WHAT IS CLAIMED IS:

1. A method for overspeed monitoring of a wind turbine, the method comprising:

monitoring, with a control device, an actual rotor speed of the wind turbine while the wind turbine is operating at a current speed setpoint;

referencing, with the control device, a dynamic overspeed setting for the wind turbine;

determining, with the control device, a final overspeed setting to be applied for the wind turbine based on a comparison between the dynamic overspeed setting and a predetermined overspeed setting for the wind turbine;

comparing, with the control device, the actual rotor speed of the wind turbine to the final overspeed setting; and

when the actual rotor speed is equal to or exceeds the final overspeed setting, initiating, with the control device, a control action to adjust an operation of the wind turbine in a manner that reduces the actual rotor speed.

2. The method of claim 1, wherein the current speed setpoint corresponds to a speed setpoint that is less than a nominal speed setpoint for the wind turbine.

3. The method of claim 2, wherein the dynamic overspeed setting varies as a function of the current speed setpoint such that the dynamic overspeed setting is less than the predetermined overspeed setting when the current speed setpoint is less than the nominal speed setpoint for the wind turbine.

4. The method of claim 1, wherein referencing the dynamic overspeed setting comprises receiving the dynamic overspeed setting from a turbine controller of the wind turbine, the turbine controller corresponding to a separate device from the control device.

5. The method of claim 1, wherein the dynamic overspeed setting is determined as a function of at least one of the current speed setpoint and an overspeed factor.

6. The method of claim 5, wherein the overspeed factor is selected such that the dynamic overspeed setting corresponds to a speed setting that is 10% to 40% higher than the current speed setpoint.

7. The method of claim 1, wherein determining the final speed setting for the wind turbine comprises selecting the final speed setting as a minimum of the dynamic overspeed setting and the predetermined overspeed setting.

8. The method of claim 1, wherein the predetermined overspeed setting corresponds to a fixed speed limit for the wind turbine determined based on a nominal speed setpoint of the wind turbine.

9. The method of claim 1, wherein initiating the control action to adjust the operation of the wind turbine comprises initiating a shutdown sequence for the wind turbine.

10. The method of claim 1, wherein initiating the control action to adjust the operation of the wind turbine comprises activating a safety chain to decouple a turbine controller of the wind turbine from other components of the wind turbine.

11. The method of claim 1, further comprising monitoring, with the control device, an operational status of a turbine controller of the wind turbine, the turbine controller correspond to a separate device from the control device.

12. An overspeed monitoring system for a wind turbine, the system comprising:

a turbine controller configured to control one or more components of the wind turbine so that the wind turbine operates at a current speed setpoint, the turbine controller being further configured to determine a dynamic overspeed setting for the wind turbine; and

an overspeed control device communicatively coupled to the turbine controller, the overspeed control device being configured to receive the dynamic overspeed setting from the turbine controller and determine a final overspeed setting to be applied for the wind turbine based on a comparison between the dynamic overspeed setting and a predetermined overspeed setting for the wind turbine, the overspeed control device being further configured to monitor an actual rotor speed of the wind turbine and compare the actual rotor speed to the final overspeed setting, wherein, when the actual rotor speed is equal to or exceeds the final overspeed setting, the control device is configured to initiate a control action to adjust the operation of the wind turbine in a manner that reduces the actual rotor speed.

13. The system of claim 12, wherein the current speed setpoint

corresponds to a speed setpoint that is less than a nominal speed setpoint for the wind turbine.

14. The system of claim 13, wherein the dynamic overspeed setting varies as a function of the current speed setpoint such that the dynamic overspeed setting is less than the predetermined overspeed setting when the current speed setpoint is less than the nominal speed setpoint for the wind turbine.

15. The system of claim 12, wherein the overspeed control device correspond to a separate device from the turbine controller.

16. The system of claim 12, wherein the dynamic overspeed setting is determined by the turbine controller as a function of both the current speed setpoint and an overspeed factor.

17. The system of claim 16, wherein the overspeed factor is selected such that the dynamic overspeed setting corresponds to a speed setting that is 10% to 40% higher than the current speed setpoint.

18. The system of claim 12, wherein the overspeed control device is configured to select the final speed setting as a minimum of the dynamic overspeed setting and the predetermined overspeed setting.

19. The system of claim 12, wherein the predetermined overspeed setting corresponds to a fixed speed limit for the wind turbine determined based on a nominal speed setpoint of the wind turbine.

20. The system of claim 12, wherein the control action correspond to the initiation of a shutdown sequence for the wind turbine.