CN117524696A - Method and system for improving pressure endurance capacity of dry-type transformer - Google Patents

Method and system for improving pressure endurance capacity of dry-type transformer Download PDF

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Publication number
CN117524696A
CN117524696A CN202311491604.6A CN202311491604A CN117524696A CN 117524696 A CN117524696 A CN 117524696A CN 202311491604 A CN202311491604 A CN 202311491604A CN 117524696 A CN117524696 A CN 117524696A
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CN
China
Prior art keywords
voltage
transformer
iron core
dry
windings
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Pending
Application number
CN202311491604.6A
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Chinese (zh)
Inventor
杨哲
赵彪
崔彬
屈鲁
余占清
曾嵘
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Tsinghua University
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Tsinghua University
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Priority to CN202311491604.6A priority Critical patent/CN117524696A/en
Publication of CN117524696A publication Critical patent/CN117524696A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/28—Coils; Windings; Conductive connections
    • H01F27/2823—Wires
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/34—Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
    • H01F27/36—Electric or magnetic shields or screens

Abstract

The invention provides a method and a system for improving the voltage endurance capacity of a dry-type transformer, wherein the method comprises the following steps: the iron core is connected to a first external voltage source, the voltage of the iron core in the transformer is raised by DeltaU, and the voltage difference between the windings of the transformer and the iron core is lower than 35kV, so that the withstand voltage level of the transformer is improved. The invention realizes the improvement of the working voltage of the dry-type transformer.

Description

Method and system for improving pressure endurance capacity of dry-type transformer
Technical Field
The invention belongs to the technical field of transformer design, and particularly relates to a method and a system for improving the pressure endurance capacity of a dry-type transformer.
Background
Dry transformers are commonly used in power distribution systems and in situations where fire and explosion protection are a high requirement. The dry-type transformer has the advantages of simple structure, no pollution, light weight, convenient maintenance and overhaul and higher reliability.
Since the working voltage class of the dry type transformer is low, (the highest voltage guided in the national standard GB1094.11 of the existing dry type transformer is 35kV class), the existing dry type transformer generally only works in a scene of not exceeding 35kV. With the rapid development of the power industry, the requirement on the working voltage is continuously increased, the working voltage of the transformer in the scenes is also required to be increased, and the development of the dry-type transformer is greatly limited by the upper limit of the withstand voltage class of 35kV.
Disclosure of Invention
The invention provides a method for improving the voltage endurance capacity of a dry-type transformer, aiming at the technical problems, wherein the method comprises the following steps:
and connecting an iron core in the transformer to a first external voltage source, lifting the voltage of the iron core by delta U, and enabling the voltage difference between the windings of the transformer and the iron core to be lower than 35kV so as to improve the withstand voltage level of the transformer.
Further, the winding is sleeved on the iron core.
Further, the method further comprises:
and integrally casting the winding by using epoxy resin.
In one aspect, the present invention further provides a method for improving the voltage endurance capability of a dry-type transformer, where the method includes:
the method comprises the steps that an iron core in a transformer is connected to a first external voltage source, the voltage of the iron core is raised by delta U, and the voltage difference between windings of the transformer and the iron core is lower than 35kV, so that the withstand voltage level of the transformer is improved;
one or more stages of electric shielding devices are additionally arranged between primary/secondary windings of the transformer to ensure that the voltage difference U between the windings hl Is divided into two or more winding pairs to shield the voltage difference between the devices.
Further, the method further comprises:
the electric shielding device is connected to an intermediate potential U through a second external voltage source p 。
Further, the voltage difference U between primary/secondary windings hl Not greater than 70kV.
Further, the windings include a primary winding and a secondary winding.
Further, the electric shielding device is made of copper foil.
Further, the head-to-tail overlapping parts of the electric shielding device are overlapped by adopting insulating layers.
In another aspect, the present invention also provides a system for improving the withstand voltage capability of a dry-type transformer, wherein the system comprises:
and the lifting module is used for enabling the iron core to be connected to a first external voltage source, lifting the iron core voltage in the transformer by delta U, and enabling the voltage difference between the windings of the transformer and the iron core to be lower than 35kV so as to improve the withstand voltage level of the transformer.
Further, the winding is integrally cast with an epoxy resin.
Compared with the prior art, the method and the system for improving the voltage endurance capacity of the dry-type transformer can enable the voltage difference between charged bodies in the dry-type transformer with high working voltage (more than 35 kV) to be smaller than 35kV, and the voltage difference between the charged bodies in the transformer is divided into a plurality of small voltage differences (namely, the voltage difference between windings and a shielding device), so that on one hand, the improvement of the working voltage of the dry-type transformer is realized, and on the other hand, the voltage withstand design of the dry-type transformer with high working voltage (more than 35 kV) is ensured to be within the range of guidance of relevant standards and technical specifications.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, a brief description will be given below of the drawings required for the embodiments or the prior art descriptions, and it is obvious that the drawings in the following description are some embodiments of the present invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 illustrates a front view of an integral encapsulated winding formed with epoxy casting in accordance with an embodiment of the present invention;
FIG. 2 illustrates a top view of an integrally encapsulated winding formed with epoxy casting in accordance with an embodiment of the present invention;
FIG. 3 shows a cross-sectional view A-A of FIG. 2 in accordance with the present invention;
fig. 4 shows a flow chart of a core voltage lifting method according to an embodiment of the invention;
FIG. 5 shows a flow chart of an electrical shielding voltage division method according to an embodiment of the invention;
fig. 6 shows a schematic diagram of a transformer structure provided with a primary shielding device according to an embodiment of the present invention;
fig. 7 shows a front view of an electrical shielding device according to an embodiment of the invention;
fig. 8 shows a top view of an electrical shielding device according to an embodiment of the invention;
fig. 9 shows a top view of a gravity assisted heat pipe radiator for a power electronic device according to an embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a method and a system for improving the voltage withstand capability of a dry-type transformer, which mainly improve the voltage withstand capability of the dry-type transformer by utilizing a voltage lifting and shielding method, namely break through the voltage class limit of 35kV, and meanwhile, the voltage difference inside the dry-type transformer is not more than 35kV, and the method and the system are described below.
1) Dry type transformer introduction:
the structure of the conventional transformer (hereinafter referred to as transformer) is as follows: primary winding, secondary winding, iron core, etc.
The insulating medium (i.e., ambient gas medium) of the conventional transformer is the gas (mostly air) of the environment, but the voltage tolerance value of the transformer under the gas insulation is low due to the relatively small insulating dielectric constant of the gas (mostly air). To further enhance the voltage withstand capability of the transformer, as shown in fig. 1, 2 and 3, the primary/secondary windings may be integrally cast (i.e., integrally encapsulated windings) with epoxy resin, thereby enhancing the voltage withstand capability of the transformer.
However, epoxy resins have limited improvement in voltage withstand capability of transformers. In the transformer related design standard of the current industry reference, the design voltage is guided to be only 35kV, namely: the voltage difference between all charged bodies in the transformer is not more than 35kV at maximum, and the standard guiding range is met.
2) Introduction of transformer voltage difference:
transformer charging body: primary winding ground voltage U h Secondary winding voltage to ground U l . The core of the conventional transformer is grounded U g =0 (volt).
The voltage difference of the transformer is thus the voltage difference between the cores of the winding pairs and the voltage difference between the different windings:
①U h -U g ＝U hg
②U l -U g ＝U lg
③U h -U l ＝U hl
u according to the existing design criteria hg 、U lg 、U hl Neither can exceed the 35kV insulation level due to U g =0 kV, and therefore has the following formula:
①U h -0≤35kV
②U l -0≤35kV
③U h -U l ≤35kV
wherein U is h 、U l 、U gl None can exceedThe maximum operating voltage of the transformer is limited to 35kV beyond the 35kV insulation level.
Therefore, the invention adopts an iron core voltage lifting method and an electric shielding voltage dividing method to improve the voltage withstand capability of the transformer and ensure that the voltage difference is not more than 35kV, and the two methods are described below.
1) Iron core voltage lifting method: at high operating voltage, the voltage of the iron core is raised, the voltage difference between the winding and the iron core is reduced to be less than 35kV, and the overlarge voltage difference between the winding and the iron core is avoided, as shown in fig. 4, the method specifically comprises the following steps:
the iron core is connected to a first external voltage source, the voltage of the iron core in the transformer is raised by DeltaU, and the voltage difference between the windings of the transformer and the iron core is lower than 35kV, so that the withstand voltage level (tolerance) of the transformer is improved. At this time, the following formula is provided:
①∣U h -△U g ∣≤35kV
②∣U l -△U g ∣≤35kV
③U h >U l
the following steps are obtained:
①U h -△U g ≤35kV
②△U g -U l ≤35kV
further, it is derived that: (3) u (U) h -U l ≤70kV
It can be seen that the difference between the primary and secondary windings (primary and secondary windings) is not greater than 70kV (U) h -U l Less than or equal to 70 kV), the voltage to the ground of the primary/secondary winding is raised from 35kV to (35+ [ delta ] U) g ) And the working voltage of the winding to the ground is improved in kV. Meanwhile, the voltage difference between the iron cores of the primary winding and the secondary winding can be ensured to be not more than 35kV, and the voltage difference is within the tolerance voltage limit range of the dry-type insulation transformer.
In some embodiments of the present invention, on the basis of improving the voltage-withstanding level of the transformer, the winding may be integrally cast with epoxy resin, so as to further improve the voltage-withstanding level of the transformer.
In conclusion, through the iron core voltage lifting method, under the condition that the winding of the transformer tolerates higher voltage to the ground (more than 35 kV), the voltage difference between all charged bodies in the transformer can be ensured not to exceed 35kV, and the voltage tolerability of the transformer is improved.
2) Electric shielding voltage division method: at high winding operating voltages, the voltage difference between the primary/secondary windings is reduced to less than 35kV, as illustrated in fig. 5, and specifically includes:
the transformer comprises the following structural components: iron core, primary winding, secondary winding (primary winding can be the high voltage winding, also can be the low voltage winding, and when primary winding is the high voltage winding, secondary voltage is the low voltage winding, and when primary winding is the low voltage winding, the secondary voltage is the high voltage winding), electric shield assembly etc. therefore, on the basis of above-mentioned iron core voltage lifting method:
one or more stages of electric shielding devices are additionally arranged between windings of the transformer, and the electric shielding devices are connected to an intermediate potential U through one or more second external voltage sources p Or a plurality of different potentials, to cause a voltage difference U between windings hl Is divided into two or more voltage differences. And the voltage difference of each charged body is not more than 35kV, when the primary shielding device is provided, as shown in fig. 6:
U h -U p ≤35kV，U p -U l ≤35kV
it can be derived that when adding a primary electric shielding device, U h -U l The highest voltage withstand voltage between windings can be raised from 35kV to 70kV, while the voltage difference of windings to the shielding device is not greater than 35kV. On the premise of ensuring that the voltage difference between the charged bodies is not more than 35kV, the voltage tolerance capability between the primary winding and the secondary winding is correspondingly improved along with the increase of the number of stages of the electric shielding device.
In addition, in the present invention, the necessary conditions for the core voltage boosting and energizing the shielding device are:
the lifting of the iron core and the electric shielding device to the ground potential requires an external voltage source, so that an external voltage source with a proper voltage value is required to be set. Meanwhile, the voltage to the ground of the iron core is increased to delta U g Therefore, the iron core and the iron core are required to be alignedThe corresponding insulation design is carried out between the grounds, and a transformer is generally arranged on an insulation support to realize insulation and isolation of the iron core to the ground.
The voltage withstand capability of the transformer, the voltage difference between the winding and the electric shielding device, and the voltage difference between the winding, the electric shielding device and the iron core of the present invention are analyzed as follows.
a) Voltage endurance analysis of the transformer of the invention:
from the analysis of the core voltage lifting method and the electric shielding voltage dividing method, it is known that: voltage tolerance improving effect of transformer and iron core lifting voltage DeltaU g The number of stages of the electric shielding device (i.e. potential U p ) There is an association. However, if a transformer meeting the standard guiding voltage is to be designed, the voltage difference between the primary winding and the secondary winding is not more than 70kV (U is hl＝ U h -U l ≤70kV)。
Therefore, the design method for improving the voltage endurance capacity of the dry-type transformer is adopted, the maximum ground operation voltage of the designed transformer is constrained by the secondary side (low voltage) winding ground voltage (the parameter requires that the secondary side winding ground voltage is 1kV, and the primary side winding can only reach 71kV at most), and the design method also needs to be noted that if the primary side secondary side voltage difference per se of the transformer required by the parameter is less than 35kV, the limitation of the voltage difference between windings is avoided, and the winding ground voltage is improved according to the requirement, as long as the iron core voltage delta U is raised g To make the voltage difference delta U between the windings and the iron core g And the voltage is not more than 35kV.
Through the improvement of the equipotential of the electric shielding device and the iron core, the voltage difference between each charged body (the charged body: the iron core, the primary winding and the secondary winding in the conventional transformer) of the transformer under the high-voltage (more than 35 kV) working voltage is not more than 35kV. This ensures that high voltage (greater than 35 kV) transformers can be designed with reference to existing standards and conform to current state of the art systems.
b) Analysis of voltage difference between windings and electrical shielding
An electric shielding device is arranged between the primary winding and the secondary winding and is communicated withThe ground potential of the electrical shielding device is raised to a desired value by an external voltage source. Meanwhile, a multi-stage electric shielding device can be arranged between the primary winding and the secondary winding according to the requirements, and the ground potential of each stage of electric shielding device can be reasonably arranged through an external voltage source, so that U can be realized h And U l The voltage difference between them is divided into a plurality of small voltage differences. By adjusting the number of stages of the electric shielding and the setting of an external voltage source, each small voltage difference is ensured to be not more than 35kV.
c) Analysis of voltage difference between winding, electric shielding device and iron core
Voltage U connected to an electrical shielding device between primary and secondary windings p Less than primary winding voltage U h Meanwhile, the voltage difference between the winding and the iron core is only required to be ensured to be not more than 35kV.
The working voltage of the transformer disclosed by the invention can break through the upper limit of 35kV according to engineering requirements, the voltage difference between all charged bodies in the transformer is not more than 35kV, and the voltage tolerance design can be carried out by referring to related standards.
The invention relates to a design method for improving the voltage endurance capacity of a dry-type transformer, wherein the maximum ground operation voltage of a single transformer is designed based on the ground voltage of a secondary winding. If the problem that the voltage difference between the primary winding and the secondary winding is larger than 70kV needs to be solved in engineering, a method of connecting a plurality of transformers in series can be adopted, and for example, 4-stage series connection is adopted, namely:
first stage transformer: u (U) l :U z1 ，U z1 -U l ≥70kV
A second stage transformer: u (U) z1 :U z2 ，U z2- U z1 ≥70kV
Third stage transformer: u (U) z2 :U z3 ，U z3 -U z2 ≥70kV
Fourth stage transformer: u (U) z3 :U h ，U h -U z3 ≥70kV
The method can obtain the following steps: u (U) h -U l ≥280kV
Wherein U is z1 Is the voltage to ground of the high-voltage winding of the first transformer, U z2 Is a second transformerHigh-voltage winding of the transformer is grounded, U z3 Is the voltage to ground of the high-voltage winding of the third transformer.
So if there is a particularly large voltage difference between the primary/secondary windings, this can be solved in engineering by a series connection of multiple transformers.
In addition, in some embodiments of the present invention, the electrical shielding device is made of copper foil (not limited to copper foil material alone, and some other conductive materials may be used in the present invention). The copper foil is designed into a required shape according to the structural requirement, for example, the copper foil is manufactured into a square shape (see fig. 7 and 8), and the bent part is smoothly processed. Wherein, the lap joint of the two ends of the electric shielding device made of copper foil adopts an insulating layer for lap joint, for example, when the lap joint of the inner copper foil and the outer copper foil at the head and the tail is carried out as shown in fig. 9, the lap joint is carried out through the insulating layer (made of insulating materials), thereby separating the two ends of the electric shielding device and avoiding the two ends of the electric shielding device from directly contacting to form a closed loop circuit.
In summary, the design method for improving the voltage endurance capability of the dry-type transformer is a brand-new design thought, the voltage difference between all charged bodies in the transformer is divided into a plurality of small voltage differences (namely, the voltage difference between the windings and the shielding device), and the voltage difference between the charged bodies in the transformer with high working voltage (more than 35 kV) can be smaller than 35kV. Therefore, on one hand, the working voltage of the transformer is improved, and on the other hand, the withstand voltage design of the high working voltage (more than 35 kV) transformer is ensured to be within the scope of guidance of related standards and technical specifications, and the manufacturing of the transformer does not exceed the prior art. On the premise of not sacrificing reliability, the improvement of the voltage tolerance capability of the transformer is realized.
The design method for improving the voltage withstand capability of the dry-type transformer breaks through the technical barrier that the dry-type transformer is limited to the voltage class of 35kV. By utilizing the method, the design of the dry-type transformer can break through the limit of the highest 35kV level of working voltage and be in the standard guiding range, so that the application field of the dry-type transformer is further widened.
In another aspect, the present invention further provides a system for improving the voltage withstand capability of a transformer, where the system includes:
and the lifting module is used for enabling the iron core to be connected to a first external voltage source, lifting the iron core voltage in the transformer by delta U, and enabling the voltage difference between the windings of the transformer and the iron core to be lower than 35kV so as to improve the withstand voltage level of the transformer.
Other functions and implementation manners of each module of the system for improving the voltage withstand capability of the transformer are corresponding to and consistent with other functions and implementation manners of each step in the method for improving the voltage withstand capability of the transformer, and therefore, the description thereof is omitted herein.
The present invention is not limited to the above-mentioned embodiments, but is not limited to the above-mentioned embodiments, and any simple modification, equivalent changes and modification made to the above-mentioned embodiments according to the technical matters of the present invention can be made by those skilled in the art without departing from the scope of the present invention.

Claims (10)

1. A method of increasing the voltage withstand capability of a dry-type transformer, wherein the method comprises:
and connecting an iron core in the transformer to a first external voltage source, lifting the voltage of the iron core by delta U, and enabling the voltage difference between the windings of the transformer and the iron core to be lower than 35kV so as to improve the withstand voltage level of the transformer.
2. The method of claim 1, wherein the winding is sleeved on the core.
3. A method of increasing the withstand voltage of a dry-type transformer according to claim 1 or 2, wherein the method further comprises:
and integrally casting the winding by using epoxy resin.
4. A method of increasing the voltage withstand capability of a dry-type transformer, wherein the method comprises:
the method comprises the steps that an iron core in a transformer is connected to a first external voltage source, the voltage of the iron core is raised by delta U, and the voltage difference between windings of the transformer and the iron core is lower than 35kV, so that the withstand voltage level of the transformer is improved;
one or more stages of electric shielding devices are additionally arranged between primary/secondary windings of the transformer to ensure that the voltage difference U between the windings hl Is divided into two or more winding pairs to shield the voltage difference between the devices.
5. The method of claim 4, wherein the method further comprises:
the electric shielding device is connected to an intermediate potential U through a second external voltage source p 。
6. A method of increasing the withstand voltage of a dry-type transformer according to claim 4 or 5, wherein the voltage difference U between primary/secondary windings hl Not greater than 70kV.
7. A method of increasing the withstand voltage of a dry-type transformer as recited in claim 4 or 5, wherein said electrical shielding means is made of copper foil.
8. The method of claim 7, wherein the end-to-end joints of the electrical shielding device are joined by an insulating layer.
9. A system for improving the withstand voltage capability of a dry-type transformer, wherein the system comprises:
and the lifting module is used for enabling the iron core to be connected to a first external voltage source, lifting the iron core voltage in the transformer by delta U, and enabling the voltage difference between the windings of the transformer and the iron core to be lower than 35kV so as to improve the withstand voltage level of the transformer.
10. The system for improving the withstand voltage of a dry-type transformer of claim 9, wherein said windings are integrally cast with epoxy.
CN202311491604.6A 2023-11-09 2023-11-09 Method and system for improving pressure endurance capacity of dry-type transformer Pending CN117524696A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311491604.6A CN117524696A (en) 2023-11-09 2023-11-09 Method and system for improving pressure endurance capacity of dry-type transformer

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311491604.6A CN117524696A (en) 2023-11-09 2023-11-09 Method and system for improving pressure endurance capacity of dry-type transformer

Publications (1)

Publication Number Publication Date
CN117524696A true CN117524696A (en) 2024-02-06

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ID=89750764

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202311491604.6A Pending CN117524696A (en) 2023-11-09 2023-11-09 Method and system for improving pressure endurance capacity of dry-type transformer

Country Status (1)

Country Link
CN (1) CN117524696A (en)

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