Blade and wind turbine generator set

Abstract

The present disclosure provides a blade and a wind turbine generator set. The blade includes: a blade shell having a leading edge and a trailing edge oppositely arranged in the chord direction of the blade; a main beam integrated in the blade shell; a web located inside the blade shell and connected to the main beam; wherein, the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section. According to an embodiment of the present disclosure, by adjusting the shear center of the blade to be located on the leading edge side of the aerodynamic center, an additional torsional moment that causes the blade to pitch down is generated by the aerodynamic force, so that the angle of attack of the blade is reduced, and further the load received by the blade is reduced, thereby having the ability of adaptive passive load reduction.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of wind power generation, and particularly relates to a blade for a wind turbine and a wind turbine having the blade. Background Art

[0002] During the operation of a wind turbine, active pitch control is mainly used to reduce the loads on the blade and the nacelle under certain wind conditions. When the wind conditions change, the torque of the unit also changes correspondingly. According to the corresponding relationship between torque and pitch angle in the main control program, the unit adjusts the pitch angle of the blade through pitch action, thereby affecting the operating angle of attack of the blade section, changing the lift of the airfoil, and affecting the loads on the blade and the unit.

[0003] For the blade to actively control pitch, the control system first needs to identify based on the current wind conditions, identify the corresponding pitch angle through the torque change of the blade, and then perform pitch control. This process takes a certain amount of time and depends on the accuracy of the control program; in addition, it also takes a certain amount of time for the angle of attack of the airfoil to change from the root of the blade to the middle and tip of the blade. Especially for large, long and flexible blades, the time for the angle change to be transmitted is longer and the control difficulty is higher. During the time of control identification and angle of attack change, the response of the control strategy is always lagging, and the blade and the unit actually bear relatively large loads, which are prone to ultimate failure or significant fatigue cumulative damage, affecting the safety of the blade and the unit operation. In addition, for some special working conditions, such as shutdown or pitch failure conditions, at this time the pitch system no longer has the ability to pitch. Under special wind conditions (such as extreme winds that occur once in several decades at a specific incoming flow angle), the blade and the unit can only passively bear relatively large loads and cannot make control responses. Summary of the Invention

[0004] The purpose of the present disclosure is to provide a blade with an adaptive passive load reduction ability and a wind turbine having the blade. According to the embodiments of the present disclosure, the shear center of the blade is adjusted to be biased towards the leading edge of the blade, on the leading edge side of the aerodynamic center, so that the aerodynamic force additionally generates a torsional moment that causes the blade to lower its head, reducing the angle of attack, and thus reducing the load on the blade, achieving an adaptive passive load reduction function.

[0005] According to one aspect of the present application, there is provided a blade for a wind turbine, the blade comprising: a blade shell having a leading edge and a trailing edge oppositely disposed in the chord direction of the blade; a main beam integrated in the blade shell; a web located inside the blade shell and connected to the main beam; wherein, the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section.

[0006] According to one aspect of the present application, the distance between the shear center and the aerodynamic center is 1% - 8% of the chord length.

[0007] According to one aspect of the present application, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section, and the range of X% is 50%-80%.

[0008] According to one aspect of the present application, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, the center of the main beam is offset towards the leading edge side of the blade, so that the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section.

[0009] According to one aspect of the present application, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, within the airfoil section of the blade, starting from the leading edge side of the blade, the shear center is located within the range of 18%-25% of the chord length of the blade.

[0010] According to one aspect of the present application, within the range from the blade root to X% of the blade length, within the airfoil section of the blade, the shear center of the blade is located on the trailing edge side of the aerodynamic center.

[0011] According to one aspect of the present application, within the range of Y%-100% of the blade length in the direction from the blade root to the blade tip, the trailing edge side of the main beam gradually inclines towards the leading edge side of the main beam, so that the width of the main beam gradually becomes narrower in the direction towards the blade tip, so that the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section, where Y% is greater than X%.

[0012] According to one aspect of the present application, the range of Y% is 70%-90%.

[0013] According to one aspect of the present application, the width of the end of the main beam towards the blade tip is at least 80% of the width of the end of the main beam towards the blade root.

[0014] According to one aspect of the present application, within the range of Z%-100% of the blade length in the direction from the blade root to the blade tip, the airfoil section of the blade is offset towards the trailing edge side relative to the airfoil section located on its blade root side, so that the aerodynamic center of the airfoil section is located on the trailing edge side of the pitch center axis of the blade, and the range of Z% is 40%-80%.

[0015] According to one aspect of the present application, the distance by which the blade tip is offset towards the trailing edge direction relative to the pitch center axis of the blade is less than 1.5% of the blade length.

[0016] According to one aspect of the present application, within the range from the blade root to Z% of the blade length, the aerodynamic center of the airfoil section of the blade is located on the leading edge side of the pitch center axis of the blade.

[0017] According to one aspect of the present application, in the root region, the aerodynamic center of the airfoil is located on the leading edge side of the pitch center, thereby forming a forward sweep in the root region. In the tip portion, the aerodynamic center of the airfoil is located on the trailing edge side of the pitch center, thereby forming a backward sweep in the tip region. The maximum forward sweep amount in the root region of the blade is 10% of the maximum backward sweep amount in the tip region.

[0018] According to another aspect of the present application, there is provided a wind turbine generator set, which includes the blade as described above. Description of the Drawings

[0019] Through the description of the embodiments in conjunction with the drawings below, the above and / or other objects and advantages of the present disclosure will become clearer, where:

[0020] Figure 1 is a schematic diagram of the relative positions of the shear center and the aerodynamic center of the blade cross-section according to an embodiment of the present invention;

[0021] Figure 2 is a distribution diagram of the relative positions of the shear center and the aerodynamic center of the blade in the blade length direction according to an embodiment of the present invention;

[0022] Figure 3 is a schematic structural diagram of the blade main beam according to another embodiment of the present invention;

[0023] Figure 4 shows the relationship between the lift and the angle of attack in the airfoil cross-section of the blade;

[0024] Figure 5 is a schematic diagram of the relative positions of the pitch center and the aerodynamic center of the blade according to another embodiment of the present invention;

[0025] Figure 6 is a distribution diagram of the relative positions of the pitch center and the aerodynamic center of the blade in the blade length direction according to another embodiment of the present invention. Detailed Embodiments

[0026] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the embodiments of the present disclosure should not be construed as being limited to the embodiments set forth herein. Identical reference numerals in the figures denote identical or similar structures, and thus their detailed description will be omitted.

[0027] According to an embodiment of the present application, there is provided a blade with an adaptive passive load reduction ability. As Figure 1As shown, the blade according to an embodiment of the present application includes a blade housing 100 and a main beam 200 integrated with the blade housing 100. The blade housing 100 includes a pressure surface housing 110 and a suction surface housing 120. The pressure surface housing 110 and the suction surface housing 120 can be cured and molded separately and then bonded together by clamping to form the blade housing 100. The leading edge and the trailing edge of the blade housing 100 are respectively located on both sides of the blade chord direction. When air flows in from the leading edge side and passes through the blade airfoil, a negative pressure is formed on the suction surface 120 of the airfoil, and a positive pressure is formed on the pressure surface 110. The pressure difference between the two surfaces generates the blade lift, thereby driving the impeller to rotate. The impeller drives the generator rotor to rotate relative to the stator, thereby converting wind energy into electrical energy.

[0028] The main beam 200 may include a first main beam cap 210 and a second main beam cap 220 arranged oppositely. The first main beam cap 210 and the second main beam cap 220 can be integrally formed with the pressure surface housing 110 and the suction surface housing 120 respectively during the process of casting and molding the blade housing 100. In addition, the blade may further include a web (not shown) located inside the blade housing 100. Both sides in the width direction of the web are respectively connected to the first main beam cap 210 and the second main beam cap 220 to ensure the overall stiffness of the blade.

[0029] According to an embodiment of the present application, the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section.

[0030] According to one aspect of the embodiment of the present application, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, the shear center A of the airfoil section of the blade is located on the leading edge side of the aerodynamic center B of the airfoil section, where the range of X% is 50%-90%. More specifically, the range of X% is 50%-80% or 60%-80%, which is determined according to specific blade design requirements.

[0031] According to an embodiment of the present application, the position of the shear center A of the blade airfoil section can be adjusted by adjusting the position of the center of the main beam 200 in the blade chord direction. Specifically, in the direction from the blade root to the blade tip (spanwise), starting from the position of X% of the blade length, the center of the main beam 200 is gradually inclined towards the leading edge side, so that the shear center A of the blade airfoil section gradually moves away from the aerodynamic center B of the blade. Figure 1 Shows the relative positions of the shear center A and the aerodynamic center B of the blade section. Figure 2 Shows the distribution diagram of the relative positions of the shear center A and the aerodynamic center B of the blade in the blade length direction according to an embodiment of the present invention.

[0032] As Figure 1As shown, it is assumed that the lower half shell of the blade housing is the pressure surface housing 110 and the upper half shell is the suction surface housing 120. The direction of the aerodynamic force F acting on the blade in the direction of the oncoming external wind (V) is upward, and the angle of attack of the blade is α.

[0033] As Figure 1 shown, by making the center of the main beam 200 deviate towards the leading edge side of the blade, the shear center A of the blade is located on the leading edge side of the aerodynamic center B. As an example, the positions of the aerodynamic center and the shear center of the airfoil section differ by 1% - 8% of the chord length. In the length direction of the blade from the root to the tip, the distance between the shear center and the aerodynamic center gradually increases.

[0034] Since a moment arm is formed between the aerodynamic center B and the shear center A, while the aerodynamic force F provides lift for the blade, it can also generate an additional torsional moment M that causes the blade to pitch down relative to the shear center. Under the action of the torsional moment M, the blade twists in the counterclockwise direction. After the cross-section twists, the angle of attack α decreases, resulting in a decrease in the lift of the blade, and further reducing the load borne by the blade.

[0035] According to the embodiments of the present application, the center of the main beam 200 can be offset towards the leading edge side throughout the blade span. However, the aerodynamic output region of the blade is mainly the region from the maximum chord length of the blade to the tip region. Therefore, according to the embodiments of the present invention, the position of the shear center of the cross-section from the middle to the tip of the blade can be adjusted only to achieve the purpose of reducing the load. Usually, when the maximum thickness of the airfoil section is near 30% of the blade chord length (in the direction from the leading edge to the trailing edge of the blade), the flapping stiffness of the blade is the highest under the same material. Therefore, in the region mainly providing the flapping stiffness of the blade, the position of the main beam 200 can be designed conventionally. In the middle to tip region of the blade, the position of the main beam 200 is offset towards the leading edge side to achieve the forward movement of the shear center position. According to the embodiments of the present invention, for example, within the range of X% of the blade length from the root, the shear center A of the blade in the airfoil section of the blade is located on the trailing edge side of the aerodynamic center B. Starting from the X% position of the blade length in the direction from the root to the tip of the blade, the center of the main beam 200 is gradually offset towards the leading edge direction. The range of X% can be 40% - 90%, and further, the range of X% can be 40% - 80% or 50% - 80%. In addition, in order to avoid causing a greater adverse impact on the blade clearance, within the range from X% to 100% in the blade length direction, the position of the shear center of the blade airfoil section is controlled within the range of 18% - 25% of the blade chord length.

[0036] According to the conventional design, the aerodynamic center of the blade airfoil is usually located near 25% of the airfoil chord, the shear center A usually coincides with the aerodynamic center B, and the center of the main beam 200 is usually located at the 30% position of the airfoil chord. According to the embodiments of the present application, the airfoil can be designed based on the blade, and the center of the main beam 200 can be moved towards the leading edge side, for example, located at 27%-30% of the airfoil chord length, and the shear center of the airfoil section can be adjusted to be located on the leading edge side of the aerodynamic center, for example, within the range of 18%-25% of the airfoil chord length.

[0037] According to the embodiments of the present invention, when the wind condition of the blade changes and the torque of the unit exceeds the safe operating range, as the lift of the blade increases, a torque that causes the blade to pitch down can be additionally generated relative to the shear center, so that the angle of attack of the blade is reduced, and the corresponding torque received by the blade is reduced, thereby suppressing the sharp increase in torque and realizing the adaptive passive load reduction of the blade.

[0038] Figure 3 FIG. is a schematic structural diagram of a blade according to another embodiment of the present invention. According to another embodiment of the present invention, the center of the main beam 200 can also be offset towards the leading edge side by making the main beam 200 narrower on the trailing edge side of the blade, thereby realizing the forward movement of the airfoil shear center. Specifically, near the tip of the blade, the leading edge side of the main beam 200 is kept in a straight extension state, while the trailing edge side of the main beam 200 gradually inclines towards the leading edge side of the main beam 200, so that the width of the main beam 200 gradually becomes smaller in the direction towards the tip.

[0039] Specifically, starting from the Y% position in the longitudinal direction of the blade, the trailing edge side of the main beam 200 gradually inclines towards the leading edge side, so that the width of the main beam 200 gradually decreases, where Y% is less than X%, for example, the range of Y% is 70%-90%. In order to avoid bringing too many adverse effects on the blade stiffness, the narrowed part of the main beam 200 is less than 20% of the width of the main beam 200. More specifically, the width of the end of the main beam 200 towards the tip direction is at least 80% of the width of the end of the main beam 200 towards the root.

[0040] Normally, the width of the main beam 200 in the span direction of the blade remains unchanged. In order to narrow the rear end of the main beam 200, different measures can be taken according to the manufacturing process of the main beam. In the case where the main beam 200 of the blade is formed by vacuum infusion, a portion of the fabric ply at the rear end of the main beam 200 can be cut off starting from the position Y% in the span direction to gradually narrow the width of the main beam 200. In the case where the main beam 200 is made of pultruded plates, a triangle can be cut off from the corresponding pultruded plates starting from the position Y% in the span direction. Normally, when the main beam is laid using pultruded plates, multiple pultruded plates are arranged in parallel in the width direction. In the part where the main beam 200 needs to be narrowed, the pultruded plate close to the trailing edge can also be cut off at the rear end of the main beam 200, and the transition of the shape and size of the main beam 200 can be formed by infusing resin. In addition, the pultruded plate can be laid only to the Y% position in the span direction of the blade, and within the range of Y%-100%, the remaining part of the main beam formed by overlapping the resin, that is, the remaining part of the main beam 200 is formed by laying fabrics of corresponding sizes and vacuum infusing resin.

[0041] By changing the width of the main beam, the symmetry center of the main beam is changed, so that the center of the main beam is offset to the leading edge, thereby adjusting the shear center position of the airfoil section. This method has little effect on the shape and aerodynamic performance of the blade.

[0042] Figure 4 The figure shows the relationship between the lift and the angle of attack of the blade section. The lift F of the blade airfoil increases linearly with the increase of the angle of attack α, but after reaching a certain critical value α3 (hereinafter referred to as the stall angle of attack), the lift F suddenly drops and the drag increases significantly, that is, a stall occurs. Stalling will not only cause a loss in the power generation performance of the unit, but also cause damage to related components and even the entire unit, thereby causing safety issues for the unit. Therefore, the blades of wind turbines should be kept from working in a stall state as much as possible.

[0043] According to an embodiment of the present application, by adjusting the shear center of the blade to the leading edge side of the aerodynamic center, the lift F can generate an additional torque relative to the shear center to make the blade lower its head, thereby reducing the angle of attack of the blade, for example, Figure 4 As shown, the angle of attack is reduced from α2 to α1, thereby moving away from the stall angle of attack α3, increasing the blade stall margin and reducing the blade stall risk.

[0044] like Figure 5 and Figure 6 As shown, according to an embodiment of the present application, the position of the blade cross section can be further adjusted to move the blade cross section toward the trailing edge side, that is, the airfoil cross section is offset toward the trailing edge side relative to the airfoil cross section on its root side, so that the aerodynamic center B is always on the trailing edge side of the pitch center C. Figure 5Shows a schematic diagram of the relative positions of the pitch center C and the aerodynamic center B of the blade according to the second embodiment of the present invention. As Figure 5 shown, the aerodynamic center B is located on the trailing edge side of the pitch center C. When the lift force F acting on the blade increases, in addition to providing a bending moment to the blade, it will also generate a torsional moment M that causes the blade to pitch down on the pitch center C. The entire blade will twist under the action of this torsional moment M. As Figure 5 shown, it twists in the counterclockwise direction, reducing the sectional angle of attack, thereby reducing the lift force and blade load, and playing the function of adaptive passive load reduction. Similarly, the stall margin of the cross-section after the blade pitches down will also increase, thereby reducing the stall risk of the blade.

[0045] The following is the actual torsional angle formula for the blade cross-section:

[0046]

[0047] where, θ is the cross-sectional torsional angle, F is the cross-sectional aerodynamic force, L is the distance from the cross-sectional aerodynamic center to the pitch center, that is, the torsional force arm, and T is the cross-sectional torsional stiffness. The farther away from the blade root, the smaller the torsional stiffness T. It can be seen from the above formula that the farther the blade cross-section is from the blade root, the larger its torsional angle θ, the greater the reduction in the angle of attack, and thus the better the load reduction effect.

[0048] However, when the distance between the cross-sectional aerodynamic center B and the pitch center increases (i.e., increasing the torsional force arm of the aerodynamic force relative to the pitch center), based on the parallel axis formula of the moment of inertia, the moment of inertia of the blade cross-section relative to the pitch center C will also increase, resulting in an increase in the pitch torque load Mz, which may affect the fatigue life of the pitch bearing. Therefore, the purpose of adaptive load reduction can be achieved by only offsetting a part of the blade cross-section towards the trailing edge. For example, starting from the position of Z% of the blade length from the blade root towards the blade tip, the cross-section of the blade is offset towards the trailing edge side of the blade. The change in the blade cross-section position can be as Figure 6 shown, where the range of Z% is 40% - 60%.

[0049] Since the pitch load is positively correlated with the distance between the aerodynamic center and the pitch center, when the distance between the aerodynamic center and the pitch center increases, the pitch load of the blade also increases accordingly. Therefore, in order to control the pitch load, the distance that the blade tip offsets towards the trailing edge direction relative to the pitch center axis is not greater than 1.5% of the blade length.

[0050] In addition, according to the embodiment of the present invention, the blade root region can also be swept forward. Specifically, as Figure 5As shown, in the region of 2% - Z% of the blade span, the aerodynamic center of the airfoil is located on the leading edge side of the pitch center. The maximum forward sweep of the blade root region can be 10% of the maximum rearward sweep of the blade tip region. By slightly bending the blade root region forward, the overall curve of the blade can be made smoother, and it can also balance the moment of inertia of the blade, reducing the increase in the Mz load caused by pure rearward sweep.

[0051] Although the schemes for adjusting the blade shear center and the blade aerodynamic center are described above in combination with the drawings respectively, these two schemes can be implemented separately or simultaneously to obtain the superposition of the adaptive passive load reduction effects.

[0052] By means of adjusting the blade shear center to move towards the leading edge side of the blade and be located on the leading edge side of the aerodynamic center and moving the aerodynamic center of the blade relative to the pitch center towards the trailing edge side, the blade has the ability of adaptive passive load reduction and improving the stall margin. During the actual operation of the blade, when encountering a suddenly increased oncoming wind, the blade can lower its head and twist itself to achieve partial unloading, avoiding excessive loads and stall phenomena to a certain extent; for the shutdown and fault conditions, the blade also has a certain self - adjustment ability. For a blade with a length of 120m, under the same conditions, the simulated blade load limit can be reduced by 2 - 5%, and at the same time, the stall margin from the middle to the tip of the blade can be increased by 1 - 3 degrees.

[0053] According to the embodiments of the present disclosure, by adjusting the shear center of the blade to be located on the leading edge side of the aerodynamic center, the aerodynamic force generates an additional torsional moment that makes the blade lower its head relative to the shear center, reducing the angle of attack of the blade. In addition, by moving the cross - section of the blade tip part, the aerodynamic center of the blade cross - section is behind the pitch center, so that when the blade undergoes bending deformation under the action of the aerodynamic force, the torsional angle deformation relative to the pitch center must be in the direction of lowering the head, thereby reducing the load on the blade, and thus having the ability of adaptive passive load reduction. The greater the oncoming wind speed, the greater the lowering and twisting, and the more obvious the load reduction effect.

[0054] The present invention realizes the function of adaptive passive load reduction of the blade under high wind speeds through the blade structure adjustment, adopting the combined design of the blade shear center, the pitch center, and the blade aerodynamic center, reducing the risk of blade failure under high winds to a certain extent, giving more response time to the control system, and at the same time reducing the operating angle of attack under high winds and reducing the blade stall risk.

[0055] In the description of the present disclosure, it should be understood that the orientation or positional relationships indicated by the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. These are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present disclosure.

[0056] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present disclosure, unless otherwise specified, the meaning of "a plurality" is two or more.

[0057] In the description of the present disclosure, it should be noted that, unless otherwise clearly specified and limited, the terms "mounted", "connected", "coupled", "fixed" should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection, an electrical connection, or a communication connection; it may be directly connected, or indirectly connected through an intermediate medium, and it may be the internal communication of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0058] The features, structures, or characteristics described in the present disclosure may be combined in any suitable manner in one or more embodiments. In the above description, many specific details are provided to give a thorough understanding of the embodiments of the present disclosure. However, those skilled in the art will realize that the technical solutions of the present disclosure can be practiced without one or more of the specific details, or other methods, components, materials, etc. may be used. In other cases, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the present disclosure.

Claims

1. A blade for a wind turbine generator set, characterized in that, the blade comprises: a blade shell having a leading edge and a trailing edge oppositely arranged in the chord direction of the blade; a main beam integrated in the blade shell; a web located inside the blade shell and connected to the main beam; wherein, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section, and the range of X% is 50%-80%, within the range of Z%-100% of the blade length in the direction from the blade root to the blade tip, the airfoil section of the blade is offset backward relative to the airfoil section on its root side, so that the aerodynamic center of the airfoil section is located on the trailing edge side of the pitch center axis of the blade, and the range of Z% is 40%-80%.

2. The blade for a wind turbine generator set according to claim 1, characterized in that, the distance between the shear center and the aerodynamic center is 1%-8% of the chord length.

3. The blade for a wind turbine generator set according to claim 2, characterized in that, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, the center of the main beam is offset toward the leading edge side of the blade, so that the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section.

4. The blade for a wind turbine generator set according to claim 3, characterized in that, within the range of X%-100% of the blade length in the direction from the blade root to the blade tip, within the airfoil section of the blade, starting from the leading edge side of the blade, the shear center is located within the range of 18%-25% of the chord length of the blade.

5. The blade for a wind turbine generator set according to claim 2, characterized in that, within the range from the blade root to X% of the blade length, within the airfoil section of the blade, the shear center of the blade is located on the trailing edge side of the aerodynamic center.

6. The blade for a wind turbine generator set according to claim 2, characterized in that, within the range of Y%-100% of the blade length in the direction from the blade root to the blade tip, the trailing edge side of the main beam gradually inclines toward the leading edge side of the main beam, so that the width of the main beam gradually becomes narrower in the direction toward the blade tip, so that the shear center of the airfoil section of the blade is located on the leading edge side of the aerodynamic center of the airfoil section, where Y% is greater than X%.

7. The blade for a wind turbine generator set according to claim 6, characterized in that, the range of Y% is 70%-90%.

8. The blade for a wind turbine generator set according to claim 6, characterized in that, the width of the end of the main beam facing the blade tip is at least 80% of the width of the end of the main beam facing the blade root.

9. The blade for a wind turbine generator set according to any one of claims 1-8, characterized in that, the difference in position between the aerodynamic center and the shear center of the airfoil section of the blade is 1%-8% of the chord length, and in the length direction from the blade root to the blade tip, the distance between the shear center and the aerodynamic center gradually increases.

10. The blade for a wind turbine according to claim 9, wherein, the distance by which the tip of the blade is offset rearward from the pitch center axis of the blade is less than 1.5% of the blade length.

11. The blade for a wind turbine according to claim 9, wherein, in the range from the root to Z% of the blade length of the blade, the aerodynamic center of the airfoil section of the blade is located on the leading edge side of the pitch center axis of the blade.

12. The blade for a wind turbine according to claim 11, wherein, the maximum forward sweep of the root region of the blade is 10% of the maximum rearward sweep of the tip region of the blade.

13. A wind turbine, wherein, the wind turbine includes a blade as described in any one of claims 1 - 12.

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