Patent Description:
Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, a generator, a gearbox, a nacelle, and one or more rotor blades. The rotor blades capture kinetic energy from wind using known airfoil principles and transmit the kinetic energy through rotational energy to turn a main shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.

The wind turbine tower typically includes a base tower section secured to a foundation and one or more upper tower sections secured atop the base tower section to form a tower of a certain height. The foundation may be a concrete slab foundation, an anchor cage foundation, or any other suitable foundation capable of supporting loads produced by the wind and/or gravitational forces. Further, each tower section generally includes a cylindrical wall defining an outer diameter and an inner diameter separated by a radial thickness that is uniform along the entire length of the sections. <CIT> relates to a concrete equipment tower with tensioning tendon guide slot. The tower may include a foundation, a bottom tower portion, a middle tower portion, a top tower portion and a steel tip adapter. The steel tip adapter may be used to support a nacelle of a wind turbine. Each tower portion may be formed with a plurality of tower segments, respectively, that may be formed of precast concrete. Transition segments may be positioned between appropriate tower portions to accommodate a progressive change in the diameter of tower segments from the bottom to the top of equipment tower. <CIT> relates to a platform assembly for a wind turbine tower. <CIT> relates to a tower with a platform.

The overall tower height of wind turbines may be dependent on a number of factors. For example, the tower height may vary based on environmental conditions at the wind turbine site and/or costs of materials. In addition, increasing the tower height allows for longer rotor blades which in turn produce more power. Thus, conventional tower heights can be increased or decreased by modifying the number of tower sections stacked together. In addition, when the tower height is modified, additional manufacturing steps are required to ensure that the tower can withstand site and component loading. More specifically, if a certain site requires a tower with an increased height to harvest higher wind speeds, the cylindrical walls of the corresponding wall sections are designed with a thicker radial thickness to account for higher loads. Alternatively, if a certain site requires a tower having a lower height to harvest lower wind speeds, the cylindrical walls of the corresponding wall sections are designed with a thinner radial thickness to save material costs. In addition, whether a tower is designed with a thicker or thinner radial thickness, it is difficult for an operator to tell the difference when assembling the tower. As such, tower heights have to be specifically designed for differing site and loading conditions. In addition, additional efforts are spent identifying and locating which tower sections should be used for which tower, e.g. at a wind farm.

Accordingly, an improved tower assembly for a wind turbine that addresses the aforementioned issues would be desired in the art. Thus, the present disclosure is directed to a tower assembly for a wind turbine having an adjustable hub height that does not require a redesign for every site.

In one aspect, the present disclosure is directed to a tower assembly according to independent claim <NUM>. A tower assembly for a wind turbine having an adjustable height includes at least one base tower section having a cylindrical base wall defining an overall length extending from a first end to a second end. The cylindrical base wall further defines an outer diameter that is uniform along the entire length from the first end to the second end. The tower assembly also includes an adjustable upper tower section arranged atop the base tower section. The upper tower section includes a first tower portion integral with a second tower portion. The first tower portion includes a first tower wall portion defining a first length extending from a first end to a second end. Further, the first tower wall portion includes a tapering cross-section from the first end to the second end of the first length thereof. The second tower portion includes a second tower wall portion defining a second length extending from a first end to a second end. Further, the second tower wall portion defines a uniform cylindrical cross-section from the first end to the second end of the second length thereof.

In one embodiment, the tapering cross-section of the first tower wall portion may taper towards the second tower portion.

In another embodiment, the tower assembly may further include a transitional tower section arranged between the base tower section and the upper tower section. In such embodiments, the transitional tower section includes an outer wall defining a length extending from a first end to a second end. Further, in certain embodiments, the outer wall of the transitional tower section may define an outer diameter that tapers along the length thereof.

In further embodiments, the second tower portion of the upper tower section may include an upper tower can mountable to a nacelle of the wind turbine. In addition, the second tower portion of the upper tower section may be constructed of one or more removable tower cans arranged below the upper tower can.

In additional embodiments, the tower assembly may further include at least one platform in any one of the base tower section, the transitional tower section, and/or the upper tower section. For example, in one embodiment, the tower assembly may include at least one platform in the second tower portion of the upper tower section.

In another aspect, the present disclosure is directed to an adjustable upper tower section for a tower of a wind turbine. The upper tower section includes a first tower portion having a first tower wall portion defining a first length extending from a first end to a second end. The first tower wall portion includes a tapering cross-section from the first end to the second end of the first length thereof. The upper tower section also includes a second tower portion integral with the first tower portion. The second tower portion includes a second tower wall portion defining a second length extending from a first end to a second end. The second tower wall portion defines a uniform cylindrical cross-section from the first end to the second end of the second length thereof. It should also be understood that the upper tower section may further include any of the additional features as described herein.

In yet another aspect, the present disclosure is directed to a method according to the independent method claim. A method for adjusting a tower height of a wind turbine includes securing a base tower section to a foundation. The base tower section has a cylindrical base wall defining an outer diameter that is uniform along its entire length. The method also includes mounting an adjustable upper tower section atop the base tower section. The upper tower section has a first tower portion integral with an adjustable second tower portion. The first tower portion has a first tower wall portion defining a first length extending from a first end to a second end. Further, the first tower wall portion has a tapering cross-section from the first end to the second end of the first length thereof. The second tower portion has a second tower wall portion defining a second length extending from a first end to a second end. Moreover, the second tower wall portion defines a uniform cylindrical cross-section from the first end to the second end of the second length thereof. Thus, the method further includes evaluating at least one of site conditions or loading conditions of the wind turbine and adjusting a height of the second tower portion based on the evaluation.

In one embodiment, the step of adjusting the height of the second tower portion based on the evaluation may include adding or removing at least one tower can of the second tower portion. More specifically, in certain embodiments, the step of adding or removing at least one tower can to the second tower portion may include adding or removing at least one tower can below an upper tower can of the second tower portion.

In another embodiment, the method may include mounting a transitional tower section between the base tower section and the upper tower section. In such embodiments, the transitional tower section may include an outer wall defining a length extending from a first end to a second end. More specifically, as mentioned, the outer wall of the transitional tower section may define an outer diameter that tapers along the length thereof.

In additional embodiments, the method may also include installing at least one platform in the second tower portion after adding or removing at least one tower can thereto. It should be understood that the method may further include any of the additional steps, features and/or embodiments as described herein.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope of the invention as claimed by the appended claims.

Generally, the present disclosure is directed to a tower assembly for a wind turbine having an adjustable height. As such, in some instances, the hub height can be adjusted to <NUM>% tower capacity so as to maximize energy production. More specifically, the tower assembly includes an adjustable upper tower section having a first tower portion integral with a second tower portion. The first tower portion includes a first tower wall portion defining a first length extending from a first end to a second end. Further, the first tower wall portion includes a tapering cross-section from the first end to the second end of the first length thereof. The second tower portion includes a second tower wall portion defining a second length extending from a first end to a second end. Further, the second tower wall portion defines a uniform cylindrical cross-section from the first end to the second end of the second length thereof. In addition, the second tower portion is constructed of a plurality of removable tower cans that can be added or removed to adjust an overall height of the tower assembly.

In other words, the adjustable upper tower section has a partially cylindrical cross-section providing many advantages not present in the prior art. For example, the tower assembly of the present disclosure is configured to optimize the tower height (and therefore hub height) based on site and/or loading conditions. Further, by providing a tower assembly with a height can that be easily increased, higher energy levels can be achieved at multiple wind turbine sites. Moreover, the tower assembly of the present disclosure provides a flexible assembly that can be easily sourced multiple wind turbine sites. In addition, the tower assembly of the present disclosure allows for positioning of the same platform for multiple configurations or heights of the tower assembly.

Thus, if a certain wind turbine site has lower wind speeds, the adjustable upper tower section can extend higher in order to harvest the higher winds and utilize <NUM>% original tower capacity. Alternatively, if a certain site has lower wind speeds, the adjustable upper tower section can be shortened to accommodate the lower winds and not exceed <NUM>% original tower capacity. Further, the tower sections described herein that are below the upper tower section are identical and the upper section differs only by the length of the cylindrical segment.

Referring now to the drawings, <FIG> illustrates a perspective view of one embodiment of a wind turbine <NUM> according to the present disclosure. As shown, the wind turbine <NUM> generally includes a tower <NUM>, a nacelle <NUM> mounted on the tower <NUM>, and a rotor <NUM> coupled to the nacelle <NUM>. The tower <NUM> extends generally perpendicular to a foundation or support surface <NUM> may be secured to the foundation <NUM> using any suitable means, such as anchor bolts (not shown). Further, the tower <NUM> (also generally referred to herein as a tower assembly <NUM>) includes a plurality of tower sections, including for example, a base tower section <NUM> and at least one upper tower section <NUM>. The rotor <NUM> includes a rotatable hub <NUM> and at least one rotor blade <NUM> coupled to and extending outwardly from the hub <NUM>. For example, in the illustrated embodiment, the rotor <NUM> includes three rotor blades <NUM>. However, in an alternative embodiment, the rotor <NUM> may include more or less than three rotor blades <NUM>. Each rotor blade <NUM> may be spaced about the hub <NUM> to facilitate rotating the rotor <NUM> to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub <NUM> may be rotatably coupled to an electric generator (not shown) positioned within the nacelle <NUM> to permit electrical energy to be produced.

Referring now to <FIG>, various embodiments of a tower assembly <NUM> for a wind turbine <NUM> having an adjustable height according to the present disclosure is illustrated. More specifically, as shown, <FIG> illustrates three variations of the tower assembly <NUM>, namely, a baseline configuration <NUM>, a reduced height configuration <NUM>, and an increased height configuration <NUM>. Further, as shown, the tower assembly <NUM> includes at least one base tower section <NUM>. As shown in <FIG>, the base tower section <NUM> has a substantially cylindrical base wall <NUM> defining an overall length <NUM> extending from a first end <NUM> to a second end <NUM>. The cylindrical base wall <NUM> further defines an outer diameter <NUM> that is uniform along the entire length <NUM> from the first end <NUM> to the second end <NUM>.

Referring back to <FIG> and <FIG>, the tower assembly <NUM> also includes at least one upper tower section <NUM> arranged atop the base tower section <NUM>. More specifically, as shown in <FIG>, the upper tower section(s) <NUM> includes at least an adjustable height upper tower section <NUM>. For example, as shown in <FIG>, the adjustable upper tower section <NUM> includes a first tower portion <NUM> integral with a second tower portion <NUM>. In addition, as shown in <FIG>, the first tower portion <NUM> includes a first tower wall portion <NUM> defining a first length <NUM> extending from a first end <NUM> to a second end <NUM>. Moreover, as shown in <FIG>, the first tower wall portion <NUM> includes a tapering cross-section from the first end <NUM> to the second end <NUM> of the first length <NUM> thereof. More specifically, as shown, the tapering cross-section of the first tower wall portion <NUM> may taper towards the second tower portion <NUM>. In alternative embodiments, the tapering cross-section of the first tower wall portion <NUM> may taper away from the second tower portion <NUM>.

Further, as shown in <FIG>, the second tower portion <NUM> includes a second tower wall portion <NUM> defining a second length <NUM> extending from a first end <NUM> to a second end <NUM>. In contrast to the first tower portion <NUM>, however, the second tower wall portion <NUM> defines a uniform cylindrical cross-section from the first end <NUM> to the second end <NUM> of the second length <NUM> thereof. As such, the adjustable upper tower section <NUM> is a partially-cylindrical, partially-tapered tower section.

Referring back to <FIG>, the second tower portion <NUM> of the adjustable upper tower section <NUM> may be constructed of one or more tower cans <NUM> (as indicated by the dotted lines), which allow the overall tower height to be adjusted. For example, as shown, the baseline configuration <NUM> of the tower assembly may include a predetermined number of tower cans <NUM> suitable for a tower height at a wind turbine site with normal wind conditions. If the tower assembly <NUM> is needed at a site having lower wind speeds, however, as shown in the reduced height configuration <NUM>, one or more of the tower cans <NUM> may be removed. Alternatively, as shown in the increased height configuration <NUM>, if the tower assembly <NUM> is needed at a site having higher wind speeds, one or more of the tower cans <NUM> may be added.

More specifically, as shown in the illustrated embodiment, the second tower portion <NUM> of the adjustable upper tower section <NUM> may further include an upper tower can <NUM> mountable to the nacelle <NUM> of the wind turbine <NUM>. For example, the upper tower can <NUM> may be specifically designed (e.g. with flanges, bolt holes, etc.) for mounting the tower assembly <NUM> to the nacelle <NUM> and/or a yaw bearing configured between the nacelle <NUM> and the top of the tower <NUM>. Thus, in such embodiments, one or more of the lower tower cans <NUM> are removed or added, leaving the upper tower can <NUM> in place.

In addition, in certain embodiments, as shown in <FIG>, the upper tower section(s) <NUM> may also include one or more transitional tower sections <NUM> arranged between the base tower section <NUM> and the adjustable upper tower section <NUM>. In such embodiments, as shown in <FIG>, the transitional tower section <NUM> includes an outer wall <NUM> defining a length <NUM> extending from a first end <NUM> to a second end <NUM>. Further, as shown, the outer wall <NUM> of the transitional tower section <NUM> may define an outer diameter <NUM> that tapers along the length <NUM> thereof.

Referring now to <FIG>, the tower assembly <NUM> may further include at least one platform <NUM> in any one of the base tower section <NUM>, the transitional tower section <NUM>, and/or the adjustable upper tower section <NUM>. For example, as shown, the tower assembly <NUM> includes a platform <NUM> in each of the illustrated sections. More specifically, as shown, the tower assembly <NUM> includes a platform <NUM> in the second tower portion <NUM> of the adjustable upper tower section <NUM>. Thus, due to the cylindrical shape of the second tower wall portion <NUM> of the second tower portion <NUM>, the same platform <NUM> can be used for all configurations <NUM>, <NUM>, <NUM> of the tower assembly <NUM>.

Accordingly, every time the hub height is adjusted as described herein, the upper platform elevation changes since the platform is typically always at the same distance from the top of the upper tower section <NUM> to allow for service and maintenance of the top section joint. Since the upper tower section <NUM> is also tapered to connect the maximum ground diameter to the required machine support diameter, the diameter of that platform changes as well and requires a redesign. Providing a cylindrical region at the top of the upper tower section <NUM> allows for using the same platform with the same diameter for each adjusted elevation.

Referring now to <FIG>, a flow diagram of one embodiment of a method <NUM> for adjusting a tower height of a wind turbine <NUM> using the tower assembly <NUM> of the present disclosure is illustrated. As shown at <NUM>, the method <NUM> includes securing the base tower section <NUM> of the tower assembly <NUM> to a foundation <NUM>. As shown at <NUM>, the method <NUM> includes mounting the adjustable upper tower section <NUM> atop the base tower section <NUM>. As shown at <NUM>, the method <NUM> evaluating site conditions and/or loading conditions of the wind turbine <NUM>. As shown at <NUM>, the method <NUM> adjusting the height of the second tower portion <NUM> of the tower assembly <NUM> based on the evaluation. More specifically, in one embodiment, the height of the second tower portion <NUM> may be adjusted by adding or removing at least one tower can <NUM> of the second tower portion. In particular embodiments, as mentioned, the method <NUM> may include adding or removing at least one tower can <NUM> below the upper tower can <NUM> of the second tower portion <NUM>.

In another embodiment, the method <NUM> may include mounting the transitional tower section <NUM> between the base tower section <NUM> and the adjustable upper tower section <NUM>. In additional embodiments, the method <NUM> may also include installing at least one platform <NUM> in the second tower portion <NUM> after adding or removing at least one tower <NUM> can thereto.

Claim 1:
A tower assembly for a wind turbine (<NUM>) having an adjustable height, the tower assembly comprising:
at least one base tower section (<NUM>) comprising a cylindrical base wall (<NUM>) defining an overall length (<NUM>) extending from a first end (<NUM>) to a second end (<NUM>), the cylindrical base wall (<NUM>) further defining an outer diameter (<NUM>) that is uniform along the entire length (<NUM>) from the first end (<NUM>) to the second end (<NUM>); and,
an adjustable upper tower section (<NUM>) arranged atop the base tower section (<NUM>), the upper tower section (<NUM>) comprising a first tower portion (<NUM>) integral with a second tower portion (<NUM>), the first tower portion (<NUM>) comprising a first tower wall portion (<NUM>) defining a first length (<NUM>) extending from a first end (<NUM>) to a second end (<NUM>), the first tower wall portion (<NUM>) comprising a tapering cross-section from the first end (<NUM>) to the second end (<NUM>) of the first length (<NUM>) thereof, the second tower portion (<NUM>) comprising a second tower wall portion (<NUM>) defining a second length (<NUM>) extending from a first end (<NUM>) to a second end (<NUM>), the second tower wall portion (<NUM>) defining a uniform cylindrical cross-section from the first end (<NUM>) to the second end (<NUM>) of the second length (<NUM>) thereof;
wherein the second tower portion (<NUM>) of the upper tower section (<NUM>) further comprises an upper tower can (<NUM>) mountable to a nacelle (<NUM>) of the wind turbine (<NUM>), the upper tower can (<NUM>) providing a cylindrical region at the top of the upper tower section (<NUM>); and wherein the second tower portion (<NUM>) of the upper tower section (<NUM>) is constructed of one or more removable tower cans (<NUM>) arranged below the upper tower can (<NUM>).