CN115331930B - Magnetic integration hybrid distribution transformer with simple structure - Google Patents

Abstract

The invention relates to a magnetic integration hybrid distribution transformer with a simple structure, and belongs to the technical field of transformers. The magnetically integrated hybrid distribution transformer includes a magnetic core structure and windings; the magnetic core structure comprises a main magnetic core and an auxiliary magnetic core, the main magnetic core comprises iron core columns and iron yokes, the iron core columns are longitudinally arranged, and windings are respectively arranged on the iron core columns; the auxiliary magnetic core comprises independent square hollow magnetic rings, and a hollow window is formed in the center of each magnetic ring; the windings comprise a high-voltage winding, a low-voltage winding and an auxiliary winding which are arranged on the iron core limb; each phase auxiliary winding is positioned above the high-voltage winding and the low-voltage winding of the phase, passes through the window of the phase auxiliary magnetic core and is wound on the core limb of the phase main magnetic core. The magnetic integrated hybrid distribution transformer has the advantages of simple structure, reduced number of discrete magnetic elements, simplified integral structure of the device, saved space required by the design of heat dissipation of the filter inductor of the transformer, and reduced volume of the hybrid distribution transformer.

Description

A magnetically integrated hybrid distribution transformer with simple structure

Technical field

The invention belongs to the technical field of transformers, and in particular relates to a magnetically integrated hybrid distribution transformer with a simple structure.

Background technique

At present, distribution transformers in distribution networks are still the most important electrical equipment for voltage conversion and power distribution, but they lack the ability to actively manage and control distributed power sources and loads as energy hubs. In this context, relevant research institutes and scientific and technological workers have proposed the concept of hybrid distribution transformers. The so-called hybrid distribution transformer is a new type of controllable distribution transformer that is realized by improving the design of the traditional distribution transformer and then integrating fully controllable power electronic devices into it. Compared with traditional distribution transformers, hybrid distribution transformers not only have the advantages of high efficiency and reliability of traditional distribution transformers, but also can greatly improve the controllability of traditional distribution transformers. Therefore, they are very suitable for the development needs of intelligent distribution networks in the future.

The hybrid distribution transformer in the prior art includes a magnetically integrated hybrid distribution transformer including a main transformer, a series isolation transformer, and a converter unit. In this structure, the main transformer and the series isolation transformer share a central iron yoke to achieve isolation between the main transformer and the series isolation transformer. Weak coupling integration of the transformer; leakage magnetic cores are arranged between the primary winding and the control winding and between the valve side winding and the grid side winding, which increases the leakage inductance between the corresponding windings. Transformers and converters are realized by replacing inductance with leakage inductance Magnetic integrated design for output connection inductor. However, this structure has two disadvantages:

1. This structure uses a series isolation transformer, with a large number of windings, and the overall structure of the device is still relatively complex;

2. In order to achieve magnetic integration, this structure arranges leakage magnetic cores between the primary winding and the control winding and between the valve side winding and the grid side winding. A total of at least 6 are required for the three phases, and the number of discrete magnetic components is still relatively large. The loss is large; in this structure, the leakage inductance needs to be adjusted by adjusting the air gap between the leakage magnetic core and the iron yoke in the control winding and the valve side winding. The adjustment method is not simple and the adjustment range is small.

Contents of the invention

The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and provide a magnetically integrated hybrid distribution transformer with a simple structure, which can reduce the number of discrete magnetic components, simplify the overall structure of the device, and eliminate the need for heat dissipation design of the converter filter inductor. The required space is reduced and the size of the hybrid distribution transformer is reduced.

According to one aspect of the present invention, the present invention provides a magnetically integrated hybrid distribution transformer with a simple structure. The magnetically integrated hybrid distribution transformer includes a transformer unit, and the transformer unit includes a magnetic core structure and windings; the magnetic core The structure includes a main magnetic core and an auxiliary magnetic core. The main magnetic core includes an iron core pillar and an iron yoke. The iron core pillars are arranged longitudinally, and windings are respectively provided on the iron core pillars. The iron yoke is arranged between the iron core pillars. The space is used to fix the iron core column; the auxiliary magnetic core includes an independent square hollow magnetic ring, and a hollow window is formed in the center of each magnetic ring; the winding includes a high-voltage winding, a low-voltage winding and an auxiliary winding arranged on the iron core column. Windings; the windings are arranged on the core pillar in sequence from left to right in the order of A phase, B phase, and C phase; each phase auxiliary winding is located above the high voltage winding and low voltage winding of the current phase, passing through the auxiliary core of the current phase The window is wound on the core pillar of the original main magnetic core.

Preferably, the high-voltage winding and the low-voltage winding of each phase winding are concentrically wound on the main magnetic core core leg of the current phase using layered coils, and the low-voltage winding, the high-voltage winding and the high-voltage winding are arranged in sequence from the core leg outward. winding.

Preferably, the leakage inductance between the auxiliary winding of each phase and the high-voltage winding of each phase is adjusted by adjusting the distance between the auxiliary winding of each phase and the high-voltage winding of each phase.

Preferably,

An auxiliary magnetic core is wound between the auxiliary winding of each phase and the high-voltage winding of each phase to form a new magnetic flux path, thereby increasing the leakage inductance between the high-voltage winding of each phase and the auxiliary winding of each phase.

Preferably,

The auxiliary magnetic core has three independent phases, and the size and material of each phase of the auxiliary magnetic core are determined according to the required leakage inductance frequency and leakage inductance value.

Preferably,

The iron yokes are arranged in two groups, and the two groups of iron yokes are respectively arranged at the upper end and the lower end of the main magnetic core core pillar; the iron yoke and the main magnetic core core pillar in the magnetic core structure are overlapped with a 45-degree oblique joint step splicing method; each level of lamination of the iron core structure is made of silicon steel sheets.

Preferably, the magnetically integrated hybrid distribution transformer includes a converter unit connected to the auxiliary winding of each phase and the low-voltage winding of each phase.

Preferably, the converter unit includes:

AC-DC converter, DC-AC converter, DC bus capacitor, filter inductor and three-phase four-wire AC voltage filter shared by the AC-DC converter and the DC-AC converter.

Preferably, the AC-DC converter includes a parallel current control bridge arm; the DC-AC converter includes a parallel voltage control bridge arm and a zero sequence control bridge arm; the filter inductor is connected to the DC-AC After the bridge arm of the converter is output, the rear end of the filter inductor connected after the voltage control bridge arm is the three-phase voltage output end of the converter unit, and the filter inductor connected after the zero sequence control bridge arm is The rear end is the zero-sequence output terminal of the converter unit; the three-phase four-wire AC voltage filter is connected in parallel between the three-phase voltage output terminal and the zero-sequence output terminal of the converter unit; the auxiliary winding and The midpoint of the current control bridge arm is connected, the low-voltage winding is connected to the three-phase voltage output end of the converter unit, and the zero-sequence output end of the converter unit is connected to the neutral line of the three-phase four-wire load.

Preferably,

The high-voltage winding is connected to the power grid through a delta connection, the low-voltage winding is connected to a three-phase four-wire load and each phase voltage output end of the converter unit, and the auxiliary winding is connected to the converter through a delta connection. connected to the current output end of the converter unit.

Beneficial effects: The present invention adopts a structure in which the high-voltage winding and the low-voltage winding are wound concentrically on the same core column and the auxiliary winding is wound separately, which increases the distance between the auxiliary winding and the high-voltage winding and increases the distance between the high-voltage winding and the auxiliary winding. leakage inductance. This structure can increase the leakage inductance while keeping the structure compact, and facilitate the magnetic integration of the filter inductor and the winding leakage inductance. At the same time, the leakage inductance can be adjusted conveniently and flexibly by adjusting the distance between the auxiliary winding and the high-voltage winding; Adding an auxiliary magnetic core between the winding and the low-voltage winding increases the leakage inductance between the high-voltage winding and the low-voltage winding of the transformer, eliminating the need for a filter inductor connecting the auxiliary winding of the converter, realizing magnetic integration of the converter filter inductor and the transformer winding, which can reduce The number of discrete magnetic components simplifies the overall structure of the device. In addition, the auxiliary magnetic core can dissipate heat together with the main magnetic core, eliminating the space required for heat dissipation design of the converter filter inductor and reducing the overall volume of the hybrid distribution transformer.

The features and advantages of the present invention will become apparent with reference to the following drawings and detailed description of specific embodiments of the invention.

Description of drawings

Figure 1(a), Figure 1(b), and Figure 1(c) are schematic diagrams of the circuit topology and connection relationships of each component of the main circuit in the magnetically integrated hybrid distribution transformer of the present invention;

Figure 2 is a three-dimensional view of the electromagnetic body of the magnetically integrated hybrid distribution transformer of the present invention.

Figure 3 is an electromagnetic simulation result diagram of the magnetically integrated hybrid distribution transformer of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention are clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

The invention provides a magnetically integrated hybrid distribution transformer with a simple structure. The magnetically integrated hybrid distribution transformer includes a transformer unit, and the transformer unit includes a magnetic core structure and windings; the magnetic core structure includes a main magnetic core and an auxiliary magnetic core. Magnetic core, the main magnetic core includes an iron core pillar and an iron yoke, the iron core pillars are arranged longitudinally, and windings are respectively provided on the iron core pillars; the iron yoke is arranged between the iron core pillars for fixing the iron core column; the auxiliary magnetic core includes an independent square hollow magnetic ring, with a hollow window formed in the center of each magnetic ring; the windings include high-voltage windings, low-voltage windings and auxiliary windings arranged on the core column; the windings are viewed from the left They are arranged on the iron core column in order of A phase, B phase and C phase to the right; each phase auxiliary winding is located above the high voltage winding and low voltage winding of the current phase, and is wound on the current phase after passing through the window of the auxiliary core of the current phase. Phase main magnetic core core pillar.

Preferably, the high-voltage winding and the low-voltage winding of each phase winding are concentrically wound on the main magnetic core core leg of the current phase using layered coils, and the low-voltage winding, the high-voltage winding and the high-voltage winding are arranged in sequence from the core leg outward. winding.

Preferably, the leakage inductance between the auxiliary winding of each phase and the high-voltage winding of each phase is adjusted by adjusting the distance between the auxiliary winding of each phase and the high-voltage winding of each phase.

Specifically, when the total amount of magnetic flux remains unchanged, the magnetic flux is greater in materials with high magnetic permeability. Since the magnetic permeability of the iron core is much greater than that of air, the magnetic flux generated by the current in the winding mainly passes through the main iron core. The leakage inductance between windings is relatively small. In the original concentrically wound structure of high-voltage winding, low-voltage winding and auxiliary winding, the leakage inductance is smaller due to the small spacing between the windings. After the structure in the present invention increases the distance between the high-voltage winding and the auxiliary winding, the coupling effect between the high-voltage winding and the auxiliary winding through the main iron core becomes weaker, the magnetic flux in the main iron core decreases, the leakage magnetic flux increases, and the leakage flux increases. The feeling also increases.

Preferably,

An auxiliary magnetic core is wound between the auxiliary winding of each phase and the high-voltage winding of each phase to form a new magnetic flux path, thereby increasing the leakage inductance between the high-voltage winding of each phase and the auxiliary winding of each phase.

Specifically, after adding an auxiliary magnetic core, the magnetic permeability of the auxiliary magnetic core is relatively high. After adding an auxiliary magnetic core between the high-voltage winding and the auxiliary winding, the magnetic flux is redistributed. The magnetic flux passing through the auxiliary magnetic core increases and passes through the main iron. The magnetic flux in the core is reduced, which is equivalent to increasing the leakage inductance.

Preferably,

The auxiliary magnetic core has three independent phases, and the size and material of each phase of the auxiliary magnetic core are determined according to the required leakage inductance frequency and leakage inductance value.

Preferably,

The iron yokes are arranged in two groups, and the two groups of iron yokes are respectively arranged at the upper end and the lower end of the main magnetic core core pillar; the iron yoke and the main magnetic core core pillar in the magnetic core structure are overlapped with a 45-degree oblique joint step splicing method; each level of lamination of the iron core structure is made of silicon steel sheets.

Preferably, the magnetically integrated hybrid distribution transformer includes a converter unit connected to the auxiliary winding of each phase and the low-voltage winding of each phase.

Preferably, the converter unit includes:

AC-DC converter, DC-AC converter, DC bus capacitor, filter inductor and three-phase four-wire AC voltage filter shared by the AC-DC converter and the DC-AC converter.

Preferably, the AC-DC converter includes a parallel current control bridge arm; the DC-AC converter includes a parallel voltage control bridge arm and a zero sequence control bridge arm; the filter inductor is connected to the DC-AC After the bridge arm of the converter is output, the rear end of the filter inductor connected after the voltage control bridge arm is the three-phase voltage output end of the converter unit, and the filter inductor connected after the zero sequence control bridge arm is The rear end is the zero-sequence output terminal of the converter unit; the three-phase four-wire AC voltage filter is connected in parallel between the three-phase voltage output terminal and the zero-sequence output terminal of the converter unit; the auxiliary winding and The midpoint of the current control bridge arm is connected, the low-voltage winding is connected to the three-phase voltage output end of the converter unit, and the zero-sequence output end of the converter unit is connected to the neutral line of the three-phase four-wire load.

Preferably,

The high-voltage winding is connected to the power grid through a delta connection, the low-voltage winding is connected to a three-phase four-wire load and each phase voltage output end of the converter unit, and the auxiliary winding is connected to the converter through a delta connection. connected to the current output end of the converter unit.

In order to better understand the present invention, the specific implementation of the magnetically integrated hybrid distribution transformer with a simple structure of the present invention will be described in detail below with reference to Figures 1(a), 1(b), 1(c), 2, and 3. process.

The main circuit of the magnetically integrated hybrid distribution transformer with a simple structure of the present invention includes a transformer unit 16 and a converter unit 6; as shown in Figure 1(a), the windings of the transformer unit 15 include an A-phase high-voltage winding 1a and a B-phase high-voltage winding. 1b, C-phase high-voltage winding 1c, A-phase low-voltage winding 2a, B-phase low-voltage winding 2b, C-phase low-voltage winding 2c, A-phase auxiliary winding 3a, B-phase auxiliary winding 3b and C-phase auxiliary winding 3c. The first and last terminals of each phase of the three-phase high-voltage windings A, B, and C are A/X, B/Y, and C/Z. The first and last terminals of each phase of the three-phase low-voltage windings A, B, and C are a2/x2, and b2/y2, c2/z2, the first/end terminals of each phase of the three-phase auxiliary windings A, B, and C are a3/x3, b3/y3, c3/z3; it is specified that the first ends of the high-voltage winding, low-voltage winding and auxiliary winding are The same terminals; the high-voltage winding is connected to the power grid using a delta connection, specifically, the first ends A, B, and C of the three-phase high-voltage windings 1a, 1b, and 1c of A, B, and C are connected to the power grid, and the first ends A and 1c of 1a are connected to the power grid. The end Z of 1 is connected, the first end B of 1b is connected with the end X of 1a, the first end C of 1c is connected with the end Y of 1b.

As shown in Figure 1(b), the converter unit 6 consists of an AC-DC converter 7, a DC-AC converter 8, a DC converter shared by the AC-DC converter and the DC-AC converter. The bus capacitor 9 is composed of 4 filter inductors 13 and 1 AC output filter 14. The AC-DC converter 7 includes three parallel current control bridge arms. Each phase current bridge arm is composed of two switch tubes 10 connected in series. The DC-AC converter includes three parallel voltage control bridge arms. and 1 zero-sequence control bridge arm. Each phase voltage bridge arm is composed of two switching tubes 11 connected in series, and the zero-sequence control bridge arm is composed of two switching tubes 12 connected in series; the auxiliary winding of each phase adopts a delta connection method. Connected to each phase current output end of the converter unit, specifically the first ends a3, b3, c3 of the three-phase auxiliary windings 3a, 3b, 3c of A, B, and C and the three-phase current output end u3 of the converter unit A, B, and C , v3, and w3 are connected. At the same time, the head end a3 of 3a is connected to the end z3 of 3c, the head end b3 of 3b is connected to the end x3 of 3a, and the head end c3 of 3c is connected to the end y3 of 3b.

As shown in Figure 1(b) and Figure 1(c), the low-voltage winding of each phase is connected to the load and the voltage output terminal of each phase of the converter unit respectively. The zero-sequence output terminal of the converter unit is connected to the three-phase four-wire The neutral line of the controlled load 15 is connected, specifically, the first ends a2, b2, c2 of the three-phase low-voltage windings 2a, B, and C of A, B, and C are connected to the front ends u2, v2, and w2 of the three-phase load 15 of A, B, and C. The terminals x2, y2, and z2 of the three-phase low-voltage windings 2a, 2b, and 2c of A, B, and C are respectively connected to the three-phase voltage output terminals u2y, v2y, and w2y of the converter. The zero-sequence output terminal ny2 of the converter unit is connected to the three-phase four-phase voltage output terminals. The neutral line n2 of the line load 15 is connected.

Figure 2 is a three-dimensional view of the electromagnetic body of the magnetically integrated hybrid distribution transformer with a simple structure according to the present invention. As shown in Figure 2, the magnetic core structure of the magnetically integrated hybrid distribution transformer with a simple structure mentioned above includes a main magnetic core and an auxiliary magnetic core. The main magnetic core includes three iron core pillars and an iron yoke. The iron core pillar includes A Phase iron leg 4a, B phase iron leg 4b and C phase iron leg 4c. The auxiliary magnetic core is three independent square hollow magnetic rings. The hollow center of each magnetic ring forms a window, including A-phase auxiliary magnetic core 5a, B-phase auxiliary magnetic core 5b and C-phase auxiliary magnetic core 5c; three-phase auxiliary The magnetic cores 5a, 5b, and 5c are arranged vertically on the three-phase core columns 4a, 4b, and 4c respectively with the windows perpendicular to the horizontal plane; the A-phase low-voltage winding 2a and the high-voltage winding 1a adopt layered windings and are wound concentrically from the inside to the outside. On the A-phase main magnetic core leg 4a, the A-phase auxiliary winding 3a passes through the window of the A-phase auxiliary core and is wound on the A-phase main magnetic core leg 4a; the B-phase low-voltage winding 2b and the high-voltage winding 1b are layered. The winding is concentrically wound on the B-phase main magnetic core leg 4b from the inside to the outside. The B-phase auxiliary winding 3b passes through the window of the B-phase auxiliary core and is wound on the B-phase main magnetic core leg 4b; C-phase low-voltage winding 2c and high-voltage winding 1c adopt layered windings and are wound concentrically on the C-phase main magnetic core core leg 4c from the inside to the outside. The C-phase auxiliary winding 3c passes through the window of the C-phase auxiliary core and is wound on the C-phase main magnetic core core. On column 4c.

As shown in Figure 2, the three-phase auxiliary cores are independent of each other and can flexibly adjust the leakage inductance according to needs.

Figure 3 is an electromagnetic simulation result diagram of a magnetically integrated hybrid distribution transformer with a simple structure according to the present invention. As shown in Figure 3, the electromagnetic simulation results provided by the embodiment of the present invention show that:

1. The part of the auxiliary core between the auxiliary winding and the high-voltage winding has a higher magnetic induction intensity (green in the picture, which is the same color as the part with a higher magnetic induction intensity in the main core), indicating that more magnetic flux passes through the auxiliary core. The leakage inductance between the core, auxiliary winding and high-voltage winding has been significantly improved, which verifies the effectiveness of the structural design of the present invention.

2. The main iron core and the auxiliary magnetic core of the magnetically integrated hybrid distribution transformer with a simple structure of the present invention are not saturated, which meets the design requirements of the transformer core and verifies the practical feasibility of the structural design of the present invention.

The invention adopts a structure in which the high-voltage winding and the low-voltage winding are wound concentrically on the same core column and the auxiliary winding is wound separately, which increases the distance between the auxiliary winding and the high-voltage winding and increases the leakage inductance between the high-voltage winding and the auxiliary winding. This structure can increase the leakage inductance while keeping the structure compact, and facilitate the magnetic integration of the filter inductor and the winding leakage inductance. At the same time, the leakage inductance can be adjusted conveniently and flexibly by adjusting the distance between the auxiliary winding and the high-voltage winding; Adding an auxiliary magnetic core between the winding and the low-voltage winding increases the leakage inductance between the high-voltage winding and the low-voltage winding of the transformer, eliminating the need for a filter inductor connecting the auxiliary winding of the converter, realizing magnetic integration of the converter filter inductor and the transformer winding, which can reduce The number of discrete magnetic components simplifies the overall structure of the device. In addition, the auxiliary magnetic core can dissipate heat together with the main magnetic core, eliminating the space required for heat dissipation design of the converter filter inductor and reducing the overall volume of the hybrid distribution transformer.

The above are only preferred embodiments of the present invention, and do not limit the patent scope of the present invention. Under the concept of the present invention, equivalent structural transformations can be made by using the contents of the description and drawings of the present invention, or directly/indirectly used in Other related technical fields are included in the patent protection scope of the present invention.

Claims (7)

1. A magnetically integrated hybrid distribution transformer with a simple structure, characterized in that the magnetically integrated hybrid distribution transformer includes a transformer unit, and the transformer unit includes a magnetic core structure and windings; the magnetic core structure includes a main magnetic core and an auxiliary magnetic core. The main magnetic core includes an iron core pillar and an iron yoke. The iron core pillars are arranged longitudinally, and windings are respectively provided on the iron core pillars. The iron yoke is arranged between the iron core pillars for fixing all the iron core pillars. The iron core pillar; the auxiliary magnetic core includes an independent square hollow magnetic ring, and a hollow window is formed in the center of each magnetic ring; the windings include high-voltage windings, low-voltage windings and auxiliary windings arranged on the iron core pillar; the windings The auxiliary winding of each phase is located above the high-voltage winding and low-voltage winding of the current phase, and is wound after passing through the window of the auxiliary core of the current phase. On the core pillar of the main magnetic core in this phase; The high-voltage winding and the low-voltage winding of each phase winding are concentrically wound on the core pillar of the current main magnetic core using layered coils, and from the core pillar outwards are the low-voltage winding and the high-voltage winding in order; Adjust the leakage inductance between the auxiliary winding of each phase and the high-voltage winding of each phase by adjusting the distance between the auxiliary winding of each phase and the high-voltage winding of each phase; An auxiliary magnetic core is wound between the auxiliary winding of each phase and the high-voltage winding of each phase to form a new magnetic flux path, thereby increasing the leakage inductance between the high-voltage winding of each phase and the auxiliary winding of each phase. 2. The magnetically integrated hybrid distribution transformer according to claim 1, characterized in that, The auxiliary magnetic core has three independent phases, and the size and material of the auxiliary magnetic core for each phase are determined according to the required leakage inductance frequency and leakage inductance value. 3. The magnetically integrated hybrid distribution transformer according to claim 1, characterized in that, The iron yokes are arranged in two groups, and the two groups of iron yokes are respectively arranged at the upper end and the lower end of the main magnetic core core pillar; the iron yoke and the main magnetic core core pillar in the magnetic core structure are overlapped with a 45-degree oblique joint step splicing method; each level of lamination of the magnetic core structure is made of silicon steel sheets. 4. The magnetically integrated hybrid distribution transformer according to claim 1, characterized in that the magnetically integrated hybrid distribution transformer includes a converter unit, the converter unit is connected to the auxiliary winding of each phase and the low-voltage winding of each phase. connected. 5. The magnetically integrated hybrid distribution transformer according to claim 4, characterized in that the converter unit includes: AC-DC converter, DC-AC converter, DC bus capacitor, filter inductor and three-phase four-wire AC voltage filter shared by the AC-DC converter and the DC-AC converter. 6. The magnetically integrated hybrid distribution transformer according to claim 5, wherein the AC-DC converter includes a parallel current control bridge arm; the DC-AC converter includes a parallel voltage control bridge arm and Zero sequence control bridge arm; the filter inductor is connected after the bridge arm output of the DC-AC converter, and the back end of the filter inductor connected after the voltage control bridge arm is the three-phase voltage of the converter unit The output end, the rear end of the filter inductor connected after the zero sequence control bridge arm is the zero sequence output end of the converter unit; the three-phase four-wire AC voltage filter is connected in parallel to the three ends of the converter unit. between the phase voltage output terminal and the zero-sequence output terminal; the auxiliary winding is connected to the midpoint of the current control bridge arm, the low-voltage winding is connected to the three-phase voltage output terminal of the converter unit, and the converter The zero sequence output terminal of the unit is connected to the neutral line of the three-phase four-wire load. 7. The magnetically integrated hybrid distribution transformer according to claim 6, characterized in that, The high-voltage winding is connected to the power grid through a delta connection, the low-voltage winding is connected to a three-phase four-wire load and each phase voltage output end of the converter unit, and the auxiliary winding is connected to the converter through a delta connection. connected to the current output end of the converter unit.