WO2023037468A1

WO2023037468A1 - Switching device, dc breaker device, and dc breaker system

Info

Publication number: WO2023037468A1
Application number: PCT/JP2021/033137
Authority: WO
Inventors: 隆昭村田; 寿彰松本; 亮太菅沼; 芳明網田; 芳充丹羽; 崇裕石黒; 久生宮崎; 学史吉田; 重哉木村
Original assignee: 株式会社東芝; 東芝エネルギーシステムズ株式会社
Priority date: 2021-09-09
Filing date: 2021-09-09
Publication date: 2023-03-16
Also published as: JPWO2023037468A1; JP7466789B2

Abstract

A switching device according to an embodiment comprises: a first electrode; a second electrode provided apart from the first electrode; a plasma switch that includes a first grid provided between the first electrode and the second electrode, and a second grid provided between the first grid and the second electrode; and an outer shell part that is provided outside the plasma switch, and forms a sealed space with the plasma switch. The first electrode includes: a hollow cathode part in which the plasma switch generates a negative glow during glow discharge; and a magnetic-field-generating unit that is provided around the hollow cathode part, and that generates a magnetic field that intersects the electric field between the negative glow and the first electrode. The hollow cathode part includes at least one material from among B, C, Al, Si and Ga.

Description

Switching devices, DC interrupters and DC interrupting systems

Embodiments of the present invention relate to switching devices, DC interrupting devices, and DC interrupting systems.

There is a switching device that uses a plasma switch. It is expected that the application range will be expanded by improving the current capacity of the plasma switch.

U.S. Pat. No. 5,828,176 Japanese Patent No. 6430294

Embodiments provide high-performance switching devices, DC interrupting devices, and DC interrupting systems.

A switching device according to an embodiment includes a first electrode, a second electrode provided apart from the first electrode, a first grid provided between the first electrode and the second electrode, and the first electrode. 1 grid and a second grid provided between the second electrode; and an outer shell provided outside the plasma switch and forming a closed space between the plasma switch and the plasma switch Prepare. The first electrode includes a hollow cathode portion for generating a negative glow during glow discharge by the plasma switch, and a magnetic field that is provided around the hollow cathode portion and intersects an electric field between the negative glow and the first electrode. and a magnetic field generator that generates a The hollow cathode portion includes at least one material selected from B, C, Al, Si and Ga.

1 is a schematic cross-sectional view illustrating a switching device according to a first embodiment; FIG. FIG. 2 is a schematic plan view taken along line AA' of FIG. 1; 2 is a schematic enlarged cross-sectional view illustrating part of the switching device of the first embodiment; FIG. 4A and 4B are schematic enlarged cross-sectional views for explaining the operation of the switching device of the first embodiment; FIG. FIG. 5 is a schematic enlarged cross-sectional view of part B of FIG. 4 for explaining the operation of the switching device of the first embodiment; 6A to 6C are schematic equivalent circuit diagrams for explaining the operation of the switching device of the first embodiment. 4 is a schematic equivalent circuit diagram for explaining the operation of the switching device of the first embodiment; FIG. FIG. 10 is a schematic cross-sectional view illustrating part of a switching device according to a second embodiment; FIG. 9A is a schematic plan view illustrating part of the switching device of the second embodiment. FIG. 9(b) is a schematic cross-sectional view taken along line CC' in FIG. 9(a). FIG. 11 is a schematic enlarged cross-sectional view for explaining the operation of the switching device of the second embodiment; FIG. 11 is a schematic cross-sectional view illustrating a part of a switching device according to a third embodiment; FIG. 12(a) is a schematic cross-sectional view taken along line DD' of FIG. FIG. 12(b) is a schematic cross-sectional view taken along line FF' of FIG. FIG. 12(c) is a schematic cross-sectional view taken along line GG' of FIG. FIG. 12B is a schematic enlarged cross-sectional view of part J of FIG. 12A for explaining the operation of the switching device of the third embodiment; 14(a) to 14(d) are schematic diagrams for explaining the operation of the switching device of the third embodiment. FIG. 11 is a schematic block diagram illustrating a DC interrupting device according to a fourth embodiment; FIG. 11 is a schematic equivalent circuit diagram illustrating part of a DC interrupting device of a fourth embodiment; FIG. 11 is a schematic block diagram for explaining the operation of the DC interrupting device of the fourth embodiment; It is an example of a typical timing chart for explaining operation of the direct-current interruption device of a 4th embodiment. 19(a) and 19(b) are schematic block diagrams for explaining the operation of the DC interrupter of the fourth embodiment. 20(a) and 20(b) are schematic block diagrams for explaining the operation of the DC interrupter of the fourth embodiment. FIG. 11 is a schematic block diagram illustrating a DC interrupting device according to a fifth embodiment; FIG. 11 is a schematic block diagram illustrating a direct current interrupting system according to a sixth embodiment; FIG. 11 is a schematic block diagram illustrating a direct current interrupting system according to a seventh embodiment; FIG. 11 is a schematic block diagram illustrating a direct current interrupting device according to an eighth embodiment; FIG. 21 is a schematic perspective view illustrating a direct current interrupting device of an eighth embodiment; FIG. 12 is a schematic block diagram illustrating a DC interrupting device according to a ninth embodiment; FIG. 20 is a schematic block diagram illustrating a DC interrupting device according to a tenth embodiment; FIG. 20 is a schematic block diagram for explaining the operation of the DC interrupting device of the tenth embodiment;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
Note that the drawings are schematic or conceptual, and the relationship between the thickness and width of each portion, the size ratio between portions, and the like are not necessarily the same as the actual ones. Also, even when the same parts are shown, the dimensions and ratios may be different depending on the drawing.
In addition, in the present specification and each figure, the same reference numerals are given to the same elements as those described above with respect to the previous figures, and detailed description thereof will be omitted as appropriate.

(First embodiment)
FIG. 1 is a schematic cross-sectional view illustrating a switching device according to this embodiment.
In the following description, three-dimensional coordinate axes including X-axis, Y-axis and Z-axis may be used. A top plate 12 and a bottom plate 13 of the insulating container 10, which will be described later, are doughnut-shaped flat plate members, and the top plate 12 and the bottom plate 13 are provided so as to be substantially parallel to the XY plane. It is assumed that the insulating container 10 and the plasma switch 20 are cylindrical and extend along the Z-axis direction. A center line C10 is the center line of the cylinders of the insulating container 10 and the plasma switch 20 .
In the following description, for convenience, the positive direction of the Z-axis may be referred to as upward or upward, and the negative direction of the Z-axis may be referred to as downward or downward, but the direction of the Z-axis is limited to the direction of gravity. not a thing

The switching device 1 of this embodiment includes a plasma switch 20 . Plasma switch 20 further comprises insulating container 10 and hydrogen storage metal 20H. At least part of the plasma switch 20 is housed in the insulating container 10 . The insulating container 10 is an outer shell of the switching device 1 and is an example thereof.

The insulating container 10 includes, for example, an insulating cylinder 11, a top plate 12 and a bottom plate 13. The insulating cylinder 11 is a cylindrical insulator. The insulating cylinder 11 is made of an insulating material having sufficient strength, such as FRP (Fiber Reinforced Plastics) or ceramic.

The top plate 12 is a doughnut-shaped flat plate member including the opening 12H when viewed from the XY plane. The opening 12H is provided around the center that intersects the centerline C10. Like the top plate 12, the bottom plate 13 is also a doughnut-shaped flat plate member including an opening (not shown). The diameters of these openings are provided according to the diameter of the plasma switch 20 when viewed from the XY plane. The top plate 12 is connected to the upper end of the insulating cylinder 11 . The bottom plate 13 is connected to the lower end of the insulating cylinder 11 .

The top plate 12 and the bottom plate 13 are conductive and made of metal, for example. A first terminal T1 is connected to the bottom plate 13 , and a second terminal T2 is connected to the top plate 12 . By interposing the insulating cylinder 11 between the top plate 12 and the bottom plate 13, the top plate 12 and the bottom plate 13 are insulated. A sealed space is formed between the insulating container 10 and the plasma switch 20 by providing the plasma switch 20 in the openings of the top plate 12 and the bottom plate 13 . The sealed space is filled with an insulating gas 10G, and the insulating container 10 functions as a pressure container filled with the insulating gas 10G. The insulating gas 10G is, for example, sulfur hexafluoride (SF ₆ ) gas or the like.

The insulating container 10 is manufactured as an airtight container by joining the insulating cylinder 11, the top plate 12 and the bottom plate 13 by brazing welding, for example.

An insulating fold 14 is provided on the outer peripheral portion of the insulating cylinder 11 . The insulating pleats 14 have, for example, polymeric creepage surfaces. The insulating folds 14 are, for example, accordion-shaped flexible tubes. The insulating folds 14 are easily deformable, protect the outer periphery of the insulating cylinder 11 , and secure the creepage distance between the top plate 12 and the bottom plate 13 .

A support member 17 is provided inside the insulating container 10 . The support member 17 is connected to the top plate 12 via a sealing flange 30 provided around the opening 12H. The support member 17 and the sealing flange 30 are conductors, for example made of metal.

The plasma switch 20 is inserted through an opening in the bottom plate 13 and connected to the support member 17 via the upper electrode 21U. The plasma switch 20 is connected to the bottom plate 13 via a sealing flange 31 provided around the opening of the bottom plate 13 . The sealing

flanges

30 and 31 are conductors, the first electrode 22 of the plasma switch 20 is electrically connected to the first terminal T1 through the bottom plate 13, and the second electrode 23 is connected through the top plate 12. is electrically connected to the second terminal T2.

The plasma switch 20 includes sidewalls 21S, a first electrode 22, a second electrode 23, a first grid 26, and a second grid 27. The side wall 21S is a cylindrical member. The side wall 21S is provided inside the insulating container 10 . The sidewall 21S has an upper end connected to the second electrode 23 and a lower end connected to the first electrode 22 . The side wall 21S is made of an insulating material, such as ceramic. The first electrode 22 and the second electrode 23 are insulated inside the insulating container 10 by the side wall 21S.

The first electrode 22 is a bottomed cylindrical conductive member extending along the Z-axis. The diameter of the circle of the first electrode 22 in XY plan view is substantially equal to the diameter of the circle of the side wall 21S in XY plan view. An upper portion of the first electrode 22 is inserted through an opening in the bottom plate 13 . The upper end of the first electrode 22 is connected to the side wall 21S inside the insulating container 10 .

The second electrode 23 is a bottomed cylindrical conductive member extending in the Z-axis direction. The diameter of the circle of the second electrode 23 in XY plan view is set smaller than the diameter of the circle of the first electrode 22 and the side wall 21S in XY plan view. The upper end portion of the second electrode 23 includes a brim-shaped portion that is smoothly bent toward the outside of the circumference. It is connected.

The positions of the first electrode 22, the side wall 21S and the second electrode 23 are determined so that the center lines C10 substantially match each other. The first electrode 22 and the second electrode 23 are arranged to face each other.

The first electrode 22 includes a first layer 22A and a second layer 22D. The first layer 22A is formed on the second layer 22D. The first layer 22A is provided inside the bottomed cylindrical first electrode 22 . The second layer 22D is provided outside the bottomed cylindrical first electrode 22 . The upper end of the first electrode 22 is inserted through an opening in the bottom plate 13 and connected to the bottom plate 13 by a sealing flange 31 . Although the first layer 22A is a conductor, it is thin, so it is illustrated with a thin dashed line to avoid complication of the drawing.

The first layer 22A contains, for example, at least one material selected from B, C, Al, Si and Ga. The first electrode 22 is formed, for example, by vapor deposition using these raw materials. The second electrode 23 includes, for example, at least one material selected from Ni, Cr, Mo, Cu, Ag, Au, Fe, Ir, and Pt.

The first layer 22A of the first electrode 22 may be made of, for example, a nitride semiconductor such as Al or Ga, an oxide semiconductor, diamond, graphite, sintered diamond, alumina cement, or the like. The second electrode 23 may be, for example, graphite, which is a conductor with a high melting point.

A current density increasing portion 60 is provided in a portion of the first electrode 22 exposed from the insulating container 10 . The current density increasing portion 60 includes a hollow cathode portion 62 and permanent magnets 64 . The hollow cathode portion 62 is provided over the circumference of the circle in the XY plane view of the first electrode 22 and is formed of two fold-shaped electrodes projecting in the radial direction. The two pleated electrodes face each other and form a hollow cathode. In this example, a plurality of hollow cathode portions 62 are provided so as to be stacked in the Z-axis direction. A permanent magnet 64 is provided between two adjacent hollow cathode portions 62 .

The permanent magnet 64 is, for example, a rare earth magnet. The permanent magnet 64 is, for example, a neodymium magnet, a samarium-cobalt magnet, or the like.

2 is a schematic plan view taken along line AA' of FIG. 1. FIG.
FIG. 2 shows an arrangement example of the permanent magnets 64 provided on the hollow cathode portion 62 .
As shown in FIG. 2 , the plurality of permanent magnets 64 are provided on the second layer 22D of the first electrode 22 , which protrudes outward in folds from the circumference of the circle in the XY plan view. The permanent magnets 64 are arranged radially. The permanent magnet 64 is arranged so that one magnetic pole faces the outside of the circle and the other magnetic pole faces the inside of the circle. In this example, the magnetic poles facing outward are N poles and the magnetic poles facing inward are S poles.

FIG. 3 is a schematic enlarged cross-sectional view illustrating a part of the switching device of this embodiment.
An enlarged view of the current density increasing portion 60 is shown in FIG.
As shown in FIG. 3, in the current density increasing portion 60, the first electrode 22 includes a plurality of hollow cathode portions 62, and the plurality of hollow cathode portions 62 are formed so as to be stacked in the Z-axis direction. . The multiple hollow cathode sections 62 each include two opposing electrodes 22A1 and 22A2. These electrodes 22A1 and 22A2 are formed by bending the first electrode 22 and are electrically connected. The electrodes 22A1 and 22A2 are arranged substantially parallel with an interval a0. The distance a0 between the electrodes 22A1 and 22A2 in the Z-axis direction is about twice the length of the ion sheath during glow discharge. The ion sheath during glow discharge refers to a dark portion generated near the first electrode 22, which is the cathode, and the ion sheath is mostly formed by ions of the discharge gas 20G.

The permanent magnet 64 is provided around the first electrode 22 and provided between two hollow cathode portions 62 adjacent in the Z-axis direction. Although not shown, the permanent magnet 64 is fixed between two adjacent hollow cathode portions 62 by, for example, an insulating adhesive.

In the hollow cathode portion 62 , the surface on which the hollow cathode is formed is the surface of the first electrode 22 on which the first layer 22A is formed, and the hollow cathode is formed inside the plasma switch 20 . The permanent magnet 64 is provided on the side of the surface of the first electrode 22 on which the second layer 22D is provided, and is provided outside the first electrode 22 .

The arrangement of the permanent magnets 64 is set so that the magnetic lines of force generated by the respective permanent magnets 64 reinforce the magnetic field within the hollow cathode portion 62 . For example, the arrangement of the permanent magnets 64 is set through experiments, simulations, etc. so that the magnitude and direction of the magnetic field in the hollow cathode portion 62 are appropriate.

Returning to FIG. 1, the description continues.
In the plasma switch 20, the space surrounded by the first electrode 22, the second electrode 23, and the sidewall 21S is a closed space, and the plasma switch 20 is hermetically sealed from the space outside the first electrode 22. An opening is provided in the lower portion of the first electrode 22, and the sealing tube 21P is connected to the opening. A sealed space inside the plasma switch 20 is filled with a discharge gas 20G via a sealing tube 21P. The discharge gas 20G is a rarefied inert gas such as hydrogen, deuterium, helium, or argon. The sealing tube 21P is hermetically sealed after the discharge gas 20G is introduced so that the inside of the plasma switch 20 has a predetermined pressure P. The predetermined pressure P is less than 1 atmosphere, for example, 1 Torr or less. The inside of the plasma switch 20 is in a decompressed state. 1 Torr is equal to 1/760 atmosphere and approximately equal to 133 Pa.

In the plasma switch 20, when the breakdown voltage is plotted against the pd product, which is the product of the pressure P and the discharge gap d, the plotted curve is U-shaped. The U-shaped curve is called the Paschen curve, and the plasma switch 20 operates to the left of the minimum of the U-shaped curve. When the pd product is small, the firing voltage becomes high and the plasma tends to be turned off. Also, near the minimum value of the U-shaped Paschen curve, the plasma switch tends to be turned on.

A first grid 26 is arranged between the first electrode 22 and the second electrode 23 . A second grid 27 is arranged between the first grid 26 and the second electrode 23 . The portions of the first grid 26 and the second grid 27 provided between the first electrode 22 and the second electrode 23 are both mesh-like.

By setting a large discharge gap d between the first grid 26 and the first electrode 22 and operating near the minimum value of the Paschen curve, a large-current plasma source is continuously maintained. A second grid 27 is provided to extract electrons from this plasma source.

In the off state, the potential of the second grid 27 is zero or negative. By raising the potential of the second grid 27 to, for example, the same potential as the first grid 26, electrons pass from the plasma source between the first grid 26 and the first electrode 22 through the second grid 27 to the second electrode. You can reach up to 23. Therefore, the plasma switch 20 is turned on. After that, the plasma switch 20 is turned off by lowering the potential of the second grid 27 to zero or a negative potential. The reason why the plasma switch 20 can be turned off is that the discharge gap d between the second grid 27 and the second electrode 23 is small and the pd product is small, so the discharge starting voltage can be increased, resulting in a non-sustained discharge. because The discharge gap d is appropriately designed so that the discharge between the second grid 27 and the second electrode 22 cannot be sustained without injection of electrons from the plasma source.

In this example, the sidewall 21S consists of four parts. That is, the side wall 21S includes a first side wall portion 21S1, a second side wall portion 21S2, a third side wall portion 21S3, and a fourth side wall portion 21S4. , are provided in this order. The upper end of the first electrode 22 and the first side wall portion 21S1 are connected by a joint portion D11. The first side wall portion 21S1 and the second side wall portion 21S2 are connected by a joint portion D12. The second side wall portion 21S2 and the third side wall portion 21S3 are connected by a joint portion D13. The third side wall portion 21S3 and the fourth side wall portion 21S4 are connected by a joint portion D15. The upper ends of the fourth side wall 21S4 and the second electrode 23 are connected by a junction D14. Each part of the first electrode 22, the second electrode 23, and the side wall 21S is airtightly connected by joints D11 to D15. For example, brazing is used to form the joints D11 to D15.

The first grid 26 is airtightly connected to the first shield 26S via the joint D12. The first shield 26S is provided so as to surround the plasma switch 20 inside the insulating container 10 . The second grid 27 is airtightly connected to the second shield 27S via the joint D13. The second shield 27S is provided so as to surround the plasma switch 20 inside the insulating container 10 .

The first shield 26S and the second shield 27S are each connected to two leads 13L and drawn out of the switching device 1 through through holes provided in the bottom plate 13 . The first grid 26 is electrically connected to the third terminal T3 for external circuit connection via the first shield 26S. The second grid 27 is electrically connected to a fourth terminal T4 for external circuit connection via a second shield 27S.

A floating potential shield 28 is provided above the second grid 27 . The floating potential shield 28 is a torus-shaped solid conductive member that is thick in the Z-axis direction and provided in the closed space of the plasma switch 20 . The floating potential shield 28 is a floating potential shield that is not connected to any potential of the first electrode 22 , the second electrode 23 , the first grid 26 and the second grid 27 . Floating potential outer shield 28K is connected to floating potential shield 28 via junction D15. An outer shield 28K is provided inside the insulating container 10 so as to surround the plasma switch 20 .

An upper shield 32 is provided between the upper electrode 21U and the support member 17 . The upper shield 32 is drawn out into the insulating container 10 and surrounds the upper electrode 21U while maintaining the airtightness of the insulating container 10 .

These shield structures are provided to mitigate the electric field inside the plasma switch 20 and inside the insulating container 10 .

The hydrogen storage metal 20H is provided below the plasma switch 20. An opening is provided in the lower part of the first electrode 22 separately from the opening for the sealing pipe 21P, and the connecting pipe 21H is connected to the opening. A hydrogen storage metal 20H is provided at the end of the connecting pipe 21H. The hydrogen storage metal 20H stores hydrogen that creates the atmosphere of the discharge gas 20G introduced into the closed space of the plasma switch 20. FIG.

Although not shown, the hydrogen storage metal 20H includes, for example, a metal body that stores hydrogen and a heater that heats the metal body. A fifth terminal T5 and a sixth terminal T6 are connected to both ends of the heater via leads 50L. Hydrogen storage metal 20H is an example of a hydrogen storage part.

The operation of the switching device 1 of this embodiment will be described.
FIG. 4 is a schematic enlarged cross-sectional view for explaining the operation of the switching device of this embodiment.
In FIG. 4, the current density increasing portion 60 is shown enlarged and the lines of magnetic force generated by the permanent magnet 64 are indicated by curved arrows. A straight arrow schematically indicates the direction of the magnetic field H generated in the hollow cathode portion 62 .
As shown in FIG. 4, the permanent magnet 64 has an S pole directed toward the center line C10 of the plasma switch 20 and an N pole directed outward from the center line C10. Magnetic lines of force of the permanent magnet 64 are generated to exit from the north pole and enter the south pole. Since the permanent magnet 64 is arranged between two hollow cathode portions 62 adjacent to each other in the Z-axis direction, the magnetic field H synthesized by the magnetic lines of force of at least the two upper and lower permanent magnets 64 is generated inside the hollow cathode portion 62 . generated.

In the switching device 1 of this embodiment, the first electrode 22, which is the cathode of the plasma switch 20, includes the first layer 22A. The first layer 22A contains at least one material selected from B, C, Al, Si, and Ga, and is, for example, nitride semiconductor such as AlN or GaN, diamond, or the like. The first layer 22A is made of a material having such a negative electron affinity, and can increase the secondary electron emission coefficient. Thus, higher current densities are achieved than in glow discharges with cathodes without these materials.

　In the switching device 1 of the present embodiment, the first electrode 22 includes the current density increasing portion 60 . Current density increasing portion 60 includes a hollow cathode portion 62 . As described with reference to FIG. 3, the hollow cathode section 62 includes the electrodes 22A1 and 22A2 facing each other substantially in parallel, and the distance a0 between the electrodes 22A1 and 22A2 is about twice the ion sheath length during glow discharge. It is said that Therefore, the electrodes 22A1 and 22A2 function as hollow cathodes, and negative glow GN is formed in the hollow cathode portion 62, so that the current density can be improved.

FIG. 5 is a schematic enlarged cross-sectional view of the B portion of FIG. 4 for explaining the operation of the switching device of this embodiment.
FIG. 5 shows a negative glow GN formed between two opposing electrodes 22A1, 22A2. FIG. 5 also shows the electric field E generated between the negative glow GN and the electrode 22A1 and the electric field E generated between the negative glow GN and the electrode 22A2.
As shown in FIG. 5, the negative glow GN is generated substantially parallel to and facing the electrodes 22A1 and 22A2. Therefore, the electric field E generated between the negative glow GN and the electrodes 22A1 and 22A2 is generated in a direction substantially perpendicular to the electrodes 22A1 and 22A2, respectively. The generated electric field E is generated in a direction from the negative glow GN toward the electrodes 22A1 and 22A2.

The arrangement of the permanent magnets 64 is adjusted so that the magnetic field H intersects the direction of the electric field E. Preferably, the permanent magnets 64 are arranged such that the magnetic field H is perpendicular to the electric field E. FIG.

Since the electric field E and the magnetic field H intersect, the electrons traveling in the electric field E receive the Lorentz force in the direction perpendicular to the electric field E and the magnetic field H. Therefore, the electrons reach the negative glow GN from the electrodes 22A1 and 22A2 while spirally rotating, so that the traveling distance of the electrons increases. This is the same as substantially increasing the distance between the negative glow GN and the electrodes 22A1 and 22A2. Therefore, the current density increasing unit 60 can increase the pd product in the Paschen curve without increasing the pressure in the plasma switch 20, so that ionization due to electron collision can be increased and the current density can be improved.

6A to 7 are schematic equivalent circuit diagrams for explaining the operation of the switching device of this embodiment.
6(a) to 6(c) show the plasma switch 20 including the first electrode 22, the second electrode 23, the first grid 26 and the second grid 27 as equivalent circuit diagrams.
As shown in FIG. 6(a), the plasma switch 20 is in the initial state, and no potential is applied to the first terminal T1 to the fourth terminal T4.

FIG. 6(b) is a schematic diagram showing the plasma switch 20 in the first state ST1. The first terminal T1 is set to the first potential V1, the second terminal T2 is set to the second potential V2, the third terminal T3 is set to the third potential V3, and the fourth terminal T4 is set to the fourth potential V4. is set to The first state ST1 is a non-conducting state and the plasma switch 20 is off.

In the first state ST1, the relationship among the first potential V1, the second potential V2, the third potential V3 and the fourth potential V4 is set as follows. The second potential V2 is higher than the first potential V1. That is, V1<V2. The third potential V3 is a potential between the first potential V1 and the second potential V2. That is, V1<V3<V2. The fourth potential V4 is lower than the third potential V3. That is, V4<V3. The first potential V1 is, for example, a negative potential or a ground potential. The second potential V2 is, for example, a positive potential. The third potential V3 is, for example, an intermediate potential. The fourth potential V4 is, for example, a negative potential.

FIG. 6(c) is a schematic diagram showing the plasma switch 20 in the second state ST2.
FIG. 6(c) is a schematic diagram showing the plasma switch 20 in the second state ST2. The potentials of the first terminal T1, the second terminal T2, and the third terminal T3 are the same potentials as in the first state ST1. That is, the first terminal T1 is set to the first potential V1, the second terminal T2 is set to the second potential V2, and the third terminal T3 is set to the third potential V3.

In the second state ST2, the fourth terminal T4 is set to the fifth potential V5. The fifth potential V5 is higher than the third potential V3. That is, V3<V5. The fifth potential V5 is, for example, a positive potential. The second state ST2 is a conducting state, and the plasma switch 20 is turned on.

The current flowing between the first terminal T1 and the second terminal T2 in the second state ST2 is larger than the current flowing between the first terminal T1 and the second terminal T2 in the first state ST1. The first state ST1 is, for example, a high resistance state. The second state ST2 is, for example, a low resistance state.

That is, in the plasma switch 20, the potentials of the first terminal T1 to the third terminal T3 are set to V1 to V3, and the potential of the fourth terminal T4 is switched between V4 and V5, thereby switching the non-conducting state and the conducting state. and can be switched.

The switching device 1 is, for example, a large-current high-voltage DC circuit breaker. The first electrode 22 is, for example, a cathode, and the second electrode 23 is, for example, an anode.

When the plasma switch 20 is in the first state ST1, a first plasma SP1P is generated in the first space SP1 between the first electrode 22 and the first grid 26. At this time, the first grid 26 and the second electrode 23 are in an insulated state. Therefore, the plasma switch 20 in the first state ST1 becomes non-conducting between the first terminal T1 and the second terminal T2.

When the plasma switch 20 is in the second state ST2, the second plasma SP2P is generated in the second space SP2 between the first grid 26 and the second grid 27, and the second plasma SP2P is generated between the second grid 27 and the second electrode 23. A third plasma SP3P is generated in the three-space SP3. Therefore, the plasma switch 20 in the second state becomes conductive between the first terminal T1 and the second terminal.

A procedure for filling the plasma switch 20 with hydrogen will be described.
FIG. 7 is a schematic equivalent circuit diagram for explaining the operation of the switching device of this embodiment.
The inside of the plasma switch 20 is preliminarily filled with hydrogen together with a gas such as argon for the purpose of increasing the voltage, creating a reducing atmosphere, or compensating for the consumption of the hydrogen termination of the diamond semiconductor. ing.

The hydrogen storage metal 20H supplements the hydrogen in the plasma switch 20. By heating the hydrogen storage metal 20H with a heater (not shown), hydrogen is taken out from the hydrogen storage metal 20H and hydrogen in the plasma switch 20 is replenished. A fifth terminal T5 and a sixth terminal T6 are terminals for supplying power to a heater provided in the hydrogen storage metal 20H. Since hydrogen is supplied by heating the hydrogen storage metal 20H, the pressure in the plasma switch 20 can be stably maintained more easily than when hydrogen is supplied using a valve or the like.

Effects of the switching device 1 of the present embodiment will be described.
The switching device 1 of this embodiment includes a plasma switch 20 in which a first electrode 22 includes a first layer 22A. The first electrode 22 is a cathode of the plasma switch 20, and the first layer 22A contains at least one material selected from B, C, Al, Si and Ga, and includes nitride semiconductors such as AlN and GaN. It is a wide bandgap semiconductor such as diamond, graphite, or sintered diamond, and is made of a material having negative electron affinity. Therefore, the secondary electron emission coefficient of the first electrode 22, which is a cathode, can be increased, and the current density of the plasma switch 20 can be improved. By doping the wide bandgap semiconductor to make it p-type or n-type, it is possible to increase the number of current bearers such as electrons or holes, and to further improve the current density.

The first electrode 22 includes a current density increasing portion 60. Current density increasing portion 60 includes a hollow cathode portion 62 . The hollow cathode portion 62 constitutes a hollow cathode with the electrodes 22A1 and 22A2 facing each other. In the hollow cathode portion 62, a negative glow GN is formed during glow discharge, and the hollow cathode portion 62 functions as a hollow cathode, so the current density of the plasma switch 20 can be improved.

The current density increasing section 60 includes magnetic field generating means with a permanent magnet 64 . The permanent magnet 64 generates a magnetic field H that intersects the electric field E generated between the negative glow GN formed within the hollow cathode and the electrodes 22A1 and 22A2. Electrons running in the hollow cathode receive the Lorentz force orthogonal to the electric field E and the magnetic field H and run spirally. Therefore, the traveling distance of the electrons is extended, and the pd product in the Paschen curve can be substantially increased without increasing the pressure in the plasma switch 20, so the current density of the plasma switch 20 can be improved. .

A plurality of hollow cathode portions 62 can be provided so as to be stacked in the Z-axis direction, and the current density of the plasma switch 20 can be further improved according to the number of layers.

The switching device 1 of this embodiment further includes a hydrogen storage metal 20H. The hydrogen storage metal 20H can be powered externally to fill the plasma switch 20 with hydrogen gas. Compared to the mechanical gas replenishment method, there is an advantage that gas replenishment can be performed easily.

The switching device 1 of this embodiment further includes an insulating container 10 . Since the insulating container 10 has an insulating gas 10G around the plasma switch 20, it becomes possible to coordinate insulation with the airtight structure of the plasma switch 20, and it is possible to apply the switching device 1 to high voltage applications. make it easier.

DC power transmission systems are attracting attention. For example, a direct-current multi-terminal power transmission system is considered promising as a system for integrating and transmitting electric power generated by wind power generation and solar power generation that are distributed over a long distance. In a DC multi-terminal power transmission system, for example, a DC interrupting device is provided for performing high-speed disconnection protection of a DC power transmission system in the unlikely event of an accident such as a DC ground fault or a DC short circuit.

A hybrid system that combines mechanical interruption and semiconductor element interruption has been developed for DC interruption devices (see, for example, Patent Document 2). A hybrid type direct-current circuit breaker needs to achieve high withstand voltage and large current, so it may become a huge structure as described below.

A DC transmission system is designed with a transmission voltage of several 100 kV in order to ensure transmission efficiency. In order to be applicable to such systems, the components of the DC interrupter must be of high voltage. In a hybrid DC interrupter, the semiconductor element interrupting circuit may be, for example, a unit in which power semiconductor elements such as IEGTs and IGBTs, capacitors, resistors, substrates, and the like are mounted. Since the withstand voltage of the power semiconductor element is several kV, it is necessary to connect the semiconductor element and the unit including the semiconductor element in series in order to apply it to the DC interrupting device having the withstand voltage of several 100 kV.

In order to ensure a certain level of insulation, interrupting circuits using semiconductor elements having such a series connection structure generally have a tower configuration in which shelves are piled up, and may become an extremely large device. In order to reduce the size of such a direct-current interrupting device, replacement of the semiconductor element with a plasma switch is under consideration.

The discharge characteristics inside the plasma switch enable a compact gap design based on the Paschen characteristics, and it is relatively easy to increase the voltage to several 100 kV. On the other hand, it has been a problem to secure a current capacity that can be applied to the DC interrupter.

In the switching device 1 of the present embodiment, as described above, the plasma switch 20 has the first electrode 22 serving as a cathode made of a material having negative electron affinity such as a wide bandgap semiconductor. Also, the first electrode 22 has a current density increasing portion 60 . Therefore, in the plasma switch 20, the current density can be dramatically improved, and the current capacity applicable to the DC interruption device can be realized.

When the plasma switch 20 is surrounded by the atmosphere, if the voltage is increased to several hundred kV, the dielectric support supporting the plasma switch 20 must be extended in order to coordinate the insulation of the outer creeping surface that is in contact with the atmosphere. and the device tends to be extremely long. For this reason, there is a problem that the size of the device increases.

In the switching device 1 of the present embodiment, at least a part of the plasma switch 20 is housed inside the insulating container 10 in which the insulating gas 10G is enclosed. Therefore, it is possible to maintain the airtightness of the insulating container 10 and the plasma switch 20 while coordinating the insulation, thereby realizing a high voltage without increasing the size.

(Second embodiment)
In the case of this embodiment, the configuration of the current density increasing section 260 is different from that of the other embodiments described above. The same reference numerals are given to the same components as in other embodiments, and detailed description thereof will be omitted as appropriate.
FIG. 8 is a schematic cross-sectional view illustrating a part of the switching device according to this embodiment.
FIG. 8 shows a schematic cross-sectional view of the plasma switch 220 that constitutes the switching device of this embodiment. Although this diagram does not show components corresponding to the insulating container 10 and the hydrogen storage metal 20H in the case of the above-described other embodiment that realizes high voltage, they can be provided in the same manner as in the case of the other embodiments. can be done.
As shown in FIG. 8, the plasma switch 220 includes sidewalls 221S, a first electrode 222, a second electrode 223, a first grid 226, and a second grid 227. As shown in FIG. The side wall 221S is a cylindrical insulating member. The sidewall 221S has an upper end connected to the second electrode 223 and a lower end connected to the bottom plate 215 . A first electrode 222 is provided on the bottom plate 215 so as to protrude into the plasma switch 220 . The first electrode 222 includes a current density increasing portion 260 . Current density increasing section 260 is provided in a closed space inside plasma switch 220 .

The first electrode 222, the second electrode 223 and the bottom plate 215 are circular conductive members in XY plan view. The side wall 221S, the first electrode 222 and the bottom plate 215 are circular with substantially the same diameter when viewed in the XY plane. smaller than diameter. The sidewalls 221S, the first electrode 222, the second electrode 223, and the bottom plate 215 are positioned relative to each other such that their centers parallel to the Z-axis substantially coincide with the centerline C20.

The internal space of the plasma switch 220 formed by the side wall 221S, the first electrode 222, the second electrode 223 and the bottom plate 215 is hermetically sealed and sealed with the discharge gas 20G. Although not shown, the bottom plate 215 is provided with a sealing tube for enclosing the discharge gas 20G in the internal space of the plasma switch 220, and the discharge gas 20G is enclosed from the sealing tube. Preferably, a hydrogen storage metal is coupled to the bottom plate 215 as in the other embodiments described above.

A first grid 226 is arranged between the first electrode 222 and the second electrode 223 . A second grid 227 is arranged between the first grid 226 and the second electrode 223 . The portions of the first grid 226 and the second grid 227 provided between the first electrode 222 and the second electrode 223 are both mesh-like.

The first electrode 222 and the bottom plate 215 are connected to each other. A first terminal T1 is connected to the bottom plate 215 , and the first electrode 222 is connected to the first terminal T1 via the bottom plate 215 . A second terminal T2 is connected to the second electrode 223 . The first grid 226 and the second grid 227 are connected to two leads 13L, respectively, and are connected to the third terminal T3 and the fourth T4.

The second electrode 223 smoothly protrudes inside the plasma switch 220 in the vicinity of the circumference of the circle in the XY plan view so as to relax the electric field inside the plasma switch 220 .

A configuration of the first electrode 222 will be described.
FIG. 9A is a schematic plan view illustrating a part of the switching device of this embodiment. FIG. 9(b) is a schematic cross-sectional view taken along line CC' in FIG. 9(a).
As shown in FIGS. 9A and 9B, the first electrode 222 is a bottomed cylindrical conductive member in the XY plan view. In this example, the flat portion 222E corresponding to the bottom is provided at the upper end of the cylindrical portion and housed in the closed space inside the plasma switch 220. As shown in FIG. Note that the portion corresponding to the bottom does not necessarily have to be flat.

A plurality of concave portions 262 are provided in the upper flat portion 222E of the second electrode 222 . In this example, the concave portion 262 has a substantially square shape in XY plan view, and two electrodes 222A1 and 222A2 are arranged to face each other. Electrodes 222A3 and 222A4 adjacent to the electrodes 222A1 and 222A2 are also arranged to face each other. In this example, the lower ends of electrodes 222A1-222A4 are electrically connected. The distance a0 between the electrodes 222A1 and 222A2 is about twice the length of the ion sheath formed in the glow discharge state, as in the other embodiments described above. The recess 262 functions as a hollow cathode.

In this example, the concave portion 262 has a substantially square shape when viewed from the XY plane, but it is not limited to a square shape and may have a substantially circular or elliptical shape. When the shape of the concave portion 262 in the XY plane view is substantially circular, the diameter of the circle is about twice the length of the ion sheath. Although two sets of counter electrodes are used in this example, one set of counter electrodes may be used.

The first electrode 222 includes a first layer 222A and a second layer 222D. The first layer 222A is formed on the second layer 222D. The first layer 222A is provided over at least the flat portion 222E at the upper end of the first electrode 222 and the electrodes 222A1 to 222A4. The first layer 222A is provided on the inner side of the plasma switch 220, and the second layer 222D may be exposed in other portions as in this example. The first layer 222A and the second layer 222D are formed of the same materials as the first layer 22A and the second layer 22D for the other embodiments described above.

A conductor wire is wound around the portion of the concave portion 262 that is outside the plasma switch 220, and a coil 266 is formed by the wound conductor wire. In this example, the power supply is connected so that the current flows counterclockwise when viewed in the XY plane.

The operation of the switching device of this embodiment will be described.
In the switching device of the present embodiment, the direction of the magnetic field H generated by the coil formed in the recess 262 intersects the electric field E generated in the recess 262, so that the traveling distance of electrons traveling in the electric field E is reduced. extend substantially.
FIG. 10 is a schematic enlarged cross-sectional view for explaining the operation of the switching device of this embodiment.
FIG. 10 shows in detail the configuration of the recess 262 formed in the first electrode 222 and the coil 266 provided around the recess 262 . In FIG. 10, the direction of the current flowing through the conducting wire forming the coil 266 is indicated by ● marks and X marks. ● indicates the negative direction of the Y-axis, and x indicates the positive direction of the Y-axis.
As shown in FIG. 10, when glow discharge is started, negative glow GN enters recess 262 . An electric field E is generated between the negative glow GN and the electrodes 222A1, 222A2. Since the electrodes 222A1 and 222A2 are provided substantially parallel to the Z-axis, the electric field E is generated substantially parallel to the X-axis in this figure.

A direct current flows through the coil 266 in the direction shown in the figure. For the conductors on the left side of the recess 262, magnetic field lines are generated counterclockwise around each conductor. In the conductors on the right side of the recess 262, magnetic field lines are generated clockwise around each conductor, and within the recess 262, a magnetic field H is generated by combining these magnetic field lines.

A magnetic field H is generated to intersect the electric field E, and preferably the configuration of the coils 266 is adjusted so that the magnetic field H is orthogonal to the electric field E. The distance between the recesses 262 in the XY plane view is appropriately set through experiments, simulations, or the like so that the magnetic field H generated in the recesses 262 is perpendicular to the electric field E. FIG.

The operation and effect of the switching device of this embodiment will be described.
In this embodiment, since the recess 262 provided in the first electrode 222 functions as a hollow cathode, the negative glow GN formed within the recess 262 improves the current density of the plasma switch 220 .

A magnetic field H that intersects the electric field E generated between the negative glow GN and the electrodes 222A1 and 222A2 can be generated in a coil 266 provided around the recess 262. Electrons running in the electric field E are subjected to the Lorentz force perpendicular to the electric field E and the magnetic field H, so they run spirally. Therefore, the distance traveled in the electric field is substantially increased, so the pd product in the Paschen curve can be increased, and the current density in the plasma switch 220 can be improved.

Since the first layer 222A is made of a material having a negative electron affinity as in the other embodiments described above, the secondary electron emission coefficient can be increased, and the current density in the plasma switch 220 can be increased. can be improved.

In the present embodiment, since the first electrode 222 and the second electrode 223 can be made into a circular plate shape, it is possible to facilitate processing and assembly of these members.

(Third Embodiment)
In the case of this embodiment, the configuration of the second electrode 322 is different from that in the other embodiments described above. The same constituent elements are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.
FIG. 11 is a schematic cross-sectional view illustrating a part of the switching device according to this embodiment.
FIG. 11 shows a schematic cross-sectional view of a plasma switch 320 that constitutes the switching device of this embodiment. Although this diagram does not show components corresponding to the insulating container 10 and the hydrogen storage metal 20H in the case of the above-described first embodiment that realizes high voltage, it is similar to the case of the first embodiment. can be provided.

As shown in FIG. 11, the plasma switch 320 includes a first electrode 322, a second electrode 323, a first grid 326, a second grid 327, a top plate 321U, and a bottom plate 321L. As will be described later, the first electrode 322 is a star-shaped cylindrical body in XY plan view. The upper end of the first electrode 322 is connected to the top plate 321U via the connecting portion 330. As shown in FIG. The connection portion 330 and the top plate 321U are made of an insulating material and are insulated from the first electrode 322 . A lower end of the first electrode 322 is connected to the bottom plate 321L via a connection portion 331 . The connection portion 331 and the bottom plate 321L are made of a conductive material, and the first electrode 322 is electrically connected to the first terminal T1 connected to the bottom plate 321L via the connection portion 331 and the bottom plate 321L. ing.

A space surrounded by the first electrode 322, the top plate 321U and the bottom plate 321L is a closed space into which the discharge gas 20G is introduced. Although not shown, the bottom plate 321L is provided with a sealing tube for enclosing the discharge gas 20G in the internal space of the plasma switch 320, and the discharge gas 20G is enclosed from the sealing tube. Preferably, a hydrogen storage metal is connected to the bottom plate 321L as in the other embodiments described above.

FIG. 12(a) is a schematic cross-sectional view taken along line DD' of FIG. FIG. 12(b) is a schematic cross-sectional view taken along line FF' of FIG. FIG. 12(c) is a schematic cross-sectional view taken along line GG' of FIG.
As shown in FIGS. 12(a) to 12(c), the first electrode 322 has a star shape in XY plan view and includes a current density increasing portion 360. As shown in FIG. The star shape is a circular shape having a center that intersects the center line C30 and radially protruding portions are provided along the circumference. A radially protruding portion is sometimes called a star-shaped protruding portion. The tubular first electrode 322 and the tubular second electrode 323 extending in the Z-axis direction are positioned relative to each other so that their centers in XY plan view substantially coincide with the center line C30 parallel to the Z-axis.

The current density increasing section 360 includes a hollow cathode section 362 and a coil 366. The hollow cathode portion 362 is provided on the star-shaped projecting portion of the first electrode 322 . That is, a plurality of hollow cathode portions 362 are provided over a circular circumference having a center that intersects the center line C30.

The first electrode 322 includes a first layer 322A and a second layer 322D, and the first layer 322A is provided on the second layer 322D. The first layer 322A is provided inside the plasma switch 320, and the second layer 322D is provided outside the plasma switch 320. As shown in FIG. The materials of the first layer 322A and the second layer 322D are the same as the materials of the first layer 22A and the second layer 22D, respectively, for the first embodiment described above.

A coil 366 is provided in each of the plurality of hollow cathode portions 362 . The coil 366 is provided so as to surround the hollow cathode portion 362 .

Returning to FIG. 11, the description continues.
The second electrode 323 is connected to the top plate 321U inside the plasma switch 320 by a support member 323U. A lead electrode 315L is connected to the first electrode 323, and the lead electrode 315L is drawn out of the plasma switch 320 from the top plate 321U. A second terminal T2 for external circuit connection is connected to the lead electrode 315L.

The second electrode 323 is a cylindrical conductive member, and has a circular shape with a center intersecting the center line C30 in XY plan view. A first grid 326 is provided between the first electrode 322 and the second electrode 323 . A second grid 327 is provided between the first grid 326 and the second electrode 323 . The first grid 326 and the second grid 327 have cylindrical shapes with different radii, and are provided so as to surround the second electrode 323 .

The first grid 326 and the second grid 327 are connected to two leads 13L, respectively, and drawn out of the plasma switch 320 through the bottom plate 321L. The first grid 326 is connected to the terminal T3 for external circuit connection, and the second grid 327 is connected to the terminal T4 for external circuit connection.

The operation of the switching device of this embodiment will be described.
FIG. 13 is a schematic enlarged cross-sectional view of part J in FIG. 12(a) for explaining the operation of the switching device of this embodiment.
14(a) to 14(d) are schematic diagrams for explaining the operation of the switching device of this embodiment.
As shown in FIG. 13, the first electrode 322 is formed in a star shape in XY plan view, and a hollow cathode portion 362 is formed in a radially protruding portion. Hollow cathode portion 362 has two opposing electrodes 322A1 and 322A2. Electrodes 322A1 and 322A2 are connected at the most projecting portion. The distance between the electrodes 322A1 and 322A2 is about twice the length of the ion sheath formed in the glow discharge state, as in the other embodiments described above.

In the glow discharge state, a negative glow GN is formed in the hollow cathode portion 362 . An electric field E is formed between the negative glow GN and the electrodes 322A1, 322A2. The formation of the negative glow GN in the hollow cathode portion 362 improves the current density of the plasma switch 320 .
As shown in FIGS. 14( a ) to 14 ( d ), magnetic lines of force are generated around the conductor according to the right-handed screw rule according to the direction of the current flowing through the conductor that constitutes the coil 366 . When a current flows from the front of the paper to the back of the paper, magnetic lines of force are generated in the clockwise direction (FIG. 14(a)). When such conductors are arranged one-dimensionally, a rightward magnetic field H is generated above the one-dimensionally arranged conductors and a leftward magnetic field H is generated below the conductors by synthesis of the magnetic lines of force of the conductors. generated (FIG. 14(b)). Reversing the direction of the current reverses the direction of the magnetic field H (FIGS. 14(c) and 14(d)). Therefore, magnetic fields H are generated in the same direction within the hollow cathode portion 362 .

The magnetic field H within the hollow cathode portion 362 generated by the coil 366 is generated so as to intersect the electric field E. Therefore, the electrons traveling by the electric field E receive the Lorentz force and travel spirally between the negative glow GN and the electrodes 322A1 and 322A2. Therefore, the traveling distance of the electrons is substantially extended, the pd product in the Paschen curve is substantially increased, and the current density inside the plasma switch 320 can be improved.

The materials of the first layer 322A and the second layer 322D are the same as in the other embodiments described above, and the current density of the plasma switch 320 is improved as in the other embodiments.

The effect of the switching device of this embodiment will be described.
The switching device of this embodiment includes the plasma switch 320 configured as described above, and can realize a switching device with dramatically improved current density, as in the case of the other embodiments described above.

In the switching device of the present embodiment, the first electrode 322 of the plasma switch 320 has a star-shaped cylindrical shape when viewed from the XY plane. There is also an advantage that the first electrode 322 can be easily formed by rolling a base material formed into a corrugated plate shape so as to form a plurality of protruding portions that form the hollow cathode portion 362 and joining the ends thereof. be.

In this way, the switching device of this embodiment can be realized.

In the above description, in the case of the first embodiment, the permanent magnet 64 is used as the magnetic field generating means for the hollow cathode portion 62, and in the case of the other embodiments, the coil is used as the magnetic field generating means. The magnetic field generating means is not limited to the examples of each of these embodiments, and can be applied by replacing each other. For example, a coil may be used in place of the permanent magnet 64 in the case of the first embodiment. The coil can be provided so as to generate a magnetic field directed outward from the center in the XY plane view generated by the permanent magnet 64 . For example, permanent magnets may be used instead of the

coils

266 and 366 in the case of the second and third embodiments.

When a magnetic field is generated by a permanent magnet, it is not limited to arranging individual permanent magnets, but may be integrally molded permanent magnets. An integral permanent magnet allows the manufacturing process of the plasma switch to be simpler.

(Fourth embodiment)
A DC interrupting device using at least one of the switching devices of the other embodiments described above will be described below.
A DC interrupter is, for example, a device that interrupts a DC system when a system fault or the like occurs in the DC system. In the following description, "normal" means a state in which a normal current flows in the DC system, and "at the time of an accident" means a state in which an excessive current flows due to lightning or the like. A DC system may include, for example, a DC power transmission and the like.
FIG. 15 is a schematic block diagram for explaining the operation of the DC interrupter of this embodiment.
FIG. 15 shows the configuration of a DC power transmission system K1 including the DC interrupting device 400 in addition to the DC interrupting device 400 of the present embodiment.
As shown in FIG. 15, the DC power transmission system K1 includes, for example, a positive power transmission line 1300 that connects a first DC power transmission network 1200A and a second DC power transmission network 1200B on the positive side, and a negative power transmission line 1400 that connects on the negative side. ,including.

The DC interrupting device 400 of this embodiment has the same effects as the switching device 1 of the other embodiments described above. Furthermore, in this embodiment, the DC interrupter 400 is provided in the positive power transmission line 1300 of the DC power transmission system K1. Here, an example of power transmission from the first DC power transmission network 1200A to the second DC power transmission network 1200B on the positive power transmission line 1300 will be mainly described.

The DC interrupting device 400 includes a mechanical disconnector 410, a mechanical circuit breaker 420, a parallel circuit 430, and an H bridge circuit 440. DC interrupter 400 includes first terminal 401 and second terminal 402 . DC interrupting device 400 is connected to first DC transmission network 1200A via first terminal 401 . The DC interrupter 400 is connected to the second DC power grid 1200B via the second terminal 402 .

The mechanical circuit breaker 420 is connected in series with the mechanical disconnector 410 . Parallel circuit 430 is connected in parallel to the series circuit of mechanical disconnector 410 and mechanical breaker 420 .

More specifically, parallel circuit 430 includes plasma switching unit 431 and reactor 432 . Plasma switching unit 431 and reactor 432 are connected in series. An arrestor 450 is connected in parallel with the plasma switching unit 431 .

One end of the H bridge circuit 440 is connected to the connection node between the mechanical disconnector 410 and the mechanical circuit breaker 420 . The other end of H bridge circuit 440 is connected to a connection node between plasma switching unit 431 and reactor 432 .

Various known configurations can be used for the mechanical disconnector 410 . In the present embodiment, the parallel circuit 430 is used to interrupt the direct current, as will be described later, so the mechanical disconnector 410 itself does not need to have a current interrupting capability. For this reason, the mechanical disconnector 410 is sufficient as long as it has a mechanical contact and has a dielectric strength that withstands the DC voltage required to disconnect the fault point in the state where the contact is disconnected. The mechanical disconnector 410 disconnects the circuit by, for example, providing a rotating contact between the terminals of the circuit, and rotating the rotating contact to contact or separate from the fixed contact attached to each terminal. can be configured to perform

The mechanical disconnector 410 is normally controlled to be in a conductive state, that is, in a state where the contacts are in contact. Current from first DC power grid 1200A flows through mechanical disconnect switch 410 to second DC power grid 1200B. At the time of an accident, as will be described later, control is performed so that current flows through the parallel circuit 430, and when the current flowing through the mechanical disconnector 410 becomes substantially zero, the mechanical disconnector 410 is switched to a non-conducting state and the circuit is disconnected.

Various known configurations can be used for the mechanical circuit breaker 420 . The mechanical circuit breaker 420 has a mechanical contact, and it is sufficient if it has the ability to cut off a small current by opening the contact. The mechanical circuit breaker 420, for example, provides a rotary contact between the terminals of the circuit, and rotates the rotary contact to make contact with or separate from the fixed contact attached to each terminal, thereby generating a small current. It can be set as the structure which interrupts.

The mechanical circuit breaker 420 is normally controlled so that it is in a conductive state, that is, in a state where the contacts are in contact. Current from first DC power grid 1200A flows through mechanical disconnector 410 and mechanical breaker 420 to second DC power grid 1200B. In the event of an accident, the current flowing through mechanical breaker 420 increases. A current sensor (not shown) is attached to the mechanical circuit breaker 420 . A fault that occurs in the DC power transmission system K1 is detected, for example, by measuring the current flowing through the mechanical circuit breaker 420 with a current sensor and comparing it with a threshold indicating a fault. Although the details will be described later, in the event of an accident, current flows through the H-bridge circuit 440 and control is performed so that the current flowing through the mechanical circuit breaker 420 becomes substantially zero. The mechanical circuit breaker 420 is switched to a non-conducting state when the flowing current becomes substantially zero, and the circuit is cut off.

The plasma switching unit 431 includes a first switching device 431A and a second switching device 431B. Both the first switching device 431A and the second switching device 431B can be, for example, any one of the switching devices of the first to third embodiments.

The first switching device 431A and the second switching device 431B are connected in anti-parallel. In the first switching device 431 A, the first electrode 22 is connected to the second terminal 402 and the second electrode 23 is connected to the first terminal 401 . In the second switching device 431 B, the first electrode 22 is connected to the first terminal 401 and the second electrode 23 is connected to the second terminal 402 .

Both the first switching device 431A and the second switching device 431B operate in the event of a ground fault or short-circuit accident in the DC power transmission system K1, and are normally in a non-conducting state and do not operate. The reactor 432 is connected in series with both the first switching device 431A and the second switching device 431B.

In this embodiment, the first switching device 431A is in charge of interrupting current flowing from the first DC power grid 1200A to the second DC power grid 1200B. The second switching device 431B is responsible for interrupting current flowing from the second DC power grid 1200B to the first DC power grid 1200A. Although the current interruption operation by the second switching device 431B will be described below, the current interruption operation by the first switching device 431A can also be explained in the same manner by changing the direction in which the current to be interrupted flows. be.

Both the first switching device 431A and the second switching device 431B are switching devices that include the plasma switch 20 (hereinafter referred to as plasma switching devices). As explained in the first to third embodiments, the plasma switching device is in the first state ST1 or the second state ST2 based on the potentials of the third terminal T3 and the fourth terminal T4. The first state ST1 is a non-conducting state and the second state ST2 is a conducting state. The plasma switching device is a switching device that shifts from the first state ST1 to the second state ST2 and from the second state ST2 to the first state ST1 by switching the potential of the fourth terminal T4.

The second switching device 431B connected in inverse parallel to the first switching device 431A is in a second conductive state and a non-conductive state by controlling the potentials of the third terminal T3 and the fourth terminal T4, respectively. A first state is switched.

The arrester 450 absorbs the surge voltage generated across the plasma switching unit 431 when the plasma switching unit 431 is switched from the conducting state to the non-conducting state, enabling safe current interruption. Reactor 432 is provided to reduce the current change rate. Reactor 432 enables current control by H bridge circuit 440 .

The H bridge circuit 440 includes a plurality of H bridge units 441. A plurality of H bridge units 441 are connected in series.

FIG. 16 is a schematic equivalent circuit diagram illustrating part of the DC interrupter of this embodiment.
FIG. 16 shows a circuit configuration example of the H bridge unit 441. As shown in FIG. H-bridge unit 441 includes switching element 442 , diode 444 and capacitor 445 . The H-bridge circuit 440 controls the current flowing through the mechanical breaker 420 by controlling the output voltage.

The switching elements 442 are connected in series. The diodes 444 are connected in anti-parallel to the switching elements 442 respectively. A series-connected switching element 442 constitutes a leg 443 . In H-bridge unit 441, two legs 443 and capacitor 445 are connected in parallel. The switching element 442 is a semiconductor element having self-extinguishing capability, such as an IEGT (Injection Enhanced Gate Transistor), an IGBT (Insulated Gate Bipolar Transistor), a MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), or the like. Capacitor 445 is charged by current flowing through positive transmission line 1300 during steady state operation.

The operation of the DC interrupter 400 of this embodiment will be described with reference to FIGS. 17 to 20(b). In the explanation of the operation, the explanation will be divided into the normal case and the accident case. Normally, the mechanical disconnecting switch 410 and the mechanical circuit breaker 420 are in a conducting state, and the plasma switching unit 431 and the H bridge circuit 440 are in a non-conducting state. FIGS. 17 and 19(a) to 20(b) are diagrams for explaining the flow from the normal state to the protection operation when an accident occurs in the DC power transmission system K1.
As shown in FIG. 17, normally, the current flowing from the first DC power transmission network 1200A to the second DC power transmission network 1200B flows into the DC interrupter 400 via the first terminal 401 as indicated by the arrow in the figure. , flows out from the second terminal 402 . In DC interrupter 400 , current flows through mechanical disconnector 410 and mechanical breaker 420 and does not flow through parallel circuit 430 and H-bridge circuit 440 .

FIG. 18 is an example of a schematic timing chart for explaining the operation of the DC interrupter of this embodiment.
For example, it is possible to obtain a timing chart as shown in FIG. 18 by utilizing simulation or the like.
In the following, the circuit model of the DC interrupting device 400 shown in FIG. A ground fault caused by lightning or the like is generated in the positive power transmission line 1300 .

As shown in FIGS. 19(a) to 20(b), the simulation assumes that a ground fault occurred at the accident point FP. The fault point FP is between the DC interrupter 400 in the positive power transmission line 1300 and the second DC power transmission network 1200B.

A solid line LN1 in FIG. 18 indicates the current flowing through the mechanical circuit breaker 420. A dashed-dotted line LN2 indicates the current flowing through the H-bridge circuit 440. FIG. A two-dot chain line LN 3 indicates the current flowing through the plasma switching unit 431 .

When an accident occurs, the fault current increases over time. As a whole, the DC interrupter 400 performs a two-step interruption operation. First, at the initial stage when the fault current is small, the mechanical circuit breaker 420 performs the breaking operation to commutate the fault current to the parallel circuit 430, and at the later stage when the fault current increases, the plasma switching unit 431 performs the breaking operation. I do. A detailed description will be given below.

As shown in FIGS. 18 and 19(a), when a ground fault occurs at the fault point FP at time t1, the current flowing through the mechanical circuit breaker 420 indicated by the solid line LN1 increases. A current sensor attached to the mechanical circuit breaker 420 detects a current Idc_M flowing through the mechanical circuit breaker 420, and the current Idc_M is compared with a preset fault occurrence detection threshold Idc_J.

As shown by solid line LN1 in FIG. 18 and FIG. 19(b), current Idc_M exceeds accident occurrence detection threshold Idc_J at time t2. The potential of the fourth terminal T4 of the second switching device 431B is changed from the fourth potential V4 to the fifth potential V5, and the second switching device 431B becomes conductive. At the same time, the output voltage control of H bridge circuit 440 is started.

Specifically, the output voltage V_H of the H bridge circuit 440 is calculated by the following equation (1).

V_H=G(s)×(Idc_M−0) (1)
In the above equation (1), G(s) is the Laplace-transformed control gain. The control gain G(s) represents, for example, a transfer function of general proportional-plus-integral control.

The switching element 442 of each H bridge unit 441 is pulse width modulation controlled, and the H bridge circuit 440 applies the output voltage VH of formula (1) across the mechanical circuit breaker 420 . The duty ratio of pulse width modulation is set in advance, for example. A current Idc_M flowing through the mechanical circuit breaker 420 is controlled to be substantially zero by applying the output voltage VH of Equation (1).

By such control by the H bridge circuit 440, the current Idc_M flowing through the mechanical breaker 420 is controlled to substantially zero in the period P1, as indicated by the solid line LN1 in FIG. At time t3, mechanical breaker 420 is transitioned to a non-conducting state. Since the current flowing through the mechanical circuit breaker 420 is substantially zero, the current can be interrupted without arcing between the contacts even if the contacts are switched to the non-conducting state. Therefore, the current can be interrupted at high speed.

When the output voltage is controlled by the H-bridge unit 441, the output voltage of the H-bridge unit 441 is directly applied to the mechanical circuit breaker 420 with almost zero conduction resistance, and a short-circuit current may flow, making current control impossible. . In this embodiment, the parallel circuit 430 is provided with a reactor 432 , and the H bridge circuit 440 is connected in series with this reactor 432 . The reactor 432 suppresses abrupt current changes due to the application of the output voltage of the H-bridge unit 441 to the mechanical circuit breaker 420, so that the current flowing through the mechanical circuit breaker 420 can be controlled.

Specifically, the current change rate dIdc_M/dt of the current Idc_M flowing through the mechanical circuit breaker 420 is expressed by the following equation (2) using the inductance value L of the reactor 432 .

　dIdc_M/dt=V_H/L (2)

Without the reactor 432, the inductance value L=0. Therefore, unless the output voltage V_H of the H bridge unit 441 is zero, the current change rate dIdc_M/dt becomes infinite, and the current flowing through the mechanical circuit breaker 420 is Control of Idc_M becomes impossible. In this embodiment, by providing the reactor 432 in the parallel circuit 430, the inductance value L is inserted in the above equation, so the current change rate dIdc_M/dt becomes finite. Therefore, it is possible to control the current change rate dIdc_M/dt according to the magnitude of the output voltage V_H of the H bridge unit 441 . This prevents direct application of the output voltage of the H-bridge unit 441 to the mechanical circuit breaker 420, and allows current control to make the current Idc_M flowing through the mechanical circuit breaker 420 substantially zero.

The output voltage control by the H bridge circuit 440 controls the current Idc_M flowing through the mechanical circuit breaker 420 until it becomes substantially zero. After time t3 has elapsed, as shown in FIG. It returns to the positive transmission line 1300 through the parallel circuit 430 . Therefore, the current Idc_M flowing through the mechanical circuit breaker 420 becomes substantially zero. In this state, the mechanical circuit breaker 420 is switched to the non-conducting state. Since the current flowing through the mechanical circuit breaker 420 is substantially zero, even if the contact is switched to the non-conducting state, unlike normal direct current conduction, an arc will not be drawn and the current will continue to flow. Therefore, the current can be interrupted at high speed.

All the switching elements 442 of the H-bridge unit 441 are turned off, as indicated by the dashed-dotted line LN2 in FIG. Then, the voltage previously stored in the capacitor 445 of the H-bridge unit 441 is applied in a direction to reduce the fault current continuing to flow through the mechanical disconnector 410 . This reduces the fault current flowing through the mechanical disconnector 410 . As the fault current flowing through the mechanical disconnector 410 is reduced, the fault current is commutated to the parallel circuit 430 connected in parallel to the mechanical disconnector 410 .

As indicated by the two-dot chain line LN3 in FIG. 18, at time t3, the current flowing through the plasma switching unit 431 increases. becomes zero and all fault currents flow through the plasma switching unit 431 . This operating state is shown in FIG. At this timing, the mechanical disconnector 410 is turned off. Since little current is flowing through the mechanical disconnector 410, the mechanical disconnector 410 can interrupt the current without arcing between the contacts.

Finally, in the operating state shown in FIG. 20B, when time t5 elapses, the fifth potential V5 of the fourth terminal T4 of the second switching device 431B is switched to the fourth potential V4, and the potential V4 flows through the parallel circuit 430. Interrupt the fault current. The surge voltage generated at this time is absorbed by the arrester 450, and current interruption is completed.

The effects of the DC interrupter 400 of this embodiment will be described.
In the DC interrupting device 400 of the present embodiment, since current normally flows through the mechanical disconnecting switch 410 and the mechanical circuit breaker 420, conduction loss can be reduced to almost zero. Therefore, high power transmission efficiency is realized. In the event of an accident, the output voltage control using the H-bridge circuit 440 induces a current in the parallel circuit 430 so that the current flowing through the mechanical disconnector 410 can be controlled without arcing between the contacts of the mechanical disconnector 410 . can be detached. Therefore, even if the mechanical disconnector 410 does not have a current interrupting capability, it is possible to safely disconnect the fault point. Furthermore, since the parallel circuit 430 includes the plasma switching unit 431, it can realize fast current interruption.

Furthermore, the plasma switching unit 431 is composed of a plasma switching device. Therefore, the device can be made extremely compact compared to the case where the parallel circuit is configured by semiconductor elements. Therefore, the power transmission efficiency can be improved, and the installation area and volume of the DC circuit breaker equipment in the DC multi-terminal power transmission equipment can be significantly reduced, contributing to the reduction of the equipment cost.

(Fifth embodiment)
FIG. 21 is a schematic block diagram illustrating the DC interrupter according to this embodiment.
FIG. 21 shows the DC interrupting device 500 of the present embodiment as well as the DC transmission system K2 that constitutes the DC interrupting device 500. As shown in FIG.
As shown in FIG. 21, the DC power transmission system K2 is similar to the above-described fourth embodiment in that the DC interrupting device 500 is connected between the first DC power transmission network 1200A and the second DC power transmission network 1200B. is different from the case of The direct-current interrupting device 500 differs from the above-described fourth embodiment in that it includes a plurality of mechanical disconnectors 410 and that a parallel circuit 530 includes a plurality of plasma switching units 431 . The same reference numerals are given to the same components as in the other embodiments described above, and detailed description thereof will be omitted as appropriate.

A DC interrupter 500 includes a first terminal 501 and a second terminal 502 . DC interrupter 500 is connected to first DC power grid 1200A through first terminal 501 and to second DC power grid 1200B through second terminal 502 . The DC interrupting device 500 includes a plurality of mechanical disconnectors 410 and parallel circuits 530 . A plurality of mechanical disconnectors 410 are connected in series. A plurality of series-connected mechanical disconnectors 410 are connected in series to a mechanical circuit breaker 420 . A series circuit of a plurality of mechanical disconnectors 410 and mechanical circuit breakers 420 is connected between first terminal 501 and second terminal 502 .

The parallel circuit 530 includes multiple plasma switching units 431 . A plurality of plasma switching units 431 are connected in series. An arrestor 450 is connected in parallel to each of the plurality of plasma switching units 431 . Parallel circuit 530 includes reactor 432 . The reactor 432 is connected in series with the series circuit of the plasma switching unit 431 .

In the operation of the DC interrupter 500 of this embodiment, the series-connected mechanical disconnectors 410 are opened and closed at the same timing. The plasma switching units 431 connected in series are also opened and closed at the same timing. Therefore, the DC interrupter 500 of this embodiment operates in the same manner as the DC interrupter 400 of the above-described fourth embodiment.

The effects of the DC interrupter 500 of this embodiment will be described.
The DC interrupter 500 of this embodiment has the same effects as the DC interrupter 400 of the fourth embodiment described above. Furthermore, the DC interrupter 500 comprises a plurality of mechanical disconnectors 410 and a plurality of plasma switching units 431 connected in series. Therefore, by appropriately setting the number of series connections of these series circuits, it is possible to appropriately respond to voltages at various locations in the DC power transmission system K2. Specifically, plasma switching units 431 of the same standard can be manufactured, and the number of series connections can be set according to the DC power grid to be installed. can contribute to the improvement of

(Sixth embodiment)
FIG. 22 is a schematic block diagram illustrating a direct-current interruption system according to this embodiment.
Although FIG. 22 does not show the first DC power transmission network 1200A, the second DC power transmission network 1200B, the positive power transmission line 1300 and the negative power transmission line 1400, A first DC power grid 1200A can be connected via a wire 1300 and a second DC power grid 1200B can be connected via a positive power transmission line 1300 to the second terminal 402 . Thereby, the DC power transmission system K3 can be configured.
A direct-current interruption system 600 of this embodiment differs from the above-described fourth and fifth embodiments in that a controller 601 is provided. The same constituent elements are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.
As shown in FIG. 22 , a DC interrupting system 600 includes a DC interrupting device 400 and a control device 601 . Control device 601 is connected to DC interrupter 400 .

The control device 601 includes a communication section 610 , a determination section 620 and an operation section 630 . Determining unit 620 and operating unit 630 are implemented, for example, by a hardware processor such as a CPU (Central Processing Unit) executing programs and software. Some or all of these components are hardware (circuits) such as LSI (Large Scale Integration), ASIC (Application Specific Integrated Circuit), FPGA (Field-Programmable Gate Array), GPU (Graphics Processing Unit) (including circuitry), or by cooperation of software and hardware. The program may be stored in advance in a storage device such as the controller's HDD or flash memory (a storage device with a non-transitory storage medium), or stored in a removable storage medium such as a DVD or CD-ROM. and may be installed in the storage device by loading the storage medium (non-transitory storage medium) into the drive device. The program may be stored in the storage unit.

For example, when an accident occurs in the DC power transmission system K3, the control device 601 switches the plasma switching unit 431 and the H bridge unit 441 to a conductive state, and controls the output voltage of the H bridge circuit 440 to control the current flowing through the mechanical breaker 420. is limited to shift the mechanical circuit breaker 420 to a non-conducting state.

The control device 601 shifts the H-bridge unit 441 to a non-conducting state, applies voltage to the capacitor 445 in the H-bridge circuit 440, commutates the fault current to the parallel circuit 430, and shifts the mechanical disconnector 410 to a non-conducting state. Let The controller 601 interrupts the fault current with the plasma switching unit 431 . The control device 601 is an example of a control unit.

The communication unit 610 is, for example, a wireless communication module for transmitting and receiving various information. Communication unit 610 receives accident information transmitted from, for example, a management center, and outputs the information to determination unit 620 . The communication unit 610 , for example, transmits control signals generated by the operation unit 630 to various devices included in the DC interrupter 400 .

Based on the accident information output by the communication unit 610, the determination unit 620 determines whether an accident has occurred in the DC power transmission system K3. When determination unit 620 determines that an accident has occurred in DC power transmission system K3, it notifies operation unit 630 of accident occurrence information including the occurrence of the accident and the circumstances of the accident.

The operation unit 630 generates a disconnecting switch operation signal, a circuit breaker operation signal, a switch operation signal, and a bridge operation signal based on the accident occurrence information notified by the determination unit 620 . The disconnecting switch operation signal is a signal for operating the mechanical disconnecting switch 410 . The circuit breaker operation signal is a signal for operating the mechanical circuit breaker 420 . A switch operation signal is a signal for operating the plasma switching unit 431 . A bridge operation signal is a signal for operating the H bridge unit 441 .

The operation unit 630 directs the generated disconnector operation signal, circuit breaker operation signal, switch operation signal, and bridge operation signal to the mechanical disconnector 410, the mechanical circuit breaker 420, the plasma switching unit 431, and the H bridge unit 441, respectively. and causes the communication unit 610 to transmit it.

The switch operation signal includes the first switch operation signal to the fourth switch operation signal. The first switch operation signal is information for switching the potential of the third terminal T3 corresponding to the first grid 26 of the first switching device 431A. The second switch operation signal is information for switching the potential of the fourth terminal T4 corresponding to the second grid 27 of the first switching device 431A. The third switch operation signal is information for switching the potential of the third terminal T3 corresponding to the first grid 26 of the second switching device 431B. The fourth switch operation signal is information for switching the potential of the fourth terminal T4 corresponding to the second grid 27 of the second switching device 431B.

The accident occurrence information includes, for example, the power transmission direction of DC power transmission and information on the occurrence of an accident in the DC system. Determination unit 620 includes a function of recognizing the power transmission direction of DC power transmission and a function of determining the occurrence of an accident in the DC system. For example, when the power transmission direction is from the first terminal 401 to the second terminal 402, the determination unit 620 selects the first switching device 431A as means for finally interrupting the current when an accident occurs. For example, when the power transmission direction is from the second terminal 402 to the first terminal 401, the determination unit 620 selects the second switching device 431B as means for finally interrupting the current when an accident occurs.

The DC interrupting device 400 is connected, for example, to the DC transmission line on the positive electrode side. For this reason, the DC interrupter 400 is configured to ensure appropriate insulation from the ground. The control device 601 is installed, for example, near various devices of the DC interrupter 400, and is installed on the ground at ground potential. For this reason, the control device 601 transmits operation signals to each device by wire cable means via an insulating transformer or optical fiber cable means electrically insulated by an optical signal.

The effect of the direct-current interruption system 600 of this embodiment will be described.
The DC interrupting system 600 of this embodiment has the same effects as the DC interrupting device 400 of the fourth embodiment described above. Since the DC interruption system 600 of the present embodiment includes the control device 601, it determines the power transmission direction and determines which of the first switching device 431A and the second switching device 431B should be cut off when an accident occurs. select. Therefore, it is possible to interrupt the fault current in both directions.

(Seventh embodiment)
FIG. 23 is a schematic block diagram illustrating a direct-current interruption system according to this embodiment.
Although FIG. 23 does not show the first DC power transmission network 1200A, the second DC power transmission network 1200B, the positive power transmission line 1300 and the negative power transmission line 1400, A first DC power grid 1200A can be connected via a wire 1300 and a second DC power grid 1200B can be connected via a positive power transmission line 1300 to the second terminal 402 . Thereby, the DC power transmission system K4 can be configured.
A DC interrupting system 700 of this embodiment includes a control device 701 different from the control device 601 of the sixth embodiment described above. The same constituent elements are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.
As shown in FIG. 23 , a DC interrupting system 700 includes a DC interrupting device 400 and a control device 701 . The control device 701 includes a hydrogen amount control section 740 .

In the control device 701, the communication unit 610, the determination unit 620, and the operation unit 630 function and operate in the same manner as in the sixth embodiment described above.

The communication unit 610 receives the number of operations of the first switching device 431A and the second switching device 431B, and outputs it to the hydrogen amount control unit 740.

Hydrogen amount control unit 740 monitors hydrogen consumption, hydrogen concentration, and withstand voltage at the surface termination of first electrode 22 in each of first switching device 431A and second switching device 431B, based on the output number of operations. Monitor levels. Based on these monitoring results, the hydrogen amount control unit 740 determines whether or not the plasma switches 20 in each of the first switching device 431A and the second switching device 431B need to be replenished with hydrogen.

When the hydrogen amount control unit 740 determines that it is necessary to replenish hydrogen, it causes the communication unit 610 to transmit a replenishment operation signal to the first switching device 431A and the second switching device 431B. The filling operation signal is a signal for heating the hydrogen storage metal 20H to release hydrogen and filling the plasma switch 20 with hydrogen.

The DC interrupting system 700 of this embodiment has the following effects in addition to the same effects as the DC interrupting device 400 of the fourth embodiment.
That is, when the hydrogen concentration in the plasma switch 20 in the first switching device 431A and the second switching device 431B decreases, the DC cutoff system 700 supplies hydrogen without inhibiting the reduced pressure in the plasma switch 20. be able to.

(Eighth embodiment)
FIG. 24 is a schematic block diagram illustrating the DC interrupting device according to this embodiment.
FIG. 25 is a schematic perspective view illustrating the direct current interrupting device of this embodiment.
Although FIG. 24 does not show the first DC transmission network 1200A, the second DC transmission network 1200B, the positive transmission line 1300 and the negative transmission line 1400, the positive transmission line is connected to the first terminal of the DC interrupter 800. A first DC power grid 1200A can be connected via 1300 and a second DC power grid 1200B can be connected via a positive power line 1300 to the second terminal. Thereby, the DC power transmission system K5 can be configured.
As shown in FIG. 24, a direct current interrupter 800 of this embodiment includes a mechanical cutoff valve 801, a plasma switch valve 802, and an H bridge valve 803.

The mechanical shutoff valve 801 includes a mechanical disconnector 410 and a mechanical circuit breaker 420 . In the mechanical shutoff valve 801 of this example, a plurality of mechanical disconnectors 410 are connected in series, and a mechanical circuit breaker 420 is connected in series to the series circuit of the mechanical disconnectors 410 . The mechanical shutoff valve 801 has

terminals

801a, 801b, 801c. A series circuit of mechanical disconnector 410 and mechanical circuit breaker 420 is connected between

terminals

801a and 801c.

The plasma switch valve 802 includes a plasma switching unit 431 and an arrester 450. In the plasma switch valve 802 of this example, a plurality of plasma switching units 431 are connected in series, and an arrester 450 is connected in parallel to each of the plurality of plasma switching units 431 . The plasma switch valve 802 has

terminals

802a and 802b. A series circuit of plasma switching units 431 is connected between

terminals

802a and 802b.

The H bridge valve 803 includes an H bridge unit 441 and a reactor 432. In the H bridge valve 803 of this example, multiple H bridge units 441 are connected in series. The H bridge valve 803 has

terminals

803a, 803b and 803c. The series circuit of H bridge unit 441 is connected between

terminals

803a and 803c. Reactor 432 is connected between

terminals

803a and 803b.

A terminal 801 a of the mechanical shutoff valve 801 is electrically connected to a terminal 802 a of the plasma switch valve 802 . Terminal 802b of plasma switch valve 802 is electrically connected to terminal 803a of H-bridge valve 803 .

Terminals

803b and 803c of H-bridge valve 803 are connected to

terminals

801c and 801b of mechanical isolation valve 801, respectively.

As shown in FIG. 25, the mechanical shutoff valve 801, the plasma switch valve 802 and the H bridge valve 803 are housed in different housings 800a to 800c and arranged independently of each other. The mechanical shutoff valve 801 is mounted, for example, on an independent mount (not shown). The mechanical shut-off valve 801, plasma switch valve 802 and H-bridge valve 803 operate in the same manner as the DC shut-off device 400 of the fourth embodiment, for example, described above.

The effects of the DC interrupter 800 of this embodiment will be described.
The direct-current interrupting device 800 of this embodiment has the following effects in addition to the same effects as those of the direct-current interrupting

devices

400 and 500 of the above-described fourth and fifth embodiments. That is, in the direct current interrupter 800, the mechanical cutoff valve 801 is mounted on an independent stand. For this reason, it is easy to prevent the operational vibration accompanying opening and closing of the electrodes of the mechanical disconnecting switch 410 and the mechanical circuit breaker 420 mounted on the mechanical shutoff valve 801 from being transmitted to the plasma switch valve 802 and the H bridge valve 803. can be realized. Therefore, reliability such as durability can be improved.

In the direct current interrupting device 800 of this embodiment, the mechanical cutoff valve 801, the plasma switch valve 802 and the H bridge valve 803 are arranged independently. Therefore, even after the installation of the direct-current interrupting device 800, work can be performed from the side of each valve, and maintenance can be facilitated.

For example, if the mechanical disconnecting switch 410, the mechanical circuit breaker 420, the plasma switching unit 431, and the H-bridge unit 441 are arranged and housed in one housing or base material, the installation area of the housing or base material becomes large, and the direct current Access to the back of the shut-off device becomes difficult. In addition, since the weight of the device borne by one housing and base material also increases, the housing and base material must be strongly configured, which increases the overall weight and cost.

In this regard, in the DC interrupter 800 of this embodiment, the mechanical cutoff valve 801, the plasma switch valve 802 and the H bridge valve 803 are arranged independently. For this reason, items to be taken into consideration regarding handling of the component parts are limited, and assembling efficiency can be improved. Furthermore, the quality can be improved by testing each valve. Therefore, it is possible to improve the durability, maintainability, assemblability, and quality of the DC interrupter 800 using the plasma switching device.

(Ninth embodiment)
FIG. 26 is a schematic block diagram illustrating the DC interrupter according to this embodiment.
FIG. 26 shows the configuration of a DC power transmission system K6 including the DC interrupting device 900 in addition to the DC interrupting device 900 of the present embodiment.
As shown in FIG. 26, the DC power transmission system K6 is similar to the above-described fourth embodiment in that a DC interrupting device 900 is connected between the first DC power transmission network 1200A and the second DC power transmission network 1200B. is different from the case of The same reference numerals are given to the same components as in the other embodiments described above, and detailed description thereof will be omitted as appropriate.

A direct current interrupting device 900 differs from that of the fourth embodiment in that it does not include an H bridge circuit 440 . That is, the DC interrupting device 900 includes a mechanical disconnector 410 , a mechanical circuit breaker 420 and a parallel circuit 430 .

The mechanical disconnector 410 and the mechanical circuit breaker 420 are connected in series. Parallel circuit 430 is connected in parallel to the series circuit of mechanical disconnector 410 and mechanical breaker 420 . The DC interrupter 900 has a first terminal 901 and a second terminal 902, and the mechanical disconnector 410, the mechanical circuit breaker 420 and the parallel circuit 430 are connected between the first terminal 901 and the second terminal 902. It is connected to the. A reactance may be connected in series with the parallel circuit 430 and connected in parallel with the series circuit of the mechanical disconnector 410 and the mechanical breaker 420 .

The DC interrupting device 900 of the present embodiment can significantly improve the voltage drop in the second state in which the plasma switches 20 of the first switching device 431A and the second switching device 431B are conductive.

The operation of the DC interrupting device 900 of this embodiment will be described separately for normal operation, accident operation, and operation. At the time of the accident, a case where a DC short-circuit fault occurs in the second DC transmission network 1200B will be described.

Normally, the mechanical disconnector 410 is in a conducting state, and the first switching device 431A and the second switching device 431B are in a non-conducting first state ST1. At this time, current from first DC power grid 1200A flows to second DC power grid 1200B via mechanical disconnector 410 and mechanical circuit breaker 420 and does not flow to parallel circuit 430 .

When an accident occurs, if the current sensor attached to the mechanical disconnector 410 detects a current Idc_M exceeding the accident occurrence detection threshold value Idc_J, the second switching device 431B is switched to the second state ST2.

At the same time that the current sensor attached to the mechanical disconnector 410 detects the current Idc_M, the mechanical disconnector 410 starts operating in the direction in which the contact electrode opens. When the contact electrodes of the mechanical disconnector 410 begin to separate, an arc is generated between the contact electrodes and an arc voltage is generated at the same time. Current continues to attempt to continue to flow, but the fault current flowing through mechanical disconnector 410 is shunted to parallel circuit 430 .

If the voltage drop in the second state ST2 of the plasma switching unit 431 is sufficiently low, most of the fault current flowing through the mechanical disconnector 410 is commutated to the parallel circuit 430. Furthermore, by blowing compressed gas to the part where the contact electrode of the mechanical disconnector 410 is separated to suppress the contact electrode and its surroundings from becoming plasma, the contact electrode opening operation is continued toward the maximum gap. , the arc voltage increases, and the fault current easily flows through the parallel circuit 430, the arc of the mechanical disconnector 410 disappears, and the current becomes zero.

After the current of the mechanical disconnector 410 becomes zero, the insulation recovery time of the mechanical circuit breaker 420 is awaited, and the second switching device 431B of the plasma switching unit 431 is switched from the conductive second state ST2 to the non-conductive state. The current flowing through the parallel circuit 430 is cut off by switching to the first state ST1. In this way, the fault current interruption by the DC interruption device 900 is completed.

The effects of the DC interrupter 900 of this embodiment will be described.
The direct current interrupting device 900 of the present embodiment has the following effects in addition to the effects similar to those of the direct current interrupting device 400 of the fourth embodiment, for example. That is, the direct-current interrupting device 900 of this embodiment does not need to be provided with an H-bridge circuit, so it can contribute to cost reduction and miniaturization. Furthermore, by reducing the number of device parts, it is possible to improve maintainability, productivity, and reliability.

(Tenth embodiment)
FIG. 27 is a schematic block diagram illustrating a DC interrupting device according to this embodiment.
FIG. 27 shows a DC transmission system K7 including a plurality of DC transmission networks and a plurality of DC interrupters.
As shown in FIG. 27, the DC power transmission system K7 includes a first DC interrupter 1000A to a third DC interrupter 1000C. The DC interrupters 1000A to 1000C of this embodiment have the same configuration. The DC interrupters 1000A-1000C comprise a plasma switching unit 1030. The plasma switching unit 1030 differs from the plasma switching unit 431 of the fourth embodiment in that it is composed of a second switching device 431B and does not include a first switching device 431A. In other respects, the configuration of the DC interrupting devices 1000A to 1000C is the same as the configuration of the DC interrupting device 400 in the case of the fourth embodiment. The same constituent elements are denoted by the same reference numerals, and detailed description thereof will be omitted as appropriate.

The DC transmission system K7 includes three DC transmission networks: a first DC transmission network 1200A, a second DC transmission network 1200B and a third DC transmission network 1200C. First DC power grid 1200A, second DC power grid 1200B, and third DC power grid 1200C all include AC/DC power converters (not shown).

The positive power transmission line 1300 of the first DC interrupter 1000A is provided with a first terminal 1001a on the side of the first DC power transmission network 1200A, and a second terminal 1002a on the opposite side of the first DC power transmission network 1200A. . The positive power transmission line 1300 of the second DC interrupter 1000B is provided with a first terminal 1001b on the second DC power grid 1200B side and a second terminal 1002b on the opposite side of the second DC power grid 1200B. The positive power transmission line 1300 of the third DC interrupter 1000C is provided with a first terminal 1001c on the side of the third DC power grid 1200C, and a second terminal 1002c on the opposite side of the third DC power grid 1200C. .

The operations of the first to third DC interrupting devices 1000A to 1000C will be described by exemplifying a plurality of accident cases.
FIG. 28 is a schematic block diagram for explaining the operation of the DC interrupter of this embodiment.
In the following description, in the DC transmission system K7, from the first DC transmission network 1200A and the third DC transmission network 1200C toward the second DC transmission network 1200B, the positive transmission line 1300 and the negative transmission line 1400 transmit DC. It is assumed that

First, accident case 1 will be explained. Accident case 1 is a case where a ground fault occurs at the first fault point FP1 of the positive transmission line 1300 between the first DC transmission network 1200A and the first DC interrupting device 1000A.

Due to the occurrence of a ground fault at the first fault point FP1, the voltage at the first fault point FP1 becomes ground potential. Therefore, the fault current flows toward the first fault point FP1. That is, current flows from the first DC transmission network 1200A side toward the first fault point FP1, and then from the second DC transmission network 1200B side and the third DC transmission network 1200C side toward the first fault point FP1.

At this time, the first DC interrupter 1000A performs protective operation, interrupts the fault current, and disconnects the first fault point FP1 from the positive power transmission line 1300. The second DC power grid 1200B and the third DC power grid 1200C transmit power from the third DC power grid 1200C toward the second DC power grid 1200B by disconnecting the first fault point FP1 from the positive power transmission line 1300. can be continued or resumed.

Next, accident case 2 will be explained. Accident case 2 is a case where a ground fault occurs at second fault point FP2 of positive transmission line 1300 connecting first DC transmission network 1200A, second DC transmission network 1200B, and third DC transmission network 1200C.

Due to the ground fault occurring at the second fault point FP2, the voltage at the second fault point FP2 becomes the ground potential. Therefore, the fault current flows toward the second fault point FP2. That is, from the first DC power grid 1200A side to the second fault point FP2, from the second DC power grid 1200B side to the second fault point FP2, and from the third DC power grid 1200C side to the second fault point FP2. , the fault current flows.

At this time, each of the first DC interrupting device 1000A to the third DC interrupting device 1000C performs protective operation, interrupts the fault current, and disconnects the second fault point FP2 from the positive power transmission line 1300. The protection operation is an operation of switching the plasma switches of the first to third DC interrupting devices 1000A to 1000C from the first state (non-conducting state) to the second state (conducting state). In accident case 2, interconnection with any of the first DC power grid 1200A to the third DC power grid 1200C is impossible unless the second fault point FP2 is restored.

Next, accident case 3 will be explained. Accident case 3 is a case where a ground fault occurs at the third fault point FP3 of the positive transmission line 1300 between the second DC transmission network 1200B and the second DC interrupting device 1000B.

Due to the ground fault occurring at the third fault point FP3, the voltage at the third fault point FP3 becomes the ground potential. Therefore, the fault current flows toward the third fault point FP3. That is, the fault current flows from the second DC power transmission network 1200B side toward the third fault point FP3, and from the first DC power transmission network 1200A side and the third DC power transmission network 1200C side toward the third fault point FP3. .

At this time, the second DC interrupter 1000B performs protective operation, interrupts the fault current, and disconnects the third fault point FP3 from the positive power transmission line 1300. 1200A of 1st DC power transmission networks and 1200C of 3rd DC power transmission networks will be in an interconnection possible state by cutting off the 3rd fault point FP3 from the positive power transmission line 1300. FIG.

Next, accident case 4 will be explained. Accident case 4 is a case where a ground fault occurred at the fourth fault point FP4 of the positive power transmission line 1300 between the third DC transmission network 1200C and the third DC interrupting device 1000C.

Due to the occurrence of a ground fault at the fourth fault point FP4, the voltage at the fourth fault point FP4 becomes ground potential. Therefore, the fault current flows toward the fourth fault point FP4. That is, current flows from the first DC power grid 1200A side and the second DC power grid 1200B side toward the fourth fault point FP4, and from the third DC power grid 1200C side toward the fourth fault point FP4.

At this time, the third DC interrupting device 1000C performs protective operation, interrupts the fault current, and disconnects the fourth fault point FP4 from the positive power transmission line 1300. The first DC power transmission network 1200A and the second DC power transmission network 1200B transmit power from the first DC power transmission network 1200A toward the second DC power transmission network 1200B by disconnecting the fourth fault point FP4 from the positive power transmission line 1300. or resume power transmission.

The effects of the DC interrupter of this embodiment will be described.
The DC interrupting devices 1000A to 1000C of this embodiment have the following effects in addition to the same effects as the DC interrupting devices of the other embodiments described above. That is, even if the DC circuit breakers 1000A to 1000C are one-way interrupting DC circuit breakers, they can isolate the fault point of the DC multi-terminal transmission line and suppress the expansion of the fault.

According to at least one embodiment described above, the first electrode connected to the first terminal is connected to the second terminal, and the second electrode separated from the first electrode is connected to the third terminal. , a first grid arranged between the first electrode and the second electrode, and a second grid connected to a fourth terminal and arranged between the first grid and the second electrode. A switching device comprising a plasma switch and an outer shell provided outside the plasma switch and forming a sealed space between the plasma switch and the plasma switch, wherein the sealed space is filled with an insulating gas. , a compact switching device and a DC interrupting device can be provided.

Although several embodiments of the invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and modifications can be made without departing from the scope of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, as well as the scope of the invention described in the claims and equivalents thereof.

Claims

a first electrode, a second electrode provided apart from the first electrode, a first grid provided between the first electrode and the second electrode, and a space between the first grid and the second electrode a plasma switch comprising a second grid disposed therebetween;
an outer shell provided outside the plasma switch and forming a closed space with the plasma switch;
with
The first electrode is
a hollow cathode portion in which the plasma switch produces a negative glow during glow discharge;
a magnetic field generator provided around the hollow cathode and generating a magnetic field that intersects the electric field between the negative glow and the first electrode;
including
The switching device, wherein the hollow cathode section comprises at least one material of B, C, Al, Si and Ga.
The switching device according to claim 1, wherein the hollow cathode section contains at least one material selected from diamond, graphite, a nitride semiconductor, and alumina cement.
The switching device according to claim 1, wherein the magnetic field generator generates a magnetic field perpendicular to the electric field between the negative glow and the first electrode.
The first electrode has a circular shape in plan view including a first direction and a second direction intersecting the first direction, and has a cylindrical shape extending in a third direction intersecting the first direction and the second direction. none,
4. A switching device according to claim 3, wherein said hollow cathode portion extends in a radial direction of said circular shape.
A plurality of the hollow cathode portions are provided,
5. The switching device according to claim 4, wherein the plurality of hollow cathode portions are provided so as to be stacked in the third direction.
the first electrode is formed in a flat plate including a first direction and a second direction crossing the first direction;
4. The switching device according to claim 3, wherein said hollow cathode portion is provided in a concave portion provided in said flat plate in a third direction crossing said first direction and said second direction.
The switching device according to claim 6, wherein a plurality of said hollow cathode portions are provided.
4. The switching device according to claim 3, wherein the hollow cathode portion protrudes in a radial direction of a circle in plan view including a first direction and a second direction intersecting the first direction.
The switching device according to claim 8, wherein a plurality of said hollow cathode portions are provided radially around said circle.
The switching device according to claim 1, wherein the magnetic field generator includes a permanent magnet.
2. The switching device according to claim 1, wherein the magnetic field generating section includes a coil formed of a conductive wire surrounding the hollow cathode section.
The outer shell is
an insulating cylinder arranged outside the plasma switch;
end plates for closing the openings of the insulating cylinders;
a junction that joins the first electrode, the second electrode, the first grid, and the second grid in the plasma switch;
2. The switching device of claim 1, comprising a pressure vessel containing:
a mechanical disconnector;
a mechanical circuit breaker connected in series with the mechanical disconnector;
a switching device according to any one of claims 1 to 12;
with
the switching device is connected in parallel to the series circuit of the mechanical disconnector and the mechanical circuit breaker;
the switching device conducts after the mechanical circuit breaker is opened;
The mechanical disconnector is a direct current interrupting device that cuts off after the switching device is turned on.
a reactor connected in series with the switching device;
an H-bridge circuit connected between a connection node of the mechanical disconnector and the mechanical circuit breaker and a connection node of the switching device and the reactor;
further comprising
the H-bridge circuit starts operating after the mechanical breaker is opened;
14. The direct current interrupting device according to claim 13, wherein the switching device conducts after the H-bridge circuit starts operating.
A plurality of the switching devices are provided,
14. The DC interrupting device according to claim 13, wherein said plurality of switching devices are connected in series.
a first housing;
a second housing different from the first housing;
a third housing different from the first housing and the second housing;
further comprising
The first housing houses a series circuit of the mechanical disconnector and the mechanical circuit breaker,
The second housing houses the switching device,
15. The direct current interrupting device according to claim 14, wherein the third housing accommodates the reactor and the H bridge circuit.
a mechanical disconnector;
a mechanical circuit breaker connected in series with the mechanical disconnector;
a switching device according to any one of claims 1 to 11;
a control device that controls the switching device;
with
the switching device is connected in parallel to the series circuit of the mechanical disconnector and the mechanical circuit breaker;
The control device conducts the switching device after the mechanical circuit breaker is opened,
A direct current interrupting system that interrupts the mechanical disconnector after the switching device conducts.
the switching device includes a hydrogen storage metal that supplies hydrogen to the interior of the plasma switch;
18. The direct current interruption system of claim 17, wherein the controller generates a command to supply hydrogen from the hydrogen storage metal to the interior of the plasma switch.