Abstract: A method for erecting a multirotor wind turbine (10) is disclosed. A carrier structure (1, 1a, 1b) is arranged circumferentially with respect to a tower structure (2) and hoisted to an upper part of the tower structure (2), using a hoisting arrangement, such as a wire winch arrangement (3, 4, 8). Furthermore, energy generating units (5) may be hoisted to the carrier structure (1, 1a, 1b) using the hoisting arrangement (3, 4, 8). A similar method for dismantling a multirotor wind turbine (10) is also disclosed. The multirotor wind turbine (10) can be erected or dismantled without the need for an external crane.

Abstract: According to an aspect of the invention, a wind farm is provided. The wind farm includes a plurality of wind turbines and a wind farm controller. The controller is configured to detect a high wind condition from at least one wind turbine in the wind farm, reduce a parameter setpoint of at least one other wind turbine, and increase a cut-out wind speed threshold of the at least one other wind turbine.

Abstract: The invention is directed to a wind turbine system comprising a first pair of wind turbines mounted to a support structure by a first support arm arrangement, and a second pair of wind turbines mounted to the support structure by a second support arm arrangement. The first and second support arm arrangements are mounted to the support structure at a respective yaw unit so as to yaw about the major axis of the support structure. Moreover, the wind turbine system further includes a control system that is configured to control the yaw angle of each of the first and second support arm arrangements, wherein the control system is configured to identify the presence of a predetermined shutdown condition and, in response, the control system is operable to control the yaw angles of the first support arm arrangement and the second support arm arrangement to a predetermined safe state.

Abstract: The present invention relates to control of a wind turbine system comprising a plurality of wind turbine modules mounted to a common support structure, i.e. to control of a multi-rotor wind turbine system. The invention discloses a control system for a multi-rotor wind turbine system which comprises local controllers operable to control the wind turbine modules in accordance with local control objectives and a central controller configured to monitor the operation of the wind turbine system and based thereon calculate the local control objectives. The central controller is implemented as a model predictive controller (MPC).

Abstract: A wind turbine including a controller configured to periodically enter an Eigen frequency detection mode in which the controller gain is incremented in a controlled manner to detect the Eigen frequencies. During normal operations, the controller output may be monitored to detect the Eigen frequency which, if detected, may allow damage control operations to be undertaken.

Abstract: A multirotor wind turbine (1) comprising a tower structure with a main tower part (2) and at least two arms (3), each arm (3) extending away from the main tower part (2) along a direction having a horizontal component. Two or more rotors (4) are mounted on the tower structure in such a manner that each arm (3) of the tower structure carries at least one rotor (4). A gear arrangement (9) of at least one of the rotors (4) comprises a number of pulleys (10, 11, 13) and a number of belts (16, 17) interconnecting the pulleys (10, 11, 13) in order to transfer rotational movements between the pulleys (10, 11, 13), thereby transferring rotational movements from the hub (5) to a rotating shaft (14) connected to a generator (15).

Abstract: A wind turbine system comprising a plurality of wind turbines mounted to a support structure including a tower, wherein each of the plurality of wind turbines includes a rotor and a power generation system driven by the rotor, and at least one of a rotor blade pitch adjustment means and a generator power control means. The system further includes control means that receives vibration data associated with the support structure and which is configured to determine a damping control command for a respective one of the plurality of wind turbines, wherein the or each of the wind turbines includes a damping controller that receives a damping control command and which is operable to apply a damping control input to one or both of the blade pitch adjustment means and the generator power control means so as to counteract the measured vibration of the support structure.

Abstract: The invention relates to a method of controlling a wind turbine, the wind turbine comprising wind turbine blades attached to a rotor hub and a control system for pitching the blades relative to the rotor hub. The method comprises determining a wind speed and providing a normal pitch mode of operation to control the output power of the wind turbine, where the pitch mode of operation comprises pitch reference values in dependence of the wind speed. The output power of the turbine is controlled according to the normal pitch mode of operation as a function of the wind speed if the wind speed is lower than a first upper level wind speed threshold, and according to a modified mode of operation if the wind speed exceeds the first upper level threshold wind speed, wherein the modified mode of operation comprises decreasing the output power according to a de-rating function which is a function of time.

Abstract: The invention relates to a method for detecting icing and other loadings on blades of wind turbines. Advantageously, the method utilizes existing wind turbine actuators, for example pitch actuators, far excitation of blade vibrations. Vibration sensors on the blade such as strain sensors or accelerometers measure the blade vibrations excited in response to the actively excised vibrations. By comparing the measured response with previously obtained reference responses, it is possible to determine if blade icing is present.

Abstract: The invention refers to a method for de-icing a blade of a wind turbine. The de-icing is carried out by means of stalling the wind turbine and at least to a position where enough turbulence is created to induce vibrations in the blade allowing ice to break off.

Abstract: A method for operating a wind turbine includes: providing a curve defining optimal pitch angle as a function of tip speed ratio or as a function of wind speed; modifying at least a part of the optimal pitch angle curve by applying a safety buffer, thereby obtaining a safety modified pitch angle curve; operating the wind turbine in accordance with the safety modified pitch angle curve; measuring one or more parameters regarding wind conditions and/or loads on one or more component of the wind turbine; adjusting the safety buffer, based on the measurements, thereby obtaining an adjusted pitch angle curve; and operating the wind turbine in accordance with the adjusted pitch angle curve. Since the safety buffer is adjusted based on measured parameters, it can be reduced if actual operating conditions are less severe than expected. This allows the wind turbine to be operated in a more optimal manner.

Abstract: To identify abnormal behavior in a turbine blade, a failure detection system generates a “fingerprint” for each blade on a turbine. The fingerprint may be a grouping a dynamic, physical characteristics of the blade such as its mass, strain ratio, damping ratio, and the like. While the turbine is operating, the failure detection system receives updated sensor information that is used to determine the current characteristics of the blade. If the current characteristics deviate from the characteristics in the blade's fingerprint, the failure detection system may compare the characteristics of the blade that deviates from the fingerprint to characteristics of another blade on the turbine. If the current characteristics of the blade are different from the characteristics of the other blade, the failure detection system may change the operational mode of the turbine such as disconnecting the turbine from the utility grid or stopping the rotor.

Abstract: A control system for calibrating a wind turbine sensor placed on a component of a wind turbine and related methods are disclosed. The wind turbine includes a rotor having at least one wind turbine blade. The method comprises pitching one or more of the at least one of the wind turbine blades according to a predetermined pitch movement which induces a vibratory motion in the at least one turbine blade. A wind turbine sensor measures a vibratory response signal at least partly caused by the vibratory motion. A characteristic sensor response value is determined from the vibratory response signal. The characteristic sensor response value may be compared to a predetermined sensor calibration parameter to determine whether a difference is greater than a predefined tolerance parameter. In this manner, the wind turbine sensor may be calibrated.

Abstract: Methods of controlling a variable speed wind turbine generator connected to a power grid. The method may include measuring the frequency, f, of the power grid, controlling the speed of the generator for optimizing the power delivered to the power grid, and setting limits for the generator speed. The setting of the limits for the generator speed is performed in dependency of the measured frequency of the power grid. This provides a dynamical set of limits providing improved possibilities of optimizing the power production.

Abstract: According to an aspect of the invention, a wind farm is provided. The wind farm includes a plurality of wind turbines and a wind farm controller. The controller is configured to detect a high wind condition from at least one wind turbine in the wind farm, reduce a parameter setpoint of at least one other wind turbine, and increase a cut-out wind speed threshold of the at least one other wind turbine.

Abstract: in a method of controlling a variable speed wind turbine, said wind turbine comprising a double-fed asynchronous generator having rotor windings and stator windings and means for controlling the wind turbine speed, the method comprises the following steps:—measuring or calculating, based on measured parameters, the active electrical power (Pr) in the rotor windings, comparing the active electrical power (Pr) in the rotor windings with a preset limit (PrLimit), when the active electrical power (Pr) in the rotor windings exceeds the preset limit (PrLimit), controlling the wind turbine speed to minimize the difference between the active electrical power (Pr) in the rotor windings and a preset reference (PrRef). The rotor power (Pr) is kept at a reduced level, thus avoiding overload of wind turbine generator components.

Abstract: A wind turbine including a controller configured to periodically enter an Eigen frequency detection mode in which the controller gain is incremented in a controlled manner to detect the Eigen frequencies. During normal operations, the controller output may be monitored to detect the Eigen frequency which, if detected, may allow damage control operations to be undertaken.

Abstract: The invention relates to a method for detecting icing and other loadings on blades of wind turbines. Advantageously, the method utilizes existing wind turbine actuators, for example pitch actuators, far excitation of blade vibrations. Vibration sensors on the blade such as strain sensors or accelerometers measure the blade vibrations excited in response to the actively excised vibrations. By comparing the measured response with previously obtained reference responses, it is possible to determine if blade icing is present.

Abstract: A method for operating a wind turbine is disclosed. The wind turbine comprises a rotor having a set of wind turbine blades, said rotor being mounted on a tower. The method comprises the steps of: Providing a curve defining optimal pitch angle as a function of tip speed ratio for the wind turbine blades or as a function of wind speed. Modifying at least a part of said optimal pitch angle curve by applying a safety buffer, e.g. at tip speed ratios and/or pitch angles where there is a risk that the blades may stall and/or that overload is caused to the wind turbine, thereby obtaining a safety modified pitch angle curve. Operating the wind turbine in accordance with the safety modified pitch angle curve. Measuring one or more parameters providing information regarding wind conditions and/or loads on one or more components of the wind turbine, during operation of the wind turbine.

Abstract: The invention refers to a method for de-icing a blade of a wind turbine. The de-icing is carried out by means of stalling the wind turbine and at least to a position where enough turbulence is created to induce vibrations in the blade allowing ice to break off.