A single-phase autotransformer core side column insulation structure

Abstract

This invention relates to an insulation structure for the core side column of a single-phase autotransformer, belonging to the field of single-phase autotransformer technology. The technical solution is as follows: the pad A (9) comprises three layers arranged vertically. The middle layer is a crescent-shaped pad (9-1) supported on the inner side of the core side column coil. The upper and lower pads form a step near the outer edge of the crescent-shaped pad (9-1). The paper-insulated cable (7) is attached to the lower edge of the crescent-shaped pad (9-1) and located at the step formed by the outer edges of the upper and lower pads. The paper-insulated cable (7) is led out to the web of the lower clamp of the core for grounding. The insulating paperboard (1) and the support strip (2) are respectively fixed on the main column (3) screen and the side column (4) screen. The beneficial effects of this invention are: it ensures that the transformer has sufficient insulation strength and more stable performance during normal operation, while also ensuring a reliable safety margin and avoiding partial discharge or even insulation breakdown caused by electric field distortion.

Description

Technical Field

[0001] This invention relates to a core side column insulation structure of a single-phase autotransformer, belonging to the field of single-phase autotransformer technology. Background Technology

[0002] Power transformers, when operating in power systems, inherently suffer from uneven electric field distribution and field strength concentration due to poor electrode shape. Under the influence of lightning strikes and switching overvoltages, electric field distortion and partial discharge can easily occur, severely impacting the stable operation of the transformer. With the rapid development of the power industry, the requirements for the safe and stable operation of transformers are becoming increasingly stringent. Furthermore, transformer technology is constantly being updated and improved, with advancements in both structure and raw materials.

[0003] For a single-phase 500kV autotransformer, under the premise of meeting the contractual and technical requirements for transformer parameters and performance, the core column is typically circular in cross-section, while the side columns use an elliptical cross-section. Whether or not windings are installed on the side columns depends on the product's specifications. If windings are installed on the side columns, the outer side of the core is an insulation system composed of excitation coils, voltage regulating coils, and insulating cylinders. This insulation system has a high insulation level, at 220kV. Therefore, the cross-section of the elliptical side column core needs to be rounded to match the cylindrical windings. This requires an insulation system to support the windings, tighten the core, and simultaneously improve the electrode shape of the core lamination steps to achieve a uniform electric field distribution.

[0004] Traditional insulation structures simply stack multiple insulating pads to support the rounded shielding device with an elliptical cross-section of the side column core. The electrodes of the rounded shielding device are far away from the core laminations. Therefore, there are sharp corners at the lower end of the rounded device, which makes the electric field distribution uneven and prone to discharge from the coil end to ground, affecting the safe and stable operation of the transformer and creating safety hazards for the transformer.

[0005] Furthermore, in traditional insulation structures, the allowable electric field value of the oil gap is increased by dividing it with partitions. This is the thin paper tube small oil gap structure commonly used in transformer insulation systems. For some transformers, a partition system is required between the main coil and the side coil, and between the main coil and the side yoke. The traditional partition system structure is shown in the attached figure. Figure 1 As shown, the excessive oil gap between the side column coil enclosure and the main column coil enclosure is separated by a partition (the support strip and the insulating cardboard are fixed by a high-strength mesh belt). However, due to the lack of an effective fixing and support device, the partition deforms or even tilts after the transformer body is dried and put into the furnace. Therefore, it is necessary to reorganize and bind it again. Even after the reorganization, the partition system will still pose a hidden danger to the safe and stable operation of the transformer after the transformer passes the test and leaves the factory. Summary of the Invention

[0006] The purpose of this invention is to provide a single-phase autotransformer core side-post insulation structure that ensures sufficient insulation strength and more stable performance during normal operation of the transformer, while also ensuring a reliable safety margin to avoid partial discharge or even insulation breakdown caused by electric field distortion, thus solving the problems existing in the background technology.

[0007] The technical solution of this invention is: A single-phase autotransformer core side column insulation structure includes a ground electrode shielding structure and an oil gap segmentation structure on the outer side of the screen. The ground electrode shielding structure includes a paper-insulated cable and a pad A. The pad A consists of three layers arranged vertically. The middle layer is a crescent-shaped pad supported inside the iron core side column coil. The upper and lower pads form a step that matches the paper-insulated cable at the end of the crescent-shaped pad's arc-shaped outer edge. The paper-insulated cable is close to the arc-shaped edge of the crescent-shaped pad and located at the step formed by the outer edges of the upper and lower pads. The paper-insulated cable is led out to the web of the lower clamp of the iron core for grounding. The outer partition structure of the screen includes insulating cardboard and support strips, which are fixed to the main column screen and the side column screen respectively.

[0008] The upper and lower pads in pad A are both composed of several trapezoidal pads, with a certain interval between adjacent trapezoidal pads in each layer.

[0009] The length of the upper pad in pad A is shorter than the length of the lower pad.

[0010] The pad A is fixed to the lower clamp of the iron core by the pad B.

[0011] The insulating cardboard and support strips in the oil gap structure on the outer side of the screen are tied to the main column screen and the side column screen with binding straps.

[0012] The support strips in the oil gap structure on the outer side of the screen are located between the insulating cardboard and the main column screen and the side column screen.

[0013] The insulating cardboard in the oil gap structure on the outer side of the screen is an arc shape that matches the main column screen and the side column screen.

[0014] The beneficial effects of this invention are: it ensures sufficient insulation strength and more stable performance during normal operation; at the same time, it guarantees a reliable safety margin, avoiding partial discharge or even insulation breakdown caused by electric field distortion. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the background technology. Figure 2 A schematic diagram of the oil gap structure on the outer side of the screen; Figure 3This is a schematic diagram of the ground electrode shielding structure; Figure 4 for Figure 3 AA section diagram; Figure 5 for Figure 4 BB cross-section diagram; In the diagram: 1. Insulating cardboard; 2. Support strip; 3. Main column; 4. Side column; 5. Longitudinal section of the long axis of the side column; 6. Center line of the side column; 7. Paper-insulated cable; 8. High-voltage clamp; 9. Pad A; 9. Crescent-shaped pad; 9-1. Trapezoidal pad; 9-2. Upper pad; 9-3. Lower pad; 9-4. Pad B10. Detailed Implementation

[0016] The invention will be further described below with reference to the accompanying drawings and examples.

[0017] See attached document Figure 2-5 A single-phase autotransformer core side column insulation structure, comprising a ground electrode shielding structure and an oil gap segmentation structure on the outer side of the screen; The ground electrode shielding structure includes a paper-insulated cable 7 and a pad A9. The pad A9 consists of three layers arranged vertically. The middle layer is a crescent-shaped pad 9-1 supported inside the iron core side column coil. The upper layer pad 9-3 and the lower layer pad 9-4 form a step that matches the paper-insulated cable 7 at their ends near the outer arc of the crescent-shaped pad 9-1. The paper-insulated cable 7 is close to the lower arc of the crescent-shaped pad 9-1 and is located at the step formed by the outer edges of the upper and lower pads. The paper-insulated cable 7 is led out to the web of the lower clamp of the iron core for grounding. The outer partition structure of the screen includes insulating paperboard 1 and support strip 2, which are fixed to the main column 3 screen and the side column 4 screen, respectively.

[0018] In this example, refer to the appendix. Figure 3-5 In the ground electrode shielding structure, the upper and lower layers of the pad A9 are both composed of several trapezoidal pads 9-2. A certain gap is provided between adjacent trapezoidal pads 9-2 in each layer, the size of which is determined by the size of the crescent-shaped pad 9-2. The upper layer pad is shorter than the lower layer pad, as shown in the attached diagram. Figure 5 As shown, the upper pad 9-3 and the lower pad 9-4 form a step near the outer edge of the crescent-shaped pad 9-1 to cooperate with the paper-insulated cable 7.

[0019] Spacer A9 is fixed to the lower clamp of the core by spacer B10, as shown in the attached figure. Figure 3 As shown.

[0020] The electrode shielding structure utilizes the plasticity and arc shape of the paper-insulated cable 7 to improve the electrode shape with sharp corners at the end of the round shielding device, making the electric field distribution as uniform as possible. The arc design of the crescent-shaped pad 9-1 shapes the paper-insulated cable 7, effectively improving the electric field distribution at the end of the elliptical side column coil, eliminating the risk of end discharge, and ensuring the stable and reliable operation of the transformer. At the same time, the combination of the crescent-shaped pad 9-1 and the trapezoidal pad 9-2 effectively divides the oil gap and provides effective support for the support plate structure that tightens the iron core.

[0021] See attached document Figure 2 The oil gap segmentation structure on the outer side of the enclosure is designed to rationally divide the oil gap according to its size. It consists of insulating cardboard 1 and several support strips 2. The insulating cardboard 1 and support strips 2 are tied to the main column 3 and the side column 4 enclosure with binding tape. This design is mainly to address the danger that a large oil gap between the outer side enclosure and the outer side of the main column enclosure can lead to high oil flow velocity and static electricity in the oil, causing distortion of the electric field. This design not only rationally divides the oil gap and improves insulation strength, but also provides a more stable binding than traditional structures, resulting in more stable performance and effectively ensuring sufficient mechanical strength and short-circuit withstand capability of the transformer. The structure of the insulating cardboard and support strips is also simpler and easier to process.

Claims

1. A single-phase autotransformer core side-post insulation structure, characterized in that: It includes a ground electrode shielding structure and an oil gap segmentation structure on the outer side of the enclosure; The ground electrode shielding structure includes a paper-insulated cable (7) and a pad A (9). The pad A (9) includes three layers arranged vertically. The middle layer is a crescent-shaped pad (9-1) supported on the inner side of the iron core side column coil. The upper layer pad (9-3) and the lower layer pad (9-4) form a step that matches the paper-insulated cable (7) at the end of the crescent-shaped pad (9-1) near the outer edge of the arc. The paper-insulated cable (7) is close to the lower edge of the crescent-shaped pad (9-1) and located at the step formed by the outer edges of the upper and lower layers. The paper-insulated cable (7) is led out to the web of the lower clamp of the iron core for grounding. The outer partition structure of the screen includes an insulating cardboard (1) and a support strip (2), which are fixed to the main column (3) screen and the side column (4) screen respectively.

2. The single-phase autotransformer core side-post insulation structure according to claim 1, characterized in that: The upper layer pad (9-3) and lower layer pad (9-4) of the pad A (9) are both composed of several trapezoidal pads (9-2), and there is a gap between two adjacent trapezoidal pads (9-2) in each layer.

3. The single-phase autotransformer core side-post insulation structure according to claim 2, characterized in that: The length of the upper pad (9-3) in pad A (9) is less than the length of the lower pad (9-4).

4. The single-phase autotransformer core side-post insulation structure according to claim 3, characterized in that: The pad A (9) is fixed to the lower clamp of the core by the pad B (10).

5. The single-phase autotransformer core side-post insulation structure according to claim 1, characterized in that: The insulating cardboard (1) and support strip (2) in the outer dividing oil gap structure of the screen are tied to the main column (3) screen and the side column (4) screen by binding straps.

6. The single-phase autotransformer core side-post insulation structure according to claim 5, characterized in that: The support strip (2) in the outer partition oil gap structure of the screen is located between the insulating cardboard (1) and the main column (3) screen and the side column (4) screen.

7. The single-phase autotransformer core side-post insulation structure according to claim 6, characterized in that: The insulating cardboard (1) in the oil gap structure on the outer side of the screen is an arc shape that matches the screen of the main column (3) and the screen of the side column (4).

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