JPS58166710A - Single phase auto transformer - Google Patents

Abstract

PURPOSE:To provide a small size single phase auto-transformer in which the tertiary voltage does not change by the position of the tap winding and has a small zero phase impedance and a small installation area by providing a first and second iron core legs on the same iron core. CONSTITUTION:As a zero phase circuit there are two circuits, a tertiary winding 3 and a stabilizing winding 8. The zero phase circuit by tertiary winding 8 has no change from the conventional circuits and has a large zero phase impedance. On the other hand, since the stabilizing winding 8 is provided on the main leg 91 of single phase three-leg iron core, the induced voltage per one turn is two times the induced voltage when it is provided on the side leg 92. The zero phase impedance by the stabilizing winding 8 is smaller compared with tertiary winding 3. This can be interpreted that, since the zero phase impedance as seen from high voltage terminal U or medium voltage terminal (u) is the parallel circuit of the stabilizing winding 8 with small impedance and a tertiary winding 3 with large impedance, it is almost determined by the stabilizing winding 8 with small impedance. Accordingly since the stabilizing circuit is not connected to load, its capacity can be small, and the winding on the main leg 91 of a single phase three-leg iron core gives little effect to the size of transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a single-phase autotransformer 62 having high-voltage line terminals, medium-voltage line terminals, and neutral point terminals.

[Technical background of the invention and the stakes]

The direct grounding method is used in the ultra-high pressure power transmission system,
The transformers used for interconnection between such directly grounded systems are manufactured as single-phase autotransformers due to transportation restrictions and economic efficiency, and are assembled and operated in three-phase banks in 31 locations. 8
FIG. 1 is a wiring diagram of such a known single-phase autotransformer. That is, one end of the series M1 is connected to the high voltage line terminal UC,
The other end is connected to the medium voltage line terminal U and one end 6 of the shunt winding [2], and the other end of the shunt winding @2 is connected to the terminal P of the switching switch 6.
Connected to G. Terminal p1. which serves as a fixed contact of this switching switch 6. Pfi is provided with taps 11#40 and g2 on both ends. Each tap of the tap winding 4 is connected via a tap changer 7 to a neutral point terminal 7 (two connected. Tertiary IIklI3
and the excitation winding 5 has two terminals α and b so that they are in parallel relationship.
connected to. Fig. 2 shows the specific arrangement of the winding heddle of the single-phase ratio winding transformer mackerel shown in Fig. m1.

In other words, the secondary winding m3 is mounted on one main leg 91 of the single-phase four-leg iron core.
x*Shunt winding 21. The series winding 11 is wound, and the other main leg 9B + two tertiary windings a 3s e shunt winding! 2s*[i
.

Row @ string 11 is wound. Sara 52 single phase 48&1I
The excitation winding 5 and the tap winding 4 are wound around the vC core @ leg 9B C. Mara, #g2 The specific winding arrangement in Figure 1: Series winding 11 shunt winding #! 2 and tertiary winding 3 are each series winding 1! It is composed of Il and 1s9 shunt windings 21 and 2s and tertiary windings 31 and 33,
And series windings 11 and 131 and shunt windings IM21 and 2! .

The secondary windings Mal and 33 are in a parallel relationship C2 (
is connected.

In the single-phase single-winding transformer can shown in FIG. 2, the voltage at the medium voltage line terminal U is constant C, and the voltage at the separating voltage line terminal U is variable, so the voltage at the excitation winding Ivi15 is low, and the voltage at the excitation winding Ivi15 is low.
It has the advantage of being relatively easy to set up, but since the voltage at the end of the high-voltage narrow path is varied by changing the tap on the neutral point side, the excitation rate of the iron core changes depending on the tap position, and therefore the tertiary voltage It also has the disadvantage that it changes very little. In general, a capacitor or an acdle is connected to terminals a and b of the tertiary winding to adjust the reactive power, so if the terminal voltage fluctuates from tap position C2, the utilization rate of the capacitor etc. will decrease. be. For this reason, a method has been proposed in which the excitation of the tertiary winding is connected in parallel with a shunt winding and a tapped series circuit in order to keep the tertiary voltage constant. In the winding #I structure, the tertiary voltage is constant regardless of the tap position, but there is a drawback that the zero-sequence impedance becomes large. The reason for this will be explained. Since the zero-sequence current flows only through the Δ circuit g2, the impedance between the tertiary winding and other windings determines the zero-sequence impedance. The impedance is inversely proportional to the square mee of the induced voltage per turn of the winding, and is -10,000 turns #! Since the induced voltage for one turn or more is proportional to the core cross-sectional area C2, y, the impedance is inversely proportional to the square of the core cross-sectional area. However, since the side legs of the iron core and the separate iron core have a smaller cross-sectional area than the main legs of the iron core, the zero-sequence impedance increases.

When the zero-sequence impedance increases, the abnormal voltage at the time of a - line ground fault increases, which poses a major problem in terms of system maintenance.

[Purpose of the invention]

The present invention obviates the above-mentioned drawbacks4, so its objectives are to:
To provide a small single-phase ratio-wound transformer whose tertiary voltage does not change depending on the tap position ti1 of a tap winding, whose zero-sequence impedance is small, and whose installation space is small.

[Summary of the invention]

In order to achieve the above object, the present invention has a single-phase ratio winding transformer having a voltage line terminal, a medium voltage line terminal, and a neutral point terminal, and tap winding on the first core leg. 9. A shunt winding, a series winding and a stable winding are wound around the second core leg, a tertiary winding and an excitation winding are wound around the second core leg, and the high voltage line terminal and the medium voltage line terminal are wound. The series winding is valved and connected, and the medium voltage line terminal and the neutral point terminal are connected to a series circuit of the shunt winding and the tap winding, and the IJ circuit. The connection is made through the excitation winding which is parallel to the excitation winding. The @1 core leg and the second core leg may be provided on the same core, or may be provided on separate cores that are not magnetically coupled to each other.

[Embodiments of the invention]

Figure 01g3, which will be explained with reference to drawings representing an embodiment of the present invention, is a wiring diagram of the single-phase single-winding transformer sushi of the present invention, and Figure 4 is a specific wiring diagram of the winding. In Figure 3C, one end of the series winding 1i11 is connected to the high voltage line terminal υ, and the other end is connected to the medium voltage Iw line terminal U9 shunt winding 1ii1512.
It is connected to one end of the excitation winding 5 and to one end of the excitation winding 5 . The other end of the shunt winding 2 is connected to the terminal PQ of the switching switch 6 through the tap switching gain 7 to the neutral point terminal Vl, and the terminals Pi, P@ which become the fixed contacts of the switching switch 6 Fi tap 41 Both ends 1 of wire 4: Provided. In addition, the tertiary winding 3 is connected between terminals a and l), and the stable winding 8Vi terminal s
, yfklJl two connected 0 and terminals x, y
When there is a three-phase puncture in three single-phase transformers, C2-Δ connection is made and one point is grounded. It is. That is, single phase tripod iron core king jarll 9
1. Tamp winding sequentially from the inside! ! 4. Stable winding 8° shunt 11!2. The series winding l is wound concentrically, and the side leg 9 of the sales iron core is also wound! Secondary winding in order from the inside @3. Encouragement be*5 to -6
Wind it into a shape.

In this embodiment, the transformer winding structure as shown in FIGS. 3 and 4 is used, so the zero-phase circuit can be used as a 3rd order! ,
I! There are two circuits: 3 and stable winding Ia8.

The former's tertiary II! f! The zero-phase 1i2 circuit using 1li13 is no different from the conventional circuit, and has a large zero-phase impedance. On the other hand, the stable winding 8 is connected to the tripod 9 of the single-phase tripod core.
1, the I electromotive force per turn of the winding is twice as much as when two side legs 92 of the wrinkled core are provided, so the zero-sequence impedance due to the stable 1m8 is It is smaller than the zero-sequence impedance of winding @3. This means that the zero-sequence impedance seen from the high-voltage terminal U or the medium-voltage terminal is a parallel circuit of the stable winding 8 with low impedance and the secondary winding 83 with high impedance. Therefore, it can be considered that most of the impedance is determined by the stable winding 8, which has a small impedance.Then, since no load is connected to the stable winding 8, its capacity is small, and the winding around the main leg 91 of the single-phase tripod core is sufficient. Even if you turn it, the size of the transformer C-4 will appear W
is small.

Furthermore, since the present invention arranges the tap winding 4 between the stable winding 8 and the tripod 91 of the single-phase tripod core as shown in Figure 144C, it is also effective to prevent the tap winding 4 from floating. That is, when switching the switching opening/closing 66 from terminal P1 to terminal P2 or vice versa as shown in FIG. 3, there is a moment when the tap winding 4 is completely separated from the shunt winding 2, and at this time the tap potential Due to the capacitance distribution between adjacent windings, the voltage becomes extremely high and may exceed the withstand voltage value of the switching switch 6. To prevent this kind of thing
i. Connection between the tap winding and the ground: ^ It is common to insert a resistor to suppress the potential of the tap winding so that it does not exceed the withstand voltage value of the switching switch, but in the present invention, # 'i 4th
As shown in the figure, since a grounded stable winding 8 is provided on the outside of tap winding #4, this stable winding 8 has a shielding effect, and therefore the acid two tap i/! Even if the f edge 4 is 70-tall, the voltage does not become high, and the voltage can be kept below the withstand voltage of the switching switch 6, and there is no need for a high resistance body for preventing tap float as described above.

Furthermore, in the embodiment shown in FIGS. 3 and 4, a single-phase tripod core is used, but the core around which the excitation III wire 5 and the secondary winding 11I3 are wound, the series winding 11, and the shunt winding. @2.
The iron core around which the tag winding edge 4 and the stable winding @B are wound may be a separate iron core 7 with no magnetic coupling.

In the case of such an iron core configuration, the third-order @ItM3
Or, if there is some kind of accident in the excitation winding 5, these windings are connected to the series winding 19, the shunt winding 2. Even if the main transformer core m1ll2 is separated from the live transformer core around which the tap winding 4 and the stable winding 8 are wound, it has the advantage that it can operate normally because the stable winding 11118 is wound around it. In the example, a single-phase tripod core is used, but
The present invention is not limited to this, and for example, a ratio-phase four-legged core or a single-phase three-legged core may be used. In this case, each of the main legs of the ratio-phase four-legged core or the single-phase three-legged core is ≦2 series windings and 9 shunt winding edges.

A tap winding and a stable winding are arranged, and regular windings are used in parallel 1J class. And at this time I'm so excited
The first winding and the tertiary winding are wound on a side leg of the above-mentioned iron core or on a separate iron core having no magnetic coupling with the iron core.

Furthermore, the winding order of the windings wound within each core may be reversed within the same core.

〔Effect of the invention〕

According to the present invention as described above, in a single-phase autotransformer having a high-voltage line terminal, a medium-voltage line terminal, and a neutral point terminal, the tertiary voltage obtained from the tertiary winding is applied to the tap winding. It is possible to provide a compact single-phase autotransformer that does not change depending on the tap position of the line, has low zero-sequence impedance, and requires a small installation space.

[Brief explanation of drawings]

Figure 1 is a wiring diagram of a conventional single-phase autotransformer, and Figure 2 is a wiring diagram of a conventional single-phase autotransformer.
3 is a wiring diagram of a single-phase single-winding transformer according to an embodiment of the present invention, and FIG. 4 is a winding layout diagram of FIG. 3. ■...High voltage line terminal U...Medium voltage W line terminal V...
・Neutral point terminal 1...Series winding 2...Shunt winding 3...Tertiary winding 4...Tap @k
5... Excitation winding 6... Switching gain 7... Tap changer 8... Stable winding 1Ij9ie 9sie 9
a - Tetsushin Kyaku (8733) Agent Patent Attorney Sho Miscellaneous
Akira (#Maka1 person) Figure 1 Figure 2; rs Figure 3 Figure 4

Claims (2)

[Claims] (1) In a single-phase single-winding transformer that has a high-voltage line terminal, a medium-voltage line terminal, and a neutral point terminal, the first core leg C-nitap winding 1 branch winding, series winding, and safe winding blaming,
Further, a tertiary I#1 wire and an excitation winding string are wound around the second core leg, and the high voltage line terminal and the medium voltage line terminal are connected via the direct IJI#f wire, and , characterized in that the medium voltage line terminal and the neutral point terminal are connected via the 11JJWi winding that is parallel to the series circuit of the shunt winding and the tap winding, and the 11JJWi winding that is parallel to the series circuit of the shunt winding and the tap winding. Single-phase autotransformer 0 (2) The first core leg and the second core leg are -1
- A single-phase autotransformer according to item 18i of the patent application, characterized in that the iron core C is bifurcated. (Group) The single-phase rate l# transformation described in Section 1 of the scope of the patent, characterized in that the first core leg and the ratio 2 core leg Fi are provided in separate cores without magnetic coupling. vessel.