WO2021094635A1

WO2021094635A1 - System for righting and reducing movements in floating platforms

Info

Publication number: WO2021094635A1
Application number: PCT/ES2020/070694
Authority: WO
Inventors: Manuel MOREU MUNAIZ; Jaime MOREU GAMAZO; Miguel Jesús TABOADA GOSÁLVEZ; Santiago DE GUZMÁN MONTÓN; Mirian TERCEÑO HERNÁNDEZ; Pedro BUENO ENCISO; Albino POMBO SILVA; Rafael AGÜI MARTÍN
Original assignee: Seaplace S.L.
Priority date: 2019-11-11
Filing date: 2020-11-10
Publication date: 2021-05-20
Also published as: ES2824373B2; ES2824373A1

Abstract

The invention relates to a method and a system that allows the reduction of pitch–roll movements in a floating wind platform formed by at least one floating body, and the reduction/countering of the average slope of the platform, simultaneously combining during the operation of the wind turbine an active ballast system and a passive ballast system that exclusively act on the water depth in the ballast tanks.

Description

SYSTEM TO STRAIGHTEN AND REDUCE MOVEMENTS ON PLATFORMS

FLOATING

TECHNICAL SECTOR The main technical field of application of the present invention is that of floating marine structures of the wind sector industry, such as those for supporting wind generators, substations and the like, in addition to the application for floating marine structures of the hydrocarbon sector industry or any type of marine floating device or unit. Procedure and system that allows a floating wind turbine platform made up of at least one floating body, the reduction of pitch-roll movements and the reduction / cancellation of the average inclination of the platform, combining during the operation of the wind turbine, simultaneously, a active and passive ballast system in which only the height of the water in the ballast tanks is acted upon. BACKGROUND OF THE INVENTION

The rise of renewable energies leads to a search for greater use of these. Particularly for wind energy, the trend observed is that of the installation of platforms at sea where wind speeds are higher than on land (and less turbulent), thus ensuring greater energy production. These wind characteristics also improve the further we get from the coast.

However, these sites have the drawback that in many cases the fixed platforms (platforms that are already economized and well known) are not competitive, either due to unevenness in the seabed, the type of soil or because we are at depths greater than 60 meters. This leads to the most viable solutions becoming floating ones, with the consequent alteration in cost due to the increase in the size of the solutions, the need for an anchoring system and means of anchoring to the seabed, different marine operations, new uncertainties, risks ... In addition, these platforms, as they are not fixed, are exposed to movements induced by wind, waves and current, which make

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SUBSTITUTE SHEET (RULE 26) that decreases the performance of the wind generator, increases the fatigue of certain components of the unit, possibility of resonances, etc.

Currently there are multiple floating solutions, some of them operating, others in demonstration, and a majority in development. These solutions are mainly based on four types of structures from the Oil Industry, being many other hybrids that take advantage of the best characteristics of each classic typology: Spars, TLPs (Tension Leg Platforms), Semisubmersibles (or semis), and barges ( barges). Spar-type structures are traditionally slender structures that are characterized in that the center of gravity is below the center of the submerged volume or center of the hull, thus ensuring stability. These structures generally have a better performance than semi-submersible structures to vertical movements (arfada) due to their great draft and have a reduced response to the vertical excitation forces of the waves. With regard to TLPs, these are structures that have excess buoyancy thanks to submerged bodies, obtaining stability through a pre-tensioned tendon mooring. This structure is very rigid in the face of vertical and angular movements (the tendons act almost as if the structure were fixed). However, its constructive complexity, high installation cost and possible frequency couplings mean that this solution remains far from the market for the moment. For their part, semi-submersibles are stabilized structures thanks to the buoyancy area, obtained by several columns separated from each other, which in general present very good behavior in pitch and roll, although not so much in vertical movements, having to have damping means. These platforms are very stable and the transport and installation operations are greatly simplified compared to the other typologies. Finally, barges are solutions that achieve stability thanks to the area in the flotation of a single body (instead of several columns like semi-submersibles). This results in a more compact structure than semi-submersibles but with a large area in the flotation and therefore subject to great accelerations, which affects the different components.

Of today's floating solutions, some are designed to reduce the mean tilt, thereby increasing the performance of the wind generator. When the wind hits the turbine during operation, it is transformed into energy

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SUBSTITUTE SHEET (RULE 26) mechanical thanks to the rotation of the blades, and produces a moment that tends to tilt the tower in the same direction of the wind with respect to the vertical. This inclination means that the area swept by the blades is no longer perpendicular to the wind direction, and therefore, the power produced decreases. In general, there is a maximum allowable dynamically in operation of 10 degrees of inclination of the tower with respect to the vertical, although it is preferable to be below three degrees. For this, the so-called active ballast systems or active heel compensating systems, which are common on ships, can be installed. Your goal is the cancellation of the average lean angle. In the case of ships, the list is usually mainly due to asymmetric loading situations or flooding. In the case of a wind platform, the heel is due to the action of the wind. To cancel the heel (or set it at a zero degree angle) the heel compensator system transfers ballast water between tanks, thus generating a torque that opposes the heeling. These systems, mostly installed on semi-submersible platforms, barges, or hybrid solutions, are also used to minimize transportation and installation costs since they help reduce the external auxiliary means necessary for transporting and installing the platform. The complexity of these systems varies from one platform to another, as well as the means to carry out the ballasting and the ways of transferring water between tanks. The correction of the mean heel with ballast tanks is considered by the industry as an active correction. That is, if the average heel is non-zero, and we want to cancel it, it is necessary to transfer water from one tank to another, which requires a contribution of energy, which gives it the connotation of active correction.

But the platforms are not only subjected to the action of the wind. There is also the swell, which, together with the variability of the wind and currents, causes the movement of the units around the average inclination of the unit. Although the designs are optimized to have the best possible behavior at sea, the existence of means on the platform that improve the behavior at sea during operation will allow an additional decrease in Operation and Maintenance Costs due to the increase in life to fatigue, the lengthening of the times between maintenance and the increase in the useful life in general, increasing the operational availability times and making the solution more competitive. To reduce the movements produced by the waves and the current, the marine industry distinguishes between active means (such as gyrostabilizers) or passive (such as anti-balance tanks,

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SUBSTITUTE SHEET (RULE 26) which can be either free surface, or in a "U" arrangement).

In free-surface tanks, the simplest passive tanks, the water moves from side to side of the tank, the natural oscillation frequency depending on the height of the water in the tank (as well as the dimensions of the tank). Thus, the natural frequency of the tank can be adjusted to a certain value thanks to the variation of the water level, so that the tank, when excited near its resonance, opposes passively, that is, without requiring the external contribution of energy, a moment that reduces high-frequency pitch or roll motion. Although an initial energy input is required to adjust the height of the tank for it to work effectively, the operation of free-surface tanks is considered passive in the marine industry. This is due to the fact that this energy contribution seeks to adjust the resonant period of the tank, but once it is done, the water inside the tank moves by itself (due to the effect of waves, wind and currents). These movements of the water inside the tank thus carry out a passive correction every few seconds.

In U-arrangement tanks, the principle of operation is different. A tank with a “U” shape (FIG 4B), consists of two vertical columns communicated by its lower part. This tank achieves damping through the oscillating movement of the mass of water contained in them.

There are solutions in which there are active systems to reduce movements on platforms:

The solution presented in ES2681271T3 refers to a procedure to control an inclination of a floating wind turbine platform of at least three stabilizing columns on which the tower is mounted, each one having an internal volume to contain the ballast. Based on the measurements received by the sensor system, the control system adjusts the turbine pitch and torque to maximize energy production, and in turn acts on the ballast tanks in order to reduce movements. low frequency roll and pitch due to swell and / or wind. This solution is applicable to platforms with at least three independent stabilizing columns, each one acting as a ballast tank. This fact limits the field of application of the invention ES2681271T3 to other platforms, where the present invention of this document does

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SUBSTITUTE SHEET (RULE 26) it is applicable, for example, to platforms with a single floating body, subdivided inside into different ballast tanks. On the other hand, the ballast system described in the patent is an active ballast system, focused on compensating for low frequency movements due to waves and / or wind through the transfer of ballast water by means of pumps between the stabilizing columns. . The low frequency movements on the platform are mainly due to the action of the wind and to a lesser extent to the waves, being able to give some swell with sufficiently high wave periods that can be mitigated with the active ballast system. However, the waves generally on floating offshore platforms produce high-frequency pitching and rolling movements, which lead to strong accelerations in the turbine and great stresses in the tower that supports it. Patent ES2681271T3 lacks means to mitigate these high-frequency movements in its procedure, since the response times that active ballast systems have by means of pumping are high, and are outside the range of the wave frequency. The present invention improves the ballast system in this aspect by adding passive compensation means, which have lower periods of action, that is to say, higher frequencies, which makes it possible to compensate for the pitch and roll movements of the platform. These passive means of the present invention are based on anti-balance tanks that can be free-surface or with a “U” arrangement.

On the other hand, there are solutions in which an active system and a passive system are combined to reduce movements on platforms: a) The solution presented in ES 2643906 T3 is a simultaneous action solution. In this case, the active system is only designed to correct the inclination of the platform, being the platform itself the one that has external structural means that allow the damping of the movement against the action of the waves and the current by increasing the mass. added. These structural means that act as a passive system, commonly called heave piafes, in order to be effective and resist the excitation force of the waves, fatigue and other stresses to which they are exposed, require dimensions and a major booster. This makes this passive system much more expensive than the one exposed in the present invention, which does not entail any additional cost since what it does is take advantage of the existing tanks on the platform.

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SUBSTITUTE SHEET (RULE 26) applying the principle of free surface anti-roll tanks for the correction of roll / pitch movements. These damping systems, arfada plates, are applicable to semi-submersible type floating structures while the present invention is applicable to any floating unit that has ballast tanks. The active system of this solution only corrects the inclination of the platform whereas in the present invention the tanks that act in the correction of the inclination thanks to the active system can also act simultaneously correcting the movements of roll and pitch by adjusting their appropriate way. filling height without affecting the correction of the mean tilt. Therefore, the tanks belonging to the system of the present invention act indistinctly as active (heel correction) or passive (roll and pitch correction) and, depending on the required performance, with the possibility of the same tank acting simultaneously. actively and passively. b) The US 4864968A solution also presents a combination of an active system and a passive system for the control of movements, although their operation is not simultaneous. Trim / list correction is performed actively, while roll / pitch damping can be performed actively or passively, but in no case simultaneously, since the active system is based on acting on the pressurization of tanks and the passive system. communicates the pressurized tanks with the outside, thus losing the simultaneity. The present invention, in addition to having simultaneity, does not require energy input during the damping of the roll / pitch movement, although its effectiveness can be optimized by modifying the water heights in the free surface tanks. Therefore, it is more economical in operation as it tends towards passivity and is adjustable with less energy expenditure.

And there are also active-passive solutions but exclusively for the damping of the movement in arfada of platforms: c) The US 4167147A solution presents an active-passive system of air pressure chambers controlled by pumps with or without valves that allow filling / emptying of ballast tanks open to the sea exerting an anti-stress force

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SUBSTITUTE SHEET (RULE 26) arfada (the arfada being the vertical movement of the platform) which is a function of the speed of the oscillation of the platform. This system can be operated actively by controlling pumps and valves, in a purely passive way producing a pressure difference in the tanks by opening valves and turning off pumps or, in a controlled passive way acting exclusively on the valves. However, this solution does not correct the roll / pitch of the platform. The passive system of the present invention has the advantage of being the most economical system in the industry by not having the need to have any means to damp the movement since it is based on the principle of free surface tanks. Furthermore, the present invention does not correct the arfade movement. d) The principle of operation of the U-shaped tanks is another passive method that allows the improvement of the behavior at sea of the floating units. However, this system is only capable of damping the movement when the direction of incidence of the waves is parallel to the tube that joins the tanks. Therefore, in the US2019 / 0061884 A1 solution, a multidirectional damping system for U-shaped tanks is proposed, which can be pure passive or passive controlled through valve actuation. The passive system of the present invention also allows multidirectional damping without the need for connection between tanks, since the principle of operation is that of free surface, with the consequent saving of material, which is not negligible, and without the need for means. restriction of fluid movement, whether liquid or gaseous, as stated in the solution US2019 / 0061884 A1.

EXPLANATION OF THE INVENTION

The present invention refers to a procedure, and systems, for righting and reducing movements in marine installations whose innovative feature consists in the combination of a passive system and an active ballast system that allows, through a combined operation of both systems, for On the one hand, to increase the operating performance of the wind turbine by being able to cancel the average inclination of the platform when faced with the action of the wind and current (active system), and, on the other hand, to increase the fatigue life of the platform (in addition to its components) and reduce maintenance costs by improving the

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SUBSTITUTE SHEET (RULE 26) behavior at sea since it is capable of reducing the pitch and roll movements of the platform when it faces the action of the waves and the variability of the wind (passive system, based on passive anti-roll tanks, whose efficiency is adjusted by the active system). Fatigue on the turbine and tower components will also be reduced by canceling the mean platform tilt.

The procedure for righting and reducing movements in marine facilities is established based on a subsystem of sensors where environmental measurements (wave height, periods, wind speed ...) and those of the floating platform (inclination, level of ballast in tanks ...), a component subsystem (remotely actuated pumps and valves) and a control and actuator subsystem that provides automation and computer support. In this procedure, the measurements of the sensors are computed, stored and processed through the computer subsystem, which, depending on how the logic modules and calculation algorithms have been programmed, automatically establishes a transferring and ballasting process and a distribution of ballast in the system tanks to optimize a predefined target (objective function), such as, among others, correcting the mean bank in the fastest way or correcting the mean bank and compensating for roll and pitch movements with the least expense energetic.

The compensation of the average inclination consists of the transfer of water from one tank to another to generate a moment opposite to the average inclination. This compensation is called active compensation since it requires active means of transferring ballast to perform its righting function.

Compensation for movements due to waves (roll and pitch) consists of achieving that the ballast of a given tank, without communication with another tank, oscillates due to the movement of the platform itself to a period such that it compensates totally or partially the oscillation itself of the platform. The period of oscillation of the ballast in a tank is a function of the height of the water in the tank and its dimensions. This compensation is considered passive since, although it requires active means of ballast transfer to adjust the height of the water in the tank, once said transfer has been carried out, the damping of movements is a totally

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SUBSTITUTE SHEET (RULE 26) independent of any external intervention.

The present invention shows the following innovative characteristics, compared to the previously described background, of application to the offshore wind industry, substantially improving the response of floating offshore wind platforms, substations or the like against wind, waves and current: a) A single system that allows to reduce two types of movements crucial for the decrease of OPEX, on the one hand, the average inclination of the tower, and on the other the pitch and balance. b) The reduction / cancellation of movements is combined and simultaneous. c) The means used are reduced to a set of ballast tanks, a ballast system, and a control system, which allows at least two of these tanks to act indistinctly for the cancellation / reduction of the two characteristic movements. d) Movement reduction tanks can cancel / reduce by themselves all movements specified in the invention or some of them in combination with another set / sets of tanks in the system. e) An economical system that does not require many means for its installation on floating offshore wind platforms, substations or similar. f) Versatile system perfectly adaptable to any type of offshore wind floating platform, substation or similar.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is described in more detail with reference to the accompanying figures, in which by way of illustration, and not limiting, the following has been represented:

Figure 1A shows a schematic elevation and plan view of an example of a floating offshore wind platform, substation or similar, in which the object of the invention is applicable, formed by a floating body that can be completely or partially submerged.

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SUBSTITUTE SHEET (RULE 26) Figure number 1 B shows a schematic elevation and plan view of an example of a floating offshore wind platform, substation or similar, in which the object of the invention is applicable, consisting of several floating bodies that can be completely or partially submerged .

Figure number 2 shows a schematic elevation view of an example of a floating offshore wind platform, substation or similar subject to wind and collinear waves (coming from the same direction), in addition to plan-elevation views of the set of tanks of the system of reduction of movements in which the operation of the system is shown.

Figure number 3 shows a schematic elevation view of an example of a floating offshore wind platform, substation or similar subject to wind and waves whose main directions of origin form 90 °, in addition to plan-elevation views of the set of tanks of the system of reduction of movements in which the operation of the system is shown.

Figure number 4A shows elevation and plan views of an example of a free surface anti roll tank in which the wave front on the free surface of the tank can be observed, induced by the roll / pitch of the platform and that would produce the effect shock absorber on said movements.

Figure 4B shows an elevation view of a column of water between two tanks joined by a conduit through their lower part.

Figure 5 shows a diagram of the system for righting and reducing movements.

Figure 6 shows a block diagram of the system for righting and reducing movements.

PREFERRED EMBODIMENT OF THE INVENTION

Therefore, it is the object of the present invention to provide a method, and system, to right and reduce the movements of floating offshore wind platforms (1), substations or the like by means of which it is possible, during the period of operation and under conditions extreme, reduce / cancel the angle of

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SUBSTITUTE SHEET (RULE 26) average inclination of the unit with respect to the vertical produced mainly by the effect of the wind and the current and, simultaneously, reducing the roll / pitch amplitude produced by the waves and by the variability of the wind speed.

The present invention consists of a combined system to right up and reduce movements in which part of the ballast tanks (100) that make up the system, depending on the direction of incidence of the metocean conditions (wind, current and waves) on the offshore wind floating platform (1), substation or similar, can act indistinctly both to reduce pitch and roll movements, and / or to reduce / cancel the average inclination. The average inclination will be reduced / canceled by the principle of anti-heeling tanks, transferring water between tanks (100) a priori opposite, correction that is achieved exclusively by active means (ballast system). However, the reduction of roll and pitch movements will be carried out through the principle of passive free surface anti-roll tanks (FIG 4A), selecting for this purpose at least one tank in which the water oscillates preferentially along wave direction (along the longest dimension of the tank if there are no internal obstacles). By means of a previous adjustment of the water level in the tank, the reduction of movement around certain periods of the waves will be optimized in a passive way thanks to the oscillation, in opposition of phase with respect to the waves, of the front of the wave that is formed on the free surface of the tank itself. Although the free surface tank (FIG 4A) in this case acts passively, being its operation therefore very economical, the height adjustment of the tank requires the actuation of the ballast system, having an associated active initial operation. In the case of irregular waves, composed of many regular components propagating in multiple directions, several tanks (100) will be acted upon. Height variations required to reduce roll and pitch motion should not change mean bank cancellation or draft. And this is possible if you have a sufficient number of tanks (100), at least three.

When the floating offshore wind platform (1), substation or similar is installed in its final location and ready for operation, it will be ballasted according to its design requirements. Part or all of that ballast necessary for the operation will be contained in the tanks (100) of the system to rightize and reduce the movements of the platform (1), some of them not being completely full,

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SUBSTITUTE SHEET (RULE 26) thus enabling the transfer of ballast between the tanks of the system (100) to right and reduce the movements of the platform.

The offshore wind floating platform (1), substation or similar will be exposed to the action of the wind, current and waves and will vary its equilibrium position according to the intensity of these, and to the design characteristics of the platform ( 1). In general terms, the platform (1) will acquire a new equilibrium position by tilting a certain angle 0¡ _m (average angle of inclination of the platform) with respect to the vertical due to the action of the wind, and another certain angle 0 _{b / c} (platform roll / pitch angle (1)) at wave frequency around this new equilibrium position due to wave action. The direction of oscillation will be the wave incidence, which in the event that it is collinear with the wind (coming from the same direction), will have the same direction of the mean inclination (FIG 2A) and, in the event that they form 90 ° (FIG 3A) will oscillate perpendicular to the direction of the mean tilt.

When the floating offshore wind platform (1), substation or similar is in regular (or monochromatic) seas, formed by regular waves at a certain period, and in which the wind and waves are collinear (coming from the same direction) ( FIG 2A), the platform acquires its new equilibrium position (FIG 2B). The average heel associated to the overturning moment caused mainly by the wind (average inclination angle) will be canceled by generating a recovery moment (righting) transferring water from the Cs tanks to the Bs tanks (FIG 2C), which in this case act as anti-heeling tanks. Simultaneously, the pitching and rolling movements of the floating offshore wind platform (1), substation or similar due to the incidence of waves will be reduced by adjusting the height of the As tanks, which in this case act as anti-balance tanks. free surface liabilities, until reaching the effective period that dampens the roll movement of the platform due to the waves (FIG 2D). In order not to vary the draft, in the event that water has to be introduced (or otherwise removed) in the As tanks, it will be removed (or otherwise introduced) from the Bs tanks and Cs tanks in such a way that it does not modify the heel correction (FIG 2D).

If the wind and waves are still collinear (coming from the same direction), but the floating offshore wind platform (1), substation or similar is in a

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SUBSTITUTE SHEET (RULE 26) irregular sea (FIG 2E), sea formed by a very large number of regular waves with different periods, the tanks that act as free surface tanks (As tanks) will be more effective at some frequencies than at others. For this reason, these As tanks can be filled at different heights, so that the frequency range in which they are effective is greater, thus cushioning the balance of the platform due to the incident waves at different periods. Again, the tanks used to cancel the average inclination angle (Bs and Cs tanks) of the floating offshore wind platform (1), substation or similar, in addition to acting as tipping compensators (and having to transfer water between them) , they will have to adjust their level to avoid a variation in draft, or trim, produced by the action on the As tanks.

When the offshore wind floating platform, substation or similar is faced with the incidence of wind and misaligned waves, several of the tanks of the system to right and reduce the movements of the platform will have a double function, regardless of the type of sea. In FIG 3A a misalignment at 90 ° of the environmental conditions is schematized and in FIG 3B the equilibrium position reached. In this case (FIG 3C) the tanks Bs and Cs will cancel the average inclination by transferring water between them (from Cs to Bs), but one or more of them will reduce the pitch and roll movements by adjusting their height. filling, using for said adjustment water from tanks As, which is adequately supplied to all tanks Bs and Cs so as not to modify the mean inclination (FIG 3D). In this way, some of the Bs and Cs tanks will have the double function of canceling the mean bank angle caused by the wind (righting) and reducing pitch / roll movements caused by the incident waves, and the As tanks will act adjustment adjustment of ballast filling-emptying of the Bs and Cs tanks (to maintain draft), in addition to being able to help reduce pitch / roll movements due to wind turbulence.

In a general sea state composed of a wind sea (short crest swell, sum of multiple regular waves propagating in different directions) and one or more bottom seas (long crest swell, irregular and propagating sensibly in a single direction ) with different dominant periods, tanks (100) will be used to reduce pitch and roll movements due to swell. The procedure will be analogous to the previous cases, water will be transferred from some tanks (100) to others to cancel the average inclination and adjust the water level of the

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SUBSTITUTE SHEET (RULE 26) tanks (100) most effective against rolling and pitching movements.

The time scale in which the active system acts is slow compared to the passive correction, associated with the periods of the swell (usually a few seconds). Corrections for differences in the average inclination are mainly associated with variations in the average intensity of the wind, the value of which is reasonably constant for tens of minutes. The same happens to the active settings necessary to adapt the natural frequency of the tanks (100): the waves associated with a sea state have an energy spectrum that is reasonably constant over ranges of one or more hours. For this reason, once the water height has been adjusted, the passive operation, where the frequency of the movements of the water in the tanks (100) is a few seconds, can be in the environment of one or more hours. Therefore, the frequency of actuation of the active system is very low (hours) compared to that of the passive system (seconds).

The system to rightize and reduce the movements of floating offshore wind platforms (1), substations or similar is, therefore, a combined-simultaneous system that will contain at least three tanks (100), and in which at least two of those tanks (100) can act either actively, by transferring ballast, or passively, by moving their free surface after adjusting the height of the water.

For this, in a floating offshore wind platform (1), substation or similar, with the capacity to house liquid ballast and made of any material (s) capable of being used in a marine environment, a combined reduction system is configured. of pitch / roll movements and cancellation of medium inclination (FIG 5) whose objective is to increase the performance of the floating platform (1) in its operation and reduce the fatigue damage of the structural components and that: a) contains the least three ballast tanks (100) b) in which the transfer medium is at least one pump (102) that moves water from one tank to another, interchangeably, through a distribution of pipes that connect the tanks (104) , c) the transfer of water through the connecting pipes (104) between tanks is controlled with remotely operated valves (106),

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SUBSTITUTE SHEET (RULE 26) d) that contains a sensor subsystem, an actuator subsystem and a control subsystem that houses the logic modules and calculation algorithms whose resolution provides the necessary ballast distribution to automatically compensate the heel / trim, while achieving the damping of roll / pitch movements. The control subsystem will be housed in one or more computers. This division into subsystems serves merely a descriptive fact for the understanding of the present invention, not departing from the general scope, since the overall operation of the system is independent of said division into subsystems, and should therefore be considered as a simple example and this division is not restrictive.

The number of tanks (100) that make up the system to right and reduce movements of the platform (1) will depend on the type of structure and design conditions. Although with three tanks (100) it would only be possible to make a single adjustment that maintains the draft (for example, correcting only the trim and pitch), from three the possibilities of different adjustments are much higher. Although a greater subdivision is favorable by providing a greater number of degrees of freedom to achieve the combined objective, a high number of tanks (100) results in tanks of smaller dimensions (beam or length), which reduces the efficiency of the passive system when the efficiency depend greatly on the dimensions of the tank (100).

The procedure that, starting from an initial distribution of ballast, is used to obtain the transfer sequence and the final distribution of ballast in the tanks of the system that produces the compensation of the average angle of inclination and / or the damping of movements roll / pitch of the platform, attends the following phases (FIG 6):

1) The floating offshore wind platform (1), substation or similar is exposed to external agents, such as environmental conditions, which cause movements on the platform (1). Among the different induced movements, the ones that will be controlled by the system to right and reduce movements are list or trim (very low frequency, with characteristic periods of the order of tens of minutes derived from changes in average speed and / or wind and current direction due to the phenomena

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SUBSTITUTE SHEET (RULE 26) occur throughout a day), and roll / pitch movements induced by wave frequency (with characteristic periods of the order of 4 seconds to 30 seconds produced by windy seas and / or swells ).

2) In a first phase, the control strategy of the transfer sequence in the control subsystem is defined. This strategy determines when the transfer sequence must be activated and which optimization criteria must be followed for its calculation. The control strategy is defined by: a set of control parameters, activation laws of the system based on said parameters, and, at least, one objective function to optimize depending on the initial and final distributions of ballast in the tanks, of the transfer sequence with its corresponding intermediate ballast distributions in the tanks and the means to carry out said transfer. The control parameters will be at least four, a threshold mean inclination angle (0i _mU ) and a time range (ti) above which if the platform remains the system is activated to correct the platform inclination, and a period characteristic threshold (T _cu ) and a time range) above which if the difference in absolute value between the periods of water (Tu) of the ballast tanks (100) and the characteristic periods of the roll / pitch of the platform due to When the swell (T ₀ ) exceeds the value of the threshold characteristic period, the system is activated to modify the ballast height of the tanks (100) that will act as passive anti-balance tanks. The optimization of the objective function determines the final distribution of the ballast in the tanks of the system and the transfer sequence between them from an initial distribution of ballast, leading to correcting the mean inclination and / or simultaneously increasing the damping of the rolling movements and pitching, considering to achieve this goal minimize any of the following variables: energy consumption, the height of the center of gravity of the water in the tanks (thus maximizing the stability of the platform), the time to reach the final distribution of ballast, structural stresses in the wind turbine (4) and / or interference in its operation, roll and / or pitch movements, or some weighted combination of these. The choice of the control parameters and the objective function to be optimized for the transfer is carried out automatically by the control subsystem, which has defined criteria based on the operation, environmental conditions and the conditions of the wind floating platform. marine (1), substation or similar. For the choice of the control parameters and the

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SUBSTITUTE SHEET (RULE 26) The objective function is also contemplated the manual option, to be executed in exceptional or emergency cases, or the definition from a control center outside the platform.

3) In a second phase, data on the status of the platform (1) are taken through the sensor subsystem and transmitted to the control subsystem. The sensor subsystem is the set of sensors and transducers installed on the platform (1). Basically, these sensors will produce a digital or analog electrical signal that is taken to the control computer / res for processing. Depending on the type of sensor, more sophisticated or not, it may be that this signal is already conditioned or processed in some way. On the platform (1) there may be sensors that measure wind speed and direction (for example anemometers), current speed and its direction (such as current meters), sensors that measure the absolute wave height and serve to subsequently obtain the period (such as ultrasonic sensor or external buoy), a system that measures the instantaneous movements of the platform (1) (such as an inertial system), level sensors that measure the draft of the platform (1) and the level of water in each ballast tank (100) of the system. The transfer system will be monitored through the sensor subsystem, which will provide at least data to the control subsystem on the status of the pumps, status of the valves, flow and pressure in the system.

4) In a third phase, from the sensor subsystem data, the control subsystem calculates the average angle of inclination of the platform (1), the periods of water in the ballast tanks (100) derived from them and the characteristic periods of the roll / pitch of the platform due to the swell.

5) In a fourth phase, the activation of the system to right up and reduce movements is analyzed by comparing both the average angle of inclination of the platform (1) and the difference in absolute value of the periods of water in the ballast tanks (100) and the characteristic periods of the roll / pitch of the platform due to the waves obtained with the parameters of the control strategy, being:

• 0 µm is the mean angle of inclination of the platform (1) due to movements induced by external forces.

• ti the time used to calculate the mean inclination 0¡ _m

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SUBSTITUTE SHEET (RULE 26) • 0¡ _mu angle threshold average inclination (control parameter).

• T _ti the periods of the water in the ballast tanks (100) of the system to right and reduce movements.

• T ₀ the characteristic periods of the roll / pitch of the platform due to the waves.

• T _cu the threshold characteristic period (control parameter).

• Í2 the time used to calculate T ₀ .

If the mean tilt of the platform is less than or equal to the control parameter mean tilt threshold during a time range ti ya) The difference in absolute value between the characteristic periods of the roll / pitch of the platform due to swell T ₀ and the periods of the water in the ballast tanks (100) Your effective for roll / pitch damping during a time range t2 is less than or equal to the threshold characteristic period, then the system is not activated. That is: If 0 _im \ _ti £ 0 _imu and, in addition, \ T _U - T ₀ \ _tz £ T _cu for the ballast tanks (100) that are going to dampen the wave movements, the system is not activated. b) The difference in absolute value between the characteristic periods of the roll / pitch of the platform due to the swell T ₀ and the periods of the water in the ballast tanks (100) Tu effective for the damping of the roll / pitch during a range of time t2 is greater than the characteristic threshold period, then the system is activated by suitably modifying the height of the water in the ballast tanks (100) that will act as free surface tanks (FIG 4A) to dampen the roll / pitch movement produced by the wind and the swell. That is: If 0 _im \ _ti £ 0 _imu and, in addition, \ T _U - T ₀ \ _tz > T _cu for the ballast tanks (100) that are going to damp the wave movements, the system is activated to damp the balance /pitching.

If the average slope of the platform (1) is greater than the control parameter average slope threshold during a time range L and

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SUBSTITUTE SHEET (RULE 26) c) The difference in absolute value between the characteristic periods of the roll / pitch of the platform due to the swell T ₀ and the periods of the water in the ballast tanks (100) Tu effective for the damping of the roll / pitch during a range of time t2 is less than or equal to the threshold characteristic period, then the system is activated by transferring water between the ballast tanks (100) to compensate for the mean angle of inclination. That is: S¡ e _im \ _ti > 0 _imu and, in addition, \ T _U - T ₀ \ _tz £ T _cu for the ballast tanks (100) that are going to dampen the wave movements, the system is activated to compensate for the medium incline. d) The difference in absolute value between the characteristic periods of the roll / pitch of the platform due to the swell T ₀ and the periods of the water in the ballast tanks (100) Tu effective for the damping of the roll / pitch during a range of time t2 is greater than the characteristic threshold period, then the system is activated by transferring water between the ballast tanks (100) to compensate for the average inclination angle produced by the wind and by suitably modifying the water height of the ballast tanks (100) that they will act as free-surface tanks (FIG 4A) to cushion the roll / pitch movement produced by wind and waves. That is: if 0 _im \ _ti > 6 _imu and, in addition, \ T _U - T ₀ \ _tz > T _cu for the ballast tanks (100) that are going to dampen the wave movements, the system is activated to compensate for the inclination medium and roll / pitch damping simultaneously.

6) In a fifth phase, once the system to right and reduce movements of the platform (1) is activated in any of the previous ways, the final distribution of water in the tanks and the transfer sequence between them is calculated to perform the control action, optimizing the objective function defined in the first phase. To do this, based on the data on the status of the tanks (100) supplied by the sensor subsystem at the instant before the system was activated, if the objective compensation is: a) the damping of the roll / pitch of the platform, the ballast distribution in the tanks is calculated at the end of the transfer sequence, so that the difference in absolute value between the periods of surface oscillation

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SUBSTITUTE SHEET (RULE 26) free (FIG 4A) in the tanks (100) and the characteristic periods of roll / pitch of the platform due to the swell is zero, | T _ti - T ₀ I = 0, without modifying the average inclination of the platform. b) correction of the mean inclination angle, the distribution of water in the tanks at the end of the transfer sequence is calculated so that the mean inclination of the platform (1) is below the threshold mean inclination, that is, G _m £ 0¡mu without altering the damping action of anti-tank free surface balance was active. c) simultaneously damping roll / pitch and correcting the mean tilt angle, the water distribution in the tanks at the end of the transfer sequence is calculated, so that simultaneously, the difference in absolute value between the oscillation periods of the free surface (FIG 4A) in the tanks (100) and the characteristic periods of roll / pitch of the platform due to the swell are zero, | T _ti - T ₀ | = 0 and the mean slope of the platform (1) is below the threshold mean slope, that is, _{G, m} £ G, mu.

The distribution of ballast between the tanks of the system, carried out by a specific algorithm, determines for each tank its filling level and consequently its natural period of oscillation, which, together with its relationship with the water levels of the rest of the tanks of This system establishes whether the tank in question is acting as an anti-heeling tank, a free surface anti-balance tank, or simultaneously as an anti-heeling and anti-balance tank.

Depending on the number of tanks in the system, the interconnections between them and the transfer means available, the possible combinations of final ballast distributions between the different tanks and transfer sequences from an initial ballast distribution, which achieve the target compensation ( control action), can be very high, and therefore, the calculation of the final distribution of ballast and of the transfer sequence between the initial and final state is carried out based on the optimization of the objective function defined in the strategy control of phase 1, considering for this purpose to minimize: o the energy consumption of the transfer means. In this case, both the final ballast distribution and the transfer sequence are calculated

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SUBSTITUTE SHEET (RULE 26) imposing that the passage from the initial state to the final state is carried out with the minimum energy consumption. the height of the center of gravity of the water in the ballast tanks of the system in its control action, that is, to maximize the stability of the platform (1). In this case, both the final ballast distribution and the transfer sequence from initial to final state are calculated to achieve this end, for example by distributing the ballast as evenly as possible in height between the tanks. time to right and / or roll / pitch damping. In this case, the final distribution of ballast and transfer sequence from the initial state to the end, are calculated so that the righting and the damping functionality is carried out as quickly as possible with the transfer means that are available. minimize structural stresses on the wind turbine (4) and / or minimally interfere with its operation. In this case, the final distribution of ballast and the transfer sequence between the initial and final state is calculated so that both the angle of inclination and the damping during transfer are conducive to this end, for example, avoiding possible resonances with the turbine operation and extreme tilt angles during racking that could occur when correcting the average tilt of the platform in exceptional situations of changes in direction and intensity of the wind. roll and pitch movements due to swell. In this case, the final distribution of ballast and the transfer sequence between the initial and final state is calculated so that roll and pitch movements are reduced to the maximum, for example, by selecting the maximum number of tanks with the possibility of exercising. an anti-balance function compatible with the correction of the average inclination. a weighted combination of the above. In this case, starting from an initial distribution of ballast, the final distribution of ballast and the ballast sequence is chosen in such a way as to minimize the factored sum

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SUBSTITUTE SHEET (RULE 26) of the squares of the values that the objective functions take for a set of final ballast distributions and ballast sequences compatible with the objective compensation in mean bank and / or roll / pitch.

7) In a sixth phase, the control subsystem will order the actuator subsystem of the transfer means (pumps, valves) to carry out the defined transfer and the platform (1) will reach the new corrected position, thus returning to phase 3) of the procedure.

All this described process is automatic and is carried out completely in a matter of very few minutes, depending on the type of transfer sequence. This system to right and reduce movements will be integrated into the other systems of the platform (1) and can be monitored from the park control post / s, from where the control strategy of the transfer sequence can be modified according to to the required performance criteria.

This procedure, in addition to correcting the average inclination produced by the wind, is capable of correcting the inclination due to the flooding of at least one ballast tank (100) caused by a waterway, righting the platform (1) and maintaining the draft. In this embodiment, the system for righting and reducing the movements of a platform (1) will be connected to the outside (open loop) through at least one sea intake. The correction criteria are exactly the same as those set forth above, that is, threshold values are not exceeded. In this case, the complete flooding of one of the tanks (100) is detected through the tank level sensor (100) The control, upon detecting the flooding, will ballast accordingly the tanks (100) necessary to completely correct the flooding ; and simultaneously, it will dislodge ballast from the rest of the tanks (100) from the platform (1) through the sea intake, since when the flooding occurs, the draft increases. If the breakdown allows it, water will be reduced until the platform (1) emerges at the transport draft, to facilitate its transfer and repair. The criterion that defines this transfer sequence will be a weighted combination of the minimum righting time and the minimum height of the center of gravity (maximum stability) to guarantee the safety of the platform (1).

An open loop also allows modifying the depth of the platform (1), to vary

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SUBSTITUTE SHEET (RULE 26) the draft from transport to operation and vice versa.

If the system incorporates four tanks (100) or more, various combinations of tank fill (100) can be allowed that result in the same trim, list and draft. In this case, it is possible to move water from some tanks (100) to others to store potential energy without modifying the trim, list and draft. Thus, excess energy generated by the wind turbine (4) can be used. In times of lower generation, it is possible to take advantage of the stored energy if a generator that takes advantage of the waterfall is incorporated.

This procedure can also correct the roll and pitch movements by using at least one tank with a “U” shape (FIG 4B), consisting of two vertical columns communicated by its lower part and which, thanks to its design, allow the Oscillating movement of the mass of water contained in them at a period and phase such that an oscillating moment is generated opposite to the roll / pitch of the platform whose period is independent of the average difference between them. The period of oscillation of the water in the tank will depend on the design and the filling of the tank.

Additionally, the signals from the wind turbine as a whole and its subsystems can be used, which, among others, measure or estimate the thrust and aerodynamic torque, the operation and supervision status (alarms, warnings), the revolutions, the structural forces, accelerations. , etc., and these are taken into account in the optimization of the objective functions.

In an informative and never limiting manner, some examples of preferred embodiment for the system associated with the process of the present invention are shown below.

Examples of floating offshore wind platforms (1), substations or the like in which the present invention is applied are shown in Figure 1A and 1B. The floating body 1 can have any type of shape as long as it is hollow to be able to contain inside at least the tanks that make up the system to right up and reduce movements, although for generality it has been represented as a cylinder / cylinders. The floating body / s (1) has a transition piece (2), a tower (3) and a wind turbine (4). The wind turbine (4) illustrated has a horizontal, downwind or upwind axis, and can also be a vertical axis, and where the number of blades

2. 3

SUBSTITUTE SHEET (RULE 26) it can be anyone. The floating body (1) can have both a wind turbine (4) that is centered or off-center in the floating body (1) or in the set of floating bodies (1). The floating body (s) (1) will be fixed to the seabed (7) by means of an anchoring system (5) whose characteristics (catenary, semi-rigid, rigid ...), materials (chain, cable ,. ..), layout (1, 2, 3, 4 ... lines) and type of anchor (type of anchors, type of platform anchors ...) will be according to the type of solution. The floating body (s) (1) can be completely submerged below the water line (6) or partially. Additionally, the floating body (s) (1) can serve to support electrical substations or the like. In that case, the wind turbine (4), the tower (3) and the transition piece (2) would be replaced by the relevant upper modules (topsides).

An example of an offshore wind platform (1), substation or the like subjected to the collinear action of wind and waves is shown in figure 2A. The wind incident on the platform formed by a floating body (1), a transition piece (2), a tower (3), a wind turbine (4) and an anchoring system (5) produces a thrust that makes the tower (3) forms an average inclination angle (0im) with respect to the vertical. If, in addition, the waves are incident in the same direction, to this average tilt angle (0im) is added the roll / pitch angle (0c / b) that will oscillate in one direction and the other due to the forces of the waves. In figure 2B, a generic distribution of tanks of the system is shown in plan and elevation to right and reduce movements before making corrections with the system. When the wind hits, figure 2C, there is a heeling moment that tilts the platform in such a way that the tanks C1 and C2 sink further, and the waves generate an oscillatory movement in the direction of their action, causing the unit to oscillate at the frequency of this. In this case, the movement reduction system transfers water from the Cs tanks to the Bs tanks to generate a recovery moment that opposes the heeling moment produced by the wind and, simultaneously, it will adjust the height of the As tanks so that they produce, due to the movement of its free surface (figure 4A), an anti-balance moment that counteracts the balance of the platform due to the swell. Adjusting the height of the As tanks is achieved by transferring ballast from the Bs and Cs tanks to the As tanks, in such a way that the righting moment produced by the Bs and Cs tanks is not modified. When the sea is regular, the height in the tanks that act as movement reducers through the principle of free surface will be the same, as seen in figure 2D. This is because in a regular sea the

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SUBSTITUTE SHEET (RULE 26) swell has a single frequency, which requires the same height in the tanks. However, when the sea is rough, this height can vary between tanks to cover more periods of swell. In such a case, one tank A will increase its water level and the other tank A will reduce it, compensating for the spin that this change produces by a movement of water from one tank C to the other tank C, as shown in figure 2E, and / or from tank B to the other B.

An example of an offshore wind platform, substations or the like subjected to the action of wind and waves at 90 ° is shown in figure 3A. The wind incident on the platform formed by a floating body (1) a transition piece (2), a tower (3), a wind turbine (4) and an anchoring system (5) produces a thrust that makes the tower (3) form a mean tilt angle (0im) with respect to the vertical. The wave acts perpendicularly, causing a roll / pitch angle (0c / b) that will oscillate with different magnitude and direction due to the onslaught of the waves. In figure 3B, a generic distribution of tanks of the system is shown in plan and elevation to right and reduce movements before making corrections with the system. When the wind hits the unit, Figure 3C, a heeling moment occurs that tilts the platform so that the tanks Cs sink further. The swell, for its part, generates an oscillatory movement in the direction of its action (whereby the Ace tanks move up and down alternately). In this case, the movement reduction system transfers water from the Cs tanks to the Bs tanks to generate a recovery moment that opposes the heeling moment produced by the wind. And, simultaneously, to correct the oscillatory movement caused by the waves, figure 3D, the tanks A will function as adjustment of the ballast filling-emptying of the tanks Cs and Bs, whose height, and therefore their period of oscillation, can be adjusted to act as free surface anti-balance tanks, in such a way that their anti-heeling action and operating draft are not modified, that is, the Cs and Bs tanks act simultaneously as anti-heeling tanks (in the direction of the wind). ) and anti-balance (in the direction of the waves). In addition, the height level of the As tanks could be adjusted (playing with the other tanks as much as possible) to reduce movements associated with wind turbulence / variability.

An example of a free surface tank is shown in Figure 4A. The water moves from side to side of the tank, the natural oscillation frequency depending on the height

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SUBSTITUTE SHEET (RULE 26) of the water in the tank, as well as its dimensions and shape. By adjusting the natural frequency of the tank to a certain value and exciting it near its resonance, the wave front (the movement of the free surface) opposes a dynamic moment that reduces the roll / pitch movement. The invention has been described with reference to specific cases, and of a single floating body (1), without departing from the general scope of the invention as defined in the appended claims. For this reason, the specification and hence the drawings are not restrictive or limiting and should be considered as an example.

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SUBSTITUTE SHEET (RULE 26)

Claims

1- Procedure to reduce the average inclination and reduce the movements of a floating offshore wind platform (1), substation or similar characterized by:

• detect, at least, wind speed, wind direction, wave height, wave period, platform tilt angles, draft, and water level of ballast tanks.

• compare that: o the platform mean tilt angle (0¡ _m ) during a time range ti is less than or equal to the threshold mean tilt angle

(0mu)

^ im \ t ₁ - imu or the difference in absolute value between the characteristic periods of the roll / pitch of the platform due to the swell (T ₀ ) and the periods of the water of the ballast tanks (Tu) effective for the damping of the balance / pitch over a time range) is less than or equal to the threshold characteristic period (T _cu ).

\ ^T ti ^{~ T} o \ t ₂ <Tcu P ^ara l ° ^s ballast tanks will dampen the movements of the waves.

• at least one objective function of the transfer sequence control strategy, which may be to minimize: the energy consumption of the transfer means, the height of the center of gravity of the ballast water in the tanks of the system, the time to right and / or damp roll / pitch, structural stresses on the wind turbine and / or minimally interfere with its operation, roll and pitch movements due to waves, or a weighted combination of the above.

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SUBSTITUTE SHEET (RULE 26) • Transfer water between the ballast tanks when any of the previous comparisons is greater than the threshold values, ensuring that the final ballast distribution and the transfer sequence are carried out according to the optimization of the objective function, for: or compensate, by means of the anti-heeling tank principle (active system), the average angle of inclination produced by the wind. o and / or damping, by means of passive anti-roll tanks, the roll / pitch movement produced by wind and waves.

2- Procedure of claim 1-, where the ballast is in an open loop system, allowing the tanks to be filled / emptied with water from outside.

3- Procedure of claim 2-, where water is transferred between the ballast tanks of the system to compensate for the average inclination angle produced by the flooding of at least one of the tanks caused by a waterway and simultaneously the increase is corrected draft caused by the flood shedding other tanks from the platform.

4- Procedure of claim 1-, where water is transferred between the ballast tanks of the system to store excess energy as potential energy in the tanks.

5- Procedure of claim 2-, where water is transferred between the ballast tanks of the system to store excess energy as potential energy in the tanks. 6- Procedure according to any of the preceding claims, where the passive compensation is also obtained by the oscillation of water in a tank with a “U” shape, consisting of two vertical columns communicated by its lower part.

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SUBSTITUTE SHEET (RULE 26) 7- Procedure according to any of the preceding claims, where the control strategy of the transfer sequence is modified according to the operating criteria required for more than one platform within one or more wind farms.

8- Procedure according to any of the preceding claims, where signals are received from the wind turbine as a whole, which measure or estimate the thrust and aerodynamic torque, the state of operation and supervision, the revolutions and the structural efforts, and these are taken into account in the optimization of the objective functions.

9- Computer-readable data carrier comprising instructions that, when executed on a computer, cause the computer to carry out the steps of any of the procedures of the preceding claims to reduce the average inclination and reduce the movements of a platform floating offshore wind (1), substation or similar.

10- System to reduce the average inclination and reduce the movements of a floating offshore wind platform (1), substation or similar that makes claim 1 characterized by:

• a control configured to perform this procedure,

• at least three ballast tanks,

• at least one pump that moves water from one tank to another, interchangeably, through a distribution of pipes connecting the tanks,

• that the transfer of water through the connecting pipes between tanks is controlled with remotely operated valves.

11. System according to claim 10- and that performs the procedure of claim 2-, where the system is connected to the sea through at least one sea outlet.

12- System according to claim 10- and that performs the procedure of claim 3-, where the system is connected to the sea through at least one sea outlet.

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SUBSTITUTE SHEET (RULE 26) 13. System according to claim 10- and that performs the procedure of claim 4-, where there is an energy generator driven by at least one turbine that takes advantage of the waterfall and at least four ballast tanks.

14- System according to claim 11- and that performs the procedure of claim 5-, where there is an energy generator driven by at least one turbine that takes advantage of the waterfall and at least four ballast tanks.

15. System according to any of claims 10- to 14- and that performs the procedure of claim 6-, where there are anti-balance tanks arranged in a "U". 16. System according to any of claims 10- to 15- and that performs the procedure of claim 7-, where the system control is monitored at the park control post / s.

17- System according to any of claims 10- to 16- and that performs the procedure of claim 8-, where the control system receives signals from the wind turbine assembly, which measure or estimate the thrust and aerodynamic torque , the state of operation and supervision, the revolutions, the structural forces, and uses them in the optimization of the objective function.

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SUBSTITUTE SHEET (RULE 26)