A wind turbine blade and a wind power generation device having a structure resistant to blade bending

Abstract

The present invention discloses a wind turbine blade and a wind power generation device having a structure for resisting blade bending. The wind turbine blade includes: a housing and an elastic cavity; the elastic cavity is disposed within the blade cavity formed by the housing, contacts the inner surface of the housing, and extends longitudinally along the interior of the blade cavity. After the large-scale development of wind turbines, the lightweight long blade structure of the present invention for resisting blade bending fracture instability is an innovation in the stress structure of the key load-bearing parts of the internal structure of traditional blades. By applying the basic principles of thermodynamics, after the blade is subjected to the action of air flow and various loads on the outside, the new cavity structure inside the blade with a pressure greater than the natural environmental air pressure established in advance has a beam sufficient to support the load-bearing structure in the blade cavity structure and a reaction force surface that supports the inner surface of the cavity structure, collaborates with the beam to resist beam bending, and collaborates with the inner surface of the blade cavity to resist deformation, absorbs the vibration energy of the beam, and suppresses the stall loss caused by blade bending.

Description

Technical Field

[0001] The present invention relates to the technical field of wind turbine blade shape control. By innovating the internal structure of traditional wind turbine blades and solving the current situation where blades are forced to bear bending loads, a new technology is achieved in which the new blade structure is lightweight, actively resists bending, suppresses blade flapping, avoids tower sweeping, and at the same time actively regulates the blade stiffness to adapt to the influence of the natural environmental temperature on the fiberglass material of the blade. Background Art

[0002] Currently, wind turbines are developing towards larger sizes and higher powers. Due to the increase in size, the blade structure and loads have become increasingly complex, leading to an increasingly serious problem of blade damage. Among various damage mechanisms of existing wind turbine blades, due to buckling and fracture instability of the structure, the blade as a whole may break, and in some cases, it may even directly sweep the tower, causing a major safety accident of the entire machine toppling. How to innovate the technology of traditional structure blades with a relatively small cost in a highly competitive market environment, reduce the blade weight and cost, and achieve good anti-buckling and fracture resistance performance is an important technical requirement in the blade design industry. The quality and performance of blades are of great significance to the healthy development of the wind power industry.

[0003] Examples are given to reflect the methods and measures to solve the above technical requirements in the current field, so as to illustrate the need to continue to seek solutions.

[0004] For example, CN 114718802 A, an improved method for anti-buckling of existing horizontal axis wind turbine blades, discloses an improved method for anti-buckling of existing horizontal axis wind turbine blades. The method includes the following steps: evaluating the buckling characteristics of existing wind turbine blades with buckling problems, determining the area where the buckling phenomenon occurs in the blade, and designing a single or several anti-buckling reinforcement structural components according to the structural characteristics of the blade in this area, and carrying out on-site technical transformation work on the buckling part of the blade and installing the anti-buckling reinforcement structural components to make the existing blade meet the anti-buckling performance requirements. By adopting this technology, the anti-buckling performance of wind turbine blades with buckling problems during existing operation can be improved through technical transformation. The improvement of the anti-buckling performance of wind turbine blades does not change the aerodynamic shape and the original layup of the blade, and will not cause adverse effects on the performance of the blade. It can be seen that this is a on-site reinforcement technical measure, a reinforcement technology measure for local blade structure to resist bending, and a measure to implement reinforcement improvement on the discovered weak points after operation, without involving how to suppress the overall bending of the rear half or the end of long blades.

[0005] For example, in CN 114580247 A, a design method for the anti-buckling reinforcement structure of a horizontal axis wind turbine blade. Among various damage mechanisms of the blade, due to the buckling instability problem of the structure, which in turn leads to the overall damage of the blade, it is a serious damage situation. Currently, to solve the blade buckling problem, the layup structure of the blade is changed to adjust the stiffness of the blade to avoid buckling. This method, although it can avoid buckling, requires a large adjustment to the blade structure design, increasing the weight and cost of the blade. How to achieve avoiding buckling without major changes to the main structure of the blade and without significant changes to the blade weight and cost, an analysis, design and evaluation method for an anti-buckling instability reinforcement structure is proposed. This method includes the following steps: Analyze the buckling characteristics of the wind turbine blade to determine whether there is buckling in the blade. If buckling occurs, determine the area where buckling occurs, and design a single or several anti-buckling reinforcement structure components according to the structural characteristics of the blade in this area. Re-analyze the buckling of the blade installed with the reinforcement structure components to determine whether there is still buckling in the modified blade. According to the results of the re-analysis and evaluation, determine whether the modified blade meets the anti-buckling performance requirements, or continue to improve the reinforcement structure components until a satisfactory analysis and evaluation effect is achieved.

[0006] For example, in CN 108481628 B, a web for a wind turbine blade, a wind turbine blade, and a mold for manufacturing the web of a wind turbine blade. As the blade length increases, the blade load also continuously increases, and the existing structure of the main beam plus two webs of the wind turbine blade cannot meet the requirements of the structural design of large wind turbine blades. The traditional "I-beam" web structure cannot meet the design requirements, and for large megawatt-class and large chord-length wind turbine blades, the structural safety risk will increase significantly. Especially in the area near the maximum chord length of the blade, the blade is prone to frequent structural problems under complex wind conditions. Especially when the blade has large deformations under wind load operation, problems such as blade buckling and trailing edge structural damage often occur in the trailing edge area of the maximum chord length, resulting in poor reliability and safety during the operation of the wind turbine blade.

[0007] For example, in CN 105760629 A, an optimized design method for the layup of the main beam of a wind turbine blade. Through optimized layup design, the weight of the blade can be effectively reduced, the fatigue load can be reduced, and the cost can be effectively saved. Optimize the layup design for the main beam. The main beam of the blade is a box structure, and the blade profile is a structure form of the main beam plus the skin, which consists of three parts: the skin, the main beam cap, and the shear web. Optimize the blade layup to reduce the weight under the condition of meeting the blade stiffness. Here, the stiffness requirement is a safety boundary condition. Reducing the weight by means of optimized layup design will inevitably touch the safety boundary condition, which is an undesirable idea.

[0008] In addition, in order to solve the problem of large vibration deformation of wind turbine blades, the current method also includes increasing the thickness of blade composite materials in the blade layer to improve the stiffness of the blade, but this method will increase the weight of the blade, thereby increasing the manufacturing and installation costs of the wind turbine. In terms of appearance design, in order to ensure a safe distance between the blade and the tower, the current blades are pre-bent. For a 6MW wind turbine of the order of 100 meters, the clearance distance of the blade tip pre-bend will be as high as 4 meters, but this practice changes the aerodynamic characteristics of the blade to a certain extent, thereby reducing the power output of the wind turbine, seriously affecting the economic efficiency of wind power generation. In terms of operation strategy, the wind turbine blades are controlled by variable pitch to reduce wind loads. Although this practice can reduce vibration, the windward area of ​​the wind turbine blades is reduced, and the power generation efficiency is also reduced. At the same time, when facing extreme gusts and instantaneous wind direction changes, the blade pitch system is constrained by inertia and has no time to respond (that is, the inherent problem of slow frequency response), and the blades cannot avoid the large vibration caused by extreme loads in this case. Summary of the invention

[0009] In view of this, an object of the embodiments of the present invention is to provide a wind turbine blade and a wind power generation device having a structure for resisting blade bending, so as to solve the technical problem in the prior art that blades are bent and broken due to excessive blade size.

[0010] To achieve the above-mentioned object, in a first aspect, the present invention provides a wind turbine blade having a structure for resisting blade bending, the blade comprising: a shell and an elastic cavity;

[0011] The elastic cavity is arranged in the blade cavity formed by the shell. After the elastic cavity expands, it contacts the inner surface of the shell and extends longitudinally along the length direction of the blade cavity.

[0012] In some possible implementations, the blade further includes a protective cover, which is disposed inside the blade and outside the elastic cavity;

[0013] The initial shape of the elastic cavity is cylindrical, elliptical or non-cylindrical, the length of the elastic cavity is less than or equal to the length of the blade cavity, and the shape of the protective cover matches the shape of the blade cavity where the protective cover is located.

[0014] In some possible implementations, the blade further comprises a beam of a load-bearing structure;

[0015] The beam of the bearing structure is arranged inside the blade cavity formed by the shell and extends along the longitudinal direction of the blade cavity;

[0016] The elastic cavity is arranged inside the beam of the bearing structure and contacts the inner surface of the beam of the bearing structure.

[0017] In some possible embodiments, the beam of the load-bearing structure is a tubular longitudinal beam structure, the tubular longitudinal beam structure is a tubular longitudinal beam, the tubular longitudinal beam forms an annular cavity, and the elastic cavity is arranged in the annular cavity; after the elastic cavity expands, it generates a first reaction force surface against the bending of the tubular longitudinal beam on the tubular longitudinal beam.

[0018] In some possible embodiments, the beam of the load-bearing structure is a new web structure of a framed longitudinal beam; the new web structure of the framed longitudinal beam includes: a first main beam and a second main beam arranged in pairs up and down, and two curved webs arranged between the first main beam and the second main beam. A frame-shaped cavity is formed between the first main beam, the second main beam and the two curved webs, and the curved surface of the curved web is concave towards the frame-shaped cavity;

[0019] When the elastic cavity expands, it generates a second reaction force surface against bending on the curved web, and a third reaction force surface against bending on the upper main beam and the lower main beam.

[0020] In some possible embodiments, one or more elastic cavities are arranged at the trailing edge of the blade cavity, and the elastic cavities are connected to the inner surface of the housing through an adhesive layer.

[0021] In some possible embodiments, the blade further includes a plurality of reinforcing ribs;

[0022] A plurality of the reinforcing ribs are arranged inside the blade cavity parallel to the central axis of the blade and are connected to the housing. The plurality of reinforcing ribs and the housing divide the blade cavity into a plurality of sub-cavities, and the elastic cavity is arranged inside the sub-cavities;

[0023] The shape of the elastic cavity matches the shape of the sub-cavity.

[0024] In some possible embodiments, a fluid inlet and an automatic pressure relief valve are arranged on the elastic cavity for filling fluid into the elastic cavity, and the fluid includes gas or liquid; when the fluid is gas, the gas source is an automatic air replenishment system or a local air replenishment device; when the fluid is liquid, the liquid source is a liquid supply and replenishment controller.

[0025] In some possible embodiments, the automatic air replenishment system includes: an inflation device, a slip ring, a first connecting pipeline, a second connecting pipeline, and a pressure value display or transmission device;

[0026] The inflation device is arranged in the nacelle of the wind turbine. The inflation device is connected to a slip ring installed on the blade hub through the first connection pipeline. The slip ring is connected to the fluid inlet of the elastic cavity through the second connection pipeline. The pressure value display or transmission device is installed on the elastic cavity for locally displaying or transmitting the pressure value or sensor signal in the elastic cavity.

[0027] The inflation device is used to inflate or supplement air to the elastic cavity according to the pressure value or sensor signal.

[0028] In some possible implementation manners, a Hall piezoelectric sensor, a strain type pressure transmitter or a polyvinylidene fluoride film is arranged on the blade for transmitting the bending signal of the blade to the air supply and supplementing device in the nacelle. The air supply and supplementing device is used to automatically supplement air to the elastic cavity according to the natural environment temperature of the wind farm and the bending signal of the blade.

[0029] In some possible implementation manners, the local air supply and supplementing device is arranged at the open position of the blade root. The local air supply and supplementing device includes: an air pump, a supplementary air pipeline, an outlet pressure and flow transmitter, a controller and a driving motor.

[0030] The outlet pressure and flow transmitter is used to feedback the outlet pressure and flow to the controller. The controller is used to input a control signal to the driving motor. The driving motor is used to control the air pump to locally supplement air to the elastic cavity through the supplementary air pipeline according to the input control signal.

[0031] In some possible implementation manners, an image sensor and a vibration sensor are arranged on the blade. The image sensor and the vibration sensor are respectively electrically connected to the controller of the air source.

[0032] The image sensor is used to observe the bending amplitude and bending direction of the wind turbine blade in real time and transmit the signal of the real-time observation to the controller of the air source.

[0033] The vibration sensor is used to monitor the vibration signal of the blade in real time and transmit the vibration signal to the controller of the air source.

[0034] The controller of the air source is used to control the air source to inflate the elastic cavity.

[0035] In a second aspect, an embodiment of the present invention provides a wind power generation device with resistance to blade bending. The wind power generation device includes the wind turbine blade described in the first aspect.

[0036] The above technical solution has the following beneficial effects:

[0037] The present invention breaks away from the single idea adopted in the traditional blade structure design, so that the stiffness of the main beam in the traditional blade is no longer independently borne by the main beam skin, the main beam cap, and the shear web alone. This increases the toughness of the blade itself and at the same time has a new structure that can absorb vibration energy and tremor energy. After the blade is affected by the airflow and various loads externally, it has a reaction force to resist bending deformation itself. This reaction force is not the reaction force generated by the traditional blade shell attempting to recover after deformation, but spontaneously increases the reaction force or so-called reliance to prevent the blade, and is no longer simply the transmission of the interaction force between the beam and the web. In this way, after the blade receives the wind load externally, a reaction force can be spontaneously generated inside the blade to resist the forced bending of the beam. Even the original cavity of the blade also has a reaction force to resist deformation, rather than the shell that constitutes the cavity alone resisting bending deformation. Currently, the research and implementation of this new structure that can absorb vibration and tremor energy inside the traditional wind turbine blade and can spontaneously generate a reaction force surface inside the blade to resist the forced bending of the beam have not been carried out. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of a wind turbine blade with a structure for resisting blade bending according to an embodiment of the present invention;

[0040] Figure 2A It is a schematic diagram of a blade with a tubular longitudinal beam structure according to an embodiment of the present invention;

[0041] Figure 2B is Figure 2A a structural diagram of a reaction force surface that can be constructed inside the blade to resist the bending of the tubular longitudinal beam;

[0042] Figure 3 It is a transient schematic diagram of the external force load of a blade along the length direction according to an embodiment of the present invention;

[0043] Figure 4 It is a schematic diagram of a blade with a new web structure of a frame-shaped longitudinal beam according to an embodiment of the present invention;

[0044] Figure 5 is Figure 4 a structural diagram of a reaction force surface in which the internal components of the blade can resist the bending of the main beam and the bending of the curved web;

[0045] Figure 6 It is a schematic diagram of establishing a curved surface that can resist the reaction force of the trailing edge cavity deformation at the trailing edge of the blade in an embodiment of the present invention;

[0046] Figure 7 It is a schematic diagram of a structure for setting a bending resistance in the inner cavity of an aluminum alloy equal chord length extrusion formed blade in an embodiment of the present invention;

[0047] Figure 8 It is a schematic diagram of another structure for setting a bending resistance in the inner cavity of an aluminum alloy equal chord length extrusion formed blade in an embodiment of the present invention;

[0048] Figure 9 It is a schematic diagram of the structure of a wind power generation device with a blade bending resistance in an embodiment of the present invention;

[0049] Figure 10 It is a schematic diagram of the structure of an in-situ gas supply and air replenishment device installed in a blade in an embodiment of the present invention;

[0050] Figure 11 It is a schematic diagram of the structure of an in-situ gas supply and air replenishment device in an embodiment of the present invention.

[0051] Explanation of the reference numerals in the attached drawings:

[0052] 1. Blade; 10. Housing; 11. Elastic cavity; 12. Blade cavity; 120. Sub-cavity; 121. Fourth reaction force curved surface; 13. Protective sleeve; 14a. Tubular longitudinal beam structure; 141a. Tubular longitudinal beam; 142a. First reaction force curved surface; 14b. Frame-shaped longitudinal beam new web structure; 141b. First main beam; 142b. Second main beam; 143b. Curved web; 144b. Second reaction force curved surface; 145b. Third reaction force curved surface;

[0053] 15. Reinforcing rib; 16. Fluid inlet; 171. Inflation device; 172. Slip ring; 173. First connecting pipeline; 18. In-situ gas supply and air replenishment device; 181. Air pump; 182. Air supply pipeline; 183. Outlet pressure and flow transmitter; 184. Controller; 185. Driving motor; 19. Image sensor; C. Adhesive layer; D. Blade and bearing installation connection surface;

[0054] 2. Nacelle; 3. Blade hub; 4. Generator; 5. Fairing; 6. Tower barrel; 7. Wind vane anemometer. Detailed implementation manners

[0055] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0056] As Figure 1 shown, the wind turbine blade 1 includes: a housing 10 and an elastic cavity 11; the elastic cavity 11 is arranged in a blade cavity 12 formed by the housing 10, contacts the inner surface of the housing 10, and extends longitudinally along the inside of the blade cavity 12. A fluid is arranged inside the elastic cavity 11, and the fluid can be a gas or a liquid. The fluid can be pre-filled into the elastic cavity 11 and then sealed, or can be filled during the commissioning work before the wind turbine is installed and starts running. After the blade 1 is feathered, when the blade 1 rotates freely to the position corresponding to three o'clock or nine o'clock on the clock, the blade 1 is in a horizontal cantilever beam state under the action of gravity, the blade 1 bends, and the pressure side and the suction side are respectively subjected to tensile and compressive forces, and the elastic cavity 11 can be relied on to prevent the fracture of the resin dense structure caused by bending or buckling.

[0057] After the wind turbine is enlarged, since the blade 1 becomes longer, it is easy to occur the situation of bending fracture. Therefore, in this embodiment, a lightweight long blade 1 structure is provided with an elastic cavity 11 arranged in the blade cavity 12 to resist the bending fracture instability of the blade 1. This lightweight long blade 1 structure is an innovation in the stress structure of the key load-bearing parts of the internal structure of the traditional blade 1. In this embodiment, the basic principles of thermodynamics are used, so that after the outside of the blade 1 is acted on by air flow and various loads, a new structure greater than the natural environmental air pressure can be pre-established inside the blade cavity 12 to support the inner surface of the blade cavity 12, cooperate with the original inner surface of the cavity of the blade 1 to resist the reaction force curved surface of deformation, absorb the vibration energy of the blade 1, and suppress the stall caused by the bending of the blade 1, especially the reduction of the performance loss in the second half of the blade 1 length.

[0058] In addition, during the manufacturing process of the blade 1 in this embodiment, the skin is wound with multiple layers of glass fiber and then infiltrated and impregnated with epoxy resin. At the same time, with the help of metal winding, it jointly bears the expansion pressure from the inside of the blade housing 10; or metal welding and non-metal melting connection technologies are used to strengthen the connection strength of the housing 10.

[0059] In this embodiment, by providing an elastic cavity 11 within the blade cavity 12 formed by the housing 10, the inner surface of the housing 10 is no longer under the action of atmospheric pressure, or approximately under the action of atmospheric pressure. The inner surface of the blade housing 10 can be supported according to the requirements of rigidity. Since the inner surface has a surface support close to rigidity, the inner surface of the housing 10 will no longer have large-scale reciprocating bending deformations in two directions, especially preventing the outer surface of the housing 10 from bending, denting, or buckling inward towards the inner surface.

[0060] As Figure 2A , Figure 2B , Figures 4 to 8 shown, in some embodiments, the wind turbine blade 1 further includes a protective sleeve 13. The protective sleeve 13 is disposed inside the blade cavity 12 and sleeved outside the elastic cavity 11. Additionally, the shape of the elastic cavity 11 can be cylindrical, elliptical cylindrical, or non-cylindrical. The length of the elastic cavity 11 is less than the length of the blade cavity 12. For example, it can also longitudinally extend from the middle section of the blade 1 to the end of the blade 1. The shape of the protective sleeve 13 matches the shape of the elastic cavity 11. The material of the protective sleeve 13 contains a fiber-reinforced or wire mesh structure. Relying on the inflation of the internal elastic cavity 11 to support it, at this time, the elastic cavity 11 can be used as an inner tube, and the protective sleeve 13 can be used as an outer tube. The outer tube bulges due to the inflation of the inner tube, and the inner tube supports the external protective sleeve 13 to form sufficient anti-bending and resilience, such that the deformation of the blade inner cavity adheres to the outer surface of the rigid rubber protective sleeve 13. In this way, the inner surface of the housing 10 is no longer under the action of atmospheric pressure, or approximately under the action of atmospheric pressure. The inner surface of the blade housing 10 can be supported according to the requirements of rigidity. Since the inner surface has a surface support close to rigidity, the inner surface of the housing 10 will no longer have large-scale reciprocating bending deformations in two directions, especially preventing the outer surface of the housing 10 from bending, denting, or buckling inward towards the inner surface. That is, the protective sleeve 13 bulges after being filled with sufficient gas in the elastic cavity 11, and its rigid surface can resist external forces and generate reaction forces, balancing the pressure difference between the pressure side and the suction side of the blade 1, avoiding the tendency of the blade 1 to bulge or dent. This balance prevents the deformation of the pressure side and the suction side, which is the potential contribution of the pressure energy or potential energy constructed by the gas pre-filled in the elastic cavity 11. It is also the so-called internal reliance that can resist the bending of the blade 1 or a new structure that can resist the bending of the blade 1.

[0061] In this embodiment, by providing the protective sleeve 13, on the one hand, it can prevent the elastic cavity 11 from rubbing against the inner surface of the housing 10 and damaging the elastic cavity 11, thus improving the service life of the elastic cavity 11. Additionally, the material of the elastic cavity 11 itself is an elastic material, and it is also a fireproof material, and it has the function of withstanding the natural environment, accepting temperature changes and humidity changes in the four seasons, and anti-aging. On the other hand, since the material of the protective sleeve 13 can be a ductile rubber material, after the elastic cavity 11 releases the fluid, the elastic cavity 11 can be taken out along the open direction of the root of the blade 1 for replacement or repair.

[0062] As Figure 2A , Figures 2B to 6 shown, in some embodiments, the blade 1 is a beam of the load-bearing structure, and the beam of the load-bearing structure is arranged inside the blade cavity 12 formed by the housing 10 and extends along the longitudinal direction of the blade cavity 12; the elastic cavity 11 is arranged inside the beam of the load-bearing structure and is in contact with the inner surface of the beam of the load-bearing structure. Specifically, in this embodiment, the blade 1 includes a beam of the load-bearing structure, and a streamlined housing 10 structure with a leading edge and a trailing edge formed by a fiberglass skin, a glass fiber epoxy skin, or a wooden thin plate skin. The blade cavity 12 is formed inside the housing 10 structure. The beam of the load-bearing structure extends along the bus of the blade cavity 12, and the elastic cavity 11 is tightly attached to the beam of the load-bearing structure along the longitudinal direction of the beam of the load-bearing structure. Optionally, the elastic cavity 11 accompanies a part or all of the longitudinal length of the beam of the load-bearing structure.

[0063] This embodiment breaks away from the single idea adopted in the traditional blade 1 structure design, so that the stiffness of the beam of the load-bearing structure in the traditional blade 1 is no longer solely borne by the main beam skin, the main beam cap, and the shear web. The beam of the load-bearing structure itself increases toughness, and the beam of the load-bearing structure itself has a new structure that can absorb vibration energy and tremor energy. After the blade 1 is externally affected by the airflow and various loads, the beam of the load-bearing structure itself has a reaction force to resist bending deformation. This reaction force is not the reaction force generated by the traditional beam of the load-bearing structure attempting to recover after deformation, but rather spontaneously increases the reaction force or so-called reliance to prevent the beam from deforming. It is no longer just the transmission of the single interaction force between the beam and the web. In this way, after the blade 1 receives the wind load externally, a reaction force that can spontaneously resist the forced bending of the beam can be generated inside the blade 1, rather than the housing 10 that forms the blade cavity 12 alone resisting bending deformation. Currently, the research and implementation of constructing a new type of beam of the load-bearing structure that can absorb vibration and tremor energy inside the traditional wind turbine blade 1 and can spontaneously generate a reaction force to resist the forced bending of the beam inside the blade 1 have not been carried out.

[0064] As Figure 2A and Figure 2BAs shown, in some embodiments, the beam of the bearing structure is a tubular longitudinal beam structure 14a, and the tubular longitudinal beam structure 14a is a structure in which the tubular longitudinal beam 141a forms an annular cavity, and the cross section of the annular cavity is a curved surface. The elastic cavity 11 is arranged in the annular cavity, and after the elastic cavity 11 expands, it contacts the tubular longitudinal beam 141a and the shell 10 there, and generates a first reaction force curved surface 142a that resists bending on the curved cross section of the annular cavity and the inner surface of the shell 10. Specifically, the inner surface of the cavity along the length direction of the blade 1 (i.e., the longitudinal direction of the tubular longitudinal beam) of the annular cavity formed by the tubular longitudinal beam 141a is a curved surface, and after the elastic cavity 11 expands, the force exerted on the annular inner cavity of the tubular longitudinal beam 141a is vertically distributed and acts on the inner surface of the (compressive stress) beam, so the outer surface of the elastic cavity 11 will make corresponding adaptive changes to the expansion pressure generated by it with the surface shape of the beam or shell in contact with it, and the direction of the interaction force will also change with the shape of the contact surface.

[0065] In this embodiment, when the inflation pressure is greater than the natural environment pressure, the elastic cavity 11 props up its external protective cover 13 to form sufficient bending strength and resilience, so that the deformation of the blade cavity 12 depends closely on the outer surface of the rubber protective cover 13 attached to the blade 1 with toughness and certain rigidity; the inner surface of the beam of the bearing structure of the blade 1 or the inner surface of the blade cavity 12 can be supported according to the rigidity requirements. Since the inner surface of the annular cavity has a nearly rigid curved surface support, the beam of the bearing structure and the inner surface of the blade shell 10 will no longer have a large reciprocating bending deformation in two directions, preventing the outer surface of the shell 10 from bending, concave or buckling to the inner surface. Since the pressure difference between the pressure surface or the suction surface of the blade 1 may cause the blade to bulge or sag, a force will be generated on the elastic cavity 11 and the protective cover 13. By supporting the protective cover 13 through the elastic cavity 11, the protective cover 13 can have a rigid surface, which can generate a reaction force on the blade 1. This reaction force can balance the previous force and prevent the blade 1 from bending and deforming due to the pressure difference between the pressure surface or the suction surface. That is, after the elastic cavity 11 expands, the curved cross-section of the annular cavity formed by the tubular longitudinal beam 141a generates a first reaction force curved surface 142a that resists bending. The first reaction force curved surface 142a can balance the force acting on the protective cover 13. Such balance can prevent the blade 1 from bending and deforming due to the pressure difference between the pressure surface or the suction surface. This is a potential contribution of the elastic potential energy formed by the pressure energy created by the gas pre-filled in the elastic cavity 11, and is also the reliance of the beam of the load-bearing structure or the blade shell 10 in this embodiment to resist bending. Figure 3It is a schematic diagram of an external force load on a blade along the length direction at a certain transient state in an embodiment of the present invention. As can be seen from the coordinate system, starting from the second half of the longitudinal section of the blade 1, the external force load gradually increases. The physical position when it reaches a relatively large value is several meters or more than ten meters at the end section of the length direction of the blade 1. And this section accounts for more than half of the weight of the circumferential power output of the wind turbine. Bending leads to stall, that is, the conversion and transmission of the kinetic energy carried by the wind speed are discounted or even invalid. In this embodiment, the elastic cavity 11 and its essential protective sleeve 13 that increase the stiffness run through from the root of the blade 1 along the length direction of the blade to the end, just balancing the external force load and preventing the blade 1 from bending.

[0066] As Figure 4 and Figure 5 shown, in some embodiments, since the traditional "I-beam" web structure cannot meet the design requirements, for large megawatt-class and large chord-length wind turbine blades 1, the structural safety risk will increase significantly. The traditional I-beam web structure cannot meet the design requirements, especially in the area near the maximum chord length of the blade 1. The blade 1 is prone to frequent structural problems under complex wind conditions. Especially under the action of wind load, problems such as blade 1 buckling and trailing edge structural damage often occur in the trailing edge area of the blade 1. Therefore, in this embodiment, the beam of the load-bearing structure is a new web structure 14b of a frame-shaped longitudinal beam; the new web structure 14b of the frame-shaped longitudinal beam includes a pair of upper and lower first main beams 141b and second main beams 142b, and two curved webs 143b arranged between the first main beam 141b and the second main beam 142b. The two curved webs 143b are respectively located on both sides of the first main beam 141b and the second main beam 142b. A frame-shaped cavity is formed between the first main beam 141b, the second main beam 142b and the two curved webs 143b. The concave surface of the curved web 143b faces the frame-shaped cavity. The elastic cavity 11 is located in the frame-shaped cavity, extends longitudinally along the frame-shaped cavity, and is in contact with the frame-shaped cavity; when the elastic cavity 11 expands in the frame-shaped cavity, a second reaction force surface 144b that resists bending is generated on the curved web 143b, and a third reaction force surface 145b that resists bending is generated on the first main beam 141b and the second main beam 142b.

[0067] In this embodiment, the curved web 143b bends relative to the middle elastic cavity 11, that is, the curved web 143b is concave towards the elastic cavity 11. After the elastic cavity 11 is inflated to build up sufficient pressure and expand, it presses the curved web 143b to deform towards the straight direction. In this way, it can not only give the curved web 143b a supporting reaction force for the main beam to transfer and support, but also provide a second reaction force surface for the curved web 143b to resist the bending of the blade 1. Through the second reaction force surface, the collapse of the main beam and the collapse of the blade housing 10 under the pressure difference between the pressure surface and the suction surface can be avoided, and the airfoil becomes thinner and bends and deforms. In addition, by the curved web 143b preventing and restricting the further expansion of the elastic cavity 11 towards both sides close to the curved web 143b, two curved surfaces of the elastic cavity 11 facing the main beam can be constructed to resist the bending of the main beam, namely the third reaction force surface 144b. Specifically, the interaction force between the elastic cavity 11 and the pre-bent web is the same. As the curvature of the web changes, the force exerted on the (supporting) web surface after the elastic cavity 11 expands is also field-distributed, which can also be called the acting force surface, that is, the direction of the acting force generated by this acting force surface changes adaptively, and this adaptive change is related to the contact condition.

[0068] In this embodiment, the curved web 143b, the main beam and the elastic cavity 11 support, restrict and rely on each other, constructing a new blade 1 structure with a reaction force surface inside the blade 1 of this embodiment that can resist the bending of the blade 1.

[0069] Such as Figure 6As shown, in some embodiments, one or more elastic cavities 11 are provided at the trailing edge of the blade cavity 12, and the elastic cavity 11 is connected to the inner surface of the housing 10 through the adhesive layer C. Optionally, the shape of the elastic cavity 11 provided at the trailing edge can match the shape of the blade cavity 12 at that place, so that the original cavity of the blade 1 also has the fourth reaction force surface 121 that resists the deformation of the trailing edge cavity. In this embodiment, one or more elastic cavities 11 are provided at the trailing edge of the blade cavity 12. The elastic cavity 11 may or may not be provided with a protective sleeve 13. At this time, the inner surface of the blade housing 10 is no longer under the action of an atmospheric pressure or approximately under the action of an atmospheric pressure. The structures of the elastic cavity 11 and the protective sleeve 13 can support the inner surface of the blade housing 10 according to the requirement of rigidity. Since the inner surface has a surface support close to rigidity, the inner surface of the housing 10 will no longer have large-scale reciprocating bending deformations in two directions, preventing the outer surface of the housing 10 from bending, denting or buckling inward. That is, when the elastic cavity 11 generates the fourth reaction force surface 121 that resists the bending of the trailing edge cavity of the housing 10, the pressure difference between the pressure surface and the suction surface of the blade 1 can be balanced through the fourth reaction force surface 121, avoiding the tendency of the blade 1 to bulge or dent. This balance prevents the deformation of the pressure surface and the suction surface, which is the potential contribution of the pressure energy or potential energy constructed by the pre-sufficient gas in the elastic cavity 11. It is also the so-called internal reliance that can resist the bending of the blade 1 or a new structure that can resist the bending of the blade 1.

[0070] As Figure 7 and Figure 8As shown, in some embodiments, when the blade 1 is an equal-chord extrusion-formed blade 1 made of aluminum alloy, the blade 1 further includes a plurality of reinforcing ribs 15; the plurality of reinforcing ribs 15 are arranged inside the blade cavity 12 parallel to the center line of the blade 1 and are connected to the housing 10. The plurality of reinforcing ribs 15 and the housing 10 divide the blade cavity 12 into a plurality of sub-cavities 120, and the elastic cavity 11 is arranged inside the sub-cavity 120; the shape of the elastic cavity 11 matches the shape of the sub-cavity 120 formed by the reinforcing ribs 15 and the blade housing 10. In this embodiment, the shape of the elastic cavity 11 arranged in one or more sub-cavities 120 can match the shape of the sub-cavity 120 at that place, generating a reaction force surface in each sub-cavity 120 to resist the deformation of the outer shell. In this embodiment, in one or more sub-cavities 120, the elastic cavity 11 may or may not be provided with a protective sleeve 13. At this time, the inner surface of the blade housing 10 is no longer under the action of an atmospheric pressure or approximately under the action of an atmospheric pressure. The structures of the elastic cavity 11 and the protective sleeve 13 can support the inner surface of the blade housing 10 according to the requirement of rigidity. Due to the support of a nearly rigid surface on the inner surface, there will no longer be large-amplitude reciprocating bending deformations in two directions on the inner surface of the housing 10, especially preventing the outer surface of the housing 10 from bending, denting, or buckling inward. Since the pressure difference between the pressure surface and the suction surface of the housing 10 corresponding to the sub-cavity 120 of the blade 1 may cause the blade to bulge or dent, at this time, a force will be generated on the elastic cavity 11 and the protective sleeve 13. By supporting the protective sleeve 13 through the elastic cavity 11, a rigid surface can be provided, generating a reaction force on the blade 1. This reaction force can balance the previous force, preventing the blade 1 from bending and deforming due to the pressure difference between the pressure surface and the suction surface. That is, when the elastic cavity 11 generates a reaction force surface that bends the housing 10 corresponding to the sub-cavity 120, the pressure difference between the pressure surface and the suction surface of the blade 1 can be balanced through the reaction force surface, avoiding the tendency of the blade 1 to bulge or dent. This balance prevents the deformation of the pressure surface and the suction surface, which is the potential contribution of the pressure energy or potential energy built by the pre-filled gas in the cavity. It is also the so-called internal reliance that can resist the bending of the blade 1 or a new structure that can resist the bending of the blade 1.

[0071] As Figure 9As shown, in some embodiments, a fluid inlet 16 and an automatic pressure relief and discharge valve (not shown in the figure) are provided on the elastic cavity 11. Fluid is filled into the elastic cavity 11 through the fluid inlet 16, and the fluid in the elastic cavity 11 can be discharged through the automatic pressure relief and discharge valve, so that the elastic cavity 11 can be taken out for maintenance or replacement; when the fluid is a gas, the gas source fills the elastic cavity 11 with gas through the fluid inlet 16, and the gas source is an air pump, an air compressor, an automatic air replenishment and supply system or a local air replenishment and supply device. In this embodiment, the elastic cavity 11 itself contains the gas fluid inlet 16, and gas can be supplemented into the elastic cavity 11 through the fluid inlet 16; an automatic exhaust valve can also be provided to prevent the elastic cavity 11 from being damaged after the inflation and air replenishment device gets out of control. When the fluid is a liquid, the liquid can be filled into the elastic cavity 11 before use. In addition, according to the actual situation, the elastic cavity 11 can be made to have a certain pressure; in addition, when the blade 1 is under maintenance or the wind turbine needs to be shut down for a long time, the liquid in the elastic cavity 11 flows out through the automatic pressure relief and discharge valve. After the fluid in the elastic cavity 11 is released, the elastic cavity 11 can be taken out along the open direction of the root of the blade 1 for replacement or repair.

[0072] As Figure 9 shown, Figure 9 The figure shows a schematic structural diagram of a wind power generation device with resistance to blade bending. The wind power generation device includes: a blade 1, a nacelle 2, a hub 3, a generator 4, a fairing 5, a tower 6 with a tower door, a wind vane anemometer 7, etc. In this embodiment, the gas source adopts an automatic air replenishment and supply system, and the automatic air replenishment and supply system includes: an inflation device 171, a slip ring 172, a first connecting pipeline 173, a second connecting pipeline 174, a pressure value display or transmission device (not shown in the figure); the inflation device 171 is arranged in the nacelle 2 of the wind turbine, the inflation device 171 is connected to the slip ring 172 installed on the hub 3 through the first connecting pipeline 173, the slip ring 172 is connected to the fluid inlet 16 of the elastic cavity 11 through the second connecting pipeline 174, and the pressure value display or transmission device is installed on the elastic cavity 11 for locally displaying or transmitting the pressure value or sensor signal in the elastic cavity 11; the inflation device 171 inflates or replenishes air to the elastic cavity 11 according to the pressure value or sensor information. Among them, the pressure value display or transmission device (not shown in the figure) can be a pressure and flow transmitter, an electrical slip ring or a pressure gauge installed on the elastic cavity 11 to transmit or locally display the pressure value in the elastic cavity 11; or it can be a pressure wireless sensor to transmit the pressure sensor signal in the elastic cavity 11.

[0073] In this embodiment, a gas slip ring 172 is designed inside the hub 3. The gas slip ring 172 has a structure of one-way air intake and three-way air outlet. The three-way air outlet supplies air to three elastic cavities 11 inside the three blades respectively. Of course, when the fluid in the elastic cavity 11 is liquid, the liquid source is a liquid supply and replenishment controller. At this time, the slip ring 172 is a liquid slip ring, and the liquid supply and replenishment controller is arranged on the operation control platform inside the tower door at the bottom of the tower barrel 6.

[0074] In some embodiments, a Hall piezoelectric sensor, a strain type pressure transmitter or a polyvinylidene fluoride film is arranged on the blade 1. The blade bending signal is measured by the Hall piezoelectric sensor, the strain type pressure transmitter or the polyvinylidene fluoride film, and the blade bending signal is transmitted to the inflation device 171 inside the nacelle. The inflation device 171 automatically replenishes air into the elastic cavity 11 according to the natural environment temperature of the wind farm and the blade bending signal. Among them, the polyvinylidene fluoride film is abbreviated as PVDF or PVF2, which is a kind of piezoelectric or pyroelectric polymer functional material. The PVDF piezoelectric film is widely used due to its advantages such as good flexibility, high strength, resistance to mechanical impact, corrosion resistance and arbitrary segmentation. Especially, its piezoelectric voltage constant is high, and after being combined with the matrix, it has little influence on the performance of the structure. It has an extremely fast response to the change of mechanical stress or strain, and has a wide frequency response range (0.1 Hz to several GHz). Therefore, it is more suitable to be used as a sensing element. PVDF measures strain by using the principle that the lateral deformation of the PVDF film outputs charge. Since the capacitance of the PVDF piezoelectric film is small, the charge generated when it is acted on by an external force is difficult to maintain for a long time. Therefore, it is more suitable for the dynamic monitoring of the structure. Functionally, when the piezoelectric film is used as a sensing element, it is a charge generator, so it can be equivalent to a charge source; from the composition and geometric structure of the PVDF piezoelectric sensing element, it is also a capacitor. The PVDF piezoelectric film unit is arranged in series between the main beam of the blade and the skin of the blade, or between the trailing edge shells of the blade. If the piezoelectric films at different positions are connected in series, the output can be increased. The diaphragm type pressure sensor composed of it and the fiber cladding of the blade shell form a sensitive element structure, which can reflect the defects of the deformation and even peeling between the main beam and the shell.

[0075] Such as Figure 10 and Figure 11As shown, in some embodiments, the in-situ gas supply and replenishment device 18 is arranged at the open position of the blade root, that is, the blade and bearing installation connection surface D; the in-situ gas supply and replenishment device includes: an air pump 181, a gas supply pipeline 182, an outlet pressure and flow transmitter 183, a controller 184, and a drive motor 185; the outlet pressure and flow transmitter 183 feeds back the outlet pressure and flow to the controller 184, and the controller 184 inputs a control signal to the drive motor 185. The drive motor 185 controls the air pump 181 to supply and replenish gas to the elastic cavity 11 in-situ through the gas supply pipeline 182. Specifically, the controller 184 inputs a control signal to the drive motor 185 to control the start, stop, motor speed, and continuous working time length of the drive motor 185.

[0076] In this embodiment, the in-situ gas supply and replenishment device 18 can be installed in-situ at the open mouth of the blade 1 root and rotate with the blade 1. In this embodiment, there is no need to set up a slip ring, nor is it necessary to be arranged inside the nacelle 2; or it is not necessary to form an automated system, and only a temporary inflation air pump and pressure gauge are required at the blade opening, and the operation is simple.

[0077] In some embodiments, an image sensor 19 and a vibration sensor (not shown in the figure) are arranged on the blade and are electrically connected to the gas source respectively; the image sensor 19 is used to observe the bending amplitude and bending direction of the blade 1 of the wind turbine in real time and feed back the observation signal to the controller of the gas source. The vibration sensor is used to monitor the vibration signal of the blade in real time and feed back the vibration signal to the controller of the gas source. The controller of the gas source is used to calculate the inflation amount in real time according to the fed-back vibration signal to adjust the volume of the fluid in the elastic cavity 11 in real time.

[0078] In this embodiment, the bending amplitude and bending direction of the blade 1 of the wind turbine are observed in real time through the image sensor 19; a vibration sensor is also arranged to monitor the blade vibration, and the vibration signal is fed back to the controller of the gas supply and replenishment device. The controller of the gas supply and replenishment device starts the gas replenishment program according to the fed-back vibration signal to increase the blade stiffness and suppress the blade flapping vibration.

[0079] In the embodiment of the present invention, by providing an elastic cavity 11 inside the blade housing 10, the inner surface of the blade housing 10 is no longer under the action of an atmospheric pressure, or approximately under the action of an atmospheric pressure. The inner surface of the blade housing can be supported according to the requirement of rigidity. Since the inner surface has a surface support close to rigidity, there will no longer be large-scale reciprocating bending deformation in two directions on the inner surface of the housing 10, especially preventing the outer surface of the housing 10 from bending, denting or buckling inward. The protective sleeve 13 bulges after relying on the sufficient gas in the elastic cavity 11 and its rigid surface can resist the external force and generate a reaction force, balancing the pressure difference between the pressure surface and the suction surface of the blade 1, avoiding the tendency of the blade 1 to bulge or dent. That is, this balance prevents the deformation of the pressure surface and the suction surface. This is the potential contribution of the pressure energy or potential energy constructed by the sufficient gas pre-filled in the elastic cavity 11. It is also the so-called internal reliance for resisting blade bending or a new structure capable of resisting blade bending.

[0080] Since the blade 1 adopted in the wind power generation device in this embodiment has the function of resisting bending, the service life of the wind power generation device can be improved.

[0081] As mentioned above, the above are only specific embodiments of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present disclosure should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A wind turbine blade having a structure for resisting blade bending, characterized in that: The blade (1) comprises: a shell (10) and an elastic cavity (11); The elastic cavity (11) is arranged in a blade cavity (12) formed by the shell (10); after expansion, the elastic cavity (11) contacts the inner surface of the shell (10) and extends longitudinally along the length direction of the blade cavity (12); The blade (1) also includes a beam of a load-bearing structure; The beam of the bearing structure is arranged inside a blade cavity (12) formed by the shell (10), and extends in the longitudinal direction of the blade cavity (12); The elastic cavity (11) is arranged inside the beam of the bearing structure and contacts the inner surface of the beam of the bearing structure; The beam of the bearing structure is a frame-shaped longitudinal beam new web structure (14b); the frame-shaped longitudinal beam new web structure (14b) comprises: a first main beam (141b) and a second main beam (142b) arranged in pairs up and down, and two curved webs (143b) arranged between the first main beam (141b) and the second main beam (142b); a frame-shaped cavity is formed between the first main beam (141b), the second main beam (142b) and the two curved webs (143b); and the curved surface of the curved web (143b) is concave toward the frame-shaped cavity; When the elastic cavity (11) expands, a second reaction force curved surface (144b) is generated for the curved web (143b) to resist bending, and a third reaction force curved surface (145b) is generated for the first main beam (141b) and the second main beam (142b) to resist bending; The blade (1) further comprises a protective cover (13), wherein the protective cover (13) is arranged inside the blade (1) and outside the elastic cavity (11); The blade (1) further comprises a plurality of reinforcing ribs (15); the plurality of reinforcing ribs (15) are arranged inside the blade cavity (12) in parallel with the center line of the blade and are connected to the shell (10); the plurality of reinforcing ribs (15) and the shell (10) divide the blade cavity (12) into a plurality of sub-cavities (120); the elastic cavity (11) is arranged inside the sub-cavity (120); the shape of the elastic cavity (11) matches the shape of the sub-cavity (120); An image sensor (19) and a vibration sensor are provided on the blade (1), and the image sensor and the vibration sensor are electrically connected to the controller of the air source respectively; the image sensor (19) is used to observe the bending amplitude and bending direction of the wind turbine blade (1) in real time, and transmit the real-time observation signal to the controller of the air source; The vibration sensor is used to monitor the vibration signal of the blade in real time, and transmit the vibration signal to the controller of the air source; the controller of the air source is used to control the air source to inflate the elastic cavity (11).

2. The wind turbine blade according to claim 1, characterized in that: The initial shape of the elastic cavity (11) is cylindrical, elliptical or non-cylindrical, the length of the elastic cavity (11) is less than or equal to the length of the blade cavity (12), and the shape of the protective cover (13) matches the shape of the blade cavity (12) at the position where the protective cover (13) is located.

3. The wind turbine blade according to claim 1, characterized in that: The beam of the bearing structure is a tubular longitudinal beam structure (14a), the tubular longitudinal beam structure (14a) is an annular cavity formed by the tubular longitudinal beam (141a), and the elastic cavity (11) is arranged in the annular cavity; after the elastic cavity (11) expands, it generates a first reaction force curved surface (142a) on the tubular longitudinal beam (141a) to resist bending of the tubular longitudinal beam (141a).

4. The wind turbine blade according to claim 1 or 2, characterized in that: One or more elastic cavities (11) are provided at the rear edge of the blade cavity (12), and the elastic cavity (11) is connected to the inner surface of the shell (10) via an adhesive layer (C).

5. The wind turbine blade according to claim 1, characterized in that: The elastic cavity (11) is provided with a fluid filling inlet (16) and an automatic pressure relief valve for filling the elastic cavity (11) with fluid, wherein the fluid includes gas or liquid; when the fluid is gas, the gas source is an automatic gas supply system or an on-site gas supply device; when the fluid is liquid, the liquid source is a liquid supply controller.

6. The wind turbine blade according to claim 5, characterized in that: The automatic air supply system comprises: an air charging device (171), a slip ring (172), a first connecting pipeline (173), a second connecting pipeline (174) and a pressure value display or transmission device; The inflation device (171) is arranged in a nacelle (2) of a wind turbine, the inflation device (171) is connected to a slip ring (172) mounted on a blade hub (3) via the first connecting pipeline (173), the slip ring (172) is connected to a fluid filling inlet (16) of the elastic cavity (11) via the second connecting pipeline (174), and the pressure value display or transmission device is mounted on the elastic cavity (11) and is used to locally display or transmit a pressure value or a sensor signal in the elastic cavity (11); The inflation device (171) is used to inflate or replenish air to the elastic cavity (11) according to the pressure value or the sensor signal.

7. The wind turbine blade according to claim 5, characterized in that: A Hall piezoelectric sensor, a strain gauge pressure transmitter or a polyvinylidene fluoride film is provided on the blade (1) for transmitting a bending signal of the blade (1) to an air supply and replenishment device in the cabin, wherein the air supply and replenishment device is used to automatically replenish air into the elastic cavity (11) according to the natural ambient temperature of the wind farm and the bending signal of the blade (1).

8. The wind turbine blade according to claim 5, characterized in that: The local air supply and replenishment device (18) is arranged at an open position at the root of the blade; the local air supply and replenishment device (18) comprises: an air pump (181), an air supply pipeline (182), an outlet pressure flow transmitter (183), a controller (184) and a drive motor (185); The outlet pressure flow transmitter (183) is used to feed back the outlet pressure flow to the controller (184); the controller (184) is used to input a control signal to the drive motor (185); the drive motor (185) is used to control the air pump (181) to locally supply air to the elastic cavity (11) through the air supply pipeline (182) according to the input control signal.

9. A wind power generation device with the ability to resist blade bending, characterized in that: The wind power generation device comprises the wind turbine blade according to any one of claims 1-8.

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