JPH025281B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a transformer, and more particularly to a structure of a transformer suitable for adjusting voltage under load.

Technical background of the invention In recent years, as the demand for electricity has increased, the transmission voltage has also increased, and transformers have also become extremely high voltage and large in capacity.Currently, 500kV autotransformers with a bank capacity of 1500MVA are also manufactured and in operation. .

When adjusting the voltage of such a large transformer,
If a tap winding is provided within the main transformer, the size and weight will increase and it will not be possible to keep it within transportation limits such as rail transportation. Therefore, as is well known, a method is used in which the voltage is adjusted by combining a main transformer without tap windings and a load voltage regulator.

FIG. 1 shows a conventional example of an excitation transformer constituting such an on-load voltage regulator, in which a is a block diagram thereof and b is a wiring diagram thereof. In the figure,
1 is a single-phase tripod iron core, and an excitation winding 2 and a tap winding 3 are wound around the main leg. Although only one wire of this tap winding 3 or a lead wire connecting it to the tap changer is shown in the figure, it can be configured as a two-circuit or three-circuit parallel configuration for each phase of the tap changer at the time of a three-phase load. In some cases, it is connected to a selector so that a small tap changer can be used.

Problems in the technical background Recently, however, there has been a growing demand for increased capacity per transformer due to the growth in power demand, and there has also been a growing demand for a wider voltage adjustment range to facilitate grid operation. There is. In order to meet such requirements, the on-load voltage regulator must also increase its capacity or tap voltage. In this case, in the conventional configuration described above, each leg of the winding requires insulation that can withstand the entire tap voltage induced when a surge enters, so as the tap voltage increases, it is necessary to strengthen the insulation within the tap winding 3. The drawback is that the winding becomes larger and the weight of the device increases.

OBJECTS OF THE INVENTION The present invention takes the above-mentioned points into consideration and aims to provide a transformer that is light in weight and has less loss.

Summary of the Invention In order to achieve this object, the present invention uses a single-phase two-leg iron core, and winds a tap winding and an excitation winding around each of the two main legs in order from the inside. While the excitation windings of are connected in parallel,
Tap windings are connected in series to form the entire tap winding to form a transformer, and when making a three-phase transformer,
The feature is that three of these are combined.

Embodiments of the Invention Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 2 shows an excitation transformer constituting a single-phase on-load voltage regulator according to an embodiment of the present invention, in which a is a structural diagram thereof and b is a wiring diagram thereof.

In the figure, the iron core is composed of a single-phase two-legged iron core consisting of two legs 11 and 12 and a yoke, and from the inside of the iron core legs, a tap winding 31, an excitation winding 21, a tap winding 32, and an excitation winding 22 are connected. They are wound concentrically in order. The excitation windings 21 and 22 are connected in parallel as shown, while the tap windings 31 and 32 are connected in parallel.
are connected in series to form the entire tap winding. Therefore, the tap windings 31 and 32 each have a capacity approximately half that of all the tap windings.

According to the above configuration, since the tap windings 31 and 32 are connected in series, the shared voltage of each tap winding is about half of the shared voltage of all the tap windings.
Therefore, even if the voltage of the tap winding increases, the insulation reinforcement within each tap winding 31, 32 can be reduced compared to the conventional example, and it is possible to prevent the tap winding from increasing in size. can. In addition, the total number of tap leads 4 is distributed among the tap windings 31 and 32, which simplifies the lead-out structure.

Furthermore, since the tap winding is wound inside the excitation winding, source loss due to winding leakage magnetic flux can also be reduced. This will be explained with reference to FIGS. 3 and 4. Incidentally, in these figures, the windings in the legs 11 and 12 are omitted to simplify the explanation.

That is, as shown in FIG.
2 is wound outside the excitation windings 21 and 22,
Since the excitation windings 21 and 22 are connected in parallel,
The main magnetic fluxes 51 and 52 passing through the core legs 11 and 12 become equal and induce the same voltage in the two excitation windings. Therefore, the winding leakage magnetic flux 6 due to the energization of the windings 22 and 32 does not enter the core leg, but almost flows to the outside, such as the tank wall 7. For this reason, there is a risk that stray loss on the tank wall 7 will increase and local heating may occur.

On the other hand, in the case of this embodiment, as shown in FIG. 4, the amount of magnetic flux in the outer excitation windings 21 and 22 is the same, and the same voltage is induced. For this reason, the winding leakage magnetic flux 8 due to the energization of the windings 22 and 32
Contrary to FIG. 3, the gas enters the core and flows in a circular manner. In this case, since the iron core is made of an excellent low-loss material, the stray loss caused by this leakage magnetic flux is extremely reduced.

Although the extreme case in which current flows only in one tap winding has been described above, the same can be said in the case where the capacitances of the two legs are at slightly different tap positions.

Therefore, according to this embodiment, a single-phase on-load voltage regulator can be obtained which has low stray loss and is excellent in quality such as overheat prevention in a large capacity device.

It goes without saying that a three-phase on-load voltage regulator can be obtained by combining three single-phase on-load voltage regulators explained in the above embodiments.

In this case, it goes without saying that the three single-phase voltage regulators may be connected through an oil submerged duct, or the contents may be installed in one tank. . Furthermore, whether it is a single-phase device or a three-phase device, it goes without saying that a parallel configuration of two or three circuits of tapped wires and lead wires may be used as explained in the conventional example. Furthermore, in the above embodiment, for convenience of explanation, the tap lead is drawn out from the middle of the tap winding, but in reality, each tap winding is wound in a cylindrical shape, and each tap lead is pulled out from the upper and lower ends of the winding. Needless to say, this happens a lot. Furthermore, although the above embodiment has been described using an on-load voltage regulator as an example, the present invention is not limited to this, and it goes without saying that, for example, a tap-switching transformer or the like may be used.

Effects of the Invention As described above, according to the present invention, a lightweight and low-loss transformer can be obtained.

[Brief explanation of drawings]

Figure 1 shows the internal configuration of a conventional on-load voltage regulator, where a is its structural diagram, b is its wiring diagram, and
The figure shows the internal configuration of a load voltage regulator according to an embodiment of the present invention, in which a is a structural diagram, b is a wiring diagram, and FIG. 3 is a leakage magnetic flux with a winding arrangement different from that in FIG. 2. FIG. 4 is an explanatory diagram of leakage magnetic flux in the winding arrangement of FIG. 2. 1... Single-phase tripod iron core, 2, 21, 22... Excitation winding, 3, 31, 32... Tap winding, 4... Tap lead, 6, 8... Winding leakage magnetic flux, 7... Tank wall, 1
1, 12...Single phase biped iron core leg, 51, 52...Main magnetic flux.

Claims (1)

[Scope of Claims] 1. A tap winding and an excitation winding are wound in order from the inside on each core leg of a single-phase two-leg iron core, and the excitation windings are connected in parallel, while the tap winding A transformer characterized by connecting two wires in series to form a tap winding. 2. A transformer according to claim 1, characterized in that three transformers having the above configuration are combined to form a three-phase system.