Method and system for determining and tracking wind turbine tower deflection

A system for determining deflection of a tower of a wind turbine, the wind turbine including a nacelle with a machine head and a rotor atop of the tower, the system comprising:

• at least one rover receiver of a global navigation satellite system (GNSS) configured at a fixed position on the nacelle or on the tower;
• a controller in communication with the rover receiver, the controller configured to perform the following operations:
• detecting a total deflection of a geographic location (“geo-location”) of a fixed location on the tower;
• determining components of the total deflection that are generated by non-thrust loads acting on the tower;
• and subtracting the non-thrust loads deflection components from the total deflection to determine a thrust loads deflection component corresponding to deflection of the tower from operational thrust loads on the rotor;
• and wherein the thrust loads deflection component is used directly as a control variable for performing one or more of:
• changing an operating parameter of the wind turbine based on a difference between an expected thrust loads deflection component and the determined thrust loads deflection component;
• performing a repair or maintenance procedure based on a difference between the expected thrust loads deflection component and the determined thrust loads deflection component;
• or determining tower or foundation integrity, or making a tower or foundation life prediction, based on a difference between the expected thrust loads deflection component and the determined thrust loads deflection component.