Gas turbine control method and apparatus

A method controlling a gas turbine engine system of the type having:

• a combustion chamber,
• a controllable fuel supply system opening to the combustion chamber and a controllable combustion air supply system opening to the combustion chamber, said fuel supply system and combustion air supply system serving to provide a combustible fuel and air mixture to the combustion chamber,
• a turbine which is operably driven by exhaust gases from the combustion chamber, said turbine being drivingly connected to a load, such as an electrical generator or the like,
• a compressor drivingly connected to the turbine, said compressor forming part of the combustion air supply system,
• and controllable inlet guide compressor vanes for controlling the amount of air supplied to the compressor.
• said method comprising:
• operating said system with a constant rotational velocity at the compressor and turbine to drive an electric generator,
• continuously generating a first electrical signal corresponding to a desired turbine exhaust temperature,
• continuously generating a second electrical signal corresponding to an actual detected turbine exhaust temperature,
• continuously comparing the first and second signals to generate an electric temperature difference signal representative of the difference between the desired and actual temperatures,
• and utilizing the temperature difference signal to select one of first and second control modes for controlling the fuel/air mixture in the combustion chamber in dependence on the relative values of the first and second signals,
• wherein said first control mode is an exhaust gas temperature control mode where the compressor inlet vanes are maintained in a set position and the exhaust gas temperature is corrected toward the desired temperature TTD Only by varying the fuel supply,
• wherein said second control mode is an inlet guide vane control mode where the exhaust gas temperature is corrected toward the desired temperature T.sub.TD by controlling the compressor inlet guide vanes, and
• wherein said exhaust gas temperature control mode is maintained for rated load operation of the system with the turbine exhaust gas temperature above a predetermined minimum value below the desired temperature T.sub.TD, and wherein said inlet guide vane control mode is switched on during decreasing load conditions when said turbine exhaust gas temperature falls below the predetermined minimum value below the desired temperature T.sub.TD.

A control system for controlling a gas turbine engine system of the type having:

• a combustion chamber having a pre-mixing combustor portion,
• a controllable fuel supply system opening to the pre-mixing combustor portion of the combustion chamber and a controllable combustion air supply system opening to the pre-mixing combustor portion of the combustion chamber, said fuel supply system and combustion air supply system serving to provide a combustible fuel and air mixture from the pre-mixing combustor portion to the combustion chamber,
• a turbine which is operably driven by exhaust gases from the combustion chamber, said turbine being drivingly connected to a load, such as an electrical generator or the like,
• a compressor drivingly connected to the turbine, said compressor forming part of the combustion air supply system,
• and controllable inlet guide compressor vanes for controlling the amount of air supplied to the compressor,
• said control system comprising:
• means for continuously monitoring the temperature of turbine exhaust gases to detect increasing or decreasing changes in the load driven by the turbine;
• and
• means for controlling at least one of the fuel supply system and the combustion air supply system so as to modify a temperature change rate for the turbine exhaust temperature to be different for increasing and decreasing loads.

A method of controlling a gas turbine engine system of the type having:

• a combustion chamber,
• a controllable fuel supply system opening to the combustion chamber and a controllable combustion air supply system opening to the combustion chamber, said fuel supply system and combustion air supply system serving to provide a combustible fuel and air mixture to the combustion chamber,
• a turbine which is operably driven by exhaust gases from the combustion chamber, said turbine being drivingly connected to a load, such as an electrical generator or the like,
• a compressor drivingly connected to the turbine, said compressor forming part of the combustion air supply system,
• and controllable compressor inlet guide vanes for controlling the amount of air supplied to the compressor.
• said method comprising:
• continuously generating a first signal corresponding to a desired turbine exhaust temperature,
• continuously generating a second signal corresponding to an actual detected turbine exhaust temperature,
• continuously comparing the first and second signals to generate a temperature difference signal representative of the difference between the desired and actual temperatures,
• and utilizing the temperature difference signal to select one of first and second control modes for controlling the fuel/air mixture in the combustion chamber in dependence on the relative values of the first and second signals,
• wherein the exhaust gas temperature is corrected toward the desired temperature at a first turbine exhaust temperature correction rate in said first control mode,
• wherein the exhaust gas temperature is corrected toward the desired temperature at a second turbine exhaust gas temperature correction rate in said second control mode, said first and second correction rates being different from one another.

A control system for controlling a gas turbine engine system of the type having:

• a combustion chamber,
• a controllable fuel supply system opening to the combustion chamber and a controllable combustion air supply system opening to the combustion chamber, said fuel supply system and combustion air supply system serving to provide a combustible fuel and air mixture to the combustion chamber,
• a turbine which is operably driven by exhaust gases from the combustion chamber, said turbine being drivingly connected to a load, such as an electrical generator or the like,
• a compressor drivingly connected to the turbine, said compressor forming part of the combustion air supply system,
• controllable compressor inlet guide vanes for controlling the amount of air supplied to the compressor.
• said control system comprising:
• first signal generator for continuously generating a first signal corresponding to a desired turbine exhaust temperature,
• second signal generator for continuously generating a second signal corresponding to an actual detected turbine exhaust temperature,
• a comparator for continuously comparing the first and second signals to generate a temperature difference signal representative of the difference between the desired and actual temperatures,
• means for utilizing the temperature difference signal to select one of first and second control modes for controlling the fuel/air mixture in the combustion chamber in dependence on the relative values of the first and second signals,
• wherein the exhaust gas temperature is corrected toward the desired temperature at a first turbine exhaust temperature correction rate in said first control mode, and
• wherein the exhaust gas temperature is corrected toward the desired temperature at a second turbine exhaust gas temperature correction rate in said second control mode, said first and second correction rates being different from one another.

A method of controlling a gas turbine engine system of the type having:

• a combustion chamber,
• a controllable fuel supply system opening to the combustion chamber and a controllable combustion air supply system opening to the combustion chamber, said fuel supply system and combustion air supply system serving to provide a combustible fuel and air mixture to the combustion chamber.,
• a turbine which is operably driven by exhaust gases from the combustion chamber, said turbine being drivingly connected to a load, such as an electrical generator or the like,
• a compressor drivingly connected to the turbine, said compressor forming part of the combustion air supply system,
• and controllable inlet guide compressor vanes for controlling the amount of air supplied to the compressor,
• said method comprising the steps of:
• continuously monitoring the temperature of turbine exhaust gases to detect increasing or decreasing changes in the load driven by the turbine;
• changing the turbine exhaust temperature at a first temperature correction rate by controlling the fuel supply system for increasing loads;
• and
• changing the turbine exhaust temperature at a second temperature correction rate, different from said first temperature correction rate, by controlling at least one of the combustion air supply system and fuel supply system for decreasing loads.