A wind turbine blade hoisting transverse swing aerodynamic damping identification method, system and risk prompting method

Abstract

The application discloses a wind turbine blade hoisting transverse swing aerodynamic damping identification method and system and a risk prompting method. The method comprises the following steps: based on a simplified condition, a three-wire spring blade hoisting model is utilized to combine the stiffness parameters of a main hoisting rope and two horizontal auxiliary traction ropes to output a free vibration equation of a wind turbine blade hoisting system, and the natural frequency of the calculation model is calculated by using the free vibration equation; the aerodynamic force suffered by the wind turbine blade in the hoisting process is Taylor expanded by using the blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length is calculated by using the expansion result; the aerodynamic damping force per unit length is integrated in the blade span direction, and the integral result is input into the free vibration equation to output a forced vibration equation; and the natural frequency of the model is combined with the forced vibration equation to output an aerodynamic damping ratio, and the model is simple, and the calculation speed is high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of wind turbine blade hoisting, and more particularly to a wind turbine blade hoisting transverse swing aerodynamic damping identification method, system and risk prompting method. BACKGROUND

[0002] With the large-scale of wind turbines and the variable working environment of hoisting wind turbine blades, it becomes more and more complex to solve various parameters by using simulation methods, which not only doubles the calculation time, but also may not be accurate. The method of wind tunnel experiment requires a larger experimental site, and the cost is also higher. It is not easy to realize for offshore wind turbines.

[0003] The common methods for identifying modal damping at present mainly include frequency domain identification method and time domain identification method. The frequency domain method needs to have input and output measured data, and needs to use experimental methods to obtain data. Although the data obtained by using experimental methods is more accurate, it is time-consuming and laborious. The time domain method has the advantage that damping identification can be directly performed through response data, but the precision of this method is low.

[0004] The prior art patent with publication number CN114626149A proposes a calculation method for quickly calculating the aerodynamic damping of a wind turbine blade. The steps of this scheme are: inputting the airfoil aerodynamic data of each interface of the blade, calculating the relative wind speed of each interface; calculating the aerodynamic damping of each section of the blade in the wind wheel rotation plane; extracting the wind turbine blade operating modal parameters, including modal main mass, modal mode shape and natural frequency; and calculating the modal aerodynamic damping ratio of the blade. The method has high calculation complexity and strong wind condition dependence. In order to calculate the damping ratio with high precision, various input parameters need to be accurately obtained. SUMMARY

[0005] To overcome the problems of high calculation complexity and strong wind condition dependence of wind turbine blade aerodynamic damping in the prior art, the present application provides a wind turbine blade hoisting transverse swing aerodynamic damping identification method, system and risk prompting method.

[0006] The primary object of the present application is to solve the above technical problems. The technical solution of the present application is as follows:

[0007] The present application provides a wind turbine blade hoisting transverse swing aerodynamic damping identification method in the first aspect, which comprises the following steps:

[0008] Based on the preset simplified condition, the free vibration equation of the wind turbine blade hoisting system is output by using the three-wire spring blade hoisting model combined with the stiffness parameters of the main hoisting rope and the two horizontal auxiliary traction ropes, and the natural frequency of the model is calculated by using the free vibration equation;

[0009] The aerodynamic force received by the blade in the hoisting process is Taylor expanded by using the blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length is calculated by using the expansion result;

[0010] The unit length aerodynamic damping force is integrated in the blade span direction, and the integral result is input into the free vibration equation to output the forced vibration equation under the action of wind load;

[0011] The natural frequency of the model is combined with the forced vibration equation to output the aerodynamic damping ratio.

[0012] Further, the preset simplification condition comprises:

[0013] The top position of the crane is considered to remain unchanged during hoisting;

[0014] The yaw angle velocity of the blade is small during hoisting, and the yaw coupling effect is ignored in the simplified model;

[0015] Each degree of freedom is independent of each other, which is respectively the pendulum, waving and rotating;

[0016] The center of gravity of the simplified model moves independently in different degrees of freedom.

[0017] Further, the method for calculating the free vibration equation of the wind turbine blade hoisting system comprises the following steps:

[0018] The hoisted blade and its clamp are considered as a lumped mass, the main hoisting cable and the two horizontal auxiliary traction ropes are simplified as three linear springs, the spring stiffness parameters of each are obtained, and a three-line spring blade hoisting simplified model is established;

[0019] According to the motion form of the simplified model, the expressions of the total kinetic energy T and the total potential energy V of the system are determined, and the expressions are as follows:

[0020]

[0021] Wherein, (X C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 ) are the initial points of the plane system A, B, C, θ0 is the initial angle, (X C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 ) are the terminal points of the plane system A, B, C after movement, wherein the distances of A, B, C from the X axis and Y axis are respectively X AC ,YAC ,X BC ,Y BC Where m is the mass of the blade clamp, I is the moment of inertia of the blade and clamp on the Y-axis, and θ is the rotation angle. and These represent the velocities in the forward and backward oscillation direction and the up and down flaring direction of the blade, respectively, indicating that the positions of A and B are rotations relative to point C. Let k be the rotational angular velocity, and k, k1, k2 be the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively.

[0022] For a simple pendulum system, applying the Lagrange equation, the expression is as follows:

[0023]

[0024] L = TV

[0025] Where L is the Lagrangian function; T is the total kinetic energy of the system; V is the total potential energy of the system; q i Let X be the i-th generalized coordinate. C1 Y C1 Even any point in two-dimensional space, The derivative of the i-th generalized coordinate with respect to time is the velocity of that generalized coordinate.

[0026] Substituting the expressions for total kinetic energy and total potential energy into the Lagrange equations, we obtain the free vibration equations in the direction of the pendulum oscillation, as shown below:

[0027]

[0028] in, For speed The acceleration is obtained by differentiating it with respect to time.

[0029] Furthermore, the natural frequencies of the model are calculated using the free vibration equation, including the following steps:

[0030] At the system's equilibrium position, the derivative of the potential energy is 0, that is...

[0031] k1(X AC cosθ0-Y AC sinθ0)+k2(X BC cosθ0-Y BC sinθ0)=0

[0032] Substituting it into the free vibration equation and simplifying, we get:

[0033]

[0034] From the above formula, we can obtain the simplified model of the wind turbine hoisting system. C1 The natural frequency of the direction is:

[0035]

[0036] Similarly, Y can be obtained. C1 The dynamic equations and related natural frequencies in the θ direction.

[0037] Furthermore, the method for calculating the aerodynamic damping force per unit length includes the following steps:

[0038] Based on the blade element momentum theory, the relative wind speed, angle of attack, and corresponding lift and drag coefficients are input into the lift and drag formulas to obtain the lift and drag of each blade element.

[0039] Projecting lift and drag onto the blade's fore-and-aft oscillation direction and performing a Taylor expansion of the aerodynamic forces, we obtain the aerodynamic damping force per unit length. The expression is as follows:

[0040]

[0041] Where r is the radial distance from the hub center of the wind turbine to the blade center, and η is the contribution of aerodynamic damping. r The expression is as follows:

[0042]

[0043] Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C D (α) is the drag coefficient corresponding to the blade element angle of attack α, C L For lift coefficient, C D C is the drag coefficient. L ′、C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

[0044] Furthermore, the method of using aerodynamic damping force per unit length to output the forced vibration equation under wind load includes the following steps:

[0045] Integrating the aerodynamic damping force per unit length about the blade spanwise coordinates yields the total aerodynamic damping force, as shown in the following expression:

[0046]

[0047] Where r is the radial distance from the hub center of the wind turbine to the blade element center, and l is the total length of the blade. The velocity of the center of gravity in the X direction;

[0048] Combining the total aerodynamic damping force with the free vibration equation, we obtain the forced vibration equation containing aerodynamic terms, as shown below:

[0049]

[0050] This leads to the expression:

[0051]

[0052] Where m is the mass of the blade clamp, X C1 Let x be the endpoint coordinate of point A. The velocity in the direction of the blade's forward and backward oscillation. For speed The acceleration is obtained by differentiating with respect to time. k, k1, and k2 are the spring stiffnesses of the main sling wire rope, the first traction rope wire rope, and the second traction rope wire rope, respectively, and the contribution of aerodynamic damping η is the aerodynamic damping. r The expression is as follows:

[0053]

[0054] Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C D (α) is the drag coefficient corresponding to the blade element angle of attack α, C L C is the lift coefficient. D C is the drag coefficient. L ′、C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

[0055] Furthermore, the aerodynamic damping ratio ζ of the wind turbine blade hoisting is calculated using the natural frequency and the forced vibration equation, including the following steps:

[0056] The general form of the equation of motion is expressed as follows:

[0057]

[0058] Where M is the mass matrix, C is the damping coefficient matrix, and K is the stiffness coefficient matrix, combined with the forced vibration equation (1), the expression for the damping coefficient matrix C can be obtained as follows:

[0059]

[0060] The general form of the aerodynamic damping ratio is expressed as follows:

[0061]

[0062] Where, ω nLet m be the natural frequency, m be the sum of the masses of the blade and the fixture, and C be the damping coefficient matrix. The damping coefficient matrix expression (2) and the natural frequency formula are:

[0063]

[0064] Substituting into expression (3), we can obtain the expression for the aerodynamic damping ratio ζ as follows:

[0065]

[0066] Where r is the radial distance from the hub center of the wind turbine to the blade center, k, k1, and k2 are the spring stiffnesses of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively, m is the mass of the blade clamp, l is the total length of the blade, and η is the contribution of aerodynamic damping. r The expression is as follows:

[0067]

[0068] Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C D (α) is the drag coefficient corresponding to the blade element angle of attack α, C L C is the lift coefficient. D C is the drag coefficient. L ′、C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

[0069] Furthermore, the aerodynamic damping ratio can be calculated using a discrete method, as shown in the following expression:

[0070]

[0071] Where l is the length of the blade, Δr is the spanwise length of each blade segment, n is the total number of segments, and η ri This contributes to the aerodynamic damping of each blade segment.

[0072] Furthermore, the method for determining the aeroelastic stability during the hoisting process based on the aerodynamic damping ratio includes the following steps:

[0073] Based on the calculated aerodynamic damping ratio, identify whether the aerodynamic damping is positive or negative under a given lifting condition;

[0074] When the aerodynamic damping is negative and its absolute value is greater than the damping of the structure itself, the output indicates that there is a risk of aeroelastic instability during blade hoisting.

[0075] The second aspect of this invention provides a method for indicating the risk of lateral sway during wind turbine blade hoisting. This method utilizes an aerodynamic damping identification method for lateral sway during wind turbine blade hoisting to calculate the aerodynamic damping ratio, determines the aeroelastic stability of the hoisting process based on the aerodynamic damping ratio, and outputs a corresponding risk warning. The method includes the following steps:

[0076] Based on the calculated aerodynamic damping ratio, identify whether the aerodynamic damping is positive or negative under a given lifting condition;

[0077] When the aerodynamic damping is negative and its absolute value is greater than the damping of the structure itself, the output indicates that there is a risk of aeroelastic instability during blade hoisting.

[0078] A third aspect of the present invention provides a wind turbine blade lateral oscillation aerodynamic damping identification system, including a memory and a processor. The memory includes a wind turbine blade lateral oscillation aerodynamic damping identification method program. When the wind turbine blade lateral oscillation aerodynamic damping identification method program is executed by the processor, it implements the steps of a wind turbine blade lateral oscillation aerodynamic damping identification method.

[0079] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0080] The calculation method of this invention does not rely on extremely complex real-time wind data. By simplifying the conditions and models, it avoids the tedious calculation of wind speed, angle of attack, and lift-drag coefficients for each blade section. Compared with traditional calculation methods, it greatly reduces the consumption of computing resources and can obtain approximately accurate calculation results in a shorter time. It is particularly suitable for the frequent aerodynamic damping calculation needs during wind turbine operation. Attached Figure Description

[0081] To make the objectives and technical solutions of this invention clearer, the following drawings are provided and described:

[0082] Figure 1 A flowchart of the method provided in an embodiment of the present invention;

[0083] Figure 2 The dynamic analysis diagram provided for the embodiments of the present invention;

[0084] Figure 3 A planar system diagram of three wire springs provided in an embodiment of the present invention;

[0085] Figure 4 A cross-sectional view of a wind turbine blade provided in an embodiment of the present invention;

[0086] Figure 5 Vibration trend diagram of blade root displacement provided in an embodiment of the present invention; Detailed Implementation

[0087] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0088] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0089] Example 1:

[0090] This invention provides a method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting, such as... Figure 1 The diagram shows a flowchart for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting. The specific steps are as follows:

[0091] S1: Based on the preset simplified conditions, the free vibration equation of the wind turbine blade hoisting system is output by combining the stiffness parameters of the main hoisting rope and two horizontal auxiliary traction ropes with the three-wire spring blade hoisting model. The natural frequency of the model is then calculated using the free vibration equation.

[0092] More specifically, the preset simplification conditions include:

[0093] 1. The position of the top of the crane is considered to remain constant during the hoisting process. Assume that the position of the center of gravity plane after simplifying the model is [0, 0, 0]. T ;

[0094] 2. Blade yaw rate during hoisting The value is relatively small, which corresponds to the yaw coupling effect being ignored in the simplified model;

[0095] 3. The degrees of freedom are independent of each other, namely pendulum, swing, and rotation;

[0096] 4. The motion of the center of gravity in the simplified model is independent under different degrees of freedom.

[0097] Due to the complex hoisting structure of ultra-long flexible blades, conventional dynamic analysis is difficult to perform, such as... Figure 2 As shown, the liftline is the main sling, and tugger line1 and tugger line2 are the first traction rope and the second traction rope, respectively.

[0098] The blade clamp is equated to a simple pendulum ball, and the hoisting rope is equated to the rope pulling the pendulum ball, simplifying the system into a simple pendulum model for dynamic analysis. The total kinetic energy T and total potential energy V of the pendulum system are obtained as follows:

[0099]

[0100] Where m is the mass of the blade and clamp, g represents the acceleration due to gravity, taken as 9.8 m / s², and l represents the length of the pendulum rope. Indicates the rotation angle. Let be the angular velocity. Based on the above formula, the governing equations of the simple pendulum system are expressed as follows:

[0101]

[0102] in, It is angular acceleration, where l represents the length of the pendulum rope, because the rotation angle... It's very small, so it has Multiplying both sides of the above formula by the mass m, we get the expression:

[0103]

[0104] Therefore, we can obtain:

[0105]

[0106] Based on the above formula, the upper rope can be simplified as a line spring connected to the center of mass, with a spring stiffness of k. During the blade hoisting process, two additional horizontal traction ropes assist in the hoisting operation. These two traction ropes are also simplified as two springs with spring stiffnesses k1 and k2 respectively. The blade hoisting system can then be simplified into a planar system with three line springs, as shown below. Figure 3 As shown.

[0107] The method for calculating the free vibration equation of a wind turbine blade hoisting system includes the following steps:

[0108] The lifting blade and its clamps are considered as a lumped mass. The main sling and the two horizontal auxiliary traction ropes are simplified into three line springs. The spring stiffness parameters of each are obtained, and a simplified three-line spring blade lifting model is established.

[0109] Based on the simplified model's motion, the expressions for the system's total kinetic energy T and total potential energy V are determined as follows:

[0110]

[0111] Among them, (X) C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 Let be the initial points of the planar system A, B, C, and θ0 be the initial angle. C1 ,YC1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 Let A, B, and C be the endpoints of the planar system after the motion, where the distances of A, B, and C along the X and Y axes are respectively X, B, and C. AC ,Y AC ,X BC ,Y BC Where m is the mass of the blade clamp, I is the moment of inertia of the blade and clamp on the Y-axis, and θ is the rotation angle. and These represent the velocities in the forward and backward oscillation direction and the up and down flaring direction of the blade, respectively, indicating that the positions of A and B are rotations relative to point C. Let k be the rotational angular velocity, and k, k1, k2 be the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively.

[0112] In dynamic analysis, to use the Lagrange equations, it is necessary to first determine the position and velocity of each particle (or key node) in the system within the global coordinate system. The matrix form of position transformation is precisely the process of transforming local coordinates to the global coordinate system, facilitating the subsequent unified expression of kinetic and potential energy within the same coordinate system. The matrix expression for position transformation is shown below:

[0113]

[0114] In the formula, (X C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 () represents the endpoints of the planar system A, B, C after the motion, where the distances of A, B, C on the X-axis and Y-axis represent the distances of X, B, C, C respectively. AC ,Y AC ,X BC ,Y BC .

[0115] R is the transformation matrix from the main fixed frame to the global frame, which is given by the following equation:

[0116]

[0117] For a simple pendulum system, applying the Lagrange equation, the expression is as follows:

[0118]

[0119] L = TV

[0120] Where L is the Lagrangian function; T is the total kinetic energy of the system; V is the total potential energy of the system; q i Let X be the i-th generalized coordinate. C1 Y C1 Even any point in two-dimensional space, The derivative of the i-th generalized coordinate with respect to time is the velocity of that generalized coordinate.

[0121] Substituting the expressions for total kinetic energy and total potential energy into the Lagrange equation, we obtain the following expressions:

[0122]

[0123] Since this invention mainly analyzes the direction of oscillation, q is chosen here. i =X C1 Perform the analysis.

[0124] T only with Related to, not related to X C1 Regarding this, we can obtain:

[0125]

[0126] Therefore, we get:

[0127]

[0128] Where L is about X C1 The function, for Taking the partial derivative, we can obtain:

[0129]

[0130] Therefore, substitute expressions (4) and (5) into the formula. Afterwards, we can obtain:

[0131]

[0132] It is velocity, and the acceleration is obtained by differentiating it with respect to time. We can obtain:

[0133]

[0134] in, It is potential energy with respect to X C1 The partial derivatives of X are substituted into the linearized X. A1 X B1 X C1 After ignoring higher-order minor quantities, we get:

[0135]

[0136] Substituting it into the Lagrange equation and rearranging, we obtain the following expression:

[0137]

[0138] in, For speed The acceleration is obtained by differentiating it with respect to time.

[0139] The natural frequencies of the model are calculated using the free vibration equation, including the following steps:

[0140] At the system's equilibrium position, the derivative of the potential energy is 0, that is...

[0141] k1(X AC cosθ0-Y AC sinθ0)+k2(X BC cosθ0-Y BC sinθ0)=0

[0142] Substituting it into the free vibration equation and simplifying, we get:

[0143]

[0144] From the above formula, we can obtain the simplified model of the wind turbine hoisting system. C1 The natural frequency of the direction is:

[0145]

[0146] Similarly, Y can be obtained. C1 The dynamic equations and related natural frequencies in the θ direction.

[0147] S2: The aerodynamic forces experienced by the wind turbine blades during hoisting are subjected to Taylor expansion based on blade element momentum theory and aerodynamic parameters. The aerodynamic damping force per unit length is calculated using the expansion results.

[0148] The specific process is as follows:

[0149] like Figure 4 As shown, assuming the wind turbine blade is in a "stationary state", the inflow angle of the blade section is φ0, the angle of attack is α0, the relative inflow velocity is W0, the twist angle is β, and x is the lateral coordinate used to describe the horizontal position of the blade. This represents the displacement velocity of the blade. When the wind turbine blade vibrates back and forth under wind load, the above value will change as follows:

[0150]

[0151]

[0152] α=φ-φ0+α0

[0153] According to the blade element momentum theory, the lift L and drag D of the blade cross section are expressed as follows:

[0154]

[0155] Where L is lift, ρ is air density, c is blade element chord length, W is relative inflow velocity, and C is... L (α) represents the lift coefficient at the blade element angle of attack α, r is the radial distance from the hub center of the wind turbine to the blade element center, ρ is the air density, D is the drag, and C is the air density. D (α) is the drag coefficient corresponding to the blade element angle of attack α.

[0156] Projecting lift and drag onto the direction of vibration yields:

[0157]

[0158] Where φ is the inflow angle and β is the twist angle, substituting W, φ, and α into the above equation, we obtain the aerodynamic force F as... The function that will F in Performing a Taylor expansion at this point yields:

[0159]

[0160] Among them, the contribution of aerodynamic damping η r The expression is as follows:

[0161]

[0162] Where F0 is the first term of the Taylor expansion. This is the oscillation velocity caused by the wind load acting on the wind turbine blades during installation, which is a high-order small quantity in the expanded equation; η r The symbol used to represent the right side of the above equation is the lift coefficient C. L Drag coefficient C D C L ′、C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively, and their expressions are shown below:

[0163]

[0164] From expression (6), the aerodynamic damping force per unit length can be obtained as:

[0165]

[0166] In the formula, r is the radial distance from the center of the wind turbine hub to the center of the blade element.

[0167] S3: Integrate the aerodynamic damping force per unit length along the blade span, input the integration result into the free vibration equation, and output the forced vibration equation under wind load.

[0168] The specific process is as follows:

[0169] Integrating the aerodynamic damping force per unit length about the blade spanwise coordinates yields the total aerodynamic damping force, as shown in the following expression:

[0170]

[0171] Where r is the radial distance from the hub center of the wind turbine to the blade element center, and l is the total length of the blade. The velocity in the direction of the blade's forward and backward oscillation;

[0172] Combining the total aerodynamic damping force with the free vibration equation, we obtain the forced vibration equation containing aerodynamic terms, as shown below:

[0173]

[0174] This leads to the expression:

[0175]

[0176] Where m is the mass of the blade clamp, X C1 Let x be the endpoint coordinate of point A. The velocity in the direction of the blade's forward and backward oscillation. For speed The acceleration is obtained by differentiating with respect to time. k, k1, and k2 are the spring stiffnesses of the main sling wire rope, the first traction rope wire rope, and the second traction rope wire rope, respectively, and the contribution of aerodynamic damping η is the aerodynamic damping. r The expression is as follows:

[0177]

[0178] Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C D (α) is the drag coefficient corresponding to the blade element angle of attack α, C L C is the lift coefficient. D C is the drag coefficient. L ′、C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

[0179] S4: Combine the natural frequency of the model with the forced vibration equation to output the aerodynamic damping ratio.

[0180] More specifically, the aerodynamic damping ratio ζ of wind turbine blade hoisting is calculated using the natural frequency and the forced vibration equation, including the following steps:

[0181] The general form of the equation of motion is expressed as follows:

[0182]

[0183] Where M is the mass matrix, C is the damping coefficient matrix, and K is the stiffness coefficient matrix, combined with the forced vibration equation (1), the expression for the damping coefficient matrix C can be obtained as follows:

[0184]

[0185] The general form of the aerodynamic damping ratio is expressed as follows:

[0186]

[0187] Where, ω n Let m be the natural frequency, m be the sum of the masses of the blade and the clamp, and C be the damping coefficient matrix. The damping coefficient matrix expression (2) and the natural frequency expression are:

[0188]

[0189] Substituting into expression (3), we can obtain the expression for the aerodynamic damping ratio ζ as follows:

[0190]

[0191] Where r is the radial distance from the hub center of the wind turbine to the blade center, k, k1, and k2 are the spring stiffnesses of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively, m is the mass of the blade clamp, l is the total length of the blade, and η is the contribution of aerodynamic damping. r The expression is as follows:

[0192]

[0193] Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C D (α) is the drag coefficient corresponding to the blade element angle of attack α, C L C is the lift coefficient. D is the drag coefficient, and are the lift coefficient gradient and drag coefficient gradient, respectively.

[0194] More specifically, the aerodynamic damping ratio can be calculated using a discrete method, as shown in the following expression:

[0195]

[0196] Where l is the length of the blade, Δr is the spanwise length of each blade segment, n is the total number of segments, and η ri Discretization allows for more flexible handling of differences in airfoil, angle, and aerodynamic coefficient at different blade sections, thus contributing aerodynamic damping to each blade segment. In this embodiment, n is set to 19, assuming an average overhead wind speed of 10 m / s, a turbulent wind intensity of 15.27%, an inflow angle φ = 90°, and a twist angle β = 90° during the hoisting process. Aerodynamic damping contribution η r The expression is as follows:

[0197]

[0198] First, define the values ​​for the parameters in the formula, where ρ (air density) is 1.255 kg / m³. 3 Strictly corresponding to the international standard atmospheric conditions at sea level (0 meters), the chord length c is divided into 19 segments according to the 10MW model, and the value of the chord length c of each segment is stored in a variable array. The lift coefficient C L Drag coefficient C D C L ′、C′ D The data corresponding to different leaf shapes are stored in a variable array in the program, which calculates and outputs η as 1*19. i Array. Calculate η i The array is summed to obtain η. i The numerical table is shown below:

[0199] Table 1

[0200] [["η1= 211.839039947248"]] ​ [eta]2 = 262.454315547705 [CDATA[η3 = 656.396258792979]]> ​ <![CDATA[η5=760.912158990232]]> ​ [CDATA[η7= 1221.21928845892]]> ​ [CDATA[η9=690.305137243342]]> 10 = 1034.41547825207 ​ 11 = 585.499032073641 ​ 12 = 626.521508992250 ​ 13 = 910.50592 1091884 ​ 14 = 500.087450256186 ​ 15 = 453.473581664152 ​ 16 = 643.515546145594 ​ 17 = 342.743456302587 ​ 18 = 294.480156240872 ​ 19 = 182.264273086605 ​

[0201]

[0202] Where l is the length η of the blade. i For η of different cross sections r Calculation results. The blade is discretized into 19 rigid body segments, each with independent aerodynamic coefficients, thus achieving segmented equivalence in the dynamic model. Δr represents the length of each rigid body segment. Each rigid body segment has a different η. i In the integral formula, the variables are r and η. i The variation with r is essentially due to the different airfoils of different rigid body segments.

[0203]

[0204] In this embodiment, the total weight is m = 7E4kg, the stiffness coefficient of the main sling is k = 9.9E9N / m, and the stiffness coefficients of the two traction ropes are k1 = 3.5E7N / m and k2 = 3.5E7N / m.

[0205] Calculations using the fractional units revealed that both the upper and lower units are kg / s, confirming that the aerodynamic damping ratio is dimensionless.

[0206]

[0207] Where a is set to an arbitrary constant.

[0208] The aeroelastic stability during the hoisting process is determined based on the aerodynamic damping ratio, and corresponding risk warnings are output, including the following steps:

[0209] Based on the calculated aerodynamic damping ratio, identify whether the aerodynamic damping is positive or negative under a given lifting condition;

[0210] When the aerodynamic damping is negative and its absolute value is greater than the damping of the structure itself, the output indicates that there is a risk of aeroelastic instability during blade hoisting.

[0211] In this embodiment, the calculated result is 0.1%. When the aerodynamic damping ratio of the wind turbine blade during hoisting is 0.1% (i.e., 0.001), although this value is within a reasonable range (typically 0.01% to 0.1%) during hoisting conditions, it is still considered acceptable. To verify whether it conforms to the trend, software modeling and simulation were used. Under turbulent wind conditions with an average wind speed of 10 m / s and a turbulence intensity of 15.27%, the vibration trend of the blade root displacement is as follows: Figure 5 As shown, the blades exhibit continuous small-amplitude vibrations under wind load, with the amplitude decaying slowly. The calculation method of this invention does not rely on extremely complex real-time wind condition data. By simplifying the conditions and model, it avoids the tedious calculations of wind speed, angle of attack, and lift / drag coefficients for each blade section. Compared with traditional calculation methods, it significantly reduces the consumption of computational resources and can obtain approximately accurate calculation results in a shorter time, making it particularly suitable for the frequent aerodynamic damping calculations required during wind turbine operation.

[0212] Example 2:

[0213] This embodiment provides a wind turbine blade hoisting lateral oscillation aerodynamic damping identification system, including a memory and a processor. The memory includes a wind turbine blade hoisting lateral oscillation aerodynamic damping identification method program. When the wind turbine blade hoisting lateral oscillation aerodynamic damping identification method program is executed by the processor, it implements the steps of a wind turbine blade hoisting lateral oscillation aerodynamic damping identification method as described in Embodiment 1.

[0214] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for identifying the aerodynamic damping of lateral oscillation during wind turbine blade hoisting, characterized in that, Includes the following steps: Based on the preset simplified conditions, the free vibration equation of the wind turbine blade hoisting system is output by combining the stiffness parameters of the main hoisting rope and two horizontal auxiliary traction ropes with the three-wire spring blade hoisting model. The natural frequency of the model is then calculated using the free vibration equation. Taylor expansion of the aerodynamic forces on wind turbine blades during hoisting was performed using blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length was calculated using the expansion results. The aerodynamic damping force per unit length is integrated along the blade span, and the integration result is input into the free vibration equation to output the forced vibration equation under wind load. By combining the model's natural frequency with the forced vibration equation, the aerodynamic damping ratio is output. The method for calculating the free vibration equation of a wind turbine blade hoisting system includes the following steps: The lifting blade and its clamps are considered as a lumped mass. The main sling and the two horizontal auxiliary traction ropes are simplified into three line springs. The spring stiffness parameters of each are obtained, and a simplified three-line spring blade lifting model is established. Based on the simplified model's motion, the expressions for the system's total kinetic energy T and total potential energy V are determined as follows: Among them, (X) C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 Let X be the initial point of the planar system A, B, C. C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 Let be the endpoint of the planar system A, B, C after its motion, where the distances of A, B, and C along the X-axis and Y-axis are respectively X... AC ,Y AC ,X BC ,Y BC Where m is the mass of the blade clamp, I is the moment of inertia of the blade and clamp on the Y-axis, and θ is the rotation angle. and These represent the velocities in the forward and backward oscillation direction and the up and down flaring direction of the blade, respectively, indicating that the positions of A and B are rotations relative to point C. Let k be the rotational angular velocity, and k, k1, k2 be the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively. For a simple pendulum system, applying the Lagrange equation, the expression is as follows: L = TV Where L is the Lagrangian function; T is the total kinetic energy of the system; V is the total potential energy of the system; q i Let be the i-th generalized coordinate, which is any point in two-dimensional space. Let t be the derivative of the i-th generalized coordinate with respect to time, i.e., the velocity of that generalized coordinate, where t is time. Substituting the expressions for total kinetic energy and total potential energy into the Lagrange equations, we obtain the free vibration equations in the direction of the pendulum oscillation, as shown below: in, For speed The acceleration is obtained by differentiating with respect to time, where θ0 is the initial angle.

2. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 1, characterized in that, The preset simplification conditions include: The position of the top of the crane is considered to remain unchanged during the hoisting process; During the hoisting process, the blade yaw angular velocity is small, so the yaw coupling effect is ignored in the simplified model. Each degree of freedom is independent of the others, namely pendulum, swing, and rotation; The motion of the center of gravity in the simplified model is independent in different degrees of freedom.

3. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 1, characterized in that, The natural frequencies of the model are calculated using the free vibration equation, including the following steps: At the system's equilibrium position, the derivative of the potential energy is 0, that is... k1(X AC cosθ0-Y AC sinθ0)+k2(X BC cosθ0-Y BC sinθ0)=0 Substituting it into the free vibration equation and simplifying, we get: From the above formula, the simplified model of the wind turbine hoisting system can be obtained as X. C1 The natural frequency of the direction is:

4. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 1, characterized in that, The method for calculating the aerodynamic damping force per unit length includes the following steps: Based on the blade element momentum theory, the relative wind speed, angle of attack, and corresponding lift and drag coefficients are input into the lift and drag formulas to obtain the lift and drag of each blade element. Projecting lift and drag onto the blade's fore-and-aft oscillation direction and performing a Taylor expansion of the aerodynamic forces, we obtain the aerodynamic damping force per unit length. The expression is as follows: Among them, the contribution of aerodynamic damping η r The expression is as follows: Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C L For lift coefficient, C D C′ is the drag coefficient. L C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

5. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 1, characterized in that, The method for deriving the forced vibration equation under wind load using aerodynamic damping force per unit length includes the following steps: Integrating the aerodynamic damping force per unit length about the blade spanwise coordinates yields the total aerodynamic damping force, as shown in the following expression: Where r is the radial distance from the hub center of the wind turbine to the blade element center, and l is the total length of the blade. The velocity in the direction of the blade's forward and backward oscillation; Combining the total aerodynamic damping force with the free vibration equation, we obtain the forced vibration equation containing aerodynamic terms, as shown below: This leads to the forced vibration equation formula (1): Where m is the mass of the blade clamp, X C1 Let x be the endpoint coordinate of point A. The velocity in the direction of the blade's forward and backward oscillation. For speed The acceleration is obtained by differentiating with respect to time. k, k1, and k2 are the spring stiffnesses of the main sling wire rope, the first traction rope wire rope, and the second traction rope wire rope, respectively, and the contribution of aerodynamic damping η is the aerodynamic damping. r The expression is as follows: Where c is the blade element chord length, ρ is the air density, φ0 is the inflow angle of the blade cross-section when the wind turbine blade is stationary, W0 is the relative inflow velocity, β is the twist angle, and C L C is the lift coefficient. D C′ is the drag coefficient. L C′ D These are the lift coefficient gradient and the drag coefficient gradient, respectively.

6. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 5, characterized in that, The aerodynamic damping ratio ζ of wind turbine blade hoisting is calculated using natural frequencies and forced vibration equations, including the following steps: The general form of the equation of motion is expressed as follows: Where M is the mass matrix, C is the damping coefficient matrix, and K is the stiffness coefficient matrix, combined with the forced vibration equation (1), the expression for the damping coefficient matrix C can be obtained as follows: The general form of the aerodynamic damping ratio is expressed as follows: Where, ω n Let m be the natural frequency, m be the mass of the blade clamp, and C be the damping coefficient matrix. The damping coefficient matrix expression (2) and the natural frequency formula are: Substituting into expression (3), we can obtain the expression for the aerodynamic damping ratio ζ as follows: Where r is the radial distance from the hub center of the wind turbine to the blade center, k, k1, and k2 are the spring stiffness of the main hoisting cable, the first traction cable, and the second traction cable, respectively, m is the mass of the blade clamp, and l is the total length of the blade.

7. The method for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting according to claim 6, characterized in that, The aerodynamic damping ratio is calculated using a discrete method, and the expression is as follows: Where l is the length of the blade, Δr is the spanwise length of each blade segment, n is the total number of segments, and η ri This contributes to the aerodynamic damping of each blade segment.

8. A method for risk warning of lateral sway during wind turbine blade hoisting, comprising calculating the aerodynamic damping ratio using the aerodynamic damping identification method for lateral sway during wind turbine blade hoisting as described in any one of claims 1-7, determining the aeroelastic stability of the hoisting process based on the aerodynamic damping ratio, and outputting a corresponding risk warning, including the following steps: Based on the calculated aerodynamic damping ratio, identify whether the aerodynamic damping is positive or negative under a given lifting condition; When the aerodynamic damping is negative and its absolute value is greater than the damping of the structure itself, the output indicates that there is a risk of aeroelastic instability during blade hoisting.

9. A wind turbine blade lateral oscillation aerodynamic damping identification system, characterized in that, The system includes a memory and a processor. The memory includes a program for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting. When the processor executes the program for identifying the aerodynamic damping of the lateral oscillation during wind turbine blade hoisting, it implements the steps of the aerodynamic damping identification method for the lateral oscillation during wind turbine blade hoisting as described in any one of claims 1 to 7.

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