JP2007088274A - Gas-insulated transformer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gas-insulated transformer which can prevent an SF<SB>6</SB>gas from contributing to global warming by reducing a usage rate and an exhaust rate of the SF<SB>6</SB>gas, and can be positively connected to a gas-insulated switchgear while ensuring excellent insulating performance. <P>SOLUTION: An insulation spacer 31 is attached on a tank 7, and an intermediate gas conduit 33 is attached on the insulation spacer 31. The intermediate gas conduit 33 is connected to the gas insulated switchgear (not shown) on a side opposite to the tank 7. The intermediate gas conduit 33 is shaped so that its dimension is gradually reduced, and a second insulation spacer 32 having hermeticity is attached on a dimension-changing portion on the intermediate portion of the intermediate gas conduit 33. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an environment-friendly gas-insulated transformer, and more particularly to a gas-insulated transformer having an improved connection with a gas-insulated switchgear.

  Conventionally, gas-insulated transformers in which an insulating gas is sealed in a tank and used as an insulating medium and a cooling medium have been proposed. There are 275 kV and 300 MV transformers as ultra-high voltage and large capacitors, and there are small and medium capacitors used in the basement of buildings and the like of the voltage 60 kV class. Here, the conventional gas-insulated transformer described in Patent Document 1 will be specifically described with reference to FIG. FIG. 2 is a cross-sectional view showing an example of the internal configuration of the gas-insulated transformer.

  As shown in FIG. 2, the gas-insulated transformer 10 includes a transformer main body 16 configured by winding a low-voltage winding 12, an intermediate-voltage winding 13, a high-voltage winding 14, and a tap winding 15 around an iron core 11, and leads. The line 17 and the tap changer 18 are formed in a sealed container 19. A partition plate 21 having high airtightness is provided in the container 19, and the interior is partitioned into a first chamber 22 and a second chamber 23.

  The transformer chamber 16 is accommodated in the first chamber 22, and the tap changer 18 is accommodated in the second chamber 23. A part of the partition plate 21 is formed of an insulating plate 24, and the insulating plate 24 is provided with a through hole 25 for penetrating the lead wire 17. The lead wire 17 has one end connected to the tap winding 15 and the other end connected to the tap changer 18.

  An insulating gas is sealed in each of the first chamber 22 and the second chamber 23. The insulating gas sealed in the first chamber 22 cools the inside of the low-voltage winding 12, the intermediate-voltage winding 13, the high-voltage winding 14 and the tap winding 15 and is circulated by a blower (not shown). The insulating gas is heated by cooling the windings 12, 13, 14, and 15, but is cooled by a cooler (not shown). Such a gas-insulated transformer may be directly connected to a gas-insulated switchgear through an insulating spacer, which greatly contributes to the reduction of substations.

SF ₆ gas (sulfur hexafluoride) is mainly used as the insulating gas sealed in the tank in the gas insulating transformer as described above. SF ₆ gas is tasteless, odorless, colorless, non-toxic, and non-flammable, very stable gas when the gas insulated transformer is used. For this reason, it is very convenient to use as an insulating gas, and it is well known that it is widely used as an insulating / cooling medium not only in gas-insulated transformers but also in high-voltage electrical equipment. The withstand voltage of SF ₆ gas increases in proportion to the gas pressure in an equal electric field. SF ₆ gas destruction is an electric field dependent type, and the magnitude of the electric field has the property of determining the destruction.

Generally, each winding in a gas-insulated transformer has an insulating configuration in which a conductor is covered with an insulating coating. This is because by applying insulating coating to the conductor, the electric field on the surface is relaxed and the withstand voltage is improved as compared with the case of the bare electrode. In such a gas insulated transformer taking the insulating structure, since the lower the dielectric strength of SF ₆ gas as compared with the insulating material of the insulating coating, dielectric strength is determined by the dielectric strength of SF ₆ gas.

In this way, SF ₆ gas is an important factor that affects the dielectric strength of a gas-insulated transformer. However, due to the recent increase in interest in environmental problems, the global warming potential GWP (Global Warming Potential) of SF ₆ gas has been increased. Evaluation has been carried out. This GWP is an index obtained by quantifying the ratio of contribution to global warming when a certain amount of gas is released into the atmosphere compared to CO ₂ . SF ₆ gas is chemically stable, has a long lifetime in the atmosphere of 3200 years, and has a large infrared absorption. Therefore, the GWP is as high as 23900 times CO ₂ and has a large greenhouse effect.

The size of the impact on global warming greenhouse gases, is represented by the product of the GWP and air concentrations, the atmospheric concentrations of presently SF ₆ gas is small, SF ₆ gas global warming The impact on is small. However, if the concentration in the atmosphere increases due to an increase in emissions, it is expected to contribute greatly to global warming. Therefore, in the United Nations Framework Convention Parties Conference on the 3rd Climate Change, which was held in Kyoto in December 1997 (COP3), SF ₆ gas is set as the target gas emissions regulations and reduction, SF ₆ gas Use reduction is a social requirement.

In response to this request, research on an alternative gas to SF ₆ gas has been conducted as a recent research on insulating gas. However, according to research results aimed at reducing SF ₆ gas, an excellent insulating gas having the same gas pressure and the same insulation strength as SF ₆ has not been observed yet. Therefore, in the gas insulated apparatus which uses SF ₆ gas, when using the alternative gas of SF ₆ gas, it has been various ideas.

For example, in the gas-insulated transformer 10 described in Patent Document 1, the use of SF ₆ gas is achieved by providing a partition plate 21 between the transformer body 16 and the on-load tap changer 18 where the bare electrode exists. The amount and total emission amount are reduced. That is, different types of insulating gases are sealed in the first chamber 22 and the second chamber 23 by partitioning the inside of the container 19 with the highly airtight partition plate 21.

Here, SF ₆ gas is sealed in the second chamber 23 that requires high dielectric strength, but the first chamber 22 that houses the transformer main body 16 has a lower environmental load than SF ₆ gas. A gas, specifically, a single gas of nitrogen gas or carbon dioxide gas, or a mixed gas composed of these gases and SF ₆ gas can be sealed. This makes it possible to reduce the consumption and emissions of SF ₆ gas.
JP 2003-197435 A

By the way, the gas-insulated transformer is also connected to the gas-insulated switchgear through an insulating spacer. However, in the connection structure with the gas-insulated switchgear, there is still an effective proposal for reducing the SF ₆ gas. The following problems occurred.

That is, the insulating spacer has been increased in size in order to ensure the withstand voltage of the insulating spacer that connects the gas insulating transformer and the gas insulating switchgear. Correspondingly, the size of the gas-insulated switchgear itself connected to the insulating spacer is increased, which not only hinders downsizing of the equipment, but is also preferable from the viewpoint of reducing the amount of SF ₆ gas used and discharged. There wasn't.

  Furthermore, since it is necessary for the gas-insulated transformer to house windings, iron cores, etc., the mechanical strength of the gas-insulated transformer is limited even if the pressure of the insulating gas sealed in the tank is increased. On the other hand, the gas insulated switchgear can easily manufacture a tank that can withstand high gas pressure due to its tank shape, and it is easy to increase the gas pressure. Therefore, when connecting an environment-friendly gas-insulated transformer and a gas-insulated switchgear, the gas pressure to be sealed is different, and there is a problem in terms of insulation between them.

The present invention has been proposed in view of the above-described circumstances, and reduces the amount of SF ₆ gas used and discharged to prevent contribution to global warming while ensuring excellent insulation performance. An object of the present invention is to provide a gas-insulated transformer that can be reliably connected to a gas-insulated switchgear.

  In order to achieve the above-mentioned object, the present invention attaches an insulating spacer to a lead wire lead-out portion of a tank containing insulating gas, a winding and an iron core, and further performs gas insulating switching while separating the gas through the insulating spacer. In a gas-insulated transformer configured to connect a device, an intermediate gas line is installed between the insulating spacer and the gas-insulated switchgear, and airtightness is provided in an intermediate part of the intermediate gas line. A second insulating spacer is attached.

In the present invention as described above, since the second insulating spacer is attached to the intermediate gas pipe, the inside of the tank of the gas insulating transformer, the portion sandwiched between the two insulating spacers in the intermediate gas pipe, The gas can be divided into three parts from the second insulating spacer to the gas insulating switchgear. For this reason, with respect to the insulating gas sealed in each part, it is possible to change the sealed gas pressure and the type of gas while achieving insulation coordination. Therefore, by using SF ₆ gas only on the gas-insulated switchgear side and using an environmentally low load gas other than SF ₆ gas in the other parts, it is possible to reduce the amount of SF ₆ gas used and discharged. it can.

According to the gas-insulated transformer of the present invention as described above, SF ₆ gas is used only on the gas-insulated switchgear side by a very simple configuration including an intermediate gas line and a second insulating spacer. By using the environmentally low load gas in this part, it becomes possible to reduce the amount of SF ₆ gas used and discharged as a whole, and contribute to the prevention of global warming.

Hereinafter, the best mode (embodiment) for carrying out the present invention will be described in detail with reference to FIG. FIG. 1 is a cross-sectional view showing an example of the internal configuration of a gas-insulated transformer according to this embodiment.
(1) Configuration As shown in FIG. 1, a gas-insulated transformer 9 according to the present embodiment includes a transformer body configured by winding a low-voltage winding 2, an intermediate-voltage winding 3, and a high-voltage winding 4 around an iron core 1. 6 and a lead wire 5 led out from the high voltage winding 4 are housed in a sealed tank 7. In order to lead out the lead wire 5 to the outside, a hole 71 is formed in a side portion of the tank 7, and a flange portion of the insulating spacer 31 is attached to the outer peripheral portion of the hole 71. The lead wire 5 is supported by the inner peripheral portion of the insulating spacer 31.

  Furthermore, an intermediate gas pipe 33 is attached to the flange portion of the insulating spacer 31 on the side opposite to the tank 7. The intermediate gas pipe 33 is connected to a gas insulated switchgear (not shown) on the side opposite to the tank 7. The insulating spacer 31 is a so-called gas partition spacer that keeps hermeticity, so that the insulating gas sealed in the tank 7 side of the gas insulating transformer 9 and the intermediate gas pipe 33 are not mixed with each other. It is configured.

Here, in the tank 7 of the gas-insulated transformer 9, an environmentally low load gas A (specifically, nitrogen gas or carbon dioxide gas having a relatively low insulation characteristic, or a mixture of these gases and SF ₆ gas) Gas) is sealed, and the intermediate gas pipe 33 is filled with SF ₆ gas B having higher insulation characteristics than the environmentally low load gas A. The insulating spacer 31 is mounted so that the tank 7 side is convex and the intermediate gas pipe 33 side is concave.

  The intermediate gas pipe 33 is shaped to have a small diameter at the middle part of the pipe, and has a large diameter part having a diameter d1 on the side (left side in FIG. 1) attached to the tank 7 of the gas insulating transformer 9. 33a and a small diameter portion 33b having a diameter d2 on the side (right side in FIG. 1) connected to the gas insulated switchgear. Further, a second insulating spacer 32 having airtightness is disposed at a portion where the diameter changes in the middle portion of the intermediate gas conduit 33, and the flange portion of the insulating spacer 32 forms the intermediate gas conduit 33. The flange part of the large diameter part 33a and the small diameter part 33b is attached. The lead wire 5 is supported by the inner peripheral portion of the insulating spacer 32. In addition, the direction of the insulating spacer 32 is the same as that of the insulating spacer 31, and the tank 7 side of the gas insulating transformer 9 is convex and the gas insulating switch side is concave.

  In the intermediate gas pipe 33, the large diameter portion 33a and the small diameter portion 33b are divided into left and right sides with the second insulating spacer 32 as a boundary. That is, the portion between the insulating spacer 31 attached to the tank 7 and the second insulating spacer 32 is the large-diameter portion 33a, and the portion between the second insulating spacer 32 and the gas-insulated switchgear is the small-diameter portion 33b. It becomes. Since the diameter of the intermediate gas pipe 33 is diameter d1> diameter d2, the insulating spacer 31 and the insulating spacer 32 correspond to this, and the diameter of the insulating spacer 31 is larger than that of the second insulating spacer 32. It is provided to be larger.

Like the insulating spacer 31 attached to the tank 7, the second insulating spacer 32 is a so-called gas partitioning spacer that maintains airtightness, and the large-diameter portion 33 a of the intermediate gas pipe 33 is formed by the insulating spacers 31 and 32. The large-diameter portion 33a and the small-diameter portion 33b close to the gas-insulated switchgear are configured so that the insulating gas sealed therein is not mixed with each other. As described above, the SF ₆ gas B is sealed in the intermediate gas pipe 33, but the large diameter portion 33a and the small diameter portion 33b have different compositions by being separated by the insulating spacer 32. SF ₆ gases B1 and B2 are enclosed.

Here, the SF ₆ gas B1 sealed in the large diameter portion 33a of the intermediate gas pipe 33 has an insulation strength higher than that of the environmental low load gas A sealed in the tank 7 of the gas insulation transformer 9. It is set higher than the insulation strength of SF ₆ gas B2 sealed from the small diameter portion 33b of the intermediate gas pipe 33 to the gas insulation switchgear side. That is, the insulation strength of the SF ₆ gas B1 sealed in the large diameter portion 33a of the intermediate gas pipe 33 is equal to the insulation strength of the environmental low load gas A on the tank 7 side of the gas insulation transformer 9 and the intermediate gas pipe 33. Is set to the middle of the insulation strength of SF ₆ gas B2 sealed from the small diameter portion 33b to the gas insulated switchgear side.

(2) Operational Effects The operational effects of the present embodiment having the above-described configuration are as follows. That is, by providing two insulating spacers 31 and 32 for gas classification, gas is supplied from the tank 7 of the gas insulating transformer 9, the large diameter portion 33 a of the intermediate gas conduit 33, and the small diameter portion 33 b of the intermediate gas conduit 33. Gas can be divided into three parts on the insulated switchgear side, and the gas pressure and gas type can be changed for the insulating gas sealed in each part. Therefore, in this embodiment, SF ₆ gas B1 and B2 are used only from the intermediate gas line 33 to the gas insulated switchgear, and the environmentally low load gas A is used in the tank 7 of the gas insulated transformer 9. . Thus, it is possible to reduce the amount of SF ₆ gas in the gas insulated transformer 9, it is possible to reduce the load on global warming.

Further, in this embodiment, as the insulating gas sealed in the tank 7 of the gas insulating transformer 9, an environmental low load gas A (nitrogen gas, carbon dioxide gas, or these gases having lower insulating strength than SF ₆ gas B is used. SF ₆ gas mixed gas) is used. However, since the diameter of the insulating spacer 31 is larger than the diameter of the second insulating spacer 32 in the intermediate gas pipe 33, SF _{6 is} used on the gas insulating switchgear side. Even if gas is used, insulation coordination can be achieved between the gas-insulated transformer 9 side and the gas-insulated switchgear side.

In addition, in this embodiment, the insulation strength of the SF ₆ gas B1 sealed in the large diameter portion 33a of the intermediate gas pipe 33 is set to the insulation strength of the environmental low load gas A on the tank 7 side of the gas insulation transformer 9. Since the intermediate gas pipe 33 is set in the middle of the insulation strength of the SF ₆ gas B2 sealed from the small-diameter portion 33b of the intermediate gas pipe 33 to the gas-insulated switchgear, more reliable insulation coordination can be achieved and insulation reliability can be achieved. Sex is further improved.

  In addition, since the concave side having a low insulation strength is set to the intermediate gas pipe 33 side in the mounting direction of the insulation spacer 31, an insulating configuration having a high insulation strength can be obtained also on the gas insulation transformer 9 side. Furthermore, since the concave side of the insulating spacer 31 is directed toward the intermediate gas pipe 33, the protrusion of the protective cover that covers the insulating spacer 31 when the transformer is transported is small, and the transport dimension is small. Therefore, there is an advantage that transportation is easy even within Japan's severe transportation restrictions.

(3) Other Embodiments The present invention is not limited to the above embodiment, and the gas pressure and type of the insulating gas sealed in each part divided by the two gas insulating spacers 31 and 32. Can be changed as appropriate. For example, in the above embodiment, the environmentally low load gas A is sealed only in the tank 7 of the gas insulated transformer 9, but in all parts from the gas insulated transformer 9 and the intermediate gas pipeline 33 to the gas insulated switchgear. Environmental low load gas A may be used.

  At that time, an intermediate gas pipe 23 is provided between the gas-insulated transformer 9 and the gas-insulated switchgear, so that the same kind of environmentally low load gas is gas-insulated from the gas-insulated transformer 9. Even when sealed on the switchgear side, the gas pressure sealed in the large-diameter portion 33a of the intermediate gas line 33 is made higher than the tank 7 side of the gas insulation transformer 9, and the intermediate gas line 33 The gas pressure sealed in the insulating gas sealed in the range from the small diameter portion 33b of the intermediate gas pipe 33 to the gas insulated switchgear is set to be higher than the gas pressure sealed in the large diameter portion 33a. Is possible.

  Thus, even if the gas pressure differs between the gas insulated transformer 9 side and the gas insulated switchgear side, the diameter of the insulating spacer 31 on the gas insulated transformer 9 side is closer to the gas insulated switchgear. Since the diameter is larger than 32, there is no problem in insulation even if an environmentally friendly gas insulated transformer and gas insulated switchgear are directly connected.

  In addition, in the gas insulated switchgear side, the gas insulated transformer 9 side, and the intermediate gas pipe 33, the environmentally low load gas having a different composition is applied to each part instead of changing the sealed gas pressure sealed in each part. May be used. Specifically, carbon dioxide gas is sealed on the gas-insulated switchgear side, nitrogen gas is sealed on the gas-insulated transformer 9 side, and another insulating gas is sealed on the large-diameter portion 33a of the intermediate gas pipe 33. You can also.

1 is a schematic longitudinal sectional view showing a first embodiment of a connection portion between a gas insulated transformer and a gas insulated switchgear according to the present invention. Schematic which shows the conventional gas insulation transformer which shows the conventional gas insulation transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 11 ... Iron core 2, 12 ... Low voltage winding 3, 13 ... Medium voltage winding 4, 14 ... High voltage winding 5, 17 ... Lead wire 6, 16 ... Transformer main body 7 ... Tank 9, 10 ... Gas insulation Transformer 31 ... Insulation spacer 32 ... Second insulation spacer 33 ... Intermediate gas conduit 33a ... Large diameter portion 33b ... Small diameter portion 71 ... Hole

Claims (6)

Gas insulation transformer configured to attach an insulation spacer to the lead wire lead-out portion of the tank containing the insulation gas, winding and iron core, and to connect the gas insulation switchgear while separating the gas through this insulation spacer In the vessel
An intermediate gas line is installed between the insulating spacer and the gas-insulated switchgear;
A gas-insulated transformer, wherein a second insulating spacer having airtightness is attached to an intermediate portion of the intermediate gas pipe. The intermediate gas is configured so that the diameter changes in the middle,
2. The gas insulation transformer according to claim 1, wherein the second insulation spacer is attached to a portion where the diameter of the intermediate gas pipe changes. The intermediate gas pipe has a diameter on the insulating spacer side larger than a diameter on the gas insulated switchgear side,
3. The diameter of the second insulating spacer attached to the intermediate portion of the intermediate gas pipe is smaller than the diameter of the insulating spacer attached to the lead wire lead-out portion of the tank. Gas-insulated transformer as described.   The insulating spacer attached to the lead wire lead-out portion of the tank and the second insulating spacer attached to the intermediate portion of the intermediate gas pipe are convex toward the tank side. The gas-insulated transformer according to any one of claims 1 to 3.   The insulating gas sealed in the tank is different from the insulating gas sealed in the gas-insulated switchgear in at least one of its kind and sealing pressure. Gas-insulated transformer as described in the paragraph.   The gas-insulated transformer according to claim 5, wherein a sealing pressure of the insulating gas sealed in the tank is lower than that of the insulating gas sealed in the gas-insulated switchgear.

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