Flexible ac transmission system transformer with auxiliary winding and flexible ac transmission system

Abstract

The utility model relates to a kind of flexible direct current transformer and flexible direct current transformation system with auxiliary winding, and the transformer includes: iron core, net side winding module, valve side winding module and auxiliary winding module. Among them, iron core is three-phase five-column type;Valve side winding module, winding is on iron core, including three-phase decoupling valve side winding, the A phase valve side bushing group connected with the A phase of valve side winding, the B phase valve side bushing group connected with the B phase of valve side winding and the C phase valve side bushing group connected with the C phase of valve side winding;Auxiliary winding module, winding is on iron core, including three-column series connection auxiliary winding, the first auxiliary bushing connected with auxiliary winding first end and the second auxiliary bushing connected with auxiliary winding second end, for testing the single-phase short-circuit impedance value of valve side winding.The flexible direct current transformer realizes the short-circuit impedance measurement of simple and reliable valve side winding, without additional transformer bushing, avoid the short-circuit risk when leading out multiple bushings.

Description

Technical Field

[0001] This utility model relates to the field of transformer technology, and in particular to a flexible DC transformer with auxiliary winding and a flexible DC transformer system. Background Technology

[0002] Currently, my country's traditional power system is evolving into a new type of power system that is clean and low-carbon, safe and controllable, flexible and efficient, open and interactive, and intelligent and user-friendly. Flexible DC transmission technology is being increasingly adopted in the consumption of new energy sources and the construction of smart grids. With the application of new converter valves, the development of control technology, and the continuous upgrading of converter topology, the operating conditions of flexible DC transformers used in flexible DC transmission systems are becoming increasingly complex.

[0003] In a novel flexible DC transmission system, the flexible DC transformer needs to withstand a large number of harmonics with diverse phases. An auxiliary winding is configured to meet low-voltage ride-through transient conditions, and the impedance value of the auxiliary winding is subject to limitations imposed by the valve-side winding of each phase. However, traditional transformers cannot meet the requirements of this novel flexible DC transmission system, and multiple sets of leads are needed for the auxiliary winding to measure the aforementioned impedance values. Utility Model Content

[0004] Therefore, it is necessary to provide a flexible DC transformer and flexible DC transformer system with auxiliary winding that can meet the requirements of new flexible DC transmission systems and realize the test measurement of the single-phase short-circuit impedance of the auxiliary winding to the valve-side winding, so as to ensure the reliability of the flexible DC transformer.

[0005] In a first aspect, this utility model provides a flexible DC transformer with an auxiliary winding, the transformer comprising:

[0006] The iron core is a three-phase, five-limb type, used to transmit and convert electromagnetic energy in a flexible DC transformer.

[0007] The wire-side winding module is wound around the iron core;

[0008] The valve-side winding module, wound on the iron core, includes a three-phase decoupled valve-side winding, an A-phase valve-side bushing group connected to the A phase of the valve-side winding, a B-phase valve-side bushing group connected to the B phase of the valve-side winding, and a C-phase valve-side bushing group connected to the C phase of the valve-side winding.

[0009] The auxiliary winding module, wound on the iron core, includes a three-column series auxiliary winding, a first auxiliary sleeve connecting the first end of the auxiliary winding, and a second auxiliary sleeve connecting the second end of the auxiliary winding.

[0010] In one embodiment, the wire-side winding module includes: a wire-side winding, a first wire-side bushing, a second wire-side bushing, and a third wire-side bushing;

[0011] The three phases of the grid-side winding are connected in a star configuration, and the first grid-side bushing, the second grid-side bushing, and the third grid-side bushing are respectively connected to the first end of the grid-side winding.

[0012] In one embodiment, the core includes: core upper and lower yokes, core side posts and core main posts;

[0013] The cross-sectional area of ​​the upper and lower yokes of the iron core is equal to the cross-sectional area of ​​the iron core side column, and the cross-sectional area of ​​the upper and lower yokes of the iron core is 75%-100% of the cross-sectional area of ​​the iron core main column.

[0014] In one embodiment, the A-phase valve-side bushing assembly includes a first valve-side bushing and a second valve-side bushing. The first valve-side bushing is connected to the first end of the A-phase of the valve-side winding, and the second valve-side bushing is connected to the second end of the A-phase of the valve-side winding.

[0015] The B-phase valve side bushing assembly includes a third valve side bushing and a fourth valve side bushing. The third valve side bushing is connected to the first end of the B-phase of the valve side winding, and the fourth valve side bushing is connected to the second end of the B-phase of the valve side winding.

[0016] The C-phase valve-side bushing assembly includes a fifth valve-side bushing and a sixth valve-side bushing. The fifth valve-side bushing is connected to the first end of the C-phase of the valve-side winding, and the sixth valve-side bushing is connected to the second end of the C-phase of the valve-side winding.

[0017] In one embodiment, the first valve-side bushing and the sixth valve-side bushing are short-circuited, the second valve-side bushing and the third valve-side bushing are short-circuited, and the fourth valve-side bushing and the fifth valve-side bushing are short-circuited to achieve a series short circuit of the valve-side windings.

[0018] In one embodiment, the auxiliary winding module is also used to measure and acquire the short-circuit impedance data of phases A, B, and C of the valve-side winding to the auxiliary winding, and to acquire the single-phase short-circuit impedance value of the valve-side winding based on the short-circuit impedance data.

[0019] In one embodiment, the short-circuit impedance data is three times the single-phase short-circuit impedance value.

[0020] In one embodiment, the auxiliary winding module further includes a test power supply, with a first end connected to a first auxiliary bushing and a second end connected to a second auxiliary bushing.

[0021] In one embodiment, the three-column series auxiliary winding includes a first column winding, a second column winding, and a third column winding;

[0022] The first end of the first column winding is connected to the second end of the third column winding, the second end of the first column winding is connected to the first end of the second column winding, the second end of the second column winding is connected to the first auxiliary bushing, and the first end of the third column winding is connected to the second auxiliary bushing.

[0023] Secondly, this utility model also provides a flexible DC transformer system, which includes the flexible DC transformer in any of the embodiments of the first aspect described above.

[0024] The aforementioned flexible DC transformer, through three auxiliary windings connected in series, changes the magnetic flux path of a three-phase transformer to that of a single-phase transformer, enabling the measurement of the short-circuit impedance of the auxiliary winding to the valve-side winding. This provides a simple, easy-to-operate, and reliable method for measuring the short-circuit impedance of the valve-side winding, eliminating the need for additional transformer bushings and avoiding the short-circuit risk associated with multiple bushing leads. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a flexible DC transformer structure according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram illustrating the wiring principle of the grid-side winding, valve-side winding, and auxiliary winding in one embodiment;

[0028] Figure 3 This is a schematic diagram of the core structure in one embodiment;

[0029] Figure 4 This is a schematic diagram of the magnetic flux distribution of the iron core in one embodiment;

[0030] Figure 5 This is a wiring diagram of the valve-side sleeve in one embodiment.

[0031] Explanation of reference numerals in the attached figures:

[0032] 10. Core; 110. Core upper and lower yokes; 120. Core side post; 130. Core main post; 20. Wire side winding module; 210. First wire side bushing; 220. Second wire side bushing; 230. Third wire side bushing; 30. Valve side winding module; 310. A-phase valve side bushing group; 311. First valve side bushing; 312. Second valve side bushing; 320. B-phase valve side bushing group; 321. Third valve side bushing; 322. Fourth valve side bushing; 330. C-phase valve side bushing group; 331. Fifth valve side bushing; 332. Sixth valve side bushing; 40. Auxiliary winding module; 410. First auxiliary bushing; 420. Second auxiliary bushing. Detailed Implementation

[0033] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0034] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0035] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0036] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0037] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. When used here, the singular forms "a," "an," and " / the" may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms "including / comprises" or "having," etc., specify the presence of the stated feature, whole, step, operation, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof.

[0038] Flexible DC transmission technology, as a key supporting technology for the construction of new power systems, is undergoing a dual transformation of equipment innovation and system reconfiguration. With the large-scale application of new power electronic converter devices and the iterative upgrading of multi-dimensional control strategies, the transmission system is showing a deep integration of power electronics and digitalization, which places stringent requirements on core equipment to adapt to complex operating conditions.

[0039] Under this trend of technological evolution, flexible DC transformers, as the core hub for AC / DC energy conversion, face new challenges in electromagnetic structure design and dynamic characteristic matching: they need to cope with the complex harmonic environment caused by the access of new energy power plants, especially the composite electrical stress formed by the superposition of specific harmonic orders and fundamental waves; and they need to meet the special requirements of multi-winding decoupled operation under the new topology structure, so as to realize the coordinated control of the main circuit and auxiliary circuit in the transient process.

[0040] Flexible DC transmission systems use flexible DC transformers that need to withstand the third harmonic in phase with the fundamental wave. Traditional transformer winding coupling methods and impedance configuration schemes are no longer suitable for the architecture of independent decoupled three-phase outputs on the valve side and dynamic series connection of auxiliary windings. Systematic breakthroughs are urgently needed in magnetic circuit design, winding arrangement and impedance setting to ensure the stable operation of the equipment in complex electromagnetic environments such as harmonic penetration and voltage drop.

[0041] Based on this, the present invention provides a flexible DC transformer with an auxiliary winding, which can realize the test measurement of the single-phase short-circuit impedance of the auxiliary winding to the valve-side winding in a three-phase series structure, thus ensuring the reliability of the transformer product.

[0042] In one exemplary embodiment, such as Figure 1 As shown, a flexible DC transformer with an auxiliary winding is provided. The transformer includes: a core 10, a grid-side winding module 20, a valve-side winding module 30, and an auxiliary winding module 40.

[0043] Iron core 10, the iron core is a three-phase five-column type.

[0044] Optionally, the transformer uses a three-phase five-limb iron core 10 as the core magnetic circuit carrier. The iron core 10 adopts a five-limb symmetrical arrangement structure, with the three middle limbs carrying the three-phase main magnetic flux respectively, and the side limbs forming a low magnetic reluctance closed path, which effectively improves the local magnetic saturation problem caused by harmonic current and ensures the stable operation of the transformer under the superposition of fundamental and harmonics; at the same time, it provides an independent magnetic circuit channel for the valve-side winding module 30 and the auxiliary winding module 40.

[0045] The wire-side winding module 20 is wound around the iron core 10.

[0046] Optionally, the grid-side winding module 20 is wound on the iron core 10 and can adopt a multi-layer pancake winding structure, arranged in layers along the iron core axis. It is flexibly connected to the AC power grid through a star connection and has the ability to adapt to voltage fluctuations in a wide frequency range, and is used to receive electrical energy input from the AC power grid.

[0047] The valve-side winding module 30, wound on the core 10, includes a three-phase decoupled valve-side winding, an A-phase valve-side bushing group 310 connected to the A phase of the valve-side winding, a B-phase valve-side bushing group 320 connected to the B phase of the valve-side winding, and a C-phase valve-side bushing group 330 connected to the C phase of the valve-side winding, used to convert the AC current of the flexible DC transformer into DC current.

[0048] Optionally, the valve-side winding module 30 is wound on the iron core 10, adopting a three-phase decoupling design. Each phase winding is independently wound and led out separately to ensure that the electromagnetic characteristics of each phase do not interfere with each other. Each bushing integrates an equalizing ring and a shielding electrode structure to ensure the uniformity of the electric field distribution under high-order harmonic environments. Among them, the A-phase valve-side bushing group 310, the B-phase valve-side bushing group 320, and the C-phase valve-side bushing group 330 are respectively connected to the three-phase valve-side windings, forming independent electrical paths to meet the independent conversion requirements of the converter valve for three-phase AC current. The valve-side winding can adopt a multi-split conductor parallel structure to reduce circulating current losses under AC / DC combined operating conditions. At the same time, the equivalent series inductance is optimized by axial staggered winding to improve the smoothness of DC current.

[0049] The auxiliary winding module 40, wound on the iron core 10, includes a three-column series auxiliary winding, a first auxiliary bushing 410 connected to the first end of the auxiliary winding, and a second auxiliary bushing 420 connected to the second end of the auxiliary winding, used to test the single-phase short-circuit impedance value of the valve-side winding.

[0050] Optionally, the auxiliary winding module 40 is wound on the core 10, adopting a three-column series structure, connecting the three-phase auxiliary windings end to end to form a closed loop. This module is led out through the first auxiliary bushing 410 and the second auxiliary bushing 420, and can be dynamically connected in series to the transformer system under low voltage ride-through transient conditions to provide voltage support; through the magnetic field coupling effect, it realizes the single-phase short-circuit impedance test of the valve-side winding, simplifying the test process and improving the measurement accuracy.

[0051] For example, such as Figure 2 The diagram shows the wiring schematics of the grid-side winding, valve-side winding, and auxiliary winding. In the grid-side wiring schematic, O, A, B, and C represent the voltage reference point, phase A, phase B, and phase C, respectively. In the valve-side winding wiring schematic, a, b, and c represent the three phases of the three-phase voltage, and x, y, and z represent the three phases of the corresponding three-phase load. In the auxiliary winding wiring schematic, Fa, Fb, Fc, Fx, Fy, and Fz are all phases of the auxiliary winding; Fx is connected to Fb, and Fa is connected to Fz, achieving three-phase series connection of the auxiliary winding. By connecting the valve-side winding in series, the magnetic flux distribution of the transformer is changed, establishing a new electromagnetic induction relationship between the valve-side winding and the auxiliary winding, achieving voltage conversion between them, and thus realizing the measurement of the short-circuit voltage value.

[0052] The aforementioned flexible DC transformer, through a three-column series-connected auxiliary winding module 40, establishes a phase impedance test channel with the valve-side winding via magnetic field coupling, enabling accurate measurement of single-phase short-circuit impedance and providing a controllable series access point for dynamic voltage compensation under low-voltage ride-through conditions. Its auxiliary winding is a three-phase series connection, with one bushing at each end connected to an external AC switch. During steady-state operation, the AC switch is off, and the auxiliary winding is open, not participating in operation. During low-voltage ride-through, the AC switch is closed, and the three phases of the auxiliary winding are connected in a delta configuration, participating in operation and providing a path for the third harmonic current. The modules decouple energy transmission and signal detection functions through directional control of the core magnetic circuit. By optimizing the core structure, winding arrangement, and auxiliary function design, the harmonic tolerance, three-phase decoupled operation stability, and transient condition adaptability are effectively improved. A simple, reliable method for measuring the short-circuit impedance of the valve-side winding is provided, eliminating the need for additional transformer bushings and avoiding the short-circuit risk associated with multiple bushing leads.

[0053] In one exemplary embodiment, such as Figure 1 As shown, the grid-side winding module 20 includes: a grid-side winding, a first grid-side bushing 210, a second grid-side bushing 220, and a third grid-side bushing 230.

[0054] The three phases of the grid-side winding are connected in a star configuration, and the first grid-side bushing 210, the second grid-side bushing 220 and the third grid-side bushing 230 are respectively connected to the first end of the grid-side winding.

[0055] For example, the grid-side windings can adopt a multi-layer disc winding process, with each phase winding symmetrically distributed along the core axis. Optimized interlayer insulation structure ensures reliable operation under high-voltage alternating electric fields. The neutral point of the three-phase windings uses an internal short-circuit copper busbar to form a stable star connection topology, effectively suppressing the influence of zero-sequence components caused by three-phase imbalance. The first grid-side bushing 210, the second grid-side bushing 220, and the third grid-side bushing 230 are reliably connected to the beginning of the three-phase windings. Each bushing adopts a composite insulator structure, with an equalizing shielding layer between the internal conductive rod and the external porcelain sleeve to improve the uniformity of the electric field distribution at the bushing ends.

[0056] In the above embodiments, the grid-side winding module 20 is optimized through electromagnetic-thermal coupling design, which enables it to maintain excellent heat dissipation performance and mechanical stability under complex working conditions containing harmonics.

[0057] The following embodiments illustrate the theoretical basis of magnetic flux for short-circuit impedance measurement of this utility model.

[0058] In one exemplary embodiment, such as Figure 3 As shown, the core 10 includes: core upper and lower yokes 110, core side columns 120 and core main columns 130.

[0059] The cross-sectional area of ​​the upper and lower yokes 110 of the core is equal to the cross-sectional area of ​​the side column 120 of the core, and the cross-sectional area of ​​the upper and lower yokes 110 of the core is 75%-100% of the cross-sectional area of ​​the main column 130 of the core.

[0060] For example, the magnetic flux distribution of the iron core 10 is as follows: Figure 4 As shown, the arrows indicate the direction of magnetic flux. The magnetic flux in the main core column 130 is all in the same direction, while the magnetic flux in the upper and lower core yokes 110 and the side core columns 120 is 1.5 times that in the main core column 130. In the yoke-enhanced core, the cross-sectional area of ​​the upper and lower core yokes 110 is 75%-100% of the cross-sectional area of ​​the main core column 130, ensuring that the sum of the cross-sectional areas of the upper and lower core yokes 110 and the side core columns 120 is more than 1.5 times the cross-sectional area of ​​the main core column 130, thus satisfying the magnetic flux requirement. The core 10 still operates in the magnetic flux unsaturation region. Each core component can be made of high-permeability oriented silicon steel sheets, stacked using a slanted joint process. Laser treatment technology is used at the joints to reduce hysteresis loss.

[0061] In one exemplary embodiment, such as Figure 1 As shown, the A-phase valve-side bushing assembly 310 includes a first valve-side bushing 311 and a second valve-side bushing 312. The first valve-side bushing 311 is connected to the first end of the A-phase of the valve-side winding, and the second valve-side bushing 312 is connected to the second end of the A-phase of the valve-side winding.

[0062] The B-phase valve-side bushing assembly 320 includes a third valve-side bushing 321 and a fourth valve-side bushing 322. The third valve-side bushing 321 is connected to the first end of the B-phase of the valve-side winding, and the fourth valve-side bushing 322 is connected to the second end of the B-phase of the valve-side winding.

[0063] The C-phase valve-side bushing assembly 330 includes a fifth valve-side bushing 331 and a sixth valve-side bushing 332. The fifth valve-side bushing 331 is connected to the first end of the C-phase of the valve-side winding, and the sixth valve-side bushing 332 is connected to the second end of the C-phase of the valve-side winding.

[0064] For example, each valve-side bushing group adopts a symmetrical double-bushing design, providing an independent input and output channel for each phase valve-side winding, ensuring complete decoupling of the current path. The A-phase valve-side bushing group 310 includes a first valve-side bushing 311 and a second valve-side bushing 312. The first valve-side bushing 311 is connected to the first end (head end) of the A-phase winding of the valve-side winding through a copper-aluminum composite transition joint to achieve low contact resistance. Its internal multi-layer umbrella skirt structure optimizes the surface electric field distribution. The second valve-side bushing 312 is connected to the second end (end end) of the A-phase winding with the same specifications. The two bushings are arranged symmetrically at 180° to form a balanced electromagnetic field structure.

[0065] Phase B valve-side bushing assembly 320 consists of a third valve-side bushing 321 and a fourth valve-side bushing 322. An equalizing ring is provided at the connection between the third valve-side bushing 321 and the first end of phase B to effectively suppress partial discharge; the fourth valve-side bushing 322 adopts a structural design that is mirror-symmetrical to the third valve-side bushing 321, and a specific spatial distance is maintained between the two bushings to avoid interphase interference.

[0066] The C-phase valve-side bushing assembly 330 includes a fifth valve-side bushing 331 and a sixth valve-side bushing 332. The fifth valve-side bushing 331 is connected to the first end of the C-phase using a spring-loaded contact finger connection structure to ensure reliable contact during long-term operation. All valve-side bushings are integrally cast from composite insulating material, with an UV-resistant coating on their outer surface to improve weather resistance for outdoor operation. The bushing assemblies are arranged in a three-dimensional staggered pattern, ensuring sufficient electrical safety distances while optimizing the overall compactness of the transformer structure.

[0067] The following examples illustrate the principle of short-circuit impedance measurement using this flexible DC transformer.

[0068] In one exemplary embodiment, such as Figure 5 As shown, the first valve-side bushing 311 and the sixth valve-side bushing 332 are short-circuited, the second valve-side bushing 312 is short-circuited with the third valve-side bushing 321, and the fourth valve-side bushing 322 is short-circuited with the fifth valve-side bushing 331 to achieve a series short circuit of the valve-side windings.

[0069] In one exemplary embodiment, such as Figure 1 As shown, the auxiliary winding module 40 is also used to measure and acquire the short-circuit impedance data of phases A, B, and C of the valve-side winding to the auxiliary winding, and to acquire the single-phase short-circuit impedance value of the valve-side winding based on the short-circuit impedance data.

[0070] In one exemplary embodiment, the short-circuit impedance data is three times the single-phase short-circuit impedance value.

[0071] In an exemplary embodiment, the auxiliary winding module 40 further includes a test power supply, with a first end connected to a first auxiliary sleeve 410 and a second end connected to a second auxiliary sleeve 420.

[0072] For example, the above wiring structure forms a complete series short-circuit loop for the three-phase valve-side windings. By changing the three-phase connection method of the valve-side windings, the magnetic flux path of the transformer is changed, transforming the magnetic flux path of the three-phase transformer into that of a single-phase transformer. Voltage is applied to the valve-side windings or auxiliary windings to obtain the measured impedance voltage value. In this measurement method, the number of turns in the transformer's valve-side windings and auxiliary windings increases by three times, so the measured impedance voltage value needs to be converted to the impedance voltage value of a single-phase valve-side winding and auxiliary winding by a factor of 1 / 3. This testing method avoids the multiple disconnection and reconnection operations required for traditional single-phase testing, significantly improving testing efficiency and measurement accuracy, and is particularly suitable for on-site commissioning and maintenance testing.

[0073] In one exemplary embodiment, such as Figure 2 As shown, the auxiliary winding connected in series with three columns includes a first column winding, a second column winding, and a third column winding.

[0074] The first end Fa of the first column winding is connected to the second end Fz of the third column winding, the second end Fx of the first column winding is connected to the first end Fb of the second column winding, the second end Fy of the second column winding is connected to the first auxiliary bushing 410, and the first end Fc of the third column winding is connected to the second auxiliary bushing 420, so as to realize the three-phase series connection of the auxiliary windings.

[0075] In the above embodiments, by connecting the valve-side windings in series, the magnetic flux distribution of the transformer is changed, and a new electromagnetic induction relationship is established between the valve-side windings and the auxiliary windings, thereby realizing voltage conversion between the two and achieving short-circuit voltage measurement.

[0076] In one exemplary embodiment, the present invention also provides a flexible DC transformer system, which includes the flexible DC transformer described in any of the above embodiments.

[0077] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0078] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0079] The above embodiments only illustrate several implementation methods of this utility model, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A flexible DC transformer with an auxiliary winding, characterized in that, include: The core, which is a three-phase five-limb type, is used to transmit and convert electromagnetic energy in the flexible DC transformer; The wire-side winding module is wound around the iron core; The valve-side winding module, wound on the iron core, includes a three-phase decoupled valve-side winding, an A-phase valve-side bushing group connected to the A phase of the valve-side winding, a B-phase valve-side bushing group connected to the B phase of the valve-side winding, and a C-phase valve-side bushing group connected to the C phase of the valve-side winding. The auxiliary winding module, wound on the iron core, includes a three-column series auxiliary winding, a first auxiliary sleeve connecting the first end of the auxiliary winding, and a second auxiliary sleeve connecting the second end of the auxiliary winding.

2. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The wire-side winding module includes: a wire-side winding, a first wire-side bushing, a second wire-side bushing, and a third wire-side bushing; The three phases of the grid-side winding are connected in a star configuration, and the first grid-side bushing, the second grid-side bushing, and the third grid-side bushing are respectively connected to the first end of the grid-side winding.

3. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The core includes: upper and lower yokes, side columns, and main columns. The cross-sectional area of ​​the upper and lower yokes of the core is equal to the cross-sectional area of ​​the side column of the core, and the cross-sectional area of ​​the upper and lower yokes of the core is 75%-100% of the cross-sectional area of ​​the main column of the core.

4. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The A-phase valve-side bushing assembly includes a first valve-side bushing and a second valve-side bushing. The first valve-side bushing is connected to the first end of the A-phase of the valve-side winding, and the second valve-side bushing is connected to the second end of the A-phase of the valve-side winding. The B-phase valve-side bushing assembly includes a third valve-side bushing and a fourth valve-side bushing. The third valve-side bushing is connected to the first B-phase end of the valve-side winding, and the fourth valve-side bushing is connected to the second B-phase end of the valve-side winding. The C-phase valve-side bushing assembly includes a fifth valve-side bushing and a sixth valve-side bushing. The fifth valve-side bushing is connected to the first end of the C-phase of the valve-side winding, and the sixth valve-side bushing is connected to the second end of the C-phase of the valve-side winding.

5. The flexible DC transformer with auxiliary winding according to claim 4, characterized in that, The first valve-side bushing and the sixth valve-side bushing are short-circuited, the second valve-side bushing and the third valve-side bushing are short-circuited, and the fourth valve-side bushing and the fifth valve-side bushing are short-circuited, so as to realize the series short circuit of the valve-side winding.

6. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The auxiliary winding module is also used to measure and obtain the short-circuit impedance data of phases A, B, and C of the valve-side winding to the auxiliary winding, and to obtain the single-phase short-circuit impedance value of the valve-side winding based on the short-circuit impedance data.

7. The flexible DC transformer with auxiliary winding according to claim 6, characterized in that, The short-circuit impedance data is three times the single-phase short-circuit impedance value.

8. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The auxiliary winding module also includes a test power supply, with a first end connected to the first auxiliary bushing and a second end connected to the second auxiliary bushing.

9. The flexible DC transformer with auxiliary winding according to claim 1, characterized in that, The auxiliary winding connected in series with three columns includes a first column winding, a second column winding, and a third column winding; The first end of the first column winding is connected to the second end of the third column winding, the second end of the first column winding is connected to the first end of the second column winding, the second end of the second column winding is connected to the first auxiliary sleeve, and the first end of the third column winding is connected to the second auxiliary sleeve.

10. A flexible DC transformer system with auxiliary windings, characterized in that, The flexible DC transformer with auxiliary winding as described in any one of claims 1-9.

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