阅读说明：本技术 一种含零序磁通回路的变压器立式卷铁芯结构 (Vertical iron core structure of rolling up of transformer that contains zero sequence magnetic flux return circuit ) 是由 刘桦 柳轶彬 高亚晨 张立石 梁得亮 李大伟 于 2021-06-10 设计创作，主要内容包括：本发明公开了一种含零序磁通回路的变压器立式卷铁芯结构,其可以用于混合配电变压器中卷铁芯结构的隔离变压器,也可以用于其它需要提供零序磁通回路的立式卷铁芯结构变压器；在现有立式卷铁芯为三相正序和负序磁通提供通路的基础上,增加了零序磁通通路,使得变压器零序阻抗变小,从而减小零序损耗。同时本发明提出的新型结构依然具有现有立式卷铁芯结构的优点：三相完全对称,磁路长度相同,磁通均匀,产生的波形好；芯柱的接缝小,运行时噪音低,空载电流和空载损耗也特别小。(The invention discloses a vertical wound core structure of a transformer containing a zero-sequence magnetic flux loop, which can be used for an isolation transformer of a wound core structure in a hybrid distribution transformer and can also be used for other vertical wound core structure transformers needing to provide the zero-sequence magnetic flux loop; on the basis that the existing vertical wound iron core provides a passage for three-phase positive-sequence and negative-sequence magnetic fluxes, a zero-sequence magnetic flux passage is added, so that the zero-sequence impedance of the transformer is reduced, and the zero-sequence loss is reduced. Meanwhile, the novel structure provided by the invention still has the advantages of the existing vertical rolled iron core structure: three phases are completely symmetrical, the lengths of magnetic circuits are the same, the magnetic flux is uniform, and the generated waveform is good; the core column has small joint, low noise in operation, and extremely small no-load current and no-load loss.)

1. A vertical wound core structure of a transformer with a zero-sequence magnetic flux loop is characterized by comprising three outer cores and three inner cores, wherein each iron core is annular, and the inner cores are arranged in the outer cores;

each iron core is divided into two iron core columns in the vertical direction and two yoke parts in the horizontal direction, and each end of each iron core column is connected with one yoke part through a connecting part;

the iron core column of each outer iron core is contacted with the iron core column of the other outer iron core, the iron core columns of the three outer iron cores are sequentially contacted, and the three outer iron cores form a virtual equilateral triangular prism structure;

one iron core column in each inner iron core is arranged at the vertical center line of the equilateral triangular prism structure, the other iron core column is arranged at the side edge of the equilateral triangular prism, and one inner iron core corresponds to one side edge;

the three core legs at each lateral edge are jointly wound by a winding.

2. The transformer vertical wound core structure with the zero-sequence magnetic flux loop according to claim 1, wherein the outer core is an annular whole body formed by winding silicon steel sheets; the inner iron core is an annular whole formed by winding silicon steel sheets.

3. The vertical wound core structure of transformer with zero-sequence magnetic flux loop according to claim 2, wherein during the winding process of the inner core from inside to outside, the width of the silicon steel sheet is from narrow to wide and then from wide to narrow, one of the side wall surfaces of the inner core is a plane, and the other is a curved surface.

4. The vertical wound core structure of the transformer with the zero-sequence magnetic flux loop according to claim 2, wherein in the process of winding the outer core from inside to outside, the width of the silicon steel sheet is from narrow to wide and then from wide to narrow; the inside wall face of outer iron core comprises two planes, two planar contained angles are 120, and the inside wall face of outer iron core is the curved surface.

5. The vertical wound core structure of transformer with zero-sequence magnetic flux loop of claim 1, wherein two outer cores and one inner core at each side edge form a phase core column, which is phase a core column, phase B core column and phase C core column; the iron core columns of the three inner iron cores form a middle core column together at the vertical central line;

the middle core column is connected with the three-phase core column through the yoke part of the inner iron core.

6. The vertical wound core structure of transformer with zero sequence magnetic flux loop of claim 1, wherein the core leg of the outer core and the core leg of the inner core are equal in height.

7. The vertical wound core structure of transformer with zero sequence magnetic flux loop of claim 1, wherein the joint is arc-shaped.

8. The vertical wound core structure of transformer with zero sequence magnetic flux loop as claimed in claim 1, wherein the radius of the outer core joint is larger than the radius of the inner core joint.

9. The vertical wound core structure of transformer with zero-sequence magnetic flux loop according to any one of claims 1 to 8, wherein the winding comprises a primary winding and a secondary winding, the secondary winding is wound outside the three core legs, and the primary winding is wound outside the secondary winding.

Technical Field

The invention belongs to the technical field of transformers, and particularly relates to a vertical wound iron core structure of a transformer with a zero-sequence magnetic flux loop.

Background

In the last decades, the characteristics of electric equipment are greatly changed due to the development of power electronic technology, and the stability of a power grid is reduced due to sensitive load; the development of renewable energy sources such as wind energy and solar energy promotes the development of smart power grids, new challenges are provided for equipment such as power transformers, and Hybrid Distribution Transformers (HDT) are produced at the same time. The hybrid distribution transformer combines the power electronic converter and the traditional transformer together, can simultaneously keep the voltage at the load side and the current at the network side stable and symmetrical by controlling the on-off of the power electronic switch, realizes the harmonic wave treatment, the reactive power compensation, the power factor improvement and the voltage stabilization, and can comprehensively improve the electric energy quality. The method is suitable for the condition that the sensitive load and the network side power supply have fluctuation, and improves the stability of the power grid.

The three-phase iron core of traditional transformer is located the coplanar, and the three-phase stem of iron core structure is rolled up to the formula and is equilateral triangle symmetry and place, and the junction of stem and yoke portion is convex. The structure is symmetrical up and down, and three phases are completely symmetrical, so that the magnetic circuits are the same in length, the magnetic flux is uniform, and a better waveform can be generated; because the core column is formed by continuously and tightly rolling the strip material, the core column has small joint, low noise in operation, extremely small no-load current and no-load loss, and higher economic benefit compared with the traditional iron core.

The hybrid distribution transformer is composed of a main transformer and an isolation transformer, wherein the isolation transformer can generate zero-sequence magnetic flux, the existing vertical wound iron core does not provide a passage for the zero-sequence magnetic flux, and the zero-sequence magnetic flux can only form a closed loop through an air gap, so that the zero-sequence impedance of the transformer is larger. Therefore, it is necessary to provide a vertical wound core structure of a transformer including a zero sequence magnetic flux loop, which not only has the advantages of the wound core structure, but also provides a loop for the zero sequence magnetic flux.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a vertical wound iron core structure of a transformer with a zero-sequence magnetic flux loop, so as to solve the problem that the existing vertical wound iron core structure does not contain the zero-sequence magnetic flux loop in the prior art.

In order to achieve the purpose, the invention adopts the following technical scheme to realize the purpose:

a vertical type wound iron core structure with a zero sequence magnetic flux loop is characterized by comprising three outer iron cores and three inner iron cores, wherein each iron core is annular, and the inner iron cores are arranged in the outer iron cores;

each iron core is divided into two iron core columns in the vertical direction and two yoke parts in the horizontal direction, and each end of each iron core column is connected with one yoke part through a connecting part;

the iron core column of each outer iron core is contacted with the iron core column of the other outer iron core, the iron core columns of the three outer iron cores are sequentially contacted, and the three outer iron cores form a virtual equilateral triangular prism structure;

one iron core column in each inner iron core is arranged at the vertical center line of the equilateral triangular prism structure, the other iron core column is arranged at the side edge of the equilateral triangular prism, and one inner iron core corresponds to one side edge;

the three core legs at each lateral edge are jointly wound by a winding.

The invention is further improved in that:

preferably, the outer iron core is an annular whole formed by winding silicon steel sheets; the inner iron core is an annular whole formed by winding silicon steel sheets.

Preferably, in the process of winding the inner iron core from inside to outside, the width of the silicon steel sheet is from narrow to wide and then from wide to narrow, one of the side wall surfaces of the inner iron core is a plane, and the other is a curved surface.

Preferably, in the process of winding the outer iron core from inside to outside, the width of the silicon steel sheet is firstly from narrow to wide and then from wide to narrow; the inside wall face of outer iron core comprises two planes, two planar contained angles are 120, and the inside wall face of outer iron core is the curved surface.

Preferably, the two outer iron cores and the inner iron core at each lateral edge jointly form a phase core column which is an A-phase core column, a B-phase core column and a C-phase core column respectively; the iron core columns of the three inner iron cores form a middle core column together at the vertical central line;

the middle core column is connected with the three-phase core column through the yoke part of the inner iron core.

Preferably, the core legs of the outer core and the core legs of the inner core are equal in height.

Preferably, the joint is arc-shaped.

Preferably, the radius of the joint of the outer iron core is larger than that of the joint of the inner iron core.

Preferably, the winding comprises a primary winding and a secondary winding, the secondary winding is wound outside the three iron core columns, and the primary winding is wound outside the secondary winding.

Compared with the prior art, the invention has the following beneficial effects:

the invention discloses a vertical wound core structure of a transformer containing a zero-sequence magnetic flow loop, which is a novel vertical wound core structure for an isolation transformer in a hybrid distribution transformer. Meanwhile, the novel structure provided by the invention still has the advantages of the existing vertical rolled iron core structure: three phases are completely symmetrical, the lengths of magnetic circuits are the same, the magnetic flux is uniform, and the generated waveform is good; the core column has small joint, low noise in operation, and extremely small no-load current and no-load loss. The invention has universality, can be used for the isolation transformer and is suitable for occasions where zero sequence magnetic flux can be generated in three phases. The zero sequence magnetic flux path is added on the basis of the original vertical type wound core structure, and zero sequence impedance and zero sequence loss are reduced, so that higher requirements are met, and better economic benefits are achieved.

Drawings

Fig. 1 is a schematic diagram of a single core structure in a vertical wound core of a transformer with a zero-sequence flux path.

Fig. 2 is a schematic diagram of an outer layer structure of a vertical wound core of a transformer with a zero-sequence flux path.

Fig. 3 is a schematic diagram of an inner layer structure of a vertical wound core of a transformer with a zero-sequence flux path.

Fig. 4 is a schematic diagram of the overall structure of a vertical wound core of a transformer with a zero-sequence flux path.

Fig. 5 is a top sectional view of the whole transformer vertical type wound core with zero sequence flux path.

FIG. 6 shows yoke E_AO1And stem X_A3Top view of a horizontal section of the junction.

FIG. 7 shows yoke E of phase A outer core_AB1And stem X_A1Top view of a horizontal section of the junction.

Detailed Description

The invention is described in further detail below with reference to the accompanying drawings:

in the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention; the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly and encompass, for example, both fixed and removable connections; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

The invention discloses a novel vertical wound iron core structure for an isolation transformer in a hybrid distribution transformer. The outer iron core is provided with three, and interior iron core is provided with three.

The vertical direction of each of the inner and outer cores is called a core leg, and the horizontal direction is called a yoke. More specifically, each outer core is composed of an outer core limb and an outer yoke portion, and each inner core is composed of an inner core limb and an inner yoke portion. Each of the inner and outer cores is an annular whole body made of silicon steel sheet wound, as shown in fig. 1.

M₁、M₂And M₃The structure of the three outer iron cores, the outer iron core column and the yoke part is similar to that of the traditional vertical type rolled iron core. As shown in FIG. 2, M₁Comprising an outer core limb X_A1And X_B2Outer yoke E_AB1And E_AB2；M₂Comprising an outer core limb X_B1And X_C2Outer yoke E_BC1And E_BC2；M₃Comprising an outer core limb X_C1And X_A2Outer yoke E_CA1And E_CA2. The three-phase core columns are the same in height and are symmetrically distributed, and the core columns of all the phases are connected by an upper yoke part and a lower yoke part which are parallel to the horizontal plane. Each phase of core limb is composed of two parts, specifically, the phase A outer core limb is composed of X_A1And X_A2The B phase outer core limb consists of X_B1And X_B2The C-phase outer core limb consists of X_C1And X_C2The upper ends of the A-phase outer core limb and the B-phase outer core limb are provided with outer yokes E_AB1Connected by an outer yoke E at the lower end_AB2Connecting; the upper ends of the A-phase outer core limb and the C-phase outer core limb are formed by an outer yoke E_CA1Connected by an outer yoke E at the lower end_CA2Connecting; the upper ends of the B-phase outer core limb and the C-phase outer core limb are formed by an outer yoke E_BC1Connected by an outer yoke E at the lower end_BC2Connecting; the whole outer iron core is a whole, the core part and the yoke part are formed by tightly and continuously winding thin strips with variable widths from inside to outside, and the joint is in an arc shape. Referring to fig. 5, which is a top view of a vertical wound core with zero-sequence flux path for a transformer, taking the outer core frame at the bottom as an example, the sections of two core columns are one third of a circle (sector), and one core column is arranged on the left and one core column is arranged on the right. The layer-by-layer lines in the sector section represent layer-by-layer strip materials; the strip material of the innermost ring in one outer iron core is narrowest and corresponds to the shortest vertical line in the sector, the width of the strip material is gradually increased and then decreased in the process that the strip material is rolled from inside to outside, correspondingly, the length of the vertical line in the sector is firstly increased to the radius of a circle and then gradually decreased to form a graph2, a core limb and an outer yoke, the cross-section of which varies per se. Because the iron core columns of the three outer iron cores are in pairwise contact, the three outer iron cores form an equilateral triangular prism structure, and the outer structure provides a closed path for the positive sequence component and the negative sequence component of the three-phase magnetic flux.

The core leg and yoke part structure of the inner core is shown in FIG. 3, N₁、N₂And N₃Are three inner cores. As shown in FIG. 3, N₁Comprising an inner core limb X_A3And X_OAInner yoke E_AO1And E_AO2；N₂Comprising an inner core limb X_B3And X_OBInner yoke E_BO1And E_BO2；N₃Comprising an inner core limb X_C3And X_OCInner yoke E_OC1And E_OC2. The three-phase core legs have the same height and are symmetrically distributed, another core leg is positioned at the geometric center of the position of the three-phase core leg and is a middle core leg, see fig. 3, and the inner core leg X is arranged on the middle core leg_OA、X_OBAnd X_OCAll in the central part, the three inner iron core columns jointly form a middle iron core column, and correspondingly, the other inner iron core column X of each inner iron core_A3、X_B3And X_C3The core columns are three-phase core columns, each phase of core column is connected with the middle core column through an upper yoke part and a lower yoke part which are parallel to the horizontal plane, the iron yokes of the three inner iron cores are arranged in equal intervals along the circumferential direction by taking the middle core column as the center of a circle, namely, the included angle between every two adjacent iron yokes is 120 degrees. The iron core is the same as the outer iron core, the whole inner iron core is a whole, the core part and the yoke part are formed by tightly and continuously winding thin strips with variable widths from inside to outside, and the joint is in an arc shape. The core part and the yoke part are formed by winding thin strips, and the joint is arc-shaped. The inner iron core can provide a closed loop for the zero sequence magnetic flux component generated in the three-phase iron core. The thin strip material is the silicon steel sheet

Taking the inner core of phase A as an example, FIG. 6 shows a yoke E_AO1And stem X_A3Top view of a horizontal section of the junction. The inner character in the figure represents the inner ring of the inner iron core winding, the outer character represents the outermost ring of the inner iron core winding, the width of the inner end surface of the inner iron core is slightly larger than that of the outer end surface, and the widest part of the whole inner iron core is at the interval of M and N points. In the process that the inner iron core is wound from inside to outside, the width of the thin strip material is changed from narrow to wide, and then from wide to narrow after passing through MN. The side wall surface of the inner iron core is not a surface, but is composed of two surfaces, including a plane and a curved surface, and the two side wall surfaces are symmetrical.

See fig. 7 for yoke E of phase a outer core_AB1And stem X_A1The horizontal section of the junction is seen from above, and fig. 7 and 6 are cross-sections at the same horizontal level. The inner character in the figure represents the inner ring of the outer iron core winding, the outer character represents the outermost ring of the outer iron core winding, the width of the inner end surface of the outer iron core is equal to that of the outer end surface, and the widest part of the whole outer iron core is the distance between the points O and R. In the process that the outer iron core is wound from inside to outside, the width of the thin strip material is changed from narrow to wide, passes through O and R and then changes from wide to narrow all the time. The outer side wall surface of the outer iron core is a curved surface and is not in contact with other surfaces, so that the outer iron core can be directly observed, and the inner side wall surface of the outer iron core is two planes with included angles of 120 degrees and is respectively in contact with two other core columns X in the phase A_A1And X_A2And (4) contacting.

The splicing mode of the inner iron core and the outer iron core is shown in figure 4: phase A core column X_AFrom X_A1，X_A2And X_A3Combined together, phase B core column X_BFrom X_B1,X_B2And X_B3Combined together, C phase core column X_CFrom X_C1And X_C2And X_C3Are combined together. Three-phase core column X_A,X_BAnd X_CThe position of placement is located at three vertexes of a virtual equilateral triangle, and a core column X is also placed at the gravity center of the virtual equilateral triangle_O，X_OFrom X_OA,X_OBAnd X_OCThe core column in the inner iron core and the outer iron core are the same in height, and the outer ring of the outer iron core is larger than the inner iron core due to the fact that the radius of the connecting part of the outer iron core is larger than the outer diameter of the connecting part of the inner iron core. And each two phase of core columns are connected by two yoke parts parallel to the horizontal plane at the top and the bottom respectively, and the yoke parts are distributed along three edges of the virtual equilateral triangle. While the three-phase core column is respectively composed of two parallel top and bottomCore column X having yoke connected to center of gravity in horizontal plane_OThe above. X_A3And X_OAFrom yoke E_AO1And E_AO2Connection, X₃And X_OBFrom yoke E_BO1And E_BO2Connection, X_C3And X_OCFrom yoke E_CO1And E_CO2And the yoke parts are distributed along the middle line of the virtual equilateral triangle. The joints of all the yokes and the core are circular arc-shaped. The transformer vertical wound core overall structure is three-phase symmetrical and vertically symmetrical, and provides a passage for A, B and C three-phase magnetic fluxes and zero-sequence magnetic fluxes.

Core column X_AExternally winding A-phase primary winding W_A1And a secondary winding W_A2Secondary winding W_A2On the inside, a primary winding W_A1On the outside; core column X_BExternally winding B-phase primary winding W_B1And a secondary winding W_B2Secondary winding W_B2On the inside, a primary winding W_B1On the outside; core column X_CExternally winding C-phase primary winding W_C1And a secondary winding W_C2Secondary winding W_C2On the inside, a primary winding W_C1On the outside. When current flows through the primary side winding of the transformer, corresponding magnetic flux can be generated in the iron core due to the alternating current. If the three-phase input current is in an ideal state, namely the three-phase current has equal amplitude and does not contain harmonic components, and when the phases are different by 120 degrees, the three-phase induced magnetic flux is distributed symmetrically and only contains positive sequence components, so that the inner layer structure of the iron core has no magnetic flux. In the outer layer structure, magnetic flux flows from a high density portion to a low density portion. However, in practical applications, due to various reasons such as harmonic of primary current and variation of secondary load, the induced magnetic flux in the iron core is asymmetric in three phases and contains positive sequence, negative sequence and zero sequence components at the same time. At this time, the three-phase induced magnetic flux is distributed asymmetrically, but the zero sequence components of the magnetic fluxes of all phases after decomposition are equal in magnitude and same in direction, so that the magnetic fluxes flow into or out of the core column X in the same direction_O。

The invention discloses a vertical wound core structure of a transformer containing a zero-sequence magnetic flux loop, which can be used for an isolation transformer of a wound core structure in a hybrid distribution transformer and can also be used for other vertical wound core structure transformers needing to provide the zero-sequence magnetic flux loop; on the basis that the existing vertical wound iron core provides a passage for three-phase positive-sequence and negative-sequence magnetic fluxes, a zero-sequence magnetic flux passage is added, so that the zero-sequence impedance of the transformer is reduced, and the zero-sequence loss is reduced. Meanwhile, the novel structure provided by the invention still has the advantages of the existing vertical rolled iron core structure: three phases are completely symmetrical, the lengths of magnetic circuits are the same, the magnetic flux is uniform, and the generated waveform is good; the core column has small joint, low noise in operation, and extremely small no-load current and no-load loss.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.