CN109841393B - Winding staggered distribution transformer - Google Patents
Winding staggered distribution transformer Download PDFInfo
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- CN109841393B CN109841393B CN201910226110.2A CN201910226110A CN109841393B CN 109841393 B CN109841393 B CN 109841393B CN 201910226110 A CN201910226110 A CN 201910226110A CN 109841393 B CN109841393 B CN 109841393B
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Abstract
The invention relates to a novel distribution transformer. The structure advantages of the existing shell type transformer and core type transformer are integrated, and the existing distribution transformer can be completely replaced. The cost is greatly reduced, and the passing rate of the burst short circuit test is basically 100 percent. The transformer winding has good cooling effect, strong overload capacity, large limit capacity and convenient transportation. The advantage of limited capacity is better than the shell type. When vertical transportation is inconvenient, can the flip-chip transportation, reduce the transportation height. The structure is compact, the appearance volume is small, the whole weight is light, the structure is compact, the lead wire is convenient to install, the capacitance distribution is uniform, the insulation is reliable, and the lightning stroke resistance and the operation overvoltage resistance are strong.
Description
Technical Field
The invention relates to a novel distribution transformer, which is used for replacing the existing distribution transformer with concentrically arranged windings.
Background
A distribution transformer is an important power device applied to a power grid and a power system, and is mainly composed of an iron core and a winding (also called a coil). The distribution transformer is mainly a core transformer, and the windings are arranged concentrically.
The basic structure of the distribution transformer is shown in figure 1 (three-phase), the section of the core limb is circular, the arrangement mode is vertical, the section of the coil is also circular, the high-voltage coil and the low-voltage coil are sequentially and concentrically sleeved on the core limb, the coil surrounds the core, and the coils are concentrically arranged. The cross section of the iron core column is formed by stacking multiple stages of iron core sheets with different sheet widths and different thicknesses, and the external shape of the cross section of the iron core column is a circumscribed circle, so the cross section of the iron core column is called as a circle.
The shell type transformer has strong short circuit resistance, is mainly applied to high-capacity and high-voltage products, has high cost because the iron core and the winding are rectangular, has complicated magnetic flux distribution in the iron core, and is easy to have unequal three-phase line voltages.
Compared with a shell type transformer, the core type transformer is low in cost, but the sudden short circuit resistance is poor, the requirement on the roundness of the winding is extremely high, and if the roundness of the winding is slightly poor, the sudden short circuit resistance is sharply reduced.
The core is typically formed of a leg (a leg around which the windings are placed), a yoke, or includes side legs. The core column is circular in cross section, namely the iron core cross section is circular, and the iron core cross section is circular no matter whether the iron yoke and the side column are rectangular, circular, E-shaped or other shapes as long as the iron core column is circular. If the core leg is rectangular, the core section is rectangular no matter whether the yoke and side legs are rectangular, circular or other shapes. Therefore, the core section is called as the same as the core limb and is independent of the iron yoke and the side limb.
At present, core transformers are mainly adopted in various countries, and account for about 95% of the total output. However, several transformer manufacturers produce shell-type transformers, the most important being three companies, namely western house, mitsubishi, and schneider, france. At present, a small amount of production is produced in China, and the production is mainly focused on the aspect of electric furnace transformers.
The distribution transformer has extremely strict requirements on cost due to market environment requirements, and various domestic enterprises can reduce the cost by sacrificing short-circuit capacity. The passing rate of the sudden short circuit test of the distribution transformer is extremely low, which is not more than 10% at present in China, even none of most enterprises is qualified. For cost reasons, a batch of core-type elliptical winding distribution transformers are designed in some domestic production and scientific research institutes, the specification is mainly 10KV voltage, the capacity is 30-500 KVA, the cost is reduced, but according to the drawing inspection of national network companies, the qualification rate of the sudden short circuit test is extremely low.
From the analysis of the current domestic market conditions, two major problems of the survival and death of transformer enterprises are determined: transformer cost and burst short circuit test qualification rate.
Disclosure of Invention
Winding staggered distribution transformer (new transformer for short, the following) is characterized in that: the transformer comprises a transformer core and a transformer winding;
the transformer core adopts a core type structure;
the arrangement mode of the transformer windings is staggered;
the method for calculating the magnetic flux of the transformer core is the same as that of a core type transformer;
the method for calculating the impedance of the transformer is the same as that of a shell type transformer.
Winding alternating distribution transformer, the characteristic is: the cross section of the transformer core and the cross section of the transformer winding are oblong, elliptical, rectangular or the shape formed by combining a plurality of groups of curves.
Winding alternating distribution transformer, the characteristic is: the transformer winding adopts a disc winding.
Winding alternating distribution transformer, the characteristic is: the plate-type spiral winding is adopted as the transformer winding of large current.
The technology mainly adopts a core type iron core and a shell type staggered winding type, so that the principle analysis of the winding and the iron core type is necessary.
The novel transformer iron core can be considered that when a primary winding applies three-phase symmetrical sine-shaped line voltage, each magnetic flux in the iron core is also three-phase symmetrical sine-shaped magnetic flux. At all instants in time, the algebraic sum of the three-phase flux is equal to zero, i.e.
ΦA+ΦB+ΦC=0
When the novel three-phase transformer is not connected into a triangular winding, the algebraic sum of three-phase magnetic flux is not always equal to zero at all the moments due to the asymmetry of a three-phase magnetic circuit (a three-phase iron core) or the fact that the saturation degrees of three-phase magnetic circuits are different at all the moments due to the fact that three single-phase iron cores are different at all the moments
ΦA+ΦB+ΦC=Φ0
Therefore, an additional magnetic flux is superposed in the sinusoidal magnetic flux of each phase, so that the three-phase magnetic flux is asymmetric, the magnetic flux of each phase is not sinusoidal, and the induced voltage of each winding is asymmetric. But from the above formula can infer phi0Only the waveform of the magnetic flux of each phase is changed, and the phase of each phase is not changed.
Phi in the core when the three-phase transformer has windings joined in a triangle0A circulating current is induced in the delta winding, which generates a magnetic potential that is substantially equal to phi according to lenz's law0And (6) demagnetizing. In this case the flux of each phase is substantially sinusoidal, thereby ensuring that the induced voltage is sinusoidal.
From the above analysis of the three-phase magnetic circuit, the three-phase voltage of the novel transformer is symmetrical and the waveform is sine wave under the condition that the novel transformer has the windings connected into a triangle. When no triangular winding is arranged, the waveform distortion of small capacity can be ignored, the large capacity needs to be careful, the point is similar to that of a heart-type transformer, and the capacity of the transformer is mainly small, so that the waveform distortion can be accepted when the Y and yn0 connection group is adopted.
The technology is mainly researched from two indexes of cost and burst short circuit test qualification rate. The cost is mainly changed by a core type structure, and the cost and the loss are reduced by technical methods of the fact that the cross section of an iron core and the cross section of a transformer winding are oval and the like. And the short circuit aspect adopts an interlaced winding. The calculation method integrates the lengths of the two. The impedance voltage percentage is controlled by changing the calculation method of the leakage magnetic area for the flattening structure of the winding.
The staggered (also called as overlapped on some books) arrangement of the transformer windings is that high, medium and low voltage coils are staggered with each other along the height of the iron core column, the low voltage coils are adjacent to iron yokes (at two ends) of the iron core, the high, medium voltage coils are arranged in the middle, the structure diagram is shown in figure 2, and figure 2 is a structure with two magnetic leakage groups. From the viewpoint of ampere-turn balance, a high voltage and two low voltages achieve the best effect of ampere-turn balance, and the combination is also called a magnetic balance group (or a magnetic leakage group). The dividing point of the balance group is the 0 point passed by the magnetic potential map, a magnetic balance group (as shown in fig. 3) is arranged between every two adjacent 0 points, and fig. 3 is a magnetic potential distribution diagram of the two magnetic balance groups.
With respect to the cross-section of the core and the windings, the core transformer is mainly circular, and the shell type is mainly rectangular. The main reason is that the short circuit electrodynamic force direction of the core type transformer winding is distributed along the radial direction, and according to electrodynamic force analysis, the circular stress effect is the best, so that the requirement of the core type transformer winding on the roundness is extremely high. The short circuit electrodynamic force direction of the shell type transformer is mainly distributed along the axial direction, and the cross section shape of the winding is not required according to electrodynamic force analysis, so that rectangular windings are adopted, and the distance between two iron core columns is mainly reduced by using the rectangle.
The iron core section and the transformer winding section of the novel transformer are in shapes of long circles, ellipses, rectangles or a combination of a plurality of groups of curves. The long circular cross section is that the two ends are semicircles with equal diameters, the middle is connected by a straight line, the diameter of the semicircle is called a winding short axis, the sum of the diameter of the semicircle and the length of the straight line is called a winding long axis, and figure 4 is a cross section of the long circular iron core. The ellipse is well understood, that is, the circumscribed form of the core and winding cross-section is an ellipse, also divided into major and minor axes (see fig. 5). The shape formed by combining a plurality of groups of curves is a shape formed by combining a plurality of curves or straight lines, for example, fig. 6 is a section similar to an ellipse formed by combining four groups of circular curves with four points of A1, A2, B1 and B2 as circle centers. Fig. 7 is a circular cross-section.
Distribution transformer windings are mainly cylindrical windings, also called layer windings, see diagram 8, usually made of round or flat wires wound one turn after the other without gaps between turns, so that a layer is formed by the turns continuously wound in this way, the two outermost wires at both ends of each layer are placed with insulation of a certain width, called end windings, fixed together with the wires. Any number of layers can be continuously wound, and interlayer insulation is arranged among the layers. It can be divided into single-layer cylinder type, double-layer cylinder type, and multilayer cylinder type.
The disc type layer winding, called disc winding or disc coil for short, is a new winding form, see diagram 9. The winding method is the same as that of a cylindrical winding, the winding is performed layer by layer, end insulation of the cylindrical winding is cancelled, the first lead and the last lead of each layer of the winding can adopt a flattening structure, the external shape of the cross section of the winding is oblong, elliptic, rectangular or a shape formed by combining a plurality of groups of curves, and when the lead of the winding adopts a round wire with small specification, the flattening structure is not adopted. The two end surfaces of the disc type layer winding can be calculated as a heat radiating surface when calculating the temperature of the winding, which is also a difference from a cylinder type winding, and the cylinder type winding has end insulation and extremely poor heat radiating effect, so the heat radiating surface can not be considered when calculating the temperature.
The flattening structure of the disc winding is as shown in fig. 9, and due to the helicity of the winding structure, a height difference of one lead is formed between the head and the tail of the first lead and the last lead, which has a great influence on short-circuit electrodynamic force and impedance calculation. Now the tail of the first wire of each layer is bent into a similar Z-shaped bend, so that the first wire is flush with the end surface of the winding, and the head of the last wire of each layer is bent into a similar Z-shaped bend, so that the last wire is flush with the end surface of the winding, and thus the two end surfaces of the whole winding are a plane. Each layer of wire or a plurality of wires of the disc type layer winding adopt a flattening structure. The disc type layer winding can adopt a flat connection structure or a flat connection structure according to design requirements. It can be divided into single-layer disc windings, double-layer disc windings, multilayer disc windings and segmented disc windings. The segmented disk type is that two or more disk windings are connected in series or in parallel, and the windings can be connected in parallel and also has an important difference from the segmented disk type and the segmented cylinder type.
The spiral winding is a structure of a transformer winding, each turn is formed by connecting a plurality of wires (flat wires, the shape of each flat wire is similar to a rectangle and is divided into width and thickness) in parallel, each parallel wire is overlapped in the width direction of the flat wire, each turn of the winding is one turn, the width of each turn is the width of the flat wire, the height of each turn is the thickness of the flat wire multiplied by the number of the parallel wires, and the turns are separated by a cushion block.
The spiral winding is divided into single spiral, double spiral, four spiral, six spiral and the like. The single spiral has only one strand of spiral, a cushion block is arranged between the similar wire turns, the double spiral, the four spiral and the six spiral are respectively formed by connecting two strands of spiral, four strands of spiral and six strands of spiral in parallel, and the cushion blocks are arranged between the adjacent strands and between turns. In order to make the lengths of the parallel wires of the spiral winding equal and make the probability of the positions of the parallel wires in the leakage magnetic field equal so as to reduce the circulating current of the parallel wires, the wires need to be transposed at certain specific positions of the winding.
Spiral plate winding, a new form of winding, is shown in diagram 10 (where b is the thickness of the copper plate). The iron core of the novel transformer is of a core type structure, but the magnetic field of the novel transformer is similar to that of a shell type transformer, and the parallel wires of each turn of the spiral winding do not need to be insulated and transposed, so that the parallel wires can be replaced by plates with the same area and the same material as the multiple parallel wires, such as copper plates and aluminum plates (for convenience of description, copper plates for short), and the first turn copper plates and the last turn copper plates of the winding can adopt a flattening structure. Due to the characteristics of the novel transformer and the spiral plate type winding, the spiral plate type winding has a good heat dissipation effect, and the turns can be separated by thin insulation blocks without using cushion blocks, such as a paperboard with the thickness of 0.5mm, and the cushion blocks are arranged between the turns as required according to the heat dissipation requirement. The spiral plate type winding has the greatest advantages that the height of the winding is reduced, and the filling coefficient in an iron window is greatly improved.
The flattening structure of the spiral plate type winding is shown in fig. 10, and due to the spiral property of the winding structure of the winding, a height difference of the thickness of the copper plate exists between the head and the tail of the first turn of copper plate and the last turn of copper plate, which has the biggest influence on short-circuit electrodynamic force and impedance calculation. And a similar Z-shaped bend is folded at the tail part of the first turn of copper plate to enable the first turn of copper plate to be level on the end surface of the winding, a similar Z-shaped bend is folded at the head part of the last first turn of copper plate to enable the last turn of copper plate to be level on the end surface of the winding, and thus the two end surface copper plates of the whole winding are a plane. Each turn of copper plate or a plurality of turns of copper plates can adopt a flattening structure. The spiral plate type winding can adopt a flat connection structure or a flat connection structure according to the design requirement.
The technical principle analysis of the non-circular winding of the novel transformer can only adopt the circular winding in the principle of the traditional distribution transformer, but the iron core structure of the novel transformer is a core type, but the winding structure is a shell type, the direction of short circuit electrodynamic force is mainly axial, radial electrodynamic force is small and controllable, and therefore the winding can adopt the non-circular structure.
Technical effects
First, the material cost is lower than that of a conventional core distribution transformer in the same performance standard.
Secondly, under the condition of the same material consumption, each performance index is lower than that of the traditional core type distribution transformer.
Thirdly, the mechanical strength is high and the short circuit resistance is strong. The capacity of the novel transformer for bearing short-circuit electrodynamic force is superior to that of the traditional core type distribution transformer. The novel transformer winding can adopt a plurality of magnetic balance groups, the magnetic leakage of each group is small, and the corresponding short-circuit stress is small in both radial direction and axial direction. The stress applied radially to the wire is only about 20% of that of a conventional heart. The general core type axial magnetic leakage is large, the shell type radial magnetic leakage is large, the appearance of a winding part in the novel transformer core window can be linear, the winding part can be conveniently extruded by using cushion blocks, the outside can be circular, and therefore the short circuit mechanical force bearing effect is superior to that of a shell type.
Fourthly, the novel transformer winding has good cooling effect and strong overload capacity. The high-low voltage winding is arranged like a shell, the oil passage is vertical, the convection is convenient during oil circulation, and the natural cooling performance is good. Especially, the advantages of strong oil guide cooling are more obvious.
Fifthly, the structure is compact, and the lead is convenient to install.
Sixthly, the capacitor is uniformly distributed, the insulation is reliable, and the lightning stroke resistance and the operation overvoltage resistance are strong.
Drawings
Fig. 1 is a schematic diagram of a core distribution transformer.
Fig. 2 is a schematic diagram of a novel transformer with two leakage groups.
FIG. 3 is a class of distribution diagrams of leakage potential of a novel transformer with two leakage groups.
Fig. 4 is a schematic view of an oblong cross-section of a novel transformer core.
Fig. 5 is an elliptical cross-sectional view of a novel transformer core.
Fig. 6 is a schematic sectional view of a novel transformer core formed by combining multiple groups of curves.
Fig. 7 is a schematic view of a circular cross-section of a novel transformer core.
Fig. 8 is a schematic diagram of a core transformer layer winding.
Fig. 9 is a schematic diagram of a novel transformer disc winding.
Fig. 10 is a schematic diagram of a novel transformer spiral plate winding.
Wherein the content of the first and second substances,
1 is a transformer core.
And 2 is a transformer winding.
And 3, distributing the leakage magnetic potential of the novel transformer.
And 4 is a circumscribed line shape of the transformer core.
And 5 is a schematic diagram of a transformer core lamination.
And 6, transformer layer winding end insulation.
And 7 is a transformer winding wire.
8, filling insulation of the novel transformer disc winding leveling structure.
And 9 is a copper plate of the novel transformer spiral plate type winding.
Detailed Description
The S13-400/10 + -2X 0.25%/0.4 transformer was chosen for implementation. Compared with the most common drawing in the industry at present, the model of a comparison group is SB 13-400/10 +/-2 multiplied by 0.25%/0.4, the sections of the iron core and the winding are elliptic, the core type transformer and the concentric winding.
Examples 1, S13-400/10. + -. 2X 0.25%/0.4
National standard: load loss Pk =4200W
No-load loss P0=410W
Percent no-load current I0% =0.8%
Impedance voltage percentage Uk% =4%
Total loss P = 4930W
One, new transformer S13-400/10 +/-2X 0.25%/0.4
The design scheme is as follows: the cross section of the iron core winding is selected to be long circular
The length-to-axis ratio of the iron core is 1: 1.49, the small diameter phi of the iron core is 155mm, the main stage of the iron core is thickened by 33mm, and the sectional area of the iron core is 280.006cm2. The magnetic density of the iron core Bm =1.546T, M0=255mm, and Hw =400 mm.
The winding structure form is as follows: staggered, six magnetic balanced groups.
High-voltage winding: the number of turns is 630 turns, 600 turns and 570 turns for the flat structure of the disc winding belt. Wire gauge ZB-0.32.12X 4. Each double magnetic balance group has 15 turns/layer, and has 15 layers.
A low-voltage winding: the flat copper wire is of a spiral plate type band flattening structure, the number of turns is 24, wire gauges are 5 multiplied by 40 bare copper bars, and a paper board with the thickness of 0.5mm is padded between turns. Each magnetically balanced group has 6 turns.
The axial arrangement mode of the high-low voltage windings along the iron core column (the column of the iron core sleeved with the windings is called the core column) is as follows:
upper yoke-low voltage winding-high voltage winding-low voltage winding-lower yoke
An insulating structure: the high voltage and the low voltage are insulated by 6mm and are provided with an angle ring structure.
Comparison table of novel transformer and universal transformer in current industry
And thirdly, burst short circuit.
Because of the staggered winding, the burst short circuit capability is far superior to that of the concentrically arranged distribution transformer.
Claims (3)
1. Winding alternating distribution transformer, the characteristic is: the transformer comprises a transformer core and a transformer winding;
the transformer core adopts a core type structure;
wherein the transformer windings are arranged in a staggered manner;
the method for calculating the magnetic flux of the transformer core is the same as that of a core type transformer;
the method for calculating the impedance of the transformer is the same as that of a shell type transformer;
the transformer body consisting of the transformer iron core and the winding is of a vertical structure;
the high-voltage winding of the transformer comprises a layer winding.
2. The winding interleaved distribution transformer according to claim 1, characterized by: the cross section of the transformer core column and the cross section of the transformer winding are in an oblong shape, or an oval shape, or a rectangular shape, or a shape formed by combining a plurality of groups of curves.
3. The winding interleaved distribution transformer according to claim 1, characterized by: the cross section of the transformer core limb and the cross section of the transformer winding are circular.
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| CN109841393B true CN109841393B (en) | 2021-10-26 |
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| CN111145991A (en) * | 2020-01-25 | 2020-05-12 | 孙崇山 | Novel winding staggered distribution transformer |
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| CN2870105Y (en) * | 2006-01-18 | 2007-02-14 | 孟昭坤 | Novel dry-type transformer |
| CN101673610A (en) * | 2008-09-09 | 2010-03-17 | 联昌电子企业股份有限公司 | Transformer, spiral plate winding thereof and method for assembling same |
| CN102054566A (en) * | 2009-11-05 | 2011-05-11 | Abb技术有限公司 | Transformer winding and a method of reinforcing a transformer winding |
| CN204991396U (en) * | 2015-06-22 | 2016-01-20 | 广东明路电力电子有限公司 | Dull and stereotyped coil reactor |
| CN107464674A (en) * | 2017-09-29 | 2017-12-12 | 中国工程物理研究院电子工程研究所 | A kind of electric-force gradient gradual change transformer and flexible circuit potential device |
| CN108010683A (en) * | 2017-12-27 | 2018-05-08 | 北方民族大学 | A kind of machine car transformer |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201741542U (en) * | 2010-07-29 | 2011-02-09 | 山东达驰电气有限公司 | Helical transformer coil |
| CN101916644A (en) * | 2010-07-30 | 2010-12-15 | 刘江 | Horizontal type transformer |
| CN202487355U (en) * | 2012-03-01 | 2012-10-10 | 广西柳州特种变压器有限责任公司 | Special energy-saving transformer |
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Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2870105Y (en) * | 2006-01-18 | 2007-02-14 | 孟昭坤 | Novel dry-type transformer |
| CN101673610A (en) * | 2008-09-09 | 2010-03-17 | 联昌电子企业股份有限公司 | Transformer, spiral plate winding thereof and method for assembling same |
| CN102054566A (en) * | 2009-11-05 | 2011-05-11 | Abb技术有限公司 | Transformer winding and a method of reinforcing a transformer winding |
| CN204991396U (en) * | 2015-06-22 | 2016-01-20 | 广东明路电力电子有限公司 | Dull and stereotyped coil reactor |
| CN107464674A (en) * | 2017-09-29 | 2017-12-12 | 中国工程物理研究院电子工程研究所 | A kind of electric-force gradient gradual change transformer and flexible circuit potential device |
| CN108010683A (en) * | 2017-12-27 | 2018-05-08 | 北方民族大学 | A kind of machine car transformer |
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