustion control device for a gas turbine which is fitted to a gas turbine provided with a gas turbine body, a combustor having multiple types of fuel nozzles, a compressor installed with an inlet guide vane, and multiple fuel flow rate control valves for respectively controlling fuel supplies to the multiple types of the fuel nozzles, the combustion control device being configured to control the fuel supplies to the multiple types of the fuel nozzles by controlling apertures of the fuel flow rate control valves, the combustion control device comprising:
- gas turbine output computing means for computing a first gas turbine output corresponding to a first combustion gas temperature at an inlet of the gas turbine, a second gas turbine output corresponding to a second combustion gas temperature at the inlet of the gas turbine being higher than the first combustion gas temperature at the inlet of the gas turbine, and a fourth gas turbine output corresponding to a fourth combustion gas temperature at the inlet of the gas turbine being lower than the second combustion gas temperature at the inlet of the gas turbine according to an intake-air temperature of the compressor and an aperture of the inlet guide vane;
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- combustion load command computing means for computing a combustion load command value to render the combustion gas temperature at the inlet of the gas turbine dimensionless by linear interpolation according to the second gas turbine output, the fourth gas turbine output and a measured gas turbine output,
- wherein the combustion control device controls the fuel supplies to the multiple types of the fuel nozzles by determining ratios of fuels to be supplied respectively to the multiple types of the fuel nozzles according to the combustion load command value computed by the combustion load command computing means, and by controlling apertures of the fuel flow rate control valves according to the ratio of the fuels, and
- the combustion control device for a gas turbine comprises a gas turbine output learning circuit comprising:
- means for computing a first exhaust gas temperature corresponding to a measured pressure ratio according to a first characteristic curve representing a relation between the pressure ratio of the compressor and an exhaust gas temperature of the gas turbine body when a combustion gas temperature at an inlet of the gas turbine is adjusted to the first combustion gas temperature at the inlet of the gas turbine;
- means for computing a second exhaust gas temperature corresponding to a measured pressure ratio according to a second characteristic curve representing a relation between the pressure ratio and the exhaust gas temperature when the combustion gas temperature at the inlet of the gas turbine is adjusted to the second combustion gas temperature at the inlet of the gas turbine;
- means for computing a third combustion gas temperature at the inlet of the gas turbine corresponding to the measured pressure ratio and a measured exhaust gas temperature by linear interpolation according to the first combustion gas temperature at the inlet of the gas turbine, the second combustion gas temperature at the inlet of the gas turbine, the first exhaust gas temperature, the second exhaust gas temperature, and the measured exhaust gas temperature;
- means for computing a third gas turbine output corresponding to the third combustion gas temperature at the inlet of the gas turbine by linear interpolation according to the first gas turbine output corresponding to the first combustion gas temperature at the inlet of the gas turbine and the second gas turbine output corresponding to the second combustion gas temperature at the inlet of the gas turbine, which are computed by the gas turbine output computing means, the first combustion gas temperature at the inlet of the gas turbine, the second combustion gas temperature at the inlet of the gas turbine, and the third combustion gas temperature at the inlet of the gas turbine;
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- means for correcting the first gas turbine output and the second gas turbine output used for computation of the third gas turbine output so as to match the third gas turbine output with the measured gas turbine output by comparing the third gas turbine output with a measured gas turbine output and,
- wherein the second gas turbine output corrected by the gas turbine output learning circuit is used for computation of the combustion load command value by the combustion load command value computing means.