JP6640651B2 - Gas insulated load tap changer - Google Patents

Description

  Embodiments of the present invention relate to a gas-insulated on-load tap changer.

  In recent years, substations installed in urban areas have been shifting to underground types in order to make them more compact because it is difficult to construct large-scale substations on the ground. With the shift to underground substations, gas-insulated transformers in which an insulating gas is sealed in a closed container have become the mainstream as transformers arranged in substations. This is because the gas insulation transformer is excellent in environmental performance and safety.

Normally, the transformer connected to the system is equipped with a tap change device at load to stabilize the system voltage, but in response to the fact that the transformer is gas-insulated, the gas-insulated load An hour tap switching device is employed. In the gas-insulated load tap changer, a gas container having a closed structure is attached to the opening of the transformer tank, and the changeover switch is housed in the gas container. A tap selector is arranged below the gas container, and is connected to the transformer via a tap lead wire.

JP 2013-247170 A

  In the gas-insulated on-load tap changer, it is necessary to isolate the changeover switch from the transformer tank and to maintain the airtightness and insulation inside the changeover switch. Therefore, the gas container is formed of a cylinder made of an insulating material, and the gas container and the head cover are sealed by a ring-shaped seal member. Then, a shield is provided so as to cover the seal. The shield has a curved surface portion so as to cover the seal member, and the shield reduces the electric field concentration inside the switching switch.

  2. Description of the Related Art In recent years, gas-insulated on-load tap switching devices have tended to increase in size due to demands for higher capacity. In a large-sized device, a supporting insulating plate extending to the upper portion of the gas container is attached to the outer periphery of the switching switch in order to accurately position and insert the switching switch in the gas container. However, as the size of the device increases, the components inside the device also tend to increase in size. As a result, the gap between the supporting insulating plate and the shield becomes extremely small, and local electric field concentration occurs, so that it has been difficult to improve the withstand voltage.

  Embodiments of the present invention have been proposed to solve the above problems, and provide a gas-insulated on-load tap switching device that prevents local electric field concentration and improves withstand voltage. Aim.

  In order to achieve the above object, a gas-insulated on-load tap switching device according to an embodiment of the present invention has a gas container in which an opening is formed at an upper end portion, a switching switch is arranged inside, and an insulating gas is sealed. A head cover fitted to the opening of the gas container, a seal member for sealing between the gas container and the head cover, a seal pressing member for pressing the seal member, and a seal pressing member. An inner shield member having a curved surface portion covering a lower end portion, and an inner shield member attached to an outer peripheral portion of the switching switch, an upper end portion disposed adjacent to the inner shield member, and a predetermined distance between the inner shield member and the curved surface portion; And a supporting insulating plate provided with a notch for forming the gap.

FIG. 1 is a cross-sectional view illustrating an overall configuration of a gas-insulated load tap switching device according to a first embodiment. It is a partial cross section perspective view of a switching switch. It is an expanded sectional view of the A section of FIG. (A) is sectional drawing which shows the equipotential line of a prior art example, (b) is an enlarged view of the B section of (a). It is sectional drawing which shows the equipotential line of 1st Embodiment. It is a partial section perspective view of a change switch of a gas insulated type tap change device at the time of a load concerning a 2nd embodiment. It is sectional drawing which shows the equipotential line of 2nd Embodiment. It is a partial section perspective view of a change switch of a gas insulation type load change tap change device concerning a 3rd embodiment. It is sectional drawing which shows the equipotential line of 3rd Embodiment. It is sectional drawing which shows the structure of the tap switching apparatus at the time of a gas insulated type which concerns on 4th Embodiment. It is an expanded sectional view of the C section of FIG. It is the elements on larger scale of the gas insulated type tap change device at the time of a load concerning a 5th embodiment. It is the elements on larger scale of the gas insulated type tap change device at the time of a load concerning a 5th embodiment. It is a partial section perspective view of a change switch of a gas insulation type tap change device at the time of a load concerning a 6th embodiment. It is sectional drawing which shows the equipotential line of 6th Embodiment.

(First embodiment)
(Constitution)
A gas-insulated load tap switching device according to a first embodiment will be described with reference to FIGS. As shown in FIG. 1, a gas container 2c is attached to an opening of a transformer tank 1 in which an insulating gas 3 is sealed in a gas-insulated load tap switching device 2. The gas container 2c is a cylindrical member made of an insulating material and having an opening formed at an upper end. A switching switch 2a is disposed inside the gas container 2c, and an insulating gas 4 for insulating and cooling the switching switch 2a is sealed therein. As the insulating gas 4, for example, SF ₆ gas which is a non-flammable and stable gas having excellent insulating performance and the like is used.

  A tap selector 2b for selecting a pair of tap positions is arranged below the gas container 2c. A tap lead wire corresponding to each tap potential is drawn from a winding of a transformer (not shown), and is connected to the tap selector 2b, whereby circuit connection between the transformer and the on-load tap switching device 2 is performed.

  A head cover 6 is fitted into the opening at the top of the gas container 2c. The head cover 6 is a member for isolating the switching switch 2a from the transformer tank 1. The head cover 6 is formed of a metal material having a cylindrical portion extending downward, and the cylindrical portion of the head cover 6 is fitted into an opening above the gas container 2c.

  As shown in FIG. 3, a seal member 8 that seals the gas container 2 c and the head cover 6 is disposed between the gas container 2 c and the head cover 6. A holding ring 7 is provided. The seal holding ring 7 is joined to the lower end surface of the cylindrical portion of the head cover 6 by a bolt 7a.

  A tube-shaped first outer shield member 11 having a circular cross section is horizontally attached to the outer periphery of the gas container 2c along the outer periphery of the gas container 2c. The first outer shield member 11 is a member that is not electrically connected to the head cover 6, and is provided to reduce electric field concentration outside the switching switch 2a. Below the first outer shield member 11, a tube-shaped second outer shield member 15 having a substantially elliptical cross section is horizontally mounted along the outer periphery of the gas container 2c. The second outer shield member 15 is electrically connected to a high voltage application unit (not shown).

  As shown in FIGS. 1 and 2, an insulating cylinder 13 is disposed coaxially with the gas container 2c above the inside of the gas container 2c. An energy storage device 20 is arranged at a lower portion inside the insulating cylinder 13. The energy storage device 20 is connected to a drive shaft 21 extending through the center of the inside of the gas container 2c. The drive shaft 21 is connected to the switching switch 2a, and is switched by the torque transmitted from the energy storage device 20 via the drive shaft 21. The switch 2a is driven to perform a switching operation. An upper shield plate 9 and a lower shield plate 10 that are electrically connected to the energy storage device 20 are disposed inside the insulating cylinder 13 and above the energy storage device 20. The upper shield plate 9 and the lower shield plate 10 are installed parallel to each other at a predetermined interval. The upper shield plate 9 is a member that protects the electric field concentration on the metal member on the upper side (ground side) of the switching switch 2a, and the lower shield plate 10 is on the lower side (charging section side) of the switching switch 2a. It is a member that protects the electric field concentration on the metal member.

  As shown in FIG. 3, an inner shield member 14 is arranged so as to cover the seal member 8 and the seal holding ring 7. The inner shield member 14 is a conductive member formed in an annular shape, and the upper end is attached to the head cover 6 via a fixing tool, and is electrically connected to the head cover 6. The inner shield member 14 can be made of, for example, an aluminum plate material.

  The inner shield member 14 is viewed in a radial cross section. It has a linear portion 14a extending vertically and a semicircular curved surface portion 14b. That is, the inner shield member 14 has a J-shape in a radial cross-sectional view. The straight portion 14 a is arranged along the cylindrical portion of the head cover 6. The curved surface portion 14b is disposed so as to cover a part of the flat surface portion 12 of the seal holding ring 7 and the bolt 7a joined to the seal holding ring 7 toward the outside of the gas container 2a. The curved surface portion 14b of the inner shield member 14 covers the vicinity of the lower end of the seal holding ring 7 where the electric field tends to concentrate in the ground insulation, so that the concentration of the electric field is reduced.

  A supporting insulating plate 22 is attached to an outer peripheral portion of the gas container 2c. The support insulating plate 22 is an elongated plate-shaped member made of an insulating material. The support insulating plate 22 is used for positioning the switching switch 2a when inserting it into the gas container 2c. The supporting insulating plate 22 is attached to the outer periphery of the switching switch 2a and inserted, and the upper end of the supporting insulating plate 22 is guided to match the mounting position of the head cover 6, thereby positioning the switching switch 2a. When the supporting insulating plate 22 is inserted into the gas container 2 c, the upper end portion is disposed adjacent to the inner shield member 14. With the recent increase in size of the gas-insulated load tap changer, the gap between the inner shield member 14 and the supporting insulating plate 22 has almost disappeared. The number of the supporting insulating plates 22 can be appropriately determined according to the accuracy required for positioning.

  As shown in FIG. 3, a notch 22 a is formed in the supporting insulating plate 22. The notch 22a is formed by cutting out a portion near the curved surface portion 14b of the inner shield member 14 from the side of the support insulating plate 22 facing the inner shield member 14 toward the vicinity of the center in the axial direction. The notch 22a forms a predetermined gap d between the supporting insulating plate 22 and the curved surface portion 14b of the inner shield member 14.

  The material forming the supporting insulating plate 22 may be any insulating material, and is not limited to a specific material. For example, paper phenol can be used. When the switching switch 2a is inserted, the notch 22a of the supporting insulating plate 22 comes into contact with the inner shield member 14, which may damage the inner shield member 14. However, by using flexible paper phenol, Damage can be prevented.

(Action)
The operation of the gas-insulated load tap changer of this embodiment will be described in comparison with a conventional example. In the conventional example shown in FIG. 4, the notch 22a is not formed in the supporting insulating plate 22. When the notch 22a is not formed, as shown in FIG. 4A, the gap between the supporting insulating plate 22 and the curved surface portion 14b of the inner shield member 14 is extremely small, and as shown in FIG. A wedge-shaped space S is formed between the curved surface portion 14b at the lower end of the inner shield member 14 and the support insulating plate 22. The electric field is locally concentrated in the wedge-shaped space S, and there is a possibility that the ground insulation performance is reduced. The electric field value in the wedge-shaped space may be 1.9 times the allowable electric field value.

  On the other hand, as shown in FIG. 5, in the present embodiment, the notch 22a is formed in the support insulating plate 22 near the curved surface portion 14b of the internal shield member 14, so that the support insulating plate 22 and the internal shield member 14 A gap d is formed between the curved surface portion 14b and the curved surface portion 14b. As a result, no wedge-shaped space S is formed, and the concentration of the electric field is reduced. The electric field value can be reduced by about 77% as compared with the conventional example of FIG.

(effect)
The gas-insulated-type on-load tap switching device 2 according to the present embodiment includes a gas container 2c in which an opening is formed at an upper end portion, a switching switch 2a is disposed inside, and an insulating gas is sealed, and an opening of the gas container 2c. , A sealing member 8 for sealing between the gas container 2 c and the head cover 6, a seal pressing ring 7 serving as a seal pressing member for pressing the seal member 8, and a seal pressing ring 7. An inner shield member 14 covering a lower end portion and having a curved surface portion 14b on the lower side; and an outer shield portion attached to an outer peripheral portion of the switching switch 2a, and an upper end portion disposed adjacent to the inner shield member 14; And a supporting insulating plate 22 provided with a notch 22a that forms a predetermined gap with the curved surface portion 14b.

  The support insulating plate 22 disposed adjacent to the inner shield member 14 is provided with a notch 22a for forming a predetermined gap between the support insulating plate 22 and the curved surface portion 14b of the inner shield member 14, thereby providing a curved surface portion of the inner shield member 14. The formation of a wedge-shaped space S between the support insulating plate 22 and the support insulating plate 22 can be prevented. As a result, local electric field concentration can be prevented, and the pressure resistance of the gas-insulated load tap switching device can be improved.

  The notch 22a is formed by notching a portion near the curved surface portion 14b of the inner shield member 14. By notching only the portion of the supporting insulating plate 22 near the curved surface portion 14b where the electric field is concentrated, the concentration of the electric field can be reduced while maintaining the function of the supporting insulating plate 22 as a positioning member.

  The supporting insulating plate 22 may be made of paper phenol. By forming the supporting insulating plate 22 with flexible paper phenol, it is possible to prevent the corners of the cutouts 22 a of the supporting insulating plate 22 from being damaged by contact with the inner shield member 14. Thus, it is possible to prevent the metal powder generated due to the damage of the inner shield member 14 from flowing into the gas container 2c, and the ground insulation performance from being lowered.

(Second embodiment)
A gas-insulated load tap switching device according to a second embodiment will be described with reference to the drawings. In the following embodiments, the same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

  In the second embodiment, as shown in FIG. 6, the notch 22 b is provided from the vicinity of the curved surface portion 14 b of the support insulating plate 22 to the upper end of the support insulating plate 22. That is, the upper end of the support insulating plate 22 is narrower than the lower end by the notch 22b. By providing the notch 22b, a gap d is formed between the curved surface portion 14b of the inner shield member 14 and the support insulating plate 22. Thus, as shown in FIG. 7, local electric field concentration between the curved surface portion 14b of the inner shield member 14 and the supporting insulating plate 22 can be prevented, as in the first embodiment. Specifically, the electric field value can be reduced by about 76% as compared with the conventional example of FIG. This makes it possible to improve the pressure resistance of the gas-insulated load tap switching device.

(Third embodiment)
A gas-insulated load tap changer according to a third embodiment will be described with reference to the drawings. As shown in FIG. 8, in the third embodiment, a notch 22b extending from the vicinity of the curved surface portion 14b to the upper end of the supporting insulating plate 22 is provided as in the second embodiment. The notch 22b is formed on the side of the support insulating plate 22 that faces the internal shield member 14, but on the opposite side of the support insulating plate 22 where the notch 22b is provided, the inside of the gas container 2c. An overhanging portion 22c is provided. The overhang portion 22c has the same length and width as the notch 22b. As a result, the upper end of the supporting insulating plate 22 has a step shape different from that of the lower part.

  As described in the second embodiment, the provision of the notch 22b makes the upper end portion of the support insulating plate 22 narrower than the lower end portion, but the provision of the overhang portion 22c makes the upper end portion the same as the lower portion. Will have a width. The notch 22b prevents local electric field concentration between the curved surface portion 14b of the inner shield member 14 and the supporting insulating plate 22, and at the same time, the supporting insulating plate 22 can be reinforced by the overhanging portion 22c, and the positioning is ensured. Can be done. In the above example, the overhang portion 22c has been described as having the same length and width as the notch 22b. In this embodiment, the electric field value can be reduced by about 75% as compared with the conventional example of FIG.

(Fourth embodiment)
A gas-insulated load tap changer according to a fourth embodiment will be described with reference to the drawings. As shown in FIG. 10, in the fourth embodiment, a guide portion 40 is provided on the outer periphery of the bottom of the gas container 2c. The guide portion 40 has a width equal to the distance from the inner wall of the gas container 2c to the installation position of the supporting insulating plate 22. As shown in the enlarged view of FIG. 11, when the supporting insulating plate 22 is inserted into the gas container 2c, the guide portion 40 comes into contact with the supporting insulating plate 22, and positions the supporting insulating plate 22. If the position of the supporting insulating plate 22 is not stable, the gap d between the inner shield member 14 provided by the notch 22a and the curved surface portion 14b of the supporting insulating plate 22 is not stable, and the electric field may be concentrated. By providing the guide portion 40 for positioning the supporting insulating plate 22, the position of the supporting insulating plate 22 can be stabilized, and the effect of reducing the electric field concentration provided with the notch 22a can be ensured.

(Fifth embodiment)
A gas-insulated load tap switching device according to a fifth embodiment will be described with reference to the drawings. In the first embodiment, it has been described that the notch 22a can prevent the inner shield member 14 from being damaged by forming the supporting insulating plate 22 with flexible paper phenol. In the fifth embodiment, a description will be given of a configuration example for preventing damage to the inner shield member 14 even when the support insulating plate 22 is formed of a material having high hardness such as, for example, FRP (fiber reinforced plastic). As one configuration example, as shown in FIG. 12, a portion of the inner peripheral surface of the inner shield member 14 facing the support insulating plate 22 made of FRP is covered with a soft insulator 30. As another configuration example, as shown in FIG. 13, the side of the support insulating plate 22 made of FRP facing the internal shield member 14 is covered with a soft insulator 30. The soft insulator 30 shown in FIGS. 12 and 13 is not limited to a specific material, but may be made of a material softer than the material forming the supporting insulating plate 22. As such a soft insulator 30, for example, PTFE (polytetrafluoroethylene) may be used.

  As described above, even when the supporting insulating plate 22 is made of FRP having high hardness, the notch is formed by covering any one of the opposing surfaces of the supporting insulating plate 22 and the inner shield member 14 with the soft insulator 30. It is possible to prevent the inner shield member 14 from being damaged by 22a. Accordingly, it is possible to prevent the metal powder generated from the inner shield member 14 from flowing into the gas container 2c and to prevent the ground insulation performance from being lowered. Furthermore, the strength of the supporting insulating plate 22 can be improved by configuring the supporting insulating plate 22 with a member having high hardness.

  As in the case of the paper phenol, the notch 22a of the supporting insulating plate 22 can be prevented from damaging the inner shield member 14. Thus, it is possible to prevent the metal powder generated due to the damage of the inner shield member 14 from flowing into the gas container 2c, and the ground insulation performance from being lowered.

(Sixth embodiment)
A gas-insulated load tap switching device according to a sixth embodiment will be described with reference to the drawings. As shown in FIG. 14, in the sixth embodiment, instead of providing notches 22 a in the support insulating plate 22, the second internal shield member 23 is provided on the side of the support insulating plate 22 opposite to the internal shield member 14. Are disposed adjacent to the supporting insulating plate 22. The second inner shield member 23 is an annular conductive member smaller than the inner shield member 14. The second inner shield member 23 has a straight portion and a curved surface similarly to the inner shield member 14, and has a shape in which the J-shape is reversed left and right in a radial cross-sectional view. The second inner shield member 23 is arranged at the same height position as the inner shield member 14 with the curved portion facing the inside of the gas container 2a. That is, the second inner shield member 23 is disposed so as to be line-symmetric with the inner shield member 14 with the support insulating plate 22 interposed therebetween in a radial cross-sectional view.

  In such a configuration, since the support insulating plate 22 does not have the notch 22a, a wedge-shaped space is formed between the support insulating plate 22 and the inner shield member 14. However, since the second inner shield member 23 is disposed on the opposite side of the supporting insulating plate 22, a wedge-shaped space is similarly formed between the supporting insulating plate 22 and the second inner shielding member 23. Will be done. As a result, as shown in FIG. 15, the concentration of the electric field between the inner shield members 14 of the supporting insulating plate 22 is reduced, and the ground insulation performance can be improved. Specifically, the electric field value can be reduced by about 49% as compared with the conventional example of FIG. Further, since the supporting insulating plate 22 is not cut out, the strength of the supporting insulating plate 22 can be maintained. The second inner shield member 23 may be any member as long as it can reduce the electric field concentration of the inner shield member 14. The second inner shield member 23 has a shape and an installation that are line-symmetric with the inner shield member 14 shown in FIGS. Not limited to location. The shape and installation position of the second inner shield member 23 that are appropriate for reducing the concentration of the electric field of the inner shield member 14 can be appropriately determined.

(Other embodiments)
The above embodiments have been presented by way of example in the present specification, and are not intended to limit the scope of the invention. That is, the present invention can be implemented in other various forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modified examples thereof are included in the scope and gist of the invention, and are also included in the invention described in the claims and equivalents thereof.

  In the third embodiment, the projecting portion 22c is provided in the support insulating plate in which the notch 22b reaching the upper end of the support insulating plate is formed, but the present invention is not limited to this. For example, the overhanging portion 22c may be provided on the support insulating plate 22 in which the notch 22a in which only the portion near the curved surface portion 14b of the inner shield member 14 is notched is formed. Similarly, the guide portion 40 described in the fourth embodiment may be formed on a supporting insulating plate in which the notch 22a is formed. Similarly, the soft insulator 30 described in the fifth embodiment may cover the supporting insulating plate 22 having the notch 22b formed therein and the inner shield 14 facing the supporting insulating plate 22.

DESCRIPTION OF SYMBOLS 1 ... Transformer tank 2 ... Gas insulation type tap switching device at the time of load 2a ... Switching switch 2b ... Tap selector 2c ... Gas container 3,4 ... Insulating gas 6 ... Head cover 7 ... Seal holding ring 8 ... Seal member 9 ... upper shield plate 10 ... lower shield plate 11 ... first outer shield member 12 ... plane portion 13 ... insulating cylinder 14 ... inner shield member 14a ... linear portion 14b ... curved surface portion 15 ... second outer shield member 20 ... energy storage Device 21 Drive shaft 22 Support insulating plates 22a and 22b Notch 22c Projecting portion 23 Second internal shield member 30 Soft insulator 40 Guide portion d Clearance S Wedge-shaped space

Claims (10)

A gas container in which an opening is formed at the upper end and a switching switch is arranged inside, and an insulating gas is sealed,
A head cover fitted into the opening of the gas container,
A sealing member for sealing between the gas container and the head cover,
A seal pressing member for pressing the seal member,
An inner shield member having a curved surface portion covering a lower end portion of the seal holding member,
A support insulating member attached to an outer peripheral portion of the switching switch, an upper end portion disposed adjacent to the inner shield member, and a notch forming a predetermined gap between the inner shield member and a curved surface portion; A gas-insulated on-load tap switching device, comprising: a plate;   2. The gas-insulated on-load tap switching device according to claim 1, wherein the cutout is formed by cutting out a portion near the curved surface of the support insulating plate. 3.   The notch extends from the vicinity of the curved surface portion of the supporting insulating plate to the upper end of the supporting insulating plate, and the notch makes the upper end of the supporting insulating plate narrower than the lower end. 3. The gas-insulated load tap changer according to claim 2, wherein:   The notch is formed on a side of the support insulating plate facing the inner shield member, and the support insulating plate protrudes toward the inside of the gas container on a side opposite to a side where the notch is provided. 4. The gas-insulated on-load tap switching device according to claim 1, further comprising an overhang portion.   The gas-insulated on-load tap switching device according to claim 4, wherein the overhang portion has the same length and width as the notch.   The gas according to any one of claims 1 to 5, further comprising a guide portion provided on an outer peripheral side of a bottom portion of the gas container and positioned to contact the support insulating plate to position the support insulating plate. Insulation type tap change device at load.   7. The gas-insulated type tap changer according to claim 1, wherein the supporting insulating plate is made of paper phenol. 8.   The said support insulating plate is comprised by fiber reinforced plastics, The part which opposes the said support insulating plate of the said internal shield member is covered with the soft insulating material, The Claims 1-6 characterized by the above-mentioned. 2. A gas-insulated load tap changer according to claim 1.   The supporting insulating plate is made of fiber reinforced plastic, and a side of the supporting insulating plate facing the inner shield member is covered with a soft insulating material. Item 2. The gas insulated type tap switching device according to item 1. A gas container in which an opening is formed at the upper end and a switching switch is arranged at the bottom, and an insulating gas is sealed,
A head cover fitted into the opening of the gas container,
A sealing member for sealing between the gas container and the head cover,
A seal pressing member for pressing the seal member,
And the shield member that have a curved portion for covering the lower end portion of the seal pressing member,
A support insulating plate attached to an outer peripheral portion of the switching switch, and an upper end portion is disposed adjacent to the inner shield member,
Said support on the side opposite to the front Symbol within shield member of the insulating plate, said insulating support and a second internal shield member disposed adjacent to the plate, the gas-insulated load tap switching device characterized by having a .