WO2010085188A1 - A wave power unit - Google Patents

A wave power unit Download PDF

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Publication number
WO2010085188A1
WO2010085188A1 PCT/SE2009/050072 SE2009050072W WO2010085188A1 WO 2010085188 A1 WO2010085188 A1 WO 2010085188A1 SE 2009050072 W SE2009050072 W SE 2009050072W WO 2010085188 A1 WO2010085188 A1 WO 2010085188A1
Authority
WO
WIPO (PCT)
Prior art keywords
wave power
power unit
contactor
electric
energy
Prior art date
Application number
PCT/SE2009/050072
Other languages
French (fr)
Inventor
Mats Leijon
Cecilia BOSTRÖM
Erik Lejerskog
Magnus Rahm
Olle Svensson
Original Assignee
Seabased Ab
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.)
Filing date
Publication date
Application filed by Seabased Ab filed Critical Seabased Ab
Priority to PCT/SE2009/050072 priority Critical patent/WO2010085188A1/en
Priority to EP09838966.1A priority patent/EP2389507A4/en
Publication of WO2010085188A1 publication Critical patent/WO2010085188A1/en

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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"
    • 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
    • F03B13/1885—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 tied to the 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
    • 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
    • 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
    • F05B2250/00—Geometry
    • F05B2250/40—Movement of component
    • 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
    • F05B2270/107—Purpose of the control system to cope with emergencies
    • F05B2270/1071—Purpose of the control system to cope with emergencies in particular sudden load loss
    • 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
    • F05B2270/30—Control parameters, e.g. input parameters
    • F05B2270/337—Electrical grid status parameters, e.g. voltage, frequency or power demand
    • 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 in a first aspect relates to a wave power unit includ- ing an electric generator arranged to be powered by wave energy, the generator having primary electric connection means for supplying energy to an electric network.
  • the invention also relates to a wave power plant including a plurality of such wave power units and to an electric network. In a second aspect of the invention it relates to a use of such a wave power unit.
  • the invention relates to a method of controlling such a wave power unit.
  • wave power units are powered by waves occurring on the surface of the sea. However also wave movements in the water beyond the sea ievel can be used for that, and the present invention is also applicable to wave power units powered by such waves.
  • the kinetic energy from the waves that is to be converted into electric energy in the generator will vary considerably. If the waves are very powerful the voltage supplied by the generator might be too high to match with the switchgear through which the electric energy is supplied to a network.
  • the object of the present invention is to solve this problem, and make the wave power unit, less sensitive to variations in the wave energy. Summary of invention
  • a wave power unit of the kind initially specified includes the specific feature that the generator has secondary electric means connecting the generator to a load. With the aid of this load all or a part of the electric energy produced by the generator can be delivered to the load such that nothing or only a part of the produced electric energy is delivered to the electric network.
  • This provides a simple and reliable way to cope with the probiem that occurs when the energy input to the generator occasionally becomes to high.
  • the invented wave power unit it includes a floating body and mechanical connection means connecting the generator and the floating body,
  • This type of wave power unit is very effective for capturing the wave energy. Furthermore, the correlation between the wave energy and the energy input to the generator is relatively high, so that the invention is particularly important in this case.
  • the load is a waste load.
  • the main purpose of deiivering energy to the ioad is to stop or reduce the energy supply to the network and not in the first place to make use of the energy for some auxiliary useful energy consumption. It is therefore appropriate to arrange the load as a waste load, which makes it possible to obtain the load by a very simple and cheap arrangement.
  • the ioad is a resistor
  • a resistor offers a simple and reliable way of consuming the energy.
  • the generator is a submerged linear generator.
  • the most convenient way of capturing the wave energy is to provide a reciprocating mechanical movement powered by the waves.
  • a linear generator is the most direct solution and elimi- nates the need to convert the reciprocating movement into a rotating movement.
  • the resistor is arranged to be cooled by water.
  • Cooling by water is a very efficient way of consuming the heat created in the resistor when current is supplied thereto. Since the invention mainly is in- tended for a submerged generator the surrounding sea water can be used to directly cool the resistor.
  • the primary electric connection means includes primary contactor means and the second electric connection includes secondary contactor means.
  • the primary contactor means and the secondary contactor means are synchronized such that the secondary contactor means is governed to close in response to opening of the primary contactor means.
  • the primary contactor means is normally closed, and the secondary contactor means is normally open, and the primary contactor means is arranged to automatically open in response to a sensed electric parameter in the primary connection means.
  • the sensed electric parame- ter is a parameter indicating failure to deliver energy to the electric network within predetermined conditions.
  • the sensed electric parameter is the voltage
  • the primary contactor means is arranged to open when the voltage exceeds a predetermined threshold value.
  • the voltage is the parameter that is most direct indicative of a non- appropriate operation condition and is easy to sense. This also makes it possible to define the trigging condition as a simple threshold value.
  • a wave power plant includes a plurality of the invented wave power units and the primary electric connection means of each wave power unit is connected to a switchgear, each primary corv tactor means is located in the respective primary electric connection means between each wind power unit and the switchgear, and the switchgear is provided with sensing means for sensing said electric parameter.
  • the energy is supplied to the network via a switchgear that is common to all the units.
  • Arranging the contactor means between the switchgear and the respective wave power unit allows a direct and individual control of each wave power unit, and arranging the sensing means in the switchgear represents a rational solution through which individual sensing is combined with centralized equipment.
  • the primary contactor means includes a first contactor adjacent to or within the switchgear and a second contactor between the generator and the first contactor, and the second contactor is arranged to open in response to opening of the first contactor.
  • the object of the invention is according to the second aspect thereof achieved in that the invented wave power unit is used for supplying energy to an electric network.
  • the object of the invention is according to the third aspect thereof achieved in that a method for controlling a wave power unit of the kind having an electric generator powered by wave energy, which generator supplies energy to an electric network includes the specific measures of - sensing an electric parameter related to the supply of energy to the electric network, and supplying electric energy to a secondary load in response to predetermined conditions related to the sensed parameter. According to a preferred embodiment of the invented method, it includes interrupting the supply of energy to the electric network when electric energy is supplied to the secondary load.
  • the invented method includes using a wave power unit according to the present invention for performing the method, In particular to any of the preferred embodiments of the invented wave power unit.
  • the invented electric network, the invented use and the invented method have advantages of similar kind as those of the invented wave power unit and the preferred embodiments thereof and which have been described above.
  • Fig. 1 is a schematica! side view of a wave power unit according to an example of the invention
  • Fig.2 illustrates the eiect ⁇ ' c connection to the generator of the wave power unit of fig, 2.
  • Fig. 3 illustrates a wave power plant according to an example of the invention.
  • Fig. 1 is a schematical side view of a wave-power unit according to the invention in operation in the sea.
  • a floating body 1 floats on the sea surface and is connected by a connection means 3, 7, to a linear generator 2 anchored at the sea bed.
  • the connection means consists of an upper part 3, which is a wire, rope, chain or the like and a lower part 7 which is a rigid rod.
  • the wire 3 is connected to the rod 7 by a joint 13.
  • the generator Is attached at the sea bed. It is, however to be understood that the generator can be located above the sea bed and be anchored in some other way.
  • the linear generator 2 has a stator 5 with windings and a translator 6 with magnets. The translator 6 is able to reciprocate up and down within the stator 5 thereby generating current in the stator windings, which current by an electric cable 11 is transferred to an electric network.
  • a spring (not shown) or the like acting on the translator 6 provides an additional force downwards.
  • the generator is located within a water-tight encapsulation, which might be filled with N 2 .
  • Fig. 2 illustrates the electric connection of the used wave power unit of fig. 1.
  • the cable 11 from the generator 2 continuous to the electric network 21 via a primary connection line 12, a switchgear 17 and a connection 20 between the switchgear 17 and the network 21.
  • a branchiine 13 from the cable 11 forms a secondary connection and leads to a resistor 14 located in the seawater.
  • the primary connection 12 is provided with two contactors 15, 16.
  • a contactor 17 is provided also in the secondary connection 13, In the switchgear 17 there is a sensor 18 sensing the voltage of the current supplied to the switchgear through the primary connection 12.
  • the switchgear has a control device 19 including a microprocessor.
  • both the contactors 15, 16 are closed and energy is supplied from the generator 2 to the electric network 21. Should the volt- age exceed a predetermined threshold pre-set in the control device 19, a signal is sent to the contactor 15 to open. Upon opening of contactor 16 the contactor 15 opens. When energy supply through the connection 12 thereby is interrupted the contactor 17 receives a signal to close. Then the electric energy is supplied through the connection 13 to the resistor 14 which becomes heated. The resistor 14 is cooled by the surrounding sea water.
  • connection 12 is schematic and shows the connection 12 as a singie cable. It is, however, to be understood that the connection normally is three-phase.
  • the connection of course also includes various equipments not depicted in the schematic figure, such as rectifiers, inverters, transformers etc., most of which can be located in the switchgear 17.
  • Figure 3 illustrates a wave power piant consisting of five wave power units with generators 2a - 2e connected to a common switchgear 17 through a respec- tive connection 12a - 12e of the kind described above with reference to fig. 2.
  • the switchgear is preferably submerged but can alternatively be located on a platform above the sea level or be land-based.
  • the generator illustrated in fig. 1 is a linear generator it is to be understood that the invention also can be applied to rotating generators.
  • Other means than a buoy and a wire can of course also be used for capturing the wave energy and transfer it to the generator.

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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

The invention relates to a wave power unit having a generator (2) powered by wave energy, The generator (2) has primary electric connection (12) means for supplying energy to an electric network (21). According to the invention the generator (2) has secondary electric connection means (13) connecting the generator to a load (14).

Description

A WAVE POWER UNIT
Field of invention
The present invention in a first aspect relates to a wave power unit includ- ing an electric generator arranged to be powered by wave energy, the generator having primary electric connection means for supplying energy to an electric network.
The invention also relates to a wave power plant including a plurality of such wave power units and to an electric network. In a second aspect of the invention it relates to a use of such a wave power unit.
And in a third aspect, the invention relates to a method of controlling such a wave power unit.
Background of the invention
During the latest decades there have been an increasing interest of making use of the energy from the waves on the sea surface and large lakes. Various constructions have been suggested for that. Examples of such wave power units can be found in WO 03/058055, WO 03/058054, WO 2004/085842, WO 2004/058 843, WO 04/090324, WO 2007/111 546 and WO 2008/130925.
In most cases wave power units are powered by waves occurring on the surface of the sea. However also wave movements in the water beyond the sea ievel can be used for that, and the present invention is also applicable to wave power units powered by such waves. The kinetic energy from the waves that is to be converted into electric energy in the generator will vary considerably. If the waves are very powerful the voltage supplied by the generator might be too high to match with the switchgear through which the electric energy is supplied to a network.
The object of the present invention is to solve this problem, and make the wave power unit, less sensitive to variations in the wave energy. Summary of invention
This object is achieved according to the first aspect of the invention in that a wave power unit of the kind initially specified includes the specific feature that the generator has secondary electric means connecting the generator to a load. With the aid of this load all or a part of the electric energy produced by the generator can be delivered to the load such that nothing or only a part of the produced electric energy is delivered to the electric network. This provides a simple and reliable way to cope with the probiem that occurs when the energy input to the generator occasionally becomes to high. According to a preferred embodiment of the invented wave power unit it includes a floating body and mechanical connection means connecting the generator and the floating body,
This type of wave power unit is very effective for capturing the wave energy. Furthermore, the correlation between the wave energy and the energy input to the generator is relatively high, so that the invention is particularly important in this case.
According to a further preferred embodiment the load is a waste load.
The main purpose of deiivering energy to the ioad is to stop or reduce the energy supply to the network and not in the first place to make use of the energy for some auxiliary useful energy consumption. It is therefore appropriate to arrange the load as a waste load, which makes it possible to obtain the load by a very simple and cheap arrangement.
According to a further preferred embodiment the ioad is a resistor.
A resistor offers a simple and reliable way of consuming the energy. According to a further preferred embodiment the generator is a submerged linear generator.
The most convenient way of capturing the wave energy is to provide a reciprocating mechanical movement powered by the waves. For converting this energy into electrical energy a linear generator is the most direct solution and elimi- nates the need to convert the reciprocating movement into a rotating movement.
According to a further preferred embodiment the resistor is arranged to be cooled by water.
Cooling by water is a very efficient way of consuming the heat created in the resistor when current is supplied thereto. Since the invention mainly is in- tended for a submerged generator the surrounding sea water can be used to directly cool the resistor.
According to a further preferred embodiment the primary electric connection means includes primary contactor means and the second electric connection includes secondary contactor means.
By these contactors a fast and reiiable change between the operation modes, i.e. supply to the network and supply to the load is easy to provide. By this embodiment a simple ON/OFF-control is achieved through which ail of the generated energy is supplied according to either of the modes. According to a further preferred embodiment, the primary contactor means and the secondary contactor means are synchronized such that the secondary contactor means is governed to close in response to opening of the primary contactor means.
Thereby the supply of energy to the ioad will automatically occur as soon as the supply to the network has been interrupted, which provides a safe and reliable control.
According to a further preferred embodiment, the primary contactor means is normally closed, and the secondary contactor means is normally open, and the primary contactor means is arranged to automatically open in response to a sensed electric parameter in the primary connection means.
By "normally" is meant during intended operation, i.e. when the generator supplies energy to the network, in occurrence of a to high input from the wave energy this will affect the electric energy supplied by the generator. By sensing an appropriate electric parameter it therefore can be detected in an easy way when the energy input is too high such that the supplied electric energy mismatches the electrical network. To govern the primary contactor in response to this sensed parameter assures a quick and secure changing of operation mode, and the need for any manual monitoring or actuation is eliminated.
According to a further preferred embodiment the sensed electric parame- ter is a parameter indicating failure to deliver energy to the electric network within predetermined conditions.
By pre-setting such conditions a well defined behaviour of the control is assured such that the generator supplies the energy to the ioad only when is required. According to a further preferred embodiment the sensed electric parameter is the voltage, and the primary contactor means is arranged to open when the voltage exceeds a predetermined threshold value.
The voltage is the parameter that is most direct indicative of a non- appropriate operation condition and is easy to sense. This also makes it possible to define the trigging condition as a simple threshold value.
According to a further preferred embodiment a wave power plant includes a plurality of the invented wave power units and the primary electric connection means of each wave power unit is connected to a switchgear, each primary corv tactor means is located in the respective primary electric connection means between each wind power unit and the switchgear, and the switchgear is provided with sensing means for sensing said electric parameter.
For a plant having a plurality of wave power units it is advantageous that the energy is supplied to the network via a switchgear that is common to all the units. Arranging the contactor means between the switchgear and the respective wave power unit allows a direct and individual control of each wave power unit, and arranging the sensing means in the switchgear represents a rational solution through which individual sensing is combined with centralized equipment.
According to a preferred embodiment of the wave power plant, the primary contactor means includes a first contactor adjacent to or within the switchgear and a second contactor between the generator and the first contactor, and the second contactor is arranged to open in response to opening of the first contactor.
To break the supply of energy to the switchgear from the wave power unit thereby can be made in a safe way with low risk for damage to the equipment in the primary connection means.
The above described preferred embodiments are set out in the claims depending from claim 1. It is to be noted that further preferred embodiments of course can be realized by any possible combination of preferred embodiments mentioned above. The electric network according to the present invention is specific in that it is connected to the invented wave power unit.
The object of the invention is according to the second aspect thereof achieved in that the invented wave power unit is used for supplying energy to an electric network. The object of the invention is according to the third aspect thereof achieved in that a method for controlling a wave power unit of the kind having an electric generator powered by wave energy, which generator supplies energy to an electric network includes the specific measures of - sensing an electric parameter related to the supply of energy to the electric network, and supplying electric energy to a secondary load in response to predetermined conditions related to the sensed parameter. According to a preferred embodiment of the invented method, it includes interrupting the supply of energy to the electric network when electric energy is supplied to the secondary load.
According to further preferred embodiments of the invented method it includes using a wave power unit according to the present invention for performing the method, In particular to any of the preferred embodiments of the invented wave power unit.
The invented electric network, the invented use and the invented method have advantages of similar kind as those of the invented wave power unit and the preferred embodiments thereof and which have been described above.
The invention will be further explained through the following detailed de- scription of examples thereof and with reference to the accompanying drawings.
Brief description of the drawings
Fig. 1 is a schematica! side view of a wave power unit according to an example of the invention, Fig.2 illustrates the eiectπ'c connection to the generator of the wave power unit of fig, 2.
Fig. 3 illustrates a wave power plant according to an example of the invention.
Description of examples according to the invention
Fig. 1 is a schematical side view of a wave-power unit according to the invention in operation in the sea. A floating body 1 floats on the sea surface and is connected by a connection means 3, 7, to a linear generator 2 anchored at the sea bed. The connection means consists of an upper part 3, which is a wire, rope, chain or the like and a lower part 7 which is a rigid rod. The wire 3 is connected to the rod 7 by a joint 13. Sn the figure the generator Is attached at the sea bed. It is, however to be understood that the generator can be located above the sea bed and be anchored in some other way. The linear generator 2 has a stator 5 with windings and a translator 6 with magnets. The translator 6 is able to reciprocate up and down within the stator 5 thereby generating current in the stator windings, which current by an electric cable 11 is transferred to an electric network.
When the floating body 1 due to the wave movements of the sea surface is forced to move up, the floating body will pui! the translator 6 down upwards. When the floating body thereafter moves down the translator δ will move down through gravity.
Optionally but preferably a spring (not shown) or the like acting on the translator 6 provides an additional force downwards. The generator is located within a water-tight encapsulation, which might be filled with N2.
Fig. 2 illustrates the electric connection of the used wave power unit of fig. 1. The cable 11 from the generator 2 continuous to the electric network 21 via a primary connection line 12, a switchgear 17 and a connection 20 between the switchgear 17 and the network 21.
A branchiine 13 from the cable 11 forms a secondary connection and leads to a resistor 14 located in the seawater. The primary connection 12 is provided with two contactors 15, 16. A contactor 17 is provided also in the secondary connection 13, In the switchgear 17 there is a sensor 18 sensing the voltage of the current supplied to the switchgear through the primary connection 12. The switchgear has a control device 19 including a microprocessor.
When normal conditions prevail both the contactors 15, 16 are closed and energy is supplied from the generator 2 to the electric network 21. Should the volt- age exceed a predetermined threshold pre-set in the control device 19, a signal is sent to the contactor 15 to open. Upon opening of contactor 16 the contactor 15 opens. When energy supply through the connection 12 thereby is interrupted the contactor 17 receives a signal to close. Then the electric energy is supplied through the connection 13 to the resistor 14 which becomes heated. The resistor 14 is cooled by the surrounding sea water.
The illustration is schematic and shows the connection 12 as a singie cable. It is, however, to be understood that the connection normally is three-phase. The connection of course also includes various equipments not depicted in the schematic figure, such as rectifiers, inverters, transformers etc., most of which can be located in the switchgear 17.
Figure 3 illustrates a wave power piant consisting of five wave power units with generators 2a - 2e connected to a common switchgear 17 through a respec- tive connection 12a - 12e of the kind described above with reference to fig. 2. Also the switchgear is preferably submerged but can alternatively be located on a platform above the sea level or be land-based.
Although the generator illustrated in fig. 1 is a linear generator it is to be understood that the invention also can be applied to rotating generators. Other means than a buoy and a wire can of course also be used for capturing the wave energy and transfer it to the generator.

Claims

1. A wave power unit including an electric generator (2) arranged to be powered by wave energy, the generator having primary electric connection means (12) for supplying energy to an electric network (21 ), characterized In that the generator (2) has secondary electric connection means (13) for connecting the generator (2) to a load (14).
2. A wave power unit according to ciaim 1 characterized in that the unit in- cludes a floating body (1) and mechanical connection means (3) connecting the generator (2) and the floating body (1).
3. A wave power unit according to claim 2 characterized in that the load (14) is a waste load.
4. A wave power unit according to claim 3 characterized in that the load (14) is a resistor (14).
5. A wave power unit according to claim 4 characterized in that the genera- tor (2) is a submerged iinear generator.
6. A wave power unit according to claim 5 characterized in that the resistor (14) is arranged to be cooled by water.
7. A wave power unit according to any of claims 1 - 5 characterized in that the primary electric connection means (12) includes a primary contactor means (15, 16) and the secondary electric connection means (13) includes a secondary contactor means (17).
8. A wave power unit according to claim 7 characterized in that the primary contactor means (15, 16) and the secondary contactor means (17) are synchronized such that the secondary contactor means (17) is governed to close in response to opening of the primary contactor means (15, 16).
9. A wave power unit according to claim 8 characterized in that the primary contactor means (15. 16) is normally closed and the secondary contactor means (17) is normally open and in that the primary contactor means (15, 16) is arranged to automatically open in response to a sensed eiectric parameter in the primary eiectric connection means (12).
10. A wave power unit according to claim 9 characterized in that the sensed eiectric parameter is a parameter indicating faϋure to deliver energy to the electric network within predetermined conditions.
11. A wave power unit according to claim 9 or 10 characterized In that the sensed eiectric parameter is the voltage and in that the primary contactor means (15, 16) is arranged to open when the voitage exceeds a predetermined threshold value.
12. A wave power plant characterized in that the plant includes a plurality of wave power units according to any of claims 1 - 11 and a switchgear (17) to which the primary eiectric connection means (12a - 12e) of each wave power unit is connected, and in that each primary contactor means (15, 16) is located in the re- spective primary eiectric connection means (12a ~ 12e) between each wave power unit and the switchgear (17), the switchgear (17) being provided with sensing means (18) for sensing said electric parameters.
13. A wave power plant according to claim 12 characterized in that the pri- mary contactor means (15, 16) includes a first contactor (16) adjacent to or within the switchgear (17) and a second contactor (15) between the generator (2) and the first contactor (16), and in that the second contactor (15) is arranged to open in response to opening of the first contactor (16).
14. An electric network (21) characterized in that the network is connected to a wave power unit according to any of claims 1 - 11.
15. The use of a wave power unit according to any of claims 1 - 11 for supplying energy to an electric network.
16. A method for controlling a wave power unit of the kind having an electric generator powered by wave energy, which generator supplies energy to an electric network characterized by sensing an electric parameter related to the supply of energy to the electric network and supplying electric energy to a secondary load in response to predetermined conditions related to the sensed parameter
17. A method according to claim 16 characterized by interrupting the supply of energy to the eiectric network when electric energy is supplied to the secondary load.
18. A method according to claim 16 or 17 characterized by using a wave power unit according to any of claims 1 - 11 or by using a wave power plant according to claim 12 or 13 for performing the method.
PCT/SE2009/050072 2009-01-23 2009-01-23 A wave power unit WO2010085188A1 (en)

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PCT/SE2009/050072 WO2010085188A1 (en) 2009-01-23 2009-01-23 A wave power unit
EP09838966.1A EP2389507A4 (en) 2009-01-23 2009-01-23 A wave power unit

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US20230213016A1 (en) * 2020-06-08 2023-07-06 Seabased Limited Array for arranging wave energy converters in a wave power park

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Publication number Priority date Publication date Assignee Title
WO2021251880A1 (en) * 2020-06-08 2021-12-16 Seabased Ab Method for determining the arrangement of wave energy converters
US20230213016A1 (en) * 2020-06-08 2023-07-06 Seabased Limited Array for arranging wave energy converters in a wave power park

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EP2389507A4 (en) 2013-07-24
EP2389507A1 (en) 2011-11-30

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