GB2599166A

GB2599166A - Subsea electrical module

Info

Publication number: GB2599166A
Application number: GB2015389.6A
Authority: GB
Inventors: Boe Ove
Original assignee: Siemens Energy AS
Current assignee: Siemens Energy AS
Priority date: 2020-09-29
Filing date: 2020-09-29
Publication date: 2022-03-30
Also published as: GB202015389D0

Abstract

A subsea electrical module 21, such as a subsea transformer 20 or subsea switchgear 23, comprises a housing 24, 26 and one or more bulkhead mounted connectors 32, 33. The housing comprises a plurality of structural panels, one or more of the panels 30, 31 being adapted to receive the bulkhead mounted connectors. The adapted panel is reinforced to provide greater strength than other non-adapted panels of the housing to allow the panel to withstand the mating force of the connectors.

Description

SUBSEA ELECTRICAL MODULE

This invention relates to a subsea electrical module for a subsea power system 5 and a method of connection Conventionally, electrical modules deployed subsea have been mounted within a structural steel frame, for example as described in EP2717401 and a panel with connectors for a remotely operated vehicle (ROY) has been mounted onto the structural steel frame. In order to connect the modules to equipment elsewhere in the system, which is outside the steel frame, flexible leads, or jumpers, are connected between the electrical module and the ROY panel. However, the structural steel frame is large, heavy and expensive to make and install and not always needed for the equipment. In accordance with a first aspect of the present invention a subsea electrical module comprises a housing and one or more bulkhead mounted connectors; wherein the housing comprises a plurality of structural panels, one or more of the panels being adapted to receive bulkhead mounted connectors, the panel being reinforced to provide greater strength than other non-adapted panels of the housing.

The bulkhead mounted connectors on the strengthened panel allow the module to be deployed subsea without an ROY panel on a steel frame being required. This saves considerable cost and weight, reducing the total number of cables. This improves overall reliability, as jumpers tend to leak water, so reducing the number, reduces the overall failure rate.

The module may comprise one of a subsea transformer, subsea switchgear, or variable speed drive.

The reinforced panel may comprise a metal panel having a thickness of between lmm and 3mm more than a non-adapted panel.

The module may comprise two reinforced panels located on opposite or adjacent sides of the module housing.

In accordance with a second aspect of the present invention, a subsea electrical power system comprises a plurality of subsea electrical modules according to the first aspect, the modules comprising at least one of a subsea transformer module and a subsea switchgear module.

An example of a subsea electrical module for a subsea power system in accordance with the present invention will now be described with reference to the accompanying drawings in which: Figure 1 illustrates a conventional subsea power system, components and connections; Figure 2 illustrates a subsea electrical module according to the invention; Figure 3 illustrates another embodiment according to the invention; As can be seen in Fig.], a conventional subsea power system, such as that described in EP 2 717 401, may comprise a subsea electrical power system 1 including, for example, a subsea transformer 2 and a subsea switchgear 3. The subsea transformer 2 typically comprises a subsea enclosure 4 and the transformer 5. The subsea switchgear 3 typically comprises a subsea enclosure 6 and the switchgear 7. The subsea transformer 2 and the subsea switchgear 3 are both mounted to and supported on the same common frame 8, which may for example be a subsea skid, which may be a construction of metal beams or the like. The enclosures 4, 6 are mounted to the frame 8 and are spaced apart by a certain distance. They are mechanically mounted to the frame 40 using brackets, clamps, bolts or the like.

The subsea transformer 2 has an electric connection, for example an umbilical 9, or cable, via which the transformer receives electric power, for example from a topside installation on a fixed or floating platform, or from an onshore site. The electric connection 9 may for example be provided by an umbilical or a subsea cable. Further intermediate electrical connections 10 in the form of flexible leads, or jumpers are taken from the transformer 5 and switchgear 7 to ROY panels 11, 12 mounted to the bars of the structural steel frame 8, so that the subsea transformer 2 and subsea switchgear 3 within the frame can be connected to the ROY panels. Each of these jumpers has a connector at each end that couples to a corresponding connector in the device, or ROY panel. The umbilical or cable 9 is connected by an ROY to the transformer ROY panel 12 using a wet mateable connector to a corresponding wet mateable connector part in the ROY panel 12. Cables 13 from other equipment (not shown) are connected by the ROY to the switchgear ROY panel 11 using a wet mateable connector to a corresponding wet mateable connector part in the ROY panel H. The separate ROV panels have been used because of the significant mating force applied by the ROV when connecting wet-mateable connectors.

This conventional arrangement has the disadvantage that the structural steel frame 8 is a very costly piece of equipment. Avoiding the need for this frame would reduce installation and manufacturing costs significantly, but even being able to reduce the size, or number of structural members, of the frame would still reduce costs.

In one embodiment of EP 2717401, instead of a jumper, an oil filled steel pipe is used to join two units subsea, with the busbar inside the oil filled pipe. However, this design cannot be disconnected subsea and if any part fails, that part has to be lifted and dealt with topside and the pipe with oil in has to be retrieved.

Fig.2 illustrates an electrical connection system for subsea power modules according to the present invention. In this case, there is no structural steel frame, but the subsea transformer 20 comprises an enclosure, or housing 24 around the transformer 25 that is provided with a reinforced structural panel 30 on one side, onto which a bulkhead mounted connector may be fitted. This connector connects the cable or umbilical 29 to the transformer, through the reinforced panel 30 of the bulkhead. Similarly, the subsea switchgear 23 comprises a housing 26 and the switchgear 27. One panel of the switchgear is a reinforced panel 31 into which bulkhead mounted connectors 33 may be fitted. The reinforced panels 30, 31 are adapted to have greater strength than the standard panels of the housings, for example, the side panels in Fig.2.

The structural panels typically comprise metal panels having a thickness of between lmm and 3mm more than a standard housing panel that has not been adapted to support bulkhead mounted connectors. The bulkhead mounted connectors connect cables from other parts of the system (not shown) In the example of Fig.2, the connectors are bulkhead mounted, i.e. they are mounted directly onto the wall of the enclosure containing the electrical parts. This allows for omitting or simplifying the stmctural frame. The bulkhead reinforcement may comprise a few millimetres of steel to withstand the mating force of the connector, but this mating force for suitable wet mate bulkhead mounted connectors is far lower than the mating force applied to an ROV panel of the conventional type.

Another application is for variable speed drives (1/SD) with a platform having volume compensators, where the frame would not be needed if bulkhead mounted connectors are used. In this example, a variable speed drive (1/SD) unit is mounted onto a rectangular steel frame with reinforcement, with a platform on the side, the VSD taking up only part of the space. The steel frame is mainly to prevent external damage, such as from ROVs swimming around. The protective frame may encompass many parts of a subsea system, rather than each individual unit needing its own protective frame, in order to protect against external damage, such as from anchors and trawlers.

All bulkhead connections may be located on side edges of the unit, so that they are accessible through gaps in the large frame, to allow for mating or demating The connections may be angled to keep cables within the protective frame.

Fig.3 illustrates another embodiment in which individual components 40, 44 of a subsea electrical power system, such as a transformer 25 and switchgear 27 in their housings 43, 42 are provided with two reinforced panels 30, 31 which are able to take bulkhead mounted connectors 32, 33. The modules are then connected together using cables 36 between bulkhead mounted connectors 34, 35. Connections from the switchgear 27 to loads, such as a variable speed drive 41 are by means of dry mated cables in the VSD and we mate connections 33 on the bulkhead panel 31 of the switchgear module 44. The example shows the reinforced panels 30, 31 on opposite sides of the module housing, but in other embodiments, the reinforced panels may be located on adjacent sides, so that the reinforced panels are orthogonal, i.e. on an end panel and a side panel next to one another, according to the location of the equipment that the bulkhead panel mounted connectors 33 need to connect to. Similarly, the connector 32 may be located on a side panel for better access The invention has the benefits of reducing the overall size and cost of the equipment to be deployed subsea, as well as increasing the reliability of the system, because there is no longer a need for a local platform or panel on the structural frame.

In addition, reducing the number of connectors and jumpers, each of which is a critical component representing a possible source of failure, will increase the reliability of the system. Furthermore, the cost of the connection system can be reduced because fewer parts are needed overall.

In some cases, there may be components in the system that do require the structural support frame, but by removing the need for an ROY panel, this frame can be made smaller, or have fewer elements making up the frame and so the overall cost is reduced.

An alternative solution is making the jumper sufficiently long to reach the other module into which it is to be connected, without the intermediate step of connecting it to the frame, but this is more complicated, as the jumper needs to be spooled up and attached to the subsea module during installation. This would require a penetrator and jumper gland each side and a long cable with the other half of the connector on the other device. For switchgear, this would result in using a lot of long jumpers, for example 3 each x 4 in one embodiment and those all need support It is not easy to spool up the long jumpers, so the end result would be expensive and cumbersome by comparison with the invention described hereinbefore.

The invention is applicable to various types of subsea device which would conventionally be mounted on a support frame, such as subsea transformers, subsea switchgear, subsea variable speed drives, or other types of subsea electrical modules.

Claims

CLAIMS1 A subsea electrical module comprising a housing and one or more bulkhead mounted connectors; wherein the housing comprises a plurality of structural panels, one or more of the panels being adapted to receive bulkhead mounted connectors, the panel being reinforced to provide greater strength than other non-adapted panels of the housing.
2. A module according to claim 1, wherein the module comprises one of a subsea transformer, subsea switchgear, or variable speed drive.
3. A module according to claim 1 or claim 2, wherein the reinforced panel comprises a metal panel having a thickness of between lmm and 3mm more than a non-adapted panel.
4. A module according to any preceding claim, wherein the module comprises two reinforced panels located on opposite or adjacent sides of the module housing.
5. A subsea electrical power system comprising a plurality of subsea electrical modules according to any preceding claim, the modules comprising at least one of a subsea transformer module and a subsea switchgear module.