JP2003347134A - Three-phase reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase rector that can reduce loss induced at yoke cores and a tank, and at the same time, can be reduced in size as a whole by reducing the size of a tank-side shielded core. <P>SOLUTION: Outside-core magnetic flux generated in a coil 4 is separated to the yoke corers 1 and 2 wound with silicon steel and the tank 6. The most part of the outside-core magnetic flux flowing to the tank 6 flows in the tank- side shielded core 5 and returns to the coil 4. Since the outside-core magnetic fluxes flowing in the yoke cores 1 and 2 contain a number of components perpendicular to the surface of the silicon steel, eddy currents tend to flow to the surface layers of the silicon steel of the cores 1 and 2, but the eddy currents are divided into a number of groups by slits 7 and become small in current values. Therefore, the size of the tank-side shielded core 5 can be reduced, because loss caused by the eddy currents is significantly reduced in accordance with the number of the divisions and, at the same time, the outside-core magnetic fluxes generated by the eddy currents and flowing to the tank 6 side can be prevented from increasing. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor, and more particularly to a three-phase triangular radial core type reactor used as a large capacity reactor such as a shunt reactor.

[0002]

2. Description of the Related Art A shunt reactor is a reactor which is inserted into a transmission line end or a power receiving end in order to cancel a transmission line charging current of a long-distance transmission line, and has a three-phase triangular arrangement as a large-capacity reactor like this shunt reactor. Radial core type reactor is used. In this three-phase reactor, a ring yoke in which a magnetic steel plate such as a silicon steel plate is wound in a ring shape is arranged vertically, three leg cores are provided between the upper and lower ring yokes, and a coil is wound around the leg core. It is turned.

FIGS. 5 and 6 show a conventional three-phase reactor. FIG. 5 is a top view of the three-phase reactor, and FIG.
FIG. As shown in FIGS. 5 and 6, the coils 4 are wound around three leg cores 3 formed by alternately stacking a plurality of block cores 31 and gaps 32 formed by gap pieces. The leg iron core 3 is magnetically coupled by an upper yoke iron core 1 and a lower yoke iron core 2 wound with a silicon steel plate.

In such a three-phase reactor, the coil 4
The magnetic flux generated outside of the core is divided into the yoke cores 1 and 2 and the tank 6 as shown by the broken line in FIG. 6, and most of the magnetic flux flowing to the tank 6 flows into the tank-side shield core 5. Then, it is returned to the coil 4. The magnetic flux outside the iron core flowing into the yoke iron cores 1 and 2 is
Inside, the three phases merge and are canceled.

[0005]

The conventional three-phase reactor is constructed as described above, but when a magnetic flux outside the iron core flows into the yoke iron core, a component perpendicular to the surface of the silicon steel plate is added to the magnetic flux. , A large eddy current is generated in the silicon steel sheet, and a loss due to the eddy current occurs. In order to reduce the total loss including this loss, the current density and the magnetic flux density are usually reduced, and measures such as increasing the wire diameter of the coil and increasing the cross-sectional area of the iron core are used. However, since these use more materials, there is a problem that the equipment becomes large. Further, the magnetic flux outside the iron core flowing into the yoke iron core is repelled by the eddy current generated in the silicon steel sheet, and more magnetic flux outside the iron core flows to the tank side than when there is no eddy current. For this reason, the shield core on the tank side needs a large cross section in order to absorb these magnetic fluxes outside the core, and there is a problem that the three-phase reactor becomes large. Furthermore, a part of the magnetic flux outside the iron core flowing to the tank side also flows into the tank itself, and there is a problem that if the magnetic flux outside the iron core flowing to the tank side increases, a large loss also occurs in the tank.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a three-phase reactor capable of reducing losses in a yoke core and a tank, reducing the size of a tank-side shield core, and reducing the size of the entire apparatus. The purpose is to provide.

[0007]

The present invention comprises upper and lower ring yokes, three leg cores disposed between the upper and lower ring yokes, and coils respectively wound around the leg cores. In the three-phase reactor housed in the tank, a horizontal slit is provided in the ring yoke.

In the three-phase reactor according to the present invention, the eddy current generated in the ring yoke can be reduced by slitting the ring yoke in the horizontal direction.
Eddy current loss in the yoke core can be reduced, and local overheating can be prevented. Furthermore, by reducing the generation of eddy current, it is possible to prevent an increase in magnetic flux outside the iron core flowing to the tank side, so that the tank-side shield iron core can be made smaller and smaller, and eddy current loss in the tank can also be reduced. Thus, the reactor can be reduced in loss. In addition, since the slit is provided in the horizontal direction of the ring yoke, it is possible to prevent a manufacturing defect such as a crack in the steel plate when the ring yoke is formed.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an enlarged top view of a part of the three-phase reactor according to the embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG. 1 and 2,
1 is an upper yoke core, 2 is a lower yoke core, 3 is a leg core, 31 is a block core, 32 is a gap, 4 is a coil, 5 is a tank side shield core, 6 is a tank, 7 is a slit, and a slit 7 is Except where provided,
It has the same structure as the conventional three-phase reactor shown in FIGS.

The upper yoke core 1 and the lower yoke core 2 are large ring yokes in which a magnetic steel plate such as a silicon steel plate having a width corresponding to the height of the yoke is wound in a ring shape. The leg iron core 3 is a gapped iron core in which a plurality of block iron cores 31 and gaps 32 formed by gap pieces are alternately laminated, and a coil 4 is wound around each of the three leg iron cores 3. 5, the upper yoke core 1 and the lower yoke core 2 are respectively provided on the upper and lower surfaces of the respective leg cores 3.
And each iron core is magnetically coupled. The tank-side shield core 5 has a height slightly longer than the height of the coil 4 and is provided with a slight gap from the tank 6. These iron cores are supported by a structure (not shown) and housed in a tank 6, into which insulating cooling liquid or gas such as insulating oil is supplied from the lower part of the tank 6 and discharged from the upper part of the tank 6. Have been.

On the other hand, on the outer periphery of the upper and lower yoke cores 1 and 2, a horizontal slit 7 is provided at a position corresponding to the coil 4.
Is inserted. The slit 7 can be formed by winding a silicon steel sheet having slits 7 in necessary portions as shown in FIG. 3, or by winding a silicon steel sheet divided in the width direction as shown in FIG. A slit can also be formed by attaching. In the case of FIG.
Slits are provided on the entire circumference of the yoke iron cores 1 and 2, and spacers 8 are inserted at appropriate positions between a plurality of divided silicon steel plates.

Next, the operation of the three-phase reactor of the present invention will be described. The magnetic flux outside the iron core generated by the coil 4 is shown in FIG.
As shown by broken lines, the yoke cores 1 and 2 are divided into the tank 6 side, and most of the magnetic flux outside the iron core flowing into the tank 6 flows into the tank-side shield core 5 and returns to the coil 4 to return to the coil 4. The magnetic flux outside the iron core that has flowed into the iron cores 1 and 2 is canceled by the three phases joining in the yoke iron cores 1 and 2.

Since the magnetic flux outside the iron core flowing into the yoke iron cores 1 and 2 contains a large amount of components in the direction perpendicular to the surface of the silicon steel sheet, the yoke iron cores 1 and 2 similarly to the conventional three-phase reactor. Although the eddy current tends to flow through the surface of the silicon steel sheet, the eddy current is divided by the slit 7 and divided into a number of groups, so that the current value of the eddy current decreases. Since the loss W generated by the eddy current is proportional to the square of the current, W = Wo / (n + 1) ² , and the loss due to the eddy current is greatly reduced in accordance with the number of divisions. In the above equation, Wo is the eddy current loss when there is no slit, and n is the number of divisions.

On the other hand, when an eddy current is generated, the magnetic flux outside the iron core flowing into the yoke iron cores 1 and 2 is repelled, and more magnetic flux outside the iron core flows to the tank 6 side than in the case where there is no eddy current. When the slits 7 are formed in the yoke cores 1 and 2 as described above, the eddy current is greatly reduced, so that the magnetic flux outside the iron core flowing to the tank 6 does not increase, and the sectional area of the shield core 5 on the tank side is reduced. And miniaturization becomes possible. Further, a part of the magnetic flux outside the iron core flowing to the tank 6 also flows into the tank 6 itself, and a loss occurs in the tank 6 because the material of the tank 6 is usually mild steel.
As described above, the eddy current is reduced by the slit 7 and the magnetic flux flowing to the tank 6 does not increase.
The loss that occurs from itself can also be reduced.

The depth of the slit 7 is determined by the magnetic flux density distribution in the silicon steel sheet on the laminated surface among the silicon steel sheets, and depends on the amount of magnetic flux generated from the coil 4. However, the thickness of the yoke cores 1 and 2 is usually about 500 mm. In this case, the depth of the slit 7 may be about 5 to 10 mm. If the width t of the slit 7 is about the length corresponding to the average diameter of the coil 4, a sufficient effect can be obtained.

On the other hand, the eddy current is reduced even if the slits provided in the yoke iron cores 1 and 2 are provided in the direction perpendicular to the longitudinal direction of the silicon steel sheet, but the slit is formed in the direction perpendicular to the longitudinal direction of the silicon steel sheet. When the silicon steel plate is provided, a bending stress is applied to the slit portion when forming the silicon steel plate on the ring yoke, which becomes a structural weak point. Therefore, it is difficult to provide the slit in a direction perpendicular to the longitudinal direction of the silicon steel plate. . That is,
If the slit is only in the middle of the width direction of the silicon steel plate, the part without the slit can be formed in a ring shape, but the part with the slit does not follow the ring shape, stress is concentrated at the end part of the slit and a crack occurs . On the other hand, when the slit 7 is provided in the longitudinal direction of the silicon steel plate as in the above-described embodiment, the bending stress at the slit portion is very small when forming the ring yoke, and the crack or the like is not generated. Not
There are no structural weaknesses.

In the above-described embodiment, the slits are provided in the upper and lower ring yokes. However, since the cooled insulating oil flows from the bottom to the top and the upper ring yoke becomes hot, only the local overheating occurs. Considering this, the slit may be provided only in the upper ring yoke, but it is more preferable to provide the slit also in the lower ring yoke. Although the magnetic flux outside the core is also generated inside the ring yoke of the coil, the magnetic flux outside the core is combined by three phases and is canceled out. Therefore, it is not particularly necessary to provide a slit on the inner circumference of the ring yoke. Further, in the above embodiment, the insulating oil is flown in the tank. However, it is also possible to cool the iron core by enclosing an insulating liquid or gas such as insulating oil in the tank and circulating this by natural convection. . Further, in the above embodiment,
Although two slits are provided, even a single slit has a certain effect, and if three or more slits are provided, a large effect can be exhibited. However, a sufficient effect can usually be obtained with two or three slits.

[0018]

As described in detail above, the three-phase reactor according to the present invention is constructed as described above, and the eddy current generated when the magnetic flux outside the iron core flows into the ring yoke is reduced by the slit formed in the ring yoke. The eddy current generated in the ring yoke can be reduced. Therefore, eddy current loss can be reduced and local overheating can be eliminated by simply adding a slit without using a material for reducing eddy current. Also,
By reducing the occurrence of eddy currents in the yoke core, it is possible to prevent an increase in magnetic flux outside the core flowing to the tank side, so that the tank-side shield core can be made smaller and the tank-side shield core can be downsized. Also, the eddy current loss in the tank is reduced, and the loss of the reactor can be reduced. Further, since the slit is provided in the horizontal direction of the ring yoke, the steel sheet does not crack due to the slit provided in the magnetic steel sheet when the ring yoke is formed, and there is no problem during production.

[Brief description of the drawings]

FIG. 1 is a top view of a partially enlarged portion of a three-phase reactor according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the three-phase reactor of FIG.

FIG. 3 is a diagram illustrating an example of a slit provided in a ring yoke.

FIG. 4 is a view showing another example of a slit provided in a ring yoke.

FIG. 5 is a top view of a conventional three-phase reactor.

FIG. 6 is a partial cross-sectional view of the conventional three-phase reactor shown in FIG.

[Explanation of symbols]

1 Upper yoke core 2 Lower yoke core 3 leg iron core 31 block iron core 32 gap 4 coils 5 Tank side shield core 6 tanks 7 slit 8 Spacer

Claims (1)

[Claims] An upper and lower ring yoke, three leg cores disposed between the upper and lower ring yokes, and coils wound around the leg cores, respectively, are housed in a tank. A three-phase reactor, wherein a horizontal slit is provided in the ring yoke.