JP2003229315A - Three-phase variable inductance device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a three-phase variable inductance device, which can be made smaller because no mechanical operation is required, has an excellent response property and high strength against an overcurrent and overvoltage, and is suitable for a reactive power control device. <P>SOLUTION: Inner leg iron cores 11a, 11b and 11c in the center of a single- phase shell-type iron core, to which main wires are wound, form a structure of a three-piece integrally connected core so that they are arranged in series. Main ac wires 4R, 4S and 4T in each phase are wound to the three inner leg iron cores 11a, 11b and 11c in the center. Control wires 14xa, 14ya, 14xb, 14yb, 14xc and 14yc are wound to side leg iron cores 12xa, 12ya, 12xb, 12yb, 12xc and 12yc, which constitute an outer frame-like iron core 13, and a dc current is allowed to flow therein to generate dc control magnetic flux which circulates in one direction in the frame-like iron core 13. Consequently, ac magnetic fluxes (ϕ<SB>r</SB>, ϕ<SB>s</SB>and ϕ<SB>t</SB>) are hardly allowed to flow, and thus the inductance of the main ac wires 4R, 4S and 4T is adjusted. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a functional improvement of a device that adds a variable inductance function to a three-phase power device such as a three-phase transformer or a three-phase reactor to form a three-phase variable inductance device.

[0002]

2. Description of the Related Art Generally, a transformer or a reactor having a variable inductance function is provided with a gap inside an iron core,
The inductance was changed by mechanically changing the size of the gap. For example, a reactor having a variable inductance function has a lower iron core 1 as shown in FIG.
The upper iron core 2 is arranged on top of the upper iron core 2 and the leg main iron cores 3a, 3b, 3c are wound around the AC main windings 4R, 4S, 4T of the respective phases, and the upper iron core 2 is mechanically moved up and down to form the lower iron core 1. The structure is such that the sizes of the gaps 5a, 5b, 5c between the upper iron cores 2 are changed.

However, in the conventional movable iron core structure, since the upper magnetic core 2 is moved, the structure is complicated and the weight is heavy. Moreover, since there is a movable portion, it is easy to break down and there is a problem that noise due to electromagnetic vibration is large. Further, since the mechanical operation is performed, there is a problem that the response speed is slow and the inductance cannot be instantaneously adjusted.

Further, the voltage of the power system is provided with a reactive power control device which balances generation and absorption of reactive power in order to keep the voltage constant. As shown in FIG. 7, this reactive power control device is provided with a shunt reactor 7 in parallel with a power factor improving capacitor 6, a semiconductor device 8 such as a thyristor is connected in series with the shunt reactor 7, and The current of the shunt reactor 7 is controlled by switching.

In a general electric power system, delayed reactive power increases with an increase in load. Therefore, in this reactive power control device, the power factor is improved by the power factor improving capacitor 6 during heavy load. On the other hand, when the load is light, the delayed reactive power due to the load decreases, so that the shunt reactor 7 suppresses the voltage increase at the power receiving end and stabilizes the voltage of the power system.

However, the semiconductor device 8 such as a thyristor requires a control device for performing high-speed switching, and has a drawback of low strength against overcurrent and overvoltage. Therefore, it is possible to omit the semiconductor device 8 by adjusting the inductance by using the reactor having the movable iron core structure of FIG. 6 as the shunt reactor 7 shown in FIG. However, when a reactor having a movable iron core structure is used, it has not been used as a reactive power control device because of the problems described above.

[0007]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, can reduce the size of the device without requiring mechanical operation, and has excellent responsiveness, high strength against overcurrent and overvoltage, and a reactive power control device. A three-phase variable inductance device suitable as

[0008]

In the three-phase variable inductance device according to claim 1 of the present invention, the central inner leg iron core around which the main winding of the single-phase outer iron core is wound is arranged in series. An iron core structure in which three cores are integrally connected is formed, and AC main windings for each phase are wound around three central inner leg cores, and a control winding is provided for an outer frame-shaped core composed of side leg cores for each phase. And a control winding is connected so that the voltages induced by the AC main magnetic flux cancel each other out, and a DC control magnetic flux that circulates in one direction is generated in the outer frame-shaped iron core. To do.

In the three-phase variable inductance device according to claim 2 of the present description, the AC main winding of each phase is wound on the inner three inner leg cores of the three-phase five-leg iron core, and the outer frame is formed. A control winding is wound around the iron core, and a DC current is passed through the control winding to generate a DC control magnetic flux that circulates in one direction in the outer frame iron core.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below.
This will be described in detail with reference to FIG. FIG. 1 shows a three-phase variable inductance device 9, which comprises an iron core 10 which constitutes the device.
Consists of a single-phase outer iron core in which side leg cores 12xa and 12ya are arranged on the left and right of the center inner leg core 11a for the first phase, and the second and third phases are also 11b and 12 respectively.
xb, 12yb and 11c, 12xc, 12yc, and the inner leg iron cores 11a, 11b, 11 in the center as a whole
It has a lattice-like structure in which three c are connected in series so as to be in series.

The main cores 11a, 11b, 11c arranged in series of the iron core 10 are respectively wound with AC main windings 4R, 4S, 4T of respective phases to form the frame-shaped iron core 13. Leg iron core 12xa, 12ya, 12xb, 12y
b, 12xc, 12yc control windings 14xa, 14y
a, 14xb, 14yb, 14xc, 14yc are respectively wound, and the control windings 14xa, 14ya, 14x are wound.
A direct current is applied to b, 14yb, 14xc, and 14yc.

The AC main windings 4R, 4S, 4T have the same polarity so that magnetic fluxes in the same direction are generated with respect to the common magnetic path composed of the inner leg iron cores 11a, 11b, 11c at the center. Also, the control windings 14xa, 14ya, 14xb, 14yb, 14x
Since an alternating voltage is induced in the c and 14yc by the alternating magnetic flux, the control windings 14xa and 14y will be described by taking the first phase as an example.
The induced voltage generated by the AC magnetic flux at a is connected in series in such a direction as to cancel each other, and the second phase 14xb,
14yb and 14xc and 14yc of the third phase are similarly connected. At this time, the control windings 14xa, 14ya, 1
4xb, 14yb, 14xc, 14yc are frame-shaped iron cores 13
Will generate a DC control magnetic flux that circulates in one direction.

In the three-phase variable inductance device having the above structure, the AC main windings 4R, 4R
AC magnetic flux of each phase (φr, φ
s, φt) is the side leg core 12xa, 12ya, 12 of each phase
xb, 12yb, 12xc, 12yc, and the iron core of each phase portion circulates independently, so that each phase operates as an independent inductance device.

In this state, the control windings 14xa, 14ya,
When a direct current is applied to 14xb, 14yb, 14xc, and 14yc, the DC control magnetic flux φdc flows so as to circulate in the frame-shaped iron core 13 in one direction. As a result, the magnetic permeability of the frame-shaped magnetic core 13 decreases as the magnetic flux density increases.
r, φs, φt) becomes difficult to flow into the frame-shaped iron core 13, and acts so as to cancel each other out on the inner leg iron cores 11a, 11b, 11c in the center, and the inductance of the AC main windings 4R, 4S, 4T Decrease.

Three-phase variable inductance device 9 having the above structure
As a result of examining the characteristics of the above, it was confirmed that as the control current was increased, the inductance gradually decreased as shown in FIG. When this three-phase variable inductance device 9 was incorporated into a reactive power control device as shown in FIG. 3 and changes in the delayed reactive current due to the control current were measured, it was found that the delayed reactive current increased as the control current increased as shown in FIG. It has been confirmed that is increased almost linearly and can be continuously changed.

The control windings 14xa, 14ya, 14
Regarding the connection of xb, 14yb, 14xc, 14yc, in addition to the method of connecting all the control windings in series and then connecting to the control DC current circuit, "14xa, 14y"
a "," 14xb, 14yb "," 14xc, 14y "
"c", such as combining for each phase and connecting in parallel to the control DC current circuit, or "14xa, 14xb, 14x"
c ”,“ 14ya, 14yb, 14yc ”, and there is a method of connecting them in parallel to a direct current circuit for control. That is, the configuration of the control winding does not matter as long as the voltage induced in the control winding by the AC magnetic flux is canceled and a DC control magnetic flux circulating in one direction can be generated in the frame-shaped iron core 13.

FIG. 5 shows another embodiment of the present invention. The iron core 10 of the three-phase variable inductance device 9 has side leg iron cores 12x, 12y on both sides of three inner leg iron cores 11a, 11b, 11c arranged in parallel. It has a three-phase five-legged iron core structure. These three inner leg iron cores 11a, 11b, 1
1 c of AC main windings 4R, 4S, and 4T of each phase are wound, respectively, and side leg iron cores 12x and 1 that form a frame-shaped iron core 13 are formed.
The control windings 14x and 14y are respectively wound around 2y, and a direct current is supplied to the control windings 14x and 14y.

The AC main windings 4R, 4S, 4T have polarities so that magnetic fluxes in the same three-phase direction are generated in the three-phase common magnetic paths of the inner three inner leg iron cores 11a, 11b, 11c. Align. The control windings 14x and 14y are configured to generate a magnetic flux that circulates in one direction in the frame-shaped iron core 13.

Also in this type of three-phase variable inductance device 9, when a DC current is passed through the control windings 14x and 14y, the DC control magnetic flux φdc flows so as to circulate in the frame-shaped iron core 13 in one direction. , The magnetic permeability decreases as the magnetic flux density increases, and the AC magnetic flux (φr, φrs, φst, φ
t) becomes difficult to flow into the frame-shaped iron core 13, and the AC main winding 4
The inductances of R, 4S and 4T are reduced.

In the above description, the case of application to a reactor is shown, but in the case of application to a transformer, three or more AC main windings 4 for each phase are wound around three leg iron cores 11a, 11b, 11c. Turn.

[0021]

As described above, according to the three-phase variable inductance device of the present invention, the inductance can be adjusted by providing a control winding on the outer frame-shaped iron core and supplying a direct current to the control winding. Therefore, there are no mechanically movable parts, the response is fast, and it is possible to change continuously, the device can be downsized, the noise is small, and the reliability can be greatly improved.

[Brief description of drawings]

FIG. 1 is a front view of a three-phase variable inductance device according to an embodiment of the present invention.

FIG. 2 is a graph showing a relationship between a control current and an inductance of the three-phase variable inductance device shown in FIG.

FIG. 3 is an explanatory diagram showing a reactive power control device incorporating the three-phase variable inductance device of FIG.

FIG. 4 is a graph showing a relationship between a control current and a delayed reactive current in a reactive power control device incorporating a three-phase variable inductance device.

FIG. 5 is a front view of a three-phase variable inductance device having a three-phase five-leg iron structure according to another embodiment of the present invention.

FIG. 6 is a front view showing a conventional movable inductance device.

FIG. 7 is an explanatory diagram showing a reactive power control device incorporating a conventional semiconductor device.

[Explanation of symbols]

1 Lower iron core 2 Upper iron cores 3a, 3b, 3c Leg iron cores 4R, 4S, 4T AC main windings 5a, 5b, 5c Gap 6 Power factor improving capacitor 7 Shunt reactor 8 Semiconductor device 9 Three-phase variable inductance device 10 Iron core 11a , 11b, 11c Inner leg iron cores 12x, 12y, 12xa, 12ya, 12xb, 12
yb, 12xc, 12yc Side leg iron core 13 Frame-shaped iron cores 14x, 14y, 14xa, 14ya, 14xb, 14
yb, 14xc, 14yc control winding

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kei Ohinata             72-1 Nakayama, Aoba-ku, Sendai City, Miyagi Prefecture             Tohoku Electric Power Co., Inc. Research and Development Center (72) Inventor Shigeaki Akatsuka             72-1 Nakayama, Aoba-ku, Sendai City, Miyagi Prefecture             Tohoku Electric Power Co., Inc. Research and Development Center (72) Inventor Tomoyuki Aoki             72-1 Nakayama, Aoba-ku, Sendai City, Miyagi Prefecture             Tohoku Electric Power Co., Inc. Research and Development Center (72) Inventor Mineo Kawakami             72-1 Nakayama, Aoba-ku, Sendai City, Miyagi Prefecture             Tohoku Electric Power Co., Inc. Research and Development Center (72) Inventor Akira Sasaki             9 Shiba, Tennohara, Matsukawa-cho, Fukushima City, Fukushima Prefecture             Electric Co., Ltd.

Claims (2)

[Claims] 1. An iron core structure of a single-phase outer iron type magnetic core in which three central inner leg cores around which a main winding is wound are connected in series so as to be in series, and three central inner leg cores are formed. The AC main winding of each phase is wound around the control winding, and the control winding is wound around the outer frame-shaped core consisting of the side leg cores of each phase so that the voltages induced by the AC main magnetic flux cancel each other out. A control winding is connected, and a DC control current is passed through the control winding to generate a DC control magnetic flux that circulates in one direction in the outer frame-shaped iron core, and the magnetic resistance of the common magnetic path of the main magnetic flux and the DC control magnetic flux is changed. A three-phase variable inductance device characterized by controlling and varying the inductance of the main winding. 2. In a three-phase five-leg iron core, an AC main winding of each phase is wound on three inner inner iron cores, and a control winding is wound on an outer frame-shaped iron core. A control current is applied to generate a DC control magnetic flux that circulates in one direction in the outer frame-shaped iron core, and the magnetic resistance of the common magnetic path of the main magnetic flux and the DC control magnetic flux is controlled to change the inductance of the main winding. A three-phase variable inductance device characterized in that