Wind turbine blade hoisting transverse swing aerodynamic damping identification method and system and risk prompting method

Abstract

The invention 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: outputting a free vibration equation of the wind turbine blade hoisting system by utilizing a three-wire spring blade hoisting model and combining rigidity parameters of a main hoisting rope and two horizontal auxiliary traction ropes based on simplified conditions, and calculating the inherent frequency of the model by utilizing the free vibration equation; taylor expansion is carried out on aerodynamic force borne by the wind turbine blade in the hoisting process according to the blade element momentum theory and aerodynamic parameters, and aerodynamic damping force per unit length is calculated according to the expansion result; the aerodynamic damping force per unit length is integrated in the blade spanwise direction, an integration result is input into a free vibration equation, and a forced vibration equation is output; the inherent frequency of the model is combined with the forced vibration equation, the aerodynamic damping ratio is output, the model is simplified, and the calculation speed is high.

Description

Technical Field

[0001] The present invention belongs to the field of wind turbine blade hoisting, and more specifically, relates to a method, system and risk warning method for identifying lateral swing aerodynamic damping of wind turbine blade hoisting. Background Art

[0002] With the increasing size of wind turbines and the changing working environment of hoisting wind turbine blades, it becomes more and more complicated to solve various parameters by simulation methods. Not only will the calculation time increase exponentially, but the results may be inaccurate. The wind tunnel test method requires a larger test site and is more expensive, which is not easy to achieve for offshore wind turbines.

[0003] At present, the commonly used methods for identifying modal damping are frequency domain identification method and time domain identification method. The frequency domain method requires measured data of input and output, so it is necessary to use experimental methods to obtain data. Although the experimental method can obtain more accurate data, it is time-consuming and laborious. The advantage of using the time domain method is that it can directly identify damping through response data, but this method has low accuracy.

[0004] The invention patent with the prior art publication number CN114626149A proposes a method for quickly calculating the aerodynamic damping of wind turbine blades. The steps of this scheme are: input the airfoil aerodynamic data of each interface of the blade, calculate the relative wind speed of each interface; calculate the aerodynamic damping of each section of the blade in the inner and outer directions of the wind rotor rotation plane; extract the operating modal parameters of the wind turbine blade, including the modal main mass, modal vibration shape and natural frequency; calculate the modal aerodynamic damping ratio of the blade. The calculation complexity of this method is high and it is highly dependent on wind conditions. It is necessary to accurately obtain various input parameters to calculate a damping ratio with high accuracy. Summary of the invention

[0005] In order to overcome the problems of high calculation complexity and strong dependence on wind conditions of wind turbine blade aerodynamic damping in the prior art, the present invention provides a method, system and risk warning method for identifying the aerodynamic damping of wind turbine blade hoisting lateral swing.

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

[0007] A first aspect of the present invention provides a method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation, comprising the following steps:

[0008] Based on the preset simplified conditions, the three-wire spring blade hoisting model is used to combine the stiffness parameters of the main hoisting rope and two horizontal auxiliary traction ropes to output the free vibration equation of the wind turbine blade hoisting system, and the natural frequency of the model is calculated using the free vibration equation.

[0009] The aerodynamic force on the wind turbine blades during the installation process is Taylor expanded using blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length is calculated using the expansion results.

[0010] Integrate the aerodynamic damping force per unit length in the span direction of the blade, input the integral result into the free vibration equation, and 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] Furthermore, the preset simplified conditions include:

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

[0014] During the hoisting process, the blade yaw angular velocity is small, and the yaw coupling effect is ignored in the corresponding simplified model;

[0015] Each degree of freedom is independent of each other, namely shimmy, flapping, and rotation;

[0016] The motions of the center of mass of the simplified model in different degrees of freedom are independent.

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

[0018] The lifting blade and its fixture are regarded as a lumped mass, the main lifting rope and two horizontal auxiliary traction ropes are simplified into three wire springs, the spring stiffness parameters of each are obtained, and a simplified model of three-wire spring blade lifting is established.

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

[0020]

[0021] Among them, (X C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 ) is the initial point of the plane system A, B, C, θ0 is the initial angle, (X C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 ) is the end point of A, B, and C after the plane system moves, where the distances of A, B, and C on the X-axis and Y-axis are X AC ,YAC ,X BC ,Y BC , m is the mass of the blade fixture, I is the moment of inertia of the blade and fixture on the Y axis, θ is the rotation angle, and are the speeds of the blade in the swinging direction and the speeds of the blade in the swinging direction, respectively, indicating that the positions of A and B are rotations relative to point C. is the angular velocity of rotation, k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction rope wire rope, and the second traction rope 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 is the i-th generalized coordinate, take X C1 , Y C1 Even any point in two-dimensional space, is the derivative of the i-th generalized coordinate with respect to time, that is, the velocity of the generalized coordinate;

[0026] Substituting the expressions of total kinetic energy and total potential energy into the Lagrange equation, we get the free vibration equation in the swing direction, which is as follows:

[0027]

[0028] in, For speed Taking the derivative with respect to time we get the acceleration.

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

[0030] At the equilibrium position of the system, 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 it, we get:

[0033]

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

[0035]

[0036] Similarly, we can get Y C1 , dynamic equations in the θ direction and related natural frequencies.

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

[0038] According to the blade element momentum theory, the relative wind speed, angle of attack, and corresponding lift coefficient and drag coefficient are input into the lift and drag formula to obtain the lift and drag of each blade element.

[0039] Project the lift and drag to the blade's forward and backward swing direction, perform Taylor expansion on the aerodynamic force, and 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 to the blade center of the wind wheel, and the aerodynamic damping contribution η r The expression is as follows:

[0042]

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

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

[0045] Integrate the aerodynamic damping force per unit length about the blade span coordinate to obtain the total aerodynamic damping force, which is expressed as follows:

[0046]

[0047] Among them, r is the radial distance from the hub center of the wind wheel to the blade center, l is the total length of the blade, is the velocity of the center of gravity in the X direction;

[0048] Combining the total aerodynamic damping force with the free vibration equation, the forced vibration equation including the aerodynamic term is obtained, and the expression is as follows:

[0049]

[0050] Then we get the expression:

[0051]

[0052] Where m is the mass of the blade fixture, X C1 is the x coordinate of the end point of point A, is the speed of the blade in the forward and backward swing direction, For speed The acceleration is obtained by differentiating it with respect to time. k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively. The pneumatic damping contribution η r The expression is as follows:

[0053]

[0054] Where c is the blade chord length, ρ is the air density, φ0 is the inflow angle of the blade section when the wind turbine blade is in a stationary state, W0 is the relative inflow velocity, β is the torsion angle, C D (α) is the drag coefficient at the corresponding blade element attack angle α, C L is the lift coefficient, C D is the drag coefficient, C L ′、C′ D 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 differential 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. Combining the forced vibration equation formula (1), the expression of the damping coefficient matrix C can be obtained as follows:

[0059]

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

[0061]

[0062] Among them, ω nis the natural frequency, m is the mass of the blade and the fixture, C is the damping coefficient matrix, the damping coefficient matrix expression (2) and the natural frequency formula are:

[0063]

[0064] Substituting into expression (3), the expression of aerodynamic damping ratio ζ can be obtained as follows:

[0065]

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

[0067]

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

[0069] Furthermore, the aerodynamic damping ratio can be calculated in a discrete manner, and the expression is as follows:

[0070]

[0071] Where l is the length of the blade, Δr is the span length of each blade segment, n is the total number of segments, η ri The aerodynamic damping contribution corresponding to each blade section.

[0072] Furthermore, the method for judging the aeroelastic stability of the hoisting process according to the aerodynamic damping ratio comprises the following steps:

[0073] Based on the calculated pneumatic damping ratio, identify whether the pneumatic 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 in the blade lifting.

[0075] A second aspect of the present invention provides a method for warning the risk of lateral swing of wind turbine blades during hoisting, which uses a method for identifying lateral swing of wind turbine blades during hoisting to calculate the aerodynamic damping ratio, judges the aeroelastic stability of the hoisting process according to the aerodynamic damping ratio, and outputs a corresponding risk warning, comprising the following steps:

[0076] Based on the calculated pneumatic damping ratio, identify whether the pneumatic 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 in the blade lifting.

[0078] A third aspect of the present invention provides a wind turbine blade hoisting lateral swing aerodynamic damping identification system, comprising a memory and a processor, wherein the memory includes a wind turbine blade hoisting lateral swing aerodynamic damping identification method program, and when the wind turbine blade hoisting lateral swing aerodynamic damping identification method program is executed by the processor, a method for identifying the lateral swing aerodynamic damping of a wind turbine blade hoisting is implemented.

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

[0080] The calculation method of the present 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 coefficient for each blade section. Compared with the traditional calculation method, 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 requirements during the operation of wind turbines. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] In order to make the purpose and technical solution of the present invention clearer, the present invention provides the following drawings and descriptions:

[0082] Figure 1 A flow chart of a method provided by an embodiment of the present invention;

[0083] Figure 2 A kinetic analysis diagram provided for an embodiment 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 by an embodiment of the present invention;

[0086] Figure 5 A vibration trend diagram of blade root displacement provided by an embodiment of the present invention; DETAILED DESCRIPTION

[0087] In order to more clearly understand the above-mentioned purpose, features and advantages of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0088] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0089] Embodiment 1:

[0090] The present invention provides a method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation. Figure 1 The figure shows a flow chart of a method for identifying aerodynamic damping of lateral swing of wind turbine blades during hoisting. The specific steps are as follows:

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

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

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

[0094] 2. Yaw angular velocity of blades during hoisting Smaller, corresponding to the simplified model where the yaw coupling effect is ignored;

[0095] 3. Each degree of freedom is independent of each other, namely swing, flap and rotation;

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

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

[0098] The blade fixture is equivalent to a simple pendulum ball, and the lifting rope is equivalent to the rope that pulls the simple pendulum ball, which is simplified into a simple pendulum model for dynamic analysis. The total kinetic energy T and total potential energy V of the simple pendulum system are obtained as follows:

[0099]

[0100] Where m is the mass of the blade plus the fixture, g is the acceleration due to gravity, which is 9.8 m / s, and l is the length of the pendulum rope. represents the rotation angle, is the angular velocity. According to the above formula, the control equation of the simple pendulum system is as follows:

[0101]

[0102] in, is the angular acceleration, l is the length of the pendulum rope, because the rotation angle It's very small, so there are Multiplying both sides of the above formula by mass m gives the expression:

[0103]

[0104] Thus we can get:

[0105]

[0106] According to the above formula, the upper rope can be simplified into a line spring connected to the center of mass, with a spring stiffness of k. During the blade hoisting process, there are two horizontal traction ropes to assist the hoisting operation. Here, the two traction ropes are also simplified into two springs, and their spring stiffnesses are k1 and k2 respectively. The blade hoisting system can be simplified into a planar system with three line springs. The planar system is as follows: Figure 3 shown.

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

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

[0109] According to the motion form of the simplified model, the expressions of the total kinetic energy T and total potential energy V of the system are determined as follows:

[0110]

[0111] Among them, (X C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 ) is the initial point of the plane system A, B, C, θ0 is the initial angle, (X C1 ,YC1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 ) is the end point of A, B, and C after the plane system moves, where the distances of A, B, and C on the X-axis and Y-axis are X AC ,Y AC ,X BC ,Y BC , m is the mass of the blade fixture, I is the moment of inertia of the blade and fixture on the Y axis, θ is the rotation angle, and are the speeds of the blade in the swinging direction and the speeds of the blade in the swinging direction, respectively, indicating that the positions of A and B are rotations relative to point C. is the angular velocity, k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction rope wire rope, and the second traction rope wire rope respectively;

[0112] In dynamic analysis, in order to use the Lagrange equation, it is necessary to first clarify the position and velocity of each particle (or key node) of the system in the global coordinate system. The matrix form of position transformation is the process of converting local coordinates to the global coordinate system, which facilitates the subsequent unified expression of kinetic energy and potential energy in the same coordinate system. The matrix expression of position transformation is as follows:

[0113]

[0114] In the formula, (X C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 ) represents the end points of A, B, and C after the plane system moves, where the distances of A, B, and C on the X-axis and Y-axis represent the X AC ,Y AC ,X BC ,Y BC .

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

[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 is the i-th generalized coordinate, take X C1 , Y C1 Even any point in two-dimensional space, is the derivative of the i-th generalized coordinate with respect to time, that is, the velocity of the generalized coordinate;

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

[0122]

[0123] Since the present invention mainly analyzes the swing direction, q is taken here i =X C1 Conduct analysis.

[0124] T only with Related to, not related to X C1 For this, you can get:

[0125]

[0126] Thus we get:

[0127]

[0128] Among them, L is about X C1 The function of Taking partial derivatives, we can get:

[0129]

[0130] So substituting expressions (4) and (5) into the formula After that, we can get:

[0131]

[0132] is the velocity, which can be differentiated with respect to time to obtain the acceleration You can get:

[0133]

[0134] in, is the potential energy with respect to X C1 Substitute the partial derivative of the linearized X A1 , X B1 , X C1 , ignoring the high-order small quantities, we get:

[0135]

[0136] Substituting it into the Lagrange equation, the expression is as follows:

[0137]

[0138] in, For speed Taking the derivative with respect to time we get the acceleration.

[0139] The natural frequency of the model is calculated using the free vibration equation, which includes the following steps:

[0140] At the equilibrium position of the system, 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 it, we get:

[0143]

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

[0145]

[0146] Similarly, we can get Y C1 , dynamic equations in the θ direction and related natural frequencies.

[0147] S2: The aerodynamic force exerted on the wind turbine blades during the lifting process is Taylor expanded based on the blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length is calculated using the expansion results.

[0148] The specific process is:

[0149] like Figure 4 As shown, it is assumed that when 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 transverse coordinate used to describe the horizontal position of the blade. is the displacement velocity of the blade. When the wind turbine blade vibrates back and forth under the action of wind load, the above values ​​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 section are expressed as follows:

[0154]

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

[0156] Projecting the lift and drag forces to the vibration direction yields:

[0157]

[0158] Where φ is the inflow angle and the twist angle is β. Substituting the above W, φ, and α into the above formula, the aerodynamic force F is about function, and F Taylor expansion is performed at:

[0159]

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

[0161]

[0162] Among them, F0 is the first term of Taylor expansion, is the oscillation velocity of the wind turbine blades due to the wind load during the installation process, which is a high-order small quantity in the expansion formula; η r The symbol used to represent the right side of the above equation, the lift coefficient C L , drag coefficient C D , C L ′、C′ D are the lift coefficient gradient and the drag coefficient gradient, respectively, and their expressions are as follows:

[0163]

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

[0165]

[0166] Where r is the radial distance from the hub center to the blade center of the wind wheel.

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

[0168] The specific process is:

[0169] Integrate the aerodynamic damping force per unit length about the blade span coordinate to obtain the total aerodynamic damping force, which is expressed as follows:

[0170]

[0171] Among them, r is the radial distance from the hub center of the wind wheel to the blade center, l is the total length of the blade, is the speed of the blade in the forward and backward swing direction;

[0172] Combining the total aerodynamic damping force with the free vibration equation, the forced vibration equation including the aerodynamic term is obtained, and the expression is as follows:

[0173]

[0174] Then we get the expression:

[0175]

[0176] Where m is the mass of the blade fixture, X C1 is the x coordinate of the end point of point A, is the speed of the blade in the forward and backward swing direction, For speed The acceleration is obtained by differentiating it with respect to time. k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively. The pneumatic damping contribution η r The expression is as follows:

[0177]

[0178] Where c is the blade chord length, ρ is the air density, φ0 is the inflow angle of the blade section when the wind turbine blade is in a stationary state, W0 is the relative inflow velocity, β is the torsion angle, C D (α) is the drag coefficient at the corresponding blade element attack angle α, C L is the lift coefficient, C D is the drag coefficient, C L ′、C′ D 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 and output the aerodynamic damping ratio.

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

[0181] The general form of the differential 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. Combining the forced vibration equation formula (1), the expression of the damping coefficient matrix C can be obtained as follows:

[0184]

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

[0186]

[0187] Among them, ω n is the natural frequency, m is the mass of the blade and the fixture, C is the damping coefficient matrix, the damping coefficient matrix expression (2) and the natural frequency expression are:

[0188]

[0189] Substituting into expression (3), the expression of aerodynamic damping ratio ζ can be obtained as follows:

[0190]

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

[0192]

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

[0194] More specifically, the aerodynamic damping ratio can be calculated in a discrete manner as follows:

[0195]

[0196] Where l is the length of the blade, Δr is the span length of each blade segment, n is the total number of segments, η ri The aerodynamic damping contribution corresponding to each blade section can be more flexibly handled by discretization, with different airfoil, angle and aerodynamic coefficient differences at different sections of the blade. In this embodiment, the value of n is 19, assuming that the average wind speed is 10m / s and the turbulence intensity is 15.27% during the hoisting process, the inflow angle is φ = 90°, and the torsion angle is β = 90° during the hoisting process. Aerodynamic damping contribution η r The expression is as follows:

[0197]

[0198] First, define the values ​​of the parameters in the formula. The air density is 1.255 kg / m 3 , strictly corresponds to the international standard atmospheric state at sea level (0 meters), the chord length c is divided into 19 sections according to the 10MW model, and the value of each chord length c is stored in the variable array, and the lift coefficient C L , drag coefficient C D , C L ′、C′ D The data corresponding to different leaf types are stored in the variable array program, and the calculation output is 1*19 η i Array. The calculated η i The array is accumulated to get η i The table of values ​​is as follows:

[0199] Table 1

[0200] <![CDATA[η1=211.839039947248]]> <![CDATA[η2=262.454315547705]]> <![CDATA[η3=656.396258792979]]> <![CDATA[η4=1146.82471876690]]> <![CDATA[η5=760.912158990232]]> <![CDATA[η6=770.479780575591]]> <![CDATA[η7=1221.21928845892]]> <![CDATA[η8=723.527279141100]]> <![CDATA[η9=690.305137243342]]> <![CDATA[η 10 =1034.41547825207]]> <![CDATA[η 11 =585.499032073641]]> <![CDATA[η 12 =626.521508992250]]> <![CDATA[η 13 =910.505921091884]]> <![CDATA[η 14 =500.087450256186]]> <![CDATA[η 15 =453.473581664152]]> <![CDATA[η 16 =643.515546145594]]> <![CDATA[η 17 =342.743456302587]]> <![CDATA[η 18 =294.480156240872]]> <![CDATA[η 19 =182.264273086605]]>

[0201]

[0202] Where l is the length of the blade η i is η of different cross sections r The blade is discretized into 19 rigid body segments, each with its own aerodynamic coefficient, so that segmented equivalent processing can be achieved in the dynamic model. Δr is represented by the length of each rigid body segment. Each rigid body segment has a different η i , the variables in the integral formula are r, η i It also changes with r, which is essentially due to the different wing shapes 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] By calculating the upper and lower units of the fraction, it is found that both the upper and lower units of the fraction are kg / s, verifying that the aerodynamic damping ratio is dimensionless.

[0206]

[0207] Here, a is set to an arbitrary constant.

[0208] Judging the aeroelastic stability of the hoisting process according to the aerodynamic damping ratio and outputting corresponding risk warnings includes the following steps:

[0209] Based on the calculated pneumatic damping ratio, identify whether the pneumatic 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 in the blade lifting.

[0211] In this embodiment, the calculation result is 0.1%. When the aerodynamic damping ratio of the wind turbine blade is 0.1% (i.e. 0.001) during the hoisting process, although this value is within a reasonable range (usually 0.01% to 0.1%) in the hoisting condition, in order to verify whether it conforms to the trend, the vibration trend of the blade root displacement under the turbulent wind conditions with an average wind speed of 10m / s and a turbulence intensity of 15.27% is as follows: Figure 5 As shown, the blades exhibit continuous small vibrations under wind loads, and the amplitude decays slowly. The calculation method of the present invention does not rely on extremely complex real-time wind data. By simplifying conditions and models, it avoids the tedious calculation of wind speed, angle of attack, and lift-drag coefficient 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, which is particularly suitable for the frequent aerodynamic damping calculation requirements during the operation of wind turbines.

[0212] Embodiment 2:

[0213] The present embodiment provides a system for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting, comprising a memory and a processor, wherein the memory comprises a method program for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting, and when the method program for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting is executed by the processor, the steps of a method for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting as described in Example 1 are implemented.

[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 embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation, characterized in that: The following steps are involved: Based on the preset simplified conditions, the three-wire spring blade hoisting model is used to combine the stiffness parameters of the main hoisting rope and two horizontal auxiliary traction ropes to output the free vibration equation of the wind turbine blade hoisting system, and the natural frequency of the model is calculated using the free vibration equation. The aerodynamic force on the wind turbine blades during the installation process is Taylor expanded using blade element momentum theory and aerodynamic parameters, and the aerodynamic damping force per unit length is calculated using the expansion results. Integrate the aerodynamic damping force per unit length in the span direction of the blade, input the integral result into the free vibration equation, and output the forced vibration equation under the action of wind load; The natural frequency of the model is combined with the forced vibration equation to output the aerodynamic damping ratio.

2. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 1, characterized in that: The preset simplified conditions include: The position of the crane top is considered to remain unchanged during the lifting process; During the hoisting process, the blade yaw angular velocity is small, and the yaw coupling effect is ignored in the corresponding simplified model; Each degree of freedom is independent of each other, namely shimmy, flapping, and rotation; The motions of the center of mass of the simplified model in different degrees of freedom are independent.

3. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 1, characterized in that: The method for calculating the free vibration equation of the wind turbine blade hoisting system includes the following steps: The lifting blade and its fixture are regarded as a lumped mass, the main lifting rope and two horizontal auxiliary traction ropes are simplified into three wire springs, the spring stiffness parameters of each are obtained, and a simplified model of three-wire spring blade lifting is established. According to the motion form of the simplified model, the expressions of the total kinetic energy T and total potential energy V of the system are determined as follows: Among them, (X C0 ,Y C0 ),(X A0 ,Y A0 ),(X B0 ,Y B0 ) is the initial point of the plane system A, B, C, θ0 is the initial angle, (X C1 ,Y C1 ),(X A1 ,Y A1 ),(X B1 ,Y B1 ) is the end point of A, B, and C after the plane system moves, where the distances of A, B, and C on the X-axis and Y-axis are X AC ,Y AC ,X BC ,Y BC , m is the mass of the blade fixture, I is the moment of inertia of the blade and fixture on the Y axis, θ is the rotation angle, and are the speeds of the blade in the swinging direction and the speeds of the blade in the swinging direction, respectively, indicating that the positions of A and B are rotations relative to point C. is the angular velocity of rotation, k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction rope wire rope, and the second traction rope 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 is the i-th generalized coordinate, take X C1 , Y C1 Even any point in two-dimensional space, is the derivative of the i-th generalized coordinate with respect to time, that is, the velocity of the generalized coordinate; Substituting the expressions of total kinetic energy and total potential energy into the Lagrange equation, we get the free vibration equation in the swing direction, which is as follows: in, For speed Taking the derivative with respect to time we get the acceleration.

4. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 3, characterized in that: The natural frequency of the model is calculated using the free vibration equation, which includes the following steps: At the equilibrium position of the system, 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 it, we get: From the above formula, we can get the simplified model of wind turbine hoisting system: C1 The directional natural frequency is: Similarly, we can get Y C1 , dynamic equations in the θ direction and related natural frequencies.

5. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 1, characterized in that: The method for calculating the aerodynamic damping force per unit length comprises the following steps: According to the blade element momentum theory, the relative wind speed, angle of attack, and corresponding lift coefficient and drag coefficient are input into the lift and drag formula to obtain the lift and drag of each blade element. Project the lift and drag to the blade's forward and backward swing direction, perform Taylor expansion on the aerodynamic force, and obtain the aerodynamic damping force per unit length. The expression is as follows: Where r is the radial distance from the hub center to the blade center of the wind wheel, and the aerodynamic damping contribution η r The expression is as follows: Where c is the blade chord length, ρ is the air density, φ0 is the inflow angle of the blade section when the wind turbine blade is in a stationary state, W0 is the relative inflow velocity, β is the torsion angle, C D (α) is the drag coefficient at the corresponding blade element attack angle α, C L is the lift coefficient, C D is the drag coefficient, C′ L , C′ D are the lift coefficient gradient and the drag coefficient gradient respectively.

6. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 1, characterized in that: The method of outputting the forced vibration equation under the action of wind load by using the aerodynamic damping force per unit length comprises the following steps: Integrate the aerodynamic damping force per unit length about the blade span coordinate to obtain the total aerodynamic damping force, which is expressed as follows: Among them, r is the radial distance from the hub center of the wind wheel to the blade center, l is the total length of the blade, is the speed of the blade in the forward and backward swing direction; Combining the total aerodynamic damping force with the free vibration equation, the forced vibration equation including the aerodynamic term is obtained, and the expression is as follows: Then we get the expression: Where m is the mass of the blade fixture, X C1 is the x coordinate of the end point of point A, is the speed of the blade in the forward and backward swing direction, For speed The acceleration is obtained by differentiating it with respect to time. k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, respectively. The pneumatic damping contribution η r The expression is as follows: Where c is the blade chord length, ρ is the air density, φ0 is the inflow angle of the blade section when the wind turbine blade is in a stationary state, W0 is the relative inflow velocity, β is the torsion angle, C D (α) is the drag coefficient at the corresponding blade element attack angle α, C L is the lift coefficient, C D is the drag coefficient, C′ L , C′ D are the lift coefficient gradient and the drag coefficient gradient respectively.

7. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 6, characterized in that: The calculation of the aerodynamic damping ratio ζ of the wind turbine blade hoisting using the natural frequency and forced vibration equation includes the following steps: The general form of the differential 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. Combining the forced vibration equation formula (1), the expression of the damping coefficient matrix C can be obtained as follows: The general form of the aerodynamic damping ratio is as follows: Among them, ω n is the natural frequency, m is the mass of the blade and the fixture, C is the damping coefficient matrix, the damping coefficient matrix expression (2) and the natural frequency formula are: Substituting into expression (3), the expression of aerodynamic damping ratio ζ can be obtained as follows: Where r is the radial distance from the hub center of the wind wheel to the center of the blade element, k, k1, k2 are the spring stiffness of the main sling wire rope, the first traction wire rope, and the second traction wire rope, m is the mass of the blade fixture, l is the total length of the blade, and the aerodynamic damping contribution η r The expression is as follows: Where c is the blade chord length, ρ is the air density, φ0 is the inflow angle of the blade section when the wind turbine blade is in a stationary state, W0 is the relative inflow velocity, β is the torsion angle, C D (α) is the drag coefficient at the corresponding blade element attack angle α, C L is the lift coefficient, C D is the drag coefficient, C′ L , C′ D are the lift coefficient gradient and the drag coefficient gradient respectively.

8. A method for identifying aerodynamic damping of lateral swing of wind turbine blades during installation according to claim 7, characterized in that: The aerodynamic damping ratio can be calculated in a discrete manner as follows: Where l is the length of the blade, Δr is the span length of each blade segment, n is the total number of segments, η ri The aerodynamic damping contribution corresponding to each blade section.

9. A method for warning the risk of lateral swing of wind turbine blades during installation, using the method for identifying lateral swing of wind turbine blades during installation according to any one of claims 1 to 8 to calculate the aerodynamic damping ratio, judging the aeroelastic stability of the installation process according to the aerodynamic damping ratio, and outputting a corresponding risk warning, comprising the following steps: Based on the calculated pneumatic damping ratio, identify whether the pneumatic 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 in the blade lifting.

10. A wind turbine blade hoisting lateral swing aerodynamic damping identification system, characterized in that: The system includes: a memory and a processor, wherein the memory includes a method program for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting. When the method program for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting is executed by the processor, the steps of a method for identifying aerodynamic damping of lateral swing of wind turbine blade hoisting as described in any one of claims 1 to 8 are implemented.

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