Manufacturing method of stator bar of main insulation structure with circular inside and square outside

Abstract

The invention discloses a manufacturing method of a stator bar of a main insulation structure with a circular inner part and a square outer part, and is suitable for the field of large-scale generator manufacturing. The stator bar is composed of a circular lead formed by twisting and transposing circular strands and a main insulator with a circular inner part and a square outer part, and a more-glue mould pressing or less-glue VPI manufacturing process is adopted. The stator bar with the main insulation structure with the round inside and the square outside has the advantages of clear principle, novel structure, convenient process and easiness in design and manufacture. The lead wire adopts a circular structure, so that the main insulation internal electric field of the stator bar can be greatly reduced, and the electrical performance and the breakdown voltage level of the stator bar are improved. The exterior of the main insulator adopts a square structure, so that the design consistency of the generator and the convenience of process wire embedding can be ensured. The stator bar with the round outside and the square inside can remarkably improve the rated voltage level of a large generator, and has great application prospects and remarkable economic and social benefits.

Description

Technical Field

[0001] The invention relates to the field of large generator manufacturing, and in particular to a method for manufacturing a stator wire bar with an inner-circle and outer-square main insulation structure. Background Art

[0002] The performance of stator bars determines the rated voltage of large generators, and the improvement of their electrical performance has always been a problem that plagues the insulation design of stator bars. With the increase in the rated voltage of units, the development of stator bars with rated voltage levels of 30kV and above has become a bottleneck in the development of the power generation industry.

[0003] The traditional method is to improve the performance of the stator bar by improving the performance of the main insulation material. However, the main insulation material system is very mature, the update and iteration speed is very slow, and the room for improvement is very limited. It is difficult to significantly improve the performance of the stator bar by upgrading the main insulation material.

[0004] Another method is to improve the performance of the stator bar by improving the insulation structure, including increasing the thickness of the main insulation, increasing the radius of the lead corners, and using a composite main insulation structure. These methods are all based on traditional designs. The internal lead wires use a rectangular structure composed of multiple strands of rectangular copper flat wires, and the field strength stress is concentrated at the corners, so there is limited room for improvement. Therefore, it is urgent to make new breakthroughs in the design of the stator bar insulation structure to meet the urgent need to increase the rated voltage of the generator. Summary of the invention

[0005] In view of this, the purpose of the present invention is to develop a method for manufacturing a stator wire bar with an inner circle and outer square main insulation structure. The inner circle and outer square stator wire bar has the advantages of clear principle, novel structure, convenient process, easy design and manufacturing, and can significantly improve the rated voltage level of large generators. The technical solution of the present invention is:

[0006] A method for manufacturing a stator wire bar with an inner circle and outer square main insulation structure, wherein the stator wire bar is composed of an inner round lead and an outer inner circle and outer square main insulation; the round lead is composed of a plurality of round strands, a covering and an equipotential layer, the plurality of round strands are evenly distributed in the round lead, the round strands are closely attached to each other, the gaps outside the round strands are completely filled with the covering, the equipotential layer is located outside the round lead, and wraps all the round strands and the covering; the inner circle and outer square main insulation is composed of a mica tape and a corner filler, the corner filler is formed by hot pressing, and the raw materials used are consistent with the mica tape material for the main insulation.

[0007] In the manufacturing method of the stator wire rod of the above-mentioned inner circle and outer square main insulation structure, when the material of the inner circle and outer square main insulation is high-resin mica tape, a high-resin molding manufacturing process is adopted; when the material of the inner circle and outer square main insulation is low-resin mica tape, a low-resin VPI manufacturing process is adopted.

[0008] In the manufacturing method of the stator wire bar with the above-mentioned inner circle and outer square main insulation structure, the material of the circular stranded wire is composed of a circular metal conductor and strand insulation, and the circular metal conductor adopts a solid conductor or a hollow conductor according to the design; the manufacturing method of the circular stranded wire adopts a twisting and positioning method, and the slot and end positions of the stator wire bar are uniformly twisted to a specified angle according to the design requirements, and then hot-pressed and glued into shape.

[0009] In the manufacturing method of the stator wire bar of the inner circle and outer square main insulation structure, the manufacturing method of the equipotential layer is to first apply low-resistance anti-corona paint and then wrap it with low-resistance anti-corona tape.

[0010] In the manufacturing method of the stator wire bar with the above-mentioned inner circle and outer square main insulation structure, the inner circle and outer square main insulation is wrapped with a specified number of layers of mica tape according to design requirements, fixed corner fillers are installed at the four corners, and then the remaining number of layers of mica tape are wrapped according to the overall thickness.

[0011] Technical Effects

[0012] The present invention can achieve the following technical effects:

[0013] 1. Effectively improve the rated voltage level of large generator stator bars. By changing the shape of the lead wire from the traditional rectangular structure to a circular structure, the fillet radius is greatly increased, and the maximum internal electric field is greatly reduced, which can effectively improve the dielectric loss partial discharge, breakdown voltage and electrical aging life of the stator bar, ensuring stable operation at a higher rated voltage.

[0014] 2. Reduced the manufacturing process difficulty of strand transposition. The traditional stator wire rod copper flat wire adopts the braiding transposition method. Due to uneven force, it is necessary to add strand insulation pads under the transposed copper flat wires to prevent short circuits between strands. The present invention adopts a circular strand uniform twisting transposition method. The strand transposition shape is symmetrical and the force is uniform. There is no need for braiding transposition operation, nor is there any need to add strand insulation material. The insulation structure of the strand transposition is simplified and the process difficulty of the strand transposition is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the stator bar cross-section of the main insulation structure with an inner circle and an outer square.

[0016] Figure 2 It is a three-dimensional perspective view of the stator bar of the main insulation structure with an inner circle and an outer square.

[0017] Markings in the figure: 1- stator bar, 2- round lead, 3- inner circle and outer square main insulation, 4- round strand, 5- covering, 6- equipotential layer, 7- corner filler, 8- round metal conductor, 9- strand insulation. DETAILED DESCRIPTION

[0018] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present application.

[0019] Specific implementation method 1: Figure 1 As shown, the structure of the stator bar 1 of the inner circle outer square main insulation structure is composed of an inner round lead 2 and an outer inner circle outer square main insulation 3;

[0020] In this embodiment, the composition structure of the stator bar of the inner circle and outer square main insulation structure is explained, and the specific characteristics of the lead wire and the main insulation structure are clarified.

[0021] Specific implementation method 2: Figure 1 As shown, the structure of the circular lead 2 is composed of multiple circular strands 4, a covering 5 and an equipotential layer 6. The multiple circular strands 4 are evenly distributed in the circular lead 2. The circular strands 4 are tightly attached to each other. The gaps outside the circular strands 4 are completely filled with the covering 5. The equipotential layer 6 is located on the outside of the circular lead 2, wrapping all the circular strands and the covering 5.

[0022] In this embodiment, the composition and internal structure of the circular lead are explained. The circular strands are closely arranged to ensure a compact structure and a high slot fill rate. The covering material is used to fill the gaps between the circular strands to ensure that the lead structure is firm and to avoid undesirable conditions such as air gaps. The role of the equipotential layer is to ensure that the potential of the entire lead is consistent.

[0023] Specific implementation method three: Figure 1 As shown, the structure of the inner circle and outer square main insulation 3 is composed of mica tape and corner filler 7. The corner filler 7 is formed by hot pressing, and the raw materials used are consistent with the mica tape material used for the main insulation.

[0024] In this embodiment, the consistency of the two main insulating materials is to ensure that no field strength distortion is generated at the interface between different materials to reduce the main insulation performance.

[0025] Specific implementation method four: Figure 1 As shown, when the material of the inner circle and outer square main insulation 3 is high-resin mica tape, a high-resin molding manufacturing process is adopted; when the material of the inner circle and outer square main insulation 3 is low-resin mica tape, a low-resin VPI manufacturing process is adopted.

[0026] In this embodiment, the method can select the manufacturing process according to different types of mica tapes, and has good versatility.

[0027] Specific implementation method five: Figure 2As shown, the material of the round strand 4 is composed of a round metal conductor 8 and a strand insulation 9. The round metal conductor 8 is a solid conductor or a hollow conductor according to the design. The round strand 4 is manufactured by a twisting method. According to the design requirements, the stator wire bar 1 is uniformly twisted at a specified angle at the slot and end position, and then hot-pressed and glued into shape.

[0028] In this embodiment, the round strands adopt twisting and switching technology, which simplifies the difficulty of process manufacturing. The round metal wire can be in the form of all solid, hollow and solid combinations, and can be used for external cooling or internal cooling, with good versatility.

[0029] Specific implementation method six: Figure 1 As shown, the manufacturing method of the equipotential layer 6 is to first apply low-resistance anti-corona paint and then wrap it with a low-resistance anti-corona tape.

[0030] In this embodiment, the combination of painting and taping ensures the stability of the equipotential layer performance.

[0031] Specific implementation method seven: Figure 1 As shown, the manufacturing method of the inner circle and outer square main insulation 3 is to wrap a specified number of layers of mica tape according to design requirements, install fixed corner fillers 7 at the four corners, and then wrap the remaining number of layers of mica tape according to the overall thickness.

[0032] In this embodiment, the purpose of the corner filler is to fill the insufficient main insulating material at the corner. Since the electric field strength at the corner is relatively low, the inconsistency of the main insulating material at this location has a smaller impact on the maximum electric field.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the above embodiments, it should be clear to those skilled in the art that the technical solutions described in the above embodiments may be modified, or some or all of the technical features therein may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for manufacturing a stator bar with an inner-circle and outer-square main insulation structure, characterized by: The stator wire bar (1) is composed of an internal circular lead wire (2) and an external inner-circle-outer-square main insulation (3); the circular lead wire (2) is composed of a plurality of circular strands (4), a covering (5) and an equipotential layer (6); the plurality of circular strands (4) are evenly distributed in the circular lead wire (2); the circular strands (4) are closely attached to each other; the gaps outside the circular strands (4) are completely filled with the covering (5); the equipotential layer (6) is located outside the circular lead wire (2) and wraps all the circular strands and the covering (5); the inner-circle-outer-square main insulation (3) is composed of a mica tape and a corner filler (7); the corner filler (7) is formed by hot pressing, and the raw materials used are consistent with the mica tape material used for the main insulation.

2. The method for manufacturing a stator bar with an inner-circle and outer-square main insulation structure according to claim 1, characterized in that: When the material of the inner circle outer square main insulation (3) is high-resin mica tape, a high-resin molding manufacturing process is adopted; when the material of the inner circle outer square main insulation (3) is low-resin mica tape, a low-resin VPI manufacturing process is adopted.

3. The method for manufacturing a stator bar with an inner-circle and outer-square main insulation structure according to claim 1, characterized in that: The material of the circular strand (4) is composed of a circular metal conductor (8) and strand insulation (9), and the circular metal conductor (8) is a solid conductor or a hollow conductor according to the design. The manufacturing method of the circular strand (4) adopts a twisting and positioning method, and according to the design requirements, the slot and end positions of the stator wire bar (1) are uniformly twisted to a specified angle, and then hot-pressed and glued into shape.

4. The method for manufacturing a stator bar with an inner-circle and outer-square main insulation structure according to claim 1, characterized in that: The manufacturing method of the equipotential layer (6) is to first apply low-resistance anti-corona paint and then wrap it with a low-resistance anti-corona tape.

5. The method for manufacturing a stator bar with an inner-circle and outer-square main insulation structure according to claim 1, characterized in that: The inner circle and outer square main insulation (3) is wrapped with a specified number of layers of mica tape according to design requirements, fixed corner fillers (7) are installed at the four corners, and then the remaining number of layers of mica tape are wrapped according to the overall thickness.

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