High-impedance angle joint phase-shifting transformer
By adopting a three-pillar core structure and a built-in three-phase reactor design in the phase-shifting transformer, the shortcomings of the existing phase-shifting transformers in terms of short-circuit impedance and lightning impact resistance are solved, and a high-impedance angle phase-shifting transformer is realized, which improves the short-circuit and overvoltage impact resistance, while reducing costs and design complexity.
Patent Information
- Application Number
- CN202411487003.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-23
- Publication Date
- 2025-06-06
AI Technical Summary
The existing phase-shifting transformers using triangular connection method have shortcomings in short-circuit impedance and lightning impact resistance, especially when the phase-shifting angle is small, the short-circuit impedance is close to zero, and the short-circuit and lightning impact resistance are poor.
A high-impedance angular phase shift transformer is designed, adopting a three-pillar core structure, with excitation winding and phase adjustment winding on each phase core column. The two ends of the excitation winding are connected in series and then triangular connections are made. The moving contacts of the phase adjustment switch are connected to the phase adjustment winding, and a third three-phase reactor is connected in series to improve the ability to resist short circuit and overvoltage impact.
By incorporating three three-phase reactors, the short-circuit resistance and overvoltage shock resistance of the phase-shifting transformer is improved, ensuring that there is still sufficient impedance at zero phase-shifting angle, reducing costs, and simplifying the structure and manufacturing process.
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Figure CN120108905A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of transformer manufacturing, and in particular to a high-impedance angle-connected phase-shifting transformer. Background Art
[0002] The phase-shifting transformer using the triangle connection has only one body, and each phase only uses two windings, the excitation winding and the voltage regulating winding, to achieve phase shifting. It has a simple structure and low material cost. However, when the phase shift angle is relatively small, the short-circuit impedance of the phase-shifting transformer using the triangle connection is very small, especially when the phase shift angle is close to zero, the short-circuit impedance of the phase-shifting transformer is close to zero, and the short-circuit resistance is very poor. In order to ensure the short-circuit resistance, it is necessary to increase the amount of winding copper wire, resulting in a significant increase in cost.
[0003] In addition, the line ends and phase-adjusting switches of all windings of the phase-shifting transformer using a triangle connection are directly connected to the system, and its ability to withstand various overvoltage shocks is relatively poor. Therefore, the existing phase-shifting transformers using a triangle connection are only suitable for occasions with low voltage levels, small phase shift angles, and low transmission capacity. Summary of the invention
[0004] In order to solve the above technical problems, the present invention provides a simple and effective solution to the above problems and proposes a high-impedance delta-connected phase-shifting transformer, which solves the problem that the phase-shifting transformer using a delta connection has poor short-circuit resistance and lightning impulse resistance.
[0005] The present invention provides a high-impedance angle-connected phase-shifting transformer, which is a three-column iron core structure, and an excitation winding and a phase-adjusting winding are sleeved on each phase iron core column of the three phases;
[0006] Two ends of the excitation winding are respectively connected in series with two three-phase reactors to form a triangle connection, and the third end of the excitation winding is connected to the phase-adjusting winding;
[0007] The high impedance angle-connected phase-shifting transformer further comprises a phase-adjusting switch, one end of a moving contact of the phase-adjusting switch is connected to the phase-adjusting winding, and the other end of the moving contact of the phase-adjusting switch is connected in series with a third three-phase reactor after three-phase extraction;
[0008] The phase angle between the voltage on the power supply side and the voltage on the load side is changed by adjusting the number of coil turns of the phase-adjusting winding connected to the circuit through the phase-adjusting switch, thereby realizing the loop closing and power flow control of the high-impedance angle-connected phase-shifting transformer.
[0009] As a further improvement, the three phases of the excitation winding are led out to three wire ends which are respectively connected to the three phases on the power supply side.
[0010] As a further improvement, three line terminals of the third three-phase reactor are respectively led out and connected to the three phases on the load side.
[0011] As a further improvement, three reactors are located inside the high-impedance angle-connected phase-shifting transformer as built-in reactors.
[0012] As a further improvement, the built-in reactor is an air-core reactor.
[0013] As a further improvement, the built-in inductor includes a coil, magnetic shielding plates arranged at the upper and lower ends of the coil, an insulating pressure plate and a support plate installed on the upper end of the upper magnetic shielding plate, and an insulating support plate and a pad installed on the lower end of the lower magnetic shielding plate. The support plate, magnetic shielding plate and pad are fastened together up and down by clamp screws to fix the three-phase inductor as a whole.
[0014] As a further improvement, the phase-adjusting winding includes an inner phase-adjusting winding and an outer phase-adjusting winding, wherein the inner and outer phase-adjusting windings are wound in opposite directions.
[0015] As a further improvement, the high impedance angle-connected phase-shifting transformer further comprises a ZnO lightning arrester arranged between each tap lead of the phase-modulating winding.
[0016] As a further improvement, the lead wires between the excitation winding and the three-phase reactor adopt a rectangular frame type lead wire clamping structure.
[0017] As a further improvement, the rectangular frame type lead clamping structure arranges the leads in layers inside and outside, wherein the phase adjustment tapping leads are arranged in the inner layer and the excitation leads are arranged in the outer layer.
[0018] The positive effects of the present invention are as follows: the structure is reasonable and simple, and the manufacturing is convenient. It solves the problem that the phase-shifting transformer with a triangle connection has poor short-circuit resistance and system overvoltage impact resistance. The high-impedance phase-shifting transformer proposed by the present invention improves the short-circuit resistance and overvoltage impact resistance of the phase-shifting transformer with a triangle connection by building three three-phase reactors into the phase-shifting transformer and connecting them in series at the beginning and end of the winding and the phase-adjusting switch. The phase-shifting transformer with this structure is still a single-body structure, does not increase the number of main windings, and has simple wiring. It is simpler than the traditional double-body structure of the phase-shifting transformer with the same function, reduces the difficulty of design and manufacturing, and improves the reliability of system operation. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 A wiring schematic diagram of a high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0020] Figure 2 This is a voltage and current vector diagram of the high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0021] Figure 3 A front view of the built-in inductor of the high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0022] Figure 4 A top view of a built-in reactor of a high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0023] Figure 5 The embodiment of the present application provides a phase-adjusting winding connection and a lightning arrester arrangement for a high-impedance angle-connected phase-shifting transformer.
[0024] Figure 6 A front view of the rectangular frame lead structure of the high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0025] Figure 7 A top view of a rectangular frame lead structure of a high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0026] Figure 8 A phase-adjusting switch elevation seat for a high-impedance angle-connected phase-shifting transformer provided in an embodiment of the present application.
[0027] Fig. 9 The high-impedance angle-connected phase-shifting transformer provided in the embodiment of the present application is fixed on the side between the body and the oil tank. DETAILED DESCRIPTION
[0028] For ease of understanding, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.
[0030] Figure 1 The wiring schematic diagram of the high impedance angle-connected phase-shifting transformer provided in the embodiment of the present application is as follows: Figure 1As shown, the present invention provides a high-impedance phase-shifting transformer adopting a brand-new triangle connection structure, specifically a three-column iron core structure, with two windings on each phase iron core column of the three phases: an excitation winding 1 and a phase-adjusting winding 2. Two three-phase reactors 3 are connected in series at both ends of the excitation winding 1 and then connected in a triangle, and three line ends of the three phases are respectively led out and connected to the three phases on the power supply side, and the other end is connected to the phase-adjusting winding 2, one end of the moving contact of the phase-adjusting switch 4 is connected to the phase-adjusting winding 2, and the other end of the moving contact of the phase-adjusting switch 4 is led out of the three phases and connected in series with another three-phase reactor 5, and the three line ends of the three-phase reactor are respectively led out and connected to the three phases on the load side.
[0031] In this embodiment, the excitation winding is connected in a triangle in the existing scheme, directly connected end to end, and three wire ends of the three phases are respectively connected to the three phases on the power supply side, and the other end is connected to the phase-adjusting winding, and the other end of the three phase-adjusting windings is respectively connected to the three phases on the load side. In the technical scheme of the present invention, two three-phase reactors 3 are connected in series at both ends of the excitation winding 1 and then connected in a triangle, and three wire ends of the three phases are respectively connected to the three phases on the power supply side, and the other end is connected to the phase-adjusting winding 2. One end of the moving contact of the phase-adjusting switch 4 is connected to the phase-adjusting winding 2. By changing the position of the moving contact of the phase-adjusting switch 4, the number of turns of the phase-adjusting winding connected in series can be adjusted, and the voltage vectors of different phases and different phase-adjusting levels are connected in series in the current phase, and the voltage vector of the current phase is changed after being synthesized with them, thereby changing the phase shift angle of the phase-shifting transformer. After the other end of the moving contact of the phase-adjusting switch 4 is connected in series with another three-phase reactor, the three wire ends of the three-phase reactor are respectively connected to the three phases on the load side.
[0032] It should be noted that the present invention connects two three-phase reactors 3 in series at both ends of the excitation winding 1, so that the overvoltage from the system will no longer directly impact the excitation winding 1, but will act on the reactor with stronger overvoltage impact resistance, thereby improving the overall ability of the phase-shifting transformer to resist system overvoltage impact. The traditional method is to strengthen the insulation of the excitation winding, which increases the cost, and if the overvoltage amplitude is high, the traditional design method will not be able to effectively guarantee its ability to withstand overvoltage.
[0033] In this embodiment, the present invention also connects a three-phase reactor 5 in series at one end of the moving contact of the phase-shifting switch 4, which is equivalent to connecting a constant impedance in series to the phase-shifting transformer. This can not only reduce the short-circuit impedance design value of the phase-shifting transformer, but also, even when the phase-shifting angle is adjusted to be close to the zero-degree phase-shifting angle, the short-circuit impedance of the phase-shifting transformer is close to zero degrees, because the reactor with constant impedance is always connected in series, it is possible to ensure that there is enough impedance to meet the ability to withstand short circuits. Therefore, this structure can improve the short-circuit resistance of the phase-shifting transformer using a delta connection. The traditional method is to increase the amount of copper used in the winding conductor, which also increases the cost, and is not as economical as this solution.
[0034] Figure 2 The voltage and current vector diagram of the high impedance angle-connected phase-shifting transformer provided in the embodiment of the present application is shown as follows: Figure 2 As shown, according to Figure 1 The wiring schematic diagram shown can obtain the voltage and current vector diagrams on the power supply side and the load side of the phase-shifting transformer, which shows that the load side leads the power supply side in phase angle.
[0035] Among them, Figure 2 The left side shows the voltage vector diagram of the power supply side and the load side of the phase-shifting transformer. SA , U LA Respectively represent the voltage on the power supply side and the load side of phase A, U SB , U LB Respectively represent the voltage on the power supply side and the load side of phase B, U SC , U LC Respectively represent the voltage on the power supply side and the voltage on the load side of phase C; I SA ,I LA Respectively represent the A-phase power supply side current and load side current, I SB ,I LB Respectively represent the B-phase power supply side current and load side current, I SC ,I LC They represent the C-phase power supply side current and load side current respectively.
[0036] It should be noted that for reactors that need to directly withstand the impact of system overvoltage, because they have more turns and smaller diameters, the method of using shielding or tangled structures to increase the longitudinal equivalent capacitance and improve the impulse distribution has less impact on the cost increase than using similar methods on the excitation coil. In addition, since the series-connected reactor increases the impedance of the phase-shifting transformer, it has a fixed impedance value even at zero phase shift angle, thereby improving the overall short-circuit resistance of the phase-shifting transformer. The impact of this method on cost increase is far less than the method of adding conductor copper to the winding.
[0037] Figure 3 , Figure 4The three-phase reactor is placed inside the phase-shifting transformer. The built-in reactor includes a magnetic shielding plate 5, a coil 6, an insulating pressure plate 7, an insulating support plate 8, a clamp screw 9, a support plate 10, a pad 11, and a lead 12. The three-phase reactor is a hollow reactor, with only a coil 6 without an iron core. In order to avoid the influence of the leakage magnetic flux at the end of the coil on the structural parts, magnetic shielding plates 5 are set at the upper and lower ends of the coil. The magnetic shielding plate 5 is composed of stacked iron core sheets. The upper end of the upper magnetic shielding plate 5 is installed with an insulating pressure plate 7 and a support plate 10, and the lower end of the lower magnetic shielding plate 5 is installed with an insulating support plate 8 and a pad 11. The clamp screw 9 fastens the support plate 10, the magnetic shielding plate 5 and the pad 11 together, fixing the three-phase reactor as a whole. At the same time, the upper clamp of the transformer presses the reactor, and the lower clamp supports the reactor, thereby enhancing the stability of the reactor structure.
[0038] Figure 4 In order to ensure that the internal structural parts of the transformer are grounded at one point, it is necessary to reliably connect the structural parts of the clamping frame inside the three-phase reactor with a lead 12 and connect it to the clamp of the transformer at the same time, so that the built-in reactor can be reliably grounded to avoid the generation of internal circulating current and partial discharge inside during operation.
[0039] Figure 5 The phase-shifting transformer has a large capacity and a low line-end voltage, so the current of the phase-adjusting winding is relatively large. Due to the large number of taps of the phase-adjusting lead wire, the leakage flux generated by the same-direction current in the multi-level lead wire will be superimposed on each other. The lead wire is immersed in oil, and the excessive leakage flux will cause overheating of the structural parts and the core sheets. In order to avoid this situation, the phase-adjusting winding is divided into an inner phase-adjusting winding and an outer phase-adjusting winding. The winding directions of the inner and outer phase-adjusting windings are opposite. When the current passes through, the current directions between the two phase-adjusting windings and between the odd and even tapped leads are opposite, which can effectively avoid the superposition of the current of multiple tapped leads, eliminate the leakage flux generated by the synthetic large current tapped leads, and avoid local overheating. At the same time, the tapped leads of the inner and outer phase-adjusting windings have the same label and are at the same end, which is convenient for the connection of the leads.
[0040] Since the phase-modulating winding is directly connected to the line end, when the impulse wave voltage enters the transformer from the line end, it is often accompanied by an oscillation process. An overvoltage higher than the incoming wave amplitude may appear on the phase-modulating winding, and the voltage distribution is uneven. The voltage borne by a certain part of the phase-modulating winding may be very high. Excessive voltage will damage the insulation of the phase-modulating coil turns and the insulation of the tapping lead wire. A ZnO lightning arrester 13 is set between each tapping lead wire of the phase-modulating winding to limit the oscillation potential between taps under impulse voltage.
[0041] Figure 6 The current of the phase-modulating winding is large and the number of leads is large. At the same time, due to the need to connect the leads of the reactor and the excitation winding, a rectangular frame lead clamping structure is adopted. Four lead vertical bars 14 form a rectangular frame structure, such as Figure 7As shown, the stability of the clamping is enhanced. This structure can arrange the leads in layers inside and outside, with the phase-adjusting tap leads arranged in the inner layer and the excitation leads arranged in the outer layer. This arrangement can effectively avoid the crossing of the leads and effectively ensure the insulation distance of the internal leads. Due to space limitations, the phase-adjusting tap leads can be arranged from the inside to the outside, which can reduce the width of the leads, reserve space for the phase-adjusting switch 4, reduce the width of the transformer oil tank, and save the cost of transformer manufacturing.
[0042] Figure 8 The phase-adjusting winding lead of the transformer needs to be connected to the phase-adjusting switch, which is installed in a suspended manner. Due to the limitation of the space of the transformer oil tank, the length of the phase-adjusting switch exceeds the size of the transformer oil tank, and a riser 15 is added to the transformer oil tank. The height dimension of the phase-adjusting switch is increased to ensure the mechanical and insulation distance of the phase-adjusting switch, saving the production cost of the transformer.
[0043] Fig. 9 In order to provide sufficient mechanical support for the transformer body, the transformer body needs to be fixed. Conventional transformers use a structure in which positioning pins are used at the bottom of the box to limit the position or a support plate and a box cover are used to fix the position of the transformer and fix the body. This fixing method can fix the body to a certain extent and meet general conventional transportation requirements. For special products, it may be necessary to lift and replace the transportation equipment several times during transportation. During the entire transportation process, the various connectors of the transformer are subjected to greater stress and are prone to deformation, resulting in problems such as body displacement. A full-length fixing plate 16 is installed at each end of the outer side of the core short shaft. The fixing plate is installed on the webs on both sides. The fixing plate can clamp the core webs to prevent the core sheets from loosening. Several bolts 17 are extended from the oil tank and connected to this fixing plate to fix the transformer body and the oil tank together, which can effectively ensure that the body does not shift and ensure the safety of transformer transportation.
[0044] It should be noted that, in this article, the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise one..." do not exclude the presence of other identical elements in the process, method, article or device including the element. In addition, it should be pointed out that the scope of the methods and devices in the embodiments of the present application is not limited to performing functions in the order shown or discussed, and may also include performing functions in a substantially simultaneous manner or in reverse order according to the functions involved, for example, the described method may be performed in an order different from that described, and various steps may also be added, omitted, or combined. In addition, the features described with reference to certain examples may be combined in other examples.
[0045] The embodiments of the present application are described above in conjunction with the accompanying drawings, but the present application is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present application, ordinary technicians in this field can also make many forms without departing from the purpose of the present application and the scope of protection of the claims, all of which are within the protection of the present application.
Claims
1. A high impedance angle-connected phase-shifting transformer, characterized in that: The high impedance angle-connected phase-shifting transformer is a three-column iron core structure, and an excitation winding and a phase-adjusting winding are sleeved on each phase iron core column of the three phases; Two ends of the excitation winding are respectively connected in series with two three-phase reactors to form a triangle connection, and the third end of the excitation winding is connected to the phase-adjusting winding; The high impedance angle-connected phase-shifting transformer further comprises a phase-adjusting switch, one end of a moving contact of the phase-adjusting switch is connected to the phase-adjusting winding, and the other end of the moving contact of the phase-adjusting switch is connected in series with a third three-phase reactor after three-phase extraction; The phase angle between the voltage on the power supply side and the voltage on the load side is changed by adjusting the number of coil turns of the phase-adjusting winding connected to the circuit through the phase-adjusting switch, thereby realizing the loop closing and power flow control of the high-impedance angle-connected phase-shifting transformer.
2. The high impedance angle-connected phase-shifting transformer according to claim 1, characterized in that: The three phases of the excitation winding are respectively led out to three wire ends which are respectively connected to the three phases on the power supply side.
3. The high impedance angle-connected phase-shifting transformer according to claim 1, characterized in that: The three line terminals of the third three-phase reactor are respectively led out and connected to the three phases on the load side.
4. The high impedance angle-connected phase-shifting transformer according to claim 1, characterized in that: Three reactors are located inside the high-impedance angle-connected phase-shifting transformer as built-in reactors.
5. The high impedance angle-connected phase-shifting transformer according to claim 4, characterized in that: The built-in reactor is an air-core reactor.
6. The high impedance angle-connected phase-shifting transformer according to claim 5, characterized in that: The built-in inductor includes a coil, magnetic shielding plates arranged at the upper and lower ends of the coil, an insulating pressure plate and a support plate installed at the upper end of the upper magnetic shielding plate, and an insulating support plate and a pad installed at the lower end of the lower magnetic shielding plate. The support plate, magnetic shielding plate and pad are fastened together up and down by clamp screws to fix the three-phase inductor as a whole.
7. The high impedance angle-connected phase-shifting transformer according to claim 5, characterized in that: The phase-adjusting winding comprises an inner phase-adjusting winding and an outer phase-adjusting winding, wherein the inner and outer phase-adjusting windings are wound in opposite directions.
8. The high impedance angle-connected phase-shifting transformer according to claim 1, characterized in that: The high impedance delta phase-shifting transformer further comprises a ZnO lightning arrester arranged between each tap lead of the phase-modulating winding.
9. The high impedance angle-connected phase-shifting transformer according to claim 5, characterized in that: The lead wires between the excitation winding and the three-phase reactor adopt a rectangular frame type lead wire clamping structure.
10. The high impedance angle-connected phase-shifting transformer according to claim 9, characterized in that: The rectangular frame type lead clamping structure arranges the leads in layers inside and outside, wherein the phase adjustment tapping leads are arranged in the inner layer and the excitation leads are arranged in the outer layer.