Hybrid power system for locomotive

Abstract

A hybrid power system for a locomotive for reducing emissions. The hybrid power system may have at least one engine powered by natural gas, at least one engine powered by diesel fuel and/or a dual fuel mixture of diesel and natural gas, a drive system operatively coupled to the at least one natural gas powered engine and the at least one diesel and/or dual fuel powered engine for propelling the locomotive, and a system controller for independently controlling power output from the respective engines to the drive system based upon a power demand. The hybrid power system may utilize the natural gas powered engine(s) at low power demands, and then supplement this power with the diesel and/or dual fuel powered engine(s) at higher power demands.

1 . A hybrid power system for a locomotive, comprising:
 at least one engine powered by natural gas;   at least one engine powered by diesel fuel and/or a dual fuel mixture of diesel and natural gas;   a drive system operatively coupled to the at least one natural gas powered engine and the at least one diesel and/or dual fuel powered engine for propelling the locomotive; and   a system controller operatively coupled to the at least one natural gas powered engine, the at least one diesel and/or dual fuel powered engine, and the drive system;   wherein the system controller is configured to:
 i) determine a desired power level for propelling the locomotive; 
 ii) command the at least one natural gas powered engine to supply power to the drive system up to a maximum power output of the at least one natural gas powered engine; and 
 iii) when the desired power level exceeds the maximum power output of the at least one natural gas powered engine, command the at least one diesel and/or dual fuel powered engine to supply power to the drive system to supplement the power supplied by the natural gas powered engine. 
   
     
     
         2 . The hybrid power system according to  claim 1 ,
 wherein the at least one natural gas powered engine includes a plurality of natural gas powered engines; and   wherein the system controller is configured to:
 command one or more of the plurality of natural gas powered engines to supply power to the drive system up to a maximum cumulative power output of the one or more natural gas powered engines; and 
 when the desired power level for propelling the locomotive exceeds the maximum cumulative power output of the one or more natural gas powered engines, command one or more additional natural gas powered engines of the plurality of natural gas powered engines to supply power to the drive system for supplementing the cumulative power output of the first-mentioned one or more natural gas powered engines. 
   
     
     
         3 . The hybrid power system according to  claim 1 ,
 wherein the at least one diesel and/or dual fuel powered engine includes a plurality of diesel and/or dual fuel powered engines; and   wherein the system controller is configured to:
 command one or more of the plurality of diesel and/or dual fuel powered engines to supply power to the drive system up to a maximum cumulative power output of the one or more diesel and/or dual fuel engines; and 
 when the desired power level for propelling the locomotive exceeds the maximum cumulative power output of the one or more diesel and/or dual fuel powered engines, command one or more additional diesel and/or dual fuel powered engines of the plurality of diesel and/or dual fuel powered engines to supply power to the drive system for supplementing the cumulative power output of the first-mentioned one or more diesel and/or dual fuel powered engines. 
   
     
     
         4 . The hybrid power system according to  claim 1 , wherein the desired power level includes a plurality of discrete graduated power levels that are selectable, in which the discrete graduate power levels correspond to a notch schedule. 
     
     
         5 . The hybrid power system according to  claim 1 ,
 wherein the at least one natural gas powered engine and the at least one diesel and/or dual fuel powered engine each have an emissions rate of one or more emissions including nitrogen oxides (NOx), particulate matter (PM), and/or hydrocarbons (NC); and   wherein the controller is configured to control the power output of the at least one natural gas powered engine and the at least one diesel and/or dual fuel powered engine for minimizing the combined emissions rate to below 0.2 g/bhp-hr NOx as an average percentage of the duty cycle.   
     
     
         6 . The hybrid power system according to  claim 1 , wherein the at least one natural gas powered engine has a NOx emission rate of less than 1.0 g/bhp-hr, and wherein the at least one natural gas powered engine has a power output of between 100-500 horsepower. 
     
     
         7 . The hybrid power system according to  claim 1 , wherein the at least one natural gas powered engine is powered only with natural gas. 
     
     
         8 . The hybrid power system according to  claim 1 , wherein the at least one diesel and/or dual fuel powered engine has a NOx emission rate of less than 2.0 g/bhp-hr, and wherein the at least one diesel and/or dual fuel powered engine has a power output of between 500-3500 horsepower. 
     
     
         9 . The hybrid power system according to  claim 1 , wherein the at least one diesel powered engine is powered only with diesel fuel. 
     
     
         10 . The hybrid power system according to  claim 1 , wherein the at least one natural gas powered engine is different from the at least one diesel and/or dual fuel powered engine. 
     
     
         11 . The hybrid power system according to  claim 1 , wherein the at least one diesel powered engine is also powered at least partially by natural gas; and/or wherein the at least one natural gas powered engine is also at least partially powered by diesel. 
     
     
         12 . The hybrid power system according to  claim 1 , further comprising:
 at least one dual fuel engine powered by both natural gas and diesel fuel;   wherein the drive system is operatively coupled to the at least one dual fuel engine for propelling the locomotive; and   the system controller is operatively coupled to the at least one dual fuel engine for controlling the power output of the dual fuel engine based upon a determination of the desired power level to propel the locomotive.   
     
     
         13 . The hybrid power system according to  claim 1 , wherein the system controller commands the at least one dual fuel engine to supply power to the drive system for supplementing the power output of the at least one natural gas powered engine and/or the at least one diesel powered engine. 
     
     
         14 . The hybrid power system according to  claim 1 , wherein the at least one natural gas powered engine, the at least one diesel powered engine, and/or the at least one dual fuel engine are operatively coupled to one or more alternators and/or one or more electrical generators configured to convert mechanical energy from the respective engines to electrical energy, thereby providing alternating current or direct current to one or more traction motors, which transmit power to wheels for propelling the locomotive. 
     
     
         15 . The hybrid power system according to  claim 1 , wherein the system controller controls the power output from the respective engines to the one or more traction motors, and controls the power output from the one or more traction motors to the wheels. 
     
     
         16 . The hybrid power system according to  claim 1 , further comprising a battery, the battery being operatively coupled to one or more traction motors for transmitting power to the wheels. 
     
     
         17 . The hybrid power system according to  claim 16 , wherein the battery is operatively coupled to one or more electrical generators, the electrical generators being configured to convert mechanical energy from the at least one natural gas powered engine, the at least one diesel powered engine, and/or the at least one dual fuel engine into electrical energy for charging the battery. 
     
     
         18 . The hybrid power system according to  claim 16 , wherein the system controller is operatively coupled to battery to receive power, and the controller is configured to charge or discharge the battery based upon the desired power demand. 
     
     
         19 . The hybrid power system according to  claim 1 , further comprising a connection, such as an electrical bus, for being connected to an external power source, such as a power line. 
     
     
         20 . A method of operating a locomotive with a hybrid power system, the method comprising:
 i) determining a desired power level for propelling the locomotive;   ii) commanding at least one natural gas powered engine to supply power to a drive system up to a maximum power output of the at least one natural gas powered engine for propelling the locomotive; and   iii) when the desired power level exceeds the maximum power output of the at least one natural gas powered engine, commanding at least one diesel and/or dual fuel powered engine to supply power to the drive system to supplement the power supplied by the natural gas powered engine.