A double-circuit tower overhead line converted into a double-section cable downlead structure

Abstract

This invention discloses a down-lead structure for converting a double-circuit overhead line to a double-section cable, belonging to the field of transmission line technology. It includes a double-circuit cable terminal tower, which has three layers of conductor crossarms (upper, middle, and lower) arranged sequentially from top to bottom. Each conductor crossarm has a conductor suspension point on each side, forming a total of six conductor suspension points for the double circuit. The conductors at the upper conductor crossarm suspension points are led down through a tension insulator string, then through double-crossarm support insulators on the middle and lower conductor crossarms to the double-section cable terminal. The conductors at the middle conductor crossarm suspension points are led down through a tension insulator string and then through double-crossarm support insulators on the lower conductor crossarm to the double-section cable terminal. The conductors at the lower conductor crossarm suspension points are led down directly to the double-section cable terminal after passing through a tension insulator string. This invention ensures the safe distance of the down-leads during the conversion of a double-circuit overhead line to a double-section cable, effectively solving the down-lead problem of double-section cables.

Description

Technical Field

[0001] This invention relates to a structure for converting a double-circuit tower overhead line into a double-section cable downlead structure, belonging to the field of power transmission line technology. Background Technology

[0002] The increasing capacity of urban power grids and the growing difficulty of constructing overhead lines in urban areas present challenges. On one hand, finding suitable routes for overhead lines has become extremely difficult, requiring them to cross numerous buildings, roads, and other urban infrastructure. This not only increases construction costs but may also lead to a series of safety hazards and aesthetic problems. On the other hand, with stricter environmental requirements and the need for urban landscape design, the presence of overhead lines in urban areas is facing greater restrictions. As a crucial method of power transmission, cables have limited current-carrying capacity per cable. Faced with ever-increasing power transmission demands, a single cable often cannot handle the transmission capacity matching that of overhead lines. Against this backdrop, the application scenarios for converting four-split overhead lines to double-split cable lines are gradually increasing.

[0003] In power transmission lines, overhead lines typically require conversion to cable lines via cable terminal towers to facilitate underground power transmission. When the overhead line to be lowered consists of four-split conductors, the fixed clamps at the ends of conventional crossarm-type support insulators are only designed for two conductors. Furthermore, the cable terminal clamps used for connecting the conductors are limited to single-conductor and double-conductor clamps. From a technical and equipment compatibility perspective, converting the four-split conductors into two double-split conductors before lowering them is a more reasonable and feasible approach. This conversion method better adapts to existing insulator and clamp conditions, ensuring the safety and stability of the lowering process and providing strong support for the efficient operation of urban power grids. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems in the prior art of converting overhead lines into double-split cables and the difficulty in drawing down the four-split conductors from the cable terminal tower. The invention aims to achieve a straight and smooth transition of the down conductors between the overhead line and the double-split cable terminal head, ensuring the reliability and safety of drawing down the four-split conductors.

[0005] To solve the above-mentioned technical problems, the present invention is implemented using the following technical solution: A double-circuit tower overhead line conversion to a double-section cable down-lead structure includes: a double-circuit cable terminal tower, wherein the double-circuit cable terminal tower is provided with a ground wire crossarm, an upper conductor crossarm, a middle conductor crossarm, and a lower conductor crossarm in sequence from top to bottom, and a conductor suspension point is provided on each side of each conductor crossarm to form a total of six conductor suspension points for the double circuit; The conductor at the upper conductor crossarm suspension point is led down to the double-crossarm support insulator after passing through the tension insulator string, then through the middle conductor crossarm, and finally through the double-crossarm support insulator set on the lower conductor crossarm to the double-jointed cable terminal. The conductor at the middle conductor crossarm suspension point passes through the tension insulator string and the suspension tension string, and then passes through the double crossarm support insulator set on the lower conductor crossarm to the double-jointed cable terminal head. The conductor at the lower conductor crossarm suspension point is led directly down to the double-section cable terminal head after passing through the tension insulator string.

[0006] The aforementioned double-circuit tower overhead line is converted into a double-cable downlead structure, in which a cable terminal platform is set for each phase conductor along the direction of the overhead line, and two cable terminal heads of the double-cable cable are set on each cable terminal platform perpendicular to the direction of the overhead line.

[0007] The aforementioned double-circuit tower overhead line conversion to a double-section cable down conductor structure also includes a surge arrester, which is installed between the two cable terminals, and the down conductor is converted into a double-section cable through the cable terminals.

[0008] The aforementioned double-circuit tower overhead line is converted into a double-section cable downlead structure, with double crossarm support insulators respectively installed on the cable side of the middle conductor crossarm and the lower conductor crossarm, and the double crossarm support insulators are arranged horizontally side by side; The conductor at the upper conductor crossarm suspension point transitions from four-split to two double-split down conductors after passing through the four-split jumper spacer bar; the two double-split down conductors are led down through the double crossarm support insulators of the middle conductor crossarm and the lower conductor crossarm, respectively, and connected to the cable terminal head.

[0009] The aforementioned double-circuit tower overhead line is converted into a double-split cable down-lead structure, with a jumper string installed at the double-split down-lead at the point where the four-split jumper spacer leads out.

[0010] In the aforementioned double-circuit tower overhead line, the conductor at the suspension point of the middle conductor crossarm is transformed from a four-split jumper spacer into two double-split down conductors. The two double-split down conductors are respectively led down through the double crossarm support insulator of the lower conductor crossarm and connected to the cable terminal head.

[0011] In the aforementioned double-circuit tower overhead line converted to a double-split cable downlead structure, at the suspension point of the middle conductor crossarm, the double-split downlead at the point where the four-split jumper spacer leads out is equipped with a suspension tension string.

[0012] The aforementioned double-circuit tower overhead line is converted into a double-split cable down conductor structure. The conductor at the lower conductor crossarm suspension point is transitioned from four-split to two double-split down conductors after passing through a four-split jumper spacer bar, and then connected to the cable terminal head.

[0013] The aforementioned double-circuit tower overhead line is converted into a double-split cable down conductor structure. Each double-split down conductor is connected to a cable terminal head using a double-conductor copper-aluminum transition clamp. Each double-split down conductor is connected to the surge arrester's lead wire via a double-conductor T-type clamp.

[0014] The aforementioned double-circuit tower overhead line is converted into a double-section cable down-leading structure, and the surge arrester is connected to the surge arrester lead line through a copper-aluminum transition equipment clamp.

[0015] The aforementioned double-circuit tower overhead line is converted into a double-section cable down-leading structure. A down-leading bracket is set at the lower part of the lower conductor crossarm, and double crossarm-type support insulators are set on both sides of the down-leading bracket. The double crossarm-type support insulators of the down-leading bracket are set parallel to the double crossarm-type support insulators of the middle conductor crossarm and the lower conductor crossarm. The conductor at the upper conductor crossarm suspension point is led down to the double-section cable terminal head via the tension insulator string, the double crossarm support insulator of the middle conductor crossarm, the double crossarm support insulator of the lower conductor crossarm, and the double crossarm support insulator of the downlead bracket. The conductor at the middle layer conductor crossarm suspension point is led down to the double-section cable terminal head via the tension insulator string, the double crossarm support insulator of the lower layer crossarm, and the double crossarm support insulator of the lead-down bracket. The conductor at the lower conductor crossarm suspension point is led down to the double-section cable terminal head via a tension insulator string and a double crossarm support insulator of the downlead bracket.

[0016] The beneficial effects achieved by this invention are as follows: The down conductor structure of this invention, through the design of the down conductor points and structure of the upper, middle, and lower conductor crossarms, solves the problem of the difficulty in down conductors of four-split cable terminal towers. It can effectively achieve a straight and smooth transition of the down conductors between the overhead line and the double-split cable terminal head. The double crossarm support insulator ensures the electrical clearance between the down conductors and the tower body. Furthermore, there is no crossing between the down conductors, and each phase conductor is connected to the double-split cable in parallel with the same phase after being down, ensuring the reliability and safety of down conductors of four-split cable. Attached Figure Description

[0017] Figure 1 This is a front view of the upper conductor leading down of a double-circuit tower overhead line converted into a double-section cable leading down structure according to Embodiment 1 of the present invention; Figure 2 This is a front view of the middle conductor leading down of a double-circuit tower overhead line converted into a double-section cable leading down structure according to Embodiment 1 of the present invention; Figure 3 This is a front view of the lower conductor of a double-circuit tower overhead line converted into a double-section cable down-lead structure according to Embodiment 1 of the present invention; Figure 4This is a side view of the upper, middle, and lower layer conductors provided in Embodiment 1 of the present invention; Figure 5 This is a detailed diagram of the connection between the cable terminal platform down conductor, the cable terminal head, and the surge arrester provided in Embodiment 2 of the present invention; Figure 6 This is a top view of the cable terminal platform provided in Embodiment 2 of the present invention.

[0018] Reference numerals in the attached diagram: 1. Tension insulator string; 2. Jumper string; 3. Down conductor; 4. Surge arrester drain wire; 5. Suspension tension string; 6. Crossarm support insulator; 7. Four-split jumper spacer; 8. Double-split jumper spacer; 9. Cable termination; 10. Surge arrester; 11. Two-conductor T-clamp; 12. Two-conductor copper-aluminum transition clamp; 13. Copper-aluminum transition clamp; 14. Cable. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to specific embodiments. Example 1

[0020] like Figure 1-4 As shown, a double-circuit 220kV overhead line with 4×630mm diameter is used. 2 The conductor is a double 2500mm. 2 The cable is used as an example. In this example, the double-circuit tower overhead line with double crossarm supporting insulators is converted into a double-section cable downlead structure. The double-circuit cable terminal tower has a ground wire crossarm and three layers of conductor crossarms (upper, middle, and lower) arranged sequentially from top to bottom. Each conductor crossarm has a conductor hanging point on both sides, forming a total of six conductor hanging points for the double circuit. The conductor at the lead-out point uses a four-split conductor. Cable terminal platforms are set on the left and right sides of the tower respectively.

[0021] The conductor at the upper conductor crossarm suspension point passes through the tension insulator string 1 suspended on the overhead line side, jumps to the cable side via the jumper string 2, and then transitions from the four-split jumper spacer 7 to two double-split down conductors 3. These down conductors then pass through the double crossarm support insulator 6 installed on the cable side via the middle and lower conductor crossarms to the double-jointed cable terminal head 9. From the cable terminal head 9, they become cable 14, which is led down from the terminal platform. The double crossarm support insulators 6 are arranged horizontally side-by-side. The down conductor between the tension insulator string 1 and the jumper string 2 uses the four-split jumper spacer 7, and the down conductor between the jumper string 2 and the cable terminal head 9 uses the double-split jumper spacer 8.

[0022] The conductor at the mid-layer conductor crossarm suspension point jumps from the tension insulator string 1 on the overhead line side to the suspension tension string 5 suspended on the side of the mid-layer crossarm. It then transitions from a four-split configuration to two double-split down conductors 3, which are led down through the double crossarm support insulator 6 on the side of the lower-layer conductor crossarm to the double-jointed cable terminal 9. From the cable terminal 9, it becomes cable 14, which is led down from the terminal platform. The down conductor between the crossarm support insulator 6 and the cable terminal 9 uses a double-split jumper spacer 8. The double crossarm support insulator ensures the electrical clearance between the down conductor and the tower.

[0023] The conductor at the lower conductor crossarm suspension point is led directly down to the double-split cable terminal 9 after passing through the tension insulator string 1 on the overhead line side. From the cable terminal 9, it becomes cable 14, which is led down from the terminal platform. After passing through a four-split jumper spacer 7, it transitions into two double-split down conductors 3. The double-split down conductors 3 use double-split jumper spacers 8. This three-layer down conductor structure solves the problem of the difficulty in leading down the four-split conductor from the cable terminal tower, effectively achieving a smooth and direct transition of the down conductor from the overhead line to the double-split cable terminal.

[0024] Example 2

[0025] The double-circuit cable terminal tower is also equipped with a downlead support. The conductor at the upper conductor crossarm suspension point is jumpered to the cable side via the tension insulator string 1 suspended on the overhead line side using a jumper string 2. It is then led down to the double-section cable terminal head 9 via the double crossarm support 6 set on the cable side through the middle conductor crossarm, the lower conductor crossarm, and the downlead support. The conductor at the middle conductor crossarm suspension point is jumpered to the suspension tension string 5 suspended on the side of the middle conductor crossarm via the tension insulator string 1 suspended on the overhead line side. It is then led down to the double-section cable terminal head 9 via the double crossarm support 6 set on the side of the lower conductor crossarm and the downlead support. The conductor at the lower conductor crossarm suspension point is led down to the double-section cable terminal head 9 via the double crossarm support 6 set on the overhead line side through the tension insulator string 1 suspended on the overhead line side. The double crossarm support 6 set on the overhead line side of the downlead support is arranged horizontally side by side. When the total height of the terminal tower of a dual-circuit cable is relatively high, adding a down conductor support can make the conductor down conductor structure more stable.

[0026] like Figure 5As shown, on the cable terminal platform, the double-split down conductor 3 and the cable terminal head 9 are connected by a double-conductor copper-aluminum transition clamp 12. This clamp enables a reliable connection between two conductors of different materials, while reducing the adverse effects caused by material differences and ensuring stable current transmission between conductors of different materials. The double-split down conductor 3 is connected to the surge arrester lead-in conductor 4 via a double-conductor T-clamp 11. The double-conductor T-clamp 11 has a T-shaped structure, which enables a reliable connection between different conductors, ensuring a smooth transition of current between different lines. It plays a crucial branching and connecting role in the electrical connection, ensuring the integrity of the line and the stability of current transmission. The surge arrester lead-in conductor 4 and the surge arrester 10 are connected by a copper-aluminum transition clamp 13, ensuring a safe and reliable transition between copper and aluminum in the electrical connection, preventing problems such as poor contact, overheating, or corrosion caused by improper connection, and ensuring the normal operation of the power system.

[0027] like Figure 6 As shown, when the phase sequence of the double-circuit overhead line is arranged from top to bottom as A1, B1, C1 and C2, B2, A2 respectively, the cable terminal platforms set on both sides of the terminal tower from the overhead line side to the cable side belong to phases C1, B1, A1 and A2, B2, C2 respectively. The two cable terminal heads 9 of the double-section cable on each platform are set perpendicular to the direction of the overhead line, and a surge arrester 10 is set between the two cable terminal heads 9; the down conductor 3 is converted into a double-section cable 14 through the cable terminal head 9.

[0028] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A structure for converting a double-circuit overhead line to a double-section cable downlead, characterized in that, include: A double-circuit cable terminal tower, wherein the double-circuit cable terminal tower is provided with a ground wire crossarm, an upper conductor crossarm, a middle conductor crossarm, and a lower conductor crossarm in sequence from top to bottom, and a conductor suspension point is provided on each side of each conductor crossarm to form a total of six conductor suspension points for the double circuit; The conductor at the upper conductor crossarm suspension point is led down to the double-crossarm support insulator (6) through the tension insulator string (1), and then through the middle conductor crossarm and the lower conductor crossarm to the double-crossarm cable terminal (9). The conductor at the middle conductor crossarm suspension point is led down through the tension insulator string (1) and then through the double crossarm support insulator (6) set on the lower conductor crossarm to the double cable terminal head (9). The conductor at the lower conductor crossarm suspension point is led directly down to the double-jointed cable terminal head (9) after passing through the tension insulator string (1). Double crossarm support insulators (6) are respectively installed on the cable side of the middle layer conductor crossarm and the lower layer conductor crossarm, and the double crossarm support insulators (6) are arranged horizontally side by side; After passing through the four-split jumper spacer bar (7), the conductor at the upper conductor crossarm suspension point transitions from four-split to two double-split down conductors (3); the two double-split down conductors (3) are led down through the double crossarm support insulators of the middle conductor crossarm and the lower conductor crossarm respectively, and connected to the cable terminal head (9). A jumper string (2) is provided at the double-split down-lead (3) at the lead-out point of the four-split jumper spacer (7); The conductor at the middle conductor crossarm suspension point is transitioned from four-split to two double-split down conductors (3) after passing through the four-split jumper spacer (7); the two double-split down conductors (3) are led down through the double crossarm support insulator (6) of the lower conductor crossarm and connected to the cable terminal head (9). At the crossarm suspension point of the middle conductor, a suspension tension string (5) is provided on the double-split down conductor (3) at the point where the four-split jumper spacer (7) leads out. The conductor at the lower conductor crossarm suspension point is connected to the cable terminal head (9) after passing through the four-split jumper spacer bar (7).

2. The structure for converting a double-circuit tower overhead line to a double-section cable downlead as described in claim 1, characterized in that, A cable terminal platform is set for each phase conductor along the direction of the overhead line, and two cable terminal heads (9) of double-stranded cable are set on each cable terminal platform perpendicular to the direction of the overhead line.

3. The structure for converting a double-circuit tower overhead line to a double-section cable downlead as described in claim 1, characterized in that, It also includes a surge arrester (10), which is located between two cable terminals, and the down conductor (3) is converted into a double-pair cable (14) through the cable terminal (9).

4. The structure for converting a double-circuit tower overhead line to a double-section cable downlead as described in claim 2, characterized in that, Each double-split down conductor (3) is connected to one of the cable terminals (9) by a double conductor copper-aluminum transition clamp (12), and each double-split down conductor (3) is connected to the surge arrester lead wire (4) via a double conductor T-clamp (11).

5. The structure for converting a double-circuit tower overhead line into a double-section cable downleading structure according to claim 3, characterized in that, The surge arrester (10) is connected to the surge arrester lead wire (4) through a copper-aluminum transition equipment clamp (13).

6. The structure for converting a double-circuit tower overhead line to a double-section cable downlead as described in claim 1, characterized in that, A down-leading bracket is provided at the lower part of the lower conductor crossarm, and double crossarm type support insulators (6) are provided on both sides of the down-leading bracket. The double crossarm type support insulators (6) of the down-leading bracket are arranged in parallel with the double crossarm type support insulators (6) of the middle conductor crossarm and the lower conductor crossarm. The conductor at the upper conductor crossarm suspension point is led down to the double-section cable terminal head (9) via the tension insulator string (1), the double crossarm support insulator (6) of the middle conductor crossarm, the double crossarm support insulator (6) of the lower conductor crossarm, and the double crossarm support insulator (6) of the downlead bracket. The conductor at the middle layer conductor crossarm suspension point is led down to the double-section cable terminal head (9) via the tension insulator string (1), the double crossarm support insulator (6) of the lower layer crossarm, and the double crossarm support insulator (6) of the lead-down bracket. The conductor at the lower conductor crossarm suspension point is led down to the double-section cable terminal head (9) via the tension insulator string (1) and the double crossarm support insulator (6) of the lead-down bracket.

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