System and method for monitoring a wind turbine gearbox

1. A wind turbine gearbox monitoring system, comprising:

a plurality of sensors coupled to a wind turbine gearbox outputting at least one of vibration information and shaft speed information; and

a controller coupled to the plurality of sensors and configured to output operating information identifying potential and actual damage within the wind turbine gearbox based on the vibration information and the shaft speed information, the controller converting the shaft speed information and the vibration information into a cycle domain signal, and performing an order analysis on the cycle domain signal, the order analysis providing information that identifies potential and actual damage within the wind turbine gearbox, wherein to convert the equal time vibration information into an equal circumferential position cycle domain signal using a tachometer pulse train signal, the controller is further programmed to divide the tachometer signal into a plurality of segments, each segment representing a different rotational position of a gearbox shaft.

2. The monitoring system in accordance with claim 1 , wherein the shaft speed information is acquired directly from a tachometer installed on the wind turbine gearbox.

3. The monitoring system in accordance with claim 1 , wherein the shaft speed information comprises synthetic low-speed shaft information that is synthesized using shaft speed profile information acquired from a high-speed shaft.

4. The monitoring system in accordance with claim 1 , wherein the tachometer signal comprises a synthetic high-speed shaft tachometer signal that is synthesized using shaft speed information acquired from a low-speed shaft.

5. The monitoring system in accordance with claim 1 , wherein the tachometer signal comprises a low-speed shaft tachometer signal that is synthesized using shaft speed information acquired from a high-speed shaft.

6. The monitoring system in accordance with claim 1 , wherein to perform the order analysis, the controller is further programmed to apply a Fast Fourier Transform (FFT) to the converted cycle domain signal.

7. The monitoring system in accordance with claim 1 , wherein the controller is further programmed to convert a shaft speed profile of a first shaft to generate a synthetic tachometer signal representing the rotational speed of a second different shaft.

8. The monitoring system in accordance with claim 1 , wherein the tachometer signal comprises a synthetic low-speed shaft tachometer signal, the controller configured to convert a high-speed tachometer signal into a high-speed shaft speed profile, convert the high-speed shaft speed profile into a low-speed shaft profile, and convert the low-speed shaft profile into the low-speed tachometer signal.

9. A wind turbine comprising:

a rotor including a plurality of blades;

a gearbox coupled to the rotor;

a generator coupled to the gearbox;

a plurality of sensors coupled to the gearbox outputting at least one of vibration information and shaft speed information; and

a controller coupled to the plurality of sensors and configured to output operating information identifying potential and actual damage within the wind turbine gearbox based on the vibration information and the shaft speed information, the controller converting the shaft speed information and the vibration information into a cycle domain signal, and performing an order analysis on the cycle domain signal, the order analysis providing information that identifies potential and actual damage within the wind turbine gearbox, wherein to convert the tachometer signal and the vibration information into a cycle domain final, the controller is further programmed to divide the tachometer signal into a plurality of segments, each segment representing a different rotational position of a gearbox shaft.

10. The wind turbine in accordance with claim 9 , wherein the shaft speed information is acquired directly from a tachometer installed on the wind turbine gearbox.

11. The wind turbine in accordance with claim 9 , wherein the shaft speed information comprises a synthetic low-speed shaft tachometer signal that is synthesized using shaft speed information acquired from a high-speed shaft.

12. The wind turbine in accordance with claim 9 , wherein the tachometer signal comprises a synthetic high-speed shaft tachometer signal that is synthesized using shaft speed information acquired from a low-speed shaft.

13. The wind turbine in accordance with claim 9 , wherein to perform the order analysis, the controller is further programmed to apply a Fast Fourier Transform (FFT) to the cycle domain signal.

14. The wind turbine in accordance with claim 9 , wherein the controller is further programmed to convert a shaft speed profile of a first shaft to generate a synthetic tachometer signal representing the rotational speed of a second different shaft.

15. A method of monitoring the health of a wind turbine gearbox, said method comprising:

acquiring vibration information from a vibration sensor coupled to a wind turbine gearbox;

acquiring a tachometer signal;

converting the tachometer signal and the vibration information into a cycle domain signal using a processor; and

performing, using the processor, an order analysis on the cycle domain signal, the order analysis enabling an operator to identify potential damage within the wind turbine gearbox, wherein converting further comprises dividing the tachometer signal into a plurality of segments, each segment representing a different rotational position of a gearbox shaft.

16. The method in accordance with claim 15 wherein acquiring a tachometer signal further comprises synthesizing a synthetic low-speed shaft tachometer signal using shaft speed information acquired from a high-speed shaft.

17. The method in accordance with claim 15 wherein acquiring a tachometer signal further comprises applying a Fast Fourier Transform (FFT) to the cycle domain signal.