Apparatus and method for controlling a locomotive consist having a locomotive and auxiliary power unit

1. A locomotive assembly comprising:

at least one locomotive comprising:

a power bus;

a primary engine-generator set electrically coupled to the power bus; and

a locomotive controller programmed to control the primary engine-generator set; and

a first auxiliary power unit comprising:

a first auxiliary engine-generator set electrically coupled to a locomotive power bus; and

a first auxiliary controller programmed to:

receive a command signal from the locomotive controller indicating a desired amount of power; and

control the first auxiliary engine-generator set of the auxiliary power unit to produce the desired amount of power; and

wherein the locomotive controller is programmed to generate control commands for the primary engine-generator set and the first auxiliary engine-generator set that minimize a total cost of power of the locomotive assembly.

2. The locomotive assembly of claim 1 wherein the locomotive controller is programmed to determine a connection status of the first auxiliary power unit to the power bus.

3. The locomotive assembly of claim 1 wherein the locomotive controller is further programmed to:

identify operating parameters of the first auxiliary power unit;

determine a desired amount of power from the first auxiliary power unit based on the identified operating parameters of the first auxiliary power unit; and

transmit the command signal to the first auxiliary controller indicating the desired amount of power.

4. The locomotive assembly of claim 3 wherein the locomotive controller is further programmed to determine the desired amount of power based on a comparison of operating costs of the first auxiliary engine-generator set and operating costs of the primary engine-generator set.

5. The locomotive assembly of claim 3 wherein the command signal comprises one of a desired operating point on a performance graph and a desired power level of the first auxiliary power unit.

6. The locomotive assembly of claim 3 wherein the identified operating parameters of the first auxiliary power unit comprise at least one of an equipment configuration of the first auxiliary power unit, performance characteristics of the first auxiliary power unit, operational history data of the first auxiliary power unit, and a current status of the first auxiliary power unit.

7. The locomotive assembly of claim 1 further comprising a second auxiliary power unit comprising:

a second auxiliary engine-generator set electrically coupled to the power bus; and

a second auxiliary controller programmed to:

receive a command signal from the locomotive controller indicating a desired amount of power; and

control the second auxiliary engine-generator set to output the desired amount of power; and

wherein the locomotive controller is further programmed to:

identify operating parameters of the first auxiliary power unit;

identify operating parameters of the second auxiliary power unit;

determine a desired amount of power from the first auxiliary power unit based on the identified operating parameters of the first auxiliary power unit;

determine a desired amount of power from the second auxiliary power unit based on the identified operating parameters of the second auxiliary power unit;

transmit a first command signal to the first auxiliary controller indicating the desired amount of power from the first auxiliary power unit; and

transmit a second command signal to the second auxiliary controller indicating the desired amount of power from the second auxiliary power unit.

8. The locomotive assembly of claim 1 further comprising:

a power connection cable electrically coupled between the output of the first auxiliary engine-generator set and the power bus; and

a disconnect sensor coupled to the power connection cable, the disconnect sensor configured to sense a connection status of the first auxiliary engine-generator set with the power bus; and

wherein the first auxiliary controller is further programmed to:

receive an alert signal from the disconnect sensor indicating a disconnection between the power connection cable and the power bus; and

upon receiving the alert signal, initiate a shutdown protocol for the first auxiliary engine-generator set.

9. The locomotive assembly of claim 1 further comprising a control connection cable electrically coupled between the primary locomotive controller and the first auxiliary controller; and

wherein at least one of the primary locomotive controller and the first auxiliary controller is further programmed to detect a fault in the transmission of control commands through the control connection cable.

10. The locomotive assembly of claim 9 wherein, upon detection of the fault, the primary locomotive controller is further programmed to perform at least one of the following actions: resend a power command and modify a power command.

11. The locomotive assembly of claim 9 wherein, upon detection of the fault, the first auxiliary controller is further programmed to:

transmit a signal to the primary locomotive controller indicating a disconnect fault; and

initiate a shutdown protocol and shunt the first auxiliary engine-generator set.

12. A method of providing power to a locomotive, the method comprising:

coupling an auxiliary power unit to a power bus of the locomotive, the auxiliary power unit comprising an auxiliary engine-generator set and an auxiliary controller electrically coupled to the auxiliary engine-generator set;

coupling the auxiliary controller to a primary locomotive controller;

sending a first power command from the primary locomotive controller to the auxiliary controller;

sending a second power command from the primary locomotive controller to a primary engine-generator set of the locomotive; and

controlling the auxiliary engine-generator set to generate an auxiliary power for delivery to the power bus responsive to the first power command.

13. The method of claim 12 further comprising:

identifying the auxiliary power unit;

obtaining operational information about the auxiliary power unit; and

generating the first power command specific to the identified auxiliary power unit.

14. The method of claim 12 further comprising:

detecting a decoupling event between the auxiliary power unit and the power bus;

adjusting the power allocation upon detection of the decoupling event; and

sending an adjusted power allocation command to the auxiliary power unit.

15. The method of claim 12 further comprising blending power from the auxiliary power unit and the locomotive on the power bus.

16. A controller for a locomotive, the controller comprising:

a processor programmed to:

receive a cost of power from an auxiliary power unit electrically coupled to the locomotive controller, the auxiliary power unit comprising an auxiliary engine-generator set;

determine a cost of power for a locomotive engine-generator set electrically coupled to the locomotive controller;

determine an amount of power required to operate the locomotive; and

use the cost of power from the auxiliary power unit and the cost of power for the locomotive engine-generator set to determine an allocation of power between the locomotive engine-generator set and the auxiliary power unit, wherein the allocation of power minimizes an overall cost of power to operate the locomotive.

17. The controller of claim 16 wherein the processor is further programmed to receive the cost of power from the auxiliary power unit as a scalar value.

18. The controller of claim 16 wherein the processor is further programmed to:

receive the cost of power from the auxiliary power unit as a cost of power vs. power generated graph;

use the cost of power vs. power generated graph and the cost of power from the locomotive engine-generator set to determine the allocation of power.

19. The controller of claim 16 wherein the processor is further programmed to:

receive a cost of fuel as at least one of a scalar value and a fuel/power graph from the auxiliary power unit; and

use the cost of fuel to determine the cost of power for the auxiliary power unit.

20. The controller of claim 19 wherein the processor is further programmed to:

send a power command to the auxiliary power unit consistent with the amount of power; and

set desired output voltage levels in order to permit power blending between power output from the locomotive engine-generator and power output from the auxiliary power unit on a power bus of the locomotive.

21. The method of claim 12 further comprising generating the first power command and the second power command to minimize a total cost of power of the locomotive.