JPS6284505A - Three-winding scott connecting transformer - Google Patents

Abstract

PURPOSE:To obtain a three-winding Scott connecting transformer being small- sized and enabling the reduction of manufacturing cost, by adding a tertiary winding to a Scott connection transformer and by disposing a primary winding between a secondary winding and the tertiary winding. CONSTITUTION:A main transformer is formed by providing a core leg 12 with a secondary winding 14 for the main, a primary U terminal side winding 15, a primary W terminal side winding 16 and a tertiary winding 17 for the main, concentrically and sequentially from inside. A teaser transformer is formed by providing a core leg 13 with a secondary winding 18 for a teaser, a primary V terminal side winding 19 and a tertiary winding 20 for the teaser concentrically and sequentially from inside. The primary windings 15, 16 and 19 are connected together by a node M. As for the insulation degree of the secondary windings and the tertiary windings, it may be a half of a conventional one, since each one end Nu1, Nu2, Nv1 and Nv2 thereof is grounded invariably in working. In addition, a dimension G4 between the winding 18 and the winding 19 is made larger than a dimension G5 between the winding 19 and the winding 20, so as to reduce a leakage impedance between the primary windings of the main transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a Scotto connection transformer used as a cylinder transformer.

[Technical background of the invention and its problems]

The cylindrical transformer for supplying power to high-speed four-wheel cars consists of a three-phase two-phase conversion transformer l and a step-up transformer 2, which is called a modified coupled bridge connection, as shown in Figure 4. is used.

(For example, "Railway Technology Research Institute Bulletin J, March 1984.

Yomu-84-39, Published by JNR (Refer to P2.3) The primary winding of the 3-phase 2-phase conversion transformer l is Y-connected and receives power at voltage B, and the secondary winding is connected in parallel with the V phase. With double triangular connection,
Ruru.

The voltage between the 1ffi output terminal ac of this secondary winding is E,
Then, the voltage between the other set of output terminals 6161 is BI
3, and the phase difference between the voltages between terminals ac and terminal 6262 is 90 degrees.

The step-up transformer 2 has a voltage Bv'V' between input terminals b'd'
This is an autotransformer that boosts the voltage between the output terminals b and d, and generates a torsion voltage.In this modified Woodbridge connected transformer system, the neutral point 0 on the primary side can be directly grounded, so the ultra-high voltage The advantage is that power can be received directly from the line, and the insulation of the primary winding can be greatly reduced.

However, power is not only received from ultra-high voltage lines, but also the receiving voltage may be less than 154 KV, and in this case it is not necessarily necessary to draw out the neutral point on the primary side and ground it. 1゜In addition to the 3-phase to 2-phase conversion transformer 1, a step-up transformer 2 is required, which increases the size and manufacturing cost, and requires a large installation space and large construction costs. There is a drawback.

Next, we will explain the reduction of the insulation class on the secondary side. Figure 5 shows a power supply 4 connected to the primary side of a single-phase two-winding transformer 3, which is equivalent to a single seat of a modified crossed-bridge connected transformer. and connect an autotransformer 6 to the secondary side via a breaker 5.
A conventional electric power system with an autotransformer (input T
1. In this method, the secondary side of the power supply transformer 3 is ungrounded, so if the autotransformer 6 is not connected, that is, the interrupter 5 is open. Considering that a ground fault occurs on the secondary side when

Figure 6 shows a recently developed new T system, in which the feeder transformer 8 has a voltage g equal to the electric car voltage Bt.
, /2, and has a secondary winding IO and a tertiary winding 11.

That is, the power supply 4 of voltage E1 is connected to the primary winding 9, the secondary winding tO and the tertiary winding 11 are connected in series, the connection point N is grounded, and the terminals T at both ends are connected.

This is a circuit in which an autotransformer 6 is connected to F via a breaker 5 and connected to an electric car 7.

In actual use, these circuits are prepared for both seats and configured so that the phase difference between their output voltages is 90 degrees. The current is 3
5 to obtain phase equilibrium.

In this new T system, the connection point N is grounded even when the circuit breaker 5 is open, so the insulation class on the secondary and tertiary sides is electrical single I+:l1Xr, that is, secondary.

A value corresponding to the tertiary voltage E,/2 may be sufficient, and can be half of that of the conventional system. .

However, even if one end is connected at the connection point N.

Since the secondary winding 10 and the tertiary winding 11 are independent, an imbalance will occur in the load current flowing through both windings, and there is a risk that abnormal voltage will occur in the event of a ground fault.

Leakage impedance between the windings of the feeder transformer 8 requires proper distribution.

Next, I will explain it. In general, the leakage impedance is l, and one of the 32 sets of windings is j.
is short-circuited, the other winding is applied with two voltages, and the other windings are open.The voltage is calculated from the current il, and the value converted to the reference capacity and voltage is displayed as z-1.

In the case of Fig. 6, the equivalent leakage impedance z? separated into terminals T, N, and P? *zN*zF is defined by the following formula +1).

Regarding this leakage impedance zT @ ZN @ zF, it is necessary to make zT and ZF almost the same value,
ZN needs to be made as small as possible in the positive direction. In other words, if the value of ZN is too large in the positive direction, if the secondary side is short-circuited, the voltage rise on the tertiary side will increase,
If the tertiary side is short-circuited, the voltage rise on the secondary side will increase, which is undesirable, and vice versa.

As the value of Z increases in the positive direction, as a characteristic of this new AT system, the degree of magnetic current unbalance that flows more in the force of the secondary winding than in the tertiary winding increases, which is still preferable. do not have.

As described above, due to operational constraints, the leakage impedance characteristic of the power transformer 8 is required to satisfy the relationship expressed by the following equation (2), which is a major factor.

[Object of the Invention] In view of the five points explained above, the object of the present invention is to apply it to a case where the receiving voltage E is 154 KVJ2 or lower.

The object of the present invention is to obtain a three-winding Scotto connection transformer which is small in size and can be manufactured at a reduced manufacturing cost.

[Summary of the invention]

The dual-purpose transformer according to the present invention is a dual-purpose transformer that has been used conventionally.
Add a tertiary winding to a winding Scotto-connected transformer, place the primary winding between the secondary and tertiary windings, and isolate the secondary and tertiary windings. The class can be reduced to half that of the conventional one, and the leakage impedance characteristic can satisfy the relationship of equation 1 (2).

[Embodiments of the invention]

Examples 1 and 2 of the present invention will be described below as the first factor.
The main seat transformer has an iron core leg 12 for the main seat, and from the inside, the secondary winding 14 for the main seat, the primary U terminal side winding 15°, the primary W terminal side winding 16 J, and the tertiary main seat winding. The winding 17 is wound concentrically. The T-seat transformer has T-buckled core legs 13 in order from the inside.
Secondary winding for section 18. Primary V terminal side winding 19. The fin and T-disused tertiary winding 20 are wound concentrically.

The primary windings 15, 16, and 19 are connected by a connection point M, and the voltage generated by the primary windings 15 and 16 is half of the power supply voltage B, and the voltage generated by the primary winding 19 is 4/4 of the source voltage B1. The secondary winding 14.18. , spear and tertiary winding 17゜2
The magnitude of the voltage generated at each zero point is set to 5 so that it becomes E,/2. FIG. 2 shows the phase difference more clearly, and the iron core legs are omitted.

With the above configuration, if a three-phase power supply is applied to the primary side terminals U, V, and W, it will function like a normal Scotto connection transformer, and the secondary winding 14 for the main seat and the tertiary winding Line 17 has a voltage of the same phase, TN! ! , the secondary winding 18 and the tertiary winding (J!
At 20, voltages having a phase difference of 90 degrees from the voltage for the main seat are obtained.

If the same load is connected to each secondary winding and tertiary winding at the same time, the three-phase current flowing from the primary side will be balanced.
It is similar to an ordinary Scotto connection transformer.

It is clear that the insulation class of the secondary winding and the tertiary winding can be half of the conventional one since one end (N@NulI Nvle Na3) is necessarily grounded during use.

Next, I am confused by this configuration. Leakage impedance characteristics will be explained.

1. When considering the main transformer, the following relationship (3) can be obtained.

zu ””(Zl4-11 +Zt4-1°)/2-
(Zti-ta)/41, :31, where Zl, is the leakage impedance between winding i and winding 1, and is the product of the dimension between the windings (such as Gl shown in Figure 1) and their diameter. Almost proportional.

In order to satisfy the condition of formula (2), it is necessary to set Ztl + Zll from the relationship of formula +1). For this purpose, the dimension Gl between the windings 14 and 15 is made larger than the dimension G3 between the windings 16 and 17 (since their diameter is smaller on the inside). In such an arrangement, zls becomes (Zst
+Zst), approximately 1 times that of 211, or approximately 2.
Since it is about twice as large, from equation (1), ZT in ZF is 0.9×
Z! i s zN medium 0. I X Zl1 * 0.1
1 X Z? The following relationship is obtained, and the relationship of equation (2) can be satisfied.

Next, for the T-seat transformer, the following relationship (13) is obtained.

However, 1, Z, . . . have the same peak as in equation (3). Third
The figure shows the leakage impedance Z'8 between the T-section secondary winding 18 and the primary winding in a T-seat transformer. This figure shows the connections when measuring. That is, the single-phase power supply 21 for measurement is connected to the secondary winding 18 for the T part, and the primary winding side terminals U, V,
W is short-circuited with a short-circuit lead 22, and the flowing current is indicated by an arrow.

When measuring the leakage impedance ZWl between the T-discarded tertiary winding 20 and the primary winding, connect the single-phase power supply 21 for measurement to the T-discarded tertiary winding 20 by connecting it as shown in Figure 3. It is done.

In order to satisfy the condition of formula (2), it is necessary to set z'3□ in 2'□ from the relationship of formula +13. To this end, as shown in FIG. 1, the dimension G4 between the windings 18 and 19 is made thicker than the dimension G5 between the windings 19 and 20 (because their diameter is smaller on the inside), and Zla- Z in 11! G-H
So let's set it to 5.

In such an arrangement, Z 18.1G is (Zl8.IO+
210-111), that is, about 2.2 times zo, 1°, and the leakage impedance between the primary windings of the main transformer, 2□, 6, is Zta,s. of about 0.
It can be reduced to 6 times or less.

Therefore, formula (1), (phantom formula, fin, and the aforementioned z18@llll
":" zto-to 2.2 X in 5z18-1O
Zts, s*, 0.6 Xzts-t in Zts-ts
From o Z T * Z y 0-95 XZ'tt,
ZN * O, Q 48 xz', 0.051X in 1
Z? The following relationship is obtained, and the relationship of equation (2) can be satisfied.

The core configurations are two-core type, in which the main seat core leg 12 and T-zashu core leg 13 are housed in the same tank as separate cores, and the side leg type, in which the two core legs 12 and 13 are shared by a yoke. There is an l-iron core type that is combined into a single piece, and the one that is most suitable for transport to the installation site and the conditions of the installation site should be adopted.

Note that reduced insulation and stage insulation on the primary side by grounding the neutral point on the primary side are not possible with the present invention, but if the insulation class on the primary side is 1.
Considering application to No. 40 and below, even a method of drawing out the connection point M with a lead and adding a lightning arrester will not pose much of a problem from the viewpoint of reducing insulation.

According to the present invention, as can be seen from the above description.

It satisfies the leakage impedance characteristics and has the following features.

(1) Since it is a tank type, it can be made smaller and lighter in heat.

(2) Secondary and tertiary insulation classes can be used in the conventional manner. And 1 for the secondary and tertiary circuits! i! breaker used,
Similarly, for disconnectors, fins, lightning arresters, etc., it is sufficient to use equipment with a low insulation class. There is also one set of each line.

It can be manufactured at low cost because it can be configured with the minimum number of parts required.
The characteristics are also good (can be done).

(13 Separate iron core leg system in which two sets of each of the secondary and tertiary windings of the main transformer are prepared, and the capacity of the windings is increased by 2/3 to allow circulating current to flow through cross-connections. In contrast, according to the present invention, there is no need to flow such a circulating current, so there is no need to increase the winding capacity.

(5) Since the primary winding is placed between the secondary and tertiary windings, the electromagnetic mechanical force generated in the primary winding in the event of a short circuit is directed in the direction of the secondary and tertiary windings. This is an advantageous structure from a mechanical point of view, as it is reversed between (6) In this new AT system, as can be seen in Fig. 6, due to the positional relationship between the autotransformer 6 and the electric car 7, the secondary side and the
Although the flow direction of the current on the secondary side is not the same, and a larger current flows on the secondary side than on the tertiary side, according to the present invention, the current flows in the secondary side.
Since the secondary winding is located inside the tertiary winding, the length of the winding conductor is shorter than that of the tertiary winding, resulting in lower winding resistance and less loss.

Also, in order to prevent the temperature rise of the winding conductor from increasing due to large currents, the cross-sectional area of the conductor is made large, but since the length of the conductor is short due to the inner winding, the weight of the required conductor is small. It has the advantage of being able to use less than external placement. .

If the transformer capacity is very large or transportation conditions are small and transport is difficult, the main transformer and T-seat transformer are stored in separate tanks and connected with an oil submerged duct. [Effects of the Invention] As described above, according to the present invention, leakage impedance characteristics are satisfied, operational problems are eliminated, and the secondary 66 and tertiary winding spacing and The insulation class of the circuit can be halved, and it is compact and
It is possible to provide a three-winding Scotto-connected transformer that can reduce heat generation and reduce manufacturing costs.

[Brief explanation of drawings]

Fig. 1 is a wiring diagram showing an embodiment of the three-winding Scott-connected transformer according to the present invention, Fig. 2 is a wiring diagram showing the winding connections and generated voltage according to the invention, and the third factor is leakage impedance measurement. Fig. 4 is a wiring diagram of a feeder phase transformer with a conventional modified wood bridge connection; Fig. 5 is a circuit diagram of an AT system with a conventional modified wood bridge connection;
The figure is a circuit diagram of an AT system using a new three-winding transformer. Electric phase transformer 5... Breaker 6... Auto transformer 7... Electric car 9, 15.16.19... Primary winding 10.14
．． 18... Secondary winding 1, 17.20... Tertiary winding 1 2.13... Iron core leg agent Patent attorney Noriyuki Nori Yudo Hirofumi Mitsumata Figure 1 Figure 3 WI

Claims (1)

[Claims] In a three-winding Scott-connected transformer in which the main transformer and the T-seat transformer each consist of primary, secondary, and tertiary windings, two Secondary winding, primary U terminal side winding, primary W terminal side winding, and main seat 3
Wrap the next winding, and apply the T to the T-seat transformer core leg from the inside.
A three-winding Scott connection transformer, characterized in that a secondary winding for a seat, a primary V terminal side winding, and a tertiary winding for a T seat are wound.