FR3053741A1 - SYSTEM FOR STORING AND GENERATING ELECTRIC ENERGY BY GRAVITY THROUGH IMMERSIONABLE LESTS - Google Patents

Abstract

The present invention relates to a system for storing and producing electrical energy deployed in a volume of water, said system comprising a platform, at least one ballast placed on the bottom of the volume of water, a lifting system in able to move said ballast between a first elevation position and a second elevation position, and a remotely controlled coupling device coupled to the lift system and configured for tracking and coupling to said at least one ballast on the bottom of the water volume, said lifting system selectively raises and lowers said at least one ballast when coupled to said remote controlled hooking device, from the first lift position to the second position elevation, said system stores and releases energy when said at least one ballast moves between the first elevation position and the second elevation position. Said system comprises a controlled adjustment device of the length and the tension of the traction cable making it possible to ensure the continuity and the smoothing of the consumption / electricity production of the installation.

Description

Field of the invention

The present invention relates to the field of storage and return of electrical energy by the immersion of ballasts from a maritime platform.

Such storage systems can be used, for example, to store energy generated by renewable sources (wind, solar photovoltaic, ...) during "off-peak" periods during which the energy demand is less than l energy produced and returned during “peak” periods when energy demand is greater than the energy produced, or for the establishment of a large energy reserve.

State of the art

The international patent application WO 2014160522 describing a system for storing and releasing energy is known in the state of the art. This system, deployed in a volume of water, comprises a platform, at least one ballast placed on the bottom of the volume of water, a lifting system able to move said ballast between a first elevation position and a second elevation position, and a remotely controlled hooking device coupled to the lifting system and configured for tracking and coupling to said at least one ballast on the bottom of the volume of water, said lifting system lifts and selectively lowers said at least one ballast when coupled to said remotely controlled hooking device, from the first elevation position to the second elevation position, said system stores and releases energy when

-2said at least one ballast moves between the first elevation position and the second elevation position.

Disadvantages of the prior art

Although the solution described in international patent application WO 2014160522 makes it possible to respond very flexibly to the needs for storage and restitution of electrical energy both for short cycles of a few hours and for long cycles of several weeks or even a few months, it appears that improvements can be made to optimize its operation and improve some of its components. One of the challenges is related to the elasticity of the traction cable used for raising and lowering the weights. This elasticity disturbs the movement and the positioning accuracy of the attachment device, in particular during the attachment or detachment phases of the ballast. This elasticity also generates variations in tension in the traction cable which are liable to disturb the operation of the motor / generator.

Another production / consumption in the troughs during the challenge phases resides in the transition of ballast electricity. For example, the transition phase of a ballast in the high position includes its attachment by the attachment device, then its begins its descent.

acceleration when

Another challenge concerns the autonomous operation of the energy source of the ballast attachment device, its exhaustion being able to cause losses in productivity.

Finally, this type of system includes components that can be motor / generator can be configured prior art improved: the according to a

-3 particular characteristic allowing to optimize the choice of the material of the cable of traction and thus to decrease its cost and its elasticity; ballast can be designed to reduce its cost; the platform can be designed to optimize its security and preserve its integrity in extreme weather conditions.

Solutions provided by the invention

In order to respond to these drawbacks, the invention relates, in its most general sense, to a system for storing and producing electrical energy deployed in a volume of water, said system comprising a platform, at least one ballast placed on the bottom of the water volume, a lifting system able to move said ballast between a first elevation position and a second elevation position, and a remotely controlled hooking device coupled to the lifting system and configured to for the purpose of locating and coupling said at least one ballast to the bottom of the volume of water, said lifting system selectively raises and lowers said at least one ballast when it is coupled to said remotely controlled hooking device, from the first elevation position to the second elevation position, said system stores and releases energy when said at least one ballast moves between the first elevation position tion and the second elevation position, characterized in that it comprises an adjustment device controlled by the length and the tension of the traction cable, making it possible to ensure continuity and smoothing of the consumption / production of electricity of the installation as well as the compensation of the movements of the ship in case of swell for example.

Advantageously, said device for adjusting the length and the tension of the traction cable is constituted by a pulley system, the spacing of which is

-4adjustable by any mechanical and / or hydraulic and / or pneumatic means.

According to a variant, said adjustment device controlled by the lengthener and by the tension of the traction cable is controlled by an electronic circuit receiving a signal representative of the submerged length and of the tension of the cable.

Said device for adjusting the length and the tension of the traction cable makes it possible to offset the transition phases of the ballast over one another over time. It can also for example play the role - at least partially - of a swell compensator or be coupled to a swell compensator. It can also be used, for example, to modulate the speed of the lifting system independently of the speed of descent of the weights when the generator is hooked to the network.

According to an advantageous embodiment, said attachment device comprises at least one autonomous energy recharging system, which avoids having to reassemble the attachment device in the event of exhaustion of the on-board energy source.

According to a first variant, said autonomous energy recharging system consists of a hydro generator.

According to a second variant, said autonomous energy recharging system is constituted by a pneumatic system actuated by the variation of the pressure of the water as a function of the depth.

According to a particular embodiment, said attachment device consists of two parts, one remaining attached to the traction cable and the other mobile.

According to an advantageous embodiment, the installation comprises at least one buffer storage device and an activation algorithm for said buffer storage device, taking into account reference values in power and / or energy.

According to a first variant, said buffer storage device consists of an additional ballast coupled to a reversible electric machine.

According to a second variant, said buffer storage device consists of an electrochemical battery.

According to a third variant, said buffer storage device consists of a thermal storage system.

According to a fourth variant, said buffer storage consists of a flywheel storage system.

According to a fifth variant, said buffer storage consists of a compressed air storage system.

According to an advantageous embodiment, said at least one ballast is designed so as to reduce the quantities of expensive materials and maximize the use of dense and inexpensive materials.

According to an advantageous embodiment, said at least one ballast is surrounded by a buoy formed by a closed envelope of hydrodynamic shape fulfilling the function of passive or active ballast.

According to an advantageous embodiment, said platform is formed of two complementary units, one fixed designed to withstand storms and comprising the storage system for surface weights and the attachment point

-6 of the submarine electrical cable for connection to the terrestrial electrical network, the other mobile designed to be moved to the shelter in the event of a storm and comprising the ballast lifting system, the generator and the electrical systems.

Detailed description of nonlimiting examples of embodiment of the invention

The present invention will be better understood on reading the description which follows, referring to a nonlimiting example of embodiment illustrated by the appended drawings where:

- Figure 1 shows a perspective view of a first example of a fastening system according to the invention

- Figure 1a shows a schematic view of another example of a fastening system according to the invention

Figures 2 to 5 show a schematic view of the operation of the system in storage mode

Figures 6 to 9 show a schematic view of the operation of the system in electrical production mode

- Figure 10 shows an example of a ballast according to a variant of the invention in transparent perspective

- Figures 11 and 12 show a variant of ballasted ballast, respectively in vertical section and face downward

- Figures 13 and 14 show a variant of the system.

-7 BODY HANGING SYSTEM (1) fitted with latch (2)

Figure 1 shows an example of a hanging device. The hanging device is formed by a hook or any other system and hung on the end of a cable (3). This device makes it possible to secure the body (1) to the ballast, or on the contrary to dissociate it, for example to abandon said ballast on the seabed, or on the contrary to hang it on the platform.

The body (1) is heavy to act as a counterweight to facilitate the descent of the traction cable when no ballast is attached to it. It is provided with two adjustable groups (4, 5), comprising a reversible electric machine. This reversible electric machine is used for the self-guided movement of the body (1) when it is supplied by a battery housed in the body (1). It is then controlled by a system for locating a ballast to be recovered, housed in the body (1).

This localization system delivers signals to a device for controlling the two adjustable groups (4, 5). When approaching the ballast, it controls the passage of these groups in engine mode (propulsion). Otherwise, these groups (4, 5) pass for example in generator mode to recharge the battery housed in the body (1).

Figure 1a shows another configuration, in which the counterweight and attachment device functions are provided by two separate components: the support cage (20) and the attachment system (21). The support cage (20) remains attached to the traction cable and is heavy in order to provide the counterweight function of the hooking device. The support cage also serves to accommodate the attachment system (21) for the phases of

-8 up and down weights. The attachment system (21) is mobile in three dimensions, energy independent and always remains linked to the support cage by means of a flexible leash (22) which can be rolled up / unrolled. It includes the hook for attaching to the weights (23) and a system for attaching (24) to the support cage. In order to hang a ballast resting on the seabed, the hooking system (21) comes out of the support cage (20) and approaches then hooks to the ballast using the fastening system (23). The leash (22) is then rolled up, which has the effect of bringing the support cage (20) closer until the latter attaches to the attachment system (21) using the clip (24). The ballast can then be raised.

PILOT ADJUSTING DEVICE FOR THE LENGTH AND TENSION OF THE TRACTION CABLE

Figures 2 to 5 show a schematic view of the device for adjusting the length and tension of the traction cable in electricity storage mode and Figures 6 to 9 show a schematic view of this same device in production mode d 'electricity.

The platform comprises a reversible electric machine coupled to a traction system (10) for the cable (3).

In this configuration, the system comprises two systems (11, 12) for compensating the length of the cable, using pulleys with variable spacing on each side of the traction system (10). The variation of the pulley spacing can be achieved by any mechanical and / or hydraulic and / or pneumatic means.

Storage mode (figures 2 to 5)

When a ballast (101) goes up, the length compensation systems (11, 12) release their entire length

-9 of cable so that the total length of submerged cable is greater than the depth of the water column (Figure 2).

Once the opposite latching system (2 _R ) reaches its target elevation position (15), the length compensation system (12) located on the side of the latching system (2 _L ) alone stores the surplus of length to allow the continuation of the ascent of the attachment system (2 _L ) and the ballast (101). This allows, while the ballast (101) still going up, to hook another ballast (102) on the opposite maneuver side without interrupting the ascent of said hooking system (2 _L ) and said ballast ( 101).

Once the opposite ballast (102) is hooked, the ballast (101) completes its ascent and reaches its target elevation position (16). The total length of submerged cable is then equal to the depth of the water column (Figure 3).

The ballast (102) which has just been hooked then begins its ascent and simultaneously the length compensation system (11) located on the side of the ballast (101) having reached its target elevation position (16) begins to store the length of cable allowing said ballast (101) to be held stationary for the maneuver of its stall while the ballast (102) continues to climb

Once said ballast (101) off the hook, the two length compensation systems (11, 12) have then stored cable to the maximum of their capacity. The total length of submerged cable is then less than the depth of the water column (Figure 4).

The ballast (102) continues its ascent and the attachment device (2 _L ) located on the opposite side begins its descent.

The two length compensation systems (11, 12) then release their entire length of cable before the ballast (102) has hooked (2 _L ) completed its ascent. The device located on the opposite side thus descends more quickly than the ballast rises (102), which allows said hooking device (2 _L ) to start the maneuver for hooking a new ballast (103) while the ballast (102) is still going up (Figure 5).

The operation is repeated until all of the weights are transferred from the second elevation position to the first elevation position.

Production mode illustrated by Figures 6 to 9:

When a ballast (111) descends, the length compensation systems (11, 12) store the maximum possible cable so that the total length of submerged cable is less than the depth of the water column (Figure 6).

Once the opposite latching system (2 _R ) reaches its target elevation position (16), the length compensation system (12) located on the side of the latching system (2 _R ) alone releases the length of cable to allow the continuation of the descent of the attachment system (2 _l ) and the ballast (111) hung on the other side. This allows, while the ballast (111) always descends, to carry out the hooking maneuver of another ballast (112) on the opposite side without interrupting the descent of said hooking system (2 _L ) and said ballast (111 ).

Once the ballast (112) is hooked, the ballast (111) finishes its descent and reaches its target elevation position (15). The total length of submerged cable is then equal to the depth of the water column (Figure 7).

-11 The ballast (112) which has just been hooked then begins its descent and simultaneously the length compensation system (11) located on the side of the ballast (111) having reached its target position (15) begins to release the length of cable allowing said ballast (111) to be kept immobile for the maneuver of its stall while the opposite ballast (112) continues its descent.

Once the opposite ballast (111) is unhooked, the two length compensation systems (11, 12) are at their minimum capacity. The total length of submerged cable is then greater than the depth of the water column (Figure 8).

The ballast (112) continues its descent and the attachment device (2 _L ) located on the opposite side begins its ascent.

The two length compensation systems (11, 12) then store the cable length to the maximum of their capacity before the ballast (112) has completed its descent. The hooking device (2 _L ) located on the opposite side thus rises faster than the ballast descends (112), which allows said hooking device (2 _L ) to start the hooking maneuver of a new ballast (113) while the ballast (112) is still going up (Figure 9).

The operation is repeated until all of the weights are transferred from the first elevation position to the second elevation position.

NATURE OF CABLES

Steel traction cables are more durable and less expensive than the cyclic use cables provided in the synthetics for this invention.

However, they have the disadvantage of having a density approximately seven times higher than the traction cables.

-12 synthetics. The variation in their mass induced by the variation in their suspended length can cause a consequent variation in the speed of descent or ascent of the ballast. The use of a variable speed generator / motor makes it possible to adjust the lowering speed of the weights as a function of the depth in order to compensate for the variation in mass caused by the suspended weight of the traction cable.

This variant requires varying the speed of descent of the weights in order to maintain a constant production power (or consumption) throughout the descent (ascent) despite the weight variation due to the suspended length of cable.

The variation in the ballast descent speed can be controlled by power electronics on the generator / motor side.

REALIZATION OF THE BALL

In order to reduce the cost of manufacturing weights capable of reaching great depths without degradation while having a hydrodynamic profile and a total mass which can approach 1000 tonnes, a particular variant of the invention relates to a specific structural design consisting in limiting the quantities expensive materials (for example by choosing a steel and synthetic fiber structure) by maximizing the quantities of heavy and inexpensive materials (for example unreinforced concrete).

Figure 10 shows an example of such a ballast.

To this end, the mass of heavy material (unreinforced concrete) is supported by a metal shell (30) made of steel (or other structurally resistant material) connected to the attachment point (36) by a network of guy wires (31 to 35) made of synthetic fibers and / or metal. The mass of concrete (37) envelops

-13 shrouds (31 to 35) which can either be embedded in the concrete (37), or located inside sheaths in the concrete. The concrete itself can be covered with a waterproof polymer coating to allow better resistance under very high pressure.

This variant relates to an unballasted ballast. It is therefore the platform that must be ballasted in order to compensate for the variation in total mass due to the variable number of weights that it must support.

BALLASTED BALLAST

Another variant for the construction of the ballast consists in building a ballast (passive or active) associated with each ballast.

The variant shown in Figures 11 and 12 consists in wrapping the ballast (40) with a buoy formed by a closed envelope (41) of plastic material which may be flexible or other material. The buoy (41) can be emptied and filled from below (passive ballast) or else equipped with a valve allowing air filling and / or emptying from above (active ballast).

The buoy (41) is hydrodynamically shaped and is attached to the ballast over its entire vertical surface, thus minimizing the ballast / buoy tension per unit of surface. Contact between the two can be ensured either:

• By gluing, and / or • By numerous roughness on the external surface of the ballast, and / or

-14 • By designing the ballast a little thicker at the top than at the bottom, thus creating a “V” ensuring permanent contact between the ballast and the buoy.

The external profiled buoy (41) shown in FIG. 18 can also be adapted to offer a potential role of "fender" between ballasts on the surface or at depth.

ENERGY BUFFER STORAGE

Compensation for system production / consumption dips can be done by buffer energy storage sources.

These energy buffer storage sources can be in particular:

• Electrochemical batteries: a maximum power and a minimum power are defined to activate the charging and discharging of the batteries in order to smooth production and consumption at the outlet of the installation, • A thermal storage system, • A storage system by flywheel, • A compressed air storage system, • one or more lifting system (s) dedicated to smoothing production / consumption. The raising and lowering of these weights from this system (s) makes it possible to fill the production / consumption gaps.

MODULAR PLATFORM

Another variant illustrated by FIGS. 13 and 14 consists in making a modular platform, formed of several complementary units:

- The first unit (50) includes the ballast lifting system (52), the generator (53) and the electrical systems.

- The second unit (51) comprises the system for storing ballast on the surface, and constitutes the point of attachment of the electric cable (54) connecting the coast.

In the event of a storm or very heavy sea, the first unit (50) can be brought back to a protected area (eg a port, a leeward shore) either by its own motorization or by towing. The second unit (51) remains offshore but, equipped with ballasts, it can possibly be positioned below the surface to a depth sufficient to escape the force of the waves and the wind.

The objective is to be able to protect storage systems in the event of a storm.

The unit (50) containing all the electricity production systems is the most sensitive to the effects of the storm. Smaller than the storage platform (51) proper, it can therefore be moved more easily. The other unit (51) contains few electrical systems (ballast supply, and network connection cable) which can be made completely watertight to a depth sufficient to minimize the effects of heavy seas on the surface.

- The first unit (50) can move - and can therefore be akin to a ship.

-16- the second unit (51) is not designed to move, but to occupy a large modular space offshore, of a size sufficient to be insensitive to the movement of waves and, if necessary to be immersed in a depth to reduce the influence of waves.

• In normal mode, the two units are securely moored and constitute only one system.

• A high voltage cable decoupling system (54) is implemented when the two units are separated.

Claims (14)

Claims 1 - System for storing and producing electrical energy deployed in a volume of water, said system comprising a platform, at least one ballast (52, 101 to 103, 111 to 113) placed on the bottom of the volume d , a lifting system (10) capable of moving said ballast between a first elevation position and a second elevation position, and a remotely controlled hooking device (2) coupled to the lifting system and configured for the purposes of locating and coupling to said at least one ballast on the bottom of the volume of water, said lifting system selectively raises and lowers said at least one ballast when it is coupled to said remotely controlled hooking device , from the first elevation position to the second elevation position, said system stores and releases energy when said at least one ballast moves between the first elevation position and the second elevation position, characterized in what it includes a device (11, 12) controlled adjustment of the length and tension of the traction cable to ensure continuity and smoothing of the consumption / production of electricity of the installation. 2 - electrical energy storage and production system according to the preceding claim characterized in that said means (11 12) controlled adjustment of the length and tension of the traction cable (3) is constituted by a system with pulleys whose spacing is adjustable by any mechanical and / or hydraulic and / or pneumatic means controlled by an electronic circuit receiving a signal representative of the length and the tension of the cable. 3 - electrical energy storage and production system according to claim 1 characterized in that said attachment device comprises at least one autonomous charging system. -184 - Electric energy storage and production system according to the preceding claim characterized in that said autonomous recharging system consists of a hydro generator ( 4, 5). 5 - Electric energy storage and production system according to claim 3 characterized in that said autonomous charging system is constituted by a pneumatic system actuated by the pressure variation as a function of the depth. 6 - Electric energy storage and production system according to claim 1 characterized in that it comprises at least one energy buffer storage system and an electronic circuit for controlling the electric machine according to a reference value of power or energy to be stored or returned. 7 - An electrical energy storage and production system according to claim 6 characterized in that said buffer energy storage system uses compressed air. 8 - electrical energy storage and production system according to claim 6 characterized in that said buffer storage system uses at least one flywheel. 9 - electrical energy storage and production system according to claim 6 characterized in that said buffer storage system is thermal storage. 10 - electrical energy storage and production system according to claim 6 characterized in that said buffer storage system is an electrochemical battery. -1911 -Electric energy storage and production system according to claim 6 characterized in that said buffer storage system consists of an additional ballast coupled to a reversible electric machine. 12 - electrical energy storage and production system according to claim 1 characterized in that said at least one ballast consists of a heavy mass of concrete or other dense material, supported by a steel shell or other structurally resistant material , connected to the attachment point by a network of guy wires (31) made of synthetic fibers and / or metal which pass through the heavy mass. 13 - electrical energy storage and production system according to claim 1 characterized in that the ballast is surrounded by a buoy formed by a closed envelope of hydrodynamic shape made of plastic material which can be flexible or other material, which can be emptied and filled from below (passive ballast) or fitted with a valve for filling and / or emptying air from above (active ballast). 14 - electrical energy storage and production system according to claim 1 characterized in that the platform is modular, formed of two complementary units, the first being fixed and comprising the storage system of surface weights, and constitutes the point for attaching the electrical cable connecting the coast, the other being mobile and comprising the ballast lifting system, the generator and the electrical systems. 15 - electrical energy storage and production system according to claim 1 characterized in that said attachment device consists of two components, one remaining attached to the traction cable and playing the role of counterweight and cage- support for the second component, which is mobile and autonomous energetically and -20 linked to the first using a leash that can be rolled up / unrolled and with the grapple attaching to the weights. 2/7