WIND TURBINE TOWER WITH CRANE CONNECTION ELEMENTS AND A CRANE WITH TOWER FLANGE CONNECTION ELEMENTS

Abstract

A crane comprising a base portion, two arms movably connected to the base portion, and a lifting arm movably connected to the base portion, said lifting arm being provided with a lifting cable and a lifting member, for example, a lifting hook, for lifting a load, wherein the two arms and the base portion in combination comprise at least three tower flange connecting elements arranged to be detachably connectable to cooperating crane connecting elements on a flange of a wind turbine tower section, wherein each arm comprises one of the tower flange connecting elements, and wherein the vertical distance between any two tower flange connecting elements in the normal operating position of the crane is less than 1 m, less than 50 cm, or less than 25 cm.This provides a crane that can be attached to a flange located on the upper portion of a tower section.

Description

WIND TURBINE TOWER WITH CRANE CONNECTION ELEMENTS AND A CRANE WITH TOWER FLANGE CONNECTION ELEMENTS The present invention relates to a wind turbine tower with crane connection elements and a crane for connecting to crane connection elements on a wind turbine tower. The present invention also relates to a method for assembling a wind turbine tower with the crane. It should be noted that the term “wind turbine tower” should be understood as a tower for a wind turbine. This could refer to the completed tower or to a tower that is in the process of being assembled. For example, a single tower section anchored to the ground is considered a wind turbine tower under construction according to the current specification. The term “wind turbine tower” as used in the claims should cover this partially assembled wind turbine tower. The current specification also describes separate inventions aimed at a new self-elevating crane and a crane with a novel moment compensation mechanism. DESCRIPTION OF THE RELATED TECHNIQUE Typically, when performing maintenance and / or construction on a wind turbine tower, or when servicing a previously installed wind turbine, a crane is set up at the maintenance / construction site. The crane must have a vertical reach greater than the height of the wind turbine tower to lift components to the top. As wind turbines and towers continue to increase in size, cranes must also become larger. This presents challenges both in transporting the crane to the maintenance / construction site and in its installation. Especially in offshore locations, it is very difficult to assemble such large cranes and provide a stable base from which to work. Instead of building a crane next to the tower, smaller cranes can also be hoisted to the top of a wind turbine tower to assist with maintenance and repairs. In this way, instead of erecting a large crane next to the wind turbine tower, the wind turbine tower itself can be used as the main crane structure. Examples of such cranes are provided in documents WO2014 / 071949 and WO2011 / 050812. These cranes can be attached to the wind turbine tower in different ways. In the two documents mentioned above, the crane is attached to an attachment located on the wind turbine nacelle. In other cases, the crane can be hoisted to the top of the wind turbine tower using a block and rigging and then secured to the tower with slings or booms that wrap around it. To withstand the moments experienced by the crane during lifting operations, multiple slings or booms are required, spaced vertically apart on the tower. When constructing the slings or booms, it is important that they do not damage the tower structure while securing the tower and during crane operation. It is also known to connect a crane via a rail system that runs along one side of the wind turbine tower. This system is described in document WO2017 / 055598. In this case, the crane can also be used to assemble the tower and raise it as it is being built. Based on a different type of tower (not a wind turbine tower), it is known to provide each tower section with multiple vertically spaced supports on its lateral surface. A crane can then be attached to these supports via multiple vertically spaced booms. See US patent 2,720,694. However, all state-of-the-art solutions suffer from several drawbacks. Some systems are relatively complex. Others require a large crane structure. Still others require an existing tower and a connection to the upper portion of the tower to lift the crane into place. Other systems require complicated supports attached to the surface of the tower sections. SUMMARY OF THE INVENTION Therefore, a first aspect of the present invention is to provide a wind turbine tower and a crane in such a way that the crane can be attached to the wind turbine tower in a simple manner. A second aspect of the present invention is to provide a wind turbine tower and a crane by which the crane raises itself, so that it can lift itself to the top portion of the wind turbine tower. A third aspect of the present invention is to provide a wind turbine tower and a crane in such a way that the crane can be used during the assembly of the wind turbine tower. At least some of these aspects are resolved by a wind turbine tower comprising a first tower section, said first tower section having an upper flange 2 disposed at an upper end of the first tower section, said upper flange comprising one or more flange portions extending horizontally beyond the outer surface of the main body of the first tower section, said one or more flange portions together comprising at least three crane connecting elements, the vertical distance between any two of said at least three crane connecting elements being less than 1 m, each of said at least three crane connecting elements arranged so that a cooperating tower flange connecting element on a crane can be detachably connected to said crane connecting element and separated around the circumference of the first tower section.In this way, the crane can be attached directly to the flange. This contrasts with prior art solutions where the crane must be secured or connected to the outer surface of the tower sections, which can damage the tower section. Furthermore, most tower sections already have a flange on their upper portion for bolting to the next tower section and / or the wind turbine nacelle. Therefore, relatively minor modifications to the existing flange are required, or a simple additional flange could be added to the existing one to provide the crane's connection points. For the purposes of this specification, the term crane connecting element should be understood as an element arranged to establish a secure and detachable connection with another element. This contrasts with flanges found on wind turbine tower sections, which may have areas to which a connection can be made but do not have specifically arranged connecting elements. A crane connecting element should be able to provide a detachable connection to a crane that is secure and capable of supporting the loads provided by the crane. In one embodiment, the at least three crane connection elements are arranged so that a crane connected to said at least three crane connection elements can safely support a load of at least 10 tons, at least 20 tons, at least 30 tons, or at least 60 tons positioned at least 6 m in a horizontal distance from the center of the tower section. In one embodiment, the at least three connecting elements of the crane are arranged so that a horizontal component of a vector A between a first set of two connecting elements has a length of at least 200 cm and a horizontal component of a vector B between a second set of two connecting elements has a length of at least 200 cm. In one embodiment, the flange and the at least three connecting elements of the crane are designed such that a first set of two connecting elements can safely withstand a moment about one of said two connecting elements of at least 1,750,000 Nm, and a second set of two connecting elements can withstand a moment about one of said two connecting elements of at least 1,750,000 Nm. This is equivalent to a load of 60 tonnes at 6 m from the base of the crane, shared between two supports. In another embodiment, the moments should be at least 3,500,000 Nm. According to this specification, safe support means that a moment can be applied to the connecting elements without causing undue deformation of the flange / crane / tower section and without risk of any damage to the flange / crane. An engineer with experience in mechanical engineering will be able to easily define the limits of what constitutes safe support for a specific structure. In one embodiment, one of said, at least, three crane connection elements is arranged on one side of a vertical plane P that passes through another of said three crane connection elements and the central axis of the first tower section, and another of said three crane connection elements is arranged on another side of the vertical plane P. In one embodiment, the vertical distance between any two of said at least three crane connecting elements is less than 50 cm or less than 25 cm. In one embodiment, said at least three crane connecting elements are arranged essentially in the same horizontal plane. In one embodiment, the vertical distance between any three of said at least three crane connecting elements is less than 50 cm or less than 25 cm. In one embodiment, the vertical distance between the highest and lowest of any three of said at least three crane connecting elements is less than 50 cm or less than 25 cm. In one embodiment, the flange comprises four crane connection elements, and a vector A between a first and a second crane connection element has a length of at least 200 cm and a vector B between a third and a fourth crane connection element has a length of at least 200 cm. In one embodiment, the length of the horizontal component of vector A and the length of the horizontal component of vector B are equal. In one embodiment, the first and second crane connection elements are arranged on one side of a vertical plane P passing through the central axis of the first tower section, and the third and fourth crane connection elements are arranged on the other side of the vertical plane. In one embodiment, the wind turbine tower further comprises a second tower section disposed in the upper portion of the first tower section; the second tower section has an upper flange comprising one or more flange portions extending horizontally beyond the outer surface of the main body of the first tower section; said one or more flange portions together comprise at least three crane connecting elements; the vertical distance between any two of said at least three crane connecting elements is less than 1 m; each of said at least three crane connecting elements is arranged so that a cooperating tower flange connecting element on a crane can be detachably connected to said crane connecting element and separated around the circumference of the first tower section.In this way, a crane can be attached to the flange of the first tower section and / or to the flange of the second tower section. In one embodiment, the at least three crane connection elements of the upper flange of the second tower section are arranged so that a crane connected to said at least three crane connection elements can safely support a load of at least 10, at least 20, at least 40 or at least 60 tonnes positioned at least 6 m horizontally from the center of the second tower section. In one embodiment, the crane connecting elements of the second tower section are arranged such that the horizontal component of vector C between a first set of two crane connecting elements has a length of at least 200 cm, and the horizontal component of vector D between a second set of two crane connecting elements also has a length of at least 200 cm, and because the angle between vectors A and B is greater than the angle between vectors C and D. In this way, a crane can be connected to either the first or second flange using the same connecting elements, even though the diameter of the tower sections may differ. In one embodiment, the lengths of vectors A and C are the same, and the lengths of vectors B and D are the same.In one embodiment, the outside diameter of the main body of the second tower section at the location of the upper flange of the second tower section is less than the outside diameter of the main body of the first tower section at the location of the upper flange of the first tower section. In one embodiment, the vertical distance between any two of the at least three crane connection elements of the second tower section is less than 50 cm or less than 25 cm. In one embodiment, the at least three crane connection elements of the second tower section are arranged essentially in the same horizontal plane. In one embodiment, the vertical distance between any three of the at least three crane connection elements of the second tower section is less than 50 cm or less than 25 cm. In one embodiment, the vertical distance between the highest and lowest of any three of the at least three crane connection elements of the second tower section is less than 50 cm or less than 25 cm. The invention also relates to a crane comprising a base portion, two arms movably connected to the base portion, and a lifting arm movably connected to the base portion, said lifting arm being provided with a lifting cable and a lifting member, for example, a lifting hook, for lifting a load, characterized in that the two arms and the base portion in combination comprise at least three tower flange connecting elements arranged to be detachably connectable to cooperating crane connecting elements on a flange of a wind turbine tower section, in that each arm comprises one of the tower flange connecting elements, and in that the vertical distance between any two tower flange connecting elements in the normal operating position of the crane is less than 1 m, less than 50 cm, or less than 25 cm.In this way, the crane can be attached to the tower section directly at the flange, and most of the loads can be supported by the flange. This contrasts with prior art cranes that need to be attached at multiple points separated by a large vertical distance on the body of the tower section. According to the current specification, the term "tower flange connecting element" should be understood as an element provided to establish a secure and detachable connection with the tower flange. Tower flange connecting elements must be suitable for use in the method described below, where the crane is repeatedly connected to and disconnected from different tower flanges. Therefore, tower flange connecting elements must be suitable for frequent disassembly and reassembly. According to the current specification, the term "displaceable" should be understood to include different types of motion paths. In the description and figures, the crane arms are shown rotatably connected to the base portion of the crane. However, within the scope of the present invention, the arms could also be displaceably connected to the base portion in ways other than rotatably. In one embodiment, the arms are rotatably connected to the base portion. In another embodiment, the arms are linearly displaceable connected to the base portion. In yet another embodiment, the displacement path of the arms can have both linear and rotary components. The same applies to the hoist arm. The hoist arm can take on different shapes as known in the art and is connected to the base portion in various ways. In one embodiment, the base portion, arms, and connecting elements of the tower flange are arranged so that the lifting member can safely lift a load of at least 10 tons, at least 20 tons, at least 30 tons, or at least 60 tons when the lifting member is placed at a horizontal distance of at least 6 m from at least one of said at least three tower flange connecting elements. In one embodiment, the tower flange connection elements are arranged such that a vector E between a first set of two tower flange connection elements has a length of at least 200 cm and a vector F between a second set of two tower flange connection elements has a length of at least 200 cm. In one embodiment, the length of the horizontal components of the aforementioned vectors is at least 200 cm. In one embodiment, the base portion, the two booms, and the tower flange connecting elements are arranged so that the crane can safely withstand a moment about one of the tower flange connecting elements of at least 1,750,000 Nm. In one embodiment, the booms are rotatably connected to the base portion. In one embodiment, the booms are arranged to pivot about vertical axes. In one embodiment, the booms are arranged to lie on either side of a vertical plane P passing through the centerline of a tower section when the crane is attached to the tower section. In one embodiment, the three tower flange connecting elements are essentially in the same plane in the normal operating position of the crane. In one embodiment, the crane comprises four tower flange connection elements, and each of the two jibs comprises two toe flange connection elements. In one embodiment, the two tower flange connection elements on a first jib and the two tower flange connection elements on a second jib are arranged on opposite sides of a vertical plane passing through the centerline of a tower section when the crane is attached to the tower section. In one embodiment, the crane comprises four tower flange connection elements and four arms, each arm comprising one of the four tower flange connection elements. In one modality, the vertical distance between any three of the at least three connecting elements of the tower flange is less than 50 cm or less than 25 cm. In one embodiment, the at least three tower flange connection elements are arranged essentially in the same horizontal plane. In one embodiment, the crane further comprises a cable and pulley system comprising the lifting cable and the lifting member. In one embodiment, the hoist cable is connected to a winch located away from the crane. According to this specification, the phrase “located away from the crane” should be understood as located separately from the crane, so that as the crane moves up or down the tower, the winch does not move by the same amount. In a typical situation, the crane will be attached to a wind turbine tower so that it can move up and down the tower, while the winch will be located near the base of the tower to which the crane is attached. In this embodiment, the only connection between the crane and the winch is the cable. In one embodiment, the cable and pulley system comprises a lower pulley block comprising a pulley and an upper pulley block comprising at least one more pulley than the lower pulley block; the upper pulley block comprises the lifting member and the lower pulley block comprises a first connecting element suitable for establishing a detachable connection with the lifting member and a second connecting element suitable for establishing a detachable connection with a crane lifting connecting element disposed in a tower section of a wind turbine tower when the crane is connected to a tower section. In one embodiment, the second connecting element is strong enough to safely support the weight of the crane. In one embodiment, the upper and lower pulley blocks are arranged to move vertically between an upper portion of the lifting arm and a lower portion of the base portion. In one embodiment, the crane further comprises a lower pulley fixed to the base portion of the crane and an upper pulley fixed to an upper portion of the lifting arm; the lower pulley is positioned below the lower pulley block and the upper pulley is positioned above the upper pulley block; the hoisting cable passes from the winch, over the lower pulley block, down to the lower pulley, up to the upper pulley, and down to the upper pulley block. In one embodiment, the crane further comprises a moment compensation mechanism consisting of a moment compensation arm at least 300 cm long extending from the crane with a horizontal component. The end of this arm is connected by a cable to a winch located some distance from the crane. By using such a moment compensation arm, the moment applied to the base portion by the hoist arm can be compensated by this arm. In this way, the moment loads on the tower section can be reduced. In one embodiment, the arm can pivot around a horizontal axis. This allows the moment provided by the cable connection to the crane to be adjusted by rotating the arm around the horizontal axis to adjust the horizontal component of the moment compensator arm extension. In one embodiment, the horizontal component of the moment compensator arm is at least 100 cm, at least 200 cm, or at least 300 cm. In another embodiment, the arm can pivot around a vertical axis. In one embodiment, the cable connected to the arm is the hoist cable of the cable and pulley system and is connected to the crane's main hoist winch. In one embodiment, the moment compensation arm is attached to the hoist arm. In another embodiment, the moment compensation arm is arranged to pivot about a vertical axis in a relationship inversely proportional to the pivot movement of the crane's hoist arm. In one embodiment, the length of the lifting arm is such that the vertical distance between the highest point of the lifting arm and the connecting elements of the tower flange is greater than 5 m, greater than 10 m, or greater than 20 m. In another embodiment, this vertical distance is greater than the height of a tower section. In this way, the crane can be used to erect the tower itself, but it lifts subsequent tower sections to the top of the preceding tower section. The invention also relates to an assembly comprising a wind turbine tower according to any one of the embodiments described herein, a crane according to any one of the embodiments described herein connected to a flange of a tower section of the wind turbine tower, and a winch located near the base of the wind turbine tower, said winch comprising a cable that connects to the cable and pulley system of the crane. It should be noted that the characteristics of the moment compensation arm could be the basis of a divisional application and could support other types of cranes, for example cranes that are 9 MA / a / ZUZ 1 / U14Ί OU connected to multiple points on the wind turbine tower separated by a vertical distance.Thus, a possible claim for this invention could be drafted along the lines of a crane comprising a base portion, a tower connection portion connected to the base portion, and a lifting arm movably connected to the base portion, said lifting arm being provided with a lifting cable and a lifting member, for example a lifting hook, for lifting a load, wherein the tower connection portion is arranged to be detachably connected to a cooperating crane connection portion in a section of the wind turbine tower, and wherein the crane further comprises a moment compensation mechanism comprising a moment compensation arm at least 300 cm long and extending from the crane with a horizontal component, the end of said arm being connected by a cable to a winch located away from the crane.The features of the other modalities described in the present description could also be combined with this invention, as will be obvious to the person skilled in the art. It should also be noted that the combination of the cable and pulley system features discussed above and the lifting arm height features could form the basis of a divisional application covering other crane types besides the one currently claimed. An example claim could be a crane comprising a base portion, a tower connecting portion connected to the base portion, and a lifting arm movably connected to the base portion, said lifting arm being provided with a lifting cable and a lifting member, for example, a lifting hook, for lifting a load, wherein the tower connecting portion is arranged to be detachably connectable to a cooperating crane connecting portion on a section of the wind turbine tower.and wherein the crane further comprises a cable and pulley system comprising the hoist cable and the hoist member, and wherein the cable and pulley system further comprises a lower pulley block comprising a pulley and an upper pulley block comprising at least one more pulley than the lower pulley block, the upper pulley block comprising the hoist member and the lower pulley block comprising a first connecting element suitable for establishing a detachable connection to the hoist member and a second connecting element suitable for establishing a detachable connection to a crane hoisting connecting element disposed in a tower section of a wind turbine tower when the crane is connected to a tower section. ML / a / ZUZl / Ul 41 ou It should be emphasized that the term "comprises" when used in this description is taken to specify the presence of stated features, whole numbers, stages, or components, but does not exclude the presence or addition of one or more features, whole numbers, stages, components, or groups thereof. For example, in the claim relating to the crane, it is stated that the crane comprises two arms. This should be understood to mean that the crane has at least two arms, and cranes with three arms, four arms, etc., would also be included within the scope of the claim. As another example, in one of the claims, it is stated that each of the arms comprises a tower flange connection element. This should also be understood to mean that each of the arms comprises at least one tower flange connection element.As such, a crane with an arm having two or more tower flange connection elements is also covered. BRIEF DESCRIPTION OF THE DRAWINGS Figures 1a and 1b show a side view and a perspective view, respectively, of a first stage in a tower construction process using the crane and tower according to the present invention. Figures 2a and 2b show a side view and a perspective view, respectively, of a second stage in a tower construction process using the crane and tower according to the present invention. Figures 3a and 3b show a side view and a perspective view, respectively, of a third stage in a tower construction process using the crane and tower according to the present invention. Figures 4a and 4b show a side view and a perspective view, respectively, of a fourth stage in a tower construction process using the crane and tower according to the present invention. Figures 5a and 5b show a side view and a perspective view, respectively, of a fifth stage in a tower construction process using the crane and tower according to the present invention. Figures 6a and 6b show a side view and a perspective view, respectively, of a sixth stage in a tower construction process using the crane and tower according to the present invention. Figures 7a and 7b show a side view and a perspective view, respectively, of a seventh stage in a tower construction process using the crane and tower according to the present invention. Figures 8a and 8b show a side view and a perspective view, respectively, of an eighth stage in a tower construction process using the crane and tower according to the present invention. Figures 9a and 9b show a side view and a perspective view, respectively, of a ninth stage in a tower construction process using the crane and tower according to the present invention. Figures 10a and 10b show a side view and a perspective view, respectively, of a tenth stage in a tower construction process using the crane and tower according to the present invention. Figures Ha and 11b show a front view and a perspective front view, respectively, of an eleventh stage in a tower construction process using the crane and tower according to the present invention. Figures 12a and 12b show a front view and a perspective front view, respectively, of an alternative eleventh stage in a tower construction process using the crane and tower according to the present invention. Figures 13a and 13b show a rear view and a perspective rear view, respectively, of the alternate eleventh stage shown in Figures 12a and 12b. Figures 14a and 14b show a schematic representation of an alternative mounting flange arrangement located on an upper and lower section, respectively, of the tower. Figures 15a and 15b schematically show two positions of the cable and pulley system. The invention will now be described in greater detail with reference to the embodiments shown in the accompanying figures. It should be emphasized that the embodiments shown are used for illustrative purposes only and should not be used to limit the scope of the invention. DETAILED DESCRIPTION OF THE MODALITIES Figures 11a–11b show eleven steps of a method for assembling a wind turbine tower, placing the nacelle on the upper portion of the tower, and mounting the blades on the nacelle. The method used in the figures makes use of a new type of crane and a tower section with a new flange to enable the assembly method. The function of the crane and the flange will be described with reference to the steps of the method to better illustrate the function. In Figures 1a and 1b, a base tower section 1 is erected on a support surface (not shown), in a manner known in the art. The base tower section is typically bolted to a foundation element (not shown) as known in the art. Once the base tower section is erected, a crane 2 is connected to the base tower section 1. The crane comprises a base portion 4 and two arms 6, 8 rotatably connected to the base portion. The two arms are arranged to pivot about a vertical axis so that they can pivot in connection with the tower section as shown in Figures 1a and 1b or pivot away from the tower section as shown in Figures 5a and 5b. In the current embodiment, each arm comprises two tower flange connection elements 10 that engage with crane connection elements 12 on the tower section. In this embodiment, the crane connection elements 12 are arranged as flanges extending outwards from the outer surface of the tower section, and the tower flange connection elements 10 are arranged as slots in the arms that engage with the tower flanges 12. A pin 13 is inserted into a hole 14 on an upper surface of the crane arms to engage with a corresponding hole 16 in the flanges 12 of the crane connection element on the tower section. It should be noted that this is one embodiment of a crane connection element and a tower flange connection element and is shown in a rather schematic manner.It should be clear to the technical expert that the crane's connecting elements in the tower section and the tower's connecting elements in the crane can be configured in many different ways. Furthermore, automated solutions with electrically or hydraulically operated locking mechanisms are conceivable. In this configuration, section 1 of the base tower has two sets of crane connecting elements 12. The first set is located near the center 18 of the base tower section, and the second set is located at the upper end 20 of the base tower section. In the first stage, the crane is attached to the first set of crane connecting elements so that the crane does not have to be raised as high. The crane can be transported to the site on a truck and then lifted into position by a separate crane or by lifting it off the truck. This process is not illustrated because a person skilled in the art could provide a suitable method for moving the crane from the truck to the lower crane connecting elements. The crane connection elements 12 shown in the Figures are arranged as steel flanges extending outward from the outer surface of the tower section. If the flanges are located on the upper portion of the tower section, they can be an integral part of the bolt flange used to bolt two tower sections together. Such bolt flanges are integrated into the ends of the tower sections, and the crane connection flanges can be provided by extending the bolt flange outward beyond the outer surface of the tower section. The base portion 4 and the arms 6 and 8 of the crane are arranged so that when both arms are connected to the crane connecting elements 12 of the tower section 1, the base portion can safely absorb a large moment around the crane connecting elements without unwanted deflection. Therefore, the entire crane load can be supported by these arms and the base portion. The term "large moment" should be considered in relation to the size of the crane and the maximum load it is designed to lift. Larger cranes capable of lifting larger tower sections require stronger arms, and stronger crane connecting elements must be provided on the tower sections. Smaller cranes that lift smaller tower sections can be built with weaker arms, and weaker crane connecting elements can be provided on the tower sections.The technical expert will be able to determine the necessary strengths and sizes to ensure safe operation of this type of crane. The crane further comprises a lifting arm 22 connected to the base portion 4. The lifting arm is arranged so that it can tilt about a horizontal axis at its connection to the base portion and also pivot about a vertical axis passing through the base portion. The details of the crane's tilting and swiveling mechanism are not shown in detail. In general, the crane's details are shown schematically to illustrate the novel concepts of the invention. However, suitable lifting arms that could be used in this application are known in the art. The actual implementation could differ from that shown in the figures. However, a person skilled in the art can provide the necessary details for implementing the solution based on their common general knowledge of lifting arms. The crane also comprises a cable and pulley system consisting of a hoist cable and several pulleys. The cable and pulley system serves two purposes. The first purpose is to act as a hoist cable for lifting loads with the crane via the hoist hook 30. The second purpose is to lift the crane itself so that it can move up and down the tower. The cable and pulley system will be described in more detail with reference to schematic Figures 15a and 15b. In Figures 11-11b, the details of the cable and pulley system are not shown in detail as they would only complicate the Figures. However, in some of Figures 1a-11b, a thick gray line is provided to schematically illustrate how the main cable 32 of the cable and pulley system could be routed. The cable is shown in a simplified manner to illustrate the concept.In a real-world system, additional details will be provided to ensure safety, strength, and functionality. A person skilled in the art will understand the concept of the present invention and, together with the more schematic illustrations in Figures 15a and 15b, will be able to provide a cable and pulley system that meets the requirements of a real-world system. The main hoist cable is controlled by a winch 34 located on the ground near the base of the tower. The winch is not shown, but its location is indicated by the reference number 34. Therefore, the crane itself does not need to include a hoist winch and does not need to be powered to lift the crane or the tower sections. The entire operation and power supply can remain on the ground. Therefore, the power supply and winch can also function as part of the counterweight for hoisting operations. Instead of having to lift a counterweight to the top of the crane, the counterweight can remain on the ground. Figures 2a and 2b show a second stage in the assembly procedure. In this stage, the main hoist cable 32 is loosened so that the hoist hook 30 (concealed by the boom) is lowered until it makes contact with a crane hoist block 36 (also concealed by the boom). The crane hoist block is attached to the tower section near the crane connecting elements via a crane hoist connecting element 38. This is partially concealed in Figure 2a by one of the booms. The hoist hook is connected to the crane hoist block, and then the crane hoist block is separated from the crane hoist connecting element. The cable is then adjusted as shown in Figures 3a and 3b. As the cable is adjusted, the crane hoist block 36 will rise until it is at the same height as a crane hoist connecting element 38 located near the top of the tower section. The crane hoist block 36 is then connected to the crane hoist connecting element at the top of the tower section. Next, the lifting hook is separated from the crane's lifting block 36, and the cable is further adjusted to move the lifting hook to the upper portion of the lifting arm. This is shown in Figures 4a and 4b. Once the cable is fully tightened, the arms are folded to release the crane's connecting elements on the tower section. This is shown in Figures 5a and 5b. The crane now hangs from the crane hoist block 36 attached to the tower section via the crane hoist connecting element 38. The cable is then further adjusted as shown in Figures 6a and 6b to hoist the crane up the tower. To prevent damage to the tower as the crane ascends, a lower support arm 40 is provided on the crane with rollers 42 that engage with the tower surface and allow the crane to roll upward along the side of the tower section. When the crane reaches the top of the tower, and its boom arms are level with the crane's connecting elements 12 at the top of the tower, the arms pivot again, and the tower flange connecting elements of the boom arms engage with the crane's connecting elements on the tower section. This is shown in Figures 7a and 7b. The crane now moves to the top of the tower section and is once again firmly connected to it via the crane's connecting elements 12. The crane is now ready to lift the next tower section and place it in position. Figures 8a and 8b show how the crane's hoist arm tilts about a horizontal axis to extend over the base tower section so that it is in position to lift the next tower section 44 into place. In this case, as is evident in Figure 8a, the next tower section exerts a relatively high load on the crane's hoist arm. This generates a large moment in the base portion of the crane and is illustrated by arrow X in the figure. This moment is absorbed by the crane arms and transferred to the tower flange through the crane connecting elements 12 in the tower section. Furthermore, as illustrated in Figure 8a, the crane in this configuration also includes an additional moment compensating arm 46 extending from the base portion of the crane. The main hoist cable 32 is passed over this arm, and due to the distance Y between the cable coupling point and the base portion of the crane, the cable itself, together with the arm, will generate a countermoment Z that helps to balance the moment X around the base portion of the crane. In this way, the actual moment transferred to the tower flange can be reduced. ML / a / ZUZ 1 / Ul 4 1 ou Furthermore, the moment compensation arm 46 can be rotated about a horizontal axis so that the horizontal distance Y between the base portion and the cable-jointing portion of the arm can be adjusted. In this way, the moment provided by the moment compensation arm can also be adjusted, although it is not possible to adjust the actual tension in the hoist cable 32. As will be described in more detail later with reference to Figures 12a-13b, the arm can also be rotated around a vertical axis to adjust the direction of the moment compensation. This is relevant when the crane's lifting arm also rotates around a vertical axis, as will be shown in relation to Figures 12a-13b. Figures 9a and 9b show how the upper tower section is installed on top of the base tower section. Once the upper tower section is in place, it and the base tower section can then be bolted together, as is known in the art. This is not described in further detail here. Once the top section of the tower is bolted into place, the crane can release the top section of the tower and restart the crane lifting procedure as illustrated in Figures 2a and 2b. The process can be repeated until the entire tower is built. Once the entire tower is built and the crane is installed on the upper section 48 of the tower, the crane can then lift the nacelle 50 into place, as shown in Figures 10a and 10b. Likewise, after the nacelle is in place, the crane can then lift the blades 52 into place as shown in Figures 11a and 11b. Once the blades are in place, the crane can be lowered by performing the procedure described in Figures 1 a-1 Ib in reverse. In the event that an existing wind turbine needs repair, a similar procedure could be used to hoist the crane to the top portion of the wind turbine tower, after which it can be used to exchange blades, turbines, generators, drives, etc. Figures 12a to 13b show further details of how the moment compensating arm 46 can be rotated about a vertical axis to better compensate for moments during hoisting operations. Comparing Figures 11a and 12a, it can be seen that in Figure 11a the blade load is located on the left side of the derrick. The moment compensating arm 46 is also located on the left side of the derrick. The moment compensating arm 46 therefore increases the moment applied to the derrick flange. However, in Figures 12a and 13a, the moment compensating arm is rotated about the vertical axis so that it extends to the right side of the derrick. In this way, the moments are better balanced. In another configuration (not shown), the moment arm could be in a fixed position relative to the crane's hoist arm. As the hoist arm rotates, the moment arm would also rotate by the same amount. In this way, the moments would always be balanced without requiring additional control of the moment arm's position. This arrangement would also ensure that the cables were less likely to become tangled or twisted together. Figures 14a and 14b illustrate another schematic representation of a crane connecting mechanism. In this case, instead of four connecting elements, only three connecting elements 100 are provided on the tower section and on the crane. The base portion 102 itself connects to one of the connecting elements on the tower section, and then each arm 104 connects to an additional connecting element 100. This illustration is provided in a very schematic way to demonstrate a solution with only three points. It is maintained that a person skilled in the art will be able to implement this in a real-life situation without undue burden. Figures 14a and 14b also schematically illustrate another option for arranging the crane's connecting elements on the tower sections. Since the towers taper from bottom to top, the diameter of the tower sections decreases as the crane ascends. In Figure 14b, the diameter is larger than in Figure 14a. This illustrates the difference between a lower section (14b) and an upper section (14a). However, although the locations of the crane's connecting elements on the circumference change as the crane ascends the tower, the connecting elements are arranged so that the spacing between them and their position on the tower section are adjusted to allow the crane's booms to be attached to different flanges without having an excess of tower flange connecting elements.In the figure, it can be seen that the length X of the arm between the pivot point and the connecting element does not change. However, the diameter of the tower section and the angle between the crane's connecting elements change, as can be seen by comparing the angle between the dashed lines in the figures. In this way, the same connecting elements for the tower and the crane arms can be used all the way up the crane. Figures 15a and 15b schematically illustrate the cable and pulley system used on the crane. Figure 15a is approximately equivalent to a position between Figures 2a and 3a, in which the crane's hoist block 36 is raised halfway to its upper portion, and Figure 15b is approximately equivalent to Figures 6a and 6b. The Figures show a portion of a tower section 1 on the right. A crane hoisting connection element 38 attached to tower section 1 is also shown. The crane's cable and pulley system comprises a crane hoisting block (lower pulley block) 36 and a hoisting block (upper pulley block) 30. In this embodiment, the hoisting block 30 has two pulleys, and the crane hoisting block 36 has only one pulley. Thus, when the two pulley blocks are connected and tension is applied to the cable, both blocks will move upward. When the connection between the blocks is broken, and tension is applied to the cable, the hoisting block 30 will move upward, and the crane hoisting block 36 will move downward. In Figure 15b, the crane hoisting block is attached to the tower and is therefore fixed in its position relative to the tower.As tension is applied to the cable, the crane will rise. Because of this system of cables and pulleys, a single cable from the base of the tower can control the entire crane operation. This covers both the crane's lifting and the loads it lifts when erected. As can be seen in the figure, the hoist cable 32 is pulled at the lower end of the figure by a tension T provided by a winch, which in the current configuration is located on the ground. The hoist cable rises to pulley 36a on the lower pulley block 36, then descends to a lower pulley 37, then rises to an upper pulley 39, and then descends again to pulleys 30a and 30b on the upper pulley block 30 before terminating on the hoist arm. This is a highly simplified arrangement to illustrate the operating principle. In the real world, additional pulleys and cables will be provided, as those skilled in the art will know. It should be noted that the figures and the preceding description show the modality examples in a simple and schematic manner. Many of the specific mechanical details are not shown since a person skilled in the art should be familiar with these details and they would simply complicate this description unnecessarily. For example, the specific materials used, the specific actuators used, and the specific construction of the crane itself are not described in detail, as it is assumed that a person skilled in the art could find suitable materials and processes to manufacture the systems according to the present invention.

Claims

1. A wind turbine tower comprising a first tower section, said first tower section having an upper flange disposed at an upper end of the first tower section, said upper flange comprising one or more flange portions extending horizontally beyond the outer surface of the main body of the first tower section, said one or more flange portions together comprising at least three crane connecting elements, the vertical distance between any two of said at least three crane connecting elements being less than 1 m, a. each of said at least three crane connecting elements being arranged so that a cooperating tower flange connecting element on a crane can be detachably connected to said crane connecting element, and b. said at least three crane connecting elements being spaced apart around the circumference of the first tower section.

2. The wind turbine tower according to claim 1, characterized in that the flange comprises four crane connection elements, and wherein a vector A between a first and a second crane connection element has a length of at least 200 cm and a vector B between a third and a fourth crane connection element has a length of at least 200 cm.

3. The wind turbine tower according to claim 1 or 2, characterized in that said at least three crane connection elements are arranged essentially in the same plane.

4. The wind turbine tower according to any of claims 1 to 3, characterized in that the vertical distance between any three of said, at least, three crane connection elements is less than 50 cm.

5. The wind turbine tower according to any of claims 1 to 4, characterized in that the vertical distance between the highest of any three of said, at least, three crane connection elements and the lowest of any three of said, at least, three crane connection elements is less than 50 cm or less than 25 cm.

6. The wind turbine tower according to any of claims 1 to 5, characterized in that the wind turbine tower further comprises a second tower section disposed in the upper portion of the first tower section, the second tower section having an upper flange comprising one or more flange portions extending horizontally beyond the outer surface of the main body of the first tower section, said flange portions comprising together at least three crane connection elements, the vertical distance between any two of said at least three crane connection elements being less than 1 m, a. each of said at least three crane connection elements being arranged so that a cooperating tower flange connection element on a crane can be detachably connected to said crane connection element, and b.These at least three crane connection elements separate around the circumference of the first tower section.

7. The wind turbine tower according to claim 6, characterized in that the flange of the second section of the tower comprises four crane connection elements, and wherein a vector C between a first and a second crane connection element has a length of at least 200 cm and a vector D between a third and a fourth crane connection element has a length of at least 200 cm.

8. The wind turbine tower according to claim 7, characterized in that the angle between vectors A and B is greater than the angle between vectors C and D, but in that the length of vectors A and C is the same and in that the length of vectors B and D is the same.

9. The wind turbine tower according to any of claims 6-8 characterized in that said at least three crane connection elements of the second tower section are arranged essentially in the same plane.

10. The wind turbine tower according to any of claims 6 to 9, characterized in that the vertical distance between any three of said, at least, three crane connection elements of the second tower section is less than 50 cm.

11. A crane comprising a base portion, two arms movably connected to the base portion, and a lifting arm movably connected to the base portion, said lifting arm being provided with a lifting cable and a lifting member, for example, a lifting hook, for lifting a load, characterized in that: a. the two arms and the base portion in combination comprise at least three tower flange connecting elements arranged to be detachably connectable to cooperating crane connecting elements on a flange of a wind turbine tower section; b. in that each arm comprises one of the tower flange connecting elements; and c. in that the vertical distance between any two tower flange connecting elements in the normal operating position of the crane is less than 1 m, less than 50 cm, or less than 25 cm.

12. A crane according to claim 11, characterized in that the crane comprises four tower flange connection elements and in that each of the two arms comprises two tower flange connection elements.

13. A crane according to claim 11, characterized in that the crane comprises four tower flange connection elements and in that the crane comprises four arms, each arm comprising one of the four tower flange connection elements.

14. A crane according to any of claims 11-13, characterized in that the vertical distance between any three of the at least three tower flange connection elements is less than 50 cm or less than 25 cm.

15. A crane according to any of claims 11-14, characterized in that said at least three tower flange connection elements are arranged essentially in the same horizontal plane.

16. A crane according to claim 13, characterized in that the four tower flange connection elements are arranged essentially in the same horizontal plane.

17. A crane according to any of claims 11 to 16, characterized in that the crane further comprises a cable and pulley system comprising the lifting cable and the lifting member.

18. A crane according to claim 17, characterized in that the cable and pulley system comprises a lower pulley block comprising a pulley and an upper pulley block comprising at least one more pulley than the lower pulley block, the upper pulley block comprising the lifting member and the lower pulley block comprising a first connecting element suitable for establishing a detachable connection to the lifting member and a second connecting element suitable for establishing a detachable connection to a crane lifting connecting element disposed in a tower section of a wind turbine tower when the crane is connected to a tower section.

19. A crane according to any of claims 11 to 18, characterized in that the crane further comprises a moment compensation mechanism comprising a moment compensation arm at least 300 cm long and extending from the crane with a horizontal component, the end of said arm being connected by a cable to a winch located away from the crane.

20. A crane according to any of claims 11 to 19, characterized in that the length of the lifting arm is such that the vertical distance between the highest location of the lifting member and the connecting elements of the tower flange is greater than 5 m, greater than 10 m or greater than 20 m.

21. A crane according to claim 20, characterized in that said vertical distance is greater than the height of a tower section.

22. An assembly comprising a wind turbine tower according to any one of claims 1 to 10, a crane according to any one of claims 11 to 21 connected to a flange of a tower section of the wind turbine tower, and a winch located near the base of the wind turbine tower, said winch comprising a cable connecting to the cable and pulley system of the crane.

23. A method for assembling a wind turbine tower comprising the following steps in this order: a. joining a tower connecting section of a crane to a crane connecting element on a tower section, b. providing a hoist arm, an upper pulley block, a lower pulley block, and a hoist cable, said hoist cable being arranged to run from a location below the crane to and over the lower pulley block, down and around a pulley attached to the crane, up and around a pulley on the upper portion of the crane, down and around the upper pulley block, and to the upper portion of the crane, c. lowering the upper pulley block from the crane, d. joining the upper pulley block to the lower pulley block, e. raising the lower pulley block by adjusting the hoist cable that raises the upper pulley block, f.g. Attach the lower pulley block of a connecting element to a tower section, h. Release the upper pulley block from the lower pulley block, i. Adjust the hoist cable until the crane is supported by the hoist cable, j. Release the crane tower connecting section from the crane connecting element on the tower section, k. Further adjust the hoist cable to raise the crane along the tower section, and l. Attach the crane tower connecting section to an upper crane connecting element on the tower section.

24. A method according to claim 23, characterized in that the method further comprises the steps of providing at least one pulley in the lower pulley block and providing a number of pulleys in the upper pulley block that is greater than the number of pulleys in the lower pulley block.

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