Angle design method for 500kV single-loop and double-loop strain tower in ice-free and light-ice area

Abstract

The invention discloses an angle design method and application of a 500kV single-loop and double-loop strain tower in an ice-free and light-ice area, the strain tower is designed into four corner towers J1-J4, the corresponding corner range of each corner tower is as follows: J1 is 0-25 degrees, J2 is 25-50 degrees, J3 is 50-80 degrees, and J4 is 80-90 degrees and also serves as a terminal, and the method is applied to a non-medium-heavy ice area. According to the design of the strain tower, the rotating angle range of the J1 is expanded to 25 degrees, the bearing capacity of the main material of the J1 tower body can be fully utilized, and the J1 tower body is not only controlled by the installation working condition. And the rotating angle range of the J4 is reduced from 60-90 degrees to 80-90 degrees, so that the tower weight increase caused by merging of excessive large rotating angles and the terminal can be effectively avoided. By the adoption of the four-angle tower planning mode, the cost of about 30,000 RMB can be saved for each module every year at the present stage on average compared with a five-tower mode, and the four-angle tower planning mode is suitable for being popularized in the existing electric power field.

Description

TECHNICAL FIELD

[0001] The present application relates to a design method of a power transmission tower, in particular to a design of a strain tower. BACKGROUND

[0002] The design of the conventional strain tower generally adopts that the strain tower in each tower module includes ordinary corner towers and terminal towers, and the strain tower division principle in single and double circuit modules is as follows.

[0003] The conventional 500kV single and double circuit in no ice and light ice area is divided into four angle series of 0~20°, 20~40°, 40~60° and 60~90° according to 4 corner towers + 1 terminal tower, and the terminal tower is designed separately; the 500kV in medium ice area is divided into four angle series of 0~20°, 20~40°, 40~60° and 60~90° (terminal) according to 4 corner towers. The 500kV in 20mm heavy ice area is divided into three angle series of 0~5°, 5~30° and 30~60° according to 3 corner towers; the 500kV in 30mm heavy ice area is divided into three angle series of 0~5°, 5~20° and 20~40° according to 3 corner towers. In summary, the planning scheme of the conventional 500kV single and double circuit strain tower in no ice and light ice area refers to the 5 tower planning of the ultra-high voltage direct current, which are J1 (0~20°), J2 (20~40°), J3 (40~60°), J4 (60~90°) and JD (0~90° terminal). The rest of the non-heavy ice area modules adopt the specification mode of J1 (0~20°), J2 (20~40°), J3 (40~60°) and J4 (60~90° terminal). In addition, considering that the application frequency of the strain tower in the project is much lower than that of the straight line and other factors, the wind speed gradient of the strain tower planning is planned once every 4m / s, that is, although the wind speed gradient of the module planning is increased every 2m / s, the strain tower still merges two adjacent wind speed modules into the same type, so that the five strain towers are shared by two modules. The above planning mode of the strain tower has some problems worthy of discussion in the actual engineering use process for many years, and there is still room for further optimization, as follows.

[0004] (1) In the calculation process of a large number of 500kV no ice and light ice area towers, it can be found that the main material of J1 tower is often controlled by the installation condition, and the carrying capacity of the main material cannot be fully utilized in the use process, especially for single circuit towers. Therefore, the division of 0~20 degrees of the 1 type corner is a little small.

[0005] (2) According to the application situation of the tower type of the overhead transmission line project in recent years, the frequency of use of the terminal tower is relatively low, the 500kV pole tower adopts the planning mode of combining the terminal and the large strain (60~90°) into one tower, which greatly increases the tower weight of the J4 tower. The frequency of use of the large angle strain is higher than that of the terminal tower, so this combined mode saves the tower type manufacturing cost to a certain extent, but the strain angle range of the terminal combination is too large, if the strain angle range of the terminal combination can be reduced, the tower weight index can be further optimized.

[0006] (3) Although the 500kV single and double circuit strain towers in the non-icing and light icing areas are planned according to 5 towers, the costs of tower design, drawing, factory lofting and increased project management of engineering construction caused thereby cannot be ignored. And the overall frequency of use of the strain tower is lower than that of the straight tower, so whether the strain tower still needs to be planned according to 5 towers is still worth discussing. SUMMARY

[0007] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a 500kV single and double circuit strain tower angle design method in non-icing and light icing areas.

[0008] In order to achieve the above purpose, the technical scheme adopted by the present application is: A 500kV single and double circuit strain tower angle design method in non-icing and light icing areas, the strain tower is a four-corner tower J1~J4 design, each corner tower corresponds to a corner range: J1 is 0~25°, J2 is 25~50°, J3 is 50~80°, and J4 is 80~90° combined with the terminal.

[0009] The present application also discloses the application of the 500kV single and double circuit strain tower angle design method in non-icing and light icing areas; The method is applied in non-medium and heavy icing areas; further, it can be applied in 500kV single circuit or 500kV double circuit; Further, the method is applied in non-icing areas; further, it can be applied in 500kV single circuit or 500kV double circuit; Further, the method is applied in light icing areas; further, it can be applied in 500kV single circuit or 500kV double circuit.

[0010] The beneficial effects of the present application are: the design of the strain tower of the case expands the corner range of J1 to 25°, which can more fully utilize the carrying capacity of the main material of J1 tower body, so that it is not only controlled by the installation condition. The corner range of J4 is reduced from 60-90° to 80-90°, which can effectively avoid the increase of tower weight caused by too many large corners and terminal mergers. Using the 4-corner tower planning mode of the present application, each module can save about 30,000 yuan in cost compared with the 5-tower mode at the present stage, which is suitable for promotion in the existing power field. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 is a fitting curve diagram of the average tower weight ratio of different corner ranges of the embodiment. DETAILED DESCRIPTION

[0012] The present application will be further described in detail below in combination with the embodiments. A corner optimization method for 500kV single and double circuit strain towers in ice-free and light ice areas, the strain tower is designed as a four-corner tower J1-J4, and the corresponding corner range of each corner tower is: J1 is 0-25°, J2 is 25-50°, J3 is 50-80°, and J4 is 80-90° and terminal. The index comparison and analysis of the existing strain towers are as follows.

[0013] I. Design comparison and analysis (1) Selection of strain tower weight index Since the analysis object is mainly aimed at non-medium and heavy ice area strain towers, three 500kV series modules are selected for this analysis, which are 5D1W1, 5D2W2 and 5G2W8. The above three series modules include two angle steel tower modules and one steel pipe tower module, and include two double circuit modules and one single circuit module, and also include one high wind speed module and two low wind speed modules. In order to eliminate the error caused by the selection of different legs, therefore, the corner towers of different modules in this case are selected for tower weight statistics. Therefore, the tower weight comparison and analysis using this series of modules has a certain representativeness.

[0014] Table 1.1 5D1W1, 5D1W1, 5G2W8 strain tower typical tower weight summary table , The average tower weight ratio is the ratio of the average tower weight of the above three series modules to the average tower weight of J1. Since 500kV ice-free and light ice area adopts 5-tower planning, therefore, for the case of 60-90° and terminal, this time, the 500kV medium ice area series tower is selected for analysis of the average tower weight ratio. Among them, 60-90° and terminal are heavier than single terminal tower due to the influence of wind conditions, according to the statistical results, the average tower weight ratio of 60-90° and terminal type is 1.640 relative to the 0-20° type in the above table.

[0015] Figure 1 The figure shows the fitting curves of the average tower weight ratio for different rotation angle ranges. From this figure, we can see that under the new planning model, the average tower weight ratios of J1 (0~25°), J2 (25~50°), and J3 (50~80°) are very close. Since the difference between the terminal and the large tension rotation angle is very small under the two planning models, the average tower weight ratio under the new planning model is shown in the table below.

[0016] Table 1.2 Summary of the average weight ratio of typical tension towers under the new planning model , Under the new planning model, the large-angle tension towers and the terminal towers remain unchanged. Therefore, the average tower weight ratio of 80-90° terminal towers is still 1.640.

[0017] (2) Project statistical benchmark tower weight To clarify the applicability of the 4-tower scheme under the new planning model, this study collected data from 14 500kV lines totaling approximately 1000km and 2435 towers constructed in recent years. The distribution of tension towers was statistically analyzed, and the results are as follows.

[0018] Table 1.3 Summary of the tower weight of tension towers for 14 500kV lines , As shown in the table above, multiplying the average weight ratio of typical tension towers by the number of towers yields a typical tower weight coefficient (total tower weight ratio). Summing the total tower weight ratio of each corner tower provides a representative calculated total tower weight value under the current 5-tower plan.

[0019] The subsequent analysis was based on the total tower recalculation results for comparison and analysis. The technical and economic comparison between the 4-tower scheme under the new planning model and the original planning model was carried out to obtain specific quantitative analysis results.

[0020] II. Technical and Economic Comparative Analysis Currently, the planning schemes for 500kV single and double-circuit tension towers in ice-free and lightly iced areas all adopt a 5-tower planning format. However, merging the large-angle tension and terminal towers, i.e., adopting a 4-tower planning mode, can save some costs in tower design, manufacturing, and layout. Therefore, for some modules with lower application frequency, the overall cost of adopting the 4-tower merged planning form may be lower. Thus, it is necessary to compare and analyze the two 4-tower planning modes with the original 5-tower mode.

[0021] The baseline scheme for the 5-tower planning mode uses the above-mentioned statistical baseline tower weight, while Scheme A (4-tower planning mode) uses J1 (0~20°), J2 (20~40°), J3 (40~60°), and J4 (60~90° and terminal), and its tower weight index is shown in the table below.

[0022] Table 2.1 Calculation of Indicators for Scheme A , As shown in the table above, the total tower weight index of Scheme A is 945.2, which is 1.82% higher than the baseline scheme of 928.3. The 5-tower configuration is consolidated into a 4-tower configuration. Because the large-angle tension also incorporates the terminal function, the tower weight increases by 1.82% for projects using the overall modular application.

[0023] The new planning model adopts a 4-tower configuration, namely J1 (0~25°), J2 (25~50°), J3 (50~80°), and J4 (80~90° and terminal), as Scheme B. Its tower weight index is shown in the table below.

[0024] Table 2.2 Calculation of Indicators for Scheme B , As shown in the table above, the total tower weight index of Scheme B is 925.5, which is 0.3% lower than the baseline scheme of 928.3. By merging the 5-tower configuration into a 4-tower configuration, and because the large-angle tension also incorporates the terminal function, the tower weight is reduced by 0.3% for projects using overall modular applications.

[0025] As shown in the two tables above, under the original planning model, reducing the design of one tension tower type will increase the tower weight index, specifically by 1.82% compared to Scheme A, while Scheme B reduces the tower weight by 0.3%. This indicates that, compared to the baseline scheme, Scheme B under the new planning model is superior to Scheme A. When appropriate consolidation is made to save on tower manufacturing and processing costs, the new planning model can further optimize the tower weight index.

[0026] Based on the above analysis, it can be concluded that for tension towers in non-medium-heavy icing areas, the corner division under the new planning model is more conducive to reducing tower weight. Only when the module application mileage reaches a certain level does a 5-tower planning division become more meaningful. Therefore, a technical and economic comparative analysis of the 4-tower and 5-tower division models under the new planning model is necessary.

[0027] Therefore, Scheme C is set up, which is simply a change from the 4-tower planning to the 5-tower planning mode based on Scheme B. Thus, the tower weight index of the 5-tower mode under the new turning range can be known.

[0028] Table 2.3 Calculation of Indicator C for Scheme , As shown in the table above, under the new angle division 5-tower planning model, the total tower weight is calculated to be 923.2, a 0.55% reduction compared to the original angle division 5-tower planning model (project baseline tower weight) of 928.3. This further confirms the superiority of the new angle division range. The total tower weight calculated for the 4-tower planning scheme B using the new angle division range is 925.5. Scheme C, compared to Scheme B, includes one more tension tower type, yet only reduces the tower weight by 0.25%. As previously mentioned, the average cost of tower fabrication, processing, layout, drafting, and construction management per tension tower is approximately 250,000 yuan. Therefore, when the application mileage of a module is relatively low, adopting the 5-tower planning model may actually increase the overall cost.

[0029] This study statistically analyzed the application mileage of 33 typical 500kV single-circuit and double-circuit modules across 138 projects in the Southern region from 2019 to 2022. The total line length, converted to single-circuit conversion, was 4012.4 kilometers. According to the analysis, from 2019 to 2022, approximately 320,992 tons of tower materials were used in these 33 typical 500kV single-circuit and double-module projects, of which approximately 120,372 tons were used in tension towers, averaging approximately 3647.6 tons per module.

[0030] Based on the usage trends from 2019 to 2022, the average annual weight of each module tension tower is approximately 911.9 tons. Under the new 4-tower planning model, which uses J1 (0–25°), J2 (25–50°), J3 (50–80°), and J4 (80–90° as a terminal tower), the weight of each module is reduced by 0.3% compared to the traditional 5-tower planning model. According to the above analysis, from a large-scale application perspective, the new 4-tower planning model reduces the annual weight of tension towers by approximately 2.74 tons, saving about 30,000 yuan. Therefore, planning 4-tower models for 500kV single and double-circuit tension towers in ice-free and light-icing areas will be more beneficial for performance control.

[0031] The above content is only used to illustrate the technical solution of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for designing the angle of 500kV single- and double-circuit tension towers in ice-free and light-icing zones, characterized in that: The tension tower is designed as a four-corner tower J1~J4. The corner range corresponding to each corner tower is: J1 is 0~25°, J2 is 25~50°, J3 is 50~80°, and J4 is 80~90° and also serves as the terminal tower.

2. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas as described in claim 1, characterized in that: The method is applied in ice-free areas.

3. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas according to claim 1, characterized in that: The method is applied to a 500kV single circuit in an ice-free zone.

4. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas according to claim 1, characterized in that: The method is applied to a 500kV dual-circuit system in an ice-free zone.

5. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas according to claim 1, characterized in that: The method is applied in light ice zones.

6. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas according to claim 1, characterized in that: The method is applied to a 500kV single circuit in a light icing zone.

7. The application of the angle design method for 500kV single and double circuit tension towers in ice-free and lightly iced areas according to claim 1, characterized in that: The method is applied to a 500kV dual-circuit system in a light icing zone.

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