A cross-phase switching method and phase switching structure for tension towers of single-circuit transmission lines

Abstract

The present invention relates to the technical field of high-voltage transmission line design, and in particular to a cross-phase switching method and a phase switching structure of a single-circuit transmission line tension tower. The present invention discloses a cross-phase switching structure of a single-circuit transmission line tension tower, including a tension tower, hardware, an insulator and a transmission line. The transmission line is a three-phase single-circuit transmission conductor, and the three-phase conductors are A, B, and C respectively. A first tension tower and a second tension tower are arranged along the transmission line path. Three conductor hanging points are arranged on the left side, the right side and the middle cross arm of each tension tower respectively. The A-phase conductor, the B-phase conductor and the C-phase conductor are respectively mounted on the first tension tower and the second tension tower, and the A-phase conductor crosses and crosses the paths of the B-phase conductor and the C-phase conductor respectively. By making full use of conventional tension towers and original power channels, the A, B, and C three-phase conductors are subjected to a one-time phase-by-phase cyclic switching, thereby solving the economic cost, construction, and operation and maintenance safety hazards brought about by the complex phase switching scheme of the overhead power line.

Description

Technical Field

[0001] The invention relates to the technical field of high-voltage transmission line design, and in particular to a cross-phase switching method and a phase switching structure for a tension tower of a single-circuit transmission line. Background Art

[0002] With the rapid development of economic construction, the power industry has also developed rapidly. At the same time, with the rapid expansion of cities, the power load has continued to increase, and the number of 110kV~500kV transmission lines built across the country has also increased sharply. The conditions where 110kV~500kV single-circuit overhead transmission lines need to be phase-changed over long distances are becoming more and more frequent, and phase-changed schemes are emerging in an endless stream. Various different phase-changed schemes inevitably lead to complex wiring, inconvenient operation, high investment, and safety risks in maintenance in specific construction and operation and maintenance projects.

[0003] When this situation occurs in 110kV~500kV single-circuit overhead transmission lines, the adoption of a more reasonable, simpler, more scientific and more economical commutation scheme is of great importance and far-reaching significance to the safety of construction and operation and maintenance of transmission lines, control of project initial investment, and planning and development of transmission lines.

[0004] There are generally two solutions for phase commutation of traditional transmission lines: one is to use specially designed phase commutation towers, and the other is to use cable commutation. The traditional phase commutation solution has the following problems:

[0005] 1. Use a special phase-commutation tower for phase commutation, as shown in the attached Figure 4 shown.

[0006] This wiring scheme requires the design of a special phase-changing tower, which increases the tower weight and requires the addition of jumper insulators and jumper support tubes. The operating space on the tower is limited and the jumper wiring is complicated.

[0007] This solution involves a lot of design calculations and requires specially designed phase-changing towers, which makes the operation of line phase-changing complicated, increases operation and maintenance costs, creates safety risks in operation and maintenance, and increases investment. It causes unnecessary waste in the transmission line project, brings adverse effects on operation and maintenance, and thus has a negative impact on the long-term safe and reliable operation of the line.

[0008] 2. Using cable commutation

[0009] In this scheme, the location of the terminal tower must be reserved on both sides of the underground and the underground passage of the cable must be guaranteed. The cost of the cable engineering for high-voltage and ultra-high-voltage lines is generally 4 to 6 times higher than that of the overhead line engineering of the same length. Once the underground passage of the cable conflicts with other pipelines such as heat, natural gas, and communications, the cost of the cable line construction will double and the safety of the passage cannot be completely guaranteed. This scheme greatly increases the investment in the line, and also buries a safety hazard to the stable operation of the line. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a single-circuit transmission line tension tower cross-commutation method, comprising the following steps:

[0011] S1. Obtain the wire rack construction standards and construct the first tension tower foundation and the second tension tower foundation respectively;

[0012] S2. According to the obtained first tension tower foundation and the second tension tower foundation, the first tension tower and the second tension tower are assembled;

[0013] S3. Install hardware and insulators on the first and second tension towers respectively;

[0014] S4. Obtain the span between the first tension tower and the second tension tower, and calculate the safety tension of the three-phase conductor between the first tension tower and the second tension tower;

[0015] S5. Based on the calculated safety tension, the C-phase conductor on the left side of the first tension tower is installed to the middle cross arm of the second tension tower; the B-phase conductor on the middle cross arm of the first tension tower is installed to the right side of the second tension tower; the A-phase conductor from the first tension tower is led out, passes through the BC two-phase conductors, and is installed to the left side of the second tension tower;

[0016] Or based on the calculated safety tension, the A-phase conductor on the right side of the first tension tower is installed to the middle cross arm of the second tension tower; the B-phase conductor on the middle cross arm of the first tension tower is installed to the left side of the second tension tower; the C-phase conductor from the first tension tower is led out, passes through the AB two-phase conductors, and installed to the right side of the second tension tower;

[0017] S6. Calculate the conductor sag of the three-phase conductors A, B, and C respectively, and measure the conductor spacing at the two crossing points X1 and X2 of the three-phase conductors respectively. If the conductor sag and the conductor spacing meet the conductor installation construction standards, the phase change is completed. Otherwise, repeat steps S5 and S6, adjust the safety tension of the three-phase conductors, and re-install the conductors until the conductor sag and the conductor spacing meet the conductor installation construction standards, and the phase change is completed.

[0018] Further, the safe tension of the wire calculated in step S4 can be specifically expressed as:

[0019]

[0020] in, The maximum tension of the wire. is the wire breaking force, is the wire safety factor.

[0021] Furthermore, the calculation of the conductor sag in step S6 can be specifically expressed as:

[0022]

[0023]

[0024] in, is the safety sag of the conductor, is the cross-sectional area of ​​the conductor, and They are the horizontal distances from the conductor mounting points A and B to any point on the conductor; is the horizontal stress at the lowest point of the conductor, The maximum tension of the wire. is the specific load of the conductor.

[0025] The present invention also provides a single-circuit transmission line tension tower cross-phase switching structure applied to the above-mentioned single-circuit transmission line tension tower cross-phase switching method, including a tension tower, hardware, insulators and a transmission line, wherein the transmission line is a three-phase single-circuit transmission conductor, the three-phase conductors are A, B, and C, and a first tension tower and a second tension tower are arranged along the transmission line path, and three conductor hanging points are respectively arranged on the left side, the right side and the middle cross arm of each tension tower, the A-phase conductor, the B-phase conductor and the C-phase conductor are respectively mounted on the first tension tower and the second tension tower, and the A-phase conductor crosses and crosses the paths of the B-phase conductor and the C-phase conductor, or the C-phase conductor crosses and crosses the paths of the A-phase conductor and the B-phase conductor, respectively.

[0026] Furthermore, the mounting points of the three-phase conductors are:

[0027] The mounting points of the A-phase conductor are the right side of the first tension tower and the left side of the second tension tower;

[0028] The mounting points of the B-phase conductor are the middle cross arm of the first tension tower and the right side of the second tension tower;

[0029] The mounting points of the C-phase conductor are the left side of the first tension tower and the middle cross arm of the second tension tower;

[0030] Or the mounting point of the three-phase conductor is:

[0031] The mounting points of the A-phase conductor are the right side of the first tension tower and the middle cross arm of the second tension tower;

[0032] The mounting points of the B-phase conductor are the middle cross arm of the first tension tower and the left side of the second tension tower;

[0033] The mounting points of the C-phase conductor are the left side of the first tension tower and the right side of the second tension tower.

[0034] Furthermore, the positions of the mounting points of the three-phase conductors of the present invention are all as shown in the drawings of the specification. Figure 2The front view portion is used as the basis, and this figure is used as an example to illustrate the positional relationship of the three-phase wires A, B, and C, and is not used to limit the protection scope of the present invention.

[0035] Furthermore, the transmission line is a 110 kV to 500 kV AC transmission line, and the first tension tower and the second tension tower are both two-base single-circuit tension terminal towers.

[0036] The beneficial effects of the present invention are:

[0037] (1) By making full use of the tension tower and the original power channel, the three-phase conductors A, B, and C are cyclically transposed one by one, which greatly facilitates the design, construction, and operation and maintenance, avoids the need for additional special design, construction, and operation and maintenance, and solves the economic costs and safety hazards of construction and operation and maintenance caused by the complex phase-changing scheme of the power overhead line;

[0038] (2) Through reasonable sag and tension control, the safe distance between conductors and operational stability are ensured, the probability of accidents such as phase-to-phase short circuit and conductor breakage is reduced, the reliability of the phase change process is improved, and the service life of the transmission line is extended. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 , a flow chart of a single-circuit transmission line tension tower cross-commutation method of the present invention.

[0040] Figure 2 , a structural schematic diagram of a cross-commutation structure of a single-circuit transmission line tension tower of the present invention.

[0041] Figure 3 , a schematic diagram of the intersection of the wind shadow of the conductor in an embodiment of the present invention.

[0042] Figure 4 , a schematic diagram of a special phase-changing tower phase-changing scheme used in the background technology of the present invention. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the content of the present invention and make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their description are only used to explain the present invention and are not intended to further limit the present invention.

[0044] Embodiment 1:

[0045] The embodiment of the present invention adopts a single-circuit 110kV line project. The project is located in a certain urban area, with a single-circuit overhead design and a total length of 22.1km. The conductor adopts JL / G1A-300 / 40 steel-core aluminum stranded wire, and the ground wire adopts 24-core OPGW optical cable. The wind speed is 27m / s, the ice coverage is 10mm, the altitude is 2000m, and the installation area is 100% flat.

[0046] like Figure 2 As shown, an embodiment of the present invention provides a single-circuit transmission line tension tower cross-phase switching structure, including tension towers, hardware, insulators and transmission lines, wherein the transmission line is a three-phase single-circuit transmission conductor, and the three-phase conductors are A, B, and C respectively; a first tension tower 1 and a second tension tower 2 are arranged along the transmission line path, and three conductor hanging points are respectively arranged on the left side, the right side and the middle cross arm of each tension tower, and the A-phase conductor, the B-phase conductor and the C-phase conductor are respectively mounted on the first tension tower 1 and the second tension tower 2, and the A-phase conductor crosses and passes through the paths of the B-phase conductor and the C-phase conductor respectively.

[0047] Furthermore, the mounting points of the three-phase conductors are:

[0048] The mounting points of the A-phase conductor are on the right side of the first tension tower 1 and on the left side of the second tension tower 2;

[0049] The mounting points of the B-phase conductor are the middle cross arm of the first tension tower 1 and the right side of the second tension tower 2;

[0050] The mounting points of the C-phase conductor are the left side of the first tension tower 1 and the middle cross arm of the second tension tower 2;

[0051] Or the mounting point of the three-phase conductor is:

[0052] The mounting points of the A-phase conductor are the right side of the first tension tower 1 and the middle cross arm of the second tension tower 2;

[0053] The mounting points of the B-phase conductor are the middle cross arm of the first tension tower 1 and the left side of the second tension tower 2;

[0054] The mounting points of the C-phase conductor are the left side of the first tension tower 1 and the right side of the second tension tower 2 .

[0055] Furthermore, the positions of the mounting points of the three-phase conductors in the embodiments of the present invention are all as shown in the drawings of the specification. Figure 2 The front view portion is used as the basis, and this figure is used as an example to illustrate the positional relationship of the three-phase wires A, B, and C, and is not used to limit the protection scope of the present invention.

[0056] Furthermore, the first tension tower 1 and the second tension tower 2 are erected using two single-circuit tension terminal towers. Based on the owner's requirements for the construction period, the construction unit starts construction first when the phase sequence of the opposite substation has not been determined. After the phase sequence is determined, the line towers have been fully assembled. At this time, based on the phase sequence determined by the final substation, two single-circuit tension terminal towers are required for phase switching. According to the conventional single-circuit tower phase sequence switching scheme, one tension tower needs to be scrapped, the foundation needs to be re-excavated, and a specially designed tension tower needs to be assembled, which makes it very difficult to meet the owner's construction period requirements. In order to save investment and shorten the construction period, a one-time phase switching implementation plan of two single-circuit tension terminal towers is adopted.

[0057] Further, such as Figure 1 As shown, an embodiment of the present invention provides a single-circuit transmission line tension tower cross-commutation method, comprising the following steps:

[0058] S1. Construct the foundation of the first tension tower 1 and the foundation of the second tension tower 2 respectively;

[0059] S2. According to the obtained first tension tower 1 foundation and the second tension tower 2 foundation, the first tension tower 1 and the second tension tower 2 are assembled;

[0060] The foundation of the first tension tower 1 and the second tension tower 2 all use 1D2-SDJ (0~40°) 2-base single-circuit tension terminal towers; the spacing range between the foundation of the first tension tower 1 and the second tension tower 2 is 200~300 meters, and the angle range is 0~10°;

[0061] S3. Install hardware and insulators for the first tension tower 1 and the second tension tower 2 respectively;

[0062] S4. Obtain the actual span value of the first tension tower 1 and the second tension tower 2, and calculate the safety tension of the three-phase conductor between the first tension tower 1 and the second tension tower 2;

[0063] S5. Based on the calculated safety tension, the C-phase conductor on the left side of the first tension tower 1 is installed on the middle cross arm of the second tension tower 2; the B-phase conductor on the middle cross arm of the first tension tower 1 is installed on the right side of the second tension tower 2; after the A-phase conductor is led out from the first tension tower 1, it passes through the BC two-phase conductors and is installed on the left side of the second tension tower 2; S6. Calculate the conductor sag of the three-phase conductors A, B, and C respectively, and measure the conductor spacing at the two crossing points X1 and X2 of the three-phase conductors respectively. If the conductor sag and the conductor spacing meet the conductor installation construction standards, the phase change is completed. Otherwise, repeat steps S5 and S6, adjust the safety tension of the three-phase conductors, and re-install the conductors until the conductor sag and the conductor spacing meet the conductor installation construction standards, and the phase change is completed.

[0064] Furthermore, the calculation of the conductor sag can be specifically expressed as:

[0065] ;

[0066] ;

[0067] in, is the safety sag of the conductor, A is the cross-sectional area of ​​the conductor, and They are the horizontal distances from the conductor mounting points A and B to any point on the conductor; is the horizontal stress at the lowest point of the conductor, The maximum tension of the wire. is the specific load of the conductor.

[0068] Specifically, the load ratio of the conductor It includes two parts, namely, the deadweight load and wind load of the conductor. The embodiment of the present invention adopts a single-circuit 110kV line project. For different conductor selections, the deadweight load and wind load are also different. There are four common conductor models for 110kV lines. The embodiment of the present invention adopts JL / G1A-300 / 40 steel-core aluminum stranded wire. The specific conductor model and parameters are based on the national standard GB / T 1179-2008 "Round Wire Concentric Stranded Overhead Conductor" standard values, as shown in Table 1:

[0069] Table 1: Wire parameters

[0070]

[0071] The conductor deadweight load and wind load are and , and the calculation formulas are:

[0072] ;

[0073] ;

[0074] in is the conductor weight, unit: kg / m; is the wind speed at the average height of the conductor, in m / s; is the wire diameter, in mm; is the conductor wind pressure unevenness coefficient, when hour, The value is 0.85; is the conductor shape coefficient, when hour, Take the value 1.2, when hour, The value is 11.1;

[0075] Therefore, the deadweight load and strong wind load of different conductor selections can be calculated, and the calculation results are shown in Table 2:

[0076] Table 2: Calculation results of conductor deadweight load and strong wind load Unit: N / m

[0077]

[0078] Therefore, the specific load of the JL / G1A-300 / 40 steel core aluminum stranded wire used in the embodiment of the present invention can be calculated as follows:

[0079]

[0080] Further, the safety tension of the calculated wire can be specifically expressed as:

[0081]

[0082] in, The maximum tension of the wire. is the wire breaking force, is the wire safety factor.

[0083] Specifically, according to the engineering technical conditions and the State Grid typical design module, considering the relaxation of the phase line within the span of the interphase crossing, in order to meet the load requirements of the tension difference, the two single-circuit tension terminal towers are all 1A3-DJ (0°~90°), and the angle of each single-circuit tension terminal tower is set to be controlled within 10°. The setting value of the conductor safety factor and the calculated value of the tension difference are shown in Table 3:

[0084] Table 3: Calculation table of conductor tension difference

[0085]

[0086] Further, such as Figure 3 As shown in the figure, in the transposition process, this scheme has crossovers of conductors between different phases, and the crossover points are Figure 3 For the circled positions 1 and 2 marked in the figure, we will now calculate and analyze the safety distance for the intersections and crossings at the above two circled positions.

[0087] The terrain of this scheme is designed as flat land, and the sag calculation ignores the height difference of the hanging point, so the sag of any point on the conductor in the section , which can be expressed as:

[0088]

[0089] in, is the safety sag of the conductor, and They are the horizontal distances from the conductor mounting points A and B to any point on the conductor; is the horizontal stress at the lowest point of the conductor, is the specific load of the conductor.

[0090] Furthermore, the conductor sag coefficient is introduced , for any point within the span, the sag Further optimization yields:

[0091]

[0092]

[0093] in, is the conductor sag coefficient, which is used to calculate the conductor sag, that is, the sag distance of the conductor under the action of its own weight and tension; It is the unit load of the conductor, in N / m.

[0094] This embodiment takes a 110kV line project as an example. The minimum layer spacing of the crossarms of two single-circuit tension terminal towers and the length of the crossarms on the inner corner have an important influence on the phase-to-phase safety distance. The main parameters are shown in Table 4:

[0095] Table 4: Cross arm parameters of 2-base single circuit tension terminal tower

[0096]

[0097] like Figure 1 As shown, the safety factor of the conductor on the B (C) phase side is set to 2.5, the safety factor of the A phase line is set to 4.5, and the three-phase conductors are measured using JL / G1A-300 / 40, JL / G1A-240 / 30, JL / G1A-185 / 30, and JL / G1A-150 / 25 respectively; the spans are taken as 200m, 250m, and 300m respectively, and the sag result values ​​under high temperature conditions are calculated. The specific results are shown in Table 5:

[0098] Table 5: Different safety factor values ​​and sag calculation results of conductors

[0099]

[0100] Furthermore, the conductor windage displacement and conductor windage angle at any point of the transmission line span are calculated, which are expressed as:

[0101] ;

[0102] ;

[0103] in, is the windage displacement value of the conductor, unit is m; is the conductor windage angle, and the conductor windage angle calculation results are shown in Table 6:

[0104] Table 6: Calculation results of conductor wind deflection angle, see table for details

[0105]

[0106] Furthermore, the wind deviation projection is a quadratic parabola function about any point of the span, referred to as the wind shadow function, which can be modeled as:

[0107]

[0108] Furthermore, by drawing the wind shadow diagram based on the wind shadow function, we can obtain the wind shadow intersection points and distances corresponding to the same line type of two crossing wires, as shown in the attached figure. Figure 3 The calculation results are shown in Table 7:

[0109] Table 7: Calculation results of wind shadow intersection distance (unit: meter)

[0110]

[0111] Furthermore, according to the wind deviation angle calculation formula, the elevation value of the wind deviation point at any span sag can be expressed as:

[0112]

[0113] in, is the elevation value of the wind deviation point at any gear pitch sag, For sag.

[0114] Furthermore, according to the elevation value of the wind deviation point at any gear pitch sag The wind deflection lift data of different spans, different types of crossing wires and crossed wires at the wind shadow intersection position can be calculated. The specific calculation results are shown in Table 8:

[0115] Table 8: Calculation results of wind shadow intersection sag wind deflection elevation value (unit: m)

[0116]

[0117] Furthermore, according to the data in Table 8, the vertical distances between the same-layer conductors A and B, and A and C at points 1 and 2 are checked after the three-phase conductors are loosened as a whole, and the clearance safety distance can be expressed as:

[0118] ;

[0119] in The minimum vertical safety distance between the conductors at points A and B and C, in meters; The maximum sag value of the A conductor under strong wind conditions at the intersection of points 1 and 2 within the span, in meters; The maximum value of wind deflection lift at the intersection of A conductors within the span at points 1 and 2 under strong wind conditions, in meters; The maximum sag value of the strong wind condition at the intersection of the B and C conductors within the span at points 1 and 2, in meters; The maximum value of wind deflection lift at the intersection of the B and C conductors within the span at points 1 and 2 under strong wind conditions, in meters; is the interlayer spacing coefficient, the value of the intersection point 1 is 0.65, and the value of the intersection point 2 is 0.5; is the value of the middle phase conductor layer spacing, in m; the calculation results are shown in Table 9:

[0120] Table 9: Calculation results of safety distances between conductors A and C, B at crossing points 1 and 2

[0121]

[0122] Furthermore, it can be seen from the calculated data in Table 9 that when the sag is calculated using the safety factor values ​​of the 1-point and 2-point conductors, the safety distances of the A-phase conductor and the B- and C-phase conductors mentioned above all meet the requirements.

[0123] According to the above calculation principle and process, referring to the State Grid's typical design module 2C2, 3B2 and 5B2 terminal towers, the minimum layer spacing is 5.5m, 7.0m and 7.0m, respectively. The wire relaxation safety factor and phase-to-phase safety distance of each intersection of the wire wind shadow after the rolling phase change of 220kV, 330kV and 500kV transmission lines can be obtained. The calculation results are shown in Table 10:

[0124] Table 10: Calculation results of safety distances between conductors A and C, B at crossing points 1 and 2 of 220kV lines

[0125]

[0126] It can be seen from the data in Table 10 that the roller phase-changing spacing of 220kV transmission lines is above 200 meters, and the safety distance requirement of 4m can be met by adjusting the sag of the phase-to-phase conductors at the intersection.

[0127] Table 11: Calculation results of safety distances between conductors A and C, B at crossing points 1 and 2 of 330kV lines

[0128]

[0129] It can be seen from the data in Table 11 that the roller phase-changing distance of the 330kV transmission line is above 200 meters, and the safety distance requirement of 5m can be met by adjusting the sag of the phase-to-phase conductors at the intersection.

[0130] Table 12: Calculation results of safety distances between conductors A and C, B at crossing points 1 and 2 of 500kV lines

[0131]

[0132] It can be seen from the data in Table 12 that the roller phase-changing spacing of 500kV transmission lines is above 250 meters, and the safety distance requirement of 6m can be met by adjusting the sag of the phase-to-phase conductors at the intersection.

[0133] Embodiment 2:

[0134] On the basis of Example 1, a preferred method for cross-commutation of tension towers of a single-circuit transmission line is proposed. The preferred method is to replace step S5 in Example 1 with step S5-1. Except for step S5-1, other steps are the same as those in Example 1.

[0135] Step S5-1: Based on the calculated safety tension, the A-phase conductor on the right side of the first tension tower (1) is installed to the middle cross arm of the second tension tower (2); the B-phase conductor on the middle cross arm of the first tension tower (1) is installed to the left side of the second tension tower (2); and the C-phase conductor is led out from the first tension tower (1), passed through the AB two-phase conductors, and installed to the right side of the second tension tower (2).

[0136] In summary, the present invention provides a single-circuit transmission line tension tower cross-phase-changing structure and phase-changing method, which utilizes span control and sag adjustment. It is feasible for 110kV~500kV transmission lines to use roller transposition to solve the cross-span of two power lines with the same voltage level. By utilizing two single-circuit tension terminal towers and making full use of the sag characteristics of the conductors, a cycle phase-changing is performed, thereby realizing the overall cross-span of one overhead power line and completing the phase-changing at one time, thereby solving the safety problems of design, construction, and operation and maintenance caused by the need to separately design a phase-changing tower in the transmission line.

[0137] Without departing from the spirit and essence of the patent of the present invention, technicians familiar with the field can make various corresponding changes to the conductor model, span, tower height, etc. according to the patent of the present invention, but these corresponding changes should fall within the scope of protection of the claims attached to the patent of the present invention.

[0138] The present invention is explained from the viewpoints of purpose of use, efficiency, progress and novelty, and the practical progress it has is in line with the functional enhancement and use requirements emphasized by the Patent Law. The above description and drawings of this application are only preferred embodiments of this application, and are not intended to limit this application. Therefore, all structures, devices, features, etc. that are similar or identical to those of this application, that is, all equivalent replacements or modifications made in accordance with the scope of the patent application of this application, should fall within the scope of protection of the patent application of this application.

[0139] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for cross-commutation of a single-circuit transmission line tension tower, characterized in that: The following steps are involved: S1. Obtain the wire rack construction standards and construct the first tension tower (1) foundation and the second tension tower (2) foundation respectively; S2. According to the obtained first tension tower (1) foundation and the second tension tower (2) foundation, assembling the first tension tower (1) and the second tension tower (2); S3. Install hardware and insulators on the first tension tower (1) and the second tension tower (2); S4. Obtaining the span between the first tension tower (1) and the second tension tower (2), and calculating the safety tension of the three-phase conductor between the first tension tower (1) and the second tension tower (2); S5. Based on the calculated safety tension, the C-phase conductor on the left side of the first tension tower (1) is respectively installed to the middle cross arm of the second tension tower (2); the B-phase conductor on the middle cross arm of the first tension tower (1) is installed to the right side of the second tension tower (2); the A-phase conductor is led out from the first tension tower (1), passes through the B-phase and C-phase conductors, and is installed to the left side of the second tension tower (2); Alternatively, based on the calculated safety tension, the A-phase conductor on the right side of the first tension tower (1) is respectively installed to the middle cross arm of the second tension tower (2); the B-phase conductor on the middle cross arm of the first tension tower (1) is installed to the left side of the second tension tower (2); the C-phase conductor is led out from the first tension tower (1), passes through the A-phase and B-phase conductors, and is installed to the right side of the second tension tower (2); S6. Calculate the conductor sag of the three-phase conductors A, B, and C respectively, and measure the conductor spacing at the two crossing points X1 and X2 of the three-phase conductors respectively. If the conductor sag and the conductor spacing meet the conductor installation construction standards, the phase change is completed. Otherwise, repeat steps S5 and S6, adjust the safety tension of the three-phase conductors, and re-install the conductors until the conductor sag and the conductor spacing meet the conductor installation construction standards, and the phase change is completed.

2. A method for cross-commutation of a single-circuit transmission line tension tower according to claim 1, characterized in that: The safe tension of the wire calculated in step S4 can be specifically expressed as: in, The maximum tension of the wire. is the wire breaking force, is the wire safety factor.

3. A method for cross-commutation of a single-circuit transmission line tension tower according to claim 1, characterized in that: The calculation of the conductor sag in step S6 can be specifically expressed as: in, is the safety sag of the conductor, is the cross-sectional area of ​​the conductor, They are the horizontal distances from the conductor mounting points A and B to any point on the conductor; is the horizontal stress at the lowest point of the conductor, The maximum tension of the wire. is the specific load of the conductor.

4. A cross-phase switching structure of a single-circuit transmission line tension tower, applied to a cross-phase switching method of a single-circuit transmission line tension tower as claimed in any one of claims 1 to 3, comprising a tension tower, hardware, insulators and a transmission line, wherein the transmission line is a three-phase single-circuit transmission conductor, and the three-phase conductors are A, B and C respectively; It is characterized in that A first tension tower (1) and a second tension tower (2) are arranged along the transmission line path, and three conductor hanging points are arranged on the left side, the right side and the middle cross arm of each tension tower, respectively. The A-phase conductor, the B-phase conductor and the C-phase conductor are respectively hung on the first tension tower (1) and the second tension tower (2), and the A-phase conductor crosses and passes through the paths of the B-phase conductor and the C-phase conductor, respectively, or the C-phase conductor crosses and passes through the paths of the A-phase conductor and the B-phase conductor, respectively.

5. A single-circuit transmission line tension tower cross-commutation structure according to claim 4, characterized in that: The mounting points of the three-phase conductors are: The mounting points of the A-phase conductor are the right side of the first tension tower (1) and the left side of the second tension tower (2); The mounting points of the B-phase conductor are the middle cross arm of the first tension tower (1) and the right side of the second tension tower (2); The mounting points of the C-phase conductor are the left side of the first tension tower (1) and the middle cross arm of the second tension tower (2); Or the mounting point of the three-phase conductor is: The mounting points of the A-phase conductor are the right side of the first tension tower (1) and the middle cross arm of the second tension tower (2); The mounting points of the B-phase conductor are the middle cross arm of the first tension tower (1) and the left side of the second tension tower (2); The mounting points of the C-phase conductor are the left side of the first tension tower (1) and the right side of the second tension tower (2).

6. A single-circuit transmission line tension tower cross-commutation structure according to claim 4, characterized in that: The transmission line is a 110 kV to 500 kV AC transmission line, and the first tension tower (1) and the second tension tower (2) are both two-base single-circuit tension terminal towers.

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