Point absorbing wave energy converters that do not require a rigid structure, are easy to deploy and are economically viable for a variety of deployments are disclosed herein below. The system includes a point absorber wave energy converter and a flexible component and ballast combination, where the flexible component and ballast combination includes a ballast subsystem and a flexible linear component extending from the point absorber wave energy converter to the ballast subsystem and operatively connected at one end to the ballast subsystem and at another end to the point absorber wave energy converter. The flexible component and ballast combination configured to provide a strong drag force when moving upward in a water column and a weak drag force when sinking in the water column.

A method for determining the load on a wind turbine blade, comprising: measuring the blade load by way of a wind turbine blade load sensor; estimating the temperature of the blade; and determining, based on the estimated temperature and the measured load, a temperature-corrected value for the load on the wind turbine blade. The invention also relates to a sensor system for a wind turbine blade, the system comprising a load sensor; a processing unit interfaced with the load sensor and configured to provide a temperature-corrected load parameter as an output, wherein the processing unit includes: a temperature estimation module that determines an estimated temperature of the blade in the vicinity of the load sensor based on at least one wind turbine parameter; and a load compensation module that determines the temperature-corrected load parameter based on the estimated temperature and the measurement of the load sensor.

The present disclosure is directed to systems and methods for automatically calibrating a load sensor system of a wind turbine and determining health of same. In one embodiment, the method includes receiving a plurality of sensor signals generated by the plurality of load sensors from the load sensor system. The method also includes determining, via a computer model, a load estimation of the wind turbine based on the sensor signals, turbine geometry, and one or more additional input parameters (e.g. rotor azimuth angle, pitch angle, rotor position, etc.). Another step includes comparing the load estimation to a load measurement to determine one or more correlation coefficients. Thus, the method also includes calibrating the plurality of sensors in the load sensor system based on the correlation coefficients.

A sensor has an at least partially conductive material to which plural conductive contacts are connected. A processor causes circuits to be formed between pairs of the conductive contacts to measure an electrical property of the material between the contacts, such as a resistance of the material. The processor conducts such measurements between plural pairs of contacts to determine a location of an influence on the material and produces an output indicating the location. The influence can be, for example, a disruption of the material or, where the electrical properties of the material are affected by strain, a strain of the material.

A method for mitigating loads acting on a rotor blade of a wind turbine includes determining, via a state estimator of a controller, a blade state estimation of the rotor blade. The method also includes reconstructing, via the controller, one or more loading signals of the rotor blade from the blade state estimation using modal analysis such that the loading signal(s) include a lead time. Further, the method includes comparing the loading signal(s) of the rotor blade to a loading threshold. Moreover, the method includes implementing a control action based on the comparison such that the lead time provided by the loading signal(s) allows the control action to take effect before a damaging load occurs on the rotor blade.

A backlash measuring method is provided for measuring backlash at a plurality of different times. The backlash measuring method includes: a rotation amount calculating step of braking a ring gear relative to a second portion while contact between a target tooth and the ring gear achieved in a contacting step is maintained, causing a target pinion to rotate toward a second side in a rotation direction opposite to the first side with a driving force less than a braking force applied to brake the ring gear relative to the second portion until the target tooth touches the ring gear at a tooth surface facing the second side, and calculating an amount of rotation of the target pinion; and a measuring step of measuring backlash between the ring gear and the target pinion based on the amount of rotation of the target pinion calculated in the rotation amount calculating step.

A method of controlling a wind turbine having a nacelle, a rotor, a rotating hub, a first rotor blade and at least a second rotor blade, both rotor blades being mounted to the hub. The method includes measuring the strain in the first rotor blade by a strain measurement device attached to the first rotor blade; and choosing the operational parameters of the wind turbine based on the measured strain such that fatigue damage of the second rotor blade is reduced. A wind turbine is controlled by such a method.

A support frame (44) and method are described herein for support of a wind turbine blade (22) on a vehicle during transport to an installation site. A load indicator (46) is provided adjacent one or more support pads (52) when using the support frame (44), with the load indicator (46) being configured to determine and communicate an amount of movement of the wind turbine blade (22) relative to the support frame (44) during initial loading into the support frame (44) and during transport. To this end, the load indicator (46) helps assure that the wind turbine blade (22) is properly loaded into the support frame (44) in a desired transport position, while also confirming whether significant shocks or other movements have occurred during transport that could lead to a higher likelihood of internal or external damage at the blade (22).

The present invention discloses methods and systems for detecting the health status of a bolt which fastens a rotor blade of a wind turbine. Values of the axial stress/strain of the bolt and motion and orientation data are acquired in different aerial orientations. Values of the prestress/strain and load-stress/strain are obtained using the values of the axial stress/strain and the motion and orientation data. Values of the prestress/strain and load-stress/strain are compared with the reference values. The health status of the bolt, rotor blade, and the wind turbine system is determined based on the comparison results. The method is noninvasive and doesn't affect the function and performance of the bolt and the turbine system.

The present disclosure is directed to a system for monitoring wear on a gearbox of a wind turbine. A controller of the system is configured to determine a torque exerted on a rotor shaft of the wind turbine or a generator shaft of the wind turbine based on measurement signals received from a first sensor of the system. The controller is also configured to determine an accumulated wear value for the gearbox based on the torque.