JPS61214409A - Autotransformer - Google Patents

Abstract

PURPOSE:To prevent a circulating current flowing in the tertiary coil by parallelly connecting the exciter coil with either one of the series coil or the shunt coil. CONSTITUTION:The series coil 1, the shunt coil 2 and the tertiary coil 3 are wound around the main leg 61 of a magnetic iron core, and the tap coil 4 and the exciter coil 5 to excite the side leg 62 are wound around the leg 62. The junction of the series coil 1 and the shunt coil 2 connected in series is connected to one end of the tap coil 4, from the other end of which the secondary terminal (u) is drawn out. The exciter coil 5 is connected with the shunt coil 2 in parallel to be excited.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an autotransformer, and in particular, the present invention relates to an autotransformer. [Background of the Invention] Conventionally, the voltage on the secondary winding side, that is, the series winding side, is held constant, and the voltage on the secondary winding side, that is, the series winding side, is In autotransformers that switch the voltage on the secondary winding side, that is, on the shunt winding # side, it is advantageous to use a fork connection in order to prevent the voltage on the tertiary winding side from fluctuating. There is.

FIG. 7 shows the winding arrangement of a fork-connected autotransformer that meets the above requirements, with the tertiary winding 3. Tap winding 42 shunt winding l112. The series windings ls1 are arranged concentrically in this order.

Here, the series winding l1iJi and the shunt winding 2 are connected in series, one end of the tap winding 4 is connected to the connection point thereof, and the secondary terminal U is drawn out from this tap winding ff54. Note that U indicates a primary terminal drawn out from the series winding a1, N indicates a neutral point terminal drawn out from the low voltage side of the shunt winding, and a and b indicate terminals of the tertiary winding.

This connection method has the advantage that the magnetic flux within the magnetic core legs 6 is not dense.

However, since the tap winding 4 is arranged between the tertiary winding #J3 and the shunt winding 2, the tertiary winding #j! 3- and shunt winding 2
The distance between the two becomes thicker and smaller.

Therefore, the amount of interlinkage magnetic flux in the space between the tertiary winding 3 and the shunt winding 2 increases, and as a result, the percent impedance between the negative side and the tertiary side and between the secondary side and the tertiary side increases, respectively. growing.

Furthermore, as shown in FIG. 8, in an autotransformer in which the voltages of K and shunt windings 2 are held constant and the voltages of series windings 1 (Ill) are switched, the same applies as described above. Each percentage impedance increases.

The winding arrangement in FIG. 8 is similar to that in FIG. 7, except that the secondary terminal U is drawn out from the connection point between the shunt winding 2 and the tap winding 4.

FIG. 9 shows the interlinkage magnetic flux distribution in the winding radial direction between the primary side and the tertiary side and between the secondary side and the tertiary side in the winding arrangement shown in FIGS. 7 and 8. FIG.

As mentioned above, a large percentage impedance between the negative side and the tertiary side (111 questions) and between the secondary side and the tertiary side is advantageous in terms of suppressing the short-circuit current on the tertiary side.
The drawback is that voltage fluctuations on the tertiary side become large. This is particularly problematic in that when a reactor is connected to the tertiary side to compensate for reactive power, a drop in the tertiary voltage results in a drop in the compensable carp effect power.

Therefore, the autotransformer used for this purpose is
- It is required to reduce the percent impedance between the secondary side and the tertiary side and between the secondary side and the tertiary side.

To meet this requirement, in the conventional winding arrangement described above, the diameter of the magnetic core must be extremely large to reduce the percent impedance between the primary and tertiary sides and between the secondary and tertiary sides. Since the number of wire turns is reduced and the distance between the series winding and the shunt winding is made very large, the transformer becomes extremely uneconomical.

Therefore, as a measure to reduce the above-mentioned percent impedance, the brochure "Siemens, Zeitschrift" ((Siemen 5-Zeit sc'hr.
ift41 (1967') Heft1. )), the paper published on pages 23 to 31 of ra sok
00-MVA-Drehstromb'jnke m
it 380-kV-Einph-asen-8p
There is a configuration introduced by VC.

The concept of this configuration is shown as a winding connection diagram in FIG. 10 or FIG. 11.

The basic idea is that the tap winding 4 and the excitation winding 31 that excites the stiffness are wound around a magnetic core side leg separate from the magnetic core main leg 6, and the tertiary winding 3 and the shunt winding are arranged. The goal is to reduce the distance to line 2.

In addition, FIG. 10 shows an example in which the tap winding 4 is connected in series to the shunt winding 2 side and the tap is switched while keeping the voltage on the series winding L side constant, and FIG. An example will be shown in which a tap winding 4 is connected in series to the winding l side and the taps are switched while keeping the voltage on the shunt winding 2 constant. Even during busy times, the excitation winding 31 is connected in parallel to the tertiary winding 3 and is not excited.

However, in the conventional example shown in Figures 10 and 11, in taps other than the rated taps, in order to cancel the ampere turn due to the current 1'↑ flowing in the tap winding, a current is applied to the excitation winding #J31. Since the current i:I- circulates through the tertiary winding 3, there is a drawback that the actual capacity of the tertiary winding must be increased in size. In addition, there was also the drawback that the current It circulating through the excitation winding 31 and the tertiary winding 3 increased load loss.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a fork-connected autotransformer which improves the drawbacks of the prior art described above and reduces losses by preventing circulating current from flowing through the tertiary winding.

[Summary of the invention]

In order to achieve this object, the present invention energizes a tap winding on a side leg of a magnetic core that is separate from a main leg of a magnetic core in which a series winding, a shunt winding, a tertiary winding, etc. are wound. The present invention is characterized in that an excitation winding is wound in a winding arrangement, and the excitation winding is configured such that a chair of the series winding or the shunt winding is connected in parallel with one of the windings.

[Embodiments of the invention]

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 6. In the drawings, the same or equivalent parts as in FIGS. 7 to 11 are designated by the same reference numerals. The embodiment shown in FIG. 1 shows an embodiment using a center core type magnetic core, and the main leg 61 of this magnetic core includes a series winding #1, a shunt winding 2, and a tertiary winding 3. Winding arrangement, side legs 62K
, a tap winding 4 and an excitation winding 5 for excitation are wound on the side legs. A series winding 1 and a shunt winding @2 are connected in series, one end of a tap winding 4 is connected to the connection point thereof, and a secondary terminal U is drawn out from the other end of the tap winding 4. The excitation winding 5 is connected in parallel to the shunt winding 2 and is excited.

With such a configuration, considering the windings and the flux linkage distribution between the windings, the tap winding 4 cannot be wound around the side leg 62 that is different from the main leg 61, so the tertiary winding 3 and , the distance between the series winding 1 and the shunt winding #2 can be reduced, and the interlinkage magnetic flux can be reduced as shown in Figure 21FIk.

In addition, in the second diagram, A is the shunt winding 2 and the tertiary winding, therefore,
The percentage impedance between the series winding @1, that is, the primary side and the tertiary winding 3, that is, the tertiary side, and between the shunt winding 2, that is, the secondary side and the tertiary side can be reduced.

Further, as described above, there is no problem of substantial increase in winding capacity and increase in load loss due to circulating current when the excitation winding 5 and the tertiary winding 3 are connected in parallel.

The reason for this will be explained using FIG. 3.

Figure 3 shows the direction of current flow in each winding.
This example shows a case where a tap with a lower voltage than the rated voltage with the tap position in the center is selected. Fork-connected autotransformers are generally selected with low tap voltage,
Since the current flowing through the shunt winding 2 and the tap winding 4 becomes large, the load loss becomes large, and the load loss is usually maximum at the lowest voltage tap.

Figure 10 and ! In the conventional example shown in the lt diagram where the excitation winding 31 and the tertiary winding 3 are connected in parallel, the load loss increases because the current flowing through the shunt winding 2 and the tap winding 4 increases. In addition, this excitation winding 31 and the tertiary winding 3
The load loss also increased due to the current flowing through the circuit. However, according to the present embodiment, the current 1c flowing through the shunt winding 2 is constant and is equal to the current when the tap with the rated voltage is selected. In order to cancel the ampere turns due to the flowing current IT, the current IE flowing through the excitation winding 5 is connected to the shunt winding 2 connected in parallel.
At a tap with a voltage lower than the rated voltage, which flows through the tap winding as a load current and causes a large load loss, there is no flow of 1 circulating between the windings. Therefore, load loss can be made smaller than in the conventional example in which the excitation winding 31 and the tertiary winding 3 are connected in parallel.

Furthermore, in the tap with a voltage lower than the rated voltage, the one current flowing to shunt winding #2 increases in the conventional configuration, but does not increase in the configuration of the present embodiment.

For this reason, in conventional configurations, the capacity of the tertiary winding 3 is substantially increased due to the circulating current, and the shunt winding 2 and the excitation winding 5
Since the combined capacity of the shunt winding 2 can be made the same as the capacity of the conventional shunt winding, the capacitance of the shunt winding 2 itself can be reduced.

In the configuration of this embodiment, at a tap with a voltage higher than the rated voltage, the current Iz flowing up the excitation winding l/s5 flows through the shunt winding 2 and becomes a circulating current, but this current Since it is smaller than the current flowing through the excitation winding 5, the load loss is smaller than in the case of the lowest voltage tap, and this circulating current becomes a problem because 1. - Yes.

In the embodiments of FIGS. 1 to 3, the shunt winding 2 has a tap winding l.
A case where the present invention is applied to an autotransformer in which R4 is connected in series and the voltage of the series winding 1 is held constant even by changing taps is shown.

In Figures 4 to 6, the tap winding 4 is connected in series to the single series winding 1, and the voltage of the /; J-% winding is kept constant even by changing the tap. An embodiment in which the present invention is applied to a pressure vessel will be shown.

This embodiment differs from the configurations in Figure f1 and Figure 3 as follows:
The secondary terminal U is drawn out from the high voltage side of the shunt winding 2, and one end of this secondary terminal uK tap winding 4 is connected, and the excitation winding #J5 is connected in parallel to the series winding i1. .

FIG. 5 shows the interlinkage magnetic flux distribution in the winding radial direction in the 4-th winding wiring wt, VC, and ! It shows almost the same tendency as the flux linkage distribution of 211N.

FIG. 6 shows the current flow situation when a tap with a voltage lower than the rated voltage is selected in this embodiment.

In an autotransformer in which tap switching is performed by the series winding 1111j on the high voltage side, the lower the voltage of the selected tap, the larger the current flowing through the series winding 1 and tap winding 4 K@, so the load loss is reduced. is large, and the load loss is usually greatest at the lowest voltage tap.

However, as shown in FIG. 6, according to this embodiment, the current Is flowing through the series winding 1 is always constant and equal to the current when the tap with the rated voltage is selected,
In order to cancel the ampere turn caused by the current 1 tl flowing through I4, the current 1 g flowing through the excitation winding 5 does not flow through the series winding 1 connected in parallel 1c, but instead becomes a load current and is applied to the tap winding 4. Flowing.

In other words, according to this embodiment, in a tap with a voltage lower than the rated voltage where the load loss is large, P is circulated between the % lines.
There is no current that changes f.

Therefore, the load loss can be lower than the conventional example in which the excitation winding #31 and the tertiary winding disconnection 3 are connected in parallel. While the current Is flowing through the wire 1 increases, in the configuration of this embodiment, it increases and the capacity l- of the column winding 1 itself can be reduced.

In addition, in the configuration of this embodiment, at a tap with a voltage higher than the rated voltage with the tap in the center position, the current flowing through the excitation winding #5 flows through the series winding and becomes a circulating current, but this current Since it is smaller than the current flowing through the excitation winding 5 at the lowest voltage tap, the load loss is smaller than at the lowest voltage tap, and as in the embodiments shown in FIGS. 1 and 3 described above, this circulating current is It has no negative influence.

〔Effect of the invention〕

As explained above using the embodiments, according to the present invention,
In a fork-connected autotransformer, it is possible to provide an autotransformer that can reduce loss by preventing the circulating tIL flow flowing into the tertiary winding.

[Brief explanation of the drawing]

Fig. 1 is a winding layout diagram of an autotransformer showing an embodiment of the present invention, Fig. 2 is a diagram showing the interlinkage magnetic flux distribution in the winding radial direction in the winding arrangement of Fig. 1, and Fig. 3 is the winding connection diagram in Figure 1,
Fig. 4 is a winding arrangement diagram of an autotransformer showing another embodiment of the present invention, Fig. 5 is a diagram showing the interlinkage magnetic flux distribution in the winding radial direction in the winding arrangement of Fig. tP4, and Fig. 6 is a winding connection diagram of FIG. 4. Figures 17 to 11 show examples of conventional autotransformers, Figures 7 and 8 are winding arrangement diagrams, and Figure 9 is a diagram of the winding radial direction in these winding arrangements. The diagrams showing the flux linkage distribution, FIGS. 10 and 11, show the winding # connection diagrams of other conventional examples. 1: Series winding, 2: Shunt winding, 3: Tertiary winding, 4: Tap winding, 5: Excitation winding #. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7--Figure 8 Figure 9 Figure 10

Claims (1)

[Claims] 1. A magnetic core consisting of a main leg and a side leg; a series winding, a shunt winding, and a tertiary winding concentrically wound on the main leg side of the magnetic core; A tap winding and an excitation winding are arranged concentrically, and the tap winding is connected in series with either the series winding or the shunt winding, and the tap winding is connected in series with either the series winding or the shunt winding. In the autotransformer configured to switch the voltage of the shunt winding, the excitation winding is configured to be connected in parallel with either the series winding or the shunt winding. An autotransformer featuring: