JPH0241855Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field of the Invention The present invention relates to a large-capacity split single-phase autotransformer.

Technical background of the idea and its problems In recent years, as the demand for electric power has increased, the transmission voltage has also increased, and transformers are also becoming ultra-high voltage and large capacity. For this reason, three-phase transformers are manufactured in units of single-phase transformers that are divided into individual phases, the transportation unit is made smaller to cope with transportation restrictions, and three-phase banks are formed by connecting wires using overhead wires etc. on-site to increase capacity. is planning to change.

FIG. 1 is a typical wiring diagram of a split-type single-phase three-winding autotransformer, and FIG. 2 is a diagram showing its contents. 1 and 2, 1 is a series winding;
2 is a shunt winding, and 3 is a low voltage winding, which are wound around the core leg 4 in this order from the inside: low voltage winding 3, shunt winding 2, and series winding 1. Also, U, u, and V are high voltage line terminal, medium voltage line terminal, neutral point terminal, a, b, respectively.
is a low voltage line terminal.

Generally, the capacity of the low-voltage tertiary winding is selected to be about 30% of the capacity of the high- and medium-voltage windings. For this reason, the impedance of the low-voltage winding based on its self-capacity is small, and the short-circuit current becomes excessive. To withstand this, the current density of the low-voltage winding must be lowered or a current limiting reactor must be connected in series. are doing.

By the way, if the configuration of the split type single-phase three-winding autotransformer shown in FIG. 2 causes transportation restriction problems, it is necessary to further split the single-phase transformer.
Conventionally, when dividing a single-phase device, it was divided into two identical single-phase devices. FIG. 3 shows an example of the configuration. In one tank 51, a series winding 11, a shunt winding 21, a low voltage winding 31, and an iron core 41 are housed, and in the other tank 52, a series winding is housed. 12, a shunt winding 22, a low voltage winding 32, and an iron core 42 are housed, and the windings are connected in parallel through an oil duct as shown. However, in such a divided structure, the impedance of the low-voltage winding is not as large as that in a case where the low-voltage winding is not divided, and the impedance of the low-voltage winding is still small.

Purpose of the invention The present invention aims to eliminate the above-mentioned drawbacks, and its purpose is to provide a split-type single-phase autotransformer that can increase the impedance of the low-voltage winding and also be smaller and lighter.

Structure of the invention In order to achieve the above object, the present invention stores an iron core and a low voltage winding, a shunt winding, and a series winding sequentially wound around the iron core from the inside in one tank, In the other tank, an iron core and a low voltage winding, a series winding, and a shunt winding wound sequentially from the inside of the iron core are stored, and each of the series windings and each of the shunt windings are connected in series. However, each of the low voltage windings is an autotransformer connected in parallel, and each winding of the low voltage winding, series winding, and shunt winding is wound around one main leg of the corresponding iron core. to wear Alternatively, each of the low-voltage winding, series winding, and shunt winding may be divided into a plurality of parallel winding units and wound around a plurality of legs of the corresponding iron core. Furthermore, a plurality of parallel divided winding units may be wound around a plurality of legs of one iron core, and corresponding windings may be wound around the main legs of the other iron core.

Embodiment of the invention An embodiment of the invention will be described with reference to the drawings. FIG. 4 is a winding arrangement diagram of a split type single-phase single-turn transformer according to an embodiment of the present invention. As shown in the figure, one tank 51 contains an iron core 41, a low voltage winding 31 wound around the iron core 41 in order from the inside, and a shunt winding 2.
1 and a series winding 11 are housed therein. The other tank 52 houses an iron core 42 and a low-voltage winding 32, a series winding 12, and a shunt winding 22 that are wound around the iron core 42 in sequence from the inside. The series windings 11 and 12 and the shunt windings 21 and 22 are connected in series through an oil submerged duct, and further a shunt is connected in series to these series connected series windings 11 and 12. Winding 2
1 and 22 are connected in series, this connection point is the medium voltage line terminal U, the series winding end opposite to this medium voltage line terminal U is the high voltage line terminal U, and the shunt winding end is also the neutral voltage line terminal U. Point terminal V is used. On the other hand, each low voltage winding 3
1 and 32 are connected in parallel.

Next, the operation of the single-phase autotransformer configured as described above will be explained. As is well known, a major factor determining the impedance of a transformer is the size of the main gap between the windings. An example of the % impedance of a typical single-phase single-winding transformer shown in Figure 2 is based on the capacitance between the high voltage and medium voltage windings.
Assuming 30% between the low voltage windings and 15% between the medium and low voltage windings, if this is simply divided into two halves as shown in Figure 3, the % impedance between each winding will be the same as before dividing and for each winding. The value is the same based on the line capacity. Here, when dividing the % impedance into each winding, the high voltage winding is 12.5%, the medium voltage winding is -2.5%, and the low voltage winding is 17.5%.
becomes. Therefore, the % impedance that determines the short-circuit current when a short circuit occurs in the low-voltage winding is 17.5, assuming that the power capacity of the high-voltage and medium-voltage windings is infinite.
+(-2.5×12.5)/(-2.5+12.5)=14.4%.

On the other hand, in the split single-phase single-winding transformer according to the present invention shown in FIG. 4, if the winding capacities of the series winding, shunt winding, and low-voltage winding are divided one to one,
The % impedance between each winding stored in the tank 51 is approximately 10% between high voltage and medium voltage windings, 30% between high voltage and low voltage windings, and 15% between medium voltage and low voltage windings based on the capacity of each winding. Become. Further, the percent impedance between the windings housed in the tank 52 is 10% between the high voltage and medium voltage windings, 30% between the high voltage and low voltage windings, and 45% between the medium and low voltage windings. Here, when calculating the % impedance between the high voltage and medium voltage windings, it is (10x10)/
(10+10)=5%. However, in order to make the % impedance between the high-voltage and medium-voltage windings the same 10% as before division, this must be doubled.
In other words, the % impedance between the high voltage and medium voltage windings is (10x10)/(10+10)x2 = 10%. % impedance between medium voltage and low voltage windings and medium voltage
Similarly, the % impedance between the low voltage windings is calculated as (30x30/(30+30)x2=30%)
And (15x45)/(15+45)×2=22.5%. Dividing this into the impedance of each winding as in the case of Figure 3, the high voltage winding is 8.8% and the medium voltage winding is 1.3%.
%, and the low voltage winding is 21.3%. Therefore, the % impedance that determines the short-circuit current when a short circuit occurs in the low-voltage winding is 21.3 + (8.8
×1.3)/(8.8+1.3)=22.4%.

In other words, the winding configuration of the single-phase autotransformer of the present invention shown in FIG. 4 has a lower voltage winding than the single-phase autotransformer shown in FIG. The impedance of the line can be increased approximately 1.5 times. Since the short-circuit mechanical force is proportional to the square of the short-circuit current, the short-circuit mechanical force is 1/(1.5) ² = 0.44, so it is necessary to lower the current density in order to withstand short circuits in low-voltage windings, and to connect current limiting reactors in series. This eliminates the need to connect to the transformer, making the transformer smaller and lighter.

As is clear from the above description, the present invention is not limited to the above-described embodiments, but can of course be modified within the scope of the claims for utility model registration. For example, each winding may be wound around multiple legs of each core housed in each tank of a split type single-phase transformer, and each of these windings may be connected in parallel. One of the cores housed in each tank of the winding transformer can be used as one main leg, and the other core can be used as a plurality of legs and each winding can be wound around the core.

FIG. 5 shows an example of this case, in which two main legs 41A, 41 of the first core of a split type single-phase autotransformer are connected.
Series winding units 11A and 11B, shunt winding units 21A and 21B, and low voltage winding unit 31 in B, respectively.
A, 31B are sequentially wound from the outside and stored in the tank 51, and a shunt winding unit 22A is wound around the two main legs 42A, 42B of the second core of the split type single-phase autotransformer. , 22B, series winding unit 12A,
12B and low-voltage winding units 32A, 32B are sequentially wound from the outside and stored in the tank 52, and these winding units are connected in parallel, and among the winding units connected in parallel, the series winding units 11A, 11B are and 1
2A, 12B and shunt winding units 21A, 21B and 22A, 22B are connected in series, and further, shunt windings 21, 22 connected in series are connected in series to these series connected series windings 11, 12. Furthermore, low voltage winding units 31A, 31B and 32A, 32B are connected in parallel.

Effects of the invention According to the invention, the impedance of the low-voltage winding can be increased, so there is no need to lower the current density of the low-voltage winding so that it can withstand short-circuit current.
Further, there is no need to provide a current limiting reactor. Therefore, it is possible to obtain a split type single-phase autotransformer that can be made smaller and lighter, and can be used to expand transportation restrictions.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of a conventional single-phase autotransformer, Figs. 2 and 3 are winding layout diagrams of a conventional single-phase autotransformer, and Fig. 4 is an implementation of the present invention. FIG. 5 is a winding layout diagram of a single-phase auto-transformer showing another embodiment of the present invention. 11, 12...Series winding, 11A, 11B, 1
2A, 12B...Series winding unit, 21, 22...
Shunt winding, 21A, 21B, 22A, 22B...
Shunt winding unit, 31, 32...Low voltage winding, 31
A, 31B, 32A, 32B...Low voltage winding unit,
41, 42... Iron core, 41A, 41B, 42A,
42B... Main landing gear with iron core, 51, 52... Tank.

Claims (1)

[Claims for Utility Model Registration] (1) An iron core and a low-voltage winding, a shunt winding, and a series winding wound sequentially around the iron core from the inside are stored in one tank, and , an iron core and a low-voltage winding, a series winding, and a shunt winding wound sequentially around the iron core from the inside are housed, and each of the series windings and each of the shunt windings are connected in series, respectively; An autotransformer characterized in that a series-connected shunt winding is connected in series with the series-connected series winding, and each of the low-voltage windings is connected in parallel. (2) A single winding according to claim 1 of the utility model registration claim, characterized in that each winding of a low voltage winding, a series winding, and a shunt winding is wound around one main leg of a corresponding iron core. transformer. (3) A practical device characterized in that each of the low-voltage winding, series winding, and shunt winding is divided into multiple winding units in parallel and wound around multiple legs of the corresponding iron core. An autotransformer according to claim 1 of the patent registration claim. (4) A utility model characterized in that a plurality of winding units divided in parallel are wound around a plurality of legs of one iron core, and a corresponding winding is wound around one main leg of the other iron core. An autotransformer according to claim 1.