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EP-4118328-B1 - METHOD FOR DETERMINING A SPATIAL ARRANGEMENT OF A FLOATING WIND TURBINE RELATIVE TO ITS ENVIRONMENT

EP4118328B1EP 4118328 B1EP4118328 B1EP 4118328B1EP-4118328-B1

Inventors

  • Esbensen, Thomas
  • Laugesen, Kasper

Dates

Publication Date
20260506
Application Date
20210303

Claims (15)

  1. A sensor system for a floating wind turbine (100), the sensor system comprising a wind sensor (160) configured to provide a wind sensor signal indicative of a wind flow (110); and a processing unit (170) configured to receive the wind sensor signal and to determine, based on the wind sensor signal, information indicative of a spatial arrangement (101, 102, 103, 104, 105, 106) of a floating base (120) of the floating wind turbine (100) relative to an environment (108) of the floating wind turbine (100); wherein the information is indicative of a rotation (104, 105, 106) of the floating base (120), namely of a floater pitch (105), a floater roll (106), and/or a floater yaw (104) of the floating base (120) relative to the environment (108), and characterized in that the wind sensor signal provided by the wind sensor (160) is used for determining further information indicative of an orientation of a wind rotor (140) of the floating wind turbine (100) relative to a tower (130) and/or the floating base (120) of the floating wind turbine (100).
  2. The sensor system according to any one of the preceding claims, wherein the wind sensor (160) comprises two different wind sensor units, which are mounted on different parts of the wind turbine, and which are each configured to provide a respective wind sensor signal indicative of a wind flow, wherein the sensor system is configured to distinguish between conventional yaw of the nacelle relative to the tower and floater yaw between the floating base and the environment.
  3. The sensor system according to claim 2, wherein one of the two different wind sensor units is mounted on the nacelle, and one of the two different wind sensor units is mounted on the tower and/or on the floating base.
  4. The sensor system according to any one of the preceding claims, wherein the wind sensor (160) is configured to measure the wind flow (110) at at least two measurement points and/or in at least two measurement directions.
  5. The sensor system according to the preceding claim, wherein the processing unit (170) is further configured to determine a wind shear based on the wind sensor signal indicative of the wind flow (110) at the at least two measurement points, and wherein the processing unit (170) determines the information based on the wind shear.
  6. The sensor system according to any one of the preceding claims, wherein the wind sensor signal is indicative of a vertical angle (β) of the wind flow (110).
  7. The sensor system according to any one of the preceding claims, wherein the information is indicative of an oscillating motion of the floating base (120) relative to the environment (108), or wherein the information is indicative of a frequency, an amplitude of the oscillating motion, and/or of an oscillating rotation relative to the environment (108).
  8. The sensor system according to any one of the preceding claims, wherein the information is indicative of a rotational offset of the floating (120) base relative to the environment (108).
  9. The sensor system according to any one of the preceding claims, wherein the processing unit (170) is further configured to determine whether the spatial arrangement (101, 102, 103, 104, 105, 106) of the floating base (120) satisfies a threshold criterion.
  10. The sensor system according to any one of the preceding claims, wherein the information is determined based on the assumption that a wind direction (211) of the wind flow (110) is horizontal.
  11. The sensor system according to any one of the preceding claims, wherein the information is indicative of a wind direction (211) relative to a reference direction (213), wherein the reference direction (213) is defined relative to the floating wind turbine (100), in particular relative to the floating base (120) and/or a tower (130) of the floating wind turbine (100).
  12. A floating wind turbine (100) comprising the sensor system according to any one of claims 1 to 11.
  13. The floating wind turbine (100) according to the preceding claim, further comprising a control system, wherein the information is indicative of a wind direction (211) relative to a reference direction (213), wherein the reference direction (213) is defined relative to the floating wind turbine (100), in particular relative to the floating base (120) and/or a tower (130) of the floating wind turbine (100), and wherein the control system is configured to rotate the floating wind turbine (100) such that the reference direction (213) is aligned with the wind direction (211).
  14. A method of operating a floating wind turbine (100) comprising: providing, by means of a sensor system according to one of the claims 1 to 11, a wind sensor signal indicative of a wind flow (110); receiving, by means of a processing unit (170), the wind sensor signal; and determining, by means of the processing unit (170) and based on the wind sensor signal, information indicative of a spatial arrangement (101, 102, 103, 104, 105, 106) of a floating base (120) of the floating wind turbine (100) relative to an environment (108) of the floating wind turbine (100).
  15. The method according to claim 14 comprising the step of using the the wind sensor signal provided by the wind sensor (160) for determining further information indicative of an orientation of a wind rotor (140) of the floating wind turbine (100) relative to a tower and/or the floating base of the floating wind turbine (100), and/or for determining further information on the basis of which a mode of operation of the wind turbine (100) may be set, namely whether or not to shut down the wind turbine (100).

Description

Field of invention The present invention relates to the technical field of floating wind turbines as well as to methods of operating such wind turbines. Art Background Standard onshore or offshore non-floating wind turbines do not have dedicated sensors installed to measure the additional degrees of freedom that a floating wind turbine has. Measuring rigid body rotations is relevant in order to control or monitor the stability of the wind turbine system. For example, the floater pitch angle information is relevant, since a floating wind turbine may have to be stabilized by control of floater pitch. However, this information is in general not available. Conventionally, two approaches are known. According to a first approach, information is determined indicating change in floater pitch or floater pitch movement from nacelle accelerometers or tower accelerometers that are typically present as standard sensors in most wind turbines. However, the absolute floater pitch angle can hardly be known from this approach. JP 2005 264865 A provides a windmill device having improved durability by reducing loads of a supporting column and a connection portion between the supporting column and a nacelle by the vibration of a float. It comprises a propeller mounted on the bottom of the float for propelling the float, a steering device for steering the propeller to change the direction of the float, and a control device for controlling the steering device according to the direction of wind of an air flow. The control device controls the steering device according to the direction of the wind to change the direction of the float following the direction of the wind. US 2011074155 A1 discloses a floating offshore wind turbine and a floating offshore wind farm with at least one floating offshore wind turbine. The floating offshore wind turbine includes a floating platform anchored to an underwater ground, a wind turbine mounted on the floating platform, and a drive. The drive is adapted to horizontally move the floating platform. Further a method for positioning a floating offshore wind turbine is provided. EP 2 807 373 A1 shows an assembly formed by a wind turbine and a floating platform. The assembly is allowing an orientation of the platform in order to obtain conditions of maximum efficiency in the wind turbine. It comprises first sensors for detecting an effective rotation axis angle formed between the rotation axis and a horizontal plane, second sensors for detecting wind direction, platform orientation means for modifying the effective rotation axis angle, and a control unit adapted for receiving a first input from the first sensors and a second input from the second sensors. According to a second approach, information about the floater pitch angle is determined by adding further sensors to the system, such as a sensor determining the inclination angle of the turbine, the tower, or the support structure of the floating wind turbine. Accordingly, there may be a need for a reliable and efficient method to determine spatial degrees of freedom of the floating wind turbine such as floater pitch. Summary of the Invention This need may be met by the subject matters according to the independent claims. Advantageous embodiments of the present invention are described by the dependent claims. According to an aspect of the invention, a sensor system for a floating wind turbine comprises a wind sensor configured to provide a wind sensor signal indicative of a wind flow. The sensor system further comprises a processing unit configured to receive the wind sensor signal and to determine, based on the wind sensor signal, information indicative of a spatial arrangement of a floating base of the floating wind turbine relative to an environment of the floating wind turbine. According to a further aspect of the invention, a method of operating a floating wind turbine comprises (i) providing, by means of a wind sensor, a wind sensor signal indicative of a wind flow; (ii) receiving, by means of a processing unit, the wind sensor signal; and (iii) determining, by means of the processing unit and based on the wind sensor signal, information indicative of a spatial arrangement of a floating base of the floating wind turbine relative to an environment of the floating wind turbine. In the context of the present application, a "wind turbine" is any device that is configured to convert wind energy into electrical energy, in particular for distribution to a grid and/or for local energy supply. A wind turbine may comprise a tower, a wind rotor, a nacelle, a shaft, in particular a low-speed shaft and/or a high-speed shaft, a gearbox, a generator, a brake assembly, a pitch drive, and/or a yaw drive. The wind rotor may be a rotor assembly and may comprise one or more blades and a central hub, to which the blades are attached. The wind rotor may further comprise pitch bearings connecting the rotor hub with the blades. With the pitch bearings, an orientation o