Fan foundation and construction method thereof

Abstract

The invention provides a fan foundation and a construction method thereof. The draught fan foundation comprises a draught fan tower drum, a center stand column and a mooring system, the center stand column is connected to the lower end of the draught fan tower drum, a plurality of lower connecting beams are horizontally arranged on the circumference of the center stand column, and the end, away from the center stand column, of each lower connecting beam is connected with an upward side stand column inclining away from the center stand column. The upper end of each side stand column is vertically connected with one mooring system; the lower connecting beam and the side stand columns are integrally formed and internally provided with a ballast tank which is communicated with the lower connecting beam, and the ballast tank is filled with water with the adjustable water volume. According to the invention, the force arm can be increased, so that the load on each group of mooring system can be reduced, the rigidity of the mooring system can be reasonably adjusted, the number of the mooring system and the anchoring foundation does not need to be increased even in a shallow sea area, and meanwhile, the interference between the mooring system and a floating body can be effectively avoided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of comprehensive utilization of marine energy, and particularly relates to a wind turbine foundation and a construction method thereof. BACKGROUND

[0002] With the continuous development of offshore wind power, the valuable field area near the coast has been basically developed, and offshore wind power will inevitably develop towards the deep sea. At present, the development cost of floating offshore wind power is too high, and the commercialization process is slow. Tension leg platforms have broad development prospects in future floating wind turbines due to their advantages of less steel consumption for floating body, low mooring cost, and small sea area. Since the water depth of a certain offshore area is not more than 100 m, it belongs to a shallow sea area. Shallow water will limit the length of the tension tendon on the existing wind turbine foundation, make the mooring system stiffness larger, and thus make the natural period of the floating wind turbine smaller, which is in the common wave frequency range, so as to easily cause resonance, resulting in a sharp increase in response, which is not conducive to the safety and economy of the floating wind turbine.

[0003] With the increase of single machine capacity of the wind turbine and the gradual deterioration of the sea conditions in the engineering sea area, the number of mooring chains will increase, thereby increasing the number of anchoring foundations, which will increase the exploration, production, transportation, piling and other costs required for the construction of anchoring foundations, and the cost is high.

[0004] Therefore, reasonably adjusting the stiffness of the mooring system while reducing the number of anchoring foundations is an important means to improve the economy of the shallow water tension leg platform.

[0005] A multi-strut stable floating wind turbine foundation disclosed in the existing patent publication CN118167561A has a central column, a central heaving tank at the lower end of the central column, a side column, and a side heaving tank at the lower end of the side column. When the tension leg is used, the tension leg is connected with the side heaving tank at the lower end of the side column. The structure has the following disadvantages: (1) the tension leg is connected to the lower end of the side column, and the length of the force arm is limited, thereby, in order to ensure the load capacity of the mooring system, the stiffness of the mooring system needs to be increased; (2) the central heaving tank and the side heaving tank are arranged, resulting in weak water capacity of the floating body, and the buoyancy is smaller than the tension power. SUMMARY

[0006] The present application aims to provide a wind turbine foundation and a construction method thereof, which is beneficial to increase the force arm and reduce the load on each group of mooring cables.

[0007] The technical scheme of the present application is: a fan foundation, comprising a fan tower, a central column and a mooring system, the central column is connected to the lower end of the fan tower, a plurality of lower connecting beams are horizontally arranged on the circumference of the central column, the end of each lower connecting beam away from the central column is connected to an edge column which is inclined upward and away from the central column, the upper end of each edge column is vertically connected to the mooring system; the lower connecting beam and the edge column are integrally formed and have a ballast tank inside which is in communication, and the ballast tank is filled with water whose amount can be adjusted.

[0008] The floating fan foundation mainly bears the bending moment caused by the fan impeller, and the final bending moment is borne by the tension leg system (mooring system) at the bottom. In the case of constant bending moment, the greater the distance between the mooring points (the length of the force arm), the smaller the load. In the above scheme, the horizontal lower connecting beams and the upwardly inclined edge columns are arranged on the central column, and the mooring points are arranged at the upper end of the edge columns, which effectively increases the force arm, thereby reducing the load on each group of mooring systems and reasonably adjusting the stiffness of the mooring system. Even in shallow water, it is not necessary to increase the number of mooring systems and anchoring foundations, and the interference between the mooring system and the floating body can also be effectively avoided.

[0009] At present, the water depth of the floating fan is about 50-70m, which is relatively shallow, and the mooring stiffness is relatively large. The water depth of the tension leg foundation is about 100m, which is more appropriate. The present scheme lifts the mooring points and makes full use of the silt layer, so that the tension leg can be applied to shallow water while ensuring its performance.

[0010] In addition, the lower connecting beam and the edge column have a ballast tank inside, water can be injected or extracted into or out of the ballast tank, and the water amount in the ballast tank is adjusted to realize the adjustment of the floating state and the draft, so that the mooring system with a buoyancy greater than the weight can be used for wind turbines above 18MW.

[0011] Preferably, the upper surface of each edge column is provided with a first platform, the central column is provided with a second platform, and a catwalk is connected between the first platform and the second platform, and the mooring system is connected to the first platform.

[0012] Preferably, one end of the catwalk is hinged to the first platform, and the other end of the catwalk is on the second platform and can slide along the radial direction of the central column. The position of the catwalk is adaptively adjusted and adapted to different sizes.

[0013] Preferably, the tension tendon comprises an end head, a first shackle, a joint, a cable, a second shackle and an anchor chain, the end head is installed through the edge column, the first shackle is connected to the lower end of the end head, the upper end of the cable is connected to the first shackle through the joint, the lower end of the cable is connected to the upper end of the anchor chain through a second shackle, and the lower end of the anchor chain is connected to the transition platform through another second shackle.

[0014] Preferably, the transition platform comprises a bearing structure, an eye plate arranged at the upper end of the bearing structure and connected with the tension tendon, a first circular tube arranged at the lower end of the bearing structure, and a spigot connected to the bottom of the first circular tube; the anchoring foundation comprises a second circular tube, the first circular tube is sleeved in the second circular tube in a shaft hole assembly manner, and the spigot is located inside the second circular tube.

[0015] Preferably, a plurality of limiting blocks are circumferentially arranged on the outer circumferential surface of the upper and lower ends of the first circular tube, a sealing ring is arranged between the limiting blocks of the lower end of the first circular tube and the spigot, and the sealing ring is attached to the inner wall of the second circular tube.

[0016] Preferably, a plurality of first ribs are arranged on the outer surface of the first circular tube, the plurality of first ribs are uniformly distributed along the axial direction of the first circular tube, a plurality of second ribs are arranged on the inner surface of the second circular tube, the plurality of second ribs are uniformly distributed along the axial direction of the second circular tube, and the plurality of first ribs and the plurality of second ribs are staggered after the first circular tube is sleeved with the second circular tube.

[0017] Preferably, a plurality of sea holes are uniformly arranged on the central column and the side column near the still water surface area.

[0018] The application also provides a method for constructing the wind turbine foundation, comprising the following steps: Step one, installing the lower connecting beam and the side column on the central column; Step two, installing the first platform on the upper surface of each side column, installing the second platform on the central column, and installing the trestle between the first platform and the second platform; Step three, installing the wind turbine tower and the wind turbine generator on the upper end of the central column; Step four, removing the silt on the surface layer of the anchoring point of the stratum; Step five, installing the anchoring foundation in the stratum in a pile installation manner; Step six, sleeving the transition platform in the anchoring foundation, grouting and sealing between the transition platform and the anchoring foundation, and connecting the lower end of the tension tendon to the transition platform; Step seven, connecting the upper end of the tension tendon with the side column.

[0019] Compared with the related art, the application has the following beneficial effects: (1) The application sets the horizontal lower connecting beam and the upwardly inclined side column on the central column, sets the mooring point on the side column, which is beneficial to increase the force arm, thereby reducing the load on each group of mooring systems, reasonably adjusting the rigidity of the mooring system, and effectively avoiding the interference between the mooring system and the floating body, without the need to increase the number of mooring systems and anchoring foundations even in the shallow sea area. Secondly, the invention sets a trestle between the inclined edge column and the center column, which is only used for passing, and can reduce the weight of the floating body; Thirdly, the invention sets a through sea hole on the edge column and the center column, which is set near the static water surface, and can effectively reduce the influence of the tidal level on the average tension of the tension tendon; Thirdly, the upper end of the tension tendon is connected to the first platform above the water surface, and the lower end of the tension tendon is connected to the transition platform in the stratum, which effectively increases the length of the tension tendon, reduces the overall stiffness of the mooring system, is beneficial to avoid the wave main frequency and reduce the motion response; in addition, the upper end of the tension tendon on the water surface is beneficial to the arrangement and operation of the tensioning device Fourthly, the tension tendon adopts two materials (cable and anchor chain), the cable is above the stratum, which is beneficial to reduce the influence of abrasion and silt on the performance of the tension tendon; the anchor chain is in the stratum, which improves the tension and mooring force; Fifthly, the tension tendon is connected with the anchoring foundation through the transition platform, the tension tendon only needs to be adapted with the transition platform, which can reduce the specification of the tension tendon, reduce the procurement difficulty, reduce the number of anchoring foundations and the cost, and effectively adjust the elevation of the anchoring point and control the installation error of the tension tendon; in addition, the reduction of the number of anchoring foundations can reduce the mutual influence between the anchoring foundations to a certain extent and improve the bearing capacity. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The front view schematic diagram of the fan foundation provided by the invention is shown in the figure; Figure 2 The side view schematic diagram of the fan foundation provided by the invention is shown in the figure; Figure 3 The top view schematic diagram of the fan foundation provided by the invention is shown in the figure; Figure 4 The three-dimensional structure schematic diagram of the fan foundation provided by the invention is shown in the figure; Figure 5 The installation schematic diagram of the tension tendon and the transition platform is shown in the figure; Figure 6 The structure schematic diagram of the transition platform is shown in the figure; Figure 7 The structure schematic diagram of the anchoring foundation is shown in the figure; Figure 8 The installation schematic diagram of the transition platform and the anchoring foundation is shown in the figure; Figure 9 The installation schematic diagram of the trestle, the first platform and the second platform is shown in the figure; Figure 10 The A-A sectional view schematic diagram along the Figure 9 is shown in the figure; Figure 11 The B-B sectional view schematic diagram along the Figure 9 is shown in the figure; Figure 12 is a flowchart of the construction of the wind turbine foundation (where a is step one, b is step two, c is step three, d is step four, e is step five, f is step six, and g is step seven).

[0021] In the attached diagram: 1. Wind turbine; 2. Wind turbine tower; 3. Lower connecting beam; 4. Side column; 5. Tension tendon; 51. End; 52. First shackle; 53. Joint; 54. Cable; 55. Second shackle; 56. Anchor chain; 6. Transition platform; 61. Eye plate; 62. Bearing structure; 63. Limiting block; 64. First circular pipe; 65. First reinforcing bar; 66. Sealing ring; 67. Spike; 7. Central column; 8. Mooring system; 9. Sea opening; 10. Trestle; 101. Railing; 102. Hinge point; 103. Walkway; 104. Free end; 105. Roller; 11. Anchorage foundation; 111. Second circular pipe; 112. Second reinforcing bar; 113. Support plate; 114. Cover plate; 12. Second platform; 13. First platform; 14. Grouting material. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described herein can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" used below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0023] like Figures 1-4 As shown, the wind turbine foundation provided in this embodiment includes a wind turbine generator 1, a wind turbine tower 2, a lower connecting beam 3, side columns 4, a central column 7, a mooring system 8, a trestle bridge 10, a second platform 12, and a first platform 13.

[0024] The wind turbine tower 2 and the wind turbine unit 1 are installed at the upper end of the central column 7. Three lower connecting beams 3 are arranged in a circular pattern on the central column 7, and each lower connecting beam 3 is connected to a side column 4 that is inclined upward and away from the central column 7 at the end away from the central column 7.

[0025] Each of the side pillars 4 has a first platform 13 on its upper surface, and the central pillar 7 has a second platform 12. A trestle 10 connects the first platform 13 and the second platform 12. Figure 9 , Figure 10 , Figure 11As shown, the trestle 10 is provided with a walkway 103, and railings 101 are provided on both sides of the walkway 103. One end of the trestle 10 along its length is hinged to the first platform 13 through a hinge point 102, and the other end of the trestle 10 along its length is provided with a roller 105 to form a free end 104. The roller 105 rolls on the second platform 12 along a direction parallel to the length of the trestle 10 (i.e., radially to the central column 7). The trestle 10 is only used for passage and is not used as a load-bearing component.

[0026] like Figure 1 , Figure 4 As shown, the mooring system 8 includes a tension tendon 5, a transition platform 6, and an anchoring foundation 11 connected in sequence. The upper end of the tension tendon 5 is connected to the side post 4. Each side post 4 corresponds to one mooring system 8. Three tension tendons 5 are connected to the transition platform 6 in each mooring system 8. The anchoring foundation 11, the transition platform 6, and some of the tension tendons 5 need to be installed in the soil of the stratum.

[0027] like Figure 5 As shown, the tension tendon 5 includes an end 51, a first shackle 52, a connector 53, a cable 54, a second shackle 55, and an anchor chain 56. The end 51 is mounted through the side post 4. The first shackle 52 is connected to the lower end of the end 51. The upper end of the cable 54 is connected to the first shackle 52 via the connector 53. The lower end of the cable 54 is connected to the upper end of the anchor chain 56 via a second shackle 55. The lower end of the anchor chain 56 is connected to the transition platform 6 via another second shackle 55. The first shackle 52 is an H-type shackle, and the second shackle 55 is a D-type shackle; their combined use increases the tension.

[0028] like Figure 6 As shown, the transition platform 6 includes a support structure 62, an eye plate 61 located at the upper end of the support structure 62 and connected to the second shackle 55 of the tension tendon 5, a first circular tube 64 located at the lower end of the support structure 62, and a tip 67 connected to the bottom of the first circular tube 64. Multiple limiting blocks 63 are circumferentially provided on the outer circular surfaces of both the upper and lower ends of the first circular tube 64, and a sealing ring 66 is provided between the limiting block 63 at the lower end of the first circular tube 64 and the tip 67. Multiple first ribs 65 are provided on the outer surface of the first circular tube 64.

[0029] like Figure 7 As shown, the anchoring foundation 11 includes a second circular tube 111, with a support plate 113 at the lower end of the inner part of the second circular tube 111, and a cover plate 114 on the upper surface of the support plate 113. The inner surface of the second circular tube 111 is provided with a plurality of second reinforcing bars 112.

[0030] like Figure 8As shown, the first circular tube 64 is fitted into the second circular tube 111 with a clearance via a shaft hole assembly, and the gap between the first circular tube 64 and the second circular tube 111 is filled with high-strength grout 14. The insertion tip 67 is located inside the second circular tube 111. The sealing ring 66 is fitted against the inner wall of the second circular tube 111. Multiple first ribs 65 and multiple second ribs 112 are staggered to better distribute the force evenly and ensure the stability of the connection.

[0031] like Figure 4 As shown, the central pillar 7 and the side pillars 4 are each provided with several sea-passing holes 9 in the area near the still water surface. The upper and lower bulkheads of the compartments where the sea-passing holes 9 are located are at extremely high and extremely low water levels, respectively. This design can effectively reduce the impact of tide level on the average tension of the tension tendon 5.

[0032] The lower connecting beam 3 and the side column 4 are integrally formed, and each has multiple interconnected ballast tanks connected by pipes. During use, water is pumped into or out of the ballast tanks to achieve different buoyancy levels for the float. This adjustable buoyancy structure enables the foundation to achieve a mooring system where buoyancy exceeds gravity. The overall design concept of the float and mooring system developed in this invention ensures application in shallow water while maintaining the performance and economy of the tension leg.

[0033] The wind turbine foundation of this invention has an overall displacement of approximately 10,000 tons, a draft of 25m for the floating body, a main structure height of approximately 40m, and a width of approximately 100m, and is suitable for wind turbines of 18MW and above.

[0034] As shown in Figure 12, the present invention also provides a method for constructing the above-mentioned wind turbine foundation, comprising the following steps: Step 1: Install the lower connecting beam 3 and the side column 4 onto the central column 7.

[0035] Step two: Install the first platform 13 on the upper surface of each side column 4, install the second platform 12 on the central column 7, and install a trestle 10 between the first platform 13 and the second platform 12. At the same time, install the end cap 51 on the first platform 13.

[0036] Step 3: Install the wind turbine tower 2 and wind turbine unit 1 on the upper end of the central column 7. At the same time, conduct a ballast water condition test to ensure that it is capable of integrated towing.

[0037] Step four: For the anchoring point location, remove the silt from the surface of the anchoring point in the stratum.

[0038] Step 5: Install the anchor foundation 11 into the ground using a piling method. Before piling, remove the cover plate 114, and after piling is completed, place the cover plate 114 on the support plate 113. Existing grouting construction methods do not have cover plates, resulting in poor sealing. This invention adds a cover plate, which can effectively control the loss of grout material 14 caused by the failure of the sealing ring 66.

[0039] Step six: Fit the transition platform 6 into the anchor foundation 11, and seal the gap between the transition platform 6 and the anchor foundation 11 with grout. Connect the lower end of the tension tendon 5 to the transition platform 6. The transition platform 6 designed in this invention reduces the number of anchor piles required.

[0040] Step seven: Connect the first shackle 52 at the upper end of the tension leg 5 to the end 51 already installed on the first platform 13. Then, place an anchor winch on the float (first platform 13) to tension the tension leg 5 until the float sinks to the designed depth. Construction is complete. Existing tension leg tensioning construction requires a dedicated platform above the water surface. This invention utilizes the existing platform of the float for construction, saving resources and simplifying the construction process.

[0041] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A wind turbine foundation, comprising a wind turbine tower (2), a central column (7), and a mooring system (8), characterized in that, The central column (7) is connected to the lower end of the wind turbine tower (2). Multiple lower connecting beams (3) are horizontally arranged on the circumference of the central column (7). Each lower connecting beam (3) is connected to a side column (4) that is inclined upward and away from the central column (7) at one end. The upper end of each side column (4) is vertically connected to a mooring system (8). The lower connecting beam (3) and the side column (4) have ballast tanks that are connected to each other. The ballast tanks are filled with water of adjustable volume.

2. The wind turbine foundation according to claim 1, characterized in that, Each of the side pillars (4) has a first platform (13) on its upper surface, and a second platform (12) is provided on the central pillar (7). A trestle (10) connects the first platform (13) and the second platform (12). The mooring system (8) is connected to the first platform (13).

3. The wind turbine foundation according to claim 2, characterized in that, One end of the trestle (10) is hinged to the first platform (13), and the other end of the trestle (10) is on the second platform (12) and can slide radially along the central column (7).

4. The wind turbine foundation according to claim 1, characterized in that, The mooring system (8) includes a tension tendon (5), a transition platform (6) and an anchoring foundation (11) connected in sequence, with the upper end of the tension tendon (5) connected to the side post (4).

5. The wind turbine foundation according to claim 4, characterized in that, The tension tendon (5) includes an end (51), a first shackle (52), a connector (53), a cable (54), a second shackle (55), and an anchor chain (56). The end (51) is installed through the side post (4). The first shackle (52) is connected to the lower end of the end (51). The upper end of the cable (54) is connected to the first shackle (52) through the connector (53). The lower end of the cable (54) is connected to the upper end of the anchor chain (56) through a second shackle (55). The lower end of the anchor chain (56) is connected to the transition platform (6) through another second shackle (55).

6. The wind turbine foundation according to claim 4, characterized in that, The transition platform (6) includes a bearing structure (62), an eye plate (61) located at the upper end of the bearing structure (62) and connected to the tension tendon (5), a first round tube (64) located at the lower end of the bearing structure (62), and a tip (67) connected to the bottom of the first round tube (64); the anchoring base (11) includes a second round tube (111), the first round tube (64) is fitted into the second round tube (111) by means of shaft hole assembly, and the tip (67) is located inside the second round tube (111).

7. The wind turbine foundation according to claim 6, characterized in that, Multiple limiting blocks (63) are provided on the outer circular surfaces of the upper and lower ends of the first circular tube (64). A sealing ring (66) is provided between the limiting block (63) at the lower end of the first circular tube (64) and the tip (67). The sealing ring (66) is in contact with the inner wall of the second circular tube (111).

8. The wind turbine foundation according to claim 6, characterized in that, The outer surface of the first round tube (64) is provided with a plurality of first ribs (65), which are evenly distributed along the axial direction of the first round tube (64). The inner surface of the second round tube (111) is provided with a plurality of second ribs (112), which are evenly distributed along the axial direction of the second round tube (111). After the first round tube (64) and the second round tube (111) are fitted together, the plurality of first ribs (65) and the plurality of second ribs (112) are staggered.

9. The wind turbine foundation according to claim 1, characterized in that, The central column (7) and the side columns (4) are each provided with several sea-access holes (9) in the area near the still water surface.

10. A method for constructing a wind turbine foundation as described in any one of claims 1-9, characterized in that, Includes the following steps: Step 1: Install the lower connecting beam (3) and the side column (4) onto the central column (7); Step 2: Install the first platform (13) on the upper surface of each side column (4), install the second platform (12) on the central column (7), and install a trestle (10) between the first platform (13) and the second platform (12). Step 3: Install the wind turbine tower (2) and wind turbine unit (1) on the upper end of the central column (7); Step 4: Remove the silt from the surface of the anchoring points in the strata; Step 5: Install the anchor foundation (11) into the stratum by piling. Step 6: Fit the transition platform (6) into the anchor foundation (11) and seal the transition platform (6) and the anchor foundation (11) with grout; connect the lower end of the tension tendon (5) to the transition platform (6); Step 7: Connect the upper end of the tension tendon (5) to the side post (4).

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