CN112038073A - Transformer current limiting device and current limiting method thereof - Google Patents
Transformer current limiting device and current limiting method thereof Download PDFInfo
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- CN112038073A CN112038073A CN202010683483.5A CN202010683483A CN112038073A CN 112038073 A CN112038073 A CN 112038073A CN 202010683483 A CN202010683483 A CN 202010683483A CN 112038073 A CN112038073 A CN 112038073A
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- 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
- H01F27/40—Structural association with built-in electric component, e.g. fuse
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- 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
- H01F27/08—Cooling; Ventilating
- H01F27/10—Liquid cooling
- H01F27/12—Oil cooling
- H01F27/14—Expansion chambers; Oil conservators; Gas cushions; Arrangements for purifying, drying, or filling
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- 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
- H01F27/40—Structural association with built-in electric component, e.g. fuse
- H01F27/402—Association of measuring or protective means
Abstract
A transformer current-limiting device and its current-limiting method, in the said transformer current-limiting device, install iron core, high-voltage winding and low-voltage winding in the oil tank of the transformer, the current-limiting reactor is set up in the said oil tank of the transformer and connected in series to the end of the said high-voltage winding, both ends of the said current-limiting reactor are drawn out from the wall of the said oil tank of the transformer via the lead wire, the said current transfer branch connects the said current-limiting reactor via the lead wire, the current transfer branch includes branch 1, branch 2 and oscillating branch, wherein, branch 1 is connected in series by semi-controlled power semiconductor device VD1 and semi-controlled power semiconductor device VD2 positive pole, branch 2 is connected in series by semi-controlled power semiconductor device VD3 and semi-controlled power semiconductor device VD4 negative pole, the oscillating branch is composed of transfer capacitor C and oscillating inductance L1 of the pre-charging, the arrester, the zinc oxide lightning arrester is connected with the current transfer branch in parallel.
Description
Technical Field
The invention relates to the field of transformers, in particular to a transformer current limiting device and a current limiting method thereof.
Background
The transformer is a junction of power transmission of a power grid and is a main device for running of the power grid, the transformer is a device for changing alternating current voltage by utilizing the principle of electromagnetic induction, and when a power transformer winding is in short circuit, especially when a load is in short circuit, the damage of huge electromagnetic force generated by fault current to the transformer winding is great, the normal use of the transformer can be influenced, and even the whole power transmission system can be influenced in serious cases.
In the existing transformer structure, in order to avoid the harm caused by the short circuit of the transformer, measures are taken to improve the short circuit strength of the transformer in the design and manufacturing process, such as keeping ampere-turn balance, strengthening the support between the winding and the core limb, increasing the number of supporting strips, improving the strength and hardness of the winding lead, the lead and the clamping piece, and the like. However, due to the cumulative effect of short-circuit, the short-circuit strength of the winding is reduced after multiple short-circuit current surges, so that short-circuit failure may still occur. And secondly, the short-circuit current is limited by adopting a mode of improving short-circuit impedance or externally connecting a current-limiting reactor, the operation loss of the mode is large, the bus voltage is increased along with the fluctuation of the load, the problem of electric energy quality is caused, and the operation mode of a power grid is limited. Thirdly, a fault current limiter is additionally arranged. At present, fault current limiters are mainly divided into superconducting type, power electronic type and conventional equipment type current limiters. The superconducting and power electronic fault current limiters are high in manufacturing cost and high in operating cost, and conventional equipment type current limiters can be divided into a resonant type, an arc transfer type and a fast switch type according to the principle. The resonant current limiter has the advantages that through-flow occurs in capacitance and inductance elements when the resonant current limiter normally operates, so that the loss is large, the arc transfer current limiter depends on short-circuit fault rapid identification and artificial zero-crossing technologies, the structure is complex, the reliability is low, the rapid switch current limiter limits current after the short-circuit current naturally crosses zero, the first peak value of the short-circuit current cannot be limited, the current limiting effect is poor, all fault current limiters are the same as a current limiting reactor, a large installation position is needed during actual use, and the current limiters are more and more limited under the conditions that the occupied area of a transformer substation is smaller and smaller, and. In summary, under the condition that the installation floor area is limited by the size, a current limiting device which is small in size, convenient to install and maintain, free of increasing operation loss and good in current limiting effect is urgently needed, and no economic and reliable technical measure is provided for limiting the short-circuit current of the transformer at present.
The above information disclosed in this background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.
Disclosure of Invention
In view of the above-mentioned deficiencies or drawbacks of the prior art, an object of the present invention is to provide a current limiting device and a current limiting method for a transformer, wherein a current limiting reactor is disposed in an oil tank of the transformer, so that when a short-circuit fault occurs, a short-circuit current can be limited before the short-circuit current reaches a peak value, and the transformer is prevented from suffering a large short-circuit current impact, thereby greatly reducing an accumulative effect of a short circuit, preventing the transformer from suffering from short-circuit impact damage, prolonging a life of the transformer, reducing a load of a related breaker on/off short-circuit current, and being convenient and fast to maintain without increasing loss.
The purpose of the invention is realized by the following technical scheme.
The transformer current limiting device comprises a current limiting device,
the transformer oil tank is internally provided with an iron core, a high-voltage winding and a low-voltage winding,
a current limiting reactor provided in the transformer tank and connected in series to an end of the high-voltage winding, both ends of the current limiting reactor being led out from a wall of the transformer tank via a lead wire,
the current transfer branch is arranged outside the transformer oil tank and is connected with the current-limiting reactor through a lead, the current transfer branch comprises a branch 1, a branch 2 and an oscillation branch, wherein the branch 1 is formed by connecting a semi-controlled power semiconductor device VD1 and a semi-controlled power semiconductor device VD2 in series, the branch 2 is formed by connecting a semi-controlled power semiconductor device VD3 and a semi-controlled power semiconductor device VD4 in series, and the oscillation branch is formed by a pre-charged transfer capacitor C and an oscillation inductor L1,
and the zinc oxide lightning arrester is arranged outside the transformer oil tank and is connected with the current transfer branch in parallel.
In the transformer current-limiting equipment, a medium-voltage winding is also arranged in a transformer oil tank.
In the transformer current-limiting device, the current-limiting reactor is a single-phase current-limiting reactor.
In the transformer current limiting device, the current limiting reactor comprises an air core current limiting reactor.
In the transformer current-limiting device, the current-limiting reactor is fixed by an iron core clamping piece of the transformer, and an insulating piece is arranged between the iron core clamping piece and the current-limiting reactor in a cushioning mode.
In the transformer current limiting device, the insulating part is a rubber product.
In the transformer current-limiting device, the semi-controlled power semiconductor devices VD1, VD2, VD3 and VD4 are any one or a combination of more of GTO, thyristor and IGBT.
According to another aspect of the present invention, a current limiting method of a current limiting apparatus for a transformer includes the steps of,
the current-limiting reactor is arranged in the transformer oil tank and is connected in series with the tail end of the high-voltage winding, two ends of the current-limiting reactor are led out from the wall of the transformer oil tank through leads,
establish current transfer branch road outside the transformer tank via the lead wire connects current-limiting reactor, establishes zinc oxide arrester outside the transformer tank connects in parallel current transfer branch road, when high-voltage winding and low-voltage winding produced short-circuit current, current-limiting reactor restriction short-circuit current, and the oscillation branch road injects the reverse phase high frequency oscillation current to current-limiting reactor, and current-limiting reactor constantly charges to the transfer capacitance, and when current-limiting reactor both ends voltage exceeded the switching-on threshold value of zinc peroxide arrester, the zinc oxide arrester switched on, because the on-state resistance of zinc oxide arrester is far less than the on-state resistance of current transfer branch road, the current shifts to the zinc oxide arrester fast.
The invention limits the short-circuit current of the transformer, does not increase the operation loss and improves the economic benefit. The current limiting device has the advantages of simple structure, no need of complex control technology, quick and automatic current limiting function, high reliability and further improved current limiting effect through the current transfer branch. The invention has compact structure and no need of additional installation field, thereby having wider application prospect.
The above description is only an overview of the technical solutions of the present invention, and in order to make the technical means of the present invention more clearly apparent, and to make the implementation of the content of the description possible for those skilled in the art, and to make the above and other objects, features and advantages of the present invention more obvious, the following description is given by way of example of the specific embodiments of the present invention.
Drawings
Various other advantages and benefits of the present invention will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort. Also, like parts are designated by like reference numerals throughout the drawings.
In the drawings:
fig. 1 is a schematic structural view of a transformer current limiting device according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a current diverting branch of a transformer current limiting device according to one embodiment of the invention.
The invention is further explained below with reference to the figures and examples.
Detailed Description
Specific embodiments of the present invention will be described in more detail below with reference to fig. 1 and 2. While specific embodiments of the invention are shown in the drawings, it should be understood that the invention may be embodied in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
It should be noted that certain terms are used throughout the description and claims to refer to particular components. As one skilled in the art will appreciate, various names may be used to refer to a component. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. The description which follows is a preferred embodiment of the invention, but is made for the purpose of illustrating the general principles of the invention and not for the purpose of limiting the scope of the invention. The scope of the present invention is defined by the appended claims.
For the purpose of facilitating an understanding of the embodiments of the present invention, the following description will be made by way of example of several specific embodiments with reference to the accompanying drawings, which are not intended to limit the embodiments of the present invention.
Fig. 1 is a schematic structural diagram of a transformer current limiting device according to an embodiment of the present invention, which will be described in detail with reference to fig. 1.
As shown in fig. 1 to 2, a transformer current limiting apparatus includes,
a transformer oil tank 6, wherein an iron core 7, a high-voltage winding 1 and a low-voltage winding 5 are arranged in the transformer oil tank,
a current limiting reactor 2 provided in the transformer tank 6 and connected in series to an end of the high-voltage winding 1, both ends of the current limiting reactor 2 being led out from a wall of the transformer tank 6 via a lead wire,
the current transfer branch circuit 8 is arranged outside the transformer oil tank and is connected with the transformer current limiting device, the current transfer branch circuit comprises a branch circuit 1, a branch circuit 2 and an oscillation branch circuit, wherein the branch circuit 1 is formed by connecting a semi-control type power semiconductor device VD1 and a semi-control type power semiconductor device VD2 in series, the branch circuit 2 is formed by connecting a semi-control type power semiconductor device VD3 and a semi-control type power semiconductor device VD4 in series, the oscillation branch circuit is formed by connecting a pre-charged transfer capacitor C and an oscillation inductor L1 in series,
and the zinc oxide lightning arrester 4 is arranged outside the transformer oil tank 6, and the zinc oxide lightning arrester 4 is connected with the current transfer branch circuit 8 in parallel.
The invention has compact structure, is suitable for the condition that the installation land occupation is limited by size, is convenient to install and maintain, does not increase the operation loss, avoids the problem of electric energy quality caused by the increase of the bus voltage along with the fluctuation of the load, does not limit the operation mode of a power grid, and has good current limiting effect, economy and reliability.
In the preferred embodiment of the transformer current limiting device, a medium voltage winding is further arranged in the transformer oil tank 6.
In the preferred embodiment of the transformer current limiting device, the current limiting reactor 2 is a single-phase current limiting reactor 2.
In a preferred embodiment of the transformer current limiting device, the current limiting reactor 2 comprises an air core current limiting reactor 2.
In a preferred embodiment of the current limiting device of the transformer, the current limiting reactor 2 is fixed by a core clamp of the transformer, and an insulating member is padded between the core clamp and the current limiting reactor 2.
In a preferred embodiment of the current limiting device for a transformer, the insulating member is a rubber product.
In a preferred embodiment of the transformer current limiting device, the lead wires are led out through the wall of the transformer tank 6 via an insulating sleeve.
In a preferred embodiment of the transformer current limiting device, the lead wires are led out through the wall of the transformer tank 6 via a basin insulator.
In the preferred embodiment of the transformer current limiting device, the power semiconductor devices VD1, VD2, VD3 and VD4 are any one or a combination of more of GTO, thyristor and IGBT.
To further understand the present invention, in one embodiment, in addition to placing transformer windings and cores in the transformer tank 6, a current limiting reactor 2 meeting current limiting requirements is placed in the tank 6, and a high voltage fuse 3 and zinc oxide components are placed outside the tank 6. The current limiting reactor 2 and the zinc oxide component are electrically connected in parallel. Structurally, two ends of the current-limiting reactor 2 are led out through a lead and a sleeve and are connected with a zinc oxide component. The invention utilizes the reactance of the current-limiting reactor 2 to reduce the short-circuit current under the short-circuit fault, the current-limiting reactor 2 is put into in time when the fault occurs, the loss of the transformer is not increased when the transformer works normally, the invention is suitable for manufacturing the transformer with higher requirement on the short-circuit resistance or the requirement on the limitation of the short-circuit current of the installation place.
In one embodiment, the transformer current limiting device comprises a transformer oil tank 6, an iron core 7, a high-voltage winding 1 and a low-voltage winding 6 are arranged in the transformer oil tank 6, and the technology also comprises a medium-voltage winding and a current limiting reactor 2 when the technology is used for a three-winding transformer. And a current transfer circuit and a zinc oxide lightning arrester 4 are arranged outside the transformer oil tank 6. The current-limiting reactor 2 is connected with the tail end of the transformer high-voltage winding 1, and both ends of the current-limiting reactor are led out from the wall of the transformer oil tank 6 through leads. The current limiting reactor 2 is a hollow current limiting reactor and is arranged in the transformer oil tank 6.
In one embodiment, the current limiting reactor 2 and the zinc oxide arrester 4 are electrically connected in parallel.
In one embodiment, when the external short-circuit fault occurs to the low-voltage winding 5 in the operation process of the transformer, the low-voltage winding 5 and the high-voltage winding 1 of the corresponding phase generate short-circuit current, and the current transfer is realized by the extremely steep current rising rate and the extremely high current density of the short-circuit current, so that the current limiting reactor 2 is connected to the high-voltage winding 1 when the short-circuit current does not reach the first half-wave peak value, and the short-circuit current is limited.
A current limiting method of the transformer current limiting device includes the following steps,
the current limiting reactor 2 is arranged in the transformer oil tank 6 and is connected in series with the tail end of the high-voltage winding 1, two ends of the current limiting reactor 2 are led out from the wall of the transformer oil tank 6 through lead wires,
establish current transfer branch road outside the transformer tank via the lead wire connects current-limiting reactor, establishes zinc oxide arrester outside the transformer tank connects in parallel current transfer branch road, when high-voltage winding and low-voltage winding produced short-circuit current, current-limiting reactor restriction short-circuit current, and the oscillation branch road injects the reverse phase high frequency oscillation current to current-limiting reactor, and current-limiting reactor constantly charges to the transfer capacitance, and when current-limiting reactor both ends voltage exceeded the switching-on threshold value of zinc peroxide arrester, the zinc oxide arrester switched on, because the on-state resistance of zinc oxide arrester is far less than the on-state resistance of current transfer branch road, the current shifts to the zinc oxide arrester fast.
Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments and application fields, and the above-described embodiments are illustrative, instructive, and not restrictive. Those skilled in the art, having the benefit of this disclosure, may effect numerous modifications thereto without departing from the scope of the invention as defined by the appended claims.
Claims (8)
1. A transformer current limiting device, characterized in that it comprises,
the transformer oil tank is internally provided with an iron core, a high-voltage winding and a low-voltage winding,
a current limiting reactor provided in the transformer tank and connected in series to an end of the high-voltage winding, both ends of the current limiting reactor being led out from a wall of the transformer tank via a lead wire,
the current transfer branch is arranged outside the transformer oil tank and is connected with the current-limiting reactor through a lead, the current transfer branch comprises a branch 1, a branch 2 and an oscillation branch, wherein the branch 1 is formed by connecting a semi-controlled power semiconductor device VD1 and a semi-controlled power semiconductor device VD2 in series, the branch 2 is formed by connecting a semi-controlled power semiconductor device VD3 and a semi-controlled power semiconductor device VD4 in series, and the oscillation branch is formed by a pre-charged transfer capacitor C and an oscillation inductor L1,
and the zinc oxide lightning arrester is arranged outside the transformer oil tank and is connected with the current transfer branch in parallel.
2. The transformer current limiting device according to claim 1, wherein: preferably, a medium-voltage winding is further arranged in the transformer oil tank.
3. The transformer current limiting device according to claim 1, wherein: the current limiting reactor is a single-phase current limiting reactor.
4. The transformer current limiting device according to claim 1, wherein: the current limiting reactor comprises an air core current limiting reactor.
5. The transformer current limiting device according to claim 1, wherein: the current-limiting reactor is fixed by an iron core clamping piece of the transformer, and an insulating piece is arranged between the iron core clamping piece and the current-limiting reactor in a cushioning mode.
6. The transformer current limiting device according to claim 5, wherein: the insulating part is a rubber product.
7. The transformer current limiting device according to claim 1, wherein: the semi-controlled power semiconductor devices VD1, VD2, VD3 and VD4 are any one or a combination of more of GTO, thyristor and IGBT.
8. A current limiting method of the transformer current limiting device according to any one of claims 1 to 7, comprising the steps of,
the current-limiting reactor is arranged in the transformer oil tank and is connected in series with the tail end of the high-voltage winding, two ends of the current-limiting reactor are led out from the wall of the transformer oil tank through leads,
establish current transfer branch road outside the transformer tank via the lead wire connects current-limiting reactor, establishes zinc oxide arrester outside the transformer tank connects in parallel current transfer branch road, when high-voltage winding and low-voltage winding produced short-circuit current, current-limiting reactor restriction short-circuit current, and the oscillation branch road injects the reverse phase high frequency oscillation current to current-limiting reactor, and current-limiting reactor constantly charges to the transfer capacitance, and when current-limiting reactor both ends voltage exceeded the switching-on threshold value of zinc peroxide arrester, the zinc oxide arrester switched on, because the on-state resistance of zinc oxide arrester is far less than the on-state resistance of current transfer branch road, the current shifts to the zinc oxide arrester fast.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010683483.5A CN112038073A (en) | 2020-07-15 | 2020-07-15 | Transformer current limiting device and current limiting method thereof |
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| CN202010683483.5A CN112038073A (en) | 2020-07-15 | 2020-07-15 | Transformer current limiting device and current limiting method thereof |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106786448A (en) * | 2016-09-29 | 2017-05-31 | 国家电网公司 | A kind of overvoltage protection for variable impedance transformer |
| CN107086541A (en) * | 2017-06-05 | 2017-08-22 | 国家电网公司 | The hybrid circuit breaker and its cutoff method of a kind of two-way disjunction |
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2020
- 2020-07-15 CN CN202010683483.5A patent/CN112038073A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106786448A (en) * | 2016-09-29 | 2017-05-31 | 国家电网公司 | A kind of overvoltage protection for variable impedance transformer |
| CN107086541A (en) * | 2017-06-05 | 2017-08-22 | 国家电网公司 | The hybrid circuit breaker and its cutoff method of a kind of two-way disjunction |
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