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EP-4739904-A1 - IMPROVEMENTS RELATING TO COMMISSIONING OF WIND TURBINES

EP4739904A1EP 4739904 A1EP4739904 A1EP 4739904A1EP-4739904-A1

Abstract

A method of commissioning a wind turbine, wherein the wind turbine comprises a tower extending along a tower axis (X), a tower top and at least one connection flange, the wind turbine having a tower damping system actuatable to control oscillatory movement of the tower, in use. The method comprises: controlling the tower damping system during a tower-settling phase of operation to cause the tower top to move in a plurality of directions (F1-F4) about at least a part of the tower axis to release residual stress in the at least one connection flange of the tower of the wind turbine. A benefit of the invention is the release of stresses built in during the manufacturing of tower sections of the wind turbine can be released rapidly allowing a more efficient commissioning process to be achieved.

Inventors

  • MORTENSEN, Peter Sigfred

Assignees

  • VESTAS WIND SYSTEMS A/S

Dates

Publication Date
20260513
Application Date
20240618

Claims (12)

  1. 1. A method (100) of commissioning a wind turbine (10), wherein the wind turbine comprises a tower (12) extending along a tower axis (X), a tower top and at least one connection flange (25), the wind turbine having a tower damping system (85,87) actuatable to control oscillatory movement of the tower, in use, the method comprising: controlling the tower damping system during a tower-settling phase of operation to cause the tower top to move in a plurality of directions (F1-F4) about at least a part of the tower axis so as to release residual stress in the at least one connection flange (25) of the tower of the wind turbine.
  2. 2. The method of Claim 1 , wherein controlling the tower damping system causes the tower top to move in a plurality of directions completely encircling the tower axis.
  3. 3. The method of Claim 2, wherein controlling the tower damping system causes the tower top to follow a generally circular path (F5) about the tower axis.
  4. 4. The method of any one of the preceding claims, wherein the step of controlling the tower damping system further comprises: determining a minimum load profile (104) for the at least one flange connection of the tower which represents the minimum load to be applied to the at least one flange connection in a plurality of directions extending about a tower axis, based on the required load profile, determine (108) a first control signal component in respect of a side-side component of oscillatory tower movement; based on the required load profile, determining (108) a second control signal component in respect of a fore-aft component of the oscillatory tower movement; and wherein the first and second control signal components are configured such that the tower damping system causes an increase in oscillatory tower movement in the horizontal plane such that the load applied to the at least one flanged connection exceeds the determined minimum load profile.
  5. 5. The method of Claim 4, wherein the control signal components are configured such that the load applied to the at least one flanged connection meets a target magnitude in exceedance of the determined load profile.
  6. 6. The method of Claim 4 or 5, wherein the determined load profile corresponds to a predetermined service load limit of the tower.
  7. 7. The method of any one of the preceding claims, wherein the tower-settling phase of operation is controlled remotely from the wind turbine.
  8. 8. A method (200) of commissioning a wind turbine (10), wherein the wind turbine comprises a tower (12) extending along a tower axis (X), a tower top having a nacelle (14), and at least one connection flange (25), the method comprising controlling the wind turbine during a tower-settling phase of operation, including the steps of: starting (206) the wind turbine and controlling a yaw system of the wind turbine so that the nacelle faces in a first one of a predetermined plurality of directions relative to the tower axis, performing (210) an emergency stop of the wind turbine whilst the nacelle faces in the first one of the predetermined plurality of directions; repeating (212) the steps of starting the wind turbine, controlling the yaw system, and performing an emergency stop of the wind turbine for each one of the predetermined plurality of directions, thereby to increase the loading applied to the tower in each of the predetermined plurality of directions, so as to release residual stress in the at least one connection flange of the tower of the wind turbine.
  9. 9. The method of any one of the preceding claims, further comprising: stopping operation of the wind turbine following the tower-settling phase of operation, and re-tensioning of bolts in one or more of the at least one flanged connection of the tower.
  10. 10. A controller (50) for a wind turbine control system comprising a processor (62) and a memory module (64), wherein the memory module comprises a set of program code instructions which when executed by the processor implements a method according to any one of Claims 1 to 8.
  11. 11. A wind turbine (10) comprising a tower (12), and a controller (50) according to Claim 10.
  12. 12. A computer program product downloadable from a communication network and/or stored on a machine readable medium comprising program code instructions for implementing a method according to any one of Claims 1 to 8.

Description

IMPROVEMENTS RELATING TO COMMISSIONING OF WIND TURBINES Technical Field This disclosure relates to systems, apparatus and methods for controlling side-side and fore-aft oscillatory movement of a wind turbine during wind turbine installation. Aspects of the invention relate to a wind turbine and a method for controlling the wind turbine, together with a controller for the wind turbine and a computer program product. Background Wind turbines are complex structures that require regular maintenance and inspection to ensure their safe and efficient operation. One critical aspect of wind turbine maintenance is the inspection and maintenance of bolted connections which are used to join various components of the wind turbine together. For example, typically bolted connections are used at the flanged interface between a foundation of a wind turbine and the lowermost tower section in order to provide a secure connection of the wind turbine to the foundation. Flanged interfaces are also present between mutually adjoining tower sections that make up a wind turbine tower. Flanged interfaces in general are highly stressed during use and so the establishment of a bolted connection at the flanged interface is a crucial part of the installation process to achieve a long operating life of the wind turbine. The bolts in the bolted connection are typically pre-tensioned as part of the installation process which improves the robustness of the flanged interface. However, after installation, residual stress in the flanged connection may release over time which reduces the pretension in the bolts. This effect may compromise the fatigue life of the bolts, which is undesirable. Although bolt pretension can be measured and corrected, this may only take place after a considerable period of wind turbine operation. Furthermore, this is a time consuming and physically demanding task. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. Summary of the Invention According to a first aspect of the invention, there is provided a method of commissioning a wind turbine, wherein the wind turbine comprises a tower extending along a tower axis (X), a tower top and at least one connection flange, the wind turbine having a tower damping system actuatable to control oscillatory movement of the tower, in use, the method comprising: controlling the tower damping system during a tower-settling phase of operation to cause the tower top to move in a plurality of directions (F1-F4) about at least a part of the tower axis so as to release residual stress in the at least one connection flange of the tower of the wind turbine. In this respect, the term 'commissioning’ may be considered to be the process of setting up a wind turbine for operation. During commissioning, the wind turbine may be run so as to produce power and to export that power to a power grid. Power export may be below typical nominal levels, however, due to the control functions implemented in the wind turbine systems during such commissioning process. A benefit of the invention is that the release of stresses built in during the manufacturing and assembly of tower sections of the wind turbine can be released rapidly during application of control algorithms that are conventionally used to control damping of oscillatory motion of the wind turbine. Hence any concerns related to later release of such stresses and implications on flange bolt pre-tension, buckling or fatigue strength of weldings can be eliminated in a short and controlled manner. In one example, controlling the tower damping system causes the tower top to move in a plurality of directions completely encircling the tower axis. Thus, the damping system is adapted to cause the tower to oscillate or vibrate in specifically selected directions in order to release residual stress in a controlled way. By controlling the damping system so that the tower oscillates in many different directions about the tower axis, stress relief can be achieved in a uniform way. Notably, the damping system is used here in a way that is not conventional. As is known, the damping system is used conventionally to reduce oscillatory motion of the wind turbine tower, whereas in the examples of the invention the damping system is used to increase, enhance or augment oscillatory tower motion to achieve a stress relieving function. The effect may be enhanced by controlling the damping system such that the induced oscillations of the tower have a frequency near to or substantially at the eigenfrequency of the tower. In another example, controlling the tower damping system causes the tower top to follow a generally circular path (F5) about the tower axis. This achieves uniforms applications of loads about the tower axis but in a different manner than described previously. In another aspect, the examples of the invention provide a method of commissioning a wind turbine, wherein the wind turbine comprise