JPH10172835A - Transformer for gas-insulated transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the electric field concentration on a gas part in a duct piece by setting the insulation resistance of the duct piece to a higher value than that of an insulation tube. SOLUTION: Windings 22, 23 and insulation tubes 27a, 27b are concentrically disposed. Duct pieces 30a, 30b are disposed between an a.c. winding 22 and insulation tube 27a, and between the insulation tube 27a and d.c. winding 23. respectively. The duct pieces 30a, 30b, 30c are disposed at equal spacings and offset in the circumferential directions of the windings 22, 23 and have insulation resistances set to higher values than that of the insulation tubes 27a, 27b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transformer for an AC / DC converter used for DC transmission, and more particularly to a transformer for a gas-insulated converter in which a solid insulator between windings to which a DC voltage is applied inside the transformer is improved. It is about.

[0002]

2. Description of the Related Art In recent years, DC power transmission has been used in various fields, and in some areas, 250 kV DC power transmission in which a system is linked is implemented. This is because DC power transmission has many advantages in system operation, such as large capacity, long-distance power transmission, and different frequency linkage. For such DC transmission, an AC / DC conversion station for converting AC to DC or DC to AC is indispensable. About this AC / DC conversion station,
This will be specifically described with reference to the wiring diagram of FIG.

[AC-DC converter] As shown in FIG. 9, an AC-DC converter, an AC line 1, conversion transformers 2a and 2b, thyristor valve groups 3a and 3b, a DC reactor 4 and a DC line 5 are sequentially connected to the AC-DC converter. It is provided. Among these components, the thyristor valves 6a and 6b forming the thyristor valve groups 3a and 3b are main components for converting an AC voltage to a DC voltage or a DC voltage to an AC voltage. At present, the thyristor valves 6a and 6b are generally of an air-insulated type in view of operation results, maintenance and inspection, and the thyristor valves 6a and 6b of this type are generally used.
6b is normally stored in a building called a valve hole 7 (shown by a two-dot chain line in FIG. 9). In FIG. 9, reference numerals 8a and 8b denote lightning arresters for transformers, 9 denotes lightning arresters for DC reactors, and 10 denotes A- of thyristor valve groups 3a and 3b.
It is a lightning arrester between K.

In FIG. 10, the thyristor valve 6 described above is used.
a, 6b, valve hole 7 and transformer 2a, 2
The example of arrangement | positioning of b etc. is shown. As shown in this figure, the AC line 1 and the transformers 2a, 2b for the converter are arranged close to the valve hole 7, and the valve hole 7
Thyristor valves 6a and 6b, lightning arrester 9 for DC reactor, and DC bushing 12 are housed therein.
Further, a wall-piercing bushing 11 is provided on the wall surface of the valve hole 7, and the thyristor valves 6a, 6b and the transformers 2a, 2b for the converter are connected via the wall-piercing bushing 11. Although not shown in FIG. 12, the DC reactor 4 connected to the DC line 5 is installed outside the valve hole 7 and is connected to the DC bushing 12 in the valve hole 7.

In the AC / DC converter having the above-described configuration, the converter transformers 2a and 2b receive an AC voltage from the AC line 1 and adjust the voltage to an appropriate voltage. The converter transformers 2a and 2b send the adjusted voltage to the thyristor valves 6a and 6b via the through-wall bushing 11. The thyristor valves 6 a and 6 b convert an AC voltage into a DC voltage and send the DC voltage to the DC line 5 via the DC bushing 12 and the DC reactor 4.

[Transformer for Oil-Insulated Converter] As an insulation method for the transformers 2a and 2b for the converter, an oil-insulated method is widely known. Since a DC voltage is applied to this transformer for an oil-insulated converter at the time of operation and a factory test, an insulation design different from an insulation design for an AC voltage is made. That is, the oil insulation system has a composite insulation structure using insulating oil and a solid insulator such as a press board. When a DC voltage is applied to a transformer for an oil-insulated converter having such a configuration, a large voltage is applied to a solid insulator having a large insulation resistance, and a small voltage is not applied to an insulation oil having a small insulation resistance. . Therefore, the transformer for an oil-insulated converter is designed and manufactured by devising the arrangement of the solid insulator so that a voltage applicable to both the solid insulator and the insulating oil is applied.

[Transformers for Gas-Insulated Converters] The transformers for oil-insulated converters as described above have been operated and are widely used at present. However, in recent years, transformers for oil-insulated converters have been used for disaster prevention reasons. As an alternative transformer for a gas transformer, a transformer for a gas-insulated converter using a nonflammable insulating gas as an insulating medium has been attracting attention. This gas-insulated converter transformer basically replaces the insulating medium and cooling medium with insulating gas from insulating oil, and its winding configuration is almost the same as that of the conventional oil-insulated converter transformer. As described above, a winding obtained by superposing and winding a polymer insulating film on a conductor wire is used.

Here, a transformer for a gas-insulated converter will be described.
This will be specifically described with reference to FIGS. FIG.
Is a sectional view of the inside of the transformer, and FIG. 12 is a plan view of a winding portion. As shown in FIG. 11, a container 21 (shown by a dashed line in FIG. 11) is filled with an insulating gas 26, and an AC winding 22 connected to an AC line and a DC winding connected to a thyristor valve. The wire 23 is housed. In FIG. 11, reference numeral 27 denotes an insulating cylinder, 28 denotes a duct collar, 29
Indicates an insulating region between the windings 22 and 23. The insulating region 29 is composed of an insulating gas 26 and a solid insulator composed of an insulating cylinder 27 and a duct piece 30 described later.

As shown in FIG. 12, the windings 22, 23 and the insulating cylinder 27 are arranged concentrically. Insulation tube 27
Is the winding 2 when the insulation distance between the windings 22 and 23 is large.
It is provided between 2 and 23. Also, the insulating cylinder 27
A plurality of duct pieces 30 are provided so as to support.

[0010] These duct pieces 30 are wound with windings 22 and 23.
Are arranged at equal intervals in the circumferential direction and in a straight line along the radial direction of the windings 22 and 23, and are formed of an insulator having a square cross section. Further, since the duct piece 30 is arranged so as to sandwich the insulating cylinder 27, the radial dimension (thickness) is shorter than the width dimension. For this reason, the duct piece 30 has high stability and is hard to fall down even if an impact is applied. Such a duct piece 30 secures an insulation distance between the windings 22 and 23 and prevents displacement and deformation of the windings 22 and 23 caused by an impact load during transportation and a short-circuit mechanical force generated during a short-circuit accident. can do.

When an AC voltage is applied to the transformer for a gas-insulated converter, both the insulating gas 26 and the solid insulator (the insulating cylinder 27 and the duct piece 30) are present in the insulating region 29 between the windings 22 and 23. Therefore, the potential is not equally shared between the insulating gas 26 and the solid insulator, and a larger potential difference is generated in the smaller relative dielectric separation.

By the way, while the duct piece 30 has a rectangular cross section, the windings 23 and 22 and the insulating cylinder 27
Is circular. Therefore, the duct piece 30 and the winding 2
A small gap is formed at the portion where the insulating piece 27 is in contact with the duct piece 30 or the duct piece 30, and a wedge gap is generated here. A large electric field is applied to the wedge gap by an amount corresponding to the relative permittivity, resulting in a decrease in dielectric strength. Therefore, as disclosed in Japanese Patent Application Laid-Open No. 2-284219, there is proposed a transformer for a gas-insulated converter in which a notch is formed in a duct piece 30 and the notch is used as an insulating gas space to reduce an electric field in a wedge gap portion. (Figure 1
3).

[0013]

In the transformer for a gas-insulated converter, not only the case where the AC voltage is applied as described above, but also the case where the DC winding is applied to the DC winding 23 and the AC winding 22 is grounded during the factory test. In some cases, a DC voltage is applied. When such a DC voltage is applied, the following problem occurs.

That is, the insulation resistance of the insulating gas 26 is much larger than the insulation resistance of the insulating cylinder 27 and the duct piece 30 which are solid insulators. Therefore, the windings 22, 2
When a DC voltage is applied in series between the three, a large voltage is applied to the insulating gas 26 having a large insulation resistance, and a small voltage is not applied to the insulating cylinder 27 and the duct piece 30 having a small insulation resistance. Therefore, the windings 22, 23
When a DC voltage is applied in parallel between them, the potential sharing is determined by the insulation resistance of the insulating cylinder 27 and the duct piece 30 which are solid insulators. This will be described in detail below using the potential distribution diagram shown in FIG.

That is, in the vicinity of the duct piece 30 having a small insulation resistance (shown by a thick line in FIG. 14), the equipotential line 39 is shown.
Is pushed out to the insulating gas 26 side and becomes "sparse",
The equipotential line 39 is "dense" in the portion of the insulating gas 26 having a large insulation resistance. At this time, the equipotential lines 39 extruded from the vicinity of the duct piece 30 to the insulating gas 26 side are as follows:
Although it enters obliquely into the duct piece 30, this means that an electric field is applied to the duct piece 30 from an oblique direction. Since pressure is applied in the thickness direction of the duct piece 30 due to its function, if an electric field is applied in an oblique direction, the dielectric strength of the duct piece 30 may be reduced.

The equipotential lines 39 pushed out from the vicinity of the duct piece 30 toward the insulating gas 26 cross the insulating cylinder 27 located between the duct pieces 30. That is, the equipotential lines 39 are perpendicular to the creeping direction of the insulating cylinder 27.
And an electric field is applied in the surface direction of the insulating cylinder 27. The potential shared in the creeping direction of the insulating cylinder 27 is the sharing of the insulation resistance in the thickness direction (vertical direction in FIG. 14) of the duct piece 30 and the insulation resistance in the circumferential direction (horizontal direction in FIG. 14) of the insulating cylinder 27. It will be largely decided.

Normally, the duct piece 30 has a wide shape because it is attached for the purpose of preventing the windings 22 and 23 from being deformed or displaced by the mechanical force generated during transportation of the transformer. The insulation resistance in the thickness direction of the duct piece 30 is relatively small. On the other hand, since the insulating cylinder 27 is formed thin by bending a laminated product on a straight line or winding a layer on a cylinder, the insulation resistance of the insulating cylinder 27 in the circumferential direction is equal to the insulation resistance of the duct piece 30. It is larger than. Since the DC voltage is shared by a large portion of the insulation resistance, in the current configuration, most of the DC voltage is shared in the circumferential direction of the insulating cylinder 27, which is a weak point in insulation.

Further, there has been proposed a transformer for a gas-insulated converter in which an AC winding 22 and a DC winding 23 are vertically arranged, and a duct collar 28 is arranged therebetween. In such a transformer for a gas-insulated converter, the duct collar 28
The electric field at the creeping portion of the surface became large, and this was a weak point on insulation.

The phenomenon that the electric field at the creeping portion of the insulating cylinder 27 or the duct collar 28 as described above is large is a phenomenon peculiar to the application of a DC voltage, and does not occur significantly when an AC voltage is applied. That is, when an AC voltage is applied, the relative permittivity ε0 of the gas portion 26 and the insulating cylinder 42 is ε0 = 1.0 and ε0 = 3.2, respectively, and the ratio between the two is small. Absent.

The present invention has been proposed to solve the above problems, and its main object is to improve the resistance and configuration of a duct piece between windings so that a DC voltage can be reduced. It is an object of the present invention to provide a transformer for a gas-insulated converter in which the potential distribution between the windings is improved to maintain the insulation strength when an AC voltage is applied, while improving the insulation strength when a DC voltage is applied.

More specifically, an object of the present invention is to add more potential sharing between the concentrically arranged AC winding and the DC winding to the duct piece than to the insulating cylinder between the windings. Therefore, the object is to improve insulation strength against a DC voltage.

It is an object of the present invention to improve the insulation strength against a DC voltage by leveling the potential distribution between the windings for each insulating cylinder.

It is an object of the present invention to improve the insulation strength against an AC voltage and the insulation strength against a DC voltage by eliminating a wedge gap generated between the insulating cylinder and the duct piece.

A sixth object of the present invention is to provide an insulation strength against a DC voltage by applying a higher potential distribution between an AC winding and a DC winding arranged vertically to a duct piece than a duct collar between the windings. Is to improve.

An object of the present invention is to improve the insulation strength against a DC voltage by leveling the potential distribution between windings for each duct collar.

An object of claims 8 to 10 is to improve insulation strength against an AC voltage and insulation strength against a DC voltage by eliminating a wedge gap generated between a duct collar and a duct piece.

[0027]

According to a first aspect of the present invention, there is provided a transformer for a gas-insulated converter, wherein an AC winding and a thyristor are connected to an AC line in a container filled with an insulating gas. A DC winding connected to the valve is housed concentrically, and between the AC winding and the DC winding, a plurality of insulating cylinders are provided on the winding and concentric circles to support the insulating cylinder. In the transformer for a gas-insulated converter in which a plurality of duct pieces are arranged as described above, the insulation resistivity of the duct pieces is set higher than the insulation resistivity of the insulating cylinder.

According to the first aspect of the present invention, the insulation resistance of the duct piece is made higher than the insulation resistance of the insulation cylinder, so that the direct current voltage between the windings is greatly applied to the duct piece, and the insulation cylinder has an insulation resistance. Join less. Therefore, equipotential lines between the AC winding and the DC winding draw concentric circles with the winding, and the electric field does not concentrate on the surface of the insulating cylinder. Therefore, the insulation strength against a DC voltage can be increased without reducing the thickness or width of the duct piece or increasing the thickness of the insulating cylinder.

In the transformer for a gas-insulated converter according to the present invention, an AC winding connected to an AC line and a DC winding connected to a thyristor valve are concentrically housed in a container filled with insulating gas. A plurality of insulating cylinders are provided between the AC winding and the DC winding on a circle concentric with the winding, and a plurality of duct pieces are arranged to support the insulating cylinder. In a dexterous transformer, the insulation resistivity of the duct piece sandwiched between adjacent insulating cylinders,
The insulation resistance of the duct piece sandwiched between the insulating cylinder and one of the windings is all set to be uniform.

According to the second aspect of the invention, the insulation resistance of the duct piece sandwiched between adjacent insulating cylinders and the insulation resistance of the duct piece sandwiched between the insulating cylinder and one of the windings are set. Since the resistivity is all uniform, the electric field between the insulating cylinders can be leveled. As a result, the electric field does not concentrate only on a part between the insulating cylinders, and the insulation strength against a DC voltage can be increased.

According to a third aspect of the present invention, there is provided the gas insulated converter transformer according to the first or second aspect, wherein an elastic insulator is attached to an end face of the duct piece.

According to the third aspect of the present invention, since the elastic insulator is attached to the end face of the duct piece, a gap is formed between the duct piece and the insulating cylinder and between the duct piece and the winding. And the occurrence of a wedge gap can be prevented. Therefore, it is possible to prevent electric field concentration when applying a DC voltage and an AC voltage.

According to a fourth aspect of the present invention, in the transformer for a gas-insulated converter according to the third aspect, the insulation resistivity of the elastic insulator is set to be lower than the insulation resistivity of the duct piece. It is characterized by having been done.

According to the fourth aspect of the present invention, since the insulation resistivity of the elastic insulator is lower than that of the duct piece, a wedge gap generated at the end face of the duct piece can be prevented, and at the same time, the elastic insulator can be prevented. It is possible to prevent electric field concentration on the substrate.

According to a fifth aspect of the present invention, there is provided the transformer for a gas-insulated converter according to the first, second, third or fourth aspect, wherein a foam insulator is attached to an end face of the duct piece. Features.

In the fifth aspect of the present invention, since the foam insulator is attached to the end face of the duct piece, a wedge gap generated between the duct piece and the insulating cylinder and between the duct piece and the winding is formed. It can be subdivided. Thereby, DC and AC breakdown electric fields can be improved.

According to a sixth aspect of the present invention, in the transformer for a gas-insulated converter, an AC winding connected to an AC line and a DC winding connected to a thyristor valve are vertically arranged in a container filled with insulating gas. A plurality of duct collars are provided vertically between the AC winding and the DC winding, and a plurality of duct pieces are arranged to support the duct collar. In the dexterous transformer, the insulation resistance of the duct piece is set higher than the insulation resistance of the duct collar.

According to the sixth aspect of the invention, since the insulation resistance of the duct piece is made higher than the insulation resistance of the duct collar, the DC voltage between the windings is largely applied to the duct piece, and the duct collar is applied to the duct collar. Join less. Therefore, the equipotential line between the AC winding and the DC winding is substantially perpendicular to the axis of the winding, and the electric field does not concentrate on the surface of the duct collar. Therefore, the insulation strength against a DC voltage can be increased without reducing the thickness or width of the duct piece or increasing the thickness of the insulating cylinder.

In the transformer for a gas-insulated converter according to the present invention, an AC winding connected to an AC line and a DC winding connected to a thyristor valve are vertically arranged in a container filled with insulating gas. A plurality of duct collars are provided vertically between the AC winding and the DC winding, and a plurality of duct pieces are arranged to support the duct collar. In the dexterous transformer, the insulation resistivity of the duct piece sandwiched between adjacent duct collars, and the insulation resistivity of the duct piece sandwiched between the duct collar and one of the windings are all uniform. It is characterized by having been set.

According to the present invention, the insulation resistivity of the duct piece sandwiched between the adjacent duct collars and the insulation resistivity of the duct piece sandwiched between the duct collar and one of the windings are set. Are all uniform,
The electric field between the duct collars can be leveled.
As a result, the electric field does not concentrate only on a part between the duct collars, and the insulation strength against a DC voltage can be increased.

According to an eighth aspect of the present invention, there is provided the transformer for a gas-insulated converter according to the sixth or seventh aspect, wherein an elastic insulator is attached to an end face of the duct piece.

According to the eighth aspect of the present invention, since the elastic insulator is attached to the end face of the duct piece, a gap is formed between the duct piece and the duct collar and between the duct piece and the winding. As in the third aspect of the present invention, wedge gaps can be prevented from being generated, and electric field concentration can be prevented when a DC voltage and an AC voltage are applied.

According to a ninth aspect of the present invention, in the transformer for a gas-insulated converter according to the eighth aspect, the insulation resistivity of the elastic insulator is set to be lower than the insulation resistivity of the duct piece. It is characterized by having been done.

According to the ninth aspect of the present invention, similarly to the fourth aspect of the present invention, it is possible to prevent wedge gaps at the end face of the duct piece and to prevent electric field concentration on the elastic insulator.

A transformer for a gas-insulated converter according to claim 10 is
The transformer for a gas-insulated converter according to claim 6, 7, 8, or 9, wherein a foam insulator is attached to an end face of the duct piece.

According to the tenth aspect of the present invention, the wedge gap generated between the duct piece and the duct collar and between the duct piece and the winding can be subdivided by the foam insulator. As in the fifth aspect of the present invention, DC and AC breakdown electric fields can be improved.

[0047]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a transformer for a gas-insulated converter according to the present invention will be specifically described below with reference to FIGS. Note that the same members as those in the conventional example are denoted by the same reference numerals, and description thereof will be omitted.

(1) First Embodiment [Configuration] The first embodiment corresponds to claim 1 of the transformer for a gas insulated converter according to the present invention. FIG. 1 is a plan view of a winding portion of the first embodiment.

As shown in FIG. 1, the windings 22, 23 and the insulating cylinders 27a, 27b are arranged concentrically. A duct piece 30a is provided in a gap between the AC winding 22 and the insulating tube 27a, a duct piece 30b is provided in a gap between the insulating tube 27a and the insulating tube 27b, and a duct piece 30c is provided in a gap between the insulating tube 27b and the DC winding 23. Are arranged respectively. Each of the duct pieces 30a, 30b, 30c is arranged at regular intervals in the circumferential direction of the windings 22, 23 and shifted in the circumferential direction between the insulating cylinders 27a, 27b.

The insulation resistivity of the duct pieces 30a to 30c is set higher than the insulation resistivity of the insulating cylinders 27a and 27b. Specifically, the insulating cylinders 27a and 27b are made of a kraft pulp press board, and the duct pieces 30a to 30c are made of an aramid fiber mixed board or PTFE.
And a press board made of PFA.

The insulation resistance of the insulation gas 26 is much higher than the insulation resistance of the duct pieces 30a to 30c and the insulation cylinders 27a and 27b. For this reason, considering the resistance distribution in the configuration corresponding to FIG. 1, it is as shown in FIG. 2. In considering the resistance distribution of the duct pieces 30 a to 30 c and the insulating cylinders 27 a and 27 b, the insulating gas 26 is ignored. can do.

[Function and Effect] In the first embodiment, the insulation resistance of the duct pieces 30a to 30c is higher than the insulation resistance of the insulating cylinders 27a and 27b.
The sharing of the DC voltage of 2, 23 is performed by the duct pieces 30a to 30.
c and a small amount to the insulating cylinders 27a and 27b. Therefore, as shown in FIG. 3, the equipotential line 39 between the AC winding 22 and the DC winding 23 is
Concentric circles 2 and 23 are drawn. That is, the equipotential lines 39 correspond to the duct pieces 30a, 30b (FIG. 3).
(Indicated by a bold line in FIG. 3), it is no longer pushed out to the insulating gas 26 side, and an electric field is applied to the duct pieces 30a, 30b in the thickness direction (vertical direction in FIG. 3). Therefore, there is no possibility that the dielectric strength of the duct pieces 30a and 30b is reduced as compared with the case where an electric field is applied from an oblique direction.

Further, since the equipotential lines 39 crossing the insulating cylinders 27a and 27b are reduced, the electric field is reduced along the surface of the insulating cylinders 27a and 27b, so that electric field concentration does not occur. Thereby, the insulation strength against a DC voltage can be increased without changing the shapes and dimensions of the duct pieces 30a to 30c and the insulating cylinders 27a and 27b.

In the above description, the press cylinder is limited to the insulating cylinder. However, the press board is only one kind of the material of the insulating cylinder, and is an insulating material having two different insulation resistances. Insulation tubes with low insulation resistivity
Similar effects can be obtained by using a duct piece having a high insulation resistivity.

(2) Second Embodiment [Configuration] Next, a second embodiment of the transformer for a gas-insulated converter according to the present invention will be described with reference to FIG. As shown in the drawing, in the second embodiment, the duct pieces 30a, 30b, and 30c are provided with the cutout portions 31 so that the duct pieces 30b and the insulating cylinders sandwiched between the adjacent insulating cylinders 27a and 27b are provided. Duct piece 30a sandwiched between the AC winding 22 and the insulating cylinder 2
The insulation resistances of the duct piece 30c sandwiched between the DC winding 7b and the DC winding 23 are all set to be uniform.

[Operation and Effect] In the second embodiment, since the duct pieces 30a to 30c all have the same insulation resistivity, the electric field between the insulation cylinders 27a and 27b can be leveled. Thereby, the insulating cylinder 27a, 2
The electric field is not concentrated only in a part between the electrodes 7b, and the insulation strength against a DC voltage can be increased.

In the above description, the notch 31 is formed in the duct pieces 30a to 30c to
Although the configuration is such that the insulation resistance between a and 27b is adjusted, the function and effect do not change even if the cross-section of the duct pieces 30a to 30c is enlarged or an insulator having a different insulation resistance is combined.

(3) Third Embodiment [Configuration] A third embodiment corresponds to claim 4 of the transformer for a gas-insulated converter according to the present invention. As shown in FIG. 5, in the third embodiment, duct pieces 30a to 30c are attached to end faces of duct pieces 30a to 30c made of PTFE.
EP rubber 4 having an insulation resistivity lower than the insulation resistivity of c
3 is attached.

[Effects] In the third embodiment, the wedge gaps are formed by the duct pieces 30a to 30a.
c and the insulating cylinders 27a and 27b or the windings 22 and 23, and since the insulation resistance of the EP rubber 43 is lower than that of the duct pieces 30a to 30c, a large electric field is applied to the EP rubber 43. Will not join.
Therefore, a transformer for a gas-insulated converter having excellent insulation strength against AC voltage and insulation strength against DC voltage can be obtained.

In the above description, the duct piece is limited to PTFE and the elastic insulator is limited to EP rubber. However, PTFE and EP rubber are only one kind of insulating material, and the insulation resistance of the duct piece is limited. Regardless of the rate, the gas gap can be eliminated by attaching any elastic insulator to the duct piece, and the effect of improving the insulation properties against DC voltage remains unchanged.

In place of the EP rubber 43, PT
If you attach a foam insulator such as FE foam, silicone foam, polyurethane foam or epoxy foam,
A transformer for a gas-insulated converter according to claim 5 of the present invention can be obtained. According to such a transformer for a gas-insulated converter, the wedge gap generated between the duct piece and the insulating cylinder and between the duct piece and the winding can be subdivided, and the DC and AC breakdown electric fields can be reduced. Can be improved.

(4) Fourth Embodiment [Structure] FIG. 6 is a diagram showing a fourth embodiment of a transformer for a gas-insulated converter according to the present invention.
As shown in the figure, in the fourth embodiment, an AC winding 22 and a DC winding 23 are housed side by side in the vertical direction, and a plurality of duct collars 28a and 28b are interposed between the windings 22 and 23 in the vertical direction. Are provided side by side, and the duct piece 30a
The insulation resistance of the duct collars 28a, 28b
Is set to be higher than the insulation resistivity.

[Operation and Effect] In the fourth embodiment, the insulation resistance of the duct pieces 30a to 30c is higher than the insulation resistance of the duct collars 28a and 28b. Duty piece 30a
~ 30c, and the duct collars 28a, 28b
Will be added less. Therefore, between the windings 22,
Since the equipotential lines 23 are almost linear, the concentration of the electric field does not occur.

The distribution of the equipotential lines is the same as that described with reference to FIG. 3, and the places of the insulating cylinders 27a and 27b are replaced with duct collars 28a and 28b.
That is. Again, the number of equipotential lines 39 crossing the duct collars 28a, 28b is reduced,
The creeping electric field of 28b can be reduced, and the insulation strength can be improved.

In the above description, the duct collar is limited to the press board. However, the press board is only one kind of the duct collar material, and is made of an insulating material having two different resistivity. The effect is not changed by using a duct with a low resistivity for the duct collar and a duct with a high resistivity for the duct piece.

(5) Fifth Embodiment [Structure] Next, a fifth embodiment of the transformer for a gas-insulated converter according to the present invention will be described with reference to FIG. This embodiment is a combination of the fourth embodiment with the second embodiment.
Notches 31 are provided in a, 30b, and 30c so that the insulation resistance of all duct pieces 30a to 30c is set to be uniform.

[Effect] In the fifth embodiment, the electric field between the duct collars 28a and 28b is leveled and the electric field does not concentrate on only a part of the duct collars 28a and 28b. Similarly, the insulation strength against a DC voltage can be increased.

In the above description, the notch 31 is inserted into the duct pieces 30a to 30c so that the duct collar 2
Although the configuration in which the insulation resistance between 8a and 28b is adjusted is adopted, the function and effect do not change even if the cross-section of the duct pieces 30a to 30c is increased or a combination of insulators having different insulation resistances is used.

(6) Sixth Embodiment [Structure] The sixth embodiment corresponds to claim 9 of the transformer for a gas-insulated converter according to the present invention. In this embodiment, the third embodiment is combined with the fourth embodiment. As shown in FIG. 8, duct pieces 30a to 30c are provided on the end faces of duct pieces 30a to 30c.
EP having an insulation resistivity lower than that of ３０30c
It is characterized in that rubber 43 is attached.

[Effects] In the sixth embodiment, the wedge gaps are formed by the duct pieces 30a to 30a.
c and duct collars 28a, 28b or windings 22, 23
A large electric field is not applied to the EP rubber 43 since the insulation resistance of the EP rubber 43 is lower than that of the duct pieces 30a to 30c. Therefore, similarly to the third embodiment, it is possible to obtain a transformer for a gas-insulated converter having excellent insulation strength against an AC voltage and excellent insulation strength against a DC voltage.

In the above description, the duct piece is limited to PTFE and the elastic insulator is limited to EP rubber. However, PTFE and EP rubber are only one kind of insulating material, and the insulation resistance of the duct piece is limited. Regardless of the rate, the gas gap can be eliminated by attaching any elastic insulator to the duct piece, and the effect of improving the insulation properties against DC voltage remains unchanged.

In place of the EP rubber 43, PT
If you attach a foam insulator such as FE foam, silicone foam, polyurethane foam or epoxy foam,
A transformer for a gas-insulated converter according to claim 10 of the present invention can be obtained. According to such a transformer for a gas-insulated converter, the wedge gap generated between the duct piece and the insulating cylinder and between the duct piece and the winding can be subdivided, and the DC and AC breakdown electric fields can be reduced. Can be improved.

[0073]

As described above, according to the present invention,
With a simple configuration that sets the insulation resistance of the duct piece higher than the insulation resistance of the insulation cylinder or duct collar between windings, the electric field in the creepage direction of the insulation cylinder or duct collar between windings is reduced. Since the electric field can be prevented from being concentrated on the gas portion of the duct piece portion, a transformer for a gas-insulated converter having high insulation strength against a DC voltage can be provided.

[Brief description of the drawings]

FIG. 1 is a plan view of a winding portion in a first embodiment of a transformer for a gas-insulated converter according to the present invention.

FIG. 2 is a diagram showing a resistance distribution of the transformer for a gas-insulated converter shown in FIG. 1;

FIG. 3 is a potential distribution diagram of a winding portion according to the first embodiment.

FIG. 4 is a side view of a main part of a winding part of a transformer for a gas-insulated converter according to a second embodiment of the present invention.

FIG. 5 is a plan view of a winding part in a third embodiment of the transformer for a gas-insulated converter according to the present invention.

FIG. 6 is a side view of a winding portion of a transformer for a gas-insulated converter according to a fourth embodiment of the present invention.

FIG. 7 is a side view of a winding portion in a fifth embodiment of the transformer for a gas-insulated converter according to the present invention.

FIG. 8 is a side view of a winding portion of a transformer for a gas-insulated converter according to a sixth embodiment of the present invention.

FIG. 9 is a wiring diagram of a general AC / DC converter station.

FIG. 10 is a bird view showing an example of the arrangement inside and outside the valve hole of FIG. 9;

FIG. 11 is a sectional view showing an example of an insulating configuration inside a transformer for a gas-insulated converter.

FIG. 12 is a plan view of a winding portion in the transformer for a gas-insulated converter shown in FIG. 11;

FIG. 13 is a plan view of a winding portion in a conventional transformer for a gas-insulated converter.

FIG. 14 is a potential distribution diagram of a winding part in a conventional transformer for a gas-insulated converter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... AC line 2a, 2b ... Transformer transformer 3a, 3b ... Thyristor valve group 4 ... DC reactor 5 ... DC line 6a, 6b ... Thyristor valve 7 ... Valve hole 11 ... Waneki bushing 12 ... DC bushing 20 ... Iron core 21 ... tank 22 ... AC winding 23 ... DC winding 26 ... insulating gas 27, 27a, 27b ... insulating cylinder 28, 28a, 28b ... duct collar 29 ... insulating area 30, 30a, 30b, 30c ... duct piece 31 ... notch 39: Equipotential line 40: Resistance of insulating cylinder 41: Resistance of duct piece 43: EP rubber

Claims (10)

[Claims] An AC winding connected to an AC line and a DC winding connected to a thyristor valve are concentrically housed in a container filled with an insulating gas. A plurality of insulating cylinders are provided between the windings on a concentric circle, and a plurality of duct pieces are arranged so as to support the insulating cylinder. A transformer for a gas-insulated converter, wherein the resistivity is set higher than the insulation resistivity of the insulating cylinder. 2. An AC winding connected to an AC line and a DC winding connected to a thyristor valve are concentrically housed in a container filled with an insulating gas. A plurality of insulating cylinders are provided concentrically with the winding, and a plurality of duct pieces are arranged so as to support the insulating cylinder. Gas insulation characterized in that the insulation resistivity of the duct piece sandwiched between them, and the insulation resistivity of the duct piece sandwiched between the insulating cylinder and one of the windings are all set uniformly. Transformer transformer. 3. The transformer for a gas-insulated converter according to claim 1, wherein an elastic insulator is attached to an end face of the duct piece. 4. The transformer for a gas-insulated converter according to claim 3, wherein the insulation resistivity of the elastic insulator is set lower than the insulation resistivity of the duct piece. 5. The transformer for a gas-insulated converter according to claim 1, wherein a foam insulator is attached to an end face of the duct piece. 6. An AC winding connected to an AC line and a DC winding connected to a thyristor valve are housed in a container filled with an insulating gas in a vertical direction. A plurality of duct collars are provided between the windings in the vertical direction, and a plurality of duct pieces are arranged so as to support the duct collar. A transformer for a gas-insulated converter, wherein a resistivity is set higher than an insulation resistivity of the duct collar. 7. An AC winding connected to an AC line and a DC winding connected to a thyristor valve are housed in a container filled with an insulating gas in a vertical direction. A plurality of duct collars are provided between the windings in the vertical direction, and a plurality of duct pieces are arranged so as to support the duct collars. The insulation resistivity of the duct piece sandwiched between each other, and the insulation resistivity of the duct piece sandwiched between the duct collar and one of the windings,
A transformer for a gas-insulated converter, wherein the transformers are all set uniformly. 8. The transformer for a gas-insulated converter according to claim 6, wherein an elastic insulator is attached to an end face of the duct piece. 9. The transformer for a gas-insulated converter according to claim 8, wherein the insulation resistivity of the elastic insulator is set lower than the insulation resistivity of the duct piece. 10. The transformer for a gas-insulated converter according to claim 6, wherein a foam insulator is attached to an end face of the duct piece.