Optimization design method and system for blade structure of wind generating set

Abstract

The invention discloses a wind generating set blade structure optimization design method and system. The method comprises the following steps that an initial blade model is generated; carrying out optimal design of strain, buckling and deflection on the main beam; carrying out strain and buckling optimization design on the trailing edge beam; carrying out optimization design on the enhancement layer; carrying out optimization design on the core material; carrying out optimization design on the above steps to obtain a blade model, carrying out section attribute calculation and outputting, and calculating the weight and the cost of the blade at the same time; if the blade weight and the cost do not meet the preset design requirements, returning to regenerate the initial blade model until the blade weight and the cost meet the preset design requirements; carrying out load calculation iteration until convergence, and ending the optimization design; according to the method, the blades are optimized and processed, full-automatic iteration is realized, human participation is reduced, and the iteration time of manual calculation adjustment is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of optimizing the structure of wind turbine blades, and in particular to a method and system for optimizing the design of wind turbine blade structures. Background Art

[0002] The blade is one of the most critical and important components in a wind turbine. As the wind-catching device in the wind turbine, its structural design has always been a difficult point in blade design. Currently, in the process of blade design, how to quickly and efficiently obtain a reasonable structural ply and improve the blade structural design efficiency has always been the goal pursued by structural engineers.

[0003] Currently, in common blade structure optimization methods such as Chinese Patent Application CN202410484642.7, the optimization design method specifically includes: first, obtaining multiple cross-sections from the root to the tip of the blade, optimizing the parameters of each cross-section, recombining the optimized cross-sections to obtain multiple optimized blade models, analyzing and testing the optimized blade models, and finally obtaining the optimal model. The optimization design method of the fan blade provided by this invention solves the disadvantages of the existing fan blade optimization design methods such as long design cycle and high cost. This design method separates each cross-section and optimizes each cross-section separately. However, the correlation between the cross-sections in blade checking has a great impact on the structure and cannot be directly ignored, and a certain smoothness needs to be ensured between the plies of each cross-section. After optimizing by this method of completely separating the cross-sections, there will be problems in the actual ply. Summary of the Invention

[0004] The purpose of the present invention is to overcome the deficiencies of the prior art and propose a method and system for optimizing the design of wind turbine blade structures. The components of the wind turbine blade are componentized, and each component is optimized under a given load. Variables, constraints, and objectives are set for each component. After the settings are completed, according to the set automatic blade design process, automatic iteration will be performed to obtain the optimized ply structure of each main component. This design process, while ensuring structural safety, considers the continuity of the ply, reduces the manual calculation and iteration time, optimizes the weight of the main ply, and achieves the purpose of improving efficiency and reducing weight and cost.

[0005] The purpose of the present invention is achieved by the following technical solutions: A method for optimizing the design of wind turbine blade structures includes the following steps: S1. Generate an initial blade model according to the initial aerodynamic shape, and calculate the ultimate load and fatigue load of the blade according to the initial blade model; wherein, the components of the initial blade model include a main beam, a trailing edge beam, a reinforcement layer, and a core material; S2. Based on the calculated ultimate load and fatigue load of the blade, optimize the design of the strain, buckling and deflection of the main beam. Divide the main beam on the suction surface and pressure surface of the blade into n segments at equal intervals, and set the ply thickness of each segment of the main beam as a variable, with a total of 2n variables; S3. Based on the calculated ultimate load and fatigue load of the blade, optimize the design of the strain and buckling of the trailing edge beam. Divide the trailing edge beam of the blade into m segments at equal intervals, and set the ply thickness of each segment of the trailing edge beam as a variable, with a total of m variables; S4. Starting from the blade root, divide the reinforcement layer at equal intervals, control the strain threshold for each segment, perform iterative calculations to obtain the final number of layers of the reinforcement layer. After smoothing the plies, evenly distribute the reinforcement layer on the inner and outer sides and fill it into the model respectively; S5. Set the minimum buckling coefficient of the shell as the control, with the core material thickness of each region as a variable. Divide the core material at equal intervals into the core materials of the leading and trailing edges, pressure surface and suction surface, perform buckling calculations and iterative calculations until the shell meets the minimum buckling coefficient reaching the set threshold, and then smooth the thickness of the core material plies; At the same time, set the minimum buckling coefficient of the web as the control, with the web thickness of each region as a variable. When the thickness reaches the preset threshold, the thickness cannot be increased any further, so the web core material needs to be replaced and then optimized; Divide the web core material at equal intervals for buckling calculations and iterative calculations until the web meets the minimum buckling coefficient reaching the set threshold, and then smooth the thickness of the web core material plies; S6. Summarize the optimization designs in steps S2 to S5 to obtain the blade model, calculate and output the cross-sectional properties of the optimized blade model, and calculate the blade weight and cost at the same time; S7. If the blade weight and cost do not meet the preset design requirements, return to step S1, adjust the blade structure form, material system or aerodynamic shape until the blade weight and cost meet the preset design requirements; S8. Perform iterative calculations on the ultimate load and fatigue load according to the blade model until the ultimate load and fatigue load converge, and the optimization design ends.

[0006] Further, step S1 includes: Generate an initial aerodynamic shape based on the externally input boundary conditions; select a suitable material system and structural system, and then give an initial structural framework to generate an initial blade model, and estimate the plies of each component. The plies of each component include initial skin plies, main beam plies, reinforcement layer plies, trailing edge beam plies and shell core material plies; Calculate the ultimate load and fatigue load of the blade based on the initial blade model, wind conditions and external boundary conditions.

[0007] Further, step S2 includes: According to the calculated ultimate load and fatigue load of the blade, optimize the design of the strain, buckling and deflection of the main beam. The suction surface and pressure surface main beams of the blade are equally spaced and divided into n segments. The ply thickness of the main beam in each segment is set as a variable, and the total number of variables is 2n. Among them, the strain threshold of each cross-section of the main beam material should be less than the set maximum strain value, the first-order buckling coefficient should be greater than the set buckling coefficient, and the allowable deflection of the blade tip should be less than the set maximum allowable deflection of the blade tip. The optimization goal is the weight of the main beam.

[0008] Further, the step S2 includes: The strain optimization design is to calculate the strain of the main beam material of each cross-section according to the ultimate and fatigue loads, and automatically increase the thickness of each segment of the main beam until the strain of all cross-sections meets the requirements according to the set strain threshold; The buckling optimization design is to thicken the core material in the area near the main beam during optimization to ensure that buckling failure occurs on the main beam under the action of the flapping load. After setting the buckling failure eigenvalue and the calculated modal order, perform buckling iterative calculation to determine whether the failure position is on the main beam. If the failure position is on the main beam, record the corresponding main beam material and position, and increase the single ply thickness of the main beam at the corresponding position in the next iteration. If the failure position is not on the main beam, it will be automatically ignored and iterated until the minimum eigenvalue is greater than the set buckling eigenvalue; The deflection optimization design is to set the priority to increase the number of main beam layers from 2 / 3 of the blade to the blade tip, and set the upper limit of the number of layers. If the upper limit of the number of layers is exceeded, then adjust and increase the thickness of the main beam in the root area of the blade until the blade deflection is less than the set value. If too many main beam plies are added and the set deflection requirement still cannot be met, an error warning will be processed. Finally, perform fairing on the optimized main beam plies to ensure the operability of the plies.

[0009] Further, the step S3 includes: According to the calculated ultimate load and fatigue load of the blade, optimize the design of the strain and buckling of the trailing edge beam. The trailing edge beam of the blade is divided into m segments at equal intervals, and the ply thickness of each segment of the trailing edge beam is set as a variable, and the total number of variables is m. Among them, the strain threshold of each cross-section of the trailing edge beam material should be less than the set maximum strain value, and the first-order buckling coefficient should be greater than the set buckling coefficient. The optimization goal is the weight of the trailing edge beam; Calculate the strain of the trailing edge beam material of each cross-section according to the ultimate and fatigue loads, and automatically increase the adjusted plies of each segment until the set requirements are fully met; perform buckling calculation, set the minimum buckling eigenvalue, and perform buckling calculation iteratively to determine whether the failure position is on the trailing edge beam, and at the same time determine whether the minimum buckling coefficient is less than the set buckling eigenvalue. If the minimum buckling coefficient is less than the set buckling eigenvalue, automatically increase the ply of the trailing edge beam at the corresponding position until all requirements are met. Finally, perform fairing on the optimized trailing edge beam plies to ensure the operability of the plies.

[0010] Further, the step S4 includes: The blade reinforcement layer includes an inner reinforcement layer and an outer reinforcement layer, which are axially laid in the area from the blade root to near the maximum chord length. The inner and outer reinforcement layers are combined and optimized uniformly. Starting from the blade root, the reinforcement layer is divided at equal intervals, and the strain threshold is controlled for each section. Through iterative calculation, the final number of layers of the reinforcement layer is obtained. After the layup is smoothed, the reinforcement layer is evenly divided on the inner and outer sides and filled into the model respectively.

[0011] Further, the step S5 includes: The blade shell is a sandwich structure. The core material includes Balsa, PVC, and PET. The minimum buckling coefficient of the shell is set as the control, and the core thickness of each area is used as a variable. When the thickness reaches the preset threshold and cannot be increased further, the core material needs to be replaced and then optimized. The core is divided at equal intervals into leading-edge and trailing-edge cores, pressure-side cores, and suction-side cores. Buckling calculation and iterative calculation are carried out until the shell meets the requirement that the minimum buckling coefficient reaches the set threshold, and then the thickness of the core layup is smoothed.

[0012] A wind turbine blade structure optimization design system for implementing the above wind turbine blade structure optimization design method, including: An initial blade model generation module, which generates an initial blade model according to the initial aerodynamic shape and calculates the blade ultimate load and fatigue load based on the initial blade model. Among them, the components of the initial blade model include a main beam, a trailing-edge beam, a reinforcement layer, and a core. A main beam optimization module, which optimizes the strain, buckling, and deflection of the main beam according to the calculated blade ultimate load and fatigue load. The main beams on the suction side and pressure side of the blade are stratified into n sections at equal intervals, and the layup thickness of the main beam is set as a variable for each section, with a total of 2n variables. A trailing-edge beam optimization module, which optimizes the strain and buckling of the trailing-edge beam according to the calculated blade ultimate load and fatigue load. The trailing-edge beam of the blade is divided into m sections at equal intervals, and the layup thickness of each section of the trailing-edge beam is set as a variable, with a total of m variables. A reinforcement layer optimization module, which divides the reinforcement layer at equal intervals starting from the blade root, controls the strain threshold for each section, performs iterative calculation to obtain the final number of layers of the reinforcement layer, smooths the layup, and then evenly divides the reinforcement layer on the inner and outer sides and fills it into the model respectively. A core optimization module, which sets the minimum buckling coefficient of the shell as the control, uses the core thickness of each area as a variable, divides the core at equal intervals into leading-edge, trailing-edge, pressure-side, and suction-side cores, performs buckling calculation and iterative calculation until the shell meets the requirement that the minimum buckling coefficient reaches the set threshold, and then smooths the thickness of the core layup. The model output module outputs a blade model according to the optimization design results of the main beam optimization module, the trailing edge beam optimization module, the reinforcement layer optimization module, and the core material optimization module; The cross-sectional property calculation module calculates the cross-sectional properties of the optimized blade model.

[0013] A non-transitory computer-readable medium storing instructions, characterized in that when the instructions are executed by a processor, the steps of the above-mentioned wind turbine blade structure optimization design method are executed.

[0014] A computing device includes a processor and a memory for storing programs executable by the processor, characterized in that when the processor executes the programs stored in the memory, the above-mentioned wind turbine blade structure optimization design method is implemented.

[0015] Compared with the prior art, the present invention has the following advantages and beneficial effects: The present invention processes the blade optimization in a flow, realizes full-automatic iteration, reduces human participation, and reduces the iteration time due to manual calculation and adjustment; at the same time, the present invention adjusts the current optimization algorithm to solve the problems of ply splitting and non-smooth structure, and finally achieves the purpose of reducing the weight and cost of the blade. Description of the Drawings

[0016] Figure 1 It is a structural cross-sectional view of a wind turbine blade.

[0017] Figure 2 It is the optimization flow chart of the main beam.

[0018] Figure 3 It is the optimization flow chart of the trailing edge beam.

[0019] Figure 4 It is the optimization flow chart of the reinforcement layer.

[0020] Figure 5 It is the optimization flow chart of the core material.

[0021] Figure 6 It is the flow chart of the wind turbine blade structure optimization design method. Detailed Embodiments

[0022] The present invention will be further described below with reference to specific embodiments.

[0023] Embodiment 1 Refer to Figures 2 to 6 As shown, the wind turbine blade structure optimization design method provided in this embodiment includes the following steps: S1. Generate an initial blade model based on the initial aerodynamic shape, and calculate the blade ultimate load and fatigue load according to the initial blade model. Among them, the components of the initial blade model include a main beam, a trailing edge beam, a reinforcement layer, and a core material. Generate the initial aerodynamic shape according to the externally input boundary conditions. Select a suitable material system and structural system, and then specify the initial structural framework to generate the initial blade model. Estimate the ply of each component. The ply of each component includes an initial skin ply, a main beam ply, a reinforcement layer ply, a trailing edge beam ply, and a shell core material ply. Refer to Figure 1 As shown in Figure 1 , it is a cross-sectional view of the blade structure of a wind turbine generator. The main components of the blade include a trailing edge beam 1, a pressure side trailing edge core material 2, a suction side trailing edge core material 3, a pressure side main beam 4, a suction side main beam 5, a web 6, a pressure side leading edge core material 7, and a suction side leading edge core material 8. Calculate the blade ultimate load and fatigue load according to the initial blade model, wind conditions, and external boundary conditions.

[0024] S2. According to the calculated blade ultimate load and fatigue load, perform optimization design on the main beam for strain, buckling, and deflection. Divide the suction side main beam and pressure side main beam of the blade into n segments at equal intervals respectively. Set the ply thickness of the main beam in each segment as a variable, and the total number of variables is 2n. Among them, the strain threshold of each cross-section of the main beam material needs to be less than the set maximum strain value, the first-order buckling coefficient needs to be greater than the set buckling coefficient, and the allowable deflection of the blade tip needs to be less than the set maximum allowable deflection value of the blade tip. The optimization objective is the weight of the main beam. The strain optimization design calculates the strain of the main beam material of each cross-section according to the ultimate and fatigue loads. According to the set strain threshold, automatically increase the thickness of each segment of the main beam until the strain of all cross-sections meets the requirements. The buckling optimization design thickens the core material in the area near the main beam during optimization to ensure that buckling failure occurs on the main beam under the action of the flapping load. After setting the buckling failure eigenvalue and the calculated mode order, perform buckling iterative calculation to determine whether the failure position is on the main beam. If the failure position is on the main beam, record the corresponding main beam material and position, and increase the single-layer thickness of the main beam at the corresponding position in the next iteration. If the failure position is not on the main beam, automatically ignore it and perform cyclic iteration until the minimum eigenvalue is greater than the set buckling eigenvalue. The deflection optimization design sets to preferentially increase the number of layers of the main beam from 2 / 3 of the blade to the blade tip, and sets the upper limit of the number of layers. When the upper limit of the number of layers is exceeded, then adjust and increase the thickness of the main beam in the root area of the blade until the blade deflection is less than the set value. If increasing too many main beam plies still cannot meet the set deflection requirement, then perform an error warning process. Finally, perform fairing treatment on the optimized main beam ply to ensure that the ply is operable.

[0025] S3. According to the calculated blade limit load and fatigue load, the trailing edge beam is optimized for strain and buckling. The trailing edge beam of the blade is divided into m sections with equal spacing. The ply thickness of each section of the trailing edge beam is set as a variable, and the total variable is m. Among them, the strain threshold of each section of the trailing edge beam material must be less than the set strain maximum value, and the first-order buckling coefficient must be greater than the set buckling coefficient. The optimization target is the weight of the trailing edge beam. The strain of the trailing edge beam material of each section is calculated according to the limit and fatigue loads. According to the set strain threshold, each section of the adjustment ply is automatically increased until the set requirements are fully met; buckling calculation, the minimum buckling eigenvalue is set, and the buckling calculation is iteratively performed to determine whether the failure position is on the trailing edge beam. At the same time, it is determined whether the minimum buckling coefficient is less than the set buckling eigenvalue. If the minimum buckling coefficient is less than the set buckling eigenvalue, the trailing edge beam ply at the corresponding position is automatically increased until all requirements are met; finally, the optimized trailing edge beam ply is smoothed to ensure that the ply is operable.

[0026] S4. The blade reinforcement layer includes an inner reinforcement layer and an outer reinforcement layer, which are axially laid in the area from the blade root to the maximum chord length. The inner and outer reinforcement layers are merged and optimized uniformly. Starting from the blade root, the reinforcement layer is divided into equal intervals, and the strain threshold is controlled in each section. The final number of reinforcement layers is obtained by iterative calculation. After smoothing the layers, the reinforcement layers are evenly divided into inner and outer sides and filled into the model respectively.

[0027] S5. The blade shell is a sandwich structure. The core materials include Balsa, PVC and PET. The minimum buckling coefficient of the shell is set as a control. The thickness of the core material in each area is used as a variable. When the thickness reaches the preset threshold, the thickness can no longer be increased. In this case, the core material needs to be replaced and then optimized. The core material is divided into leading and trailing edge core materials, pressure surface core materials and suction surface core materials by equidistant division. Buckling calculations are performed and iterative calculations are performed until the shell meets the minimum buckling coefficient and reaches the set threshold. Then, the core material ply is smoothed by thickness. Similarly, the web is also a sandwich structure. The web core material can be optimized according to the shell core material optimization method. The minimum buckling coefficient of the web is set as a control. The thickness of the web in each area is used as a variable. When the thickness reaches the preset threshold, the thickness can no longer be increased. In this case, the web core material needs to be replaced and then optimized. The web core material is divided into leading and trailing edge core materials, pressure surface core materials and suction surface core materials by equidistant division. Buckling calculations are performed and iterative calculations are performed until the web meets the minimum buckling coefficient and reaches the set threshold. Then, the web core material ply is smoothed by thickness. S6, summarizing the optimization designs of steps S2 to S5, obtaining a blade model, calculating and outputting cross-sectional properties, and calculating the weight and cost of the blade; S7, if the weight and cost of the blade do not meet the preset design requirements, return to step S1, and adjust the blade structure and material system or aerodynamic shape until the weight and cost of the blade meet the preset design requirements; S8. Perform iterative calculations on the ultimate load and fatigue load according to the blade model until the ultimate load and fatigue load converge, and the optimization design is completed.

[0028] Example 2 The wind turbine blade structure optimization design system disclosed in this example is used to implement the wind turbine blade structure optimization design method described in Example 1, and includes: An initial blade model generation module, which generates an initial blade model according to the initial aerodynamic shape and calculates the ultimate load and fatigue load of the blade according to the initial blade model; wherein, the components of the initial blade model include a main beam, a trailing edge beam, a reinforcement layer and a core material; A main beam optimization module, which optimizes the strain, buckling and deflection of the main beam according to the calculated ultimate load and fatigue load of the blade. The main beams on the suction surface and pressure surface of the blade are divided into n segments at equal intervals, and the ply thickness of each segment of the main beam is set as a variable, and the total number of variables is 2n; A trailing edge beam optimization module, which optimizes the strain and buckling of the trailing edge beam according to the calculated ultimate load and fatigue load of the blade. The trailing edge beam of the blade is divided into m segments at equal intervals, and the ply thickness of each segment of the trailing edge beam is set as a variable, and the total number of variables is m; A reinforcement layer optimization module divides the reinforcement layer at equal intervals starting from the blade root, controls the strain threshold for each segment, performs iterative calculations to obtain the final number of layers of the reinforcement layer, after smoothing the plies, evenly distributes the reinforcement layer on the inner and outer sides and fills it into the model respectively; A core material optimization module sets the minimum buckling coefficient of the shell as the control, takes the core material thickness of each region as a variable, divides the core material at equal intervals, divides it into the core materials of the leading and trailing edges, the pressure surface and the suction surface, performs buckling calculations and iterative calculations until the shell meets the minimum buckling coefficient reaching the set threshold, and then smooths the thickness of the core material plies; A model output module outputs the blade model according to the optimization design results of the main beam optimization module, the trailing edge beam optimization module, the reinforcement layer optimization module and the core material optimization module; A cross-sectional property calculation module calculates the cross-sectional properties of the optimized blade model.

[0029] The specific implementation manner of applying the wind turbine blade structure optimization design system described in this example is as follows: 1) The aerodynamic engineer generates an initial aerodynamic shape according to the externally input boundary conditions and gives it to the structural engineer.

[0030] 2) The structural engineer determines a reasonable blade structure form and material system according to the blade cost and weight target, selects a reasonable template blade, generates an initial blade structure through the initial blade model generation module, and returns the model to the aerodynamic engineer. Note that the rationality of the template blade is the summary of the structural engineer's experience.

[0031] 3) The aerodynamic engineer generates extreme and fatigue loads based on the model and wind condition information and feeds them back to the structural engineer.

[0032] 4) The structural engineer follows the optimization process. Based on the obtained extreme and fatigue loads, the main beam optimization module, the trailing edge beam optimization module, the reinforcement layer optimization module, and the core material optimization module, for each component in turn: the main beam, the trailing edge beam, the reinforcement layer, and the core material, define the variables, constraints, and objectives for component optimization and perform optimization iterations one by one. Calculate the sectional properties of the optimized blade model to obtain the optimized structural model, and calculate the blade weight and cost.

[0033] 5) If the blade weight and cost exceed the initial design requirements, it is necessary to first modify the blade structure form and material system and then perform iterative calculations.

[0034] 6) If the adjustment of the structure form and material system still cannot meet the design requirements, then adjust the aerodynamic shape, and after adjustment, perform iteration again until the requirements are met.

[0035] 7) After the requirements are met, perform load iteration until the load deviation between two calculations of the model is very small, then it is considered that the load converges and the optimization ends.

[0036] 8) If it still cannot be solved after aerodynamic optimization, it is necessary to judge the rationality of the input cost and weight targets or boundary conditions.

[0037] Embodiment 3 This embodiment discloses a non - transitory computer - readable medium storing instructions, which when executed by a processor, perform the steps of the method for optimizing the design of the wind turbine blade structure according to Embodiment 1.

[0038] The non - transitory computer - readable medium in this embodiment can be a magnetic disk, an optical disk, a computer memory, a read - only memory (ROM), a random access memory (RAM), a USB flash drive, a mobile hard disk, or other media.

[0039] Embodiment 4 This embodiment discloses a computing device, including a processor and a memory for storing the executable program of the processor. When the processor executes the program stored in the memory, it implements the method for optimizing the design of the wind turbine blade structure according to Embodiment 1.

[0040] The computing device described in this embodiment may be a desktop computer, a laptop computer, a smart phone, a PDA handheld terminal, a tablet computer, a programmable logic controller (PLC), or other terminal devices with processor functions.

[0041] The above-described embodiments are only the preferred embodiments of the present invention, and do not limit the scope of implementation of the present invention. Therefore, all changes made according to the shape and principle of the present invention should be covered within the protection scope of the present invention.

Claims

1. A method for optimizing the structure of a wind turbine blade, characterized in that: The following steps are involved: S1. Generate an initial blade model according to the initial aerodynamic shape, and calculate the blade limit load and fatigue load according to the initial blade model; wherein the components of the initial blade model include a main beam, a trailing edge beam, a reinforcement layer and a core material; S2. According to the calculated blade limit load and fatigue load, the strain, buckling and deflection of the main beam are optimized. The suction side and pressure side main beams of the blade are divided into n sections with equal spacing. The thickness of the main beam ply is set as a variable in each section, and the total variable is 2n. S3. According to the calculated blade limit load and fatigue load, the trailing edge beam is optimized for strain and buckling. The trailing edge beam of the blade is divided into m sections with equal spacing. The ply thickness of each trailing edge beam is set as a variable, and the total variable is m. S4. Starting from the blade root, the reinforcement layer is divided into equal intervals, and the strain threshold is controlled in each section. The number of layers of the final reinforcement layer is obtained by iterative calculation. After the ply is smoothed, the reinforcement layer is evenly divided into the inner and outer sides and filled into the model respectively. S5. Set the minimum buckling coefficient of the shell as a control, and the thickness of the core material in each area as a variable. Use equidistant to divide the core material into the front and rear edges, pressure surface and suction surface core materials, perform buckling calculations and iterative calculations until the shell meets the minimum buckling coefficient and reaches the set threshold, and then the core material layer is smoothed in thickness; at the same time, set the minimum buckling coefficient of the web as a control, and use the thickness of the web in each area as a variable. When the thickness reaches the preset threshold, the thickness cannot be increased any further, and the web core material needs to be replaced and optimized; use equidistant to divide the web core material for buckling calculations and iterative calculations until the web meets the minimum buckling coefficient and reaches the set threshold, and then the web core layer is smoothed in thickness; S6, summarizing the optimization designs of steps S2 to S5 to obtain a blade model, calculating and outputting the cross-sectional properties of the optimized blade model, and calculating the weight and cost of the blade at the same time; S7, if the weight and cost of the blade do not meet the preset design requirements, return to step S1, and adjust the blade structure and material system or aerodynamic shape until the weight and cost of the blade meet the preset design requirements; S8. Iterate the calculation of the limit load and fatigue load according to the blade model until the limit load and fatigue load converge and the optimization design is completed.

2. A method for optimizing the structure of a wind turbine blade according to claim 1, characterized in that: The step S1 comprises: Generate the initial aerodynamic shape according to the boundary conditions of external input; select the appropriate material system and structural system, and then give the initial structural framework, generate the initial blade model, and estimate the layup of each component, including the initial skin layup, main beam layup, reinforcement layer layup, trailing edge beam layup and shell core material layup; calculate the blade limit load and fatigue load according to the initial blade model, wind conditions and external boundary conditions.

3. The method for optimizing the structure of a wind turbine blade according to claim 1, characterized in that: The step S2 comprises: According to the calculated blade limit load and fatigue load, the main beam is optimized in terms of strain, buckling and deflection. The suction side and pressure side main beams of the blade are layered into n sections at equal intervals. The main beam ply thickness is set as a variable in each section, and the total variable is 2n. Among them, the strain threshold of each section of the main beam material must be less than the set maximum strain value, the first-order buckling coefficient must be greater than the set buckling coefficient, the allowable deflection of the blade tip must be less than the set maximum allowable deflection of the blade tip, and the optimization target is the weight of the main beam.

4. A method for optimizing the structure of a wind turbine blade according to claim 3, characterized in that: The step S2 comprises: Strain optimization design is to calculate the strain of each section of the main beam material according to the limit and fatigue loads, and automatically increase the thickness of each section of the main beam according to the set strain threshold until the strain of all sections meets the requirements; Buckling optimization design is to thicken the core material near the main beam during optimization to ensure that buckling failure occurs on the main beam under the swinging load; after setting the buckling failure eigenvalue and calculating the modal order, perform buckling iteration calculation to determine whether the failure position is on the main beam. If the failure position is on the main beam, record the corresponding main beam material and position, and increase the single-layer thickness of the main beam at the corresponding position in the next iteration; if the failure position is not on the main beam, it will be automatically ignored and iterated until the minimum eigenvalue is greater than the set buckling eigenvalue; The deflection optimization design is to prioritize increasing the number of main beam layers from 2 / 3 of the blade to the tip of the blade, and set an upper limit for the number of layers. If the upper limit is exceeded, the thickness of the main beam in the root area of ​​the blade is adjusted to increase until the blade deflection is less than the set value. If too many main beam layers are added and the set deflection requirement cannot be met, an error warning will be issued; finally, the optimized main beam layers are smoothed to ensure that the layers are operable.

5. The method for optimizing the structure of blades of a wind turbine generator set according to claim 1, characterized in that: The step S3 comprises: According to the calculated blade limit load and fatigue load, the trailing edge beam is optimized for strain and buckling. The blade trailing edge beam is divided into m sections with equal spacing. The ply thickness of each trailing edge beam section is set as a variable, and the total variable is m. The strain threshold of each section of the trailing edge beam material must be less than the set maximum strain value, and the first-order buckling coefficient must be greater than the set buckling coefficient. The optimization target is the weight of the trailing edge beam. The strain of the trailing edge beam material of each section is calculated according to the limit and fatigue loads. According to the set strain threshold, each section of the adjustment ply is automatically increased until the set requirements are fully met; buckling calculation, the minimum buckling eigenvalue is set, and the buckling calculation is iteratively performed to determine whether the failure position is on the trailing edge beam. At the same time, it is determined whether the minimum buckling coefficient is less than the set buckling eigenvalue. If the minimum buckling coefficient is less than the set buckling eigenvalue, the trailing edge beam ply at the corresponding position is automatically increased until all requirements are met; finally, the optimized trailing edge beam ply is smoothed to ensure that the ply is operable.

6. The method for optimizing the structure of a wind turbine blade according to claim 1, characterized in that: The step S4 comprises: The blade reinforcement layer includes an inner reinforcement layer and an outer reinforcement layer, which are axially laid in the area from the blade root to the maximum chord length. The inner and outer reinforcement layers are merged and optimized uniformly. Starting from the blade root, the reinforcement layer is divided into equal intervals, and the strain threshold is controlled in each section. The final number of reinforcement layers is obtained by iterative calculation. After smoothing the layers, the reinforcement layers are evenly divided into inner and outer sides and filled into the model respectively.

7. A method for optimizing the structure of a wind turbine blade according to claim 1, characterized in that: The step S5 comprises: The blade shell is a sandwich structure. The core materials include Balsa, PVC and PET. The minimum buckling coefficient of the shell is set as a control. The thickness of the core material in each area is used as a variable. When the thickness reaches the preset threshold, the thickness cannot be increased any further. In this case, the core material needs to be replaced and then optimized. The core material is divided into leading and trailing edge core materials, pressure surface core materials and suction surface core materials at equal intervals. Buckling calculations are performed and iterative calculations are performed until the shell meets the minimum buckling coefficient and reaches the set threshold. The core material layer is then laid to make the thickness smooth.

8. A wind turbine blade structure optimization design system, characterized in that: The method for optimizing the structure of a wind turbine blade according to any one of claims 1 to 7 comprises: An initial blade model generation module generates an initial blade model according to an initial aerodynamic shape, and calculates the blade limit load and fatigue load according to the initial blade model; wherein the components of the initial blade model include a main beam, a trailing edge beam, a reinforcement layer and a core material; The main beam optimization module optimizes the strain, buckling and deflection of the main beam according to the calculated blade limit load and fatigue load. The suction side and pressure side main beams of the blade are divided into n sections with equal spacing. The main beam ply thickness is set as a variable in each section, and the total variable is 2n. The trailing edge beam optimization module performs strain and buckling optimization design on the trailing edge beam according to the calculated blade limit load and fatigue load. The blade trailing edge beam is divided into m sections with equal spacing. The ply thickness of each trailing edge beam section is set as a variable, and the total variable is m. The reinforcement layer optimization module divides the reinforcement layer at equal distances starting from the blade root, controls the strain threshold of each section, performs iterative calculation to obtain the final number of reinforcement layers, and after smoothing the plies, divides the reinforcement layers evenly into the inner and outer sides and fills them into the model respectively; The core material optimization module sets the minimum buckling coefficient of the shell as a control, and uses the thickness of the core material in each area as a variable. The core material is divided into the front and rear edges, the pressure surface, and the suction surface core material by equidistant spacing. Buckling calculations are performed and iterative calculations are performed until the shell meets the minimum buckling coefficient and reaches the set threshold, and then the core material layer is smoothed in thickness. The model output module outputs the blade model according to the optimization design results of the main beam optimization module, the trailing edge beam optimization module, the reinforcement layer optimization module and the core material optimization module; The section property calculation module calculates the section properties of the optimized blade model.

9. A non-transitory computer-readable medium storing instructions, characterized in that: When the instruction is executed by the processor, the steps of the method for optimizing the structure of a wind turbine blade according to any one of claims 1 to 7 are performed.

10. A computing device comprising a processor and a memory for storing a program executable by the processor, characterized in that: When the processor executes the program stored in the memory, the method for optimizing the structure of a wind turbine blade as described in any one of claims 1 to 7 is implemented.

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