JP3032115B2 - Thyristor valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air-insulated thyristor valve used for DC power transmission and the like, and more particularly to an air-insulated thyristor valve improved in insulation of a column.

[0002]

2. Description of the Related Art Large-capacity, long-distance power transmission and inter-frequency connection, etc.
DC transmission, which has many advantages in system operation, is used in various fields. Currently, in Japan, the capacity is 300M
W, DC voltage up to 250 KV has been put into practical use, but further increase in capacity and voltage is expected in the future.

[0003] In the case of performing such DC power transmission, thyristors have been mainly used as semiconductor elements constituting a power converter for converting AC power to DC or vice versa. A semiconductor switch using a thyristor is called a thyristor valve. Here, a thyristor valve will be described as a typical example of a semiconductor valve. Recently, GTO thyristors have begun to be used, but the present invention can be applied to these.

In DC transmission, an AC / DC conversion station for converting AC into DC or DC into AC is installed. As shown in FIG. 5, the AC / DC converter converts the AC voltage from the AC system 6 into converter transformers 7a and 7b, a high-voltage converter 8a, and a low-voltage converter 8b.
To a DC voltage, and the DC power is transmitted through the DC reactor 10. Among them, the thyristor valve 9 constituting the high-side and low-side converters 8a and 8b is a main element for converting an AC voltage to a DC voltage or a DC voltage to an AC voltage as described above. From the viewpoint of maintenance and inspection, an air-insulated type is often used.
This air-insulated thyristor valve is installed in a building usually called a valve hole.

FIG. 6 shows the configuration of the thyristor valve 9.
In FIG. 6, an insulating support column 2 made of an organic insulator is connected to a metal beam 14 via a flange 1 by bolting or the like to form a frame. In order to reduce the electric field of the metal beam 14, shields 11 and 12 are attached to the upper and lower portions. Reference numeral 13 denotes a thyristor module containing a plurality of thyristor elements connected in series and parallel and their associated circuits such as a capacitor, a resistor, and a reactor. The thyristor module 13 is fixed to the insulating column 2 by an insulating support 3. Although the thyristor modules 13 stacked in a plurality of stages are electrically connected in series, the potential of each module 13 is fixed to the potential of one of the stored thyristors, ie, the potential of one of the thyristors. Generates a potential difference. Therefore, the interval S between the insulating supports 3 is determined as follows so as to withstand the applied voltage.

[0006]

S = U × E (1) Here, U is an applied voltage (KV), E is a design electric field (mm / KV) of creepage insulation determined by environmental conditions and the like, and generally 10
About 25 mm / KV. From this, the overall length L of the insulating support 2 can be obtained by equation (2).

[0007]

L = (N + 1) × S (2) where N is the number of stacking thyristor modules.

[0008]

L = (N + 1) × U × E (3) From the equation (3), if the applied voltage U increases, the insulating support L
And the height of the thyristor valve increases accordingly.

[0009]

At present, the DC power transmission record in Japan is up to 250 KV DC, and a corresponding thyristor valve has been produced by domestic manufacturers. Each of them is of the air insulation type as described above.

[0010] A DC voltage of 250 KV class has a height of about 10 m, and there is a concern that a 500 KV class DC power transmission realized in the near future will become a large device exceeding 20 m in height if manufactured as it is. This poses a serious problem in terms of seismic strength, and as the thyristor valve becomes larger, the size of the stored valve hole becomes larger. In Japan, which is an earthquake-prone country and has a narrow land area, further enlargement of the thyristor valve is expected to be an obstacle to promoting DC transmission.
Under such a background, reduction of the height of the thyristor valve is a current problem. An object of the present invention is to solve the above problems and to provide an air-insulated thyristor valve having high strength and high insulation reliability.

[0011]

According to the first aspect of the present invention, at least two insulating columns made of an organic insulating material are vertically arranged, and at least two metal beams are provided. An air insulation device comprising a plurality of semiconductor elements and modules accommodating the attached components, which are horizontally mounted on upper and lower portions of the insulating support column to form a frame, and are stacked in several stages at predetermined intervals between the insulating support columns. In the thyristor valve of the type, between the uppermost module and the upper metal beam, between the lowermost module and the lower metal beam, and the upper, middle, and lower portions of the insulating support between the modules. At least one shade is attached to each of the three locations.

According to a second aspect of the present invention, in the thyristor valve according to the first aspect, the shade attached to the upper portion of the insulating support is mounted below the lower surface of the module above the lower module. The shade is characterized by being arranged above the upper surface of the module below it.

Further, the invention according to claim 3 is the invention according to claim 1.
In the thyristor valve described in the above, when using a hollow insulating pillar as the insulating pillar, the opening of the hollow insulating pillar is sealed at the fastening part with the upper and lower metal beams. is there.

[0014]

According to the first aspect of the present invention, it is possible to increase the creepage insulation distance of the insulating support column by dispersing the shades at three positions between the electrodes of the insulating support column for insulatingly supporting the thyristor module, thereby enabling flashover. Since the voltage can be increased, the length of the insulating pillar can be shortened, and the height of the thyristor valve can be reduced.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the spatial distance between the tip of the cap and the thyristor module can be increased. The electric field at the tip and the end of the thyristor module can be reduced, and the occurrence of partial discharge can be prevented.

Further, according to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, there is a disadvantage that the inner surface of the insulating column is contaminated and flashover occurs on the inner surface of the insulating column 2. Can be prevented.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the block diagram of the thyristor valve shown in FIG.
Will be described. In FIG. 4, 4a, 4b,
Reference numeral 4c denotes a shade which is attached to the upper, central, and lower portions of the outer peripheral surface of the insulating support 2 two by two.

FIG. 2 shows an insulating post model having no cap and three kinds of caps, and FIG. 3 shows the results of testing the DC flashover voltage (FOV) of this model by changing the humidity. It is a support | pillar DC discharge characteristic diagram. When the shade is placed above, inside, or below, the flashover voltage hardly decreases even if the humidity increases, whereas when there is no shade or when the shade is not located above, middle, or below, the flashover increases with the humidity. It can be seen that the overvoltage has decreased.

As described above, by attaching the shade, the creepage insulation distance of the insulating pillar can be increased, and
Further, the flashover voltage in a fouling and high humidity state can be increased by dispersing and disposing the upper, middle, and lower portions.

Therefore, according to the first aspect of the present invention,
The height of the thyristor valve can be reduced, and the reliability of insulation can be improved. Reducing the height of the thyristor valve has the advantages of improving seismic performance, reducing the ceiling height of the valve hole, and simplifying maintenance and inspection as well as economic effects.

FIG. 4 is a partial structural view of a thyristor valve according to an embodiment of the present invention. FIG. 4 shows the same configuration as in the above-described embodiment, except that the mounting position of the upper fold 4a is below the lower surface of the thyristor module 9a, and the mounting position of the lower fold 4c is above the upper surface of the thyristor module 9b.

In this embodiment, since the spatial distance between the tip of the shade and the thyristor module can be increased, the electric field at the tip of the shade and the end of the thyristor module can be reduced, and partial discharge occurs. Can be prevented.

According to this embodiment, in addition to the effect of the first aspect,
It is possible to obtain an air-insulated thyristor valve in which electric field concentration hardly occurs and partial discharge hardly occurs. Next, the invention according to claim 3 will be described.

The insulating pillar is generally made of a hollow insulator in terms of material saving. According to the first aspect of the present invention, a creepage is provided on the surface of the insulating pillar to improve the creepage insulation properties, but no special insulation strengthening measures are taken on the inner surface of the hollow insulating pillar. If the creepage insulation of the insulator is not contaminated, the opening of the insulating column 2 is fastened at the joint between the flange 1 and the beam 14 shown in FIG. 1 so that the flashover voltage does not decrease even if the humidity increases. You can rub it tightly.

According to this embodiment, it is possible to prevent a problem that the inner surface of the insulating support 2 is soiled and a flashover occurs on the inner surface of the insulating support 2. Therefore, according to the present embodiment, a thyristor valve having high insulation reliability even in a dirty state can be obtained.

[0026]

As described above, according to the first aspect of the present invention, it is possible to increase the creeping insulation distance of the insulating support and to increase the flashover voltage. Thus, the height of the thyristor valve can be reduced. Further, since the height of the thyristor valve is reduced, the seismic strength is greatly improved, and maintenance exploration such as thyristor module replacement can be easily performed, which leads to improvement in reliability.

According to the second aspect of the present invention, in addition to the effect of the first aspect, the spatial distance between the tip of the cap and the thyristor module can be increased. The electric field at the end of the thyristor module can be reduced, and the occurrence of partial discharge can be prevented.

Further, according to the third aspect of the present invention, in addition to the effect of the first aspect of the present invention, it is possible to prevent a problem that the inner surface of the insulating column is soiled and a flashover occurs on the inner surface of the insulating column 2. Therefore, a thyristor valve with high insulation reliability can be obtained even in a dirty state.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a thyristor valve according to an embodiment of the present invention.

FIG. 2 is a model diagram of an insulating support column constituting the thyristor valve.

FIG. 3 is a characteristic diagram of humidity versus discharge voltage of the insulating support column of FIG.

FIG. 4 is a partial configuration diagram of a thyristor valve showing one embodiment of the invention described in claim 2;

FIG. 5 is a circuit diagram showing connection of an AC / DC conversion station.

FIG. 6 is a configuration diagram of a conventional thyristor valve.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Flange 2 ... Insulating pillar 3 ... Insulating support stand 4a ... Upper cap 4b ... Central cap 4c ... Lower cap 6 ... AC bus 7a ... Transformer for converter 8b ... Low-voltage transformer 13 ... Module 14 ... Beam

Claims (3)

(57) [Claims] At least two insulating posts made of an organic insulating material are vertically arranged, and at least two metal beams are horizontally mounted on upper and lower portions of the insulating posts to form a frame, and a plurality of semiconductors are provided. In an air-insulated thyristor valve configured by stacking several modules containing elements and their attached parts at predetermined intervals between the insulating columns, between the uppermost module and the upper metal beam, A thyristor valve, wherein at least one shade is attached to each of three places between the lowermost module and the lower metal beam and at the upper, middle and lower portions of the insulating support between the modules. . 2. The shade mounted on the upper part of the insulating support post is arranged below the lower surface of the module on the upper side thereof, and the shade mounted on the lower part of the insulating support pillar is arranged above the upper surface of the module on the lower side thereof. The thyristor valve according to claim 1, wherein Wherein the insulating support rod der of the insulating struts hollow structure
Ri, characterized by sealing the opening portion of the hollow insulating support rod at the upper and the fastening portion of the lower metallic beam
The thyristor valve according to claim 1 .