An offshore connecting system, a connecting device for the offshore connecting system and a method for assembling the offshore connecting system

Abstract

An offshore connecting system (1) comprising: an offshore station-keeping system (2) comprising a receiving portion (20) and a pass-through opening (21); one or more submarine electrical cables (3) with respective connection terminals (30); a connecting device (4) comprising a main body (40) removably connectable to the connection terminals (30) such that the main body (40) encloses said terminals (30) within an inner compartment (41); wherein the connecting device (4) is configured to be upwardly inserted through the pass-through opening (21) to be arranged in a predetermined resting position (R) relative to the receiving portion (20) of the offshore station-keeping system (2); and one or more blocking means (5) configured to be selectively arranged in a blocking position (a) for interacting with the connecting device (4) and the receiving portion (20) of the offshore station-keeping system (2) to selectively retain the connecting device (4) in the predetermined resting position (R).

Description

[0001] An offshore connecting system, a connecting device for the offshore connecting system and a method for assembling the offshore connecting system

[0002] TECHNICAL FIELD

[0003] The present invention relates to an offshore connecting system at least comprising an offshore station-keeping system (e.g. an offshore mooring structure, which may be pre-laid in an offshore location)), one or more submarine cables, a connecting device and one or more blocking means. The offshore connecting system belongs to the technical field of offshore power generation, such as wind power generation with floating offshore structures / platforms. The invention further relates to a connecting device for being used as part of the offshore connecting system. The invention also refers to a method for assembling the offshore connecting system.

[0004] PRIOR ART

[0005] The emerging field of floating offshore energy production platforms / structures (mostly wind turbine platforms, but also tidal platforms and solar platforms) is faced with the increased complexity of handling the electrical connection of these platforms to an electrical substation, which can be offshore or onshore depending on the wind farm layout. In fixed-foundation wind turbines, the electrical cables are pulled into the wind turbine support structure through an l-tube or J-tube, up to a dry deck in which the cable terminations can be connected to a switchgear. The cable here becomes fully static once connected, and can remain in place for the lifetime of the system, even if the turbine requires maintenance.

[0006] Floating wind turbine platforms however are not static structures but can typically move in six degrees of freedom under the influence of waves, wind and currents. Therefore, the static cable connection is not feasible, and a dynamic cable section is needed. This generates three significant problems, the first being that the dynamic cable section suffers dynamic loading through the relative motion of the platform and the cable itself. The second problem occurs in the installation process where there is no static structure in place to pre-connect the cable if the cable lay operation is done prior to the tow-out of the floating offshore wind turbine (FOWT) units, which will generally be the case. The third problem is that the floating platform may need to be towed to port to perform large component substitution on the wind turbine, for example, a blade or generator failure, and in such circumstances, provisions need to be in place to leave the electrical cable well protected so that it can be reconnected to the platform once it is towed back to site after repairs. An additional consideration is that in a typical wind farm layout, several FOWT units may be connected in a “daisy-chain” configuration, that is, with 2 to 10 or more FOWT units being connected in series to a substation. FOWT can also be connected in a ring configuration or in other multiple configurations. In these situations, not one but two or even three cables may need to be pulled into each FOWT unit, to maintain the continuity of the connection to the previous and next FOWTs in this series connection. If a single FOWT unit then needs to be towed to port, arises the additional problem of how to maintain this continuity in the connection so that the downstream FOWT units can continue operation.

[0007] A known technology for addressing the second and third problem mentioned above consists on encapsulating within a buoy a joint box to which the connecting terminals of one or more submarine cables are connected, this joint box being configured to be lifted into the platform with the help of a support vessel during installation, and afterwards in the event of a platform disconnect. However, in this solution there is no precise control over the position of the buoy. Also, an important drawback of this solution is that requires a vessel to intervene for arranging the joint box within the buoy (e.g. while the FOWT unit has not yet been towed to its position) and also for connecting, removing the joint box from the buoy and for subsequently connecting the joint box to the FOWT unit (e.g. to a respective switchgear).

[0008] The current invention therefore aims to provide a precise system description and method to overcome the limitations of the state of the art for this specific FOWT configuration.

[0009] SUMMARY OF THE INVENTION

[0010] The present invention aims to provide system, a device and a method that eliminates the above- mentioned problems, reducing complexity, and greatly improving reliability and serviceability of the floating offshore structures for power generation (e.g. as FOWT systems).

[0011] A first aspect of the invention refers to a system (also referred to as an offshore system or as an offshore connecting system) for arranging / receiving one or more submarine cables (also referred to as dynamic cables). This system may be a system for receiving one or more submarine cables for connection to an offshore power (i.e. electric) generator (i.e. the one or more submarine cables are intended / configured to be connected to an offshore power generator, wherein said power generator may or may not be part of the system). The system according to the first aspect comprises an offshore station-keeping system (e.g. a pre-laid mooring structure, such as a tension leg platform), one or more submarine electrical cables and a connecting device for connecting the one or more electrical cables to the offshore pre-laid mooring structure. In the context of the present invention, an offshore station-keeping system refers to a system configured for connecting a floating offshore platform or structure (e.g. a floating offshore wind turbine platform / structure) to the seabed to maintain the floating offshore floating platform / structure in a predetermined location relative to the seabed. The offshore station-keeping system may comprise a base connected to the seabed and a connector for connecting a floating offshore. Such a system ensures the stability and operational reliability of the offshore floating structure by counteracting environmental forces such as wind, waves, and currents. An offshore station-keeping system may also be referred to as offshore static positioning system or as offshore stationary positioning system.

[0012] The offshore station-keeping system may, in some embodiments, be configured as a mooring structure or system, which may include components such as anchors, mooring lines (e.g. chains or cables), and at least one connector (for connecting a floating offshore structure), which provide a secure and resilient attachment to the seabed, enabling the floating offshore platform to remain stationary while accommodating dynamic movements induced by the marine environment. An offshore mooring structure / system, in the general context of offshore power generation (and in particular in the field of wind turbines), is a set of anchors, mooring lines (e.g. chains or cables), and other components (e.g. connectors) that are installed on the seabed prior to the deployment of the floating wind turbine structure / platform (offshore mooring structures may also be referred to as offshore pre-laid mooring structures). Offshore mooring structure is used to secure and stabilize floating offshore wind turbines in their designated locations, allowing them to generate electricity efficiently and safely, even in deepwater environments. A non-limiting example of offshore mooring structure is represented by tension leg platforms TLP, wherein a plurality of mooring lines (e.g. three or more; the mooring lines are also referred to as tendons) are tensioned to provide the necessary stability and support for a floating offshore structure of a wind turbine, thereby the TLP being configured to remain in a static or quasi-static position. A TLP normally comprises a buoyant body connected to a seabed anchor (i.e. a structure being embedded in the seabed that provide the necessary support for the mooring lines) by means of the plurality of mooring lines, wherein the buoyant body is configured to be connected to an external floating offshore structure (e.g. with a power generator, such as a wind turbine). Proper tensioning ensures that the turbine remains in its intended position and are configured to withstand the dynamic forces exerted by the marine environment. However, the pre-laid mooring system is also compatible with other configurations, such as with a catenary configuration.

[0013] The offshore station-keeping system (e.g. configured as an offshore mooring structure, which may comprise a base connected to the seabed and a floating body connected to the base by means of a plurality of mooring lines, wherein the floating body may comprise a connector for connecting a floating offshore platform) comprises a receiving portion (which may be arranged in the floating body, if any) for receiving the connecting device, wherein said receiving portion comprises a pass- through opening. The pass-through opening is configured to allow the passage of the connecting device and may be configured as a hole (e.g. with a closed or open perimeter). Preferably, offshore station-keeping system may be configured as an offshore pre-laid mooring structure, such as, for example, a tension-leg platform TLP (e.g. comprising a respective floating body).

[0014] The receiving portion may comprise (or may be configured as) a tubular section, wherein the pass- through opening may be part of said tubular section. The tubular section may be configured such that, when the connecting device is arranged in the predetermined resting position, the tubular section surrounds at least a part of the main body (e.g. the tubular section may be configured for restricting (e.g. limiting at last partially) the movement of the main body relative to the receiving portion when the connecting device is in the predetermined resting position). For example, the tubular section may be configured as a cylindrical tubular section. The pass-through opening may be arranged to have at least a part of the tubular section below its position (e.g. the through-pass opening is arranged at an upper end of the tubular section). It should be noted that the tubular section is vertically arranged (i.e. when the offshore station-keeping system is in its position of use) to allow the connecting device to be introduced through it upwardly. The area of the receiving position in which the through-pass opening is arranged may be configured to be coincidentally arranged with the predetermined resting position (e.g. the through-pass opening may be arranged in a part of the receiving portion that coincides with the position of the connecting device when arranged in its predetermined resting position; e.g. the through-pass opening may be arranged at an upper end of the tubular section).

[0015] The offshore station-keeping system (e.g. configured as an offshore mooring structure) may also comprise an optional hollow section surrounded by walls to provide a vertical path upwards to the connecting device (e.g. in the event that the connecting device has to be raised / lifted from the predetermined resting position upwards). This hollow section may be arranged above the tubular section (e.g. above the pass-through opening), wherein said hollow section may be configured as a tubular section having greater cross-sectional area than the pass-through opening. In some embodiments, the hollow section may have a cross-sectional area that increases as the height increases upwards (e.g. the tubular section being configured as an inverted truncated cone). In the connection of the hollow section with the pass-through opening there may be an optional support face (surrounding the pass-through opening). Each of the one or more submarine electrical cables respectively comprises one or more connection terminals (e.g. per each end of the cable). The offshore connecting system may comprise a single submarine electrical cable or may comprise a plurality of submarine electrical cables (e.g. two, three, four or more). Each of the one or more submarine electrical cables may be comprise a plurality of connection terminals. For example, the one or more submarine electrical cables may be configured as a three-phase cable, thereby comprising at least three connection terminals (i.e. per end of the cable). In the context of the current invention, the submarine electrical cables may be configured to transmit electrical power generated by offshore power generation systems, such as wind turbines (e.g. of floating offshore structures / platforms), to the shore or to substations, to interconnect multiple wind turbines located at a distance from each other or to import power from the mainland to the offshore facilities, especially in cases where energy storage or backup power is needed. Thus, at least some these submarine cables may be configured to carry the electricity produced by the power generators (e.g. wind turbines), allowing it to be integrated into the electrical grid for distribution.

[0016] The connecting device comprises a main body configured to be removably connected (i.e. detachably) to the one or more connection terminals of the one or more submarine electrical cables, such that the main body encloses said one or more connection terminals within an inner compartment of the main body, which is preferably configured to be watertight. The main body may be interpreted as a shell configured to protect and encapsulate the connection terminals. The connecting device is further configured to be upwardly (i.e. partially or totally in a vertical direction) inserted through the pass-through opening of the offshore station-keeping system (e.g. configured as an offshore pre-laid mooring structure) to allow the main body to be arranged in a predetermined resting position relative to the receiving portion of the offshore station-keeping station.

[0017] The one or more blocking means (also referred to as a locking system, i.e. the locking system may comprise one or more means of locking) may be configured to be selectively arranged in a blocking position, in which the blocking system interacts with the connecting device and the receiving portion of the offshore station-keeping system (e.g. configured as an offshore mooring structure) to selectively retain the connecting device in the predetermined resting position. The one or more blocking means may be configured to be part of the connecting device; or part of the offshore station-keeping system; or may be configured such that some blocking means are part of the connecting device and some blocking means are part of the offshore station-keeping system. Alternatively or complementarily, the system may comprise one or more blocking means that are external to the connecting device and to the offshore pre-laid mooring structure. The offshore connecting system may further comprise a floating offshore structure (also referred to as floating offshore platform) having a power generator. The power generator may be configured, preferably, as a wind turbine or as a solar panel or as a tidal generator. In those embodiments in which the power generation is specifically configured as a wind turbine, the floating offshore structure may be identified as a floating offshore wind turbine (FOWT). The floating offshore structure may be configured to be mechanically connected to the offshore station-keeping system (e.g. configured as an offshore mooring structure, preferably such that the floating offshore structure is connected to a floating body of the offshore mooring structure - e.g. when the offshore pre-laid mooring structure is configured as a TLP). The offshore station-keeping system (e.g. the offshore pre-laid mooring structure) may be configured as a single-point mooring system for the floating offshore structure. Preferably, the floating offshore structure may be connected to the offshore offshore station-keeping system (e.g. configured as a mooring structure) such that the floating offshore structure is configured to weathervane relative the offshore station-keeping system.

[0018] The floating offshore structure may further comprise a pivot column (also referred to as connecting column) configured to be mechanically connected to the offshore station-keeping system (e.g. configured as an offshore mooring structure), such that the floating offshore structure may be configured to be connected to the offshore station-keeping system by means of the connection of said pivot column to the offshore station-keeping system. Therefore, the floating offshore structure may be connected to the offshore station-keeping system at least (e.g. exclusively) by means of said pivot column (in other words the offshore station-keeping system may be configured as a single-point mooring system for the floating offshore structure, wherein the only point of the floating offshore structure connectable to the offshore station-keeping system may be the pivot column).

[0019] In preferred embodiments, the pivot column may be configured to be connected to the offshore station-keeping system (e.g. configured as an offshore mooring structure) such that a vertical axis (also referred to as pivoting axis) of the pivot column about which the pivot column is configured to rotate (e.g. to weathervane) is aligned (e.g. within a predetermined tolerance) with the through- pass opening (e.g. perpendicularly aligned with a centre of the through-pass opening) of the offshore station-keeping system, so that, when the connecting device is upwardly inserted through the pass-through opening, the connecting device is upwardly inserted in a direction aligned with the vertical axis of the pivot column. In other words, the offshore station-keeping system may be configured to be connected to the floating offshore structure such that, when said connection is made, the pivoting axis of the pivot column is aligned with the pass-through hole of the receiving portion of the offshore station-keeping system. This may be interpreted in the sense that, when floating offshore structure is connected to the offshore station-keeping system, then the pivoting axis is arranged substantially perpendicular to an area of the pass-through opening surrounded by its perimeter, preferably being perpendicular to the centre of said area. Accordingly, the predetermined resting position may be aligned with the pivoting axis.

[0020] In some embodiments, the offshore connecting system may further comprise a lifting system configured to be connected to the connecting device to lift / raise the connecting device from the predetermined resting position upwards. Upwards may be interpreted as indicating an ascending movement in a direction being at least partially vertical (i.e. having at least a vertical component), preferably fully vertical.

[0021] In some embodiments, the lifting system may be configured to lift the connecting device from the predetermined resting position (i.e. in the offshore station-keeping system, which may be configured as an offshore mooring structure) upwards to arrange the connecting device in an operating (i.e. operative / operational) position in the floating offshore structure. Preferably, the lifting system may be configured as part of the floating offshore structure. The operating position may be interpreted as the position of the connecting device in relation to the floating offshore structure which arranges the connection device close to the part of the offshore floating structure to which the connection terminals are to be connected (e.g. to receive the energy provided by a power generator of the offshore floating structure). Accordingly, the pivot column may comprise (or be configured to provide) an inner passage for allowing the connecting device to be lifted from the predetermined resting position to the operating position.

[0022] In more preferred embodiments, the lifting system may be arranged in the pivot column (e.g. within the pivot column) of the floating offshore structure and may be configured to lift the connecting device from the predetermined resting position upwards, preferably through an inner hollow part of the pivot column, to arrange the connecting device in an operating position within the pivot column of the floating offshore structure. Preferably, the floating offshore structure may be configured such that the operating position in the pivot column is arranged distally in a vertical direction above the predetermined resting position. For example, the floating offshore structure may be configured such that the operating position is coincidentally arranged with the pivoting axis of the pivot column, wherein, as previously described, the predetermined resting position in the offshore station-keeping system (optionally configured as an offshore pre-laid mooring structure) may also be aligned with the pivoting axis. Therefore, the lifting system may be configured to lift the connecting device from the resting position (i.e. in the offshore station-keeping system) upwards in a vertical direction aligned with the pivoting axis to arrange the connecting device in the operating position within the pivot column of the floating offshore structure.

[0023] The lifting system may comprise a cable and a pulling element (e.g. a motor for providing a pulling force to the cable). The cable may be configured to be connected to the connecting device (e.g. to a connecting portion of the connecting device). Thus, the cable may comprise a mechanical connector suitable for being connected to the connecting element, such as a mechanical clamp or a hook. In some embodiments, the lifting system may be configured as a winch. It is noted that, in some embodiments, the mechanical connector may be configured to be generically connected to the connecting element without requiring any further adaptation of the connecting element (e.g. the mechanical connector may be configured to embrace and / or clamp the connecting element).

[0024] In preferred embodiments, the floating offshore structure (e.g. the pivot column of the floating offshore structure) may comprise a switchgear suitable for connecting the one or more connection terminals of the one or more submarine electrical cables. The connecting device may be configured to be removed and disconnected from the connection terminals before connecting said terminals to the switchgear. The floating offshore structure may further comprise a support element (e.g. a platform) configured to be connected to the rest of the floating offshore structure by means of a bearing system. The bearing system may be configured to allow the floating offshore structure (e.g. the pivot column) to rotate relative to the support element, wherein the support element may be further configured to be solidly connected (e.g. indirectly, i.e. by means of intermediate elements) to the offshore station-keeping system (e.g. configured as an offshore mooring structure). Preferably, the support element may be arranged above the water level.

[0025] It should be noted that the fact that the connecting device can be arranged in a predetermined resting position relative to the offshore station-keeping system (which may optionally be configured as an offshore mooring structure), and then be subsequently lifted to an operating position relative to the floating offshore structure allows a reduction of the accumulation of fatigue stress in the one or more submarine electrical cables. The one or more submarine electrical cables are exposed to fatigue stresses that may compromise their service life. The stresses on the one or more submarine electrical cables should therefore be optimised as far as possible. In the present invention, when the connecting device is in its operating position, the one or more submarine electrical cables will accumulate fatigue stress in a specific area (i.e. the area that will determine the lifetime of the cable). In this sense, the offshore connecting system according to the first aspect of the invention allows to establish a predetermined resting position for the one or more submarine electrical cables, so that, when the cables are not going to be used to be connected to a floating offshore structure (e.g. when there is no floating offshore structure available, e.g. because it has not yet arrived or because it has been disconnected and separated from the offshore station-keeping system for, for example, maintenance work) the accumulation of fatigue will take place in a second part of the one or more cables, so that the lifetime of the submarine electrical cables in the operating position will not be compromised. In this way, the lifetime of the one or more submarine electrical cables is extended while allowing the cables to remain connected in series (daisy-chain connection) or other configurations (e.g. ring configuration) to other elements (e.g. other offshore power generation systems or substations).

[0026] The main body of the connecting device may further comprise a connecting portion configured to be connected to a lifting system (external to the connecting device) for lifting the connecting device from the predetermined resting position upwards. The lifting system may be configured as the previously described lifting system of the offshore connecting system, which is preferably arranged as part of the floating offshore structure.

[0027] The one or more blocking means may be configured such that, when arranged in the blocking position, the one or more blocking means are configured to prevent the main body of the connecting device from passing downwards through the pass-through opening. Thus, since the connecting device has been previously described as being configured to be upwardly inserted through the pass-through opening, then the fact of preventing the connecting device from passing downwards through the pass-through opening has to be understood as a way of ensuring that the connecting device is retai ned / locked at the predetermined resting position.

[0028] Preferably, the one or more blocking means may be further configured such that, when arranged in the blocking position: the one or more blocking means (or at least a part of said one or more locking means) provide the main body of the connecting device with an additional / increased width being greater than a width of the pass-through opening; and / or the one or more blocking means (or at least a part o said one or more locking elements) engage between the main body and the receiving portion (e.g. a part of the receiving portion) of the offshore station-keeping system (which may be configured as an offshore mooring structure). In some embodiments, a first subgroup of blocking elements may be configured to increase the width of the main body and / or a second group of blocking elements may be configured to engage between the receiving portion and the connecting element. It should be noted that the increase of width of the main body of the connecting device may be obtained by configuring the one or more blocking means (or a subgroup of them, e.g. a first subgroup) to locally increase the width of the connecting device. In some embodiments, at least some (i.e. a group / subgroup / set) of the one or more blocking means (this group not necessarily being the same as the first and second subgroups described above) may be configured to be part of the main body. The one or more blocking means that are part of the main body may comprise: one or more blocking means fixed / attached to an external part of the main body and configured as extensions (e.g. protrusions) protruding from the main body, thereby providing the main body with a particular cross-section shape; and / or one or more blocking means that may be configured as respective mechanical connectors being movable between a retracted position, in which said blocking means are retracted against the main body such that the main body is allowed to pass through the pass-through opening (i.e. the blocking means in its retracted position are configured to allow passage through the pass-through opening, without creating an obstacle), and the blocking position, in which said blocking means are extended (i.e. protrude) from the main body such that the main body is prevented from passing through the pass-through opening (e.g. when the said blocking means are extended in the blocking position, they may be configured to engage with the receiving portion of the offshore station-keeping system -e.g. configured as an offshore mooring structure- and / or may be configured to provide the main body with an additional width being greater than a width of the through-pass opening).

[0029] When the main body comprises respective blocking means configured as (e.g. fixed / permanent) extensions protruding from the main body to form a particular cross-section shape, then at least a part of the receiving portion (e.g. the pass-through opening) of the offshore station-keeping system (e.g. configured as an offshore mooring structure) may be configured to fit the particular crosssection shape of the main body, such that the connecting device is allowed to pass through said part of the receiving portion only when the particular cross-section shape of the main body is aligned with the geometrical shape of the receiving section. Accordingly, said part of the receiving portion configured to fit the particular cross-section shape of the main body may be configured such that, when the particular cross-section shape of the main body is aligned with the geometrical shape of said part of the receiving portion, then the connecting device is allowed to be upwardly inserted through the receiving portion to allow the connecting device to be arranged at the predetermined resting position. Thus, when the connecting device (once duly inserted upwardly towards the resting position) is rotated (e.g. along a longitudinal axis of the connecting device, which may be a vertical axis) relative to the receiving portion such that the particular cross-section shape of the main body is no longer aligned with the part / section of the receiving portion having the same particular cross-section shape (e.g. reaching a position of misalignment), then the connecting device is prevented from being downwardly extracted through the receiving portion. The misalignment position corresponds to the blocking position of the relevant blocking means in this configuration. In some embodiments, independently of whether or not some blocking means are part of the main body according to any of the preceding embodiments, at least a set of the one or more blocking means may be part of the offshore station-keeping system (which may be configured as an offshore mooring structure). Said set may comprise one or more blocking means that are configured as respective mechanical connectors arranged at the receiving portion and configured to be engaged with a corresponding connection area of the connecting device. In some embodiments, said mechanical connectors may be configured to be movable between a retracted position, in which said blocking means are retracted against the offshore station-keeping system (e.g. against the receiving portion) such that the main body is allowed to pass through the opening, and the blocking position, in which said blocking means are extended from the offshore station-keeping system (e.g. from the receiving portion) such that the main body is prevented from passing through the pass- through opening (e.g. when the said blocking means are extended may be configured to engage with the main body of the connecting device).

[0030] In some embodiments, at least one or more of the one or more blocking means may be configured as elements being external to the main body and to the offshore station-keeping system (which may be configured as an offshore mooring structure) (i.e. the one more blocking means being an element of the system being independent from the main body and the offshore station-keeping system (which may be configured as an). Said blocking means may be configured to selectively provide the connecting device with an additional (i.e. increased) width when said blocking means are arranged in the blocking position “a”, wherein said additional width provides the connecting device with a width being greater than a width of the pass-through opening of the receiving section, thereby retaining the connecting device in its predetermined resting position. Thus, said blocking means may be configured to be arranged as a contact interface between the connecting device and the offshore station-keeping system when the connecting device is arranged in the predetermined resting position to retain the connecting device in the predetermined resting position. The one or more external blocking means may require a person or an auxiliary mechanical (or electromechanical) device (this device may be part of the system) to arrange it in the blocking position “a”, i.e. surrounding the main body of the connecting device. The external blocking means may be configured to engage with the connecting device.

[0031] A second aspect of the invention refers to a specific connecting device for connecting at least one submarine electrical cable to an offshore station-keeping system (which may be configured as an offshore mooring structure) in a system according to the first aspect of the invention. The connecting device of the second aspect of the invention comprises a main body configured to be removably connected to one or more connection terminals of at least one submarine electrical cable, such that the main body encloses said one or more terminals within an inner compartment, wherein the main body is further configured to be upwardly inserted through a pass-through opening of a receiving portion of the offshore station-keeping system to allow the main body to be arranged in a resting position relative to the offshore station-keeping system . Preferably, the inner compartment of the main body of the connecting device may be configured to be watertight.

[0032] The main body of the connecting device according to the second aspect of the invention further comprises one or more blocking means configured to be movable between a retracted position, in which the one or more blocking means are retracted against the main body such that the main body is allowed to pass through the opening, and a blocking position, in which said blocking means are extended from the main body such that the main body is prevented from passing through the pass-through opening (e.g. when the blocking means are extended, said blocking means may be configured to engage with the receiving portion of the offshore station-keeping system (which may be configured as an offshore mooring structure) and / or may be configured to provide the main body with an additional width being greater than a width of the through-pass opening).

[0033] The main body of the connecting device according to the second aspect of the invention further comprises a connecting portion configured to be connected to a lifting system of a floating offshore structure (e.g. a floating offshore structure of an offshore connecting system according to the first aspect of the invention) for pulling upwardly the main body from the resting position to an operating position in the floating offshore structure. The connecting portion may be configured as an orifice configured to receive a cable or to be engaged by a hook of the lifting system. Alternatively, the connecting portion may be shaped / configured to be clamped by a mechanical clamp of the cable of the lifting system.

[0034] The connecting device of the second aspect of the invention may further comprise one or more mechanical actuators connected to the one or more blocking means and configured to selectively move (e.g. with an automatic control) them between its retracted position and its blocking position.

[0035] The connecting device of the second aspect of the invention may further comprise one or more elastic means connected to the one or more blocking means. The one or more elastic means may be configured to provide a resisting force between the one or more blocking means and the main body forcing the blocking means towards the blocking position. Thus, in order to arrange the one or more blocking means in the retracted position, the resisting force provided by the one or more elastic means has to be overcome. The retracting means may be configured to be manually actuated (e.g. the retracting means may be configured as respective screws configured to be manually screwed). Alternatively, the retracting mean may comprise an automatic actuator - e.g. an electro-mechanical actuator - configured to overcome the resisting force of the elastic means to arrange the blocking means in the retracted position.

[0036] In those embodiments in which the connecting device comprises elastic means, the connecting device may further comprise a hood (also referred to as external jacket) (e.g. independent from the main body) configured to be inserted vertically and downwardly around the connecting device. The hood may comprise one or more sidewalls configured such that, as the hood is inserted to be arranged around the connecting device, the hood contacts the blocking means and forces them back into their retracted position “b”. The weight of the hood itself may be configured to overcome the resisting force exerted on the blocking means by the elastic means.

[0037] A third aspect of the invention refers to a method for assembling an offshore connecting system according to the first aspect of the invention (wherein this system may comprise a connecting device according to the second aspect of the invention). The method comprises (preferably in the order provided): connecting the connecting device of the system to the one or more connection terminals of the one or more submarine electrical cable such that the main body of the connecting device encloses said one or more terminals within the inner compartment of the connecting device; inserting upwardly the connecting device through the pass-through opening of the offshore station-keeping system (which may be configured as an offshore mooring structure) to arrange the main body in the predetermined resting position relative to the receiving portion of the offshore station-keeping system; and arranging the one or more blocking means in the / its blocking position such that the one or more blocking means interact with the connecting device and the receiving portion of the offshore station-keeping system to retain the connecting device in the predetermined resting position.

[0038] The method of the third aspect of the invention may further comprise (preferably in the order provided): connecting a floating offshore structure having a power generator, which is preferably configured as a wind turbine, to the offshore station-keeping system; connecting a lifting system to the connecting device; lifting the connecting device with the lifting system from the predetermined resting position upwards to arrange the connecting device in the operating position in the floating offshore structure; and electrically connecting the one or more terminals of the one or more submarine electrical cables to the power generator, wherein preferably this step further comprises disconnecting and removing the connecting device from the one or more terminals before connecting the one or more terminals of the one or more submarine electrical cables to the power generator.

[0039] The method may further comprise (e.g. for maintenance purposes; and preferably in the order provided): electrically disconnecting the one or more terminals of the one or more submarine electrical cables from the power generator; connecting the lifting system to the connecting device; wherein preferably, when the connecting device has been previously disconnected and removed from the one or more terminals, this step further comprises connecting the connecting device to the one or more connection terminals of the one or more submarine electrical cables such that the main body of the connecting device encloses said one or more terminals within the inner compartment; lowering the connecting device with the lifting system from the operating position in the floating offshore structure downwards to the predetermined resting position; and blocking the connecting device in the predetermined resting position with the one or more locking means;

[0040] Preferably, the method may further comprise: disconnecting the lifting system from the connecting device; and disconnecting the floating offshore structure from the offshore station-keeping system; and preferably moving the floating offshore structure away from the offshore station-keeping system.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figs. 1A-1 D show different views of an offshore connecting system 1 according to the first aspect of the invention comprising an offshore station-keeping system 2, a submarine electrical cable 3 and a connecting device 4 for connecting the submarine electrical cable 3 to the offshore stationkeeping system 2. Figs. 2A and 2B show an embodiment of the system 1 according to the first aspect of the invention in which the system 1 further comprises a floating offshore structure 6 having a power generator 60.

[0043] Figs. 3A-3D show different positions of a connecting device 4 relative to the rest of a system 1 of the first aspect of the invention, which may be a system 1 according to Figs. 2A and 2B.

[0044] Figs. 4A-4C show three different embodiments of a connecting device 4 according to the second aspect of the invention, the three embodiments being compatible with a system 1 of the first aspect of the invention.

[0045] Figs. 5A-5E depict different views of the connecting device 4 of Fig. 4A.

[0046] DETAILED DESCRIPTION OF THE DRAWINGS

[0047] Figs. 1A shows a lateral view of an offshore connecting system 1 according to the first aspect of the invention comprising an offshore station-keeping system 2 (which is optionally configured as an offshore pre-laid mooring structure 2), a submarine electrical cable 3 and a connecting device 4 for connecting the electrical cable 3 to the offshore station-keeping system 2. Fig. 1 B represents a top view of the system 1 , while Fig. 1C represents a cutaway view AA (see Fig. 1 B for reference of the cut plane AA) of the same system 1 and Fig. 1 D shows a detail view of the part encircled with the cercle B in Fig. 1C.

[0048] The offshore station-keeping system 2 shown in Figs. 1A-1 D is broadly compatible with a plurality of embodiments of the system 1 according to the first aspect of the invention. Figs. 1A-1 D represent the offshore station-keeping system configured as an offshore pre-laid mooring structure 2, more particularly, as a tension leg platform (TLP). The tension leg platform comprises a floating body 22 (e.g. a buoy; i.e. a body configured to have a significant amount of self-buoyancy), which is connected to the seabed through a mooring system that comprises three tension / leg elements (although in other embodiments the number of tension legs may be different, e.g. three, four, five or more). However, this offshore station-keeping system 2 is also compatible with other configurations, such as with a catenary configuration.

[0049] The submarine electrical cable 3 is depicted in Figs. 1A-1C as comprising a plurality of optional floating elements (e.g. three) attached to the cable 3 to provide the cable 3 with self-buoyancy. Figs. 1A-1 D depict a single submarine electrical cable 3, however the system 1 may comprise a single submarine electrical cable 3 or may comprise a plurality of submarine electrical cables 3 (e.g. two, three, four or more). Each of the one or more submarine electrical cables 3 may comprise a plurality of connection terminals 30 (e.g. one, two, three or more terminals).

[0050] Fig. 1 D shows a detailed and enlarged view of the area B shown in Fig. 1C. Fig. 1 D shows details of the configuration of the offshore station-keeping system 2 and the connecting device 4.

[0051] The offshore station-keeping system 2 comprises a receiving portion 20 for receiving the connecting device 4, wherein the receiving portion 20 comprises a pass-through opening 21 that is configured to allow the passage of the connecting device 4 and may be configured as a hole (with a closed or open permitter).

[0052] Fig. 1 D shows the optional configuration in which the receiving portion 20 comprises (or is configured as) a tubular section, wherein the pass-through opening 21 is part of said tubular section (e.g. is integrated in the tubular section). The tubular section 20 is configured such that, when the connecting device 4 is arranged in the predetermined resting position R, the tubular section 20 surrounds at least a part of the main body 40. The tubular section 20 is (optionally) configured for restricting the movement of the main body 40 relative to the receiving portion 20 when the connecting device is in the predetermined resting position R. In Fig. 1 D, the pass through-pass opening 21 is arranged to have at least a part of the tubular section below its position (e.g. the through-pass opening 21 is arranged at an upper end of the tubular section 20). The tubular section 20 is vertically arranged to allow the connecting device 4 to be introduced through it upwardly. The area / part of the receiving position 20 in which the through-pass opening is optionally configured to be coincidentally arranged with the predetermined resting position R (e.g. the through-pass opening 21 may be arranged in a part of the receiving portion 20 that coincides with the position of the connecting device 4 when arranged in its predetermined resting position R; e.g. the through- pass opening 21 may be arranged at an upper end of the tubular section 20).

[0053] The connecting device 4 comprises a main body 40 configured to be removably connected to the one or more connection terminals 30 of the one or more submarine electrical cables 3, such that the main body 40 encloses said one or more terminals 30 within an inner compartment 41 of the main body 40, which is preferably configured to be watertight. The connecting device 4 is further configured to be upwardly (i.e. partially or totally in a vertical direction) inserted through the pass- through opening 21 of the offshore station-keeping system 2 to allow the main body 40 to be arranged in a predetermined resting position R relative to the receiving portion 20 of the offshore station-keeping system 2. The system 1 comprises respective blocking means 5 (e.g. one or more) that are configured to be selectively arranged in a blocking position “a” in which the blocking system 5 interact with the connecting device 4 and the receiving portion 20 of the offshore station-keeping system to selectively retain the connecting device 4 in the predetermined resting position R.

[0054] Fig. 1 D shows the connecting device 4 arranged in the predetermined resting position R relative to the offshore pre-laid mooring structure 2. Dig. 1 D shows a particular embodiment in which the one or more blocking means 5 are part of the main body 40 of the connecting device 4. However, it should be noted that this arrangement for the one or more blocking means 5 is only shown for illustrative purpose, inasmuch as in other compatible embodiments the one or more blocking means 5 may be arranged as part of the offshore pre-laid mooring structure 2. Also, the offshore connecting system 1 may alternatively be configured such that at least a part / (sub)group / (sub)set of the one or more blocking means 5 are part of the main body 40 and / or such that at least a part(sub) / (sub)group / (sub)set are part of the offshore station-keeping system 2.

[0055] Fig. 1 D further shows that the offshore station-keeping system 2 also comprises a main connector 25 intended to connect a floating offshore structure 6 comprising a power generator 60. The main connector 25 may be configured to provide a mechanical connection configured to allow a rotation of the floating offshore structure 6 relative to the offshore station-keeping system 2 (e.g. for weathervaning purposes).

[0056] Fig. 1 D shows the offshore station-keeping system 2 comprises an optional hollow section surrounded by walls to allow the connecting device 4 to be lifted from the predetermined resting position R upwards. This hollow section is arranged above tubular section 20 (e.g. above the pass- through opening 21), wherein said hollow section is configured as a tubular section having greater cross-sectional area than the pass-through opening, e.g. by having a cross-sectional area that increases as the height increases upwards (e.g. the tubular section being configured as an inverted truncated cone). In the connection of the hollow section with the pass-through opening 21 there is an optional support face (surrounding the pass-through opening).

[0057] Figs. 2A and 2B show an embodiment of the offshore connecting system 1 according to the first aspect of the invention in which the system 1 further comprises a floating offshore structure 6 having a power generator 60. The embodiment of Figs. 2A-21 B is compatible with the embodiment of Figs. 1A-1 D.

[0058] The power generator 60 is configured as a wind turbine 60 (although in some compatible embodiments the power generator 60 may be configured as any other type of offshore power generator, such as a solar panel). The floating offshore structure 6 is configured to be mechanically connected to the offshore station-keeping system 2 (which may be configured as an offshore mooring structure 2) (e.g. to be mechanically connected to the floating body 22 of the offshore prelaid mooring structure 2), such that the floating offshore structure 6 is configured to weathervane relative the offshore station-keeping system 2. The offshore station-keeping system 2 is connected to the seabed F. Fig. 2A specifically shows the floating offshore structure 6 floating such that most of the structure is arranged above the water level W.

[0059] The floating offshore structure 6 of Figs. 2A-2B further comprises an optional pivot column 61 configured to be mechanically connected to the offshore pre-laid mooring structure 2 (e.g. by means of a main connector 25), such that the connection of the floating offshore structure 6 to the offshore pre-laid mooring structure is provided (e.g. exclusively) by the connection of the pivot column 61 to the offshore station-keeping system 2.

[0060] Figs. 2A-2B show the preferred and optional embodiments in which the pivot column 61 is configured to be connected to the offshore pre-laid mooring structure 2 such that a vertical axis 611 (also referred to as pivoting axis 611) of the pivot column 61 about which the pivot column 61 is configured to weathervane is aligned (e.g. within a predetermined tolerance) with the through- pass opening 21 (e.g. perpendicularly aligned with a centre of the through-pass opening 21) of the offshore station-keeping system 2, so that, when the connecting device 4 is upwardly inserted through the pass-through opening 21 , the connecting device 4 is upwardly inserted in a direction aligned with the vertical axis 611 of the pivot column 61.

[0061] Figs. 3A-3D show different positions of a connecting device 4 relative to the rest of a system 1 of the first aspect of the invention, which may be a system 1 according to Figs. 2A and 2B. Figs. 3A- 3D show enlarged views of a pivot column 61 of a floating offshore structure 6 conveniently connected to an offshore station-keeping system 2.

[0062] The system 1 shown in Figs. 3A-3D further comprises a lifting system 62 configured to be connected to the connecting device 4 to lift the connecting device 4 from the predetermined resting position R (shown in Fig. 3A) upwards. Figs. 3A-3D show the optional and preferred configuration in which the lifting system 62 is configured as part of the floating offshore structure 6 and is configured to lift the connecting device 4 from the predetermined resting position R (i.e. in the offshore pre-laid mooring structure) upwards to arrange the connecting device 4 in an operating position S (shown in Fig. 3C) in the floating offshore structure 6. The embodiment shown in Figs. 3A-3D shows the optional configuration in which the lifting system 62 is arranged in the pivot column 61 (e.g. within the pivot column 61) of the floating offshore structure 6 (preferably, the lifting system 62 being aligned with the pivoting axis 611 to lift the connecting device 4 along the direction of the pivoting axis 611) and being configured to lift the connecting device 4 from the predetermined resting position R upwards, preferably through an inner hollow part of the pivot column 61 , to arrange the connecting device 4 in an operating position within the pivot column 61 of the floating offshore structure 6.

[0063] The lifting system 62 may comprise a cable 620 and pulling element 62 (e.g. a motor for providing a pulling force for pulling the cable 620). The cable 620 may be configured to be connected to the connecting device 4 (e.g. to a connecting portion of the connecting device). Thus, the cable may comprise a mechanical connector suitable for being connected to the connecting element 4, such as a mechanical clamp or a hook. In some embodiments, the lifting system 62 may be configured as a winch.

[0064] The main body 40 of the connecting device 4 may further comprise a connecting portion 42 (see Figs. 4A-4C) configured to be connected to the lifting system 62 for lifting the connecting device 4.

[0065] Fig. 3A shows the connecting device 4 arranged in the predetermined resting position R relative to the offshore pre-laid mooring structure 2, whereas Fig. 3C shows the connecting device 4 being arranged in the operating position S relative to the floating offshore structure 6. Fig. 3B shows the connecting device 4 being lifted from the predetermined resting position R towards the operating position S. Fig. 3D shows the connecting device 4 conveniently removed from the connection terminals 30 of the one or more submarine electrical cables 3, such that the connection terminals 30 can be connected to a switchgear 64 of floating offshore structure 6. The switchgear 64 may be supported by a support element 65 (e.g. configured as a platform 65 or table 65) of the floating offshore structure 6, wherein said support element 65 may be connected to the rest of the floating offshore structure 6 by means of a bearing system configured to allow the floating offshore structure 6 (e.g. the pivot column 6) to rotate relative to the support element 65, the support element 65 being further solidly connected (e.g. indirectly, i.e. by means of intermediate elements) to the offshore pre-laid mooring structure 2. Preferably, the support element 65 may be arranged above the water level W. The support element 65 is broadly compatible with any of the embodiments of the system 1 described above, independently of the characteristics of the connecting device 4.

[0066] Figs. 4A-4C show three different embodiments of a connecting device 4 according to the second aspect of the invention, the three embodiments are compatible with a system 1 of the first aspect of the invention, so that any of the features described for the connecting elements 4 of Figs. 4A-4C may be included in the connecting device 4 of a system according to any of the embodiment shown in Figs. 1A-1 D, Figs. 2A-2B and 3A-3D.

[0067] For each of the two embodiments 4A-4B, two lateral views and two top views are provided: the left drawings show the configuration of the respective connecting device 4 with the blocking means 5 not being in the blocking position “a” (it should be noted that this position is referred to in the figures with the reference sign “b”) and the two right drawings show the configuration of the respective connecting device 4 with the blocking means 5 arranged in the blocking position “a”.

[0068] In all three embodiments of Figs. 4A-4C, the one or more blocking means 5 are configured such that, when arranged in the blocking position “a”, the one or more blocking means 5 are configured to prevent the connecting device 4 (e.g. the main body 40 of the connecting device 4) from passing downwards through the pass-through opening 21 , thereby ensuring that the connecting device 4 is retai ned / locked at the predetermined resting position R.

[0069] Fig. 4A depicts a connecting device 4 comprising a plurality of blocking means 5. The blocking means 5 are configured as respective mechanical connectors being movable between a retracted position “b”, in which said blocking means 5 are retracted against the main body 40 such that the main body 40 is allowed to pass through the pass-through opening 21 , and the blocking position “a”, in which said blocking means 5 are extended from the main body 40 to engage with the receiving portion 20 of the offshore pre-laid mooring structure 2, thereby preventing the main body 40 from passing (e.g. downwards) through the pass-through opening 21.

[0070] Fig. 4A shows the optional feature in which the connecting device 4 further comprises one or more elastic means 43 connected to the one or more blocking means 5. The one or more elastic means 43 are configured to provide a resisting force between the one or more blocking means 5 and the main body 40 forcing the blocking means 5 towards the blocking position “a”. Thus, in order to arrange the one or more blocking means 5 in the retracted position “b”, the resisting force provided by the one or more elastic means 43 has to be overcome. The connecting device 4 may further comprise retracting means (not shown in Fig. 4A) configured to overcome the resisting force provided the elastic means 43. Alternatively, the connecting device 4 may comprise one or more mechanical actuators (which may also be identified with the same reference sign 43 in Fig. 4A) connected to the one or more blocking means 5 and configured to selectively move them between its retracted position “b” and its blocking position “a”.

[0071] Although not shown in the figure, when the connecting device 4 comprises elastic means 43, the connecting device 4 may further comprise an independent hood (or jacket) configured to be inserted vertically and downwardly around the connecting device 4, wherein the hood may comprise one or more sidewalls configured such that, as the hood is inserted to be arranged around the connecting device 4, the hood contacts the blocking means 5 and forces them back into their retracted position “b”. The weight of the hood itself may be configured to overcome the resisting force exerted on the blocking means 5 by the elastic means 43.

[0072] Further, the connecting device 4 of Fig. 4A also comprises a connecting portion 42 configured to be connected to the lifting system 62 of the system according to the first aspect of the invention (e.g. the lifting system 62 arranged at the floating offshore structure 6). The connecting portion 42 of Fig. 4A is especially suitable for being clamped by a clamping element 621 arranged at an end of the cable 620 of the lifting system 62.

[0073] Fig. 4B depicts an alternative connecting device 4, wherein the blocking means 5 are configured to selectively provide the connecting device 4 with an additional (i.e. increased) width when said blocking means 5 are arranged in the blocking position “a”, wherein said additional width provides the connecting device 4 with a width being greater than a width of the pass-through opening 21 of the receiving section 20, thereby retaining the connecting device 4 in its predetermined resting position R.

[0074] The blocking means 5 of Fig. 4B is configured as an element being external to the main body 40, wherein said blocking means 5 is configured to be arranged as a contact interface between the connecting device 4 and the offshore station-keeping system 2when the connecting device 4 is arranged in the predetermined resting position R to retain the connecting device in the predetermined resting position R relative to the offshore station-keeping system 2 of an offshore connecting system 1 according to the first aspect of the invention. The blocking means 5 of the connecting device 4 shown in Fig. 4B are especially suitable for being used when the offshore station-keeping system 2 comprises a hollow section surrounded by walls to allow the connecting device 4 to be lifted from the predetermined resting position R upwards and arranged above the pass-through opening 21 , wherein said hollow section is preferably configured as a tubular section having greater cross-sectional area than the pass-through opening 21 , e.g. by having a cross- sectional area that increases as the height increases upwards (e.g. the tubular section being configured as an inverted truncated cone).

[0075] The external blocking mean 5 requires a person or an auxiliary mechanical (or electromechanical) device to arrange it in the blocking position “a”, i.e. surrounding the main body 40 of the connecting device 4. The external blocking means 5 may be configured to engage with the connecting device 4. Fig. 4C shows a third embodiment of the connecting device 4 for a system 1 according to the first aspect of the invention comprising a plurality of blocking means 5 (four) fixed / attached to an external part of the main body 40 and configured as extensions protruding from the main body 40, thereby providing the main body 40 with a particular cross-section shape. In the case of Fig. 4C the particular cross-section shape corresponds to a circle with four planar protrusions extending from the main body 40 with angles of 90 degrees between consecutive blocking means 5. However, it should be noted that this specific geometry is provided only for the purpose of providing an illustrative example, so that other geometries are compatible with the invention.

[0076] The connecting device 4 of Fig. 4C requires at least a part of the receiving portion 20 (e.g. the pass-through opening 21) of the offshore station-keeping system 2 to be configured to fit the particular cross-section shape of the main body 40, such that the connecting device 4 is allowed to pass through said part of the receiving portion 20 only when the particular cross-section shape of the main body 40 is aligned with the geometrical shape of the receiving portion 20. Accordingly, said part of the receiving portion 20 configured to fit the particular cross-section shape of the main body 40 may be configured such that, when the particular cross-section shape of the main body 40 is aligned with the geometrical shape of said part of the receiving portion 20, then the connecting device 4 is allowed to be upwardly inserted through the receiving portion 20 to allow the connecting device 4 to be arranged at the predetermined resting position R. Thus, when the connecting device 4 (once inserted upwardly towards the resting position R) is rotated (e.g. along a longitudinal axis of the connecting device 4, which may be a vertical axis) relative to the receiving portion 20 such that the particular cross-section shape of the main body 40 is no longer aligned with the part / section of the receiving portion 20 having the same particular cross-section shape (e.g. reaching a position of misalignment), then the connecting device 4 is prevented from being downwardly extracted through the receiving portion 20.

[0077] The connecting devices 4 depicted in Figs. 4B and 4C are especially suitable for being connected to a hook (or similar) at an end of the cable 621 of the lifting system 62. However, it should be noted that all the connecting devices 4 of any of the preceding embodiments are broadly compatible with all the different configurations described above for the connecting element 42.

[0078] Figs. 5A-5E depict different views of the connecting device 4 of Fig. 4A. In particular, Figs. 5C and 5E respectively show cutaway views of the connecting device 4. The connecting device 4 of Figs. 4A and 5A-5E further comprise respective retracting means 44 configured to overcome the resisting force provided the elastic means 43 to arrange the blocking means 5 in the retracted position “b”. The retracting means 44 may be configured to be manually actuated (e.g. the retracting means 44 may be configured as respective screws configured to be manually screwed). Alternatively, the retracting means 44 may comprise an automatic actuator configured to overcome the resisting force of the elastic means 43 to arrange the blocking means 5 in the retracted position “b”.

Claims

CLAIMS1. An offshore connecting system (1) comprising: a offshore station-keeping system (2) comprising a receiving portion (20) which comprises a pass-through opening (21), the offshore station-keeping system (2) being preferably configured as an offshore mooring structure, such as a tension-leg platform TLP; one or more submarine electrical cables (3), wherein each submarine electrical cable (3) respectively comprises one or more connection terminals (30); a connecting device (4) comprising a main body (40) configured to be removably connected to the one or more connection terminals (30) of the one or more submarine electrical cables (3) such that the main body (40) encloses said one or more connection terminals (30) within an inner compartment (41), which is preferably configured to be watertight; wherein the connecting device (4) is further configured to be upwardly inserted through the pass-through opening (21) of the offshore station-keeping system (2) to allow the main body (40) to be arranged in a predetermined resting position (R) relative to the receiving portion (20) of the offshore station-keeping system (2); and one or more blocking means (5) configured to be selectively arranged in a blocking position (a) in which the one or more blocking means (5) interacts with the connecting device (4) and the receiving portion (20) of the offshore station-keeping system (2) to selectively retain the connecting device (4) in the predetermined resting position (R).

2. The system (1) of claim 1 , wherein the receiving portion (20) comprises a tubular section, wherein the pass-through opening (21) is part of said tubular section, and wherein the tubular section is preferably configured such that, when the connecting device (4) is arranged in the predetermined resting position (R), the tubular section surrounds at least a part of the main body (40) for limiting a relative movement of the main body (40) in relation to the receiving portion (20).

3. The system (1) of any of the preceding claims, further comprising a floating offshore structure (6) comprising a power generator (60), preferably configured as a wind turbine (60), wherein the floating offshore structure (6) is configured to be mechanically connected to the offshore station-keeping system (2), preferably to a floating body (22) of the offshore stationkeeping system (2), such that the floating offshore structure (6) is configured to weathervane relative the offshore station-keeping system (2).

4. The system (1) of claim 3, wherein the floating offshore structure (6) further comprises a pivot column (61) configured to be mechanically connected to the offshore station-keeping system(2), such that the floating offshore structure (6) is configured to be connected to the offshore stationkeeping system (2) by means of the connection of said pivot column (61) to the offshore stationkeeping system (2); wherein preferably the pivot column (61) is configured to be connected to the offshore station-keeping system (2) such that a vertical geometric axis (611) of the pivot column (61) about which the pivot column (61) is configured to weathervane is aligned within a predetermined tolerance with the thorough-pass opening (21) of the offshore station-keeping system (2), so that, when the connecting device (4) is upwardly inserted through the pass-through opening (21), the connecting device (4) is upwardly inserted in a direction aligned with the vertical geometric axis (611) of the pivot column (61).

5. The system (1) of any of the preceding claims, further comprising a lifting system (62) configured to be connected to the connecting device (4) to lift the connecting device (4) from the predetermined resting position (R) upwards.

6. The system (1) of claims 4 and 5, wherein the lifting system (62) is configured to lift the connecting device (4) from the predetermined resting position (R) upwards to arrange the connecting device (4) in an operating position (S) at the floating offshore structure (6), wherein preferably: the lifting system (62) is part of the floating offshore structure; and / or the lifting system (62) is arranged in the pivot column (61) of the floating offshore structure (6) and is configured to lift the connecting device (4) from the predetermined resting position (R) upwards, preferably through an inner hollow part of the pivot column (61), to arrange the connecting device (4) in an operating position (S) within the pivot column (61) of the floating offshore structure (6).

7. The system (1) of any of the preceding claims, wherein the main body (40) of the connecting device (4) further comprises a connecting portion (42) configured to be connected to a lifting system (62) for lifting the connecting device (4) from the predetermined resting position (R) upwards.

8. The system (1) of any of the preceding claims, wherein the one or more blocking means (5) are configured such that, when arranged in the blocking position (a), the one or more blocking means (5) prevent the main body (40) of the connecting device (4) from passing downwards through the pass-through opening (21);wherein preferably the one or more blocking means (5) are further configured such that, when arranged in the blocking position (a): the one or more blocking means (5) provide the main body (40) with an additional width being greater than a width of the pass-through opening (21); and / or the one or more blocking means (5) engage between the main body (40) and the receiving portion (20) of the offshore station-keeping system (2).

9. The system (1) of any of the preceding claims, wherein at least a group of the one or more blocking means (5) are part of the main body (40), wherein: said group comprises one or more blocking means (5) that are fixed to an external part of the main body (40) and are configured as extensions protruding from the main body (40), thereby providing the main body (40) with a particular cross-section shape; wherein at least a part of the receiving portion (20) has a geometrical shape configured to fit the particular cross-section shape of the main body (40), such that the connecting device (4) is allowed to pass through said part of the receiving portion (20) only when the particular cross-section shape of the main body (40) is aligned with the geometrical shape of the receiving portion (20); and / or said group comprises one or more blocking means (5) that are configured as respective mechanical connectors being movable between a retracted position (b), in which said blocking means (5) are retracted against the main body (40) such that the main body (40) is allowed to pass through the pass-through opening (21), and the blocking position (a), in which said blocking means (5) are extended from the main body (40) such that the main body (40) is prevented from passing through the pass-through opening (21).

10. The system (1) of any of the preceding claims, wherein at least a set of the one or more blocking means (5) are part of the offshore station-keeping system (2), wherein preferably said set comprises one or more blocking means (5) that are configured as respective mechanical connectors arranged at the receiving portion (20) and configured to be engaged with the connecting device (4).

11. The system (1) of any of the preceding claims, wherein at least one or more of the one or more blocking means (5) are configured as elements being external to the main body (40) and to the offshore station-keeping system (2), wherein said at least one or more of the one or more blocking means are configured to be arranged as a contact interface between the connecting device (4) and the offshore station-keeping system (2) when the connecting device (4) is arrangedin the predetermined resting position (R) to retain the connecting device (4) in the predetermined resting position (R).

12. A connecting device (4) for connecting at least one submarine electrical cable (3) to an offshore station-keeping system (2) in a system (1) according to any of the preceding claims, wherein the connecting device (4) comprises: a main body (40) configured to be removably connected to one or more connection terminals (30) of a submarine electrical cable (3), such that the main body (40) encloses said one or more terminals (30) within an inner compartment (41), wherein the main body (40) is further configured to be upwardly inserted through a pass-through opening (21) of a receiving portion (20) of the offshore station-keeping system (2) to allow the main body (40) to be arranged in a predetermined resting position (R) relative to the offshore station-keeping system (2), wherein the main body (40) further comprises: one or more blocking means (5) configured to be movable between a retracted position (b), in which the one or more blocking means (5) are retracted against the main body (40) such that the main body (40) is allowed to pass-through the opening (21), and a blocking position (a), in which the one or more blocking means (5) are extended from the main body (40) such that the main body (40) is prevented from passing through the pass- through opening (21); and a connecting portion (42) configured to be connected to a lifting system (62) of a floating offshore structure (6) for pulling upwardly the main body (40) from the predetermined resting position (R) to an operating position (S) in the floating offshore structure (6); wherein preferably the inner compartment (41) of the main body (40) is configured to be watertight.

13. The connecting device (4) of claim 12, further comprises: one or more mechanical actuators connected to the one or more blocking means (5) and configured to selectively move them between its retracted position (b) and its blocking position (a); and / or one or more elastic means (43) connected to the one or more blocking means (5), wherein the one or more elastic means (43) are configured to provide a resisting force between the one or more blocking means (5) and the main body (40) forcing the blocking means (5) towards the blocking position (a), such that in order to arrange the one or more blocking means (5) in the retracted position (b) the resisting force provided by the one or more elastic means (43) has to be overcome.

14. A method for assembling a system (1) according to any of claims 1 to 11 , the method comprising: connecting the connecting device (4) to the one or more connection terminals (30) of the one or more submarine electrical cables (3) such that the main body (40) of the connecting device (4) encloses said one or more terminals (30) within the inner compartment (41) of the connecting device (4); inserting upwardly the connecting device (4) through the pass-through opening (21) of the offshore station-keeping system (2) to arrange the main body (40) in the predetermined resting position (R) relative to the receiving portion (20) of the offshore station-keeping system (2); and arranging the one or more blocking means (5) in the blocking position (a) such that the one or more blocking means (5) interact with the connecting device (4) and the receiving portion (20) of the offshore station-keeping system (2) to retain the connecting device (4) in the predetermined resting position (R).

15. The method of claim 14, further comprising: connecting a floating offshore structure (6) having a power generator (60), which is preferably configured as a wind turbine (60), to the offshore station-keeping system (2); connecting a lifting system (62) to the connecting device (4); lifting the connecting device (4) with the lifting system (62) from the predetermined resting position (R) upwards to arrange the connecting device (4) in the operating position (S) in the floating offshore structure (6); and electrically connecting the one or more terminals (30) of the one or more submarine electrical cables (3) to the power generator (60), wherein preferably this step further comprises disconnecting and removing the connecting device (4) from the one or more terminals (30) before connecting the one or more terminals (30) of the one or more submarine electrical cables (3) to the power generator (60).

16. The method of claim 15, further comprising: electrically disconnecting the one or more terminals (30) of the one or more submarine electrical cables (3) from the power generator (60); connecting the lifting system (62) to the connecting device (4); wherein preferably, when the connecting device (4) has been previously disconnected and removed from the one or more terminals (30), this step further comprises connecting the connecting device (4) to the one or more connection terminals (30) of the one or more submarine electrical cables (3) such that the mainbody (40) of the connecting device (4) encloses said one or more terminals (30) within the inner compartment (41); lowering the connecting device (4) with the lifting system (62) from the operating position(S) in the floating offshore structure (6) downwards to the predetermined resting position (R); and blocking the connecting device (4) in the predetermined resting position (R) with the one or more locking means (2); wherein preferably the method further comprises: disconnecting the lifting system (62) from the connecting device (4); and disconnecting the floating offshore structure (6) from the offshore station-keeping system (2); and preferably moving the floating offshore structure (6) away from the offshore station-keeping system (2).

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