Correction system and method for gas turbine proportional droop governor

Patent metadata

Field	Value
Publication number	US-9932850-B2
Application number	US-201514612491-A
Country	US
Kind code	B2
Filing date	Feb 3, 2015
Priority date	Feb 3, 2015
Publication date	Apr 3, 2018
Grant date	Apr 3, 2018

Abstract

A method, including receiving a turbine system operating parameter. The turbine system operating parameter includes an indication of a frequency variation of an electric power system associated with the turbine system. The method includes determining a correction factor to vary the output of the turbine system according to the frequency variation, wherein the correction factor is based on a droop power response and a nominal droop power ratio. The droop power response is calculated based on a gas turbine power output and a speed-load error. The method further includes varying the output of the turbine system based at least in part on the correction factor.

First claim

The invention claimed is:

1. A system, comprising:
a droop response system configured to detect one or more operational characteristics of a turbine system as an indication of a frequency variation of an electric power system associated with the turbine system, wherein the droop response system is further configured to generate a nominal fuel flow command that adjusts fuel flow of the turbine system to control the droop response in proportion to the frequency variation; and
a proportional droop correction control system configured to:
determine a correction factor based on a droop power response and a nominal droop power ratio, wherein the droop power response is calculated based on a gas turbine power output and a speed-load error; and
generate the correction factor to apply to the nominal fuel flow command generated by the droop response system, wherein the correction factor is configured to correct the nominal fuel flow command generated by the droop response system;

wherein the droop response system is configured to determine an actual fuel flow command based at least in part on the correction factor applied to the nominal fuel flow command and to output an actual fuel flow command to control operation of the turbine.

2. The system of claim 1 , wherein the proportional droop correction control system is configured to use a gas turbine power estimation from an online model as the gas turbine power output when the turbine system in a single shaft operation.

3. The system of claim 1 , wherein the droop response correction system is configured to determine a calculated droop power ratio as the nominal droop power ratio, wherein the calculated droop power ratio is determined based on a rated gas turbine power output and a preset droop level.

4. The system of claim 1 , wherein the proportional droop correction control system is configured to use a difference between a speed-load reference and a power grid frequency as the speed-load error.

5. The system of claim 1 , wherein the proportional droop correction control system is configured to limit the correction factor within an upper limit, a lower limit, or any combination thereof, by using a clamp, and wherein the correction factor is further limited by using a rate limiter to limit the rate of change of the correction factor.

6. The system of claim 1 , wherein proportional droop correction control system is configured to monitor a load level of the turbine system by comparing a speed-load reference to a threshold value, wherein the proportional droop correction control system is configured to update the correction factor when the load level exceeds the threshold value and a set of droop conditions are met and to use a prior correction factor as the correction factor when the load level does not exceed the threshold value.

7. The system of claim 6 , wherein the set of droop conditions comprise when an enable bit is enabled, a droop permitted bit is enabled, a single shaft configuration condition is met, and a valid online model condition are met.

8. The system of claim 7 , wherein the proportional droop correction control system is configured to use the nominal droop power ratio as the droop power response when the set of droop conditions are not met.

9. The system of claim 6 , wherein the set of droop conditions comprise when an enable bit is enabled, a droop permitted bit is enabled, and a single shaft configuration condition is not met.

10. The system of claim 1 , wherein the nominal droop power ratio is divided or multiplied by the droop power response as the correction factor.

11. A method, comprising:
receiving a turbine system operating parameter, wherein the turbine system operating parameter comprises an indication of a frequency variation of an electric power system associated with the turbine system;
determining a nominal fuel flow command based on a corresponding magnitude of the frequency variation, wherein the nominal fuel flow command controls operation of the turbine system in proportion to the frequency variation;
determining a correction factor to vary the output of the turbine system according to the frequency variation, wherein the correction factor is based on a droop power response and a nominal droop power ratio, wherein the droop power response is calculated based on a gas turbine power output and a speed-load error;
determining an actual fuel flow command based at least in part on the correction factor applied to the nominal fuel flow command; and
varying the output of the turbine system based at least in part on the actual fuel flow command.

12. The method of claim 11 , comprising determining a calculated droop power ratio as the nominal droop power ratio, wherein the calculated droop power ratio is determined based on a rated gas turbine power output and a preset droop level.

13. The method of claim 11 , wherein the correction factor is determined without a generator output, megawatt sensor, or any combination thereof.

14. The method of claim 11 , comprising dividing the gas turbine power output by the speed-load error as the droop power response, wherein the speed-load error comprises a difference between a speed-load reference and a power grid frequency.

15. The method of claim 11 , comprising:
deriving a load level corresponding to a first operating parameter of the turbine system based on a speed percentage value and a frequency percentage value of the turbine system;
comparing the load level to a threshold value;
performing a hold based on the comparison, wherein the hold uses a prior correction factor as the correction factor when the load level is below the threshold value, and wherein the hold uses the correction factor when the load level is above the threshold value.

16. A non-transitory computer-readable medium having computer executable code stored thereon, the code comprising instructions to:
receive a turbine system operating parameter, wherein the turbine system operating parameter comprises an indication of a frequency variation of an electric power system associated with the turbine system;
generate a droop correction factor to apply to a response generated to vary the output of the turbine system according to the frequency variation, wherein the droop correction factor is based on a nominal droop power ratio and a droop power response, wherein the nominal droop power ratio comprises a rated gas turbine output divided by a preset droop level, and wherein the droop power response comprises a gas turbine power output divided by a speed-load error; and
vary the output of the turbine system according to the droop correction factor applied to the response.

17. The non-transitory computer-readable medium of claim 16 , wherein the instructions comprise instructions to derive an actual fuel flow command based on the droop correction factor and a nominal fuel flow command as the corrected response, wherein the actual fuel flow command is configured to actuate an actuator, and wherein the actuator is configured to control a flow of a fuel into the turbine.

18. The non-transitory computer-readable medium of claim 16 , wherein the instructions comprise instructions to divide the nominal droop power ratio by the droop power response as the droop correction factor.

Assignees

• Gen Electric

Inventors

• Chen Yuhui
• Sweet Bryan Edward
• Szepek Scott William

Classifications

• F05D2270/061

  in particular the electrical frequency of driven generator · CPC title

• F05D2220/764

  of the alternating current (A.C.) type · CPC title

• F01D21/003

  Arrangements for testing or measuring (for measuring vibrations G01H) · CPC title

• F02C9/28 Primary

  Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed (F02C9/30 - F02C9/38, F02C9/44 take precedence) · CPC title

• F05D2270/701

  proportional · CPC title