A spherical joint connecting structure and assembling method for water-cooled stator bars

Abstract

The application relates to a spherical joint connecting structure and an assembling method for water internal cooling stator bars, and belongs to the technical field of water internal cooling generators, which comprises a stator bar, a coil water box and a spherical joint structure, the strand end of the stator bar is connected with the coil water box, and the spherical joint structure is fixed with the coil water box to form a cooling water passage; two sides of the outer periphery of the spherical joint structure are symmetrically provided with connecting copper bars, the inner side of the connecting copper bar in contact with the spherical joint structure is provided with a spherical arc surface matched with the outer surface of the spherical joint structure, the inner ring diameter of the spherical arc surface is smaller than the outer diameter of the spherical joint structure, and an interference fit is formed; the connecting copper bars are mechanically clamped and fixed on the two sides of the spherical joint structure through penetrating bolts, mechanical fastening of electrical connection and water-electric separation are realized, the application is favorable for realizing water-electric separation and ensuring the reliability of the electrical connection of the upper and lower stator bars, and electrical connection failure caused by load change, nose end vibration and other factors is avoided.

Description

Technical Field

[0001] This invention relates to the stator bar nose end structure and the upper and lower bar connection structure of a generator, which is used to solve the problem of easy solder joint failure when connecting the upper and lower bar solder joints, and belongs to the technical field of water-cooled generators. Background Technology

[0002] The stator winding ends of large water-cooled generators are critical areas for electromagnetic energy conversion and also concentration points of mechanical vibration and electrical stress. The stator bar nose, as the core node connecting the upper and lower layers of bars to form a complete electrical circuit, directly affects the safe and stable operation of the generator set due to the reliability of its connection structure.

[0003] In existing technologies, the stator bar nose end typically employs an integrated water and electricity connection structure. Specifically, the bar strands are brazed to the coil water box at the nose end to form a cooling water passage, while the electrical connection between the upper and lower bar layers is mostly achieved by soldering tin-plated soft copper wire. That is, the nose ends of the upper and lower bar layers are soldered together with tin-plated soft copper wire to form a current loop, which is then secured with conductive bus bolts.

[0004] However, the above-mentioned solder joint structure has inherent defects: First, the solder material itself has low mechanical strength and limited fatigue resistance, and is prone to micro-cracks due to the electromagnetic force at the end during long-term operation; Second, the solder joint is sensitive to vibration, and the welding quality is highly dependent on the consistency of the process, making it difficult to ensure 100% reliability; Third, the solder joint lacks self-adjustment capability, and when there is an error in the wire rod embedding, forced welding will cause stress concentration inside the wire rod.

[0005] In recent years, with the increasing demands of the power grid for the flexible operation of thermal power units, generator units have frequently undergone unsteady operations such as deep peak shaving and rapid load changes, which has significantly exacerbated stator end vibration. The mechanical vibration caused by frequent load changes, combined with thermal cycling stress, makes traditional solder joints more prone to fatigue cracking or even solder joint failure. Once the nose-end electrical connection fails, it will not only cause local overheating but may also trigger grounding faults, seriously threatening generator safety.

[0006] Therefore, there is an urgent need for a new type of stator bar nose connection structure that can ensure the sealing of the cooling water passage while achieving mechanical reinforcement and adaptive adjustment capabilities of the electrical connection part, thereby fundamentally solving the reliability problem of traditional solder joints under vibration conditions. Summary of the Invention

[0007] The purpose of this invention is to provide a spherical joint connection structure and assembly method for water-cooled stator bars. The novel stator bar nose end water-electric connection structure achieves water and circuit separation while ensuring the reliability of the electrical connection between the upper and lower bars, avoiding electrical connection failures caused by load changes, nose end vibration, and other factors.

[0008] To achieve the above objectives, the present invention provides a spherical connector connection structure for water-cooled stator bars, comprising stator bars, a coil water box, and a spherical connector structure. The ends of the stator bars are connected to the coil water box, and the spherical connector structure and the coil water box are fixedly connected to form a cooling water passage. Connecting copper busbars are symmetrically arranged on both sides of the outer periphery of the spherical connector structure. The inner surface of the connecting copper busbars in contact with the spherical connector structure has a spherical arc surface adapted to the outer surface of the spherical connector structure. The inner diameter of the spherical arc surface is smaller than the outer diameter of the spherical connector structure, forming an interference fit to achieve electrical connection. The connecting copper busbars are mechanically clamped and fixed to both sides of the spherical connector structure by through bolts, achieving mechanical fastening of the electrical connection and separation of water and electricity.

[0009] Preferably, the spherical connector structure and the spherical surface of the connecting copper busbar, as well as the spacing between the two spherical surfaces of the connecting copper busbar, are optional, so that the connecting copper busbar can be angularly adjusted relative to the spherical connector structure in three-dimensional space to adapt to assembly errors.

[0010] Preferably, the spherical connector structure and the coil water box are precisely positioned by positioning pins and then fixedly connected by brazing.

[0011] Preferably, the spherical joint structure is sealed to the insulated water pipe by a clamp.

[0012] Preferably, the connecting copper busbar is provided with mounting holes for the bolt to pass through, and the axial clamping force generated by the bolt when tightening causes the spherical arc surface to form a surface contact and mechanical anti-loosening structure with the outer surface of the spherical joint structure.

[0013] Preferably, one end of the coil water box is connected to the end of the stator bar strand by brazing, and the other end is provided with a positioning pin that matches the inner hole of the spherical joint structure.

[0014] Preferably, the connecting copper busbar is configured with various length specifications according to the actual assembly distance between the noses of the upper and lower wire rods.

[0015] The technical solution of the present invention also provides an assembly method for a spherical joint connection structure for water-cooled stator bars, comprising the following steps:

[0016] The stator wire strands are brazed and sealed to the coil water box, and the coil water box is fixed to the ball joint structure by positioning and then brazed to form a complete cooling water passage. Then the insulated water pipe is connected to the water outlet of the ball joint structure. Measure the actual assembly distance between the noses of the upper and lower bar wires, and select the connecting copper busbar with a length specification that matches the distance. The connecting copper busbar has a spherical arc surface with an inner diameter smaller than the outer diameter of the spherical joint structure. Align the spherical arc surface of the selected connecting copper busbar with both sides of the spherical joint structure of the upper and lower wire rods, and use the bolts to pass through the mounting holes on the connecting copper busbar for pre-tightening and positioning; Under pre-tightened conditions, the angle and position of the connecting copper busbars are adjusted using the multi-degree-of-freedom characteristics of spherical mating until a stress-free docking state is achieved. Tighten the bolts so that the connecting copper busbar is subjected to interference fit mechanical compression to produce elastic deformation on the surface of the spherical joint structure, thereby achieving electrical connection fixation and mechanical clamping to prevent loosening of the upper and lower wire rods.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention replaces traditional soldering with a mechanical interference fit, significantly improving the reliability and mechanical strength of the electrical connection. The contact surface between the connecting copper busbar and the ball joint adopts a matching spherical arc surface design, with the inner diameter of the spherical arc surface slightly smaller than the outer diameter of the ball joint. During assembly, the mechanical compression generated by bolt tightening causes controllable elastic deformation on the surface of the ball joint, thereby achieving 100% electrical contact area and effectively reducing contact resistance. At the same time, the mechanical clamping connection method has excellent fatigue resistance and can withstand end vibration and impact loads caused by frequent load changes, fundamentally solving the problems of easy desoldering and poor vibration resistance of traditional solder joints.

[0018] This invention employs a spherical contact surface combined with a selectable length connecting copper busbar, achieving multi-directional adaptive adjustment capability for the electrical connection. Due to the multi-degree-of-freedom nature of the spherical fit, the connecting copper busbar can be finely adjusted in three-dimensional space relative to the spherical connector. Simultaneously, by selecting a copper busbar length that matches the actual assembly distance, positional errors generated during the wire rod embedding process can be effectively compensated, avoiding stress concentration in the wire rod caused by forced connection. This significantly improves the convenience of in-factory assembly and process adaptability, ensuring that the electrical connection is installed under stress-free conditions.

[0019] This invention achieves complete separation of the water circuit and the electrical circuit, improving the overall reliability of the stator bar nose end at the system level. The cooling water passage is formed by brazing a ball joint, coil water box, and bar strands into an independent sealed structure, while the electrical connection is achieved through a purely mechanical means, with the two not interfering with each other. This structure not only eliminates the impact of water leakage on electrical insulation, but also gives the electrical connection parts long-term stable mechanical holding force and anti-loosening ability, making it particularly suitable for the operating environment of frequent load changes and increased end vibration under the flexible operation conditions of thermal power units, ensuring the long-term safe and stable operation of the generator. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the overall structure of a spherical joint connection structure and assembly method for water-cooled stator bars according to the present invention. Figure 2 This is a schematic diagram of the original bar connector in the prior art; Figure 3 This is a schematic diagram of the bar joint structure in the ball joint connection structure and assembly method for water-cooled stator bars of the present invention. Figure 4 This is a schematic diagram of the electrical connection between the upper and lower layers of rods in the existing technology; Figure 5 This is a schematic diagram of the electrical connection between the upper and lower layers of stator bars in a spherical joint connection structure and assembly method for water-cooled stator bars according to the present invention.

[0021] Reference numerals: 1. Coil water box; 2. Upper layer bar; 3. Lower layer bar; 4. Spherical joint structure; 5. Insulated water pipe; 6. Connecting copper busbar; 7. Brazing; 8. Tinned soft copper wire; 9. Conductive busbar; 10. Bolt; 11. Conductive busbar bolt. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] This invention discloses a spherical joint connection structure and assembly method for water-cooled stator bars. The stator bar nose end structure adopts a spherical joint structure 4 to achieve the separation of water circuit and electrical circuit.

[0024] like Figure 1As shown, the stator bar strands are connected to the coil water box 1 at the nose end by brazing 7. The coil water box 1 is then precisely positioned by a positioning pin and a ball joint, and then fixed by brazing 7, thus forming a complete cooling water passage. The cooling water is connected to the insulated water inlet pipe 5 through the ball joint. The electrical connection between the upper bar 2 and the lower bar 3 is achieved by mechanical clamping and fixing through connecting copper busbars 6 and bolts 10. Connecting copper busbars 6 are respectively provided on both sides of the outer periphery of the ball joints of the upper bar 2 and the lower bar 3. The corresponding connecting copper busbars 6 of the upper and lower layers are fastened through by bolts 10, clamping the ball joints of the upper bar 2 and the lower bar 3 in the middle to form an electrical connection.

[0025] like Figure 2 and Figure 3 As shown, without changing the original cross-sectional dimensions of the wire rod and the connection method of the coil water box 1, the present invention changes the original wire rod connector to a ball connector. The ball connector and the coil water box 1 still maintain the brazing 7 connection method, but the structural form of the external electrical connection is changed.

[0026] like Figure 4 As shown, the original upper and lower layer electrical connections were made by soldering tin-plated soft copper wire 8. After soldering, the tin-plated soft copper wire 8 was fixed by conductive busbar 9 and conductive busbar bolt 11. This structure is susceptible to breakage due to vibration and heat at the end of the wire rod.

[0027] To avoid the aforementioned problems, this invention employs mechanical clamping instead of soldering. The portion of the connecting copper busbar 6 that contacts the spherical connector structure 4 is machined into a spherical arc surface adapted to the outer surface of the spherical connector, and the inner diameter of this spherical contact surface is smaller than the outer diameter of the spherical connector, forming an interference fit structure. When the connecting copper busbar 6 is fastened and clamped to both sides of the spherical connector by bolts 10, the connecting copper busbar 6 causes elastic deformation of the spherical connector surface through mechanical compression, thereby achieving 100% electrical contact area and forming a reliable mechanical anti-loosening structure, significantly enhancing the impact resistance of the wire nose end under complex working conditions.

[0028] To address the error issues that arise during in-plant assembly, this invention achieves multi-directional adaptive adjustment through a spherical contact surface and an adjustable connecting copper busbar 6. Because the contact surface between the connecting copper busbar 6 and the spherical connector is spherical, this spherical fit allows the connecting copper busbar 6 to adjust its angle relative to the spherical connector in three-dimensional space. Furthermore, the connecting copper busbar 6 is designed with various length specifications based on the actual assembly distance between the noses of the upper wire rod 2 and the lower wire rod 3. During assembly, the appropriate length of the connecting copper busbar 6 is selected based on the actual measured dimensions on site. The multi-degree-of-freedom characteristics of the spherical contact are used to adjust the installation angle, eliminating the problem of forced nose alignment caused by wire rod embedding errors and avoiding stress concentration in the wire rods due to forced connection.

[0029] In the specific assembly process, the stator wire strands are first brazed and sealed to the coil water box 1, and the coil water box 1 is fixed to the ball joint by positioning pins and brazing 7 to ensure the water system's airtightness. Then, the electrical connection is assembled. The spherical contact surfaces of the selected connecting copper busbar 6 are aligned and fitted against both sides of the ball joint. Bolts 10 are passed through the mounting holes on the connecting copper busbar 6 for pre-tightening and positioning. During this process, the angle and position of the connecting copper busbar 6 are adjusted using the spherical fit until a stress-free state is reached. Finally, the bolts 10 are tightened to simultaneously complete the mechanical fixing and electrical connection.

[0030] Through the above structural design and assembly method, this invention improves the reliability of the stator bar nose-end water-electric connection structure. The separation design of the water and electrical circuits ensures the independence and sealing of the cooling water passage, while the mechanical interference fit and bolt 10 fastening method used in the electrical connection can withstand end vibrations caused by frequent load changes, fundamentally solving the defect of easy desoldering of traditional tin-welded joints. At the same time, the multi-directional adjustable characteristics of the spherical contact surface, combined with the selectable length of the connecting copper busbar 6, effectively compensates for assembly errors, avoids stress concentration in the bar, and ensures the stability and safety of the end electrical connection of the generator during long-term operation.

[0031] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A spherical joint connection structure for water-cooled stator bars, characterized in that, The stator includes stator bars, a coil water box (1), and a spherical connector structure (4). The ends of the stator bars are connected to the coil water box (1), and one end of the spherical connector structure (4) is fixed to the coil water box (1) to form a cooling water passage. Connecting copper busbars (6) are symmetrically arranged on both sides of the outer periphery of the spherical connector structure (4). The inner side of the connecting copper busbar (6) that contacts the spherical connector structure (4) is provided with a spherical arc surface that is adapted to the outer surface of the spherical connector structure (4). The inner diameter of the spherical arc surface is smaller than the outer diameter of the spherical connector structure (4) to form an interference fit. The connecting copper busbar (6) is mechanically clamped and fixed on both sides of the spherical connector structure (4) by through bolts (10) to realize the mechanical fastening of electrical connection and water-electricity separation.

2. The spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, The spherical joint structure (4) and the spherical surface of the connecting copper busbar (6) allow the connecting copper busbar (6) to be angularly adjusted relative to the spherical joint structure (4) in three-dimensional space to adapt to assembly errors.

3. The spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, The spherical connector structure (4) and the coil water box (1) are precisely positioned by positioning pins and then fixedly connected by brazing (7).

4. A spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, The spherical joint structure (4) is connected to the insulated water pipe (5) by a clamp seal.

5. A spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, The connecting copper busbar (6) is provided with mounting holes for the bolt (10) to pass through. The axial clamping force generated by the bolt (10) when tightening causes the spherical arc surface to form a surface contact and mechanical anti-loosening structure with the outer surface of the spherical joint structure (4).

6. A spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, One end of the coil water box (1) is sealed to the end of the stator bar strand by the brazing (7), and the other end is provided with a positioning pin that matches the inner hole of the ball joint structure (4).

7. A spherical joint connection structure for water-cooled stator bars according to claim 1, characterized in that, The connecting copper busbar (6) has various length specifications depending on the actual assembly distance between the nose ends of the upper layer wire rod (2) and the lower layer wire rod (3).

8. An assembly method for a spherical joint connection structure for water-cooled stator bars according to any one of claims 1-7, characterized in that, Includes the following steps: The stator wire strands are brazed (7) to seal the connection with the coil water box (1), and the coil water box (1) is fixed to the ball joint structure (4) by the brazing (7) after positioning to form a complete cooling water passage. Then the insulated water pipe (5) is connected to the water outlet of the ball joint structure (4). Measure the actual assembly distance between the nose ends of the upper layer bar (2) and the lower layer bar (3), and select the connecting copper busbar (6) with a length specification that matches the distance. The connecting copper busbar (6) is provided with a spherical arc surface with an inner diameter smaller than the outer diameter of the spherical joint structure (4). Align the spherical arc surface of the selected connecting copper busbar (6) with the two sides of the spherical joint structure (4) of the upper layer bar (2) and the lower layer bar (3), and use the bolt (10) to pass through the mounting hole on the connecting copper busbar (6) for pre-tightening and positioning. Under pre-tightened conditions, the angle and position of the connecting copper busbar (6) are adjusted using the multi-degree-of-freedom characteristics of the spherical fit until a stress-free docking state is achieved; Tighten the bolts (10) so that the connecting copper busbar (6) can be mechanically squeezed by interference fit to produce elastic deformation on the surface of the spherical joint structure (4), thereby realizing the electrical connection fixation and mechanical clamping and anti-loosening of the upper bar (2) and the lower bar (3).

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