Abstract
Counterweight system for a wind turbine comprising a hub mounted to a nacelle such that the hub is rotatable around a rotation axis with respect to the nacelle. The counterweight system comprises: a mechanical unit comprising a fixed part and a rotatable part, the fixed part being mountable to the hub in such a way that the rotatable part is rotatable with respect to the hub substantially around the rotation axis of the hub; a drive unit for causing rotation of the rotatable part; a beam coupled to the rotatable part at a first point of the beam in such a way that the beam is arranged substantially perpendicular to the rotation axis of the hub; and a counterweight mass coupled to the beam at a second point of the beam. A method of mounting a blade to a hub by using said counterweight system is also provided.
Claims
1. A counterweight system for a wind turbine comprising a hub mounted to a nacelle such that the hub is rotatable around a rotation axis with respect to the nacelle, the counterweight system comprising: a mechanical unit comprising a fixed part and a rotatable part coupled to the fixed part, the fixed part being mountable to the hub in such a way that the rotatable part is rotatable with respect to the hub substantially around the rotation axis of the hub; a drive unit for causing rotation of the rotatable part; a beam coupled to the rotatable part at a first point of the beam in such a way that, when the fixed part is mounted to the hub, the beam is arranged substantially perpendicular to the rotation axis of the hub; a counterweight mass coupled to the beam at a second point of the beam at a distance from the first point of the beam; and wherein the fixed part is mountable to a region of the hub configured to receive a blade root.
2. The counterweight system according to claim 1, wherein the fixed part is mountable to a pitch bearing in the region of the hub configured to receive a blade root.
3. The counterweight system according to claim 2, wherein the beam is a telescopic beam such that the distance between the first and second points of the beam can be varied.
4. The counterweight system according to claim 1, further comprising a locking unit for locking the rotatable part.
5. The counterweight system according to claim 1, wherein the hub is configured to carry a plurality of blades each having a center of mass; and wherein a distance between the first and second points of the beam is substantially equal to a distance between the center of mass of a blade of the plurality of blades when carried by the hub and the rotation axis of the hub.
6. The counterweight system according to claim 1, wherein the hub is configured to carry a plurality of blades each having a mass; and wherein the counterweight mass is substantially equal to a mass of a blade of the plurality of blades.
7. The counterweight system according to claim 1, wherein the beam is a telescopic beam such that the distance between the first and second points of the beam can be varied.
8. The counterweight system according to claim 1, wherein the wind turbine is a direct drive wind turbine.
9. A wind turbine comprising a hub and a counterweight system according to claim 1 mounted to the hub.
10. The counterweight system according to claim 1, wherein the beam is a telescopic beam such that the distance between the first and second points of the beam can be varied.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) Non-limiting examples of the present disclosure will be described in the following, with reference to the appended drawings, in which:
(2) FIGS. 1a-1b schematically represents a side view and a front view of a counterweight system according to an example, said counterweight system being mounted to a hub of a wind turbine;
(3) FIG. 2 is a schematic representation of another counterweight system according to an alternative example, said counterweight system being mounted to a hub of a wind turbine; and
(4) FIGS. 3a-3m schematically illustrate a sequence of situations occurred during performance of a method of mounting a plurality of blades to a hub of a wind turbine, according to an example.
DETAILED DESCRIPTION OF EXAMPLES
(5) FIGS. 1a-1b schematically represents a side view and a front view of a counterweight system according to an example, said counterweight system being mounted to a hub 100 of a wind turbine. FIG. 1a shows said side view, and FIG. 1b shows said front view.
(6) In both FIGS. 1a and 1b, the wind turbine is shown having a tower 104, a nacelle 103 mounted on the tower 104, and a hub 100 mounted to the nacelle 103. The hub 100 is mounted to the nacelle 103 in such a way that the hub 100 is rotatable 112 around a rotation axis 113 (not indicated in FIG. 1b) with respect to the nacelle 103. The hub 100 is shown comprising a first region 101 adapted to receive a blade root, a second region 102 adapted to receive a blade root, and a third region 110 adapted to receive a blade root. This third region 110 is shown in FIG. 1b but not in FIG. 1a.
(7) The counterweight system is shown comprising a mechanical unit comprising a fixed part 105 and a rotatable part 106 (not shown in FIG. 1b). The fixed part 105 may be mountable to the hub 100 in such a way that the rotatable part 106 is rotatable 115 with respect to the hub 100 substantially around the rotation axis of the hub 113.
(8) In some implementations, this fixed part 105 may be mountable to a front portion of the hub 100. Alternatively, this fixed part 105 may be mountable to a region of the hub 100 configured to receive a blade root. For example, this fixed part 105 may be mountable to a pitch bearing comprised in said region of the hub 100 configured to receive a blade root (such as e.g. any of the regions 101, 102, 110).
(9) Details about how the fixed part 105 can be mountable to a hub region 101, 102, 110 adapted to receive a blade root will be discussed in other parts of the description with reference to FIG. 2.
(10) In the particular views of FIGS. 1a and 1b, the fixed part 105 is mounted to a front portion (e.g. a nose) 111 of the hub 100. This front portion 111 is not shown in FIG. 1b. The counterweight system of FIGS. 1a and 1b is shown having a beam 108 coupled to the rotatable part 106 at a first point 107 of the beam 108 in such a way (when the fixed part 105 is mounted to the hub 100) that the beam 108 is arranged substantially perpendicular to the rotation axis of the hub 113.
(11) The counterweight system of FIGS. 1a and 1b is shown as further comprising a counterweight mass 109 coupled to the beam 108 at a second point 116 of the beam 108 at a distance 114 from the first point 107 of the beam 108. The counterweight system may further comprise a drive unit 120 (FIG. 1a) for causing rotation of the rotatable part 106 of the mechanical unit.
(12) The hub 100 may be configured to carry a plurality of blades. Only one blade 117 and its center of mass 118 are shown in FIG. 1b. In some examples, the distance 114 between the first and second points 107, 116 of the beam 108 may be e.g. substantially equal to a distance 119 between the center of mass 118 of a blade 117 when carried by the hub 100 and the rotation axis of the hub 113.
(13) Each of the blades 117 carried by the hub 100 have a corresponding center of mass 118. In some examples of the counterweight system, the counterweight mass 109 may be substantially equal to said mass of the blade 117.
(14) According to examples of the counterweight system, the beam 108 may be a telescopic beam such that the distance 114 between the first and second points 107, 116 of the beam 108 can be suitably varied.
(15) FIG. 2 is a schematic representation of another counterweight system according to an alternative example, said counterweight system being mounted to a hub 100 of a wind turbine. The hub 100 shown in FIG. 2 may be similar to the one shown in FIGS. 1a and 1b. The same reference numbers used in FIGS. 1a and 1b have been re-used in FIG. 2 to indicate the same or similar elements of the hub 100.
(16) In FIG. 2, the counterweight system is also shown to be mounted to the hub 100. In this case, however, the counterweight system is shown comprising a fixed part 205 (of a corresponding mechanical unit) configured to be coupled to a corresponding region 102 of the hub 100 adapted to receive a blade root. In this particular figure, the fixed part 205 is shown coupled to the region 102 of the hub 100, but it could be similarly coupled to the region 101 or to the region 110.
(17) A rotatable part 206 (of the mechanical unit) is shown coupled to the fixed part 205 such that, when the fixed part 205 is coupled to a region of the hub 100 adapted to receive a blade root (such as anyone of the regions 102 or 101 or 110), the rotatable part 206 is arranged just in front of a front region (nose) 111 of the hub 100. In particular, the rotatable part 206 is shown in FIG. 2 to be arranged in the vicinity of the nose 111 of the hub 100 in such a way that the rotatable part 206 can be rotated (driven by a corresponding drive unit 120 (FIG. 1a)) with respect to the hub 100 substantially around the rotation axis 213 of the hub 100.
(18) The counterweight system of FIG. 2 is also shown having a beam 208 coupled to the rotatable part 206 at a first point 207 of the beam 208 in such a way that, when the fixed part 205 is mounted to the hub 100, the beam 208 is arranged substantially perpendicular to the rotation axis 213 of the hub 100. Furthermore, a counterweight mass 209 is shown coupled to the beam 208 at a second point 216 of the beam 208 at a distance 214 from the first point 207 of the beam 208.
(19) Other aspects and/or features commented with respect to the counterweight system of FIGS. 1a and 1b may be similarly attributed to the counterweight system of FIG. 2. For example, the beam 208 may be a telescopic beam so that the first and second points 207, 216 of the beam 208 can be selectively distanced by substantially the same amount as a blade center of mass is distanced from the hub root.
(20) An aspect of the counterweight system of FIG. 2 with respect to the counterweight system of FIGS. 1a and 1b is that no special arrangements may be required in the hub 100 for mounting the counterweight system to the hub 100. The counterweight system of FIG. 2 is configured to be mounted to a region 102 (or 101 or 110) which is necessary for the hub 100 to carry a blade which, in turn, is necessary for the wind turbine to operate. That is, a region 102 (or 101 or 110) which is necessary for the wind turbine to operate may be re-used for mounting the counterweight system to the hub 100.
(21) Otherwise, the counterweight system of FIGS. 1a and 1b may require the nose 111 of the hub 100 to have some kind of special arrangement (although it may be simple) for the counterweight system to be coupled to the nose 111.
(22) FIGS. 3a-3m schematically illustrate a sequence of situations occurring during performance of a method of mounting a plurality of blades to a hub of a wind turbine, according to an example. Said method will be described below with reference to said sequence of situations illustrated by FIGS. 3a-3m. For the sake of simplicity, references to FIGS. 1a and 1b may be made along said descriptions.
(23) Also for the sake of simplicity, references to times indicated by an imaginary clock may also be included in descriptions about FIGS. 3a-3m. Said references to times may be used to indicate approximate positions of a blade and/or a counterweight beam-mass (of a counterweight system according to an example) by considering said blade and/or counterweight beam-mass as an hour hand of said imaginary clock. Thus, for example, reference may be made to the counterweight beam-mass pointing to 6 o'clock to indicate that the counterweight beam-mass is vertically pointing downwards.
(24) The method of mounting a plurality of blades 300-302 implicitly illustrated by FIGS. 3a-3m may comprise several iterations of a method of mounting a single blade to the hub 100. In particular, FIGS. 3a-3e illustrate a first sequence of situations caused by a first iteration aimed at mounting a first blade 300 to the hub 100. FIGS. 3f-3i illustrate a second sequence of situations caused by a second iteration aimed at mounting a second blade 301. FIGS. 3j-3m illustrate a third sequence of situations caused by a third iteration aimed at mounting a third blade 302.
(25) FIG. 3a illustrates an initial situation in which the counterweight beam-mass 108-109 is pointing to 6 o'clock (i.e. freely hanging) and the hub 100 is not in a desired position for mounting the first blade 300. This initial position corresponds to a balanced position of the hub 100.
(26) FIG. 3b illustrates the counterweight beam-mass 108-109 rotated (by properly operating a corresponding drive unit 120 (FIG. 1a) of the counterweight system) in a clockwise direction for leading the counterweight beam-mass 108-109 towards a 7 o'clock position or the like. FIG. 3c implicitly illustrates that the weight of the counterweight beam-mass 108-109 acts (in anti-clockwise direction) against said forced motion in clockwise direction, such that a pendulum movement (back to the 6 o'clock position) is performed by the counterweight beam-mass 108-109.
(27) This pendulum motion of the counterweight beam-mass 108-109 induces an imbalance/torque (due to only weight loads) in the hub 100, which causes the hub 100 to rotate. This rotation of the hub 100 is counterclockwise (as reflected in FIG. 3c) such that the hub 100 is moved to a desired position for mounting a first blade 300.
(28) Once the hub 100 is in the desired position for mounting the first blade 300 (e.g. horizontally), the hub 100 may be locked by a corresponding locking unit 121 (FIG. 1a) (if present in the wind turbine). This locking of the hub 100 ensures that the hub 100 remains in the desired position during the entire mounting operation of the blade 300.
(29) FIG. 3d illustrates the counterweight beam-mass 108-109 rotated (by the drive unit 120 (FIG. 1a)) to e.g. a 3 o'clock position, which creates an anticipated counter-torque on the hub 100. This anticipated counter-torque may be of an amount substantially equal to a torque that will be induced by the weight of the first blade 300 once completely mounted to the hub. Once the counterweight beam-mass 108-109 is in the 3 o'clock position (or any other position aimed at achieving the mentioned objective), it may be locked by a corresponding locking unit 121 (FIG. 1a) (if present in the counterweight system).
(30) FIG. 3e illustrates the first blade 300 mounted to a suitable region 110 of the hub 100. The blade 300 may be mounted horizontally to the hub 100 (as shown in FIG. 3e) but other (non-horizontal) orientations may be considered depending on e.g. the particular configuration of the wind turbine. Once the blade 300 has been mounted to the region 110, the hub 100 may become significantly balanced. The weight of the blade 300 (in 9 o'clock position) and the weight of the counterweight beam-mass 108-109 (in 3 o'clock position) induce respective torques on the hub which may substantially cancel each other out. Accordingly, since a resultant torque of zero or close to zero may result, the hub 100 becomes substantially balanced.
(31) Once the first blade 300 has been mounted to the region 110, the hub 100 is in a balanced position. Then, a next iteration of the method of installing a single blade may be started from said balanced position of the hub 100. FIG. 3f illustrates said starting of said new iteration. Prior to the operation illustrated by FIG. 3f, the hub 100 may be unlocked (by suitably operating the corresponding locking unit 121 (FIG. 1a)) for cancelling the locking of the hub 100 occurred in the previous iteration.
(32) FIG. 3f illustrates the counterweight beam-mass 108-109 rotated in a clockwise direction from the 3 o'clock position (of FIG. 3e). This clockwise rotation of the counterweight beam-mass 108-109 may cause the (unlocked) hub 100 to rotate, due to the weight of the blade 300, counterclockwise from the 9 o'clock position (of FIG. 3e).
(33) FIG. 3g illustrates the rotation of the counterweight beam-mass 108-109 commented with reference to FIG. 3f stopped when the hub 100 has achieved a desired position for mounting a second blade 301 to the hub. In the particular case of FIG. 3g, said rotation is stopped when an available region 101 suitable for receiving a blade root is pointing to 9 o'clock, such that the second blade 302 may be mounted to said region 101 horizontally. The hub 100 is again in a balanced position due to a symmetric distribution of the first blade 300 (in e.g. 5 o'clock position) and the counterweight beam-mass 108-109 (in e.g. 7 o'clock position).
(34) In the situation illustrated by FIG. 3g, the hub 100 may be locked by a corresponding locking unit 121 (FIG. 1a) (if present in the wind turbine). This locking of the hub 100 may ensure that the hub 100 will remain in the desired position for mounting the second blade 301.
(35) FIG. 3h illustrates the counterweight beam-mass 108-109 rotated counterclockwise from a position (e.g. 5 o'clock position) which may cause the hub 100 to be again in an anticipated balanced situation taking into account the future installation of the second blade 301. Once the counterweight beam-mass 108-109 is in the e.g. 5 o'clock position, it may be locked by a corresponding locking unit 121 (FIG. 1a) (if present in the counterweight system).
(36) FIG. 3i illustrates the second blade 301 being (horizontally) mounted to the corresponding region 101 of the hub 100. Once mounted, a torque induced on the hub 100 by the weight of the second blade 301 may be suitably cancelled by a torque induced on the hub 100 by the weight of the first blade 300 and the counterweight beam-mass 108-109. Accordingly, the hub 100 is now again in a balanced situation caused by a resultant torque equal or close to zero. Then, a next iteration of the method of installing a single blade may be started from said balanced position of the hub 100. FIG. 3j illustrates said starting of said new iteration.
(37) Prior to the operation illustrated by FIG. 3j, the hub 100 may be unlocked (by suitably operating the corresponding locking unit 121 (FIG. 1a)) for cancelling the locking of the hub 100 occurred in the previous iteration.
(38) FIG. 3j illustrates the counterweight beam-mass 108-109 rotated in a clockwise direction (from the e.g. 5 o'clock position) which causes the hub 100 to rotate in a counterclockwise direction. FIG. 3k illustrates that said rotation of the counterweight beam-mass 108-109 may be stopped once it has induced the hub 100 to rotate to a position suitable for mounting the third blade 302 to the hub 100. Then, the hub 100 may be locked by a corresponding locking unit 121 (FIG. 1a) (comprised in the wind turbine) in order to ensure that the hub 100 will remain in the desired position during the entire mounting of the third blade 302.
(39) In the particular example of FIG. 3k, the counterweight beam-mass 108-109 is shown pointing to around 9 o'clock position, the first blade 300 is shown pointing to around 1 o'clock position, and the second blade 301 is shown pointing to around 5 o'clock position. The hub 100 is now again in a balanced position.
(40) FIG. 3l illustrates the counterweight system (i.e. the counterweight beam-mass 108-109) dismounted from the hub 100. The hub 100 is now in an anticipated balanced situation taking into account the future installation of the third blade 302.
(41) FIG. 3m illustrates that the third blade 302 may be (horizontally) mounted to a suitable region 102 of the hub 100. Once mounted, this third blade 302 causes the hub 100 to be in a balanced situation in conjunction with the other previously installed blades 300, 301.
(42) Although only a number of examples have been disclosed herein, other alternatives, modifications, uses and/or equivalents thereof are possible. Furthermore, all possible combinations of the described examples are also covered. Thus, the scope of the present disclosure should not be limited by particular examples, but should be determined only by a fair reading of the claims that follow.
