JP2871025B2 - Industrial transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a transformer for a rectifier, a transformer for an electric furnace, etc., in which the voltage on the secondary low voltage side is a low voltage of the 100V level and the capacity is 10MV.
It relates to an A-level large-capacity industrial transformer.

[Conventional technology]

FIG. 3 is a winding arrangement diagram showing a winding arrangement of a conventional industrial transformer. In this figure, the iron core 1 is shown only at the surface position on the outer diameter side, but has a rod shape which is symmetrical in the axial direction which is the upper direction of the figure. The transformer is a three-phase three-legged iron core with three iron legs magnetically connected at both ends with yoke. The winding group shown in this figure is coaxially arranged on each of the three iron legs. Is done. In addition, in the transformer of the high voltage winding of 66 kV, 77 kV or 154 kV which is the voltage of the power system that obtains the power of the above-mentioned capacity and this capacity, the oil-immersed transformer using the insulating oil as a medium that combines cooling and insulation Generally, it is a container.

The low-voltage winding 3 has a number of disk coils 31 stacked in the axial direction with a predetermined gap therebetween, and two of these disk coils 31 constitute one set to form a coil group 34, These coil groups 34 are connected in series on the inner diameter side, respectively, and the lead 32 is pulled out from the outer diameter side to pull out the lead 33.
Connected to. The other coil groups 34 are connected in the same manner, and eventually several tens of groups of two disk coils 31 are connected in parallel to form one low-voltage winding 3. Such a winding configuration of the low-voltage winding 3 is called a multi-parallel disk winding, and is often used in industrial transformers as a special winding configuration suitable for low voltage and large current.

The low-voltage winding is normally provided on the outermost diameter side as shown in the drawing because of the arrangement of the lead 33, and the power transformer is configured such that the high-voltage winding is the outermost diameter side, the medium-voltage winding, and the low-voltage winding. In contrast to the general winding arrangement provided on the inner diameter side, the arrangement of such a low-voltage winding on the outermost diameter side is also a feature of the winding arrangement of industrial transformers. Has become.

In this figure, the high-voltage winding 2 is provided on the innermost diameter side closest to the iron core 1, and the tap winding 23 is provided between the high-voltage winding 2 and the low-voltage winding 3. The tap winding 23 is composed of a multi-parallel cylindrical winding in which a number of wires determined by the number of taps are arranged in the axial direction and wound simultaneously, and in this figure, only two wires are shown, but in actuality, About 10 wires are wound simultaneously. In this multi-parallel cylindrical winding, even if an electric wire through which no current flows due to tap switching by a load tap changer (not shown), the nonuniformity of the axial distribution of ampere turns due to this is small. There is a feature that the axial electromagnetic mechanical force generated between the windings is reduced by a short-circuit current flowing through the windings due to an external short circuit.

The high-voltage winding 2 may be originally a disk winding or a cylindrical winding,
Cylindrical windings may be adopted for technical reasons that cylindrical windings are better for pre-tightening together with tap windings 23. Is illustrated assuming that such a high-voltage winding 2 is a cylindrical winding. When a disk winding is adopted as the high-voltage winding 2, a winding arrangement provided between the high-voltage winding 2 and the iron core is often adopted as the tap winding 23.

These three windings are arranged coaxially as shown in the figure, and are also arranged so that the winding heights, which are the respective axial dimensions, are matched and the surfaces at both ends are also matched. This configuration is a basic winding arrangement of a transformer employing not only an industrial transformer but also an inner iron core. Adopting such a winding arrangement is to reduce the strong axial electromagnetic mechanical force generated when a short circuit current of 10 times or more of the rated current flows through each winding as much as possible, This is because the configuration is designed to sufficiently withstand the electromagnetic mechanical force. If the winding height of each winding is different, an electromagnetic mechanical force acts on the winding in the axial direction in proportion to the difference. Further, even if the winding heights match, if the position is displaced in the axial direction, an axial electromagnetic mechanical force proportional to the displacement dimension acts. Therefore, in order to reduce the axial electromagnetic mechanical force, as described above, a winding arrangement in which the winding height matches the winding height is employed. Actually, there is an unavoidable generation of a certain amount of electromagnetic electromagnetic force in the axial direction due to manufacturing errors.Therefore, in consideration of this, the structure to support each winding and the tightening force in the axial direction must be applied to the winding in advance. Measures such as tightening before giving are taken.

[Problems to be solved by the invention]

FIG. 3 shows that the cylindrical winding is adopted as the high voltage winding 2 as described above, because the tap winding 23 is pre-tightened together with the high voltage winding 2. . In a disc winding, an insulator is inserted between adjacent disc coils 31 to ensure a necessary gap, whereas in a cylindrical winding, an electric wire is wound in contact with an axial direction. Therefore, there is a difference that the ratio of the insulator occupied by the disk winding in the axial direction is much larger. Most of the contraction in the pre-tightening of the winding in the axial direction is caused by the insulator, and since the electric wire conductor is made of metal, there may be almost no dimensional change compared to the insulator. Therefore, when the disk winding and the cylindrical winding are simultaneously pre-tightened in parallel, a pre-tightening force is applied to the cylindrical winding in a biased manner, and a problem arises in that the necessary pre-tightening force is not applied to the disk winding. During the pre-tightening, the winding is dried, and the insulator shrinks due to the drying, so that the bias of the pre-tightening force is further increased. Therefore, in order to pre-tighten the tap winding 23 composed of the multi-parallel cylindrical winding together with the high-voltage winding 2 as described above, the high-voltage winding 2
It is necessary to adopt a cylindrical winding.

When the disk winding is adopted as the high voltage winding 2 because the disk winding has the advantage that the size of the disk winding is smaller than the cylindrical winding at about the voltage of the high voltage winding 2 In this case, however, in this case, it is necessary to adopt a configuration in which the tap winding 23 is independently pre-tightened for the above-described reason. Since the capacity of the tap winding 23 is small and the winding width, which is the radial dimension of the winding, is also small, a special configuration is required to securely tighten the winding, which complicates the structure. There is a problem that it may cause price rise.

An object of the present invention is to arrange a tap winding in a space at an axial end of a high-voltage winding or a low-voltage winding by utilizing the special property that a low-voltage winding is formed of a multi-parallel disk winding. ,
An object of the present invention is to provide an industrial transformer in which a disk winding can be adopted as a high-voltage winding and a winding arrangement in which an axial electromagnetic force does not become excessive is adopted.

[Means for solving the problem]

According to the present invention, in order to solve the above problems, a cylindrical low-voltage winding inserted into an iron core is a multi-parallel disk winding in which a plurality of coil groups are connected in parallel, and a high-voltage winding and a tap winding are used. In an industrial transformer in which other windings including the same windings are arranged coaxially with the low-voltage winding, the tap winding and the high-voltage winding are formed by disc windings, and the tap winding is formed by the high-voltage winding. It shall be located at the axial end of the wire or low voltage winding.

[Action]

In the configuration of the present invention, since the low-voltage winding is constituted by a multi-parallel disk winding composed of a plurality of coil groups connected in parallel, the ampere caused by the arrangement of the other windings being not symmetrical in the axial direction. There is a characteristic that the asymmetry of the distribution of turns is corrected by uneven distribution of the current flowing through each coil group of the low-voltage winding. Therefore, if a disc winding is adopted as the tap winding and it is arranged in one space at both ends in the axial direction of the high-voltage winding, the ampere turn becomes asymmetric in the axial direction due to the current flowing through this tap winding. As described above, since the current distribution in the low-voltage winding corrects this asymmetrical ampere-turn distribution, the axial electromagnetic mechanical force generated by the short-circuit current due to the external short-circuit is suppressed. The same effect occurs if a tap winding is provided at one of the axial ends of the low voltage winding. As a result, there is no reason to adopt a cylindrical winding for the high-voltage winding, so that a disk winding having a smaller winding size than the cylindrical winding can be adopted without any trouble.

〔Example〕

Hereinafter, the present invention will be described based on examples. FIG. 1 is a winding arrangement diagram showing an embodiment of the present invention. The same reference numerals are given to the same components as those in FIG. 3, and the detailed description will be omitted. In this figure, the tap winding
Reference numeral 21 denotes a disk winding composed of four disk coils, and is arranged in the space at the upper end of the high-voltage winding 2A formed by the disk winding. The position of the upper end of the high-voltage winding 2A is located slightly below the position of the upper end of the low-voltage winding 3, and the upper end of the tap winding 21 is disposed slightly above the upper end of the low-voltage winding 3. The center height position of the tap winding 21 matches the upper end of the low-voltage winding 3. The positions of the lower ends of the high-voltage winding 2A and the low-voltage winding 3 are matched.

In the tap winding 21, the current flowing turn changes depending on the tap position selected by a not-shown load tap changer,
This figure shows the arrangement of the tap winding 21 when the ampere turn changes according to the tap position between the case where the current flows through all the turns of the tap winding 21 and the case where no current flows through all the turns. When the ampere-turn of the tap winding 21 is the maximum, the magnetic equivalent axial direction corresponding to the axial distribution of the ampere-turn of the inner winding including the high-voltage winding 2A and the tap winding 21 The dimension is longer than that of the low-voltage winding 3. On the contrary, when the ampere-turn of the tap winding 21 is 0, the axial dimension of the winding on the inner diameter side is the dimension of the high-voltage winding 2A itself. It is shorter than 3. As described above, when the ampere-turn distribution of the winding facing the low-voltage winding 3 does not match the coil size of the low-voltage winding 3 and is asymmetric, the respective coil groups 34 constituting the low-voltage winding 3
The distribution of the current flowing through is uneven. The tendency is that when the high voltage winding 2A side is long, the coil group 34 above the low voltage winding 3
In the case of short current, the current sharing of the upper coil group 34 decreases, and in the case of short current, the asymmetric portion of the ampere turn on the high voltage winding 2A makes the current sharing of the low voltage winding 3 non-uniform. Will cancel each other out. In order to obtain the stricter current sharing of the low-voltage winding 3, the impedance matrix of each winding in FIG. 1 is obtained, and the current value of each coil group 34 is solved by solving a multi-element complex simultaneous equation. Can be Qualitatively, it is a universal phenomenon that can be explained from the property that, in an AC electromagnetic field, currents in opposite directions distribute toward each other and currents in the same direction distribute away from each other.

As described above, if the ampere turns on the high-voltage winding 2A including the high-voltage winding 2A and the tap winding 21 have a distribution that is asymmetric with respect to the winding arrangement of the low-voltage winding 3, this asymmetry is canceled. As described above, the current sharing of the coil group 34 connected in parallel constituting the low-voltage winding 3 is determined, and as a result, the generation of the axial electromagnetic mechanical force at the time of external short circuit is suppressed. Therefore, even if the arrangement of the tap windings 21 having an asymmetrical ampere turn as shown in FIG. 1 is employed, the axial electromagnetic mechanical force does not increase as much as the conventional common sense.

In the pre-tightening, a front tightening force is applied to the high-voltage winding 2A and the tap winding 21 at the same time. Since the same force is applied to the high-voltage winding 2A and the tap winding 21 as the pre-tightening force, there is no problem in performing common pre-tightening regardless of the winding type.

FIG. 2 is a winding arrangement diagram showing another embodiment of the present invention. The difference between FIG. 1 and FIG.
Are arranged on the low-voltage winding 3. In the case where the tap winding 22 is a part of the high-voltage winding 2B and the high-voltage winding 2B and the tap winding 22 are electrically connected, the configuration of FIG. 1 is appropriate from the viewpoint of insulation. is there. Among the industrial transformers, a series transformer is inserted in series with the low-voltage side circuit in order to adjust the low-voltage side in a wide range, and the primary voltage of the series transformer is controlled by the main transformer. And the tertiary winding is used as a tap winding, and the induced voltage of the series transformer is changed by changing the tap of this tap winding, thereby changing the low voltage side voltage in a wide range. It is to try. When such a configuration is employed, the tap winding 22 is a separate circuit from the high-voltage winding 2B, and its voltage is generally lower than that of the high-voltage winding 2B. It is appropriate to dispose it in the space at the upper end of the low-voltage winding 3. In this configuration, the high-voltage winding
The feature that the upper terminal of the 2B can be easily pulled out as compared with FIG. 1 and that the tap lead of the tap winding 22 can be easily drawn because the tap winding 22 is on the outer diameter side. There is.

In this figure, when the current of the tap winding 22 is in the same direction as that of the low-voltage winding 3, the tap winding 22 of the low-voltage winding 3 is evident from the aforementioned qualitative current distribution property of the AC electromagnetic field. The current sharing of the coil group 34 on the side closer to the above decreases and increases in the opposite direction, which is qualitatively the same as that in FIG. Since the positions of the tap windings 22 are different, the axial electromechanical force associated therewith is slightly different, but does not cause any substantial difference. The pre-tightening is performed by the low-voltage winding 3 and the tap winding 22 together.

The tap windings 21 and 22 in the above two embodiments are each composed of four disk coils, and the number of the coil groups is also shown as 2. However, the number of taps of an actual industrial transformer is shown. As described above, there are various types of connection between the tap windings 21 and 22, and the configuration and arrangement of the tap windings 21 and 22 in implementing the present invention are different from those of the present invention. The conditions should be determined after comprehensively judging each condition within a range that conforms to.

〔The invention's effect〕

According to the present invention, as described above, since the low-voltage winding is constituted by a multi-parallel disk winding, the asymmetry of the ampere-turn distribution caused by the arrangement of the other windings being not symmetrical in the axial direction is as follows. This is corrected by the non-uniform current flowing through each coil group connected in parallel with the low-voltage winding. Therefore, if a disk winding is adopted as the tap winding and it is arranged in one space at both ends in the axial direction of the high-voltage winding, the ampere turns have an asymmetric distribution in the axial direction due to the current flowing through this tap winding. As described above, since the current distribution in the low-voltage winding corrects this asymmetrical ampere-turn distribution, the axial electromagnetic mechanical force generated by the short-circuit current due to the external short-circuit is suppressed. The same effect occurs if a tap winding is provided at one of the axial ends of the low voltage winding. As a result, there is no reason to use a cylindrical winding for the high-voltage winding, so that a disk winding having a smaller winding size than the cylindrical winding can be used without any trouble.

The space at the axial end of the high-voltage winding and low-voltage winding where the tap winding is arranged can use an unnecessary dimension for insulation. The effect is obtained that the radial dimension of the arranged winding is reduced by the radial dimension occupied by the tap winding. Furthermore, in the prior art, even in the case where a cylindrical winding is used for the high-voltage winding, a disk winding having a good space factor is adopted, and no problem occurs. The effect is added. In this way, by reducing the radial dimension, the weight of the electric wire used for the winding is reduced, whereby the effect of reducing the cost of the industrial transformer is obtained, and the load loss generated in the winding is also reduced. Therefore, it is possible to obtain an effect of improving the efficiency and reducing the operation cost accordingly.

[Brief description of the drawings]

1 is a winding arrangement diagram showing an embodiment of the present invention, FIG. 2 is a winding arrangement diagram showing another embodiment of the present invention, and FIG. 3 is a winding arrangement diagram of a conventional industrial transformer. FIG. 1: Iron core, 2, 2A, 2B: High-voltage winding, 21, 22, 23: Tap winding, 3: Low-voltage winding, 31: Disc coil, 32: Lead, 33: Lead, 34: Coil group .

Claims (1)

(57) [Claims] A cylindrical low-voltage winding inserted in an iron core is a multi-parallel disk winding in which a plurality of coil groups are connected in parallel, and other windings including a high-voltage winding and a tap winding are connected to the low-voltage winding. In an industrial transformer arranged coaxially with a pressure winding, the tap winding and the high-voltage winding are each configured by a disk winding,
An industrial transformer, wherein the tap winding is arranged at an axial end of the high-voltage winding or the low-voltage winding.