METHOD FOR OPERATING A GAS TURBINE AT PART LOAD
The invention refers to a method for controlling part load operation of a gas turbine comprising a controller wherein a load set point of the controller is greater or equal a minimum load set point. The minimum load set point depends on a hot gas temperature that is calculated based on a hot gas temperature model.
1 . A method for controlling part load operation of a gas turbine comprising a controller wherein a load set point of the controller is greater or equal a minimum load set point and wherein the minimum load set point depends on a hot gas temperature that is calculated based on a hot gas temperature model.
2 . Method according to claim 1 , wherein from the hot gas temperature a minimum hot gas temperature is subtracted and the difference between the hot gas temperature and the minimum hot gas temperature serves as an input to a controller, which switches off at least one burner and/or adjusts fuel staging parameter when the difference becomes negative and which switches on at least one burner and/or readjusts a fuel staging parameter when the difference exceeds a threshold value.
3 . Method according to claim 1 , wherein from the hot gas temperature a minimum hot gas temperature is subtracted and the difference between the hot gas temperature and the minimum hot gas temperature serves as an input to a controller, which determines a delta load based on the difference between the hot gas temperature and the minimum hot gas temperature.
4 . Method according to claim 1 , wherein a first target load is generated based on the actual power AP 0 [MW] of the gas turbine at the moment the claimed method is activated.
5 . Method according to claim 4 , wherein the minimum load set point is equal to the sum of the first target load and the delta load.
6 . Method according to claim 4 , wherein the first target load is equal to the actual power of the gas turbine minus an offset.
7 . Method according to claim 1 , wherein the hot gas temperature model depends from at least one of the following inputs:
n: rotor speed
Tamb: ambient temperature
pamb: ambient pressure
hamb: ambient humidity
VIGV: variable inlet guide vane position
m r : air split ratio
m f : fuel mass flow
WI: fuel Wobbe index
LHV: fuel low heating value
b s : burner fuel stage ratio
γ: cooling air leakage degradation rate.
8 . Method according to claim 1 , wherein the minimum hot gas temperature is adapted by comparing the CO emissions of the exhaust gas of the gas turbine with the maximum allowable CO emissions.
9 . Method according to claim 8 , wherein the minimum hot gas temperature is raised if the CO emissions are higher than the maximum allowable CO emissions.
10 . Method according to claim 8 , wherein the minimum hot gas temperature is lowered if the CO emissions are lower than the maximum allowable CO emissions.
11 . Method according to claim 1 , wherein the method is activated once a predefined activation criteria is reached.
12 . Method according to claim 11 , wherein the predefined activation criteria comprises comparing the actual hot gas temperature THG with a predefined minimum hot gas temperature.
13 . Controller of a gas turbine, operating according to claim 1 .
14 . Gas turbine comprising a controller, wherein the controller operates according to claim 1 .
15 . Gas turbine according to claim 14 , comprising at least one combustor, at least one compressor and at least one turbine.