High-current transformer dynamic stability enhancing structure based on induced electrodynamic force and assembling method of high-current transformer dynamic stability enhancing structure

Abstract

The invention provides a high-current transformer dynamic stability enhancing structure based on induced electrodynamic force and an assembling method thereof. The high-current transformer dynamic stability enhancing structure comprises at least one conductive hoop integrated on a primary winding of a current transformer, each conductive hoop meets the following conditions: the conductive hoop is of a cylindrical shell-shaped structure formed by winding a plate, and the height of the conductive hoop is greater than the height of a primary winding wire layer on the radial inner side of the conductive hoop; the conductive hoop is located in a magnetic field area opposite to the iron core center magnetic field direction when the current transformer primary winding is magnetically saturated in the iron core; the conductive hoop and the conductive hoop radial inner side / radial outer side primary winding wire layer are separated by an inner side fiber composite material / outer side fiber composite material; the conductive hoop radial inner side primary winding wire layer is electrically connected with the conductive hoop radial outer side primary winding wire layer. According to the invention, the dynamic stability performance of the large-current transformer in a power grid short-circuit fault and type test is obviously improved.

Description

Technical Field

[0001] This invention belongs to the field of advanced measurement and sensing technology of high current, and specifically relates to a dynamic stability enhancement structure for a high current transformer based on induced electrodynamics and its assembly method. Background Technology

[0002] High-current transformers are key equipment for high-current measurement in power systems, and dynamic stability current is one of the core technical indicators for measuring their performance limits. It characterizes the transformer's ability to withstand the enormous electrodynamic impact generated by a sudden short-circuit fault in the power grid without winding deformation, breakage, or insulation damage. With the development of ultra-high-voltage power grids and the continuous increase in system short-circuit capacity, the peak short-circuit current can reach hundreds of kiloamperes or more, which places extremely stringent requirements on the mechanical strength and stability of the transformer's primary winding. In type testing, the dynamic stability test is the ultimate assessment of the transformer's mechanical structure design, and traditional structures often pay a heavy price to pass this test.

[0003] Currently, all technical means to improve the dynamic stability of current transformers focus on passive mechanical reinforcement schemes, which mainly include:

[0004] 1) Significantly increase conductor cross-sectional area: The primary winding uses ultra-thick copper wire or multiple wires wound in parallel, thereby increasing the amount of material used to rigidly resist electrodynamic forces (which are proportional to the square of the current). This is the most direct but also the most expensive and inefficient method.

[0005] 2) Strengthen external mechanical restraint: Use high-strength non-magnetic binding tape or epoxy resin casting layer with significantly increased thickness to "lock" the primary winding in its original position.

[0006] 3) High-strength composite insulation material internal support: High-strength composite insulation material is used for internal support in the winding to balance the electrodynamic force on each layer of winding.

[0007] However, when these traditional methods are used with high-current transformers, their inherent drawbacks are further amplified:

[0008] 1) Significantly increased leakage inductance in the primary winding: Increasing the conductor cross-sectional area directly increases self-inductance; while adding internal supports and thickening the casting inevitably increases the distance between the primary and secondary windings, severely disrupting magnetic coupling and leading to a sharp increase in leakage inductance. High leakage inductance severely degrades the transient transmission characteristics of protective instrument transformers, causing current transmission delays and distortions, which may lead to maloperation or failure of protection devices. This is a fatal flaw during power grid faults.

[0009] 2) Size, cost, and temperature rise issues: To pass higher levels of dynamic stability testing, the amount of conductor and insulation material used increases exponentially, resulting in huge product sizes and high costs. Excessively thick conductors may also lead to increased eddy current losses and difficulties in heat dissipation.

[0010] Therefore, especially in the field of high-current transformers for power grid fault conditions and type testing, there is an urgent need for a new technical solution that can significantly improve the dynamic stability limit of the transformer without changing the original winding structure and coupling, in order to cope with the increasingly severe power grid operating environment. Summary of the Invention

[0011] The purpose of this invention is to propose a dynamic stability enhancement structure for a high-current transformer based on induced electrodynamics and its assembly method, which aims to significantly improve the dynamic stability performance of the high-current transformer in power grid short-circuit faults and type tests.

[0012] To achieve the above objectives, the technical solution of the present invention is as follows:

[0013] A dynamic stability enhancement structure for a high-current transformer based on induced electrodynamics includes at least one conductive clamp integrated into the primary winding of the current transformer; each conductive clamp satisfies the following condition:

[0014] The conductive hoop is a cylindrical shell structure made of rolled sheet metal, and the height of the conductive hoop is greater than the height of the primary winding conductor layer on the radial inner side of the conductive hoop.

[0015] The conductive ring is located in the magnetic field region of the primary winding of the current transformer when the iron core is magnetically saturated, and the direction of the magnetic field at the center of the iron core is opposite.

[0016] The conductive hoop and the primary winding conductor layer on the radial inner side of the conductive hoop are separated by an inner fiber composite material, and the inner fiber composite material, the conductive hoop, and the primary winding conductor layer on the radial inner side of the conductive hoop are tightly fitted.

[0017] The conductive hoop and the outer radial primary winding conductor layer of the conductive hoop are separated by an outer fiber composite material. The outer radial primary winding conductor of the conductive hoop is directly wound on the outer fiber composite material of the conductive hoop to form a conductor layer. The outer fiber composite material, the conductive hoop, and the outer radial primary winding conductor layer of the conductive hoop are tightly fitted.

[0018] The primary winding conductor layer on the inner radial side of the conductive hoop is electrically connected to the primary winding conductor layer on the outer radial side of the conductive hoop.

[0019] Preferably, the overall circumferential strength of the conductive hoop is not less than 500 MPa; the overall thickness of the conductive hoop is less than 1 mm; and the withstand voltage rating of the overall primary winding is greater than 30 kV.

[0020] Preferably, the conductive hoop is made of a material with a conductivity of not less than 80% IACS and a UTS of not less than 300MPa.

[0021] Preferably, the inner fiber composite material and the outer fiber composite material are made of glass fiber composite material.

[0022] Preferably, the thickness of the sheet material does not exceed 0.5 mm, and the starting and ending sections of the sheet material are transitioned by a wedge-shaped structure to ensure that the thickness difference at all points along the circumference of the cylindrical shell structure formed by rolling the sheet material is less than 0.1 mm.

[0023] Preferably, the lead wires of the primary winding conductor layer on the inner radial side of the conductive hoop and the lead wires of the primary winding conductor layer on the outer radial side of the conductive hoop are electrically connected by crimping or welding, and the tensile strength at the connection is not less than the strength of the base material.

[0024] Preferably, it also includes an internal component winding skeleton of the primary winding of the current transformer, which consists of an inner upper flange, a winding sleeve, and an inner lower flange, and an external component winding skeleton of the primary winding of the current transformer, which consists of an outer upper flange and an outer lower flange, wherein the number of external component winding skeletons is consistent with the number of conductive clamps.

[0025] Preferably, the incoming and outgoing wires of each layer of the primary winding are led out through through holes on the flange.

[0026] An assembly method for a dynamic stability enhancement structure of a high-current transformer based on induced electrodynamics, wherein the fabrication method is based on the above-mentioned dynamic stability enhancement structure of a high-current transformer.

[0027] When the number of conductive hoops is 1, the preparation method specifically includes the following steps:

[0028] Step S1: Insert the winding sleeve between the inner upper flange and the inner lower flange to form the internal component winding skeleton of the primary winding of the current transformer.

[0029] Step S2: Based on the internal component winding frame, wind the internal components of the primary winding of the current transformer according to the conventional process of the current transformer, and lead out the internal component inlet and outlet wires through the flange through hole of the internal component winding frame.

[0030] Step S3: Wind the inner fiber composite material on the outside of the internal components of the primary winding to ensure electrical insulation performance;

[0031] Step S4: Wrap a conductive hoop around the inner fiber composite material and wrap an outer fiber composite material around the outside of the conductive hoop.

[0032] Step S5: Fix the upper outer flange and the lower outer flange to the upper and lower surfaces of the internal component respectively, as the external component winding skeleton of the primary winding of the current transformer, wherein the internal component inlet wire and the internal component outlet wire are led out through the flange through hole of the external component winding skeleton.

[0033] Step S6: Based on the external component winding frame, wind the external component of the primary winding of the current transformer according to the conventional process of the current transformer, and lead out the external component inlet and outlet through the flange through hole of the external component winding frame.

[0034] Step S7: Outside the primary winding, complete the crimping or welding of the internal component outgoing wires and the external component incoming wires;

[0035] When the number of conductive hoops is greater than 1, based on the external components of the primary winding in step S6, repeat the assembly of the next set of inner fiber composite material, conductive hoops, outer fiber composite material, outer upper flange, and outer lower flange, as well as the winding of the next layer of external components and the lead-out of the incoming and outgoing lines of each layer of components; after completing all the assembly according to the number of conductive hoops, connect the components of each layer of the primary winding in series by crimping or welding through the lead-out incoming and outgoing lines.

[0036] Preferably, the inner fiber composite material is wound to ensure the dimensions by turning.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] 1) Excellent dynamic stability performance: It can fundamentally improve the ability of the instrument transformer to withstand short-circuit electrodynamic impacts, and is expected to improve the peak dynamic stability current index by 30% to 50% or even higher, easily meeting the most stringent type test requirements and the application needs of high short-circuit capacity power grids.

[0039] 2) Maintaining excellent transient characteristics: Since there is no need to sacrifice magnetic circuit design for mechanical strength, the present invention can maintain the original low leakage inductance characteristics of the current transformer to the greatest extent, ensuring that key indicators such as the accuracy limit factor (ALF) and transient error of the protection current transformer are not affected, and ensuring the accuracy of current measurement.

[0040] 3) Economy and miniaturization: It avoids the "over-design" that was traditionally done for the purpose of testing, effectively controls the amount of conductor material used and the product volume, and achieves higher performance density and cost-effectiveness.

[0041] 4) High reliability: This structure is a passive system that requires no external power supply or control. Its action response is a natural process determined by physical laws, ensuring instantaneous reliability and a lifespan that is the same as that of the product. Attached Figure Description

[0042] Figure 1 This is a cross-sectional view of the conductive hoop and radially inner primary winding assembly of the present invention;

[0043] Figure 2 This is an overall view of the conductive hoop and radially inner primary winding assembly of the present invention;

[0044] Figure 3 This is a cross-sectional view of the primary winding of the high-current transformer with conductive clamps according to the present invention.

[0045] Figure 4 This is an overall view of the primary winding of the high-current transformer with conductive clamps according to the present invention;

[0046] Figure 5 This is a schematic diagram of the conductive hoop winding of the present invention.

[0047] In the picture:

[0048] 1-Inner upper flange; 2-Winding sleeve; 3-Inner lower flange; 4-Inner component; 5-Inner component inlet; 6-Inner component outlet; 7-Inner fiber composite material; 8-Conductive clamp; 9-Outer upper flange; 10-Outer lower flange; 11-Outer fiber composite material; 12-Outer component; 13-Outer component inlet; 14-Outer component outlet. Detailed Implementation

[0049] The following is in conjunction with the appendix Figure 1-5 The technical solution of the present invention will be described in detail below.

[0050] This invention proposes a dynamic stability enhancement structure for a high-current transformer based on induced electrodynamics, suitable for coping with the impact of short-circuit fault currents in the power grid and rigorous type testing; it includes at least one conductive clamp integrated into the primary winding of the current transformer; each conductive clamp satisfies the following conditions:

[0051] 1. The conductive hoop is a cylindrical shell structure made of rolled sheet metal, and the overall circumferential strength of the conductive hoop is not less than 500MPa;

[0052] 2. The height of the conductive hoop is greater than (slightly higher than) the height of the primary winding conductor layer on the radial inner side of the conductive hoop, and the overall thickness is less than 1mm;

[0053] 3. The conductive ring is located in the magnetic field region of the primary winding of the current transformer, which is opposite to the direction of the magnetic field at the center of the iron core when the iron core is magnetically saturated;

[0054] 4. The conductive hoop and the primary winding conductor layer on the radial inner side of the conductive hoop are separated by an inner fiber composite material, and the inner fiber composite material, the conductive hoop, and the primary winding conductor layer on the radial inner side of the conductive hoop are tightly fitted.

[0055] The conductive hoop and the outer radial primary winding conductor layer of the conductive hoop are separated by an outer fiber composite material. The outer radial primary winding conductor of the conductive hoop is directly wound on the outer fiber composite material of the conductive hoop to form a conductor layer. The outer fiber composite material, the conductive hoop, and the outer radial primary winding conductor layer of the conductive hoop are tightly fitted.

[0056] The adjacent conductor layers are separated by fiber composite materials, so they do not come into direct contact and have good electrical insulation properties. The withstand voltage rating of the overall primary winding is greater than 30kV.

[0057] 5. The primary winding conductor layer on the inner radial side of the conductive hoop is electrically connected to the primary winding conductor layer on the outer radial side of the conductive hoop (made by a discontinuous winding process).

[0058] 6. The conductive hoop shall be made of materials with a conductivity of not less than 80% IACS and a UTS of not less than 300MPa.

[0059] In this embodiment, both the inner and outer fiber composite materials are made of glass fiber composite materials.

[0060] In this embodiment, the thickness of the plate does not exceed 0.5 mm, and the starting and ending sections of the plate are transitioned using a wedge-shaped structure (see reference). Figure 5 To avoid uneven thickness, the thickness difference in the circumferential direction of the cylindrical shell structure formed by rolling the sheet is less than 0.1 mm.

[0061] In this embodiment, the lead wires of the primary winding conductor layer on the inner radial side of the conductive hoop and the lead wires of the primary winding conductor layer on the outer radial side of the conductive hoop are electrically connected by crimping or welding, and the tensile strength at the connection is not less than the strength of the base material.

[0062] In this embodiment, the dynamic stability enhancement structure of the high current transformer also includes an internal component winding skeleton of the transformer primary winding, which is composed of an inner upper flange, a winding sleeve, and an inner lower flange, and an external component winding skeleton of the transformer primary winding, which is composed of an outer upper flange and an outer lower flange. The number of external component winding skeletons is consistent with the number of conductive clamps.

[0063] In this embodiment, the incoming and outgoing wires of each layer of the primary winding are led out through the through holes on the flange.

[0064] Based on the above-mentioned dynamic stability enhancement structure for high-current transformers, the present invention also proposes an assembly method for a dynamic stability enhancement structure for high-current transformers based on induced electrodynamics.

[0065] When the number of conductive hoops is 1, refer to the appendix. Figure 1-4 The preparation method specifically includes the following steps:

[0066] Step S1: Insert the winding sleeve (2) between the inner upper flange (1) and the inner lower flange (3) to form the internal component winding skeleton of the primary winding of the transformer;

[0067] Step S2: Based on the internal component winding frame, wind the internal component of the primary winding of the current transformer (4) according to the conventional process of the current transformer, and lead out the internal component inlet wire (5) and internal component outlet wire (6) through the flange through hole of the internal component winding frame.

[0068] Step S3: Wind the inner fiber composite material (7) on the outside of the inner component (4) of the primary winding to ensure electrical insulation performance, and perform turning to ensure the winding dimensions;

[0069] Step S4: Wrap the conductive hoop (8) around the inner fiber composite material (7) and wrap the outer fiber composite material (11) around the outside of the conductive hoop (8) to ensure electrical insulation performance while making the conductive hoop (8) a whole.

[0070] Step S5: Fix the outer upper flange (9) and the outer lower flange (10) to the upper and lower surfaces of the inner component (4) respectively, as the outer component winding skeleton of the primary winding of the transformer, wherein the inner component inlet wire (5) and the inner component outlet wire (6) are led out through the flange through hole of the outer component winding skeleton.

[0071] Step S6: Based on the external component winding frame, wind the external component of the primary winding of the current transformer (12) according to the conventional process of the current transformer, and lead out the external component inlet (13) and external component outlet (14) through the flange through hole of the external component winding frame.

[0072] Step S7: Outside the primary winding, complete the crimping or welding of the internal component outgoing wire (6) and the external component incoming wire (13);

[0073] When the number of conductive hoops is greater than 1, based on the external components of the primary winding in step S6, repeat the assembly of the next set of inner fiber composite material, conductive hoops, outer fiber composite material, outer upper flange, and outer lower flange, as well as the winding of the next layer of external components and the lead-out of the incoming and outgoing lines of each layer of components; after completing all the assembly according to the number of conductive hoops, connect the components of each layer of the primary winding in series by crimping or welding through the lead-out incoming and outgoing lines.

[0074] The basic principle of the dynamic stability enhancement structure and method for high-current current transformers based on induced electrodynamics is as follows:

[0075] Reference Appendix Figure 1 , 3In cylindrical coordinates, when a short-circuit fault occurs in the power grid or a dynamic stability test is performed, a short-circuit current with extremely high amplitude and rate of change (maximum di / dt) flows through the primary winding. The drastically changing strong magnetic field generated by this current causes the transformer core to reach magnetic saturation and induces extremely strong eddy currents in the conductive ring. Assuming the direction of the magnetic field at the center of the primary winding is +z, the conductive ring will generate an induced electric field and induced current in the -θ direction due to the change in magnetic flux linked to it. The induced current will interact with the axial magnetic field in the -z direction at that location, generating an induced electromotive force in the -r direction. The magnitude of the electromotive force on the conductive ring is positively correlated with its volume, which is larger than the internal single-layer conductor. Therefore, the induced electromotive force of the conductive ring will be similar in magnitude but opposite in direction to the +r electromotive force on its internal conductor layer, thus strengthening the primary winding.

[0076] It should be understood that the terms "top", "bottom", "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "inner", "outer", "Z-axis", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application 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. Therefore, they should not be construed as limitations on this application.

[0077] The above are preferred embodiments of the present invention. Any changes made to the technical solution of the present invention that do not exceed the scope of the technical solution of the present invention shall fall within the protection scope of the present invention.

Claims

1. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces, characterized by, The current transformer comprises at least one conductive hoop integrated with a primary winding of the current transformer; each of the conductive hoops satisfies the following conditions: The conductive hoop is a cylindrical shell structure wound by a plate material, and the height of the conductive hoop is greater than the height of a primary winding wire layer on the inner side of the conductive hoop in the radial direction; The conductive hoop is located in a magnetic field region opposite to the central magnetic field direction of the core when the primary winding of the current transformer is in magnetic saturation; The conductive hoop and the primary winding wire layer on the inner side of the conductive hoop in the radial direction are separated by inner fiber composite material, and the inner fiber composite material, the conductive hoop and the primary winding wire layer on the inner side of the conductive hoop in the radial direction are in an interference fit; The conductive hoop and the primary winding wire layer on the outer side of the conductive hoop in the radial direction are separated by outer fiber composite material, the primary winding wire layer on the outer side of the conductive hoop in the radial direction is directly wound on the outer fiber composite material of the conductive hoop to form a wire layer, and the outer fiber composite material, the conductive hoop and the primary winding wire layer on the outer side of the conductive hoop in the radial direction are in an interference fit; The primary winding wire layer on the inner side of the conductive hoop in the radial direction is electrically connected with the primary winding wire layer on the outer side of the conductive hoop in the radial direction.

2. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 1, characterized in that, The overall hoop strength of the conductive hoop is not less than 500 MPa; the overall thickness of the conductive hoop is less than 1 mm; and the withstand voltage level of the overall primary winding is greater than 30 kV.

3. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 1, characterized in that, The material used for the conductive hoop has an electrical conductivity of not less than 80% IACS and a UTS of not less than 300 MPa.

4. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 1, characterized in that, The inner fiber composite material and the outer fiber composite material are glass fiber composite materials.

5. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 1, characterized in that, The thickness of the plate material is not more than 0.5 mm, and the initial section and the end section of the plate material adopt a wedge-shaped structure for transition, so as to ensure that the thickness difference of the cylindrical shell structure wound by the plate material is less than 0.1 mm.

6. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 1, characterized in that, The outgoing line of the primary winding wire layer on the inner side of the conductive hoop in the radial direction is electrically connected with the outgoing line of the primary winding wire layer on the outer side of the conductive hoop in the radial direction through pressure welding or welding, and the tensile strength at the connection is not less than the bulk strength of the base material.

7. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to any of claims 1-6, characterized in that, Further comprising an internal component winding skeleton of the primary winding of the current transformer composed of an internal upper flange, a winding sleeve and an internal lower flange, and an external component winding skeleton of the primary winding of the current transformer composed of an external upper flange and an external lower flange, the number of the external component winding skeleton being consistent with the number of the conductive hoop.

8. A dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 7, characterized in that, The incoming line and the outgoing line of each layer component of the primary winding are led out through the through holes in the flanges.

9. A method of assembling a dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces, characterized in that, The preparation method is based on the large-current transformer dynamic stability enhancement structure of claim 8; When the number of the conductive hoop is 1, the preparation method specifically comprises the following steps: Step S1, embedding the winding sleeve between the internal upper flange and the internal lower flange to form the internal component winding skeleton of the primary winding of the current transformer; Step S2, based on the internal component winding skeleton, winding the internal component of the primary winding of the current transformer according to the conventional process of the current transformer, and leading out the incoming line and the outgoing line of the internal component through the flange through holes of the internal component winding skeleton; Step S3, winding the inner fiber composite material on the outer side of the internal component of the primary winding to ensure the electrical insulation performance; Step S4, winding the conductive hoop on the inner fiber composite material, and winding the outer fiber composite material on the outer side of the conductive hoop. Step S5, fixing the external upper flange and the external lower flange on the upper and lower surfaces of the internal assembly respectively as the external assembly winding skeleton of the primary winding of the transformer, wherein the incoming line of the internal assembly and the outgoing line of the internal assembly are led out through the flange through hole of the external assembly winding skeleton; Step S6, based on the external assembly winding skeleton, winding the external assembly of the primary winding of the transformer according to the conventional process of the transformer, and leading out the incoming line and the outgoing line of the external assembly through the flange through hole of the external assembly winding skeleton; Step S7, completing the crimping or welding of the outgoing line of the internal assembly and the incoming line of the external assembly outside the primary winding; When the number of the conductive hoops is greater than 1, on the basis of the external assembly of the primary winding in step S6, repeating the assembly of the next group of the internal fiber composite material, the conductive hoop, the external fiber composite material, the external upper flange, the external lower flange, and the winding of the next layer of the external assembly and the leading out of the incoming line and the outgoing line of each layer of the assembly; after completing all the assemblies according to the number of the conductive hoops, connecting in series the primary winding of each layer of the assembly by using the crimping or welding of the led-out incoming line and outgoing line.

10. An assembly method of a dynamic stability enhancement structure for a large current transformer based on induced electrodynamic forces according to claim 9, characterized in that, The internal fiber composite material is ensured in size by turning.

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