US20120313373A1 - Controller for pendulum type wave-power generating apparatus - Google Patents

Controller for pendulum type wave-power generating apparatus Download PDF

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US20120313373A1
US20120313373A1 US13/512,697 US201113512697A US2012313373A1 US 20120313373 A1 US20120313373 A1 US 20120313373A1 US 201113512697 A US201113512697 A US 201113512697A US 2012313373 A1 US2012313373 A1 US 2012313373A1
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hydraulic
pressure
wave
port
controller
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Seung-Ho Shin
Key-Yong Hong
Tomiji Watabe
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Korea Ocean Research and Development Institute (KORDI)
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Korea Ocean Research and Development Institute (KORDI)
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    • 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
    • F03B13/1805—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 is hinged to the rem
    • F03B13/181—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 is hinged to the rem for limited rotation
    • F03B13/182—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 is hinged to the rem for limited rotation with a to-and-fro movement
    • 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
    • F03B13/22—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 flow of water resulting from wave movements to drive a motor or turbine
    • 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
    • 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
    • F03B15/00—Controlling
    • 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
    • F03B15/00—Controlling
    • F03B15/02—Controlling by varying liquid flow
    • 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
    • F03G—SPRING, WEIGHT, INERTIA OR LIKE MOTORS; MECHANICAL-POWER PRODUCING DEVICES OR MECHANISMS, NOT OTHERWISE PROVIDED FOR OR USING ENERGY SOURCES NOT OTHERWISE PROVIDED FOR
    • F03G3/00—Other motors, e.g. gravity or inertia motors
    • F03G3/06—Other motors, e.g. gravity or inertia motors using pendulums
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B1/00—Installations or systems with accumulators; Supply reservoir or sump assemblies
    • F15B1/02—Installations or systems with accumulators
    • F15B1/04—Accumulators
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B11/00—Servomotor systems without provision for follow-up action; Circuits therefor
    • F15B11/16—Servomotor systems without provision for follow-up action; Circuits therefor with two or more servomotors
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B13/00—Details of servomotor systems ; Valves for servomotor systems
    • F15B13/02—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors
    • F15B13/06—Fluid distribution or supply devices characterised by their adaptation to the control of servomotors for use with two or more servomotors
    • 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
    • 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
    • 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
    • F05B2270/00—Control
    • F05B2270/10—Purpose of the control system
    • F05B2270/20—Purpose of the control system to optimise the performance of a machine
    • F05B2270/202—Tuning to wave conditions
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F15—FLUID-PRESSURE ACTUATORS; HYDRAULICS OR PNEUMATICS IN GENERAL
    • F15B—SYSTEMS ACTING BY MEANS OF FLUIDS IN GENERAL; FLUID-PRESSURE ACTUATORS, e.g. SERVOMOTORS; DETAILS OF FLUID-PRESSURE SYSTEMS, NOT OTHERWISE PROVIDED FOR
    • F15B2211/00—Circuits for servomotor systems
    • F15B2211/50—Pressure control
    • 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 present invention relates, in general, to controllers for pendulum type wave-power generating apparatuses.
  • Wave-power generation is a spectacular field that uses sea waves having high energy density, but commercialization has been delayed by the difficulty of reducing the cost of power generation.
  • Wave power is irregular wave energy, so it is difficult to handle it.
  • Commercialization is much more difficult, compared to other fields, because of the severe environmental conditions of the sea. The biggest problem is low power generation efficiency. Solving this problem has been pointed out as the basic priority.
  • the present invention relates, more particularly, to a controller for pendulum type wave-power generating apparatuses which controls the operation conditions of a pendulum type wave-power generating apparatus in response to the characteristics of sea waves so that high power generation efficiency can always be maintained regardless of variations in the state of the sea waves, thus reducing the cost of power generation.
  • Sea waves are composite waves that are a combination of different kinds of regular waves, but they are not completely irregular and have spectrum structures in which most energy is concentrated around regular waves of a specific height and frequency. Using such characteristics, sea waves are converted into regular waves of the same period as that of the center of the spectrum.
  • the response of wave-power generation with respect to the regular waves of specified wave height and frequency is checked using antenna theory.
  • a method of commercialization has been discovered that makes reference to the above behavior of the response. There is a close correspondence between wave-power generation and the antenna.
  • the antenna theory can be used as an effective tool when researching wave-power generation.
  • sea waves are not regular.
  • the waveform of sea waves is distorted with respect to that of a sine wave.
  • the wave height and wave length are also not constant.
  • the wave nature can be obviously read from the sea waves.
  • sea waves are regarded as semi-regular waves and as a kind of wave motion which continuously varies within a regular pattern. Therefore, with regard to wave-power generation, if parameters of a generation apparatus are adjusted (optimized) in response to variation of characteristics attributable to the irregularity of the sea waves, that is, in response to a variation in conditions, satisfactory power generation can be automatically maintained. For this, development of a controller for wave-power generating apparatuses that can reduce the cost of power generation is required.
  • a first object of the present invention is to control the output volume value (the size of output volume) of a hydraulic motor in response to a variation in irregular sea waves such that the generation load is optimized, thus automatically maintaining satisfactory power generation, thereby reducing the cost of power generation.
  • a second object of the present invention is to cope with variation in the state of sea waves without using a separate wave height meter, in an effort to realize a reduction in the cost of power generation.
  • the wave height meter is not only very expensive but also requires high technology to process obtained data, thus making common on-line use of it difficult. If data about irregular waves could be obtained without using a wave height meter, the practical effect of a wave-power generating apparatus would be markedly enhanced.
  • the present invention provides a controller for a pendulum type wave-power generating apparatus converting a pendulum motion of wave-power energy into a rotary motion using a hydraulic transmission that has pressure accumulators ( 31 ) and ( 41 ) on a hydraulic circuit thereof, thus operating a generator ( 60 ), the controller including: pressure control valves ( 33 ) and ( 43 ) controlling output volumes of hydraulic motors ( 32 ) and ( 42 ) that operate the generator ( 60 ) such that the output volumes are proportional to mean hydraulic pressures in pipes ( 30 ) and ( 40 ) of the hydraulic circuit so that a mean value of wave-power energy input into the hydraulic circuit is equal to a mean value of a drive force of the generator ( 60 ), whereby wave-power energy is able to be used regardless of a variation in wave conditions on the sea.
  • a pendulum type wave-power generation apparatus is characterized in that it can be constructed at a comparatively low cost and the efficiency thereof is superior. For instance, in the case of a unit apparatus, estimated unit generation cost has been reported as being ⁇ 0.085$/kWh, so it has already reached a practicable level.
  • a controller for pendulum type wave-power generating apparatuses according to the present invention can further reduce unit power cost compared to the level of the conventional technique.
  • the present invention can reliably eliminate the obstacle (the problem of the high cost of power generation) to commercializing the wave-power generation. Therefore, the present invention makes it possible to devise a detailed plan for using wave-power energy as well as measures to cope with stormy conditions, thus promoting the commercialization of wave-power generation.
  • the controller for pendulum type wave-power generating apparatuses has a simple and strong structure, thus ensuring the sufficient durability against conditions of the sea.
  • FIG. 1 is a system circuit view showing the structure of a pendulum type wave-power generating apparatus provided with a controller for pendulum type wave-power generating apparatuses according to an embodiment of the present invention to improve the power generation efficiency.
  • FIG. 2 is of front sectional views of an embodiment of a pressure control valve showing an initial stage of operation of a pendulum in which internal valve pressure is increasing.
  • FIG. 3 is of front sectional views showing an embodiment of the pressure control valve which transmits a control signal of an increase of the output volume of a hydraulic pump as the valve pressure (P 3 ) is reduced, according to the present invention.
  • the present invention has the following characteristics in order to achieve the above-mentioned objects.
  • a pendulum type wave-power generating apparatus converts pendulum motion of wave-power energy into rotary motion using a hydraulic transmission that has pressure accumulators 31 and 41 on a hydraulic circuit thereof, thus operating a generator 60 .
  • a controller for the wave-power generating apparatus includes pressure control valves 33 and 43 which control the output volumes of the hydraulic motors 32 and 42 that operate the generator 60 such that they are proportional to mean hydraulic pressures in pipes 30 and 40 of the hydraulic circuit so that the mean value of wave-power energy input into the hydraulic circuit is equal to the mean value of the drive force of the generator 60 , thus making it possible to use wave-power energy regardless of variations in the state of the waves on the sea.
  • the pressure control valves 33 and 43 use the force of the wave-power energy as input signals and transmit pressures proportional to the input signals to the generator 60 as output signals, wherein the mean hydraulic pressures of the hydraulic circuit are used as the input signals.
  • the hydraulic transmission includes: a pump 20 , which is connected to a pendulum 11 that swings in a pendulum motion resulting from variations of the wave; the hydraulic motors 32 and 42 , which are respectively connected to the pipes 30 and coupled to the opposite ends of the pump 20 ; and the generator 60 , which is operated by the hydraulic motors 32 and 42 .
  • the pressure accumulators 31 and 41 respectively accumulate and store pressures P 1 and P 2 in the pipes 30 and 40 of the hydraulic circuit.
  • the pressure control valves 33 and 43 are configured such that if the mean hydraulic pressures of the pipes 30 and 40 connected to the hydraulic motors 32 and 42 of the hydraulic transmission differ from each other and the difference between the mean hydraulic pressures exceeds a preset limiting value, a switching valve 50 communicates the pipes 30 and 40 connected to the hydraulic motors 32 and 42 with each other so that the mean hydraulic pressures in the pipes 30 and 40 of the hydraulic motors 32 and 42 become the same.
  • Each of the pressure control valves 33 and 43 includes: a first port 100 which is connected to the corresponding pipe 30 , 40 of the hydraulic circuit and into which the hydraulic pressure P 1 , P 2 is input; a cylinder 110 into which the hydraulic pressure P 1 , P 2 is applied from the first port 100 ; a damper 111 which is installed in the cylinder 110 and is moved upwards or downwards by the hydraulic pressure P 1 , P 2 applied thereto from the first port 100 ; a third elastic member 113 which is contracted by the hydraulic pressure P 1 , P 2 applied to the damper 111 from the first port 100 ; a chamber 120 in which a spool 122 is moved upwards or downwards by the damper 111 , thus increasing or reducing a valve pressure P 3 in the chamber 120 ; first and second elastic members 121 and 123 which are respectively installed on and under the spool 122 and are expanded or contracted depending on the movement of the spool 122 ; a second port 130 through which the hydraulic pressure P 1 , P 2 of the hydraulic
  • Each pressure control valve 33 , 43 transmits the valve pressure P 3 in the chamber 120 , which is increased or reduced by the hydraulic pressure P 1 , P 2 transmitted through the first port 100 or the second port 130 , to a servo 35 , 45 of the hydraulic motor 32 , 42 through the fourth port 150 as a control signal. If the valve pressure P 3 is increased, the control signal is transmitted such that the output volume is reduced. If the valve pressure P 3 is reduced, the control signal is transmitted such that the output volume is increased.
  • the case where the output volume of the hydraulic motor 32 , 42 is increased refers to the case where as the wave-power energy increases, the pressure in the pipe 30 , 40 increases so that the damper 120 and spool 122 are moved upwards by the hydraulic pressure P 1 , P 2 from the fist port, thus increasing the valve pressure P 3 .
  • the controller of the pendulum type wave-power generating apparatus converts the pendulum motion into constant high-speed rotation using the hydraulic transmission, thus operating the generator 60 .
  • the pressure accumulators (spring pressure accumulators) 31 and 41 are provided on the hydraulic circuit.
  • the controller smoothens the output of power generation using the characteristics of the pressure accumulators and, simultaneously, calculates an incident wave from the mean value of the circuit pressure (the mean hydraulic pressure in the hydraulic circuit pipe) and controls the output volume of the hydraulic motors 32 and 42 such that they correspond to the incident power.
  • the impedance matching state can be maintained.
  • the pendulum type wave-power generating apparatus using the controller of the present invention is focused on the wave nature of the sea and accelerates the pendulum 11 using periodic wave-power, thus generating the pendulum motion that resonates with the wave.
  • the hydraulic transmission converts the pendulum motion into rotary motion, thus operating the generator 60 .
  • the apparatus is characterized in that if two conditions of the resonance and impedance matching are satisfied, the power generation efficiency is maximized (in the same manner as that of an antenna). In other words, the same method as optimizing the antenna can be used in the wave-power generation. If the wave of the sea is constant like an electric wave, the method of the antenna can be directly used in the wave-power generation and the optimization of the system is possible. However, because the waves of the sea cannot be constant, the present invention uses the following means.
  • Statistical data about the sea waves that has been collected by a separate process are organized, and characteristics of power, wave heights and periods are arranged in a database.
  • the characteristics are the mean of data obtained after have been continuously measured for a predetermined time period (e.g., 20 minutes) rather than being obtained in a single measurement.
  • the mean wave height or the mean period can be obtained, so that the mean power corresponding to them can be determined.
  • the present invention indirectly measures the mean wave height without using a separate wave height meter, determines the mean power using the wave height, and controls the hydraulic motors 32 and 42 depending on the mean wave height so that the output volumes of the hydraulic motors 32 and 42 are optimized. Thereby, the efficiency of wave-power generation can be markedly enhanced.
  • the present invention uses a transmission circuit that is configured such that the resonance and impedance matching of each wave can be approximated.
  • a transmission circuit that is configured such that the resonance and impedance matching of each wave can be approximated.
  • the discharge rate of the pump 20 (the flow rate supplied to the hydraulic motors 32 and 42 ) is increased, so that the mean pressure of the hydraulic circuit that is provided with the hydraulic motors 32 and 42 (that is, the pressures P 1 and P 2 in the pipes 30 and 40 of the hydraulic circuit) is increased.
  • the output volumes of the hydraulic motors 32 and 42 are extended so that the outputs of the hydraulic motors 32 and 42 are increased, the consumption flow rate increases, thus reducing the mean pressure of the hydraulic circuit (of the pipes 30 and 40 of the hydraulic circuit).
  • the mean pressure of each of the pipes 30 and 40 of the hydraulic motors also is a parameter that indicates the status of supply and demand of energy used in the generation. In the present invention, this parameter is used as a control signal.
  • the output (Lm) of the hydraulic motor at a constant speed is proportional to the torque of the motor.
  • the torque (Tm) of the motor is proportional to a multiple of the pressure (P) by the output volume (Dm) of the motor, so that the output (Lm) of the hydraulic motor at a constant speed is proportional to P ⁇ Dm.
  • the present invention realizes the desired control using this relationship.
  • the hydraulic motors 32 and 42 used in the present invention refer to standardized products that comply with the above policy.
  • Each hydraulic motor 32 , 42 has a characteristic that adds or subtracts the output volume (Dm) of the motor using a pressure signal (analog).
  • the control method of the present invention is to control the output volume (Dm) of each hydraulic motor 32 , 42 using the pressure signal (analog) of the pressure control valve 33 , 43 .
  • the desired control can be easily implemented by the hydraulic analog method, but also the control signal 34 , 44 is transmitted through the thin pipe (connected to the fourth port 150 of the pressure control valve), so that there is no problem even though it is exposed to the sea water.
  • the present invention will be commercially available as a standardized product.
  • the power (from 10 to 20 times the design rating power) of the sea waves may destroy the apparatus.
  • a positive incident power-cut is needed to enhance the safety.
  • the power of the sea waves exceeds the design rating power, it is required to reduce the input power rather than to increase the power generation efficiency.
  • requiring the control effect of the present invention is limited to normal conditions in which the power of the sea waves is within the design rating power.
  • a normal ‘control error’ attributable to not using data about the period of the waves can be disregarded in practical use.
  • the power (force of the wave-power energy)(per unit width) of the sea waves: W(kW/m) is expressed by the following Equation (1).
  • the sea waves having such characteristics act as the input, thus operating the pendulum 11 . Then, the pendulum 11 swings and absorbs wave-power energy.
  • the absorbed power: E(kW) is expressed as the following Equation (2).
  • Equation (1) Equation (2)
  • Equation 3 must also be satisfied to realize the high efficiency operation.
  • the consumption rates are increased or reduced by adjusting the output volumes of the hydraulic motors 32 and 42 in response to the variation of the mean values of the pressures P 1 and P 2 of the pipes 30 and 40 so that the state of Equation (3) is satisfied, the high efficiency operation can be automatically maintained.
  • the pressure control valves 33 and 43 of the present invention increases or reduces the output volume (the size of output volume) of the hydraulic motors 32 and 42 in response to the pressures P 1 and P 2 of the pipes of the hydraulic circuit, thus reviving the impedance matching conditions, thereby stabilizing the mean value of each pipe pressure P 1 , P 2 at another predetermined value.
  • FIG. 1 is a system circuit view showing the structure of the pendulum type wave-power generating apparatus provided with the controller according to the embodiment of the present invention to improve the power generation efficiency. This will be explained in detail below.
  • the apparatus converts wave-power energy into the swing energy of the pendulum 11 and converts it into continuous rotary motion using the hydraulic transmission, thus operating the generator 60 , wherein because of the two factors of: ⁇ circle around (1) ⁇ the wave-power energy being efficiently used for the operation of the generator 60 ; and ⁇ circle around (2) ⁇ preventing period variation from occurring in the generation output are satisfied, the apparatus can be of practical use.
  • the structure and operation of the power generation system having the controller of the pendulum type wave-power generating apparatus according to the present invention will be described with reference to FIG. 1 .
  • This pendulum motion is transmitted to the pump (hydraulic pump 20 ).
  • the pump 20 sucks oil from a bed tank 21 and alternately sends pressing oil to the pipe ( 30 , referred to as ‘the first pipe’ for the sake of explanation, Pressure P 1 ) or the pipe ( 40 , referred to as ‘the second pipe’ for the sake of explanation, Pressure P 2 ) depending on the direction in which the pendulum 11 moves.
  • the pressure accumulator 31 is provided on the first pipe 30 .
  • the hydraulic motor 32 is connected to the first pipe 30 .
  • the pressure accumulator 41 is provided on the second pipe 40 .
  • the hydraulic motor 42 is connected to the second pipe 40 .
  • the hydraulic motors 32 and 42 operate as a pair on the generator 60 . Because there is a phase difference of 180° between the hydraulic motors 32 and 42 , periodic torque variations of the hydraulic motors 32 and 42 are offset by overlap between the two motors. Thereby, the output of power generation can become smooth.
  • One stroke of the oil discharge of the pump 20 includes discharging oil for a 1 ⁇ 2 T second to the hydraulic motor 32 , and resting for a subsequent 1 ⁇ 2 T second (the discharge rate per one stroke corresponds to the amount required to continuously rotate the hydraulic motor 32 for the one period of a T second).
  • the pressure accumulator 31 connected to the first pipe 30 and the pressure accumulator 41 connected to the second pipe 40 are of the spring type, wherein each increases the pressure in proportion to the volume of oil accumulated therein, and accumulated energy is proportional to the square of the volume of oil accumulated therein.
  • the pressure of the first pipe 30 varies depending on the size of the volume of oil accumulated in the pressure accumulator 31 .
  • the pressure of the second pipe 40 varies depending on the size of the volume of oil accumulated in the pressure accumulator 41 .
  • the swing angle of the pendulum 11 and the discharge rate of the hydraulic pump 20 are increased. Because the required flow rates of the hydraulic motors 32 and are constant, extra oil accumulates in the pressure accumulators 31 and 41 , so that the mean value of the pressure p 1 in the first pipe 30 and the mean value of the pressure P 2 in the second pipe 40 are increased.
  • the pressure control valve 33 receives the pressure P 1 as a control signal and controls the output volume Dm of the hydraulic motor 32 using its output signal, thus increasing the required flow rate of the hydraulic motor 32 .
  • the discharge rate of the hydraulic pump 20 is balanced with the required flow rate of the hydraulic motor 32 , so that the mean value of the pressure P 1 of the first pipe 30 is stabilized at a new value.
  • the pressure control valve 43 receives the pressure P 2 in the second pipe 40 as a control signal and controls the output volume Dm of the hydraulic motor 42 , thus increasing the required flow rate of the hydraulic motor 42 .
  • the discharge rate of the hydraulic pump 20 is balanced with the required flow rate of the hydraulic motor 42 , so that the mean value of the pressure P 2 of the second pipe 40 is stabilized into another new value.
  • Equation (4) Energy Ew(kNm) of an incident wave applied to the pendulum 11 of a width B for a period of a T second is expressed by the following Equation (4).
  • the hydraulic pressure P is proportional to a displacement x of the piston in the pressure accumulator 31 , 41 (therefore, it is proportional to the volume V of oil accumulated in the pressure accumulators 31 , 41 ).
  • the size of the swing angle of the pendulum is proportional to the incident wave height.
  • Equation (4) is proportional to the square of the wave height H
  • E 0 of Equation (5) is proportional to the square of the volume V
  • the volume V is proportional to the weight height H. Therefore, if an appropriate parameter is selected, in the state in which the parameter is fixed, the conditions of the impedance match, such as Equation (6) that is derived from Equations (4) and (5), are satisfied within a wide range of wave heights H.
  • the output volume Dm of each hydraulic motor 32 , 42 is increased or reduced depending on the variation in the discharge rate of the pump 20 .
  • the purpose of the pressure control valves 33 and 43 is to achieve the above purpose.
  • the pressure control valve 33 increases or reduces the output volume of the hydraulic motor 32 using the servo 35
  • the other pressure control valve 43 increases or reduces the output volume of the hydraulic motor 42 using the servo 45 .
  • the pressure P 1 in the first pipe is determined by the volume of oil accumulated in the pressure accumulator 31
  • the pressure P 2 in the second pipe is determined in the same manner as that of the pressure P 1 .
  • the pressures in the first and second pipes may vary. The reason for this is because although there is slight oil leakage, errors accumulate over a long period of time. If this compounding is neglected, power distribution between the two hydraulic motors 32 and 42 becomes unbalanced.
  • the switching valve 50 compares the control signal 34 of the pressure control valve 33 and the control signal 44 of the pressure control valve 43 , and if the difference between the two exceeds a predetermined limit, the switching valve 50 connects the first pipe to the second pipe, thus equalizing the pressures in the two pipes. After the pressures in the two pipes have been equalized, the connection between the two pipes is interrupted. Thereby, the balanced load distribution to the two hydraulic motors 32 and 42 can be automatically maintained.
  • FIGS. 2 and 3 are front sectional views showing the pressure control valve according to the present invention.
  • FIG. 2 illustrates one of the pressure control valves that is provided on the first pipe 30
  • the principle and structure thereof are the same as those of the pressure control valve provided on the second pipe 40 .
  • the pressure control valve includes a part which extracts the mean value of the pressure (hydraulic pressure, P 1 )(which is periodically varying) in the first pipe using a displacement of plunger 102 , and a spool type pressure control valve which converts the displacement into hydraulic pressure.
  • FIG. 2 will be explained with reference to the pressure control valve 33 provided on the first pipe 30 .
  • the plunger 102 is placed upright in the lower end of the pressure control valve 33 , and the hydraulic pressure P 1 of the first pipe 30 that has passed through an iris diaphragm 101 pushes the plunger 102 upwards with a force proportional to the pressure P 1 .
  • This force is transmitted to the third elastic member 113 via the damper 111 and makes an upward displacement proportional to the pressure (hydraulic pressure, p 1 ).
  • This is the pressure accumulator provided with a small damper.
  • the spool 122 may communicate the fourth port 150 of the pressure control valve 33 with the second port 130 or communicate the fourth port 150 with the third port 140 .
  • This operation is governed by the combination of three kinds of axial forces including the first and second elastic members 121 and 123 that are applied to the spool 122 and the valve pressure P 3 in the chamber 120 .
  • the second port 130 communicates with the fourth port 150 , so that the pressure P 1 is high when applied to the second port 130 through the first pipe 30 and applied towards P 3 of the chamber 120 .
  • the valve pressure P 3 in the chamber 120 is increased, thus pushing the spool 122 upwards in the chamber 120 .
  • the second port 130 that has been connected to the first pipe 30 is closed, so that the increase in the valve pressure P 3 in the chamber 120 stops.
  • the magnitude of the valve pressure P 3 is proportional to the intensity of the resultant force applied to the spool 122 downwards.
  • the valve pressure P 3 may decrease.
  • the damper 111 when the pressure in the first pipe 30 increases and the pressure p 1 is applied into the first port 100 , thus moving the plunger 102 upwards, the damper 111 is moved upwards. Then, the third elastic member 113 is compressed and a damper guide 116 is moved upwards, so that the second elastic member 123 is compressed and the force of the second elastic member 123 offsets the force of the first elastic member 121 that biases the spool 122 downwards, thus reducing the valve pressure P 3 in the chamber. At this time, the valve pressure P 3 is used as the control signal 34 of the output volume of the hydraulic motor 32 and is transmitted through the fourth port 150 .
  • the discharge rate of the hydraulic pump 20 is also increased.
  • the reduced valve pressure P 3 in the pressure control valve 33 is transmitted as the control signal through the fourth port 150 connected to the servo 35 of the hydraulic motor 32 .
  • the output volume of the hydraulic motor 32 is increased.
  • the reduced valve pressure P 3 in the pressure control valve 33 is transmitted as the control signal 34 , so that the output volume of the hydraulic motor 32 is increased (of course, as shown in FIG.
  • the first pipe 30 that transmits the pressure P 1 to the pressure control valve 33 and the second pipe 40 that transmits the pressure P 2 to the other pressure control valve 43 are connected to the switching valve 50 , so that when signals are transmitted from the pressure control valves 33 and 43 , the pressures (hydraulic pressures P 1 and P 2 ) in the first and second pipes 30 and 40 are applied to the switching valve 50 , and a member in the switching valve 50 is thus moved in one direction, thus connecting the first and second pipes 30 and 40 to each other, thereby balancing the pressures P 1 and P 2 in the first and second pipes 30 and 40 that have become unbalanced).
  • this embodiment illustrates the case where when the valve pressure P 3 is high, the output volume Dm is small, and as the valve pressure P 3 is reduced, the output volume Dm is increased (of course, as stated above, the principle of the above-mentioned operation is also applied in the same manner to the pressure control valve 43 provided on the second pipe 40 ).
  • the present invention is configured such that the variable constituent is prevented from being transmitted to the valve pressure P 3 .
  • the present invention is provided with the damper 111 .
  • the damper guide 116 is provided on the upper end of the damper 111 .
  • the damper 111 uses the inner surface of the cylinder 110 as a guide surface and is guided by the damper guide 116 , so that the damper 111 can be smoothly moved upwards or downwards by the movement of the plunger 102 .
  • the interior of the cylinder 110 is partitioned into a lower chamber 114 and an upper chamber 115 by the damper 111 .
  • a strong damping operation is conducted by oil flowing along a thin hole 112 which is formed between the two chambers.
  • This value is a short-time means value and takes into account the characteristics of the sea waves. It is greater than a long-time mean value obtained from Equation (4).
  • the capacity of each pressure accumulator 31 , 41 is 10 liters, and the maximum pressure thereof is 20 Mpa.
  • the diameter of the spool 122 ranges from 10 mm to 20 mm. This is not large as a control element.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Other Liquid Machine Or Engine Such As Wave Power Use (AREA)
US13/512,697 2011-04-08 2011-07-18 Controller for pendulum type wave-power generating apparatus Abandoned US20120313373A1 (en)

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Cited By (9)

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US20140007568A1 (en) * 2011-03-23 2014-01-09 Michael David Crowley Power capture of wave energy converters
CN103850867A (zh) * 2014-03-05 2014-06-11 天津大学 浮子式波浪能液压发电系统
WO2015063667A1 (en) * 2013-11-04 2015-05-07 Xhabija Blerina An energy generator exploiting tidal/ wave movements
US9356489B1 (en) * 2015-01-20 2016-05-31 John A. Saavedra Device and method for generating power using buoyancy
US20160186715A1 (en) * 2014-01-20 2016-06-30 Mitchell Fait Buoy for obtaining energy from a wave in a body of water
CN107559131A (zh) * 2017-08-25 2018-01-09 广东海洋大学 一种悬挂摆式与振荡水柱式耦合的波浪能发电装置
EP3751131A4 (de) * 2018-02-07 2021-09-08 The University of Tokyo System zur erzeugung von wellenenergie
CN115204347A (zh) * 2022-08-17 2022-10-18 山东方能毅装备科技有限公司 一种基于浮球的海浪计数装置
US11473552B2 (en) 2018-08-02 2022-10-18 The University Of Tokyo Wave power generation system

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FR3029241B1 (fr) * 2014-12-01 2019-05-03 Gilles Grosso Appareil pour convertir une energie de houle en energie electrique
CN105114238B (zh) * 2015-08-10 2018-06-08 华北电力大学（保定） 一种摆板式波浪能发电系统及其控制方法
CN105604774B (zh) * 2016-01-22 2017-04-19 上海交通大学 基于共振的振荡纵荡式波浪能转换器系统
CN107740746B (zh) * 2017-09-20 2019-06-21 中国科学院广州能源研究所 一种可自动增压的波浪能装置能量提取系统
KR101997489B1 (ko) * 2017-12-12 2019-07-08 유원산업(주) 배열 파력용 유압 ｐｔｏ 에너지 변환 시스템
KR102027553B1 (ko) 2018-03-09 2019-10-01 주식회사 인진 파력발전 시스템 및 그 제어 방법
CN110081039B (zh) * 2019-04-28 2020-09-04 深圳市中粤海洋能源科技有限公司 一种能量跟踪阀组及模块化洋流发电系统
CN112664487B (zh) * 2020-12-21 2022-08-30 浙江大学 一种循环式等比减压高压发电装置

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US20140007568A1 (en) * 2011-03-23 2014-01-09 Michael David Crowley Power capture of wave energy converters
WO2015063667A1 (en) * 2013-11-04 2015-05-07 Xhabija Blerina An energy generator exploiting tidal/ wave movements
US20160186715A1 (en) * 2014-01-20 2016-06-30 Mitchell Fait Buoy for obtaining energy from a wave in a body of water
CN103850867A (zh) * 2014-03-05 2014-06-11 天津大学 浮子式波浪能液压发电系统
US9356489B1 (en) * 2015-01-20 2016-05-31 John A. Saavedra Device and method for generating power using buoyancy
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CN107559131A (zh) * 2017-08-25 2018-01-09 广东海洋大学 一种悬挂摆式与振荡水柱式耦合的波浪能发电装置
EP3751131A4 (de) * 2018-02-07 2021-09-08 The University of Tokyo System zur erzeugung von wellenenergie
US11473552B2 (en) 2018-08-02 2022-10-18 The University Of Tokyo Wave power generation system
CN115204347A (zh) * 2022-08-17 2022-10-18 山东方能毅装备科技有限公司 一种基于浮球的海浪计数装置

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US20170089320A1 (en) 2017-03-30
EP2696065A2 (de) 2014-02-12
WO2012138014A3 (ko) 2013-03-07
KR20120115000A (ko) 2012-10-17
KR101206396B1 (ko) 2012-11-29
CN103403343B (zh) 2015-11-25
EP2696065A4 (de) 2014-12-24
US10253750B2 (en) 2019-04-09
EP2696065B1 (de) 2016-06-01
CN103403343A (zh) 2013-11-20

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