Same-tower double-loop drilling and crossing tower

Abstract

The invention belongs to the technical field of ultrahigh-voltage overhead transmission lines, and particularly discloses a same-tower double-loop drilling tower which comprises a tower body and a tower head, and the tower head is sequentially connected with a first cross arm, a second cross arm and a ground wire cross arm from bottom to top; the two end points of the first cross arm are respectively provided with a first insulator string, the two end points of the second cross arm are respectively provided with a second insulator string, and the two end points and the middle point of the lower side of the ground wire cross arm on the drilling side are respectively provided with a first ground wire hanging point. Second ground wire hanging points are arranged at the two end points of the upper side of the ground wire cross arm on the non-drilling side respectively. The problem that an existing 330kV double-loop line cannot directly drill a high-voltage-class line due to the fact that the tower height is high can be solved.

Description

Technical Field

[0001] This invention relates to the field of ultra-high voltage overhead transmission line technology, specifically to a double-circuit tunnel tower on the same tower. Background Technology

[0002] With the rapid development of high-voltage transmission lines, high-voltage line paths are relatively scarce. For newly built 330kV lines, which account for the majority in both number and length, it will be more frequent to drill through higher voltage power lines. The primary condition for drilling through lines is to maintain sufficient clearance and distance to the ground during crossings to prevent the high-voltage lines drilling through the tower from affecting the electric field of the line to be crossed.

[0003] For 330kV drilling towers that drill through higher voltage towers, the minimum vertical distance between the 330kV line and the power line being drilled through must not be less than 5m. Currently, the typical design of 330kV transmission towers by the State Grid is a double-circuit straight-line tower and a double-circuit tension tower with the same tower. The minimum tower height is 15cm, and the tower head height is 11.5-14.7m. Such double-circuit towers cannot meet the necessary conditions for drilling through higher voltage levels of transmission lines. Therefore, when drilling through, direct drilling should be avoided. The current traditional methods are mainly: 1) Raising the power line to be drilled through to meet the drilling requirements. However, this method not only increases the cost of modification, but also causes power loss due to power outages and poses safety risks to the operation of the power grid; 2) Rerouting the 330kV line or rerouting it to a higher point of the planned line to be drilled through. Although this does not require modification of the power line to be drilled through, the detour will increase the line path and increase operating costs; 3) Converting the 330kV double circuit into two single circuits for drilling. Although this method does not require raising the power line to be drilled through, it increases the amount of tower materials, foundation steel bars and concrete during construction, increasing the amount of construction work and costs. Summary of the Invention

[0004] This invention provides a method for drilling through a double-circuit tower on the same tower, which aims to solve the problem that existing 330kV double-circuit lines cannot directly drill through higher voltage level lines due to the high tower height.

[0005] This invention is achieved through the following technical solution: a double-circuit drilling tower, comprising a tower body and a tower head, wherein a first crossarm, a second crossarm, and a ground wire crossarm are connected sequentially from bottom to top on the tower head; a first insulator string is provided at both ends of the first crossarm, and a second insulator string is provided at both ends of the second crossarm; a first ground wire hanging point is provided at both ends and the middle point of the lower side of the ground wire crossarm on the drilling side, and a second ground wire hanging point is provided at both ends of the upper side of the ground wire crossarm on the non-drilling side.

[0006] Compared with the prior art, the present invention has the following advantages and beneficial effects: The first ground wire suspension points at the two ends and the middle point on the lower side of the ground wire crossarm on the drilling side significantly reduce the height of the ground wire on the drilling side compared to the second ground wire suspension point on the upper side of the non-drilling side. This structure directly reduces the vertical distance redundancy between the ground wire on the drilling side and the line being drilled above (such as 500kV or 750kV lines), ensuring that when drilling through low-voltage lines such as 330kV, the risk of electric field interference or discharge due to insufficient safety distance caused by excessively high ground wires is avoided. This effectively solves the problem that existing 330kV double-circuit lines cannot directly drill through higher-voltage lines due to their high tower height.

[0007] Traditional drilling-through solutions (such as raising the line to be drilled through, rerouting, or converting a double-circuit line to a single-circuit line) incur power outage losses (raising the line causes power interruption), route extension costs (rerouting increases line length), and increased tower material costs (converting a double-circuit line to a single-circuit line requires additional foundation steel reinforcement and concrete). This solution, through low-hanging ground wires and layered crossarm stringing, directly achieves in-situ drilling-through of 330kV double-circuit lines on the same tower, without altering existing lines or adjusting routes, saving on renovation costs and avoiding economic losses from power outages.

[0008] In this scheme, the second ground wire hanging point (at a normal height) on the upper side of the ground wire crossarm on the non-drilling side can ensure the lightning protection range in the non-drilling direction (the ground wire height is sufficient to cover the conductor), avoiding the overall lightning protection performance from being reduced due to the lowering of the ground wire on the drilling side; hanging ground wires at both ends and the middle of the drilling side can form a denser lightning protection network, reducing the probability of the conductor on the drilling side being struck by lightning and improving the reliability of line operation.

[0009] Furthermore, the first insulator string is V-shaped.

[0010] Beneficial effects: In this scheme, the first insulator string is changed to a V-shape, which utilizes triangular stability to reduce the wind deflection of the jumper wire, thereby reducing the width of the tunnel across the tower.

[0011] Furthermore, one side of the first insulator string consists of two parallel insulator strings, and the other side consists of a single insulator string. The lower end of the single insulator string intersects at the midpoint of the line connecting the lower ends of the two parallel insulator strings.

[0012] Beneficial effects: The V-shaped insulator string in this scheme can ensure that none of the insulators are under pressure when subjected to strong wind loads in the direction perpendicular to the line. Due to the inherent stability characteristics of the triangular structure of the V-shape, it can effectively suppress the wind deflection of the insulator string.

[0013] In this design, the conductor on the drilling-through side must simultaneously bear vertical loads (conductor self-weight and icing weight) and horizontal loads (strong winds and conductor tension). Furthermore, due to the high requirement for fixed conductor spatial positioning in drilling-through scenarios, conventional symmetrical V-shaped strings (single or double strings on both sides) are prone to load concentration on one side. In this structure, the parallel double-string side can bear greater vertical loads and horizontal tensions (such as increased conductor weight under icing conditions and horizontal thrust caused by strong winds) through the coordinated force distribution of the double insulator strings. The single-string side, through its triangular arrangement with the double strings, forms a stable force balance system. The connection between the lower end of the single string and the midpoint of the double strings ensures that the conductor tension is evenly distributed to the crossarm, preventing insulator string tilting or crossarm deformation due to uneven force distribution, thus adapting to the complex stress environment on the drilling-through side.

[0014] Compared to the full double-string V-shaped structure (double strings on both sides), the asymmetrical design, while ensuring load-bearing capacity, reduces the number of insulator strings by one, thus lowering the overall tensile load on the crossarm. Under the same load, the tensile force on the crossarm can be reduced by the asymmetrical V-shaped string, eliminating the need to increase the thickness of the crossarm steel or extend its length to withstand excessive tensile force. This indirectly achieves a lightweight tower structure, reducing tower material consumption and construction costs.

[0015] Furthermore, one side of the first insulator string is positioned facing the center of the tower head.

[0016] Beneficial effects: During the operation of a double-circuit line, the conductor tension will exert a lateral force on the crossarm. If the force is unbalanced, it can easily lead to the crossarm tilting and the tower tilting. The layout of the first insulator string with "double strings facing outward and single strings facing inward" (the double strings bear a larger load, and the single strings balance the tension) allows the conductor tension to be evenly transmitted to the crossarm through the V-shaped structure.

[0017] If the insulator string is oriented with one side facing outwards, it is susceptible to impact from strong lateral airflow during high winds, generating additional swaying torque (leading to fatigue damage at the insulator string root). When the single string is oriented with one side facing the tower head center, the tower body can form a wind barrier for the insulator string, reducing the direct impact of strong winds and decreasing the sway amplitude, thereby reducing mechanical fatigue wear. Simultaneously, the balanced stress state also prevents the insulation performance of the single-string insulator from deteriorating due to overload, improving overall operational reliability.

[0018] Furthermore, a third insulator string with the same structure as the first insulator string is provided at a position adjacent to the first insulator string.

[0019] Beneficial Effects: The core function of a dual-circuit tunnel tower is to simultaneously erect two 330kV lines on a single tower (one tunnel main line and one parallel line). This requires physical and electrical isolation between the two lines using independent insulator strings. The first and third insulator strings are adjacent and have the same structure, serving as suspension carriers for the two lines respectively. Each set of insulator strings corresponds to the conductor suspension requirements of one line. Through preset spacing, horizontal isolation between the two lines is achieved, preventing phase-to-phase discharge. Simultaneously, the identical V-shaped structure ensures that the conductors of both lines are confined within a safe space trajectory, allowing for independent operation without interference, thus meeting the maintenance requirements of "same tower erection, separate control" for dual-circuit systems.

[0020] As the main load-bearing structure for double-circuit conductors, the first crossarm is prone to tilting and excessive tower torque due to uneven stress if only a single set of insulator strings or insulator strings of different structures are installed. The first and third insulator strings have the same structure, which can evenly transfer the conductor tension of the two circuits to both ends of the crossarm. The asymmetrical V-shaped structure's "double strings facing outwards, single string facing inwards" characteristic creates a reverse balance of tension on the crossarm for each set of insulator strings. The synergistic effect of the two strings can counteract the unilateral bending moment of the crossarm (such as the horizontal thrust of one conductor being balanced by the tension on the other side during strong winds), avoiding crossarm deformation or breakage due to localized load concentration and extending the service life of the tower.

[0021] Furthermore, the second insulator string consists of two insulator strings arranged in parallel.

[0022] Beneficial effects: As the upper conductor load-bearing structure of a double-circuit tower, the second crossarm must bear the conductor's own weight, the weight of icing, and the horizontal load brought by strong winds (especially in high-altitude and windy areas). The parallel double-string design, through the coordinated force sharing of two sets of insulator strings, improves the vertical load-bearing capacity compared to a single insulator string. It can effectively cope with the increased weight of the conductor and the horizontal thrust caused by strong winds under icing weather, avoiding insulator string breakage or crossarm deformation due to overload, and ensuring the stable operation of the upper line.

[0023] Furthermore, the second insulator strings are all arranged vertically.

[0024] Beneficial effects: The second insulator string bears the vertical load (conductor self-weight and icing weight) and longitudinal tension (tensile force generated by thermal expansion and contraction of the line) of the upper conductor. Vertical installation allows the load to be directly transferred along the axis of the insulator string to the second crossarm attachment point, avoiding horizontal components caused by tilted installations (such as the lateral tension on the crossarm caused by tilted strings). This axial force distribution mode maximizes the mechanical strength of the insulator string, reduces the additional torque of the insulator string hardware and the lateral bending moment of the crossarm, and prevents insulator breakage and crossarm deformation due to deviations in the force direction, thus meeting the requirements of long-term heavy-load operation.

[0025] The second insulator string is a parallel double-string structure. The vertical arrangement ensures that the stress state of the two insulator strings is completely consistent: the load in the vertical direction is evenly distributed to the two strings, eliminating the risk of overload on a single string. At the same time, the vertical layout keeps the spacing between the two strings stable, avoiding changes in the distance between strings due to tilting, and further ensuring the balance of the stress on both strings. Especially under extreme conditions such as icing and strong winds, it can effectively resist the impact of load fluctuations on the insulator strings.

[0026] Furthermore, the tower head between the second crossarm and the ground wire crossarm is a straight-arm structure, while the tower head between the second crossarm and the first crossarm is a conical structure.

[0027] Beneficial effects: The second crossarm supports the upper-level lines, while the ground wire crossarm bears the weight of the ground wire. The small distance between the two results in lower vertical loads and horizontal tensions that the tower head needs to transmit. The straight-arm structure (uniform cross-sectional dimensions, without narrowing) can stably transmit loads through a uniform stress section, meeting strength requirements without needing to increase the thickness of the tower steel. It also avoids stress concentration caused by abrupt changes in cross-section, making it suitable for long-term stable operation in low-load areas.

[0028] The first crossarm supports the lower layer of the line, and the second crossarm supports the upper layer. With a significant distance between them, the tower head needs to transfer the combined load of the two layers of lines. The conical structure (with the tower cross-section gradually narrowing from the first crossarm upwards to the second crossarm) conforms to the mechanical law of decreasing load: the cross-section near the first crossarm is larger and can withstand high loads; the cross-section near the second crossarm narrows as the load decreases, ensuring strength while reducing material waste. Simultaneously, the conical shape optimizes the tower's wind resistance, reduces the lateral thrust of strong winds on the tower head, and effectively enhances the overall stability of the tower, making it particularly suitable for high-altitude, windy tunneling environments.

[0029] Furthermore, the lateral length of the first crossarm is greater than the lateral length of the ground wire crossarm, and the lateral length of the ground wire crossarm is greater than the lateral length of the second crossarm.

[0030] Beneficial effects: The core of balancing the forces at the tower head is to avoid unilateral imbalance caused by differences in crossarm lengths. The first crossarm is the longest, and through the force characteristics of the V-shaped insulator strings it carries ("double strings facing outwards, single string facing inwards"), it can transfer the outer tension to the top of the tower head. The second crossarm is the shortest, and the vertical double insulator strings it carries are subjected to forces vertically downwards, resulting in minimal lateral torque on the tower body. The ground wire crossarm is of medium length, and its ground wire tension can act as a balancing layer, offsetting part of the outer tension of the first crossarm.

[0031] Furthermore, the first crossarm, the second crossarm, and the ground wire crossarm are all symmetrically fixed to the tower head with respect to the center line of the tower head.

[0032] Beneficial effects: This configuration makes the entire drilling tower structure more stable and the stress distribution more balanced. Attached Figure Description

[0033] The accompanying drawings, which are included to provide a further understanding of embodiments of the invention and form part of this application, do not constitute a limitation thereof. In the drawings: Figure 1 This is a front view of an embodiment of a dual-circuit drilling tower according to the present invention; Figure 2 This is a front view of the drilling tower after dimensioning, in an embodiment of a dual-circuit drilling tower according to the present invention. Figure 3 This is a side view of the drilling tower after dimensioning, in an embodiment of a dual-circuit drilling tower of the present invention; Figure 4 This is a side view of an embodiment of a dual-circuit drilling tower according to the present invention; Figure 5 This is a schematic diagram of the structure of a double-circuit drilling tower according to the present invention, in which a first ground wire hanging point and a second ground wire hanging point are set on the ground wire crossarm; Figure 6 This is a top view of the first and third insulator strings in an embodiment of a dual-circuit drilling tower according to the present invention.

[0034] The attached diagram shows the markings and corresponding component names: 1. Tower body; 2. Tower head; 3. First crossarm; 4. Second crossarm; 5. Ground wire crossarm; 6. Straight arm structure; 7. First insulator string; 8. Third insulator string; 9. Second insulator string; 10. First ground wire suspension point; 11. Second ground wire suspension point. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0036] As one embodiment of this application, such as Figures 1-2 As shown, this embodiment provides a dual-circuit drilling tower, including a tower body 1 and a tower head 2. The tower head 2 is fixedly connected to the top of the tower body 1. From bottom to top, a first crossarm 3, a second crossarm 4, and a ground wire crossarm 5 are connected to the tower head 2. In this embodiment, the first crossarm 3, the second crossarm 4, and the ground wire crossarm 5 are all symmetrically fixed on the tower head 2 with respect to the center line of the tower head 2. That is, the two ends of the first crossarm 3, the two ends of the second crossarm 4, and the two ends of the ground wire crossarm 5 are equidistant from the center line of the tower head 2, making the entire drilling tower a symmetrical structure. First insulator strings 7 are installed at both ends of the first crossarm 3, and second insulator strings 9 are installed at both ends of the second crossarm 4. First ground wire hanging points 10 are installed at both ends and the middle point of the ground wire crossarm 5 on the drilling side, and second ground wire hanging points 11 are installed at both ends of the ground wire crossarm 5 on the non-drilling side.

[0037] In one embodiment, such as Figure 1 As shown, in this embodiment, the lateral length of the first crossarm 3 is greater than the lateral length of the ground wire crossarm 5, and the lateral length of the ground wire crossarm 5 is greater than the lateral length of the second crossarm 4. That is, the lateral length of the first crossarm 3 is the longest, the lateral length of the second crossarm 4 is the shortest, and the lateral length of the ground wire crossarm 5 is between the lateral length of the first crossarm 3 and the lateral length of the second crossarm 4.

[0038] Combination Figure 2 As shown, in this embodiment, the tower body 1 has a height of 12000mm, the first crossarm 3 has a horizontal length of 19000mm, the second crossarm 4 has a horizontal length of 8000mm, and the ground wire crossarm 5 has a horizontal length of 16400mm.

[0039] In one embodiment, such as Figure 1 As shown, in this embodiment, the first insulator string 7 is V-shaped, combined with... Figure 6 As shown, one side of the first insulator string 7 consists of two parallel insulator strings, and the other side of the first insulator string 7 consists of one insulator string. The lower end of the one insulator string intersects at the midpoint of the line connecting the lower ends of the two parallel insulator strings.

[0040] In this embodiment, the V-shape of the first insulator string 7 has a double insulator string on one side and a single insulator string on the other side.

[0041] Combination Figure 1 and Figure 6 As shown, in this embodiment, a third insulator string 8 with the same structure as the first insulator string 7 is provided at a position adjacent to the first insulator string 7. That is, the third insulator string 8 is also a V-shaped structure, and one side of the third insulator string 8 is a double insulator string, and the other side is a single insulator string.

[0042] Furthermore, in this embodiment, the side of each insulator string, including the first insulator string 7 and the third insulator string 8, faces the center of the tower head 2. This V-shaped insulator string configuration of the first insulator string 7 and the third insulator string 8 ensures that none of the insulators are subjected to pressure when subjected to strong wind loads perpendicular to the line. Due to the inherent stability of the triangular structure of the V-shape, wind deflection of the insulator string can be effectively suppressed.

[0043] In one embodiment, such as Figure 1As shown, in this embodiment, the second insulator strings 9 at both ends of the second crossarm 4 are two insulator strings arranged in parallel, and the second insulator strings 9 are both arranged vertically.

[0044] In one embodiment, combined Figure 4 and Figure 5 As shown, first ground wire hanging points 10 are respectively set at the lower positions of the two ends and the middle point of the ground wire crossarm 5 on the drilling-crossing side, and second ground wire hanging points 11 are respectively set at the higher positions of the two ends of the ground wire crossarm 5 on the non-drilling-crossing side. Figure 3 As shown, in this embodiment, the vertical distance between the first ground wire hanging point 10 and the second ground wire hanging point 11 is 1500mm; this can further reduce the height of the ground wire on the drilling tower.

[0045] In one embodiment, such as Figure 1 As shown, in this embodiment, the tower head 2 between the second crossarm 4 and the ground wire crossarm 5 is a straight arm structure 6, that is, the tower head 2 between the second crossarm 4 and the ground wire crossarm 5 is a rectangular structure with uniform cross-sectional dimensions and no narrowing. The tower head 2 between the second crossarm 4 and the first crossarm 3 is a conical structure that is narrow at the top and wide at the bottom. In this embodiment, the tower body 1 is also a conical shape that is narrow at the top and wide at the bottom. The tower head 2 between the second crossarm 4 and the first crossarm 3 is welded and fixed to the top of the tower body 1.

[0046] like Figure 2 As shown, in this embodiment, the horizontal width of the straight arm structure 6 is 1350mm.

[0047] In one embodiment, such as Figure 2 and Figure 3 As shown, the vertical distance between the hanging point of the first insulator string 7 on the first crossarm 3 and the hanging point of the second insulator string 9 on the second crossarm 4 is 4000mm, and the vertical distance between the hanging point of the second insulator string 9 on the second crossarm 4 and the hanging point of the first ground wire 10 is 2000mm.

[0048] Thus, the total height of the dual-circuit drilling tower of the present invention is 19,500 mm, and the first ground wire suspension point 10 on the drilling side is 18,000 mm. Therefore, it can be ensured that the maximum height of the ground wire at the drilling point does not exceed 19,000 mm, thereby ensuring that the drilling tower of the present invention can successfully drill directly to higher voltage level lines.

[0049] The drilling tower of this invention has a low overall height, and the ground wire suspension point on the drilling side is set at a low position. At the same time, it is changed to three ground wires, which can further reduce the ground wire height at the drilling point. The insulator string of the drilling tower is changed to a V-shape, which utilizes triangular stability to reduce the wind deflection of the jumper wire, thereby reducing the corridor width of the drilling tower. This drilling tower can directly drill through a 330kV double-circuit drilling tower to a higher voltage level line without modifying the original line, detouring through the drilling line, or changing the 330kV double circuit to a single circuit. Therefore, it solves the problems of power outage construction, high construction difficulty, high overall investment, and inconvenient operation.

[0050] It should be noted that the above description of the disclosed embodiments enables those skilled in the art to implement or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A dual-circuit drilling tower, comprising a tower body and a tower head, characterized in that, The tower head is connected from bottom to top with a first crossarm, a second crossarm, and a ground wire crossarm. A first insulator string is installed at both ends of the first crossarm, and a second insulator string is installed at both ends of the second crossarm. A first ground wire hanging point is installed at both ends and the middle point of the lower side of the ground wire crossarm on the drilling side, and a second ground wire hanging point is installed at both ends of the upper side of the ground wire crossarm on the non-drilling side.

2. The dual-circuit drilling tower according to claim 1, characterized in that, The first insulator string is V-shaped.

3. A dual-circuit drilling tower according to claim 2, characterized in that, One side of the first insulator string consists of two parallel insulator strings, and the other side consists of a single insulator string. The lower end of the single insulator string intersects at the midpoint of the line connecting the lower ends of the two parallel insulator strings.

4. A dual-circuit drilling tower according to claim 3, characterized in that, One side of the first insulator string is positioned facing the center of the tower head.

5. A dual-circuit drilling tower according to any one of claims 2-4, characterized in that, A third insulator string with the same structure as the first insulator string is provided at a position adjacent to the first insulator string.

6. A dual-circuit drilling tower according to claim 1, characterized in that, The second insulator string consists of two insulator strings arranged in parallel.

7. A dual-circuit drilling tower according to claim 6, characterized in that, The second insulator strings are all vertically arranged.

8. A dual-circuit drilling tower according to claim 1, characterized in that, The tower head between the second crossarm and the ground wire crossarm is a straight-arm structure, and the tower head between the second crossarm and the first crossarm is a conical structure.

9. A dual-circuit drilling tower according to claim 1, characterized in that, The lateral length of the first crossarm is greater than the lateral length of the ground wire crossarm, and the lateral length of the ground wire crossarm is greater than the lateral length of the second crossarm.

10. A dual-circuit drilling tower according to claim 1, characterized in that, The first crossarm, the second crossarm, and the ground wire crossarm are all symmetrically fixed to the tower head with respect to the center line of the tower head.

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