transformer

Abstract

This invention relates to a transformer, comprising: a high-voltage coil including: a first high-voltage coil portion wound on an iron core, having a first end and a second end, the potential of the first end being higher than the potential of the second end; and a second high-voltage coil portion wound on the iron core radially insulated from the first high-voltage coil portion, having a third end and a fourth end, the potential of the third end being higher than the potential of the fourth end, and the potential of the second end being higher than the potential of the third end; and a switch including: a first contact connected to the second end; a second contact connected to the third end; a third contact connected to the fourth end; and contacts including a first contact portion and a second contact portion, wherein when the first contact portion is connected to the second contact and the second contact portion is connected to the first contact, the first high-voltage coil portion and the second high-voltage coil portion are connected in series; and when the first contact portion is connected to the first contact and the second contact portion is connected to the third contact, only the first high-voltage coil portion is used.

Description

Technical Field

[0001] This invention relates to the field of transformers, and more specifically, to a transformer for testing shunt reactors. Background Technology

[0002] Typically, shunt reactors undergo withstand voltage tests such as power frequency withstand voltage and induced withstand voltage before leaving the factory or being put into operation on-site. Because the rated voltage of shunt reactors is extremely high (e.g., 550kV), the test voltage must reach up to 1.8 times its rated voltage (i.e., up to 990kV), which requires a specially designed transformer for testing shunt reactors.

[0003] Currently, transformers used for shunt reactor testing typically employ a two-column series or parallel structure for their high-voltage coils to achieve high-voltage output (up to 990kV). In such a structure, if a series-parallel switch is used to change the series-parallel connection method (number of turns) of the high-voltage coil, it could potentially subject the switch to a voltage as high as 990kV. However, such a high-voltage level series-parallel switch does not currently exist. Therefore, the high-voltage coils of such transformers are generally not connected to a series-parallel switch; instead, the series or parallel connection method of the high-voltage coil is changed externally through at least four bushings outside the tank.

[0004] However, manually switching the series and parallel connections of high-voltage coils outside the oil tank via bushing connection results in problems such as complex operation, low safety, a large number of bushings required, large system size, and low on-site debugging efficiency. Summary of the Invention

[0005] In view of the current state and shortcomings of the prior art, the purpose of this invention is to provide a transformer that divides the high-voltage coil into two high-voltage coil sections arranged radially on the iron core. By using a switch to change the connection of the three terminals of the two high-voltage coil sections at the lower potential, it achieves rapid and safe switching between series (high voltage output) and single-line operation (low voltage output) modes for the two high-voltage coil sections, without relying on external bushing wiring. This significantly simplifies the operation process, reduces the number of bushings, improves equipment integration and on-site operational safety, while meeting the test voltage requirements up to 990kV.

[0006] According to an embodiment of the present invention, a transformer is provided, comprising: a high-voltage coil, the high-voltage coil including: a first high-voltage coil portion wound on an iron core, having a first end and a second end, the potential of the first end being higher than the potential of the second end; and a second high-voltage coil portion wound on the iron core radially insulated from the first high-voltage coil portion, having a third end and a fourth end, the potential of the third end being higher than the potential of the fourth end, and the potential of the second end being higher than the potential of the third end; and a switch including: a first contact connected to the second end; and a second contact connected to the third end; The third contact is connected to the fourth terminal; and the contact includes a first contact portion and a second contact portion, the contact being configured to be connected to both the first contact and the second contact or both the first contact and the third contact via the first contact portion and the second contact portion, wherein when the first contact portion is connected to the second contact and the second contact portion is connected to the first contact, the first high-voltage coil portion and the second high-voltage coil portion are connected in series; when the first contact portion is connected to the first contact and the second contact portion is connected to the third contact, the first high-voltage coil portion is connected and the second high-voltage coil portion is disconnected.

[0007] By employing the above method, the high-voltage coil is divided into two radially arranged high-voltage coil sections on the iron core. A switch is used to change the connection of the three terminals of the two high-voltage coils at the lower potential, enabling rapid and safe switching between series (high-voltage output) and single-column (low-voltage output) operation modes without relying on external bushing wiring. This significantly simplifies the operation process, reduces the number of bushings, improves equipment integration and on-site operational safety, while simultaneously meeting test voltage requirements up to 990kV.

[0008] In a transformer according to an embodiment of the present invention, a first high-voltage coil portion includes a first coil winding, a second high-voltage coil portion includes a second coil winding, and the conductor diameter of the first coil winding is larger than the conductor diameter of the second coil winding.

[0009] The first high-voltage coil section uses thick wire windings, which can effectively reduce the resistance and current density of this section in single-column operation mode, ensuring that the transformer can safely and efficiently carry the rated power under low voltage and high current conditions, and achieving seamless and reliable switching between the two operating modes.

[0010] In a transformer according to an embodiment of the present invention, the transformer further includes: a low-voltage coil wound around the core outside the second high-voltage coil portion, wherein the first high-voltage coil portion is wound around the core outside the low-voltage coil.

[0011] By arranging the low-voltage coil radially between the first high-voltage coil section and the second high-voltage coil section in the above manner, the low-voltage coil and the high-voltage coils on both sides form a bidirectional close-range coupling structure, which significantly shortens the leakage flux path between the high-voltage coil and the low-voltage coil and reduces the equivalent leakage reactance between them.

[0012] In the transformer according to an embodiment of the present invention, it further includes: a low-voltage coil directly wound on the iron core, wherein a first high-voltage coil portion is wound around the iron core on the outside of the low-voltage coil portion, and a second high-voltage coil portion is wound around the iron core on the outside of the first high-voltage coil portion.

[0013] By means of the above method, when the switch is switched to the single-row operation mode that uses only the first high-voltage coil section, the first high-voltage coil section and the low-voltage coil are made to form the minimum radial coupling distance, thereby significantly reducing the equivalent leakage reactance between the two.

[0014] In the transformer according to an embodiment of the present invention, a first end of the first high-voltage coil portion is connected to the outside via a first bushing, and a fourth end of the second high-voltage coil portion is further connected to the outside via a second bushing.

[0015] By setting a first bushing at the first end of the first high-voltage coil section and a second bushing at the fourth end of the second high-voltage coil section, the transformer can achieve internal series / single mode switching while retaining only two electrical interfaces externally. This ensures the integrity of the high-voltage output circuit and avoids the operational complexity and safety hazards caused by traditional multi-bucket switching. Attached Figure Description

[0016] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of a transformer according to an embodiment of the present invention is shown.

[0017] Figure 2 A first arrangement of the high-voltage coil of a transformer according to an embodiment of the present invention is shown.

[0018] Figure 3 A second arrangement of the high-voltage coil of a transformer according to an embodiment of the present invention is shown.

[0019] The reference numerals in the attached figures are as follows: 1: Transformer 10: High-voltage coil 12: Switch 14: Transformer oil tank 16: Low-voltage coil 101: First high-voltage coil section 103: Second High Voltage Coil Section 1011: First terminal of the first high-voltage coil section 1012: The second end of the first high-voltage coil section 1031: The third terminal of the second high-voltage coil section 1032: The fourth terminal of the second high-voltage coil section 161: The first terminal of the low-voltage coil 163: The second terminal of the low-voltage coil 121: First Contact Point 122: Second contact point 123: Third contact point 124: Contacts 1241: First contact section 1242: Second contact section. Detailed Implementation

[0020] 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 should fall within the scope of protection of the present invention.

[0021] This invention provides a transformer. Figure 1 A schematic diagram of a transformer is shown. Figure 2 A first arrangement of the high-voltage coil of a transformer according to an embodiment of the present invention is shown. Figure 3 A second arrangement of the high-voltage coil of a transformer according to an embodiment of the present invention is shown.

[0022] It is known that a transformer mainly consists of an iron core, a high-voltage coil, a low-voltage coil, an insulation system, an oil tank, a cooling device, bushings, and a grounding device. Since the inventive point of this invention mainly focuses on the radial segmentation design of the high-voltage coil and its relative arrangement with the low-voltage coil, as well as the electrical connection method of the internal switches, in order to avoid redundancy and ambiguity in the technical solution, this specification will not describe in detail the well-known structures and conventional connection methods of the iron core, oil tank, cooling system, and grounding device in the art. Their structure, materials, and installation methods can all be implemented according to industry standards or specifications, and do not constitute the necessary technical features of this invention, nor are they intended to limit the scope of protection of this invention.

[0023] For ease of understanding, Figure 1 The diagram only shows the electrical connection between the high-voltage coil and the switch inside the transformer. Figure 2 and Figure 3The diagram uses a cross-sectional view of the iron core to illustrate the spatial arrangement of the high-voltage and low-voltage coils in the radial direction. Only half of the cross-section is shown; the other half is symmetrical, with the iron core (not shown) located on the left side of the cross-section. The following section will combine... Figures 1 to 3 The transformer according to the present invention will be described.

[0024] like Figure 1 As shown, the transformer 1 according to an embodiment of the present invention includes a high-voltage coil 10 and a switch 12, both of which are sealed inside the transformer oil tank 14. The oil tank is filled with insulating oil for insulation and heat dissipation.

[0025] The high-voltage coil 10 includes a first high-voltage coil portion 101 and a second high-voltage coil portion 103 arranged radially and insulatedly on the iron core. Here, "radial" refers to the arrangement direction along the radius of the iron core, from the inside out or from the outside in, that is, the radial extension direction perpendicular to the iron core axis (axial direction).

[0026] The first high-voltage coil portion 101 is wound on the iron core and has a first end 1011 and a second end 1012, wherein the potential of the first end 1011 is higher than the potential of the second end 1012.

[0027] The second high-voltage coil section 103 is wound radially insulated from the first high-voltage coil section 101 on the iron core, and has a third end 1031 and a fourth end 1032. The potential of the third end 1031 is higher than the potential of the fourth end 1032, and the potential of the second end 1012 is higher than the potential of the third end 1031.

[0028] That is, the first end 1011 of the first high-voltage coil section 101 is the high-voltage output terminal, and the fourth end 1032 of the second high-voltage coil section 103 is the low-voltage output terminal. The first end 1011 of the first high-voltage coil section 101 can be connected to the outside of the transformer tank (e.g., one input terminal of a shunt reactor) via a bushing, serving as the main high-voltage output terminal. The fourth end 1032 of the second high-voltage coil section 103 is connected to the outside of the transformer tank (e.g., another input terminal of a shunt reactor) via a bushing, serving as the reference terminal of the high-voltage circuit. Together, they constitute the two polarity terminals of the test circuit. This design allows the present invention to require only two external bushings, significantly simplifying the complexity of on-site wiring and reducing insulation risks and space occupation compared to the four or more bushings required by the traditional double-column series structure.

[0029] For example, both the first high-voltage coil section 101 and the second high-voltage coil section 103 can adopt a disc-shaped structure, which is formed by stacking disc-shaped coils wound with multiple layers of insulated wires along the axial direction of the iron core. Each coil has insulating pads on its inner and outer sides, and the layers are separated by insulating paper or insulating cardboard. The coils are connected in series by the ends of the wires to form an axial current path, and oil channels are provided between the coils to enhance heat dissipation and insulation. In a cross-section viewed from the extension direction of the iron core, the first high-voltage coil section 101 and the second high-voltage coil section 103 are distributed in concentric circles around the iron core.

[0030] Transformer 1 may further include a low-voltage coil 16 wound on an iron core. The low-voltage coil 16 includes a first end 161 and a second end 163. In the transformer, the two ends of the low-voltage coil are typically connected to a low-voltage bushing, through which it is led out to an external low-voltage power supply for receiving the external low-voltage power and inductively exciting the high-voltage coil. The structure of the low-voltage coil 16 can be implemented according to common designs in the art, such as a cylindrical or helical winding.

[0031] like Figure 2 As shown, it illustrates the first arrangement relationship between the first high-voltage coil portion 101 and the second high-voltage coil portion 103 of the high-voltage coil and the low-voltage coil 16.

[0032] exist Figure 2 The image shows half of a cross-section taken along the center of the iron core, parallel to its extension direction, illustrating the arrangement of the high-voltage and low-voltage coils. The iron core is located to the left of the second high-voltage coil section 103. Figure 2 The iron core and the other half of the cross-section on the left side of the iron core are not shown in the figure.

[0033] like Figure 2 As shown, the second high-voltage coil portion 103 is directly wound on the outer surface of the iron core, the low-voltage coil 16 is wound around the iron core on the outside of the second high-voltage coil portion 103, and the first high-voltage coil portion 101 is wound around the iron core on the outside of the low-voltage coil 16, forming a structure in the radial direction of the iron core consisting of the second high-voltage coil portion 103, the low-voltage coil 16, and the first high-voltage coil portion 101 in sequence from the iron core outwards.

[0034] With this arrangement, the low-voltage coil 16 is radially positioned between the first high-voltage coil section 101 and the second high-voltage coil section 103, forming a bidirectional close-range coupling structure between the low-voltage coil and the high-voltage coils on both sides. This significantly shortens the leakage flux path between the high-voltage coil and the low-voltage coil and reduces the equivalent leakage reactance between them.

[0035] Other arrangements may also be used between the first high-voltage coil section 101 and the second high-voltage coil section 103 of the high-voltage coil and the low-voltage coil 16.

[0036] like Figure 3 As shown, it illustrates a second arrangement relationship between the first high-voltage coil portion 101 and the second high-voltage coil portion 103 of the high-voltage coil and the low-voltage coil 16.

[0037] exist Figure 3 The image shows half of a cross-section taken along the center of the iron core, parallel to its extension direction, illustrating the arrangement of the high-voltage and low-voltage coils. The iron core is positioned to the left of the low-voltage coil 16. Figure 3 The iron core and the other half of the cross-section on the left side of the iron core are not shown in the figure.

[0038] like Figure 3 As shown, the low-voltage coil 16 is directly wound on the outer surface of the iron core, the first high-voltage coil portion 101 is wound around the iron core on the outside of the low-voltage coil 16, and the second high-voltage coil portion 103 is wound around the iron core on the outside of the first high-voltage coil portion 101, forming a structure in the radial direction of the iron core consisting of the low-voltage coil 16, the first high-voltage coil portion 101, and the second high-voltage coil portion 103 in sequence from the iron core outwards.

[0039] With this arrangement, when the transformer is in single-line operation mode using only the first high-voltage coil section, the first high-voltage coil section and the low-voltage coil section are made to form the minimum radial coupling distance, thereby significantly reducing the equivalent leakage reactance between them.

[0040] like Figure 1 As shown, the switch 12 may include a first contact 121, a second contact 122, a third contact 123, and a sliding contact 124.

[0041] The first contact 121 can be connected to the second end 1012 of the first high-voltage coil section 101, the second contact 122 can be connected to the third end 1031 of the second high-voltage coil section 103, and the third contact 123 can be connected to the fourth end 1032 of the second high-voltage coil section 103.

[0042] The contact 124 includes two independent conductive parts, namely, a first contact part 1241 and a second contact part 1242, which are rigidly connected by an insulating link to achieve synchronous operation.

[0043] like Figure 1 As shown, contact 124 can be connected to both first contact 121 and second contact 122 or both first contact 121 and third contact 123 via first contact portion 1241 and second contact portion 1242. That is, switch 12 can have two operating states: series mode (high voltage output mode) and single-row mode (low voltage output mode).

[0044] Specifically, in series mode, contact 124 is in the first position, the first contact portion 1241 is in contact with the second contact 122, and the second contact portion 1242 is in contact with the first contact 121. At this time, the first high-voltage coil portion 101 and the second high-voltage coil portion 103 are connected in series by switch 12. The total number of turns of the high-voltage coil is the sum of the two. The transformer can provide high voltage to the outside, for example, up to 990kV.

[0045] In single-row mode, contact 124 is in the second position, with the first contact portion 1241 in contact with the first contact 121 and the second contact portion 1242 in contact with the third contact 123. At this time, the second high-voltage coil portion 103 is removed, and only the first high-voltage coil portion 101 is connected to the circuit, allowing the transformer to provide a lower voltage to the outside.

[0046] Here, switch 12 can achieve physical displacement through mechanical actuators (such as electric push rods or manual cranks), or it can achieve automated switching through intelligent control systems (such as MCUs, position sensors, and remote communication modules), supporting remote control and test process programming, and is compatible with digital test platforms.

[0047] In the transformer according to an embodiment of the present invention, when the contact 124 of the switch 12 moves to the second position and is in single-coil mode, only the first high-voltage coil portion 101 is connected to the circuit, and the second high-voltage coil portion 103 is removed. At this time, the output voltage of the transformer decreases, but in order to maintain the rated output capacity (i.e., power P = U × I constant), the output current will increase significantly. Since the first high-voltage coil portion 101 bears the entire load current at this time, its current density is much higher than its operating state in series mode (two coils sharing the current). If the first high-voltage coil portion 101 is still wound with the same thin wire as the second high-voltage coil portion 103, the sudden increase in current will lead to excessive temperature rise, a sharp increase in copper loss, and even the risk of local overheating, insulation aging, or operational failure.

[0048] Therefore, the present invention uses a wire with a larger diameter to wind the coil winding of the first high-voltage coil section 101, so that its cross-sectional area is larger than that of the wire cross-sectional area of ​​the second high-voltage coil section 103. This effectively reduces the resistance and current density of this section in single-row operation mode, ensuring that it can safely and efficiently carry the rated power under low voltage and high current conditions, and realizing seamless and reliable switching between the two working modes.

[0049] In the transformer according to an embodiment of the present invention, by dividing the high-voltage coil into two high-voltage coil sections arranged radially on the iron core, and using a switch to change the connection of the three terminals of the two high-voltage coils at the lower potential, a rapid and safe switching between series (high voltage output) and single-line operation (low voltage output) modes for the two high-voltage coil sections is achieved without relying on external bushing wiring. This significantly simplifies the operation process, reduces the number of bushings, improves equipment integration and on-site operational safety, while meeting the test voltage requirements of up to 990kV.

[0050] To better understand the present invention, the following describes the operation mode of the transformer according to the embodiments of the present invention, in conjunction with the application scenario of the transformer in the withstand voltage test of the parallel reactor.

[0051] When the transformer according to an embodiment of the present invention is used for a withstand voltage test of a shunt reactor, the high-voltage output terminal of the transformer (i.e., the first end 1011 of the first high-voltage coil section 101) is led out through the first bushing and connected to the high-voltage terminal of the shunt reactor under test via a lead wire. The low-voltage output terminal of the transformer (i.e., the fourth end 1032 of the second high-voltage coil section 103) is led out through the second bushing and connected to the low-voltage terminal of the shunt reactor under test via a lead wire. The transformer switch 12 is initially placed in the "series mode" position, that is, the first contact section 1241 of its contact 124 is connected to the second contact 122, and the second contact section 1242 is connected to the first contact 121, so that the first high-voltage coil section 101 and the second high-voltage coil section 103 are connected in series, forming a high-voltage output circuit with a total number of turns equal to the sum of the two sections. At this time, the transformer can output a test voltage of up to 990kV to meet the requirements of a 1.8 times rated voltage power frequency withstand voltage test for a 550kV shunt reactor.

[0052] After completing the 990kV withstand voltage test, without disconnecting any external wiring, the user only needs to operate switch 12 on the transformer control panel or the local operating switch 12 to switch contact 124 to the "single-row mode" position. At this time, the first contact portion 1241 is connected to the first contact 121, the second contact portion 1242 is connected to the third contact 123, the second high-voltage coil portion 103 is removed, and only the first high-voltage coil portion 101 operates independently, with the output voltage dropping to approximately 550kV. This voltage can be used for subsequent low-voltage conditions such as partial discharge detection, induced withstand voltage testing, or insulation resistance retesting.

[0053] Since switch 12 is built into the transformer tank, all high-voltage connections do not require manual external bushing disconnection and reconnection, completely avoiding major safety risks such as electric shock, short circuit, and misconnection caused by frequent plugging and unplugging of bushings in high-altitude and high-voltage environments in traditional methods. At the same time, only two sets of external high-voltage bushings (the first bushing and the second bushing) are required throughout the entire test process, which is a significant reduction compared to the four or more sets of bushings required by the traditional double-column series structure. The system has high integration, small footprint, and shortened commissioning time.

[0054] This invention enables "one-click switching" of voltage modes through an internal switch, achieving a seamless transition from high-voltage withstand voltage to low-voltage detection without interrupting the test circuit or changing the wiring layout. This significantly improves the automation level, safety, and operational efficiency of the withstand voltage test of parallel reactors.

[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A transformer (1), comprising: High-voltage coil (10), the high-voltage coil comprising: A first high-voltage coil section (101) is wound on an iron core and has a first end (1011) and a second end (1012), wherein the potential of the first end is higher than the potential of the second end; and The second high-voltage coil portion (103), radially insulated from the first high-voltage coil portion, is wound on the iron core and has a third end (1031) and a fourth end (1032), wherein the potential of the third end is higher than that of the fourth end, and the potential of the second end is higher than that of the third end; and Switch (12), the switch comprising: The first contact (121) is connected to the second end (1012); The second contact (122) is connected to the third end (1031); The third contact (123) is connected to the fourth terminal (1032); and The contact (124) includes a first contact portion (1241) and a second contact portion (1242), the contact being configured to be connected via the first contact portion (1241) and the second contact portion (1242) to either the first contact (121) and the second contact (122) or to either the first contact (121) and the third contact (123). When the first contact portion (1241) is connected to the second contact (122) and the second contact portion (1242) is connected to the first contact (121), the first high-voltage coil portion (101) and the second high-voltage coil portion (103) are connected in series. When the first contact portion (1241) is connected to the first contact (121) and the second contact portion (1242) is connected to the third contact (123), the first high-voltage coil portion (101) is connected and the second high-voltage coil portion (103) is disconnected.

2. The transformer (1) according to claim 1, wherein, The first high-voltage coil portion (101) includes a first coil winding, and the second high-voltage coil portion (103) includes a second coil winding. The conductor diameter of the first coil winding is larger than the conductor diameter of the second coil winding.

3. The transformer (1) according to claim 1, further comprising: The low-voltage coil (16) is wound around the iron core on the outside of the second high-voltage coil portion (103). The first high-voltage coil portion (101) is wound around the iron core on the outside of the low-voltage coil (16).

4. The transformer (1) according to claim 1, further comprising: The low-voltage coil (16) is directly wound on the iron core. The first high-voltage coil portion (101) is wound around the iron core on the outside of the low-voltage coil (16), and the second high-voltage coil portion (103) is wound around the iron core on the outside of the first high-voltage coil portion (103).

5. The transformer (1) according to claim 1, wherein, The first end (101) of the first high-voltage coil portion (10) is connected to the outside via a first sleeve, and the fourth end (1032) of the second high-voltage coil portion (103) is further connected to the outside via a second sleeve.

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