Climbing rate calculation method of wind power variable pitch bearing

Abstract

The invention belongs to the technical field of bearings, and particularly relates to a ramp rate calculation method of a wind power variable pitch bearing. The method comprises the following steps: S1, establishing and solving an integral model of the wind power variable pitch bearing to obtain the displacement of a roller of the variable pitch bearing in each coordinate axis direction; applying constraint to a roller of the variable pitch bearing in the form of a spring unit, a rod unit or a beam unit so as to simulate Hertz contact between the roller and a raceway; s2, taking displacement of a roller of the variable-pitch bearing in each coordinate axis direction as a boundary condition, cutting a variable-pitch bearing part from the wind power variable-pitch bearing integral model, encrypting a grid to obtain a sub-model, and solving the sub-model to obtain contact stress distribution between the roller of the variable-pitch bearing and a raceway; and S3, determining a contact ellipse between the roller and the raceway according to the contact stress distribution, and taking the cut-off rate of the contact ellipse as the ramp rate of the variable pitch bearing. According to the method, the technical problem that the calculation error of the climbing rate in the existing variable-pitch bearing checking calculation is relatively large is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of bearings, and particularly relates to a method for calculating the climbing rate of a wind power pitch bearing. Background Technique

[0002] The bearing is a key load-bearing and supporting component in the wind turbine and is one of the core components for realizing the functions of the wind turbine. The failure of the bearing not only affects the normal operation of the wind turbine, but also results in relatively high maintenance costs. The four-point ball pitch bearing applied to the pitch system of the wind turbine mainly functions to adjust the angle of the wind turbine blade to adapt to different wind speed conditions, thereby maintaining the stable power output of the wind turbine unit. Existing research has shown that in the structural design of the bearing, the contact angle is an important structural parameter of the bearing. The change of the contact angle has an obvious effect on improving the bearing capacity and prolonging the bearing life. However, an excessive designed contact angle may lead to too high a climbing rate of the contact shoulder, causing the bearing climbing problem, thereby resulting in the risk of premature failure of the bearing at the shoulder position. Therefore, a reasonable initial designed contact angle is selected to avoid the bearing climbing problem under the action of the ultimate load.

[0003] For the check calculation of the pitch bearing, generally there are two methods: engineering check calculation and finite element simulation analysis. The engineering check is based on the Hertz contact theory, assuming that the inner and outer rings are rigid bodies, and only the local contact deformation of the roller and the average contact stress between the roller and the raceway can be obtained, and the overall deformation of the bearing and the force condition of the bearing under flexible support cannot be analyzed.

[0004] In the finite element simulation analysis, usually the bearing is simplified, and a super element composed of spring elements and rigid beams is used to simulate the contact problem between the roller and the raceway. This method avoids the problem of difficult convergence in contact analysis, but the calculation accuracy is difficult to guarantee. Since the friction in the tangential and normal directions between the roller and the raceway cannot be considered, the contact behavior between the roller and the raceway cannot be accurately simulated, and there is a large error between the calculated climbing rate and the real model. Summary of the Invention

[0005] The purpose of the invention is to provide a method for calculating the climbing rate of a wind power pitch bearing to solve the technical problem of large calculation error of the climbing rate in the existing check calculation of the pitch bearing.

[0006] To solve the above technical problem, the technical solution of a method for calculating the climbing rate of a wind power pitch bearing provided by the invention is as follows: A method for calculating the climbing rate of a wind power pitch bearing, the method includes: S1. Establish an overall model of the wind power pitch bearing and solve the overall model of the wind power pitch bearing to obtain the displacements of the rollers of the pitch bearing in each coordinate axis direction; The overall model of the wind power pitch bearing includes a pitch bearing, blades, and a hub. In the overall model of the wind power pitch bearing, constraints are applied to the rollers of the pitch bearing in the form of spring elements, rod elements, or beam elements, so as to simulate the Hertz contact between the rollers and the raceways of the pitch bearing. S2. Taking the displacements of the rollers of the pitch bearing in each coordinate axis direction as boundary conditions, cutting out the pitch bearing part from the overall model of the wind power pitch bearing, densifying the mesh to obtain a sub-model, and solving the sub-model to obtain the contact stress distribution between the rollers and the raceways of the pitch bearing. S3. Determining the contact ellipse between the rollers and the raceways according to the contact stress distribution, and taking the truncation rate of the contact ellipse as the climbing rate of the pitch bearing.

[0007] The beneficial effects of the above technical solution are as follows: The technical solution of the climbing rate calculation method for a wind power pitch bearing of the present invention belongs to an improved invention. The present invention applies constraints to the rollers modeled as flexible bodies in the form of spring elements, rod elements, or beam elements to more realistically simulate the contact between the rollers and the raceways. The present invention can more realistically simulate the contact behavior between the rollers and the raceways, consider the tangential and normal friction between the rollers and the raceways, and achieve an infinite approximation to the Hertz classical contact theory of the elastic approach amount between the rollers and the raceways by adjusting the contact stiffness between the rollers and the raceways, so that the data for calculating the climbing rate is closer to the actual situation in the end, and the calculation accuracy is greatly improved. The present invention solves the technical problem of large calculation errors in the climbing rate calculation in the existing pitch bearing calibration calculation.

[0008] Further, the truncation rate of the contact ellipse is obtained in the following manner: taking the ratio of the truncation amount of the contact ellipse in the major axis direction to the major axis of the ellipse as the truncation rate of the contact ellipse.

[0009] Further, the truncation amount Δ of the contact ellipse in the major axis direction x is calculated according to the following formula: where a is the semi-major axis of the contact ellipse; X 1 is the distance between the center point of the contact ellipse and the outer shoulder of the raceway in the chord length direction; X 2 is the distance between the center point of the contact ellipse and the inner shoulder of the raceway in the chord length direction.

[0010] Further, the X 1 and X 2 are obtained in the following manner: Extract the spatial coordinates of the contact points between the rollers and the raceways in the sub-model, and fit the spatial coordinates of the contact points to obtain the raceway profile curve; Mark the center and boundary of the contact ellipse on the raceway profile curve, and measure in AutoCAD to obtain X ​1 and X 2.

[0011] Furthermore, the spatial coordinates of the contact points are fitted by a parabolic curve to obtain the raceway profile curve.

[0012] Furthermore, the blade prosthesis of the blade is made of a non-linear material; the components other than the blade prosthesis of the blade are made of a linearly elastic material.

[0013] Furthermore, the process of solving the overall model of the wind power pitch bearing includes: applying the maximum pre-tightening force to the bolts for connecting the pitch bearing to the hub and the bolts for connecting the pitch bearing to the blade; applying the ultimate load to the pitch bearing based on the maximum pre-tightening force to obtain the displacements of the rollers of the pitch bearing in the directions of the respective coordinate axes of the finite element model of the pitch bearing under the ultimate load.

[0014] Furthermore, the bolts for connecting the pitch bearing to the hub and the bolts for connecting the pitch bearing to the blade are modeled by the beam element beam188, and the cross-sectional properties of the beam element beam188 are defined to simulate the threaded and smooth rod parts of the bolts.

[0015] Furthermore, in the overall model of the wind power pitch bearing, the mesh size of the hub is lower than the mesh sizes of the pitch bearing and the blade.

[0016] Furthermore, the ultimate load is the ultimate load at the main node; the main node is set at the center of the root of each blade, and the main node is connected to the upper end face node of the root by the beam element beam188 so that the load at the main node can be transmitted to the entire blade. Description of the Drawings

[0017] Figure 1 is the flowchart of the method according to the embodiment of the present invention; Figure 2 is the schematic diagram of constraint loading of the overall analysis model in the embodiment of the present invention; Figure 3 is the schematic diagram of the local mesh of the pitch bearing in the embodiment of the present invention; Figure 4 is the schematic diagram of the bolt connection in the embodiment of the present invention; Figure 5 is the schematic diagram of the roller constraint in the embodiment of the present invention; Figure 6 is the contact stress nephogram of the rollers of the pitch bearing in the embodiment of the present invention; Figure 7 is the schematic diagram of the sub-model in the embodiment of the present invention; Figure 8 is the contact stress nephogram of the sub-model in the embodiment of the present invention; Figure 9Schematic diagram for calculating the climbing rate of the bearing in the embodiment of the present invention.

[0018] Wherein, 1. Blade prosthesis; 2. Inner ring bolt; 3. Blade flange; 4. Roller; 5. Bearing outer ring; 6. Outer ring bolt; 7. Hub; 8. Gear; 9. Bearing inner ring. Specific implementation manner

[0019] The present invention applies constraints to the roller modeled as a flexible body in the form of a spring element, a rod element or a beam element to more realistically simulate the contact between the roller and the raceway. The present invention can more realistically simulate the contact behavior between the roller and the raceway, consider the tangential and normal friction between the roller and the raceway, and achieve an infinite approximation to the Hertzian contact theory of the elastic approach amount between the roller and the raceway by adjusting the contact stiffness between the roller and the raceway, so that the data for calculating the climbing rate is closer to the actual situation in the end, and the calculation accuracy is greatly improved. The present invention solves the technical problem of large calculation error of the climbing rate in the existing pitch bearing calibration calculation.

[0020] Embodiment of the method for calculating the climbing rate of a wind power pitch bearing: As Figure 1 shown, a method for calculating the climbing rate of a wind power pitch bearing, the method includes: S1. Establish an overall model of the wind power pitch bearing and solve the overall model of the wind power pitch bearing to obtain the displacements of the rollers of the pitch bearing in each coordinate axis direction; The overall model of the wind power pitch bearing includes a pitch bearing, a blade and a hub; by applying constraints to the rollers of the pitch bearing in the form of spring elements, rod elements or beam elements in the overall model of the wind power pitch bearing, the Hertzian contact between the rollers and the raceways of the pitch bearing can be simulated; S2. Take the displacements of the rollers of the pitch bearing in each coordinate axis direction as boundary conditions, cut out the pitch bearing part from the overall model of the wind power pitch bearing and densify the mesh to obtain a sub-model, and solve the sub-model to obtain the contact stress distribution between the rollers and the raceways of the pitch bearing; S3. Determine the contact ellipse between the roller and the raceway according to the contact stress distribution, and take the truncation rate of the contact ellipse as the climbing rate of the pitch bearing.

[0021] Specifically, the method for calculating the climbing rate of the wind power pitch bearing in this embodiment includes the following steps: (1) The overall model of the wind power pitch bearing (i.e., the multi-blade overall finite element model, which is three blades in this embodiment) is as Figure 3As shown in the figure, taking the blade as an example, the model consists of components such as the inner ring bolts 2, outer ring bolts 6, gears 8, pitch bearings, hubs 7, and blades. The pitch bearing includes rollers 4, bearing inner rings 9, and bearing outer rings 5. The bearing inner ring 9 and the bearing outer ring 5 form a four-point contact area with the rollers 4, respectively forming the inner and outer contact raceways of the bearing. The blade includes a blade prosthesis 1 and a blade flange 3. The pitch bearing is connected to the hub 7 through the outer ring bolts 6, and the pitch bearing is connected to the blade through the inner ring bolts 2. First, use the 3D software SolidWorks to build the model and complete the assembly.

[0022] (2)Establish materials: Conduct a combined simulation analysis of HyperMesh and ANSYS. The pre-processing is completed in the HYPERMESH software. Import the 3D model established in SolidWorks and establish material properties in the materials module of HYPERMESH.

[0023] 1) Right-click on the blank space under the Model model tree and select Create→Material, and name it "STEEL-BEARING". Click on "STEEL-BEARING", change the Young's modulus to "205000"; set the major Poisson's ratio to "0.3". Keep other options default. This material corresponds to the bearing and bolt components.

[0024] 2) Right-click on the blank space under the Model model tree and select Create→Material, and name it "STEEL-BLADE". Click on "STEEL-BLADE" and set the material parameters of the non-linear material. The radial Young's modulus is "13500", the circumferential Young's modulus is "11000", the axial Young's modulus is "29000", the radial / circumferential Poisson's ratio is "0.3", the axial / radial Poisson's ratio is "0.3", the axial / circumferential Poisson's ratio is "0.47", the radial / circumferential shear modulus is "4000", the axial / radial shear modulus is "4000", and the axial / circumferential shear modulus is "6600". Keep other options default. This material corresponds to the blade component.

[0025] 3) Right-click on the blank space under the Model model tree and select Create→Material, and name it "STEEL-HUB". Click on "STEEL-HUB", change the Young's modulus to "169000"; set the major Poisson's ratio to "0.3". Keep other options default. This material corresponds to the hub component.

[0026] 4) Right-click on the blank space under the Model tree, select Create → Material, and name it "STEEL-FLANGE". Click on "STEEL-FLANGE" and change the Young's modulus to "206000"; set the primary Poisson's ratio to "0.3". Keep other options default. This material corresponds to the flange component.

[0027] (3) Use finite element preprocessing software to mesh the 3D geometric model: Among them, it includes: The hub is meshed using the ten-node tetrahedral element solid187; the remaining components except the hub (such as gears, inner bearing rings, outer bearing rings, rollers, blade flanges, blade prostheses, etc.) are all simulated using regular twenty-node hexahedral elements solid186.

[0028] (4) Use finite element preprocessing software to define relevant contact pairs according to the actual contact relationship between adjacent components and establish a finite element model. Frictional contact is set between the outer bearing ring 5 and the hub 7, between the blade flange 3 and the blade root part, and between the blade flange 3 and the inner bearing ring 9. The contact relationship between the remaining components is set as bonded contact.

[0029] In surface-to-surface contact, the TARGE170 element is used to simulate the target surface, and the 174 element is used to simulate the contact surface. The specific operation of establishing the contact relationship in HYPERMESH software is as follows: 1) Right-click on the blank space under the Model tree, select → Sensor, and rename it conta174. Since the solid186 element is used for the previous solid elements, the contact element and the target element are respectively selected as contact174 and targe170.

[0030] 2) Right-click on the blank space under the Model tree, select → Property, name them conta174p and targe170p respectively, and set the Card Image to conta174p and targe170p respectively. Establish two element types respectively, namely the contact element and the target element.

[0031] 3) Right-click on the blank space under the Model tree, select → contact, a new Group will be added and a new contact pair will be automatically added. Left-click on the contact pair and set the items that need to be set in the display below. MASTER is the information related to the contact that needs to be selected, and SLAVE is the information related to the target that needs to be selected, which are the contact surface set and the element type, the target surface set and the target element type, and the contact characteristics respectively.

[0032] 4) Switch to the Contact column, and under the contact pair, switch the contact type to Standard, which is equivalent to the friction contact type. Set the friction coefficient to 0.2, and set all other contact settings to the default.

[0033] 5) Set the surface-to-surface contacts between the roller and the raceway, the blade flange and the inner ring of the bearing, and the outer ring of the bearing and the hub respectively.

[0034] (5) The connecting bolts between the pitch bearing and the hub 7 (i.e., the inner ring bolts 2) and the connecting bolts between the pitch bearing and the blade (i.e., the outer ring bolts 6) are modeled using beam element beam188, and the threaded parts and the smooth rod parts of the inner ring bolts 2 and the outer ring bolts 6 are simulated by defining the cross-sectional properties of the beam element beam188; the meshing between the thread and the screw rod is achieved by rigid coupling of the beam element with the surrounding nodes.

[0035] The steps for constructing the bolt connection are as follows: Right-click in the blank area under the Model tree, select Create → component, and name it "beam". Construct the beam element under this component. Right-click in the blank area under the Model tree, select Create → component, and name it "rigid". Construct the rigid coupling element under this component.

[0036] 1) The establishment of the beam element is operated according to the following steps: Establish the beam element under the 1D panel, and ensure that there are at least three nodes for defining the beam element. Enter the creation page, select one of the nodes for a and another for b, and note that the orientation below needs to be selected in a direction different from the two nodes.

[0037] 2) The establishment of the cross-section of the beam element (beam188). Right-click on beamsection in the blank area of the model tree. The default parameter is to generate a circular cross-section for the beam element, and the diameter of the beam element cross-section is 10. The beam element cross-section can be modified as needed.

[0038] 3) The establishment of the beam element (beam188). Right-click on sensors in the blank area of the model tree, and create the beam188 element under elementtype.

[0039] 4) The establishment of the properties of the beam element (beam188). Right-click on properties in the blank area of the model tree. Select SECTYPE in the Card Image of this card, and select the cross-section beam established in the previous step under hyperbeam section. Make the cross-sectional properties of the beam element associated.

[0040] 5) Assign materials, elements, and properties to the beam components. Select the previously created beam elements, materials, and properties under the beam components and associate them.

[0041] 6) Set the rigid component to the current group and place the rigid coupling constraints between the beam element endpoints and the bolt holes generated in the following operations in this group.

[0042] As a preferred implementation, a beam element can be constructed at the bolt hole position, and the beam elements at other positions are realized through circular array in the circumferential coordinate system.

[0043] 7) Couple the two endpoints of the beam element with the bolt hole. One end of the bolt forms a main node by connecting to one endpoint of the beam element and couples with multiple nodes of the bolt hole to form an umbrella structure. The other end of the bolt also forms a main node by connecting to one endpoint of the beam element and couples with multiple nodes of the bolt hole to form an umbrella structure.

[0044] 8) As a preferred implementation, the circular array in the circumferential direction can be realized using the TCL scripting language of HYPERMESH, which can not only reduce human operation errors but also improve work efficiency.

[0045] 9) Application of bolt pre-tightening force. For the pitch bearing bolt pre-tightening force, a pre-tightening force element (i.e., PRETS179 element) is usually inserted at the middle node of the 1D element (BEAM188).

[0046] 10) HYPERMESH realizes it in the 1D beam element in the pretention type under the tool, pretention bolt menu. Automatically add bolt pre-tightening force elements by manually picking the common nodes of the two beam elements of the bolt. Through this step of operation, the finally formed bolt connection structure is as Figure 4 shown. Add bolt pre-tightening force in the SLOAD card under the CARDS card of HYPERMESH.

[0047] Simplify the bolt connection into a spider-web-like rigid connection structure. The core idea is to simulate each installed bolt with two beam elements connected end to end (i.e., Figure 4 the two beam188 beam elements in it). The parameters of the beam elements (area, moment of inertia, elastic modulus, etc.) are determined according to the actual bolt calculation. Apply a pre-tightening force load at the center node of the beam188 beam element, and load it in two steps along the bolt axis: the first step is to apply the pre-tightening force, and the second step is to lock the displacement. The head and tail nodes of the beam188 beam element are respectively coupled with the bolt hole nodes on the bearing end face and the bolt hole nodes of the connecting piece, respectively, to simulate the nut and the threaded hole.

[0048] (6)Apply a weak spring constraint to the roller to limit the rigid body displacement so as to be able to simulate the Hertz contact between the roller and the raceway of the pitch bearing. This is achieved by constructing three grounding springs (combine14) in the X, Y, and Z directions respectively. Taking the establishment of the weak spring in the X direction as an example, the establishment steps are as follows: 1) The method for establishing the combine14 spring element. Establish the spring element under the 1D panel, ensuring that there are two nodes, and select I and J for the two nodes respectively.

[0049] 2) Establish the spring element (combine14). Right-click on sensors in the blank area of the model tree, and create the combine14 element under element type. Set the X-direction stiffness in Keyopt2 option 1. Different parameter settings are made for the Y and Z directions in this option. 3) Establish the real constant of the spring element (combine14). Right-click on properties in the blank area of the model tree, select combine14 in the Card Image of this card to associate it with the X-direction spring element properties. The roller constraint is as Figure 5 shown.

[0050] In other embodiments, a unit with relatively weak rigidity such as a rod element or a beam element can also be used as the constraint applied to the roller.

[0051] (7)Fully constrain all degrees of freedom of the nodes on the rear end face of the spindle prosthesis part as the main constraint of the relevant degrees of freedom. Set a main node at the center of the root part of each of the 3 blades respectively, and connect it to the upper end face node of the root part of the blade through the rigid beam element beam188 to transfer the ultimate loads at the roots of the 3 blades to the 3 blades, where the ultimate loads are the ultimate loads at the centers of the root parts of the 3 blades. The bearing constraint and loading are as Figure 2 shown.

[0052] (8)Solve to obtain the displacements of the roller in the X, Y, and Z directions. View the results through the post-processing software. The contact effect between the roller and the raceway is as Figure 6 shown. A contact patch is formed in the contact area between the roller and the raceway, and the contact patch gradually decreases from the bearing load-bearing area to the non-load-bearing area, which is consistent with the test law.

[0053] (9)Submodel analysis, the operation steps are as follows.

[0054] Step 1, generate and analyze a relatively rough model on the basis of the above operations. Conduct an overall analysis with ansys, generally dividing the mesh relatively sparsely. After the calculation is completed, generate the fullmodel.db and fullmodel.rst files.

[0055] Step 2: Create a submodel with a relatively fine mesh (i.e., the finite element model of the pitch bearing) and save the submodel database. The submodel is a local area model cut from the overall model, with a finer mesh re-divided. The submodel only includes the pitch bearing part, namely the roller 4, the bearing inner ring 9, and the bearing outer ring 5, ignoring components such as the blade, flange, and hub. The bearing inner ring 9 and the bearing outer ring 5 form a four-point contact area with the roller 4, respectively forming the inner and outer contact raceways of the bearing.

[0056] The created submodel is as shown in Figure 7 . The boundary conditions of the submodel are to solve for the displacements of the roller in the X, Y, and Z directions from the overall model, and write the nodes on the cutting boundary of the submodel into the node file (model.node). The specific implementation method is as follows: Main Menu→Preprocessor→Create→Nodes→Write Node File Step 3: Generate a displacement interpolation load definition file (model.cbdo) for the nodes on the cutting boundary of the submodel based on the calculation results of the overall model and the cutting boundary node file.

[0057] Step 4: Perform submodel analysis and calculation. It is necessary to read in the displacement interpolation load definition file (model.cbdo) for the nodes on the cutting boundary of the submodel, define the settings for the analysis and calculation load steps, and perform the solution to obtain the contact stress distribution between the roller and the raceway near the shoulder of the pitch bearing raceway. The results are as shown in Figure 8 .

[0058] (10) Calculation method for the climbing rate of the roller and the raceway.

[0059] Define the percentage of the contact ellipse truncation amount near the shoulder of the raceway to the total ellipse length (i.e., the major axis of the ellipse) as the climbing rate. Its calculation method is carried out according to the following steps: 1) Extract the spatial coordinates of the contact point and the contact stress, and through secondary development in AutoCAD, develop a macro program for multi-point regression to construct the raceway arc profile.

[0060] Specifically, the spatial coordinates of the contact point are fitted with a parabolic curve to obtain the raceway arc profile.

[0061] 2) Determine the center and boundary of the contact ellipse through the contact stress, and mark them on the constructed arc curve (i.e., the parabola obtained by the above fitting).

[0062] 3) As shown in Figure 9 , according to the raceway arc profile obtained in 1), measure in AutoCAD a , X 1 and X2; Calculate the elliptical truncation rate (i.e., the bearing climbing rate) according to the following formula: where f is the bearing climbing rate; a is the major semi - axis of the contact ellipse; X 1 is the distance between the center point of the contact ellipse and the outer shoulder of the raceway in the chord length direction; X 2 is the distance between the center point of the contact ellipse and the inner shoulder of the raceway in the chord length direction; Δ x is the elliptical truncation amount.

[0063] When the ellipse overlaps with the edge of the raceway (Δ x > 0), the truncation is positive, and the positive value of the truncation indicates that truncation occurs.

[0064] When the ellipse falls within the edge of the raceway (Δ x ≤ 0), the truncation is negative, and the negative value of the truncation indicates that there is no truncation.

[0065] The present invention has the following characteristics: The present invention applies constraints to the rollers in the form of spring units to more realistically simulate the contact between the rollers and the raceways. The present invention can more realistically simulate the contact behavior between the rollers and the raceways, consider the tangential and normal friction between the rollers and the raceways, and achieve an infinite approximation to the Hertz classical contact theory of the elastic approach amount between the rollers and the raceways by adjusting the contact stiffness between the rollers and the raceways, making the data for calculating the climbing rate closer to the actual situation and greatly improving the calculation accuracy.

[0066] Finally, it should be noted that the above - mentioned are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still make modifications to the technical solutions recorded in the foregoing embodiments without creative efforts, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for calculating the climbing rate of a wind power pitch bearing, characterized in that, The method includes: S1. Establish an overall model of the wind turbine pitch bearing, solve the overall model of the wind turbine pitch bearing, and obtain the displacements of the rollers of the pitch bearing in the directions of each coordinate axis; The overall model of the wind turbine pitch bearing includes a pitch bearing, a blade, and a hub; in the overall model of the wind turbine pitch bearing, constraints are applied to the rollers of the pitch bearing in the form of spring elements, rod elements, or beam elements to simulate the Hertz contact between the rollers and the raceways of the pitch bearing; S2. Using the displacements of the rollers of the pitch bearing in the directions of each coordinate axis as boundary conditions, cut out the pitch bearing part from the overall model of the wind turbine pitch bearing, densify the mesh to obtain a sub-model, and solve the sub-model to obtain the contact stress distribution between the rollers and the raceways of the pitch bearing; S3. Determine the contact ellipse between the rollers and the raceways according to the contact stress distribution, and use the truncation rate of the contact ellipse as the climbing rate of the pitch bearing.

2. The method for calculating the climbing rate of the wind power pitch bearing according to claim 1, wherein The truncation rate of the contact ellipse is obtained in the following way: taking the ratio of the truncation amount of the contact ellipse in the major axis direction to the major axis of the ellipse as the truncation rate of the contact ellipse.

3. The method for calculating the climbing rate of the wind power pitch bearing according to claim 2, wherein, The truncation amount Δ of the contact ellipse in the major axis direction x is calculated according to the following formula: Among them, a is the major semi-axis of the contact ellipse; X 1 is the distance between the center point of the contact ellipse and the outer shoulder of the raceway in the chord length direction; X 2 is the distance between the center point of the contact ellipse and the inner shoulder of the raceway in the chord length direction.

4. The method for calculating the climbing rate of a wind power pitch bearing according to claim 3, characterized in that The said X 1 and X 2 are obtained according to the following method: Extract the spatial coordinates of the contact points between the rollers and the raceways in the sub-model, and fit the spatial coordinates of the contact points to obtain the raceway profile curve; mark the center and boundary of the contact ellipse on the raceway profile curve, and measure in AutoCAD to obtain X 1 and X 2.

5. The method for calculating the climbing rate of a wind power pitch bearing according to claim 4, characterized in that, The spatial coordinates of the contact points are fitted by a parabolic curve to obtain the raceway profile curve.

6. The method for calculating the climbing rate of the wind power pitch bearing according to claim 1, characterized in that The blade prosthesis of the blade is a non-linear material; components other than the blade prosthesis of the blade are set as linear elastic materials.

7. The method for calculating the climbing rate of the wind power pitch bearing according to claim 1, characterized in that, The process of solving the overall model of the wind turbine pitch bearing includes: applying the maximum pre-tightening force to the bolts for connecting the pitch bearing and the hub and the bolts for connecting the pitch bearing and the blade; applying a limit load to the pitch bearing based on the maximum pre-tightening force to obtain the displacements of the rollers of the pitch bearing in the directions of each coordinate axis of the finite element model of the pitch bearing under the limit load.

8. The method for calculating the climbing rate of the wind power pitch bearing according to claim 1, wherein The bolts for connecting the pitch bearing and the hub and the bolts for connecting the pitch bearing and the blade are modeled by beam element beam188, and the cross-sectional properties of the beam element beam188 are defined to simulate the threaded and plain rod parts of the bolts.

9. The method for calculating the climbing rate of the wind power pitch bearing according to claim 1, wherein In the overall model of the wind turbine pitch bearing, the mesh size of the hub is lower than the mesh sizes of the pitch bearing and the blade.

10. The method for calculating the climbing rate of the pitch bearing of a wind turbine according to claim 7, wherein The limit load is the limit load at the master node; the master node is set at the center of the root of each blade, and the master node is connected to the upper end face node of the root by beam element beam188 so that the load at the master node can be transmitted to the entire blade.

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