NL1041499B1

NL1041499B1 - Crane for installing a Wind Turbine.

Info

Publication number: NL1041499B1
Application number: NL1041499A
Authority: NL
Inventors: Lambertus Lagerweij Hendrik; Heinz Pubanz André; Van De Pol Aart; Waaijenberg Albèrt; Paul Corten Gustave
Original assignee: Lagerwey Wind B V
Priority date: 2015-10-01
Filing date: 2015-10-01
Publication date: 2017-04-19

Abstract

Hoisting system for the installation of a wind turbine comprising a column and a boom wherein said column comprises measures to achieve a load bearing connection to the tower of the wind turbine and wherein said column comprises measures to move the hoisting system up and down along the tower. Such a system can install successive tower sections while moving upwardly along the installed tower sections. After the tower is completed it can install the nacelle, generator, hub and the rotor blades. According to a further aspect the column comprises a rail which guides the hoisting system in essentially vertical direction along guiding points which a fixed to the tower and wherein said rail has a length of maximally 60m and in particular at least 23m and more in particular at least 34m. The long rail allows the hoisting of heavy parts such as the lower tower sections or the nacelle without applying high sideward forces to the tower since force = bending moment / arm. This hoisting system is efficient since it allows simple and fast movement of the system up and down along the guiding points on the tower. The aim is further reached by a wind turbine comprising a tower, a nacelle, a generator, a hub and at least a blade wherein the tower comprises guiding point for the fixation and guiding of the hoisting system according to the invention.

Description

Crane for Installing a Wind Turbine

Relation

The present invention relates to a hoisting system for the commissioning of a wind turbine and to a wind turbine which comprises measures to facilitate the use of said hoisting system and to the combination of said wind turbine and said hoisting system.

Introduction/problem

The costs of labor and maintenance increase only gradually with increasing turbine size, and therefore to minimize costs, wind turbines are getting bigger and bigger. With increasing size and height the installation costs of the turbines are not rising gradually but at least linearly with turbine size. The largest industrial cranes available are required to install the largest land based wind turbines. Those heavy modular crane units are expensive, often require strengthening of the roads and special transportation permits. In addition to these disadvantages said cranes need a lot of space which is not always available and when such a crane is needed for the next turbine in a wind farm it may occur that the crane cannot move thereto for example because the terrain is complex or the roads are too small. Then the crane has to be decommissioned, transported in parts and commissioned again which is an inefficient time consuming operation. This explains the initiatives to find a way around: to install a wind turbine more efficiently and in particular without the need of a large general purpose crane.

Prior Art

One initiative is that described in WO2014/082176A1 (Pellerin 2012) wherein a rails is attached to the tower and a lifting platform can move up and down over said rails. This system has the drawbacks that the rails is required over the full length of the tower, which adds weight and that the rails increases the tower stiffness in one direction so that the tower eigen frequencies in that direction become higher than those in the perpendicular direction which reduces the design freedom for modern variable rotor speed wind turbines where resonance between the tower eigen frequencies should be avoided in the full range of rotor frequencies and blade passage frequencies. Another drawback of the lifting platform is that it is attached to the rails over a vertical distance of about the length of 1 tower section or less. This relatively short distance leads to large forces on the wind turbine tower when heavy parts like the nacelle are lifted. And since the lifting platform moves over the entire rails length, the rails needs to be strong and heavy over the entire length and becomes expensive and economically inefficient. All said disadvantages of a lifting platform also turn up for the embodiments presented in US4311434 (Abe 1982), US6357549B1 (Brennan 2000), US6614125B2 and US6522025B2 (Willis 2002).

An alternative and also not efficient solution is presented in US8069634B2 (Livingston 2007). Herein a first crane which can be a large industrial crane or a crane of the ginpole type which is moveably attached to a partially constructed structural tower of a wind turbine is applied to hoist and install a structural tower in several parts and, once the tower is completed, to lift a second lifting system which is installed on top of the tower and serves to hoist the nacelle and the rotor. Next to the con of requiring two lifting systems the application is time consuming: the first crane should hoist the second lifting system to the top and this second should be installed and made operational. Then the first crane should be positioned away to avoid interfering with the second lifting system. After that the nacelle and rotor can be hoisted and when this is finished all steps need to be repeated in reversed order. A third con is that the ginpole as is shown in figures 29-37 of Livingston 2007 is not resistant to sideward wind loading: the tall crane has one or two slender beamlike joints to the tower which cannot take the sideward wind load so that the entire crane could spin around the vertical axis. A fourth con considers the embodiment of the ginpole moving system shown in figures 57 and 58 of Livingston 2007: The system employs one or more standoff brackets for fixation of a jump rack slidably to the wind turbine tower. The ginpole is also connected slidably to the jump rack. Moving the ginpole is a stepwise procedure wherein each step consists of installing successive standoff brackets to wind turbine tower, shifting the jump rack so that it overlaps with the successive standoff brackets and subsequently sliding the ginpole over the jump rack. This cumbersome procedure, which looks essentially equivalent to the invention presented in Gebrauchsmuster G9414643.8 (Kroger 1994) is time consuming and not cost-effective. It should be noted that the erection of a wind turbine requires a period of calm weather and in particular low wind speeds. If the hoisting takes much time the probability of completing the job in the low wind period is reduced which further decreases efficiency. US2015/0048043A1 (Laurens 2011) presents another comparable lifting system wherein after completion of the tower, a crane is installed on the tower top to hoist the nacelle and rotor. This system has the additional disadvantages that it feeds forces all the way down to the tower bottom and it cannot lift tower sections, so that a large conventional crane is still required.

An alternative method to install a wind turbine is by designing the nacelle of the wind turbine in such a way that is comprises a hole which encloses a non tapered tower.

Embodiments used for this approach are described e.g. in US756216 (Crunican 1902), DE2823525B1 (Sprang 1978), DE2735298A1 (Rogge 1979) and in US6408575B1 (Yoshida 2000). Although the Growian, a turbine of 100m height was made using this method, it turned out to be not efficient for large wind turbines: the large turbines require tapered towers to deal efficiently with the high bending moments. Therefore non-tapered towers have phased out for wind turbines with an axis height of above about 80 meters.

State of the art wind turbine towers are of the tapered structural type or of the tapered tubular type and sometimes the lower side of the tower is structural and the upper side tubular. The structural tower has the benefit that it can be transported in parts and assembled at the side, this advantage is however valid as well for the tubular towers of which the vertical sections can be assembled from easily transportable segments or shells. The tubular tower has the additional advantages that its appearance has better public acceptance and that it protects the equipment inside the turbines such as the inverter, transformer, controller etc. against the outdoor climate. Therefore solving the problem of the inefficiency of the installation of wind turbines is more relevant for tubular towers than for structural towers. This is another argument against the lifting system presented by Livingston 2007 which is suitable for structural towers only. It should be noted that we define tubular towers as towers of which horizontal cross sections are closed curves, which can be circular, polygonal, or of any other closed shape.

In DE19741988A1 (Peiter 1999) and DE19647515A1 (Gerd-Albrecht 1996) alternative lifting systems are presented wherein the lifting systems can climb cylindrical tubular towers by fixing itself by a system that surrounds the tower. Those systems easily damage the tower since large holding forces are needed to obtain sufficient friction on the tower wall to avoid the systems from gliding downward. Furthermore the systems are most suitable for non-tapered towers which have phased out. Finally the systems are not designed for carrying heavy parts of large modern wind turbines since the vertical length whereover the bending moments are fed into the tower is less that the length of one tower section or less than 2 tower top diameters which leads to unacceptable high forces on the tower wall.

Since the wind speed increases with height, and the average hub height of wind turbines increases with the successive wind turbine generations, the hoisting is getting increasingly hindered by high wind speeds. In particular this is relevant to the hoisting of the entire rotor i.e. the hub and the blades in a single hoist: the large aerodynamically shaped blades are sensitive to gusts. The lifting devices described in the above prior art are designed for single hoist lifting of the rotor and are not suitable for single blade hoisting and in particular not for the case that a single blade is hoisted in an about horizontal position.

All the above mentioned patent texts should be considered as integrated in this document with the exception that in the case of inconsistencies, the contents of this documents supersedes above the referenced texts.

Aim / Invention

The aim of the invention is to overcome the above mentioned disadvantages of existing solutions. This aim is reached by a hoisting system for the installation of a wind turbine comprising a column, a boom and a winch wherein said column comprises measures to achieve a load bearing connection to the tower of the wind turbine and wherein said column comprises measures to move the hoisting system up and down along the tower. Such a system can install successive tower sections while moving upwardly along the installed tower sections. After the tower is completed it can install the nacelle, generator, hub and the rotor blades. According to a further aspect the column comprises a rail which guides the hoisting system in essentially vertical direction along guiding points which are fixed to the tower. A beneficial maximum length of said rail is 60m, while the minimum length is 10m and in particular 20m and more in particular 34m. The long rail allows the hoisting of heavy parts such as the lower tower sections or the nacelle without applying high sideward forces to the tower since force = bending moment / arm. This hoisting system is efficient since it allows simple and fast movement of the system up and down along the guiding points on the tower. A further embodiment of the hoisting system is that wherein it comprises a rail of which a section can be put in a first position wherein the rail section can be placed over a guiding point on the wind turbine tower and in a second position wherein it encloses the guiding point in such a way that the rail can only move up and down along the tower. In a further embodiment the column of the hoisting system comprises measures to move the hoisting up and down along the tower. Such measures can comprise a hydraulic cylinder or an electromechanical linear actuator which is fixed at one end to the column and at the other end to a guiding point or alternatively it can comprise a chain which moving around over driven cogwheels which are fixed to the column. By fixing the chain to a guiding point it can move the hoisting system up and down. Another option to move the hoisting system is to fix a cable at one side to a guiding point and at another side to a winch which is mounted to the column. A further embodiment of the hoisting system comprises a coupling which can fix the hoisting system rigidly to a guiding point in such a manner that it can transfer vertical forces of the hoisting system to the guiding point in particular at least 30% of those vertical forces and more in particular at least 90% of those vertical forces. The height position of a coupling in the column is within the lower 65% of the length of the rail and in particular between 35% and 65% of the rail length. A beneficial embodiment of the hoisting system comprises a boom which reaches at least 15m from the rail and in particular at least 25m from the rail. According to one embodiment of the hoisting system the maximum length of the boom is 60m. A further beneficial hoisting system is that wherein the boom is fixed to the column via a yaw bearing and in particular wherein the rotation axis of said yaw bearing is inclined to the length direction of the rail by more than 0.5 degrees and in particular by more than 1 degree and even more in particular by less than 5 degrees. In a further beneficial embodiment of the hoisting system the boom is fixed with a tilt hinge to the yaw bearing or the boom comprises a tilt hinge, wherein the tilt hinge can be adjusted over at least 20 degrees and in particular over less than 200 degrees. The tilt motion can be driven by a hydraulic or electro mechanic actuator. An alternative beneficial embodiment is one wherein the column is extended to more than 15m and in particular more than 25m above the rail and comprises a yaw bearing whereon an about horizontal boom is attached which comprises a hoisting point which can move along the boom. In a further beneficial embodiment of the hoisting system the boom comprises a winch which drives the hoisting cable and in particular the boom comprises multiple winches which each have a separate hoisting cable leading to the hoisting point so that each winch carries part of the total load. A further beneficial embodiment of the hoisting system comprises a boom which is bended or inflected to that a line piece from the center of the tilt hinge to the hoisting point reaches a distance to the boom of at least 1.5m and in particular of at least 2.5m and preferably of about 4m. while a conventional heavy crane requires several dozens of trucks e.g. 50 for transportation, The hoisting system according to the invention can be transported by less than 5, e.g. just 2 standard trucks, , which gives advantage in cost and space requirements at the site. A further advantage is that the hoisting system can be installed in several hours while the erection of a heavy crane takes several days. An even further advantage is that the hoisting system can move up and down along the wind turbine tower relatively fast compared to the lifting systems found in the prior art.

The aim of the invention is further reached by a wind turbine comprising a tower, a nacelle, a generator, a hub and at least a blade wherein the tower comprises guiding points for the fixation and guiding of a hoisting system and in particular of the hoisting system according to the invention. An embodiment of such a wind turbine comprises guiding points at a relative spacing of more than 10m and less than 30m. A further embodiment of a wind turbine according to the invention is that wherein the tower comprises tubular overlapping sections which are bolted together on the overlap and wherein a guiding point is installed on the overlap so that less stiffening of the tower near the guiding points is required since the double layered overlapping parts have more stiffness by themselves. An even further embodiment of the wind turbine according to the invention comprises a guiding point which comprises a stiffening structure which is fixed to the tower and which extends from the center of the guiding point by at least 50cm and in particular by at least 100cm. Such a stiffening structure can be installed at the outer side or at the inner side or at both sides of the tower. In particular for the first or second tower section of a segmented tower the stiffening structure may comprise a structural beam from the guiding point to the tower foundation or a structural beam in about horizontal direction to the tower wall at a position which is more than 10degrees and in particular more than 30degrees away from the guiding point when rotating around the tower axis along the tower wall. A further embodiment of a wind turbine according to the invention comprises N guiding points which are numbered 1 to N in upward direction wherein for guiding point M for M = 1 to N-2, the line between the centers of guiding points M and M+1 reaches a distance to the center of a successive guiding point of maximally 5cm, in particular of maximally 10cm and more in particular of maximally 20cm. A further embodiment of a wind turbine according to the invention comprises a tower with a load carrying wall and in particular one wherein the wall is load carrying over a tower length of at least 50% and more in particular over at least 80%. One beneficial embodiment of a wind turbine according to the invention comprises a non-structural tower with a load carrying wall over its full length. A further embodiment of a wind turbine according to the invention comprises a tower of which a horizontal cross section of the outer side is shaped circular or polygonal. A further embodiment of a wind turbine according to the invention comprises a tubular tower which comprises a vertical section of which said sections are made of bended or folded steel plates which extend over the vertical length of said section. A further embodiment of a wind turbine according to the invention comprises a tower which comprises multiple vertical sections of a length between 10m and 22m and particularly between 10m and 16m. A further embodiment of a wind turbine according to the invention comprises a tower which is tapered over at least 50% of the tower length and in particular over at least 80% of the tower length. A further embodiment of a wind turbine according to the invention comprises a tower of which the guiding points including the stiffening thereof cover together less than 10% and in particular less than 20% of the tower length in any side view of the tower. A further embodiment of a wind turbine according to the invention of which the tower center is installed at a horizontal distance to the center of a dike of less than 100m, in particular less than 50m and more in particular less than 20m. A further embodiment of a wind turbine according to the invention which is installed using a hoisting system according to the invention. A further embodiment of a wind turbine according to the invention comprises an offshore turbine and in particular an offshore turbine of which the part which passes the sea level comprises a guiding point and more in particular wherein the transition piece comprises a guiding point for a hoisting system. A further embodiment according to the invention comprises a wind turbine with a axis height of more than 80m and in particular more than 130m and more in particular of more than 180m, wherein the maximum axis height according to an embodiment is 500m. A further embodiment according to the invention comprises a wind turbine of which the ratio between the design rotor speed at 6m/s wind speed and at 12 m/s wind speed is above 1.3 and in particular above 1.5 and more in particular above 1.8 and less than 3.

The aim of the invention is further reached by the combination of a wind turbine according to the invention with a hoisting system according to the invention. A further embodiment of a combination according to the invention is one wherein the rail of the hoisting system during hoisting work is fixed permanently in a star non-slidable manner to the column of the hoisting system while said rail is star or slidably fixed to the guiding points on the tower of the wind turbine. A further embodiment of the combination according to the invention is one wherein the rail of the hoisting system is at least connected to two or three guiding point during hoisting work. A further embodiment of the combination according to the invention is one wherein the highest guiding position where the hoisting system is fixed to the tower during the hoisting of tower parts corresponds to the overlapping part of the highest two installed tower sections.

The aim of the invention is reached as well by installing a wind turbine according to a following method according to the invention which comprises the following steps: The installation of the lower 1 to 3 tower sections with a conventional method possibly by the hoisting system according to the invention. Subsequently the installation of the rail of the hoisting system to the guiding points of the one or more installed tower sections. Subsequently the hoisting of 1 to 3 higher tower sections in parts or in single hoists and the installation of said higher sections. The repetition of unlocking, moving and relocking the hoisting system in a higher position and the hoisting and installation of one or two higher tower sections until the tower is fully assembled. Subsequently the unlocking, moving and relocking the hoisting system in the highest position and the hoisting of the nacelle, generator, hub and the rotor blades in one or more combined hoists or in a single hoist. In case of single blade hoisting the hoisting system can be used to turn the hub in a convenient position for installation a next blade by hoisting an installed blade to a lower or higher position. And finally the unlocking of the hoisting system and moving it downwardly by repetitively locking and moving the hoisting system back to the tower bottom and the removal of the hoisting system. A further method according to the invention is one wherein the horizontal distance between the hoisting point of the boom and the highest applied guiding point is less than the diameter of a hoisted tower segment.

Figures

The figures below show preferred embodiments of the invention.

Fig. 1: a wind turbine and a hoisting system;

Fig. 2; tower sections of a wind turbine;

Fig. 3: tower sections of a wind turbine;

Fig. 4: tower sections of a wind turbine;

Fig. 5: tower sections of a wind turbine;

Fig. 6: a wind turbine under construction and a hoisting system;

Figure 1 shows the combination of a wind turbine and a hoisting system 1. The wind turbine comprises tower sections 2 which overlap in areas 8 and each have a guiding point 7, a nacelle 3, a generator 4, a hub 5 and several blades 6. The hoisting system comprises a column 10, a yawing platform 11 which carries via a tilt hinge 12 the boom 14. The boom can tilt by activation of the hydraulic cylinder 13. The hoisting cable 18 is lead via pulleys 16 and 17 to the winch 15. The hoisting system is fixed to a rail 9 which is, depending on its position, slidably attached to guiding points 7, 19 and 20, so that it can move up and down along the tower. Before hoisting is started any of the locking systems 21, 22, 23, 24 locks the rail to a guiding point. Figure 2 shows the first three tower sections 30, 31 and 32 of a wind turbine. Section 32 is elevated for illustrative reasons. Section 30 comprises the guiding points 34 and 36 with respectively stiffening structures 33 and 35. Sections 31 and 32 comprise guiding points 39 and 40 with stiffening structures 38. Guiding points 36 and 40 comprise a hole 37 which is used for locking the hoisting system to the installed tower sections. The supporting beams 44 are fixed to stiffener 35 and to fixation means 45 which are fixed to the tower foundation 46. The dashed lines 41, 42 and 43 illustrate positions of the connection between the tower sections which e.g. can be bolted together. In this example the stiffeners 33, 35 and 38 are also bolted to the tower sections. According to an installation method according to the invention a general purpose crane installs the first tower section 30. Then the hoisting system is installed to the guiding points 34 and 36 of this first tower section 30. The hoisting system uses locking system 22 to lock itself to hole 37 of guiding point 36. Then it hoists tower section 31 on top of section 30 and during this hoist the guiding point 39 is placed in the rail 9. The sections are bolted together and the hoisting system hoists section 32 similarly on top of section 31 and subsequently hoists the fourth section. Then the hoisting system unlocks, moves upwardly and locks with locking system 23 to guiding point 37 of section 32 so that it can hoist section 5. This continues until the entire tower is installed. The hoisting system subsequently hoists and installs the nacelle, generator, hub and the blades, where several combined hoisting operations can be beneficial e.g. the nacelle and generator or the entire rotor comprising the hub and the blades or even the combination of the nacelle, the generator and the rotor in a single hoist. Figure 3 illustrates another embodiment of the first two tower sections 55 and 56 where section 55 has two guiding points 34 and 62. Guiding point 62 is installed on stiffener 58 which is placed via plate 59 (shown by a dashed line) to the tower wall. Plate 59 has the same thickness as the wall of tower section 56, so that this section fits precisely between section 57 and stiffener 58. The dashed lines 57 and 58 illustrate the positions for a bolted connections. In practice the bolts can be placed in multiple lines per connections which is not shown for illustrative reasons. Guiding point 62 is supported by beams 60 which are fixed to supports 61 on the inner side of the tower. The embodiment of figure 2 can also be combined with supporting beams on the inner side of the tower and that of figure 3 can be combined with supporting beams on the outside of the tower. In the case of the embodiment in figure 3 the locking system 22 is not required. Figure 4 illustrates again another embodiment of the first tower sections 70, 71 and 32 of a wind turbine. In this case section 32 and the higher sections which are not shown have a standard length 78 which can be transported easily e.g. a length between 10m and 16m such as e.g. 12m. The tower sections overlap over a distance 76 which is e.g. 0.5m, so that the tower height increases 11.5m per standard section. For the hoisting system it is beneficial when the guiding points always have the same vertical spacing 79, e.g. one guiding point per 11.5m. By increasing the length 75 of the first tower section 70 it can comprise two guiding points at a spacing of 11.5m and still sufficient length is left for the overlap 76 with tower section 71. This enables to attach the hoisting system to section on 70 and subsequently to hoist section 71 and 32, without the need of the special structure with plates 58 and 59 in figure 3. A consequence is that section 75 requires a longer transport length. Section 71 has a shorter length 77 and does not carry a guiding point. Guiding point 74 has a stiffening structure 73 on the outer side of the tower and a stiffening structure 80 on the inner side of the tower. Figure 5 illustrates a further embodiment of the first tower sections. In this case the first tower section 85, which also could be an integrated part of the tower foundation 46, comprises the first guiding point 90 with stiffener 91 at a distance 94 from the foundation. The second section 86 comprises a guiding point 92 with stiffener 93 and similar to figure 4 an internal stiffener 79. This embodiment has the advantage that the first, second and third sections can have equal or shorter lengths, respectively 88, 89 and 77, compared to the length 78 of the fourth section 32, which can be the maximum transport length of all sections. Figure 6 shows the hoisting system and the first tower sections in more detail compared to figure 1. The column of the hoisting system comprises a hydraulic cylinder 95 with piston 96 and an actuator in a state 97 so that it can pass a guiding point 99 and in a state 98 wherein it connects to guiding point 99. The hoisting system can move up after the actuator is in state 98 and is locked to guiding point 99 on tower section 103 and the hydraulic cylinder 95 is actuated until the weight of the crane is carried by the hydraulic cylinder. Then the locking systems 21, 23 and 24 are unlocked, where it should be noted that although this figure illustrated 3 locking systems any number of locking systems larger than zero is possible. Then the hydraulic cylinder 95 is further activated so that piston 96 is pulled into cylinder 95 so that the hoisting system moves upwardly. The upward movement continues until any locking system reaches a guiding point whereon it can be locked and the weight of the hoisting system can be transferred from the hydraulic cylinder 95 to the locking system. The figure is just an illustrative example. It should be clear that also two cylinders are possible: each at one side of the column or even multiple cylinders e.g. cylinders which push the hoisting system upwardly instead of pulling it upwardly. The figure further illustrates another tower section 100 which still has to be hoisted. The section comprises a guiding point 102 with edge 101 which serves to capture actuator 98.

Interpretation / Generalisation:

The above description focusses at the installation of a wind turbine using the hoisting system according to the invention, but is should be understood that the same hoisting system according to the invention is favourable for maintaining and decommissioning the wind turbine according to the invention.

Although the illustrative embodiments of the present invention have been described in greater detail with reference to the accompanying drawings, it will be understood that the invention is not limited to those embodiments. Various changes or modifications or combinations of embodiments in the description and or in the figures may be effected by one skilled in the art without departing from the scope or the spirit of the invention as defined in the claims.

It is to be understood that in the present application, the term "comprising" does not exclude other elements or steps. Also, each of the terms "a" and "an" does not exclude a plurality. Any reference sign(s) in the claims shall not be construed as limiting the scope of the claims.

In this description the term hoisting system always refers to an embodiment according to the invention.

Claims

Lifting system

CLAIMS 1. A hoisting system for building a wind turbine comprising a mast, a boom and a winch, the mast comprising means for establishing a bearing connection with a part of the tower of the wind turbine and means with which the hoisting system is substantially vertical direction along said tower part.

2. Hoisting system as claimed in claim 1, wherein the mast is rigidly connected to a rail which in particular has a length of at least 10 m, more in particular at least 20 m and even more in particular at least 34 m.

3. Hoisting system as claimed in claim 2, wherein the rail comprises a section within which the rail can assume a first position in which a guide point can be placed in the rails and a second position in which a guide point is confined in the rail and can only continue in the longitudinal direction of the rail shift.

4. Hoisting system as claimed in any of the foregoing claims, wherein the mast comprises provisions for the purpose of displacing the hoisting system in the substantially vertical direction, said provisions comprising for instance a circumferential chain or a hydraulic cylinder.

5. Hoisting system as claimed in any of the foregoing claims, wherein the mast comprises a bearing coupling for rigidly connecting the hoisting system to a guide point of the tower and in particular that this coupling is located in the lower 65% of the rail length and more particularly that this coupling is between 35% and 65% of the rail length.

6. Hoisting system as claimed in any of the foregoing claims, wherein the coupling between mast and a guide point is such that during hoisting operation it permits at least 0.25 degrees and in particular at least 0.5 degrees and more in particular at least 1 degree freedom of rotation about an imaginary horizontal axis between the parts connected to the link.

The hoisting system of claim 2 wherein the boom extends to a distance of at least 15 m from the rail and preferably of at least 25 m.

Crane as claimed in claim 7, wherein the boom is connected via a cross-bearing to the mast of the hoisting system and in particular wherein the axis of the cross-bearing makes an angle with the longitudinal direction of the rail of at least 0.5 degrees and in particular at least 1 degree .

The hoisting system of claim 1 wherein the boom is connected via a tilt hinge to the mast of the hoisting system.

10. Hoisting system as claimed in claim 9, comprising a hydraulic cylinder for rotating the boom relative to. the mast around the tilt hinge such that a tilt rotation of at least 20 degrees is possible.

11. Hoisting system as claimed in any of the foregoing claims, wherein the boom comprises a cable winch for operating the hoisting cable.

12. Hoisting system as claimed in any of the foregoing claims, wherein the boom is bent or bent such that a distance of at least 1.5 m and in particular at least 2.5 arises between the boom and the imaginary line section from the hoisting point of the boom to the center of the tilt hinge. m and preferably about 4 m.

A wind turbine comprising a tower, a gondola, a generator, a hub and at least one blade, wherein the tower is provided with mounting points for mounting and guiding a hoisting system.

14. Wind turbine according to claim 13, wherein the tower comprises mounting points at a mutual vertical distance of more than 10 m and less than 30 m.

Wind turbine according to claim 13 or 14, wherein at least one fixing point is arranged on the overlap of two consecutive tower sections.

Wind turbine according to one of the preceding claims 13 to 15, wherein a fixing point is reinforced up to a distance of the center of the fixing point of 50 cm and in particular of 100 cm.

A wind turbine according to any one of the preceding claims 13 to 16, wherein the tower interior is reinforced at the location of a mounting point.

A wind turbine according to any one of the preceding claims 13 to 17 with N fastening points that can be numbered from bottom to top with numbers 1 to N, where for M = 1 to N-2, the line representing the centers of two consecutive fastening points M and M + 1 connects a distance from the center of a third consecutive attachment point M + 2 of at most 5 cm and in particular at most 10 cm and more in particular at most 20 cm.

Wind turbine according to one of the preceding claims 13 to 18, the tower of which is provided with a load-bearing wall over 50% of the tower length and in particular over 80% of the tower length.

A wind turbine according to claim 13 to 19, wherein an outer view of a horizontal section of the bearing wall is substantially in the form of a circle or of a polygon.

A wind turbine according to any one of the preceding claims 13 to 20, wherein the tower is in the form of a tube that is made up of vertical sections, wherein said section is made up of curved or set plates that extend the length of the section.

A wind turbine according to any one of the preceding claims 13 to 21, wherein the tower is made up of several vertical sections with a length between 10 m and 16 m.

Wind turbine according to one of the preceding claims 13 to 22 with a tower that is tapered over 50% of the tower length and in particular over 80% of the tower length.

Wind turbine according to one of the preceding claims 13 to 23, wherein the attachment points together take up less than 20% and in particular less than 10% of the tower length for each side view of the tower.

25. Wind turbine according to one of the preceding claims 13 to 24, wherein the wind turbine is placed at a distance from the center of a dyke of less than 100 m, in particular less than 50 m and more in particular of less than 20 m.

26. Wind turbine according to one of the preceding claims 13 to 25, wherein the wind turbine is placed using a hoisting system.

27. Wind turbine as claimed in any of the foregoing claims 13-26, which relates to an offshore wind turbine.

A wind turbine according to claim 27 comprising a structure that passes the sea level and in particular wherein this structure relates to a transition part wherein said structure is provided with a mounting point for the mounting and guiding of a hoisting system.

Wind turbine according to one of the preceding claims 13 to 28 with a shaft height of more than 80 m, in particular of more than 130 m and more in particular of more than 180 m.

A wind turbine according to any one of the preceding claims 13 to 29, wherein the ratio between the design speed of the rotor at a wind speed of 6 m / s and at 12 m / s is less than 3 and more than 1.3 and in particular more than 1.5 and preferably more than 1.8.

Wind turbine according to one of claims 13 to 30, wherein this wind turbine is combined with a hoisting system according to one of claims 1 to 12.

Wind turbine according to claim 31, wherein the mast of the hoisting system is provided with rails connected to the mast and wherein said rails can be rigidly and slidably connected to a guide point on said wind turbine.

A wind turbine according to claim 31 or 32, wherein during hoisting operations the rails of the hoisting system are connected to at least two and preferably three guide points on the wind turbine tower.

A wind turbine according to any of claims 31, 32 or 33 wherein the highest position at which the hoisting system is connected during hoisting operations of tower parts for the construction of the wind turbine is at most the part of the upper tower segment already placed which overlaps with the tower segment below.

A method for installing a wind turbine according to any of claims 31 to 34 comprising at least 6 of the steps below: a. Building at least one tower segment in a conventional manner or with the hoisting system. b. Attaching the hoisting system with its rails to the guide points which are connected to the one or more placed tower segments. c. Hoisting in one or more parts of one to three subsequent tower segments with the hoisting system and installing these segments. d. Repeating making the hoisting system movable, guiding the hoisting system upwards, securing the hoisting system, hoisting one or two subsequent tower segments and installing these elements until the tower is fully assembled. e. Making the hoisting system movable, guiding the hoisting system to the highest position, securing the hoisting system and hoisting and installing the gondola, generator, hub and rotor blades assembled separately or in one or more parts. f. When lifting and installing the blades separately: rotating the position of the hub after placing the first blade by raising or lowering the blade with the hoisting system so that the hub is favorably positioned for the installation of the second blade . Repeating this step for any subsequent sheets. g. Making the hoisting system movable and moving the hoisting system down and dismantling the hoisting system from the wind turbine.

The method of claim 31 wherein when lifting a tower segment, the horizontal distance between the boom lifting point and the upper attachment between crane and tower is less than the diameter of said tower segment.