WO2014068592A1

WO2014068592A1 - Tower for a wind turbine

Info

Publication number: WO2014068592A1
Application number: PCT/IN2013/000662
Authority: WO
Inventors: Yogesh Jogindernath MEHRA
Original assignee: Mehra Yogesh Jogindernath
Priority date: 2012-10-31
Filing date: 2013-10-30
Publication date: 2014-05-08

Abstract

The present subject matter relates to a tower (100) for supporting a wind turbine. The tower (100) comprises at least two tubular tower sections (102-1, 102-2). Each of the tower sections (102-1, 102-2) are of predefined thickness. Further, the tower (100) comprises at least one tower hub (104) and the thickness of the tower hub (104) is greater than the predefined thickness of the tower sections (102-1, 102-2).

Description

TOWER FOR A WIND TURBINE

TECHNICAL FIELD

[0001] The present subject matter is related, in general, to wind turbines and, in particular to a tower assembly for the wind turbines.

BACKGROUND

[0002] In recent times, wind turbines have received attention as environmentally safe and relatively less expensive alternative energy sources. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient. Generally, wind turbines include a tower, a nacelle located on the tower, and a rotor that is supported in the nacelle by means of a shaft. The wind turbines require assembly at remote facilities, where pre-fabricated components of the wind turbines must be transported and assembled.

[0003 J Generally, the tower is about 40-150 meters in height. The height of the tower can further increase as power requirement increases. The construction of wind turbines with supporting towers having a height of hundreds of feet is difficult, dangerous, and very expensive. Further, the massive foundations required for such exceptionally high towers also add to the overall cost of the wind turbines. Additionally, the large sized components of such exceptionally high towers are to be transported at the erection site. In case, the jurisdiction where the wind turbine is to be installed may impose size-related limits on cargo which can be transported and so, transportation of such components could also pose many challenges.

BRIEF DESCRIPTION OF THE DRAWINGS

[0004] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[0005] Figure 1 illustrates a schematic representation of a tower assembly for supporting a wind turbine according to an embodiment of the present subject matter. [0006] Figure 2 illustrates a schematic representation of perspective view of a tower hub, according to a further embodiment of the present subject matter.

[0007] Figure 3 illustrates a schematic representation of top view of a tower hub, according to a further embodiment of the present subject matter.

[0008] Figures 4 and 5a illustrate a schematic representation of a tower assembly for supporting a wind turbine according to further embodiments of the present subject matter.

[0009] Figures 5b illustrate a schematic representation of top view of a tower assembly for supporting a wind turbine according to a further embodiment of the present subject matter.

[0010] Figure 6 illustrates a schematic representation of a tapered tower hub, according to a further embodiment of the present subject matter.

[0011] Figure 7 illustrates a schematic representation of one of tower section with integrated supporting members, according to a further embodiment of the present subject matter.

[0012] Figure 8 illustrates a schematic representation of a tower assembly for supporting a wind turbine according to a further embodiment of the present subject matter.

[0013] Figure 9 illustrates a schematic representation depicting the variations in wind directions during the year and corresponding orientation of supporting members to provide maximum support for the tower for wind turbine, according to one embodiment of the present subject matter.

[0014] It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative tower assembly embodying the principles of the present subject matter.

SUMMARY

[0015] This summary is provided to introduce concepts related to wind turbine tower, and the concepts are further described below in the detailed description. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter. [0016] In one implementation, the present subject matter relates to a tower for supporting a wind turbine. The tower comprises at least two tower sections. Each of the tower sections are of predefined thickness. The tower further comprises at least one tower hub. The thickness of the tower hub is greater than the predefined thickness of the tower sections.

DETAILED DESCRIPTION

[0017] The subject matter described herein relates to a tower assembly for a wind turbine, according to an embodiment of the present subject matter.

[0018] With rapid depletion of non-renewable energy resources due to excessive usage, utilization of renewable energy resources is being encouraged worldwide. Wind energy, being one of the renewable energy resources, has gained popularity as an alternative renewable power source for electricity generation. Consequently, frequent developments are emerging in the wind energy realm aiming towards improving overall efficiency of wind power generation.

[0019] In recent times, wind turbines have evolved in various aspects of power generation, such as efficiency, economy, and capacity. To comply with increased power requirements, modern wind turbines have also grown in terms of the power that they can generate: The increase in the demand of power output from such wind power installations has resulted in the increase in size of the wind turbine and the wind power generators.

[0020] One of the major factors affecting the capacity of wind turbines is the height of the supporting structure. Taller supporting structures, such as taller towers, enable the wind turbine to capture more wind power at higher elevation, resulting into more power generation. Therefore, a suitable supporting structure is desired to handle wind turbines with larger capacity, and correspondingly a larger size.

[0021] However, as the height of the wind turbine increases, load experienced by the tower also increases. To withstand the increased loading, these taller towers may be conventionally tapered, i.e., diameters of such towers increase towards the base of the tower. Therefore, such towers possess a larger tubular base. Although, such towers with the larger tubular base provide additional strength to the structure, it may also impose certain drawbacks. For example, costs associated with manufacturing of such tapered towers with huge and, thus heavy base are high. Further, area covered by such towers at the base may be large, and therefore may also require a larger foundation. Consequently, such towers may involve significant cost due to the requirement of extra raw material, special production equipment, special transport arrangements, and special equipment and skills to install such towers at the site.

[0022] Conventionally, such tapered wind turbine towers can be prefabricated in sections. Towers for wind turbine assembled from a plurality of tower sections allow lower manufacturing and transportation costs. For example, the tower sections can be easily transported from one location to another, and later assembled at the required site. However, manufacturing such tapered tower sections may be costly, as a large number of differently sized tower sections have to be manufactured, which in turn would require special equipment for manufacturing the tower sections of varying dimensions.

[0023] Further, various jurisdictions may have their set of regulations for transportation of large sized components. For example, clearance height for bridges and tunnels may be fixed. Therefore, transportation may be a concern in such jurisdictions which impose one or more of upper limits for load, sizes and weights of articles that may be transported via roads present in such jurisdiction. For example, transportation of the towers having large cross- sectional area may also prove to be a challenge as the dimensions of such towers may not conform to the clearance heights for bridges or tunnels that may be used for transportation. Further, as mentioned above, in case of the tapered towers, i.e., towers with varying diameter, assembling the tower sections of different cross sections at the site leads to inconvenience, and additional cost. Therefore, the tapered towers may prove to be limiting factors in aspects relating to wind tower erection, such as site selection and transportation.

[0024] In various implementations of the present subject matter, a tower assembly for a wind turbine is described. As would be appreciated by a person skilled in the art, a wind turbine includes a tower, a nacelle mounted on the tower, and a rotor hub carrying a blade assembly coupled to a power generator mounted on the nacelle. Towers for wind turbines may be tubular steel towers, lattice towers, concrete towers, or hybrids variants of such types of towers.

[0025] The present invention relates to a tower assembly for a wind turbine. In one implementation, the tower assembly, also interchangeably referred to as a tower, is assembled from a plurality of tower sections and one or more tower hubs. The tower is assembled such that at least one tower hub is used as a connecting member between any two tower sections. The tower hub acts a transition piece between the two tower sections for carrying static and dynamic loads from top to bottom of tower. The one or more tower sections and the tower hubs can be connected together by various means conventionally known in the art. Example of such means include, but are not limited, to flanges. In certain cases, the tower sections and the tower hubs can be joined together, during assembling, by welding. These, and other aspects, are provided in greater detail in the sections that follow.

[0026] As mentioned previously, transportation of large sized components of the wind turbine can be a challenge. This is further compounded in cases where the jurisdictions, where such installations are to be implemented, carry a statutory limit on the size of the components that can be transported. In one implementation, each of the tower sections is defined by an inner and an outer diameter. The outer diameter of the one or more tower sections and/or the tower hubs can be selected such that the outer diameter is substantially uniform or equal, i.e., the tower of the wind turbine formed after assembling the tower sections and the tower hubs would have a constant diameter, and therefore have a uniform outer profile. As would be appreciated by a person skilled in the art, such a tower for a wind turbine would be having a constant outer diameter throughout its length. The constant outer diameter may be less than an outer diameter of a tower base of a conventional wind turbine. In this way, mass and cost of the tower is lowered, and at the same time transportation issues are avoided.

[0027] In order to achieve same or even better stability and load bearing capacity for the tower having constant and reduced outer diameter as that of conventional tapered towers with huge and heavy tower bases, in one implementation, the tower hub may be provided with protrusions or supporting arms for connection with one end of supporting members. Other end of the supporting members may be anchored in ground on foundations, which may be separate from a main foundation of the tower. The tower hub acts a transition piece also between an upper tower section and a supporting member for carrying static and dynamic loads. In this way, production and transportation costs of the tower can be lowered without compromising with stability and load bearing capacity of the tower.

[0028] Further, the tower hubs along with the supporting arms may be provided as a single piece. In one implementation, the supporting members may be connected with the tower hub through a flange connection provided on an outer surface of the tower hub. The supporting arms further include means for connecting to a plurality of supporting means. The supporting means can be flexible, such as guy wires, or can be rigid, such as guy tubes. In such a case, one end of the supporting means would be connected to the supporting arms with their one end rigidly connected to the ground, thereby providing support to the tower. The supporting members or means can be distributed around the outer diameter of the one or more tower hubs. Further, the supporting members or means may be attached with the tower hub at a pre-defined angle based on location of site.

[0029] As described previously, the tower is composed of a plurality of tower sections and a plurality of tower hubs. For high capacity wind turbines, the height of the tower might be close to or greater than 100 meters in length. In such a case, the number of tower sections is also likely to be large. As the wind turbine having a generator is mounted upon the tower assembly, each of the tower sections may experience greater stresses. To this end, the tower hub placed between two tower sections can be so structured so as to provide support for the one or more tower sections. For example, in an implementation, the tower hubs can be such that they have a thickness greater than the thickness of the tower sections connected with it. As explained previously, the outer diameter of the tower sections and the one or more tower hubs can be equal. However, the inner diameter of the tower hub can be so selected such that it is less than the inner diameter of the tower sections. The resulting thicker tower hub, in turn, provides additional supporting strength to the assembled tower for wind turbine. At least one of the tower hubs can be further provided with supporting members.

[0030] Further, in one implementation, the plurality of tower sections and the tower hubs are made of steel. However, other material when used for manufacturing the tower sections and tower hubs would also be within the scope of the present subject matter. Furthermore, in another implementation, the tower sections and the supporting members may be manufactured by spiral tube manufacturing process. As would be appreciated by a person skilled in the art, manufacturing the tower sections and the supporting members by spiral tube manufacturing process provides cost efficient production of tower sections and thus helps in reducing the cost of the tower assembly.

[0031] It may also be the case that the outer diameter of two or more tower sections is different. In such a case, the tower for the wind turbine can be formed by tower sections of largest outer diameter forming the base, the smaller outer diameter tower sections forming the middle portion of tower, and the smallest outer diameter forming the top or the higher portions of the tower for the wind turbine. In one implementation, the tower hubs can be such that they are tapered in shape so as to provide an adequate supporting contact between the lower and the upper tower sections.

[0032] In yet another implementation, the tower for the wind turbine can be composed of only one or more_j tower sections. In such a case, the tower sections can be welded together for assembling the tower for the wind turbine. Continuing with the present implementation, at least one of the tower sections can be provided with supporting members for providing support to the assembled tower for the wind turbine. The resulting tower for the wind turbine would have a constant outer diameter. As would be appreciated by a person skilled in the art, the tower so formed can be of varying shape. For example, the tower, and consequently the tower sections and the tower hubs can be tubular in shape or can have a polygonal shape as well, without deviating from the scope of the present subject matter.

[0033] As mentioned previously, the supporting members can be rigid or flexible. Example of such supporting members include, but are not limited to, guy pipes, guy tubes or pre-stressed wires, for providing support of the tower with the ground. In another implementation, any combination of guy tubes and pre-stressed wires may also be used for supporting the tower. Further, the supporting members may be distributed about the tower hub and may be attached to the tower hub via one or more flange couplings or via "tubular connections". The supporting members can extend radially outwards and vertically downwards from the flange couplings to the ground, where they can be rigidly attached. In a preferred implementation, the flange couplings may include structural flanges to achieve a firm connection between the tower hub and the supporting members. As would be gathered, the present subject matter allows for towers for wind turbines which are more stable, and which allows for the installations of large wind turbine at higher heights, i.e., in excess of one hundred meters. Furthermore, it would also be gathered that uniformly shaped and profiled towers for wind turbines also result in saving space within the immediate vicinity of the wind turbine, and thereby overcoming the need for installing tower for wind turbines having a broad or a large base.

[0034] Figure 1 illustrates a schematic representation of a tower 100 for supporting a wind turbine, according to an embodiment of the present subject matter. In present implementation, the tower 100 is shown to be tubular. It should be noted that the same is for purposes of explanation only and should not be considered for limiting the scope of the present subject matter. Other implementations, such as polygonal, are also possible without deviating from the scope of the present subject matter. As illustrated, the tower 100 may include a plurality of tower sections 102-1; 2...n (collectively referred to as tower sections 102), and one or more tower hubs, such as tower hub 104, each hub connecting two adjacent tower sections. In one implementation, a steel tower 100 may be assembled from the tower sections 102 and the tower hubs 104. In an implementation, the tower sections 102 are similar in construction, i.e., have the same dimensions including outer and inner diameters and the same shape. Therefore, the tower sections 102 may be assembled interchangeably and thereby reducing the production costs and the time and the efforts required for assembling the tower 100 at a site.

[0035] Further, the tubular steel tower may be assembled such that the tower hub 104 serves as a connecting member between an upper tower section, tower section 102-1, and a lower tower section, tower section 102-2, while assembling. In one implementation, the tower sections 102 and the tower hubs 104 may be made of steel. Figure 1 as provided illustrates an implementation with one tower section 102 between two tower hubs 104. As would be appreciated by a person skilled in the art, the number of tower sections 102 between two tower hubs 104 can be more than one, without deviating from the scope of the present subject matter. [0036] As indicated in the present figure, each of the plurality of the tower sections 102 may have an inner diameter 102a and an outer diameter 102b. The inner diameter 102a and the outer diameter 102b of the tower sections 102 may remain constant throughout the length of the tower sections 102. Further, each of the tower sections 102 includes two opposing ends. In one implementation, each end of the tower sections 102 may further include one or more flanges 108a-b (collectively referred to as 108) for allowing the one or more tower sections 102 to be connected with either another tower section 102 or with the tower hub 104. In one embodiment, such flanges 108 may be provided as an integral piece with the tower sections 102. However, in another embodiment, such flanges 108 may also be provided a separate element mountable to the tower sections 102. The tower hub 104 is further illustrated in Figures. 2-3. In another implementation, the outer diameter 102b of the tower sections 102 may be such that the same is in compliance with the transportation rules and regulations in a specific jurisdiction. In yet another implementation, the thickness of the tower section(s) 102 may be about 25 mm.

[0037] As mentioned above, the tower hub 104 may be formed to serve as a connecting member between the upper tower section 102-1 and the lower tower section 102-2. In other words, the tower hub 104 serves as a transition zone between the tower sections 102, and the supporting members 106. The tower hub 104 further has an inner diameter 104a and an outer diameter 104b. In one implementation, the outer diameter 104b may be similar to the outer diameter 102b of the tower sections 102. Therefore, when assembled, the tubular steel tower may possess a uniform outer profile with a constant outer diameter throughout its length.

[0038] As would be gathered, the size of the tower sections 102 and the tower hub 104 is substantially the same. Thus, in such a case, each of the tower sections 102 and the tower hub 104 can be transported without violating the prevailing local transportation size limits. Furthermore, this would also allow for using the same infrastructure for transporting the similarly sized components, thereby also reducing the transportation costs.

[0039] In another implementation, the inner diameter 104a of the tower hub 104 may be less than the inner diameter 102a of the tower sections 102. Consequently, the wall thickness of the walls of the tower hub 104 may be greater than wall thickness of the tower sections 102. In a further implementation, the inner diameter 104a of the tower hub 104 may be selected so that the wall thickness of the tower hub 104 is twice the wall thickness of any one or more of the tower sections 102. The tower hub 104, in such a case, provides greater structural integrity to the steel tower 100, and a very stiff connection point for a plurality of supporting members 106 surrounding the tower hub 104. For example, the plate thickness and the material can be so selected such that the same is sufficient to address instability associated with the natural frequency of the tower. As would be gathered, the motion of the rotor blades of the wind turbine may induce certain vibrations within the tower of the wind turbine, the frequency of which may correspond to the natural resonant frequency of the tower. This may affect the stability of the tower. In the present subject matter, the tower hub 104 imparts greater structural ability and strength to the resulting tower for wind turbine.

[0040] Further, as illustrated in Figure 1, in one implementation, the tower hub 104 may be coupled with the upper tower section 102-1 and the lower tower section 102-2 through an upper flange connection 108-1 and a lower flange connection 108-2, respectively.

[0041] In yet another implementation, the tower 100 may include the plurality of supporting members 106 to provide the tubular steel tower with additional stability and strength to withstand the pressure and tension caused by the forces acted upon by wind. In one implementation, at least three supporting members 106 are to be arranged around the circumference of the tubular steel tower. In one implementation, the three supporting members 106 may be provided around the circumference of the tubular steel tower, equidistant from each other.

[0042] Each of the supporting members 106 further includes a first end and a second end. In one implementation, the supporting members 106 may be one or more guy tubes, guy pipes for providing a rigid support, or pre-stressed cables or wires for providing a non-rigid or flexible support. In one implementation, the first end of each of the supporting members 106 is attached to an outer surface of the tower hub 104 through a flange connection 110 or a "tubular connection". In the present implementation, each of the flange connection 1 10 may lie on the vertex of an equilateral triangle. Further, from the flange connection 110, each of the supporting members 106 extend radially outward and in a downward direction to be fixedly attached to the ground, or may be configured to be mounted onto a suitable ground foundation (not shown). In one implementation, the foundation of the tower may be different from the foundation provided to support the supporting members 106 at the ground. Further, the foundation of the supporting members 106 may be provided with an earth-cover for providing an additional strength to the foundation.

[0043] Figures 4 and 5a illustrate a schematic representation of a tower assembly for supporting a wind turbine according to different implementations of the present subject matter. In the present implementation, when more supporting members 106 are used, the first end of the supporting members 106 may be attached to two or more tower hubs 104 at different heights. In such a case, then the opposite or the second foot end of the plurality of supporting members 106 may be mounted on a common ground foundation (not shown). In one implementation, if the first end of the plurality of supporting members 106 is attached at more than one height, then the opposite foot end of the plurality of supporting members 106 may also be mounted on different ground foundations. In this implementation, the plurality of supporting members 106 which are attached at a higher point to the tubular steel tower may have a separate ground foundation at a greater distance from the tubular steel tower than the ground foundation for the plurality of supporting members 106 attached at a lower point to the tubular steel tower (or vice versa).

[0044] In all possible arrangements, the first end of the plurality of supporting members 106 may always be attached to the tower hub 104 at any point below the lowest point attained by a blade tip during its rotation. This provides freedom of rotation to the blades without causing interference with the supporting members 106.

[0045] As shown in Figure 4 the plurality of supporting members 106 being guy pipes may have any shape, e.g., circular, oval, rectangular etc. Further, the guy pipes may be hollow or solid. In yet another implementation, the supporting members 106 may be arranged around the tubular steel tower in pairs.

[0046] As shown in Figure 5a, the supporting members 106 can be further comprised of one or more pre-stressed wires. As would be appreciated by a person skilled in the art, pre- stressed wires are non-rigid and provide a flexible mechanism for providing support in the supporting members 106. In one implementation, the supporting members 106 can be further implemented with stress/strain sensors. Such sensors can be configured to determine the level of stresses that develop within the supporting members 106. In one implementation, a tensioning control mechanism can be provided for further controlling the tension experienced by the supporting members 106. In one implementation, the tensioning control means can be further configured to control the operation of the wind turbine on determining the stress/strain levels to be above a predefined threshold limit. One example of the tensioning control means is a turnbuckle. Such a turnbuckle may be used with fastening nuts for adjusting tension experienced by the supporting members 106.

[0047] As mentioned earlier, the tubular steel tower may be supported by the plurality of supporting members 106 around the circumference. In one implementation, three supporting members 106 may support the tubular steel tower. The supporting members 106 may be placed equidistant from each other, i.e., 120 degrees apart. The holes shown on the top of the tower hub 104 may facilitate the flange connection 108 with the tower section 102. In one implementation, the supporting members 106 may not be equidistant from each other. In such a case, the positioning of the supporting members 106 can be based on the wind profile map for a certain geographic location. For example, the wind profile map may indicate a predominant wind direction for a certain region or location. Depending on the predominant wind direction, the positioning of the supporting members 106 can be thus selected to ensure that optimum support is provided to the wind turbine.

[0048] Figure 5b illustrates the top view of a tower assembly 100 for supporting a wind turbine according to a different implementation of the present subject matter. In the present implementation, the supporting members 106 are connected to each other via horizontal support members 502. The horizontal support members 502 provide additional structural stability to the tower assembly 100. In one example, the horizontal support members 502 may connect the supporting members 106 with each other at mid points of the supporting members 106. However, in other examples, the horizontal support members 502 may connect the supporting members 106 with each other at points other than the mid points of the supporting members 106. [0049] Figure 6a illustrates a schematic representation of an assembled tower for wind turbine using tower sections 602, each of the tower sections 602 having constant but different diameters. For example, as illustrated in Figure 6, both tower section 602-1 and tower section 602-2 are tubular and have constant respective diameters. However, the diameter of the upper tower section 602-1 is less than the diameter of the lower tower section 602-2. The tower sections 602 are connected to each other through a conically shaped or tapered tower hub, such as tower hub 604, shown in figure 6b. As mentioned earlier, in one implementation, a tower hub 604 may be tapered, i.e., the cross-section of the upper portion of the tower hub 604 is less than the cross-section of the lower portion of the tower hub 604. Each of the tower sections 602-1 and 2, can be joined with the tapered tower hub 604 via one or more flange couplings 608-1 and 2, respectively.

[0050] Similarly, in cases where the tower is assembled form a number of tower sections 602 that is greater than two, the diameter of each of the tower sections 602 can be so selected, such that the diameter of the tower sections 602 decreases with their relative position along the length of the tower extending vertically in the upward direction. Therefore, the diameter of the lowest tower section, such as tower section 602-2, is the largest and the diameter of the other tower sections (not shown in the figure) decreases along the heights of the tower at predetermined heights. As would be appreciated by a person skilled in the art, the broader base provided by the lowest tower section, i.e., tower section 602-2 provides additional support. Furthermore, other tower sections having a smaller cross-section would also involve lower manufacturing as well as lower transportation costs.

[0051] Further, the tower hub 604 may be produced, such as by casting, in a single piece, i.e., the tower hub 604 may be provided with protrusions or supporting arms 606 for connection with one or more supporting members (not shown in the figure). The provision of the supporting arms 606 integral to the tower hub 604 provides a stronger and efficient load bearing structure and also enables to control stresses at connection point of the one or more supporting members and the tower hub 604. In one implementation, a flange connection 610 may be provided at the open end of the supporting arms 606 with the one or more supporting members and thereby ensuring additional strength and stability to tower assembly. As would be gathered by a person skilled in the art, the tower hub 604 further experiences the stress and/or strain due to the load of the dynamic loading on the wind turbine. In one implementation, the tower hub 604 can be manufactured as a single casted component. In one implementation, the tower hub 604 can be used along with conical shaped tower sections 602-

1, 2, to result in a tower for a wind turbine having a conical profile, but with a smaller outer diameter when considered with respect to conventional towers for wind turbine.

[0052] Figure 7 illustrates a schematic representation of one of the tower sections with integrated supporting members, according to a further embodiment of the present subject matter. In one implementation, the tower 100 can include at least three tower sections 702-1,

2, and 3. In the present implementation, the tower sections 702-1 and 702-3 are connected via the tower section 702-2. In the present implementation, the tower section 702-2 is used as a tower hub to connect the tower sections 702-1 and 702-3. In the present implementation, the tower section 702-2 is of same dimensions as the tower sections 702-1 and 702-3, but includes features of the tower hub. Each of the tower sections 702-1, 2 and 3 are further characterized by an inner and an outer diameter. Each of the respective inner diameters of the tower sections 702-1, 2 and 3 are equal. Similarly, each of the respective outer diameters of the tower sections 702-1, 2 and 3 are also equal. The resulting tower for the wind turbine would also consequently have a uniform outer profile along its entire length. Each of the tower sections 702-1, 2 and 3 can be joined to each other by methods which are conventionally known in the art. For example, the tower sections 702-1, 2 and 3 can be joined together by welding.

[0053] Continuing with the present implementation, the tower section 702-2 can be further integrally provided with a plurality of supporting members 704 for providing support. The supporting members 704 can be distributed about the tower section 702-2. In one embodiment the supporting members 704 can be integrated with multiple tower sections, say tower sections 702-1, 2 and 3.

[0054] Figure 8 illustrates a schematic representation of a tower assembly for supporting a wind turbine according to a further embodiment of the present subject matter. As mentioned earlier, in one implementation, tower assembly 800 may include a plurality of supporting members 802, such as guy pipes and pre-stressed wires to provide a tubular steel tower with additional stability and strength to withstand the pressure and tension caused by the forces acted upon by wind. Continuing with the present implementation, the tower assembly 800 may include a plurality of horizontal tubes 804. In one implementation, the plurality of horizontal tubes 804 is provided to structurally strengthen the supporting members 802. As would be appreciated by a person skilled in the art, the horizontal tubes 804 at one end may be connected to the supporting members 802 by conventional methods of attachment, such as welding, bolting, etc. In one implementation, one end of the plurality of horizontal tubes 804 and the supporting members 802 is connected to a tower hub or a tower section of the tower assembly 800. In the same implementation, other end of supporting members 802 is connected to ground, optionally via a foundation. In another implementation, the supporting members 802 can be coupled to vertically extending supporting tubes such that the supporting members 802 are horizontally oriented with respect to the ground. As per the previous implementation, the supporting members 802 extend from the transition piece to the vertically extending supporting tubes.

[0055] Further, providing the horizontal tubes 804 may result in reduction of buckling length of the supporting members 802, thereby reducing their weight. Furthermore, lesser weight of the supporting members 802 may facilitate convenient replacement and subsequently easy maintenance. In one implementation, due to the support of the horizontal tubes 804, the supporting members 802, instead of being in straight line between the point of joining with the tower and the point of joining with the ground, may be bent from a point where the horizontal member is attached to the supporting member. Bending of the supporting members 802 ensures a favorable angle between the supporting members 802 and the tubular steel tower. Subsequently, the favorable angle provides a stronger support to the supporting members 802, thereby ensuring additional strength to the tubular steel tower. In one example, the favorable angle may be selected based on one or more parameters, such as height of the tower hub, diameter of the tower base, load calculation, and mass of the tower.

[0056] Figure 9 provides a wind map indicating the variations of wind energy through the year and how the same can be utilized for determining an optimum position for the one or more supporting members. As explained previously, the wind tower can be supported by way of one or more supporting arms, each of which can be connected to supporting members. Examples of such supporting members include, but are not limited to, guy pipes, guy tubes or pre-stressed wires. The supporting members can be distributed about the wind tower and may be placed equidistant from each other, i.e., 120 degrees apart. In one implementation, the positioning of the supporting members can be based on statistical variations in wind speeds over the year. For example, Figure 9(a) indicates a wind map 900 indicating the average wind speeds that have been recorded for a specific location. Wind maps may differ for different locations. It should be noted that the present wind map is only illustrative and should not be construed as a limitation to the present subject matter.

[0057] As can be gathered from the wind map 900, the highest average wind speeds are recorded during the months of July-September. Furthermore, nearly during the entire period high wind speeds are found to be prevailing from the south-west direction. Consequently, it can be concluded that the tower for wind turbine is likely to experience highest levels of mechanical stresses due to winds blowing from the south-west direction. Based on the assessment, the positioning of the supporting members, such as supporting members 902 can be such that the supporting members 902 are able to provide the maximum support during such high wind speed conditions. For example, the supporting members 902 can be so positioned such that the area enclosed by supporting members 902-1 and 902-2 face the incoming winds from the south-west direction. When implemented, the supporting members 902 provide maximum support in highest mechanical stress conditions experienced during the high wind speed conditions in the aforementioned months. It should be noted that the present implementation is only one of the many possible implementations of the present subject matter. Different positioning of the supporting members is possible for other locations and for other wind variations. Furthermore, based on the average speeds and the recorded directions, a further determination can also be made as to the number of supporting members that might be required for providing the optimum support. In one implementation, the positioning of the supporting members can be based on one or more arrangements as depicted in any of the preceding figures.

[0058] Although embodiments for a tower for wind turbine have been described in language specific to structural features and/or methods, it is to be understood that the invention is not necessarily limited to the specific features or methods described. Rather, the specific features and methods are disclosed as exemplary implementations of the claimed subject matter.

Claims

I/We claim:

1. A tower (100) for a wind turbine, the tower comprising: at least two tower sections (102-1, 102-2); and at least one tower hub (104) connecting the at least two tower sections (102-1, 102-2), wherein a wall thickness of the at least one tower hub is greater than a wall thickness of each of the at least two the tower sections (102-1, 102-2).

2. The tower (100) as claimed in claim 1, wherein the at least two tower sections (102-1, 102-2) and the at least one tower hub (104) are made of steel.

3. The tower (100) as claimed in one of claims 1 and 2, wherein each of the tower sections (102-1, 102-2) is of a uniform cross-section having a uniform inner diameter (102a) and a uniform outer diameter ( 102b) .

4. The tower (100) as claimed in one of claims 1-3, wherein the at least one tower hub (604) is tapered, wherein area of upper cross-section of the at least one tower hub (104) is smaller than area of lower cross-section of the at least one tower hub (104).

5. The tower (100) as claimed in claim 4, wherein cross-section of the tower section (602-1) attached to the upper portion of the tower hub (604) is equal to the upper cross-section of the tower hub (604) and cross-section of the tower section (602-2) attached to the lower portion of the tower hub (604) is equal to the lower cross-section of the tower hub (604).

6. The tower (100) as claimed in one of claims 1-3, wherein the at least one tower hub (104) is of an outer diameter (104b) is equal to the outer diameter (102b) of any of the tower sections (102-1, 102-2).

7. The tower (100) as claimed in one of claims 1-3 and 6, wherein the wall thickness of at least one tower hub (104) is about twice the wall thickness of each of the at least two tower sections (102-1, 102-2).

8. The tower (100) as claimed in one of claims 1-7, wherein one or more of the tower hubs (104) are associated with a plurality of supporting members (108) for providing a support to the tower assembly, when assembled.

9. The tower (100) as claimed in claim 8, wherein the supporting members (108) are connected with each other via horizontal support members (502).

10. The tower (100) as claimed in claim 8, wherein the supporting members (108) are selected from a group comprising of guy tubes and guy pipes for providing the support to the tower with the ground.

11. The tower (100) as claimed in one of claims 8-10, wherein the supporting members (108) are attached around the circumference of the at least one tower hub (104) via one or more flange couplings (106).

12. The tower (100) as claimed in one of claims 8-11, wherein position of the supporting members (108) is determined based on one of statistical variations in wind speed and direction of wind for a geographical location.

13. The tower (100) as claimed in one of claims 8-12, wherein, the supporting members (108) extend radially outwards and vertically downwards from the flange couplings (106) towards and are rigidly attachable to the ground.

14. The tower (100) as claimed in one of claims 1-13, wherein the at least one tower hub (104) includes a plurality of integral protrusions (606) for connecting the supporting members (108).

15. The tower (100) as claimed in one of claims 1-14, wherein the at least one tower hub (104) includes a radial hole for allowing entry for maintenance.

16. The tower (100) as claimed in one of claims 1-15, wherein each of the tower sections (102-1, 102-2) and the at least one tower hub (104) is further provided with flanges to allow connection of the tower sections (102-1, 102-2) and the tower hub (104) at the time of assembly.

17. The tower (100) as claimed in one of claim 8-16, wherein at least one of a connection between the supporting members (108) and the at least one tower hub (104), and a connection between the tower sections (102-1, 102-2) and the at least one tower hub ( 104) is provided by bolts.

18. The tower (100) as claimed in one of claims 1-17, wherein the tower includes at least two tower hubs (104) separated by at least one tower section (102-1, 102-2, ...).

19. The tower (100) as claimed in one of claims 8-18, further comprising horizontal supporting tubes (804) providing a rigid support to the supporting members (108), the horizontal supporting tubes (804) extending horizontally from the tower and connected to the supporting members (108).

20. The tower (100) as claimed in claim 19, wherein the supporting members (108) are bent at a point where the horizontal supporting tubes (804) are connected with the supporting members.

21. A wind turbine installation including a nacelle and a rotor hub carrying a blade assembly coupled to a power generator mounted on the nacelle, wherein the nacelle is mounted on top of the tower (100) as claimed in one of claims 1-20.

22. A tower (100) for a wind turbine, the tower comprising:

at least two tower sections (102-1, 102-2); and

at least one tower hub (104) connecting the at least two tower sections (102-1, 102-2), the at least one tower hub (104) having a plurality of integral protrusions (606) provided about the tower hub (104) for connecting supporting members (108).