A design method for scaled-down test model of UHV transmission lines

Abstract

The present invention discloses a method for designing a scaled test model of an ultra-high voltage transmission line. The method determines the scale ratio of the size according to the limitations of the drawings of the real transmission line tower and the test site, retains the main structure of each section of the tower, scales the size of the components accordingly, designs a scaled tower model, determines the load similarity coefficient of the scaled test tower by dimensional analysis, determines the wire diameter according to the parameters of the scaled conductor, and evenly suspends a counterweight on the scaled conductor so that the scaled model and the original model meet the similarity of the wire density, and at the same time makes the load similarity coefficient of the scaled conductor consistent with the scaled tower. Finally, the similarity coefficients of the scaled model and the original model in size, load, frequency, displacement response, etc. are calculated according to the dimensional analysis method. The method of the present invention can restore the relevant features of the appearance and mechanical properties of the real transmission line, so as to explore the damage mechanism of the transmission line icing, dancing, ground settlement, etc. on the conductor, tower, insulator string and other components, and carry out fatigue damage research.

Description

Technical Field

[0001] The invention relates to the field of disaster prevention and reduction of power transmission lines, and in particular to a design method for a scaled-down test model of a tower-line system of an ultra-high voltage transmission line. Background Art

[0002] As the scale of the power grid system continues to increase and the line voltage level increases, the operation of the power grid will become more complicated. Therefore, in the actual operation of the power system, higher requirements are placed on its safe and reliable operation. However, in winter, ice and swaying of transmission lines, tilting of transmission towers, cracking of foundations, etc. will affect the stable operation of the transmission line state, posing a great threat to the normal and safe operation of the power grid system, and even causing significant economic losses and serious social impacts.

[0003] At present, domestic and foreign scholars have conducted a lot of research on the failure mechanism of transmission lines, such as transmission conductors, poles, and insulator strings under icing and dancing, including finite element numerical simulation, real-type tests, and wind tunnel tests. However, there are simplifications and assumptions in finite element simulation calculations, which makes it difficult to restore the actual stress conditions of components under icing and dancing of transmission lines; real-type tests are often costly, dependent on the external natural environment and difficult to control; wind tunnel test-related research focuses on the simulation of the aerodynamic characteristics of iced conductors, while research on the failure mechanism of conductors, poles, and insulator strings caused by icing and dancing is often less. Therefore, it is necessary to propose a method for establishing a scaled test model of a tower-line system based on similarity theory to restore the relevant characteristics of the appearance and mechanical properties of the real transmission line, so as to explore the damage mechanism of transmission line icing, dancing, ground settlement, etc. on conductors, poles, insulator strings, and other components, and carry out fatigue damage research. Summary of the invention

[0004] The purpose of the present invention is to provide a design method for a scaled-down test model of a UHV transmission line tower-line system, to restore the relevant characteristics of the appearance and mechanical properties of the real transmission line, so as to explore the damage mechanism of components such as conductors, towers, and insulator strings caused by icing, dancing, and ground settlement of the transmission line, and to carry out fatigue damage research.

[0005] The above technical problems of the present invention are mainly solved by the following technical solutions:

[0006] A method for designing a scaled-down test model for an ultra-high voltage transmission line, characterized in that it comprises the following steps:

[0007] Step S1. According to the drawings of the real transmission line tower and the limitations of the test site, determine the scale ratio of the size, retain the main structure of each section of the tower, scale the component size accordingly, and design a scaled tower model;

[0008] Step S2, calculating the load similarity coefficient between the scaled tower model and the original model according to the dimensional analysis method and the designed scaled tower model parameters;

[0009] Step S3, using a steel wire rope to simulate a scaled transmission line, the length ratio of the scaled transmission line is consistent with the transmission tower, and the wire diameter of the steel wire rope used is determined according to the consistency between the load similarity coefficient of the scaled transmission line and the scaled tower model;

[0010] Step S4, determining the mass of the counterweight according to the scale of the mass per unit length of the conductor, and evenly suspending the counterweight on the conductor to ensure that the linear density and tension scale of the scaled-down transmission conductor are consistent with those of the original conductor;

[0011] Step S5, based on the design parameters of the scaled tower-line system and the actual parameters of the original model, the dimensional analysis method is used to calculate the similarity coefficient of size, load, frequency, and displacement response between the scaled model and the original model, providing a basis for subsequent research on the failure mechanism of components such as conductors, towers, and insulator strings caused by icing and dancing.

[0012] Preferably, the main frame of the tower should be retained in the design of the scaled tower model, and some non-load-bearing auxiliary materials should be omitted. The material of the scaled model tower should be consistent with the actual transmission tower, and the force on the tower should meet the similarity of the scale in the actual production process.

[0013] Preferably, during the design of the scaled conductor model, counterweights should be evenly suspended on the scaled conductor so that the scaled model and the original model meet the similarity of the conductor wire density, and at the same time, the load similarity coefficient of the scaled conductor is consistent with that of the scaled tower. The mass of the counterweight is determined by calculation using the dimensional analysis method.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] 1. The method of the present invention utilizes similarity theory to scale down the UHV transmission towers and transmission lines to ensure the consistency of the load similarity coefficients of the transmission towers and transmission lines, and can build a scaled test model of the transmission tower-line system that meets the requirements of the test site.

[0016] 2. The method of the present invention is used in the design of a scaled-down test model of a transmission line tower-line system. At the same time, the similarity coefficients between the scaled-down model and the original model in terms of size, load, frequency, displacement response, etc. can be calculated, providing a test platform and theoretical basis for the study of failure mechanisms of components such as conductors, poles, towers, and insulator strings caused by icing and dancing.

[0017] 3. The method of the present invention is applicable to the design of a scaled-down test model of a UHV transmission line tower-line system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a specific flow chart of the method of the present invention.

[0019] Figure 2 It is a scaled model design drawing of the 219# straight tower of Example 1 of the present invention.

[0020] Figure 3 It is a scaled model design drawing of the 220# straight tower according to the embodiment of the present invention. DETAILED DESCRIPTION

[0021] In order to make the technical problems, technical solutions and beneficial effects to be solved by the embodiments of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0022] It should be understood that the orientation or position relationship indicated by terms such as "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the embodiments of the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0023] In the description of the present invention, unless otherwise specified, the term "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] Example:

[0025] This embodiment takes the design of a scaled test model of a DC 1000kV transmission line conductor and a tower as an example, and specifically includes the following steps:

[0026] The selected tension section is a 1000kV three-stage four-tower double-circuit transmission line. The tower types involved are mainly SZ323 straight towers and SJ321 and SJ324 tension towers. The total length of the three-stage conductor is 1532m. The specific parameters of the line are shown in Table 1.

[0027] Table 1 Line parameters

[0028] Rod No. Classification Tower Type Exhalation height / m Gear spacing / m 218 Tension tower SJ324 39 477 219 Straight Tower SZ323 69 581 220 Straight Tower SZ323 63 474 221 Tension tower SJ321 39 /

[0029] Among them, the tension towers have an isolating effect on the force, so the tension towers 218# and 221# on both sides do not need to be scaled down, and the walls can be used directly. Only the two straight towers 219# and 220# in the middle need to be scaled down. According to the drawings, the original total heights of the 219# and 220# straight towers are 113.1m (corresponding to a 69m call height) and 107.1m (corresponding to a 63m call height). Considering the actual site limitations, the design scale is 40:1, and the total heights of the scaled model towers are 2.83m and 2.698m respectively. Omit some auxiliary materials and retain the main frame of the tower. The scaled model design drawing of the 219# straight tower is as follows Figure 2 As shown in the figure, the scaled model design of the 220# straight tower is as follows Figure 3 shown.

[0030] The height and length of each section are scaled according to the actual drawings. After the reduction, the steel structure used in each part is compared as shown in the following table. Considering the actual material restrictions, the actual scaled model components used are different from the model components that should be used after the original reduction. According to the drawings of the prototype tower, the component sizes of the corresponding positions of the scaled model tower are shown in Table 2.

[0031] Table 2 Cantilever beam dimensions and material parameters

[0032]

[0033] The width of the components used is in the range of 3 to 7 mm, and the thickness is in the range of 0.2 to 1 mm. In the manufacturing process, the components are connected by combining bolts and node plates as much as possible. If the component size is too small, welding is used for connection. For L-shaped angle steels that are too small, thin steel plates can be bent to simulate.

[0034] Since the material used to make the scaled model of the transmission tower is consistent with that of the prototype, that is, the elastic modulus and density similarity coefficient are set to 1:1, other similar parameters of the model can be determined by dimensional analysis. The calculation formula and specific values ​​are shown in Table 3.

[0035] Table 3 Similarity coefficients of small transmission tower models

[0036]

[0037] It can be seen from the above table that the load similarity coefficient between the small model of the transmission tower and the original model is 1:1600.

[0038] For the design of transmission line scale model, if the scale of the model and the original model in the axial length of the conductor is C l2 , the radial length scale is C D , elastic modulus scale is C E2 , the scales of other parameters can be derived based on the dimensional analysis method and the above criteria. The specific derivation process is omitted and the results are shown in Table 4.

[0039] Table 4 Scale ratios of physical quantities of the small model and the original model

[0040]

[0041] The original model is a conductor made of steel core aluminum stranded wire, model LGJ-630 / 45. The conductor elastic modulus is 63000N / mm 2 The maximum breaking force is 148.7kN, the outer diameter of a single split conductor is 33.6mm, and the calculated cross-sectional area is 666.55mm 2 , the equivalent diameter of 8 split conductors is about 82.4mm. The mass of a single split conductor per unit length is 2060kg / km.

[0042] The material used for making the small model is steel wire rope, and the diameter is to be determined. The elastic modulus of the steel wire rope is about 110000N / mm 2 , that is, the elastic modulus ratio C E2 1.746. Due to the limitation of the test site, the axial length of the conductor is l2 Set to 1:40. Since the total length of the actual 3-stage wire is 1532m, the length of the small model wire is 38.3m.

[0043] To restore the stress of the transmission tower model during the process of conductor ice coating and wind deflection, it is necessary to ensure that the load similarity parameters of the conductor and the transmission tower are consistent, that is, the tension similarity coefficient C F2 Take 1:1600, which is consistent with the tower load similarity coefficient.

[0044] because

[0045] C F2 =C E2 C l2 C D

[0046] Therefore C D It should be 0.044. Since the equivalent diameter of the actual line is about 82.4mm, the calculated diameter of the wire rope should be 3.6mm. Considering the commonly used wire rope sizes on the market and the fact that the conductor is actually split, it is reasonable to use a 4mm wire rope for simulation. For a wire rope with a diameter of 4mm and a 7×7 structure, its linear density is about 65kg / km. Therefore, in order to ensure the similarity of the linear density of the scaled model conductor and the prototype conductor, counterweights need to be evenly suspended on the wire rope. The mass required for the unit length of counterweight is calculated as shown in the following formula:

[0047] Δq m =C E2 C l2 q 1 -q 2

[0048] Where q 1 and q 2 They are the linear density of the prototype conductor and the linear density of the steel wire rope, that is, the weight per unit length is 654g / m. The weight block can be made of high-density lead blocks.

[0049] After the parameters are determined, the similarity coefficients of the parameters of the scaled conductor model and the original transmission conductor model can be determined based on the dimensional analysis method, as shown in Table 5.

[0050] Table 5 Similarity coefficients of small wire models

[0051]

[0052] From the above analysis, we can see that through the dimensional analysis method, the similarity relationship between the physical quantities of the transmission tower small model and the original model is established, among which the similarity ratio of the tower deflection is 1:40. The line load is the key parameter connecting the tower and the conductor. The load similarity ratio of the transmission tower small model is consistent with that of the conductor small model, both of which are 1:1600.

[0053] The specific embodiments described above are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A design method for a scaled-down test model of UHV transmission lines. It is characterized in that The following steps are included: Step S1. According to the drawings of the real transmission line tower and the limitations of the test site, determine the scale ratio of the size, retain the main structure of each section of the tower, scale the component size accordingly, and design a scaled tower model; Step S2, calculating the load similarity coefficient between the scaled tower model and the original model according to the dimensional analysis method and the designed scaled tower model parameters; Step S3, using a steel wire rope to simulate a scaled transmission line, the length ratio of the scaled transmission line is consistent with the transmission tower, and the wire diameter of the steel wire rope used is determined according to the consistency between the load similarity coefficient of the scaled transmission line and the scaled tower model; Step S4, determining the mass of the counterweight according to the scale of the mass per unit length of the conductor, and evenly suspending the counterweight on the conductor to ensure that the linear density and tension scale of the scaled-down transmission conductor are consistent with those of the original conductor; Step S5, based on the design parameters of the scaled tower-line system and the actual parameters of the original model, the dimensional analysis method is used to calculate the similarity coefficient of size, load, frequency, and displacement response between the scaled model and the original model, providing a basis for subsequent research on the failure mechanism of conductors, towers, and insulator strings caused by icing and dancing.

2. The method for designing a scaled-down test model for an ultra-high voltage transmission line according to claim 1, Features: In the design of the scaled tower model, the main frame of the tower should be retained, and the non-load-bearing auxiliary materials should be omitted. The material of the scaled model tower is consistent with the actual transmission tower. In the actual production process, the force on the tower can meet the similarity of the scale.

3. The method for designing a scaled-down test model for an ultra-high voltage transmission line according to claim 1, Features: During the design of the scaled conductor model, counterweights should be evenly suspended on the scaled conductor to ensure that the scaled model and the original model meet the similarity of the conductor line density, and at the same time make the load similarity coefficient of the scaled conductor consistent with that of the scaled tower. The mass of the counterweight is determined by calculation using the dimensional analysis method.

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