DE102011102473A1 - Tower structure for wind energy plants, comprises multiple nested tubes inserted into one another in polygon shape and tubes are interconnected by web, whose cavities are filled with mass - Google Patents

Abstract

The tower structure comprises multiple nested tubes inserted into one another in a polygon shape. The tubes are interconnected by a web, whose cavities are filled with mass, where a frictional force exist between the tube elements and partly filled mass. The polygonal nested tubes are connected by radial webs and form a concentric cavity. The portions between the tubes or chambers are filled with mass, particularly reinforced concrete, which provides the bending strength in the horizontal direction and the load in a vertical direction.

Description

Short description:

The present invention proposes a construction method for improving towers of wind turbines. It is multi-tubular, multi-shell and / or chambered, massive and prestressed construction of the tower and their combination. The constructional measures described allow slimmer towers, more rigid towers, less susceptible towers and towers greater heights than towers of wind turbines conventional designs.

State of the art:

Wind turbines of different size, power and different types are spreading more and more in all countries of the world to generate electrical energy from the kinetic energy of the wind. The trend toward "regenerative" energies from wind, solar, biomass and water has increased significantly in recent years and manufacturers have stimulated the construction of ever larger wind turbines, particularly in the field of highly successful wind energy.

This increase in size, especially in the most widespread type of wind turbines, that of the three-bladed horizontal-axis rotor on a tower, increasingly causes problems that are to a considerable extent due to increasing component sizes.

It is well known that the higher the wind turbines are built, the higher the yield of wind turbines, because at higher altitudes the wind blows faster and more laminarly on average. Accordingly, in the recent past, various tower types have been tried to successively raise the hub height and position the rotor in higher yielding higher air layers (hybrid tower or lattice tower). The focus is currently on the development of ever larger rotors, more powerful generators, and other components associated with performance growth.

The towers carrying the wind machines, on the other hand, receive relatively little attention, and the development of this component is relatively slow. In addition to questions of erection and the approval of towers over 140 m height, little consideration is given to how such towers can be designed efficiently, lean, stable and permanently reliable. On the contrary, at the present time it is primarily the enlargement of already existing tower or lattice mast geometries or the mixture of two tower construction principles which is the case with hybrid towers. The potential of other construction methods, such as those derived from high-rise construction and the structural design of bridge construction, has so far not been used.

Task:

It is the object of the invention to combine proven construction methods from the field of high-rise statics, from the floor slab construction and bridge construction with the requirements of wind turbine construction and to suggest in this way construction methods for wind turbines, which are both efficient and more economical at werter growing size of wind turbines , as existing construction methods.

It is the object of the invention to improve by multi-tubular and / or chambered construction methods as well as by multi-shell construction methods of the wind turbine tower and their combination, the stability and reduce the susceptibility to vibration.

It is the object of the invention to improve the efficiency of towers of wind turbines by multi-pipe and / or chambered constructions, as well as by multi-shell construction, as well as by bias and the combination of all proposed designs.

It is the object of the invention to improve the buildability of the towers of wind turbines and to dimension the individual delivered to the place of construction tower segments so that they can be easily transported to the place of construction and easily mounted on the ground.

It is the object of the invention to improve the efficiency of the tower construction by saving material in relation to the buoyancy and the height of the tower of the wind turbine.

It is the object of the invention to produce the load-bearing behavior in the respectively optimum manner through the materials used.

It is the object of the invention to non-positively connect the constructive materials used and thus to achieve a composite effect.

It is the object of the invention, the bearing behavior by the principle of a lost formwork first by lightweight formwork elements prepare and then produce by casting, for example, with mortar or concrete.

The solution of the problem:

According to the invention, the efficiency of the tower construction is improved in that the tower is not only a single assembled from segments steel or concrete pipe of a certain thickness and a certain diameter or even formed as a lattice mast, but that it consists of at least two concentric nested tubes , Which are interconnected by webs or through a tube which is divided into chambers and thus redistributes the bending moment by lateral load in the tower of the wind turbine so that greater bending stiffness is achieved despite lower overall tower thicknesses.

According to the invention, the efficiency of the tower construction is improved in that the tower consists not only of a single assembled from segments steel pipe of a certain thickness and a certain diameter, or even as a lattice mast is formed, but that it consists of two or more concentrically arranged tubes, the are interconnected by radial webs which form an annular segmented cavity.

According to the invention, the efficiency of the tower construction is thereby improved and the susceptibility to vibration is reduced by filling the cavity between the tubes or chambers with mass, preferably with reinforced concrete, which decisively improves the bending strength in the horizontal direction and the load capacity in the vertical direction.

According to the invention, the efficiency of the tower construction and the bearing behavior is improved by the fact that the lateral surfaces and the filled mass are non-positively connected to each other (composite construction).

According to the invention, the buckling behavior of the lateral surfaces of the construction is improved by filling the cavity between the tubes or chambers with mass, preferably with reinforced concrete, which further improves the flexural strength in the horizontal direction and the load-bearing capacity in the vertical direction.

According to the invention, the bending strength is improved by introduced into the tower or guided along the tower bracing elements, primarily by certified tensioning cable devices from the prestressed concrete, as z. B. are known from prestressed concrete bridges ago. According to this composite of tendons and tower segments of the wind turbine achieves a higher rigidity and thus a higher load capacity, greater slenderness and higher efficiency than towers of wind turbines without distortion.

Brief Description:

The 1 to 4 illustrate in an illustrative way the problem of existing wind turbines and their towers in a simplified manner.

The 5 to 9 describe the solutions of the invention of the previously illustrated problems.

1 describes by way of example the prior art in an overview: The figure shows a wind turbine of conventional design with its components rotor blades ( 1 ), Rotor blade suspension ( 2 ), Gondola ( 6 ) with gearbox located therein ( 4 ) and a generator ( 5 ) for converting the rotational movement about the axis ( 3 ) into electrical energy. The gondola rotates ( 7 ) on the tower shaft ( 8th ), which may have a conical or otherwise widened tower base ( 9 ) and on the tower foundation ( 10 ), which forces in the ground ( 11 ).

2 shows by way of example various tower constructions according to the prior art and the bending moments occurring in the tower shaft as a result of lateral stress by the oncoming wind. ( 1a / b), ( 6 ) and ( 7 ) show by way of example the simplest tower variant according to the prior art. To ( 1 ), the influx of wind (F _W ) can be understood as a concentrated force (F _ΣW ), which holds the nacelle in position by a counterforce (F _T ). This counterforce generates a bending moment in the tower shaft, which reaches its maximum at the end of the tower shaft at the level of the floor (h ₁ ). The bending moment at the level of the clamping points (P ₁ ) and (P ₂ ) is calculated from the product of force and lever arm = (F _ΣW ) × (h ₁ ). The slenderness of the tower (d ₁ ) determines how large the occurring normal forces (F _Z ) and (F _D ) become at the clamping points. (P ₁ ) in the windward is claimed to train, (P ₂ ) in the lee on pressure. The leaner the tower is, the larger the normal forces in the tower tube are, because (F _{D / Z} ) = (M ₁ ) 2 / (d ₁ ). In addition, the system tends (F _Wr1, F _Wr2 and _Wr3 F) due to non-uniform wind and the resulting uneven lift forces (F _{Tr1, Tr2} F and F _Tr3) must be compensated by opposing forces of the tower, to oscillate. (2) to (5) show, by way of example, various current tower constructions which attempt to reduce the occurring bending moment near the ground by broadening tower bases by widening the geometry of the tower construction to (d ₂ ) and maximum occurring normal forces (F _Z ) and (F _D ) decrease according to the formula (F _{D / Z} ) = (M ₂ ) 2 / (d ₂ ). Neither the vibration susceptibility due to the lightweight construction, nor the desire for greater heights provide these standard solutions an adequate answer.

3 describes in (A) and (B) for example the problem of the maximum deflection (I _x ) of the tower in the nacelle by the applied horizontal force (F _ΣW ), the rotational forces (F _ΣWr ) and the counter forces of the tower (F _T and F _ΣTr ). The deflection in the area of the nacelle (I _x ) is greater, the stronger the wind against the wind turbine presses (B). Due to the great slenderness, the system tends to vibrate, whereby various vibration states may occur, as exemplified in (C) to (F). Not only do these vibrations adversely affect the tower, they also transfer to the rotor blades and the moving components within the nacelle, which reduces their operational reliability and shortens their life or causes emergency shutdowns through resonances, compromising economy.

4 shows the tower shaft of a wind turbine according to the prior art in longitudinal and cross-section. All occurring forces must be passed through the thin wall cross-section, which limits both the maximum free buckling length, ie the maximum height of the tower for given tower tube diameter (d ₁ ) and given wall thickness (t ₁ ). It does not matter if the tower is made of steel, reinforced concrete, shell concrete or prestressed reinforced concrete. This single-shell construction principle reaches its economic limit from a certain free bend length.

5 to 9 show by way of example a plurality of variants according to the invention, which can accommodate higher normal forces with the same outer diameter (d ₁ ), since they have combined construction principles in the component cross-sections. In addition, web formations or other geometric composite solutions improve the buckling behavior of the pipe at long lengths and thus at high slenderness, or with a large free buckling length.

The solutions according to the invention in detail:

5 describes, by way of example, the construction according to the invention of the tower of a wind power plant, in which two tubes (2) are nested concentrically in one another (FIG. 1 ) and ( 2 ) with the same outer diameter (d ₁ ) divide all occurring loads among themselves. Through the bridge training ( 3 ), the load distribution improves again, since the bending moment acting differently on both tubes can be passed through the web. In addition, the buckling behavior improves by the cooperating width (b ₁ ) of the combined tubes.

6 describes by way of example the structure according to the invention of the tower of a wind turbine, as in 5 , In addition, the cavities ( 4 ) filled with a stiffening mass, such as concrete, fiber concrete, here in particular steel fiber concrete or reinforced concrete. The buckling behavior of the steel pipe walls ( 1 and 2 ) improves compared to the filled cavities 5 again. The occurring normal forces are now distributed depending on the material in addition to the filler and homogenize the force curve within the tower tube. For economic reasons, the filler will usually be concrete, fiber concrete or reinforced concrete, which, depending on the design, can only _absorb compressive forces (F _Dconc ) or additional tensile forces (F _Dconc ) due to additional reinforcement and non-positive connection with the pipes.

7 describes by way of example the construction according to the invention of the tower of a wind turbine as in 6 with all the properties described there. In addition, elements for prestressing are introduced into the tower construction ( 5 ), with which the entire tower of the wind turbine or parts thereof can be placed under pretension (F _V ), whereby in all remaining components ( 1 to 4 ) only pressure forces (F _D ) occur. The bending moment within the tower disappears completely in this construction from the tower shaft of the wind turbine.

8th describe by way of example the construction according to the invention of the tower of a wind energy plant with internal tensioning cables ( 1 ).

9 describes by way of example a construction according to the invention of the tower of a wind energy plant, in which elements ( 1 ), z. B. steel mandrels protrude for better bonding effect in the filling and at the same time the webs ( 2 ) may be formed weaker between the inner and outer lateral surface.

Advantageous effect:

• 1. The multi-shell leads to greater resilience at the same total diameter.
• 2. The web formation allows power transmission between the inner and outer sheath.
• 3. The web formation avoids buckling of both the outer and the inner proposed lateral surface.
• 4. Composite construction allows for variably applicable building materials that can be used and combined according to their particular merits.
• 5. The chambered construction allows multiple use of the outer and inner wall as a static element and gleichzetig as permanent formwork or as a permanent protection against external environmental influences.
• 6. The proposed designs rely on the use of proven composite construction from the basement ceiling construction and on bracing elements from prestressed concrete bridge construction and high-rise building with the same thermal expansion coefficients whose behavior has been tested and observed over decades and their use is absolutely safe and harmless.
• 7. The proposed designs allow for greater slenderness coupled with lower susceptibility to vibration due to the larger total mass of the tower.
• 8. The proposed designs allow for higher tower constructions as they break the inefficiency barrier of conventional designs, the proposed designs are more efficient in their entirety than conventional constructions.
• 9. Outer and inner lateral surface allow corrosion and weather protection for the introduced filling material.
• 10. The filling prevents the buckling of both the outer and the inner shell.
• 11. The bracing elements improve the power flow within the tower by reducing the tensile forces on the side from which the wind power comes, which has so far led to a bending stress and thus to a tensile stress just this side of the tower shaft.
• 12. The susceptibility to vibration decreases due to the larger mass.
• 13. The susceptibility to vibration is reduced due to the higher bending stiffness.
• 14. The proposed designs allow the proven design in segments with final assembly at the installation site.
• 15. The transport of extra-wide and over-high tower elements can be reduced or avoided by meaningful disassembly and on-site assembly.
• 16. The proposed designs allow easy release of the tension and a simple dismantling of the wind turbine for decommissioning.
• 17. The proposed designs allow for easy reconstruction of the tower at a different location, depending on the design.
• 18. The proposed construction methods allow a sorted recycling of separable building materials.
• 19. The proposed designs are also applicable to hybrid designs.

Claims (7)

Tower construction, characterized in that the tower consists of several nested tubes or polygons, which may be interconnected by webs, the cavity or cavities may be filled with mass and may have a non-positive connection between pipe elements and filled mass Tower construction according to claim 1, characterized in that the tubes or polygons can be connected to each other by radial webs and form a concentric cavity, so that due to the thereby improved statics lower overall tower thicknesses can be achieved with greater flexural rigidity. Tower construction according to one of the above claims, characterized in that the cavity of some or all areas between the tubes or chambers is filled with mass, preferably with reinforced concrete, which further improves the bending strength in the horizontal direction and the load capacity in the vertical direction. Tower construction according to one of the above claims, characterized in that the filled into the cavities concrete can be positively connected to the lateral surfaces (composite construction). Tower construction according to one of the above claims, characterized in that the bending strength is improved by introduced into the tower or guided along the tower bracing elements, primarily by certified tensioning cable devices from the prestressed concrete, as z. B. are known from prestressed concrete bridges ago. Tower construction according to one of the preceding claims, characterized in that this composite of tendons and tower segments of the wind turbine gives a higher rigidity and thus a higher load capacity, greater slenderness and higher efficiency, as the towers of wind turbines without distortion. Tower construction according to any one of the preceding claims, characterized in that all proposed design principles can be combined as desired to make the tower construction as efficient as possible for each application.

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