CN116153634A - Combined 110kV three-phase dry-type transformer - Google Patents
Combined 110kV three-phase dry-type transformer Download PDFInfo
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- H01F27/00—Details of transformers or inductances, in general
- H01F27/28—Coils; Windings; Conductive connections
- H01F27/32—Insulating of coils, windings, or parts thereof
- H01F27/324—Insulation between coil and core, between different winding sections, around the coil; Other insulation structures
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- H01F27/26—Fastening parts of the core together; Fastening or mounting the core on casing or support
- H01F27/266—Fastening or mounting the core on casing or support
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- H01F27/30—Fastening or clamping coils, windings, or parts thereof together; Fastening or mounting coils or windings on core, casing, or other support
- H01F27/306—Fastening or mounting coils or windings on core, casing or other support
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- H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
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- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
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- H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
- H01F2027/348—Preventing eddy currents
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- H01F38/00—Adaptations of transformers or inductances for specific applications or functions
- H01F2038/006—Adaptations of transformers or inductances for specific applications or functions matrix transformer consisting of several interconnected individual transformers working as a whole
Abstract
The invention provides a combined 110kV three-phase dry-type transformer, which comprises: three single-phase transformers with the same structure; each single-phase transformer is of two columns, three single-phase transformers comprise an A column and an X column, and the structures of the A column and the X column are as follows: the iron core, the low-voltage winding and the high-voltage winding are sequentially arranged from inside to outside; an insulating material is arranged between the low-voltage winding and the high-voltage winding; the low-voltage windings of the three single-phase transformers are connected through an external connecting wire; the high-voltage windings of the three single-phase transformers are connected through external connecting wires. The combined 110kV three-phase dry-type transformer provided by the invention has the advantages of high operation safety performance, strong short circuit resistance, good insulating performance, impact resistance, environment friendliness, oil-free and flame-retardant safety products and good market prospect.
Description
Technical Field
The invention relates to the technical field of transformers, in particular to a combined 110kV three-phase dry-type transformer.
Background
In the oil immersed transformer in the prior art, the transformer oil is often added to play an insulating role, but the transformer oil has combustibility and can burn and explode when encountering flame; meanwhile, the transformer oil has the problems of being harmful to human bodies, needing to be checked regularly, leaking oil and the like.
Compared with an oil immersed transformer, the dry type transformer product has better environmental protection performance and electricity safety performance, can change the selection of power supply equipment in large-scale urban high-rise buildings, and also has wide application in the fields of data centers and new energy sources. However, as the capacity and voltage level of the dry-type transformer are continuously increased, the problems of large magnetic leakage, local overheating and surge potential of the large-capacity 110kV dry-type transformer are increased correspondingly, and the design of an insulation structure is also more and more important.
Disclosure of Invention
In view of the above, the invention provides a combined 110kV three-phase dry-type transformer, which solves the problems of large magnetic leakage, local overheating and surge oscillation potential existing in a large-capacity 110kV product along with the continuous increase of the capacity and voltage level of the dry-type transformer, and particularly solves the design problem of an insulation structure.
In order to solve the technical problems in the background technology, the invention adopts the following technical scheme:
the invention provides a combined 110kV three-phase dry-type transformer, which comprises:
three single-phase transformers with the same structure;
each single-phase transformer is of two columns, and three single-phase transformers comprise an A column and an X column; the structures of the A column and the X column are: the iron core, the low-voltage winding and the high-voltage winding are sequentially arranged from inside to outside; an insulating material is arranged between the low-voltage winding and the high-voltage winding;
the low-voltage windings on the A column and the X column are respectively divided into an upper low-voltage winding and a lower low-voltage winding, the upper low-voltage winding and the lower low-voltage winding in the A column are connected in series or in parallel, the upper low-voltage winding and the lower low-voltage winding in the X column are connected in series or in parallel, the low-voltage winding of the A column is connected in series or in parallel or in series-parallel with the low-voltage winding of the X column, the low-voltage windings of the three single-phase transformers after connection are respectively led out of low-voltage outgoing terminals, and the low-voltage windings of the three single-phase transformers are connected through low-voltage outgoing terminals and external connecting wires;
the high-voltage windings on the A column and the X column are respectively divided into an upper high-voltage winding and a lower high-voltage winding, the upper high-voltage winding and the lower high-voltage winding in the A column are connected in parallel, the upper high-voltage winding and the lower high-voltage winding in the X column are connected in parallel, and the high-voltage winding of the A column is connected in series with the high-voltage winding of the X column; and the high-voltage windings of the three single-phase transformers after being connected in series are respectively led out of high-voltage outlet terminals, and the high-voltage windings of the three single-phase transformers are connected with an external connecting wire through the high-voltage outlet terminals.
Further, an insulating material is arranged between the A column and the X column.
Further, the low-voltage windings of the A column and the X column are all multi-layered, and a heat dissipation air passage is arranged between two adjacent layers.
Further, the low-voltage winding is wound in a mixed mode in an N shape and a U shape; the N-shaped winding means that when the winding of the previous layer rises from the winding of the next layer to the winding of the next layer, the tail head of the winding of the previous layer and the head of the winding of the next layer are not at the same end, and the tail head and the head are connected in a diagonal manner; the U-shaped winding means that when the winding is lifted to the last layer, the tail head of the winding of the last second layer and the head of the winding of the last layer are at the same end, and the tail head and the head are connected in a flat pulling mode.
Further, the high-voltage windings of the A column and the X column are of a sectional layer type structure, wherein a main layer is formed by multiple layers and multiple sections, the high-voltage windings are provided with multiple main layers, and a heat dissipation structure is arranged between every two adjacent main layers.
Further, in the a column: the upper high-voltage winding and the lower high-voltage winding are connected in parallel at the middle part of the high-voltage winding of the A column, and a 110kV wire inlet end is arranged at the middle part parallel connection part; in the X column: the upper high-voltage winding and the lower high-voltage winding are connected in parallel and then connected in series with the high-voltage winding of the A column, and the end of the series connection is arranged in the middle of the high-voltage winding of the whole X column.
Further, in the X column: and the upper high-voltage winding and the lower high-voltage winding are both provided with on-load voltage regulation.
Further, a ground screen is arranged between the leg of the iron core and the low-voltage winding; and/or the head positions of the high-voltage wire outgoing terminals are all shielded.
Further, the three-phase dry-type transformer also comprises pull plates, wherein the pull plates are arranged on the front side and the rear side of the iron core, and the number of grooves of the pull plates is 2-6; and/or
The grooving width of the pulling plate is 2-15 mm; and/or
The length coefficient of the iron core pulling plate groove of the pulling plate is more than or equal to 1.
Further, the three-phase dry-type transformer further comprises clamping pieces, the clamping pieces are arranged on two sides of the upper iron yoke and the lower iron yoke of the iron core, each clamping piece comprises a web plate parallel to the surface of the iron yoke and limb plates perpendicular to the web plates, and the web plates and the limb plates are made of stainless steel or low-magnetic steel plates.
The technical scheme of the invention has the following beneficial effects:
the invention provides a combined 110kV three-phase dry-type transformer, which aims to solve the problems of large magnetic leakage, local overheating and impact oscillation potential of a high-capacity 110kV product, in particular to the problem of insulation structure design, and the combined 110kV three-phase dry-type transformer has the following design:
the design for the insulation structure comprises: (1) An insulating material is arranged between two columns of each single phase, and an insulating material is arranged between a low-voltage winding and a high-voltage winding of each column; (2) The lifting layer transition of the low-voltage winding adopts a diagonal structure, namely N-shaped winding, so that the interlayer voltage of the winding layer at the wire inlet side can be reduced, more importantly, the interlayer impulse gradient voltage is reduced, the longitudinal capacitance between layers is increased, the lightning impulse resistance of an interlayer air passage is improved, and the electrical safety performance of the winding is improved; (3) The 110kV wire inlet end of the high-voltage winding adopts a middle wire inlet mode, so that the lightning impulse voltage resistance of the wire inlet end of each side of the high-voltage winding is improved, and the lightning impulse voltage resistance of the whole combined three-phase dry-type transformer is further improved; (4) In the high-voltage winding of the sectional layer structure, the number of turns of the coil of each layer of each section of winding is calculated by computer software; the voltage distribution is more uniform and the voltage tends to be in a stable state when the high-voltage winding is impacted; (5) The high-voltage outlet terminal is provided with the voltage equalizing cover, so that the lightning impulse voltage resistance of the inlet wire end of each side of high-voltage winding can be improved, the lightning impulse voltage resistance of the whole combined three-phase dry-type transformer is further improved, and the requirement of the voltage resistance of the three-phase dry-type transformer under 110kV voltage class is met; (6) A ground screen is arranged between the iron core limb and the low-voltage winding, so that a slightly uneven electric field between the low-voltage winding and the iron core limb is improved, and a further even strong field is formed; (7) The positions of the heads of the high-voltage wire outgoing terminals are completely shielded so as to improve the shape of the electrode.
Structural design for the problems of magnetic leakage and local overheating includes: (1) A heat dissipation air passage is arranged between two adjacent layers of the low-voltage winding of each column; the high-voltage winding is provided with a plurality of main layers, and a heat dissipation structure is arranged between two adjacent main layers; (2) The pull plate is made of a low-magnetic steel plate or a stainless steel plate, and is provided with 2-6 channels to reduce eddy current loss; the final stage of the iron core column is provided with 2-6 channels to reduce the eddy current loss of the final stage; the slot width of the slot of the last stage of the iron core column is 2-15 mm; (3) The webs in the clamping pieces and the limb plates are made of low-magnetic steel plates or stainless steel plates, so that eddy current loss in the clamping pieces is reduced, loss of structural members of the transformer is reduced, the risk of local overheating of the transformer is reduced, and the related insulating pieces of the iron core are ensured to operate in an allowable temperature.
The combined 110kV three-phase dry-type transformer provided by the invention has the advantages of high operation safety performance, strong short circuit resistance, good insulating performance, impact resistance, environment friendliness, oil-free and flame-retardant safety products and good market prospect.
Drawings
Fig. 1 is a schematic structural diagram of a combined 110kV three-phase dry transformer;
FIG. 2 is a low voltage lead diagram of a combined 110kV three-phase dry-type transformer;
fig. 3A is a schematic diagram of a single-phase lead of a low-voltage winding of a combined 110kV three-phase dry-type transformer;
fig. 3B is a schematic diagram of three-phase leads of a low-voltage winding of a combined 110kV three-phase dry-type transformer;
fig. 4 is a high voltage lead diagram of a combined 110kV three-phase dry transformer;
fig. 5A is a schematic diagram of a single-phase lead of a high-voltage winding of a combined 110kV three-phase dry-type transformer;
fig. 5B is a schematic diagram of three-phase leads of a high-voltage winding of a combined 110kV three-phase dry-type transformer;
fig. 6 is a schematic drawing of a pulling plate slotting of a combined 110kV three-phase dry transformer.
Reference numerals:
a core 1, a low-voltage winding 2, a high-voltage winding 3, and an external connection 4;
a low-voltage two-post connecting line 21, a low-voltage support 22, and low-voltage outgoing terminals (23-1, 23-2);
the high-voltage two-column connecting wire 31, the high-voltage supporting frame 32, the high-voltage outgoing terminals (33-1, 33-2), the equalizing cover 34, the tapping lead 35, the tapping lead public end 36 and the on-load voltage-regulating tapping switch 37;
the insulation cylinder 5, the insulation partition plate 6, the ground screen 7, the web 8, the limb plate 9, the pulling plate 10 and the pulling plate slot 10-1.
Detailed Description
For a further understanding of the present invention, preferred embodiments of the invention are described below in conjunction with the examples, but it is to be understood that these descriptions are merely intended to illustrate further the features and advantages of the invention and are not limiting of the invention.
The combined 110kV three-phase dry-type transformer according to the invention is further explained below with reference to the accompanying drawings.
As shown in fig. 1, the present invention provides a combined 110kV three-phase dry transformer, the dry transformer comprising:
three single-phase transformers with the same structure; each single-phase transformer is of two columns, each single-phase transformer comprises an A column and an X column, the structures of the three single-phase A columns are identical, and the structures of the three single-phase X columns are identical; the structures of the A column and the X column are: the iron core 1, the low-voltage winding 2 and the high-voltage winding 3 are sequentially arranged from inside to outside, the low-voltage winding 2 is wound on the periphery of the iron core 1, and the high-voltage winding 3 is wound on the periphery of the low-voltage winding 2; an insulating material is arranged between the low-voltage winding 2 and the high-voltage winding 3; the low-voltage windings 2 on the A column and the X column are respectively divided into an upper low-voltage winding and a lower low-voltage winding, the upper low-voltage winding and the lower low-voltage winding in the A column are connected in series or in parallel, the upper low-voltage winding and the lower low-voltage winding in the X column are connected in series or in parallel, and then the A column and the low-voltage winding of the X column are integrally connected in series or in parallel or are mixed in series and parallel; the low-voltage windings 2 of the three single-phase transformers are respectively led out of low-voltage outlet terminals (23-1 and 23-2), the low-voltage windings 2 of the three single-phase transformers can be connected with an external connecting wire 4 through the low-voltage outlet terminals (23-1 and 23-2), and the low-voltage windings 2 of the three single-phase transformers are connected with the external connecting wire 4 through the low-voltage outlet terminals (23-1 and 23-2); the high-voltage windings 3 on the A column and the X column are respectively divided into an upper high-voltage winding and a lower high-voltage winding, the upper high-voltage winding and the lower high-voltage winding in the A column are connected in parallel, the upper high-voltage winding and the lower high-voltage winding in the X column are connected in parallel, and then the A column and the high-voltage winding of the X column are integrally connected in series; the high-voltage windings 3 of the three single-phase transformers are respectively led out of high-voltage outgoing terminals (33-1 and 33-2), the high-voltage windings 3 of the three single-phase transformers can be connected with an external connecting wire 4 through the high-voltage outgoing terminals (33-1 and 33-2), and the high-voltage windings 3 of the three single-phase transformers are connected with the external connecting wire 4 through the high-voltage outgoing terminals (33-1 and 33-2).
The structure of the combined 110kV three-phase dry-type transformer provided by the invention is shown in the attached figure 1, the three-phase dry-type transformer consists of three 1/3 capacity single-phase transformers with the same structure, each single-phase transformer is two-column type, wherein the three-phase transformers are divided into two columns according to an iron core 1: the A column and the X column are in one phase and in three phases. The structure of each of the above six columns is: the low-voltage winding 2 and the high-voltage winding 3 are arranged from inside to outside, and an insulating material is arranged between the low-voltage winding 2 and the high-voltage winding 3. Preferably, a multi-layer insulation cylinder 5 is arranged between the low-voltage winding 2 and the high-voltage winding 3, the insulation cylinder 5 is made of a heat-resistant grade H-level winding insulation cylinder, and the surface of the insulation cylinder 5 is flat and smooth and free from burrs, stains and impurities.
In the combined 110kV three-phase dry-type transformer, the three single phases have the same structure, and only one phase (a column and X column) is taken as an example for specific explanation.
For the low-voltage winding in the combined 110kV three-phase dry-type transformer, the winding mode of the low-voltage winding is as follows:
the low voltage windings 2 on the a-pillar and the X-pillar are each divided into an upper and a lower part (respectively referred to as an upper low voltage winding and a lower low voltage winding). The upper low-voltage winding and the lower low-voltage winding in the column A are connected in series or in parallel, the upper low-voltage winding and the lower low-voltage winding in the column X are connected in series or in parallel, and the column A and the low-voltage winding 2 on the column X are integrally connected in series or in parallel after being connected in series, so that a head and a head are respectively led out (see figure 3A); similarly, the low-voltage windings 2 of the other two phases respectively lead out a b (y) head and a c (z) head, and the three phases can be all connected in series, all connected in parallel or mixed in series-parallel. The three single-phase transformer low-voltage windings 2 are finally connected through an external connection 4, wherein the connection method can be an angle connection method, and fig. 3B is a three-phase lead schematic diagram of the low-voltage windings. Specifically, as shown in fig. 2, the a-pillar and the X-pillar low-voltage winding 2 are integrally connected in series through a low-voltage two-pillar connecting wire 21, are fixed through a low-voltage support 22, and respectively lead out two low-voltage wire outlet terminals a and X.
Preferably, the low voltage windings 2 on the a-pillar and the X-pillar are each divided into an upper and a lower part (respectively denoted as upper low voltage winding and lower low voltage winding). The upper low-voltage winding and the lower low-voltage winding in the column A are connected in series, the upper low-voltage winding and the lower low-voltage winding in the column X are connected in series, and the column A and the low-voltage winding 2 on the column X are connected in series integrally, so that a head and a head X are respectively led out; similarly, the low-voltage windings 2 of the other two phases lead out the b (y) and c (z) heads, respectively. The three single-phase transformer low-voltage windings 2 are finally connected into an "angle" connection by means of external connections 4.
According to some embodiments of the present invention, the low-voltage windings 2 of the a-pillar and the X-pillar are all multi-layered, and a heat dissipation air passage is provided between two adjacent layers.
According to some embodiments of the invention, the low-voltage winding 2 is mixed-wound in an N shape and a U shape; the N-shaped winding means that when the winding of the previous layer rises from the winding of the next layer to the winding of the next layer, the tail head of the winding of the previous layer and the head of the winding of the next layer are not at the same end, and the tail head and the head are connected in a diagonal manner; the U-shaped winding means that when the winding is lifted to the last layer, the tail head of the winding of the last second layer and the head of the winding of the last layer are at the same end, and the tail head and the head are connected in a flat pulling mode. The N-shaped winding method not only can reduce the interlayer voltage of the winding layer at the wire inlet side, but also can reduce the interlayer impact gradient voltage, increase the longitudinal capacitance between layers, improve the lightning impulse resistance of an interlayer air passage and improve the electrical safety performance of the winding. The U-shaped winding method is beneficial to the connection of external leads and simplifies the lead structure.
For the high-voltage winding in the combined 110kV three-phase dry-type transformer, the winding mode of the high-voltage winding is as follows:
the high-voltage winding 3 is divided into an upper part and a lower part (respectively referred to as an upper high-voltage winding and a lower high-voltage winding) on the A column and the X column. The upper high-voltage winding and the lower high-voltage winding in the column A are connected in parallel, the upper high-voltage winding and the lower high-voltage winding in the column X are connected in parallel, and the column A and the high-voltage winding 3 on the column X are integrally connected in series after being connected in parallel to respectively lead out a head and a head X (see figure 5A); similarly, the other two phases of high-voltage windings 3 are led out of the B (Y) and C (Z) heads, respectively. The three single-phase transformer high-voltage windings 3 are finally connected into a star-shaped connection through an external connection wire 4, and fig. 5B is a three-phase lead schematic diagram of the high-voltage windings. Specifically, as shown in fig. 4, the high-voltage windings 3 of the a-pillar and the X-pillar are integrally connected in series through a high-voltage two-pillar connecting wire 31, and are fixed through a high-voltage supporting frame 32, and two high-voltage wire outlet terminals a and X are respectively led out.
According to some embodiments of the present invention, the high-voltage winding 3 of the a-pillar and the X-pillar is a segmented layered structure, wherein one main layer is composed of multiple layers and multiple segments, the high-voltage winding 3 has multiple main layers, and a heat dissipation structure is disposed between two adjacent main layers. Specifically, in the present invention, the high-voltage winding 3 may be provided with three main layers, and a heat dissipation structure is provided between two adjacent main layers.
According to some embodiments of the invention, in the a column: the upper high-voltage winding and the lower high-voltage winding are connected in parallel in the middle of the high-voltage winding 3 of the whole A column, and a 110kV wire inlet end is arranged at the parallel connection position of the middle; in the X column: the upper high-voltage winding and the lower high-voltage winding are connected in parallel and then connected in series with the high-voltage winding 3 of the A column, and the end of the series connection is arranged in the middle of the high-voltage winding 3 of the whole X column.
According to some embodiments of the invention, in the X column: the upper high-voltage winding and the lower high-voltage winding are respectively provided with on-load voltage regulation, and the on-load voltage regulation is close to the middle lower parts of the upper high-voltage winding and the lower high-voltage winding.
Referring to fig. 5A and 5B, the high-voltage winding 3 is not tapped on the a-pillar, the upper high-voltage winding and the lower high-voltage winding are connected in parallel at the middle part of the high-voltage winding 3 of the whole a-pillar, and a 110kV lead-in end is arranged at the middle parallel part (i.e. the middle lead-in) of the high-voltage winding of the whole a-pillar, so that the lightning impulse voltage resistance of the lead-in end of each high-voltage winding 3 at each side can be improved, the lightning impulse voltage resistance of the whole combined three-phase dry transformer is further improved, and the requirement of the insulating voltage resistance of the three-phase dry transformer under 110kV voltage level is met. The upper and lower high-voltage windings of the 3X column of the high-voltage winding are connected in parallel, and the wire end connected in series with the A column is arranged in the middle of the whole X column high-voltage coil. The on-load voltage regulation tapping is arranged near the middle lower parts of the upper high-voltage winding and the lower high-voltage winding; the on-load voltage-regulating tapping of the upper and lower high-voltage windings is connected with the on-load voltage-regulating tapping switch 37 after being connected with the common end 36 of the tapping lead through the tapping lead 35 in parallel.
According to some embodiments of the present invention, the high-voltage outlet terminals (33-1, 33-2) are provided with the equalizing cover 34, which can improve the lightning impulse voltage resistance of the incoming line end of each side high-voltage winding, further improve the lightning impulse voltage resistance of the whole combined three-phase dry-type transformer, and meet the requirement of the insulating voltage resistance of the three-phase dry-type transformer under 110kV voltage level.
The design of the proposal is largeThe capacity combined type 110kV three-phase dry-type transformer improves the lightning impulse voltage resistance of the inlet wire end of each single-phase transformer by arranging the inlet wire end of the three-phase transformer in the middle of the high-voltage winding at the inlet wire side of each single-phase transformer, further improves the voltage resistance of the combined type three-phase dry-type transformer, meets the requirement of the insulating voltage resistance of the three-phase dry-type transformer under 110kV voltage level, solves the problem of insufficient insulating property of the transformer in the prior art, and the three-phase dry-type transformer does not contain flammable transformer oil or SF (sulfur hexafluoride) with no greenhouse effect 6 The gas has strong short circuit resistance, and is a safe, flame-retardant and environment-friendly power transformer.
For the main insulation, in order to make the insulation design of the transformer reliable, attention should be paid to the electric field distribution of each part, the insulation structure and the maximum electric resistance of the insulation material when the transformer is subjected to various overvoltage actions in operation. For the longitudinal insulation of transformers, particular attention is paid to the potential distribution along the axial height of the windings and to the inter-winding potential difference distribution under the action of the shock waves. The actual operation condition of the transformer shows that the lightning strike impact causes the insulation damage of the transformer to occupy 60 percent, and lightning strike waves invade a substation along a transmission line to cause the transformer to suffer impact, so that a complex electromagnetic process, namely a wave process of a winding, is generated on the winding. The design of the dry-type transformer with a more reasonable and more economical insulation structure has important significance.
According to some embodiments of the invention, in the high-voltage winding of the segmented layer structure, the number of coil turns of each layer of each segment of winding is calculated by computer software.
Specifically, in an alternative embodiment of the present invention: under the action of impulse voltage, the equivalent frequency of voltage waveform is extremely high, so that the influence of inter-turn and inter-segment capacitance of winding and the capacitance to ground of winding can not be ignored, and under the action of impulse voltage, the inductance energy and capacitance energy of winding can be exchanged to form an oscillation process, and the inter-turn, inter-segment and ground potential of winding can not be distributed according to turns, and the potential difference between the inter-turn and inter-segment and the ground potential and power frequency can be greatly exceeded, so that it is necessary to adopt reasonable insulating structure to improve impulse voltage distribution, and ensure that under the action of impulse voltage, the winding has sufficient insulating reliability.
The high-voltage winding of the combined transformer can be used for calculating the wave process in the winding by using computer software, and the optimal design scheme can be selected according to the calculation result. Specifically, computer software forms a finite electric branch through a discrete transformer winding, forms an equivalent circuit, obtains a required calculation result by solving a partition capacitance and inductance matrix of a centralized parameter, and comprises the following calculation contents:
1) Winding capacitance and inductance matrix;
2) Initial and final potential profiles of the windings;
3) The maximum winding-to-ground potential envelope curve;
4) Gradient between winding segments and allowable safety margin distribution curve;
5) Considering the allowable breakdown voltage of the volt-second characteristic transformer insulation medium (in particular: the maximum Xu Yongchang strength of the resin-air interface under the action of lightning impulse full wave);
6) A time-varying voltage gradient profile between any of the nodes of the winding;
7) A transformer inlet capacitance;
the high-voltage winding adopts the partition design calculation result, each layer of turns on a specific section of the segmented winding is adjusted, the longitudinal capacitance is increased to reach an optimal compensation state by adjusting the configuration of the turns capacitance of each section, and the capacitance distribution is more ideal, so that when the winding is impacted, the voltage distribution is more uniform and the winding is more stable; the transient voltage distribution of the winding, namely the potential gradient of the winding on the transverse equivalent capacitance and the maximum potential distribution condition of the winding on the longitudinal equivalent capacitance are greatly improved, and the oscillation frequency in the transition process is obviously reduced; compared with the traditional uniform design scheme, the oscillation peak value is reduced by 45%; the oscillation peak value of the potential difference in the middle of the transformer winding is reduced by 75%; the gradient of the voltage regulating range, the inter-stage gradient and the ground potential of the tapping contacts can be reduced under the action of lightning impulse voltage, and the insulation strength of the winding is improved.
In an alternative implementation of this embodiment: from the magnetic potential balance law and the relation between the impedance and the magnetic potential, the impedance of the single-phase double-winding transformer is the sum of the impedance of the A column and the impedance of the X column, namely:
U k ％＝U KA ％+U KX ％；
wherein: i W: reference magnetic potential, I W =i GA W GA +I GX W GX ；
I GA : a column A high-voltage winding current;
I GX : x column high voltage winding current;
W GA : the number of turns of the high-voltage winding of the column A;
W GX : the number of turns of the X-column high-voltage winding.
A. When the X two columns are in rated tapping, the turns of the high-voltage winding and the low-voltage winding are completely consistent; namely W GA ＝W GX At this time, the ampere turns of the high-voltage winding and the low-voltage winding are balanced;
A. the turns of the high-voltage windings of the two X columns are different when the two X columns are in the most positive tapping and the most negative tapping, namely W GA ≠W GX The method comprises the steps of carrying out a first treatment on the surface of the Under the working condition, unbalance of high and low voltage ampere turns is caused, so that impedance change of a transformer and local stray loss are caused to be increased suddenly (the impedance change causes uneven distribution of magnetic leakage, so that the control of the distribution of the magnetic leakage is one of important factors for ensuring the heat resistance of the transformer, along with the increase of the capacity of a single product, the magnetic leakage field is also increased rapidly, and for a large-capacity single-phase giant dry-type transformer, the magnetic leakage is a prominent problem which has to be solved, if the magnetic leakage is controlled improperly, the magnetic leakage is likely to be concentrated at a certain position of a winding and a steel structural member to cause local overheating, and the distribution of the eddy current loss generated in the adjacent metal member is extremely not caused due to the magnetic field of the windingEven, if the design is improper, the local overheat is easy to be generated at the part with concentrated eddy current loss, the leakage magnetic field generated by winding current can generate loss in the metal structural members such as upper clamping pieces, lower clamping pieces, pull plates and the like, the loss is a component part of the load loss of the transformer, the stray loss concentrated on a small area can often cause the local overheat problem in the winding and the structural members), and in order to ensure the safety margin of the structural members of the transformer and eliminate the local overheat, the structure of the three-phase transformer is further improved, and the technical scheme is as follows:
(1) The three-phase dry-type transformer further comprises pull plates 10, wherein the pull plates 10 are arranged at the upper end and the lower end of the iron core 1, and the number of grooves of the pull plates 10 is 2-6; and/or the grooving width of the pull plate 10 is 2-15 mm; and/or the core pulling plate slot length coefficient of the pulling plate 10 is greater than 1. Specifically, the pull plate 10 is made of a low-magnetic steel plate or a stainless steel plate. The pull plate 10 is provided with 2-6 channels to reduce eddy current loss in the pull plate 10; the final stage of the iron core column is provided with 2-6 channels to reduce the eddy current loss of the final stage; the slot width of the slot of the last stage of the iron core column of the pull plate 10 is 2-15 mm; the ratio of the slot length of the pull plate 10 and the final pole piece of the iron core limb to the winding height is more than 1. A schematic illustration of the slotting of the pull plate 10 of the present invention is shown in fig. 6;
(2) The three-phase dry-type transformer further comprises clamping pieces, the clamping pieces are arranged on two sides of the upper iron yoke and the lower iron yoke of the iron core 1, each clamping piece comprises a web 8 parallel to the surface of the iron yoke and a limb plate 9 perpendicular to the web 8, the web 8 and the limb plates 9 are made of low-magnetic steel plates or stainless steel plates, eddy current loss in the clamping pieces can be reduced, transformer structural member loss is reduced, the risk of local overheating of the transformer is reduced, and the operation of related insulating pieces of the iron core is ensured to be within an allowable temperature.
According to some embodiments of the invention, an insulating material is disposed between the a-pillar and the X-pillar in three phases; preferably, the insulating material may be a plurality of insulating spacers 6, and the insulating spacers 6 are made of insulating material with heat-resistant grade H; the surfaces of all the insulating spacers 6 are flat and smooth and free from burrs, stains and impurities.
According to some embodiments of the invention, a ground shield 7 is arranged between the leg of the core 1 and the low voltage winding 2. Since the voltage of the low-voltage winding 2 is 35kV, in order to meet the insulation requirement and improve the electrode shape of the core column of the iron core 1, a ground screen 7 is arranged between the core column of the iron core 1 and the low-voltage winding 2, so that a slightly uneven electric field between the low-voltage winding 2 and the core column of the iron core 1 is improved, and a further even strong field is achieved.
According to some embodiments of the present invention, in order to further improve the insulation performance of the combined 110kV three-phase dry-type transformer, the structure of the transformer is designed as follows: the positions of the heads of the high-voltage wire outgoing terminals (33-1, 33-2) are completely shielded to improve the electrode shape. Furthermore, the invention also carries out rounding treatment on the casting part of the winding end part, the body cushion block of the transformer, the forming part, the lead clamping part and other insulating parts; chamfering and rounding the metal parts in the transformer; and ensuring the distance between the external lead and each charged point and the insulation distance to ground.
In summary, in the combined 110kV three-phase dry-type transformer provided by the invention, the following components are included:
the design for the insulation structure comprises: (1) An insulating material is arranged between two columns of each single phase, and an insulating material is arranged between a low-voltage winding 2 and a high-voltage winding 3 of each column; (2) The lifting layer transition of the low-voltage winding 2 adopts a diagonal structure, namely N-shaped winding, so that the interlayer voltage of a winding layer at the wire inlet side can be reduced, more importantly, the interlayer impact gradient voltage is reduced, the longitudinal capacitance between layers is increased, the lightning impulse resistance of an interlayer air passage is improved, and the electrical safety performance of the winding is improved; (3) The 110kV inlet wire end of the high-voltage winding 3 adopts a middle inlet wire mode, so that the lightning impulse voltage resistance of the inlet wire end of each side of the high-voltage winding is improved, and the lightning impulse voltage resistance of the whole combined three-phase dry-type transformer is further improved; (4) In the high-voltage winding 3 with the sectional layer structure, the number of turns of each layer of each section of winding is calculated by computer software; the voltage distribution is more uniform and the voltage tends to be in a stable state when the high-voltage winding is impacted; (5) The high-voltage outlet terminals (33-1, 33-2) are provided with the equalizing cover 34, so that the lightning impulse voltage resistance of the inlet wire end of each side of the high-voltage winding 3 can be improved, the lightning impulse voltage resistance of the whole combined three-phase dry-type transformer is further improved, and the requirement of the insulating voltage resistance of the three-phase dry-type transformer under the 110kV voltage level is met; (6) A ground screen 7 is arranged between the iron core limb and the low-voltage winding 2, so that a slightly uneven electric field between the low-voltage winding 2 and the iron core limb is improved, and a further even strong field is achieved; (7) The positions of the heads of the high-voltage wire outgoing terminals (33-1, 33-2) are completely shielded to improve the electrode shape.
Structural design for the problems of magnetic leakage and local overheating includes: (1) A heat dissipation air passage is arranged between two adjacent layers of the low-voltage winding 2 of each column; the high-voltage winding 3 is provided with a plurality of main layers, and a heat dissipation structure is arranged between two adjacent main layers; (2) The pull plate 10 is made of a low-magnetic steel plate or a stainless steel plate, and is provided with 2-6 channels to reduce eddy current loss; the final stage of the iron core column is provided with 2-6 channels to reduce the eddy current loss of the final stage; the slot width of the slot of the last stage of the iron core column is 2-15 mm; (3) The web 8 and the limb plates 9 in the clamping piece are made of low-magnetic steel plates or stainless steel plates, so that eddy current loss in the clamping piece is reduced, loss of a transformer structural member is reduced, risk of local overheating of the transformer is reduced, and operation of related insulating pieces of the iron core 1 is ensured to be within an allowable temperature.
In addition, the large-sized 110kV dry-type transformer substation has an important role in a transformer system, and in a large-load operation season, if a three-phase common transformer type 110kV transformer is out of operation due to faults, the influence on regional economy and life of people is often difficult to measure, so that maintenance power failure time of equipment is reduced as much as possible, and the transformer type 110kV transformer is a very important factor in equipment type selection; in addition, the three-phase common transformer type 110kV transformer is difficult to solve in situ due to the special structure of the transformer, equipment can be generally replaced only, the three-phase common transformer type 110kV transformer is difficult to transport, the single structure is complex (particularly an insulation system), the power supply reliability is low, and the fault is difficult to repair in a short time if the fault occurs. By adopting the three single-phase combined transformers provided by the invention, only 1 standby single-phase transformer with the same parameters is configured, and when an accident occurs, the standby single-phase transformer is replaced, so that the power supply can be recovered in a short time, and the power supply continuity and reliability can be met.
Unless defined otherwise, technical or scientific terms used herein should be given the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs. The terms "first," "second," and the like, as used herein, do not denote any order, quantity, or importance, but rather are used to distinguish one element from another. The terms "connected" or "connected," and the like, are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "upper", "lower", "left", "right", etc. are used merely to indicate a relative positional relationship, which changes accordingly when the absolute position of the object to be described changes.
While the foregoing is directed to the preferred embodiments of the present invention, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the present invention.
Claims (10)
1. A modular 110kV three-phase dry transformer, comprising:
three single-phase transformers with the same structure;
each single-phase transformer is of two columns, and three single-phase transformers comprise an A column and an X column; the structures of the A column and the X column are: the iron core, the low-voltage winding and the high-voltage winding are sequentially arranged from inside to outside; an insulating material is arranged between the low-voltage winding and the high-voltage winding;
the low-voltage windings on the A column and the X column are respectively divided into an upper low-voltage winding and a lower low-voltage winding, the upper low-voltage winding and the lower low-voltage winding in the A column are connected in series or in parallel, the upper low-voltage winding and the lower low-voltage winding in the X column are connected in series or in parallel, the low-voltage winding of the A column is connected in series or in parallel or in series-parallel with the low-voltage winding of the X column, the low-voltage windings of the three single-phase transformers after connection are respectively led out of low-voltage outgoing terminals, and the low-voltage windings of the three single-phase transformers are connected through low-voltage outgoing terminals and external connecting wires;
the high-voltage windings on the A column and the X column are respectively divided into an upper high-voltage winding and a lower high-voltage winding, the upper high-voltage winding and the lower high-voltage winding in the A column are connected in parallel, the upper high-voltage winding and the lower high-voltage winding in the X column are connected in parallel, and the high-voltage winding of the A column is connected in series with the high-voltage winding of the X column; and the high-voltage windings of the three single-phase transformers after being connected in series are respectively led out of high-voltage outlet terminals, and the high-voltage windings of the three single-phase transformers are connected with an external connecting wire through the high-voltage outlet terminals.
2. The combined 110kV three-phase dry transformer of claim 1, wherein an insulating material is disposed between the a-pillar and the X-pillar.
3. The combined 110kV three-phase dry-type transformer according to claim 1, wherein the low-voltage windings of the A column and the X column are all multi-layered, and a heat dissipation air passage is arranged between two adjacent layers.
4. The combined 110kV three-phase dry-type transformer according to claim 3, wherein the low-voltage winding is formed by mixing and winding in an N shape and a U shape;
the N-shaped winding means that when the winding of the previous layer rises from the winding of the next layer to the winding of the next layer, the tail head of the winding of the previous layer and the head of the winding of the next layer are not at the same end, and the tail head and the head are connected in a diagonal manner; the U-shaped winding means that when the winding is lifted to the last layer, the tail head of the winding of the last second layer and the head of the winding of the last layer are at the same end, and the tail head and the head are connected in a flat pulling mode.
5. The combined 110kV three-phase dry-type transformer according to claim 1, wherein the high-voltage windings of the A column and the X column are of a segmented layered structure, wherein one main layer is formed by multiple layers and multiple sections, the high-voltage windings are provided with a plurality of main layers, and a heat dissipation structure is arranged between two adjacent main layers.
6. The combined 110kV three-phase dry transformer of claim 1, wherein the a-pole is: the upper high-voltage winding and the lower high-voltage winding are connected in parallel at the middle part of the high-voltage winding of the A column, and a 110kV wire inlet end is arranged at the middle part parallel connection part;
in the X column: the upper high-voltage winding and the lower high-voltage winding are connected in parallel and then connected in series with the high-voltage winding of the A column, and the end of the series connection is arranged in the middle of the high-voltage winding of the whole X column.
7. The combined 110kV three-phase dry transformer of claim 6, wherein the X-pole is: and the upper high-voltage winding and the lower high-voltage winding are both provided with on-load voltage regulation.
8. The combined 110kV three-phase dry transformer of claim 1, wherein a ground shield is disposed between the leg of the core and the low voltage winding; and/or
The positions of the heads of the high-voltage outgoing terminals are all shielded.
9. The combined 110kV three-phase dry-type transformer according to claim 1, further comprising pull plates, wherein the pull plates are arranged on the front side and the rear side of the iron core, and the number of slots of the pull plates is 2-6; and/or
The grooving width of the pulling plate is 2-15 mm; and/or
The length coefficient of the iron core pulling plate groove of the pulling plate is more than or equal to 1.
10. The combined 110kV three-phase dry-type transformer according to claim 1, further comprising clamping pieces, wherein the clamping pieces are arranged on two sides of an upper iron yoke and a lower iron yoke of the iron core, the clamping pieces comprise webs parallel to the surfaces of the iron yokes and limb plates perpendicular to the webs, and the webs and the limb plates are made of stainless steel or low-magnetic steel plates.
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117150791A (en) * | 2023-09-05 | 2023-12-01 | 正泰电气股份有限公司 | Method and device for optimally designing main insulation structure of transformer |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117150791A (en) * | 2023-09-05 | 2023-12-01 | 正泰电气股份有限公司 | Method and device for optimally designing main insulation structure of transformer |
| CN117150791B (en) * | 2023-09-05 | 2024-03-26 | 正泰电气股份有限公司 | Method and device for optimally designing main insulation structure of transformer |
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