JPH0945551A - Gas insulated stationary induction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a large-capacitance gas insulated stationary induction apparatus which is inexpensive and excellent in long-term reliability of mechanical and electrical strength of an insulating cover layer of a winding. SOLUTION: An insulating cover layer of a winding 3 having its upper and lower parts connected to a neutral point with a high-voltage line led out from the center thereof is divided into three parts, which are covered with three types of plastic films having different characteristics. An upper part 3a is covered with a film having heat resistance property of insulation type not lower than type F and higher than heat resistance properties of the other films. A center part 3b is covered with a film having a dielectric breakdown field higher than those of the other films and heat resistance property higher than that of the film covering a lower part 3c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas-insulated static induction machine.

[0002]

2. Description of the Related Art In underground substations and substations in buildings, equipment is being made nonflammable from the viewpoint of disaster prevention, and the use of gas-insulated static induction generators is increasing. Since the conventional gas-insulated static induction generator is inferior in gas cooling performance to liquid refrigerant, it is more heat-resistant than the pressboard made of kraft paper or wood pulp, which is a type A insulating material generally used for oil-filled static induction generators. Highly insulating material is used. For example, for the insulation coating material of the coil that has the highest temperature, polyethylene terephthalate (PE of insulation type E (maximum allowable temperature 120 ° C))
T) film is often used.

Further, with the recent increase in power demand in urban areas, there is an increasing demand for large capacity of 275 kV, 300 MVA class in gas-insulated static induction generators installed in underground substations. When increasing the capacity of a gas-insulated static induction electric machine, if the current density of the winding is reduced and the temperature is suppressed to 120 ° C. or lower, which is the maximum allowable temperature of the Class E insulation, the winding and eventually the equipment become large. Since problems such as not being able to satisfy transportation restrictions in urban areas arise, the insulation coating material of the winding requires a material of insulation type B (maximum allowable temperature 130 ° C.) or higher. However, since the PET film is hydrolyzed at high temperature even if a small amount of water is present, there is concern that mechanical strength and electrical strength may decrease, and it is suitable as a winding coating material for large-capacity gas-insulated static induction generators. Not.

Under such circumstances, various plastic films having higher heat resistance have been studied in place of the PET film. Among them, F class insulation material (maximum allowable temperature
155 ° C.), and application of a polyphenylene sulfide (PPS) film, which does not cause hydrolysis, to a gas-insulated static induction electric device has been studied and put into practical use.

[0005]

Generally, in a gas-insulated static induction electric generator of the gas feeding type, the gas cooled by the cooler is introduced into the lower part of the main body tank by the blower. The gas cools the winding from a lower portion of the winding through a gas flow path formed in the winding, then flows from an upper portion of the winding to an upper portion of the main body tank, is guided to a cooler through a pipe, and circulates. 275kV with gas cooling
When manufacturing a large-capacity device of 300 MVA or more, the difference in gas temperature between the inlet and the outlet of the gas passage for cooling the winding is much larger than that of the conventional oil-filled static induction generator, which is 20 ° C. or more. This is because in order to increase the capacity, the current density of the winding must be increased and the heat generation from the winding increases, and the gas flow path for cooling the winding becomes long. Therefore, the temperature of the winding also has a large temperature difference of 20 ° C. or more between the upper portion and the lower portion of the winding, like the gas temperature.

[0006] When the temperature difference between the upper and lower windings becomes large as described above, the PET film of insulation type E, which has been conventionally used as an insulating coating material for the winding, is subject to hydrolysis or the like at the upper portion of the winding where the temperature becomes high. Deteriorates, and long-term reliability of electrical and mechanical strength is impaired. On the other hand, when the insulation type F type PPS film is used, there is no risk of hydrolysis, and long-term reliability of electrical and mechanical strength is secured. However, since the breakdown voltage per unit thickness of the PPS film is only about 70% as compared with the PET film, it is necessary to thicken the coating layer in order to prevent penetration breakdown of the insulating coating layer. Not only will the cooling be insufficient, but the space factor of the winding will decrease, leading to an increase in the size of the device. Further, since the PPS film is an expensive material, it cannot be ignored that the material cost increases when the PPS film is used up to the lower part of the winding where high heat resistance is not particularly required.

As described above, conventionally, the temperature distribution above and below the winding in the winding coating layer of a large-capacity gas-insulated static induction electric device has not been taken into consideration, and long-term reliability and economical efficiency of cooling characteristics and insulation characteristics are satisfied. The insulating coating layer and the insulating structure to be used have not been sufficiently considered.

An object of the present invention is to provide an inexpensive large-capacity gas-insulated static induction electric device which is excellent in long-term reliability of electrical and mechanical strength of an insulating material and is inexpensive.

[0009]

In order to achieve the above-mentioned object, the present invention connects the insulating coating layers of the upper and lower parallel windings whose upper and lower and middle are connected to the neutral point and the high voltage line, respectively, to the neutral point. A first insulating coating layer covering the upper portion of the winding, a second insulating coating layer covering the middle portion of the winding connected to the high voltage line, and a first insulating coating layer covering the lower winding portion connected to the neutral point. 3 insulating coating layers, each insulating coating layer is formed by winding three kinds of plastic films having different characteristics around a conductor, and the plastic film forming the first insulating layer is made of insulating material. It has heat resistance of type F or more and has higher heat resistance than the plastic film forming the other insulating layer, and the plastic film forming the second insulating layer is more insulated than the plastic film forming the other insulating layer. Destruction Field is high is and those having a high plastic film heat resistance than plastic film forming the third insulating layer.

[0010]

When the insulation coating of the winding is constructed as above, the upper part of the winding where the temperature becomes the highest is covered with the plastic film with the highest heat resistance, so the long-term reliability of the electrical and mechanical strength of the insulation coating is ensured. Is secured. Further, since the central portion of the winding from which the high voltage line is drawn out is covered with the plastic film having the highest dielectric breakdown electric field, the insulation strength against the impulse voltage can be improved without increasing the thickness of the coating and lowering the cooling characteristics. That is, it acts to maintain the electrical and mechanical strength of the insulation coating without impairing the cooling characteristics of the winding. Further, since the conventional plastic film can be used in the lower part of the winding where the temperature rise is small, the application places of the expensive high heat resistant plastic film can be limited, and the increase in material cost can be suppressed.

[0011]

The present invention will be described in detail below with reference to the illustrated embodiments.

FIG. 1 is an explanatory view showing an embodiment of the gas-insulated static induction generator of the present invention. In the figure, reference numeral 1 denotes a tank, which is provided inside with an iron core 2 and a winding 3 wound around the iron core 2. In addition, tank 1 has about 0.5MP
SF ₆ gas 4 which is an insulating and cooling medium pressurized to a
Is filled. The SF ₆ gas 4 is circulated in the cooler 6 and the tank 1 by the blower 5 communicating with the tank 1,
The iron core 2 and the winding 3 are cooled. Here, the SF ₆ gas 4 cooled by the cooler 6 is cooled from the lower part to the upper part of the winding wire 3 through a gas flow path in the winding wire 3 (not shown). Reference numeral 7 is a partition plate, and 8 is a high voltage terminal of the winding 3 connected to the high voltage line.

FIG. 2 shows SF ₆ along the gas flow path in winding 3.
It shows the temperature distribution of the gas 4 and the temperature distribution of the winding 3. The temperature of SF ₆ gas 4 is the lowest at the bottom of winding 3,
It gets hotter toward the top. 275kV, 300M
In the VA class gas-insulated static induction electric machine, since the current density of the winding is high and the heat capacity of the SF ₆ gas 4 is small, the temperature of the SF ₆ gas 4 at the upper and lower gas passage inlets and outlets of the winding 3 is small. The difference is 20 ° C or more. The temperature of the winding 3 is SF
₆ 30 than SF ₆ gas 4 due to the low heat transfer rate for the gas 4
The temperature rises to about ℃.

Here, the upper portion 3a, the central portion 3b, and the lower portion 3c of the winding 3 of FIG. 1 are wound with different plastic films to form an insulating coating layer. Below, winding 3
The structure will be described in some detail with reference to FIG. FIG. 3 (a)
FIG. 2 is an axial sectional view of a winding wire 3 of FIG. 1. In the figure,
The winding 3 is configured by stacking a large number of disk coils 11 wound around an inner insulating tube 9 with eight inner vertical spacing pieces 10 evenly arranged in the axial direction. An outer insulating cylinder 13 is arranged around the disk coil 11 with eight equally spaced outer vertical spacing pieces 12 therebetween. Here, between the inner insulating cylinder 9 and the disk coil 11, and between the disk coil 11 and the outer insulating cylinder 13, the inner vertical gas duct 14,
An outer vertical gas duct 15 is formed. Reference numeral 16 is a horizontal insulator spacing piece which is sandwiched between the laminated disk coils 11.
Here, as a specific material, for example, a commercially available press board whose main component is natural pulp is used as the inner and outer insulating cylinders 9 and 13, and the horizontal insulator spacing piece 16 and the inner and outer vertical insulator spacing pieces 10 and 12 are used. A commercially available heat-resistant press board containing aromatic polyamide as a main component is used as. FIG.
4A is a sectional view taken along line AA of FIG. Figure 4 (a)
Then, the disk coils 11 are stacked with a horizontal gas duct 17 formed by sandwiching the horizontal insulator spacing piece 16 interposed therebetween. In addition, the inner vertical gas duct 14 and the outer vertical gas duct 15 are provided at predetermined intervals between the disk coils 11.
The flow fold plate 18 made of a commercially available heat-resistant press board containing aromatic polyamide as a main component, which alternately closes the
A folding zone is formed. Therefore, SF which is the cooling medium
_{The 6} gas flows in the zigzag shape in the bent region from the lower part of the winding toward the upper part, and the disk coil 11 is cooled. here,
As an insulating coating material for the disk coil 11, a PPS film, a PEN film, and a PET film were used in the winding upper portion 3a, the winding central portion 3b, and the winding lower portion 3c, respectively. 1
Reference numerals 9a and 19b are an upper support insulator and a lower support insulator, respectively, for tightening the winding from above and below. FIG. 4B is a sectional view taken along line BB of FIG.

In FIGS. 4 (a) and 4 (b), the disk coil 11 has the highest temperature as shown in FIG. 2 in the winding upper part 3a, and therefore has the highest heat resistance among the three kinds of plastic films. It is covered with a film. In the winding central portion 3b, the disk coil 11 is connected to the high voltage terminal 8 and a high dielectric strength is required for the insulating coating layer, so that the film having the highest dielectric breakdown electric field among the three types of plastic films. It is covered with. In the lower part 3c of the winding, the disk coil 11 has a small temperature rise and a small voltage share when the impulse voltage enters, and is therefore covered with a plastic film of insulation type E or B. Specifically, in the winding upper portion 3a, the winding central portion 3b, and the winding lower portion 3c, commercially available polyphenylene sulfide (PPS) film and polyethylene naphthalate (PEN) are used as coating materials for the disc coil 11, respectively. ) Films and polyethylene terephthalate (PET) films can be used.

When the insulating coating layer of the winding wire 3 is constructed in this way, the winding upper portion 3a, which has a high temperature, is a high heat resistant material of insulation type F and is covered with a PPS film that does not cause hydrolysis. The insulating coating layer in this portion ensures long-term reliability of electrical and mechanical strength. Further, the winding central portion 3b connected to the high voltage line is covered with a PEN film having a heat resistance close to that of the PPS film and a dielectric breakdown voltage which is about 1.4 times higher than that of the PPS film. The cooling characteristics are improved and the winding space factor can be increased. Here, in principle, hydrolysis proceeds in the PEN film, but since the temperature of the winding central portion 3b does not become higher than that of the winding upper portion 3a, there is no practical problem. The lower portion 3c of the winding has a small temperature rise in this portion even if an inexpensive PET film of insulation type E or B is used, the hydrolysis progresses very slowly, and the deterioration of electrical and mechanical strength is a problem. It does not become.

Further, generally, the higher the heat resistance is, the higher the price of the insulating material is. However, with the above-mentioned structure, the use of a plastic film having different heat resistance depending on the temperature rise of the winding leads to a high price. It is possible to suppress the increase in material cost by limiting the places where the high heat resistant material is applied.

As described above, in this embodiment, a plurality of insulating materials having different heat resistance and dielectric strength are used as the insulating coating material of the winding in consideration of the required insulating strength and temperature distribution, so that the material cost is increased. While minimizing the above, the long-term reliability of the electrical and mechanical strength of the entire insulating material forming the winding is further improved.

In this embodiment, the horizontal insulator spacing piece 1 is used.
6, heat-resistant pressboards were used as the inner and outer vertical insulator spacing pieces 10 and 12, and the flow fold plate 18. However, the insulating members other than the insulating coating of the windings including them also differ in consideration of the temperature distribution. It makes more sense to use materials. For example, a heat-resistant press board of insulation type H containing aromatic polyamide as a main component is provided on the horizontal insulator spacing piece 16 on the upper portion 3a of the winding, and an insulation type B obtained by mixing aromatic polyamide and PET at the central winding portion 3b. Seed heat resistant press board,
Insulation type A whose main component is natural pulp in the lower part of the winding 3c
Each type of press board can be used. Further, the inner vertical spacing piece 10 and the outer vertical spacing piece 12 may be made of two kinds of materials having different heat resistances. For example,
It is also possible to configure the upper part of the two insulating members with a heat-resistant pressboard of insulation type H containing aromatic polyamide as the main component and the lower part with a pressboard of insulation type A containing natural pulp as the main component. . Further, the upper and lower supporting insulators 19a and 19b of the winding and the insulating coating layers of the electric field mitigating shield ring at the upper and lower ends of the winding are also 2
It is more rational if it is composed of more than one kind of material.

[0020]

According to the present invention, the long-term reliability of the electrical and mechanical strength of the insulating coating on the upper portion of the winding where the temperature becomes highest can be ensured. Further, the insulation strength against the impulse voltage can be improved without thickening the coating at the central portion of the winding where the high voltage line is drawn out and lowering the cooling characteristic. Furthermore, since a conventional plastic film can be used in the lower part of the winding where the temperature rise is small, it is possible to limit the application places of the expensive high heat-resistant plastic film and suppress an increase in material cost.

Therefore, it is possible to provide an inexpensive large-capacity gas-insulated static induction electric device having excellent long-term reliability of the electrical and mechanical strength of the insulator.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a gas-insulated static induction generator according to the present invention.

FIG. 2 is a characteristic diagram showing the relationship between the gas flow path position in the winding of the gas-insulated static induction generator and the gas and winding temperature.

FIG. 3 is a cross-sectional view of windings of the gas-insulated static induction generator of the present invention.

FIG. 4 is a vertical sectional view of the same.

[Explanation of symbols]

1 ... Tank, 2 ... Iron core, 3 ... Winding, 4 ... SF ₆ gas.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshihiro Nagao 1-1-1, Kokubuncho, Hitachi City, Ibaraki Hitachi Co., Ltd. Kokubun Plant, Hitachi Ltd.

Claims (3)

[Claims] 1. A gas-insulated static induction electric machine comprising a single or a plurality of windings wound concentrically around an iron core and an approximately iron core in a tank filled with pressurized SF ₆ gas. At least one of which is configured by stacking a plurality of winding units having insulating coating layers made of different materials on top of each other, and the uppermost winding unit has heat resistance of insulation type F or more. Insulation static induction. 2. A tank filled with a pressurized SF ₆ gas is provided with an iron core and a single or a plurality of windings wound concentrically around the iron core, and at least one of the windings is vertically and vertically arranged. In a gas-insulated static induction electric machine, the middle of which is an upper and lower parallel winding connected to a neutral point and a high-voltage line, respectively, and an insulating coating layer of the upper and lower parallel windings covers an upper portion of the winding connected to the neutral point. A first insulating cover layer, a second insulating cover layer covering the middle part of the winding connected to the high voltage line, and a third insulating cover layer covering the lower part of the winding connected to the neutral point, Each of the insulating coating layers is formed by winding three kinds of plastic films having different characteristics around a conductor, and the plastic film forming the first insulating layer has heat resistance of insulation type F or more, The plastic film that constitutes the insulating layer The heat resistance is high, the plastic film forming the second insulating layer has a higher dielectric breakdown electric field than the plastic film forming the other insulating layers, and the heat resistance is higher than the plastic film forming the third insulating layer. A gas-insulated static induction electric device characterized by the above. 3. The plastic film constituting the first insulating layer, the second insulating layer, and the third insulating layer according to claim 2, wherein the plastic films are a polyphenylene sulfide film, a polyethylene naphthalate film, and a polyethylene, respectively. A gas-insulated static induction electric device that is a terephthalate film.