Wave energy converter

Abstract

The wave energy converter (1) includes a floating unit (2) that floats on or near the fluid surface, in which a stroke device (7) is movably disposed; a generator (26) assigned to the floating unit (2) or the stroke device (7) and capable of generating electrical energy when driven; and a submerged vertical-to-vertical-motion damping unit (10) comprising a rod (12) extending from there into the floating unit (2) and connected to the stroke device (7), wherein when waves impart motion to the floating unit (2), it causes the floating unit (2) to move relative to the stroke device (7) and thus generates a fluid flow capable of driving the generator (26).

Description

Technical Field

[0001] The present invention relates to a wave energy converter including a floating unit floating on or near the water surface.

Background Art

[0002] In known wave energy converters provided with a floating unit, different driving means for driving a generator or a turbine are used.

[0003] Regarding the prior art, reference is made to International Publication No. 2012 / 169898A1, which discloses a floating unit including driving means connected to a generator for generating electrical energy. The cable extends upward from a fixed point on the seabed around the drive shaft of the driving means. The linear movement of the cable is converted into torque in the driving means.

[0004] Regarding other prior art documents related to wave energy converters provided with a floating unit, reference is made to German Patent No. 19947149D1 and German Utility Model No. 202008 / 007235U1.

[0005] However, the designs of known wave energy converters are not ideal. The mechanisms for converting wave energy into electrical energy are various. A problem that often occurs in wave energy converters is destruction, especially in high wave and / or strong wind situations. Known wave energy converters and mechanisms can be improved in terms of stability, simplicity, field of use, and suitability for mass production.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Therefore, an object of the present invention is to improve and further develop a wave energy converter of the above type, for example, by improving its stability and simplicity. Another object of the present invention is to provide a wave energy converter suitable for use in another field of use and mass production. [Means for solving the problem]

[0007] According to the present invention, the above-mentioned object is achieved by a method comprising the features of claim 1. According to claim 1, the wave energy converter includes a floating unit that floats on or near the surface of water, and a stroke device is movably positioned within the floating unit. The wave energy converter further includes a generator which may be assigned to the floating unit or, alternatively, to the stroke device. The generator, when driven, can produce electrical energy. The wave energy converter further includes a submerged vertical-to-vertical

[0008] The wave energy converter can be used in seawater. In many cases, the fluid surface may be the water surface or the sea surface. Nevertheless, it can also be used in other environments and with other fluids. The vertical oscillation damping unit can be positioned at an appropriate distance from the floating unit in the fluid. As waves pass through the fluid, they effectively cause the floating unit to rise and fall along with the fluid surface. However, the motion of the vertical oscillation damping unit in the fluid is not affected by the waves in the same way as the floating unit. As a result, each time the waves cause the floating unit to rise and fall, a relative motion occurs between the floating unit and the vertical oscillation damping unit, and the wave energy converter is designed to use this to generate electrical energy.

[0009] In an inventive manner, the aforementioned object of the present invention has been found to be achieved in a remarkably simple way by providing a wave energy converter equipped with a stroke device movably positioned within a floating unit. The special mechanism according to the present invention is such that the stroke device is connected to a rod extending from a submersible roll damping unit into the floating unit, and is easy to construct and relatively inexpensive. The wave energy converter equipped with the stroke device mechanism is robust and sturdy to withstand harsh wind and sea surface conditions. Furthermore, as waves impart motion to the floating unit, the floating unit moves with respect to the submersible roll damping unit and therefore with respect to the stroke device. In the system according to the present invention, it is not relevant whether the stroke device is stationary and the floating unit is moving, or vice versa, or whether the floating unit is stationary and the stroke device is moving. Regardless of the inertial coordinate system, there is relative motion between the stroke device and the floating unit, which drives the wave energy converter. The relative motion between the stroke device and the floating unit generates a fluid flow. This fluid flow can be used to drive a generator. Therefore, the wave energy converter is also suitable for use in other application areas. Therefore, the wave energy converter according to the present invention is improved in terms of stability, simplicity, application fields, and suitability for mass production.

[0010] According to a preferred embodiment, the stroke device of the wave energy converter may be positioned within the floating unit to move substantially longitudinally.

[0011] Preferably, the rod extends substantially longitudinally upward from the submerged motion damping unit into the floating unit. In this manner, the stroke device moves substantially longitudinally up and down within the floating unit. However, other configurations and orientations are possible depending on the different application areas and the fluid flow and current conditions, such as oblique orientations aligned with the flow direction and velocity.

[0012] The stroke of the stroke device within the floating unit can be limited by at least one damping device. Such damping devices may be positioned on rods above and below the floating unit. Preferably, the stroke can be limited to 2 meters, 1.5 meters, 1 meter, or less. The damping devices improve the stability of the wave energy converter, thereby making it suitable for withstanding harsh weather and sea surface conditions.

[0013] The rod can be directly and securely connected to and / or attached to the submarine vertical roll damping unit. However, tests have shown that the dynamic behavior of the wave energy transducer can be improved by connecting the rod to the submarine vertical roll damping unit by providing a coupling and / or suspension and / or shock absorber at the lower end of the rod. The coupling may be a universal joint or a cardan joint to ensure rotational freedom of the rod with respect to the submarine vertical roll damping unit at all axles. Relative motion can be limited by limiting means. The shock absorber and / or suspension may preferably be located above the coupling, thereby further dampening the movement of the system and making the wave energy transducer more suitable to withstand severe wind and sea surface conditions.

[0014] Preferably, the acceleration and / or velocity of the relative motion between the floating unit and the stroke device can be measured by their respective sensors. Sensor data may be used by an electronic control system to support a damping device, for example, by setting their damping coefficients or by providing additional information. The damping device may also be supported by reducing the flow to the generator or turbine using an electrically controlled valve, which may be controlled by an electronic control system.

[0015] According to a preferred embodiment, the floating unit may include inlet and / or outlet nozzles for allowing fluid to flow into and out of the floating unit. The nozzles can be designed to communicate fluidly with a stroke device that moves the fluid within the nozzles. The nozzles can also communicate fluidly with a generator. Preferably, fluid from outside the wave energy converter, such as seawater, can be drawn into at least one inlet nozzle as the stroke device moves downward within the floating unit. As the stroke device moves upward within the floating unit, the fluid can be pushed out through the outlet nozzle. Simultaneously, the movement of the stroke device can be used to push the fluid toward the generator or through another generator circulation loop. The generator circulation loop can be designed as a piping system within the floating unit. Advantageously, the piping system can guide the fluid flow from one side of the stroke device through the piping system to the other side of the stroke device. The piping system may include a system of valves arranged so that the flow around the generator or turbine flows in only one direction around the generator or turbine.

[0016] Preferably, the stroke device can be implemented as a piston, and the rod can be implemented as a piston rod. The piston mechanism is particularly suitable for moving fluid within a nozzle.

[0017] The generator is driven by a turbine and can produce electrical energy. In general, any suitable type of turbine can be used. By switching valves in the piping system, it is possible to ensure that the fluid flow around the turbine is in the same direction and that water flows through the generator under pressure from the stroke device cylinder and returns to the stroke device cylinder using the suction effect.

[0018] The turbine is driven by the flow of water and can drive the shaft of a generator. Preferably, the turbine may be an omnidirectional turbine and / or a pump that functions without creating airflow. The turbine can be implemented as a Kaplan turbine having a propeller (also called a runner) with adjustable blades. In particular, the blade pitch can be set according to the fluid flow rate. At high fluid flow rates, the blade pitch can be longitudinal or axial. At high fluid flow rates, the blade pitch can be horizontal or tangential. That is, even if the flow rate changes, the blades can be set to a pitch with the optimal angle of attack for the fluid. Kaplan turbines enable efficient operation under a wide range of flow conditions.

[0019] In a preferred embodiment, the stroke device may be implemented as a turbine. In this configuration, the generator may be assigned to and / or incorporated into the turbine. The turbine may be fixed to a rod, and the rod cannot be moved up and down. Furthermore, the turbine wheel may rotate around the rod, but the rod itself does not rotate.

[0020] To hold the wave energy converter in a predetermined position and orientation with respect to wind direction or fluid flow direction, the floating unit may include at least one transverse fin. The transverse fin may be attached to or fixed to the floating unit, or formed integrally with the floating unit.

[0021] In other preferred embodiments, the wave energy converter may include a workbench. Preferably, the workbench may be positioned on or above the floating unit body so that the workbench is substantially above the fluid surface or above the sea level.

[0022] Because the wave energy converter according to the present invention is suitable for various application fields, such a workbench may include various technical equipment, including antennas for transmitting and receiving information, inspection equipment, research equipment, electrical energy storage units, and / or equipment for intelligence or homeland security.

[0023] Preferably, the electrical energy generated by the generator of the wave energy converter can be used to power the technical equipment arranged on the workbench. In this way, the wave energy converter according to the present invention can be used to provide a self-sufficient and energy-independent workbench at sea, that is, an autonomous single system for various fields of use.

[0024] According to another preferred embodiment, the wave energy converter can be fixed to a ground anchor. The ground anchor can be positioned on the seabed. The ground anchor can be, for example, a lump weight, bolt-fixed, or suction anchor. The wave energy converter can be fixed to the ground anchor using a long connecting element that can be attached to the wave energy converter, for example, to a floating unit. Advantageously, the long connecting element can be attached to the heave damping unit of the wave energy converter in the sea. The long connecting element can include, for example, a cable, a chain, or a rope.

[0025] The heave damping unit can include a buoyancy element for compensating for approximately half of the weight of the wave energy converter, including related equipment such as the workbench and technical equipment, in addition to the weight of the long connecting element. The buoyancy element causes the damping element to float at a substantially neutral position in the sea. The buoyancy element can include a foam material.

[0026] To make the wave energy converter less susceptible to the influence of severe weather and sea surface conditions, the long connecting element does not directly fix the wave energy converter to the ground anchor. Instead, the long connecting element extending from the wave energy converter is guided underground via a chain buoy and / or a subsea floater and / or its fixture. Preferably, the fixing of the wave energy converter to the seabed or underground, that is, the mooring rigging, can be achieved by a long connecting element connecting the heave damping unit in the sea to the subsea floater, or by a second long connecting element connecting the subsea floater to the seabed / ground anchor.

[0027] According to a preferred embodiment, the long connection element includes at least one cable for transporting electrical energy to a marine storage unit for electrical energy. The marine storage unit can be assigned to or arranged on a ground anchor, a chain buoy, a marine floater, and / or any of their fixtures.

[0028] The marine storage unit for storing electrical energy opens up yet another field of use for the wave energy converter according to the invention. For example, the marine storage unit can be used to charge remotely operated vehicles such as underwater drones. The marine storage unit can be used as a charging spot like a gas station for remotely operated vehicles, i.e., "ROV (remotely operated vehicle)".

[0029] There are several ways to design and further develop the teachings of the present invention in an advantageous manner. For this purpose, on the one hand, refer to the dependent claims that depend on the claims, and on the other hand, refer to the following description of the preferred examples of the embodiments of the present invention shown in the drawings. Regarding the description of the preferred embodiments of the present invention using the drawings, in general, the preferred embodiments of this teaching and other, further developed ones are described.

Brief Description of the Drawings

[0030] [Figure 1] It is a diagram of an exemplary embodiment of a wave energy converter according to the present invention. [Figure 2] It is a diagram of the floating unit of the wave energy converter of FIG. 1. [Figure 3] It is a diagram of an exemplary embodiment of a wave energy converter according to the present invention fixed to a ground anchor. [Figure 4] It is an example of four graphs showing the distribution functions of several measured values related to the wave energy converter. [Figure 5] It is a diagram of another exemplary embodiment of the wave energy converter according to the present invention. [Figure 6] It is a diagram of the wave energy converter of FIG. 5 showing a flexible joint connecting a rod to a marine heave damping unit. [Figure 7] Figure 5 shows a wave energy converter, specifically a stroke device implemented as a turbine. [Figure 8] This is a cross-sectional view of the stroke device shown in Figure 7, which is implemented as a turbine. [Figure 9] This is a diagram of an exemplary embodiment of the wave energy converter according to the present invention, fixed to an underwater float. [Modes for carrying out the invention]

[0031] Figure 1 shows a wave energy converter 1 equipped with a floating unit 2.

[0032] The floating unit 2 floats on or near the sea surface 3. Waves 4 on the oscillations around the sea surface 3 are shown in schematic form. In addition, the stroke 5 of the waves 4 is shown in schematic form. A stroke device 7, implemented as a piston, is movably positioned within the floating unit 2 and moves substantially longitudinally 8. The wave energy converter 2 further includes a pitch-and-drop damping unit 10 having buoyancy elements 11 inside to compensate for weight and help to keep the pitch-and-drop damping unit 10 at a substantially neutral height in the sea.

[0033] The rod 12 extends from the submerged vertical motion damping unit 10 into the floating unit 2 and is connected to the stroke device 7. When the wave 4 imparts vertical motion 8 to the floating unit 2, the floating unit 2 moves relative to the stroke device, thus creating a fluid flow through the floating unit 2.

[0034] The rod 12 is equipped with damping devices 13a and 13b. The damping devices 13a and 13b are positioned on the rod 12 at the upper and lower positions of the floating unit 2. The damping devices 13a and 13b effectively limit the maximum stroke of the piston 7 within the floating unit 2.

[0035] Rod 12 further extends upward through the floating unit 2 and supports the work platform 15. The work platform 15 is positioned above the sea surface 3 and above the main body of the floating unit 2. Technical equipment 17 which will be positioned on the work platform 15 is schematically shown, and this is, for example, an antenna 18 for transmitting and receiving information.

[0036] The floating unit 2 further includes a transverse fin 20, an inlet nozzle 21a, and an outlet nozzle 21b. Fluid near the sea surface 3 can be drawn into the inlet nozzle 21a by the downward stroke of the stroke device 7, which is implemented as a piston, that is, by the downward movement within the floating unit 2 by the stroke device 7, or in other words, by the downward movement of the floating unit 2 in relation to the vertical oscillation damping unit 10.

[0037] Figure 2 shows a more enlarged view of the floating unit 2. Separate generator circulation loops 23 of the internal piping system are shown for the fluid moved within the floating unit 2 by a stroke device 7 implemented as a piston. The fluid moved through the generator circulation loops 23 drives a Kaplan turbine 24. The Kaplan turbine 24 then drives a generator shaft 25, which drives a generator 26, which generates electrical energy. The generator may be a 2kW generator. The energy generated by the generator 26 is used for technical equipment on a workbench (not shown in Figure 2).

[0038] Figure 3 shows a more typical configuration of the wave energy converter 1. The wave energy converter 1 is fixed to an underground anchor 28 on the seabed 29 by a long connecting element 30a, which is implemented as a chain including a cable. The long connecting element 30a is attached to the underwater vertical oscillation damping unit 10 of the wave energy converter 1.

[0039] From the underwater vertical-to-vertical motion damping unit 10, the long connecting element 30a is guided into the seabed via the attachment 31a of a chain buoy 32 floating on or near the sea surface 3, and via the attachment 31b of an underwater floater 33. The attachments 31a and 31b are designed as three-hole tabs to ensure easy and secure connection of the long connecting element 30.

[0040] The underwater floater 33 provides sufficient buoyancy to hold approximately half the chain weight of the long connecting element 30a mounted on the chain buoy 32.

[0041] To ensure the stable anchoring of the wave energy converter 1, which is not significantly affected by storms, tides, or currents, the underwater floater 33 serves as a standby point for the long connecting element 30a, which is implemented as an anchor chain. The underwater floater 33 is positioned approximately 10-20 m below the sea surface 3. The long connecting element 30b between the underwater anchor 28 and the attachment 31b is implemented as a nylon rope, providing flexibility within the system.

[0042] The long connecting elements 30a and 30b include cables for transporting electrical energy from the generator in the wave energy converter 1 to the underwater storage unit 35. In this exemplary embodiment, the underwater storage unit 35 is another unit located on the underground anchor 28. The underwater storage unit 35 can be used for a variety of application areas. One example would be to charge remotely operated vehicles such as underwater drones (not shown).

[0043] Figure 4 shows illustrative graphs of the distribution functions of several measured values ​​obtained by simulation of the experimental configuration of the wave energy converter power plant according to the present invention.

[0044] In the experimental configuration, significant wave height H S The value is set to 0.5m, and the zero crossing wave period T Z It was set to 3.0 seconds.

[0045] The graph in the upper left of Figure 4 shows the energy output of the wave energy converter in kilowatts (kW). From this graph, it can be seen that the energy output is quite reasonable, with an average distribution of 0.5 kW. Furthermore, there are no very high peaks, which is advantageous for the stability of the wave energy converter, as it is not significantly affected by storms, tidal currents, or ocean currents, and therefore can withstand severe weather and sea surface conditions.

[0046] The graph in the upper right of Figure 4 shows the force distribution function of the stroke device implemented as a piston, in units of kilonewtons (kN). The piston force is reasonable, and the load on the piston is less than 10 kN.

[0047] In the lower left graph of Figure 4, the distribution function of the relative velocity of the stroke device within the floating unit is shown in meters per second (m / s). The velocity is less than 1.0 meter per second in most parts.

[0048] In the lower right graph of Figure 4, the distribution function of the relative motion of the stroke device within the floating unit is shown in meters ("m"). The motion is within a preferred maximum stroke of 2.0 meters, which means there is no significant endstop effect within the system.

[0049] Figure 5 shows another exemplary embodiment of the wave energy converter 1 comprising a floating unit 2. A stroke device 7, implemented as a turbine 24, is movably positioned within the floating unit 2 and moves substantially longitudinally 8. Unlike the embodiment in Figure 2, the floating unit 2 of the wave energy converter 1 in Figure 5 does not include inlet or outlet nozzles. There is no circulating loop of an internal piping system that moves fluid through the floating unit 2. Instead, electrical energy is generated directly from the turbine 24 by the stroke of the stroke device 7 implemented as a turbine 24, i.e., by the motion of the turbine 24 within the cylinder of the stroke device in the floating unit 2, or in other words, by the motion of the floating unit 2 relative to the vertical-to-vertical The stroke device cylinder is attached to and / or part thereof of the floating unit 2. However, even in embodiments where the stroke device 7 is implemented as a turbine 24, additional inlet and / or outlet nozzles can be provided, and as previously mentioned with respect to Figure 2, a circulation loop of the internal piping system can additionally move fluid within the floating unit 2 to drive an additional turbine and / or an additional generator.

[0050] Figure 6 is a detailed diagram of the connection between the rod 12 and the submarine vertical-to-vertical-motion damping unit 10. A universal joint 36, or in other words, a cardan joint, is provided to ensure rotational degrees of freedom of the rod 12 with respect to the submarine vertical-to-vertical-motion damping unit around all axles. A shock absorber and / or suspension is provided at position 37 on the rod 12, preferably above the universal joint, to further dampen the motion of the system.

[0051] Figure 7 is a detailed view of the stroke device 7, which is implemented as a turbine 24 in this embodiment. The turbine 24 is fixed to the rod 12 and cannot move the rod 12 up and down. Furthermore, the turbine wheel 40 can rotate around the rod 12, but the rod 12 itself does not rotate. The generator 26 is integrated with the turbine 24 and is depicted by symbols in Figure 7.

[0052] Figure 8 shows a cross-sectional view of the stroke device 7 of Figure 7 as implemented as a turbine 24. It can be seen how the turbine wheel 40 is rotatably held on the rod 12 and how the generator 26 is integrated with the turbine 24. The hollow space within the rod 12 can be used for electrical cables and energy transport to supply power to technical equipment which may be located on a floating unit and / or a work platform, and / or to transport energy to an underwater storage unit for storing electrical energy.

[0053] Figure 9 shows an exemplary overall configuration of the exemplary embodiment of the wave energy converter 1 according to Figure 5. The wave energy converter 1 is secured to the underwater floater 33 by long connecting elements 30a, which are mounted as a chain. The long connecting elements 30a are attached to the underwater vertical oscillation damping unit 10 of the wave energy converter 1. The underwater floater 33 can then be secured to an underground anchor (not shown) on the seabed by other long connecting elements 30b. The long connecting elements 30a, 30b may include cables for transporting electrical energy from the generator in the wave energy converter 1 to the underwater storage unit, as previously described with respect to Figure 3.

[0054] Many improvements and other embodiments of the invention described herein will be conceived by those skilled in the art who enjoy the benefits of the teachings presented in the above description and the associated drawings. Particular emphasis is placed on the situations in which the above embodiments can be scaled down to smaller or larger units. Therefore, it should be understood that the invention is not limited to the specific embodiments disclosed herein, and improvements and other embodiments are also intended to be included within the scope of the accompanying claims. While specific terms are used herein, they are used in a general and descriptive sense only and are not intended to be limiting. [Explanation of symbols]

[0055] List of reference codes 1. Wave Energy Converter 2 Floating Units 3 Sea surface 4 waves 5 strokes 7 Stroke device 8. Vertical direction 10. Vertical oscillation reduction unit 11 Buoyancy elements 12 rods 13a, 13b Damping device 15 Workbench 17 Technical equipment 18 Antennas 20 lateral fins 21a Inlet nozzle 21b Outlet nozzle 23. Generator circulation loop 24 Turbines 25 Generator shaft 26 Generators 28 Underground anchors 29 Undersea 30a, 30b Long connection elements 31a, 31b Mounting hardware 32 Chain Buoy 33 Underwater floaters 35 Underwater Storage Units 36. Flexible joint 37 position 40 Turbine Wheel

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