Method for changing the blades of a wind turbine

Abstract

The invention relates to a method for changing the blades of a wind turbine, in which method block and tackle devices are used for raising and / or lowering a blade, the fixed pulleys of which devices are fixed within the installation opening in the hub (5) of the wind turbine (28), an engagement point of a cable end of at least one first block and tackle device (41) is arranged within the installation flange (6) of the blade (1), and the other cable end is guided over diverting pulleys (25, 26) in the nacelle (27) of the wind turbine (28) to at least one winch (30) on a platform (35) that is anchored so as to be capable of bearing load.

Description

[0001] Procedure for changing the blades of a wind turbine

[0002] Description :

[0003] The invention relates to a method for changing the blades of a wind turbine.

[0004] The construction of today's bladed wind turbines, which are well over 100 meters tall, is carried out with the help of very large cranes. The use of such cranes requires not only appropriate access roads but also a high level of soil strength. Furthermore, even relatively low wind speeds can impede the use of such cranes.

[0005] The blades of the wind turbines in question become dirty and age. To prevent the performance of a wind turbine from being impaired to an undue extent, and especially to prevent the blades from breaking and thus endangering the surrounding area, replacing the blades is often unavoidable.

[0006] The use of correspondingly large cranes is, as explained above, problematic and, moreover, expensive.

[0007] Against this background, the invention aims to provide a cost-effective, resource-saving method for changing the blades of a wind turbine, which can also be used in higher wind speeds and in offshore wind farms.

[0008] This technical problem is solved with the help of pulleys and industrial climbers.

[0009] Confirmation copy Thus, according to claim 1, it is provided that for raising and / or lowering a wing, pulley blocks are used, the fixed rollers of which are fixed within the mounting opening in the hub of the wind turbine, that an engagement point of a rope end of at least one first pulley block is arranged within the mounting flange of the wing, and that the other rope end is guided via deflection rollers in the nacelle of the wind turbine to at least one winch on a load-bearing anchored platform.

[0010] The platform must be anchored in such a way that the forces acting on the winches can be safely absorbed. Various options are available for this. The platform can be anchored firmly to the ground, loaded with counterweights, or, for example, attached to the mast in offshore installations.

[0011] In order to ensure that no pressure is exerted on the wing tip when the wing is lifted off or placed on the ground, it is further provided that one end of the rope of at least one second pulley system is attached to the free wing tip and that the other end of the rope is guided via deflection pulleys in the nacelle of the wind turbine to at least one winch on a resiliently anchored platform.

[0012] The design of the pulley blocks is essentially arbitrary, but care must be taken to keep the height as low as possible so that the threaded bolts of the wing's mounting flange can be inserted into the corresponding recesses in a mounting ring around the mounting opening. Accordingly, pulley blocks with the roller axes in one plane and, if necessary, the rollers mounted in a block are preferred.

[0013] Since the entire load of a wing is diverted via pulleys within the nacelle to be guided through a material hatch to a winch on a resiliently anchored platform, the nacelle experiences a load of several tons, which must be taken into account statically.

[0014] To prevent damage to the threaded bolts protruding from the mounting flange, particularly when lifting a blade from the ground, it can further be provided that a textile loop, for example, 5 m long Dyneema webbing loops, is arranged between an attachment point within the mounting flange of the blade and the rope end of at least one first pulley for the ground-side pickup or storage of a blade. However, the use of such loops prevents the threaded bolts from being directly inserted into corresponding holes in the mounting ring around the hub's mounting opening.In such a case, it is provided that during assembly, after lifting the sash in a horizontal position, the sash is brought into a vertical position with the mounting flange at the top, that in this vertical position, rope ends of two pulley blocks on the sash are released and that the first pulley blocks are relieved one after the other and that with a relieved pulley block, the loops are removed and the block of the movable rollers or the rope end is fixed to the attachment point within the mounting flange of the sash.

[0015] Once a sufficient height has been reached, the wing can be easily moved into a vertical position. Second pulley blocks then no longer exert a pulling force and can be detached from the wing, for example, by industrial climbers. The wing is then suspended from several of the first pulley blocks. Their load-bearing capacity is designed so that one pulley block can be relieved. It is then possible to remove the loop from this pulley block and attach it directly to the anchor point within the wing's mounting flange. All loops can be removed one after the other, thus allowing the wing to be installed.

[0016] The method of wing installation described above requires the hub to be aligned as precisely as possible with the mounting hole facing downwards. This alignment is achieved using dummies that initially replace the wings. Such a dummy has the advantage of being significantly smaller and lighter than a wing. For example, a dummy similar to a 3-point truss can be only approximately 15 m long and weigh 1.5 t, compared to a 100 m long wing weighing more than 20 t.

[0017] The assembly of such a first dummy is basically carried out in the manner described above, in that at least one pulley block is used, the fixed rollers of which are fixed within the assembly opening in the hub of the wind turbine, that an engagement point of a rope end of the at least one pulley block is arranged within the assembly flange of the dummy, and that the other rope end is guided via deflection rollers in the nacelle of the wind turbine to at least one winch on a load-bearing anchored platform.

[0018] After mounting such a dummy, a rope is attached approximately in the middle of it, which runs above the hub to at least one winch on a securely anchored platform. The rope length is then shortened until the mounting opening in the hub following the dummy faces downward, allowing another dummy to be mounted, and so on until a final mounting opening for the first wing is facing downward.

[0019] After assembly, a rope is attached to the center of the wing, which runs over the tips of dummies to a winch on a rigidly anchored platform. The rope length is shortened until the dummy following the wing points downwards for disassembly. After disassembling the dummy, another wing is mounted, and so on until the final wing is mounted.

[0020] In a further embodiment of the method according to the invention, for the alignment and stabilization of a wing during its assembly, three cables are attached to the wing tip, which are guided at a distance from the wind turbine on resiliently anchored rollers to winches on a resiliently anchored platform.

[0021] For this purpose, pulleys are fixed with ground nails at a distance of, for example, 200 m above the ground. The load-bearing capacity of the ground anchors, which are preferably driven into the ground with back-up anchors, must be checked.

[0022] For offshore installations, the idea is to secure the rollers to the seabed with anchors.

[0023] If an additional deflection point is provided on the wind turbine mast at a sufficient height between the deflection point on the load-bearing anchored pulleys and the winches, this measure has the advantage that the cables can be guided from above to winches on a platform, for example, fixed to the vehicle and particularly loaded with additional weights. Such a platform will not only accommodate all of the winches, but also their control systems. It has proven useful to monitor the loads on the cables using tension scales, the measurements of which are transmitted wirelessly, for example via Bluetooth. In particular, it is conceivable that a closed delivery van is used as the vehicle. In such a vehicle, the cables are fed to the winches through a roof hatch in the roof. To counteract the resulting load, the vehicle must be regularly loaded with additional weights.

[0024] Such a vehicle represents a central control center from which the changing of blades of a wind turbine is monitored and controlled.

[0025] The method according to the invention is explained in more detail with reference to the drawing, in which the individual process steps are merely outlined. In the drawing, which is not to scale,

[0026] Fig. 1: the explanation of lifting a wing from a ground, shows

[0027] Fig. 2: a side view of the nacelle with a wing held in a vertical position and is shown by the

[0028] Fig. 3 to 6: the positioning of the hub is explained.

[0029] Fig. 1 shows a wing 1 in a holder 2 of a transport carriage 3 on a floor 4.

[0030] For mounting on a hub 5 of a wind turbine (not shown further in Fig. 1), threaded bolts 7 protrude from a mounting flange 6 of the blade 1. The threaded bolts 7 are to be inserted into corresponding recesses of a mounting ring 8 to 10 enclosing a mounting opening.

[0031] To do this, the blade 1 must be lifted as horizontally as possible from the bracket 2 so that the blade tip 11 is not subjected to any load. Only pulley blocks are used, whose fixed rollers are attached within the mounting openings or the vertically downward-facing mounting ring 8 in the hub 5, while movable rollers or rope ends engage the blade 1.

[0032] In particular, pulley blocks are intended which, with typical dimensions of approximately 100 m in length of wing 1 and weights of over 20 t, have two fixed pulleys and two movable pulleys.

[0033] For such wings 1, the use of five to six first pulley blocks is envisaged, which engage within the mounting flange 6, indicated by arrows 15, 16. One or two second pulley blocks, whose fixed rollers are arranged corresponding to the fixed rollers of the first pulley blocks, engage toward the free wing tip 11 in stop anchors on the wing, usually provided for this purpose at the factory, indicated by arrows 18, 19.

[0034] The other, free rope ends of the pulleys are guided over deflection pulleys 25, 26 in the nacelle 27 or the hub 5 of the wind turbine 28 through a material hatch 29 to a winch 30, each of which is indicated in Fig. 2, for lifting the blade 1. The winches 30 are arranged on a platform 35 in a vehicle 36 and are accessible through a roof hatch 37. To securely anchor the platform 35 to a floor 38, the vehicle 36 must regularly be loaded with additional weights, not shown in the drawing.

[0035] Raised to a sufficient height, the wing 1 is aligned vertically, see Fig. 2. In this position, the second pulleys no longer have any function and are removed.

[0036] To prevent the threaded bolts 7 protruding from the mounting flange 6 from being damaged by the rollers or blocks 40 of the first pulley blocks 41 when lifting the blade 1 in a horizontal position, textile loops 42, which have a length of, for example, 5 m, such as Dyneema webbing, are provided between the attachment points within the mounting flange 6 inside the blade 1 and the block 40 or the rope end of the first pulley block 41. These loops must be removed for mounting the blade 1 on the hub 5.

[0037] To do this, one of the first five to six pulley blocks 41 is unloaded. The load-bearing capacity of the first pulley blocks 41 must be designed accordingly. Industrial climbers, for example, then remove the loop 42 and attach the pulley or block 40 of the unloaded pulley block to the wing 1. Once all loops 42 have been removed, the wing 1 can be raised further and installed.

[0038] In order to align the blade 1 for assembly and to stabilize it during further lifting, for example to prevent pendulum movements, three additional cables are attached to the blade tip 11. These are located at a distance of approximately 200 m from the wind turbine 28 and deflected to the ground at an interval of 120°. Fig. 2 shows only one such cable 43 as an example, which is deflected for the first time on a ground-fixed roller 44. Since in the exemplary embodiment the platform 35 with winches 45 is provided within the vehicle 36, a further deflection 46 takes place on the mast 47 of the wind turbine 28 at a sufficient height so that the cable 43 can also be fed to winches 45 through the roof hatch 37 of the vehicle 36.

[0039] For the described assembly of a blade 1 to a hub 5, the vertical alignment of the mounting rings 8 to 10 is required. To ensure this, a dummy 50 is first installed. Such a dummy 50 is significantly smaller and lighter than a blade 1. For example, it can be designed in the form of a tapered triangular crossbeam with a length of approximately 15 m and a weight of 1.5 t. A roller or a fork can also be provided at the tip of such a dummy 50.

[0040] The assembly of such a dummy 50 is carried out as explained above for the wing 1.

[0041] After the dummy 50 is mounted, a rope 51 is attached to it approximately in its center and guided via the hub 5 to a ground-mounted winch. If the rope 51 is shortened, the hub 5 behaves like a rotating pulley. The rope 51 is then shortened until the subsequent mounting opening with mounting ring 10 points downward, into which a second dummy 52 is then mounted. The rope 51 can then run from approximately the center of the second dummy 52 across the center of the first dummy 50 and the hub 5, see Fig. 4.

[0042] If a final free mounting opening with mounting ring 9 points vertically downward, a first wing 53 can be mounted, shown in abbreviated form in Figs. 5 and 6. To align the subsequent mounting opening with mounting ring 8, another cable 54 is attached approximately in the center of wing 53. This cable 54 is guided over the tips 55, 56 of the dummies 50, 52 to a ground-mounted winch. This measure significantly increases the leverage of the applied force on hub 5 to accommodate the weight of wing 53.

[0043] The cable 54 is shortened until the first-mounted dummy 50 points vertically downwards and can be removed for the installation of a second wing 57. For a further rotation for the dismantling of the second dummy and the installation of the third and final wing, the cable 54 is attached to the center of each of the two wings 53, 57 and guided over the tip 55 of the second dummy 52 to a ground-mounted winch.

Claims

Procedure for changing the blades of a wind turbine Claims:

1. Method for changing the blades of a wind turbine, characterized in that for raising and / or lowering a blade, pulley blocks are used, the fixed rollers of which are fixed within the mounting opening in the hub (5) of the wind turbine (28), that an engagement point of a rope end of at least one first pulley block (41) is arranged within the mounting flange (6) of the blade (1) and that the other rope end is guided via deflection rollers (25, 26) in the nacelle (27) of the wind turbine (28) to at least one winch (30) on a load-bearing anchored platform (35).

2. Method according to claim 1, characterized in that one rope end of at least one second pulley system is attached to the free wing tip and that the other rope end is guided via deflection pulleys in the nacelle of the wind turbine to at least one winch on a load-bearing anchored platform.

3. Method according to one or more of the preceding claims, characterized in that for the bottom-side reception or storage of a wing (1) between a stop point within the A textile loop (42) is arranged between the mounting flange (6) of the wing (1) and the rope end of the at least one first pulley (41). Method according to claim 3, characterized in that during assembly, after lifting the wing (1) in a horizontal position, the wing (1) is brought into a vertical position with the mounting flange (6) at the top, that in this vertical position, rope ends of two pulley blocks on the wing (1) are released and that first pulley blocks (41) are relieved one after the other and that with a relieved pulley block (41) the loop (42) is removed and the block (40) of the movable rollers or the rope end is fixed to the attachment point within the mounting flange (6) of the wing (1).Method for aligning the hub of a wind turbine for mounting a blade according to one or more of the preceding claims, characterized in that at least one pulley block is used for mounting a first dummy (50), the fixed rollers of which are fixed within the mounting opening in the hub of the wind turbine, that an engagement point of a rope end of the at least one pulley block is arranged within the mounting flange of the dummy (50), and that the other rope end is guided via deflection rollers in the nacelle of the wind turbine to at least one winch on a load-bearing anchored platform.Method according to claim 5, characterized in that a cable (51) is attached to the center of the dummy (50), that cable is guided above the hub (5) to at least one winch on a load-bearing anchored platform and that the cable length is shortened until the assembly opening of the hub following the dummy (50) points downwards and a further (52) dummy can be mounted and so on until a last assembly opening for the assembly of a first wing (53) points downwards. Method according to claim 6, characterized in that a cable (54) is attached to the center of the wing (53), which cable runs over the tips (55, 56) of dummies (50, 52) and is guided to at least one winch on a load-bearing anchored platform, that the cable length is shortened until the dummy (50) following the wing (53) points downwards for disassembly, and that after the disassembly of the dummy (50), a further wing (57) is mounted, and so on until a last wing is mounted. Method for aligning and stabilizing a wing during assembly according to one or more of the preceding claims, characterized in that three cables are attached to the wing tip (11), which cables are guided at a distance from the wind turbine (28) and deflected on load-bearing anchored rollers towards winches (45) on a load-bearing anchored platform (35).Method according to claim 8, characterized in that between the deflection (44) on the load-bearing anchored rollers and the winches (45), a further deflection (46) is provided on the mast (47) of the wind turbine (28). Method according to one or more of the preceding claims, characterized in that a vehicle-mounted or mast-mounted platform (35) is provided.

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