Fuel control system for gas turbine and feed forward control method

A gas turbine comprising:

• a compressor, turbine, combustion system and fuel supply;
• a fuel conduit extending from the fuel supply to the combustion system;
• a fuel supply pressure sensor proximate the fuel supply and sensing fuel pressure proximate to the fuel supply;
• a fuel pressure control valve regulating a fuel pressure in a downstream portion of the fuel conduit proximate to the combustion system;
• a combustion system fuel pressure sensor sensing fuel pressure in the downstream portion of the fuel conduit;
• a fuel controller including a proportional-integrated (Pl) unit generating a control command for the pressure control valve and receiving a desired fuel pressure input signal representing a desired fuel pressure from a core fuel control system and an actual fuel pressure input signal from the first pressure sensor representing an actual fuel pressure downstream of the pressure control valve, and
• a plurality of control gains stored in electronic memory of the fuel controller, wherein each of the control gains is applicable to a respective predefined operating condition of the gas turbine, and wherein the controller selects which control gain is to be applied by the PI logic unit based on an actual operating condition of the gas turbine, wherein each difference between the desired fuel pressure input signal and the actual fuel pressure input signal is multiplied by one of the plurality of control gains.

A method to control a pressure of a gaseous fuel flowing from a fuel supply to a combustion system of a gas turbine, the method comprising:

• selecting a control gain from a plurality of control gains, wherein each of the control gains is applicable to a predefined operating condition of the gas turbine engine and wherein the selection is dependent on a current operating state of the gas turbine;
• sensing a pressure of the fuel flow upstream from the combustion system;
• determining a pressure difference between the sensed pressure and a desired fuel pressure;
• multiplying the selected control gain to the pressure difference to generate a correction, and
• applying the correction to adjust a pressure valve regulating the pressure of the gaseous fuel proximate to the combustion system.