CN112069588A - Method and system for predicting buckling stability of wind turbine generator tower - Google Patents
Method and system for predicting buckling stability of wind turbine generator tower Download PDFInfo
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Abstract
The invention provides a method and a system for predicting the buckling stability of a wind turbine tower, which comprises the following steps: calculating the buckling allowance of each section of the tower frame based on the stress parameter of each section of the tower frame; calculating the reduction coefficient of the section of the tower door by using the constructed tower door finite element model; obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section; and determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door. The method adopts a mode of combining an engineering algorithm and a finite element, quickly and accurately calculates the buckling stability of the tower, improves the calculation accuracy, shortens the calculation time, improves the working efficiency, can provide technical service for each host factory, and has wide application prospect.
Description
Technical Field
The invention relates to the field of wind turbine generators, in particular to a method and a system for predicting the buckling stability of a wind turbine generator tower.
Background
The modern large-scale wind turbine tower adopts a thin-wall cylindrical structure, the height of the tower is about 100m, the diameter of the bottom of the tower is about 5m, and the wall thickness of the tower is less than 1/100 of the diameter, so that the tower belongs to a typical slender thin-wall structure. In practical application, the bottom of the wind turbine tower is fixed, the top of the wind turbine tower is free and bears the gravity and wind load of a cabin and a wind wheel, and the structural form is easy to be unstable. With the continuous increase of the single-machine capacity of the wind turbine generator, the weight and the overall dimension are increased, the height of the tower is increased, and the gravity load and the pneumatic load acting on the tower are more obvious. The stability and the safety of the wind turbine tower are the guarantee of the safe operation of the wind turbine, so the research on the stability of the wind turbine has been widely concerned.
In the aspect of structural buckling stability research, the classical solid mechanics form a rich theoretical result in the aspect of column shell buckling. In the early 20 th century, researchers applied linear theory to obtain some theoretical results of column shells and provided famous critical load formulas of instability of axial compression column shells and external pressure spherical shells. In 1934, Donnell established a nonlinear column shell large-disturbance-degree equation by applying a nonlinear large-disturbance-degree theory. The wind turbine tower belongs to a slender thin-wall structure, a cabin and a wind wheel with larger mass are supported at the top, and buckling is a main damage form of the structure. The buckling strength of the cylindrical shell under the action of axial compression is researched by Seung-Eock Kim and the like, the buckling strength is estimated by applying a numerical analysis method, the conclusion that the buckling strength can be rapidly reduced along with the increase of the diameter-to-thickness ratio of the shell and slightly reduced along with the increase of the height-to-diameter ratio of the shell is obtained, and the conclusion is also applicable to the wind turbine tower. Chengxinghua and the like analyze the buckling of the cylindrical shell under the axial pressure load, point out that the stiffened plate is beneficial to improving the buckling performance of the cylindrical shell, but do not carry out systematic research on the buckling problem of the wind turbine tower caused by the action of the load of a wind wheel and an engine room and the self gravity of the tower.
In the prior art, a finite element buckling analysis is adopted to establish a tower model, divide grids, assume that the bottom of a tower is fixedly connected with a foundation, a load application point is arranged at the top of the tower, and then linear buckling analysis is carried out. The linear buckling analysis is based on the assumption of a small displacement linear theory, changes of the structure shape are ignored in the process that the structure is under the action of load, linear buckling loads and corresponding instability modes under different load modes can be solved, and the linear buckling problem can be converted into the characteristic value problem shown as follows:
([K 0 ]+λ i [K σ ])v i =0
in the formula (2)K 0 ]Is an initial stiffness matrixK σ ]In the form of a stress-stiffness matrix,λ i is as followsiThe characteristic value, i.e. the ratio of the buckling load to the actual load,v i is as followsiA feature vector.
In the prior art, an integral finite element method is adopted, a complete finite element model of the tower needs to be established, the model scale is large, the processing of complex load conditions and boundary conditions is limited, and the calculation is slow. And the tower design is a process of repeatedly modifying and iterating, a finite element model needs to be reestablished every time the tower appearance design is changed, and the workload is huge. Meanwhile, the existing wind turbine generator is in an express development stage, technicians can quickly respond to a new design, and the existing technology is not suitable for engineering technology application.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides a method for predicting the buckling stability of a wind turbine tower, which comprises the following steps:
calculating the buckling allowance of each section of the tower frame based on the stress parameter of each section of the tower frame;
calculating the reduction coefficient of the section of the tower door by using the constructed tower door finite element model;
obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
and determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
Preferably, the calculating the buckling margin of each section of the tower based on the stress parameter of each section of the tower includes:
calculating the total compressive stress and the total shear stress of each section of the tower on the basis of the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
respectively calculating axial ideal buckling stress and shearing ideal buckling stress of each section of the tower on the basis of the wall thickness and the radius of each section of the tower;
calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
and calculating the buckling allowance of each section of the tower based on the total compressive stress, the total shear stress and the ultimate buckling stress of each section of the tower.
Preferably, the total compressive stress of each section of the tower is calculated according to the following formula:
σ x= σ x,m +σ x,p
in the formula:σ x the total compressive stress of each section of the tower;σ x,m stress for the main moment;σ x,m= M∕W b ；Mis the main moment;W b bending section stiffness;σ x,p stress due to gravity;
；Ais the cross-sectional area;Pis gravity;
the total shear stress of each section of the tower is calculated according to the following formula:
τ=τ v +τ t
in the formula:τthe total shear stress of each section of the tower;τ v shear stress generated for shear force;
，Vis a shear force;τ t shear stress for torque;
，W t torsional section stiffness;M t is the torque.
Preferably, the axial ideal buckling stress of each section of the tower is calculated according to the following formula:
in the formula:σ x,Rct the axial ideal buckling of each section of the tower is achieved;E: the modulus of elasticity of the steel;C x is an axial coefficient;tthe wall thickness of the tower section;ris the radius of the tower section;
wherein the axial coefficientC x The values of (A) include:
when in useωWhen the height is less than or equal to 1.7, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC x =1.0；
When in use
The tower is a long rod, thenC x Take a total of 0.6 and
the one with the larger median value;
when in use
、
And is
When it is, then
；
In the formula:ωis a dimensionless parameter;C xb is a support form parameter;C x,N is a standard axial coefficient;f yk is the yield strength of the material;σ x,p stress due to gravity;σ x the total compressive stress of each section of the tower;σ x,m stress for the dominant moment.
Preferably, before calculating the axial ideal buckling stress of each section of the tower, the judgment needs to be performed according to the wall thickness of the section of the tower, the radius of the section of the tower and the yield strength of the material of the tower:
when it is satisfied with
If not, calculating the axial ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
Preferably, the shear ideal buckling stress of each section of the tower is calculated according to the following formula:
wherein:τ xθ,Rcr the ideal bending stress for shearing each section of the tower;C τ : a shear coefficient;E: the modulus of elasticity of the steel;ωis a dimensionless parameter;t: wall thickness of tower section;r: the radius of the tower section;
wherein the shear coefficientC τ The values of (A) include:
when in useω<When 20, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC τ =1.0；
When in use
The tower is a long rod, then
。
Preferably, before calculating the shear ideal buckling stress of each section of the tower, the judgment needs to be performed according to the wall thickness of the section of the tower, the radius of the section of the tower and the yield strength of the material of the tower:
when it is satisfied with
If so, not calculating the shearing buckling stress, otherwise, calculating the shearing ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
Preferably, the calculating of the ultimate buckling stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower includes:
obtaining the length fineness of the tower caused by compressive stress and the length fineness of the tower caused by shear stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower;
calculating an axial buckling reduction coefficient and a shearing buckling reduction coefficient based on the length fineness caused by the compressive stress and the length fineness caused by the shearing stress of the tower;
calculating axial characteristic buckling stress and shearing characteristic buckling stress based on the axial buckling reduction coefficient, the shearing buckling reduction coefficient and the yield strength;
and calculating the axial limit buckling stress and the shear limit buckling stress based on the axial characteristic buckling stress and the shear characteristic buckling stress.
Preferably, the calculation formula of the axial ultimate buckling stress is as follows:
τ x,Rd = τ x, Rk / γ M
in the formula:σ x,Rd axial ultimate buckling stress;σ x,Rk is the axial characteristic buckling stress; gamma ray M The safety coefficient of the material is set;
the shear limit buckling stress is calculated by the following formula:
τ xθ,Rd = τ xθ,Rk / γ M
in the formula:τ xθ,Rd shear ultimate buckling stress;τ xθ,Rk is a shear characteristic buckling stress.
Preferably, the buckling margin of each section of the tower is calculated according to the following formula:
in the formula:SME buckling the buckling allowance of each section of the tower is taken;σ x the total compressive stress of each section of the tower;σ x,Rd axial ultimate buckling stress;k x is an axial buckling interaction parameter;τthe total shear stress of each section of the tower;τ xθ,Rd shear ultimate buckling stress;k τ is a shear buckling interaction parameter.
Preferably, the determining the stability of the wind turbine tower based on the buckling margin of each section of the wind turbine tower and the buckling margin of the section of the tower door includes:
when the buckling allowance of each section of the wind turbine generator tower and the buckling allowance of the section of the tower door respectively meet set threshold values, the stability of the wind turbine generator tower meets requirements, and otherwise, the stability of the wind turbine generator tower does not meet requirements.
Based on the same invention concept, the invention also provides a system for predicting the buckling stability of the wind turbine tower, which comprises the following steps:
the buckling allowance module is used for calculating buckling allowances of the sections of the tower based on the stress parameters of the sections of the tower;
the module for calculating the reduction coefficient of the cross section of the tower door is used for calculating the reduction coefficient of the cross section of the tower door by utilizing the constructed finite element model of the tower door;
the buckling allowance module of the tower door section is used for obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
and the stability analysis module is used for determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
Preferably, the module for calculating the buckling margin of each section of the tower is specifically configured to:
calculating the total compressive stress and the total shear stress of each section of the tower on the basis of the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
respectively calculating the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower by the length of the tower;
calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
and calculating the buckling allowance of each section of the tower based on the total compressive stress, the total shear stress and the ultimate buckling stress of each section of the tower.
Compared with the prior art, the invention has the beneficial effects that:
according to the technical scheme provided by the invention, the buckling allowance of each section of the tower is calculated based on the stress parameter of each section of the tower; calculating the reduction coefficient of the section of the tower door by using the constructed tower door finite element model; obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section; the method and the device have the advantages that the buckling stability of the wind turbine tower is rapidly and accurately calculated by combining an engineering algorithm and a finite element, so that the calculation accuracy is improved, the calculation time is shortened, the working efficiency is improved, technical services can be provided for various host plants, and the method and the device have wide application prospects.
Drawings
FIG. 1 is a flow chart of a method for predicting the buckling stability of a wind turbine tower in the present invention;
fig. 2 is a schematic diagram of a system architecture for predicting the buckling stability of a wind turbine tower in the present invention.
Detailed Description
For a better understanding of the present invention, reference is made to the following description taken in conjunction with the accompanying drawings and examples.
With the development and continuous improvement of modern wind power technology, in order to reduce the cost of wind power generation and improve the market competitiveness of energy development, wind turbine generators are rapidly developing towards high power, which means that the size of the wind turbine generators is continuously increased and the height of a tower is continuously increased. The wind turbine tower serves as a main supporting structure of the whole wind turbine, the safety performance of the wind turbine tower directly influences whether the wind turbine normally works, and therefore the tower must have sufficient strength and rigidity. In order to ensure that the tower can normally operate within the design life of the tower and improve the safety of the tower, the overall stability analysis of the tower must be performed.
As shown in fig. 1, the invention provides a method for predicting the buckling stability of a wind turbine tower, which comprises the following steps:
s1, calculating the buckling allowance of each section of the tower based on the stress parameter of each section of the tower;
s2, calculating the reduction coefficient of the section of the tower door by using the constructed tower door finite element model;
s3, obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
s4 determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
As the wind generating set tower serves as a main supporting structure of the whole wind generating set, the safety performance of the wind generating set tower directly influences whether the wind generating set normally works or not, and therefore the tower must have sufficient strength and rigidity. In order to ensure that the tower can normally operate within the design life of the tower and improve the safety of the tower, stability analysis must be performed on the tower. In the prior art, an integral finite element method is adopted, the quantity of model meshes is huge, the calculation is slow, the tower design is a process of repeatedly modifying and iterating, and a finite element model cannot respond quickly. The method adopts a mode of combining an engineering algorithm and a finite element, quickly and accurately calculates the buckling stability of the tower, improves the calculation accuracy, shortens the calculation time, improves the working efficiency, can provide technical service for each host factory, and has wide application prospect.
The method for analyzing the buckling of the wind turbine generator system tower comprises the steps of calculating buckling allowance of each section of the tower and buckling allowance of each section of the tower door, when the buckling allowance of each section of the tower door is calculated, firstly calculating a reduction coefficient of each section of the tower door through a finite element model of each section of the tower door, and then obtaining the buckling allowance of each section of the tower door according to the buckling allowance of each section of the tower and the reduction coefficient of each section of the tower door.
In this embodiment, the step of calculating the buckling margin of each section of the tower based on the stress parameter of each section of the tower in S1 may include:
s11, calculating the total compressive stress and the total shear stress of each section of the tower based on the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
s12, respectively calculating axial ideal buckling stress and shearing ideal buckling stress of each section of the tower based on the wall thickness and the radius of each section of the tower;
s13, calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
s14, calculating the buckling allowance of each section of the tower based on the total compression stress, the total shear stress and the ultimate buckling stress of each section of the tower.
In this embodiment, S11 calculates total compressive stress and total shear stress of each section of the tower based on the moment, gravity, bending section stiffness, section area, shear force, and torque applied to each section of the tower, and specifically includes:
total compressive stress:σ x= σ x,m +σ x,p
stress generated by the main moment:σ x,m= M∕W b
stress due to gravity:
wherein:σ x as a tower frameThe total compressive stress of each section;σ x,m stress for the main moment;σ x,p stress due to gravity;Ais the cross-sectional area;W b bending section stiffness;Pin order to be the gravity force, P =F z ；Mis a main moment of force, passing
And (4) calculating.
Total shear stress:τ=τ v +τ t
shear stress by shear force:
shear stress by torque:
wherein:τthe total shear stress of each section of the tower;τ v shear stress generated for shear force;W t torsional section stiffness; shear forceVBy passing
Calculating; M t is a torque andM t =M z 。
in this embodiment, when load software is used to calculate the load, the tower is divided into a plurality of sections, and the divided sections are calculated by using the load when the tower buckling analysis is performed.
In this embodiment, S12 calculates the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower based on the wall thickness and the radius of each section of the tower, and specifically includes:
1) the calculation formula of the axial ideal buckling stress is as follows:
wherein:σ x,Rct the axial ideal buckling of each section of the tower is achieved;E: the modulus of elasticity of the steel;C x is an axial coefficient;tthe wall thickness of the tower section;ris the radius of the tower section;
before calculating the axial ideal buckling stress, judgment is needed:
when it is satisfied with
In time, no axial buckling calculation is required, in whichf yk Is the yield strength of the material.
In calculating the axial coefficientC x Firstly, the tower is required to be judged to be a short rod, a middle rod and a long rod, and the judgment basis is as follows:
when in useωWhen the tower is not more than 1.7, the tower is judged to be a short rod, then
；
When in use
If the tower is judged to be a middle pole, thenC x =1.0；
When in use
If the tower is a long rod, thenC x =C x，N (ii) a WhereinC x，N Take a total of 0.6 and
the one with the larger median value;
in the above formula:ωis a dimensionless parameter;C xb the support form parameters are determined according to the support condition;C x,N is a standard axial coefficient;f yk is the yield strength of the material.
When the following conditions are simultaneously satisfied:
1. the long rod requirement is met;
2、
；
3、
；
4、，f yk is the yield strength of the material;
then
Adopting another calculation method, the calculation formula is as follows;
wherein:σ x= σ x,m +σ x,p ，σ x,p stress due to gravity;σ x the total compressive stress of each section of the tower;σ x,m stress for the dominant moment.
) The calculation of the shear ideal buckling stress is as follows:
wherein:τ xθ,Rcr the ideal bending stress for shearing each section of the tower;C τ : a shear coefficient;E: the modulus of elasticity of the steel;ωis a dimensionless parameter;t: wall thickness of tower section;r: the radius of the tower section;
when the ideal shearing buckling stress is calculated, judgment is needed when the ideal shearing buckling stress is met
When the shear buckling calculation is not needed.
When the ideal shearing buckling stress is calculated, the short rod, the middle rod and the long rod need to be judged firstly, and the judgment basis is as follows:
when in useω<When 20 hours later, the tower is judged to be a short rod, then
；
When in use
If the tower is judged to be a middle pole, thenC τ =1.0；
When in use
If the tower is a long rod, then
。
In an embodiment, the step S13 of calculating the ultimate buckling stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower may include:
obtaining the length fineness of the tower caused by compressive stress and the length fineness of the tower caused by shear stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower;
calculating an axial buckling reduction coefficient and a shearing buckling reduction coefficient based on the length fineness caused by the compressive stress and the length fineness caused by the shearing stress of the tower;
calculating axial characteristic buckling stress and shearing characteristic buckling stress based on the axial buckling reduction coefficient, the shearing buckling reduction coefficient and the yield strength;
and calculating the axial limit buckling stress and the shear limit buckling stress based on the axial characteristic buckling stress and the shear characteristic buckling stress.
In the embodiment, firstly, the length fineness caused by the compressive stress and the length fineness caused by the shear stress of the tower are obtained according to the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower;
second length and fineness by compressive stressλ x Calculating the axial buckling reduction coefficientχ x Elongation by shear stressλ τ Calculating the shear buckling reduction coefficientχ τ ；
In which the length and fineness caused by compressive stressλ x As shown in the following formula:
when in useλ x ≤λ 0 When it is, thenχ x =1；
When in useλ 0 < λ x < λ p When it is, then
；
When in useλ x ≥λ p When it is, then
；
Here, the
，λ x0=0.20， λ τ 0=0.40， β=0.60，η=1.0；
Elongation due to shear stressλ τ As shown in the following formula:
when in useλ τ ≤λ 0 When it is, thenχ x =1；
When in useλ 0 < λ τ < λ p When it is, then
；
When in useλ τ ≥λ p When it is, then
；
Here, the
，λ x0=0.20， λ τ 0=0.40， β=0.60，η=1.0；
Then calculating the axial characteristic buckling stress and the shearing characteristic buckling stress according to the axial buckling reduction coefficient, the shearing buckling reduction coefficient and the yield strength;
the calculation formula of the axial characteristic buckling stress in the embodiment is as follows:
σ x,Rk = χ x f yk
the calculation formula of the shear characteristic buckling stress in this embodiment is:
then calculating the axial ultimate buckling stress and the shear ultimate buckling stress according to the axial characteristic buckling stress and the shear characteristic buckling stress;
the calculation formula of the axial ultimate buckling stress in the embodiment is as follows:
τ x,Rd = τ x, Rk / γ M
in the formula:σ x,Rd axial ultimate buckling stress;σ x,Rk is the axial characteristic buckling stress; gamma ray M The safety coefficient of the material is set;
wherein: when in useλ x When the value is less than or equal to 0.25, then gamma is M =1.1；
When 0.25<λ x <At 2.00 hours, then
；
The calculation formula of the shear limit buckling stress in this embodiment is:
τ xθ,Rd = τ xθ,Rk / γ M
in the formula:τ xθ,Rd shear ultimate buckling stress;τ xθ,Rk is shear characteristic buckling stress;
wherein: when in useλ x When the value is less than or equal to 0.25, then gamma is M =1.1；
When 0.25<λ x <At 2.00 hours, then
。
In this embodiment, the S14 calculates the buckling margin of each section of the tower based on the total compressive stress, the total shear stress, and the ultimate buckling stress of each section of the tower, and specifically includes:
computing buckling strength margin based on stress interaction
Wherein:k x =1.25+0.75χ x ，k τ =1.25+0.75χ τ ；
finally obtaining the buckling allowance:
in the formula:SME buckling the buckling allowance of each section of the tower is taken;σ x the total compressive stress of each section of the tower;σ x,Rd axial ultimate buckling stress;k x is an axial buckling interaction parameter;τthe total shear stress of each section of the tower;τ xθ,Rd shear ultimate buckling stress;k τ is a shear buckling interaction parameter.
In this embodiment, S2 calculates a reduction coefficient of the tower door section by using the constructed tower door finite element model, including:
for the thin-wall column shell structure, the opening has a great influence on the buckling performance, so that the influence of the load and the opening on the buckling performance of the position of the tower door needs to be comprehensively considered, and the calculation result of the position of the tower door is reduced.
The method is characterized in that a tower door position finite element model is required to be established, an MPC method is adopted in a load loading mode, and the MPC method is a node degree-of-freedom coupling method widely applied to finite element calculation and allows constraints to be imposed between different degrees of freedom of the calculation model, namely, a certain degree of freedom of one node is taken as a standard value, and then a certain relation is established between the certain degrees of freedom of other specified nodes and the standard value.
And the reduction coefficient of the tower door section is =12.5926/14.7027=0.856, the reduction coefficient of the tower door position is substituted into the engineering algorithm of the tower door section, and the calculation result under the condition of no tower door is corrected.
In this embodiment, S4 determines the stability of the wind turbine tower based on the buckling margin of each section of the wind turbine tower and the buckling margin of the section of the tower door, and includes:
when the buckling allowance of each section of the wind turbine generator tower and the buckling allowance of the section of the tower door respectively meet set threshold values, the stability of the wind turbine generator tower meets requirements, and otherwise, the stability of the wind turbine generator tower does not meet requirements.
As shown in fig. 2, based on the same inventive concept, the present embodiment further provides a system for predicting the buckling stability of a wind turbine tower, including:
the buckling allowance module is used for calculating buckling allowances of the sections of the tower based on the stress parameters of the sections of the tower;
the module for calculating the reduction coefficient of the cross section of the tower door is used for calculating the reduction coefficient of the cross section of the tower door by utilizing the constructed finite element model of the tower door;
the buckling allowance module of the tower door section is used for obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
and the stability analysis module is used for determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
In the prediction system provided by this embodiment, the buckling margin module for calculating each section of the tower is called to calculate the buckling margin of each section of the tower based on the stress parameter of each section of the tower; calling a module for calculating the reduction coefficient of the cross section of the tower door, wherein the module is used for calculating the reduction coefficient of the cross section of the tower door by using the constructed tower door finite element model; calling a buckling allowance module of the tower door section, wherein the buckling allowance module is used for obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section; and calling a stability analysis module for determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door, wherein the buckling stability of the tower is quickly and accurately calculated in the process of combining an engineering algorithm and a finite element, so that the calculation accuracy is improved, the calculation time is shortened, the working efficiency is improved, technical services can be provided for each host factory, and the method has a wide application prospect.
In an embodiment, the module for calculating the buckling margin of each section of the tower is specifically configured to:
calculating the total compressive stress and the total shear stress of each section of the tower on the basis of the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
respectively calculating axial ideal buckling stress and shearing ideal buckling stress of each section of the tower on the basis of the wall thickness and the radius of each section of the tower;
calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
and calculating the buckling allowance of each section of the tower based on the total compressive stress, the total shear stress and the ultimate buckling stress of each section of the tower.
In an embodiment, the total compressive stress of each section of the tower is calculated as follows:
σ x= σ x,m +σ x,p
in the formula:σ x the total compressive stress of each section of the tower;σ x,m stress for the main moment;σ x,m= M∕W b ；Mis the main moment;W b bending section stiffness;σ x,p stress due to gravity;
；Ais the cross-sectional area;Pis gravity;
the total shear stress of each section of the tower is calculated according to the following formula:
τ=τ v +τ t
in the formula:τthe total shear stress of each section of the tower;τ v shear stress generated for shear force;
，Vis a shear force;τ t shear stress for torque;
,W t torsional section stiffness;M t is the torque.
In an embodiment, the axial ideal buckling stress of each section of the tower is calculated according to the following formula:
in the formula:σ x,Rct the axial ideal buckling of each section of the tower is achieved;E: the modulus of elasticity of the steel;C x is an axial coefficient;tthe wall thickness of the tower section;ris the radius of the tower section;
wherein the axial coefficientC x The values of (A) include:
when in useωWhen the height is less than or equal to 1.7, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC x =1.0；
When in use
The tower is a long rod, thenC x Take a total of 0.6 and
the one with the larger median value;
when in use
、
And is
When it is, then
；
In the formula:ωis a dimensionless parameter;C xb is a support form parameter;C x,N is a standard axial coefficient;f yk is the yield strength of the material;σ x,p stress due to gravity;σ x the total compressive stress of each section of the tower;σ x,m stress for the dominant moment.
In the embodiment, before calculating the axial ideal buckling stress of each section of the tower, the judgment needs to be performed according to the wall thickness of the tower section, the radius of the tower section and the yield strength of the tower material:
when it is satisfied with
If not, calculating the axial ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
In an embodiment, the shear ideal buckling stress of each section of the tower is calculated according to the following formula:
wherein:τ xθ,Rcr the ideal bending stress for shearing each section of the tower;C τ : a shear coefficient;E: the modulus of elasticity of the steel;ωis a dimensionless parameter;t: wall thickness of tower section;r: the radius of the tower section;
wherein the shear coefficientC τ The values of (A) include:
when in useω<When 20, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC τ =1.0；
When in use
The tower is a long rod, then
。
In the embodiment, before calculating the shear ideal buckling stress of each section of the tower, the judgment needs to be performed according to the wall thickness of the tower section, the radius of the tower section and the yield strength of the tower material:
when it is satisfied with
If so, not calculating the shearing buckling stress, otherwise, calculating the shearing ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
In an embodiment, when the module for calculating the buckling margin of each section of the tower calculates the ultimate buckling stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower, the following steps are specifically performed:
obtaining the length fineness of the tower caused by compressive stress and the length fineness of the tower caused by shear stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower;
calculating an axial buckling reduction coefficient and a shearing buckling reduction coefficient based on the length fineness caused by the compressive stress and the length fineness caused by the shearing stress of the tower;
calculating axial characteristic buckling stress and shearing characteristic buckling stress based on the axial buckling reduction coefficient, the shearing buckling reduction coefficient and the yield strength;
and calculating the axial limit buckling stress and the shear limit buckling stress based on the axial characteristic buckling stress and the shear characteristic buckling stress.
In an embodiment, the calculation of the axial ultimate buckling stress is as follows:
τ x,Rd = τ x, Rk / γ M
in the formula:σ x,Rd axial ultimate buckling stress;σ x,Rk is the axial characteristic buckling stress; gamma ray M The safety coefficient of the material is set;
the shear limit buckling stress is calculated by the following formula:
τ xθ,Rd = τ xθ,Rk / γ M
in the formula:τ xθ,Rd shear ultimate buckling stress;τ xθ,Rk is a shear characteristic buckling stress.
In an embodiment, the buckling margin of each section of the tower is calculated according to the following formula:
in the formula:SME buckling the buckling allowance of each section of the tower is taken;σ x the total compressive stress of each section of the tower;σ x,Rd axial ultimate buckling stress;k x is an axial buckling interaction parameter;τthe total shear stress of each section of the tower;τ xθ,Rd shear ultimate buckling stress;k τ is a shear buckling interaction parameter.
In an embodiment, the stability analysis module is specifically configured to:
when the buckling allowance of each section of the wind turbine generator tower and the buckling allowance of the section of the tower door respectively meet set threshold values, the stability of the wind turbine generator tower meets requirements, and otherwise, the stability of the wind turbine generator tower does not meet requirements.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the scope of the claims of the present invention which are filed as the application.
Claims (13)
1. The method for predicting the buckling stability of the wind turbine tower is characterized by comprising the following steps of:
calculating the buckling allowance of each section of the tower frame based on the stress parameter of each section of the tower frame;
calculating the reduction coefficient of the section of the tower door by using the constructed tower door finite element model;
obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
and determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
2. The method of claim 1, wherein calculating the buckling margin of each section of the tower based on the force parameters of each section of the tower comprises:
calculating the total compressive stress and the total shear stress of each section of the tower on the basis of the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
respectively calculating axial ideal buckling stress and shearing ideal buckling stress of each section of the tower on the basis of the wall thickness and the radius of each section of the tower;
calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
and calculating the buckling allowance of each section of the tower based on the total compressive stress, the total shear stress and the ultimate buckling stress of each section of the tower.
3. The method of claim 2, wherein the total compressive stress of each section of the tower is calculated as:
σ x= σ x,m +σ x,p
in the formula:σ x the total compressive stress of each section of the tower;σ x,m stress for the main moment;σ x,m= M∕W b ；Mis the main moment;W b bending section stiffness;σ x,p stress due to gravity;
；Ais the cross-sectional area;Pis gravity;
the total shear stress of each section of the tower is calculated according to the following formula:
τ=τ v +τ t
in the formula:τthe total shear stress of each section of the tower;τ v shear stress generated for shear force;
，Vis a shear force;τ t shear stress for torque;
，W t torsional section stiffness;M t is the torque.
4. The method of claim 2, wherein the axial ideal buckling stress of each section of the tower is calculated as follows:
in the formula:σ x,Rct the axial ideal buckling of each section of the tower is achieved;E: the modulus of elasticity of the steel;C x is an axial coefficient;tthe wall thickness of the tower section;ris the radius of the tower section;
wherein the axial coefficientC x The values of (A) include:
when in useωWhen the height is less than or equal to 1.7, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC x =1.0；
When in use
The tower is a long rod, thenC x Take a total of 0.6 and
the one with the larger median value;
when in use
、
And is
When it is, then
；
In the formula:ωis a dimensionless parameter;C xb is a support form parameter;C x,N is a standard axial coefficient;f yk is the yield strength of the material;σ x,p stress due to gravity;σ x the total compressive stress of each section of the tower;σ x,m stress for the dominant moment.
5. The method of claim 4, wherein before calculating the axial ideal buckling stress of each section of the tower, the determination is made according to the wall thickness of the tower section, the radius of the tower section and the yield strength of the tower material:
when it is satisfied with
If not, calculating the axial ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
6. The method of claim 2, wherein the shear ideal buckling stress for each section of the tower is calculated as follows:
wherein:τ xθ,Rcr the ideal bending stress for shearing each section of the tower;C τ : a shear coefficient;E: the modulus of elasticity of the steel;ωis a dimensionless parameter;t: wall thickness of tower section;r: the radius of the tower section;
wherein the shear coefficientC τ The values of (A) include:
when in useω<When 20, the tower is a short rod, then
；
When in use
The tower is a middle pole, thenC τ =1.0；
When in use
The tower is a long rod, then
。
7. The method of claim 5, wherein the calculation of the shear ideal buckling stress of each section of the tower is preceded by a determination based on the wall thickness of the tower section, the radius of the tower section, and the yield strength of the tower material:
when it is satisfied with
If so, not calculating the shearing buckling stress, otherwise, calculating the shearing ideal buckling stress of each section of the tower;
whereinf yk Is the yield strength of the material.
8. The method of claim 2, wherein calculating the ultimate buckling stress based on the axial ideal buckling stress and the shear ideal buckling stress for each section of the tower comprises:
obtaining the length fineness of the tower caused by compressive stress and the length fineness of the tower caused by shear stress based on the axial ideal buckling stress and the shear ideal buckling stress of each section of the tower;
calculating an axial buckling reduction coefficient and a shearing buckling reduction coefficient based on the length fineness caused by the compressive stress and the length fineness caused by the shearing stress of the tower;
calculating axial characteristic buckling stress and shearing characteristic buckling stress based on the axial buckling reduction coefficient, the shearing buckling reduction coefficient and the yield strength;
and calculating the axial limit buckling stress and the shear limit buckling stress based on the axial characteristic buckling stress and the shear characteristic buckling stress.
9. The method of claim 8, wherein the axial ultimate buckling stress is calculated as follows:
τ x,Rd = τ x, Rk / γ M
in the formula:σ x,Rd axial ultimate buckling stress;σ x,Rk is the axial characteristic buckling stress; gamma ray M The safety coefficient of the material is set;
the shear limit buckling stress is calculated by the following formula:
τ xθ,Rd = τ xθ,Rk / γ M
in the formula:τ xθ,Rd shear ultimate buckling stress;τ xθ,Rk is a shear characteristic buckling stress.
10. The method of claim 2, wherein the buckling margin for each section of the tower is calculated as follows:
in the formula:SME buckling the buckling allowance of each section of the tower is taken;σ x the total compressive stress of each section of the tower;σ x,Rd axial ultimate buckling stress;k x is an axial buckling interaction parameter;τthe total shear stress of each section of the tower;τ xθ,Rd shear ultimate buckling stress;k τ is a shear buckling interaction parameter.
11. The method of claim 1, wherein determining the stability of the wind turbine tower based on the buckling margins of the sections of the wind turbine tower and the buckling margins of the tower door sections comprises:
when the buckling allowance of each section of the wind turbine generator tower and the buckling allowance of the section of the tower door respectively meet set threshold values, the stability of the wind turbine generator tower meets requirements, and otherwise, the stability of the wind turbine generator tower does not meet requirements.
12. A prediction system for the buckling stability of a wind turbine tower is characterized by comprising:
the buckling allowance module is used for calculating buckling allowances of the sections of the tower based on the stress parameters of the sections of the tower;
the module for calculating the reduction coefficient of the cross section of the tower door is used for calculating the reduction coefficient of the cross section of the tower door by utilizing the constructed finite element model of the tower door;
the buckling allowance module of the tower door section is used for obtaining the buckling allowance of the tower door section based on the buckling allowance of each section and the reduction coefficient of the tower door section;
and the stability analysis module is used for determining the stability of the wind turbine tower based on the buckling allowance of each section of the wind turbine tower and the buckling allowance of the section of the tower door.
13. The system of claim 12, wherein the calculate buckling margin module for each section of the tower is specifically configured to:
calculating the total compressive stress and the total shear stress of each section of the tower on the basis of the moment, gravity, bending section rigidity, section area, shear force and torque of each section of the tower;
respectively calculating the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower by the length of the tower;
calculating ultimate buckling stress based on the axial ideal buckling stress and the shearing ideal buckling stress of each section of the tower;
and calculating the buckling allowance of each section of the tower based on the total compressive stress, the total shear stress and the ultimate buckling stress of each section of the tower.
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