WO2017049200A1 - Système de prise de force pour convertisseur d'énergie des vagues - Google Patents

Système de prise de force pour convertisseur d'énergie des vagues Download PDF

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Publication number
WO2017049200A1
WO2017049200A1 PCT/US2016/052304 US2016052304W WO2017049200A1 WO 2017049200 A1 WO2017049200 A1 WO 2017049200A1 US 2016052304 W US2016052304 W US 2016052304W WO 2017049200 A1 WO2017049200 A1 WO 2017049200A1
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WIPO (PCT)
Prior art keywords
pumping
driving
cylinder
generator
force
Prior art date
Application number
PCT/US2016/052304
Other languages
English (en)
Inventor
Balakrishnan G. Nair
Timothy R. MUNDON
Original Assignee
Oscilla Power Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Oscilla Power Inc. filed Critical Oscilla Power Inc.
Priority to GB1804991.6A priority Critical patent/GB2557808B/en
Priority claimed from US15/268,341 external-priority patent/US10352291B2/en
Publication of WO2017049200A1 publication Critical patent/WO2017049200A1/fr

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/14—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy
    • F03B13/16—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem"
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/14—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy
    • F03B13/16—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem"
    • F03B13/18—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore
    • F03B13/1845—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem
    • F03B13/187—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem and the wom directly actuates the piston of a pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F03—MACHINES OR ENGINES FOR LIQUIDS; WIND, SPRING, OR WEIGHT MOTORS; PRODUCING MECHANICAL POWER OR A REACTIVE PROPULSIVE THRUST, NOT OTHERWISE PROVIDED FOR
    • F03B—MACHINES OR ENGINES FOR LIQUIDS
    • F03B13/00—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates
    • F03B13/12—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy
    • F03B13/14—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy
    • F03B13/16—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem"
    • F03B13/18—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore
    • F03B13/1845—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem
    • F03B13/1875—Adaptations of machines or engines for special use; Combinations of machines or engines with driving or driven apparatus; Power stations or aggregates characterised by using wave or tide energy using wave energy using the relative movement between a wave-operated member, i.e. a "wom" and another member, i.e. a reaction member or "rem" where the other member, i.e. rem is fixed, at least at one point, with respect to the sea bed or shore and the wom slides relative to the rem and the wom is the piston or the cylinder in a pump
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2220/00—Application
    • F05B2220/70—Application in combination with
    • F05B2220/706—Application in combination with an electrical generator
    • F05B2220/707—Application in combination with an electrical generator of the linear type
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F05—INDEXING SCHEMES RELATING TO ENGINES OR PUMPS IN VARIOUS SUBCLASSES OF CLASSES F01-F04
    • F05B—INDEXING SCHEME RELATING TO WIND, SPRING, WEIGHT, INERTIA OR LIKE MOTORS, TO MACHINES OR ENGINES FOR LIQUIDS COVERED BY SUBCLASSES F03B, F03D AND F03G
    • F05B2260/00—Function
    • F05B2260/40—Transmission of power
    • F05B2260/406—Transmission of power through hydraulic systems
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N35/00—Magnetostrictive devices
    • H10N35/101—Magnetostrictive devices with mechanical input and electrical output, e.g. generators, sensors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/30—Energy from the sea, e.g. using wave energy or salinity gradient

Definitions

  • the device for generating electrical energy from mechanical motion includes a surface float and at least one force modifier disposed at least partially within the interior of the surface float, the force modifier to receive an input force at a pumping cylinder and apply a modified force to a generator through a driving cylinder.
  • the pumping cylinder or the driving cylinder is a tandem cylinder.
  • Other embodiments of the device for generating electrical energy from mechanical motion are also described.
  • the generator is a linear actuated generator. In some embodiments, the generator is a variable reluctance magnetostrictive generator. In some embodiments, the modified force applied to the generator is greater in magnitude than the input force. In some embodiments, the modified force applied to the generator is smaller in magnitude than the input force. In some embodiments, the generator is a high-displacement, multi-pole generator. In some embodiments, the pumping cylinder includes a pumping tandem cylinder and the driving cylinder includes a driving tandem cylinder.
  • Embodiments of a method for generating electrical energy from mechanical motion include receiving an input force from a mechanical motion, modifying the input force to an output force, and applying the output force to a generator disposed within an interior of a surface float. Modifying the input force includes receiving the input force at a pumping cylinder and converting the input force to an output force at a driving cylinder.
  • the pumping cylinder includes a pumping tandem cylinder or the driving cylinder includes a driving tandem cylinder.
  • Other embodiments of a method for generating electrical energy from mechanical motion are also described.
  • Fig. 1A depicts an embodiment of a configuration of a linear generator where input wave forces are translated to lower displacement and higher forces.
  • Fig. IB depicts an embodiment of a configuration of a linear generator where input wave forces are translated to higher displacement and lower forces.
  • Fig. 2A depicts one embodiment of a wave energy converter including a surface float, a heave plate, and a plurality of tethers.
  • Fig. 2B depicts one embodiment of a surface float, with the surface float partially transparent to show internal components.
  • Fig. 3 depicts one embodiment of a graphical depiction of power and damping plotted against wave period.
  • Fig. 4 depicts an embodiment of a configuration of a linear generator with tandem cylinders.
  • Fig. 5 depicts one embodiment of a magnetostrictive generator with a closed loop flux path.
  • Fig. 6 depicts a schematic diagram of an embodiment of a wave energy converter system.
  • Some embodiments describe a high reliability, variable-damping linear drivetrain concept, which combines a linear hydraulic "gear-box" and a linear generator solution to provide high reliability and active variability. This design enables high energy capture by tuning across a wide range of conditions, require minimal scheduled maintenance and can operate successfully over the system lifetime.
  • Some embodiments combine a nearly hydrostatic linear hydraulic gearbox 210 with a linear generator 212, which may be a multi-pole linear generator 212 or an innovative, highly reliable variable reluctance generator 212.
  • the linear gearbox 210 which operates similarly to a hydraulic press, translates highly variable wave generated linear mechanical energy into loads and displacements of an optimal magnitude to maximize performance of both these classes of linear generators 212.
  • the linear hydraulic gearbox 210 may be used with high- force, low-displacement, variable reluctance magnetostrictive power generator 212, where the optimal input to the generators 212 is a high force, low displacement input ( Figure 1A).
  • Variable reluctance is achieved through the use of magnetostrictive alloys and/or a variable air gap in the generator 212.
  • this version of linear drive-train can enable high-efficiency, wide-band energy capture from ocean waves with a relatively simple (i.e., highly reliable and low cost) prime mover such as Oscilla Power Inc.' s ("OPI”)
  • OPI Oscilla Power Inc.' s
  • Triton(TM) wave energy converter (“WEC”), a point absorber that captures energy from both heave and pitch (see e.g. , Figs. 2A and 2B).
  • the linear hydraulic gearbox 210 can be used with linear generators 212.
  • the function of the linear hydraulic gearbox 210 is analogous to a rotary gearbox (increasing linear velocity rather than RPM) ensuring that the input force is tuned so that the linear generator 212 can be substantially smaller for the same capacity, and operates at high efficiency (Figure lb).
  • PTO power takeoff
  • the linear drivetrain can enable a power takeoff (PTO) solution that can be configured for use with a wide range of wave energy converters, ranging from point absorbers and attenuators to Oscilla Power's Triton device, a multi-mode point absorber.
  • PTO power takeoff
  • the linear drivetrain promises to enable high conversion efficiency across the wave spectrum without sacrificing cost or reliability, with only minimal scheduled maintenance over the system's 20+ year lifetime.
  • the linear drivetrain described herein comprises a linear hydraulic gearbox 210 coupled with one of a number of different linearly actuated generator 212 concepts ranging from a very stiff variable reluctance generator 212 (e.g., OPI's magnetostrictive generator 212) to a high-displacement, multi-pole generator 212.
  • a very stiff variable reluctance generator 212 e.g., OPI's magnetostrictive generator 212
  • the linear gearbox 210 allows the wave-generated forces from the marine system to be manipulated and adjusted for application to a linear generator 212 so that the generator 212 can operate at maximum efficiency.
  • This operation can be seen to be somewhat analogous to a rotary gearbox 210, which converts input rotary energy at one RPM into a different (usually higher) RPM that is more suitable for optimal performance of a rotary generator 212.
  • this is achieved through a simple, nearly hydrostatic system similar to that used in a hydraulic press, whereby a compressive force on one cylinder is transferred directly to another cylinder with a different piston area, thereby applying an amplification ratio that is dependent upon the ratio of the piston areas.
  • linear gearbox 210 offers many drivetrain options that embody trade-offs between technical risk and maintenance cost.
  • a multi-pole linear generator 212 At the one end of this scale is a multi-pole linear generator 212.
  • the linear gearbox 210 provides an effective spring and damping coefficient that is optimized for the wave environment, and this captured mechanical energy can be transferred to linear generators 212 with an appropriately amplified displacement/velocity.
  • This approach could reduce required generator 212 mass and cost substantially, to the point where the generator 212 only employs components suitable for high- volume manufacturing. Further, this decouples generator 212 sizing from the available float displacement, providing flexibility that can be used to minimize cost and maximize reliability.
  • variable reluctance generators 212 offer the possibility for significantly more reliable system performance. Integration of a variable reluctance generator 212 with a linear gearbox 210 enables this advantage to be maximized.
  • variable reluctance is driven by changing the stress on magneto strictive components of the magnetic flux path. The magnetic permeability of these components, and thus the reluctance of the magnetic flux path, is a function of stress.
  • the variable reluctance can be due to elastic extension of components that control a variable air gap within a magnetic circuit.
  • the key advantages are high reliability (due to the low displacements involved in the linear gearbox 210), and the fact that no end-stops or high-displacement return springs are needed. In effect, the return spring is built into the system from the elastic deflection of the generator 212 itself.
  • the damping coefficient 302 required for maximum power generation 304 increases as the incident wave period 306 becomes longer than the WEC's natural period. This is illustrated in Figure 3.
  • Conventional generators struggle to operate efficiently or reliably at the higher damping values required for longer wave periods, and therefore the overall efficiency drops significantly in this region.
  • OPI's magnetostrictive generator 212 has an intrinsically high damping coefficient, enabling it to operate more efficiently and reliably in this region.
  • a conventional generator 212 may have a higher efficiency than a magnetostrictive generator 212, but it will also have higher displacements, which will need to be carefully accommodated to ensure high reliability.
  • This advantage is especially important as it enables better matching of the device to the input wave so as to allow a smaller (lower cost) float to provide the same energy capture as that provided by a larger unit (i.e., heavy, expensive).
  • the intrinsically high damping of OPI's magnetostrictive generator 212 improves efficiency in this non-resonant regime; in conjunction with a lower cost structure these gains more than compensate for reduced performance (relative to conventional generators) in resonant conditions.
  • These "no moving parts" power generators 212 have closed magnetic paths made of steel and load- bearing, magnetostrictive iron-aluminum (Fe-Al) rods.
  • the driving magnetomotive force in each generator 212 is provided by small permanent magnets that make up a very small fraction of the generator's 212 mass.
  • OPI's Triton WEC the mechanical energy captured from the waves by the system is transmitted to the generators 212 through the tethers 202 as a high force, low displacement mechanical energy input.
  • the stress changes imposed on the generators 212 create substantial changes in the magnetic permeability of the Fe-Al rods, resulting in changes in the flux density in the magnetic circuit.
  • Electricity is generated by electromagnetic induction, using copper or aluminum coils wound around the alloy rods, with essentially no relative motion. The current in the coil produces a force that is opposite to the change in magnetic flux, and therefore opposite to the applied force, resulting in electromechanical coupling.
  • the linear drivetrain will be optimized initially for use with the Triton WEC. While the baseline diameter for the Triton WEC's surface float 206 is 27 m, OPI aims to reduce it through the application and optimization of the PTO system described here to reduce extreme loads and minimize system mass.
  • each tether 202 is connected mechanically to a linear gearbox 210 through a load transfer unit 208 ("LTU") that eliminates off-axis loads ⁇ e.g., a tether coupling point).
  • LTU load transfer unit 208
  • the LTU 208 is a vertically oriented cylinder comprised of a sea-water lubricated bearing material around steel, attached to the tether 202 at the bottom and to the linear gearbox 210 at the top. The cylinder moves within a steel tube that was a structural part of the surface float 206.
  • Some embodiments include a similar design, scaled up to accommodate the higher loads.
  • the input wave forces will be realized as tension changes in the tethers 202 that are applied directly to 'pumping' cylinders 102.
  • Linear gearboxes 210 connect each of the cylinders to four variable reluctance generators 212.
  • a system would have three 'pumping' cylinders, three linear gearboxes 210 and twelve discrete generators 212.
  • Other configurations are envisioned within the scope of this disclosure.
  • each generator 212 is actuated by a 'driving' hydraulic cylinder whose sizing depends on the nature of the generator 212.
  • the Triton WEC's variable reluctance generators 212 require a very high force, low displacement energy, so the linear gearbox 210 applies a positive ratio of force (i.e., a small diameter pumping cylinder 102 is connected to the input force while a large diameter driving cylinder 104 acts upon the generator 212) such that a low magnitude, high displacement input is translated into high magnitude, low displacement output.
  • a large diameter pumping cylinder 102 is connected to the input force while a small diameter cylinder acts upon the generators 212 so that displacement is amplified.
  • the pumping cylinder 102 is a triple tandem cylinder, while each generator 212 is driven by tandem driving cylinders 104.
  • the gearboxes 210 operating states can be described as follows (see Figure 4): [0040] 1. Under operational waves, a single chamber (e.g. , first pumping chamber 112) in the pumping cylinder is connected to the both of the chambers (e.g., first driving chamber 114 and second driving chamber 124) in the driving cylinder 104, providing a particular amplification ratio.
  • the pumping cylinder 102 switches to the smaller diameter chamber (e.g. , second pumping chamber 122), providing a higher amplification ratio, lower system compliance, and increased displacement, which increases the loads to the generator 212 (until maximum displacements are reached).
  • the smaller diameter chamber e.g. , second pumping chamber 122
  • first pumping chamber 112 and second pumping chamber 122 are connected to only one of the driving cylinder chambers (e.g. , one of first driving chamber 114 or second driving chamber 124), further lowering the amplification ratio and limiting the maximum force that can be applied to the each generator 212.
  • the survival configuration (4) will be further enhanced by adding energy dissipation into the hydraulic system. This would be completed by diverting flow from the primary hydraulic loop through a series of orifices (pressure reducing valves) designed to dissipate the energy in the fluid by creating pressure drops and consequently heating the fluid, which can then be dissipated through a seawater-cooled heat exchanger.
  • orifices pressure reducing valves
  • One challenge is that by switching to a higher load multiplier, the travel of the pumping cylinder 102 also increases and there is the risk that this could result in excessive cylinder travel and requirement for end-stops.
  • Some embodiments choose an amplification factor and operating point that maximizes the travel of the float, while not requiring significantly more travel than can be reasonably accommodated.
  • Some embodiments are intrinsically more reliable than conventional hydraulics used in WECs as the use of a nearly hydrostatic system results in low travel, low flow, low heat and low frequency - key factors that enable high-reliability hydraulic systems.
  • Possible combinations of a linear gearbox 210 and a linear generator 212 include: Magnetostrictive generator 212, Variable air gap generator 212, Magnetostrictive + variable air gap generator 212, a multi-pole generator 212, or combinations thereof.
  • Magnetostrictive generators 212 are a class of variable reluctance generators 212 that have unique reliability, integration and cost advantages due to the fact that the spring elements are built into the generator 212 itself and that very little displacement is needed (Figure 5). Based on the principle of reverse magnetostriction, in which certain ferromagnetic alloys experience significant magnetic permeability changes when subjected to changes in stress, the Triton WEC's magnetostrictive generators 212 require no relative motion. Power is produced via electromagnetic induction from magnetic flux changes caused by very small, compression-induced deformations of the magnetostrictive alloys. The generators 212 require high forces, but very low displacements (and velocities), and thus can provide very high damping coefficients.
  • These generators 212 have closed magnetic paths composed largely of steel and magnetostrictive iron-aluminum (Fe-Al) cores.
  • the driving magnetomotive force is provided by permanent magnets that are a very small fraction of the generator 212 mass.
  • the Triton WEC interacts with ocean waves, the motions of the surface float 206 relative to the heave plate 204 generate significant changes in tether 202 tension, which are transmitted to the generators 212 as high force, low displacement mechanical energy via the linear hydraulic gearbox 210.
  • These stress changes result in substantial changes in the magnetic permeability of the Fe-Al cores, resulting in changes in the flux density in the magnetic circuit.
  • Electricity is generated by electromagnetic induction, using copper or aluminum coils wound around the alloy rods, with no relative motion of the coil and core. The current in the coil produces a force that is opposite to the change in magnetic flux and the applied force, resulting in electromechanical coupling.
  • the operating principle of the linear gearbox 210 is analogous to a rotary gearbox in that it allows optimum matching of the input driving forces to the generator 212 input forces so as to keep the generator 212 operating at maximum efficiency.
  • the gearbox's design allows for the load or velocity amplification level to change automatically during operation based on the wave state, enabling generator 212 displacements to be maintained at an optimum level that is largely independent of the WEC's displacement. Additionally, such a system provides for the introduction of various non- continuous control strategies such as latching and declutching without imposing excess loadings on the generator 212 or marine system.
  • Another unique aspect of the linear drivetrain is its ability to use variable reluctance generators 212, such as OPI's
  • magneto strictive generator 212 This generator 212 provides greatly increased reliability over moving magnet designs due to the minimal displacement and zero core motion relative to coil motion.
  • the linear drivetrain may enable wider power bandwidth and increased reliability at an attractive cost structure for a very wide range of WECs,
  • variable reluctance generators 212 While the use of the linear drivetrain enables the incorporation of variable reluctance generators 212, it is equally feasible to combine the linear hydraulic gearbox 210 with multi-pole linear generators 212. These two options present different value propositions, with the variable reluctance systems offering very high reliability and wide-band energy capture, and the linear generator 212 based system offering high top line energy conversion efficiencies and reduced generator 212 mass. The choice of the optimal architecture, driven by LCOE, will be unique to a specific wave environment.
  • FIG. 2A and 2B One example of a WEC that the drivetrain described in some embodiments may be used with is shown in Figures 2A and 2B, in which the Triton comprises of a catenary moored surface float 206 connected to a sub-surface heave plate 204 by taut tethers 202, with the linear drivetrain located inside the surface float 206.
  • This design which captures energy from the heave, pitch and roll motion of the surface float 206, has significant reliability, performance, operability, survivability and installation advantages compared with other WECs, while maintaining a very attractive cost structure, high reliability and high
  • the Triton WEC can include, but is not limited to, 12 individual generators 212, arranged in six sets of two, with the output of each set being 170kW under rated operational sea conditions. The aim therefore is that the device will be capable of delivering 1 MW under rated conditions.
  • variable reluctance (magneto strictive or variable air gap) generators 212 with low displacement, integral spring and high damping.
  • Cost and reliability remain as critical obstacles to the commercialization of wave energy converter (WEC) technologies. Costs of "mature" devices are currently estimated to be 3-10 times their required level and private investors have not shown a strong interest in financing deployments to drive the learning curves required to allow today' s technologies to achieve our collective objectives. Some embodiments have the potential to deliver a very low levelized cost of electricity. This low cost structure is largely enabled by the following features of the linear drivetrain, which are extensible to a wide range of WECs:
  • a linear drivetrain with variable reluctance generators 212 e.g., OPI's magnetostrictive generators 212
  • OPI's magnetostrictive generators 212 enables the elimination of moving magnet assemblies and associated sub-system (e.g., lubrication, bearings) costs.
  • Usage of the linear drivetrain will significantly reduce operations and maintenance costs of a WEC due to the reduction of the need to periodically service joints, bearings, and other such components.
  • the materials sets for ⁇ s linear drivetrain do not include significant quantities of any supply limited or expensive materials.
  • materials include aluminum, iron, copper, and steel.
  • Some embodiments include only small amounts of permanent magnet - less than 0.1% of the total generator 212 weight - are used in variable reluctance generators 212. Concrete and glass-reinforced plastic may also be used may be used in the heave plate 204 and surface float 206, respectively.
  • the linear gearbox 210 improves performance across the wave spectrum: By optimally coupling the input forces with those required by an electromagnetic generator 212, the linear gearbox 210 enables much improved power performance across the full range of wave heights, significantly increasing efficiency in small waves by altering the load and displacement transfer ratio. In addition, the linear gearbox 210 enables the introduction of high-reliability active control strategies, which holds the potential to further improve power capture in periods away from device resonance.
  • End stops are a requirement for any linearly actuated wave energy device to prevent excess displacements and system damage in the case of large waves.
  • the combination of a linear gearbox 210 and a variable reluctance generator 212 (or a linear generator 212 with additional return spring functionality added to the gearbox 210) provides an increasing force-displacement curve that provides a natural limit to displacement as the input force increases. Additionally, in order to manage extreme events, the gearbox 210 can be adjusted to limit the force-displacement curves of both the primary input and the generator 212 output.
  • the linear gearbox 210 system allows the ability to implement active device control on a wave-by-wave basis.
  • Active control strategies such as latching or declutching can be implemented through manipulation of valves 402, 404, 406 within the system and there maybe the possibility of applying more advanced control strategies such as reactive or complex conjugate control, although at the cost of increasing system complexity.
  • the introduction of active control provides the ability to increase device power output in smaller waves and provide a significant benefit in terms of AEP.
  • Embodiments described herein may have uses with various other types of wave energy converters, including, but not limited to the ones described below.
  • the primary hydraulic driving cylinders 104 can provide the primary linear input to the linear gearbox 210 and enable the use of a variable reluctance or linear generator 212, rather than being limited to a rotary hydraulic generator 212.
  • Use of such a linear drivetrain that enables a high degree of adjustment of effective damping and stiffness, can increase the energy capture across the wave spectrum.
  • Point Absorber Some embodiments are directly applicable to any devices in this category that currently use a linear generator 212, and may offer a significant improvement to other devices that use flexible tethers 202 to drive a rotary drivetrain.
  • Oscillating Surge Wave Converter In some embodiments such as an OWSC type device, a hydraulic cylinder connected to the surge flap would provide the primary linear input to the linear gearbox 210 and enable the use of a variable reluctance or linear generator 212, rather than being limited to onshore or offshore rotary hydraulic generators 212.
  • Embodiments of the invention described herein may be used outside of wave energy, including, but not limited to downhole oil and gas applications.
  • the forces and vibrations present just above the drill bit are converted into small amounts of reliable power during drilling operations.
  • This power will be used to enhance the operating and/or telemetry capabilities of measurement-while-drilling (MWD) and logging- while-drilling (LWD) sensors used to assess the position and direction of the drill bit as well as the characteristics of the surrounding environment.
  • MWD measurement-while-drilling
  • LWD logging- while-drilling
  • the generator 212 for this application which meets the key form factor and robustness specifications for the application, has already demonstrated achievement of the target power levels.
  • concepts have also been developed for devices that can continuously produce small amounts of power from hydrocarbon flow in completed wells to power downhole sensors and valves that can enable more efficient production.
  • OPI's linear drivetrain has strong potential to achieve high power capture and high conversion efficiency.
  • the former is achieved through the linear gearbox's 210 ability to adjust the effective generator 212 parameters to match the sea-state and, when used with variable reluctance generators 212, by having the capability to operate at higher damping levels than conventional systems.
  • the latter can be achieved through the use of linear generators 212 operating under optimum motions (as enabled by the linear gearbox 210).
  • Such ultra-high efficiency designs may trade off reliability with efficiency.
  • OPI's linear drivetrain has the potential to enable a significantly improved cost structure for a number of wave energy converters: (1) high power capture for a given size of device, as described in 6.2.1 and high availability as described in 6.2.3, (2) low CAPEX, enabled by simple hydraulic systems that are easily manufactured, and by generator 212 designs amenable to high volume manufacturing.
  • OPI's linear drivetrain can offer a step change in reliability to the wave energy industry.
  • the linear gearbox 210 based is a fundamentally more reliable approach relative to hydraulic systems that employ rotary generators 212 due to the relative simplicity and durability of the parts involved.
  • Some embodiments of the variable reluctance generator 212 described herein provide significant increases in reliability due to an architecture that eliminates the vast majority of moving parts compared to conventional generators.
  • OPI's linear drivetrain enables a survivable WEC design by being able to minimize prime-mover displacements and manage peak loads. Additionally, some embodiments have the ability to dissipate additional power (and hence generator 212 loads) in extreme conditions by using pressure reducing valves and transferring the energy into heat, which can be dissipated by seawater cooled heat exchangers.
  • Fig. 6 depicts a schematic diagram of an embodiment of a wave energy converter system 600.
  • the system includes a heave plate 204 connected to a force modifier through a tether 202 or plurality of tethers 202.
  • the tethers 202 connect to the force modifier at a tether coupling point 216.
  • the force modifier may include a gearbox 210 that modifies the input force from the tethers 202 to convert the input force into an output force on generator(s) 212.
  • the generator(s) 212 and the force modifier(s) may be wholly or at least partially disposed within an interior of a surface float 206.
  • the gearbox 210 may include a pumping cylinder 102, a driving cylinder 104, and a plurality of valves 402, 404, 406.
  • the pumping cylinder 102 which may incorporate a tandem cylinder, receives the input force from the tether 202 causing the fluid in the pumping cylinder 102 to actuate the driving cylinder 104, which may incorporate a tandem cylinder.
  • a plurality of valves may be disposed throughout the gearbox 210, before or after each of the chambers of the pumping cylinder 102 and/or driving cylinder 104.
  • the valves 402, 404, 406 may be situated in various configurations (not specifically described herein) to affect the modification of the input force into an appropriate output force.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)

Abstract

L'invention concerne un dispositif pour générer de l'énergie électrique à partir d'un mouvement mécanique, comprenant un flotteur de surface et au moins un modificateur de force disposé au moins partiellement à l'intérieur du flotteur de surface, le modificateur de force étant apte à recevoir une force d'entrée au niveau d'un cylindre de pompage et à appliquer une force modifiée à un générateur par le biais d'un cylindre d'entraînement. Le cylindre de pompage ou le cylindre d'entraînement est un cylindre en tandem.
PCT/US2016/052304 2015-09-16 2016-09-16 Système de prise de force pour convertisseur d'énergie des vagues WO2017049200A1 (fr)

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US201562219573P 2015-09-16 2015-09-16
US62/219,573 2015-09-16
US15/268,341 US10352291B2 (en) 2008-07-07 2016-09-16 Power take off system for wave energy convertor
US15/268,341 2016-09-16

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4296677A (en) * 1979-06-25 1981-10-27 Mcdonnell Douglas Corporation Tandem hydraulic actuator
US20100207390A1 (en) * 2007-07-02 2010-08-19 Stefan Zimmermann Converter and method for converting mechanical energy into electrical energy
WO2013140042A2 (fr) * 2012-03-20 2013-09-26 Aalto University Foundation Générateur de pression hydraulique adaptatif
US20140007568A1 (en) * 2011-03-23 2014-01-09 Michael David Crowley Power capture of wave energy converters
US20140225371A1 (en) * 2013-02-14 2014-08-14 Oscilla Power Inc. Magnetostrictive devices and systems
US20140305118A1 (en) * 2011-10-28 2014-10-16 Kam Wa Tai Energy Collector

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4296677A (en) * 1979-06-25 1981-10-27 Mcdonnell Douglas Corporation Tandem hydraulic actuator
US20100207390A1 (en) * 2007-07-02 2010-08-19 Stefan Zimmermann Converter and method for converting mechanical energy into electrical energy
US20140007568A1 (en) * 2011-03-23 2014-01-09 Michael David Crowley Power capture of wave energy converters
US20140305118A1 (en) * 2011-10-28 2014-10-16 Kam Wa Tai Energy Collector
WO2013140042A2 (fr) * 2012-03-20 2013-09-26 Aalto University Foundation Générateur de pression hydraulique adaptatif
US20140225371A1 (en) * 2013-02-14 2014-08-14 Oscilla Power Inc. Magnetostrictive devices and systems

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GB2557808A (en) 2018-06-27
GB201804991D0 (en) 2018-05-09

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