Simulation method for electromagnetic environmental effects on wind turbine nacelles or hubs

Abstract

This invention discloses a simulation method for electromagnetic environment effects of wind turbine nacelles or hubs, comprising the following steps: Step 1, establishing a three-dimensional geometric model of the wind turbine nacelle or hub; Step 2, assigning material properties and electromagnetic parameters to each component in the model; Step 3, setting up a physical field, setting terminal boundary conditions on the lightning protection conductor, and setting ground boundary conditions at the grounding end; Step 4, loading a lightning current excitation source at the terminal boundary conditions; Step 5, meshing the model; Step 6, calculating the distribution results of electromagnetic environment effects; Step 7, evaluating based on the distribution results, and iteratively optimizing the parameters in the model. This simulation method solves the problem of existing simulation methods, which can only complete electromagnetic field distribution analysis under a single lightning strike condition and at the whole-machine scale, without systematically considering the comprehensive impact of multi-dimensional factors such as the internal equipment layout of the nacelle or hub, lightning current conduction paths, and different lightning current parameters on the electromagnetic environment.

Description

Technical Field

[0001] This invention belongs to the field of lightning protection technology for wind turbine generator sets, specifically involving a simulation method for electromagnetic environment effects on wind turbine nacelles or hubs. Background Technology

[0002] Wind turbines are typically installed in open areas or offshore, with towers reaching heights of over 100 meters, making them typical targets sensitive to lightning strikes. As wind turbines become larger and even ultra-larger, their height increases, exacerbating the risk of lightning strikes. The probability of components such as blades, nacelles, and hubs being struck by lightning increases significantly. The serious accident in 2025 at the Vineyard offshore wind farm in the United States, where the AW-38 wind turbine caught fire and crashed due to a lightning strike, further highlights the importance and urgency of lightning protection for wind turbines. Once struck by lightning, strong electromagnetic interference is generated inside the turbine, affecting its normal operation, leading to control system failure, damage to electronic equipment, or even complete destruction of the entire turbine.

[0003] Currently, the main standards for lightning protection of wind turbines include IEC 61400-24 "Wind power generation systems - Part 24: Lightning protection" and the national standard GB / T 33629-2024 "Lightning protection of wind power generation systems". These standards define the lightning environment and risk assessment methods for wind turbines, and specify the requirements for direct and indirect lightning protection of blades, structural components, and electrical control systems. The third revision of IEC 61400-24 is currently underway, upgrading the high-current adhesion test on blades to a mandatory requirement and introducing for the first time lightning protection and grounding technical requirements for hybrid tower structures. Furthermore, the IEC 61400-40:2026 standard specifically addresses the electromagnetic compatibility (EMC) requirements and test methods for wind turbines. These iterative upgrades of the standards indicate that the industry's emphasis on lightning protection for wind turbines is continuously increasing, and the demand for electromagnetic environment assessment methods is becoming increasingly urgent.

[0004] In terms of existing technical means, there have been studies in this field on lightning electromagnetic transient analysis of offshore wind turbines using the finite element method. For example, existing literature has reported the construction of finite element-based models of offshore wind turbine nacelles, towers and grounding bodies, and the calculation of electromagnetic field distribution when lightning strikes the nacelle using the dipole method. However, these studies still have the following shortcomings: (1) They mainly rely on general electromagnetic simulation platforms such as ANSYS / Maxwell, and the modeling process is not tightly coupled with the complex structure of the nacelle / hub in actual engineering; (2) They usually only complete the electromagnetic field distribution analysis of a single lightning strike condition and the whole machine scale, without systematically considering the comprehensive impact of multiple dimensions such as the internal equipment layout of the nacelle / hub, lightning current conduction path, and different lightning current parameters on the electromagnetic environment; (3) The simulation models mostly serve academic research and lack a rapid evaluation process and parameterized optimization methods for iterative design of lightning protection systems; (4) There is no technical solution for systematic electromagnetic environment effect simulation evaluation of wind turbine nacelles / hubs based on the magnetic field module of COMSOL finite element software and using coil boundary conditions. Summary of the Invention

[0005] The purpose of this invention is to provide a simulation method for electromagnetic environment effects of wind turbine nacelles or hubs. This method solves the problem that existing simulation methods can only complete the electromagnetic field distribution analysis of a single lightning strike condition and the whole machine scale, without systematically considering the comprehensive impact of multi-dimensional factors such as the internal equipment layout of the nacelle or hub, lightning current conduction path, and different lightning current parameters on the electromagnetic environment.

[0006] The technical solution adopted in this invention is a simulation method for electromagnetic environment effects of wind turbine nacelles or hubs, comprising the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Step 4: Apply a lightning current excitation source at the terminal boundary condition; Step 5: Mesh the model; Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

[0007] The invention is further characterized by: The three-dimensional geometric model in step 1 also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle.

[0008] In step 2, the material properties include electrical conductivity, relative permeability, and relative permittivity. For metal structural components, the relative permeability is set according to the actual BH curve. For insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value.

[0009] In step 3, the physical field is set up as follows: In the COMSOL software, select the "Magnetic Field" physical field interface of the AC / DC module as the main solution physical field, and select transient as the study type; Define the lightning protection conductor as a coil as follows: Set the lightning protection conductor as a coil characteristic node; For the geometrically open lightning protection conductor, apply current excitation through the terminal boundary condition, and close the current loop through the ground boundary condition. Step 3 also includes setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity.

[0010] In step 4, the lightning current excitation source is defined using the Heidler function or the double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200kA, the wavefront time is 10μs, and the half-peak time is 350μs. The peak current of the subsequent lightning strikes is 50kA.

[0011] In step 5, a non-uniform meshing strategy is adopted: a dense mesh is used in the lightning conductor, the lightning protection area, and the area where the electromagnetic field gradient changes drastically, while a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, with the mesh size gradually increasing from near to far.

[0012] Step 6 uses a transient solver, covering the entire lightning current pulse process from 0 to 500 μs, with an initial time step of 0.1 μs and a maximum time step of 5 μs. The solver used is either the direct solver PARDISO or MUMPS, with a relative tolerance of 1 × 10⁻⁶. -4 .

[0013] The electromagnetic environment effect distribution results in step 6 include the magnetic induction intensity distribution, induced current density distribution, electric field intensity distribution, and electromagnetic energy density distribution.

[0014] The evaluation in step 7 includes: analyzing the distribution of magnetic induction intensity, induced current density, and electric field intensity in the distribution results; determining the electromagnetic interference level at key locations in the internal components; identifying weak links in the lightning protection conductor conduction path; and verifying the effectiveness of the lightning protection conductor layout and grounding design. Adjusting the parameters in the model includes adjusting the layout path, cross-sectional dimensions, and grounding method of the lightning protection conductor; adding local electromagnetic shielding structures; or adjusting the arrangement scheme of internal components.

[0015] The iterative optimization in step 7 specifically involves adjusting the parameters in the model based on the evaluation results, and then re-executing steps 1 to 6 until the electromagnetic environment effect index meets the protection requirements. The entire iterative process is completed in a software environment without the need to create a physical prototype.

[0016] The beneficial effects of this invention are: The electromagnetic environment effect simulation method for wind turbine nacelles or hubs provided by this invention accurately describes the conduction path of lightning current in the lightning protection conductors of the nacelle / hub using coil boundary conditions. It eliminates the need for physical models, significantly shortening the simulation evaluation cycle compared to traditional physical high-voltage tests. It can quickly generate evaluation results, significantly accelerating the iterative optimization process of lightning protection design. Employing full-size three-dimensional geometric modeling, it does not rely on simplified models based on equivalent circuits, accurately reflecting the electromagnetic field distribution characteristics in complex structures. By precisely simulating the closed conduction path of lightning current through coil boundary conditions, it ensures the physical rationality and engineering accuracy of the calculation results. The simulation results have been verified through physical tests on multiple models, proving that they have an engineering-acceptable level of accuracy. Compared with the traditional method of manufacturing physical prototypes and conducting high-voltage tests, this method eliminates the need for physical processing and test site costs. The simulation process can be repeated, and multiple iterative evaluations of the design scheme incur almost no additional costs, resulting in minimal economic impact. This method supports parametric modeling, allowing for rapid adjustment of geometric models and material parameters according to different turbine models. It is applicable to the electromagnetic environment effect assessment of different nacelle / hub configurations (including onshore and offshore turbines, doubly-fed and direct-drive turbines, etc.). This method provides quantitative electromagnetic environment assessment data and visualized electromagnetic field distribution results for the layout of equipment inside the nacelle / hub and the optimization of lightning protection paths. It can guide the iterative design of lightning protection systems and effectively improve the lightning protection level of wind turbines. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to the present invention. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0019] The electromagnetic environment effect simulation method for wind turbine nacelles or hubs provided by this invention, such as... Figure 1As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; The three-dimensional geometric model also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Material properties include electrical conductivity, relative permeability, and relative permittivity; for metallic structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value. Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Setting up the physical field involves selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type. Defining the lightning protection conductor as a coil involves setting the lightning protection conductor as a coil characteristic node. For a geometrically open lightning protection conductor, current excitation is applied through the terminal boundary condition, and the current loop is closed through the ground boundary condition. Step 3 also includes: setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity. Step 4: Apply a lightning current excitation source at the terminal boundary condition; The lightning current excitation source is defined using the Heidler function or the double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200 kA, the wavefront time is 10 μs, and the half-peak time is 350 μs. The peak current of the subsequent lightning strikes is 50 kA. Step 5: Mesh the model; The mesh generation adopts a non-uniform mesh strategy: a dense mesh is used in the lightning protection conductor, the lightning interception area and the area where the electromagnetic field gradient changes drastically, and a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning protection conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, and the mesh size gradually increases from near to far. Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; The calculation uses a transient solver, and the solution time range covers the entire process of the lightning current pulse from 0 to 500 μs. The initial time step is 0.1 μs and the maximum time step is 5 μs. The solver uses the direct solver PARDISO or MUMPS, and the relative tolerance is set to 1 × 10⁻⁴. The distribution results of electromagnetic environment effects include magnetic induction intensity distribution, induced current density distribution, electric field intensity distribution, and electromagnetic energy density distribution; Step 7: Evaluate based on the distribution results and iteratively optimize by adjusting the parameters in the model; The assessment includes: analyzing the distribution of magnetic induction intensity, induced current density, and electric field intensity in the distribution results; determining the electromagnetic interference level at key locations in the internal components; identifying weak points in the lightning protection conductor conduction path; and verifying the effectiveness of the lightning protection conductor layout and grounding design. Adjusting parameters in the model includes adjusting the layout path, cross-sectional dimensions, and grounding method of the lightning protection conductor; adding local electromagnetic shielding structures; or adjusting the arrangement scheme of internal components. The iterative optimization process involves adjusting the parameters in the model based on the evaluation results, and then re-executing steps 1 to 6 until the electromagnetic environment effect index meets the protection requirements. The entire iterative process is completed in a software environment without the need to create a physical prototype.

[0020] Example 1 The electromagnetic environment effect simulation method for wind turbine nacelles or hubs proposed in this embodiment, such as... Figure 1 As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Step 4: Apply a lightning current excitation source at the terminal boundary condition; Step 5: Mesh the model; Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

[0021] Example 2 The electromagnetic environment effect simulation method for wind turbine nacelles or hubs proposed in this embodiment, such as... Figure 1 As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; The three-dimensional geometric model also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Material properties include electrical conductivity, relative permeability, and relative permittivity; for metallic structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value. Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Setting up the physical field involves selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type. Defining the lightning protection conductor as a coil involves setting the lightning protection conductor as a coil characteristic node. For a geometrically open lightning protection conductor, current excitation is applied through the terminal boundary condition, and the current loop is closed through the ground boundary condition. Step 3 also includes: setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity. Step 4: Apply a lightning current excitation source at the terminal boundary condition; Step 5: Mesh the model; Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

[0022] Example 3 The electromagnetic environment effect simulation method for wind turbine nacelles or hubs proposed in this embodiment, such as... Figure 1 As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; The three-dimensional geometric model also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Material properties include electrical conductivity, relative permeability, and relative permittivity; for metallic structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value. Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Setting up the physical field involves selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type. Defining the lightning protection conductor as a coil involves setting the lightning protection conductor as a coil characteristic node. For a geometrically open lightning protection conductor, current excitation is applied through the terminal boundary condition, and the current loop is closed through the ground boundary condition. Step 3 also includes: setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity. Step 4: Apply a lightning current excitation source at the terminal boundary condition; The lightning current excitation source is defined using the Heidler function or the double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200 kA, the wavefront time is 10 μs, and the half-peak time is 350 μs. The peak current of the subsequent lightning strikes is 50 kA. Step 5: Mesh the model; The mesh generation adopts a non-uniform mesh strategy: a dense mesh is used in the lightning protection conductor, the lightning interception area and the area where the electromagnetic field gradient changes drastically, and a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning protection conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, and the mesh size gradually increases from near to far. Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

[0023] Example 4 The electromagnetic environment effect simulation method for wind turbine nacelles or hubs proposed in this embodiment, such as... Figure 1 As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; The three-dimensional geometric model also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Material properties include electrical conductivity, relative permeability, and relative permittivity; for metallic structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value. Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Setting up the physical field involves selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type. Defining the lightning protection conductor as a coil involves setting the lightning protection conductor as a coil characteristic node. For a geometrically open lightning protection conductor, current excitation is applied through the terminal boundary condition, and the current loop is closed through the ground boundary condition. Step 3 also includes: setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity. Step 4: Apply a lightning current excitation source at the terminal boundary condition; The lightning current excitation source is defined using the Heidler function or the double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200 kA, the wavefront time is 10 μs, and the half-peak time is 350 μs. The peak current of the subsequent lightning strikes is 50 kA. Step 5: Mesh the model; The mesh generation adopts a non-uniform mesh strategy: a dense mesh is used in the lightning protection conductor, the lightning interception area and the area where the electromagnetic field gradient changes drastically, and a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning protection conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, and the mesh size gradually increases from near to far. Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; The calculations employed a transient solver, covering the entire lightning current pulse process from 0 to 500 μs, with an initial time step of 0.1 μs and a maximum time step of 5 μs. The solver used was either the direct solver PARDISO or MUMPS, with a relative tolerance set to 1 × 10⁻⁶. -4 ; The distribution results of electromagnetic environment effects include magnetic induction intensity distribution, induced current density distribution, electric field intensity distribution, and electromagnetic energy density distribution; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

[0024] Example 5 The electromagnetic environment effect simulation method for wind turbine nacelles or hubs proposed in this embodiment, such as... Figure 1As shown, it includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; The three-dimensional geometric model also includes the blade root lightning arrester, lightning protection down conductor, lightning protection bridging device, and the air domain surrounding the main body of the nacelle and the hub; the lightning protection bridging device includes conductive brushes and conductive ring assemblies; the size of the air domain is 5 times the maximum size of the main body of the nacelle; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Material properties include electrical conductivity, relative permeability, and relative permittivity; for metallic structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value. Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Setting up the physical field involves selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type. Defining the lightning protection conductor as a coil involves setting the lightning protection conductor as a coil characteristic node. For a geometrically open lightning protection conductor, current excitation is applied through the terminal boundary condition, and the current loop is closed through the ground boundary condition. Step 3 also includes: setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity. Step 4: Apply a lightning current excitation source at the terminal boundary condition; The lightning current excitation source is defined using the Heidler function or the double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200 kA, the wavefront time is 10 μs, and the half-peak time is 350 μs. The peak current of the subsequent lightning strikes is 50 kA. Step 5: Mesh the model; The mesh generation adopts a non-uniform mesh strategy: a dense mesh is used in the lightning protection conductor, the lightning interception area and the area where the electromagnetic field gradient changes drastically, and a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning protection conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, and the mesh size gradually increases from near to far. Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; The calculations employed a transient solver, covering the entire lightning current pulse process from 0 to 500 μs, with an initial time step of 0.1 μs and a maximum time step of 5 μs. The solver used was either the direct solver PARDISO or MUMPS, with a relative tolerance set to 1 × 10⁻⁶. -4 ; The distribution results of electromagnetic environment effects include magnetic induction intensity distribution, induced current density distribution, electric field intensity distribution, and electromagnetic energy density distribution; Step 7: Evaluate based on the distribution results and iteratively optimize by adjusting the parameters in the model; The assessment includes: analyzing the distribution of magnetic induction intensity, induced current density, and electric field intensity in the distribution results; determining the electromagnetic interference level at key locations in the internal components; identifying weak points in the lightning protection conductor conduction path; and verifying the effectiveness of the lightning protection conductor layout and grounding design. Adjusting parameters in the model includes adjusting the layout path, cross-sectional dimensions, and grounding method of the lightning protection conductor; adding local electromagnetic shielding structures; or adjusting the arrangement scheme of internal components. The iterative optimization process involves adjusting the parameters in the model based on the evaluation results, and then re-executing steps 1 to 6 until the electromagnetic environment effect index meets the protection requirements. The entire iterative process is completed in a software environment without the need to create a physical prototype.

[0025] Example 6 This embodiment proposes a simulation method for electromagnetic environment effects on wind turbine nacelles or hubs. Taking a certain type of onshore doubly-fed wind turbine as an example, it performs electromagnetic environment effect simulation and evaluation on its nacelle and hub, and optimizes the lightning protection system design accordingly. Figure 1 As shown, it includes the following steps: Step 1: Create a 3D geometric model of the wind turbine nacelle and hub; In the COMSOL Multiphysics software geometric modeling environment, a full-size 3D geometric model was created at a 1:1 scale based on the unit's engineering design drawings. The model includes: the nacelle cowling and internal frame structure (steel structure); the hub main structure (ductile iron); and the blade root lightning arresters and lightning protection down conductors (copper conductor, 70mm in diameter). 2 Equivalent cross section; lightning protection bridging device from hub to nacelle, including conductive brush and conductive ring assembly; key equipment inside the nacelle, including simplified model of generator housing, gearbox housing, main control cabinet, converter cabinet, sensor module, etc.; transition section from tower top to nacelle and lightning protection grounding conductor; air domain surrounding the nacelle and hub, with the air domain size taken as 5 times the maximum size of the nacelle to truncate the calculation domain; geometric simplification of details such as connecting bolts, seals, and non-metallic casings that do not affect electromagnetic distribution; Step 2: Assign material properties and electromagnetic parameters to each component in the model; The material properties settings for each component are shown in Table 1: Table 1 Summary of Material Properties for Each Component

[0026] For insulating and composite material components, the conductivity is set to a minimum or zero value; Step 3: Set up the physical field, define the coils and boundary conditions; In the COMSOL model developer, add the "Magnetic Fields (mf)" physical field interface of the AC / DC module, and select "Transient" as the study type to capture the time evolution of lightning current. Under this physical field, coil characteristic nodes are established for different sections of the lightning protection conductor: (1) Blade lightning arrester to hub lightning protection down conductor segment: establish coil characteristics, current direction along down conductor from lightning arrester end to hub side; (2) Hub to nacelle bridging section (conductive brush-conductive ring assembly): establish coil features; since there is relative rotational motion between the conductive brush and the conductive ring, the bridging structure is equivalent to the continuous conductive domain in the model, and coil features are set at the corresponding positions; (3) Lightning protection conductor section inside the engine room (from the conductive ring interface to the tower grounding conductor): establish coil characteristics; A "terminal" boundary condition is set at the top of the lightning arrester to apply lightning current excitation; a "grounding" boundary condition (potential V=0) is set at the end of the tower grounding conductor; the entire lightning protection conductor path forms a complete closed current loop from terminal → lightning protection conductor → grounding.

[0027] A "magnetically insulated" boundary condition (i.e., n×A=0) is set at the outer boundary of the air domain to simulate the natural decay of the magnetic field at infinity. Step 4: Apply the lightning current excitation source; The lightning current waveform is defined using the Heidler function specified in the IEC 61400-24 standard. The current parameters for the first lightning strike are set as follows: peak current I_peak = 200kA, wavefront time T1 = 10μs, half-peak time T2 = 350μs. For subsequent lightning strike conditions, the peak current is set to 50kA to cover the needs of multi-condition evaluation. Lightning current function expression: ; In COMSOL, terminal boundary conditions are applied by defining analytical or interpolation functions. Step 5: Mesh the model; User-controlled mesh settings are employed; a non-uniform mesh strategy is used, employing mapped or swept meshes for the lightning protection conductor domain, with radially set boundary layer meshes (≥5 boundary layer layers) to accurately capture the skin effect in the conductor; local mesh refinement is performed in areas with drastic current density changes, such as the conductive brush-conducting ring interface and the lightning arrester-down conductor connection; a free tetrahedral mesh is used for the air domain, with mesh size controlled by a progressive strategy of gradually increasing from near to far. The total number of mesh elements is controlled within a reasonable range, balancing computational accuracy with computational efficiency.

[0028] Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Select the transient solver, set the solution time range to 0~500μs (covering the entire lightning current pulse process), set the initial time step to 0.1μs, and the maximum time step to 5μs. Use a direct solver (PARDISO or MUMPS) with a relative tolerance of 1×10⁻⁶. -4 ; After solving the problem, COMSOL post-processing is used to obtain parameters such as the distribution of magnetic induction intensity B, induced current density J_ind, electric field intensity E, and electromagnetic energy density within the engine compartment / hub interior space. Special attention is paid to the electromagnetic environment values ​​at the main control cabinet installation location, converter cabinet location, sensor installation area, and the engine compartment / hub connection interface. Step 7: Evaluation and Optimization Iteration Based on the simulation results, the electromagnetic environment level at each key location is assessed to determine whether it exceeds the electromagnetic tolerance threshold of sensitive equipment. Specifically, this includes analyzing the distribution of magnetic induction intensity, induced current density, and electric field intensity; determining the electromagnetic interference level at key locations within internal components; identifying weak points in the lightning protection conductor conduction path; and verifying the effectiveness of the lightning protection conductor layout and grounding design.

[0029] If the magnetic induction intensity or induced current density in a certain area exceeds the expected limit, targeted optimization measures are proposed: for example, adjusting the wiring path of the lightning protection conductor to keep it away from the area of ​​sensitive electronic equipment, adjusting the cross-sectional size of the lightning protection conductor, optimizing the grounding method, adding a local electromagnetic shielding structure, or adjusting the layout of internal components. After adjusting the design, the geometric model parameters are quickly updated, and the simulation process from steps 1 to 6 is re-executed. This process is repeated 2-3 times until the electromagnetic environment effect indicators meet the protection requirements. The entire iterative process is completed in a software environment, without the need to create any physical prototypes.

[0030] Result Validation The method of this invention has been verified through high-voltage tests on multiple wind turbine nacelles and hubs. The peak magnetic induction intensity at key locations inside the nacelle obtained from simulation calculations was compared with the corresponding measured values ​​from experiments. The two values ​​remained consistent in magnitude and distribution trend, verifying the effectiveness of the simulation method. This method is applicable to the assessment of electromagnetic environment effects and the optimization design of lightning protection systems for different nacelle / hub configurations (including doubly-fed, direct-drive, and semi-direct-drive types).

Claims

1. A simulation method for electromagnetic environment effects on wind turbine nacelles or hubs, characterized in that, Includes the following steps: Step 1: Establish a three-dimensional geometric model of the wind turbine nacelle or hub; the model includes the main body of the nacelle, the main body of the hub, internal components, lightning protection conductors, and metal structural parts; Step 2: Assign material properties and electromagnetic parameters to each component in the model; Step 3: Set up the physical field, set the terminal boundary conditions on the lightning protection conductor, set the grounding boundary conditions at the grounding end, and define the lightning protection conductor as a coil; Step 4: Apply a lightning current excitation source at the terminal boundary condition; Step 5: Mesh the model; Step 6: Calculate and obtain the distribution results of electromagnetic environment effects; Step 7: Evaluate based on the distribution results and adjust the parameters in the model for iterative optimization.

2. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The three-dimensional geometric model described in step 1 also includes a blade root lightning arrester, a lightning protection down conductor, a lightning protection bridging device, and an air domain surrounding the main body of the nacelle and the main body of the hub; the lightning protection bridging device includes a conductive brush and a conductive ring assembly; the size of the air domain is 5 times the maximum size of the main body of the nacelle.

3. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The material properties mentioned in step 2 include electrical conductivity, relative permeability, and relative permittivity; wherein, for metal structural components, the relative permeability is set according to the actual BH curve; for insulating materials and composite materials, the electrical conductivity is set to zero or a minimum value.

4. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The physical field setting in step 3 specifically involves: selecting the "Magnetic Field" physical field interface of the AC / DC module in the COMSOL software as the main solution physical field, and selecting transient as the study type; defining the lightning protection conductor as a coil specifically involves: setting the lightning protection conductor as a coil characteristic node; for a geometrically open-circuit lightning protection conductor, applying current excitation through the terminal boundary conditions, and closing the current loop through the grounding boundary conditions; Step 3 also includes setting magnetically insulating boundary conditions on the outer boundary of the air domain of the model to simulate the natural decay of the magnetic field at infinity.

5. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The lightning current excitation source in step 4 is defined using a Heidler function or a double exponential function. The parameters of the lightning current excitation source include the peak current, wavefront time, and half-peak time of the first and subsequent lightning strikes. The peak current of the first lightning strike is 200kA, the wavefront time is 10μs, and the half-peak time is 350μs. The peak current of the subsequent lightning strikes is 50kA.

6. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The meshing in step 5 adopts a non-uniform meshing strategy: a dense mesh is used in the lightning protection conductor, the lightning interception area, and the area where the electromagnetic field gradient changes drastically, while a sparse mesh is used in the air domain; a boundary layer mesh is set on the lightning protection conductor, with no less than 5 boundary layer layers, to capture the skin effect; a free tetrahedral mesh is used in the air domain, with the mesh size gradually increasing from near to far.

7. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The calculation in step 6 uses a transient solver, with a solution time range covering the entire lightning current pulse from 0 to 500 μs, an initial time step of 0.1 μs, and a maximum time step of 5 μs. The solver used is either the direct solver PARDISO or MUMPS, with a relative tolerance set to 1 × 10⁻⁶. -4 .

8. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The electromagnetic environment effect distribution results mentioned in step 6 include the magnetic induction intensity distribution, induced current density distribution, electric field intensity distribution, and electromagnetic energy density distribution.

9. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The evaluation in step 7 includes: analyzing the magnetic induction intensity distribution, induced current density distribution, and electric field intensity distribution in the distribution results; determining the electromagnetic interference level at key locations in the internal components; identifying weak points in the conduction path of the lightning protection conductor; and verifying the effectiveness of the lightning protection conductor layout and grounding design. The parameters in the adjustment model include adjusting the layout path, cross-sectional dimensions, grounding method, adding local electromagnetic shielding structures, or adjusting the arrangement scheme of the internal components.

10. The electromagnetic environment effect simulation method for wind turbine nacelles or hubs according to claim 1, characterized in that, The iterative optimization described in step 7 specifically involves adjusting the parameters in the model based on the evaluation results, and then re-executing steps 1 to 6 until the electromagnetic environment effect index meets the protection requirements. The entire iterative process is completed in a software environment without the need to create a physical prototype.

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