A wind turbine tower section selection method and system

Abstract

The present application belongs to the field of wind power generation, and particularly relates to a wind turbine tower drum plate material selection method and system. The method determines the lowest mass plate material that can be used by the tower drum wall under the existing wall thickness and actual working condition load conditions, and avoids the increase of construction cost and resource waste by reasonably matching the actual working condition and tower drum plate material performance. In the calculation of the tower drum cross section stress, the additional bending moment generated by the tower drum vertical deviation is considered in the used external load, and the tower drum parameters used are also the parameter values at the load position, so the accuracy of the stress calculation result under the external load can be improved. The yield strength value is calculated according to the nominal yield strength of the plate material and the wall thickness reduction, and the nominal yield strength value is selected according to the corresponding yield strength of the relationship between the wall thickness and the nominal yield strength in the national standard, which is equivalent to f y The (t) value is corrected twice according to the wall thickness.

Description

Technical Field

[0001] The present invention belongs to the field of wind power generation, and in particular relates to a method and system for selecting a tower plate material for a wind turbine generator set. Background Art

[0002] my country is rich in wind energy, particularly in the "Three Norths" region, where newly installed wind turbine capacity accounts for a significant portion of the national total. Winter temperatures in these regions are relatively low, requiring wind turbines to possess strong low-temperature resistance. According to relevant wind power industry design standards, the normal operating ambient temperature for wind turbines is generally considered to be between -40°C and 40°C. Low-temperature wind turbine equipment must be able to operate safely and stably at -40°C.

[0003] like Figure 1 As shown, Figure 1 The 1 in the figure represents the wind turbine tower. As the supporting structure of a wind turbine, the tower is often directly exposed to low-temperature environments, bearing loads from the rotor, nacelle, and its own weight, which are then transferred to the foundation. Whether the wind turbine tower wall material can withstand the requirements of low-temperature environments is crucial for the safe and efficient operation of the wind turbine. The most commonly used structural steel material for tower walls is Q355C / D / E (replacing Q345C / D / E in the old standard GB / T 1591-2008). Its low-temperature resistance increases with increasing grade, while its ultimate strength decreases with decreasing temperature. For low-temperature environments, GB / T 1591-2018 stipulates that steel (12mm to 150mm, the thickness of tower components within this range) must meet an impact resistance of at least 34J (Joules) at -40°C.

[0004] Currently, when designing wind turbine towers for low-temperature units, Q355E is generally used as the wall material. However, under appropriate operating conditions, the low-temperature impact performance of Q355C / D can also meet the requirements of low-temperature wind turbines. He Xuan's "Research on the Low-Temperature Toughness of Q345C Steel," published in December 2018, Lu Lin's "Low-Temperature Mechanical Properties of S355 and Q345D," published in October 2012, and Li Peihai's "Research on the Low-Temperature Impact Performance of Q345C / D Structural Steel for Megawatt-Class Wind Turbine Rear Frames," published in September 2020, all conducted a series of experiments on the low-temperature impact performance of hot-rolled Q345C / D. The results showed that at -40°C, the average impact energy of Q355D exceeded the national standard requirement of 34J. The price of Q355E is much higher than that of Q355C / D, and the manufacturing process is more complicated. Therefore, although directly selecting the design method of Q355E can guarantee performance, it may result in increased tower costs and waste of resources. Summary of the Invention

[0005] The purpose of the present invention is to provide a method and system for selecting plate materials for a wind turbine tower, so as to solve the problems of high cost and waste of resources caused by mismatch between material selection and actual working conditions during wind turbine tower design in the prior art.

[0006] In order to achieve the above object, the present invention provides a method for selecting a tower plate material for a wind turbine generator set, comprising the following steps:

[0007] 1) Obtain the actual initial wall thickness of the wind turbine tower and the stress value of the wall under external load;

[0008] 2) Calculate the yield strength f of the wind turbine tower plate y (t), and calculate af y (t) and bf y (t); where 0 <a<b<1;所述风电机组塔筒板材屈服强度f y (t) is calculated based on the nominal yield strength of the plate and the reduced wall thickness; wherein the reduced wall thickness is the smaller value of the thickness of the upper section of the wall or the thickness of the lower section of the wall at the location of the external load; the nominal yield strength of the plate is calculated based on the actual wall thickness and the relationship between the actual wall thickness and the nominal yield strength;

[0009] 3) Determine when selecting a certain quality grade of plate that the plate has y (t), bf y (t) Maximum allowable wall thickness at yield strength;

[0010] 4) When determining the corresponding quality grade of plate, the stress value of the tower wall under the external load is the same as af y (t), bf y (t) Compared with the interval in which it is located, the maximum allowable thickness of the cylinder wall under the external load is obtained;

[0011] 5) Determine whether the actual thickness of the cylinder wall is less than or equal to the maximum allowable value. If so, determine the plate model of the corresponding quality grade. If greater than the maximum allowable value, select a plate of a higher quality grade and repeat steps 4)-5) until the plate model is determined.

[0012] The tower plate selection method can determine the lowest quality grade plate model that can be used for the tower wall under such working conditions based on the existing wall thickness and load conditions. Therefore, it can select plates that match the working conditions, reduce the material cost of the tower while ensuring that normal working conditions are met, and avoid the waste of high-quality grade plates. In addition, when calculating the yield strength of the wind turbine tower plate, the reduced wall thickness that is highly correlated with the external load is taken into account, which is more in line with the actual working conditions of the tower.

[0013] Furthermore, in step 5), if the plate material is of the highest quality grade and the actual thickness of the cylinder wall is still greater than the maximum allowable value, the external load is reduced so that the actual thickness of the cylinder wall satisfies the requirement of being less than or equal to the maximum allowable value.

[0014] Furthermore, in step 4), if the stress value of the cylinder wall under the external load is less than af y (t), then the corresponding plate will be used when af y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load;

[0015] If the stress value of the cylinder wall under the external load is greater than bf y (t), then increase the actual thickness of the cylinder wall, and then repeat steps 1)-3) until the stress value of the cylinder wall under the external load is less than bfy(t);

[0016] If the stress value of the cylinder wall under the external load is in the range [af y (t), bf y (t)], then according to the corresponding plate in af y (t), bf y (t) The corresponding relationship between the yield strength and the maximum allowable value of the cylinder wall thickness. The maximum allowable value of the cylinder wall thickness corresponding to this stress value when the corresponding plate is used is obtained by linear interpolation.

[0017] Furthermore, in step 2) cf is also calculated y (t), where a <c<b;确定在选用某种质量等级的板材时,该板材在af y (t), cf y (t), bf y (t) The maximum allowable wall thickness at yield strength, and by using the corresponding quality grade of plate, the stress value of the tower wall under external load is the same as af y (t), cf y (t), bf y (t) Compared with the interval in which it is located, the maximum allowable thickness of the cylinder wall under external load is obtained.

[0018] Dividing the interval used for comparison with the stress value more finely can improve the accuracy of the comparison result, thereby obtaining a more accurate maximum allowable thickness value.

[0019] Furthermore, in step 4), if the stress value of the cylinder wall under the external load is less than af y (t), then the corresponding plate will be used when af y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load;

[0020] If the stress value of the cylinder wall under the external load is greater than bf y (t), the actual thickness of the cylinder wall is increased, and then steps 1)-3) are repeated until the stress value of the cylinder wall under the external load is less than bf

[0021] If the stress value of the cylinder wall under the external load is in the interval [af y (t), cf y (t)] or [cf y (t), bf y (t)], the maximum allowable thickness of the cylinder wall corresponding to the stress value when the corresponding plate is used is obtained by linear interpolation according to the corresponding relationship between the yield strength of the corresponding plate at af y (t), cf y (t), bf y (t) and the maximum allowable thickness of the cylinder wall.

[0022] The interval division for linear interpolation is more detailed, which can improve the fitting precision of the linear interpolation method, so as to obtain a maximum allowable thickness with higher accuracy.

[0023] Further, in step 1), the stress value of the cylinder wall under the external load is calculated by the following formula:

[0024] σ eqv =(σ n 2 +3τ 2 )^0.5;

[0025] In the formula, σ n =(Mxy+ΔMxy) / w+abs(Fz / s), σ n is the normal stress; τ=Mz / W p +abs(Fxy / s), τ is the shear stress;

[0026] where W=πr 2 t min , W is the bending section modulus at the load position; W p is the torsional section modulus at the load position, W p =2πr 2 t min ; S is the cross-sectional area at the load position, S=2πrt min ; r is the mean diameter of the cylinder wall at the load position, r=(D-t) / 2; D is the outer diameter of the cylinder wall at the load position; t min is the reduced thickness of the cylinder wall;

[0027] Mxy, Mz, Fxy, Fz and AMxy are all load components, wherein AMxy is an additional bending moment generated by vertical deviation of the tower drum caused by factors such as tower drum manufacturing defects, unidirectional solar radiation, tower and foundation inclination; Mxy is a resultant bending moment of bending moments Mx and My around X and Y axes respectively; Mz is a torque around Z axis; Fxy is a resultant force of forces Fx and Fy along X and Y axes respectively; and Fz is an external force along Z axis.

[0028] In the calculation of the external load stress borne by the tower drum, the stress parameters used take into account the additional bending moment AMxy generated by vertical deviation of the tower drum caused by factors such as tower drum manufacturing defects, unidirectional solar radiation, tower and foundation inclination, and the drum wall thickness parameters, cross-section modulus parameters and drum wall cross-section parameters used are all parameters collected at corresponding load positions, and have stronger correlation with load stress, so the calculation result is more accurate.

[0029] Further, the calculation formula of the additional bending moment is as follows:

[0030] AMxy, i =G i,d * Ah i * s + AMxy, i-1

[0031] In the formula, AMxy, i is an additional bending moment of the drum wall at the current load position; G i,d is a gravity value of the current drum wall; Ah i is a height of the current drum wall; s is a vertical deviation amount of the tower drum; AMxy, i-1 is an additional bending moment value of the upper section drum wall.

[0032] Further, the yield strength f y (t) of the wind turbine tower drum plate material is f y,nom - 0.25t min , wherein f y,nom is a nominal yield strength of the plate material, and t min is a drum wall reduced thickness.

[0033] Further, in order to make the interval division more uniform, the value of a is 0.25, the value of b is 0.75, and the value of c is 0.5.

[0034] The application further provides a wind turbine tower drum plate material selection system comprising a processor configured to execute program instructions to implement the wind turbine tower drum plate material selection method described above. The system can achieve the same beneficial effects as the wind turbine tower drum plate material selection method described above. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1A schematic diagram of a wind turbine tower in the background technology of the present invention;

[0036] Figure 2 This is a flow chart of a tower plate selection method in an embodiment of a method for selecting a tower plate for a wind turbine generator system according to the present invention;

[0037] Figure 3 Schematic diagram of the geometric structure of a wind turbine tower in an embodiment of the method for selecting plate materials for a wind turbine tower according to the present invention;

[0038] Figure 4 A schematic diagram of the outer diameter and median diameter of a wind turbine tower in an embodiment of the method for selecting a plate material for a wind turbine tower according to the present invention;

[0039] Among them, 1 is the wind turbine tower, 2 is the lower section of the tower wall where the external load is located, 3 is the location of the external load, and 4 is the upper section of the tower wall where the external load is located. DETAILED DESCRIPTION

[0040] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.

[0041] Example of a method for selecting a tower plate material for a wind turbine generator set

[0042] This embodiment provides a technical solution for selecting a tower plate material for a wind turbine generator set. Figure 2 , the specific steps are as follows:

[0043] 1) Obtain the actual initial wall thickness of the wind turbine tower and the stress value of the wall under external load.

[0044] Among them, the initial actual thickness of the tower wall refers to the original thickness of the wall in the tower design model; in a preferred embodiment, the initial actual thickness of the wall is the initial thickness of the wall obtained after tower wall verification items such as tower wall weld strength, buckling strength and vortex-induced strength verification, and then this initial thickness is used as the initial value of the actual thickness of the wall.

[0045] The external load used in this embodiment is based on the tower base coordinate system defined in the GL2010 specification. The stress value of the cylinder wall under the external load can be calculated using the following formula:

[0046] σ eqv =(σ n 2 +3τ 2 )^0.5;

[0047] Where σ n =(Mxy+ΔMxy) / w+abs(Fz / s),σ n is the normal stress; τ=Mz / Wp +abs(Fxy / s), τ is the shear stress; where W = πr 2 t min , W is the bending section modulus at the load position; W p is the torsional section modulus at the load location, W p =2πr 2 t min ; S is the cross-sectional area at the load position, S = 2πrt min ; r is the median diameter of the cylinder wall at the load position, r = (Dt) / 2; D is the outer diameter of the cylinder wall at the load position; t min The thickness of the cylinder wall is reduced. Figure 3 The load is applied at the upper height 3 of cylinder section 2. The reduced wall thickness is the smaller of the thickness of the upper section wall 4 at the location of the external load or the thickness of the lower section wall 2. This reduced thickness is used to calculate the maximum stress at this location, better reflecting the effect of the external load on the cylinder wall at this location.

[0048] Figure 4 Schematic diagram of the outer diameter and median diameter of the wind turbine tower, where r is the median diameter of the tower wall at the load position, and D is the outer diameter of the tower wall at the load position.

[0049] Mxy, Mz, Fxy, Fz and ΔMxy are all load components, among which ΔMxy is the additional bending moment caused by the vertical deviation of the tower due to tower manufacturing defects, unidirectional solar radiation, and the inclination of the tower and foundation; Mxy is the sum of the bending moments Mx and My around the X and Y axes respectively; Mz is the torque around the Z axis; Fxy is the sum of the forces Fx and Fy along the X and Y axes respectively; and Fz is the external force along the Z axis.

[0050] The specific calculation formula for the additional bending moment is as follows:

[0051] ΔMxy, i =G i,d *Δh i *s+ΔMxy, i-1

[0052] Where: ΔMxy, i is the additional bending moment of the cylinder wall at the current load position; G i,d is the current gravity value of the cylinder wall; Δh i is the current wall height; s is the vertical deviation of the tower; ΔMxy, i-1 is the additional bending moment value at the upper cylinder wall

[0053] It can be seen from the above formula that the stress parameters used in calculating stress take into account the additional bending moment ΔMxy caused by the vertical deviation of the tower due to factors such as tower manufacturing defects, unidirectional solar radiation, and the inclination of the tower and foundation. In addition, the wall thickness parameters, section modulus parameters, and wall section parameters used are also parameters collected at the corresponding load position, which are more closely related to the load stress, so the calculation results are more accurate.

[0054] 2) Calculate the yield strength f of the wind turbine tower plate y (t), and calculate af y (t) and bf y (t); where 0 <a<b<1;风电机组塔筒板材屈服强度f y (t) is calculated by the nominal yield strength of the plate and the reduced thickness of the tube wall. The specific calculation formula is:

[0055] f y (t) = f y,nom -0.25t min ;

[0056] where f y (t) is the yield strength of the wind turbine tower plate, f y,nom is the nominal yield strength of the plate, t min is the reduced thickness of the cylinder wall. y,nom The value of a should be selected according to the thickness range specified in Table 9 of GB / T 1591-2018 Low Alloy High Strength Structural Steel to select the corresponding yield strength. In this embodiment, the value of a is 0.25 and the value of b is 0.75.

[0057] 3) Determine when selecting a certain quality grade of plate that the plate has y (t), bf y (t) Maximum allowable wall thickness at yield strength.

[0058] Taking Q355C plate as an example, according to Table 2.1 in the specification "BS EN 1993-1-10:2005", the corresponding values ​​of Q355C (corresponding to S355-J0 in the table) under the working condition of -40° are 0.25f y (t), 0.75f y (t) Maximum allowable value of cylinder wall thickness at yield strength t max_0.25 , t max_0.5 , t max_0.75 .

[0059] 4) When determining the corresponding quality grade of plate, the stress value of the tower wall under the external load is the same as af y (t), bf y(t) is compared with the range in which it is located to obtain the maximum allowable thickness of the cylinder wall under external load. The specific method is as follows:

[0060] If the stress value of the cylinder wall under the external load is less than af y (t), then the corresponding plate will be used when af y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load;

[0061] If the stress value of the cylinder wall under the external load is greater than bf y (t), then increase the actual thickness of the cylinder wall, and then repeat steps 1)-3) until the stress value of the cylinder wall under the external load is less than bfy(t);

[0062] If the stress value of the cylinder wall under the external load is in the range [af y (t), bf y (t)], then according to the corresponding plate in af y (t), bf y (t) The corresponding relationship between the yield strength and the maximum allowable value of the cylinder wall thickness. The maximum allowable value of the cylinder wall thickness corresponding to this stress value when the corresponding plate is used is obtained by linear interpolation.

[0063] In a preferred embodiment, the above steps 2)-4) also use cf y (t), where a <c<b;确定在选用某种质量等级的板材时,该板材在af y (t), cf y (t), bf y (t) The maximum allowable wall thickness at yield strength, and by using the corresponding quality grade of plate, the stress value of the tower wall under external load is the same as af y (t), cf y (t), bf y (t) Compared with the interval in which it is located, the maximum allowable thickness of the cylinder wall under external load is obtained.

[0064] In this preferred embodiment, the value of a is 0.25, the value of b is 0.75, and in order to make the interval division more uniform, the value of c is 0.5. Taking the Q355C plate as an example, according to Table 2.1 in the specification "BS EN 1993-1-10:2005", the values ​​of Q355C (corresponding to S355-J0 in the table) under the working condition of -40° are 0.25f and y (t), 0.5f y (t), 0.75f y (t) Maximum allowable value of cylinder wall thickness at yield strength t max_0.25 , tmax_0.5 , t max_0.75 .

[0065] If the stress value of the cylinder wall under the external load is less than 0.25f y (t), no interpolation calculation is performed, and the corresponding plate value 0.25f is directly used. y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load; if the stress value of the cylinder wall under external load is greater than 0.75f y (t), then increase the actual thickness of the cylinder wall, and then repeat steps 1)-3) until the stress value of the cylinder wall under the external load is less than 0.75fy(t); if the stress value of the cylinder wall under the external load is in the range [0.25f y (t), 0.5f y (t)] or [0.5f y (t), 0.75f y (t)], then according to the corresponding plate at 0.25f y (t), 0.5f y (t), 0.75f y (t) The corresponding relationship between the yield strength and the maximum allowable value of the cylinder wall thickness. The maximum allowable value of the cylinder wall thickness corresponding to this stress value when the corresponding plate is used is obtained by linear interpolation.

[0066] This preferred embodiment can improve the accuracy of the comparison result by dividing the interval used for comparison with the stress value more finely, thereby obtaining a maximum allowable thickness value with higher accuracy.

[0067] In other embodiments, by continuing to add y (t), bf y (t)] y (t), ef y (t) and other yield strengths, more intervals can be divided. The finer the interval division, the higher the accuracy of linear interpolation may be, but the corresponding calculation amount will increase. Therefore, the number of yield strength intervals can be determined based on the actual accuracy and calculation amount requirements.

[0068] 5) Determine whether the actual thickness of the cylinder wall is less than or equal to the maximum allowable thickness. If it is less than or equal to the maximum allowable value, determine the plate model of the corresponding quality grade; if it is greater than the maximum allowable value, select a plate of a higher quality grade and repeat steps 4)-5) until the plate model is determined.

[0069] The quality grade here can refer to the classification of plate models in the national standard "GB / T 1591-2018 Low Alloy High Strength Structural Steel". This classification is equivalent to the quality classification given after comprehensive consideration of steel performance. The quality is divided into Q355C / D / E and other models from poor to good (from low to high); taking Q355C model plate as an example, if the actual thickness of the cylinder wall obtained in step 1) is less than or equal to the maximum allowable value calculated in step 4), then Q355C model plate is selected for the cylinder wall of the wind turbine; if it is greater than the maximum allowable value, a higher quality grade is selected. Repeat steps 4)-5) to calculate the new maximum allowable value and make a judgment. If the actual thickness of the cylinder wall is less than or equal to the new maximum allowable value, then determine to select Q355D type plate for the cylinder wall of the wind turbine; similarly, if it is greater than the maximum allowable value, take a higher quality grade plate Q355E, repeat steps 4)-5) to calculate the new maximum allowable value and make a judgment. If the actual thickness of the cylinder wall is less than or equal to the new maximum allowable value, then determine to select Q355E type plate for the cylinder wall of the wind turbine.

[0070] Q355E can be regarded as the highest quality grade of plate. If the plate is of the highest quality grade and the actual thickness of the cylinder wall is still greater than the corresponding maximum allowable value, it is necessary to reduce the external load so that the actual thickness of the cylinder wall is less than or equal to the maximum allowable value.

[0071] The characteristics of the wind turbine tower plate selection method of the present invention are as follows:

[0072] This method determines the minimum plate model that can be used for the tower wall under the existing wall thickness and actual working load conditions. By reasonably matching the actual working conditions with the tower plate performance, it avoids increased tower construction costs and waste of resources.

[0073] When calculating the tower section stress, the wall thickness used is the minimum value of the thickness of the upper section wall and the thickness of the lower section wall at the corresponding load position. min , and the external load used takes into account the additional bending moment ΔMxy caused by the vertical deviation of the tower caused by factors such as tower manufacturing defects, unidirectional solar radiation, tower and foundation inclination, etc., and uses the wall median diameter r and the minimum wall thickness t min Calculate the bending section modulus W at the load location n , torsional section modulus W p , cross-sectional area S, thus improving the accuracy of the calculation results of external load stress.

[0074] The yield strength f used in this method y (t) value is based on the formula f y (t) = f y,nom -0.25t min Calculate the corrected, and fy,nom When taking the value, the corresponding yield strength is selected according to the thickness range specified in Table 9 of the national standard "GB / T 1591-2018 Low Alloy High Strength Structural Steel", which is equivalent to the f obtained in the present invention. y The (t) value was stress-corrected twice according to the cylinder wall thickness.

[0075] Wind turbine tower plate selection system implementation

[0076] This embodiment provides a technical solution for a wind turbine tower plate selection system. The system includes a processor configured to execute program instructions to implement the wind turbine tower plate selection method described in the aforementioned embodiment, achieving the same beneficial effects as the aforementioned wind turbine tower plate selection method. The specific principles of the system and the program instructions executed have been described in detail in the aforementioned embodiment of the wind turbine tower plate selection method and will not be further elaborated here.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A method for selecting a tower plate material for a wind turbine generator set, characterized in that: Here are the steps: 1) Obtain the actual initial wall thickness of the wind turbine tower and the stress value of the wall under external load; 2) Calculate the yield strength f y (t) of the tower barrel plate of the wind turbine, and calculate af y (t) and bf y (t) respectively; where 0 < a < b < 1; the yield strength f y (t) of the tower barrel plate of the wind turbine is obtained by calculating the nominal yield strength of the plate and the reduced thickness of the barrel wall; where the reduced thickness of the barrel wall is the smaller value of the upper barrel wall thickness and the lower barrel wall thickness at the position where the external load is located; the nominal yield strength of the plate is obtained according to the actual thickness of the barrel wall and the relationship between the actual thickness of the barrel wall and the nominal yield strength; 3) Determine when selecting a certain quality grade of plate that the plate has y (t), bf y (t) Maximum allowable wall thickness at yield strength; 4) When determining the corresponding quality grade of plate, the stress value of the tower wall under the external load is the same as af y (t), bf y (t) Compared with the interval in which it is located, the maximum allowable thickness of the cylinder wall under the external load is obtained; 5) Determine whether the actual thickness of the cylinder wall is less than or equal to the maximum allowable value. If so, determine the plate model of the corresponding quality grade. If greater than the maximum allowable value, select a plate of a higher quality grade and repeat steps 4)-5) until the plate model is determined.

2. The method for selecting a tower plate material for a wind turbine generator set according to claim 1, wherein: In step 5), if the actual thickness of the cylinder wall is still greater than the maximum allowable value when the plate is of the highest quality grade, the external load is reduced so that the actual thickness of the cylinder wall is less than or equal to the maximum allowable value.

3. The method for selecting a tower plate material for a wind turbine generator set according to claim 1, wherein: In step 4), if the stress value of the cylinder wall under the external load is less than af y (t), then the corresponding plate will be used when af y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load; If the stress value of the cylinder wall under the external load is greater than bf y (t), then increase the actual thickness of the cylinder wall, and then repeat steps 1)-3) until the stress value of the cylinder wall under the external load is less than bf y (t); If the stress value of the cylinder wall under the external load is in the range [af y (t), bf y (t)], then according to the corresponding plate in af y (t), bf y (t) The corresponding relationship between the yield strength and the maximum allowable value of the cylinder wall thickness. The maximum allowable value of the cylinder wall thickness corresponding to this stress value when the corresponding plate is used is obtained by linear interpolation.

4. The method for selecting a tower plate material for a wind turbine generator set according to claim 1, wherein: cf is also calculated in step 2) y (t), where a < c < b; when selecting a certain quality grade of plate, the maximum allowable value of the thickness of the cylinder wall at the yield strength of af y (t), cf y (t), bf y (t) is determined, and by using the plate of the corresponding quality grade, the stress value of the cylinder wall of the tower under the external load is compared with af y (t), cf y (t), bf y (t), and the maximum allowable value of the thickness of the cylinder wall under the external load is obtained from the interval in which it is located.

5. The method for selecting a tower plate material for a wind turbine generator set according to claim 4, wherein: In step 4), if the stress value of the cylinder wall under the external load is less than af y (t), then the corresponding plate will be used when af y (t) The maximum allowable value of the cylinder wall thickness at the yield strength is used as the maximum allowable value of the cylinder wall thickness under external load; If the stress value of the cylinder wall under the external load is greater than bf y (t), then increase the actual thickness of the cylinder wall, and then repeat steps 1)-3) until the stress value of the cylinder wall under the external load is less than bfy(t); If the stress value of the cylinder wall under the external load is in the range [af y (t), cf y (t)] or [cf y (t), bf y (t)], then according to the corresponding plate in af y (t), cf y (t), bf y (t) The corresponding relationship between the yield strength and the maximum allowable value of the cylinder wall thickness. The maximum allowable value of the cylinder wall thickness corresponding to this stress value when the corresponding plate is used is obtained by linear interpolation.

6. The method for selecting a tower plate material for a wind turbine generator set according to any one of claims 1 to 5, characterized in that: In step 1), the stress value of the cylinder wall under the external load is calculated by the following formula: s eqv =(s n 2 +3t 2 )^0.5; Where σ n =(Mxy+ΔMxy) / W+abs(Fz / S),σ n is the normal stress; τ=Mz / W p +abs(Fxy / S), τ is the shear stress; Where W = πr 2 t min , W is the bending section modulus at the load position; W p is the torsional section modulus at the load location, W p =2πr 2 t min ; S is the cross-sectional area at the load position, S = 2πrt min ; r is the median diameter of the cylinder wall at the load position, r = (Dt) / 2; D is the outer diameter of the cylinder wall at the load position; t min is the reduced thickness of the cylinder wall; Mxy, Mz, Fxy, Fz and ΔMxy are all load components, among which ΔMxy is the additional bending moment caused by the vertical deviation of the tower due to tower manufacturing defects, unidirectional solar radiation, and the inclination of the tower and foundation; Mxy is the sum of the bending moments Mx and My around the X and Y axes respectively; Mz is the torque around the Z axis; Fxy is the sum of the forces Fx and Fy along the X and Y axes respectively; and Fz is the external force along the Z axis.

7. The method for selecting plate materials for wind turbine tower according to claim 6, characterized in that: The calculation formula for the additional bending moment is as follows: ΔMxy,i=G i,d *Δh i *s+ΔMxy,i-1 Where: ΔMxy,i is the additional bending moment of the cylinder wall at the current load position; G i,d is the current gravity value of the cylinder wall; Δh i is the height of the current cylinder wall; s is the vertical deviation of the tower; ΔMxy,i-1 is the additional bending moment value at the upper cylinder wall.

8. The method for selecting a tower plate material for a wind turbine generator set according to claim 1, wherein: The yield strength f of the wind turbine tower plate y (t) = f y,nom -0.25t min , where f y,nom is the nominal yield strength of the plate, t min The thickness of the cylinder wall is reduced.

9. The method for selecting plate materials for a wind turbine tower according to claim 4 or 5, characterized in that: The value of a is 0.25, the value of b is 0.75, and the value of c is 0.

5.

10. A wind turbine tower plate selection system, characterized in that: The method comprises a processor configured to execute program instructions to implement the method for selecting a tower plate material for a wind turbine generator set according to any one of claims 1 to 9.

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