A design method for tension plate of UHV transmission line based on topology optimization

Abstract

A method for designing a tension joint plate for an ultra-high voltage transmission line based on topological optimization includes the following steps: S1: determining an initial model of topological optimization based on information of the tension joint plate to be optimized; S2: determining design variables, objective functions and constraints for topological optimization, wherein the design variables are the thickness of each subunit in the design area, and the objective function is to maximize the load proportional factor corresponding to the first-order buckling mode of the tension joint plate; the constraint condition is that the volume fraction is less than a limit value; S3: topologically optimizing the initial model of the tension joint plate; S4: obtaining a reasonable optimized design of the tension joint plate in combination with processing cost and difficulty; S5: performing nonlinear buckling analysis on the reasonable optimized design of the tension joint plate to determine whether the buckling load meets the stability requirements and whether the Mises stress meets the static strength requirements. The method provided by the present invention improves the buckling resistance of the tension joint plate by topologically optimizing the design of the tension joint plate and changing the size and position of the weight-reducing holes in the joint plate.

Description

Technical Field

[0001] The invention relates to the technical field of electric hardware design, and in particular to a design method for a tension joint plate of an ultra-high voltage transmission line based on topology optimization. Background Art

[0002] Topology optimization is the most challenging research field in structural optimization design and is an innovative design method. Continuum structure optimization aims to find the best material distribution in the design domain under the condition of satisfying constraints and achieve the design of target performance. Topology optimization designs the presence or absence of each unit in the structure after finite element division. Compared with size optimization and shape optimization, it has more design freedom and can break through the reliance on experience in design, so it is favored by many designers.

[0003] With the rapid growth of the national economy and the widespread application of communication technology, the demand for electricity is increasing day by day, and the power grid industry has entered a period of vigorous development. Due to the imbalance of resources in various regions, overhead transmission lines responsible for the transmission, regulation and distribution of electric energy have become an important part of the rational distribution of electric energy. UHV transmission lines are the core of the power grid system. Due to the high voltage level and large span, components such as tension plates bear a large load. The buckling of tension plates will seriously affect the safe and stable operation of transmission lines.

[0004] In order to solve the buckling problem of tension plates and improve their anti-buckling capacity in transmission lines, the main methods currently used are increasing the thickness of the tension plates and welding longer reinforcing ribs on the plates. Although this method increases the anti-buckling performance of the tension plates to a certain extent, it also greatly increases the weight of the tension plates, which is not conducive to overhead line operations and greatly increases the manufacturing cost. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem that the anti-buckling capacity of the tension joint plate is not strong, and a design method of the tension joint plate of the ultra-high voltage transmission line based on topological optimization is proposed. The tension joint plate is topologically optimized, the size and position of the weight-reducing holes in the joint plate are changed, the anti-buckling capacity of the tension joint plate is improved, and the safe operation of the ultra-high voltage direct current transmission line is guaranteed.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] 1. A design method for a UHV transmission line tension plate based on topology optimization, the design method comprising the following steps:

[0008] S1: According to the initial size, initial thickness, material information and location information of connection holes and lifting holes of the tension joint plate to be optimized, and the weight-reducing holes are removed, the initial model of topology optimization is determined, the connection holes and lifting holes are set as fixed areas, and the rest of the areas are design areas;

[0009] S2: Determine the design variables, objective function and constraints of topology optimization. The design variable is the thickness of each subunit in the design area. The objective function is to maximize the load proportional factor corresponding to the first-order buckling mode of the tension joint plate. The constraint is that the volume fraction is less than the limit value.

[0010] S3: Topology optimization is performed on the initial model of the tension joint plate, and the topology optimization result is obtained;

[0011] S4: Based on the topology optimization results, combined with the processing cost and difficulty, a reasonable optimization design of the tension joint plate is obtained;

[0012] S5: Perform nonlinear buckling analysis on the reasonable optimization design of the tension joint plate to determine whether the buckling load meets the stability requirements and whether the Mises stress meets the static strength requirements. If so, output the reasonable optimization design of the tension joint plate. If not, relax the constraints or change the initial thickness of the tension joint plate, and return to step S3 for topology optimization.

[0013] Furthermore, in step S2, the implementation process is:

[0014] The design area in the initial model is divided into n sub-units. The material thickness t of each sub-unit is between 0 and 1. 0 represents that the unit is completely deleted, and 1 represents that the unit is completely retained. The expression of the design variable is:

[0015] t={t1 … t n} T ∈R n ;

[0016] The load proportional factor corresponding to the first-order buckling mode in the objective function can be obtained through eigenvalue buckling analysis;

[0017] The constraints are:

[0018]

[0019] Wherein, Volfrac is the volume fraction, which is the ratio of the current volume of the tension joint plate to the initial volume of the tension joint plate.

[0020] Furthermore, in step S3, topology optimization includes the following steps:

[0021] S3.1: Perform eigenvalue buckling analysis on the tension plate structure;

[0022] S3.2: Determine whether the load scale factor converges based on the buckling analysis results. If converged, output the topology optimization results. If not, perform sensitivity analysis, change the design variables based on the sensitivity analysis results, and return to step S3.1 to perform eigenvalue buckling analysis.

[0023] Furthermore, sensitivity is the response quantity of the constraint conditions and the objective function, that is, the gradient of the load proportional factor and volume fraction corresponding to the first-order buckling mode of the tension joint plate to the design variables. The modification direction of the design variables is determined by sensitivity analysis. The modification direction includes increasing the thickness of the sub-unit in the design area and reducing the thickness of the sub-unit in the design area, thereby modifying the tension joint plate model.

[0024] Furthermore, the initial load of the tension joint plate includes the gravity load of the joint plate itself, the additional load of the shielding ring and the additional load of the unbalanced tension of the conductor. When the load reaches the load corresponding to the first-order buckling mode, the tension joint plate will buckle and fail. The buckling load is the product of the load proportional factor at this time and the applied initial load.

[0025] Furthermore, the additional load of the shielding ring is equivalent to the surface load applied in the area connected to the shielding ring. The additional load of the unbalanced tension of the conductor is obtained by numerical simulation method. Firstly, a finite element model of the line where the tension joint plate is located is established. The icing load is equivalent to the gravity of the conductor and is obtained by changing the gravitational acceleration. The maximum load on the joint plate during the process of conductor icing and deicing is calculated and attached to the connecting hole of the tension joint plate for optimization analysis.

[0026] Compared with the prior art, the design method of the UHV transmission line tension plate based on topology optimization provided by the present invention has the following beneficial effects:

[0027] The method for designing tension joint plates for ultra-high voltage transmission lines based on topological optimization provided by the present invention establishes an initial model of the buckling joint plate to be optimized, sets a fixed area and a design area, and during topological optimization, only designs the thickness of the joint plate in the design area, while the thickness of the tension joint plate in the fixed area is not designed, so as to avoid affecting the strength at the lifting holes and the connection holes.

[0028] The method for designing ultra-high voltage transmission line tension plates based on topology optimization provided by the present invention determines the design variables, objective functions and constraints of the topology optimization, performs topology optimization on the design area in the initial model of the tension plates, obtains the topology optimization results, and maximizes the load proportional factor corresponding to the first-order buckling mode of the tension plates. Because the buckling load of the tension plates is equal to the product of the load proportional factor and the initial load, the load proportional factor is maximized, that is, the buckling load of the tension plates is maximized, thereby improving the bending resistance of the tension plates.

[0029] The method for designing a tension joint plate for an ultra-high voltage transmission line based on topological optimization provided by the present invention performs topological optimization design on the tension joint plate, changes the size and position of the weight-reducing holes in the joint plate, and improves the anti-buckling capacity of the tension joint plate, which is of great significance for ensuring the safe operation of ultra-high voltage direct current transmission lines. Compared with the traditional method of increasing the thickness, width, and height of the joint plate and welding longer reinforcing ribs based on experience, on the one hand, it has more design freedom and meets more engineering requirements. On the other hand, the volume of the joint plate can be controlled, and then the quality of the joint plate can be controlled, which is helpful for overhead line erection and can save engineering costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A schematic flow chart of a method for designing tension joint plates for ultra-high voltage transmission lines based on topology optimization provided by the present invention. DETAILED DESCRIPTION

[0031] The specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

[0032] Please refer to Figure 1 , Figure 1 A schematic flow chart of a method for designing tension joint plates for ultra-high voltage transmission lines based on topology optimization provided by the present invention.

[0033] The method for designing a tension plate for an ultra-high voltage transmission line based on topology optimization provided by the present invention comprises the following steps:

[0034] S1: According to the initial size, initial thickness, material information, and location information of connection holes and lifting holes of the tension joint plate to be optimized, and the weight-reducing holes are removed, the initial model of topology optimization is determined, and the connection hole and lifting hole areas are set as fixed areas, and the remaining areas are design areas; when performing topology optimization, only the thickness of the joint plate in the design area is designed, and the thickness of the tension joint plate in the fixed area is not designed to avoid affecting the strength of the lifting holes and the connection holes.

[0035] S2: Determine the design variables, objective function and constraints of topology optimization. The design variable is the thickness of each subunit in the design area. The objective function is to maximize the load proportional factor corresponding to the first-order buckling mode of the tension plate. The constraint is that the volume fraction is less than the limit value. The implementation process is:

[0036] The design area in the initial model is divided into n sub-units. The material thickness t of each sub-unit is between 0 and 1. 0 represents that the unit is completely deleted, and 1 represents that the unit is completely retained. The expression of the design variable is:

[0037] t={t1 … t n} T ∈R n ;

[0038] The load proportional factor corresponding to the first-order buckling mode in the objective function can be obtained through eigenvalue buckling analysis;

[0039] The constraints are:

[0040]

[0041] Wherein, Volfrac is the volume fraction, which is the ratio of the current volume of the tension joint plate to the initial volume of the tension joint plate.

[0042] The load proportional factor corresponding to the first-order buckling mode of the maximized tension joint plate is the buckling load of the maximized tension joint plate. Because the buckling load of the tension joint plate is equal to the product of the load proportional factor and the initial load, the load proportional factor is the largest, which means that the buckling load of the tension joint plate is maximized, thereby improving the bending resistance of the tension joint plate.

[0043] The initial load of the tension joint plate includes the gravity load of the joint plate itself, the additional load of the shielding ring and the additional load of the unbalanced tension of the conductor. When the load reaches the load corresponding to the first-order buckling mode, the tension joint plate will buckle and fail. The buckling load is the product of the load proportional factor at this time and the initial load applied.

[0044] The additional load of the shielding ring is equivalent to the surface load applied in the area connected to the shielding ring. The additional load of the unbalanced tension of the conductor is obtained by numerical simulation method. Firstly, the finite element model of the line where the tension joint plate is located is established. The icing load is equivalent to the gravity of the conductor and is obtained by changing the gravitational acceleration. The maximum load on the joint plate during the process of conductor ice covering and deicing is calculated and attached to the connecting hole of the tension joint plate for optimization analysis.

[0045] S3: Perform topological optimization on the initial model of the tension joint plate and obtain the topological optimization result. In some preferred embodiments, the topological optimization includes the following steps: S3.1: Perform eigenvalue buckling analysis on the tension joint plate structure; S3.2: Determine whether the load proportional factor converges based on the buckling analysis results. If converged, output the topological optimization result; if not converged, perform sensitivity analysis, change the design variables based on the sensitivity analysis results, and return to step S3.1 to perform eigenvalue buckling analysis.

[0046] Sensitivity is the response quantity of the constraint conditions and the objective function, that is, the gradient of the load proportional factor and volume fraction corresponding to the first-order buckling mode of the tension joint plate to the design variables. The modification direction of the design variables is determined by sensitivity analysis. The modification direction includes increasing the thickness of the sub-unit in the design area and reducing the thickness of the sub-unit in the design area, thereby modifying the tension joint plate model.

[0047] S4: Based on the topological optimization results, combined with the processing cost and difficulty, a reasonable optimization design of the tension joint plate is obtained. This is mainly because the thickness of the tension joint plate obtained according to the optimization results is uneven, and the shape of the weight-reducing holes in the tension joint plate is irregular, which is not convenient for processing or has a high processing cost.

[0048] S5: Perform nonlinear buckling analysis on the reasonable optimization design of the tension joint plate to determine whether the buckling load meets the stability requirements and whether the Mises stress meets the static strength requirements. If so, output the reasonable optimization design of the tension joint plate. If not, relax the constraints or change the initial thickness of the tension joint plate, and return to step S3 for topology optimization. The static strength check of the reasonable optimization design of the tension joint plate is performed because the stress state of the tension joint plate is not considered during the eigenvalue buckling analysis, and the optimization results are modified. It is necessary to further obtain the accurate buckling load of the tension joint plate through nonlinear buckling analysis.

[0049] The method for designing a tension joint plate for an ultra-high voltage transmission line based on topological optimization provided by the present invention performs topological optimization design on the tension joint plate, changes the size and position of the weight-reducing holes in the joint plate, and improves the anti-buckling capacity of the tension joint plate, which is of great significance for ensuring the safe operation of ultra-high voltage direct current transmission lines. Compared with the traditional method of increasing the thickness, width, and height of the joint plate and welding longer reinforcing ribs based on experience, on the one hand, it has more design freedom and meets more engineering requirements. On the other hand, the volume of the joint plate can be controlled, and then the quality of the joint plate can be controlled, which is helpful for overhead line erection and can save engineering costs.

[0050] The above description is only for the best embodiment of the present invention, but it should not be understood as limiting the claims. The present invention is not limited to the above embodiments, and its specific structure is allowed to be changed. However, all changes made within the protection scope of the independent claims of the present invention are within the protection scope of the present invention.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

Claims

1. A method for designing tension plates for ultra-high voltage transmission lines based on topology optimization, characterized in that: The design method comprises the following steps: S1: According to the initial size, initial thickness, material information and location information of connection holes and lifting holes of the tension joint plate to be optimized, and the weight-reducing holes are removed, the initial model of topology optimization is determined, the connection holes and lifting holes are set as fixed areas, and the rest of the areas are design areas; S2: Determine the design variables, objective function and constraints of topology optimization. The design variable is the thickness of each subunit in the design area. The objective function is to maximize the load proportional factor corresponding to the first-order buckling mode of the tension joint plate. The constraint is that the volume fraction is less than the limit value. S3: topologically optimizing the initial model of the tension joint plate and obtaining a topological optimization result; S4: Based on the topology optimization results, combined with the processing cost and difficulty, a reasonable optimization design of the tension joint plate is obtained; S5: Perform nonlinear buckling analysis on the reasonable optimization design of the tension joint plate to determine whether the buckling load meets the stability requirements and whether the Mises stress meets the static strength requirements. If so, output the reasonable optimization design of the tension joint plate. If not, relax the constraints or change the initial thickness of the tension joint plate, and return to step S3 for topology optimization.

2. The method for designing a tension plate for a UHV transmission line based on topology optimization according to claim 1, characterized in that: In step S2, the implementation process is: The design area in the initial model is divided into n sub-units. The material thickness t of each sub-unit is between 0 and 1. 0 represents that the unit is completely deleted, and 1 represents that the unit is completely retained. The expression of the design variable is: t={t1…t n } T ∈R n ; The load proportional factor corresponding to the first-order buckling mode in the objective function can be obtained through eigenvalue buckling analysis; The constraints are: Wherein, Volfrac is the volume fraction, which is the ratio of the current volume of the tension joint plate to the initial volume of the tension joint plate.

3. The method for designing a tension plate for a UHV transmission line based on topology optimization according to claim 2 is characterized in that: In step S3, the topology optimization includes the following steps: S3.1: Perform eigenvalue buckling analysis on the tension plate structure; S3.2: Determine whether the load scale factor converges based on the buckling analysis results. If converged, output the topology optimization results. If not, perform sensitivity analysis, change the design variables based on the sensitivity analysis results, and return to step S3.1 to perform eigenvalue buckling analysis.

4. The method for designing a tension plate for a UHV transmission line based on topology optimization according to claim 3 is characterized in that: The sensitivity is the response quantity of the constraint condition and the objective function, that is, the gradient of the load proportional factor and volume fraction corresponding to the first-order buckling mode of the tension joint plate to the design variable. The modification direction of the design variable is determined by sensitivity analysis. The modification direction includes increasing the thickness of the sub-unit in the design area and reducing the thickness of the sub-unit in the design area, thereby modifying the tension joint plate model.

5. The method for designing a tension plate for a UHV transmission line based on topology optimization according to claim 1, characterized in that: The initial load of the tension joint plate includes the gravity load of the joint plate itself, the additional load of the shielding ring and the additional load of the unbalanced tension of the conductor. When the load reaches the load corresponding to the first-order buckling mode, the tension joint plate will buckle and fail. The buckling load is the product of the load proportional factor at this time and the initial load applied.

6. A method for designing a tension plate for a UHV transmission line based on topology optimization according to claim 5, characterized in that: The additional load of the shielding ring is equivalent to a surface load applied in the area connected to the shielding ring. The additional load of the unbalanced tension of the conductor is obtained by a numerical simulation method. First, a finite element model of the line where the tension joint plate is located is established. The icing load is equivalent to the gravity of the conductor and is obtained by changing the gravitational acceleration. The maximum load on the joint plate during the process of conductor icing and deicing is calculated and attached to the connecting hole of the tension joint plate for optimization analysis.

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