Cable terminal steel pipe pole, secondary transformation transmission structure and wiring method

Abstract

The invention discloses a cable terminal steel pipe pole, a secondary transformation transmission structure and a wiring method, and an upper-phase wire cross arm, a middle-phase wire cross arm and a lower-phase wire cross arm each comprise at least one wire overhead cross arm used for connecting an overhead wire and at least two wire down-leading cross arms used for leading down a cable. And an angle is formed between the lead down cross arm and the lead overhead cross arm in the horizontal projection direction. The three-phase wire is a three-phase double-loop wire, one loop is connected through a wire overhead cross arm, the other loop is disconnected into two paths, the two paths are pulled down through two wire leading-down cross arms of an upper-phase wire cross arm, a middle-phase wire cross arm and a lower-phase wire cross arm respectively, and the wire leading-down cross arms and the wire overhead cross arm form angles in the projection direction. Six upper-phase, middle-phase and lower-phase lead down cross arms can be arranged at different angles, the tension of the pull-down lead at different angles ensures the requirement of the lead on the tension resistance of the steel pipe pole, and the power transmission and tension resistance requirements of the lead can be met by only arranging one cable terminal steel pipe.

Description

Technical Field

[0001] The present invention relates to the technical field of power transmission lines, and in particular to a cable terminal steel pipe pole, a secondary voltage transformation transmission structure and a wiring method. Background Art

[0002] Based on the existing transmission line grid, new substation sites are planned and sited. For each additional 220kV substation, two or more 110kV substations are required, along with several new 110kV transmission lines. During line design, specific plans are developed for special circumstances. For situations where one circuit is routed overhead, while the other circuit is disconnected to form two cable lines, conventional steel tubular poles require at least one tension steel tubular pole and one cable terminal steel tubular pole.

[0003] Therefore, there is an urgent need for a 110kV cable terminal steel pipe pole that can realize complex wiring, reduce the use of pole tower materials, reduce project costs, and save pole tower floor space. Summary of the Invention

[0004] In order to overcome the disadvantages of needing two steel pipe poles for power transmission, which results in a large floor space and high cost, the present invention provides a cable terminal steel pipe pole, which can achieve 110kV power transmission requirements using only one cable terminal steel pipe pole.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A cable terminal steel pipe pole comprises a main pole, a ground wire crossarm, an upper phase conductor crossarm, a middle phase conductor crossarm, and a lower phase conductor crossarm, wherein the ground wire crossarm, the upper phase conductor crossarm, the middle phase conductor crossarm, and the lower phase conductor crossarm are sequentially arranged on the main pole from top to bottom; the upper phase conductor crossarm, the middle phase conductor crossarm, and the lower phase conductor crossarm each comprise at least one overhead conductor crossarm for connecting an overhead conductor and at least two down-leading conductor crossarms for down-leading cables, wherein the down-leading conductor crossarm and the overhead conductor crossarm form an angle in the horizontal projection direction.

[0006] By adopting the above technical solution, the three-phase conductor is a three-phase double-circuit conductor, one of which is connected by an overhead conductor crossarm, and the other is disconnected into two circuits, which are pulled down using two conductor lead-down crossarms, namely the upper phase conductor crossarm, the middle phase conductor crossarm and the lower phase conductor crossarm. There is an angle between the conductor lead-down crossarm and the overhead conductor crossarm in the projection direction. The six conductor lead-down crossarms of the upper, middle and lower phases can be set at different angles. The tensioning of the conductors pulled down at different angles ensures the tension resistance of the conductors to the steel pipe poles, and only one cable terminal steel pipe can be set to meet the power transmission and tension resistance requirements of the conductors.

[0007] Furthermore, the overhead conductor cross-arms of the upper phase conductor cross-arm, the middle phase conductor cross-arm, and the lower phase conductor cross-arm overlap in the horizontal projection direction.

[0008] By adopting the above technical solution, there is a gap between the upper, middle and lower three-phase overhead conductors during transmission. The overhead cross-arms of the three-phase conductors are set to overlap in the horizontal projection, which will not cause insufficient gaps between the three-phase conductors. In addition, the overhead conductors can be better installed and managed, because the overhead cross-arms of the conductors generally need to be operated at high altitudes, and it is inconvenient to operate if they are set in different directions, and more space is saved in the circumferential direction for the allocation of the conductor lead-down cross-arms.

[0009] Furthermore, an angle is formed between the two conductor down crossarms of each phase, the midlines of the angles of the three-phase conductor down crossarms coincide in the horizontal projection direction, and the midlines of the angles of the conductor overhead crossarms and the conductor down crossarms are collinear.

[0010] By adopting the above technical solution, the three-phase conductor crossarms can be arranged as far away from the overhead conductor crossarms as possible, meeting the electrical clearance. In addition, the conductor crossarms are arranged with a symmetrical center line distribution of the overhead conductors, which can just balance the tension resistance requirements.

[0011] Furthermore, the included angle between the two same-phase conductor down-lead cross-arms in the horizontal projection direction is greater than or equal to 45°.

[0012] By adopting the above technical solution, the 45° design can meet the minimum requirement for the electrical clearance of the same-phase down-conductor cross-arm.

[0013] Furthermore, the included angle between the down-lead cross arms of two different phase conductors in the horizontal projection direction is greater than 30°.

[0014] By adopting the above technical solution, the 30° design meets the electrical clearance requirements between the cross arms of conductors of different phases.

[0015] Furthermore, the upper phase conductor crossarm includes an upper phase conductor overhead crossarm, an upper phase conductor long crossarm, and an upper phase conductor short crossarm; the angle between the projection directions of the upper phase conductor long crossarm and the upper phase conductor short crossarm is 45°; the upper phase conductor overhead crossarm is the same height as the upper phase conductor long crossarm, and the upper phase conductor short crossarm is lower height than the upper phase conductor long crossarm.

[0016] Using the above technical solution, when the angle between the upper phase conductor long crossarm and the upper phase conductor short crossarm in the projection direction is 45°, the angle between the two and the upper phase conductor overhead crossarm in the horizontal projection direction is 157.5°. Where 45° is less than 157.5°, the angle between the upper phase conductor long crossarm and the upper phase conductor short crossarm and the upper phase conductor overhead crossarm is greater than the angle between the upper phase conductor long crossarm and the upper phase conductor short crossarm. In this case, the upper phase conductor long crossarm and the upper phase conductor short crossarm are placed at different heights on the main pole, with either one of them being placed at the same height as the upper phase conductor overhead crossarm, thereby better ensuring the electrical clearance requirements.

[0017] Furthermore, the middle phase conductor crossarm includes a middle phase conductor overhead crossarm, a middle phase conductor down long crossarm, and a middle phase conductor down short crossarm. The angle between the projections of the middle phase conductor down long crossarm and the middle phase conductor down short crossarm in the horizontal direction is 105°; the middle phase conductor overhead crossarm and the middle phase conductor down short crossarm are the same height, and the height of the middle phase conductor down long crossarm is lower than the height of the middle phase conductor down short crossarm.

[0018] With the above technical solution, when the angle between the long crossarm and the short crossarm of the middle-phase conductor in the projection direction is 105°, the angle between them and the middle-phase conductor overhead crossarm in the horizontal projection direction is 127.5°. 105° is less than 127.5°. In this case, the angle between the long crossarm and the short crossarm of the middle-phase conductor and the middle-phase conductor overhead crossarm is greater than the angle between the long crossarm and the short crossarm of the middle-phase conductor. In this case, the long crossarm and the short crossarm of the middle-phase conductor are placed at different heights on the main pole, with either one of them being placed at the same height as the upper phase conductor overhead crossarm, thereby better ensuring the electrical clearance requirement.

[0019] Furthermore, the lower phase conductor crossarm includes a lower phase conductor overhead crossarm, a lower phase conductor long crossarm, and a lower phase conductor short crossarm. The angle between the lower phase conductor long crossarm and the lower phase conductor short crossarm is 165°; the lower phase conductor long crossarm and the lower phase conductor short crossarm have the same height, and the lower phase conductor overhead crossarm is higher than the lower phase conductor long crossarm.

[0020] With the above technical solution, when the angle between the long lower-phase conductor crossarm and the short lower-phase conductor crossarm in the projection direction is 165°, the angle between the two and the lower-phase conductor overhead crossarm in the horizontal projection direction is 97.5°. 165° is greater than 97.5°. At this time, the angle between the long lower-phase conductor crossarm and the short lower-phase conductor crossarm and the lower-phase conductor overhead crossarm is smaller than the angle between the long lower-phase conductor crossarm and the short lower-phase conductor crossarm. In this case, the long lower-phase conductor crossarm and the short lower-phase conductor crossarm are set at the same height as the main pole, while the overhead crossarm is set at a different height from the long lower-phase conductor crossarm and the short lower-phase conductor crossarm. This better ensures the electrical clearance requirements, and crossarms with sufficient electrical clearance are set at the same height, reducing the length of the steel pipe pole, saving steel pipe pole materials, and reducing the construction height.

[0021] The present invention also provides a secondary transformer transmission structure, including a first substation, a second substation and a third substation and the cable terminal steel pipe pole as described above, the conductors on both sides of the overhead cross arm are connected to the first substation and the second substation respectively, and the two conductors of the conductor down cross arm are led down and connected to the third substation.

[0022] Using the above technical solution, if line A is disconnected, the power supply direction is from the first substation to the third substation to the second substation; if line B is disconnected, the power supply direction is from the first substation to the second substation to the third substation; if line C is disconnected, the power supply direction is from the second substation to the first substation to the third substation. When one of the lines is out of power, using the design of this application, the three substations can continue to work, and the substation will not be unable to supply power because one of the lines is disconnected.

[0023] The present invention also provides a wiring method for a two-stage voltage transformation transmission structure, which adopts the above-mentioned two-stage voltage transformation transmission structure and includes the following steps: S1. Divide the 110V double-circuit transmission line into an overhead conductor circuit and a disconnected conductor circuit; S2. Use the three-phase conductor overhead crossbeams on the upper, middle, and lower cable terminal steel poles to suspend the overhead conductor loop, and connect the two sides to the first substation and the second substation respectively; S3. Disconnect the conductor disconnection loop from the cable terminal steel pipe pole and divide it into two paths. Use the conductors of the upper, middle and lower three-phase of the cable terminal steel pipe pole to lead the two disconnected conductor disconnection loops down to the third substation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A schematic structural diagram of the cable terminal steel pipe rod provided by the present invention; Figure 2 A side view of the cable terminal steel pipe rod provided by the present invention from a first perspective; Figure 3 A side view of the cable terminal steel pipe rod provided by the present invention from a second perspective; Figure 4 This is a top view of the upper phase conductor cross arm; Figure 5 It is a top view of the cross arm of the middle phase conductor; Figure 6 It is a top view of the lower phase conductor cross arm; Figure 7 A top view of all conductor cross arms; Figure 8 It is a structural diagram of the two-stage transformer transmission structure.

[0025] In the figure: 1. Cable terminal steel pipe pole; 2. First substation; 3. Second substation; 4. Third substation; 5. Overhead conductor loop; 6. Conductor disconnect loop; 7. First independent support; 8. Second independent support; 10. Main pole; 20. Ground wire crossarm; 30. Upper phase conductor crossarm; 31. Upper phase conductor overhead crossarm; 32. Upper phase conductor long crossarm; 33. Upper phase conductor short crossarm; 40. Middle phase conductor crossarm; 41. Middle phase conductor overhead crossarm; 42. Middle phase conductor long crossarm; 43. Middle phase conductor short crossarm; 50. Lower phase conductor crossarm; 51. Lower phase conductor overhead crossarm; 52. Lower phase conductor long crossarm; 53. Lower phase conductor short crossarm. DETAILED DESCRIPTION

[0026] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1: The present invention provides a cable terminal steel pipe rod, such as Figures 1 to 7 As shown, it includes a main pole 10, a ground wire crossarm 20, an upper phase conductor crossarm 30, a middle phase conductor crossarm 40, and a lower phase conductor crossarm 50. The ground wire crossarm 20, the upper phase conductor crossarm 30, the middle phase conductor crossarm 40, and the lower phase conductor crossarm 50 are arranged on the main pole 10 in sequence from top to bottom; the upper phase conductor crossarm 30, the middle phase conductor crossarm 40, and the lower phase conductor crossarm 50 each include at least one overhead conductor crossarm for connecting an overhead conductor and at least two down-leading conductor crossarms for down-leading cables, and the down-leading conductor crossarm and the overhead conductor crossarm have an angle in the horizontal projection direction.

[0028] When implementing it specifically, Figure 1 、 Figure 2 and Figure 3As shown, the main pole 10 is vertically fixed to the ground, and the three-phase conductors are three-phase double-circuit conductors, one of which is connected by an overhead conductor crossarm, and the other circuit is disconnected into two circuits and pulled down using two conductor lower crossarms, namely, the upper phase conductor crossarm 30, the middle phase conductor crossarm 40 and the lower phase conductor crossarm 50. The two conductor lower crossarms are respectively provided with a first independent bracket 7 and a second independent bracket 8, and the first independent bracket 7 and the second independent bracket 8 are both provided with terminal heads. The disconnected two-circuit conductors are pulled down to the terminal heads, and then converted from the terminal heads into cables and pulled down to the required substation.

[0029] Preferably, there is an angle between the conductor down-lead cross-arm and the conductor overhead cross-arm in the projection direction, and six conductor down-lead cross-arms for the upper, middle and lower phases can be set at different angles. The tensioning of the conductors at different angles ensures the tension resistance of the conductors to the steel pipe poles, and only one cable terminal steel pipe can be set to meet the transmission tension resistance requirements of the conductors.

[0030] In one embodiment, if Figure 2 and Figure 3 and Figure 7 As shown, the overhead conductor cross arms 30 of the upper phase conductor, 40 of the middle phase conductor, and 50 of the lower phase conductor overlap in the horizontal projection direction.

[0031] In specific implementation, since there is a gap between the heights of the upper, middle and lower overhead conductors during transmission, the overhead crossarms of the three-phase conductors are set to overlap in the horizontal projection, which will not cause insufficient gaps between the three-phase conductors. In addition, the overhead conductors can be better installed and managed, because the overhead crossarms of the conductors generally need to be operated at high altitudes, and it is inconvenient to operate if they are set in different directions, and more space is saved in the circumferential direction for the allocation of the setting of the conductor lead-down crossarms.

[0032] In one embodiment, an angle is formed between the two conductor down-lead cross-arms of each phase, the midlines of the angles of the three-phase conductor down-lead cross-arms coincide in the horizontal projection direction, and the midlines of the angles of the conductor overhead cross-arms and the conductor down-lead cross-arms are collinear.

[0033] In specific implementation, this setting allows the three-phase conductor crossarms to be as far away from the overhead conductor crossarms as possible, meeting the electrical clearance. In addition, the conductor crossarms are arranged with a symmetrical center line distribution of the overhead conductors, which can just balance the tension resistance requirements.

[0034] In one embodiment, the included angle between the two same-phase conductor cross-arms in the horizontal projection direction is greater than or equal to 45°.

[0035] In specific implementation, the 45° design can meet the minimum electrical clearance requirement of the same-phase down-conductor cross-arm.

[0036] In one embodiment, the included angle between the cross-arms of two conductors of different phases in the horizontal projection direction is greater than 30°.

[0037] In specific implementation, the 30° design meets the electrical clearance requirements between the cross arms of conductors of different phases.

[0038] In one embodiment, if Figure 4 As shown, the upper phase conductor crossarm 30 includes an upper phase conductor overhead crossarm 31, an upper phase conductor down long crossarm 32, and an upper phase conductor down short crossarm 33; the angle between the projection direction of the upper phase conductor down long crossarm 32 and the upper phase conductor down short crossarm 33 is 45°; the upper phase conductor overhead crossarm 31 and the upper phase conductor down long crossarm 32 are the same height, and the upper phase conductor down short crossarm 33 is lower in height than the upper phase conductor down long crossarm 32.

[0039] In a specific implementation, when the angle between the upper phase conductor long crossarm 32 and the upper phase conductor short crossarm 33 in the projection direction is 45°, the angle between the two and the upper phase conductor overhead crossarm 31 in the horizontal projection direction is 157.5°. Where 45° is less than 157.5°, the angle between the upper phase conductor long crossarm 32 and the upper phase conductor short crossarm 33 and the upper phase conductor overhead crossarm 31 is greater than the angle between the upper phase conductor long crossarm 32 and the upper phase conductor short crossarm 33. In this case, the upper phase conductor long crossarm 32 and the upper phase conductor short crossarm 33 are arranged at different heights on the main pole 10, with either one of them being arranged at the same height as the upper phase conductor overhead crossarm 31, thereby better ensuring the electrical clearance requirement.

[0040] In one embodiment, if Figure 5 As shown, the middle phase conductor cross arm 40 includes a middle phase conductor overhead cross arm 41, a middle phase conductor down long cross arm 42, and a middle phase conductor down short cross arm 43. The included angle between the projections of the middle phase conductor down long cross arm 42 and the middle phase conductor down short cross arm 43 in the horizontal direction is 105°; the middle phase conductor overhead cross arm 41 and the middle phase conductor down short cross arm 43 are the same height, and the height of the middle phase conductor down long cross arm 42 is lower than that of the middle phase conductor down short cross arm.

[0041] In a specific implementation, when the angle between the long crossarm 42 and the short crossarm 43 of the middle-phase conductor in the projection direction is 105°, the angle between the two and the middle-phase conductor overhead crossarm 41 in the horizontal projection direction is 127.5°. 105° is less than 127.5°. At this time, the angle between the long crossarm 42 and the short crossarm 43 of the middle-phase conductor and the middle-phase conductor overhead crossarm 41 is greater than the angle between the long crossarm 42 and the short crossarm 43 of the middle-phase conductor. At this time, the long crossarm 42 and the short crossarm 43 of the middle-phase conductor are arranged at different heights on the main pole 10, and either one of them is arranged at the same height as the upper phase conductor overhead crossarm 31, thereby better ensuring the electrical clearance requirement.

[0042] In one embodiment, if Figure 6 As shown, the lower phase conductor crossarm 50 includes a lower phase conductor overhead crossarm 51, a lower phase conductor long crossarm 52, and a lower phase conductor short crossarm 53. The angle between the lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53 is 165°. The lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53 are the same height. The height of the lower phase conductor overhead crossarm 51 is higher than the height of the lower phase conductor long crossarm 52.

[0043] In specific implementation, when the included angle between the lower phase conductor long cross arm 52 and the lower phase conductor short cross arm 53 in the projection direction is 165°, the included angle between the two and the lower phase conductor overhead cross arm 51 in the horizontal projection direction is 97.5°. Among them, 165° is greater than 97.5°. At this time, the angle between the lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53 and the lower phase conductor overhead crossarm 51 is smaller than the angle between the lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53. At this time, the lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53 are set at the same height of the main pole 10, and the lower phase conductor overhead crossarm 51 is set at a different height from the lower phase conductor long crossarm 52 and the lower phase conductor short crossarm 53, which better guarantees the electrical clearance requirement, and sets the crossarms with sufficient electrical clearance at the same height, so that the length of the steel pipe pole is shorter, saves the material of the steel pipe pole, and reduces the construction height.

[0044] In one embodiment, the cross arms are arranged in a vertical direction in the form of "long-short-long" and "short-long-short".

[0045] Specifically, vertically adjacent crossarms have different lengths. This prevents the conductors connected to the upper and lower crossarms from contacting each other during de-icing and rebounding, potentially damaging the circuit. Preferably, the three-phase overhead crossarms in the present invention utilize a "long-short-long" configuration, with two downconductor circuits: one using a "short-long-short" configuration and the other using a "long-short-long" configuration.

[0046] This application designs the overhead crossarms of the conductors, the crossarms leading down to the conductors, the angles between the crossarms, and the angles between adjacent crossarms in the vertical direction, thereby ensuring that a single steel pipe pole can meet the power transmission and tension resistance requirements while meeting the electrical clearances between conductors of different phases and different loops. At the same time, it also saves the material used for the steel pipe pole and saves costs.

[0047] Example 2: The present invention also provides a two-stage voltage transformation transmission structure, such as Figure 8As shown, it includes a first substation 2, a second substation 3 and a third substation 4 and a cable terminal steel pipe pole 1 as in the above embodiment. The conductors on both sides of the overhead crossarm are connected to the first substation 2 and the second substation 3 respectively, and the two conductors of the conductor downcrossarm are led down to the third substation 4.

[0048] In specific implementation, the cable terminal steel pipe pole 1 of the present invention can well meet the power transmission needs between the three substations. The first circuit of the first substation 2 and the second substation 3 are directly connected through overhead wires. The second circuit is first disconnected into two cable lines during the transmission process, and the two ends of the two cable lines are respectively connected to the third substation 4.

[0049] The overhead conductors of the first circuit are connected via an upper phase conductor overhead cross arm 31 , a middle phase conductor overhead cross arm 41 , and a lower phase conductor overhead cross arm 51 .

[0050] The conductors led down from one side of the first substation 2 are led down to the first independent support 7 through the upper phase conductor short cross arm 33, the middle phase conductor long cross arm 42, and the lower phase conductor short cross arm 53. The conductors are connected to the terminal heads of the independent support. After passing through the first independent support 7, the conductors are changed into cables and led down to the third substation 4.

[0051] The conductors led down from one side of the third substation 4 are led down to the second independent support 8 through the upper phase conductor long cross arm 32, the middle phase conductor short cross arm 43, and the lower phase conductor long cross arm 52. The conductors are connected to the terminal head of the second independent support 8. After passing through the second independent support 8, the conductors are changed into cables and led down to the third substation 4.

[0052] When one of the lines is disconnected, the three substations can continue to work using the design of this application, and the substation will not be unable to supply power due to the disconnection of one of the lines. Figure 8 If line A is disconnected, the power supply direction is from the first substation 2 to the third substation 4 to the second substation 3; if line B is disconnected, the power supply direction is from the first substation 2 to the second substation 3 to the third substation 4; if line C is disconnected, the power supply direction is from the second substation to the first substation 2 to the third substation 4. This application can connect three substations simultaneously by using a cable terminal steel pipe pole 1 to complete the secondary voltage transmission process. When one of the lines is disconnected, the power transmission between the three substations will not be affected, and the substations can operate normally, which has good application value.

[0053] The present invention also provides a wiring method for a two-stage voltage transformation transmission structure, which adopts the above-mentioned two-stage voltage transformation transmission structure and includes the following steps: S1. Divide the 110V double-circuit transmission line into an overhead conductor circuit 5 and a disconnected conductor circuit 6; S2. The overhead conductor loop 5 is suspending the upper, middle and lower three-phase conductor overhead cross arms of the cable terminal steel pipe pole 1, and the two sides are connected to the first substation 2 and the second substation 3 respectively; S3. Disconnect the conductor disconnection loop 6 from the cable terminal steel pipe pole 1 and divide it into two paths. The two disconnected conductor disconnection loops 6 are respectively connected to the third substation 4 using the conductors of the upper, middle and lower three phases of the cable terminal steel pipe pole 1 through cross arms.

Claims

1. A cable terminal steel pipe pole, characterized in that: It includes a main pole, a ground wire crossarm, an upper phase conductor crossarm, a middle phase conductor crossarm, and a lower phase conductor crossarm. The ground wire crossarm, the upper phase conductor crossarm, the middle phase conductor crossarm, and the lower phase conductor crossarm are arranged on the main pole in sequence from top to bottom; the upper phase conductor crossarm, the middle phase conductor crossarm, and the lower phase conductor crossarm each include at least one overhead conductor crossarm for connecting an overhead conductor and at least two down-leading conductor crossarms for down-leading cables, and the down-leading conductor crossarm and the overhead conductor crossarm have an angle in the horizontal projection direction.

2. The cable terminal steel pipe rod according to claim 1, characterized in that: The overhead conductor cross-arms of the upper phase conductor cross-arm, the middle phase conductor cross-arm, and the lower phase conductor cross-arm overlap in a horizontal projection direction.

3. The cable terminal steel pipe rod according to claim 2, characterized in that: An angle is formed between the two conductor down cross arms of each phase, the midlines of the angles of the conductor down cross arms of the three phases coincide in the horizontal projection direction, and the midlines of the angles of the conductor overhead cross arms and the conductor down cross arms are collinear.

4. The cable terminal steel pipe rod according to claim 1, characterized in that: The included angle between the cross arms of two same-phase conductors in the horizontal projection direction is greater than or equal to 45°.

5. The cable terminal steel pipe rod according to claim 1, characterized in that: The angle between the cross arms of two different phase conductors in the horizontal projection direction is greater than 30°.

6. The cable terminal steel pipe rod according to claim 1, characterized in that: The upper phase conductor cross arm includes an upper phase conductor overhead cross arm, an upper phase conductor down long cross arm, and an upper phase conductor down short cross arm; the angle between the projection direction of the upper phase conductor down long cross arm and the upper phase conductor down short cross arm is 45°; The upper phase conductor overhead cross arm has the same height as the upper phase conductor lower long cross arm, and the upper phase conductor lower short cross arm has a lower height than the upper phase conductor lower long cross arm.

7. The cable terminal steel pipe rod according to claim 1, characterized in that: The middle phase conductor cross arm includes a middle phase conductor overhead cross arm, a middle phase conductor down-lead long cross arm, and a middle phase conductor down-lead short cross arm, and the included angle between the projections of the middle phase conductor down-lead long cross arm and the middle phase conductor down-lead short cross arm in the horizontal direction is 105°; The middle phase conductor overhead cross arm and the middle phase conductor down short cross arm have the same height, and the middle phase conductor down long cross arm has a lower height than the middle phase conductor down short cross arm.

8. The cable terminal steel pipe rod according to claim 1, characterized in that: The lower phase conductor cross arm includes a lower phase conductor overhead cross arm, a lower phase conductor long cross arm and a lower phase conductor short cross arm, and the angle between the lower phase conductor long cross arm and the lower phase conductor short cross arm is 165°; The lower phase conductor long cross arm and the lower phase conductor short cross arm have the same height, and the lower phase conductor overhead cross arm has a higher height than the lower phase conductor long cross arm.

9. A two-stage voltage transformation transmission structure, characterized in that: It includes a first substation, a second substation and a third substation and a cable terminal steel pipe pole as described in any one of claims 1 to 8, the conductors on both sides of the overhead conductor crossarm are respectively connected to the first substation and the second substation, and the two conductors of the conductor down-lead crossarm are led down and connected to the third substation.

10. A wiring method for a two-stage voltage transformation transmission structure, using the two-stage voltage transformation transmission structure according to claim 9, characterized in that: The following steps are involved: S1. Divide the 110V double-circuit transmission line into an overhead conductor circuit and a disconnected conductor circuit; S2. Use the three-phase overhead conductor cross arms of the upper, middle, and lower cable terminal steel pipe poles to suspend the overhead conductor loops, and connect the two sides to the first substation and the second substation respectively; S3. Disconnect the conductor disconnection loop from the cable terminal steel pipe pole and divide it into two paths. The two disconnected conductor disconnection loops are respectively connected to the third substation using the conductors of the upper, middle and lower three phases of the cable terminal steel pipe pole through cross arms.

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