Separating type voltage-sharing ball of transformer bushing and manufacturing method of separating type voltage-sharing ball

Abstract

The invention belongs to the technical field of insulation of high-voltage power equipment, and relates to a separated voltage-sharing ball for a transformer bushing and a manufacturing method of the separated voltage-sharing ball. Comprising a pressure-equalizing ball body and an end part, the pressure equalizing ball main body is connected with the end part through a connecting structure; wherein the connecting structure is configured to enable the end part to be fixedly separated from the pressure equalizing ball main body in space, so that the central axis of the end part and the central axis of the pressure equalizing ball main body form a non-coaxial spatial position relationship; and therefore, an electric field buffer structure is formed in the junction area of the voltage-sharing ball main body and the end part. According to the invention, the technical problems of high partial discharge risk and non-uniform electric field distribution are effectively solved, and the safety margin and the operation life of the transformer bushing under a high-voltage working condition are remarkably improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-voltage power equipment insulation, and relates to a transformer bushing split type grading sphere and a manufacturing method thereof. BACKGROUND

[0002] A transformer is a key device in a power system, and its bushing is an important element for leading out and supporting insulation as a conductor, which bears complex electric field distribution under high-voltage and extra-high-voltage operating conditions. The bushing is usually divided into an air end and an oil end, and the electric field distribution of the tail of the oil end bushing is particularly complex. If the electric field distribution is uneven, local electric field concentration is easily generated in the oil end, which further causes problems such as partial discharge and oil gap breakdown, and seriously affects the safe operation of the transformer.

[0003] In order to improve the electric field distribution of the bushing tail in oil, a grading device is usually arranged at the end of the bushing in engineering, and the grading sphere is a relatively common one. The grading sphere changes the electric field boundary conditions to make the electric field line distribution tend to be uniform, thereby reducing the local electric field strength. However, the existing grading spheres are mostly single spherical structures, and their grading effect in oil is limited. The existing grading sphere structure still has the following deficiencies. First, the grading effect is limited, and under ultra-high-voltage and extra-high-voltage operating conditions, the existing spherical structure cannot significantly improve the electric field distribution, and local electric field concentration still exists, which increases the risk of insulation breakdown and partial discharge. Second, the electric field distribution is uneven, and the traditional grading sphere mostly adopts a single spherical or approximately spherical structure, and its electric field control ability in different directions is different, which makes it difficult to comprehensively optimize the circumferential and spatial electric field of the bushing. Third, the operation reliability is limited, and during long-term operation in oil, local electric field distortion easily accelerates the aging of oil-paper insulation, and reduces the overall operation life of the bushing.

[0004] Therefore, the transformer bushing tail grading sphere in the prior art still has problems such as unsatisfactory grading effect, uneven electric field distribution, and easy degradation of insulation performance when operating in oil. There is an urgent need for a new type of grading sphere structure to improve the electric field environment of the oil end bushing tail and improve the safety and reliability of the transformer under high-voltage operating conditions. SUMMARY

[0005] In order to solve the problems of unsatisfactory grading effect, uneven electric field distribution, and insufficient operation reliability of the transformer bushing tail grading sphere in the prior art when operating in oil, the present application provides a transformer bushing split type grading sphere and a manufacturing method thereof to improve the electric field distribution of the oil end and improve the insulation performance and operation safety of the bushing.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solutions: In a first aspect, the present invention provides a transformer bushing-separable equalizing ball, comprising an equalizing ball body and an end portion; the equalizing ball body and the end portion are connected by a connecting structure. The connection structure is configured such that the end is spatially fixedly separated from the equalizing sphere body, such that the central axis of the end and the central axis of the equalizing sphere body form a non-coaxial spatial positional relationship, thereby forming an electric field buffer structure in the boundary region between the equalizing sphere body and the end.

[0007] Preferably, the spatial positional relationship is a translational relationship; the connection structure includes a connector with a radial offset, and the end is fixed to the equalizing ball body through the connector, such that the central axis of the end is parallel to but deviates from the central axis of the equalizing ball body.

[0008] Preferably, the radial translation distance of the end relative to the equalizing ball body is 5mm to 50mm.

[0009] Preferably, the spatial positional relationship is a rotational relationship; the connection structure is configured such that the mounting plane at the end is tilted at a preset angle relative to the normal direction of the central axis of the equalizing ball body.

[0010] Preferably, the preset angle is in the range of 5° to 30°.

[0011] Preferably, the equalizing ball body and the end are spatially separated by the connecting structure to form an oil gap filled with insulating oil.

[0012] Preferably, both the equalizing ball body and the end are made of conductive metal material.

[0013] Preferably, the connection structure is a detachable connection structure.

[0014] Preferably, the surfaces of the equalizing ball body and the end are smooth surfaces.

[0015] Secondly, the present invention provides a method for manufacturing a transformer bushing-separable equalizing sphere, comprising the following steps: S1. Based on the rated voltage level and insulation requirements of the transformer bushing, the target spatial positional relationship parameters of the end relative to the equalizing sphere body are determined through finite element electric field simulation; the target spatial positional relationship parameters include radial translation distance or rotation angle. S2. Manufacture the equalizing ball body, the end portion, and the connection structure that conforms to the target spatial positional relationship parameters; S3. The end is fixedly connected to the equalizing ball body through the connection structure, so that the central axis of the end and the central axis of the equalizing ball body form the target spatial position relationship.

[0016] Compared with the prior art, the present invention has the following beneficial effects: By setting the ends and the main body as separate structures that are not coaxial in space, the bottleneck of electric field concentration caused by geometric continuity at the junction of the traditional integrated equalizing sphere is broken. This structure changes the original electric field path, forms an electric field buffer zone, makes the equipotential surface distribution more gentle and the electric field lines more uniform, effectively solves the technical problems of high risk of partial discharge and uneven electric field distribution, and significantly improves the safety margin and service life of transformer bushings under high voltage conditions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a transformer bushing-separable equalizing ball according to the present invention; Figure 2 This is a diagram showing the equipotential surface distribution of the electric field in a traditional equal-pressure sphere. Figure 3 This is a diagram showing the distribution of the equipotential surface of the electric field of the equal-pressure sphere of the present invention.

[0019] The components are: 1. the main body of the equalizing ball; 2. the end; and 3. the connecting parts. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0021] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0022] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0023] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0025] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0026] The present invention will now be described in further detail with reference to the accompanying drawings: The first objective of this invention is to provide a transformer bushing-separable equalizing sphere, such as... Figure 1 As shown, it includes a pressure equalization ball body 1 and an end 2; the pressure equalization ball body 1 and the end 2 are connected by a connecting structure; The connection structure is configured such that the end 2 is spatially fixedly separated from the equalizing ball body 1, such that the central axis of the end 2 and the central axis of the equalizing ball body 1 form a non-coaxial spatial positional relationship, thereby forming an electric field buffer structure in the boundary region between the equalizing ball body 1 and the end 2.

[0027] The equalizing sphere body 1 is the main load-bearing part of the equalizing sphere, usually installed at the end of the transformer bushing guide rod to expand the equipotential surface of the conductor and reduce the initial electric field strength. Its shape can be hemispherical, ellipsoidal, or other rotating structures that facilitate electric field diffusion, and the specific shape is adapted according to the internal space of the bushing and the electric field distribution requirements. The end 2 is set at the end of the equalizing sphere away from the opening side or close to the grounding cylinder wall. Its main function is to redistribute and guide the electric field in the edge area to prevent the electric field lines from densely pointing towards the metal wall.

[0028] The connecting structure is used to achieve mechanical connection and electrical conduction between the main body 1 and the end 2 of the equalizing sphere. Its key feature is that it can maintain the relative fixed position of the two in space, while allowing their axes to be non-coaxial. The connecting structure must have sufficient mechanical strength to withstand vibration and thermal expansion and contraction stress during operation, while ensuring good electrical conductivity to ensure that the entire equalizing sphere is at the same potential.

[0029] "Non-coaxial spatial relationship" refers to the fact that the central axis of end 2 no longer coincides with or extends collinearly with the central axis of the equipotential sphere body 1, but is offset or tilted in space. This non-coaxial arrangement breaks the design inertia of the traditional structure where end 2 must extend symmetrically along the main axis, allowing the position and orientation of end 2 to be adjusted independently, thereby actively intervening in the electric field distribution path of the interface region. For example, when end 2 undergoes radial translation, the original continuous transition region is interrupted, forming a gap region with a certain width; when end 2 undergoes angular rotation, its orientation towards the grounding body changes, affecting the direction of the local potential gradient. All of the above changes can make the equipotential surface tend to be gentler, and the electric field lines are distributed more evenly. The electric field buffer structure is the physical and electrical interface naturally formed by the above non-coaxial arrangement, located in the interface region between the equipotential sphere body 1 and end 2. This structure does not rely on additional dielectric layers or complex components, but creates a transition region for electric field redistribution through structural separation itself. In this region, electric field lines that might otherwise be concentrated are forced to detour or disperse, and the peak field strength is reduced. The existence of this buffer structure is equivalent to introducing a "soft transition" mechanism in the high field strength region, which helps to reduce the partial discharge initiation voltage and improve the safety margin of the insulation system.

[0030] This invention eliminates the unavoidable abrupt changes in geometric curvature inherent in a monolithic structure by spatially fixing and separating the end portion 2 from the equipotential sphere body 1 in a non-coaxial arrangement. This eliminates sharp transitions in the junction area, effectively solving the problem of electric field concentration. Because the central axis of the end portion 2 is spatially misaligned relative to the equipotential sphere body 1, the electric field lines are forced to make smooth turns in the junction area instead of densely accumulating, resulting in a significant decrease in local field strength and making the equipotential surfaces more parallel to the grounding cylinder wall. Therefore, it achieves the technical effects of improving the uniformity of the electric field distribution in oil, suppressing partial discharge, and enhancing insulation reliability. Furthermore, it provides a structural basis for subsequent parameterized optimization based on voltage levels and is applicable to various high-voltage and ultra-high-voltage transformer bushing scenarios.

[0031] The spatial relationship is a translational one; the connection structure includes a connector 3 with a radial offset, and the end portion 2 is fixed to the equalizing sphere body 1 through the connector 3, such that the central axis of the end portion 2 is parallel to but deviates from the central axis of the equalizing sphere body 1. By introducing the connector 3 with radial offset characteristics, the end portion 2 is spatially arranged relative to the equalizing sphere body 1 in a translational manner, thereby breaking the geometric continuity and symmetry constraints between the end portion 2 and the body in traditional integral equalizing spheres, so that the two form a stable and controllable separation state in space, thereby optimizing the electric field distribution characteristics of the interface region.

[0032] like Figure 2 As shown, in the traditional structure, the equipotential surface is severely bent and twisted between the equalizing sphere and the grounding cylinder wall, indicating that the electric field distribution is extremely uneven. The large angle between the equalizing surface and the cylinder wall leads to a high concentration of electric field lines in certain areas, posing a high risk of partial discharge and insulation breakdown. Figure 3 This clearly demonstrates that after optimization using the method described in this invention (forming a non-coaxial, separate structure by independently designing the chamfer, width, and rotation angle of end 2 relative to the main body), the equipotential surfaces become straight, uniformly spaced, and nearly parallel to the cylinder wall. This change signifies a fundamental improvement in the electric field distribution, allowing the electric field lines to diverge uniformly and effectively eliminating local field strength peaks. This proves that the voltage equalization sphere structure of this invention can significantly optimize the voltage equalization effect, suppress partial discharge, and thus greatly improve the insulation reliability and operational safety of transformer bushings.

[0033] For example, the radial offset of connector 3 can be parametrically designed according to actual working conditions, and its size range can be flexibly selected between 5mm and 50mm. The specific value is determined comprehensively based on factors such as the rated voltage level of the transformer bushing, the distance of the insulating oil gap, and the spatial layout of the grounding cylinder. In addition, the cross-sectional shape of connector 3 can be circular, rectangular, or polygonal, and its length and rigidity must meet the mechanical load-bearing requirements to prevent positional displacement caused by vibration or thermal expansion and contraction during operation.

[0034] The spatial relationship is a rotational one; the connection structure is configured such that the mounting plane of the end 2 is tilted at a preset angle relative to the normal direction of the central axis of the equalizing ball body 1. By changing the spatial orientation of the end 2, the electric field distribution path is actively intervened. Since the end 2 is no longer directly facing the inner wall of the bushing or other grounding components, the electric field focusing effect that may be caused by direct facing is avoided; at the same time, the tilted setting makes the electric field lines more parallel to the direction of the cylinder wall when they diffuse outward from the end 2, reducing the distortion area and improving the local insulation margin.

[0035] The preset angle refers to the angle between the mounting plane of end 2 and the normal direction of the central axis of the equipotential ball body 1, that is, the tilt angle formed by the rotation of end 2 relative to the main body about a certain axis. The existence of this angle changes the spatial orientation of end 2, thereby affecting the relative potential distribution between it and the grounding cylinder wall, the bushing shell, and other adjacent conductors. When this angle is within the range of 5° to 30°, the orientation of the equipotential surface can be effectively controlled without significantly damaging the structural continuity and connection reliability, making it closer to being parallel to the inner wall of the grounding metal structure, thereby achieving the orderly arrangement of electric field lines and the effective dispersion of field strength.

[0036] The equalizing ball body 1 and the end 2 are spatially separated by the connecting structure, forming an oil gap filled with insulating oil. This gap is not caused by structural defects or assembly errors, but is an oil-filled area with a clear electrical function, actively designed through the connecting structure. By filling this gap with insulating oil, air or other low-dielectric-strength media that might otherwise be present are replaced by a high-insulating liquid, thereby improving the overall insulation level of the local area.

[0037] The insulating oil is typically a transformer-specific mineral oil or synthetic ester-based insulating liquid, possessing high breakdown field strength, good thermal stability, and gas evolution suppression capabilities. The presence of the oil gap extends the creepage path for surface discharge, and due to the continuity of the liquid medium, it effectively smooths the distribution of electric field lines, avoiding electric field distortion caused by abrupt changes at the solid interface.

[0038] Both the equalizing sphere body 1 and the end 2 are made of conductive metal materials, such as copper, aluminum alloy, and stainless steel, which ensures that the two are electrically equipotentially connected and avoids the accumulation of potential difference and stray current caused by material differences. At the same time, by utilizing the inherent high conductivity of metal materials, the entire equalizing sphere structure can quickly respond to changes in electric field, realize the homogenization of surface potential, and effectively suppress the risk of partial discharge.

[0039] The connection structure is a detachable connection structure, which refers to a mechanical connection method that allows for repeated assembly and disassembly between the equalizing ball body 1 and the end 2, without relying on permanent connection processes such as welding, bonding, or integral molding. This connection structure, while ensuring electrical conductivity and mechanical stability, allows operators to separate and reinstall the end 2 relative to the equalizing ball body 1 without damaging any components.

[0040] For example, such structures can be connected using threaded fasteners, such as by using a high-strength insulating washer and a metal bolt assembly to achieve conductive connection and sealing fixation through the connection interface corresponding to the end 2 of the mounting flange set on the equalizing ball body 1; or they can be connected using a snap-fit ​​quick-installation structure, such as the form of elastic claws and positioning grooves, which automatically locks after being pushed in axially, suitable for application scenarios that require frequent maintenance or quick replacement.

[0041] The surfaces of the equalizing sphere body 1 and the end 2 are smooth, which can significantly weaken the tip effect and suppress the phenomenon of local field strength increase. Since the electric field strength is significantly enhanced in regions with small radii of curvature, any tiny surface protrusion may become a discharge initiation point. Therefore, by improving the surface smoothness, it is equivalent to increasing the local effective radius of curvature, thereby smoothing the distribution of electric field lines and reducing the local maximum field strength value.

[0042] A second objective of this invention is to provide a method for manufacturing a transformer bushing-separated equalizing sphere, comprising the following steps: S1. Based on the rated voltage level and insulation requirements of the transformer bushing, the target spatial position relationship parameters of the end 2 relative to the equalizing ball body 1 are determined through finite element electric field simulation; the target spatial position relationship parameters include radial translation distance or rotation angle. Among them, the rated voltage level and insulation requirements based on transformer bushings refer to the electrical performance boundary conditions that the equalizing sphere must meet, based on the actual operating voltage level of the transformer in the engineering application scenario (such as 110kV, 220kV, 500kV, or even ultra-high voltage 1000kV level), combined with the technical indicators such as external insulation creepage distance, internal insulation withstand voltage strength, and partial discharge limit specified in relevant national standards (such as GB / T 10237, IEC 60137). These conditions directly affect the input parameter settings for subsequent simulation modeling. For example, the maximum allowable field strength threshold is usually set in the range of 1.8~2.5 kV / mm to avoid corona discharge in oil.

[0043] Finite element electric field simulation refers to the use of commercial electromagnetic field simulation software (such as COMSOL Multiphysics) to establish a three-dimensional electrostatic field model including the main body 1 and end 2 of the equalizing sphere. By applying a working voltage to the model and setting appropriate boundary conditions, the potential and electric field intensity distribution throughout the entire field domain can be obtained.

[0044] Determining the target spatial positional relationship parameters means finding the optimal configuration scheme that makes the electric field most uniform in the key areas (especially the transition area connecting the main body 1 and the end 2 of the equalizing ball, and the oil gap area near the grounding cylinder wall) through iterative simulation analysis.

[0045] S2. Manufacture the equalizing ball body 1, the end 2, and the connection structure that conforms to the target spatial positional relationship parameters respectively; S3. The end 2 is fixedly connected to the equalizing ball body 1 through the connection structure, so that the central axis of the end 2 and the central axis of the equalizing ball body 1 form the target spatial position relationship.

[0046] This method employs simulation-driven design based on electrical insulation requirements, ensuring that the product closely aligns with the electric field optimization needs of actual operating conditions from the conceptual stage. Subsequently, based on the key parameters determined by simulation, the main body, end 2, and connecting structure are manufactured separately, ensuring that the dimensions of each component are highly consistent with the design intent, laying the foundation for achieving the preset spatial positional relationship. Finally, precision assembly is performed through the connecting structure, transforming the non-coaxial concept from the design stage into a solid structure, thereby stably forming an electric field buffer structure between the equalizing sphere main body 1 and end 2 that effectively improves the electric field distribution and suppresses partial discharge.

[0047] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A transformer bushing-separable equalizing sphere, characterized in that, It includes a pressure equalization ball body (1) and an end (2); the pressure equalization ball body (1) and the end (2) are connected by a connecting structure; The connection structure is configured such that the end (2) is spatially fixedly separated from the equalizing ball body (1), such that the central axis of the end (2) and the central axis of the equalizing ball body (1) form a non-coaxial spatial position relationship, thereby forming an electric field buffer structure in the boundary area between the equalizing ball body (1) and the end (2).

2. The transformer bushing-separable equalizing sphere according to claim 1, characterized in that, The spatial position relationship is a translational relationship; the connection structure includes a connector (3) with a radial offset, and the end (2) is fixed to the equalizing ball body (1) through the connector (3), so that the central axis of the end (2) is parallel to but deviates from the central axis of the equalizing ball body (1).

3. The transformer bushing-separable equalizing sphere according to claim 2, characterized in that, The radial translation distance of the end (2) relative to the equalizing ball body (1) is 5mm~50mm.

4. The transformer bushing-separable equalizing sphere according to claim 1, characterized in that, The spatial positional relationship is a rotational relationship; the connection structure is configured such that the mounting plane of the end (2) is tilted at a preset angle relative to the normal direction of the central axis of the equalizing ball body (1).

5. A transformer bushing-separable equalizing sphere according to claim 4, characterized in that, The preset angle ranges from 5° to 30°.

6. The transformer bushing-separable equalizing sphere according to claim 1, characterized in that, The equalizing ball body (1) and the end (2) are spatially separated by the connecting structure to form an oil gap filled with insulating oil.

7. A transformer bushing-separable equalizing sphere according to claim 1, characterized in that, Both the equalizing ball body (1) and the end (2) are made of conductive metal material.

8. A transformer bushing-separable equalizing sphere according to claim 1, characterized in that, The connection structure is a detachable connection structure.

9. A transformer bushing-separable equalizing sphere according to claim 1, characterized in that, The surfaces of the equalizing ball body (1) and the end (2) are smooth surfaces.

10. A method for manufacturing a transformer bushing-separated equalizing sphere according to any one of claims 1 to 9, characterized in that, Includes the following steps: S1. Based on the rated voltage level and insulation requirements of the transformer bushing, the target spatial position relationship parameters of the end (2) relative to the equalizing ball body (1) are determined by finite element electric field simulation; the target spatial position relationship parameters include radial translation distance or rotation angle. S2. Manufacture the equalizing ball body (1), the end (2), and the connection structure that conforms to the target spatial position relationship parameters respectively; S3. The end (2) is fixedly connected to the equalizing ball body (1) through the connection structure, so that the central axis of the end (2) and the central axis of the equalizing ball body (1) form the target spatial position relationship.

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