Simulation and evaluation method of lightning attachment point on wind turbine blades

Abstract

The wind turbine blade lightning attachment point simulation evaluation method disclosed in the present invention comprises the following steps: step 1, importing a three-dimensional blade model and optimizing the model; step 2, setting the material parameters of the model; step 3, establishing a flat plate discharge structure according to the model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the model; step 4, setting the physical boundary of the air domain; step 5, meshing the model in terms of surface, volume and space; step 6, simulating and calculating the divided model in COMSOL software, calculating the induced electric field under different postures of the blade, and obtaining a distribution cloud map of the electric field intensity on the surface of the blade structure; step 7, analyzing the electric field intensity on the blade surface according to the distribution cloud map, determining the lightning attachment point, and completing the simulation evaluation of the lightning attachment point. The simulation evaluation method of the present invention solves the problem that the prior art cannot evaluate the attachment point of the wind turbine lightning discharge process affected by rotation.

Description

Technical Field

[0001] The present invention belongs to the technical field of lightning detection, and in particular relates to a method for simulating and evaluating lightning attachment points on wind turbine blades. Background Art

[0002] The research on wind turbine attachment points is the foundation and basis for wind turbine lightning zoning and protection design. The purpose is to determine the initial attachment area of ​​lightning when the wind turbine is struck by lightning, and adopt appropriate lightning protection design and measures for each area. As the size of wind turbines becomes larger and larger, the lightning risk of wind turbines is more closely related to the upward leader. There are differences in the ability of wind turbines to trigger the upward leader of lightning with different polarities, which in turn affects the lightning resistance characteristics of wind turbines. Wind turbines are in a rotating state for a long time, and the rotation of blades will affect the lightning attraction ability and lightning resistance position of wind turbines. However, the current research on the mechanism of rotation affecting the lightning discharge process of wind turbines is still not perfect. The number of wind turbines, installation location, external environment, etc. have a great impact on the lightning risk of wind turbines. The lightning resistance mechanism of multiple leaders competing with each other in wind turbine groups and the evaluation method of lightning attachment points need to be further studied. Summary of the invention

[0003] The purpose of the present invention is to provide a method for simulating and evaluating lightning attachment points on wind turbine blades, which solves the problem that the prior art cannot evaluate the attachment points of the wind turbine lightning discharge process affected by rotation.

[0004] The technical solution adopted by the present invention is a wind turbine blade lightning attachment point simulation evaluation method, comprising the following steps:

[0005] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0006] Step 2: Set the material parameters of the optimized blade 3D model;

[0007] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0008] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0009] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0010] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0011] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0012] The present invention is also characterized in that:

[0013] The specific process of step 1 is:

[0014] Step 1.1, import the blade 3D model through COMSOL software;

[0015] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0016] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0017] Step 1.4: Place the lightning rod model and metal mesh model into the blade three-dimensional model, build a blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model.

[0018] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade three-dimensional model and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the metal mesh model parameters use copper mesh, and the blade parameters of the blade three-dimensional model use carbon fiber composite materials.

[0019] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material, and the conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0020] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0021] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0022] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0023] (1);

[0024] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m;

[0025] S3, calculate its conductivity according to formula (2);

[0026] (2);

[0027] In the formula, s is the conductivity.

[0028] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade.

[0029] The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150 kV, and the voltage of the grounding plate is 0 kV.

[0030] The specific process of step 5 is:

[0031] Step 5.1, segmenting the surface of the lightning receptor model simulation part according to the segmentation standard, and segmenting the surface of the lightning receptor model simulation part into a free triangle grid with a maximum unit size of 0.01m;

[0032] Step 5.2, segmenting the surface of the metal mesh model simulation part according to the segmentation standard, and segmenting it into a free triangle mesh with a maximum unit size of 0.1m;

[0033] Step 5.3, segmenting the surface of the blade three-dimensional model simulation part according to the segmentation standard, and segmenting it into a free triangle grid with a maximum unit size of 0.3m;

[0034] Step 5.4, based on the surface free triangle mesh size of the lightning receptor model simulation, the metal mesh model simulation and the blade three-dimensional model simulation, expand inward and outward according to a certain growth rate until the outermost boundary of the model, and divide the entire air domain into meshes of a predefined size, and the mesh type is a free tetrahedral mesh;

[0035] The division standard is: the minimum grid size is smaller than the minimum size of the model; first divide the surface of the simulation part, and then expand inward and outward according to a certain growth rate based on the surface of the simulation part until the outermost boundary of the model is reached. When encountering an interface, the grid growth rate must first decrease, and then increase after passing the interface; design the grid in the order of points, lines, surfaces, and bodies; construct the basic framework through the orderly arrangement and combination of points; then form the surface area through a number of lines; finally, form a volume grid through the division of the surface.

[0036] The specific process of step 6 is:

[0037] Step 6.1, in COMSOL software, set the angle theta between the blade and the ground plane to 10°, 30°, 60° and 90°, and set the angle phi of the blade to the ground to 0°, 90°, 180° and 270° through parametric scanning during simulation; the posture of the blade during simulation consists of the windward side to the ground posture, the leeward side to the ground posture, the leading edge to the ground posture and the trailing edge to the ground posture;

[0038] Step 6.2, select the scan type in the software as the specified combination;

[0039] Step 6.3, select the study type in the software as steady state;

[0040] Step 6.4, select the steady-state solver configuration in the software to display the default solver;

[0041] Step 6.5. Click the Calculate button in the COMSOL software to obtain the electric field intensity distribution cloud map on the blade surface and calculate the electrostatic induction of the blade in different postures.

[0042] The specific process of step 7 is:

[0043] Step 7.1. Select the 3D plot group as the result setting in COMSOL software, select the parameterized solution as the data set, the theta value of the parameterized solution is 10°, and the phi value of the parameterized solution is 0°.

[0044] Step 7.2, select the surface drawing as the 3D drawing group of COMSOL software, select the electric field normE as the expression for drawing, and draw the electric field distribution cloud diagram on the blade surface;

[0045] Step 7.3, set the maximum value in the range setting of COMSOL software to 8%, and use the range with higher electric field intensity of the surface cloud map shown in the figure as the attachment point on the blade in this posture;

[0046] Step 7.4, change the phi value to 90°, 180° and 270° respectively, repeat steps 7.1 to 7.3, and obtain the attachment range on the blade under different postures of the blade;

[0047] Step 7.5, change the theta value to 30°, 60° and 90° respectively, repeat steps 7.1 to 7.3, obtain the attachment range on the blade under all blade postures, and complete the simulation evaluation of the lightning attachment point.

[0048] The beneficial effects of the present invention are:

[0049] The wind turbine blade lightning attachment point simulation evaluation method provided by the present invention is a fast, efficient, high-precision simulation evaluation, which is applied to the design optimization of the full-size blade lightning protection system; through the attachment point simulation evaluation method, the blade lightning protection system evaluation results are generated quickly, supporting the iterative optimization of the blade design method. The method does not require the production of a physical model, has a low economic cost, and the simulation results are verified by tests of multiple models, and are suitable for the evaluation of lightning attachment points of different blade configurations and different blade postures; it provides a high-precision simulation tool for the rapid evaluation of the lightning attachment point of the blade and the lightning zoning of the blade, supporting the iterative design of the blade lightning protection system. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 It is a flow chart of the method for simulating and evaluating the lightning attachment point of a wind turbine blade according to the present invention. DETAILED DESCRIPTION

[0051] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0052] Example 1

[0053] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0054] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0055] Step 2: Set the material parameters of the optimized blade 3D model;

[0056] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0057] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0058] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0059] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0060] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0061] Example 2

[0062] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0063] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0064] The specific process is:

[0065] Step 1.1, import the blade 3D model through COMSOL software;

[0066] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0067] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0068] Step 1.4, layout the lightning receptor model and the metal mesh model into the blade three-dimensional model, construct the blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model;

[0069] Step 2: Set the material parameters of the optimized blade 3D model;

[0070] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade of the three-dimensional blade model, and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the parameters of the metal mesh model use copper mesh, and the parameters of the blade of the three-dimensional blade model use carbon fiber composite materials;

[0071] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material. The conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0072] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0073] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0074] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0075] (1);

[0076] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m;

[0077] S3, calculate its conductivity according to formula (2);

[0078] (2);

[0079] In the formula, s is the conductivity;

[0080] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0081] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade;

[0082] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0083] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0084] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0085] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0086] Example 3

[0087] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0088] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0089] The specific process is:

[0090] Step 1.1, import the blade 3D model through COMSOL software;

[0091] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0092] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0093] Step 1.4, layout the lightning receptor model and the metal mesh model into the blade three-dimensional model, construct the blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model;

[0094] Step 2: Set the material parameters of the optimized blade 3D model;

[0095] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade of the three-dimensional blade model, and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the parameters of the metal mesh model use copper mesh, and the parameters of the blade of the three-dimensional blade model use carbon fiber composite materials;

[0096] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material. The conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0097] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0098] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0099] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0100] (1);

[0101] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m;

[0102] S3, calculate its conductivity according to formula (2);

[0103] (2);

[0104] In the formula, s is the conductivity;

[0105] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0106] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade;

[0107] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0108] The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150 kV, and the voltage of the grounding plate is 0 kV.

[0109] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0110] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0111] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0112] Example 4

[0113] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0114] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0115] The specific process is:

[0116] Step 1.1, import the blade 3D model through COMSOL software;

[0117] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0118] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0119] Step 1.4, layout the lightning receptor model and the metal mesh model into the blade three-dimensional model, construct the blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model;

[0120] Step 2: Set the material parameters of the optimized blade 3D model;

[0121] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade of the three-dimensional blade model, and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the parameters of the metal mesh model use copper mesh, and the parameters of the blade of the three-dimensional blade model use carbon fiber composite materials;

[0122] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material. The conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0123] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0124] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0125] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0126] (1);

[0127] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m;

[0128] S3, calculate its conductivity according to formula (2);

[0129] (2);

[0130] In the formula, s is the conductivity;

[0131] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0132] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade;

[0133] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0134] The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150 kV, and the voltage of the grounding plate is 0 kV.

[0135] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0136] The specific process is:

[0137] Step 5.1, segmenting the surface of the lightning receptor model simulation part according to the segmentation standard, and segmenting the surface of the lightning receptor model simulation part into a free triangle grid with a maximum unit size of 0.01m;

[0138] Step 5.2, segmenting the surface of the metal mesh model simulation part according to the segmentation standard, and segmenting it into a free triangle mesh with a maximum unit size of 0.1m;

[0139] Step 5.3, segmenting the surface of the blade three-dimensional model simulation part according to the segmentation standard, and segmenting it into a free triangle grid with a maximum unit size of 0.3m;

[0140] Step 5.4, based on the surface free triangle mesh size of the lightning receptor model simulation, the metal mesh model simulation and the blade three-dimensional model simulation, expand inward and outward according to a certain growth rate until the outermost boundary of the model, and divide the entire air domain into meshes of a predefined size, and the mesh type is a free tetrahedral mesh;

[0141] The division standard is: the minimum grid size is smaller than the minimum size of the model; first divide the surface of the simulation part, and then expand inward and outward according to a certain growth rate based on the surface of the simulation part until the outermost boundary of the model is reached. When encountering the interface, the grid growth rate must first decrease, and then increase after the interface; design the grid in the order of point, line, surface, and body; construct the basic framework through the orderly arrangement and combination of points; then form the surface area through a number of lines; finally, form the body grid through the division of the surface;

[0142] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0143] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0144] Example 5

[0145] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0146] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0147] The specific process is:

[0148] Step 1.1, import the blade 3D model through COMSOL software;

[0149] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0150] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0151] Step 1.4, layout the lightning receptor model and the metal mesh model into the blade three-dimensional model, construct the blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model;

[0152] Step 2: Set the material parameters of the optimized blade 3D model;

[0153] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade of the three-dimensional blade model, and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the parameters of the metal mesh model use copper mesh, and the parameters of the blade of the three-dimensional blade model use carbon fiber composite materials;

[0154] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material. The conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0155] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0156] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0157] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0158] (1);

[0159] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ;L is the length of the specimen, unit: m;

[0160] S3, calculate its conductivity according to formula (2);

[0161] (2);

[0162] In the formula, s is the conductivity;

[0163] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0164] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade;

[0165] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0166] The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150 kV, and the voltage of the grounding plate is 0 kV.

[0167] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0168] The specific process is:

[0169] Step 5.1, segmenting the surface of the lightning receptor model simulation part according to the segmentation standard, and segmenting the surface of the lightning receptor model simulation part into a free triangle grid with a maximum unit size of 0.01m;

[0170] Step 5.2, segmenting the surface of the metal mesh model simulation part according to the segmentation standard, and segmenting it into a free triangle mesh with a maximum unit size of 0.1m;

[0171] Step 5.3, segmenting the surface of the blade three-dimensional model simulation part according to the segmentation standard, and segmenting it into a free triangle grid with a maximum unit size of 0.3m;

[0172] Step 5.4, based on the surface free triangle mesh size of the lightning receptor model simulation, the metal mesh model simulation and the blade three-dimensional model simulation, expand inward and outward according to a certain growth rate until the outermost boundary of the model, and divide the entire air domain into meshes of a predefined size, and the mesh type is a free tetrahedral mesh;

[0173] The division standard is: the minimum grid size is smaller than the minimum size of the model; first divide the surface of the simulation part, and then expand inward and outward according to a certain growth rate based on the surface of the simulation part until the outermost boundary of the model is reached. When encountering the interface, the grid growth rate must first decrease, and then increase after the interface; design the grid in the order of point, line, surface, and body; construct the basic framework through the orderly arrangement and combination of points; then form the surface area through a number of lines; finally, form the body grid through the division of the surface;

[0174] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0175] The specific process is:

[0176] Step 6.1, in COMSOL software, set the angle theta between the blade and the ground plane to 10°, 30°, 60° and 90°, and set the angle phi of the blade to the ground to 0°, 90°, 180° and 270° through parametric scanning during simulation; the posture of the blade during simulation consists of the windward side to the ground posture, the leeward side to the ground posture, the leading edge to the ground posture and the trailing edge to the ground posture;

[0177] Step 6.2, select the scan type in the software as the specified combination;

[0178] Step 6.3, select the study type in the software as steady state;

[0179] Step 6.4, select the steady-state solver configuration in the software to display the default solver;

[0180] Step 6.5, click the calculation button in the COMSOL software to obtain the electric field intensity distribution cloud map on the blade structure surface and calculate the electrostatic induction of the blade in different postures;

[0181] Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

[0182] Example 6

[0183] The wind turbine blade lightning attachment point simulation evaluation method proposed in this embodiment is as follows: Figure 1 As shown, the following steps are included:

[0184] Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model;

[0185] The specific process is:

[0186] Step 1.1, import the blade 3D model through COMSOL software;

[0187] Step 1.2, processing the blade three-dimensional model into a surface structure;

[0188] Step 1.3, construct the lightning arrester model and the metal mesh model;

[0189] Step 1.4, layout the lightning receptor model and the metal mesh model into the blade three-dimensional model, construct the blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model;

[0190] Step 2: Set the material parameters of the optimized blade 3D model;

[0191] The material parameters in step 2 include the material parameters of the lightning receptor model, the material parameters of the metal mesh model, the material parameters of the blade of the three-dimensional blade model, and the conductivity parameters; the material parameters of the lightning receptor model use metal aluminum, the parameters of the metal mesh model use copper mesh, and the parameters of the blade of the three-dimensional blade model use carbon fiber composite materials;

[0192] The conductivity parameters include the conductivity of the copper mesh and the conductivity of the carbon fiber composite material. The conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a DC resistance tester.

[0193] The test process of the electrical conductivity of copper mesh and carbon fiber composite materials is as follows:

[0194] S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester;

[0195] S2. Calculate the corresponding resistivity according to formula (1) r ;

[0196] (1);

[0197] In the formula, r is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m;

[0198] S3, calculate its conductivity according to formula (2);

[0199] (2);

[0200] In the formula, s is the conductivity;

[0201] Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model;

[0202] In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade;

[0203] Step 4: Set the physical boundary of the air domain containing the blade 3D model;

[0204] The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150 kV, and the voltage of the grounding plate is 0 kV.

[0205] Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary;

[0206] The specific process is:

[0207] Step 5.1, segmenting the surface of the lightning receptor model simulation part according to the segmentation standard, and segmenting the surface of the lightning receptor model simulation part into a free triangle grid with a maximum unit size of 0.01m;

[0208] Step 5.2, segmenting the surface of the metal mesh model simulation part according to the segmentation standard, and segmenting it into a free triangle mesh with a maximum unit size of 0.1m;

[0209] Step 5.3, segmenting the surface of the blade three-dimensional model simulation part according to the segmentation standard, and segmenting it into a free triangle grid with a maximum unit size of 0.3m;

[0210] Step 5.4, based on the surface free triangle mesh size of the lightning receptor model simulation, the metal mesh model simulation and the blade three-dimensional model simulation, expand inward and outward according to a certain growth rate until the outermost boundary of the model, and divide the entire air domain into meshes of a predefined size, and the mesh type is a free tetrahedral mesh;

[0211] The division standard is: the minimum grid size is smaller than the minimum size of the model; first divide the surface of the simulation part, and then expand inward and outward according to a certain growth rate based on the surface of the simulation part until the outermost boundary of the model is reached. When encountering the interface, the grid growth rate must first decrease, and then increase after the interface; design the grid in the order of point, line, surface, and body; construct the basic framework through the orderly arrangement and combination of points; then form the surface area through a number of lines; finally, form the body grid through the division of the surface;

[0212] Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure;

[0213] The specific process is:

[0214] Step 6.1, in COMSOL software, set the angle theta between the blade and the ground plane to 10°, 30°, 60° and 90°, and set the angle phi of the blade to the ground to 0°, 90°, 180° and 270° through parametric scanning during simulation; the posture of the blade during simulation consists of the windward side to the ground posture, the leeward side to the ground posture, the leading edge to the ground posture and the trailing edge to the ground posture;

[0215] Step 6.2, select the scan type in the software as the specified combination;

[0216] Step 6.3, select the study type in the software as steady state;

[0217] Step 6.4, select the steady-state solver configuration in the software to display the default solver;

[0218] Step 6.5, click the calculation button in the COMSOL software to obtain the electric field intensity distribution cloud map on the blade structure surface and calculate the electrostatic induction of the blade in different postures;

[0219] Step 7: Analyze the electric field strength on the blade surface according to the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point according to the electric field strength, and complete the lightning attachment point simulation evaluation;

[0220] The specific process is:

[0221] Step 7.1. Select the 3D plot group as the result setting in COMSOL software, select the parameterized solution as the data set, the theta value of the parameterized solution is 10°, and the phi value of the parameterized solution is 0°.

[0222] Step 7.2, select the surface drawing as the 3D drawing group of COMSOL software, select the electric field normE as the expression for drawing, and draw the electric field distribution cloud diagram on the blade surface;

[0223] Step 7.3, set the maximum value in the range setting of COMSOL software to 8%, and use the range with higher electric field intensity of the surface cloud map shown in the figure as the attachment point on the blade in this posture;

[0224] Step 7.4, change the phi value to 90°, 180° and 270° respectively, repeat steps 7.1 to 7.3, and obtain the attachment range on the blade under different postures of the blade;

[0225] Step 7.5, change the theta value to 30°, 60° and 90° respectively, repeat steps 7.1 to 7.3, obtain the attachment range on the blade under all blade postures, and complete the simulation evaluation of the lightning attachment point.

Claims

1. A wind turbine blade lightning attachment point simulation evaluation method, characterized in that: The following steps are involved: Step 1, importing a blade three-dimensional model, optimizing the blade three-dimensional model, and obtaining an optimized blade three-dimensional model; Step 2: Set the material parameters of the optimized blade 3D model; Step 3: establishing a flat plate discharge structure according to the blade dimensions of the optimized blade three-dimensional model, and applying an equally spaced electrostatic field to the blade to form an air domain containing the blade three-dimensional model; Step 4, setting the physical boundary of the air domain containing the blade 3D model; Step 5, performing surface, volume and space meshing on the blade three-dimensional model after setting the physical boundary; Step 6: In COMSOL software, the three-dimensional blade model after division is simulated and calculated by a steady-state solver to calculate the induced electric field of the blade under different postures, and obtain a cloud diagram of the electric field intensity distribution on the surface of the blade structure; Step 7: Analyze the electric field strength on the blade surface based on the electric field strength distribution cloud map on the blade structure surface, determine the lightning attachment point based on the electric field strength, and complete the lightning attachment point simulation evaluation.

2. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1 is characterized in that: The specific process of step 1 is as follows: Step 1.1, import the blade 3D model through COMSOL software; Step 1.2, processing the blade three-dimensional model into a surface structure; Step 1.3, construct the lightning arrester model and the metal mesh model; Step 1.4: Place the lightning rod model and metal mesh model into the blade three-dimensional model, build a blade rotation attitude reference coordinate system, obtain the blade rotation attitude, the angle between the blade and the ground plane is theta, the angle between the blade and the ground is phi, and obtain the optimized blade three-dimensional model.

3. The wind turbine blade lightning attachment point simulation evaluation method according to claim 2 is characterized in that: The material parameters described in step 2 include lightning arrester model material parameters, metal mesh model material parameters, blade three-dimensional model blade material parameters and conductivity parameters; the lightning arrester model material parameters use metal aluminum, the metal mesh model parameters use copper mesh, and the blade three-dimensional model blade parameters use carbon fiber composite materials.

4. The wind turbine blade lightning attachment point simulation evaluation method according to claim 3 is characterized in that: The conductivity parameter includes the conductivity of the copper mesh and the conductivity of the carbon fiber composite material, and the conductivity of the copper mesh and the conductivity of the carbon fiber composite material are both obtained by testing with a direct current resistance tester.

5. The wind turbine blade lightning attachment point simulation evaluation method according to claim 4 is characterized in that: The test process of the electrical conductivity of the copper mesh and the electrical conductivity of the carbon fiber composite material is as follows: S1. Clamp the two ends of the copper mesh or carbon fiber composite material test piece with a fixture and read the resistance value on the display screen of the DC resistance tester; S2. Calculate the corresponding resistivity according to formula (1) ρ ; （1）； In the formula, ρ is the resistivity; R is the resistance, unit is Ω; S is the cross-sectional area, unit: m 2 ; L is the length of the specimen, unit: m; S3, calculate its conductivity according to formula (2); （2）； In the formula, σ is the conductivity.

6. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1 is characterized in that: In step 3, the distance between the flat electrode of the flat discharge structure and the center of the blade is 1.5 times the length of the blade model, and the area of ​​the flat discharge structure is twice the area of ​​the blade body of the covered model blade.

7. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1, characterized in that: The specific process of setting the physical boundary of the air domain containing the blade three-dimensional model in step 4 is as follows: the upper boundary of the air domain containing the blade three-dimensional model simulates the high-voltage electrode in the test environment, and the lower boundary of the air domain containing the blade three-dimensional model simulates the grounding plate. The voltage of the high-voltage electrode is 150kV, and the voltage of the grounding plate is 0kV.

8. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1, characterized in that: The specific process of step 5 is: Step 5.1, segmenting the surface of the lightning receptor model simulation part according to the segmentation standard, and segmenting the surface of the lightning receptor model simulation part into a free triangle grid with a maximum unit size of 0.01m; Step 5.2, segmenting the surface of the metal mesh model simulation part according to the segmentation standard, and segmenting it into a free triangle mesh with a maximum unit size of 0.1m; Step 5.3, segmenting the surface of the blade three-dimensional model simulation part according to the segmentation standard, and segmenting it into a free triangle grid with a maximum unit size of 0.3m; Step 5.4, based on the surface free triangle mesh size of the lightning receptor model simulation, the metal mesh model simulation and the blade three-dimensional model simulation, expand inward and outward according to a certain growth rate until the outermost boundary of the model, and divide the entire air domain into meshes of a predefined size, and the mesh type is a free tetrahedral mesh; The segmentation standard is as follows: the minimum grid size is smaller than the minimum size of the model; the surface of the simulation part is first segmented, and then the surface of the simulation part is used as a reference to expand inward and outward at a certain growth rate until the outermost boundary of the model is reached. When an interface is encountered, the grid growth rate must first be reduced, and then the growth rate will increase after the interface is exceeded; the grid is designed in the order of points, lines, surfaces, and bodies; the basic framework is constructed through the orderly arrangement and combination of points; then a surface area is formed through a number of lines; and finally a volume grid is formed through the segmentation of the surface.

9. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1, characterized in that: The specific process of step 6 is: Step 6.1, in COMSOL software, setting the angle theta between the blade and the ground plane to 10°, 30°, 60° and 90° during simulation through parametric scanning, setting the angle phi of the blade to the ground to 0°, 90°, 180° and 270°; the posture of the blade during simulation consists of the windward side to the ground posture, the leeward side to the ground posture, the leading edge to the ground posture and the trailing edge to the ground posture; Step 6.2, select the scan type in the software as the specified combination; Step 6.3, select the study type in the software as steady state; Step 6.4, select the steady-state solver configuration in the software to display the default solver; Step 6.

5. Click the Calculate button in the COMSOL software to obtain the electric field intensity distribution cloud map on the blade surface and calculate the electrostatic induction of the blade in different postures.

10. The wind turbine blade lightning attachment point simulation evaluation method according to claim 1, characterized in that: The specific process of step 7 is: Step 7.1, select the result setting in COMSOL software as 3D plot group, select the data set as parameter solution, the theta value of the parameter solution is 10°, and the phi value of the parameter solution is 0°; Step 7.2, select the surface drawing as the 3D drawing group of COMSOL software, select the electric field normE as the expression for drawing, and draw the electric field distribution cloud diagram on the blade surface; Step 7.3, set the maximum value in the range setting of COMSOL software to 8%, and use the range with higher electric field intensity of the surface cloud map shown in the figure as the attachment point on the blade in this posture; Step 7.4, change the phi value to 90°, 180° and 270° respectively, repeat steps 7.1 to 7.3, and obtain the attachment range on the blade under different postures of the blade; Step 7.5, change the theta value to 30°, 60° and 90° respectively, repeat steps 7.1 to 7.3, obtain the attachment range on the blade under all blade postures, and complete the simulation evaluation of the lightning attachment point.

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