The present invention relates to a method for operating a wind power installation, comprising the steps of: sensing at least one angular velocity of the wind power installation, in particular by use of a rotation rate sensor in a hub of the wind power installation, preferably for the purpose of sensing a tilt of the nacelle; sensing a reference value for the at least one sensed angular velocity; determining at least one state variable of the wind power installation from the at least one angular velocity and the reference value; controlling the wind power installation in dependence on the state variable, in particular such that the state variable becomes smaller.

There is provided a method (40) of correcting blade pitch in a wind turbine (10) having a tower (12) and a plurality of rotor blades (18). The method (40) comprises: receiving (410) sensor output data from one or more wind turbine sensors (141), the sensor output data including data indicative of excitation of the tower (12) for a plurality of different pitch angles of a particular one of the blades (18); determining (420) a corrected pitch reference of the particular blade (18), the corrected pitch reference corresponding to a minimum tower excitation based on the received sensor output data; and, sending (430) the corrected pitch reference to a pitch actuator system (24) of the particular blade (18).

Methods and related apparatus for improving synchronization of two or more engines on an aircraft are disclosed. Such method may be used where each engine comprises a first spool and a second spool, and, where a rotational speed of a first spool of a first engine has been substantially synchronized with a rotational speed of a first spool of a second engine. An exemplary method comprises receiving a value of a sensed parameter useful in controlling the first engine; adding a bias to the value; and using the biased value for controlling the first engine to cause a change in rotational speed of the second spool of the first engine in relation to the rotational speed of the first spool of the first engine.

A controller for a wind turbine including a rotor and a nacelle arranged on a tower is provided, the tower having a fundamental frequency close to or below a rated rotational frequency of the rotor. The controller includes a rotor speed control module including a first linear time invariant control system adapted to generate a first pitch control signal based on a rotor speed error signal, a tower damping module including a second linear time invariant control system adapted to generate a second pitch control signal based on a nacelle acceleration signal, and an output module adapted to output a pitch control signal based on the first pitch control signal and the second pitch control signal. Furthermore, a wind turbine and a method of controlling a wind turbine is provided.

The present invention relates to blade monitoring of a wind turbine by actively promoting blade vibrations by imposing a pitch actuation signal. A method of operating a wind turbine is disclosed where for each blade of a wind turbine, vibrations of the blade are actively promoted by imposing a pitch actuation signal to the pitch actuator, and at least one parameter relating to the blade vibration is determined.

Disclosed herein is a vibration monitoring and diagnosing system for monitoring conditions of a wind power generator and diagnosing a defective portion thereof using vibration characteristics obtained from acceleration sensors mounted to the wind power generator. A vibration-based defect detecting method may include: collecting vibration data of the wind power generator using the plurality of sensors; extracting a first characteristic value of a time domain based on the vibration data; extracting characteristic values in one or more frequency bands for a location of each sensor in a frequency domain or an envelope frequency domain if the first characteristic value is greater than a preset alarm setting value; and determining that a defect is present when at least one characteristic value of the characteristic values is greater than a preset normal value.

A method for monitoring a wind turbine is described. The method comprises measuring acceleration by means of a fiber-optic acceleration sensor in a rotor blade of the wind turbine; opto-electronically converting an acceleration signal of the fiber-optic acceleration sensor; and filtering the opto-electronically converted acceleration signal by means of an analog anti-aliasing filter.

A system and method are provided for reducing vibrations and loads in one or more rotor blades of a wind turbine when the rotor hub is locked against rotation, The method detects that the rotor blades are vibrating above a threshold limit, and determines one or more wind parameters for wind impacting the rotor blades. An initial orientation of the blades is also determined. Based on the wind parameters and initial blade orientation, a first angle of attack for the rotor blades is determined that will reduce the vibrations in the rotor blades. The method then determines if expected loads induced at one or more wind turbine components will exceed a threshold limit at the first angle of attack for the rotor blades. The first angle of attack is modified when the expected loads exceed the threshold limit to reduce the expected loads to below the threshold limit. A controller pitches the rotor blades to achieve the first angle of attack.

A method for operating a wind turbine includes determining at least one wind condition of the wind turbine for a plurality of time intervals. The method also includes determining a status of the wind turbine at the beginning of each of the plurality of time intervals. Further, the method includes determining at least one vibration parameter of the wind turbine for one or more preceding time intervals of the plurality of time intervals. Moreover, the method includes predicting whether a trip event is imminent based on the at least one wind condition, the status of the wind turbine at the beginning of each of the plurality of time intervals, and the vibration parameter. Thus, the method further includes implementing a control action for the wind turbine so as to prevent the trip event.

The invention relates to a method of identifying a wind distribution pattern over a rotor plane and a wind turbine thereof. At least one operating parameter of the wind turbine and a rotational position of the rotor are measured over a time period. A first wind turbine blade passing signal is extracted from the measured operating parameter and a second wind turbine blade passing signal is generated from the rotational position. The first and second wind turbine blade passing signals are then analysed to determine the characteristics of the actual wind turbine blade passing signal in the rotor plane. These characteristics are afterwards compared to the characteristics of a plurality of known wind distribution patterns, and a unique relationship between the characteristics of the wind turbine blade passing signal and the wind distribution pattern is used to identify a distinctive wind distribution pattern.