JP2021034425A - Transformer - Google Patents

Abstract

To provide a transformer that can suppress a change in detection sensitivity depending on a position where partial discharge occurs in a winding.SOLUTION: A transformer 1 includes an iron core 10, a winding 20 wound around the iron core 10, and a detection unit 40 that detects the discharge from the winding 20. At least a part of the detection unit 40 is provided integrally with the iron core 10 and is arranged so as to be surrounded by the winding 20. Since the detection unit 40 is provided so as to be surrounded by the winding 20, even when the partial discharge generation position is wide in the axial direction of the winding 20, the partial discharge generation position in the winding 20 can be brought closer to the detection unit 40, and even when the partial discharge generation position in the winding 20 changes, the detection sensitivity of the detection unit 40 can be made uniform, and the partial discharge in the winding 20 can be detected stably and accurately.SELECTED DRAWING: Figure 1

Description

The present invention relates to a transformer, and more particularly to a transformer capable of detecting a partial discharge generated in a winding.

In a transformer, a winding having a high voltage is arranged inside a metal housing, and is insulated by an insulating material covering the winding and an insulating fluid filled in the housing. If the insulating material or the like is deteriorated for some reason, the insulating performance may be deteriorated, resulting in dielectric breakdown. Therefore, in order to prevent such dielectric breakdown, a method of detecting partial discharge, which is a sign of dielectric breakdown, is known.

A technique for detecting a partial discharge is disclosed in Patent Document 1. In Patent Document 1, a current detector detects a current that is excited and propagated by a conductor of a winding due to the occurrence of a partial discharge.

Japanese Unexamined Patent Publication No. 2003-232829

In Patent Document 1, the current detector is installed at the end of the portion wound by the conductor of the winding, and away from the end and the wound portion. For this reason, if a partial discharge occurs in the winding at a position away from the installation location of the current detector, there is a problem that the signal (change in current) due to the partial discharge is attenuated in the process of propagation and the detection sensitivity is lowered. is there.

The present invention has been made in view of this point, and one of the objects of the present invention is to provide a transformer capable of suppressing a change in detection sensitivity depending on a position where a partial discharge occurs in a winding.

The transformer of one aspect of the present invention includes an iron core, a winding wound around the iron core, and a detection unit for detecting a discharge from the winding, and at least a part of the detection unit. Is provided integrally with the iron core and is arranged at a position surrounded by the winding.

According to the present invention, since the detection unit is provided at a position surrounded by the winding in the iron core, when a partial discharge occurs in the winding, even if the generation position extends over a wide range in the axial direction of the winding, the partial discharge occurs. The position where the is generated can be brought close to the detection unit. As a result, even if the position where the partial discharge occurs in the winding changes, the attenuation due to the propagation of the current can be suppressed to make the detection sensitivity uniform in the detection unit, and the partial discharge in the winding can be stabilized. It can be detected with high accuracy.

It is a side view which shows the main part of the transformer which concerns on this embodiment. It is the schematic front view of the detection part. It is a graph which shows the frequency characteristic in an iron core and a core part.

Hereinafter, the transformer according to the embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following, a case where the present invention is applied to an oil-immersed transformer will be described. However, the application target of the present invention is not limited to the oil-immersed transformer, and can be changed as appropriate. For example, it can be applied to a dry transformer (for example, a molded transformer, a class H dry transformer, etc.) and a gas-insulated transformer.

FIG. 1 is a partial front sectional view schematically showing a transformer according to an embodiment. The transformer 1 shown in FIG. 1 has an iron core 10 constituting a magnetic circuit, a winding (coil) 20 constituting an electric circuit, and a frame portion 30 supporting the iron core 10 and the winding 20 (shown by a two-dot chain line). It is configured with and. The iron core 10, the winding 20, and the frame portion 30 are housed in a tank (not shown). In FIG. 1, a transformer 1 having a three-phase three-leg structure in which a part of an iron core 10 inserted into three windings 20 arranged side by side in the left-right direction in the figure is fixed to a pair of upper and lower frame portions 30. Is shown. The structure of the transformer to which the present invention is applied is not limited to this, and can be applied to a transformer having an arbitrary structure such as a three-phase five-leg structure.

The iron core 10 has a plurality of (three in the present embodiment) leg portions 11 located apart from each other, and an upper yoke portion (yoke portion) joined (connected) to the upper and lower positions (both ends) of the leg portions 11. ) 12 and a lower yoke portion (yoke portion) 13. The iron core 10 is formed by laminating a plurality of electromagnetic steel plates (steel plates) in the direction orthogonal to the paper surface of FIG. The iron core 10 is provided with a gap 16 at an intermediate portion in the stacking direction via a plurality of spacers 15. The positions, sizes, and number of spacers 15 shown in FIG. 1 are schematically shown, and are appropriately changed according to the form of the iron core 10 and the like. In the iron core 10, a pair of openings 17 and 18 penetrating in the laminating direction of the electromagnetic steel plate are formed by a plurality of leg portions 11 and yoke portions 12 and 13. These openings 17 and 18 are sometimes called windows of the iron core 10. The iron core 10 is set to the ground potential via appropriate wiring or the like.

The windings 20 are wound around the three legs 11 and arranged, and the three windings 20 are U-phase, V-phase, and W-phase windings. In the winding 20, the outer winding 21 and the inner winding 22 are arranged concentrically. The outer winding 21 and the inner winding 22 are formed by coating a conductor such as copper or aluminum with an insulating material and then winding a plurality of loops in a coil shape. Here, the axial direction of the winding 20 is a direction in which the central axis of the winding 20 having a cylindrical shape extends, and is the vertical direction in FIG. The winding 20 is positioned with the frame portion 30 via a spacer member (not shown).

The transformer 1 of the present embodiment further includes two detection units 40. The detection unit 40 is arranged in the gap 16 of the iron core 10, is arranged so as to be sandwiched between a plurality of electromagnetic steel plates constituting the iron core 10, and is provided integrally with the leg portion 11. The detection unit 40 is arranged (formed) in a rectangular loop shape along the forming edges of the openings 17 and 18. Therefore, the detection unit 40 is arranged at a position surrounded by the winding 20 so as to face the inner circumference of the winding 20 forming a cylinder at a portion extending in the vertical direction, and is arranged across two adjacent windings 20. It will be installed. Here, the same configuration is adopted for the two detection units 40, and the configuration of one detection unit 40 will be described below with reference to FIG.

FIG. 2 is a schematic front view of the detection unit. As shown in FIG. 2, the detection unit 40 includes a core unit 41, an insulating plate 42, and a coil unit 43.

The core portion 41 is formed in a sheet shape having the thickness direction in the direction orthogonal to the paper surface of FIG. In FIG. 2, the core portion 41 is formed in a region represented by halftone dots, and is formed in a closed loop shape along a vertically long rectangular shape (square shape). The core portion 41 has a pair of vertical portions 41a extending in the vertical direction and a horizontal portion 41b extending in the horizontal direction by connecting the upper ends and the lower ends of the vertical portions 41a. The core portion 41 is also represented by halftone dots in FIG. 1, but the halftone dots are provided for convenience so as to be distinguished from other configurations and easy to see, and the appearance is not particularly limited.

The core portion 41 is formed in a square shape as a closed loop, but it is preferable to provide at least one gap (a gap electrically insulated by a resin coating, oil, etc.), and the vertical orientation is opposite. It can be exemplified that two U-shaped members are joined to form a U-shaped member. It is preferable that the core portion 41 is electrically insulated from the iron core 10 by keeping it at an arbitrary distance or the like. The material of the core portion 41 is made of a material different from that of the iron core 10, and is made of, for example, a ferrite core, and its characteristics and the like will be described later.

The insulating plate 42 is provided in a U-shaped region (at least a part of the region) below the middle in the vertical direction in the core portion 41. The insulating plate 42 is made of an appropriate resin material such as a printed circuit board. The insulating plate 42 is provided at a position where the core portion 41 is sandwiched from both sides in the thickness direction (direction orthogonal to the paper surface in the drawing). In FIG. 2, the core portion 41 of the portion that overlaps with the insulating plate 42 is shown so as to be visible in the same manner as the core portion 41 that does not overlap with the insulating plate 42, but is actually shielded by the insulating plate 42. Become.

A coil portion 43 is provided in a region of each vertical portion 41a of the core portion 41 that overlaps with the insulating plate 42. The coil portion 43 is formed by wiring copper or the like to an insulating plate 42 sandwiching the vertical portion 41a so that the coil portion 43 is wound around the vertical portion 41a of the core portion 41. One end (lower end in the middle of FIG. 2) of each coil portion 43 is electrically connected by the first wiring 45. A second wiring 46 is electrically connected to the other end (upper end in FIG. 2) of each coil portion 43, and a detection impedance 47 is connected to each second wiring 46. Further, each second wiring 46 is provided with a terminal (not shown) in the vicinity of the detection impedance 47, and is connected to an external device (not shown) via such a terminal. As a result, the current (electric signal) flowing through the coil unit 43 is output to the external device.

Returning to FIG. 1, in the detection unit 40, each vertical portion 41a of the core portion 41 and the coil portion 43 wound around the vertical portion 41a are arranged in a state of being inserted inside the winding 20. Further, by disposing a single detection unit 40 across two windings 20 adjacent to each other on the left and right sides in FIG. 1, one vertical portion 41a and the coil portion 43 of the detection unit 40 and the other vertical portion 40 are arranged. The portion 41a and the coil portion 43 are inserted into two different windings 20.

In the detection unit 40, if a partial discharge occurs from the winding 20 during the operation of the transformer 1, the magnetic flux in the high frequency band in the core unit 41 changes. At this time, an induced current is generated in the coil portion 43 so as to prevent such a change in magnetic flux, and the induced current is output to an external device (not shown) to detect partial discharge.

Here, in the present embodiment, there are three windings 20 and two detection units 40, but the two detection units 40 determine which of the three windings 20 is causing partial discharge. It can be detected from the detection result.

Specifically, when a partial discharge is generated from the central winding 20 in FIG. 1 among the three windings 20, the two detection units 40 penetrate through the central winding 20. The two detection units 40 can obtain substantially the same output. Further, when a partial discharge is generated from the windings 20 on the left side or the right side, only one of the two detection units 40 penetrates through those windings 20, so the inserted detection unit 40 The output is obtained only from the detection unit 40, and the corresponding output cannot be obtained from the detection unit 40 that does not penetrate. In this way, by comparing the outputs of the two detection units 40 and obtaining the difference, it is possible to identify the winding 20 in which the partial discharge occurs in the three windings 20.

Further, in the present embodiment, the position where the partial discharge occurs in the axial direction of the winding 20 can be detected. Specifically, when a partial discharge occurs, an induced current flows through the coil portion 43, and the output time of the induced current changes according to the position where the partial discharge occurs. For example, when a current is generated by partial discharge on the high-voltage end side of the coil portion 43, the current flows through the entire coil portion 43, so that the output time due to partial discharge becomes relatively long. On the other hand, when a partial discharge occurs on the low-voltage end side of the coil portion 43, a current flows through a small part of the coil portion 43, so that the output time due to the partial discharge becomes relatively short. By detecting the output time from the detection unit 40 in this way, the position where the partial discharge occurs in the axial direction of the winding 20 can be specified.

By the way, conventionally, a configuration using a current transformer is known to detect a partial discharge of a winding in a transformer. The current transformer is installed at a location away from high voltage locations to avoid electric leakage, discharge, etc., for example, a lead wire connected to the winding and away from the transformer tank. .. In this case, there is a problem that the detection sensitivity is lowered because the current that is excited and propagates is attenuated because the current is electrically far from the position where the partial discharge is generated to the current transformer.

In this regard, according to the above embodiment, since the detection unit 40 is provided on the iron core 10 and penetrates the winding 20, it can be detected at a position electrically close to the winding 20 which is the position where the partial discharge occurs. Therefore, attenuation can be suppressed and the detection sensitivity of partial discharge can be improved. Here, since the detection unit 40 is provided on the iron core 10 having the ground potential and the terminal of the detection unit 40 can be taken out from the low potential, the detection unit 40 is wound around the detection unit 40 while avoiding the discharge in the detection unit 40. It can be placed close to.

FIG. 3 is a graph showing the frequency characteristics of the iron core and the core portion. In the graph of FIG. 3, the horizontal axis represents frequency and the vertical axis represents magnetic permeability. In the iron core, the magnetic permeability becomes substantially constant and high at the operating frequency of the transformer (for example, commercial frequencies 50 Hz and 60 Hz), which is a relatively low frequency, although it varies depending on the operating conditions, and the frequency is higher than the higher cutoff frequency. Then, the magnetic permeability drops sharply. On the other hand, in the core part of the detector, the magnetic permeability that is substantially constant is smaller than that of the iron core, but the range in which the frequency is substantially constant is widened to high frequencies, and when the frequency is higher than the cutoff frequency, the permeability is increased. Permeability drops sharply. In other words, the core portion is made of a material different from the iron core and has the above-mentioned frequency characteristics. A core portion having a magnetic permeability lower than that of the iron core at the operating frequency and having a magnetic characteristic higher than that of the iron core in the frequency region where partial discharge is detected is preferably adopted.

In the above embodiment, since the detection unit 40 is provided so as to penetrate the winding 20, even if the partial discharge generation position becomes wide in the axial direction of the winding 20, the partial discharge generation position in the winding 20 And the detection unit 40 have a close positional relationship. As a result, regardless of the position where the partial discharge occurs in the winding 20, it is possible to suppress the attenuation due to the propagation of the current and make the detection sensitivity in the detection unit 40 uniform, and stabilize the partial discharge in the winding 20. It can be detected with high accuracy.

Further, in the iron core 10 formed by laminating steel plates, there is one in which a gap 16 is formed as a flow path for passing a refrigerant such as insulating oil. That is, the detection unit 40 can be installed by using the existing gap 16, and the detection unit 40 can be easily installed without changing each configuration of the transformer 1 including the iron core 10 or only a slight change. However, in the present invention, it does not prevent the iron core 10 from forming the gap 16 dedicated to the installation of the detection unit 40.

The present invention is not limited to the above embodiment, and can be modified in various ways. In the above embodiment, the size, shape, orientation, etc. shown in the accompanying drawings are not limited to this, and can be appropriately changed within the range in which the effects of the present invention are exhibited. In addition, it can be appropriately modified and implemented as long as it does not deviate from the scope of the object of the present invention.

In the above embodiment, the configuration in which the present invention is applied to a transformer has been described, but it can also be applied to other power stationary devices and power conversion devices as long as the above-mentioned effects can be obtained.

Further, the contents illustrated in the above embodiment are schematically shown for explanation, and if the above-mentioned effects can be exhibited, the shapes of the iron core 10, the winding 20, the frame portion 30, and the like may be changed. May be good.

Further, the coil unit 43 in the detection unit 40 can be changed in various ways as long as the core unit 41 is wound at least once. For example, the formation region of the coil portion 43 may be expanded or contracted or repositioned in the vertical direction with respect to the formation position shown in FIG. 1, or the coil portion 43 may be provided on the lateral portion 41b of the core portion 41.

Further, as long as at least a part of the detection unit 40 is integrally provided with the iron core 10, it may be provided at a position different from the inside of the gap 16, for example, on both sides of the iron core 10 in the stacking direction. Further, it is preferable that at least a part of the detection unit 40 is sandwiched between a plurality of steel plates constituting the iron core 10, in other words, the detection unit 40 is arranged without being partially sandwiched between the plurality of steel plates. May be.

Further, in the detection unit 40, the length and the formation position of each of the coil units 43 inserted into the two different windings 20 in the vertical direction may be the same as shown in FIG. 2, or may be different. May be good.

1 Transformer 10 Iron core 11 Leg part 16 Gap 20 Winding 40 Detection part 41 Core part 42 Insulation plate 43 Coil part

Claims (7)

It is provided with an iron core, a winding wound around the iron core, and a detection unit for detecting a discharge from the winding.
A transformer characterized in that at least a part of the detection unit is provided integrally with the iron core and is arranged at a position surrounded by the winding. The iron core is formed by laminating a plurality of steel plates.
The transformer according to claim 1, wherein at least a part of the detection unit is arranged so as to be sandwiched between the plurality of steel plates. The transformer according to claim 1 or 2, wherein the detection unit is arranged at a position facing the inner circumference of the winding on the iron core. It is provided with an iron core, a winding, and a detection unit for detecting a discharge from the winding.
The iron core includes a plurality of legs and yoke portions connected to both ends of the plurality of legs.
The winding is wound around each of the plurality of legs.
A transformer characterized in that at least a part of the detection unit is provided integrally with each of the plurality of leg portions and is arranged at a position surrounded by the winding. The transformer according to claim 4, wherein the detection unit is formed in a loop shape along an opening formed by the plurality of legs and the yoke portion. The detection unit includes a sheet-shaped core portion formed in a closed loop shape, an insulating plate provided at a position where at least a part of the core portion is sandwiched from both sides in the thickness direction, and the core wired to the insulating plate. The transformer according to any one of claims 1 to 5, further comprising a coil portion wound around the portion. The transformer according to claim 6, wherein the core portion is made of a material different from that of the iron core.

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