DK201870867A1 - Apparatus and method for rotating a rotor of a wind turbine - Google Patents

Abstract

The present invention provides apparatus for rotating a rotor of a wind turbine. The apparatus includes a rotatable control element in the form of a locking disc associated with the rotor, and rotation of the locking disc causes rotation of the rotor. The locking disc has a number of engagement holes around its periphery. The apparatus includes a drive shoe having a number of engaging pins movable between an engaged position in which the pins engage with the engaging holes such that movement of the drive shoe causes rotation of the locking disc and a disengaged position in which the drive shoe is movable relative to the locking disc. The apparatus has two linear drives such as hydraulic drives each movable between extended and retracted positions and each connected to the drive shoe. When the engaging pins are in the engaged position a first of the linear drives moves towards the retracted position, and the other of the linear drives moves towards the extended position, to cause movement of the drive shoe and rotation of the locking disc.

Description

APPARATUS AND METHOD FOR ROTATING A ROTOR OF A WIND TURBINE

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for rotating a rotor of a wind turbine and, in particular, to an apparatus and method for rotating the rotor during installation or maintenance of the wind turbine. Aspects of the invention relate to an apparatus and to a method.

BACKGROUND

Wind turbines for power generation are well known in the art. In a common arrangement, a nacelle is mounted on a tower, with a rotor being mounted on the nacelle, and a plurality of blades being mounted on the rotor. The rotor is mounted on a rotor shaft or ‘low-speed’ shaft which is supported in the nacelle by a shaft or bearing housing. A gearbox is located in the nacelle, with the low-speed shaft being mounted to the gearbox to connect the gearbox to the rotor. A generator is also located in the nacelle, and a ‘high-speed’ shaft is mounted to the gearbox and connects the gearbox with the generator.

When installing a wind turbine, the rotor and blades are typically mounted to the nacelle after the tower has been positioned on-site and the nacelle has been mounted atop the tower. The rotor includes a rotor hub which is mounted to the already-installed nacelle, and then each blade is installed successively to the rotor hub. In particular, it is common to install each blade at a particular predefined angular position of the rotor hub so that each blade may be mounted from a particular direction. After a first blade has been mounted to the rotor hub, the rotor hub must therefore be rotated through a predefined angle so that the second blade may be mounted to the rotor hub from the same direction. For example, for a wind turbine having three blades equally spaced in the angular direction the rotor hub must be rotated through an angle of 120° between mounting each successive blade.

Typically, rotation of the rotor hub during installation is initiated by a drive device or turner device which applies a drive torque to the high-speed shaft. The resulting rotation of the high-speed shaft is transferred through the gearbox to cause rotation of the lowspeed shaft and therefore of the rotor and rotor hub.

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When all three of the blades are mounted to the rotor hub, rotating the rotor in this manner is relatively simple as the rotor is balanced. When only one or two of the blades are mounted to the rotor hub, however, the rotor is unbalanced and the level of torque needed to rotate the rotor is relatively large and, in particular, significantly larger than during normal operation of the wind turbine when all of the blades are mounted to the rotor hub.

In conditions of sufficiently high wind speeds, the torque required to rotate an unbalanced rotor may be higher than a maximum torque capacity of the gearbox. This can result in costly delays during installation of a wind turbine until there is a reduction in wind speed.

One way of addressing this issue is to design one or more components of the drivetrain/gearbox so that they may withstand the high loads experienced during such conditions. However, these high loads may only be experienced on a single occasion during the entire lifetime of the wind turbine. This means that the gearbox may be significantly ‘over-dimensioned’ in relation to its dimensional requirements during normal operating conditions (for a balanced rotor), i.e. the gearbox is over-dimensioned for the vast majority of the wind turbine lifespan. Such over-dimensioning increases the cost of the gearbox, which is already a particularly expensive component to manufacture and maintain.

It is an aim of the present invention to address disadvantages associated with the prior art.

SUMMARY OF INVENTION

According to an aspect of the present invention there is provided an apparatus for rotating a rotor of a wind turbine. The apparatus may comprise a rotatable control element associated with the rotor, wherein rotation of the control element causes rotation of the rotor, the control element comprising a plurality of engagement formations. The apparatus may comprise a drive element including engaging means movable between an engaged position in which the engaging means engages with the engagement formations such that movement of the drive element causes rotation of the control element and a disengaged position in which the drive element is movable relative to the

DK 2018 70867 A1 control element. The apparatus may comprise first and second linear drives each movable between extended and retracted positions and each connected to the drive element, wherein when the engaging means is in the engaged position the first linear drive may be configured to move towards the retracted position and the second linear drive may be configured to move towards the extended position to cause movement of the drive element and rotation of the control element.

The first and second linear drives may be considered to be an antagonistic pair of linear drives which respectively ‘push’ and ‘pull’ the control element in order to rotate the control element, and thereby split the load needed to cause such rotation. Note that the control element may be rotated in either direction using the first and second linear drives.

The first linear drive may be arranged to move from a fully extended state to a fully retracted state to rotate the control element, or may be arranged to move partially between these extreme positions to rotate the control element.

The control element may be at least part-circular in form, and the engagement formations may be disposed on a periphery of the control element.

The engagement formations may be in the form of holes, and the engaging means may include at least one pin.

The apparatus may comprise locking means movable between a locked position in which the locking means cooperates with the engagement formations to restrain movement of the control element relative to a housing and/or a main frame of the wind turbine, and an unlocked position in which the control element is rotatable relative to the locking means.

Advantageously, in such embodiments both the engaging means of the drive element and the locking means cooperate with the engagement formations of the control element. This simplifies manufacture in that a separate set of engagement formations is not needed, and means that a current locking disc of a wind turbine may be used in its current form, or relatively easily adapted, to include the turner tool components, i.e. the drive element and the linear drives, of the present invention. That is, there is extensive re-use of an existing structure of the wind turbine.

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The apparatus may be located between the rotor and a gearbox of the wind turbine, and the control element may be associated with a low-speed shaft of the wind turbine connecting the rotor and the gearbox. Typically, few other components reside in this area of a wind turbine and so the apparatus of the present invention may be readily incorporated at this location. Advantageously, the second drive means may be used to rotate the rotor into a position where the locking means may be moved to the locked position in case of failure of one or more drivetrain components, such as the gearbox, and/or when the drivetrain is being unmounted.

When the engaging means is in the disengaged position and the locking means is in the locked position the first linear drive may be configured to move towards the retracted position and the second linear drive may be configured to move towards the extended position to cause movement of the drive element relative to the control element.

The first and second linear drives may each include a hydraulic cylinder. Hydraulic pressure may be applied in the hydraulic cylinders to cause the first and second linear drives to move between the extended and retracted positions. In particular, the first and second linear drives may be in the form of hydraulic ram-style drives. Such hydraulic cylinders may be relatively common constructions elements, and so the turner tool may be a relatively inexpensive addition to a wind turbine.

The engaging means may be operable to move between the engaged and disengaged positions via hydraulic power.

The apparatus may comprise a further drive element including further engaging means movable between an engaged position in which the further engaging means engages with the engagement formations such that movement of the further drive element causes rotation of the control element and a disengaged position in which the further drive element is movable relative to the control element. The apparatus may comprise third and fourth linear drives each movable between extended and retracted positions and each connected to the further drive element. When the further engaging means is in the engaged position the third linear drive may be configured to move towards the extended position and the fourth linear drive may be configured to move towards the retracted position to cause movement of the further drive element and rotation of the control element.

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By providing four linear drives in the form of two antagonistic pairs, a better distribution of the load needed to rotate the control element between the linear drives is achieved. This also allows each of the linear drives to be relatively compact as each of the linear drives only needs to provide a smaller proportion of the required drive torque to turn the control element. Note also that the closer the engagement formations are to each other, the more compact (or shorter or smaller) the linear drives can be as each rotation cycle only needs to rotate the control element by a smaller amount. The provision of four linear drives increases the amount of drive torque that may be applied to the control element.

The further drive element may be arranged on a side of the control element opposite to that of the drive element. Advantageously, in such embodiments the applied torque may be split evenly on both sides of the control element.

The first and fourth linear drives may be rotatably mounted along a first rotation axis to a housing and/or a main frame of the wind turbine. The second and third linear drives may be rotatably mounted along a second rotation axis to the housing and/or the main frame. The second rotation axis may be different from the first rotation axis. Advantageously, in such embodiments only two connecting points to connect the four linear drives to the structure of the wind turbine are needed. Again, this simplifies manufacture and limits the number of additional components needed to adapt a current wind turbine layout or arrangement to include the turner tool of the present invention.

The control element may include an aperture arranged to receive a low-speed shaft of the wind turbine. Rotation of the control element may cause rotation of the low-speed shaft so as to rotate the rotor.

According to another aspect of the present invention there is provided a method of rotating a rotor of a wind turbine. The wind turbine may comprise a rotatable control element associated with the rotor, wherein rotation of the control element causes rotation of the rotor, and the control element may comprise a plurality of engagement formations. The wind turbine may comprise a drive element including engaging means movable between an engaged position in which the engaging means engages with the engagement formations such that movement of the drive element causes rotation of the control element and a disengaged position in which the drive element is movable relative to the control element. The wind turbine may comprise first and second linear drives each movable between extended and retracted positions and each connected to the

DK 2018 70867 A1 drive element. The method may comprise actuating the engaging means from the disengaged position to the engaged position. The method may comprise actuating the first linear drive towards the retracted position and actuating the second linear drive towards the extended position to cause movement of the drive element and rotation of the control element. Actuation of the first and second linear drives may be effected substantially simultaneously.

The wind turbine may comprise locking means movable between a locked position in which the locking means cooperates with the engagement formations to restrain movement of the control element relative to a housing and/or a main frame of the wind turbine, and an unlocked position in which the control element is rotatable relative to the locking means. The method may comprise actuating the locking means from the locked position to the unlocked position between actuating the engaging means and actuating the first and second linear drives.

The method may comprise the successive steps of:

(i) actuating the locking means from the unlocked position to the locked position;

(ii) actuating the engaging means from the engaged position to the disengaged position; and, (iii) substantially simultaneously actuating the first linear drive towards the retracted position and actuating the second linear drive towards the extended position to at least partially reset a position of the drive element relative to the control element, wherein steps (i)-(iii) are performed prior to actuating the engaging means and/or after actuating the first and second linear drives.

Advantageously, in certain embodiments each of the linear drives may be moved simultaneously relative to the control elements to reset their positions as the locking means ensures that the control element remains fixed in position during such movement. Expressed differently, one of the linear drives does not need to remain engaged with the control element to ensure the control element remains stationary while another of the linear drives resets its position as the locking means provides this functionality.

According to another aspect of the present invention there is provided a wind turbine comprising an apparatus as described above.

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BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:

Figure 1 is a diagram illustrating a front view of a wind turbine arrangement according to an aspect of the invention;

Figure 2 is a schematic plan view of a drivetrain of the wind turbine arrangement of Figure 1, the drivetrain including a high-speed shaft drive and a low-speed shaft drive for rotating a rotor of the wind turbine arrangement;

Figures 3a-d show various views of the low-speed drive of Figure 2;

Figure 4 shows a perspective view of part of a component part of the low-speed drive of Figure 2;

Figure 5 shows the steps of a method of rotating the rotor of the wind turbine arrangement of Figure 1; and,

Figures 6a-g show various configurations of the low-speed shaft drive of Figure 2.

DETAILED DESCRIPTION

Figure 1 shows a wind turbine arrangement 10, or simply a wind turbine, according to an embodiment of the invention. The arrangement 10 includes a tower 12, a nacelle 14 rotatably coupled to the top of the tower 12 by a yaw system, a rotor including a rotor hub 16 mounted to the nacelle 14 and a plurality of wind turbine rotor blades 18 coupled to the rotor hub 16. The nacelle 14 and rotor blades 18 are turned and directed into the wind direction by the yaw system. The nacelle 14 houses generating components (not shown) of the wind turbine, including the generator, gearbox, drivetrain and brake assembly, as well as convertor equipment for converting the kinetic energy of the wind into electrical energy for provision to the grid. The wind turbine is shown in its fullyinstalled form suitable for operation; in particular, the rotor 16 is mounted on the nacelle 14 and each of the blades 18 are mounted on the rotor and rotor hub 16.

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Figure 2 shows a schematic plan view of a drivetrain 20 located in the nacelle 14 of the wind turbine 10. The rotor 16 is coupled to a generator 22 for harnessing the captured wind energy. In particular, the rotor 16 is coupled to the generator 22 via a gearbox 24 and two rotatable shafts 26, 28. Specifically, the rotor 16 is connected to the gearbox 24 via a so-called ‘low-speed’ shaft 26 (also referred to as a rotor shaft, driveshaft or main shaft), and the gearbox is then connected to the generator 22 via a so-called ‘highspeed’ shaft 28. The rotor 16 is connected to the low-speed shaft 26 such that rotation of the low-speed shaft 26 causes rotation of the rotor 16.

The wind turbine includes two drive or turner devices 30, 32. A first (or high-speed) drive device 30 is positioned between the generator 22 and the gearbox 24, in particular along or adjacent to the high-speed shaft 28. The high-speed drive device 30 is arranged to apply drive torque to the high-speed shaft 30 so as to cause rotation of the high-speed shaft 30. This causes rotation of the low-speed shaft 26 through the gearbox 24, and therefore rotation of the rotor 16.The high-speed drive device 30 may be any suitable drive device. In the described embodiment, the high-speed drive device 30 is a rotary drive device including a plurality of hydraulic motors.

A second (or low-speed) drive device 32 is positioned between the rotor 16 and the gearbox 24, in particular along or adjacent to the low-speed shaft 26. The low-speed drive device 32 is arranged to apply drive torque to the low-speed shaft 26 so as to cause rotation of the low-speed shaft 26 and therefore the rotor 16.

Figures 3a-d show various views of the low-speed drive device 32 of the described embodiment. In particular, Figures 3a-d show the low-speed shaft 26 and a housing or casing 34 of a bearing of the low-speed shaft 26 with the low-speed drive device 32 adjacent the low-speed shaft housing 34 and engaging with the low-speed shaft 26.

A rotatable locking disc 36 completely surrounds the low-speed shaft 26 and is adjacent to the low-speed shaft 26. The locking disc 36 is generally of annular shape and receives the low-speed shaft 26 therethrough in a relatively tight fit so that rotation of the locking disc 36 causes rotation of the low-speed shaft. That is, the locking disc 36 has an aperture 37 that receives the low-speed shaft 26. The locking disc or plate 36 is located adjacent to the rotor and rotor hub 16.

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The low-speed shaft 26 and the locking disc 36 are rotatable relative to the shaft housing 34, but such rotation of the low-speed shaft 26 and the locking disc 36 may be restrained or restricted, i.e. the low-speed shaft 26 and the locking disc 36 may be locked relative to the housing 34. In particular, rotation of the locking disc 36 relative to the housing 34 may be restricted by locking means including locking pins 40 attached to, or part of, the housing 34. In the described embodiment there are two locking pins 40, one on each side of the housing 34 opposite each other. In turn, the outer edge or periphery 38 of the locking disc 36 has a number of equally-spaced holes or recesses 42 or, more generally, engagement formations 42. The locking pins 40 are adjacent to the periphery of the locking disc 36 and may engage with the engagement formations 42 to lock the locking disc 36 relative to the shaft or bearing housing 34.

The locking pins 40 are movable between unlocked and locked positions. In the unlocked position, the locking pins 40 are retracted away from the locking disc 36. As such, the locking pins 40 do not engage or cooperate with the engagement formations 42 of the locking disc 36 and therefore do not restrict rotation of the locking disc 36 relative to the housing 34. In the locked position, each of the locking pins 40 is lined up with, and received in, a corresponding engagement formation 42 of the locking disc 36. The locking pins 40 are fixed relative to the shaft housing 34 when in the locked position, and the locking pins 42 engage or cooperate with the engagement formations 42 of the locking disc 36 to restrict or prevent rotation of the locking disc 36 (and therefore the lowspeed shaft 26). The locking disc 36 is also referred to as a control element as it controls relative rotation between the low-speed shaft 26 and the housing 34.

Figures 3a-d also show that the low-speed drive device 32 includes two drive shoes or drive elements 38, 39 disposed along the periphery of the locking disc 36, in particular substantially on opposite sides of the locking disc 36. With additional reference to Figure 4, which shows part of one of the drive elements, each drive element 38, 39 is generally arc-shaped having two arc-shaped side walls 44a, 44b and connected at one end by an end wall 44c. The side walls 44a, 44b and end wall 44c define a gap 45 for receiving part of the edge of the locking disc 36. The drive elements 38, 39 also each include two circular flange portions 46a, 46b extending from one of the side walls 44a and two holes or apertures 48a, 48b through the side walls 44a, 44b and the circular flange portions 46a, 46b. The drive elements 38, 39 also each include corresponding pins 50a, 50b that may be extended into, or retracted from, the holes 48a, 48b.

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The drive element holes 48a, 48b are of similar dimensions to the engagement formations 42 of the locking disc 36, and the drive elements 38, 39 receive the edge of the locking disc 36 therebetween. The drive element pins 50a, 50b are movable between engaged and disengaged positions. In particular, in the disengaged position the drive element pins 50a, 50b are retracted from the drive element holes 48a, 48b and also the engagement formations 42 of the locking disc 36. That is, in the disengaged position the drive element pins 50a, 50b do not cooperate with, and are distant from, the engagement formations 42 such that relative movement of the drive elements 38, 39 and the locking disc 36 is permitted.

In contrast, in the engaged position the drive elements 38, 39 are arranged relative to the locking disc 36 such that the engagement formations 42 are adjacent to the drive element holes 48a, 48b, and the drive element pins 50a, 50b are inserted into, or received through, the engagement formations 42 of the locking disc 36. That is, in the engaged position the drive element pins 50a, 50b cooperate with the engagement formations 42 such that relative movement of the drive elements 38, 39 and the locking disc 36 is not permitted. Specifically, in the engaged position movement of the drive elements 38, 39 causes rotation of the locking disc 36.

The drive element pins 50a, 50b may be more generally referred to as engaging means, and the engaging means is movable between the engaged and disengaged positions using hydraulic power as will be described further below.

The low-speed drive device 32 also includes four linear drives 52a, 52b, 52c, 52d, in particular hydraulic linear drives each including a hydraulic cylinder 54a, 54b, 54c, 54d and piston 56a, 56b, 56c, 56d. The hydraulic pressure in the hydraulic cylinders 54a, 54b, 54c, 54d may be adjusted so as to cause linear movement of the pistons 56a, 56b, 56c, 56d relative to the cylinders 54a, 54b, 54c, 54d. In particular, each cylinder has a rod end and a cap end. Specifically, the pistons 56a, 56b, 56c, 56d are extended by applying pressure and flow in the cap-end chamber and by connecting the rod-end chamber to a hydraulic pressure tank. The pistons 56a, 56b, 56c, 56d are retracted by applying pressure and flow in the rod-end chamber and by connecting the cap-end chamber to a hydraulic pressure tank. In the described embodiment, the four linear drives 52a, 52b, 52c, 52d are identical.

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Two of the linear drives 52a, 52b are associated with one of the drive elements 38, and the other two of the linear drives 52c, 52d are associated with the other drive element 39. Focussing firstly on the first drive element 38 and the first pair of linear drives 52a, 52b, a first one of the linear drives 52a is rotatably fixed or attached at one end to the shaft housing 34 or main frame of the wind turbine 10, and rotatably fixed or attached at the other end to one of the circular flange portions 46a of the drive element 38. Similarly, a second of the linear drives 52b is rotatably fixed or attached at one end to the shaft housing 34 or main frame of the wind turbine 10, and rotatably fixed or attached at the other end to the other of the circular flange portions 46b of the drive element 38.

In more detail, the hydraulic cylinder 54a of the first linear drive 52a is attached to the housing 34 at an opposite side of the locking disc 36 from which the hydraulic cylinder 54b of the second linear drive 52a is attached to the housing 34. Also, the piston 56a of the first linear drive 52a is attached to the first circular flange portion 46a and the distal end of the piston 46a is shaped to engage with and receive the first circular flange portion 46a. The piston 56b of the second linear drive 52b is shaped in a corresponding manner to engage with the other circular flange portion 46b.

It is seen that when the first linear drive 52a is in the extended position, i.e. the piston 56a extends out of the cylinder 54a, the second linear drive 52b is in the retracted position, i.e. the piston 56b is retracted into the cylinder 54b, and vice versa. This will be discussed further below.

The other drive element 39 and the other pair of linear drives 52c, 52d are arranged in a similar manner to the first drive element 38 and the first pair of linear drives 52a, 52b. In particular, one of the other pair of linear drives, referred to as the third linear drive 52c, is rotatably attached to the shaft housing 34 at generally the same point as the second linear drive 52b. Similarly, the remaining linear drive, referred to as the fourth linear drive 52d, is rotatably attached to the shaft housing 34 at generally the same point as the first linear drive 52b.

The first and fourth linear drives 52a, 52d are rotatable relative to the housing 34 along a common, first rotation axis 58, and the second and third linear drives 52b, 52c are rotatable relative to the housing 34 along a common, second rotation axis 60. As seen in Figures 3a-d, the first and second axes 58, 60 are located on opposite sides of the locking disc 36.

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It is seen that when the third linear drive 52c is in the extended position, the fourth linear drive 52d is in the retracted position. Furthermore, the first and third linear drives 52a, 52c are generally on opposite sides of the locking disc 36: when the first linear drive 52a is in the extended position, the third linear drive 52c is also in the extended position; and, when the first linear drive 52a is in the retracted position, the third linear drive 52c is also in the retracted position. Similarly, the second and fourth linear drives 52b, 52d are generally on opposite sides of the locking disc 36: when the second linear drive 52b is in the extended position, the fourth linear drive 52d is also in the extended position; and, when the second linear drive 52b is in the retracted position, the fourth linear drive 52d is also in the retracted position.

Figure 5 shows the steps of a method 70 of mounting the blades 18 to the rotor hub 16 of the wind turbine 10 using the high-speed drive 30 and the low-speed drive 32. As outlined above, the blades 18 are to be mounted to the rotor hub 16 once the wind turbine tower 12, nacelle 14, and rotor and rotor hub 16 have already been installed. In particular, each of the three blades 18 are to be mounted one at a time and from generally the same direction to aid ease of installation. The rotor 16 must therefore be rotated through generally 120° between mounting each of the blades 18 to the hub.

The rotor is rotated so that the rotor hub 16 is at the appropriate angular position to receive the first of the blades 18. Both the high-speed drive 30 and the low-speed drive 32 are used to rotate the rotor 16. In particular, the high-speed drive 30 is arranged to apply drive torque to the high-speed shaft 28 and, substantially simultaneously, the lowspeed drive 32 is arranged to apply drive torque to the low-speed shaft 26.

In order that the low-speed drive 32 may be used to cause rotation of the low-speed shaft 26, the low-speed shaft 26 must be unlocked from the housing 34 and the first and second drive elements 38, 39 must be engaged with the locking disc 36. Figure 6a shows an initial state of the low-speed drive 32 in which the locking pins 40 are in the locked position and the drive element pins 50a, 50b of both drive elements 38, 39 are in the disengaged position. It is also seen that the four linear drives 52a, 52b, 52c, 52d are in an initial or reset position whereby the first and third linear drives 52a, 52c are in the extended position, and the second and fourth linear drives 52b, 52d are in the retracted position.

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Therefore, at step 72 the drive element pins 50a, 50b are actuated using hydraulic power to move from the disengaged position to the engaged position, i.e. the pins 50a, 50b are now inserted into, and cooperate with the engagement formations 42 of the locking disc 36. This configuration of the low-speed drive 32 is illustrated in Figure 6b.

Next, at step 74 the locking pins 40 are actuated to move from the locked position to the unlocked position, i.e. the locking pins 40 no longer cooperate with the engagement formations 42 of the locking disc 36. The wind turbine 10 includes sensors, for example inductive proximity sensors, to ensure that the locking pins 40 have been fully retracted from the engagement formations 42 before proceeding to the next step. This configuration of the low-speed drive 32 is illustrated in Figure 6c.

At step 76, the high-speed drive 30 is controlled to apply drive torque to the high-speed shaft 28 and, substantially simultaneously, the low-speed drive 32 is controlled to apply drive torque to the low-speed shaft 26. In particular, in order for the low-speed drive to apply torque to the low-speed shaft 26, pressure in the hydraulic cylinders 54a, 54b, 54c, 54d must be applied. The pistons 56a, 56c apply a linear ‘pulling’ force to the drive elements 38, 39, respectively, and the pistons 56b, 56d apply a linear ‘pushing’ force to the drive elements 38, 39, respectively. That is, the first and third linear drives 52a, 52c move from their extended to the retracted positions, and the second and fourth linear drives 52b, 52d move from their retracted to extended positions.

In turn, this causes the drive elements 38, 39 to apply a force to the locking disc 36 via the interaction or cooperation between the drive element pins 50a, 50b and the engagement formations 42. The drive elements 38, 39 move and so the locking disc 36 and the low-speed shaft 26 begin to rotate. In other words, the drive elements 38, 39 convert the linear drive torque of the linear drives 52a, 52b, 52c, 52d to be converted into rotational drive torque of the locking disc 36. The low-speed shaft 26 and rotor 16 are rotated until the rotor hub is in the appropriate position to accept or receive the first of the blades 18. Note that the drive elements 38, 39 (or drive shoes or callipers remain on the locking disc 36 during rotation of the locking disc 36). The pressure in each of the cylinders is monitored by pressure sensors, and the pressure and flow is controlled so that the desired amount of rotation of the locking disc 36 is achieved. This configuration of the low-speed drive 32 is illustrated in Figure 6d.

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It is noted that the locking disc 36 is rotated to a position in which engagement formations 42 of the locking disc 36 line up with, and are adjacent to, the locking pins 40. At step 78 the locking pins 40 are actuated using hydraulic power to move from the unlocked position to the locked position so as to restrain movement of the locking disc 36 and low-speed shaft 26 relative to the housing 34. Again, the inductive sensors are used to ensure that the locking pins 40 are fully inserted into the engagement formations 42 prior to initiating the next step of the rotation cycle process. This configuration of the lowspeed drive 32 is illustrated in Figure 6e, and the first of the blades may then be mounted to the rotor hub 16.

As mentioned above, in order for the second of the blades 18 to be mounted the rotor 16 must be rotated through an angle of 120° so that the rotor hub is in the appropriate position to receive the second of the blades 18. At step 80, the drive element pins 50a, 50b are moved from the engaged to the disengaged position so as to allow movement of the drive elements 38, 39 relative to the locking disc 36. This configuration of the lowspeed drive 32 is illustrated in Figure 6f.

At step 82, the linear drives 52a, 52b, 52c, 52d are configured to return to their initial or reset positions by controlling the hydraulic pressure such that the first and third linear drives 52a, 52c move to their extended positions, and the second and fourth linear drives 52b, 52d move to their retracted positions. This configuration is illustrated in Figure 6g, and it is noted that this ‘reset’ position returns the low-speed drive 32 to the configuration illustrated in Figure 6a. Rotation of the rotor 16 to the appropriate position for the rotor hub to receive the second of the blades 18 is therefore effected by repeating steps 72 to 80.

As mentioned above, the high-speed drive 30 and the low-speed drive 32 are actuated substantially simultaneously to cause rotation of the rotor 16. This means that the drive torque needed to cause rotation of the rotor may be provided by a combination of the high- and low-speed drives 30, 32, i.e. the required drive torque is split between the highand low-speed drives 30, 32.

The torque split may be chosen to include any suitable combination of contributions from the two drives 30, 32. However, the drive torque provided by the high-speed drive 30 is limited to be no greater than a maximum level of drive torque that the gearbox 24 may withstand, i.e. a drive torque capacity, without causing failure of the gearbox 24. In

DK 2018 70867 A1 certain wind conditions, the drive torque capacity of the gearbox 24 may be less than the level of drive torque required to cause rotation of the rotor 16. The low-speed drive 32 may therefore be used to make up the deficit in drive torque being provided to the rotor 16. In such cases, the total drive torque being provided by the high- and low-speed drives 30, 32 is greater than the maximum torque capacity of the gearbox 24. Expressed differently, a maximum operational drive torque of the wind turbine 10, i.e. a maximum level of drive torque that may be needed to rotate the (unbalanced or balanced) rotor 16 during the lifetime of the wind turbine 10, perhaps in relatively extreme weather conditions, e.g. high winds, is greater than the maximum torque capacity of the gearbox 24.

In the described embodiment, the high-speed drive 30 drives the high-speed shaft 28 close to the limit that the gearbox 24 may withstand. In particular, the maximum drive torque that the high-speed drive 30 may provide is equal to the maximum torque capacity of the gearbox 24. It may be that the high-speed drive 30 provides the majority of the drive torque needed to rotate the rotor 16, with the low-speed drive 32 making up the shortfall, i.e. the sum of the drive torque being provided by the high- and low-speed drives 30, 32 is greater than the drive torque capacity of the gearbox 24. However, even if the high-speed drive 30 is operated at close to capacity, there may be certain weather conditions in which the low-speed drive 32 needs to, or is chosen to, provide the majority of the drive torque to rotate the rotor 16, i.e. where the drive torque provided by the lowspeed drive 32 is greater than that provided by the high-speed drive 30.

In the described embodiment, it is possible for the low-speed drive 32 to provide greater levels of drive torque to the drivetrain 20 than the high-speed drive 30. The torque split between the high- and low-speed drives 30, 32 depends on the total torque required, and how much torque may be transferred through the gearbox 24.

The low-speed drive 32 may also be used to limit the torque transferred through the gearbox 24 in the event of a wind spike. One or both of the drive elements 38, 39 and the locking pins 40 will always be engaged, and so can assist in dissipating torque that may otherwise be transferred through the gearbox 24 in the case of such an event.

Many modifications may be made to the above examples without departing from the scope of the present invention as defined in the accompanying claims.

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In the above-described embodiment, the holes or engagement formations 42 along the periphery of the locking disc 36 are partial holes or open holes located at the very edge of the locking disc 36; however, in different embodiments, the engagement formations may be completely enclosed and/or may be located at any suitable location of the locking disc, for example, radially inwards relative to the engagement formations of the described embodiment, and/or may be of any suitable size or shape.

In the above-described embodiment, the drive elements 38, 39 are each formed in a single piece, i.e. two hydraulic pistons are connected to a single drive element having two pins for engaging with the locking disc. In different embodiments, each of the drive elements may be in two pieces so that one hydraulic piston is connected to one drive element piece having one pin for engaging with the locking disc, and another hydraulic piston is connected to another drive element piece having another pin for engaging with the locking disc. The two pieces of the drive element may then be positioned adjacent each other at the periphery of the locking disc.

In the above-described embodiment, each of the two drive elements 38, 39 has two pins 50a, 50b, i.e. a total of four pins 50a, 50b, and each of the four hydraulic pistons 56a, 56b, 56c, 56d is associated with a different one of the pins 50a, 50b. In different embodiments, each drive element may only include one pin for engaging with the locking disc, with two hydraulic pistons being associated with the same pin.

In the above-described embodiment, the engaging means is movable between the engaged and disengaged positions using hydraulic power; however, in different embodiments different means of power may be used to cause such movement, for example electric power. The use of electric power may be advantageous in that the power means may be more suited for positioning in a relatively tight space.

Claims (15)

1. An apparatus (32) for rotating a rotor (16) of a wind turbine (10), the apparatus (32) comprising:

a rotatable control element (36) associated with the rotor (16), wherein rotation of the control element (36) causes rotation of the rotor (16), the control element (36) comprising a plurality of engagement formations (42);

a drive element (38) including engaging means (50a, 50b) movable between an engaged position in which the engaging means (50a, 50b) engages with the engagement formations (42) such that movement of the drive element (38) causes rotation of the control element (36) and a disengaged position in which the drive element (38) is movable relative to the control element (36);

first and second linear drives (52a, 52b) each movable between extended and retracted positions and each connected to the drive element (38), wherein when the engaging means is in the engaged position the first linear drive (52a) is configured to move towards the retracted position and the second linear drive (52b) is configured to move towards the extended position to cause movement of the drive element (38) and rotation of the control element (36).

2. An apparatus (32) according to Claim 1, wherein the control element (36) is at least part-circular in form, and wherein the engagement formations (42) are disposed on a periphery of the control element (36).

3. An apparatus (32) according to Claim 1 or Claim 2, wherein the engagement formations (42) are in the form of holes, and wherein the engaging means (50a, 50b) includes at least one pin.

4. An apparatus (32) according to any previous claim, the apparatus (32) comprising locking means (40) movable between a locked position in which the locking means (40) cooperates with the engagement formations (40) to restrain movement of the control element (36) relative to a housing (34) and/or a main

DK 2018 70867 A1 frame of the wind turbine (10), and an unlocked position in which the control element (36) is movable relative to the locking means (40).

5. An apparatus (32) according to Claim 4, wherein when the engaging means (50a, 50b) is in the disengaged position and the locking means (40) is in the locked position the first linear drive (52a) is configured to move towards the extended position and the second linear drive (52b) is configured to move towards the retracted position to cause movement of the drive element (38) relative to the control element (36).

6. An apparatus (32) according to any previous claim, wherein the first and second linear drives (52a, 52b) each include a hydraulic cylinder (54a, 54b), wherein hydraulic pressure is applied in the hydraulic cylinders (54a, 54b) to cause the first and second linear drives (52a, 52b) to move between the extended and retracted positions.

7. An apparatus (32) according to any previous claim, wherein the engaging means (50a, 50b) is operable to move between the engaged and disengaged positions via hydraulic power.

8. An apparatus (32) according to any previous claim, the apparatus (32) comprising:

a further drive element (39) including further engaging means (50a, 50b) movable between an engaged position in which the further engaging means (50a, 50b) engages with the engagement formations (42) such that movement of the further drive element (39) causes rotation of the control element (36), and a disengaged position in which the further drive element (39) is movable relative to the control element (36);

third and fourth linear drives (52c, 52d) each movable between extended and retracted positions and each connected to the further drive element (39), wherein when the further engaging means (50a, 50b) is in the engaged position the third linear drive (52c) is configured to move towards the retracted position and the fourth linear drive (52d) is configured to move towards the extended position to cause movement of the further drive element (39) and rotation of the control element (36).

DK 2018 70867 A1

9. An apparatus (32) according to Claim 8, wherein the further drive element (39) is arranged on a side of the control element (36) opposite to that of the drive element (38).

10. An apparatus (32) according to Claim 8 or Claim 9, wherein:

the first and fourth linear drives (52a, 52d) are rotatably mounted along a first rotation axis (58) to a housing (34) and/or a main frame of the wind turbine (10); and, the second and third linear drives (52c, 52d) are rotatably mounted along a second rotation axis (60) to the housing (34) and/or the main frame, the second rotation axis (60) being different from the first rotation axis (58).

11. An apparatus (32) according to any previous claim, wherein the control element (36) includes an aperture (37) arranged to receive a low-speed shaft (26) of the wind turbine (10), wherein rotation of the control element (36) causes rotation of the low-speed shaft (26) so as to rotate the rotor (16).

12. A method (70) of rotating a rotor (16) of a wind turbine (10), the wind turbine (10) comprising:

a rotatable control element (36) associated with the rotor (16), wherein rotation of the control element (36) causes rotation of the rotor (16), the control element (36) comprising a plurality of engagement formations (42);

a drive element (38) including engaging means (50a, 50b) movable between an engaged position in which the engaging means (50a, 50b) engages with the engagement formations (42) such that movement of the drive element (38) causes rotation of the control element (36) and a disengaged position in which the drive element (38) is movable relative to the control element (36);

first and second linear drives (52a, 52b) each movable between extended and retracted positions and each connected to the drive element (38), the method (70) comprising the steps of:

(a) actuating the engaging means (50a, 50b) from the disengaged position to the engaged position; and,

DK 2018 70867 A1 (b) substantially simultaneously actuating (76) the first linear drive (52a) towards the retracted position and actuating (76) the second linear drive (52b) towards the extended position to cause movement of the drive element (38) and rotation of the control element (36).

13. A method (70) according to Claim 12, the wind turbine (10) comprising locking means (40) movable between a locked position in which the locking means (40) cooperates with the engagement formations (42) to restrain movement of the control element (36) relative to a housing (34) and/or a main frame of the wind turbine (10), and an unlocked position in which the control element (36) is rotatable relative to the locking means (40), and the method (70) comprising actuating (74) the locking means (40) from the locked position to the unlocked position between step (a) and step (b).

14. A method (70) according to Claim 13, the method (70) comprising the steps of:

(c) actuating (78) the locking means (40) from the unlocked position to the locked position;

(d) actuating (80) the engaging means (50a, 50b) from the engaged position to the disengaged position; and, (e) substantially simultaneously actuating (80) the first linear drive (52a) towards the extended position and actuating (80) the second linear drive (52b) towards the retracted position to at least partially reset a position of the drive element (38) relative to the control element (36), wherein steps (c)-(e) are performed prior to step (a) and/or after step (b).

15. A wind turbine (10) comprising the apparatus (32) of any of Claims 1 to 13.