The present disclosure is directed to a system and method for reducing vortex-induced vibrations of a tower of a wind turbine. The wind turbine has a nacelle mounted atop the tower. The nacelle has a rotor with a rotatable hub having at least one rotor blade mounted thereto. The rotor blade has a first pitch position. Thus, the method includes measuring, via one or more sensors, an acceleration of the nacelle. The method also includes determining a rotor speed of the rotor. Further, the method includes determining a second pitch position for the rotor blade based on the acceleration of the nacelle and the rotor speed and pitching the rotor blade to the second pitch position if the rotor speed is below a speed threshold and the acceleration of the nacelle is above an acceleration threshold. As such, the second pitch position disturbs vortices caused by interactions between the tower and the rotor blade as the rotor blade passes in front of the tower so as to reduce vortex-induced vibrations of the tower.

A method for diagnosing a lubricant containing an additive, is executed by an information processor. Chromaticity information of the lubricant which is a diagnosis target is obtained from an input device, the chromaticity information is obtained by an optical sensor, and a storage device stores a deterioration curve of the lubricant which is the diagnosis target, the deterioration curve is determined in advance regarding a transition in a chromaticity coordinate caused by a deterioration, and a chromaticity coordinate corresponding to a limit contamination level determined in advance using a contaminated lubricant. The processing device obtains a chromaticity coordinate of the lubricant from the chromaticity information and uses a relative contamination level obtained from a distance of the chromaticity coordinate of the lubricant from the deterioration curve and a distance of the chromaticity coordinate corresponding to the limit contamination level from the deterioration curve.

The invention relates to a method for wind turbine generators for reducing electrical disturbances in the form of power variations which are caused by damping controllers arranged the compensate structural oscillations by inducing shaft torque variations. The shaft torque variations are generated by imposing corresponding variations in a generator set-point, e.g. a power or torque set-point. Variations in the generator set-point cause undesired variations in the power injected to the grid by one or more wind turbine generators. According to an embodiment of the invention the electrical disturbances may be reduced by limiting a damping controller's control action. The amount of limitation or restriction of the damping controller may be determined on basis on electrical disturbance information determined from power measured e.g. at a location on the grid.

The present disclosure is directed to a system and method for controlling and/or upgrading aftermarket multivendor wind turbines. The system includes a turbine controller configured to control operations of the wind turbine, a safety device configured to provide a signal indicative of a health status of the safety device, and a secondary controller inserted between the safety device and the turbine controller. The secondary controller is configured to receive the signal from the safety device over a communication interface. As such, if the signal indicates a normal health status, the secondary controller is configured to send the signal to the turbine controller, i.e. maintain normal operation. Alternatively, if the signal indicates a poor health status, the secondary controller is configured to adjust the signal based at least in part on a signal bias to an adjusted signal and to provide the adjusted signal to the turbine controller.

A method for damping vibration in a wind turbine including aerodynamic devices for influencing the airflow flowing from the leading edge of a rotor blade of the wind turbine to the trailing edge of the rotor blade, each aerodynamic device being movable by an actuator between a first protruded configuration and a second retracted configuration is provided. The method includes measuring vibrations in the wind turbine, if the measured vibrations are greater than a threshold within a predefined frequency band, moving a portion of the aerodynamic devices to the second retracted configuration and continuing to measure vibrations, if the measured vibrations are still greater than a threshold within a frequency band, reducing the pitch angle interval of the blade and continuing to measure vibrations, if the measured vibrations are still greater than a threshold within a frequency band, moving all the aerodynamic devices to the second retracted configuration.

A method is provided for dampening oscillations in a wind turbine, the wind turbine having a tower 1, a rotor 3 arranged on the tower 1 such as to be able to rotate about an X axis, and a plurality of blades 4 with adjustable pitch mounted on the rotor. The method includes monitoring the fore-aft oscillation of the tower 1 in the direction of the X axis, at the 2nd or a higher bending mode frequency; determining a compensating torque to be applied by the rotor 3 to the tower 1 of the wind turbine about a Y axis, which is horizontal and at right angles to the X axis, for at least partly dampening the oscillation at the 2nd or higher bending mode frequency; determining for each rotor blade 4 of the wind turbine an adjustment of the pitch angle suitable to generate the compensating torque about the Y axis; and adjusting the pitch angle β1, β2, β3 of at least one of the individual blades 4 to generate at least part of the compensating torque.

A vibration sensor (5) mountable to a wind turbine generator for detecting excessive vibration of the wind turbine generator, the sensor comprising a pendulum having a pendulum bob (25) of pre-determined mass coupled to a detection switch (10), the detection switch arranged to detect oscillation of the pendulum exceeding a predetermined oscillation threshold; said pendulum bob selectively adjustable along said pendulum so as to vary the oscillation threshold of said sensor; wherein the sensor is arranged to exceed the oscillation threshold on receiving a forced vibration corresponding to a vibration threshold of the wind turbine generator.

The invention relates to a method for the individual pitch control of the rotor blades of a wind turbine. The method comprises: measuring an acceleration by means of an acceleration sensor in a rotor blade of the wind turbine; high-pass filtering of a signal of the acceleration sensor in order to determine a time-variant variable; and setting the pitch of the first rotor blade of the wind turbine using the time-variant variable, said pitch setting being part of an individual pitch control.

A shutdown controller for a wind turbine comprises, to improve the estimation of a state of the wind turbine, at least two sensors being adapted to provide sensor data significant for different mechanical states in the wind turbine. The controller can provide an estimated state of the wind turbine based on the sensor data from the at least two sensors and compare the state of the wind turbine with a predefined detection limit to provide a shutdown signal if the estimated state is outside the detection limit.

The present invention relates to control of a wind turbine where nacelle vibration is reduced by use of blade pitching. The nacelle vibrations are reduced based on a position signal of the nacelle. A pitch signal is determined based on the position signal and applied to the pitch-adjustable rotor blades in order to reduce nacelle vibration.