NO20230681A1

NO20230681A1 - High-voltage subsea assembly

Info

Publication number: NO20230681A1
Application number: NO20230681A
Authority: NO
Inventors: Roberto Rosales; Frode Aasberg; Lars-Arne Abrahamsen; Marius Asak; Marcel T Michaelis; Simon Sköld
Original assignee: Benestad Solutions As
Priority date: 2023-06-13
Filing date: 2023-06-13
Publication date: 2024-12-16
Also published as: WO2024258291A1; NO348563B1

Description

HIGH-VOLTAGE SUBSEA ASSEMBLY

Technical Field

[0001] The present invention relates to the transfer of high electrical power through pressure barriers at subsea locations.

Background Art

[0002] High voltage wet-mate connectors are used to connect electric components and modules together after installation at a subsea location. A typical example is the connection between a large subsea transformer to a power cable. Since it is impractical to land the subsea transformer on the seabed while the power cable is connected to it, the connection must take place after landing on the seabed.

[0003] At the seabed, there may exist significant pressures. Some electrical components, such as said subsea transformers, may be pressure compensated, such that the oil inside their enclosures has substantially the same pressure as the ambient seawater. However, some electric subsea components are not pressure compensated. This leads to a significant pressure difference over the enclosure wall. A penetrator is used to guide the electric power through the enclosure wall without risking intrusion of seawater into the enclosure.

[0004] Connecting high-power subsea equipment at the seabed requires expensive equipment, such as service vessels and remotely operated vehicles (ROVs).

Furthermore, the equipment used to connect such equipment is expensive and sometimes delicate.

[0005] It is thus an aim to reduce the time necessary for installing such equipment.

[0006] Another object may be to reduce the complexity of the connecting components, such as cables, cable terminations, and wet-mate connectors, and thereby reduce the risk of failure. Equipment being complex and having more parts are more prone to failure than less complex equipment with less parts.

[0007] Still further objects will be clear to the skilled reader from the following discussion.

Summary of invention

[0008] According to the present invention, there is provided a high voltage subsea assembly configured for voltages above 12 kV. The high voltage subsea assembly comprises a high-voltage subsea component with a water-tight enclosure filled with a dielectric fluid. The enclosure has an enclosure wall with a wall aperture. The high voltage subsea assembly further comprises a high-voltage subsea cable terminated at its end to a male part or a female part, respectively, of a subsea high-voltage wetmate connector. The high-voltage subsea assembly further comprises a high-voltage penetrator assembly that comprises a penetrator with a penetrator body extending through the wall aperture and with a penetrator flange arranged in a sealing state against the enclosure wall, a female part or a male part, respectively, of the highvoltage wet-mate connector, rigidly attached to the penetrator. The male part or the female part of the high-voltage subsea cable is mated with the female part or the male part, respectively, of the high-voltage penetrator assembly.

[0009] The said dielectric fluid can typically be a dielectric oil, which is commonly used in subsea high-voltage transformers. It could also be a dielectric gas.

[0010] As defined above, the high-voltage subsea assembly is configured or rated for voltages above 12 kV but could instead be configured for voltages above 24 kV, 36 kV, or even above 60 kV. The indicated voltage values relate to phase-phase voltages.

[0011] With the term subsea cable is meant a cable of which at least a portion, for instance its end, is arranged at the seabed. Such a subsea cable can for instance extend from a location near the sea surface, e.g. from an offshore wind turbine down to a collector unit at the seabed. It may also extend entirely along the seabed, for instance between a collector unit and a subsea transformer.

[0012] In some embodiments, the high-voltage subsea component can be a subsea transformer comprising a transformer core and windings arranged inside the enclosure and wherein the dielectric fluid inside the enclosure is oil.

[0013] In other embodiments, the high-voltage subsea component can be a collector hub, a switchgear, a variable speed drive / variable frequency drive, or other highvoltage equipment having an enclosure with a dielectric fluid.

[0014] The wall aperture can in some embodiments extend through an upwardly facing and horizontally extending enclosure wall.

[0015] The penetrator body and the female part or the male part of the high-voltage penetrator assembly may extend in orthogonal directions.

[0016] The high-voltage subsea assembly may further comprise a high-voltage bridging unit fixed between the penetrator and the male part or the female part of the connector, forming a rigid assembly comprising the penetrator and male or female part.

[0017] In such embodiments, the high voltage bridging unit can typically comprise a main body with an inner bore, and a dielectric body radially within the inner bore, wherein the dielectric body comprises a first conical surface and a second conical surface. The high voltage bridging unit may further comprise a conductor unit of a conductive material at the axial center axis of the inner bore. The conductor unit can have a first conductor end and a second conductor end facing in opposite axial directions.

[0018] The high voltage bridging unit can advantageously further comprise two connection flanges.

[0019] The high voltage bridging unit provides flexibility for the operator when installing a high voltage subsea assembly at the seabed.

Detailed description of the invention

[0020] While various features of the present invention have been discussed in general terms above, a more detailed and non-limiting example of embodiment is given in the following with reference to the drawings, in which

Fig. 1 is a schematic view of an embodiment according to the prior art, illustrating how a subsea power cable is connected to a subsea transformer;

Fig. 2 is a schematic cross-section side-view through a high-voltage penetrator assembly according to the invention;

Fig. 2a is an enlarged view of a high voltage bridging unit;

Fig. 3 is a perspective view of the assembly shown in Fig.2;

Fig. 4 is a perspective view of another embodiment of a high-voltage penetrator assembly;

Fig. 5 is a schematic cross-section side-view through the assembly shown in Fig.4;

and

Fig. 6 is a side-view illustrating a high-voltage subsea assembly according to the invention.

[0021] Fig. 1 shows an embodiment according to prior art. A subsea power cable 101 shall be connected to a high voltage subsea transformer 103. The transformer 103 is schematically indicated and has an enclosure 105. The transformer 103 is installed on the seabed and is thus surrounded by seawater.

[0022] The enclosure 105 has an enclosure wall 107. A penetrator 109 is installed in the enclosure wall 107 in a sealed manner. The penetrator 109 comprises a penetrator flange 112 that is configured for attachment to the enclosure wall 107. Moreover, the penetrator flange 112 is provided with a sealing surface (not shown), for sealing abutment against a seal (not shown) for sealing between the penetrator flange 112 and the enclosure wall 107. Metal seals are typically used for large sea depths where the hydrostatic pressure is substantial.

[0023] A jumper 111 connects to the penetrator 109 via a jumper termination 113a. The jumper termination 113a functions as a dry-mate connector. Consequently, the jumper 111 is connected to the penetrator 109 before the subsea transformer 103 is lowered into the sea.

[0024] At the subsea location, the subsea power cable 101 is connected to the jumper 111 with a high-voltage wet-mate connector 115. The wet-mate connector 115 has a male part 115a and a female part 115b. The connection of the male part 115a and the female part 115b can typically be performed with the use of a remotely operated vehicle (ROV), as is common in the art.

[0025] Fig. 2 is a cross section view through a wet-mate penetrator 10 according to the present invention. The wet-mate penetrator 10 comprises a penetrator 9 and a female part 15b of a wet-mate connector.

[0026] The penetrator 9 has a penetrator flange 12 attached to an enclosure wall 7 of an enclosure of a subsea transformer. The penetrator 9 has a penetrator body 9a that extends through a wall aperture 7a of the enclosure wall 7. Indicated between the penetrator flange 12 and the enclosure wall 7 is a metal seal 14, which provides sealing between the penetrator 9 and the enclosure wall 7.

[0027] In the embodiment shown in Fig.2, a high voltage bridging unit 20 is used to connect the penetrator 9 to the female part 15b.

[0028] Fig. 2a depicts the bridging unit 20 in better detail with a cross-section side view. It comprises two connection flanges 21 that are used to connect the bridging unit 20 to the penetrator 9 and to the female part 15b, as shown in Fig.2. The connection flanges 21 protrude out from a main body 22. The main body 22 has an inner bore 23. Radially within the inner bore 23 there is arranged a dielectric body 24. The dielectric body 24 has a first conical surface 25a and a second conical surface 25b, which each are arranged at opposite axial ends of the high voltage bridging unit 20.

[0029] In the embodiments disclosed herein, the high voltage bridging unit 20 is configured to be mounted in either direction, as the two respective interfaces comprising the first and second conical surfaces 25a, 25b and the first and second conductor ends 26a, 26b are identical. However, in other embodiments the two interfaces may not be identical.

[0030] Moreover, while the first and second conical surfaces 25a, 25b are inwardly coned (like a funnel), they may also be outwardly coned.

[0031] The high voltage bridging unit 20 provides more flexibility when installing subsea equipment at a subsea location, as it allows quick connection to either a penetrator, or a male wet mate or female wet mate, without further adaptation or modification of said connectors.

[0032] Centrally located, at the center axis of the inner bore 23, there is arranged a conductor unit 26. The conductor unit 26 has a first conductor end 26a and a second conductor end 26b that protrudes in opposite axial directions. The first and second conductor ends 26a, 26b are configured to establish electric contact with the conductor in the penetrator 9 and the conductor in the female part 15b. As the skilled person will appreciate, the conductor ends 26a, 26b can also mate with the conductor of the male part 15a (as shown in Fig.5).

[0033] Fig. 3 depicts the wet-mate penetrator 10 with a perspective view.

[0034] Fig. 4 depicts a perspective view of another embodiment of a wet-mate penetrator 10 according to the invention. In this embodiment, it has a male part 15a with an axial direction being oriented 90 degrees with respect to the axial direction of the penetrator 9. A cross section through this wet-mate penetrator 10 is shown in Fig. 5.

[0035] Fig. 6 presents a schematic view a high-voltage subsea component 30 according to the invention. Depicted is the wet-mate penetrator 10 in Fig.4 and Fig.5 arranged in an upwardly facing enclosure wall 7 of a subsea transformer 3. As this image depicts, the subsea cable 1 is now directly connected to the wet-mate penetrator 10 with a female part 15b of a wet-mate connector 15. As the skilled reader now appreciates, the wet-mate penetrator 10 comprises one of the connecting parts of the wet-mate connector 15, namely the male part 15a or the female part 15b.

[0036] Although not discussed in detail above, the male part 15a, the female part 15b, and the penetrator 9, all have an electric conductor 4.

[0037] Reference is again made to Fig.1, which illustrates an embodiment of the prior art. In this embodiment, three terminations are used, namely two jumper terminations 113a at the ends of the jumper 111, and one cable termination 113b at the end of the subsea power cable 101. In the embodiment shown in Fig.6, however, only one termination is used, namely the cable termination 13b at the end of the subsea power cable 1.

[0038] While a subsea high voltage subsea transformer 3 is used in this example embodiment, it shall be clear that other subsea high-voltage components having an enclosure 5 can be used. Such components include for instance a subsea highvoltage switchgear, a subsea high-voltage collector unit, or a subsea high-voltage variable speed drive (VSD).

Claims

1. A high-voltage subsea assembly (30) configured for voltages above 12 kV, comprising

- a high-voltage subsea component (3) with a water-tight enclosure (5) filled with a dielectric fluid, wherein the enclosure (5) has an enclosure wall (7) with a wall aperture (7a);

- a high-voltage subsea cable (1) terminated at its end to a male part (15a) or a female part (15b), respectively, of a subsea high-voltage wet-mate connector (15);

wherein the high-voltage subsea assembly (30) further comprises a highvoltage penetrator assembly (10) comprising

- a penetrator (9) with a penetrator body (9a) extending through the wall aperture (7a) and with a penetrator flange (12) arranged in a sealing state against the enclosure wall (7);

- a female part (15b) or a male part (15a), respectively, of the high-voltage wet-mate connector (15), rigidly attached to the penetrator (9);

wherein the male part (15a) or the female part (15b) of the high-voltage subsea cable (1) is mated with the female part (15b) or the male part (15a), respectively, of the high-voltage penetrator assembly (10).

2. A high-voltage subsea assembly (30) according to claim 1, wherein the highvoltage subsea component (3) is a subsea transformer comprising a transformer core and windings arranged inside the enclosure (5) and wherein the dielectric fluid inside the enclosure (5) is oil.

3. A high-voltage subsea assembly (30) according to claim 1 or claim 2, wherein the wall aperture (7a) extends through an upwardly facing and horizontally extending enclosure wall (7).

4. A high-voltage subsea assembly (30) according to claim 3, wherein the penetrator body (9a) and the female part (15b) or the male part (15a) of the high-voltage penetrator assembly (10) extend in orthogonal directions.

5. A high-voltage subsea assembly (30) according to one of the preceding claims, wherein it further comprises a high-voltage bridging unit (20) fixed between the penetrator (9) and the male part (15a) or the female part (15b) of the connector (15), forming a rigid assembly comprising the penetrator and male or female part.

6. A high-voltage subsea assembly (30) according to claim 5, wherein the highvoltage bridging unit (20) comprises a main body (22) with an inner bore (23), a dielectric body (24) radially within the inner bore (23), wherein the dielectric body comprises a first conical surface (25a) and a second conical surface (25b), and further comprising a conductor unit (26) of a conductive material at the axial center axis of the inner bore (23), the conductor unit (26) comprising a first conductor end (26a) and a second conductor end (26b) facing in opposite axial directions.