A wiring system for the low-voltage side of a single-phase autotransformer and a prefabricated switchyard in a confined space.

Abstract

This utility model provides a wiring system for the low-voltage side of a single-phase autotransformer and a prefabricated box-type switchgear in a confined space, comprising: a low-voltage bushing of the single-phase autotransformer, an aluminum tube busbar branch bus, an aluminum tube busbar main bus, a copper tube bus, and a prefabricated box-type switchgear. The low-voltage bushing of the single-phase autotransformer is connected to the aluminum tube busbar branch bus via a flexible copper busbar; the aluminum tube busbar branch bus is connected to the phase-separated aluminum tube busbar main bus via a flexible copper busbar; the aluminum tube busbar main bus is connected to the copper tube bus; and the end of the copper tube bus is connected to the prefabricated box-type switchgear. The wiring system provided by this utility model occupies little space and has a simple and compact layout; the delta connection on the low-voltage side of the transformer uses an aluminum tube bus to reduce costs, and the connection to the box-type switchgear bus avoids terrain limitations by using a flexible copper tube bus; the prefabricated box-type switchgear occupies little space, is easy to assemble and saves construction time, and the internal switch cabinet spacing is easy to expand.

Description

Technical Field

[0001] This utility model belongs to the field of substation wiring technology, and in particular relates to a wiring system for the low-voltage side of a single-phase autotransformer and a box-type switch station in a confined space. Background Technology

[0002] In large substations and power plants, where the size or weight of three-phase transformers cannot meet transportation requirements, single-phase power transformers are used and connected according to specified connection groups. To reduce the impact of third harmonics, transformers typically employ a star-delta (Y / Δ) connection method, where the high-voltage side uses a star connection and the low-voltage side uses a delta connection (see Yd11 connection illustration below). Figure 1 For single-phase power transformers, the low-voltage windings need to be delta-connected outside the transformer body. In substations and other locations where space is not limited, overhead steel strands can be combined with open switchgear for connection. However, in mountainous areas, renovation and expansion projects, or other locations with limited space, using overhead steel strands requires the arrangement of conductor frames and consideration of factors such as conductor wind deflection and swaying, which occupies a large area and cannot be arranged.

[0003] Due to the need for wiring on the 35kV side, after the delta connection is made on the low-voltage side of the single-phase transformer, it needs to be led to the 35kV switchgear. Similarly, if the traditional combination scheme of overhead steel strand and open switchgear is used, it will be greatly affected by the spatial terrain conditions.

[0004] Because of the large capacity of the transformer, the current on the 35kV side is usually very large. If a cable solution is used on the 35kV side, it is difficult to meet the current carrying capacity and short-circuit thermal stability requirements of the cable.

[0005] The existing scheme uses a combination of steel stranded wire and open-type switchgear (i.e., the 35kV delta connection busbar on the low-voltage side of the transformer uses steel-cored aluminum stranded wire, and the switchgear connected to the 35kV busbar of the transformer uses open-type switchgear connected to the 35kV main busbar via steel-cored aluminum stranded wire). Its main disadvantages are: 1. It occupies a large area, and the conductors need to take into account wind deflection factors, which increases the phase spacing. The conductor sag to the ground also increases the height, and a conductor frame needs to be arranged; 2. The site shape needs to be as regular as possible to facilitate the arrangement and connection of the conductor frame and open-type switchgear; 3. It is not convenient for the expansion of the 35kV bay on the low-voltage side.

[0006] Large single-phase autotransformers are mostly used in large substations. Large substations typically have flat sites with unrestricted space, and their low-voltage side connections usually employ a combination of steel strand and open-type switchgear. However, in substation design in canyon areas, the combination of steel strand and open-type switchgear cannot be used due to terrain limitations. Utility Model Content

[0007] The purpose of this utility model is to provide a wiring system for the low-voltage side of a single-phase autotransformer and a box-type switch station in a confined space, so as to solve the wiring arrangement of the low-voltage side of a single-phase autotransformer in a confined space or complex terrain.

[0008] Therefore, the above-mentioned objective of this utility model is achieved through the following technical solution:

[0009] A wiring system for the low-voltage side of a single-phase autotransformer and a prefabricated box-type switch station in a confined space includes: a low-voltage bushing of a single-phase autotransformer, aluminum tube busbars, branch busbars, aluminum tube busbars, main busbars, copper tube busbars, and a prefabricated box-type switch station.

[0010] The low-voltage bushing of the single-phase autotransformer is connected to the aluminum tube busbar via a flexible copper busbar.

[0011] The aluminum tube bus branch bus is connected to the phase-separated aluminum tube bus main bus via a flexible copper busbar.

[0012] The aluminum tube busbar is connected to the copper tube busbar.

[0013] The end of the copper tube is connected to the prefabricated box-type switch station.

[0014] While adopting the above technical solutions, this utility model may also adopt or combine the following technical solutions:

[0015] As a preferred technical solution of this utility model: the aluminum tube main busbar and the copper tube busbar are connected by a copper-aluminum transition terminal joint.

[0016] As a preferred technical solution of this utility model: the copper-aluminum transition terminal joint is connected to the connector terminal plate of the copper pipe female.

[0017] As a preferred technical solution of this utility model: a flexible expansion joint is provided in the connection section between the aluminum tube main bus and the copper tube.

[0018] As a preferred technical solution of this utility model: the aluminum tube bus branch bus and the aluminum tube bus main bus are connected by an aluminum tube T-type connector.

[0019] As a preferred technical solution of this utility model: a zinc oxide surge arrester is provided on the main busbar of the aluminum tube, and the zinc oxide surge arrester is connected to the main busbar of the aluminum tube via a surge arrester clamp and a conductor.

[0020] As a preferred technical solution of this utility model: the segments of the aluminum tube busbar are spliced ​​together in pairs via aluminum tube busbar intermediate joints.

[0021] The sections of the copper tube are spliced ​​together in pairs via intermediate joints.

[0022] As a preferred technical solution of this utility model: the copper tube is provided with a vertical transition section and a matching post insulator.

[0023] As a preferred technical solution of this utility model: the aluminum tube busbar branch busbar, the aluminum tube busbar main busbar, and the copper tube busbar are supported by a combination of steel columns and steel brackets;

[0024] The steel columns are fixed to the concrete foundation;

[0025] The aluminum tube busbar branch busbar, aluminum tube busbar main busbar, and copper tube busbar are equipped with interlaced fixed support hardware and sliding support hardware.

[0026] The fixed support hardware and the sliding support hardware are respectively equipped with steel brackets to limit the aluminum tube bus branch bus, the aluminum tube bus main bus, and the copper tube bus.

[0027] This utility model provides a wiring system for the low-voltage side of a single-phase autotransformer and a box-type switch station in a confined space, which has the following advantages:

[0028] 1) It occupies little space and has a simple and compact layout;

[0029] 2) The low-voltage side delta connection of the transformer adopts aluminum tube bus connection to reduce costs, and the rear is connected to the 35kV box-type switch station bus to avoid terrain restrictions and adopts copper tube bus for connection with good flexibility.

[0030] 3) The section from the 35kV side of the transformer to the 35kV box-type switch station uses copper tube busbars to ensure current carrying capacity and transmission capacity;

[0031] 4) The 35kV side adopts a prefabricated box-type switch station, which occupies a small area, is simple to assemble and saves construction time, and the internal 35kV switch cabinet bay is easy to expand.

[0032] 5) Simple maintenance. Attached Figure Description

[0033] Figure 1 This is a delta connection structure on the low-voltage side of a single-phase power transformer.

[0034] Figure 2 This diagram illustrates the connection structure of the wiring system between the low-voltage side of a single-phase autotransformer and a box-type switch station in a confined space, as provided by this utility model.

[0035] Figure 3 for Figure 1 Cross-sectional view along the AA direction.

[0036] Figure 4 for Figure 1 Cross-sectional view along the BB direction.

[0037] Figure 5 for Figure 1 Cross-sectional view along the CC direction.

[0038] Figure 6 This is a schematic diagram of the terminal block lap joint for the copper-aluminum transition terminal joint of the aluminum tube. Detailed Implementation

[0039] The low-voltage side delta connection of the autotransformer uses aluminum busbars (advantages: simple and compact layout, large current carrying capacity, and good economy). The aluminum busbar ends are connected to the 35kV box-type switchyard using copper busbars (advantages: simple and compact layout, large current carrying capacity, and copper busbars are flexible and easy to bend). Surge arresters are installed on the aluminum busbars to prevent overvoltage intrusion and damage to the transformer. Flexible connections or expansion joints are installed at all busbar joints to compensate for busbar deformation. A combination of fixed and sliding supports is used to avoid the effects of thermal expansion and contraction of the busbars.

[0040] Copper busbar flexible connections are used between the main busbar and the branch busbars of the aluminum tube busbar, and between the branch busbars and the low-voltage bushings of the transformer. The joint hardware between the branch busbars and the main busbars uses aluminum tube busbar T-type connectors. To avoid the effects of thermal expansion and contraction of the busbars, a fixed support hardware is used at the middle point of the branch busbar, while sliding support hardware is used on both sides.

[0041] A copper-aluminum transition terminal joint is installed at one end of the aluminum conduit busbar (the right end in the example diagram, but it can be at the left or right end or in the middle of the busbar, depending on the actual layout). The copper-aluminum transition terminal joint is connected to the copper conduit busbar terminal block via a copper flexible expansion joint. Similarly, a fixed support hardware is installed at a point in the middle of the copper conduit busbar, and sliding support hardware is installed at the remaining positions on both sides. The end of the copper conduit busbar is connected to the 35kV switchgear incoming busbar via the terminal joint terminal block and the flexible copper busbar. A fixed support hardware is installed at a point in the middle of the copper conduit busbar, and sliding support hardware is installed at the remaining positions on both sides.

[0042] The low-voltage bushing of the transformer is connected to the copper-aluminum transition terminal joint of the aluminum tube busbar via a flexible copper busbar and bolts. The terminal plate size of the terminal joint must meet the current carrying capacity requirements and the terminal plate size must meet the formula.

[0043] Because the main busbar is quite long, it is transported in sections for easy transport and assembly. The sections are connected and assembled using connectors. The main busbar of the aluminum busbar uses aluminum connectors, and the main busbar of the copper busbar uses copper connectors.

[0044] To accommodate varying heights of interfaces with different equipment, vertical transition sections are installed at appropriate locations on the copper busbars to connect busbars at different heights.

[0045] Zinc oxide surge arresters are installed on the main busbar of the aluminum tube busbar to minimize the impact of lightning overvoltage and switching overvoltage on the low-voltage side of the main transformer, and to prevent the transformer from being damaged by lightning intrusion waves.

[0046] Specifically, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

[0047] In the diagram, 1 is a single-phase autotransformer, 2 is the low-voltage bushing (35kV) of the autotransformer, 3 is a flexible copper busbar, 4 is the copper-aluminum transition terminal joint of the aluminum tube busbar, 5 is the branch busbar of the aluminum tube busbar, 6 is a steel support, 7 is the sliding support hardware of the tube busbar, 8 is a concrete foundation, 9 is a steel column, 10 is the T-joint of the aluminum tube busbar, 11 is the fixed support hardware of the tube busbar, 12 is the surge arrester clamp, 13 is the surge arrester, 14 is the copper flexible expansion joint, 15 is the copper tube busbar, 16 is the post insulator, 17 is the intermediate joint of the aluminum tube busbar, 18 is the intermediate joint of the copper tube busbar, 19 is the terminal joint of the copper tube busbar, and 20 is the main busbar of the aluminum tube busbar.

[0048] The low-voltage bushing 2 of the transformer is bolted to the copper-aluminum transition terminal joint 4 of the aluminum tube busbar via a flexible copper busbar 3. The terminal plate size of the terminal joint must meet the current carrying capacity requirements, and the terminal plate size must meet the following formula (all other conductor connections below must meet this formula, and other details will not be repeated):

[0049] Figure 6 In the diagram, a (mm) represents the terminal block overlap length, and b (mm) represents the terminal block overlap width.

[0050] a>b

[0051] S = a × b

[0052]

[0053] In the formula, S is the area of ​​the terminal block (mm²). 2 );I j To calculate the current (A) (i.e., the conductor current magnitude corrected for environmental factors, etc.); J is the required current density value for the unplated connector contact surface, which can be found in the table below. When the connector terminal block is made of copper, refer to J. Cu When the connector terminal block is made of aluminum, refer to J. Al .

[0054] Table 1

[0055]

[0056] In the table above, the unit of operating current is A; J Cu J Al The unit is A / mm 2 .

[0057] Each single-phase autotransformer's low-voltage bushing 2 is connected to the corresponding phases of the three-phase aluminum busbar 20 (a, b, c) via aluminum busbar 5. Specifically, the x and a bushings on the low-voltage side of the A-phase autotransformer are connected to phases c and a of the main busbar 20, respectively; the y and b bushings on the low-voltage side of the B-phase autotransformer are connected to phases a and b of the main busbar 20, respectively; and the z and c bushings on the low-voltage side of the C-phase autotransformer are connected to phases b and c of the main busbar 20, thus forming a delta circuit on the low-voltage side of the transformer.

[0058] The main busbar is supported by a combination of steel columns 9, steel brackets 6, and post insulators 16. The steel columns 9 are reliably fixed to the concrete foundation 8, and the fixing method can be pre-embedded anchor bolts or post-installed chemical anchors. Both ends of the branch busbar 5 are connected to the main busbar 20 of the aluminum busbar and the low-voltage bushing 2 of the transformer respectively using flexible copper busbars 3. The joint hardware between the branch busbar 5 and the main busbar 20 of the aluminum busbar uses aluminum busbar T-type joints 10.

[0059] The aluminum tube busbar 20 is arranged in parallel phases. The distances between phases a, b, and c, as well as their distances to ground, must meet the minimum safe clearance requirements of the power distribution equipment. The main busbar support foundations are arranged relatively evenly and must meet structural strength requirements. A fixed support fitting 11 is installed at a point relatively close to the center of the aluminum tube busbar 20. The remaining support fittings on both sides are sliding support fittings 11 to avoid the effects of thermal expansion and contraction of the tube busbar. Figure 2 , Figure 3 and Figure 4 As shown.

[0060] A zinc oxide surge arrester 13 is installed on the aluminum tube main busbar 20 to minimize the impact of lightning overvoltage and switching overvoltage on the low-voltage side of the main transformer, and to prevent the transformer from being damaged by lightning surge waves. The equipment end of the surge arrester 13 is connected to the aluminum tube main busbar 20 through the surge arrester clamp 12 and the conductor, and the grounding end of the surge arrester 13 is reliably connected to the main grounding grid through a flat steel or other metal conductor.

[0061] A copper-aluminum transition terminal joint 4 is installed at one end of the aluminum main busbar 20 (the right end in the example diagram, but it can be the left or right end or the middle of the busbar, depending on the actual layout). The copper-aluminum transition terminal joint 4 is connected to the copper busbar terminal joint 19 of the copper busbar 15 through a copper flexible expansion joint 14.

[0062] When the conductor operating current is relatively small, the copper tube 15 can also be replaced by a cable, and the joint between the aluminum tube 15 and the cable will be replaced by a special cable joint.

[0063] To accommodate varying heights at interfaces with different equipment, a vertical transition section is installed at an appropriate location on the copper busbar 15 to connect busbars of different heights. Supporting insulators 16 must be installed in the vertical section for support and fixation. Figure 3 As shown.

[0064] Similarly, a fixed support fitting 11 is installed at the middle point of the copper tube, and sliding support fittings 7 are installed at the other positions on both sides, such as... Figure 2 , Figure 3 and Figure 4 As shown.

[0065] Because the main busbar is quite long, it is transported in sections for easy transport and assembly. The sections are connected and assembled using connectors. The main busbar of the aluminum main busbar uses aluminum main busbar connector 17, and the main busbar of the copper main busbar uses copper main busbar connector 18.

[0066] The end of the copper tube busbar 15 is connected to the incoming busbar of the 35kV switchgear via the terminal block 19 and the flexible copper busbar 3.

[0067] The above specific embodiments are used to explain and illustrate the present utility model, and are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made to the present utility model within the spirit and protection scope of the claims shall fall within the protection scope of the present utility model.

Claims

1. A wiring system for the low-voltage side of a single-phase autotransformer and a prefabricated switchyard in a confined space, characterized in that, include: Single-phase autotransformer low-voltage bushing (2), aluminum tube bus branch bus (5), aluminum tube bus main bus (20), copper tube bus (15), prefabricated box-type switch station; The low-voltage bushing (2) of the single-phase autotransformer is connected to the aluminum tube busbar (5) via a flexible copper busbar (3); The aluminum tube branch bus (5) is connected to the phase-separated aluminum tube main bus (20) via a flexible copper busbar (3); The aluminum tube main bus (20) is connected to the copper tube (15); The end of the copper tube (15) is connected to the prefabricated box-type switch station.

2. The wiring system according to claim 1, characterized in that, The aluminum main bus (20) and the copper main bus (15) are connected by a copper-aluminum transition terminal joint (4).

3. The wiring system according to claim 2, characterized in that, The copper-aluminum transition terminal joint (4) is connected to the terminal block (19) of the copper tube female (15).

4. The wiring system according to claim 1, 2, or 3, characterized in that, The connection section between the aluminum tube main busbar (20) and the copper tube busbar (15) is provided with a flexible expansion joint (14).

5. The wiring system according to claim 1, characterized in that, The aluminum tube bus branch bus (5) and the aluminum tube bus main bus (20) are connected by an aluminum tube bus T-type connector (10).

6. The wiring system according to claim 1, characterized in that, The aluminum tube main busbar (20) is equipped with a zinc oxide surge arrester (13), which is connected to the aluminum tube main busbar (20) via a surge arrester clamp (12) and a conductor.

7. The wiring system according to claim 1, characterized in that, The segments of the aluminum tube main busbar (20) are spliced ​​together in pairs via aluminum tube intermediate joints (17). The segments of the copper tube (15) are spliced ​​together in pairs via the copper tube intermediate joint (18).

8. The wiring system according to claim 1, characterized in that, The copper tube (15) is provided with a vertical transition section and a matching post insulator (16).

9. The wiring system according to claim 1, characterized in that, The aluminum tube bus branch bus (5), aluminum tube bus main bus (20), and copper tube bus (15) are supported by a combination of steel columns (9) and steel brackets (6); The steel column (9) is fixed to the concrete foundation (8); The aluminum tube bus branch bus (5), aluminum tube bus main bus (20), and copper tube bus (15) are provided with interlaced fixed support hardware (11) and sliding support hardware (7); The fixed support hardware (11) and the sliding support hardware (7) are respectively provided with steel brackets (6) to limit the aluminum tube branch bus (5), the aluminum tube main bus (20), and the copper tube bus (15).

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