Hybrid gas turbine engine-electric motor/generator drive system

Abstract

A method of operating a drive system for a load is disclosed. The drive system may have an electric motor/generator and a gas turbine engine. The engine may have a combustor, and main and pilot flow paths via which fuel is supplied to the combustor. The engine may be operable in low and standard emissions modes. A proportion of the fuel that is supplied to the combustor via the pilot flow path may be greater in the standard emissions mode than in the low emissions mode. The method may include determining an engine power requirement of the load, and whether the engine power requirement of the load is sufficiently large to operate the engine in the low emissions mode. Additionally, the method may include operating the electric motor/generator if the engine power requirement of the load is not sufficiently large to operate the engine in the low emissions mode.

1 - 21 . (canceled) 
     
     
         22 . A method of operating a drive system for a load, the drive system including an electric motor/generator and a gas turbine engine, the engine including a combustor, and main and pilot flow paths via which fuel is supplied to the combustor, the engine being operable in a low emissions mode and a standard emissions mode, a proportion of the fuel that is supplied to the combustor via the pilot flow path being greater in the standard emissions mode than in the low emissions mode, the method comprising:
 determining whether an environmental condition exceeds a threshold to operate the engine in the low emissions mode, wherein the environmental condition comprises at least one of inlet air temperature, humidity, air density, and fuel type; and   maintaining the engine in an off position if the environmental condition fails to exceed the threshold to operate the engine in low emissions mode.   
     
     
         23 . The method of  claim 22 , wherein determining whether the environmental condition exceeds a threshold to operate the engine in the low emissions mode includes:
 determining an inlet air temperature of the engine;   determining whether the inlet air temperature exceeds a threshold to operate the engine in the low emissions mode; and   determining that the environmental condition fails to exceed the threshold to operate the engine in the low emissions mode if the inlet air temperature fails to exceed a threshold to operate the engine in the low emissions mode.   
     
     
         24 . The method of  claim 22 , further including:
 determining a minimum modified engine power requirement of the load if the electric motor/generator is operated as a motor; and   determining whether the minimum modified engine power requirement exceeds a threshold to enable engine shut down, wherein the engine is only shut down if the minimum modified engine power requirement exceeds the threshold to enable engine shut down.   
     
     
         25 . The method of  claim 22 , further including:
 determining an engine power requirement of the load;   determining whether the engine power requirement of the load exceeds a threshold percentage of rated power to operate the engine in the low emissions mode; and   operating the electric motor/generator if:
 the environmental condition exceeds the threshold to operate the engine in the low emissions mode; and 
 the engine power requirement of the load fails to exceed the threshold percentage of rated power to operate the engine in the low emissions mode. 
   
     
     
         26 . The method of  claim 25 , further including:
 determining a maximum modified engine power requirement of the load when the electric motor/generator is operated as a generator; and   determining whether the maximum modified engine power requirement exceeds a threshold percentage of rated power to operate the engine in the low emissions mode, wherein the electric motor/generator is operated as a generator if the maximum modified engine power requirement exceeds the threshold percentage of rated power to operate the engine in the low emissions mode.   
     
     
         27 . The method of  claim 25 , further including:
 determining a minimum modified engine power requirement of the load when the electric motor/generator is operated as a motor; and   determining whether the minimum modified engine power requirement exceeds a threshold to enable engine shut down, wherein the engine is shut down if the minimum modified engine power requirement exceeds the threshold to enable engine shut down.   
     
     
         28 . The method of  claim 22 , further including:
 determining an engine power requirement of the load;   determining whether a rated power of the engine exceeds the engine power requirement of the load; and   maintaining the engine in the off position if the rated power of the engine fails to exceed the engine power requirement of the load.   
     
     
         29 . The method of  claim 28 , further including:
 determining a minimum modified engine power requirement of the load if the electric motor/generator is operated as a motor;   determining whether the rated power of the engine exceeds the minimum modified engine power requirement; and   notifying an offboard system if the rated power of the engine fails to exceed the minimum modified engine power requirement.   
     
     
         30 . A method of operating a drive system for a load, the drive system including an electric motor/generator and a gas turbine engine, the engine including a combustor, and main and pilot flow paths via which fuel is supplied to the combustor, the engine being operable in a low emissions mode and a standard emissions mode, a proportion of the fuel that is supplied to the combustor via the pilot flow path being greater in the standard emissions mode than in the low emissions mode, the method comprising:
 determining an engine power requirement of the load;   determining whether the engine power requirement of the load exceeds a threshold percentage of rated power to operate the engine in the low emissions mode; and   maintaining the engine in an off position if the engine power requirement of the load fails to exceed the threshold percentage to operate the engine in low emissions mode.   
     
     
         31 . The method of  claim 30 , further including:
 determining a maximum modified engine power requirement of the load if the electric motor/generator is operated as a generator;   determining whether the maximum modified engine power requirement exceeds a threshold percentage of rated power to operate the engine in the low emissions mode; and   operating the electric motor/generator as a generator if the maximum modified engine power requirement exceeds the threshold percentage of rated power to operate the engine in the low emissions mode.   
     
     
         32 . The method of  claim 30 , further including:
 determining a minimum modified engine power requirement of the load if the electric motor/generator is operated as a motor; and   determining whether the minimum modified engine power requirement exceeds a threshold to enable engine shut down, wherein the engine is shut down if the minimum modified engine power requirement exceeds the threshold to enable engine shut down.   
     
     
         33 . The method of  claim 30 , further including:
 determining whether a rated power of the engine exceeds the engine power requirement of the load; and   maintaining the engine in the off position if the rated power of the engine fails to exceed the engine power requirement of the load.   
     
     
         34 . The method of  claim 33 , further including:
 determining a minimum modified engine power requirement of the load the electric motor/generator is operated as a motor;   determining whether the rated power of the engine exceeds the minimum modified engine power requirement; and   notifying an offboard system if the rated power of the engine fails to exceed the minimum modified engine power requirement.   
     
     
         35 . The method of  claim 30 , further including determining whether an environmental condition exceeds a threshold to operate the engine in the low emissions mode, wherein:
 the environmental condition comprises at least one of inlet air temperature, humidity, air density, and fuel type; and   the engine is maintained in the off position if the environmental condition fails to exceed the threshold to operate the engine in the low emissions mode.   
     
     
         36 . The method of  claim 35 , wherein determining whether the environmental condition exceeds a threshold to operate the engine in the low emissions mode includes:
 determining an inlet air temperature of the engine;   determining whether the inlet air temperature exceeds a threshold to operate the engine in the low emissions mode; and   determining that the environmental condition fails to exceed the threshold to operate the engine in the low emissions mode if the inlet air temperature fails to exceed the threshold to operate the engine in the low emissions mode.   
     
     
         37 . The method of  claim 35 , further including:
 determining a minimum modified engine power requirement of the load if the electric motor/generator is operated as a motor; and   determining whether the minimum modified engine power requirement exceeds a threshold to enable engine shut down, wherein the engine is only shut down if the minimum modified engine power requirement exceeds the threshold to enable engine shut down.   
     
     
         38 . A turbine-compressor unit, comprising:
 a centrifugal compressor;   a gas turbine engine coupled to the centrifugal compressor, the engine including:
 a combustor; and 
 main and pilot flow paths via which fuel is supplied to the combustor, wherein the engine is operable in a low emissions mode and a standard emissions mode, a proportion of the fuel that is supplied to the combustor via the pilot flow path being greater in the standard emissions mode than in the low emissions mode; 
   an electric motor/generator coupled to the centrifugal compressor; and   a controller in communication with the centrifugal compressor, the engine, and the electric motor/generator, the controller being configured to:
 determine an engine power requirement of the centrifugal compressor; 
 determine whether the engine power requirement of the centrifugal compressor exceeds a threshold to operate the engine in the low emissions mode; and 
 maintain the engine in the off position if the engine power requirement of the centrifugal compressor fails to exceed a threshold to operate the engine in the low emissions mode. 
   
     
     
         39 . The turbine-compressor unit of  claim 38 , wherein the controller is further configured to:
 determine a maximum modified engine power requirement of the centrifugal compressor if the electric motor/generator is operated as a generator;   determine whether the maximum modified engine power requirement exceeds a threshold to operate the engine in the low emissions mode; and   operate the electric motor/generator as a generator if the maximum modified engine power requirement exceeds a threshold to operate the engine in the low emissions mode.   
     
     
         40 . The turbine-compressor unit of  claim 39 , wherein the controller is further configured to determine whether an environmental condition exceeds a threshold to operating the engine in the low emissions mode, wherein the electric motor/generator is only operated as a generator if the environmental condition is conducive to operating the engine in the low emissions mode. 
     
     
         41 . The turbine-compressor unit of  claim 38 , wherein the controller is further configured to:
 determine a minimum modified engine power requirement of the centrifugal compressor if the electric motor/generator is operated as a motor;   determine whether the minimum modified engine power requirement exceeds a threshold to enable engine shut down; and   shut down the engine if the minimum modified engine power requirement exceeds a threshold to enable engine shut down.