CONNECTION STRUCTURE WITH UHF ANTENNA FOR A GAS-ISOLATED SWITCHGEAR

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a connecting structure for connecting two housing parts of a gas-insulated switchgear, relates to a gas-insulated switchgear, further relates to a manufacturing method or retrofitting method of a connecting structure for connecting two housing parts of a gas-insulated switchgear and further relates to a method of monitoring a gas-insulated switchgear. STATE OF THE ART

[0002] A gas-insulated switchgear (GIS) is a completely gas-tight, encapsulated switchgear for high and medium voltage applications that surrounds the electrical conductor(s) with sulfur hexafluoride (SF6) as a protective gas. This allows for compact switchgear to be implemented in confined spaces. SF6 has a dielectric strength three to four times higher than air at normal pressure.

[0003] In the event of a fault inside the switchgear, an arc fault, generally a gas discharge, can occur. This can result in very high overpressures and heating, which can place mechanical and / or thermal stress on the switchgear and potentially destroy it. In particular, partial discharges (PD) in gas-insulated switchgear (GIS) can generate electromagnetic waves with frequencies in the ultra-high frequency (UHF) range. These UHF waves can be detected and analyzed for monitoring and diagnostic purposes. Provided UHF sensors are present in the GIS, monitoring can thus be easily performed.

[0004] JP H11 122761 A discloses a gas-insulated switchgear assembly in which an insulating spacer made of cast resin is used to detect such electromagnetic waves. To guide the electromagnetic waves from the switchgear assembly to the surface of the spacer, a waveguide made of a material with a lower dielectric constant than the cast resin is used. A ring-shaped antenna is arranged on the surface of the spacer, enclosing the end of the waveguide.

[0005] JP 4 936846 B2 discloses an insulating piece comprising an integrated circuit with a sensor. The sensor is used to detect partial discharges.

[0006] From the document JP H10 341520 A it is known to guide the microwaves generated during partial discharges to an antenna of a microwave sensor by means of a waveguide and to receive them by means of this antenna.

[0007] The document US 2011 / 005809 A1 discloses a rotationally symmetrical insulating part for a gas-insulated system, which has an opening for filling with casting resin.

[0008] The documents WO 2007 / 097491 A1 and FR 3 015 043 A1 also disclose UHF sensors arranged at a radial opening of a gas-insulated system.

[0009] Document FR 3 015 043 A1 discloses a connecting structure for a gas-insulated switchgear assembly with a flange ring supported on the outer edge of an insulating part. The flange ring has an opening in which a UHF sensor with a sensor electrode and electrical connection is mounted. However, the flange ring is not encapsulated with the insulating part.

[0010] Traditionally, however, gas-insulated switchgear is inadequately equipped with UHF sensors. Even retrofitting UHF sensors is not possible in all situations, or only when the entire system is shut down. In particular, viewports are not always available at the GIS, or their number is very limited. Furthermore, it has been found that the sensitivity of a UHF sensor placed at a viewport is very low. UHF antennas cannot generally be mounted on flanges with metallic rings, as with this type of placement, electromagnetic waves cannot pass through metal and thus cannot be detected. Traditionally, gas-insulated switchgear was retrofitted, but this required shutting down the system or SF6 gas work and new, custom-made components.

[0011] It is therefore an object of the present invention to provide devices and methods which enable the GIS to be monitored, in particular to attach a UHF sensor or a UHF antenna to a GIS in such a way that the detection of electromagnetic waves due to a partial discharge is possible.

[0012] The object is achieved by the subject matter of the independent claims. The dependent claims particularly specify embodiments of the present invention. SUMMARY OF THE INVENTION

[0013] According to the present invention, a connecting structure according to claim 1 is provided for connecting two components (also referred to as equipment parts) of a gas-insulated switchgear, comprising, among other things: a metallic flange ring; a cast resin gate opening in the flange ring; and a UHF sensor with antenna mounted at the cast resin gate opening.

[0014] The gas-insulated switchgear (GIS) can comprise several system components (also referred to as system components), wherein a current conductor or an electrical component, such as a voltage transformer, a current transformer, a disconnector, an interrupter unit, an earthing switch, or the like, can be arranged in each of the system components. An electrical component located in a first system component may be required to be connected to a second electrical component located in a second system component. For this purpose, a connecting structure, which can also be conventionally referred to as a "feedthrough," can be used. The connecting structure, on the one hand, mechanically connects the two system components to one another and, on the other hand, enables an electrical connection between the first electrical component located in the first system component and the second electrical component located in the second system component.Thus, each of the system components has an outer wall, in particular a metallic outer wall, and an interior space surrounded by the outer wall, in which the one or more electrical components are arranged.

[0015] A connecting structure (bushing) consisting of a flange ring, a cast resin body, and one or three electrodes is designed to mechanically and electrically connect two parts of the system, whereby a gas-tight connection must be achieved. The cast resin body is cast into the flange ring (e.g., made of metal), and the electrode is cast into the cast resin body. Gas-insulated switchgear is filled with a gas (generally SF 6 ) during operation and is designed for voltages above 500 kV.

[0016] A plug (also called a lid) can conventionally be provided on the flange ring, which allows direct contact with the casting resin when opened, since the latter is enclosed by the flange ring.

[0017] The plug is therefore traditionally used to close the cast resin sprue opening and has a circular cross-section. The cast resin sprue opening can thus be accessed from the outside of a fully assembled gas-insulated switchgear.

[0018] The connecting structure can be manufactured or retrofitted in a separate manufacturing process or retrofit process, according to an embodiment of the present invention. The retrofitting can include, for example, replacing the plug (lid) with a UHF sensor. The UHF sensor includes at least the UHF antenna and can additionally have a closing and sealing function to close the pouring opening (similar to the conventional plug / lid).

[0019] According to IEC 60270, partial discharges are local electrical discharges that only partially bridge the insulation between conductors. They are usually the result of an excessive increase in the local electric field strength within the insulation material (liquid, solid, or gaseous) or on the surface of the insulation or a conductor.

[0020] Partial discharges are the result of a defect or impurity within the GIS and generate electromagnetic waves that then propagate. These electromagnetic waves have frequencies in the UHF (ultra-high frequency) range and can be detected using UHF probes or antennas.

[0021] The UHF probes can be mounted internally or externally. The internal version is best installed during the GIS construction phase, as retrofitting is associated with high costs.

[0022] The external flange ring design is only possible if the flange ring is not metallic. Like the viewport design, it is more susceptible to failure.

[0023] Through the cast resin sprue, a UHF antenna can be mounted in such a way that it protrudes at least partially into an interior space; thus, a convenient way to mount or use a UHF antenna for monitoring and diagnostic purposes is provided.

[0024] According to one embodiment of the present invention, the UHF antenna is mounted in such a way that electromagnetic waves present within the GIS can be detected. The electromagnetic waves, caused by partial discharges, propagate within the interior of the gas-insulated switchgear, so they can also be present within the cast resin. This enables simple monitoring of the gas-insulated switchgear.

[0025] According to one embodiment of the present invention, the cast resin pouring opening extends through a peripheral surface of the flange ring. Cast resin pouring openings can be conventionally provided on this peripheral surface. During the pouring of the cast resin through the cast resin pouring opening, the end faces of the flange ring can be closed by plates (or pouring molds).

[0026] In the space surrounded by the flange ring, one (or more, depending on the number of electrical phases) connecting electrodes can be provided, which are surrounded by the cast resin and mechanically fixed after curing. The connecting electrode (or generally electrical connecting structure) can enable a first conductor from a first system part of the GIS to be connected, in particular electrically, to a second conductor in a second system part of the GIS.

[0027] The UHF antenna is mounted in such a way that it is in contact with the (cured) cast resin material. The cast resin material can comprise a dielectric material, particularly a non-conductive material. In particular, electromagnetic waves can propagate within the cast resin material with lower attenuation. This allows an electromagnetic wave present within the GIS interior to also propagate through the cast resin material and be detected by the UHF antenna.

[0028] The cast resin material may be gas-tight to form a gas-tight bonding structure.

[0029] In some embodiments, the casting resin material is first poured in without surrounding the UHF antenna. Only after the casting resin material has hardened can the UHF sensor and the UHF antenna be properly mounted. For this purpose, the UHF sensor has a mounting section and a connected closure section. The mounting section enables mounting on the flange ring, with the closure section closing the sprue opening. The UHF antenna is attached to the closure section, which functions, for example, as a cover.

[0030] The UHF sensor can be mounted on the flange ring by screwing the mounting section into existing holes around the sprue opening.

[0031] According to one embodiment of the present invention, the cover has a conductor feedthrough through which an antenna signal detected by the UHF antenna can be conducted to the outside. Generally, the cover can be made of a metal, such as steel. The conductor feedthrough can be routed insulated through the metallic material of the cover. The conductor feedthrough can, for example, be designed with two poles. This allows for easy external routing of the electrical antenna signal.

[0032] According to the invention, the UHF sensor has an electrical connector (N-connector or BNC connector) on the outside, which is electrically connected to the head of the UHF antenna. A partial discharge measuring device can be connected to this connector using a coaxial cable only when needed. When not in use, the antenna is short-circuited by a protective cap on the connector. Monitoring is not required in every case. This allows for great flexibility.

[0033] According to one embodiment of the present invention, the closing section of the UHF sensor and / or an edge of the flange ring defining the cast resin inlet opening has a seal that is particularly impermeable to SF6. This allows support for gas-insulated switchgear systems conventionally filled with SF6.

[0034] According to one embodiment of the present invention, the flange ring is substantially circular-cylindrical in shape. This allows conventional connection structures to be supported, and conventional flanges of GIS system components can be connected to the flange ring.

[0035] According to one embodiment of the present invention, the flange ring has holes along its circumference to allow a respective system component of the GIS to be attached to each of the two end faces (of the flange ring) using screws and / or bolts, wherein the attachment can be made in a gas-tight manner. This can support a conventional connection technique for connecting the flange ring to a system component.

[0036] According to one embodiment of the present invention, the UHF antenna is designed to receive an electromagnetic wave triggered by a gas discharge or spark formation, particularly with a frequency between 100 MHz and 2 GHz. This allows for effective monitoring of the GIS.

[0037] According to one embodiment of the present invention, a gas-insulated switchgear assembly is provided, comprising a first assembly part and a second assembly part and a connecting structure (conventionally also referred to as a "feedthrough") according to one of the preceding embodiments, which is connected to the first assembly part at a first end face and to the second assembly part at a second end face.

[0038] The GIS may include additional system components with additional electrical components therein. In particular, multiple connection structures may be provided according to embodiments of the present invention to enable monitoring at various locations within the GIS.

[0039] It should be understood that features which have been described, provided or explained individually or in any combination in connection with a connection structure for connecting two parts of a gas-insulated switchgear are also applicable, individually or in any combination, to a method of manufacturing or retrofitting or to a method of monitoring a GIS, according to embodiments of the present invention and vice versa.

[0040] According to one embodiment of the present invention, a method of manufacturing and / or retrofitting a connecting structure for connecting two parts of a gas-insulated switchgear assembly is provided, comprising mounting a UHF sensor at a cast resin injection opening of a metallic flange ring of the connecting structure.

[0041] According to one embodiment of the present invention, a method of monitoring a gas-insulated switchgear is provided, comprising using a UHF sensor with a UHF antenna mounted at a cast resin injection opening of a metallic flange ring of a connecting structure connecting two parts of the GIS, and detecting an electromagnetic wave generated within the GIS by means of the UHF antenna.

[0042] Embodiments of the present invention will now be described with reference to the accompanying drawings. The invention is not limited to the illustrated or described embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Fig. 1 schematically illustrates a gas-insulated switchgear (Type 8DN9) according to an embodiment of the present invention; Fig. 2 illustrates part of the Fig. 1 GIS shown, illustrating a connection structure ("feedthrough") according to an embodiment of the present invention; Fig. 3 illustrates a portion of a connection structure according to an embodiment of the present invention including a mold resin gate; Fig. 4 schematically illustrates a cross-sectional view of a connection structure (feedthrough) with a built-in UHF sensor according to an embodiment of the present invention; and Fig. 5 illustrates a detailed view of the Fig. 4 . DETAILED DESCRIPTION OF EMBODIMENTS

[0044] The schematically shown in Fig. 1 The illustrated gas-insulated switchgear (GIS) 1 according to an embodiment of the present invention comprises a first installation part 3 and a second installation part 5, both of which have corresponding outer walls and a corresponding interior space in which a first electrical component and a second electrical component (not illustrated) are arranged, respectively. The GIS 1 has further installation parts 7, 9, 11, which are connected to the first installation part 3 and the second installation part 5, respectively.

[0045] A connecting structure 13 according to the present invention is provided to connect the first system part 3 with the second system part 5. In particular, the Fig. 1 illustrated GIS has further connection structures 13 according to embodiments of the present invention, wherein each of these connection structures 13 has a corresponding UHF sensor with UHF antenna in order to be able to detect electrical waves generated within the GIS 1.

[0046] The circular section 15, which contains the connecting structure 13, is in Fig. 2 The connecting structure 13 has a metallic flange ring 17 and a cast resin inlet opening 19, which Fig. 2 is closed by a cover 21. The connecting structure 13 further comprises a Fig. 2 und Fig. 3 not illustrated part of the system 23 with UHF antenna 22, 24, which e.g. in Fig. 4 and 5 is illustrated.

[0047] Fig. 3 illustrates section 16 of the Fig. 2 , particularly in greater detail the cast resin inlet opening 19, while the cover 21 is removed. A cast resin material 25 can be seen, which is arranged within the flange ring 17 and has hardened there. The UHF antenna 23 can be in contact with the cast resin 25. As in Fig. 3 As can be seen, the cast resin pouring opening 19 is guided through a jacket surface 27 of the flange ring.

[0048] Fign. 4 , 5 illustrate a schematic representation of an overview sectional view and a detailed sectional view of the connecting structure 13, wherein the drawing plane is parallel to an end face of the flange ring 17. The casting resin 25 has been poured into the flange ring 17 through the casting resin pouring opening 19.

[0049] The conventional cover 21 is removed and instead a UHF sensor 23 is mounted on the flange ring.

[0050] The UHF sensor 23 with antenna is designed to fit into the sprue opening 19. It has a sensor electrode 24 at its end; this is then guided through a conductive shaft 22 to the connector 33. The mounting section 26 of the UHF sensor 23 is screwed into threaded holes on the outer surface 27 of the flange 17 with screws 28. The closing section 20 of the UHF sensor 23 carries the UHF antenna 22, 24 and simultaneously closes the sprue opening 19. The UHF antenna (22, 24) includes a sensor electrode 24 at a radially inner end, which is sensitive to electromagnetic waves.

[0051] The closing section 20 has a conductor feedthrough 31 through which an antenna signal detected by the UHF antenna 22, 24 can be conducted outward. The closing section 20 also has an electrical connection 33 on an outer side, which is electrically connected to the UHF antenna 22, 24.

[0052] Furthermore, a seal 35 is provided between the UHF sensor 23 and the flange ring 17, as can be seen from Fig. 5 is evident.

[0053] As from Fig. 4 As can be seen, the flange ring has a circular cylindrical shape. Furthermore, the flange ring 17 has holes 37 along a circumference 39. This allows each of the two end faces of the flange ring 17 to be mechanically connected to the first system part 3 or the second system part 5, for example, by means of screws and / or bolts.

[0054] At least one (three for three phases) electrical connecting electrode 41 is provided in the center of the flange ring, by means of which a first conductor (or a first electrical component) in the first system part 3 can be connected to a second conductor (or a second electrical component) in the second system part 5. The connecting electrode 41 is cast, for example, in the casting resin 25.

[0055] Pouring openings, such as pouring opening 19, can be present at many locations on the GIS. These openings can allow direct contact with the cast resin insulation. According to embodiments of the present invention, specially manufactured UHF sensors are placed at these openings. No SF6 gas work is required for installation or retrofitting to the GIS, nor is a shutdown of the system required.

[0056] Significant advantages according to embodiments of the present invention arise during installation or retrofitting. No additional work is performed on the GIS. The system does not require shutdown during installation, making the installation less expensive overall. Furthermore, the signal-to-noise ratio of the signals detected by the UHF antenna should be significantly better than that of conventionally used barrier sensors. Specially manufactured UHF sensors can be mechanically designed to fit the existing sprue openings. The sensor antenna can be tuned to this installation situation. The metallic ring of the flange can also serve as a shield against external electrical interference.

Claims

1. Connecting structure (13) for connecting two installation parts (3, 5) of a gas-insulated switchgear installation (1), comprising: a metallic flange ring (17); a casting resin pouring opening (19) in the flange ring (17); and a UHF sensor (23) having a UHF antenna (22, 24), the UHF sensor being fitted at the casting resin pouring opening, characterized in that the UHF sensor (23) has a fitting portion (26) for being fitted to the flange ring and a closing portion (20) for closing the casting resin pouring opening, wherein the UHF antenna (22, 24) is attached to the closing portion (20), the closing portion (20) of the UHF sensor (23) has an electrical connection (33) on the outside, the UHF antenna (22, 24) has a sensor electrode (24), which is sensitive to electromagnetic waves, at a radially inner end, and the sensor electrode is connected to the electrical connection (33) by a conductor (22), in particular by a conductive shaft (22).

2. Connecting structure according to the preceding claim, wherein the UHF antenna (23) is fitted in such a way that electromagnetic waves that are present within the flange ring (17) can be detected.

3. Connecting structure according to either of the preceding claims, wherein the casting resin pouring opening (19) passes through a lateral surface (27) of the flange ring (17).

4. Connecting structure according to one of the preceding claims, further comprising: an, in particular cured, casting resin material (25) within the flange ring (17), wherein the UHF antenna (22, 24) is fitted in such a way that it is in contact with the casting resin material (25).

5. Connecting structure according to the preceding claim, further comprising: at least one connecting electrode (41) which is surrounded by the casting resin material within the flange ring and by means of which a first conductor in a first installation part (3) of the gas-insulated switchgear installation can be connected to a second conductor in a second installation part (5) of the gas-insulated switchgear installation.

6. Connecting structure according to any of the preceding claims, wherein the UHF antenna has the conductor (22), by way of which a detected antenna signal can be output to the outside.

7. Connecting structure according to any of the preceding claims, wherein the electrical connection is electrically connected to the UHF antenna (22, 24).

8. Connecting structure according to any of the preceding claims, wherein the closing portion (20) and / or an edge of the flange ring, the edge delimiting the casting resin pouring opening, has a seal (35).

9. Connecting structure according to any of the preceding claims, wherein the flange ring (17) is substantially circularcylindrical.

10. Connecting structure according to any of the preceding claims, wherein the flange ring (17) has holes (37) along a circumference (39), in order to be able to attach a respective installation part of the gas-insulated switchgear installation to each of the two end sides by means of screws and / or pins, wherein the attachment is performed in a gas-tight manner in particular.

11. Connecting structure according to any of the preceding claims, wherein the UHF antenna (22, 24) is designed for receiving an electromagnetic wave triggered by partial discharge in particular at a frequency of between 100 MHz and 2 GHz.

12. Gas-insulated switchgear installation (1), comprising: a first installation part (3) and a second installation part (5); and a connecting structure (13) according to any of the preceding claims, which is connected to the first installation part at a first end side and to the second installation part at a second end side.

13. Method of producing and / or retrofitting a connecting structure (13) for connecting two installation parts (3, 5) of a gas-insulated switchgear installation (1), wherein the connecting structure (13) is designed according to any of Claims 1 to 11, comprising: fitting a UHF sensor (23) having a UHF antenna (22, 24) at a casting resin pouring opening (19) of a metallic flange ring (17) of the connecting structure (13).

14. Method of monitoring a gas-insulated switchgear installation (1) by means of a connecting structure (13) according to any of Claims 1 to 11, comprising: using a UHF sensor (23) which is fitted at a casting resin pouring opening (19) of a metallic flange ring (17) of the connecting structure (13), which connects two installation parts (3, 5) of the gas-insulated switchgear installation (1); detecting an electromagnetic wave, which is produced within the gas-insulated switchgear installation (1), by means of the UHF sensor (23).