Wind turbine with blades connected to tensioning members of varying diameter

Abstract

A wind turbine (1) includes a tower (2), a nacelle (3), and at least three wind turbine blades (5). The wind turbine (1) also includes blade connection tensioning members (8) extending between a connection point (9) at one wind turbine blade (5) and a connection point (9) at an adjacent wind turbine blade (5). Each blade connection tensioning member (8) includes a plurality of first segments (12) having a first cross-sectional diameter and a plurality of second segments (13) having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter. The first segments (12) and second segments (13) are arranged alternately along the length of the blade connection tensioning member (8). This reduces noise generated during operation of the wind turbine (1).

Description

Technical Field

[0001] The present invention relates to a wind turbine comprising at least three wind turbine blades, wherein blade connection tensioning members extend between connection points at adjacent wind turbine blades. Background Technology

[0002] During operation and shutdown, wind turbine components are subjected to various loads. For example, wind turbine blades are subjected to loads from gravity acting on them, wind pressure, changes in wind direction, and turbulence.

[0003] As the size of wind turbine blades increases, the load on the wind turbine also increases. To handle this increased load, the amount of material used in manufacturing the wind turbine can be increased. However, this increases the weight of the wind turbine and its manufacturing cost.

[0004] As an alternative to increasing the amount of material used in wind turbines, particularly for wind turbine blades, wind turbines can be equipped with blade connection tensioning members (e.g., in the form of wires), which are blade connection tensioning members that interconnect the wind turbine blades. These blade connection tensioning members allow the wind turbine blades to support each other, meaning that a portion of the load on the wind turbine blades is "shared" between the blades through the blade connection tensioning members.

[0005] Introducing such blade connection tensioners can generate noise due to air passing over them during wind turbine operation. Because the blade connection tensioners move with the rotor as it rotates, the angle of attack between the air and the corresponding blade connection tensioner changes during wind turbine operation. This is particularly problematic when the ratio of rotor angular speed to wind speed changes, such as when the turbine transitions from partial-load to full-load operation, or due to wind shear, turbulence, or yaw errors. Furthermore, the airflow over a given blade connection tensioner will not be perpendicular to its length. Therefore, the airflow over the blade connection tensioner has a component along its length. This makes it difficult to predict the expected noise level resulting from installing a specific type of blade connection tensioner on a given wind turbine. For example, modifications to the blade connection tensioners that appear to reduce noise on a non-moving component may not necessarily lead to noise reduction once the tensioner is installed on an operating wind turbine. Summary of the Invention

[0006] The purpose of embodiments of the present invention is to provide a wind turbine having a blade connection tensioning member extending between wind turbine blades, wherein the noise generated by the wind turbine is reduced compared to similar prior art wind turbines.

[0007] This invention provides a wind turbine comprising a tower, a nacelle mounted on the tower, a hub rotatably mounted on the nacelle, and at least three wind turbine blades, wherein each wind turbine blade extends between a root end connected to the hub and a tip end arranged opposite to the root end. The wind turbine also includes blade connection tensioning members, each extending between a connection point at one wind turbine blade and a connection point at an adjacent wind turbine blade. The connection point at a given wind turbine blade is arranged at a distance from both the root end and the tip end of the wind turbine blade. Each blade connection tensioning member includes: - A plurality of first segments having a first cross-sectional diameter and a plurality of second segments having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter. The first and second sections are arranged alternately along the length of the blade connecting tensioning member.

[0008] Therefore, the present invention provides a wind turbine comprising a tower, on which a nacelle is preferably mounted via a yaw system. A hub carrying at least three wind turbine blades is rotatably mounted on the nacelle. The hub and the wind turbine blades may be referred to as rotors. During operation, the rotors are positioned according to wind direction by appropriately operating the yaw system. The wind turbine blades capture wind and cause the hub to rotate. This rotation may then be transmitted to a generator via a gear system, where mechanical energy is converted into electrical energy, which can then be supplied to the power grid.

[0009] Each wind turbine blade extends between a root end connected to the hub (possibly via a pitch system) and a tip end arranged opposite to the root end. Thus, each wind turbine blade may optionally extend radially outward from the hub with a small cone angle.

[0010] The wind turbine also includes blade connection tensioning members. Each blade connection tensioning member extends between a connection point on one wind turbine blade and a connection point on an adjacent wind turbine blade. Thus, each blade connection tensioning member interconnects two adjacent wind turbine blades, i.e., wind turbine blades that are connected to the hub adjacent to each other. The blade connection tensioning member can be, for example, in the form of wire, cable, or any other suitable type of blade connection tensioning member.

[0011] The connection point on a given wind turbine blade is arranged at a distance from both the root and the tip. Therefore, the connection point is neither located at the root nor the tip, i.e., not at either of the two ends of the wind turbine blade. Instead, it is located at a suitable intermediate position between the root and the tip. This will be described in further detail below.

[0012] Therefore, the blade connection tensioning members enable wind turbine blades to support each other, meaning that the load on the wind turbine blades (especially edge loads and, optionally, some degree of flapping loads) is "shared" between the blades via the blade connection tensioning members. Consequently, the load on the wind turbine blades can be handled with a smaller material thickness during operation and downtime, thus reducing weight and manufacturing costs.

[0013] Each blade connection tensioning member includes a plurality of first segments having a first cross-sectional diameter and a plurality of second segments having a second cross-sectional diameter. For example, each blade connection tensioning member may have 20 to 400 first segments and 20 to 400 second segments, such as 40 to 200 first segments and 40 to 200 second segments. The first cross-sectional diameter is smaller than the second cross-sectional diameter. Therefore, the cross-sectional diameter of the blade connection tensioning member is not constant over the entire length of the blade connection tensioning member, but is smaller in the portions corresponding to the first segments than in the portions corresponding to the second segments.

[0014] The first and second segments are arranged alternately along the length of the blade-connecting tensioning member. In this context, the term "alternately arranged" should be interpreted as meaning that each first segment is arranged between two second segments or between one second segment and one end of the blade-connecting tensioning member, and each second segment is arranged between two first segments or between one first segment and one end of the blade-connecting tensioning member. However, it is not excluded that one or more additional segments having a cross-sectional diameter different from both the first and second cross-sectional diameters may be arranged between a first segment and a second segment.

[0015] Therefore, along the length direction, the cross-sectional diameter of the blade connection tensioning member varies alternately between the first cross-sectional diameter and the second cross-sectional diameter, and may have further variations in the cross-sectional diameter as described above.

[0016] The inventors of this invention have discovered that this alternating variation in the cross-sectional diameter of the blade connection tensioner results in a reduction in noise generated during wind turbine operation. More specifically, the inventors have discovered that the alternating variation in the cross-sectional diameter, in a manner that results in a reduction in noise caused by air passing over the blade connection tensioner as the rotor rotates, interferes with a portion of the airflow flowing near the blade connection tensioner. Recognizing this is by no means easy, because, as mentioned above, the interaction between the noise-generating airflow and the rotating blade connection tensioner is unpredictable.

[0017] The first segment may have a first length, the second segment may have a second length, and the first length may be substantially equal to the second length. According to this embodiment, all first segments have substantially the same length, i.e., the first length, and all second segments have substantially the same length, i.e., the second length. Furthermore, the length of the first segment is substantially equal to the length of the second segment.

[0018] The first and second lengths may be, for example, within the range of 1 to 6 times the diameter of the first cross-section, for example, within the range of 2 to 5 times the diameter of the first cross-section, for example, within the range of 2 to 4 times the diameter of the first cross-section, for example, approximately 4 times the diameter of the first cross-section.

[0019] For example, the first and second lengths can be in the range of 5 cm to 30 cm, for example, in the range of 10 cm to 25 cm, for example, about 20 cm.

[0020] In an alternative embodiment, the first length may differ from the second length. According to this embodiment, similar to the embodiment described above, all first segments have substantially the same length, and all second segments have substantially the same length. However, in this case, the lengths of the first segments differ from the lengths of the second segments. For example, the second length may be shorter than the first length. In this case, the segments with larger cross-sectional diameters are shorter than the segments with smaller cross-sectional diameters. For example, the first length may be in the range of 2 cm to 10 cm, for example, approximately 5 cm, and the second length may be in the range of 5 cm to 30 cm, for example, approximately 20 cm. Alternatively, the second length may be greater than the first length. For example, the first length may be in the range of 5 cm to 30 cm, for example, approximately 20 cm, and the second length may be in the range of 2 cm to 10 cm, for example, approximately 5 cm.

[0021] In another alternative embodiment, the length of the first segment and / or the length of the second segment can vary from one first / second segment to another. For example, the lengths of the first and / or second segments can vary randomly, or they can be systematically increased or decreased along the length direction of the blade connection tensioning member.

[0022] The diameter of the first cross section can be between 70% and 90% of the diameter of the second cross section, for example, between 75% and 85% of the diameter of the second cross section, for example, approximately 80% of the diameter of the second cross section.

[0023] According to this embodiment, the difference in cross-sectional diameter between the first section and the second section is large enough to produce the desired aerodynamic effect that reduces noise generation, but not so large as to produce undesirable side effects on the strength of the blade connection tensioning member or the performance of the rotor.

[0024] For example, the difference between the diameter of the first cross section and the diameter of the second cross section can be in the range of 5 mm to 50 mm, for example in the range of 10 mm to 30 mm, for example, about 20 mm.

[0025] Alternatively or additionally, the diameter of the first cross-section may be in the range of 70 mm to 110 mm, for example in the range of 80 mm to 100 mm, such as about 90 mm, and / or the diameter of the second cross-section may be in the range of 90 mm to 130 mm, for example in the range of 100 mm to 120 mm, such as about 110 mm.

[0026] Each blade connection tensioning member may include multiple transition sections, each transition section interconnecting a first section and a second section, and the transition section may have a length L3 within the range defined by L3 / (L1+L2)<0.05 (e.g., L3 / (L1+L2)<0.03), where L1 and L2 are the lengths of the first section and the second section interconnected by the transition sections, respectively.

[0027] According to this embodiment, the first segment and the adjacent second segment are interconnected by a transition segment. Therefore, the transition segment provides a transition between the smaller cross-sectional diameter of the first segment and the larger cross-sectional diameter of the second segment. Since L3 / (L1+L2)<0.05, the length L3 of the transition segment is significantly smaller than the length L1 of the first segment and / or the length L2 of the second segment. Therefore, the transition between the two cross-sectional diameters occurs in a relatively abrupt or sharp manner. It has been found that such abrupt or sharp transition is beneficial for achieving the desired aerodynamic effect in providing the desired noise reduction.

[0028] For example, the transition section can be defined as the section between the first section and the second section, where the cross-sectional diameter D is within the range defined by (D1 + 0.1∙(D2 - D1)) < D < (D2 - 0.1∙(D2 - D1)), where D1 is the first cross-sectional diameter and D2 is the second cross-sectional diameter. In this case, the length L3 of the transition section can be regarded as the distance between the position on the blade connection tension member where the cross-sectional diameter is greater than the first cross-sectional diameter by 10% of the difference between the first and second cross-sectional diameters and the position on the blade connection tension member where the cross-sectional diameter is less than the second cross-sectional diameter by 10% of the difference between the first and second cross-sectional diameters.

[0029] For example, the length L3 of the transition section can be less than 30 mm, for example less than 20 mm, for example less than 10 mm.

[0030] Each blade connection tension member can include: - a tension member core, and - a surface shaping layer circumferentially arranged relative to the tension member core, the surface shaping layer defining the first section and / or the second section.

[0031] Since the surface shaping layer is circumferentially arranged relative to the tension member core, it defines the shape and texture of the outer surface of the blade connection tension member. The first and / or second section can be provided, for example, by applying the surface shaping layer to some sections of the blade connection tension member and not applying it to other sections, or by changing the thickness of the surface shaping layer along the length direction of the blade connection tension member.

[0032] The tension member core can be made of a polymer material. The polymer material can be, for example, ultra-high molecular weight polyethylene, such as that manufactured under the trademark 'Dyneema'. Ultra-high molecular weight polyethylene fibers have a high strength / weight ratio, a high Young's modulus, and good fatigue properties.

[0033] As an alternative, the polymer material can be based on polyester, polyamide, nylon, polypropylene, aramid, etc. As another alternative, the polymer material can be a composite material, such as a liquid crystal polymer, such as poly(p-phenylene benzobisoxazole) (PBO).

[0034] As an alternative to the polymer material, the tension member core can be made of steel, for example in the form of steel wire, or made of carbon fiber. In the latter case, the tension member core can be provided as a composite member by carbon pultrusion.

[0035] The surface-forming layer may be or includes a braided or braided layer. According to this embodiment, the surface-forming layer may be directly braided or braided onto the tensioning member core, for example, by arranging yarns in a suitable pattern. Alternatively, the braided or braided layer may be manufactured separately and then arranged circumferentially relative to the tensioning member core. In one embodiment, the surface-forming layer may be or includes a 3D braided material, for example, made of synthetic polymer fibers.

[0036] The surface-forming layer may be or includes a coating. According to this embodiment, the surface-forming layer can be applied directly, for example, by brushing, spraying, or rolling, onto the tensioning member core in a suitable pattern. Preferably, the coating is a high-viscosity, UV-resistant coating material applied in one or more layers, with a total layer thickness of 1-6 mm. The coating may, for example, be a polyurethane-based coating.

[0037] The surface forming layer may be or include self-fusion tapes. According to this embodiment, the surface forming layer may include at least two layers disposed on or around the core, such that at least one self-fusion tape is attached to the top of the inner layer, thereby causing self-fusion.

[0038] The surface forming layer may be or include heat-shrinkable wrapping tape or heat-shrinkable tube. According to this embodiment, the surface forming layer may include one or more layers of heat-shrinkable wrapping tape circumferentially wrapped around the tensioning member core, followed by heating the heat-shrinkable wrapping tape to shrink the tape and form a tight layer around the tensioning member core; alternatively, the surface forming layer may include a heat-shrinkable tube circumferentially slid from one end of the tensioning member core onto the tensioning member core, followed by heating the heat-shrinkable tube to shrink the tube and form a tight layer around the tensioning member core.

[0039] The surface-forming layer may be or include open-cell or closed-cell foam. According to this embodiment, the surface-forming layer can be prepared by applying sprayed foam or other expanding fluid (e.g., expanded polyurethane) onto a tensioning member core, foaming, and then curing the open-cell or closed-cell foam. Alternatively, the open-cell or closed-cell foam can be manufactured separately and then arranged circumferentially relative to the tensioning member core.

[0040] The surface forming layer may be or include a porous or dense polyurethane material. According to this embodiment, the surface forming layer is preferably manufactured separately from the tensioning member core and then arranged circumferentially relative to the tensioning member core.

[0041] The surface-forming layer may include one or more surface-forming elements, which are respectively disposed between the tensioning core and the braided or braided layer, coating, self-fusion tape, heat-shrinkable wrapping tape or heat-shrinkable tube, open-cell or closed-cell foam, and / or porous or dense polyurethane material. According to this embodiment, the braided or braided layer, coating, self-fusion tape, heat-shrinkable wrapping tape or heat-shrinkable tube, open-cell or closed-cell foam, and / or porous or dense polyurethane material may have a substantially uniform thickness, and the first and second cross-sectional diameters of the first and second sections may be defined by the surface-forming elements. For example, a surface-forming element may be provided in the second section but not in the first section, or the first section may be provided with a surface-forming element smaller than the one provided in the second section.

[0042] The surface forming layer may include an inner layer arranged circumferentially relative to the core of the tensioning member and an outer layer arranged circumferentially relative to the inner layer, and the inner layer may define a first segment and / or a second segment.

[0043] According to this embodiment, the surface-forming layer comprises two layers, namely an inner layer and an outer layer, which are concentrically arranged relative to each other and relative to the tensioning member core, with the inner layer disposed between the tensioning member core and the outer layer. Furthermore, the outer surface of the outer layer forms the outer surface of the surface-forming layer, and thus forms the outer surface of the blade connection tensioning member. On the other hand, the inner layer defines a first section and / or a second section. Therefore, the inner layer can be selected to allow for easy and appropriate definition of the first section and / or the second section, while the outer layer can be selected to obtain suitable and desired surface characteristics of the blade connection tensioning member.

[0044] According to this embodiment, the blade connection tensioning member can be manufactured, for example, by applying an inner layer to the tensioning member core and then applying an outer layer to the inner layer.

[0045] The outer layer can be made of silicone-based, polyurethane-based, polyurea-based, or ethylene propylene rubber. These materials may have suitable UV resistance, be soft enough to absorb the impact of raindrops to achieve suitable rain erosion resistance, and have proven to produce a smooth surface-forming layer with improved noise and drag characteristics for skewed rotors under relevant flow conditions.

[0046] Alternatively or additionally, the outer layer may be in the form of a self-fusion tape, such as an EPDM-based or silicone-based tape. According to this embodiment, the outer layer can be easily applied to the inner layer by simply wrapping the self-fusion tape around it.

[0047] For example, the outer layer can be in the form of a molded shell, such as a polyurethane-based injection-molded profile, such as a C-shaped profile, or it can be in the form of a braided overlay that forms a greater overall thickness.

[0048] The surface forming layer may be made at least partially of a porous material. In this context, the term "porous material" should be interpreted as meaning a material that allows airflow to pass through it at least to a certain extent.

[0049] Due to the porous nature of the surface forming layer of the blade connection tensioner, the airflow passing through the blade connection tensioner during wind turbine operation will partially pass through the surface forming layer of the blade connection tensioner, rather than along its outer surface. Therefore, the porous outer layer interferes with the airflow.

[0050] The inventors of this invention have discovered that the perforated surface layer of the blade connection tensioning member, which provides interference with the passing airflow, results in a reduction in noise generated during wind turbine operation. Therefore, the noise generated by the wind turbine during operation is further reduced.

[0051] The porous material of the surface forming layer can be defined as having a porosity of at least 0.5, for example, in the range of 0.8 to 1.0, or in the range of 0.9 to 1.0.

[0052] Porosity is a dimensionless parameter Defined as ,in, It is the density of the actual porous material. Porosity is the density of a material without pores. Therefore, a porosity of 0 indicates that the material contains no pores, i.e. A porosity close to 1 indicates that the density of a porous material is significantly lower than that of a non-porous material, i.e. High porosity, such as close to 1, provides good acoustic performance, and therefore can be expected to result in a significant reduction in generated noise.

[0053] The porous material of the surface forming layer can be limited to 1000 Pa∙s / m 3 Up to 10000 Pa∙s / m 3 Airflow drag ratio within a given range. Airflow drag ratio is a measure of the resistance experienced by air particles as they pass through a material, thus providing a measure of how difficult or easy it is for air particles to pass through the material. It is also a parameter that controls the sound absorption acoustic behavior of porous materials.

[0054] Porous materials can be or include open-cell foams, such as polyurethane foam or polyethylene foam. A major advantage of using open-cell foams is that they are naturally porous, thus eliminating the need for complex manufacturing processes, such as additive manufacturing or secondary processing, to create porous flow channels. Furthermore, open-cell foams are typically lightweight.

[0055] In one embodiment, the porous material is an open-cell foam, and the porous material is disposed on the tensioning member core by spraying foam or providing an expanding fluid onto the tensioning member core. After foaming, the sprayed foam or expanding fluid is cured. Optionally, a mold may be disposed on the tensioning member core before the porous material is disposed on it, and sprayed foam or other expanding fluid may be provided into the mold to ensure the desired external shape and / or positioning of the porous material relative to the tensioning member core. After the porous material has cured, the mold is removed from the tensioning member, and optionally the porous material is subsequently surface-finished, for example, by grinding. It has been found that providing open-cell foam by spraying foam or providing an expanding fluid onto the tensioning member core also provides an advantageous method for preparing partially degraded porous material disposed on the tensioning member core. Specifically, the remediation method includes the steps of spraying foam or providing an expanding fluid onto the tensioning member core and optionally disposing of residual old porous material on the tensioning member core. Due to the nature of sprayed foam, residues of partially bonded old porous material can be reattached to the tensioning member core by the applied sprayed foam. Therefore, preparation of the surface of the tensioning member core with old porous material before applying the sprayed foam may be limited or even unnecessary. However, alternatively, the repair method may also include removing partially released porous material before spraying or providing an expanding fluid to the tensioning member core and optionally the old porous material. Furthermore, the method may optionally include the step of placing a mold on the tensioning member core before placing the porous material onto the tensioning member core, wherein the optional old porous material remains attached to the tensioning member core.

[0056] Airflow resistance is defined as the ratio of the pressure difference across a material sample to the volumetric airflow rate passing through the sample. Specific airflow resistance applies to a specific material thickness. Airflow drag ratio is defined as the specific airflow resistance per unit thickness of material in the airflow direction. Therefore, airflow drag ratio is a material-specific parameter; a low airflow drag ratio indicates that airflow can easily pass through the material, while a high airflow drag ratio indicates that airflow cannot easily pass through the material.

[0057] At 1000 Pa∙s / m 3 Up to 10000 Pa∙s / m 3 Within the range, for example, at 1000 Pa∙s / m 3 Up to 8000 Pa∙s / m 3 Within the range, for example, at 1000 Pa∙s / m 3 Up to 5000 Pa∙s / m 3 The airflow drag ratio within the specified range represents a relatively low airflow drag ratio. This is desirable because it allows airflow to easily pass through the surface-forming layer of the blade-connected tensioning member, and thus the aforementioned noise reduction effect is largely achieved.

[0058] Each blade connecting tensioning member can have a surface roughness of 0.100 mm. <R a <0.400 mm (e.g., 0.200 mm) <R a Within the range defined by <0.300 and / or 0.200 mm <R z <0.500 mm (e.g., 0.300 mm) <R z The outer surface is defined within the range of <0.400). According to this embodiment, the surface texture and / or surface roughness of the blade connection tensioning member are obtained, which further helps to reduce the noise generated by the interaction between the blade connection tensioning member and the passing air.

[0059] The above values ​​are particularly suitable for blade connection tensioning components with a diameter of approximately 70 mm. For smaller diameters, lower surface roughness may be appropriate, while for larger diameters, higher surface roughness may be suitable. A suitable normalized measure of roughness could be 0.0014. <R a / D<0.0057, for example 0.0029 <R a / D<0.0043, and / or 0.0029 <R z / D<0.0071, for example 0.0043 <R z / D<0.0057, where D is a representative diameter of the blade connection tensioning member. It should be noted that the above R... a and R z The preferred range is to provide "macro" roughness of the outer surface for surface texture (see below).

[0060] The aforementioned intervals can be defined on an evaluation scale or filter scale, which corresponds to the length of the blade connection tensioning member between relevant connection points. Therefore, these parameters and intervals can be considered as the "macro" roughness, or "low-frequency" roughness, of the surface-forming layer. The sample length or cutoff length λ used for "macro" roughness... c It can be λ c =60 mm, excluding the transition section. Accordingly, the sample length or cutoff length for "micro" roughness can be λ. c =0.8 mm, excluding the transition section.

[0061] According to ISO standards 16610-1 and 16610-21, parameter R a R is defined as the average deviation of the surface position from the average surface position. Therefore, R a It is a measure of the size of the peaks and valleys formed on the surface, taken as an average. Outliers in the form of very large or very small deviations affect the parameter R. a The impact is minimal.

[0062] Furthermore, according to ISO standards 16610-1 and 16610-21, parameter R z R is defined as the difference between the representative sample with the largest deviation from the average surface position and the representative sample with the smallest deviation from the average surface position. Therefore, R z It reflects the extreme cases of surface position deviation, and is therefore a measure of the magnitude of surface position fluctuation. Outliers in the form of very large or very small deviations affect the parameter R. z It has a significant impact.

[0063] The inventors of this invention have discovered that a certain surface roughness improves the aerodynamic characteristics of the blade connection tensioning member, but excessively high surface roughness may have adverse effects. Therefore, the roughness defined by the above-mentioned range is suitable.

[0064] For example, R a It can be in the range of 0.100 mm to 0.400 mm, for example, in the range of 0.200 mm to 0.300 mm, for example, in the range of 0.220 mm to 0.280 mm, for example, in the range of 0.230 mm to 0.270 mm.

[0065] Similarly, R z It can be in the range of 0.200 mm to 0.500 mm, for example, in the range of 0.300 mm to 0.400 mm, for example, in the range of 0.320 mm to 0.380 mm, for example, in the range of 0.330 mm to 0.370 mm.

[0066] At the microscale or high-frequency scale, the surface roughness of the surface-forming layer can be significantly lower than that at the macroscale, for example, by 1-3 orders of magnitude. For example, at the microscale, R... a It can be in the range of 0.700 μm-1.400 μm, for example, in the range of 0.800 μm-1.200 μm, for example, about 1.000 μm.

[0067] The connection point at the wind turbine blade can be arranged at a distance from the root end of the blade between 15% and 50% of the blade's length from the root to the tip. According to this embodiment, the connection point at the wind turbine blade is located away from both the root and tip ends of the blade.

[0068] The location of the connection point along the wind turbine blade can be chosen in a way that appropriately balances various considerations. For example, positioning the connection point near the tip of the wind turbine blade results in very effective support of the blade connection tensioner for the wind turbine blade. However, this comes at the cost of high drag caused by the blade connection tensioner during rotor rotation, thus reducing energy production. On the other hand, positioning the connection point near the root of the wind turbine blade results in low drag caused by the blade connection tensioner, thus minimizing the adverse impact on the wind turbine's energy production. However, the support of the blade connection tensioner for the wind turbine blade will not be very effective. By arranging the connection point at a distance of 15% to 50% of the wind turbine blade length from the root, these considerations are balanced in such a way that effective support is obtained without introducing unacceptable drag. Furthermore, by positioning the connection point in this area, it is ensured that the blade connection tensioner is attached to the wind turbine blade at a location where the structural stiffness of the wind turbine blade is sufficiently high. For example, the structural stiffness of wind turbine blades decreases towards the tip, so attaching the blade tensioning member too close to the tip can result in significant pre-bending of the wind turbine blade.

[0069] The wind turbine can be a pitch-controlled wind turbine. According to this embodiment, the wind turbine blades are connected to the hub via their respective pitch systems, and the connection points at the wind turbine blades for connecting the blade tensioning cables are arranged to allow the blades to pitch, enabling the wind turbine blades to perform pitch movements relative to the hub about a longitudinal axis arranged along the blade length to adjust the angle of attack between the wind turbine blades and the incoming wind.

[0070] The wind turbine may also include a pretensioning system arranged with the hub, and each blade connection tensioning member may include a tensioner leg, which may be connected to the pretensioning system.

[0071] According to this embodiment, pretensioning is introduced into each blade connection tensioning member by appropriately operating the pretensioning system to act on the blade connection tensioning members via the corresponding tensioner legs. By appropriately applying pretensioning to the blade connection tensioning members, a desired level of blade mutual support can be achieved. The pretensioning applied to the wind turbine blade connection tensioning members can be adjustable.

[0072] Each tensioner leg may include: - A plurality of first segments having a first cross-sectional diameter and a plurality of second segments having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter. The first and second sections are arranged alternately along the length of the tensioner leg.

[0073] According to this embodiment, due to the varying cross-sectional diameter, the tensioner leg exhibits acoustic characteristics similar to those of the blade connection tensioning member. Therefore, the noise level generated by air passing through the tensioner leg is also substantially reduced in the manner described above regarding the blade connection tensioning member. Attached Figure Description

[0074] The invention will now be described in further detail with reference to the accompanying drawings, in which: Figure 1 and Figure 2 A wind turbine according to one embodiment of the present invention is shown. Figure 3 and Figure 4 A blade connection tensioning member for a wind turbine according to a first embodiment of the present invention is shown. Figure 5 and Figure 6 A blade connection tensioning member for a wind turbine according to a second embodiment of the present invention is shown. Figure 7 and Figure 8 A portion of a blade connection tensioning member of a wind turbine according to a third embodiment of the present invention is shown. Figure 9 and Figure 10 A portion of a blade connection tensioning member of a wind turbine according to a fourth embodiment of the present invention is shown. Figure 11 The diagram illustrates a transition section between a first and a second section of a blade connection tensioning member for a wind turbine according to an embodiment of the present invention, and... Figure 12 A wind turbine according to one embodiment of the present invention is shown. Detailed Implementation

[0075] Figure 1 and Figure 2 A wind turbine 1 according to one embodiment of the present invention is shown. Figure 1 This is the front view of wind turbine 1. Figure 2 This is a side view of wind turbine 1.

[0076] The wind turbine 1 includes a tower 2, a nacelle 3 mounted on the tower 2, and a hub 4 mounted on the nacelle 2. Three wind turbine blades 5 are connected to the hub 4. Each wind turbine blade 5 extends between a root end 6 connected to the hub 4 and an oppositely arranged tip end 7.

[0077] The wind turbine 1 also includes three blade connection tensioning members 8. Each blade connection tensioning member 8 interconnects two adjacent wind turbine blades 5 by means of a connection point 9 at the corresponding wind turbine blade 5. The wind turbine blades 5 can support each other through the blade connection tensioning members 8, meaning that the load on the wind turbine blades 5, especially the edge load and flapping load, is shared between the wind turbine blades 5 through the blade connection tensioning members 8.

[0078] The blade connection tensioning member 8 is of the type comprising a plurality of first segments having a first cross-sectional diameter and a plurality of second segments having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter. The first segments and the second segments are arranged alternately along the length direction of the blade connection tensioning member 8.

[0079] Therefore, the cross-sectional diameter of the blade connection tensioning member 8 is not constant along its entire length, but varies between a first cross-sectional diameter and a second cross-sectional diameter. This alternating variation in cross-sectional diameter interferes with the airflow along the length of the blade connection tensioning member, resulting in a reduction in noise caused by the air passing through the blade connection tensioning member as the rotor rotates and the angle of attack between the air and the blade connection tensioning member changes accordingly. Therefore, noise generated during the operation of the wind turbine 1 due to the air passing through the blade connection tensioning member 8 is reduced.

[0080] Figure 3 and Figure 4 The blade connection tensioning member 8 of a wind turbine according to a first embodiment of the present invention is shown. Figure 3 This is a perspective view of the blade connection tensioning member 8, and Figure 4 This is a side view of the blade connection tensioning member 8.

[0081] Figure 3 and Figure 4 The blade connection tensioning member 8 includes a plurality of first sections 12 and a plurality of second sections 13. In the first sections 12, the blade connection tensioning member 8 has a first cross-sectional diameter, and in the second sections 13, the blade connection tensioning member 8 has a second cross-sectional diameter. The first cross-sectional diameter is smaller than the second cross-sectional diameter. The first sections 12 and the second sections 13 are arranged alternately along the length of the blade connection tensioning member 8.

[0082] Therefore, along the length of the blade connection tensioning member 8, the cross-sectional diameter alternates between a first smaller cross-sectional diameter and a second larger cross-sectional diameter. It can also be seen that the transition between the first segment 12 and the second segment 13 is relatively abrupt or sudden. This variation in cross-sectional diameter disrupts the airflow parallel to the length of the blade connection tensioning member 8. This results in a reduction in noise generated during wind turbine operation due to airflow impacting the blade connection tensioning member 8.

[0083] The first section 12 and the second section 13 can be provided, for example, by changing the thickness of the outer layer or surface forming layer of the blade connection tensioning member 8.

[0084] exist Figure 3 and Figure 4 In the blade connecting tensioning member 8, the length of the first section 12 and the length of the second section 13 are basically the same.

[0085] Figure 5 and Figure 6 The blade connection tensioning member 8 of a wind turbine according to a second embodiment of the present invention is shown. Figure 5 This is a perspective view of the blade connection tensioning member 8, and Figure 6 This is a side view of the blade connection tensioning member 8.

[0086] Figure 5 and Figure 6 The blade connection tensioning member 8 and Figure 3 and Figure 4 The blade connection tensioning member 8 is very similar, meaning that it includes a plurality of first sections 12 having a first cross-sectional diameter and a plurality of second sections 13 having a second cross-sectional diameter. Therefore, the above regarding Figure 3 and Figure 4 The proposed reference numerals also apply here.

[0087] However, in Figure 5 and Figure 6 In the blade connection tensioning member 8, the length of the first section 12 is significantly smaller than the length of the second section 13.

[0088] In another embodiment (not shown), the length of the first segment can be varied, such that some or all of the first segments have different, for example, randomly varying or gradually varying lengths. Similarly, in another embodiment (not shown), the length of the second segment can be varied, such that some or all of the second segments have different, for example, randomly varying or gradually varying lengths.

[0089] Figure 7 and Figure 8 A portion of the blade connection tensioning member 8 of a wind turbine according to a third embodiment of the present invention is shown. Figure 7This is a perspective view of the blade connection tensioning member 8, and Figure 8 This is a side view of the blade connection tensioning member 8.

[0090] Figure 7 and Figure 8 The blade connection tensioning member 8 includes a tensioning member core 10 and a surface forming layer 11 arranged circumferentially relative to the tensioning member core 10. Figure 7 In this view, a portion of the surface forming layer 11 has been removed to expose the tensioning member core 10 and to provide a cross-sectional view of the surface forming layer 11.

[0091] The surface forming layer 11 is in the form of a braided layer, which can be applied at various thicknesses along the length direction of the blade connecting tensioning member 8 to form a first segment with a first cross-sectional diameter and a second segment with a second cross-sectional diameter, for example, as described above regarding... Figures 3-6 The method described above reduces noise generated during wind turbine operation due to air impact on the blade connection tensioning member 8.

[0092] Figure 9 and Figure 10 A portion of the blade connection tensioning member 8 of a wind turbine according to a fourth embodiment of the present invention is shown. Figure 9 This is a perspective view of the blade connection tensioning member 8, and Figure 10 This is a cross-sectional view of the blade connection tensioning member 8.

[0093] Figure 9 and Figure 10 The blade connection tensioning member 8 is similar to Figure 7 and Figure 8 The blade connection tensioning member 8 includes a tensioning member core 10 and a surface-forming layer 11 arranged circumferentially relative to the tensioning member core 10. The surface-forming layer 11 is made of a porous material in the form of open-cell polyester foam, defining relatively large and visible pores that allow incoming airflow to pass through the surface-forming layer 11 at least partially. This reduces noise generated during wind turbine operation due to air impact on the blade connection tensioning member 8.

[0094] Furthermore, the thickness of the surface forming layer 11 can vary along the length of the blade connecting tensioning member 8 to form a first segment with a first cross-sectional diameter and a second segment with a second cross-sectional diameter, as described above. Figures 3-6 The way it is described.

[0095] Figure 11 The diagram shows a transition section 14 between a first section 12 and a second section 13 of a blade connection tensioning member 8 of a wind turbine according to an embodiment of the present invention.

[0096] Similar to the reference above Figures 3-6 the described blade connection tensioning member 8, Figure 11 the blade connection tensioning member 8 includes a plurality of first segments 12 having a first cross-sectional diameter D1 and a plurality of second segments 13 having a second cross-sectional diameter D2. The first segments 12 have a first length L1, the second segments 13 have a second length L2, and the first segments 12 and the second segments 13 are alternately arranged along the length direction of the blade connection tensioning member 8.

[0097] The alternately arranged first segments 12 and second segments 13 are connected to each other by transition segments 14, each transition segment having a third length L3. Thus, each transition segment 14 defines a transition between the smaller cross-sectional diameter D1 of the first segment 12 and the larger cross-sectional diameter D2 of the adjacent second segment 13.

[0098] It can be seen that the third length L3 of the transition segment 14 is significantly shorter than the first length L1 of the first segment 12 and is also significantly shorter than the second length L2 of the second segment 13. Thus, the transition between the first cross-sectional diameter D1 and the second cross-sectional diameter D2 occurs in a relatively sudden or sharp manner. This ensures that the desired aerodynamic effect for providing the required noise reduction is obtained. The third length L3 can be, for example, within the range defined by L3 / (L1+L2)<0.05 (e.g., L3 / (L1+L2)<0.03).

[0099] For example, the transition segment 14 can be defined as the segment between the first segment 12 and the second segment 13, wherein the cross-sectional diameter D is within the range defined by (D1+0.1∙(D2-D1))<D<(D2-0.1∙(D2-D1)).

[0100] Figure 12 FIG. 16 shows a wind turbine 1 according to an embodiment of the present invention. Figure 12 The wind turbine 1 is similar to Figure 1 and Figure 2 the wind turbine 1, in the sense that it is provided with a blade connection tensioning member 8. Thus, the reference numerals proposed above with respect to Figure 1 and Figure 2 also apply herein.

[0101] Figure 12 The wind turbine 1 is also provided with a pre-tensioning system 15 located at the hub 4. The tensioner legs 16 interconnect each blade connection tensioning member 8 with the pre-tensioning system 15 in order to introduce pre-tension in each blade connection tensioning member 8. By appropriately selecting the introduced pre-tension, a desired level of mutual support of the wind turbine blades 5 can be obtained.

[0102] The tensioner leg 16 can be similar to the blade-connected tensioning member 8, including a plurality of first segments having a first cross-sectional diameter and a plurality of second segments having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter, and wherein the first and second segments are arranged alternately along the length direction of the tensioner leg 16. In this case, the tensioner leg 16 exhibits acoustic characteristics similar to those of the blade-connected tensioning member 8, and thus noise reduction due to air passing through the tensioner leg 16 is also achieved.

Claims

1. A wind turbine (1) comprising a tower (2), a nacelle (3) mounted on the tower (2), a hub (4) rotatably mounted on the nacelle (3), and at least three wind turbine blades (5), wherein, Each wind turbine blade (5) extends between a root end (6) connected to a hub (4) and a tip end (7) arranged opposite to the root end (6). The wind turbine (1) also includes blade connection tensioning members (8), each blade connection tensioning member (8) extending between a connection point (9) at a wind turbine blade (5) and a connection point (9) at an adjacent wind turbine blade (5), wherein the connection point (9) at a given wind turbine blade (5) is arranged at a distance from the root end (6) and a distance from the tip end (7), wherein each blade connection tensioning member (8) includes: - A plurality of first segments (12) having a first cross-sectional diameter and a plurality of second segments (13) having a second cross-sectional diameter, wherein the first cross-sectional diameter is smaller than the second cross-sectional diameter. The first section (12) and the second section (13) are arranged alternately along the length of the blade connecting tensioning member (8).

2. The wind turbine (1) according to claim 1, wherein, The first segment (12) has a first length, and the second segment (13) has a second length, wherein the first length is substantially equal to the second length.

3. The wind turbine (1) according to claim 1 or 2, wherein, The diameter of the first cross-section is between 70% and 90% of the diameter of the second cross-section.

4. The wind turbine (1) according to any one of the preceding claims, wherein, The diameter of the first cross section is in the range of 70 mm to 110 mm, and / or the diameter of the second cross section is in the range of 90 mm to 130 mm.

5. The wind turbine (1) according to any one of the preceding claims, wherein, Each blade connecting tensioning member (8) includes multiple transition sections (14), each transition section (14) interconnecting a first section (12) and a second section (13), wherein the transition section (14) has a length L3 within the range defined by L3 / (L1+L2)<0.05, wherein L1 and L2 are the lengths of the first section (12) and the second section (13) interconnected by the transition section (14), respectively.

6. The wind turbine (1) according to any one of the preceding claims, wherein, Each blade connection tensioning member (8) includes: -Tensioning component core (10), and - A surface forming layer (11) arranged circumferentially relative to the tensioning member core (10) defines a first section (12) and / or a second section (13).

7. The wind turbine (1) according to claim 6, wherein, The surface forming layer (11) is or includes a braided or braided layer, a coating, a self-fusion tape, a heat-shrinkable wrapping tape or heat-shrinkable tube, an open-cell or closed-cell foam, and / or a porous or dense polyurethane material.

8. The wind turbine (1) according to claim 7, wherein, The surface forming layer (11) includes one or more surface forming elements arranged between the tensioning member core (10) and the braided or braided layer, coating, self-fusion tape, heat shrink wrap or heat shrink tube, open or closed cell foam, and / or porous or dense polyurethane material.

9. The wind turbine (1) according to any one of claims 6-8, wherein, The surface forming layer (11) includes an inner layer arranged circumferentially relative to the tensioning member core (10) and an outer layer arranged circumferentially relative to the inner layer, wherein the inner layer defines a first section (12) and / or a second section (13).

10. The wind turbine (1) according to claim 9, wherein, The outer layer is made of silicone-based materials, polyurethane-based materials, polyurea-based materials, or ethylene propylene rubber.

11. The wind turbine (1) according to claim 9 or 10, wherein, The outer layer is in the form of a self-fusion zone.

12. The wind turbine (1) according to any one of claims 6-11, wherein, The surface forming layer (11) is at least partially made of a porous material.

13. The wind turbine (1) according to any one of the preceding claims, wherein, Each blade connecting tensioning member (8) has a surface roughness of 0.100 mm. <R a Within the range defined by <0.400 mm and / or within 0.200 mm <R z The outer surface within the range defined by <0.500 mm.

14. The wind turbine (1) according to any one of the preceding claims, wherein, The connection point (9) at the wind turbine blade (5) is arranged at a distance from the root end (6) between 15% and 50% of the length of the wind turbine blade (5) from the root end (6) to the tip end (7).

15. The wind turbine (1) according to any one of the preceding claims, wherein, A wind turbine (1) is a pitch-controlled wind turbine.

Images