Method and system to increase gas turbine engine durability

1. A method of operating a gas turbine engine, said method comprising:

adjusting a first stage turbine nozzle assembly to a first position;

comparing a firing temperature to a threshold value and determining a difference value therefrom;

determining that the difference value exceeds the threshold value; and

adjusting the first stage turbine nozzle assembly to a second position such that the firing temperature is substantially equal to the threshold value when the difference value exceeds the threshold value.

2. The method in accordance with claim 1 , wherein adjusting the first stage turbine nozzle assembly to the first position comprises adjusting the first stage turbine nozzle assembly to a minimum flow area for a fluid flow.

3. The method in accordance with claim 2 , wherein adjusting the first stage turbine nozzle assembly comprises rotating a turbine nozzle vane of the first stage turbine nozzle assembly to a first turbine angle position.

4. The method in accordance with claim 3 , wherein adjusting the first stage turbine nozzle assembly to a second position comprises rotating the turbine nozzle vane to a second turbine angle position to increase mass flow through the gas turbine engine, wherein the second turbine angle position is different than the first turbine angle position.

5. The method in accordance with claim 2 , wherein adjusting the first stage turbine nozzle assembly to the first position comprises rotating an inlet guide vane of an inlet assembly to a first inlet angle position.

6. The method in accordance with claim 5 further comprising rotating the inlet guide vane to a second inlet angle position to increase mass flow through the gas turbine engine, wherein the second inlet angle position is different than the first inlet angle position.

7. A method of operating a gas turbine engine, said method comprising:

operating the gas turbine engine at a first condition to generate a first power output;

comparing a firing temperature to a threshold value and determining a difference value therefrom;

determining that the difference value exceeds the threshold value; and

derating the first power output of the gas turbine engine to a second power output, wherein the gas turbine engine is operated at a second condition such that the firing temperature is substantially equal to the threshold value when the difference value exceeds the threshold value.

8. The method in accordance with claim 7 , wherein comparing the firing temperature to t threshold value comprises comparing the firing temperature to a conditional threshold value and determining a first difference value therefrom, wherein the conditional threshold value is based on the first condition of the gas turbine engine, and comparing the firing temperature to a maximum threshold value and determining a second difference value therefrom, wherein the threshold value is a maximum firing temperature rating of the gas turbine engine.

9. The method in accordance with claim 8 further comprising:

determining that the first difference value is less than the conditional threshold value; and

adjusting the firing temperature such that the firing temperature is substantially equal to the conditional threshold value when the first difference value is less than the conditional threshold value.

10. A system for operating a gas turbine engine, said system comprising:

a gas turbine engine comprising a first stage turbine nozzle assembly; and

a controller configured to control operation of said gas turbine engine, said controller comprising a processor programmed to:

adjust said first stage turbine nozzle assembly to a first position;

compare a firing temperature to a threshold value and determine a difference value therefrom;

determine that the difference value exceeds the threshold value; and

adjust said first stage turbine nozzle assembly to a second position such that the firing temperature is substantially equal to the threshold value when the difference value exceeds the threshold value.

11. The system in accordance with claim 10 , wherein said gas turbine engine further comprises a turbine nozzle vane coupled to said first stage nozzle assembly and a first actuator coupled to said turbine nozzle vane, wherein said first actuator is configured to adjust a rotation angle of said turbine nozzle vane.

12. The system in accordance with claim 11 , wherein the processor is further programmed to adjust said first stage turbine nozzle assembly by actuating said first actuator to rotate said turbine nozzle vane to a first turbine angle position.

13. The system in accordance with claim 12 , wherein the processor is further programmed to adjust said first stage turbine nozzle assembly by actuating said first actuator to rotate said turbine nozzle vane to a second turbine angle position to increase mass flow through said gas turbine engine, wherein said second turbine angle position is different than said first turbine angle position.

14. The system in accordance with claim 10 , wherein said turbine gas engine further comprises a sensor configured to transmit an input signal to said controller.

15. The system in accordance with claim 14 , wherein said sensor comprises at least one of an exhaust gas temperature sensor, a firing temperature sensor, an inlet guide vane angle sensor, and a turbine nozzle vane angle sensor.

16. The system in accordance with claim 10 , wherein said gas turbine engine further comprises an inlet assembly comprising an inlet guide vane, and wherein said processor is further programmed to rotate the inlet guide vane to a second inlet angle position to increase mass flow through said gas turbine engine.

17. The system in accordance with claim 16 , wherein said gas turbine engine further comprises a second actuator coupled to said inlet guide vane, wherein said second actuator is configured to adjust a rotation angle of said inlet guide vane.