METHOD FOR COMPENSATING FOR COMBUSTION EFFICIENCY IN FUEL CONTROL SYSTEM

• US 20120036861A1
• Filed: 08/10/2010
• Published: 02/16/2012
• Est. Priority Date: 08/10/2010
• Status: Active Grant

• Current Assignee: GE Infrastructure Technology, LLC (GE Vernova, Inc.)
• Original Assignee: General Electric Company
• Inventors: Seely, William Forrester, Hughes, Michael John
• Granted Patent: US 8,276,363 B2
• Time in Patent Office: Days
• US Class Current: 60/776
• CPC Class Codes: F02C 9/28 Regulating systems responsive to plant or ambient parameters, e.g. temperature, pressure, rotor speed F02C9/30 - F02C9/38, F02C9/44 take precedence
• CPC Class Codes: F05D 2260/821 Parameter estimation or prediction
• CPC Class Codes: F05D 2270/07 to improve fuel economy
• CPC Class Codes: F05D 2270/092 in particular blow-out and relight
• CPC Class Codes: F05D 2270/14 to control thermoacoustic behaviour in the combustion chambers
• CPC Class Codes: F05D 2270/303 Temperature
• CPC Class Codes: F05D 2270/54 by electronic means, e.g. electronic tubes, transistors or IC's within an electronic circuit
• CPC Class Codes: F05D 2270/708 with comparison tables

Abstract

Compensation is provided for a fuel demand signal of a gas turbine controller during transition between operating modes. The compensation adjusts fuel demand to account for combustion efficiency differences between the starting and ending operating mode that otherwise can lead to severe swings in combustion reference temperature and lean blowout.

Claims

1. A method of compensating for combustion efficiency in a fuel control system of a gas turbine system, including a compressor, combustors and a turbine, with a turbine control system employing a mode logic for controlling operational parameters of the gas turbine system from startup through base load operation wherein a fuel demand signal is provided to a fuel control system according to a controller of the turbine control system, the method comprising:

providing encoded information in a turbine control system for combustion efficiency in a plurality of combustion modes based on at least one reference parameter;

sensing a combustion mode transfer from a starting combustion mode to an ending combustion mode;

calculating a combustion efficiency signal for operating conditions under the starting combustion mode for the gas turbine;

calculating a combustion efficiency signal for operating conditions under the ending combustion mode; and

biasing a fuel demand signal to a fuel control system according to an algorithm whose technical effect is to correct for combustion efficiency according to combustion mode.

2. The method according to claim 1, wherein the reference parameter for the encoded information comprises a combustion reference temperature.

3. The method according to claim 1 wherein combustion efficiency comprises steady state combustion efficiency.

4. The method according to claim 3, wherein encoded information comprises combustion efficiency for operation with a gaseous fuel.

5. The method according to claim 3, wherein encoded information comprises combustion efficiency for operation with a liquid fuel.

6. The method according to claim 1, wherein the step of providing comprises accessing the encoded information in a turbine control system for combustion efficiency as a numerical model.

7. The method according to claim 6, wherein the step of accessing the encoded information for combustion efficiency comprises accessing in one of a lookup table, a transfer function, and a neural network.

8. The method according to claim 1, wherein the step of biasing the fuel demand signal comprises:

adding a bias signal of (1/η

−

1)*fuel demand to the fuel demand signal wherein η

is the combustion efficiency.

9. The method according to claim 8, further comprising:

iteratively applying a transient combustion efficiency η

_transient to the bias signal for fuel demand during a combustion mode change according to a progress of transistion between the starting combustion mode with a combustion efficiency of η

_{starting mode} and the ending combustion mode with a combustion efficiency of η

_{ending mode}.

10. The method according to claim 8, further comprising:

applying a steady state combustion efficiency to the bias signal for fuel demand during steady state operation within a combustion mode.

11. A gas turbine system with operating modes, the gas turbine system comprising:

a compressor, a combustion system and a turbine;

a turbine control system employing a mode logic for controlling operational parameters of the gas turbine system from startup through base load operation;

a fuel control system;

a fuel demand signal from the turbine control system to the fuel control system;

encoded information in the turbine control system for combustion efficiency in a plurality of combustion modes based on at least one reference parameter;

a calculation for a combustion efficiency signal for operating conditions under a starting combustion mode for the gas turbine;

a calculation for a combustion efficiency signal for operating conditions under an ending combustion mode for the gas turbine; and

a bias to the fuel demand signal according to an algorithm whose technical effect is to correct the fuel demand signal for combustion efficiency according to combustion mode.

12. The gas turbine system according to claim 11, wherein the encoded information comprises information for operation with at least one of a gaseous fuel and a liquid fuel.

13. The gas turbine system according to claim 11, wherein the bias to the fuel demand signal according to combustion mode is a function of combustion reference temperature.

14. The gas turbine system according to claim 11, further comprising a numerical model in the turbine control system wherein combustion efficiency is accessed.

15. The gas turbine system according to claim 14 wherein the numerical model in the turbine control system for efficiency comprises one of a lookup table, a transfer function, and a neural network.

16. The gas turbine system according to claim 15, wherein the numerical model accepts as input physical parameters that are determinant of combustion system performance.

17. The gas turbine system according to claim 11, the turbine control system comprising:

a combustion efficiency calculation for the fuel control system under a starting operating mode and a a combustion efficiency calculation for the fuel control system under a ending operating mode.

18. The gas turbine system according to claim 17, wherein the fuel demand signal is biased according to:

(1/η

−

1)*Fuel Demand wherein η

is the combustion efficiency.

19. The gas turbine system according to claim 18 wherein combustion efficiency comprises a transient combustion efficiency η

_transient to the bias signal for fuel demand during a combustion mode change according to a progress of transition between the starting combustion mode with a combustion efficiency of η

_{starting mode} and the ending combustion mode with a combustion efficiency of η

_{ending mode}.

20. The gas turbine system according to claim 18, wherein a steady state combustion efficiency comprises the bias signal for fuel demand during steady state operation within a combustion mode.