Floating hydroelectric power plant for waterways and maintenance procedure for such a power plant

Abstract

Floating hydroelectric power plant for watercourses and method of maintenance of such a power plant Floating hydroelectric power plant, intended to be partially immersed in a watercourse, comprising a flotation device (10) comprising at least two hulls (12) coupled by a frame (14) comprising a floor (15) extending in a principal plane (B), and, for each hull (12), a connecting element (30 to 33) connecting the hull (12) to the floor (15);a channel (20) comprising two turbines (36) mounted counter-rotating about two axes of rotation (X, X') respectively, together defining a secondary plane (C), and telescopic slides (50, 51), each telescopic slide being located entirely below the main plane (B) and connecting one of the connecting elements of the frame (14) to the channel (20), the telescopic slides being configured to allow translation of the channel (20) along a direction (Z) perpendicular to the main plane (B), so that an upper face (FS) of the channel (20) remains below the main plane (B). Figure for the abstract: Fig.1;

Description

Title of the invention: Floating hydroelectric power plant for waterways and method for maintaining such a power plant. Technical field

[0001] The present invention relates to floating power plants for waterways, and more particularly for shallow rivers. STATE OF THE ART

[0002] Floating hydroelectric power plants, hereafter referred to as floating tidal turbines, usable in shallow rivers (for example, between 2 m and 4 m), as well as in rivers with moderate velocities, but nevertheless exceeding 1.5 m / s, can be deployed at numerous sites. Such tidal turbines have the advantage of being able to meet the electrical energy needs of off-grid sites, in Europe because they are difficult to access or isolated, and in developing countries due to incomplete electrification networks. Conversely, the target power outputs range from a few hundred watts to around twenty kilowatts, corresponding to the upper limit defining picoelectricity.

[0003] Some tidal turbines have an above-water platform and are attached by various mooring lines (rope, cable, chain, etc.) to any fixed device on the bottom of a river or to pre-existing land-based structures such as bridge piers on said river. They differ from many variants of river turbines without a platform, which are also called floating turbines. Indeed, although these variants have components that ensure buoyancy greater than one, they are kept completely submerged, at a depth and orientation controlled by more or less complex systems that generally include ballast tanks, filled or emptied of surrounding water, as in US patent 2010327583. These tidal turbines, designed to be completely submerged, are designed for significant depths, whether in rivers or tidal currents.They differ conversely from hydro turbines where the turbine is positioned close to the water surface as in patent US2007020097, or even crossing the water surface, as in patent DE102011084017A1.

[0004] Finally, some floating hydro turbines of the prior art are poorly suited to shallow rivers, because they do not satisfy the following two constraints: a. the available resource being modest, it is advantageous that the architecture of the turbomachine (i.e. a device comprising one or more turbines) adapts to the section of the shallow watercourse and its low speed; It is therefore desirable to locally accelerate the flow near the turbine via fairings while respecting the flattened wetted section of the river; b. It is also important that the generator not occupy a high position above the floating platform, as is the case in patent application CA2696758, because in operation, the following disadvantages arise: loss of maneuverability in hard-to-reach locations, visual pollution, and the possibility of vandalism. It is therefore preferable that the platform be as unobstructed as possible.

[0005] Realistic solutions have been proposed in the power plant disclosed in patent application EP3707371 to satisfy these two constraints. However, this power plant, as with all other prior art power plants, presents problems, particularly those related to the maintenance of the components of a hydro turbine. For example, current hydro turbines may be deficient in terms of easily performing basic on-site maintenance on the turbines and their drive unit. Furthermore, for major repairs, these hydro turbines are difficult to tow by riverboats to a maintenance or repair site on the shore, which may be shared by an entire array, and then to be repositioned just as easily in the river.

[0006] To ensure optimal conditions for intervention on the platform, several turbine lifting / repositioning systems exist for carrying out necessary maintenance operations. One example is French patent application FR3079002, which discloses a tidal turbine equipped with floats, a propeller supported by a mast, and a hydraulic cylinder allowing the mast to be raised by rotation around an axis located above the floats. However, such a tidal turbine does not have a platform and must be towed to the banks of the watercourse for maintenance. Another example is US patent application US2010176595, which discloses a lifting system for pivoting the turbine around an axis of rotation located above the power plant's floats.Other tidal turbines feature platforms equipped with a similar lifting system, but the platform must include a central opening to allow the turbine to be raised. This reduces the available space on the platform and limits the maintenance personnel's ability to move around the turbine or to place potentially bulky repair and testing tools. For example, US patent application 2018087484 discloses a crane attached to the platform to facilitate pivoting the turbine around its axis of rotation located on the platform's sides. The lifting system is cumbersome, and the platform becomes unbalanced when raised. The turbine. We can also mention international application WO2014064067Al, which discloses a floating tidal turbine comprising a propeller mounted to rotate at the base of a mast around a horizontal axis of rotation, an electric generator resting on a platform above the water, and a maneuvering system designed to raise or lower a mast that passes through the platform. However, the platform is obstructed by the generator, and even more so when the mast is raised above the platform.

[0007] These systems are mechanically complex, often heavy and / or large. Moreover, whether in a repair or transport situation, these lifting systems, as well as the generator, occupy a significant amount of space on the platform connecting the floats and affect the transport of the tidal turbine to or from the repair dock.

[0008] In order to reduce maintenance operations on the turbines, tidal turbines can be equipped with debris protection systems. Indeed, medium or small debris, consisting mainly of dead leaves, twigs, and aquatic vegetation, or debris of anthropogenic origin, which is primarily submerged, can directly affect the operation of the turbines. Thus, the twin rotors of patent application EP3707371, placed in a rectangular channel, are protected by a debris protection system located upstream of the channel mouth. This system comprises four cylindrical surfaces made up of a series of parallel bars. These bars prevent debris from entering the submerged channel and also contribute to regulating the incoming current by breaking up large turbulent structures.However, these screens become clogged over time and require cleaning to keep them clean. This cleaning, also called screen removal, is essential for all inlet screen systems; it should also be remotely controllable. But patent EP3707371 does not disclose any system that could facilitate cleaning the debris removal system on-site, that is, when the turbine is in operation.

[0009] Furthermore, other larger floating debris can affect either the floats or the structures connecting the floats to the turbomachine. To deflect large floating debris from the platform, a partially submerged structure in the form of two elongated V-shaped plates, called by the acronym RDDP (Research Debris Diversion Platform), is used. However, such a structure tends to block the incoming current. In addition, French patent application FR3079002 discloses a similar anti-debris system; however, this system does not protect the turbine in a fully submerged position. Therefore, there is a challenge in simultaneously providing protection against both types of debris, at a lower cost, without impairing performance, and with minimal human intervention.

[0010] Thus, we observe that the different solutions provided by the power plants Prior art designs attempting to address the aforementioned drawbacks are not sufficiently compatible with architectural properties that ensure strong passive stability of the nominal operating regime, primarily with respect to pitch and yaw disturbances. Indeed, in the prior art, this stability is often achieved by designing a bulky flotation device that is material-inefficient, resulting in excessive manufacturing and transportation costs. This design may stem from a poor connection between the tidal turbine and its mooring line(s), but it may also result from the need to support the weight of the entire turbine assembly of the lifting system and / or the elevation of the turbomachine's center of gravity during lifting.

[0011] An object of the present invention is therefore to propose means to overcome the aforementioned disadvantages, and in particular, to propose means to improve the maintenance of floating hydroelectric power plants.

[0012] Another objective is to improve maintenance at the plant's operating site or on the riverbank.

[0013] Another objective is to reduce the frequency of maintenance operations.

[0014] The other objects, features and advantages of the present invention will become apparent from an examination of the following description and accompanying drawings. It is understood that other advantages may be incorporated. SUMMARY

[0015] To achieve this objective, a floating hydroelectric power plant is proposed, intended to be partially immersed in a watercourse having a direction of current, the floating hydroelectric power plant comprising a flotation unit comprising at least two hulls coupled by a frame, the frame comprising a flat part, called floor, an upper face of the floor extending in a principal plane, and, for each hull, the frame comprises a connecting element linking the hull to the floor.

[0016] The control unit further comprises: a. a channel having a convergent then divergent section in the direction of the current, the channel comprising a pair of lateral fairings connected by an upper plate and a lower plate parallel to the main plane; b. two counter-rotating turbines mounted within the channel along two axes of rotation respectively defining together a secondary plane, perpendicular to the main plane, each turbine having at least two blades and being coupled to at least one generator carried by the power plant; c. a mooring line configured to connect the canal to an anchoring system intended to be fixed to the bed or bank of the watercourse; and d. a first pair of telescopic slides located upstream of the plane secondary in the direction of the current, and a second pair of telescopic slides located downstream of the secondary plane, each telescopic slide being located entirely below the main plane and connecting one of the armature's connecting elements to the channel, the telescopic slides being configured to allow translation of the channel relative to the armature in a direction, called displacement, perpendicular to the main plane and so that a top face of the channel remains below the main plane.

[0017] Thus, a floating hydro turbine is provided that facilitates the maintenance operations necessary for its operation. Such a hydro turbine allows the channel containing the components to be maintained to be brought closer to the site, for example, for cleaning a turbine or repairing a generator, to facilitate access, while avoiding cluttering the platform on which the operators work. Advantageously, such a hydro turbine facilitates its towing to a riverbank to allow for more extensive maintenance operations, such as replacing a channel component, like a turbine. Such a hydro turbine is particularly well-suited for towing near the banks of shallow rivers, the depth of which can vary from 2 to 4 m.

[0018] According to another aspect, a maintenance method for a floating hydroelectric power plant as defined above is proposed, comprising: a. a positioning for operation at an operating site of the floating hydroelectric power plant, which is afloat on the surface of a watercourse, and b. a maintenance positioning comprising a translation of the channel relative to the armature along the direction of movement, so that an upper face of the channel remains below the main plane and occupies an emerged position. BRIEF DESCRIPTION OF THE FIGURES

[0019] The aims, objects, features and advantages of the invention will become clearer from the detailed description of an embodiment thereof, which is illustrated by the following accompanying drawings in which:

[0020] [Fig.1] The [Fig.1] schematically illustrates a perspective view of an embodiment of a floating hydroelectric power plant;

[0021] [Fig.2] [Fig.2] schematically illustrates a perspective view of one embodiment of the channel;

[0022] [Fig.3] [Fig.3] schematically illustrates a partial perspective view of the power plant illustrated in [Fig.1] with a view along a section in a plane AB perpendicular to the secondary plane C and passing through the axis X' of a turbine;

[0023] [Fig.4] the [Fig.4], schematically illustrates a perspective view of an embodiment of an anti-debris system in a first position;

[0024] [Fig.5] [Fig.5], schematically illustrates a perspective view of the debris protection system illustrated in [Fig.4], in a second position;

[0025] [Fig.6] the [Fig.6], schematically illustrates a perspective view of another embodiment of a floating hydroelectric power plant;

[0026] [Fig.7] the [Fig.7], schematically illustrates a side view of another embodiment of a floating hydroelectric power plant in which the canal occupies a submerged position;

[0027] [Fig.8] [Fig.8] schematically illustrates a top view of another embodiment of a floating hydroelectric power plant;

[0028] [Fig.9] the [Fig.9], schematically illustrates a cross-sectional view of an embodiment of a telescopic slide;

[0029] [Fig. 10] the [Fig. 10], schematically illustrates a cross-sectional view of another embodiment of a telescopic slide;

[0030] [Fig. 11] the [Fig. 11], schematically illustrates a perspective view of another embodiment of a floating hydroelectric power plant in which the canal occupies an emerged position.

[0031] The drawings are given by way of example and are not limiting of the invention. They constitute schematic representations of principle intended to facilitate understanding of the invention and are not necessarily to scale with practical applications. DETAILED DESCRIPTION

[0032] Before beginning a detailed review of embodiments and implementations of the invention, optional features which may possibly be used in association or alternatively are stated below.

[0033] According to one example, the floor includes a main opening and the power plant includes a lifting system comprising a connecting element linked to the channel and passing through the main opening, the lifting system being configured to move the channel in translation along the direction of movement.

[0034] According to one example, the telescopic slides are configured to occupy a deployed position in which the telescopic slides maintain the channel in a submerged position and a raised position in which the telescopic slides maintain at least the upper face of the channel in an emerged position

[0035] According to one example, each telescopic slide comprises a lower part fixed to the channel, an upper part fixed to one of the connecting elements and at least one intermediate part movable in translation along the direction of movement relative to to the lower and upper parts.

[0036] According to one example, the lower part of at least one slide includes a ball bearing configured to guide said at least one intermediate part in movement along the direction of movement.

[0037] According to one example, the channel comprises an upper housing mounted on the upper plate and a lower housing mounted on the lower plate, at least one of the upper and lower housings being configured to house said at least one generator.

[0038] According to one example, said at least one generator is housed within the upper casing.

[0039] According to one example, the upper plate of the channel includes at least one secondary opening leading into the upper housing.

[0040] According to one example, said at least one secondary opening is located opposite the main opening in the direction of movement.

[0041] According to one example, the power plant includes an anti-debris system comprising a lower grid located upstream of the channel and having a downstream edge mounted on the lower plate of the channel and an upstream edge located upstream of the downstream edge, and an upper plate located upstream of the channel and having a downstream edge mounted on the upper plate of the channel and an upstream edge located upstream of the downstream edge of the upper grid, the upper grid being shaped so that its upstream edge is configured to be in contact with the upstream edge of the lower grid.

[0042] According to one example, the upper grid comprises several bars located on either side of a middle bar having a "Y" shape flared towards the upstream edge of the upper grid so that the middle bar forms a passage for the mooring line.

[0043] According to one example, the upper grid is pivotally mounted about a transverse axis contained in a secondary plane parallel to the main plane, between a first position in which the upstream edge of the upper grid is located below the secondary plane so that the upper grid can retain debris transported by the watercourse, and a second position in which the upstream edge of the upper grid is located in or above the secondary plane so that the retained debris can be transported by the watercourse above the channel.

[0044] According to one example, the control unit includes a control device configured to move the upper grid by pivoting around the transverse axis.

[0045] According to one example, the control device includes a cylinder, preferably a pneumatic cylinder, and preferably a cylinder with a movable rod.

[0046] According to one example, the control unit includes an electronic control unit configured to control the control device so as to bring the upper grid into the second position at a determined frequency.

[0047] According to one example, the electronic control unit is configured to determine a power difference between a current electrical power supplied by said at least one generator and a reference power corresponding to an electrical power supplied by said at least one generator in the absence of debris on the upper grid, the electronic control unit being further configured to calculate the frequency determined from the power difference.

[0048] According to one example, the method comprises, before being put into the operating position, an installation including: a. a towing of the floating hydroelectric power station on the surface of the watercourse, from a bank of the watercourse to the operating site, the towing including a translation of the canal relative to the framework in the direction of movement, so that an upper face of the canal remains below the main plane and occupies an emerged position; b. mooring the floating hydroelectric power station by connecting the canal, via the mooring line, to an anchoring system fixed to the bed or bank of the watercourse, and c. an operational phase, comprising a translation of the channel relative to the armature along the direction of movement, such that an upper face of the channel remains below the main plane and occupies a submerged position

[0049] According to one example, the method comprises, after placing the device in the maintenance position, a dismantling process including: a. a disconnection of the mooring line from the anchoring system; and b. a towing of the floating hydroelectric power plant on the surface of the watercourse, from the operating site to a bank of the watercourse.

[0050] Figures 1 to 11 show a floating hydroelectric power plant 1 designed to be partially submerged in a watercourse with a current direction D. The power plant 1 is particularly suitable for rivers, and more specifically for shallow rivers, i.e., those with a depth between 2 m and 4 m. The power plant 1 comprises a flotation device 10, a frame 14, a channel 20 and a mooring line 80.

[0051] The flotation device 10 comprises at least two hulls 12 coupled by the frame 14. The flotation device 10 has a catamaran-type design. The hulls 12 form two elongated floats oriented in the direction of the current D. For example, the hulls 12 are parallel to each other with respect to a median plane A. The frame 14 comprises a flat portion 15, referred to as the floor, with an upper face of the floor 15 extending in a principal plane B. The floor 15 is intended to be horizontal in the absence of swell. Furthermore, the frame 14 comprises, for each hull 12, a Connecting elements 30 to 33 link the shell 12 to the floor 15. The connecting elements 30 to 33 support the floor 15. The floor is horizontally exposed under nominal conditions, i.e., in the so-called zero-profile position. The reinforcement 14 has an overall arch shape. Preferably, each shell 12 is equipped with a longitudinal reinforcement 16, extending in a plane parallel to the median plane A, and comprising parallel and overlapping bars. The two longitudinal reinforcements 16 are fixed to the reinforcement 14.

[0052] The channel 20 has a convergent and then divergent cross-section in the direction of the current D. The channel 20 comprises a pair of lateral fairings 22 connected by an upper plate 24 and a lower plate 26 parallel to the main plane B. For example, the lateral fairings 22 have cylindrical surfaces generated by a vertical line resting on two highly curved wing profiles, symmetrical with respect to the median plane A. The framework of a lateral fairing 22 may comprise vertical sheet metal plates, of a height equal to the height of the fairing 22, joined so as to follow the average line of the profile adopted by the fairing 22. A lateral fairing 22 may further comprise reduced transverse plates connected by welding to the preceding longitudinal plates and some of which are also connected to U-shaped profiles, thus preserving the external grooves which are locally reinforced.Advantageously, a side fairing 22 includes pre-cut foam blocks, inserted between the sheet metal plates and the transverse reduced plates to recreate the desired hydrodynamic profiles. Links can be added between the vertical sheet metal plates and the upper 24 and lower 26 plates. The assembly comprising the side fairings 22 and the upper 24 and lower 26 plates can form a monobloc frame.

[0053] The mooring line 80 is configured to connect the channel 20 to an anchoring system intended to be fixed to the bed or bank of the watercourse. The mooring line 80 secures the power plant against the current. The line 80 may include an upstream portion, D, depending on the direction of the current, configured to be connected to one or more fixed objects of the anchoring system. The mooring line 80 lies in the median plane A, which is perpendicular to the principal plane B.

[0054] Furthermore, the power plant 1 comprises two turbines 36 mounted counter-rotating within the channel 20 along two axes of rotation X, X', respectively, which together define a secondary plane C. The axes of rotation X, X' are parallel to each other. Preferably, the turbines are identical to limit the pitching of the power plant 1 during operation. The secondary plane C is perpendicular to the main plane B. The secondary plane C is vertical during operation (and in the absence of waves), i.e., during electricity production. Each turbine 36 has at least two blades 38. Each turbine 36 is coupled to at least one generator 48 mounted on the power plant 1. The channel 20 can Furthermore, it includes an upper casing 25 mounted on the upper plate 24 of the channel 20, and a lower casing 27 mounted on the lower plate 26 of the channel 20. Advantageously, at least one of the upper casings 25 and lower casings 27 is configured to house at least one generator 48. Alternatively, the power plant 1 comprises two generators 48 respectively coupled to the two turbines 36. Preferably, the generator(s) 48 are housed within the upper casing 25. In this case, each turbine 36 is rotationally mounted on a generator 48 by an upper pivot joint, and is rotationally mounted downwards by a lower pivot joint located within the lower casing 27.

[0055] For example, the upper casing 25 and lower casing 27 are bounded by transversely uniform walls that are symmetrical to each other with respect to a horizontal plane of the channel 20, parallel to the main plane B, located midway between the upper plates 24 and lower plates 26. The casings 25, 27 may have a profile such that the sections parallel to the median plane A form a planar convex profile in the direction of the current D. The casings 25, 27 each have a flat face fixed below and on the upper plates 24 and lower plates 26 respectively, and a convex face connecting upstream with said flat faces by a leading edge 28.

[0056] For example, the upper casing 25 contains generators 48 advantageously with direct drive and discoidal shape, and also contains an electronic control unit 201, illustrated in [Fig.5], configured to regulate the rotational speed of one of the two generators 48, called master, via a rotational speed search system ensuring the maximum power extracted for a given incident current speed on the rotors, and regulating another generator 48 to rotate at the same rotational speed and in the same angular position relationship.

[0057] The channel 20 further comprises a profiled mid-section 17 extending longitudinally in the mid-plane A, separating the two turbines 36 and fixed between the two upper plates 24 and lower plates 26. The mid-section 17 has a leading edge 18 forming a cylindrical column to which the tensioned mooring line 80 (cable, chain, rope, rod, etc.) is attached at a point O. The attachment point O may include a pivot joint 19 with an axis perpendicular to the mid-plane A. For example, the pivot joint 19 is attached to a nut of a screw-nut system, the nut being housed within said column so that a rotational movement of the screw is transformed into a translational movement for the nut and allows fine adjustment of the height position of the pivot joint 19.

[0058] In particular, the central unit 1 comprises a first pair of telescopic slides 50, 51 located upstream of the secondary plane C in the direction of the current D, and a second pair of telescopic slides 52, 53 located downstream of the secondary plane C. Each telescopic slide 50 to 53 is located entirely below the main plane B. Each slide 50 to 53 connects one of the connecting elements 30 to 32 of the reinforcement 14 to the channel 20. The telescopic slides 50 to 53 are further configured to allow translation of the channel 20 relative to the reinforcement 14 along a Z direction, referred to as the displacement direction. The Z displacement direction is perpendicular to the principal plane B. In addition, the slides 50 to 53 are configured to allow translation of the channel 20 such that an upper face FS of the channel 20 remains below the principal plane B. Generally, the telescopic slides 50 to 53 are configured to occupy a deployed position in which the telescopic slides 50 to 53 maintain the channel 20 in a submerged position, and a raised position in which the telescopic slides 50 to 53 maintain at least the upper face FS of the channel 20 in an emerged position.

[0059] In general, the slides 50 to 53 maintain the rigidity of the central unit 1 with respect to the appearance of a compensating torque linked to the lateral displacement of the Archimedes' thrust in reaction to the rolling disturbances, and which are transmitted to the pivot joint 19 on the cylinder 18 of the channel 20. The telescopic slides 50 to 53 ensure the guidance of the channel 20 during the process of lowering / raising the channel 20.

[0060] According to one embodiment, a telescopic slide 50 to 53, and preferably each slide 50 to 53, comprises a lower part 70 fixed to the channel 20, preferably on an external face of the side fairings 22. For example, the lower part 70 is screwed vertically onto the external face of a side fairing 22 and forms a groove whose bottom is parallel to the median plane A. Each slide 50 to 53 further comprises an upper part 71 fixed to one of the connecting elements 30 to 32 and at least one intermediate part 72 movable in translation along the direction of movement Z relative to the lower and upper parts 70, 71. Each upper part 71 is, for example, screwed onto each connecting element 30 to 33, for example onto internal faces of the connecting elements 30 to 33 facing the median plane A.Advantageously, as illustrated in Figures 9 and 10, the lower portion 70 of at least one slide 50 to 53 includes a first ball bearing 55 configured to guide the intermediate portion 72 in movement along the Z-direction. Furthermore, the upper portion 71 of a telescopic slide 50 to 53 may include a second ball bearing 56 configured to guide the intermediate portion 72 in movement along the Z-direction. The deployment and retraction of the slides 50 to 53 are facilitated by two ball bearings 55 and 56. The ball bearings 55 and 56 reinforce the connection of the channel 20 to the frame 14. These ball bearings 55 and 56 absorb crushing forces on the portions 70 to 72 of the slides in the direction perpendicular to the Z-direction. These bearings 55 and 56 also absorb torsional moments associated with disturbances. yawing and yaw which are restored at the level of channel 20 and which are transmitted to the flotation device 10.

[0061] Thus, the slides can be kept in the deployed position during operation, in order to rigidly hold the frame 14 of the flotation device 10 with the channel 20, by which the power plant 1 is moored; or in the fully raised position, for maintenance phases for light repairs or when towing the power plant between a repair quay on the banks and the operating site.

[0062] All the slides 50 to 53 are thus mounted on edge so that, in the deployed position, they offer maximum resistance to maintain the rigidity of the central unit 1 vis-à-vis: a. of a couple related to the longitudinal thrust on the flotation device 10 associated with the incident flow in nominal regime; and b. of the appearance of clockwise or counterclockwise compensation couples linked to the upstream or downstream longitudinal displacement of the Archimedes thrust in reaction to pitch disturbances, couples transmitted to the pivot joint 19 on the cylinder 18 of the channel 20. The disturbances which are exerted on the flotation device 10 and which are transmitted to the channel 20 are also controlled.

[0063] Thus, the channel 20 can occupy a fully submerged position, as illustrated in Figures 1 and 7, under the operating flotation device 10, and a fully raised position to bring the channel 20 closer to the floor 15 in order to facilitate maintenance operations, and where necessary, to facilitate towing the power plant 1 towards the banks in order to carry out more extensive maintenance operations, for example, changing a turbine. In particular, when the channel 20 is fully raised, as illustrated in [Fig. 11], the upper face of the upper fairing 25 moves closer to the floor 15. A technician working on the floor 15 can access the entire electrical system of the power plant 1, in particular the generators 48. Furthermore,

[0064] Advantageously, the control unit 1 includes a lifting system 61 configured to move the channel 20 in translation. For example, the floor 15 includes a main opening 60, and the lifting system 61 includes a connecting element 62 attached to the channel 20 and passing through the main opening 60. The connecting element 62 may be attached at its lower end, preferably by at least three strands, to the upper plate 24 of the channel 20. The connecting element 62 may be a cable or a sling. The lifting system 61 may include a winch 63, manual or motorized, mounted on the floor 15, the upper end of the connecting element 62 being attached to the winch 63.

[0065] Furthermore, the upper plate 24 of the channel 20 may include at least one Secondary openings 95 and 96 lead into the upper casing 25. This allows access to the interior of the upper casing 25, enabling the turbines 36 to be removed. A generator 48 can then be extracted, repaired on-site, or its power electronics or electronic control unit can be serviced. Furthermore, the electrical connection (not shown for simplicity) linking the generators to the electrical grid allows access to the power plant 1, enabling maintenance on the electrical energy produced by the unit.

[0066] When the generator(s) 48 are housed within the upper casing 25, secondary openings provide access to the generators to facilitate maintenance operations, for example, at the operating site or at a dedicated maintenance site located on the riverbank to allow for more extensive maintenance. To further facilitate access from the floor 15 into the upper casing 25, the secondary opening(s) 95, 96 are located directly opposite the main opening 60 along the direction of travel Z.

[0067] According to another advantage, the power plant 1 may include an anti-debris system 90, illustrated in Figures 4, 5; 7, 8 and 11, to retain debris transported by the watercourse, and prevent the debris from coming into contact with the turbines 36. The anti-debris system makes it possible to protect the power plant 1, and in particular the turbines, in order to limit maintenance operations as much as possible. The debris control system includes a lower grid 91 located upstream of channel 20. The lower grid 91 has a downstream edge 100 mounted on the lower plate 26 of channel 20 and an upstream edge 101 located upstream of the downstream edge 100. The debris control system 90 also includes an upper plate 92 located upstream of channel 20 and having a downstream edge 102 mounted on the upper plate 24 of channel 20 and an upstream edge 103 located upstream of the downstream edge 102 of the upper grid 92.The upper grid 92 is further shaped so that its upstream edge 103 is configured to be in contact with the upstream edge 101 of the lower grid 91. For example, the upper grid 92 may include several bars 97. Advantageously, the upper grid 92 may include a middle bar 98, and the bars 97 are located on either side of the middle bar 98. In particular, the middle bar 98 has a Y-shaped profile that flares outward toward the upstream edge 103 of the upper grid 92, so that the middle bar 98 forms a passage for the mooring line 80, as illustrated in [Fig. 8]. According to another advantage, the upper grid 92 is pivotally mounted about a transverse axis T contained in a secondary plane Pr parallel to the principal plane B.Furthermore, the grid 92 is configured to be mobile between a first position, in which the upstream edge 103 of the upper grid 92 is located below the secondary plane Pr, and a second position in which the upstream edge 103 of the upper grid 92 is located in or above. of the secondary plan Pr. In particular, in the first position, the screen 92 is configured to retain debris carried by the watercourse, and in the second position, the retained debris can be carried by the watercourse over the channel 20. Preferably, the debris control system 90 is configured so that when the upper screen is in the first position, the upstream edge 103 of the upper screen is in contact with the upstream edge 101 of the lower screen 91. According to one advantage, the power plant includes a control device 200 configured to pivotally move the upper screen 92. The control device 200 may include a cylinder, preferably a pneumatic cylinder, and preferably a sliding rod cylinder. The cylinder may be mounted, at both ends, to the channel 20 and to the upper screen 92 so as to be able to rotate the upper screen 92 about the transverse axis T relative to the channel 20.Alternatively, the cylinder is electric, comprising a geared motor 210 contained in a cylindrical housing 212 pivotally mounted about an axis T2 mounted perpendicularly to the median plane A. The geared motor 210 actuates a rod 211 of the cylinder. The rod 211 has an end pivotally mounted on the upper grid 92. The rod 211 is coaxial with the geared motor 210, which imposes a translational movement on the rod 211 and drives the upper grid 92 in pivoting about the transverse T.

[0068] Thus, by means of a screening operation, at the operating site of the power plant 1, the channel 20 is fully raised and the upper face 24 of the upper fairing 25 is brought closer to the floor 15, being in the vicinity of the floor 15. The upper grille 92 is also placed in the second position. In this case, an operator working on the floor 15 can access the debris suppression system 90, in particular the upper grille 92, to place the upper grille 92 in the second position by rotating it manually or by remote control.

[0069] The electronic control unit 201 can further be configured to control the control device 200 so as to bring the upper grid 92 into the second position at a predetermined frequency. For example, the electronic control unit 201 is configured to determine a power difference between a current electrical power supplied by said at least one generator 48 and a reference power corresponding to an electrical power supplied by said at least one generator in the absence of debris on the upper grid 92. The electronic control unit 201 can further be configured to calculate the determined frequency from the determined power difference.

[0070] To improve the protection of the control unit 1, the control unit 1 may include a V-shaped deflector 300 mounted on the flotation device 10, as illustrated in Figures 6 to 8, and 11. The deflector 300 is partially submerged, fixed to the upstream extension of the two longitudinal frames 16. The deflector 300 is intended to The flotation device 10 is protected from large floating debris by deflecting it to either side of the V-shaped arms. More specifically, the apex of the V is equipped with a vertical cylinder 301, extending longitudinally perpendicular to the main plane B. The vertical cylinder 301 forces trunks or branches impacting this apex transversely to tip to one side or the other of the deflector 300. Furthermore, the V-shaped arms include superimposed horizontal bars, or blades, 302. A cross-section along the median plane A of each of these horizontal blades is that of a symmetrical profile, which promotes the yaw stability of the central unit 1.

[0071] As illustrated in [Fig. 7], the mooring line 80, used to stabilize the power plant 1 in a neutral position against the current D, is subjected at the attachment point O to a tension R inclined at an angle Ph to a horizontal axis parallel to the main plane B. The tension R is composed of a vertical component of magnitude Iv = R * sin(Ph) (with Ph expressed in radians, R and Iv expressed in N). The magnitude of the vertical component Iv is included in the balance of vertical forces acting on the power plant 1, namely the resultant Ba of the Archimedes forces and the overall weight Wl of the power plant 1. The tension R is composed of a horizontal component of magnitude Ih = R * cos(Ph) (with Ph expressed in radians, R and Ih expressed in N).The intensity of the horizontal component Ih is a factor in the balance of horizontal forces acting on the central 1, namely a drag force Df exerted on the two hulls 12 at a point CD located at the intersection of a first axis G and a central axis Va, and a force De of greater intensity. The first axis G is located at the intersection of the median plane A and a horizontal plane passing through the wetted surface of the two hulls 12. The central axis Va is located at the intersection of the median plane A and the secondary plane C (in [Fig. 7], the secondary plane C is perpendicular to the plane of the sheet in [Fig. 7]). The force De corresponds to the sum of the drag forces exerted on channel 20. The drag forces exerted on channel 20 correspond to the thrusts on the turbines, the drags on the side fairings 22, on the upper plates 24 and lower plates 26, and on the grids 91, 92 of the anti-debris system 90.

[0072] Advantageously, the power plant 1 is configured so that in nominal operation (i.e. in zero attitude position), the equilibrium of the three vertical forces Ba, Wl, Iv acting in the median plane A on the power plant 1 is obtained, and the equilibrium of the moments of these three forces Ba, Wl, Iv at the anchor point O.

[0073] For example, the side fairings 22 of the channel 20 contain ballasts in the vicinity of the secondary plane C symmetrically with respect to the median plane A so that the center of gravity CG of the power plant is located on the central axis Va and below the anchor point O.

[0074] For example, the frame 14 is positioned so that the center of buoyancy CB of the central 1 is located on the central axis Va. The center of buoyancy CB corresponds to the center of the fluid volume (and also the center of gravity of the fluid) displaced by central 1. The center of buoyancy CB is also the point of application of the Archimedes' principle which makes central 1 float.

[0075] For example, the degree of immersion of the channel 20 is sufficient so that the flow above the upper plate 24 of the channel 20 is stabilized from vertical hydrodynamic forces, and that consequently the lifts on the upper casing 25 and lower casing 27 are opposite and substantially equal in intensity.

[0076] Thus, the vertical forces can balance according to the balance Iv + W1 = Ba (where W1 is the overall weight expressed in N, and Ba the Archimedes forces expressed in N) and do not create any moment at the anchor point O.

[0077] Advantageously, the power plant 1 is configured so that in nominal operation (i.e. in zero attitude position), the balance of the three horizontal forces Ih, Df, De acting in the median plane A on the power plant 1, and the balance of the moments of these three forces Ih, Df, De at the anchor point O.

[0078] For example, the length Lf of the hulls 12, with a constant cross-section over at least 80% of its length, is sufficiently large so that the Froude number (dimensionless) FF = Vsmax / (Lf * g)1 / 2, where Lf is in meters, Vsmax is the maximum conceivable surface flow velocity for the given site of the watercourse (expressed in meters per second) and g is gravity (expressed in m / s2), is less than 0.4. In this case, the sum of the hydrodynamic drags on the hulls 12 is substantially reduced to a friction drag Df, the wave drag, the source of longitudinal oscillations, being thus eliminated.

[0079] For example, the position of the anchor point O is fixed to equalize the magnitudes of the opposing moments MDf and MDc generated respectively by the drag force Df exerted on the two hulls 12 and the drag force exerted on the channel 20. This positioning can be defined during the design phase based on an average river velocity profile. For example, the position of the anchor point O is fixed on the column 18 of the mid-section 17, and the magnitude of the moment MDf can then be adjusted, if necessary, from the length of the connecting element 62, either manually or controlled via the winch 63.

[0080] Thus, the horizontal forces can balance according to the balance Ih = Df + De and the moments MDf and MDc cancel each other out.

[0081] A maintenance method for the power plant 1 described above can also be provided. The method comprises the following main steps: - a positioning for operation at an operating site of the floating hydroelectric power plant 1, floating on the surface of a watercourse, and - a maintenance positioning comprising a translation of the channel 20 relative to the armature 14 along the direction of displacement Z, so that an upper face FS of the channel 20 remains below the main plane B and occupies an emerged position.

[0082] The method may further include, prior to being put into the operating position, an installation comprising: - a towing of the floating hydroelectric power station 1 on the surface of the watercourse, from a bank of the watercourse towards the operating site, the towing including a translation of the channel 20 relative to the frame 14 along the direction of movement Z, so that an upper face FS of the channel 20 remains below the main plane B and occupies an emerged position; - mooring of the floating hydroelectric power station by connecting canal 20, via mooring line 80, to an anchoring system fixed to the bed or bank of the watercourse, and - an operational setting, comprising a translation of the channel 20 relative to the armature 14 along the direction of displacement Z, so that an upper face FS of the channel 20 remains below the main plane B and occupies an immersed position.

[0083] Furthermore, the process may include, after being placed in the maintenance position, a dismantling comprising: - a disconnection of the mooring line 80 from the anchoring system; and - towing the floating hydroelectric power plant across the surface of the waterway, from the operating site towards a bank of the watercourse.

Claims

Demands

1. A floating hydroelectric power station, intended to be partially submerged in a watercourse with a direction of current, the floating hydroelectric power station comprising: a flotation device (10) comprising at least two hulls (12) coupled by a frame (14), the frame (14) comprising a flat part (15), called floor, an upper face of the floor (15) extending in a principal plane (B), and, for each hull (12), the frame (14) comprises a connecting element (30 to 33) linking the hull (12) to the floor (15); characterized in that the power plant comprises: a channel (20) having a convergent then divergent section in the direction of the current, the channel (20) comprising a pair of lateral fairings (22) connected by an upper plate (24) and a lower plate (26) parallel to the main plane (B); two turbines (36) mounted counter-rotating within the channel (20) along two axes of rotation (X, X') respectively defining a secondary plane (C), perpendicular to the main plane (B), each turbine (36) having at least two blades (38) and being coupled to at least one generator (48) carried by the power plant; a mooring line (80) configured to connect the channel (20) to an anchoring system intended to be fixed to the bed or bank of the watercourse; and a first pair of telescopic slides (50, 51) located upstream of the secondary plane (C) in the direction of the current, and a second pair of telescopic slides (52, 53) located downstream of the secondary plane (C), each telescopic slide (50 to 53) being located entirely below the main plane (B) and connecting one of the connecting elements (30 to 33) of the reinforcement (14) to the channel (20), the telescopic slides being configured to allow a translation of the channel (20) relative to the reinforcement (14) along a direction (Z), called the displacement direction, perpendicular to the main plane (B) and so that a top face (FS) of the channel (20) remains below the main plane (B).

2. Power plant according to claim 1, wherein the floor (15) includes a main opening (60) and the power plant includes a lifting system (61) comprising a connecting element (62) connected to the channel (20) and passing through the main opening (60), the lifting system being configured to move the channel (20) in translation along the direction of movement (Z).

3. Central according to any one of the preceding claims, wherein the telescopic slides (50 to 53) are configured to occupy a deployed position in which the telescopic slides (50 to 53) maintain the channel (20) in a submerged position and a raised position in which the telescopic slides (50 to 53) maintain at least the upper face of the channel (20) in an emerged position.

4. Central according to any one of the preceding claims, wherein each telescopic slide (50 to 53) comprises a lower part (70) fixed to the channel (20), an upper part (71) fixed to one of the connecting elements (30 to 32) and at least one intermediate part (72) movable in translation along the direction of displacement (Z) relative to the lower and upper parts (70, 71).

5. Central according to the preceding claim, wherein the lower part (70) of at least one slide comprises a ball bearing configured to guide said at least one intermediate part (72) in movement along the direction of movement (Z).

6. Power plant according to claim 2, wherein the channel (20) comprises an upper housing (25) mounted on the upper plate (24) and a lower housing (27) mounted on the lower plate (26), at least one of the upper (25) and lower (27) housings being configured to house said at least one generator (48).

7. Central unit according to the preceding claim, wherein said at least one generator (48) is housed within the upper casing (25).

8. Power unit according to any one of claims 6 and 7, wherein the upper plate (24) of the channel (20) comprises at least one secondary opening (95, 96) opening into the upper housing (25).

9. Central according to the preceding claim, wherein said at least one secondary opening (95, 96) is located opposite the opening main (60) according to the direction of movement (Z).

10. Power plant according to any one of the preceding claims, comprising an anti-debris system (90) having a lower grid (91) located upstream of the channel (20) and having a downstream edge (100) mounted on the lower plate (26) of the channel (20) and an upstream edge (101) located upstream of the downstream edge (100), and an upper plate (92) located upstream of the channel (20) and having a downstream edge (102) mounted on the upper plate (24) of the channel (20) and an upstream edge (103) located upstream of the downstream edge (102) of the upper grid (92), the upper grid (92) being shaped so that its upstream edge (103) is configured to be in contact with the upstream edge (101) of the lower grid (91).

11. Central according to the preceding claim, wherein the upper grid (92) comprises several bars (97) situated on either side of a median bar (98) having a "Y" shape flared towards the upstream edge (103) of the upper grid (92) so that the median bar (98) forms a passage for the mooring line (80).

12. A power plant according to any one of claims 10 and 11, wherein the upper grid (92) is pivotally mounted about a transverse axis (T) contained in a secondary plane (Pr) parallel to the main plane (B), between a first position in which the upstream edge (103) of the upper grid (92) is located below the secondary plane (Pr) so that the upper grid (92) can retain debris transported by the watercourse, and a second position in which the upstream edge (103) of the upper grid (92) is located in or above the secondary plane (Pr) so that the retained debris can be transported by the watercourse above the channel (20).

13. Central unit according to the preceding claim, comprising a control device (200) configured to move the upper grid (92) by pivoting about the transverse axis (T).

14. Central according to the preceding claim, wherein the control device (200) comprises a cylinder, preferably a pneumatic cylinder, and preferably a cylinder with a movable rod.

15. Power plant according to any one of claims 13 and 14, comprising an electronic control unit (201) configured to control the control device (200) so as to bring the upper grid (92) into the second position at a determined frequency.

16. Central according to the preceding claim, wherein the unit of electronic control (201) is configured to determine a power difference between a current electrical power supplied by said at least one generator (48) and a reference power corresponding to an electrical power supplied by said at least one generator in the absence of debris on the upper grid (92), the electronic control unit (201) being further configured to calculate the frequency determined from the power difference.

17. A method for maintaining a floating hydroelectric power plant according to any one of the preceding claims, comprising: - placing the floating hydroelectric power plant in an operating position at an operating site while floating on the surface of a watercourse, and - placing it in a maintenance position comprising translating the channel (20) relative to the frame (14) along the direction of movement (Z), so that an upper face (FS) of the channel (20) remains below the main plane (B) and occupies an emerged position.

18. A method according to the preceding claim, comprising, prior to being put into operating position, an installation including: • towing the floating hydroelectric power plant on the surface of the watercourse, from a bank of the watercourse to the operating site, the towing including a translation of the channel (20) relative to the frame (14) in the direction of movement (Z), so that an upper face (FS) of the channel (20) remains below the main plane (B) and occupies an emerged position; • mooring the floating hydroelectric power plant by connecting the channel (20), by the mooring line (80), to an anchoring system fixed on the bed or a bank of the watercourse, and • putting into operation, including a translation of the channel (20) relative to the frame (14) in the direction of movement (Z), so that an upper face (FS) of the channel (20) remains below the main plane (B) and occupies a submerged position.

19. A method according to any one of claims 17 and 18, comprising, after being placed in the maintenance position, a dismantling comprising: • disconnecting the mooring line (80) from the anchoring system; and • towing the floating hydroelectric power plant on the surface of the watercourse, from the operating site to a bank of the watercourse.

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