Power storage system

Abstract

The device's rated output is being suppressed. [Solution] The power storage system comprises a power supply means (26) that supplies at least a portion of the power generated by the alternating repeated unwinding and winding of the tether that anchors the aircraft (22) to a power storage unit (271, 272) that stores the power in a predetermined manner, a power holding unit (281, 273) that can charge and discharge power, and a control means (25) that controls the power holding unit so that power is supplied from the power holding unit to the power storage unit when the tether is wound up.

Description

Technical Field

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[0001] The present invention relates to the technical field of power storage systems.

Background Art

[0002] As this type of system, for example, a power distribution management system that switches the wiring of a power transmission network based on the maximum power that can be generated by a plurality of power generation devices that perform wind power generation using kite-shaped flying objects and the target power required by each of a plurality of power demand facilities has been proposed (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Power generation using renewable energy such as wind power is affected by weather and the like, so it is difficult to control the amount of generated power. For example, in order to prevent surplus power from being discarded, surplus power is stored. As an example of power storage, power is converted into hydrogen and stored by electrolyzing water using power.

[0005] By the way, in wind power generation using a kite-shaped flying object, power generation is performed when the kite-shaped flying object rises due to wind, while power generation is not performed when the kite-shaped flying object is recovered. In wind power generation using a kite-shaped flying object, the output during power generation is significantly larger than the time average of the output during power generation and the output during the recovery of the kite-shaped flying object. When performing electrolysis of water using the power of wind power generation using a kite-shaped flying object, a device capable of corresponding to the output during the above power generation is required. That is, in this case, there is a technical problem that a device with a rated output significantly larger than the time average output of wind power generation using a kite-shaped flying object is required. <00

[0006] This invention has been made in view of the above-mentioned problems, and aims to provide a power storage system that can suppress the rated output of the device. [Means for solving the problem]

[0007] A power storage system according to one aspect of the present invention comprises a power storage unit that stores power in a predetermined manner, a power holding unit that can charge and discharge power, and a power supply means that supplies at least a portion of the power generated by the alternating repeated unwinding and winding of a tether for mooring an aircraft to a power storage unit, and a power supply means that controls the power holding unit to supply power to the power storage unit from the power holding unit when the tether is wound up. [Brief explanation of the drawing]

[0008] [Figure 1] This is a conceptual diagram showing an example of a power generation system. [Figure 2] This is a conceptual diagram showing an example of a floating power generation structure. [Figure 3] This block diagram shows an example of the configuration of a power-generating floating structure. [Figure 4] This graph shows an example of how power output changes over time. [Figure 5] This block shows another example of the configuration of a power-generating floating structure. [Modes for carrying out the invention]

[0009] Embodiments relating to the power storage system will be described with reference to Figures 1 to 4.

[0010] (Power generation system) The power generation system will be explained with reference to Figure 1. The power generation system comprises a transport ship 10 and power generation floats 20. In this power generation system, power generation is carried out in a sea area SA relatively far from land, using multiple power generation floats 20 that do not require mooring. The multiple power generation floats 20 automatically navigate within the sea area SA. In other words, each of the multiple power generation floats 20 generates power while automatically navigating within the sea area SA.

[0011] The number of power-generating floating bodies 20 that automatically navigate within the sea area SA may be determined according to the power generation scale of the power generation system. For example, there may be several hundred to several thousand power-generating floating bodies 20 within the sea area SA. For example, the sea area SA may be a sea area 50 kilometers away from land. For example, the length of one side of the sea area SA may be several tens of kilometers. Furthermore, the shape of the sea area SA is not limited to a rectangle.

[0012] The transport ship 10 navigates between a port P located on land and a sea area SA. For example, the transport ship 10 may recover energy generated from the power generation floating 20 near the edge of the sea area SA (for example, area CA). The transport ship 10 then transports the energy recovered from the power generation floating 20 to port P. In this way, the power generation system involves offshore power generation using multiple power generation floating 20 and energy transport by the transport ship 10.

[0013] (Power generation floating body 20) The power generation float 20 will be explained with reference to Figures 2 and 3. In Figure 2, the power generation float 20 is equipped with a sail 21 and a kite 22. The power generation float 20 may use the wind energy received by the sail 21 as propulsion. The power generation float 20 may also use the wind energy received by the kite 22 as propulsion. In Figure 3, the power generation float 20 is equipped with a navigation unit 23, a power generation unit 24, a control unit 25, a power distribution device 26, a main storage 27, and a sub-storage 28. In Figure 3, solid arrows indicate the flow of electricity, and dotted arrows indicate the flow of data.

[0014] The navigation unit 23 may include one or more elements for automatically navigating the power-generating float 20. For example, the navigation unit 23 may include a mechanism for changing the direction of the sail 21. For example, the navigation unit 23 may include at least one of a rudder that determines the direction of the hull of the power-generating float 20 and a centerboard that generates lateral force. For example, the navigation unit 23 may include sensors necessary for navigation. For example, the sensors may include at least one of a wind direction and speed sensor, a wind rate sensor, an acceleration sensor, an angular velocity sensor, and a speed sensor. In addition to wind energy, the power-generating float 20 may also utilize electrical energy as propulsion. In this case, the navigation unit 23 may include a screw propeller and a motor that drives the screw propeller.

[0015] The power generation unit 23 includes a winch for the tether that moores the kite 22, a motor capable of rotating the drum of the winch, and a generator. In the power generation floating body 20, as the kite 22 rises, the tether that moores the kite 22 is extended from the winch. The extension of the tether causes the drum of the winch to rotate. Power is generated as the generator rotates in conjunction with the rotation of the drum. Once the tether has been extended to a predetermined length, or after a predetermined time has elapsed, the motor of the winch rotates the drum of the winch in the direction of winding up the tether. As a result, the kite 22 descends due to the winding up of the tether. In the power generation floating body 20, power is generated by repeatedly performing the extension and winding up of the tether. In other words, tether-type wind power generation is performed in the power generation floating body 20.

[0016] The control unit 25 controls various processes in the power generation floating body 20. For example, the control unit 25 may be configured as a unit including a CPU (Central Processing Unit), a memory device and input / output interfaces necessary for the operation of the CPU. The memory device may include, for example, ROM (Read Only Memory), RAM (Random Access Memory), and data storage. For example, the control unit 25 may be connected to the navigation unit 23, power generation unit 24, power distribution device 26, main storage 27, and sub-storage 28 via a data bus. For example, the control unit 25 may transmit control instructions to the navigation unit 23, power generation unit 24, power distribution device 26, main storage 27, and sub-storage 28 via the data bus. For example, the control unit 25 may acquire various information from the navigation unit 23, power generation unit 24, power distribution device 26, main storage 27, and sub-storage 28 via the data bus.

[0017] Furthermore, research by the inventors of this invention has shown that net power generation improves when the power generation float 20 moves upwind when the tether is extended (i.e., during power generation) and downwind when the tether is retracted. For this reason, the control unit 25 may control the navigation unit 23 so that the power generation float 20 moves upwind when the tether is extended and downwind when the tether is retracted.

[0018] For example, at least one of the ROM and the data storage may store a computer program for realizing the processing in the control unit 25. The control unit 25 may read the computer program stored in at least one of the ROM and the data storage. Incidentally, the control unit 25 may acquire a computer program from a device (not shown) disposed outside the power generation floating body 20 via a communication unit (not shown). The control unit 25 may execute the read computer program. As a result, logical functional blocks for controlling various processes in the power generation floating body 20 may be realized within the control unit 25. For example, a power conditioner 251 may be realized as a functional block within the control unit. Details of the operation of the power conditioner 251 will be described later.

[0019] The power distribution device 26, the main storage 27, and the sub-storage 28 constitute the power storage system according to the present embodiment. The power obtained by the tethered wind power generation using the kite 22 is distributed to each of the main storage 27 and the sub-storage 28 via the power distribution device 26. In other words, the power distribution device 26 distributes the power obtained by the tethered wind power generation to the main storage 27 and the sub-storage 28.

[0020] The main storage 27 includes a hydrogen generation device 271 and a hydrogen tank 272. The hydrogen generation device 271 electrolyzes water using the power (i.e., electrical energy) supplied via the power distribution device 26. As a result, hydrogen is generated. The hydrogen generation device 271 stores the hydrogen in the hydrogen tank 272. The hydrogen may be stored in the hydrogen tank 272 as compressed hydrogen or liquefied hydrogen. The hydrogen tank 272 may contain a hydrogen storage alloy. In this case, the hydrogen may be stored in the hydrogen tank 272 by being absorbed by the hydrogen storage alloy. Incidentally, the hydrogen tank 272 may store not only hydrogen but also hydrogen compounds. The hydrogen compounds may be ammonia, methylcyclohexane, or the like. In this case, in addition to the hydrogen generation device 271, the main storage 27 may have a device for generating hydrogen compounds.

[0021] Furthermore, the transport ship 10 may recover the hydrogen tank 272 in which hydrogen or a hydrogen compound is stored from the power generation floating body 20. The transport ship 10 may load an empty hydrogen tank (corresponding to the hydrogen tank 272) onto the power generation floating body 20. The hydrogen generator 271 may store hydrogen or a hydrogen compound in the empty hydrogen tank. Thus, in the present embodiment, the transport ship 10 may recover the energy obtained by power generation from the power generation floating body 20 by recovering the hydrogen tank 272. That is, in the present embodiment, hydrogen or a hydrogen compound may be used as an energy carrier.

[0022] The sub-storage 28 has power storages 281 and 282. The power storage 281 is a device that temporarily stores the power used in the main storage 27 (for example, the hydrogen generator 271). The power storage 281 may be an electric double layer capacitor (which may also be referred to as a "supercapacitor" or an "ultracapacitor"), or a flywheel battery. The power storage 282 is a device that stores the power necessary for the operation of the power generation floating body 20. The power storage 282 may be a secondary battery such as a lithium ion battery or a NAS battery. The power storage 282 may supply power to the navigation unit 23, the power generation unit 24 (for example, a motor capable of rotating the drum of a winch), and the control unit 25. Note that the electric double layer capacitor and the flywheel battery have a longer cycle life than secondary batteries. Therefore, it can be said that the power storage 281 is a power storage with a longer cycle life than the power storage 282.

[0023] (Temporal change of power in the power generation floating body 20) The time variation of power in the power generation floating body 20 will be explained with reference to Figure 4. Figure 4(a) is an example of the time variation of power according to a comparative example. Figure 4(b) is an example of the time variation of power according to this embodiment. In Figures 4(a) and (b), the solid line shows the time variation of power related to tethered wind power generation, the dotted line shows the time variation of power related to the sub-storage 28, and the dashed line shows the time variation of power supplied to the hydrogen generator 271. The negative value of the power related to the sub-storage 28 indicates that the power output from the sub-storage 28 is greater than the power supplied to the sub-storage 28.

[0024] The power storage system in the comparative example does not have a power storage 281. For example, in the first period from time t11 to time t12 in Figure 4(a), power may be generated as the kite 22 rises. In the second period from time t12 to time t13, the kite 22 may be recovered. Therefore, the power generated in the second period is zero. Also, in the second period, power is supplied from the sub-storage 28 (specifically, the power storage 282) to the motor of the power generation unit 24 in order to recover the kite 22, so the power related to the sub-storage 28 is a negative value.

[0025] The electricity generated during the first period is distributed to the main storage 27 and the sub-storage 28. For example, 2 MW (megawatts) of power may be supplied to the main storage 27 and 0.5 MW of power to the sub-storage 28. The hydrogen generator 271 is required to be a hydrogen generator that can operate appropriately with the power supplied to the main storage 27 during the first period. For example, the time-averaged output of a tethered wind power generation system using a kite 22 may be 1 MW. In this case, the power supplied to the main storage 27 during the first period is significantly larger than the time-averaged output of the wind power generation. Therefore, the power storage system according to the comparative example has a technical problem in that it requires a hydrogen generator with a rated output significantly larger than the time-averaged output of the wind power generation.

[0026] The power storage system according to this embodiment will be explained with reference to Figure 4(b). For example, in the third period from time t21 to time t22 in Figure 4(b), power may be generated as the kite 22 rises. In the fourth period from time t22 to time t23, the kite 22 may be recovered. The power obtained by power generation in the third period is distributed to the main storage 27 and the sub-storage 28. For example, 1 MW of power may be supplied to the main storage 27, 1 MW of power may be supplied to the power storage 281 of the sub-storage 28, and 0.5 MW of power may be supplied to the power storage 282 of the sub-storage 28. For example, in the fourth period, 1 MW of power may be supplied from the power storage 281 to the main storage 27. In this case, the control unit 25 may control the power storage 281 so that power is supplied from the power storage 281 to the main storage 27 in the fourth period.

[0027] In this embodiment, during the third period, the power used by the main storage 27 is temporarily stored in the power storage 281 of the sub-storage 28. Therefore, the power supplied to the main storage 27 can be suppressed during the third period. As a result, the rated output of the hydrogen generator 271 can be suppressed.

[0028] (Power adjustment section 251) The operation of the power adjustment unit 251 will now be described. The power adjustment unit 251 may predict the amount of electricity demand in the power generation floating body 20. This amount of electricity demand may be the amount of electricity required for the operation of the power generation floating body 20. The power adjustment unit 251 may acquire energy storage information of the power storage 282 of the sub-storage 28. For example, the energy storage information may indicate at least one of the amount of energy stored and the energy storage rate related to the power storage 282. For example, the power adjustment unit 251 may determine the amount of electricity to be supplied to the power storage 282 as the difference between the predicted amount of electricity demand and the amount of energy stored in the power storage 282.

[0029] For example, the power adjustment unit 251 may determine the amount of power to be supplied to the main storage 27 based on the rated output of the hydrogen generator 271. For example, the power adjustment unit 251 may determine that the amount of power to be supplied to the power storage 281 of the sub-storage 28 is the amount of power that exceeds the sum of the amount of power to be supplied to the main storage 27 and the amount of power to be supplied to the power storage 282 from the amount of power obtained from the tethered wind power generation. Subsequently, the power adjustment unit 251 may control the power distribution device 26 so that the determined amount of power is supplied to the main storage 27, power storage 281 and power storage 282.

[0030] (Technical effects) As explained with reference to Figure 4(a), in the comparative example power storage system, power is supplied to the hydrogen generator 271 when the tethered wind turbine is generating electricity, but power is not supplied to the hydrogen generator 271 when the kite 22 is being recovered (i.e., when power is not being generated). For this reason, the rated output of the hydrogen generator 271 is relatively large in the comparative example power storage system.

[0031] In contrast, in the power storage system according to this embodiment, when tethered wind power generation is in progress, the power to be used by the main storage 27 is temporarily stored in the power storage 281 of the sub-storage 28, and when power generation is not in progress, power is supplied from the power storage 281 to the main storage 27. Therefore, the power storage system according to this embodiment can smooth the power supplied to the main storage 27. As a result, the rated output of the hydrogen generator 271 can be suppressed. Here, the price of the hydrogen generator 271 is directly proportional to its rated output. For example, by suppressing the rated output of the hydrogen generator 271, the manufacturing cost of the power generation float 20 can be reduced.

[0032] For example, the period from time t21 to time t23 in Figure 4(b) is several tens to several hundreds of seconds. In other words, one charge-discharge cycle of the power storage 281 of the sub-storage 28 is also several tens to several hundreds of seconds. As mentioned above, the power storage 281 may be an electric double-layer capacitor or a flywheel battery. With this configuration, the cycle life of the power storage 281 can be made relatively long. As a result, the operating costs of the power generation system can be reduced.

[0033] <Variation> A modified example of the power storage system according to the above embodiment will be described with reference to Figure 5. In Figure 5, the main storage 27 according to the modified example includes a hydrogen generator 271, a hydrogen tank 272, and a power storage 273. The power storage 273 is a power storage corresponding to the power storage 281 described above. In other words, the power storage 273 is a device that temporarily stores the electricity used by the hydrogen generator 271. In Figure 5, the sub-storage 28 according to the modified example includes a power storage 282. In other words, the sub-storage 28 according to the modified example does not have a power storage 281.

[0034] For example, in the third period from time t21 to time t22 in Figure 4(b), electricity may be generated as the kite 22 rises. In the fourth period from time t22 to time t23, the kite 22 may be recovered. The electricity generated in the third period is distributed to the main storage 27 and the sub-storage 28. For example, 1 MW of electricity may be supplied to the hydrogen generator 271 of the main storage 27, 1 MW of electricity may be supplied to the power storage 273 of the main storage 27, and 0.5 MW of electricity may be supplied to the power storage 282 of the sub-storage 28. For example, in the fourth period, 1 MW of electricity may be supplied from the power storage 273 to the hydrogen generator 271.

[0035] According to the modified power storage system, the rated output of the hydrogen generator 271 can be suppressed, similar to the power storage system according to the embodiment described above.

[0036] In addition, although the above-described embodiment mentioned tethered wind power generation performed offshore, the power storage system according to the present invention is also applicable to tethered wind power generation performed on land.

[0037] Aspects of the invention derived from the embodiments and modifications described above are described below.

[0038] A power storage system according to one aspect of the invention comprises a power storage unit that stores power in a predetermined manner, a power holding unit that can charge and discharge power, and a power supply means that supplies at least a portion of the power generated by the alternating repeated unwinding and winding of a tether for mooring an aircraft to the power storage unit, and a power supply means that controls the power holding unit so that power is supplied from the power holding unit to the power storage unit when the tether is wound up.

[0039] In the above-described embodiment, "Kite 22" corresponds to an example of "flying body," "hydrogen generator 271" and "hydrogen tank 272" correspond to an example of "power storage unit," "power storage 281" and "power storage 273" correspond to an example of "power holding unit," "power distribution device 26" corresponds to an example of "power supply means," and "control unit 25" corresponds to an example of "control means."

[0040] In this power storage system, the flying object may be moored via the tether to a floating object capable of navigating on water.

[0041] In this embodiment, the power storage system may include a main storage system having the power storage unit and a sub-storage system capable of charging and discharging power used for the operation of the floating body, and the sub-storage system may have the power holding unit. In the above embodiment, "main storage 27" corresponds to an example of the "main storage system," and "sub-storage 28" corresponds to an example of the "sub-storage system."

[0042] Alternatively, the power storage system may comprise a main storage system having the power storage unit and a sub-storage system capable of charging and discharging power used for the operation of the floating body, and the main storage system may have the power holding unit.

[0043] In this power storage system, the power retention unit may be an electric double-layer capacitor or a flywheel battery.

[0044] The present invention is not limited to the embodiments described above, and can be modified as appropriate without contradicting the gist or idea of ​​the invention as can be read from the claims and specification as a whole. Power storage systems with such modifications are also included within the technical scope of the present invention. [Explanation of Symbols]

[0045] 10...Transport ship, 20...Power generation float, 21...Sail, 22...Kite, 23...Navigation unit, 24...Power generation unit, 25...Control unit, 26...Power distribution device, 27...Main storage, 28...Sub-storage, 271...Hydrogen generator, 272...Hydrogen tank, 273, 281, 282...Power storage

Claims

1. A power supply means that supplies at least a portion of the power generated by the alternating repeated extension and retraction of a tether for mooring an aircraft to a power storage unit that stores power in a predetermined manner and a power holding unit that can charge and discharge power, Control means for controlling the power holding unit so that power is supplied from the power holding unit to the power storage unit when the tether is wound up, A power storage system equipped with the following features.

2. The aircraft is moored via the tether to a floating structure capable of navigating on water. The power storage system according to claim 1.

3. A main storage system having the aforementioned power storage unit, A sub-storage system capable of charging and discharging the power used for the operation of the floating structure, Equipped with, The sub-storage system has the power holding unit The power storage system according to claim 2.

4. A main storage system having the aforementioned power storage unit, A sub-storage system capable of charging and discharging the power used for the operation of the floating structure, Equipped with, The main storage system has the power holding unit The power storage system according to claim 2.

5. The power retention unit is an electric double-layer capacitor or a flywheel battery. The power storage system according to claim 1.

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