JPS62279612A - Transformer for ac to dc converter - Google Patents

Abstract

PURPOSE:To reduce a potential difference between an AC-side winding and a DC-side winding by a method wherein both windings wound on a core are formed by winding a sheet-shaped conductor and insulating paper and are disposed so that the low-potential sides thereof are opposite to each other. CONSTITUTION:The title transformer is formed by winding a tertiary winding 11 on a transformer core 10 formed of laminated electric iron plates, by winding an AC-side winding 22 further thereon and by winding further thereon a DC-side winding 23 connected to a thyristor valve. The AC-side winding 22 and the DC-side winding 23 are formed by winding a sheet-shaped conductor and insulating paper in a number of layers. In this sheet-shaped winding, the inner peripheral surface can be set as a neutral point potential N in a Y connection and the outer peripheral surface as a high-voltage potential element as is seen in the AC-side winding 22, for instance. In the DC-side winding 23, likewise, the inner peripheral surface can be set as a high potential element and the outer peripheral surface as a neutral point potential N. In such a state as described above, a voltage is not impressed substantially between the AC-side winding 22 and the DC-side winding 23.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention relates to a transformer for an AC/DC converter, and particularly relates to an improvement in the winding insulation structure. ) With the increase in demand for electricity in recent years, DC power transmission has been used in a wide range of applications, as it has many advantages in terms of system operation, such as large-capacity, long-distance, one-distance power transmission and power interchange between systems with different frequencies. At present, there are 1 domestic grid connections in some areas, and 2
50 kV DC power transmission has been implemented, and it is hoped that this DC power transmission will have a larger capacity and higher voltage in the future.

FIG. 4 shows a typical connection diagram of an AC/DC converter station in conventional DC power transmission. The AC/DC converter station shown in the figure is a unipolar 12
It performs phase rectification and is an open/close bag from 3-phase AC voltage system 1.
2. Voltage is supplied to the Cysta valve 5.6 through the AC/DC converter transformers 3 and 4, converted to DC voltage, and transmitted to the DC line 7.

This AC/DC converter station uses a 12-phase rectification system, so the AC/DC converter transformers 3 and 4 are a Y-Y connection AC/DC converter transformer 3 on the high voltage side, and a Y-Δ connection AC/DC converter transformer on the low voltage side. It consists of 402 machines. These AC/DC converter transformers not only supply AC voltage to the thyristor valves, but also play a major role in electrically insulating the secondary AC side and the secondary DC side. An example of a conventional winding structure of this AC/DC converter transformer is shown in FIG.

That is, it is a vertical cross-sectional view of a part of the iron core and a part of the winding. A tertiary winding is wound around a voltage generator core 10 made of laminated electrical iron plates, a DC side winding 12 connected to a thyristor valve is wound thereon, and an AC side winding 13 is further wound on the outermost side of the tertiary winding. Wind. An electrostatic shield 14a is provided at the end of each winding to provide the same potential as the end of each winding in order to alleviate the electric field.
, 14b; 15a, 15b are attached. Also,
An insulating barrier is provided between each winding to withstand the respective operating voltage and test voltage.

In this AC/DC converter transformer, the DC side winding 12 is electrically connected to the DC system through the thyristor valve, so a DC voltage is always applied during operation, and the DC voltage is added to the AC voltage supplied from the negative side. The voltage is in a biased state. Therefore, around the DC side winding 12, a DC insulation design technology that is not found in conventional AC transformers is required. As described above, the insulation design of AC/DC converter transformers requires consideration of DC voltage, and this necessity is becoming more and more prominent as voltages become higher.

(Problems to be Solved by the Invention) In FIG. 5, a (DC/AC) voltage is applied to a circled and hatched portion 16 between the DC side winding 12 and the AC side winding 13. In this portion 16 insulated by the oil-impregnated paper, there is a phenomenon in which the DC voltage component is applied to the oil-impregnated paper, and the AC voltage component is applied almost equally to the oil and the oil-impregnated paper. In other words,
There was a voltage sharing phenomenon that conventional AC transformers did not have, and the insulation method was unlucky. In addition, lead 1 of the DC side winding 12
The same thing can be said about the insulated portion 17 in the drawer section 8. Insulating these portions 16, 17 becomes more difficult as the voltage increases. It was therefore necessary to eliminate these insulated parts 16,17.

The present invention has been made in consideration of the above points, and its purpose is to change the winding configuration so that it does not include parts that are difficult to insulate as in the past, thereby increasing the voltage. An object of the present invention is to provide an AC/DC converter transformer with excellent insulation stability.

[Structure of the invention]

(Means and effects for solving the problem) At least one of the AC side winding and the DC side winding to be wound around the iron core is formed by winding a sheet-like conductor and insulating paper, or the AC side One of the windings and the DC side winding is formed by winding a sheet-like conductor and insulating paper, and the corresponding other side is formed by winding a rectangular copper wire, and the AC side winding and the DC side winding are formed by winding a sheet-like conductor and insulating paper. By arranging the low potential sides of the wires to face each other, the potential difference between both windings is reduced, the complexity of the applied voltage waveform is eliminated, and the formation of elegant insulation spots is avoided. do.

(Embodiment) An embodiment of the AC/DC converter transformer of the present invention will be described below with reference to FIG. FIG. 1 is a longitudinal sectional view of a portion of the core and a portion of the winding. That is, a tertiary winding 11 is wound around a transformer iron core 10 formed by laminating electrical iron plates, an AC/current side winding 22 is further wound, and a DC side winding 23 connected to a thyristor valve is further wound. to form.

Further, electrostatic shields 20a, 20b; 2La, 21b are installed to set the end portions of the windings at the same potential and to alleviate the electric field. Further, an insulating barrier is provided between each winding to withstand the operating voltage and test voltage.

These are housed in the grounded tank 19 together with the insulating oil 26.

The AC side winding 22 and the DC side winding 23 described above are formed by winding sheet-like conductors and insulating paper in multiple layers. In this sheet-like winding, for example, the AC side winding 2
As shown in Figure 2, the inner circumferential surface can be connected to a Y-connected neutral point potential N, for example, a contact L (!! potential), and the outer circumferential surface can be a high voltage potential section.

Similarly, in the DC side winding 23, the inner peripheral surface can be set to a high potential portion, and the outer peripheral surface can be set to a neutral point potential N4, for example, a ground potential. In this state, almost no voltage is applied between the AC side winding 22 and the DC side winding 23. In other words, insulation against voltages (AC + DC), which was considered unlucky in the past, is almost unnecessary. Therefore, there are no areas where insulation is insecure.

In addition, by arranging the DC side winding 23 at the outermost periphery,
The potential wire 25 can be easily drawn out from the outermost side of the winding, and insulation only needs to be considered for the tank. The AC side winding 22 can be pulled out to the outside and the door 24 can be pulled out to the top. This kind of winding arrangement and lead extraction method is the third
This is a good idea for an AC/DC converter transformer 37 in an AC/DC converter station as shown in the figure.

In FIG. 3, the DC voltage is drawn outside through a through-wall bushing 29, a lightning arrester 30 and a blocking reactor 31 are provided, and a lead from the DC side winding of the AC/DC converter transformer 27 is connected to the thyristor valve 28 in the valve hole 34 through the bushing. Connected by bushing @32, bushing @3
3 connects the lead from the AC side winding to the AC system. As described above, considering the equipment arrangement shown in FIG. 3, it can be seen that the winding arrangement and lead extraction method of the present invention as shown in FIG. 1 can be carried out without difficulty.

Next, another embodiment of the present invention will be described with reference to FIG.

The same parts and parts having the same functions as those in FIG. 1 are given the same reference numerals. The AC side winding 22 is formed by multiple windings of a sheet-like conductor and insulating paper, and the DC side winding 23 is formed by winding a rectangular conducting wire into, for example, a disk shape.

In this configuration, by taking advantage of the features of the sheet-shaped winding, the side of the AC side winding 22 facing the DC side winding 23 is set to a neutral point potential N in a Y connection, for example, a ground potential, and the tertiary winding 1
The first side was made into a high voltage potential section. Further, the DC side winding 23 has a lead taken out from the center of the winding, that is, the center of the winding has the highest potential, and the lead is taken out from the side wall of the grounding tank 19. By arranging the windings in this way,
Insulation between the AC side winding 22 and the DC side winding 23 becomes easy.

For example, since substantially the same voltage is applied to the direct current side winding 23 between the drawing lines as that between the opposing tanks, the insulation between the windings can be performed in substantially the same manner as the tank insulation to the ground.

In this respect, in the past, complex voltages such as (AC + DC) voltages were added, and the insulation method had to be considered separately from that for tanks, and the insulation method was also difficult, leading to concerns about insulation. It had become.

In addition, the AC side winding is placed on the inside and the DC side winding is placed on the outside, and the leads of the outside DC side winding can be taken out from the center of the winding, so that it can be used as a transformer for AC/DC converters at AC/DC converting stations as shown in Figure 3. The container 37 has a convenient configuration as described above.

Furthermore, the DC side winding may be a sheet-like winding, and the AC side winding may be a disk winding using, for example, a rectangular copper wire. Furthermore, although insulating oil was specified as the insulating medium to be sealed in the tank above, SF, gas, or nitrogen gas may also be used.

〔Effect of the invention〕

As explained above, according to the present invention, the insulation method between the AC side winding and the DC side winding and around the leads from each winding becomes easy and reliable.

Thereby, it is possible to provide an AC/DC converter transformer with stable insulation.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a transformer for an AC/DC converter of the present invention, Fig. 2 is a sectional view of another embodiment of the invention, and Fig. 3 is a perspective view showing peripheral equipment of the transformer for an AC/DC converter of an AC/DC converting station. , FIG. 4 is a wiring diagram of a conventional AC/DC converter station, and FIG. 5 is a sectional view of a conventional AC/DC converter transformer. 19...Grounded tank. 20a, 20b; 21a, 21b - electrostatic shield,
22...AC side winding, 23...DC side winding.

Claims (4)

[Claims] (1) In an AC/DC converter transformer in which an AC side winding and a DC side winding are enclosed together with an insulating medium in a grounded tank, at least one of the AC side winding and the DC side winding is made of a sheet-like conductor. A transformer for an AC/DC converter, characterized in that it is formed by concentrically winding and insulating paper around an iron core. (2) The transformer for an AC/DC converter according to claim 1, wherein either the AC side winding or the DC side winding is formed by winding a rectangular copper wire. (3) The transformer for an AC/DC converter according to claim 1, wherein among the windings wound around the iron core, an AC side winding is arranged on the inside and a DC side winding is arranged on the outside. (4) The transformer for an AC/DC converter according to claim 1, wherein the AC side winding and the DC side winding are arranged so that their respective low potential sides are opposed to each other.