WO2022259042A2

WO2022259042A2 - Mooring system and method for installing a floating platform using said mooring system

Info

Publication number: WO2022259042A2
Application number: PCT/IB2022/000334
Authority: WO
Inventors: Antonio Luís GARCÍA FERRÁNDEZ
Original assignee: Gazelle Wind Power Limited
Priority date: 2021-06-10
Filing date: 2022-06-10
Publication date: 2022-12-15
Also published as: CN117561198A; EP4353577A2; AR126134A1; WO2022259042A3; US20240278882A1

Abstract

The present invention relates to a mooring system for a floating platform, wherein said system eliminates the pitch and roll movements of the floating platform by using mooring lines (200) attached to the seabed (5), which are supported on several pulleys or rotary securing means (2, 3) of the floating platform (100) and are all attached to a shared counterweight (1) that hangs from the floating platform (100). Each mooring line (200) comprises a direct subline (200d) and a crossed subline (200c), which maintain the counterweight (1) always located to coincide with the central axis (300) of the floating platform (100). The invention further discloses a novel method for installing the floating platform at its intended site without the need for special vessels.

Description

Anchoring system and installation procedure for a floating platform using said anchoring system

DESCRIPTION

Object of the invention

The object of the present invention is an anchoring system especially indicated for floating platforms that serve as the base of wind turbines located in the sea. The anchoring system that is the object of this invention comprises a set of anchoring cables or chains (anchoring lines) attached to piles buried in the seabed or to weights located or deposited on the seabed.

The anchoring system object of the present invention has unique characteristics that make it ideal to be used on floating platforms that serve as a base for maritime structures where it is important to avoid pitching or rolling, also solving some drawbacks of other anchoring systems. anchoring for floating platforms of the state of the art.

The object of the present invention is also a procedure for installing a floating platform using the aforementioned anchoring system.

The anchoring system object of the present invention can be applied to any type of structure intended to float on the surface of the sea, and which needs to have several anchoring points on the seabed, to hold the anchoring cables or chains of the floating platforms. Background of the invention and technical problem to be solved

Floating platforms, especially those dedicated to supporting wind turbines for the generation of electrical energy from wind energy at sea, need anchoring systems that keep them in their position and contribute to their stability.

Platforms of the type called TLP (for the acronym in English of "Tension Leg Platform") are known in the state of the art. These platforms comprise three or more anchoring lines (usually chains or cables that join the platform with piles anchored to the bottom The mooring lines of the TLP platforms are designed to be placed in tension, joining the platform in a vertical position with each one of the piles anchored in the seabed.The TLP platforms comprise a set of floats designed to produce an excess of buoyancy of the platform (taking into account the weight of the structure that sits on the platform) This excess buoyancy guarantees a high level of tension in the cables, which in turn guarantees that they are always arranged in a vertical position. In this way, pitch and roll movements of the platform and of the structure that sits on the platform are avoided.

Document EP 2743170 A1 describes a TLP platform as described in the previous paragraph.

A drawback of the TLP platforms is that the high tension of the cables necessary to keep them in a vertical position and thus avoid pitching and/or rolling movements also causes a blockage of the platform's movements in the vertical direction. Thus, with rising tide, the platform cannot move up (because the mooring lines have little or no extensibility) and therefore the tension on the mooring lines increases considerably. This causes a high risk of breaking the mooring lines and makes it necessary to have mooring lines with a high section or to increase the number of mooring lines. Additionally, in TLP platforms, in situations of very low tide, the platform also lowers and the anchoring lines can loosen a lot, increasing the risk of the platform moving both vertically and laterally in an uncontrolled manner, and also increasing the risk of that pitching and/or rolling movements occur (due to the push of the wind and/or waves on the platform and the structure that sits on it) that can cause the platform to overturn.

In order to avoid the mentioned inconveniences, other types of floating platforms are known where the mooring lines are connected to a counterweight through pulleys located on the platform. These types of platforms allow the vertical and lateral movement of the platform in response to the tides, waves and wind, thus making it unnecessary to have a large number of anchoring lines or anchoring lines with a high section.

Document ES 2629867 A2 describes a platform like the one described in the previous paragraph.

An existing problem with the anchoring system described in the document mentioned in the previous paragraph is that the floating platforms that use said anchoring system are subjected to pitching and/or rolling movements that can become important, which makes that the funding system described in said document is not the most appropriate for:

- applications boarded by persons prone to motion sickness of the platform (ie non-marine professionals), such as young children, tourists, scientists, guests, and general visitors; floating platforms on which offshore marine wind turbines are installed, where it is important to avoid excessive rocking and/or pitching of the platform;

- applications in which the equipment installed and in which the activity to which they are dedicated (laboratories, research centers, factories) require small movements and accelerations of the platform; - Floating platforms that may be subjected (at some point) to extremely severe storms, which could jeopardize the safety of the structure itself or could even capsize it (if its pitching movement is very large).

Description of the invention

In order to solve the aforementioned drawbacks, the present invention refers to an anchoring system.

The anchoring system object of the present invention comprises a floating platform (for example, to support a wind turbine) and at least one pair of anchoring lines (for example, anchoring cables or anchoring chains), configured to fix or anchor the Floating platform to the seabed (for example, to some piles driven into the seabed, or to some bottom weights or anchoring ring deposited on the seabed) through at least one bottom section of each anchoring line.

Each mooring line also includes a central section attached to a counterweight.

Each pair of mooring lines comprises two mooring lines arranged in a plane that passes through a central axis of the floating platform. These anchoring lines arranged in the same plane are located respectively on one side and the other of the central axis of the floating platform.

The central axis of the floating platform is an axis that preferably defines a radial symmetry of the floating platform.

The anchoring system comprises at least one first rotary fixing means (for example, a pulley) for each anchoring line, where each first rotary fixing means is fixed to a first point on the floating platform and is configured to fix each line. anchoring to the floating platform at said first point of the floating platform, allowing the sliding of the anchoring line by said first rotating fixing means.

Newly, in the anchoring system object of the present invention:

- each anchoring line includes at least one direct subline and one crossed subline. These sublines are chains or cables that run parallel, at least in their bottom section. Each direct subline runs from the first rotating fixing means to the counterweight without passing through the central axis of the floating platform. Each crossed subline runs from the first rotating fixing means to the counterweight through the central axis of the floating platform. The first rotating fixing means can, for example, be formed by a pulley with two sheaves (for the passage/sliding of the two anchoring sublines), or by a set of two pulleys.

- the system comprises at least one second rotary fixing means (for example, a pulley) for each mooring line, where each second rotary fixing means is fixed to a second point on the floating platform and is configured to fix each crossed sub-line of each mooring line to the floating platform at said second point of the floating platform, allowing the sliding of the crossed subline by said second rotating fixing means, in such a way that each crossed subline runs from the first rotating fixing means to the counterweight firstly traversing the central axis of the floating platform and secondly sliding through the second rotary fixing means.

By means of the anchoring system described above, the pitching and/or rolling of the floating platform is canceled or drastically reduced, with respect to other anchoring systems such as the one described in document ES 2629867 A2., while leaving freedom for the floating platform can move vertically, also allowing restricted horizontal movements. By means of the mooring system described above, the pulley system used in other mooring systems using pulleys and cables in the state of the art is mechanically simplified. By not having central pulleys located in correspondence with the central axis of the floating platform, the anchoring system is simpler and also, all the central pulleys of all the arms that make up the system do not coincide at almost the same point.

Additionally, through the anchoring system described above, the pendulum movement, characteristic of the central counterweight, induced by the horizontal movements of the platform due to the waves, is eliminated.

Likewise, through the anchoring system described above, the need for a central well in the hull (main structure or central structure) of the platform is eliminated, which in the state of the art was necessary for the passage of the central sections. of the anchoring lines (those that hold the central counterweight).

Preferably, the floating platform comprises a pair of protruding structural arms for each pair of mooring lines. Thus, each pair of protruding structural arms comprises a first arm and a second arm located symmetrically with respect to the central axis of the floating platform. Each projecting structural arm is attached to a main structure (or hull) of the floating platform. Each protruding structural arm runs radially from a first end attached to the main structure of the floating platform to a second end projecting outward from the floating platform. Thus, the at least one first rotatable fixing means is fixed to the floating platform in correspondence with the second end of the first arm, and the at least one second rotatable fixing means is fixed to the floating platform at a point located in correspondence with the second arm.

The main structure (or hull) of the floating platform can comprise a geometry in the form of a cylindrical, conical or pyramidal shaft. Additionally, the mooring system can comprise a plurality of spokes connected to this main structure, where there is a flotation element at each free end of each spoke. These flotation elements can comprise at least one Floodable chamber. The main structure (or hull) of the floating platform may lack the aforementioned radii with flotation elements at their ends. However, the main structure or hull, with a shaft-shaped geometry, can include at least one flotation element. This at least one floating element can comprise at least one floodable chamber.

The flotation elements provide buoyancy and, when they are floodable, allow the floating platform to be moved or towed to its place or installation location, with a reduced weight and, later, flood the corresponding flotation elements, to provide tension to the anchoring cables, increasing its stability.

When the flotation elements are located at the end of the spokes attached to the shaft, the structure is particularly stable and appropriate to guarantee the stability of the floating platform during the installation maneuver.

As an alternative to the shaft-shaped geometry, the main structure (or hull) of the floating platform can comprise a ring-shaped geometry, said ring being joined by spokes to a cylindrical, conical or pyramidal shaft. This main structure can constitute a flotation ring (a ring-shaped float or flotation element). This floating ring can comprise at least one floodable chamber.

This floatation ring-shaped structure also provides great stability to the floating platform.

The mooring system can comprise at least one third rotating fixing means (for example, a pulley) for each mooring line. Each third rotary fixing means is fixed to a third point of the floating platform and is configured to fix each direct subline of each mooring line to the floating platform at said third point of the floating platform, allowing the direct subline to slide through said third rotary fixing means, in such a way that each direct subline runs from the first rotating fixing means to the counterweight by passing and sliding through the third rotating fixing means.

This third rotary fixing means allows the direct subline to run an intermediate section parallel to one of the protruding structural arms, so that the central section (which runs from the third rotary fixing means to the counterweight) runs closer to the axis center of the floating platform.

Additionally, the anchoring system can comprise at least one rotary guide means (for example, a pulley or grooved wheel) for each anchoring line, where each rotary guide means is fixed to a fourth point of the floating platform and is configured to guide the course of the crossed subline of each anchoring line allowing the sliding of the crossed subline by said rotary guide means, in such a way that each crossed subline runs between the first rotary fixing means and the second rotary fixing means passing and sliding through the rotating guide means.

This rotary guide means allows the cross subline to avoid obstacles on its way from the first rotary fixing means, through the central axis to the second rotary fixing means. By this rotary guiding means, it can be prevented that the crossed sublines of all mooring lines collide with each other, or that the crossed sublines collide with the main structure of the floating platform.

Preferably, each bottom section of each anchoring line comprises a buoy that divides the bottom section into a first portion that runs between the seabed and the buoy and a second portion that runs between the buoy and the at least one first portion. rotary fixing means.

The previous characteristic facilitates the installation of the floating platform, since the bottom weight, pile or anchoring ring can be arranged attached to a first portion of the bottom section (with the buoy) in a pre-installation maneuver (once the location of the floating platform) and, subsequently, connect the second portion of the bottom section directly to the buoy, when the floating platform and counterweight have moved to the installation site.

Also preferably, the counterweight of the anchoring system comprises at least one floodable flotation chamber. This characteristic also facilitates the transport of the counterweight (which can be transported without flooding with less weight), and also facilitates a progressive contribution of tension to the anchoring lines, as the at least one floodable flotation chamber fills up.

The present invention also refers to a procedure for installing a floating platform, using an anchoring system such as the one described above.

Thus, the installation procedure of a floating platform object of the present invention comprises:

- position and/or anchor to the seabed, under a place or installation location of the floating platform, at least one anchor and/or at least one bottom weight, and/or at least one anchoring ring and/or a set of piles; move the floating platform and the counterweight to its place of installation, where the at least one floodable chamber is not flooded;

- fix a free end of the bottom section of each mooring line: or at least one anchor and/or at least one bottom weight, and/or at least one mooring ring and/or to the set of piles, either; or to a buoy previously attached by means of a first portion of the bottom section of the anchoring line to at least one anchor and/or at least one bottom weight, and/or at least one anchoring ring and/or to the set of piles; fix a free end of the central section of each anchoring line to the counterweight;

- drag the floating platform laterally until the anchoring lines are taut, e; flooding the at least one floatation chamber.

In the anchoring system of the present invention, the floating platform does not need to rest on the bottom, so it is suitable for areas of any sea depth, both near the coast (for example, at a depth of 80 m), and far away. from it (up to depths of 1000 m or more) and at any intermediate distance, since it is capable of withstanding very severe storms.

In the preferred embodiments of the anchoring system of the invention, various platforms (for offshore wind turbines) are presented that are intrinsically stable in all their possible states, from manufacturing in port, to their final operating condition, passing through the transfer to the park. wind energy and the assembly phases of the system wiring, flooding of the counterweight and final adjustments. Therefore, the installation process is much simpler and faster. No special vessels are needed, just a small conventional tugboat.

The anchoring system of the invention allows the floating platform to be uninstalled and moved to another location, through an innovative procedure that is more simplified and faster than that proposed in ES 2629867 A2.

The anchoring system of the invention presents the following main characteristics and advantages: - It can be applied to any type of platform, especially for windmills and for platforms dedicated to maritime leisure activities;

Totally prevents pitch and roll movement of the platform, but allows horizontal or vertical movements;

- It does not need foundations, nor special preparation of the seabed (although conventional foundations that are simpler than usual can be used);

The optimal depths are between 50m and 400m, although it can reach greater depths;

- It can be installed or relocated (as many times as you want) without the need for special ships, you just need a tugboat to move it;

It can be adapted to capture the energy of the waves, simply by including one or several conventional generators;

The forces that appear in the anchoring lines are much less than in the TLP platforms; if any anchor line breaks, it continues to work with the others. In addition, it can be repaired / replaced on site;

It makes it possible to design much lighter platforms (and therefore more economical) and reduced uprights (with less visual impact);

The anchoring system of the invention is applicable to any floating marine installation, in which movement requirements are an important determinant of the design, especially for the following cases: - Tourism, maritime leisure and water sports; A platform designed with this type of anchoring is ideal for the hotel and recreation industry, since most of the potential clients of this type of facility are not expert sailors and the fact that it moves very little is a great attractive; A hotel can be installed, placing it in extraterritorial waters more than 10 nautical miles from the coast, so it could have rest, recreation, casino and game rooms, theme parks or any type of facility for which an equivalent facility on land You could encounter urban-planning impediments or have difficulties obtaining opening permits or have problems with current municipal regulations; Being far from the coast, the depth of the sea is greater and it is not possible to rest the hotel on the seabed; In addition, the waves are higher, so a conventional platform would move too much for this application.

- Wind farms. Windmills need a base that moves as little as possible, in fact, beyond a certain level of inclination (pitch) or a certain level of acceleration, the wind turbines must stop for safety reasons. The fact that it moves less than there are currently, increases the profitability of the installation, by having more net hours per year to generate electricity. In fact, all the preferred embodiments presented in this patent application refer to platforms specifically designed to support offshore wind turbines.

- Alternative energies. By its very nature, the proposed system reduces the pitch angle of the platform by extracting energy from the translational movement of the main float (buoyancy element). This is done by incorporating an electric generator to one of the pulleys (2 or 3) of the damping lines. The electrical energy generated can be used for the installation's own consumption or to send it to earth through the corresponding electrical cable. In fact, the present invention can be approached from two points of view: o As a renewable energy collector: It is a system that extracts energy from the movement of the platform caused by the waves, simultaneously canceling the annoying pitching and rolling movements of the platform; o As a comfort device: It is a system that cancels the pitching movements of the platform, which can also generate energy from the waves.

From the second point of view, the energy drawn from the damper lines can be directly dissipated as heat or can be converted into electrical energy. If it dissipates, the necessary equipment is cheaper and simpler, the movements of the platform would be the same, but the full potential of the system is not used. If it is decided to take advantage of the available energy, it can be stored in batteries or consumed on board at the facility.

Thus, one or more shock absorbing lines with or without energy collectors can be included in the mooring. The fundamental mission of these lines is to reduce the vibrations (oscillations) that can be produced as a consequence of the elasticity of the anchoring cables, in a system that is conceptually quite rigid (in general it is a hyperstatic system). These low/medium frequency vibrations could significantly increase the accelerations on the platform and make it unacceptable. The incorporation of shock absorber lines almost completely cancels these vibrations (oscillations).

These shock absorbing lines are very similar to blocking anchor lines (anchor lines attached to an anchor element or pile on the seabed), with the difference that one of its pulleys (internal or external) drives an electric generator. (if the energy is going to be used) or a hydraulic or electrical dissipator (if they only work as shock absorbers).

Brief description of the figures As part of the explanation of at least one embodiment of the invention, the following figures have been included, with an illustrative and non-limiting nature.

Figure 1: Shows a schematic front view, in rest position, of two mooring lines (arranged on the same plane) according to a possible embodiment of the mooring system object of the present invention.

Figure 2: Shows a schematic view of the theoretical displacement of two central mooring lines, in a counterweight mooring system according to the state of the art.

Figure 3: Shows the scheme of forces that act on a structure that uses the anchoring system object of the present invention.

Figure 4: Shows a schematic view similar to that of Figure 1, where the buoys of the bottom sections of the anchoring lines have been removed.

Figure 5: Shows a schematic view of the anchoring system of Figure 4, where said anchoring system has been displaced horizontally and vertically by the effect of waves and wind.

Figure 6: Shows a schematic view of the displacement of a mooring system in which the bottom sections of diametrically opposed mooring lines are parallel.

Figure 7: Shows a schematic view of the displacement of a mooring system in which the bottom sections of diametrically opposed mooring lines are divergent.

Figure 8: Shows a perspective schematic view of an anchoring system according to the present invention, where two pairs of anchoring lines (that is, four anchoring lines) arranged in respective perpendicular planes are observed. Figure 9: Shows a top view of the anchoring system of Figure 8.

Figure 10: Shows a schematic front view of a first installation phase of an anchoring system according to the present invention, where four protruding structural arms of the floating platform are observed (two of them in a plane perpendicular to the view of Figure ), which support four mooring lines of two pairs of mooring lines, and where the second portion (upper portion) of the bottom sections of the mooring lines has not yet been connected to the buoys of the first portion (lower portion). ) of the bottom sections of the mooring lines.

Figure 11: Shows a schematic view of the anchoring system of Figure 10, where the second portion of the bottom sections of the anchoring lines has already been connected to the buoys.

Figure 12: Shows a schematic view of the anchoring system of Figure 11, where the Floodable chambers of the flotation elements and the counterweight have been Flooded.

Figure 13: Shows a schematic side view of a first embodiment of the anchoring system according to the present invention, where a floating platform is observed that comprises a main structure in the form of a cylindro-conical shaft with four protruding structural arms that support four mooring lines, and where the main structure of the floating platform comprises four spokes connected to said main structure, each of the spokes comprising a flotation element at its end.

Figure 14: Shows a perspective view of the anchoring system of Figure 13.

Figure 15: Shows a schematic front view of the anchoring system of Figure 13 and Figure 14. Figure 16: Shows a schematic side view of a second embodiment of the anchoring system according to the present invention, where a floating platform is observed that comprises a main structure in the form of a cylindro-conical shaft with four protruding structural arms that support four anchoring lines, and where the main structure of the floating platform comprises three flotation elements.

Figure 17: Shows a perspective view of the anchoring system of Figure 16.

Figure 18: Shows a schematic front view of the anchoring system of Figure 15 and Figure 16.

Figure 19: Shows a schematic front view of a third embodiment of the anchoring system according to the present invention, where a floating platform is observed that comprises a main structure in the form of a flotation ring, with four protruding structural arms that support four anchor lines.

Figure 20: Shows a perspective view of the anchoring system of Figure 19.

Figure 21: Shows a schematic side view of the anchoring system of Figure 19 and Figure 20.

Detailed description

The present invention refers, as previously mentioned, to a mooring system comprising a floating platform (100).

Some elements that are mentioned in this description are defined below.

Float or flotation element (500): it is a closed and watertight envelope, totally or partially submerged in the water and that can be subjected to hydrostatic forces or hydrodynamics due to the effect of waves or marine currents. If partially submerged, it may also be subjected to wind forces on its side or superstructures.

Hull or main structure (400): it is a structure that comprises one or several floats or watertight flotation elements (500) that form a rigid and resistant assembly, in which at least one of them is partially submerged.

Floating platform (100): it is a hull or main structure (400) of any shape or configuration, which additionally includes other elements or structures (radii (600), projecting structural arms (12), flotation elements (500),... .), dedicated to any function (accommodation, industrial or recreational facilities, support for windmills, etc.), equipped with the anchoring system proposed here.

External agents: they are the wind, sea currents, waves, internal load movements or any element external to the floating platform (100) that tries to move it away from its projected position or tries to make it have pitching or rolling movements.

Tension of the anchoring cable or line (200): tensile force to which the anchoring cable or line (200) is subjected (due to its flexible nature, the cable cannot be subjected to compression forces).

Central counterweight (1): it is a totally submerged hull, with an average density greater than 1.2 kg/dm ³ , which keeps the anchoring lines (200) that connect to it taut. In simple installations there is only one counterweight (1) located in the central axis (300) of the floating platform (100), but there may be several counterweights (1) or be located below other points of the floating platform (100).

Anchoring block or bottom weight (4): It is a (large) weight resting on the seabed (5), to which the anchoring cables or lines (200) of the anchoring system are attached. In other conventional installations, it is equivalent to the anchor, to the 'dead' that they keep in their position buoys or other marine elements or any other type of anchoring by means of piles.

Anchor cable or anchor line (200): is a cable, chain or mooring of any type that keeps the floating platform (100) attached to the bottom weight (4), preventing the floating platform (100) from being dragged by external agents. Each funding line (200) is made up of the following elements:

- Bottom section (8) is the part of the anchoring line (200) that joins the bottom weight (4) with the first rotating fixing means (3) (or external pulley) of the anchoring line (200) . In most applications, when they are in the design condition, the bottom section (8) is completely vertical, although in special cases it may be slightly divergent. In some cases it can be in one piece down to the seabed (5); in other cases, the bottom section (8) is split or divided into a first portion (lower portion) and a second portion (upper portion), and both portions (upper and lower) are joined together by a buoy (9). intermediate.

- Intermediate section (7): it is the part of the anchoring line (200) that joins the outer pulley (the first rotating fixing means (3)) with the inner pulley or pulleys (the second rotating fixing means (2c) and, possibly, the third rotary fixing means (2d)) that hold the cable; it can be horizontal or it can have a slight slope (if the pulleys are not at the same height).

More specifically, as will be seen later, the anchor line (200) comprises a crossed subline (200c) and a direct subline (200d). The intermediate section (7) is the part of the crossed subline (200c) of the anchoring line (200) that joins the first rotary fixing means (3) (or external pulley) with the second rotary fixing means (2c) (or internal pulley).

On the other hand, if there is a third rotating fixing means (2d) (or internal pulley), the part of the subline is also called the intermediate section (7). direct line (200d) of the anchoring line (200) that joins the first rotary fixing means (3) with the third rotary fixing means (2d).

Central section (6): is the part of the anchoring line (200) that joins the inner pulley (or each one of the inner pulleys) with the central counterweight (1).

- Intermediate buoy (9): it is an optional element, which can be inserted in the bottom section (8) of each anchoring line (200). The buoy (9) is connected to the seabed (5) by means of a cable (a first portion of the bottom section (8) of the anchoring line (200)). The first portion of the bottom section (8) can comprise one or more cables or chains in parallel. The advantage of using this buoy (9) is that it can be pre-installed when the ground is conditioned and the bottom weights (4) are placed, leveling it at the correct height so that later, when installing the floating platform (100), there is only to connect the anchoring lines (200) (the second portion of the bottom section (8) of each anchoring line (200)) to the buoy (9), which are prepared with their correct length, significantly speeding up the installation process of the floating platform (100).

- Central axis (300) of the anchoring system: a vertical axis that passes through the center of gravity of the counterweight (1) in its rest (or project) position. Preferably, this central axis (300) constitutes a central axis (300) of symmetry of the floating platform (100).

- Anchoring subline (generic): it is the basic unit of the anchoring system, it is made up of the following elements: o An anchoring weight (or bottom weight (4)) resting on the seabed (5) (which can be shared by various funding sublines); A first rotating fixing means (3) (or external or external pulley): fixed to the floating platform (100) in a fixed or partially flexible way (or rotating/tilting), close to the vertical of the bottom weight (4); One or two inner or internal pulleys (2) (a second rotating fixing means (2c) and, optionally, a third rotating fixing means (2d)): holds the floating platform (100) in a fixed or partially flexible way (or swivel/tilt), at some point in the structure of the floating platform (100). Despite their name, they are located some distance from the central axis (300) of the floating platform (100); The corresponding part of the central counterweight (1) (several cables must necessarily share the same counterweight (1)); A cable that joins all these elements, made up of the previously defined sections (central section (6), intermediate section (7) and bottom section (8)); Optionally there can be an intermediate buoy (9) inserted in the bottom section (8); Optionally, there may be some intermediate pulleys (rotary guide means (11)), which serve as support for the intermediate section (7) of the cable of the sub-mooring lines, or which help guide the cable along the most appropriate path.

Some of the pulleys described above can be self-orienting, so that they adapt to the variations in direction suffered by the central section (6) and the bottom section (8), due to the movements of the floating platform (100). - Outgoing structural arms (12): on floating platforms (100) in which the external pulleys (first rotating fixing means (3)) are further away from the central counterweight (1) than the perimeter of the main structure (400) of the floating platform (100), these protruding structural arms (12) are bracket-shaped extensions of the hull (or any other type of structure), which serve to hold the external pulleys (first rotating fixing means (3)), internal pulleys (2) (second rotary fixing means (2c) and, optionally, third rotary fixing means (2d)), or intermediate pulleys (rotary guide means (11)).

- Crossed subline (200c): It is a anchoring subline in which the inner pulley (second rotating fixing means (2c)) is beyond the central axis (300) of the floating platform (100), almost diametrically opposite to the corresponding outer pulley.

- Direct subline (200d): It is a anchoring subline in which the inner pulley (third rotating fixing means (2d)) is very close to the outer pulley (first rotating fixing means (3)). However, it is also possible that the direct subline (200d) lacks an internal pulley (third rotary fixing means (2d)); in this case, the cable is directed from the outer pulley (first rotary fixing means (3)) directly to the counterweight (1).

The complete anchoring line (200) is the set of two anchoring sublines (a direct subline (200d) and another crossed subline (200c)), which share the same bottom weight (4), a part of the bottom section ( 8) of the anchoring cables and the corresponding part of the central counterweight (1). Its external or external pulleys (first rotating fixing means (3)) are very close to each other, they are generally parallel with the same axis of rotation. On platforms that use projecting structural arms (12), these outer pulleys hang from the end of the projecting structural arm (12) itself. Instead of two outer pulleys, it can comprise a single outer pulley with at least two sheaves (one sheave for the direct subline (200d) and another sheave for the crossed subline (200c)). - Blocking line: it is a generic anchoring line (200) (as previously described), in charge of maintaining the verticality of the floating platform (100). Its elements are large, as they can be subjected to great tensions in their anchoring cable, especially in the floating platforms (100) that serve as support for wind turbines.

Damping line: it is a mooring line (200) with some variations: o One of its pulleys (indistinctly the inner or the outer) is connected to an electric generator through a multiplier gear (or to a hydraulic motor that moves a generator) , which allows capturing the energy of the movement of the floating platform (100); o The central section (6) of the anchoring cable has a more elastic part (which works like a spring), so that it absorbs the variations in length with respect to the blocking lines; o The voltage of the cable is limited by the electrical characteristics of the generator and is much lower than the voltage of the blocking lines; o The size of its elements (cable diameter, pulleys, supports...) is also smaller, due to the lower stresses to which its cable is subjected. In fact, they may be made of other materials that are less resistant than the blocking lines.

Parallel anchoring line (200): It is an anchoring line (200) in which its bottom section (8) is vertical (in its rest position), as shown in Figures 1 to 6; all the bottom sections (8) remain parallel even if the platform moves. - Divergent anchoring line (200): It is an anchoring line (200) in which its bottom section (8) (the one that is attached to the seabed (5)) is not vertical, but is inclined outwards (forming an angle (A) with the vertical), that is, the lower end of the anchoring line (200) is further from the central counterweight (1) than the outer pulley (Figure 7).

- Group of mooring lines (200): It is the set of several mooring lines (200) (blocking or damping) that share a common central counterweight (1). The resulting layout is necessarily radial, although each branch can have a different size (distance between the center line axis and the outer pulley). All the internal pulleys of the group must be at the same distance from the central axis (300) of the floating platform (100) (which coincides with the vertical of the counterweight (1)).

Floating platforms (100) with very elongated geometries can have several groups of anchoring lines (200) installed acting on the same counterweight (1) (the central lines of each group of anchoring lines (200) are attached to different points on the counterweight (1), which is also elongated).

In especially large floating platforms (100), there may be several groups of anchoring lines (200), each group with its corresponding counterweight (1).

In all the preferred embodiments shown in the Figures, the anchoring system has only one group of anchoring lines (and therefore a single counterweight (1)).

- SLP Platform (Soft Leg Platform): it is a floating platform (100) in which the anchoring system proposed in this patent application has been installed. In each complete mooring line (200) there are two sub-mooring lines (200d, 200c), whose inner pulleys (second rotating fixing means (2c) and third rotating fixing means (2d)) are at the same distance from the central axis. (300) of the floating platform (100). Each anchoring line (200) is made up of a direct subline (200d) and a crossed subline (200c), whose inner pulleys (second rotary fixing means (2c) and third rotary fixing means (2d)) are located symmetrically with respect to the vertical central axis (300) that passes through the central counterweight (1), as can be seen in Figures 8 and 9.

Central Well (optional, not represented in the Figures): it is a hole that vertically crosses the entire floating platform (100), just below the interior pulleys, for the passage of the pendulum (cables of the central section (6) and counterweight (1 )); If the Inner pulleys are too far apart from the vertical of the central counterweight (1), the central well is unnecessary.

Most of the elements that make up the proposed system have been described above. There are other optional elements that can help the correct functioning of the main elements and other elements that can help the actual implementation on a given platform.

The simplest configuration is made up of four blocking anchoring lines (200), each of which is made up of two sublines (one direct (200d) and the other crossed (200c)), each of which includes:

A bottom weight (4) resting on the seabed (5);

- Two pulleys or rotary fixing means (2, 3): an outer pulley (or first rotary fixing means (3)) and another inner pulley (second rotary fixing means (2c)); optionally, there can be a second inner pulley (or third rotary fixing means (2d)) for the direct subline (200d) of each anchoring line (200);

A central counterweight (1), common to the four anchoring lines (200); - A cable (in each subline) that joins the bottom weight (4) with the central counterweight (1), passing through the outer pulley (first rotating fixing means (3)) and the inner pulley (second rotating fixing means (2c) or third rotating fixing means (2d)), defining three sections (6, 7, 8) in those sublines (200c, 200d) that have internal pulleys: o The central section (6) of the anchoring cable, which joins the inner pulley (second rotary fixing means (2c) or third rotary fixing means (2d)) with the central counterweight (1). Its length depends on the vertical position of the central counterweight (1). Optionally, the part of the cable closest to the central counterweight (1) has been called the adjustment section of the anchoring cable and can be used to adjust the total length of the cable to the irregularities of the sea bed or bottom (5) at the point where it is attached. go to place the floating platform (100); o The intermediate section (7) of the anchoring cable, which joins the inner pulley (second rotating fixing means (2c) or third rotating fixing means (2d)) with the outer pulley (first rotating fixing means (3)) , by its nature it has a constant length; o A bottom section (8) of the anchoring cable, which joins the outer pulley (first rotary fixing means (3)) with the bottom weight (4). Its length depends on the geographical position of the platform (ie the depth of the seabed (5)). Optionally, this bottom section (8) can be divided into two parts or portions that are attached to an intermediate buoy (9). In this way, cable installation and maintenance operations are facilitated.

Since all three spans (6, 7, 8) are part of the same cable, the sum of their lengths is constant. The mission of these elements is to prevent the rolling and pitching movement of the floating platform (100), allowing it to be moved horizontally or vertically. If the floating platform (100) moves vertically a height V, the counterweight moves vertically a height 2V, but the forces on the floating platform (100) are hardly changed.

If the floating platform (100) moves horizontally by an amount H, the anchoring lines (200) generate an opposing horizontal force that tends to return the floating platform (100) to its original position. The vertical forces on the floating platform (100) hardly vary. The counterweight (1) moves slightly up.

If a bending moment is applied that attempts to make the floating platform (100) rotate in the pitching direction, the tensions in the mooring lines cables (200) vary to compensate and prevent rotation; If this bending moment increases sufficiently, one of the anchoring lines (200) will loosen and the floating platform (100) is only supported by the other anchoring lines (200). In general, the hull or central structure (400) of the floating platform (100) will begin to submerge slightly.

When all the anchoring lines (200) except one have been released, the floating platform (100) will possibly begin to capsize. This overturning will be reversible or irreversible depending on the particular geometry of the entire set.

The theoretical foundation of the invention is based on a geometric construction, as can be seen in Figure 2.

Each anchor cable can be considered almost inextensible. If we suppose it to be made up of three sections with lengths: T6 (length of the central section), T7 (length of the intermediate section) and T8 (length of the background section), the sum of the lengths (T6, T7, T8) of the three sections (6, 7, 8) is constant: T6 + T7 + T8 = constant.

Since the intermediate section (7) does not vary in length, it is also true that: T6 + T8 = constant. The floating platform (100) has two anchoring lines (200) (if the movement is assumed to be flat, if it is considered three-dimensional there would be at least four anchoring lines (200), crossed two by two, but the result is the same) . If we compare the lengths of the sections in two different positions of the platform:

Project condition: it has two lines (P and Q), each one with its three aforementioned sections;

- Any other position: the lines become (R and S).

Since each line (P, Q, R, S) maintains its length:

T6(P) + T8(P) = T6(R) + T8(R) and T6(Q) + T8(Q) = T6(S) + T8(S)

Since T6(P) = T6(Q) and T6(R) = T6(S) (represent the same measure).

If we start from two symmetrical lines, that is, T8(P) = T8(Q), then T8(R) = T8(S)

In other words, the two outer pulleys (first rotating fixing means (3)) and the two bottom weights (4) form an "articulated" quadrilateral in which their opposite sides are equal and therefore the upper side is always parallel to the upper side. bottom, regardless of the position of the center of the floating platform (100).

To block the rotation of the floating platform (100) in one plane, two anchoring lines (200) are sufficient, as seen in Figures 1 or 2. For example, if you want to avoid the pitch angle, you need two anchoring lines (200) in a longitudinal plane, with an outer pulley at the bow and an outer pulley at the stern, with the two inner pulleys between them (it is not necessary that the intermediate sections of the anchoring cable are equal). if you want To avoid the angle of roll, the two anchoring lines (200) must be in a transverse plane to the waves.

Figures 4 and 5 show a diagram of a complete anchoring line (200) made up of a direct subline (200d) and a crossed subline (200c), which represent the positions of the floating platform (100) in its condition. project (Figure 4) and in any other position (Figure 5).

The two inner pulleys (2d: direct and 2c: crossed) are at the same distance from the central axis (300) of the floating platform (100) (actually the axes of the pulleys are at different distances, but so that the sections (7) seem to come from symmetrical points: the point of contact of the cable with the pulley). In the design condition (Figure 4), the lengths of the two sublines (200c, 200d) are different, but they are such that the central sections (6d, 6d) are equal, so that the central counterweight (1) is located in correspondence with the central axis (300) of the floating platform (100).

When the floating platform (100) (Figure 5) is moved, the bottom sections (8d and 8c) change in length, but remain equal to each other. The intermediate sections (7d and 7c) do not vary in length (the pulleys move rigidly with the platform). Since the total length of each subline (200c, 200d) does not vary, the central sections (6d and 6c) also vary in length, but remain equal to each other, that is, the central counterweight (1) moves vertically, but is It is kept located in correspondence with the central axis (300) of the floating platform (100). In this way, the pendulum movement that the counterweight (1) could have in the original version of the anchoring system is totally eliminated.

When two complete mooring lines (200) are combined (each with a direct (200d) and crossed (200c) subline), applying the same reasoning as when the lines are central (in state-of-the-art platforms with a central well through which the central lines pass), the bottom sections (8) of each complete anchoring line (200) remain equal to each other, regardless of the position of the floating platform (100). In this sense, the anchoring system (with direct (200d) and crossed (200c) sublines) behaves as if all the sublines were central. The operating scheme of the system with direct (200d) and crossed (200c) sublines can be seen in Figure 3. If it had only central sublines it would be the same scheme, with the angle (B) between the central sections (6) null (ie they would be vertical).

When external agents (winds, waves or sea currents) act on the floating platform (100), they generate a bending moment (Mf) and a force (Fx) that pushes the floating platform (100) to the position seen in the figure.

On the other hand, the central counterweight (1) has a net weight (dry weight minus hydrostatic thrust) that tensions the two anchoring line cables (200) generating two forces, windward (F1) and leeward (F2). . Neglecting the inertial forces due to the movements of the floating platform (100) and the counterweight (1), the forces in the direct and crossed cables on each side are equal:

F1c = F1d = F1/2, and F2c = F2d = F2/2

By the balance of forces in the counterweight it is fulfilled that:

(F1 + F2) x Cosine (B) = P

These forces are transmitted through the cable to the bottom weights (4).

For the floating platform (100) to be in equilibrium, the two forces F1 and F2 applied in the bottom sections (8) must fully compensate the bending moment of the external agents (Mf).

(F1-F2) x External pulley distance x cosine (a) = Mf Since the cables do not work in compression, as long as F2 is positive, the floating platform (100) will maintain horizontality, then it will begin to tilt to the leeward.

On the other hand, the equilibrium of the horizontal forces imposes that:

FH = F1 x sine (a) + F2 x sine (a) = P x sine (a) / cosine (b)= Fx

According to a variant of the anchoring system where the anchoring lines (200) are divergent, the pitch angle imposed by external forces acting on the floating platform (100) can be corrected. The elasticity of the mooring lines (200) means that when the floating platform (100) is subjected to external forces, the windward cables lengthen and the leeward cables shrink. As a result of these deformations, the floating platform (100) acquires a small pitch angle to leeward.

The variant indicated consists of giving an angle to the bottom sections (8) of the anchoring lines (200), separating the anchoring points from the vertical of the external pulleys (first rotary fixing means (3)) outwards), as can be seen in Figure 7.

When the floating platform (100) is moved horizontally by the wind, the deck of the floating platform (100) is not kept horizontal, but is turned to the windward. This turning angle is geometrically related to the angle of the bottom sections (8) and to the depth of the seabed (5), being approximately proportional to the magnitude of the horizontal movement. By adjusting the angle of the bottom sections (8) of the anchor lines (200), it is possible to exactly cancel the pitch of the floating platform (100) due to the elasticity of the anchor lines (200), whatever the applied horizontal force (until one of the lines is relaxed).

Three alternatives are proposed below, by way of example, to fasten the cables of the bottom section (8) on the sea bed or bottom (5). All of them can include some intermediate buoys (9) in the bottom sections (8) (located at a depth similar to that of the counterweight (1), in its project position) attached by cables or chains to the anchorage on the seabed (5).

In this way, the final installation is very simple, since it is enough to fasten the cables in the buoys (9) and the floating platform (100) is fully operational.

- An anchoring ring can be used, for example by joining all the bottom weights (4) by means of a rigid structure, which includes fixing points for the cables in the appropriate places. This structure includes several ballast tanks, which are initially empty so that the whole has a slightly positive buoyancy. This structure is moved to the wind farm and sunk in the place where you want to install the floating platform (100). This operation does not require great precision, since it is certain that the anchoring points will be correctly placed, whatever the position in which the ring remains on the seabed (5). When the floating platform (100) is placed in its place or installation location, it is enough to hold the cables in the anchors and the floating platform (100) is operational;

- Piles driven into the seabed can be used (5). This system is copied from the foundations of the TLP-type platforms. The seabed (5) is prepared and piles are driven in, which include the anchoring points for the anchoring lines (200). The fundamental difference with the TLP system is that the traction stresses that must be supported with the anchoring system of the present invention are much lower than in a TLP platform, in fact, for an equal installed power, the stresses are of the order of one fifth or less. This makes anchoring preparation much cheaper and easier.

- Bottom weights (4) previously located on the seabed (5) can be used. Due to the low tensions of the cables, individual bottom weights (4) can be used precisely located on the seabed (5), on a pre-prepared esplanade. It is an intermediate solution between the ring anchoring (which is a very large structure but easy to place) and the use of piles (you have to slightly prepare the ground and place the bottom weights (4) with precision). Comparison of the anchoring system of the present invention with the TLP platforms (Tension Leg Platform):

Apparently, the floating platforms (100) with the TLP-type anchoring system serve the same purpose as a floating platform (100) with the anchoring system of the present invention. Its objective is to nullify the pitch/roll movement of the floating platform (100). However, the operating principle of both is radically different and so are their kinematic and dynamic characteristics, as can be seen in the following table:

The Figures of this patent application are described and commented below.

In all the Figures, the depth at which the seabed is found (5) has been reduced, so that the images are more proportionate and easier to interpret. If the seabed were so close, it would not be worthwhile for them to be floating platforms (100), since it would be better if they were directly resting on the seabed (5). In real projects, the counterweight (1) would also be proportionally deeper than what is shown in the Figures.

Figure 1 shows a basic diagram of the blocking anchoring lines (200) (those that prevent the rotating movement of the floating platform (100)). An installation of this type consists of a floating platform (100) floating in the sea, equipped with two or more anchoring lines (200) (the minimum is two anchoring lines (200) when you only want to cancel the turning movement in one direction, such as pitching; the minimum is four anchoring lines (200) when you want to simultaneously cancel pitch and roll), each of which is made up of at least two sublines (200d, 200c). , each of which consists of: one (or two) inner pulley(s) (second rotary fixing means (2c) and third rotary fixing means (2d)) and an outer pulley (first rotary fixing means ( 3)), which support a cable or anchoring line (200) made up of three sections, a bottom section (8) that reaches a bottom weight (4) resting on the seabed (5), another central section ( 6) subject to the central counterweight (1) and an intermediate section (7) that joins the other two sections (8, 6). The central counterweight (1) is shared by all the anchoring lines (200). The bottom section (8) can be divided into two portions, which are attached to an intermediate buoy (9); in this case, the lower portion (first portion) of this bottom section (8) is common to all the sublines that hang from the same protruding structural arm (12). In Figure 1, two complete mooring lines (200) have been simultaneously represented, one by a continuous line (the one on the right) and the other (the one on the left) by a broken line.

Figure 2 shows a diagram of the geometric principle that regulates the lengths of each section (6, 7, 8) of the anchoring lines (200) and justifies that the floating platform (100) always moves parallel to the initial position of the same. The scheme corresponds to central anchoring sublines (where the floating platform comprises a central well) of a state-of-the-art anchoring system (as defined in document ES 2629867 A2). This Figure is provided to serve as a basis and facilitate understanding of the operation of the anchoring system object of the present invention.

Figure 3 shows a diagram of the dynamic principle, with the forces that act on the anchoring lines (200) when the floating platform (100) is subjected to a force (Fx) and a bending moment (Mf) caused by external agents. (wind, waves or marine currents). The sum of the tensions in all the mooring lines (200) is always constant (equal to the apparent weight of the central counterweight (1), divided by the cosine of the angle (8) between the central section (6) and the central axis ( 300)), the difference between the tensions of the anchoring lines (200) is proportional to the applied bending moment and the horizontal force (FH) that the floating platform (100) is capable of supporting is proportional to the sine of the angle (a) between the bottom sections (8) of the anchoring lines (200) and the vertical direction. If the cables of the bottom sections (8) of the leeward anchoring line (200) loosen, the platform loses its horizontality (pitch or roll movements appear).

Figure 4 and Figure 5 show a basic diagram of the anchoring system, similar to that of Figure 1, in which the intermediate buoys (9) have been removed, so that the bottom sections (8d, 8c ) of the direct subline (200d) and the crossed subline (200c) reach the bottom weight (4) on the seabed (5). Figure 4 represents the floating platform (100) in its rest position and Figure 5 corresponds to the floating platform (100) when it has changed its position (horizontal and vertical) due to the effect of the wind and waves.

Figure 6 shows an operating diagram of the anchoring system with parallel anchoring lines (200), in which the bottom sections (8) are vertical in their rest position (dashed lines). When the floating platform (100) moves (solid line), the cover of the floating platform (100) is always kept horizontal.

Figure 7 shows an operating scheme of the anchoring system with divergent anchoring lines (200), in which the bottom sections (8) do not descend vertically to the seabed (5), but rather their layout forms an angle ( A) with the vertical. When the floating platform (100) moves horizontally, tilts to windward. In a first approximation it is as if it rotated around the point of intersection of the two bottom sections (8). If the floating platform (100) is a support for marine wind turbines, with a tower (13) and a nacelle (14) of a wind turbine, it can be achieved that the axial component of the weight of the nacelle (14) (due to the inclination of the tower (13)) exactly compensates for the thrust of the wind on the rotor blades, so that the bending moment in the entire tower (13) of the wind turbine is canceled (and therefore the bending moments are also canceled). that transmits the tower (13) to the floating platform (100)).

Figure 8 and Figure 9 show an example of the mooring system comprising four mooring lines (200). This version of the anchoring system is applied to floating platforms (100) with an even number of protruding structural arms (12). In this scheme, the inner pulleys (third rotary fixing means (2d)) of the direct subline (200d) have been suppressed, so that the outer pulley (first rotary fixing means (3)) also functions as the inner pulley and of course the intermediate section (7) of the direct subline (200d) has also been deleted. Apparently, the inner pulley (second rotary fixing means (2c)) of the crossed subline (200c) seems to be next to the outer pulley (first rotary fixing means (3)), but it is an optical effect, said pulley corresponds to the crossed subline (200c) of another protruding structural arm (12) (the opposite arm). In the Figures you can also see the intermediate pulleys (rotary guide means (11)) of the crossed subline (200c) that divert the intermediate sections (7) of the crossed subline (200c) so that they do not intersect with the same sections of the perpendicular lines (at the "apparent intersection point", said sections pass at different heights).

Figure 10 and Figure 12 correspond to the installation phases of a stable floating platform (100) in the ballast condition (the Figures show the floating platform (100) with four protruding structural arms (12), although is valid for any platform of this type)). More concretely:

- Figure 10 shows the bottom anchors prepared to receive the floating platform (100), with the intermediate buoys (9), the lower portions (first portions) of the bottom sections (8) of the anchoring lines. (200) and background weights (4). The floating platform (100) is in its condition of ballast, with the flotation elements (500) comprising a submerged area (15) another emerging area (16) above a waterline (21), and where the central counterweight (1) is located centrally below the floating platform (100). The anchoring lines (200) are connected to the counterweight (1), but not connected to the buoys (9).

Figure 11 shows the upper portions (second portions) of the bottom sections (8) of the anchoring lines (200) already connected to the buoys (9) and the counterweight (1) has been partially flooded, tightening the cables and sinking towards its projected position. The floating platform (100) is somewhat deeper than in the ballast condition, but has not yet reached the operating condition (where the waterline (21) is located in correspondence with the operating draft (22)). . The spokes (600) of the floating platform (100) are completely out of the water and the floating platform (100) retains all its stability.

Figure 12 shows the fully installed floating platform, with the floodable counterweight chambers (1) flooded and the cables working with their nominal tension. The floating platform (100) is already at its operating draft (22), ready to go into service.

Figure 13, Figure 14 and Figure 15 correspond to a first embodiment of the invention. These Figures show a floating platform (100) that serves as a support for an offshore wind turbine, which is stable in its ballast condition, with four mooring lines (200). The floating platform (100) has two main loading conditions: the ballast condition, where the waterline (21) passes through an intermediate point of the flotation elements (500) (which divides them into two parts: a zone submerged (15) and another emerging zone (16) or emerged, which is only submerged in the operating condition) and the operating condition, where the waterline (21) is already in correspondence with the operating draft ( 22) and passes through an intermediate point of the radios (600) (distinguishing a submerged radio zone in operating condition (17) and another zone never submerged (18)). The spokes (600) are attached to the hull in a shaft that, in this case, comprises a structural ring (19) that has eight rectangular faces. (where the four spokes (600) and the four protruding structural arms (12) meet) and another eight trapezoidal faces joining the rectangular faces. Four protruding structural arms (12) support the outer pulleys (first rotary fixing means (3)) and the inner pulleys (only the second rotary fixing means (2c) have been shown and not the third rotary fixing means (2d)) of the anchoring lines (200). On the structural ring (19) there is a small frustoconical superstructure (20) for the electronic equipment of the floating platform (100) and on which the tower (13) of the wind turbine rests.

Figures 13, 14 and 15 represent three views of the floating platform (100), with direct (200d) and crossed (200c) sublines. Figure 13 shows a (lateral) profile view of the assembly, aligned with the spokes (600) or legs of the floating platform (100) that hold the submerged flotation elements (500). Figure 15 shows a front view of the assembly, aligned with the protruding structural arms (12) that support the external pulleys (rotated 45 ^s with respect to the spokes (600), arranged in the bisectors between the spokes (600)). Figure 15 shows a first arm (12a) and a second arm (12b) belonging to a pair of protruding structural arms (12) located in the same plane. Figure 14 shows a 3D view of the assembly.

The protruding structural arms (12) comprise a first end (121) attached to the hull or main structure (400) of the floating platform (100) and a second end (122) projecting outward from the floating platform (100).

Figure 16, Figure 17 and Figure 18 correspond to a second embodiment of the invention. These Figures show a floating platform (100) that serves as a support for an offshore wind turbine, which is not stable in its ballast condition, with four anchoring lines (200) with direct sublines (200d) and crossed sublines (200c), in which have included an intermediate pulley (rotary guide means (11)) for diversion in the intermediate section (7) of the mooring lines (200). In this case, the pulley is located horizontally and diverts the cables outwards, to avoid the superstructure (20) that supports the tower (13) of the wind turbine. The hull or main structure (400) is the simplest possible, a simple cylinder with a vertical axis, divided (conceptually) into three parts: a submerged area (15), which is always submerged (even in ballast condition), another emerging zone (16) or emerged, which is only submerged in the operating condition) (these two parts together constitute the 'hull' of the floating platform (100)). It also has a never-submerged zone (18), that is, a part of the hull or main structure (400) that is out of the water in any loading condition (analogous to the top of the spokes (600) of the floating platform ( 100) in the first embodiment). Like the floating platform (100) of the first embodiment shown in Figures 13 to 15, also in the second embodiment the floating platform (100) incorporates four protruding structural arms (12) and a small superstructure (20) on the hull that supports the tower (13) of the wind turbine.

Figures 16, 17 and 18 represent three views of the floating platform (100) with four protruding structural arms (12), respectively in profile, in 3D and frontal perspective (aligned with the protruding structural arms (12) of the floating platform ( 100)).

Figure 19, Figure 20 and Figure 21 correspond to a third embodiment of the invention, where a floating platform (100) is shown that serves as a support for a marine wind turbine, which is stable in the ballast condition. . According to this third embodiment, the hull or main structure (400) of the floating platform has an annular geometry, forming a flotation ring (700). It has a central well, although it is not used as such (it is not used for the passage of counterweight cables). Four protruding structural arms (12) arise from the submerged hull or main structure (400). Figure 19 is a front view of the assembly (aligned with the pulleys and protruding structural arms (12)). Figure 21 is a side view, rotated 45 ^e (oriented along the bisector of the arms). Figure 20 is a 3D view of the assembly.

Although the proposed anchoring system is valid for any floating platform (100) (intended to support any type of structure), the present invention is especially indicated for two specific applications, as a support for offshore wind turbines and as a platform for maritime entertainment. With regard to the object of the proposed patent (the anchoring system), the main difference between the two applications is the covered area of the floating platform (100), which means that in the platforms designed to support wind turbines, the outer pulleys hang from projecting structural arms (12) arranged radially, which protrude quite far from the deck of the floating platform (100), and in platforms designed for marine leisure, it causes the outer pulleys to hang from very short arms that protrude from the main tweendeck of the platform.

The anchoring system, according to the first embodiment of the present invention, comprises the following elements:

- Four anchoring lines (200), each of which is formed by two anchoring sublines (200c, 200d), each of the sublines (200d, 200c) consists of an anchoring cable hung from an external pulley (first rotating fixing means (3)) and another inner pulley (2c, 2d), which in turn hang from a protruding structural arm (12) that serves as support for the mooring lines (200). The bottom section (8) of the anchoring cable of all the sublines (of the same anchoring line/arm), is subject to a bottom weight (4) directly or through an intermediate buoy (9) and a section common fund (first portion or lower portion of the fund section (8)). The central section (6) of all the mooring lines (200) is subject to a central counterweight (1) that is common to all the mooring lines (200).

- Floating platform (100): its hull or main structure (400) is attached to four cylindrical floats or flotation elements (500) with a vertical axis arranged at the vertices of a square, sufficiently separated from each other so that the counterweight (1) center will fit in the center of the platform with the necessary clearances. The flotation elements (500) are attached to the hull or main structure (400) of the floating platform (100) by means of four 'legs' or inclined spokes (600) that coincide in a reinforced structural ring (19) located below the superstructure (20) of the floating platform (100), well above its operating draft (22). In this structural ring (19) the four protruding structural arms (12) that hold the mooring line pulleys (200) (the outer pulleys (first rotary fixing means (3)) and the inner pulleys ( second rotary fastening means (2c) and third rotary fastening means (2d) if any). On this reinforced structural ring (19) there is a superstructure (20) on which the wind turbine tower (13) rests. the ballast condition, the line The flotation platform (21) is located approximately halfway up the flotation elements (500) and the floating platform (100) is stable by itself. In the operating condition, the operating draft (22) is located halfway up the spokes (600) and the flotation elements (500) are totally submerged.

- Central counterweight (1): It is a cylindrical tank with a vertical axis, ballasted, but with such a volume that completely empty it has a positive buoyancy of the order of 10% of its volume. Internally it is divided into several ballast tanks or floodable chambers that can be filled or emptied independently. With one of its chambers flooded, it has slightly negative buoyancy. On its roof, there are four pairs of anchors where the ends of the central sections (6) of all the sublines (200c, 200d) of the anchoring lines (200) are attached.

- Wind turbine: composed of a tower (13) of the wind turbine that rests on the main structure (400) of the floating platform (100) (on the superstructure (20) that is on the reinforced structural ring (19)) where it is they hold the protruding structural arms (12) and the upper part of the spokes (600). The tower (13) holds the gondola (14), where the wind turbine itself is located. It is a commercial component, so it is not described in more detail.

The submerged flotation elements (500) are accessible (for maintenance operations) through stairs located inside the spokes (500) of the floating platform (100). Said legs or spokes (600) are accessed through watertight doors located in the corresponding rectangular faces of the reinforced structural ring (19). This floating platform (100) has two modes of operation: o The transfer (or ballast) condition, in which all its floodable chambers are empty, all the anchoring lines (200) collected and it floats freely with no other ties than the cable that connects it to the tugboat. In this condition, the floating platform (100) is stable by itself. o The operating (or project) condition, in which one of its ballast tanks or floodable chambers is partially filled to ensure that the platform floats at its operating (22) or project draft. The floating platform (100) is connected to the central counterweight (1) through the central sections (6) of all the anchoring lines (200) and to the seabed (5) through the bottom sections (8) of the anchoring lines. (200). In this condition, the floating platform (100) has no stability on its own and depends exclusively on the stability provided by the anchoring lines (200).

Figures 13 to 15 show three views of this first embodiment (in which its main elements have been identified), with the proposed anchoring system.

In the mooring system, according to the second embodiment of the present invention, unlike the first embodiment, in the ballast condition, the floating platform (100) is not stable, so it is mandatory to use a anchoring ring, whose function is to provide stability to the platform during the entire transport from the shipyard to the wind farm.

The main structure (400) of the floating platform (100) comprises a cylinder with a vertical axis, conceptually divided into three parts or zones: a submerged zone (15) in any load condition in the deepest part of the cylinder; an emergent zone (16) or emerged (intermediate zone) that is out of the water in the ballast condition and submerged in the operating condition and another zone never submerged (18) (upper part), which is always above the line of flotation (21). In addition, the floating platform (100) comprises four projecting structural arms (12) arranged radially (and of course the same number of mooring lines (200)). The main structure (400) includes a small superstructure (20) for the electrical equipment of the wind turbine and which also serves as support for the tower (13) of the wind turbine. In this second embodiment, the floating platform (100) is the simplest and most economical (among the three proposed embodiments), but it has a different hydrodynamic behavior than the other two embodiments, since having much more floating area, it tends to follow the movement of the waves, so its vertical movements are greater than those of the other embodiments; On the other hand, it is capable of capturing more energy from the wave movement and the wave profile remains closer to its design waterline (operational draft (22)), so it needs less freeboard than the other platforms.

Figures 16 to 18 show three views of this second embodiment (in which its main elements have been identified), with the proposed mooring system with an intermediate pulley (rotary guide means (11)) horizontal in each intermediate section (7) of the anchoring cable, which serves to separate the cable from the superstructure (20).

The anchoring system, according to the third embodiment of the present invention, is stable in the ballast condition and comprises the following characteristics:

- It has four outgoing structural arms (12) arranged radially, with four anchoring lines (200);

The reinforced structural ring (19) is located higher than in the other embodiments and the superstructure (20) is smaller (lower) than in the other embodiments and serves as a connecting element to the four legs or spokes. (600), which are somewhat longer than in the other embodiments.

The main structure (400) has an annular geometry, constituting a flotation ring (700) that includes at least one floodable chamber.

Figures 19 to 21 show three views of this third embodiment (in which its main elements have been identified). The direct sublines (200d) do not have interior pulleys (third rotary fixing means (2d)), since the outer pulley (first rotary fixing means (3)) performs both functions (interior and exterior, to save space) and the crossed sublines (200c) use vertical intermediate pulleys (rotating guide means (11)) to redirect the cable.

As can be seen in the Figures, the reinforced structural ring (19) is higher so that the cables of the intermediate section (7) of the crossed sublines (200c) pass under the superstructure (20), between the legs or radios. (600) of the floating platform (100). If intermediate pulleys were included in this section, which divert the cable downwards, the reinforced structural ring (19) could occupy a lower position.

As already described, in the anchoring system of the present invention, in each of the anchoring lines (200) there is a direct subline (200d) and a crossed subline (200c), where the inner pulley of the crossed subline (200c) is located diametrically opposite the inner pulley of the direct subline (200d). This arrangement requires that there be an even number of mooring lines (200) (and protruding structural arms (12)), and also makes the inner pulley of the direct subline (200d) of a first mooring line (200) in a protruding structural arm (12) it is next to the inner pulley of the crossed subline (200c) of a second anchoring line (200) diametrically opposite, although on different sides of the protruding structural arm (12).

On floating platforms (100) for wind turbines that use protruding structural arms (12) to hold the pulleys, on each head there are two outer pulleys, a direct inner pulley (which can be omitted) and the inner pulley that crosses the anchoring line diametrically opposite.

In Figures 8 and 9 you can see two projections of this anchoring system with four protruding structural arms (12); however, the floating platform (100) could have another even number of protruding structural arms (12).

In this type of anchoring, the intermediate sections (7) of the crossed sublines (200c) of the anchoring lines (200) can pass to the other side of the floating platform (100) very close to its central axis (300) of symmetry. ; For this reason, in the hull or in the superstructure, passage holes can be made for these cables. An alternative used in the examples previously presented, is to use intermediate pulleys (rotating guide means (11)) to divert these cables and pass them under the superstructure (20) of the floating platform (100) (or outside its sides).

Depending on the geometry of the floating platform (100) that the anchoring lines (200) are going to hold, the anchoring system may need some elements that facilitate its correct operation and that have already been introduced previously. Some of these elements can be seen in Figures 8 to 11, others are normal shipbuilding elements and have not been represented in the Figures. Among others we can cite:

- Intermediate pulleys to support the intermediate section (7) (rotary guide means (11)): the intermediate section (7) is in the form of a catenary supported on the inner and outer pulleys. A catenary varies its length depending on the tension to which the cable is subjected. This phenomenon translates (if the distance between pulleys is large) in that in this part the cable acts as if it were more elastic than normal and could match the philosophy of the system. To avoid this, intermediate support pulleys (rotary guide means (11)) can be placed in this section (which reduce the distance between supports and therefore drastically reduce the deflection of the corresponding catenary), so that the cable behaves almost as if go in a straight line and the cable recovers its original rigidity. It also serves to reorient the intermediate section (7) (to avoid obstacles in the structure);

External pulley support arms (protruding structural arms (12)): in floating platforms (100) that serve as support for a wind turbine, the diameter of the floating platform (100) is much less than the optimal distance to place the external pulley . Some radial protruding structural arms (12) are then needed that protrude from the main structure (400) of the floating platform (100) and from which the external pulley hangs. Each protruding structural arm (12) can be a reticulated structure (the elements are exposed to the weather) or a closed structure (the elements are protected from the weather); the choice of one type or another will depend on the philosophy of each specific design. The floating platforms (100) that support a wind turbine have several characteristics, among others:

The floating platform (100) does not need a large deck area, it can be a small buoy that supports the weight of the wind turbine and its tower (13);

- The main force that acts on the system and that must be taken into account in the design is the aerodynamic thrust of the wind on the rotor blades of the wind turbine;

The force of the wind exerts a very large bending moment on the base of the tower (13).

If the anchoring lines (200) in the design condition are not vertical (as seen in Figure 13), but slightly divergent (as seen in Figure 14), then when the floating platform (100) looks dragged by the wind, the leeward pulley rises with respect to the windward one, as a consequence, the floating platform (100) has a pitch angle opposite to the force of the wind. This pitch angle is proportional to the horizontal displacement of the floating platform (100) and is barely sensitive to its vertical movement.

This angle causes the weight (Q) of the nacelle (14) to have an axial component opposite to the wind thrust on the rotor blades, which is proportional to the angle rotated, which in turn is proportional to the horizontal movement of the floating platform. (100), which in turn is proportional to the force exerted by the wind. If these proportionality constants are properly synchronized, it can be achieved that the axial component of the weight of the nacelle (14) exactly cancels the force of the wind, whatever the wind speed.

In this way, the bending moment at the base of the tower (13) due to the wind could be completely cancelled. The forces and moments due to the waves would still remain, but they are minor forces and moments. Consequently: - The tower (13) could be lightened, giving less thickness to its structural elements;

The forces acting on the nacelle load bearings (14) are reduced;

- The loads on the anchorage are reduced, and the structure of the floating platform (100) can be light (and cheap to build).

On floating platforms (100) dedicated to marine leisure, the external agent that has the most influence on passenger comfort is the effect of the waves. With the anchoring system of the present invention, the turning movements of the floating platform (100) are cancelled, the vertical movement has little influence (especially if a semi-submersible floating platform (100) is used), but the effect of the horizontal movement of the waves, which with severe seas can generate significant accelerations (up to 1.5 m/s ² ).

In some applications, an anchoring system with divergent anchoring lines (200) can be used, which produces a pitch opposite to the horizontal movement. This pitching can generate a longitudinal acceleration that opposes the acceleration of the horizontal movement, so that the resultant is less than if the floating platform (100) moves without pitching, this would improve the comfort of the people on board.

A terrestrial analogy of this reverse pitch and pan motion would be the motion of a swing or a hammock, it has large motions and turns, but does not have the psychological sensation of accelerations. In fact, the accelerations remain perpendicular to the surface of the deck of the floating platform (100) (perpendicular to the surface of the seat, in the case of the swing).

The operating scheme would be similar to that of Figure 7, but with a divergence angle (A) somewhat greater than that shown in this Figure. One difficulty that appears is that the cancellation of the longitudinal accelerations can only be achieved for a relatively small range of waves, for example this cancellation can be achieved for waves between 8s and 10s, it is then a question of tuning these periods with the periods of the waves. most probable waves, this tuning depends on:

The geometry of the floating platform (100), its stability and its inertia;

The geometry of the mooring lines (200) and their elastic characteristics.

The anchoring line cable (200) is quite long, it measures at least the draft in the area of operation, plus the length of the outgoing structural arms (12) (usually between 30 and 40m), plus double the the height between the pulleys and the sea surface, plus twice the maximum vertical travel of the floating platform (100) (maximum tide height + wave height), plus 20% of the sea depth in the area of installation, plus the margin that is deemed appropriate.

In some applications, the bottom sections (8) do not reach the sea bed or bottom (5), but are attached to an intermediate buoy (9) located relatively close to the sea surface and which is anchored to the sea bottom ( 5) by means of chains or cables, so that in case of wear only the upper part of the cable needs to be changed, which is the part that wears out the most (and is also the most accessible part).

The length of the detachable cables must be such that, with the greatest foreseeable movements of the floating platform (100), the buoys (9) never come close to the outer pulleys (first rotating fixing means (3)); if they touched, a major failure could occur. The material of the anchoring lines (200) can be any that is suitable for these applications, among others: - Braided metallic cable: there is no possibility of it twisting, since the tension of the lines (applied according to the edges of a vertical prism) prevents the yaw rotation of the floating platform (100);

Cable of synthetic or textile material;

- Link chains: this is ideal for the intermediate section (7) (and the upper part of the other two sections (6, 8)) of the floating platforms (100) that serve as a support for a wind turbine, since it allows the use of pulleys notched (at the buffer lines) and have relatively small radii of gyration. Its drawback is that it is louder. For leisure facilities it is less recommended and should be very well acoustically insulated. In the floating platforms (100) for marine leisure, the intermediate section (7) and the upper part of the other two sections (6, 8) should be made of textile material, because with waves, it is moving continuously and would have a more quieter than if it is a chain with links (which could cause noise problems in the structure).

One of the advantages of the anchoring system of the present invention is the ease of transportation, installation and uninstallation of the platforms equipped with this anchoring system.

Next, the installation procedure of the floating platform (100) is described in somewhat more detail.

In the ballast condition, the submerged flotation elements (500) of the platform float at half height, giving the floating platform (100) all or part of the stability it needs for its transfer. The existence of a buoyancy reserve (materialized in the emerging area (16) or non-submerged part of the flotation elements (500)), allows the floating platform (100) to remain stable throughout the transfer, despite the pitching motions produced by waves. As already mentioned, in the case of the second embodiment of the anchoring system, in its condition as ballast the floating platform (100) also needs to be anchored to an anchoring ring to guarantee its stability during transport.

Before moving the floating platform (100), the bottom anchors of the mooring lines (200) are prepared. To do this, the background weights (4) are placed in their position, which can be of any type:

- Anchoring by piles;

Individual bottom weights (4) located on a smoothed area of the seabed (5);

- An anchoring ring, deposited on the seabed (5) by any procedure.

In these bottom weights (4) the common part (the first portion or lower portion) of the bottom sections (8) of the anchoring lines (200) that in turn hold the buoys (9) are attached or fixed. intermediate. The buoys (9) are leveled, so that they are all at the same depth and at the same distance from the central axis (300) of the floating platform (100).

This operation can be done while the platform is being built.

To transport the floating platform (100), a tugboat is enough to drag the floating platform (100) and the counterweight (1) to the wind farm. Optionally, the counterweight (1) can be placed just below the floating platform (100) (lightly supported by the central sections (6) of the sublines (200c, 200d) of the anchoring lines (200)) and towed together. During the transfer, all the ballast tanks or floodable chambers of the floating platform (100) and of the counterweight (1) are kept completely empty. In this condition, the counterweight (1) has a slightly positive buoyancy, with a small freeboard relative to its upright.

The first phase of the installation is very simple, just place the floating platform (100) on top of the anchors, with the counterweight (1) under the center of the floating platform (100), as can be seen in Figure 10. In this phase it is not necessary to resort to any external stabilization system, since both the floating platform (100) and the counterweight (1) are stable 'per se'.

Next, the upper portions (second portions) of the bottom sections (8) of the anchoring lines (200) are attached to the intermediate buoys (9). The cables are prepared with the length that they must have in the operational condition, so when they are hooked they will be slack (geometrically there is excess cable in this condition). To tighten them, it is enough to slightly move the floating platform (100) from its vertical position on the anchors (with the tug that brought it), or even let the wind drag the floating platform (100) laterally until these cables are slightly taut.

One of the tanks or floodable chambers of the counterweight (1) is filled, so that it has a slightly negative buoyancy. The counterweight (1) begins to submerge and the tension of the cables returns the floating platform (100) to its position on the bottom anchors. With the floating platform (100) in place, ballast tanks or floodable chambers of the counterweight (1) continue to be filled, as a consequence of which, the floating platform (100) gradually sinks dragged by the increasing weight of the counterweight. (1) center. In this phase, the floating platform (100) is as can be seen in Figure 11:

- The counterweight (1) is increasingly submerged, with an increasing net weight;

The cables are quite taut and provide the floating platform (100) with increasing stability; - The floating platform (100) is sinking, but it still retains all its initial stability, since the flotation elements (500) have not yet fully sunk. The waterline (21) rises from the ballast float to the operating float (operating draft (22)).

As the floating platform (100) sinks, there is a moment when the floats or flotation elements (500) are completely submerged. At that instant, the inherent stability of the floating platform (100) almost disappears (or is drastically reduced). This is not a problem, since the tension of the cables has already reached more than 50% of their nominal tension and they are capable of providing the floating platform (100) with all the stability it may need.

When all the ballast tanks or floodable chambers of the counterweight (1) are completely filled with water, the floating platform (100) is almost operational, in general it will float a little above its design float (since it must have a certain margin of safety in terms of its buoyancy). At this moment, it is enough to introduce some ballast water into one of its tanks, so that the platform floats exactly as expected in its operating condition.

The assembly now looks like it can be seen in Figure 12. At this point, all that remains is to make the electrical connections of the generator with the farm's transformer station, so that the wind turbine can function normally.

To uninstall the floating platform (100), just follow the reverse process, that is:

Disconnect the electrical circuits of the wind turbine from the park's electrical network;

- Emptying the ballast compensation tank of the floating platform (100) (ie, emptying the at least one floodable chamber of the flotation elements (500)); - Gradually empty the ballast tank (at least one floodable chamber) from the counterweight (1).

As this tank (the at least one floodable chamber of the flotation elements (500)) is emptied, the floating platform (100) begins to rise (at the same time as the counterweight (1)). When the flotation elements (500) reach the surface of the sea, the floating platform (100) recovers all its stability. When the cables begin to slacken, the floating platform (100) will be dragged laterally by the wind until the counterweight (1) reaches the sea surface.

When the ballast tanks (flooded chambers) of the counterweight (1) are completely empty (and the counterweight (1) has sufficient positive buoyancy), the bottom sections (8) of the intermediate buoys (9) and the platform are released. floating (100) is ready to be transferred to another location (or to port, for periodic maintenance operations).

Thus, the anchoring system for marine floating platforms (100), object of the present invention, is preferably formed by four or six anchoring lines (200), arranged radially around a common point (10) of the floating platform ( 100), each of which is made up of two funding sublines (200c, 200d) that may include the following elements:

An inner pulley (2) (second rotary fixing means (2c) and, optionally, third rotary fixing means (2d)) and another outer pulley (first rotary fixing means (3)), located in the upper part of the anchor line (200); They can be simple (with a single sheave) or multiple (with several superimposed parallel sheaves);

A central counterweight (1) common to all the anchoring lines (200), located below the intersection point of all the anchoring lines (200), with several ballast tanks or floodable chambers, such that, when the ballast tanks counterweight (1) are empty, has a small positive buoyancy (for example, less than 20% of the total volume of the counterweight (1)) and when all ballast tanks in the center counterweight (1) are flooded, has a weight apparent (net) large (for example, greater than 15% of the total displacement of the floating platform (100));

A flotation ring (700) or several flotation elements (500), with several ballast tanks or floodable chambers such that, when the flotation ring ballast tanks are empty, it has a small positive buoyancy (less than 20% of the total volume of the floatation ring) and when the floatation ring ballast tanks are fully flooded, it has a very large apparent weight (greater than 15% of the total displacement of the floating platform (100)).

An anchoring ring common to all the anchoring lines or several fund weights (4) (one for each anchoring line (200)). In the operating condition, the anchoring ring rests on the seabed (5) and performs the functions of the anchor of a conventional ship, preventing the wind, sea currents or waves from dragging the floating platform (100). In some applications, it can be replaced by various conventional anchors on the seabed (5) (piles, suction anchors,...), to which the anchoring system cables are attached.

An anchor cable, which joins the central counterweight (1) with the anchor ring (or with each one of the bottom weights (4) or anchor anchors) and that rests on the inner pulley(s). (2) and on the outer pulley (first rotary fixing means (3)) of each anchoring line (200), virtually divided into three zones or sections: the central section (6) of the anchoring cable, which runs from the central counterweight (1) to the inner pulley (2) of that subline (200c, 200d), the intermediate section (7) of the anchoring cable, between the inner pulley (2) and the outer pulley (first rotating fixing means (3)), and the bottom section (8) of the anchoring cable, which goes from the outer pulley (first rotating fixing means (3)) to the anchoring ring or bottom weight (4). As auxiliary elements, each anchor line (200) can also include any of the following elements: o One or more intermediate pulleys (rotary guide means (11)), which serve as support for the intermediate section (7) of the mooring cable, inserted between the inner pulley (2) and the outer pulley (first rotary fixing means ( 3)), which serve as support or help to change the route of said section; o An intermediate buoy (9) inserted in the bottom section (8) of the anchoring lines (200). If any, it is connected to the bottom weight (4) by means of another cable segment that constitutes a first portion of the bottom section (8); o A protruding structural arm (12) to support the anchoring line (200), supported (or embedded) on the deck or in the hull or in the superstructure (20) of the floating platform (100), from which hang: the outer pulley (first rotating fixing means (3)), the inner pulley (2) and the support pulleys (rotary guiding means (11)) of the intermediate section (7) (if any).

The anchoring system of the present invention can also include other auxiliary elements, common to conventional anchoring systems and that can help to install/uninstall the floating platform (100) in its place of operation, such as winches, windlasses, bitts or other typical elements of any traditional anchoring system.

Each mooring line (200) has a direct subline (200d) and a crossed subline (200c), whose inner pulley (second rotary fixing means (2c)) is located diametrically opposite the outer pulley (first rotary fixing means ( 3)). The mooring system has an even number of protruding structural arms (12) and the corresponding mooring lines (200) are arranged two by two in diametrically opposite positions. In the project position, at rest and with calm seas, the bottom sections (8) of the anchoring cable of all the anchoring sublines (200c, 200d) can be vertical (and parallel to each other).

Alternatively, the bottom section (8) of all the anchoring sublines (200c, 200d) can be slightly divergent, that is, the anchoring point of the anchoring cable in the bottom weights (4) is more horizontally separated from the counterweight ( 1) central than the outer pulley (first rotating fixing means (3)).

The floating platform (100) can comprise the following elements:

A partially submerged hull or main structure (400) with any geometry;

- A tower (13) supporting an offshore wind turbine, located just above the hull of the floating platform (100);

A complete marine wind turbine, whose nacelle (14) is installed on top of the corresponding tower (13);

- A central counterweight (1), located in the central axis (300) of symmetry of the floating platform (100), hung from the central sections (6) of all anchoring lines (200). Inside there is a series of ballast tanks or floodable chambers, which meet the following restrictions: With all the ballast tanks empty, the central counterweight (1) has a slightly positive buoyancy (floats). With one or more of the tanks flooded, the buoyancy of the central counterweight (1) is slightly negative (it sinks). With all ballast tanks flooded, the apparent (net) weight of the central counterweight (1) is large (eg at least 15% of the total weight of the floating platform (100)); - 4 or 6 protruding structural arms (12) to support the mooring lines

(200), arranged radially around the central axis (300) of symmetry of the hull of the floating platform (100). From the ends (121, 122) of each protruding structural arm (12) hang the outer pulleys (first rotatable fixing means (3)) of the lines associated with each protruding structural arm (12). These pulleys can be simple (with one sheave) or multiple (with several superimposed sheaves);

- The anchoring cable hangs from the two pulleys, the inner pulley (2) and the outer pulley (first rotary fixing means (3)) of each protruding structural arm (12). The central section (6) of the anchoring cable hangs from the inner pulley (2) and is held in the central counterweight (1). The bottom section (8) of the mooring cable hangs from the outer pulley (first rotating fixing means (3)) and is fastened to the mooring ring, to the bottom weights (4) or to anchors fixed to the bed. or seabed (5). The anchor cable can be simple (a single cable) or multiple (several cables).

The hull or main structure (400) of the floating platform (100) has two main loading conditions: a transportation condition, in which all its ballast tanks are empty and it floats freely with a characteristic waterline (21), and an operating condition, in which all the mooring lines (200) are connected to the seabed (5) and support the net weight of the central counterweight (1). Some of its ballast tanks may be totally or partially full so that its waterline (21) coincides with the project waterline (operating draft (22)).

According to a possible embodiment, the floating platform (100) comprises the following elements:

- Four cylindrical floats or flotation elements (500), separated from the central axis (300) of the floating platform (100), evenly distributed around it. The waterline (21) in the ballast condition is located at half height of these floats, defining two volumes in them, the submerged zone (15) and the emerging zone (16) or emerged (the rest of the float). In ballast condition (floating platform transfer (100)) your floatation surface gives you all the stability you need for transfer operations. In the operating condition, the floats are fully submerged and do not provide stability;

- Four legs or spokes (600), approximately prismatic in shape, inclined with respect to the vertical, which join each of the floats or flotation elements (500) with the rest of the floating platform (100). In the ballast condition, they are completely out of the water, but in the operating condition, they have a submerged part or area with a radius submerged in operating condition (17) and another part or area never submerged (18) above the waterline or of the operating draft (22). In the operating condition (or project) the floating platform (100) does not have stability 'per se';

- four protruding structural arms (12) arranged radially, approximately horizontal, which serve as support for the pulleys of the anchoring system;

- A reinforced and resistant structural ring (19), at the base of the superstructure (20), in which the legs or spokes (600) that go to the floats and the protruding structural arms (12) that support the lines are attached. funding (200);

- The superstructure (20) on the reinforced structural ring (19), which serves as the base for the tower (13) of the wind turbine and inside which the electrical equipment of the wind turbine or the electrical connection systems with the rest of the wind turbines can be located. of the wind farm;

The tower (13) and the wind turbine.

According to another possible embodiment, the floating platform (100) comprises the following elements: - A hull or main structure (400) cylindrical with a vertical axis, with three differentiated zones: the lower part or submerged zone (15), which is submerged in the ballast condition, the upper part or never submerged zone (18) that always it is above the flotation or operating draft (22) and the intermediate zone or emerging zone (16) or emerged, which is between the ballast flotation and the project;

- Four protruding structural arms (12) that support the mooring system pulleys, attached to the upper part or never submerged area (18) of the hull, where a mooring line hangs from each of the protruding structural arms (12) ( 200);

- An anchoring ring, which groups the four bottom weights (4), which provides the necessary stability to the floating platform (100) (according to this embodiment with a cylindrical hull) during transfer and installation operations, and is incompatible with the use of pre-fixed anchors to the seabed (5), since it does not have its own stability.

According to another alternative embodiment, the floating platform (100) comprises the following elements: with four arms (and therefore with four mooring lines and four legs). The main and characteristic elements of its geometry are:

- The submerged hull is formed by a slender flotation ring (700), with a large diameter (compared to its height or thickness), which in the ballast condition has two parts, a submerged area (15) that is always submerged and another emerging zone (16) or emerged, which in the ballast condition is above the waterline (21), but in operation it is totally submerged; - Four legs or radios (600), inclined with respect to the vertical, uniformly distributed, which join the submerged hull with the resistant structural ring (19);

- Four protruding structural arms (12) that hold the pulleys and anchoring lines (200) of the anchoring system; these four protruding structural arms (12) are attached to the submerged hull and are also quite inclined with respect to the vertical;

- The central sections (6) of all the anchoring sublines (200c, 200d) go from the inner pulleys (2) to the counterweight (1), passing through the inner hole of the flotation ring (700) that forms the hull or main structure (400) submerged.

For those floating platforms (100) that are stable "per se" in the ballast condition, the following simplified sequence of installation phases can be followed:

- The platform (100) is built by any conventional shipbuilding procedure and is launched (thrown into the water). The central counterweight (1) is also built, all its ballast tanks are emptied and it is launched;

- All the equipment on board has been installed, including the tower (13) and the wind turbine, the platform now floats in its ballast condition and is perfectly stable with all the ballast tanks empty;

- The bottom anchors of the floating platform (100) are fixed at their destination (by means of piles, bottom weights (4), an anchoring ring or any other conventional anchoring system), the lower sections of the section are installed bottom (8) and are hooked to an intermediate buoy (9), which has a buoyancy slightly higher than the own weight of the cables that join it to the bottom; the buoy (9) remains floating at half height, all at the same depth; - The floating platform (100) and the counterweight (1) are transferred to their destination, using a conventional tugboat. The central counterweight (1) is located under the axis of the floating platform (100);

- The cables of all the anchoring sublines (200c, 200d) are connected both to the central counterweight (1) and to the intermediate buoys (9); At this moment, the cables are slack, since they are somewhat longer than the actual distances between the counterweight (1), the outer pulleys (first rotating fixing means (3)) and the intermediate buoys (9);

- The floating platform (100) is towed laterally (with the tug), until the anchoring system cables are slightly taut;

- The counterweight ballast tanks (1) are flooded very slowly; when the counterweight (1) reaches an apparent density equal to that of seawater, it begins to sink, dragging the floating platform (100) towards its project position;

- As the apparent density of the counterweight (1) increases, the tension in the cables increases and the floating platform (100) begins to sink slowly. When all the ballast tanks of the central counterweight (1) are full, the floating platform (100) is almost at its design draft or operating draft (22);

- The draft of the floating platform (100) is corrected by totally or partially filling any of the ballast tanks or floodable chambers of the floating platform (100) (of the flotation elements (500) or of the flotation ring (700)) ;

The electrical connection of the floating platform (100) with the rest of the wind farm is made. At this time, the floating platform (100) is fully operational.

For those floating platforms (100) that are stable "per se" in the ballast condition, the following simplified sequence of uninstall phases can be followed (inverse of the sequence of installation phases described above):

- The floating platform (100) is electrically disconnected from the rest of the wind farm;

The ballast tanks or floodable chambers of the floating platform (100) are emptied (of the flotation elements (500) or of the flotation ring (700));

- The ballast tanks or floodable chambers of the central counterweight (1) are emptied, by means of hydraulic pumps or by injecting compressed air inside;

- As the counterweight (1) loses its net weight, the anchoring line cables (200) loosen; the floating platform (100) slowly rises and the counterweight (1) approaches the surface;

- When the submerged floats or flotation elements (500) of the floating platform (100) reach the sea surface, the floating platform (100) recovers all its stability and no longer needs the stability provided by the cables of the anchoring;

- A tugboat is attached to the floating platform (100) and a lateral force is exerted that tends to separate the floating platform (100) from its equilibrium position; - When the counterweight (1) reaches the surface, the floating platform (100) will have moved laterally, then the ballast tanks of the counterweight (1) are emptied, until it acquires all the buoyancy of its transport condition. ;

- The tugboat's towing cable is released and then the hooks of all the central sections (6) of the counterweight (1) and of all the bottom sections (8) of the intermediate buoy (9) are released. At this moment, both the floating platform (100) and the central counterweight (1) float by themselves, with all the stability they need and are ready to be moved to another location or to the port for maintenance operations.

Claims

1. Anchoring system comprising a floating platform (100) and at least one pair of anchoring lines (200), configured to fix or anchor the floating platform (100) to the seabed (5) through at least one bottom section (8) of each mooring line (200), where each mooring line (200) also includes a central section (6) attached to a counterweight (1), where each pair of mooring lines (200) includes two mooring lines. anchorage (200) arranged in a plane that passes through a central axis (300) of the floating platform (100), and located respectively on one side and the other of the central axis (300) of the floating platform (100), where the system anchorage comprises at least one first rotary fixing means (3) for each anchoring line (200), where each first rotary fixing means (3) is fixed to a first point of the floating platform (100) and is configured to fix each anchor line (200) to the floating platform (100) at said first point of the floating platform e (100), allowing the anchoring line (200) to slide by said first rotating fixing means (3), characterized in that:

- each anchoring line (200) comprises at least one direct subline (200d) and one crossed subline (200c), each of them comprising its own anchoring cable or chain, where each direct subline (200d) runs from the first medium rotary fixing device (3) to the counterweight (1) without passing through the central axis (300) of the floating platform (100), and where each crossed subline (200c) runs from the first rotary fixing device (3) to the counterweight (1) traversing the central axis (300) of the floating platform (100);

- where the system comprises at least one second rotary fixing means (2c) for each anchoring line (200), where each second rotary fixing means (2c) is fixed to a second point of the floating platform (100) and is configured to fix each crossed subline (200c) of each anchor line (200) to the floating platform (100) at said second point of the floating platform (100) allowing the sliding of the crossed subline (200c) by said second means of rotary fixing (2c), in such a way that each crossed subline (200c) runs from the first rotary fixing means (3) to the counterweight (1) firstly traversing the central axis (300) of the floating platform (100) and secondly sliding through the second rotary fixing means (2c).

2. Anchoring system according to claim 1, characterized in that the floating platform (100) comprises a pair of protruding structural arms (12) for each pair of anchoring lines (200), where each pair of protruding structural arms (12) It comprises a first arm (12a) and a second arm (12b) located symmetrically with respect to the central axis (300) of the floating platform (100), where each protruding structural arm (12) is attached to a main structure (400) of the floating platform (100), where each protruding structural arm (12) runs radially from a first end (121) attached to the main structure (400) of the floating platform (1) to a second end (122) projecting outwards of the floating platform (1), where the at least one first rotary fixing means (3) is fixed to the floating platform (100) in correspondence with the second end (122) of the first arm (12a), and where the al least one second means of fixation rotary ion (2) is fixed to the floating platform (100) at a point located in correspondence with the second arm (12b).

3. Mooring system according to claim 2, characterized in that the main structure (400) of the floating platform (100) comprises a geometry in the form of a cylindrical, conical or pyramidal shaft.

4. Mooring system according to claim 3, characterized in that it comprises a plurality of spokes (600) connected to the main structure (400), where at each free end of each spoke (600) there is a flotation element (500).

5. Mooring system according to claim 4, characterized in that the flotation elements (500) comprise at least one floodable chamber.

6. Mooring system according to claim 3, characterized in that the main structure (400) comprises at least one flotation element (500).

7. Mooring system according to claim 6, characterized in that the at least one flotation element (500) comprises at least one floodable chamber.

8. Anchoring system according to claim 2, characterized in that the main structure (400) of the floating platform (100) comprises a ring-shaped geometry, said ring being joined by means of spokes (600) to a cylindrical, conical shaft or pyramidal.

9. Mooring system according to claim 8, characterized in that the main structure (400) constitutes a flotation ring (700).

10. Mooring system according to claim 9, characterized in that the floating ring (700) comprises at least one floodable chamber.

11. Mooring system according to any of the preceding claims, characterized in that it comprises at least one third rotating fixing means (2d) for each mooring line (200), where each third rotating fixing means (2d) is fixed to a third point of the floating platform (100) and is configured to fix each direct subline (200d) of each anchor line (200) to the floating platform (100) at said third point of the floating platform (100) allowing the sliding of the direct subline (200d) by said third rotary fixing means (2d), in such a way that each direct subline (200d) runs from the first rotary fixing means (3) to the counterweight (1) passing and sliding through the third rotary fixing means (2d)..

12. Anchoring system according to any of the preceding claims, characterized in that it comprises at least one rotary guide means (11) for each anchor line (200), where each rotary guide means (11) is fixed to a fourth point. of the floating platform (100) and is configured to guide the course of the crossed subline (200c) of each anchor line (200) allowing the sliding of the crossed subline (200c) by said rotary guide means (11), in such a way that each crossed subline (200c) runs between the first rotary fixing means (3) and the second rotary fixing means (2c) passing and sliding through the rotating guide means (11).

13. Anchoring system according to any of the preceding claims, characterized in that each bottom section (8) of each anchoring line (200) comprises a buoy (9) that divides the bottom section (8) into a first portion that it runs between the seabed (5) and the buoy (9) and a second portion that runs between the buoy (9) and the at least one first rotating fixing means (3).

14. Mooring system according to any of the preceding claims, characterized in that the counterweight (1) comprises at least one floodable chamber.

15. Installation procedure for a floating platform (1) using an anchoring system according to claim 14, characterized in that it comprises:

- position and/or anchor to the seabed (5), under an installation place of the floating platform (100), at least one anchor and/or at least one bottom weight (4), and/or at least one ring anchorage and/or a set of piles; moving the floating platform (100) and the counterweight (1) to its installation location, where the at least one floodable chamber is not flooded;

- fix a free end of the bottom section (8) of each anchoring line (200): or at least one anchor and/or at least one bottom weight (4), and/or at least one ring anchoring and/or to the set of piles, or; or to a buoy (9) previously attached by means of a first portion of the bottom section (8) of the anchoring line (200) to at least one anchor and/or at least one bottom weight (4), and/or to the at least one anchoring ring and/or set of piles;

- fix a free end of the central section (6) of each anchoring line (200) to the counterweight (1);

- drag the floating platform (100) laterally until the anchoring lines (200) are taut, e;

- flooding the at least one flotation chamber.