WO2010051872A1

WO2010051872A1 - Electrical connections to watercraft

Info

Publication number: WO2010051872A1
Application number: PCT/EP2009/006269
Authority: WO
Inventors: Aaron Jack Stevens
Original assignee: Rolls-Royce Plc
Priority date: 2008-11-04
Filing date: 2009-08-28
Publication date: 2010-05-14
Also published as: GB0820099D0

Abstract

The invention provides a connection arrangement for electrical connection to a watercraft, the connection arrangement being electrically connected to a source of electrical power via subsea means and being provided within the confines of a waterway. At least part of the connection arrangement is provided in the region of the bed of the waterway. The arrangement may include a buoyant connection unit for connection to the watercraft. Also proposed is a related electricity supply system for supplying electrical power to a watercraft, the system including the aforementioned connection arrangement together with a transmitter carried by the watercraft and configured to transmit a signal; a receiver configured to receive said signal; and an actuator actuable in response to the receipt of said signal to move said connection unit from said stowage position to said operational position for connection to the watercraft. The invention further relates to a method involving use of the system.

Description

ELECTRICAL CONNECTIONS TO WATERCRAFT

The present invention relates to the connection of watercraft to external sources of electrical power. More particularly, the invention relates to a connection arrangement for electrical connection to a watercraft, an electricity supply system incorporating such a connection arrangement, and an associated method of connecting a watercraft to an external source of electrical power.

It is known to use marine vessels for the periodic maintenance of structures lying offshore such as offshore wind farms, tidal power sites, wave power sites and the like. Whilst a generally conventional marine vessel is located at the site of an offshore structure, the vessel is typically moored alongside the structure but remains reliant on the use of its main onboard engines in order to generate electrical power for both the operation of its onboard systems and for operation of certain equipment required on the offshore structure itself. As will be appreciated, with emissions from marine vessels falling under increasing scrutiny, and with certain countries or regions beginning to introduce coastal air emissions regulations, it can be disadvantageous or problematical to continue to use the onboard engines of moored marine vessels in this manner.

"Cold ironing" has long been used to provide shore-side electrical power to a ship moored in port in order to allow its main and auxiliary engines to be shut down, thereby reducing emissions when in port. Cold ironing involves the connection of a ship's onboard electrical system to a shore-side source of electrical power in order to permit emergency equipment, refrigeration, cooling, heating, lighting systems etc to be powered continuously while the ship loads or unloads its cargo. However, emissions concerns also apply to vessels moored just a few hundred metres, up to a few kilometres, away from port which is a particularly common practice for cruise ships. However, when ships are moored away from port in this manner it is currently not possible for them to "cold iron", thus necessitating the continued use of at least the ship's auxiliary engines. It is therefore an object of the present invention to provide an improved connection arrangement for electrical connection to a watercraft. It is another object of the present invention to provide an improved electricity supply system for supplying electrical power to a watercraft. It is a still further object of the present invention to provide an improved method of connecting a watercraft to an external source of electrical power.

According to a first aspect of the present invention, there is provided a connection arrangement for electrical connection to a watercraft, the connection arrangement being electrically connected to a source of electrical power via subsea means, and being provided within the confines of a waterway. Most preferably, it is envisaged that the connection arrangement will be provided at an offshore or coastal location.

The preferred connection arrangement of the present invention includes a substantially buoyant connection unit which may be either substantially permanently buoyant in water or may be selectively buoyant in water.

Preferably, the connection unit is tethered to the bed of the waterway, and may be tethered in such a way as to float on the surface of the waterway, either permanently, or only when specifically required to for connection to a watercraft.

Preferably the connection unit is tethered so as to be moveable between a stowage position at a first depth within the waterway and an operational position at a second depth within the waterway, the second depth being shallower than the first depth.

Conveniently, said stowage position is located substantially at or substantially adjacent the bed of the waterway.

Advantageously, said operational position is located substantially at or substantially adjacent the surface of the waterway. Most preferably, connection unit substantially floats on the surface of the water when in the operational position. The connection arrangement may optionally include a winch mechanism operable to move the connection unit from said operational position to said stowage position.

Said winch mechanism may additionally be operable also to move the connection unit from said stowage position to said operational position.

In some embodiments of the invention, the connection unit can be tethered to the bed of the waterway via an elongate arm which is pivotally connected to a base unit located (preferably anchored) on the bed of the waterway.

The connection arrangement of the present invention may further include a releasable retaining arrangement configured to releasably retain the connection unit in the stowage position.

The connection arrangement can be connected to a source of electrical power which itself is located within the confines of the waterway. However, it should be appreciated that the connection arrangement can alternatively be connected to a shore-based source of electrical power, for example by one or more cables.

In arrangements which are electrically connected to a power source located within the waterway, such as at an offshore site, the source of electrical power may be selected from the group comprising: a submerged turbine, a wind turbine, a wave power generator, a tidal power generator, and an underwater nuclear reactor.

According to another aspect of the present invention, there is provided an electricity supply system for supplying electrical power to a watercraft, the system including: a connection arrangement of the type defined above; a transmitter carried by the watercraft and configured to transmit a signal; a receiver configured to receive said signal; and an actuator actuable in response to the receipt of said signal to move said connection unit from said stowage position to said operational position for connection to the watercraft. According to a further aspect of the invention, there is provided a method of connecting a watercraft to an external source of electrical power, the method comprising the steps of: providing an electricity supply system as defined above, transmitting a signal from the transmitter on the watercraft, receiving said signal at said receiver, actuating said actuator in response to the receipt of said signal to move the connection unit from said stowage position to said operational position, and connecting said connection unit to the onboard electrical system of the watercraft.

Preferably, said method includes the further step of lifting the connection unit from said operational position onto the watercraft prior to said step of connecting the connection unit to the onboard electrical system.

So that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which:

Figure 1 is a schematic illustration showing a connection arrangement in accordance with a first embodiment of the present invention;

Figure 2 is a schematic illustration showing a connection arrangement in accordance with a second embodiment of the present invention, showing a connection unit in an initial stowage position;

Figure 3 is a view corresponding generally to that of Figure 2, but illustrating the connection unit in an alternate position;

Figure 4 is a view corresponding generally to that of Figure 3, that shows the connection unit in an operational position;

Figure 5 is a view corresponding generally to that of Figure 4, and illustrates the connection unit being lifted from its operational position on to a watercraft; Figure 6 is a schematic illustration of a connection arrangement in accordance with a third embodiment;

Figure 7 is a schematic illustration showing a connection arrangement (for example in accordance with the second embodiment) provided at the site of an underwater array of tidal turbines; and

Figure 8 illustrates the connection arrangement of Figure 7 forming part of an electricity supply system in accordance with another aspect of the present invention.

Turning now to consider the arrangement of Figure 1 in more detail, there is illustrated a connection arrangement 1 which is configured for convenient eiectricai connection to a watercraft 2. In the context of this patent specification the term watercraft is intended to refer to any convenient form of water-going craft or vessel, and is specifically intended to include surface vessels such as ships, but also submarine vessels.

The connection arrangement 1 is provided within the confines of a waterway indicated generally at 3. In this regard, the term waterway is intended to refer to navigable bodies of water, including both offshore and coastal regions of seas and oceans, but also inland waterways such as lakes and rivers.

The connection arrangement 1 comprises a substantially buoyant connection unit 4 which, due to its buoyancy in water, is arranged to float on the surface 5 of the water. The floating connection unit 4 is connected to a source of electrical power (not shown) by a subsea cable 6 extending downwardly from the connection unit 4 to a point located on the bed 7 of the waterway 3 from where the cable 6 extends along or under the surface of the bed 7 to the source of electrical power. In this regard, it should be appreciated that the source of the electrical power can either be located remote from the connection arrangement 1 , or can be located in the region of, and preferably generally adjacent, the connection arrangement 1. In particular embodiments, it is envisaged that the cable 6 will extend from the site of the connection arrangement 1 within the confines of the waterway 3 to the shore or bank of land for connection to a land-based source of electrical power.

The electrical cable 6 is anchored to the bed 7 by an anchor cable 8 extending from the electrical cable 6 to an anchor 9 which is securely attached to the bed 7 of the waterway 3. This anchor arrangement ensures that the location of the connection arrangement, and most particularly the floating connection unit 4, remains substantially fixed within the waterway 3.

As will therefore be appreciated, the connection arrangement illustrated in Figure i provides an electrical connection point within the waterway 3, remote from the shore or bank of land, for connection with the watercraft 2. In operation, the watercraft 2 approaches the site of the connection arrangement 1 and carefully draws alongside the floating connection unit 4. The crew of the watercraft 2 are then able to electrically connect the connection unit 4 to the onboard electrical systems of the watercraft 2, for example via a conventional waterproof "wet-mate" electrical connector, in order to draw electrical power from the remote electrical power source. When the vessel 2 is electrically connected to the connection arrangement 1 in this manner, the various onboard electrical systems and appliances carried by the watercraft 2 can be operated even when the main propulsive and auxiliary engines of the watercraft 2 are shut down. The connection arrangement of the present invention thus permits operation of the watercraft's electrical systems without operation of its engines, thereby permitting a reduction in polluting emissions from the watercraft 2.

As will be appreciated, it is important that the watercraft 2 remains substantially stationary with respect to the connection arrangement 1 whist connected to it. This can be achieved by anchoring the watercraft 2 to the bed 7 of the waterway using its own onboard anchors. However, in a preferred arrangement of the embodiment illustrated in Figure 1 , it is envisaged that the connection arrangement 1 will, in itself, serve as a mooring for the watercraft 2 thereby offering the benefit of avoiding the risk of the watercraft 2 damaging subsea cables or other subsea components, by use of an onboard anchor which could unintentionally drag and come into contact with such subsea cables or components. In such an arrangement, the floating connection unit 4 effectively serves as a floating anchor buoy to which the watercraft 2 may be moored. In such an arrangement, the length of electrical cable 6 extending between the connection unit 4 and the anchor 9 effectively serves as a tether or rode, and so is provided in the form of a high tensile cable of sufficient strength to anchor the watercraft 2 on station at the site of the connection arrangement 1.

Turning now to consider Figure 2, there is iiiustrated an alternative connection arrangement 10 which, in certain respects, resembles the connection arrangement illustrated in Figure 1. However, the key difference between the connection arrangement 10 of Figure 2 and the connection arrangement 1 of Figure 1 is that in the arrangement of Figure 2, the buoyant connection unit 11 is arranged to adopt a stowage position (indicated generally in Figure 2) beneath the water surface 5 when not in operation. In this arrangement, the connection unit 1 1 is most preferably arranged so as to be substantially permanently buoyant in water. However, as will be explained hereinafter, it is also envisaged that a modified form of the arrangement illustrated in

Figure 2 could incorporate a selectively buoyant connection unit 11.

As indicated above, Figure 2 shows the buoyant connection unit 11 in its stowage position beneath the water surface 5. In this position, the connection unit 11 is realisably held at a first depth generally adjacent the bed 7 of the waterway 3. A base unit 12 is securely anchored to the bed 7 and incorporates a releasable retaining mechanism (indicated generally at 13) configured to realisably hold the buoyant connection unit 1 1 in its stowage position. The base unit 12 also houses a winch mechanism comprising a winch drum 14 on which is wound a tether 15 securely connected to the underside of the buoyant connection unit 11. The releasable retaining mechanism 13 comprises a solenoid actuator 16 arranged to control a locking pin which, in the stowage position illustrated in Figure 2, extends through a locking aperture provided in a locking element 17 extending downwardly from the buoyant connection unit 11.

As will therefore be appreciated, with the connection unit 11 retained in its stowage position illustrated in Figure 2, the connection unit 11 is held at the bottom of the waterway 3 thereby allowing the free passage of watercraft 2 over the site of the connection arrangement 10 when the connection arrangement is not required for connection.

Figure 3 illustrates the connection arrangement 10 during deployment of the buoyant connection unit 11. Upon actuation of the solenoid actuator 16, the blocking pin is removed from engagement with the locking element 17, thereby permitting the buoyant connection unit 11 to float upwardly towards the water surface 5 as indicated generally by arrow 18. As the connection unit 11 floats to the surface in this manner, the tether 15 is allowed to pay out from the winch 14. In preferred arrangements, the winch 14 is braked in order to provide for controlled pay out of the tether 15 so that the connection unit 11 moves relatively slowly towards the water surface 5 in order to prevent damage to the internal components of the connection unit 11.

Figure 4 illustrates the connection unit 11 in its operational position in which it floats on the water surface 5 for connection to the watercraft 2 in generally the same manner as discussed above in the context of the arrangement of Figure 1. The operational position is thus defined at a second depth (preferably zero) being shallower than the first depth defining the stowage position.

Figure 5 illustrates the connection unit 11 being lifted from its operational position in which it floats on the water surface 5, on to the deck of the watercraft 2. As illustrated, the connection unit 1 1 may be provided with a lifting loop or strop 19 for convenient engagement by a lifting hook 20 of a lifting arrangement carried by the watercraft 2 and which may, for example, comprise a davit 21.

Figure 6 illustrates another alternative embodiment of connection arrangement illustrated generally at 22. In this arrangement, the connection unit 23 is fixedly secured to one end of an elongate arm 24 which is preferably substantially rigid. The other end of the arm 24 is pivotally connected to a base unit 25 which is securely anchored to the bed 7 of the waterway 3. As in the case of the embodiments described above and as shown in Figures 1 to 5, the connection unit 23 is electrically connected to a source of electrical power by a cable 6.

Figure 6 illustrates the connection unit 23 in its stowage position in which it lies generally adjacent the bed 7 of the waterway 3. The connection unit 23 is moved from this stowage position to its operational position at or near the water surface 5 via pivotal movement of the arm 24 about its connection to the base unit 25. In arrangements where the connection unit 23 is configured to be substantially buoyant in water, this pivotal movement of the arm 24 can be effected by simply releasing the arm relative to the base unit 25, such that the connection unit 23 is allowed to float to the surface following an arcuate path defined by the pivoting arm. However, with this general arrangement the connection unit 23 may not be buoyant in water at all, in which case it is envisaged that an actuating mechanism will be provided within the base unit 25 in order to drive the arm 24 from the generally horizontal position illustrated in Figure 6 to a raised position in which the connection unit 23 lies on or generally adjacent the water surface 5.

Figure 7 illustrates a connection arrangement in accordance with the present invention provided at the site of a subsea renewable source of electrical power, within the confines of the waterway 3. Whilst it should be appreciated that any of the previously described embodiments of the connection arrangement could be provided in this manner, the arrangement illustrated schematically in Figure 7, and also in Figure 8, most closely resembles the connection arrangement 10 described above with reference to Figures 2 to 5. Figure 7 illustrates the connection arrangement 10 provided at the site of a subsea array of tidal turbines indicated generally at 26. As will be appreciated, the array of tidal turbines is arranged below the water surface 5, with each of the tidal turbines being anchored to the bed 7 of the waterway 3 and arranged to be driven by underwater tidal currents flowing in the waterway 3 in order to generate electrical power therefrom. The tidal turbines of the array 26 are thus electrically connected to a monitoring/control station 27 on the shore 28, remote from the site of the tidal array, via an electrical grid arrangement 29. The connection arrangement 10 is electrically connected to the grid 29 at the site of the tidal array 26, via the electrical cable 6.

As wiii be appreciated, Figure 7 iiiustrates the connection unit i 1 of the connection arrangement 10 in its stowage position 1 1 in the region of the bed 7 of the waterway.

Figure 8 illustrates a watercraft 2 such as a service vessel approaching the site of the tidal array 26, for example in order to service or repair the array 26. Whilst the surface vessel 2 is on site at the tidal array 26, it is advantageous to shut down the vessel's main propulsive engine and any auxiliary engines burning fossil fuels in order to reduce emissions whilst at the site of the tidal array 26. The vessel 2 is provided with a transmitter 30 which is activated as the vessel 2 approaches the site of the tidal array 26 in order to emit a signal (indicated schematically at 31) by way of a request to electrically connect to the grid 29. The signal 31 is received by a shore-based receiver 32 which is provided at the site of the monitoring/control station 27. Upon receipt of the signal 31 by the receiver 32, the monitoring/control station 27 sends an appropriate signal to the underwater connection arrangement 10, effective to actuate the actuator, thereby initiating movement of the connection unit 11 from its stowage position towards its operational position on the water surface 5 for connection to the surface vessel 2. When the surface vessel 2 has finished on site at the tidal array 26, it sends another signal, via the transmitter 30 and the receiver 32, to the monitoring/control station 27, whereupon the connection unit 11 is winched back down towards the seabed 7, from its operational position to its stowage position where it is retained, by the releasable retaining mechanism, ready for subsequent use by the same or another service vessel 2.

The signal 31 transmitted from the service vessel 2 to the transmitter 32 can take any convenient form such as, for example, a radio signal or a satellite telephone signal. Communication between the underwater connection arrangement 10 and the monitoring/control station 27 may be via a separate conductor cable or, alternatively, and more preferably, by modulating control signals on to the grid connection conductors 29 in a manner which is known per se.

Whilst the electricity supply system and method of the present invention has been described above in the context of the system of Figures 7 and 8 in which the service vessel 2 transmits a signal to a shore based receiver 32, it should be appreciated that in variants of the invention, the receiver 32 can be provided at the site of the tidal array 27, or other renewable energy source, within the confines of the waterway 3. Also, whilst the renewable energy source has been described above as represented by an underwater array of tidal turbines, it should be appreciated that it could be represented by a single turbine, one or more wind turbines, one or more wave power generators or an underwater nuclear reactor.

When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components.

The features disclosed in the foregoing description, or in the following claims, or in the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for obtaining the disclosed results, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

While the invention has been described in conjunction with the exemplary embodiments described above, many equivalent modifications and variations will be apparent to those skilled in the art when given this disclosure. Accordingly, the exemplary embodiments of the invention set forth above are considered to be illustrative and not limiting. Various changes to the described embodiments may be made without departing from the spirit and scope of the invention.

Claims

A connection arrangement (1 , 10, 22) for electrical connection to a watercraft (2), the connection arrangement being electrically connected to a source of electrical power (26) via subsea means, and being provided within the confines of a waterway (3).

A connection arrangement according to claim 1 including a substantially buoyant connection unit (4, 11 , 23).

A connection arrangement according to claim 2 wherein the connection unit (4, 11 , 23) is selectively buoyant.

A connection arrangement according to claim 2 or claim 3, wherein the connection unit (4, 11 , 23) is tethered to the bed (7) of the waterway (3).

A connection arrangement according to any one of claims 2 to 4, wherein the connection unit (4, 11 , 23) is tethered so as to float on the surface (5) of the waterway (3).

A connection arrangement according to any one of claims 2 to 5, wherein the connection unit (1 1 , 23) is tethered so as to be moveable between a stowage position at a first depth within the waterway (3) and an operational position at a second depth within the waterway (3), the second depth being shallower than the first depth.

A connection arrangement according to claim 6, wherein said stowage position is located substantially at or substantially adjacent the bed (7) of the waterway (3). A connection arrangement according to claim 6 or claim 7, wherein said operational position is located substantially at or substantially adjacent the surface (5) of the waterway (3).

A connection arrangement according to any one of claims 5 to 7, including a winch mechanism (14) operable to move the connection unit (11) from said operational position to said stowage position.

A connection arrangement according to claim 8, wherein said winch mechanism (11) is operable also to move the connection unit from said stowage position to said operational position.

A connection arrangement according to any one of claims 6 to 8, wherein said connection unit (23) is tethered to the bed (7) of the waterway (3) via an elongate arm (24) pivotally connected to a base unit (25) located on the bed (7) of the waterway (3).

A connection arrangement according to any one of claims 6 to 11 , further including a releasable retaining arrangement (16, 17) configured to releasably retain the connection unit (1 1 ) in said stowage position.

A connection arrangement according to any preceding claim, connected to a source of electrical power (26) which is located within the confines of the waterway.

A connection arrangement according to claim 13, wherein said source of electrical power (26) is selected from the group comprising: a submerged turbine, a wind turbine, a wave power generator, a tidal power generator, and an underwater nuclear reactor. An electricity supply system for supplying electrical power to a watercraft (2), the system including: a connection arrangement (10, 22) according to claim 6 or any preceding claim dependant upon claim 6; a transmitter (30) carried by the watercraft (2) and configured to transmit a signal (31 ); a receiver (32) configured to receive said signal (31 ); and an actuator (16) actuable in response to the receipt of said signal (31) to move said connection unit (11 , 23) from said stowage position to said operational position for connection to the watercraft (2).

A method of connecting a watercraft (2) to an external source of electrical power (26), the method comprising the steps of: providing an electricity supply system according to claim 15, transmitting a signal (31 ) from the transmitter (30) on the watercraft (2), receiving said signai (31) at said receiver (32), actuating said actuator (16) in response to the receipt of said signal (31 ) to move the connection unit (11 , 23) from said stowage position to said operational position, and connecting said connection unit (11 , 23) to the onboard electrical system of the watercraft (2).

A method according to claim 16, including the further step of lifting the connection unit (11 , 23) from said operational position onto the watercraft prior to said step of connecting the connection unit (11 , 23) to the onboard electrical system.