Method and system for combustion control for gas turbine system with exhaust gas recirculation

A method, comprising:

• sensing a first angle position of a blower vane of a blower, wherein the blower vane is disposed inside the blower and wherein in operations of the blower the blower vane rotates to move a gas turbine exhaust gas flow through the blower at pressures less than provided by compressor vanes of a compressor of a gas turbine system;
• receiving a desired loading for the gas turbine system;
• computing, via non-model based control logic comprising a physics-based model, a model-based limit comprising a Mach number;
• comparing the Mach number to a Mach limit to derive an indirect limit comprising a difference between the Mach number and the Mach limit;
• computing, by executing a proportional, integral, derivative (PID) control logic that comprises a gas turbine loading value as input, a vane position command;
• comparing the vane position command to a vane position limit to derive a PID limit comprising the difference between the vane position command and the vane position limit;
• selecting the minimum of the indirect limit or the PID limit;
• deriving a second angle position of the blower vane by model-based control or by PID control via adjustment to the first angle position based on the minimum of the indirect limit or the PID limit;
• and
• transmitting an actuation signal to a blower vane actuator to position the blower vane at the second angle position.

A control system comprising:

• a processor configured to:
• sense a first angle position of a blower vane of a blower, wherein the blower vane is disposed inside the blower and wherein in operations of the blower the blower vane rotates to move a gas turbine exhaust gas flow through the blower at pressures less than provided by compressor vanes of a compressor of a gas turbine system;
• receive a desired loading for the gas turbine system;
• compute, by executing a model-based control logic comprising a physics-based model, a model-based limit comprising a Mach number;
• compare the Mach number to a Mach limit to derive an indirect limit comprising a difference between the Mach number and the Mach limit;
• compute, by executing a proportional, integral, derivative (PID) control logic that comprises a gas turbine loading value as input, a vane position command;
• compare the vane position command to a vane position limit to derive a PID limit comprising the difference between the vane position command and the vane position limit;
• select the minimum of the indirect limit or the PID limit;
• derive a second angle position of the blower vane by model-based control or by PID control via adjustment to the first angle position based on the minimum of the indirect limit or the PID limit;
• and
• transmit an actuation signal to a blower vane actuator to position the blower vane at the second angle position.