Power storage system

Abstract

The invention provides a power storage system which suppresses rated output of a device. This power storage system is provided with: a power supply means (26) that supplies at least a portion of generated power obtained by alternately repeating unwinding and winding of a tether for mooring a flying body (22) to power storage units (271, 272) that store power in a predetermined manner, and power holding units (281, 273) that hold the power in a predetermined manner, the power storage units (271, 272) holding the power in a predetermined manner, and the power holding units (281, 273) holding the power storage units (271, 272); the power holding units (281, 273) are capable of charging and discharging power. And a control means (25) for controlling the power holding unit such that power is supplied from the power holding unit to the power storage unit when the tether is wound up.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of an electric power storage system. BACKGROUND

[0002] As such a system, for example, there is proposed an electric power distribution management system that switches a wiring of a power transmission grid based on a maximum producible electric power of a plurality of power generation devices that implement wind power generation using a kite-type flying body, and a target electric power that is respectively required from a plurality of electric power demand apparatuses (see Patent Literature 1).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2020-094521 SUMMARY

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] Since power generation using renewable energy such as wind power generation is affected by weather and the like, it is difficult to control the amount of generated power. For example, in order to prevent surplus electric power from being wasted, a process of storing surplus electric power is implemented. As one example of electric power storage, by electrolysis of water using electric power, electric power is converted into hydrogen and stored.

[0008] In addition, in wind power generation using a kite-type flying body, power generation is performed when the kite-type flying body is raised by wind, and on the other hand, power generation is not performed when the kite-type flying body is recovered. In wind power generation using a kite-type flying body, the output at the time of power generation is significantly larger than the time-averaged output of the output at the time of power generation and the output at the time of recovery of the kite-type flying body. In a case where electrolysis of water is performed using electric power of wind power generation using a kite-type flying body, a device capable of coping with the above-mentioned output at the time of power generation is required. That is, in this case, there is a technical problem point that a device having a rated output significantly larger than the time-averaged output of wind power generation using a kite-type flying body is required.

[0009] The present application is an application made in view of the above-mentioned problem point, and a subject thereof is to provide an electric power storage system capable of suppressing a rated output of a device.

[0010] MEANS FOR SOLVING THE PROBLEMS

[0011] One aspect of the present invention relates to an electricity storage system comprising: a power supply unit that supplies at least a portion of the generated electricity obtained by alternately and repeatedly unwinding and rewinding the tether of a tethered aircraft to a power storage unit and a power holding unit, wherein the power storage unit stores electricity in a predetermined manner and the power holding unit is capable of charging and discharging the electricity; and a control unit that controls the power holding unit to supply electricity from the power holding unit to the power storage unit during the rewinding of the tether. Attached Figure Description

[0012] Figure 1 A conceptual diagram illustrating an example of a power generation system.

[0013] Figure 2 A conceptual diagram illustrating an example of a power-generating floating body.

[0014] Figure 3 A block diagram illustrating an example of the structure of a power generation buoy.

[0015] Figure 4 A graph showing an example of how power generation output changes over time.

[0016] Figure 5 A block diagram illustrating other examples of the structure of a power generation buoy. Detailed Implementation

[0017] Reference Figures 1 to 4 The implementation methods involved in the power storage system will be described.

[0018] (Power generation system)

[0019] Reference Figure 1 The power generation system is described below. The power generation system includes a transport vessel 10 and power generation floats 20. In this system, multiple power generation floats 20, which do not require mooring, are used to generate electricity in a sea area SA relatively far from land. The multiple power generation floats 20 navigate automatically within the sea area SA. That is, the multiple power generation floats 20 generate electricity while simultaneously navigating automatically within the sea area SA.

[0020] Furthermore, the number of power-generating buoys 20 that navigate autonomously within the sea area SA can be determined based on the power generation scale of the power generation system. For example, there may be hundreds to thousands of power-generating buoys 20 within the sea area SA. For example, the sea area SA may be a sea area 50 kilometers from the land. For example, the length of one side of the sea area SA may also be tens of kilometers. In addition, the shape of the sea area SA is not limited to a quadrilateral.

[0021] The transport ship 10 travels between a port P provided on land and a sea area SA. For example, the transport ship 10 can recover the energy obtained by power generation from the power generation buoy 20 near the end of the sea area SA (for example, the region CA). Thereafter, the transport ship 10 transports the energy recovered from the power generation buoy 20 to the port P. Thus, in the power generation system, the sea power generation by the plurality of power generation buoys 20 and the energy transportation by the transport ship 10 are performed.

[0022] (Power generation buoy 20)

[0023] The power generation buoy 20 will be further described with reference to Figure 2 and Figure 3 In Figure 2 , the power generation buoy 20 is provided with a sail 21 and a kite 22. The power generation buoy 20 can utilize the wind energy received by the sail 21 as a propulsive force. In addition, the power generation buoy 20 can utilize the wind energy received by the kite 22 as a propulsive force. In Figure 3 , the power generation buoy 20 is provided with a traveling 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 addition, in Figure 3 , a solid arrow mark indicates the flow of electric power, and a dashed arrow mark indicates the flow of data.

[0024] The traveling unit 23 can include one or more elements for causing the power generation buoy 20 to travel automatically. For example, the traveling unit 23 can include a mechanism for changing the orientation of the sail 21. For example, the traveling unit 23 can include at least one of a rudder that determines the direction of the hull of the power generation buoy 20 and a central plate that generates a lateral force. For example, the traveling unit 23 can include a sensor-like component required for traveling. For example, the sensor-like component can include at least one of a wind direction and wind speed sensor, a wind volume sensor, an acceleration sensor, an angular velocity sensor, and a speed sensor. In addition to the wind energy, the power generation buoy 20 can utilize electric energy as a propulsive force. In this case, the traveling unit 23 can include a propeller and a motor that drives the propeller.

[0025] The power generation unit 23 has a winch of the tether of the kite 22, a motor capable of rotating a drum of the winch, and a generator. In the power generation float 20, the tether of the kite 22 is paid out from the winch in conjunction with the rising of the kite 22. The drum of the winch is rotated by the paying-out action of the tether. The generator is rotated in conjunction with the rotation of the drum, and thus power generation is performed. After the tether is paid out to a predetermined length or a predetermined time elapses, the drum of the winch is rotated in the direction of winding up the tether by the motor of the winch. As a result, the kite 22 is lowered by the winding-up action of the tether. In the power generation float 20, power generation is performed by repeating the paying-out action and the winding-up action of the tether. That is, in the power generation float 20, kite-type wind power generation is performed.

[0026] The control unit 25 controls various processes in the power generation float 20. For example, the control unit 25 can be configured as a unit including a CPU (Central Processing Unit), a storage device required for the operation of the CPU, an input / output interface, and the like. The storage device can include, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), a data storage, and the like. For example, the control unit 25 can be connected to the sailing unit 23, the power generation unit 24, the power distribution device 26, the main storage 27, and the sub storage 28 via a data bus. For example, the control unit 25 can transmit a control instruction to the sailing unit 23, the power generation unit 24, the power distribution device 26, the main storage 27, and the sub storage 28 via the data bus. For example, the control unit 25 can acquire various information from the sailing unit 23, the power generation unit 24, the power distribution device 26, the main storage 27, and the sub storage 28 via the data bus.

[0027] In addition, it has been found by the present inventor that, if the power generation float 20 travels in the upwind direction when the tether is paid out (i.e., when power generation is performed), and the power generation float 20 travels in the downwind direction when the tether is wound up, the net power generation amount increases. Therefore, the control unit 25 can also control the sailing unit 23 in such a manner that the power generation float 20 travels in the upwind direction when the tether is paid out, and the power generation float 20 travels in the downwind direction when the tether is wound up.

[0028] For example, in at least one of the ROM and the data storage, a computer program for implementing the processing in the control unit 25 can be stored. The control unit 25 can read in the computer program stored in at least one of the ROM and the data storage. In addition, the control unit 25 can acquire the computer program from a device not shown that is configured outside the power generation buoy 20 via a communication unit not shown. The control unit 25 can execute the read-in computer program. As a result of this, in the control unit 25, a logical functional block for controlling various processes in the power generation buoy 20 can be implemented. For example, in the control unit, a power adjustment section 251 can be implemented as a functional block. Details of the operation of the power adjustment section 251 will be described later.

[0029] 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 kite 22 of the tether type wind power generation is distributed to 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 tether type wind power generation to the main storage 27 and the sub storage 28.

[0030] The main storage 27 has a hydrogen generation device 271 and a hydrogen tank 272. The hydrogen generation device 271 electrolyzes water using the power (i.e., electric energy) supplied via the power distribution device 26. As a result of this, hydrogen is generated. The hydrogen generation device 271 stores the hydrogen in the hydrogen tank 272. The hydrogen can be stored in the hydrogen tank 272 as compressed hydrogen or liquefied hydrogen. The hydrogen tank 272 can also contain a hydrogen storage alloy. In this case, the hydrogen can also be stored in the hydrogen tank 272 by causing the hydrogen to be adsorbed by the hydrogen storage alloy. In addition, in the hydrogen tank 272, not limited to hydrogen, a hydrogen compound can also be stored. The hydrogen compound can be ammonia, methylcyclohexane, or the like. In this case, the main storage 27 can have a device for generating a hydrogen compound in addition to the hydrogen generation device 271.

[0031] In addition, the transport ship 10 can recover the hydrogen tank 272 in which hydrogen or a hydrogen compound is stored from the power generation buoy 20. The transport ship 10 can load an empty hydrogen tank (corresponding to the hydrogen tank 272) into the power generation buoy 20. The hydrogen generation device 271 can store hydrogen or a hydrogen compound in the empty hydrogen tank. In this way, in the present embodiment, the transport ship 10 can recover the energy obtained by power generation from the power generation buoy 20 by recovering the hydrogen tank 272. That is, in the present embodiment, hydrogen or a hydrogen compound can be used as an energy carrier.

[0032] The secondary storage unit 28 includes power storage units 281 and 282. Power storage unit 281 is a device for temporarily storing electricity used in the main storage unit 27 (e.g., hydrogen generation device 271). Power storage unit 281 can be an electric double-layer capacitor (also referred to as a "supercapacitor" or "polar capacitor") or a flywheel battery. Power storage unit 282 is a device for storing electricity required for the operation of the power-generating float 20. Power storage unit 282 can be a secondary battery such as a lithium-ion battery or a NAS battery. Power storage unit 282 can supply power to the navigation unit 23, the power generation unit 24 (e.g., a motor that can rotate the drum of a winch), and the control unit 25. In addition, electric double-layer capacitors and flywheel batteries have a longer cycle life compared to secondary batteries. Therefore, it can be said that power storage unit 281 is a power storage unit with a longer cycle life compared to power storage unit 282.

[0033] (Time-varying power in the power-generating float 20)

[0034] Reference Figure 4 This will explain the temporal variation of the electricity in the power generation float 20. Figure 4 (a) in the comparison example is an example of the time variation of electricity. Figure 4 (b) in this embodiment is an example of the temporal variation of electricity. Figure 4 In (a) and (b), the solid line represents the time variation of electricity related to tethered wind power generation, the dotted line represents the time variation of electricity related to the auxiliary storage 28, and the dashed line represents the time variation of electricity supplied to the hydrogen generation device 271. A negative value for electricity related to the auxiliary storage 28 indicates that more electricity is output from the auxiliary storage 28 than is supplied to it.

[0035] The comparative example's power storage system does not have a power storage device 281. For example, it can be used from... Figure 4 During the first period from time t11 to time t12 in (a), electricity is generated by power generation accompanying the ascent of kite 22. Kite 22 can be retrieved during the second period from time t12 to time t13. Therefore, the electricity generated during the second period is zero. Furthermore, since electricity is supplied from the secondary storage 28 (specifically, the power storage 282) to the motor of the power generation unit 24 during the second period for retrieving kite 22, the electricity related to the secondary storage 28 becomes negative.

[0036] The electric power obtained by the power generation in the first period is distributed to the main accumulator 27 and the sub-accumulator 28. For example, 2 MW (megawatt) of electric power can be supplied to the main accumulator 27, and 0.5 MW of electric power can be supplied to the sub-accumulator 28. The hydrogen generation device 271 is required to be a hydrogen generation device that can appropriately operate using the electric power supplied to the main accumulator 27 in the first period. For example, the time average output of the kite 22 of the tether type wind power generation can be 1 MW. In this case, the electric power supplied to the main accumulator 27 in the first period is significantly larger than the time average output of the wind power generation. Therefore, in the electric power storage system related to the comparative example, there is a technical problem that the hydrogen generation device having a rated output significantly larger than the time average output of the wind power generation is required.

[0037] Further description of the electric power storage system related to the present embodiment is made with reference to (b) in FIG. 12. For example, in the third period from the time t21 to the time t22 of (b) in FIG. 12, electric power can be generated by the power generation accompanying the ascent of the kite 22. In the fourth period from the time t22 to the time t23, the kite 22 can be recovered. The electric power obtained by the power generation in the third period is distributed to the main accumulator 27 and the sub-accumulator 28. For example, 1 MW of electric power can be supplied to the main accumulator 27, 1 MW of electric power can be supplied to the electric power storage device 281 of the sub-accumulator 28, and 0.5 MW of electric power can be supplied to the electric power storage device 282 of the sub-accumulator 28. For example, 1 MW of electric power can be supplied from the electric power storage device 281 to the main accumulator 27 in the fourth period. In this case, the control unit 25 can control the electric power storage device 281 in such a manner that electric power is supplied from the electric power storage device 281 to the main accumulator 27 in the fourth period. Figure 4 Figure 4 Further description of the electric power storage system related to the present embodiment is made with reference to (b) in FIG. 12. For example, in the third period from the time t21 to the time t22 of (b) in FIG. 12, electric power can be generated by the power generation accompanying the ascent of the kite 22. In the fourth period from the time t22 to the time t23, the kite 22 can be recovered. The electric power obtained by the power generation in the third period is distributed to the main accumulator 27 and the sub-accumulator 28. For example, 1 MW of electric power can be supplied to the main accumulator 27, 1 MW of electric power can be supplied to the electric power storage device 281 of the sub-accumulator 28, and 0.5 MW of electric power can be supplied to the electric power storage device 282 of the sub-accumulator 28. For example, 1 MW of electric power can be supplied from the electric power storage device 281 to the main accumulator 27 in the fourth period. In this case, the control unit 25 can control the electric power storage device 281 in such a manner that electric power is supplied from the electric power storage device 281 to the main accumulator 27 in the fourth period.

[0038] In the present embodiment, in the third period, the electric power used in the main accumulator 27 is temporarily accumulated in the electric power storage device 281 of the sub-accumulator 28. Therefore, it is possible to suppress the electric power supplied to the main accumulator 27 in the third period. As a result, it is possible to suppress the rated output related to the hydrogen generation device 271.

[0039] (power adjustment unit 251)

[0040] ​The operation of the power regulation unit 251 will be explained. The power regulation unit 251 can predict the power demand in the power generation float 20. The power demand can be the amount of electricity required for the operation of the power generation float 20. The power regulation unit 251 can obtain the energy storage information of the power storage unit 282 of the auxiliary storage unit 28. For example, the energy storage information can represent at least one of the energy storage capacity and energy storage rate related to the power storage unit 282. For example, the power regulation unit 251 can determine the amount of electricity to be supplied to the power storage unit 282 based on the difference between the predicted power demand and the energy storage capacity of the power storage unit 282.

[0041] For example, the power regulation unit 251 can determine the amount of electricity to be supplied to the main storage unit 27 based on the rated output of the hydrogen generation device 271. For example, the power regulation unit 251 can determine the amount of electricity to be supplied to the power storage unit 281 of the secondary storage unit 28, based on the amount obtained from tethered wind power generation that exceeds the total amount of electricity to be supplied to the main storage unit 27 and the power storage unit 282. Then, the power regulation unit 251 can control the power distribution device 26 to supply the determined amount of electricity to the main storage unit 27, the power storage unit 281, and the power storage unit 282.

[0042] (Technical effect)

[0043] For reference Figure 4 As explained in (a) of the comparative example, in the power storage system, electricity is supplied to the hydrogen generation device 271 during the generation of electricity by the tethered wind power generator, but not during the retrieval of the kite 22 (i.e., when not generating electricity). Therefore, in the power storage system of the comparative example, the rated output related to the hydrogen generation device 271 is relatively large.

[0044] In contrast, in the power storage system of this embodiment, during tethered wind power generation, the power used in the main storage unit 27 is temporarily stored in the power storage unit 281 of the auxiliary storage unit 28, and power is supplied from the power storage unit 281 to the main storage unit 27 when not generating power. Therefore, the power storage system of this embodiment can smooth the power supplied to the main storage unit 27. As a result, the rated output of the hydrogen generation device 271 can be suppressed. Here, the price of the hydrogen generation device 271 is proportional to its rated output. For example, by suppressing the rated output of the hydrogen generation device 271, the manufacturing cost of the power generation float 20 can be suppressed.

[0045] For example, Figure 4The period from time t21 to time t23 in (b) is from tens to hundreds of seconds. That is, one charge-discharge cycle of the power storage device 281 in the secondary storage device 28 is also from tens to hundreds of seconds. As mentioned above, the power storage device 281 can be a double-layer capacitor or a flywheel battery. With this configuration, the cycle life of the power storage device 281 can be relatively long. As a result, the operating cost of the power generation system can be reduced.

[0046] <Change Example>

[0047] Reference Figure 5 A modification example of the power storage system described in the above embodiment will be explained. Figure 5 In this modified example, the main storage unit 27 includes a hydrogen generation device 271, a hydrogen tank 272, and an electricity storage unit 273. The electricity storage unit 273 is an electricity storage unit equivalent to the aforementioned electricity storage unit 281. That is, the electricity storage unit 273 is a device for temporarily storing the electricity used in the hydrogen generation device 271. Figure 5 In the modified example, the secondary storage 28 has a power storage device 282. That is, the secondary storage 28 in the modified example does not have a power storage device 281.

[0048] For example, it can be Figure 4 In (b) of the third period, from time t21 to time t22, electricity is generated by generating electricity as the kite 22 rises. The kite 22 can be retrieved during the fourth period, from time t22 to time t23. The electricity generated during the third period is distributed to the main storage unit 27 and the secondary storage unit 28. For example, 1 MW of electricity can be supplied to the hydrogen generation device 271 of the main storage unit 27, 1 MW of electricity can be supplied to the power storage unit 273 of the main storage unit 27, and 0.5 MW of electricity can be supplied to the power storage unit 282 of the secondary storage unit 28. For example, 1 MW of electricity can be supplied from the power storage unit 273 to the hydrogen generation device 271 during the fourth period.

[0049] According to the modified example, the power storage system is similar to the power storage system described in the above embodiment, and can suppress the rated output related to the hydrogen generation device 271.

[0050] Furthermore, although the above embodiments exemplify tethered wind power generation at sea, the power storage system of the present invention can also be applied to tethered wind power generation on land.

[0051] The invention derived from the above-described embodiments and modifications will be described below.

[0052] The power storage system according to one embodiment is provided with: a power supply unit that supplies at least a part of power generated by alternately repeating unwinding of a tether of a tethered flying body and winding of the tether to a power storage portion that stores power in a predetermined manner and a power holding portion that can charge and discharge power; and a control unit that controls the power holding portion in such a manner that power is supplied from the power holding portion to the power storage portion when the tether is wound.

[0053] In the above-described embodiment, the "kite 22" corresponds to one example of a "flying body", the "hydrogen generation device 271" and the "hydrogen tank 272" correspond to one example of a "power storage portion", the "power storage 281" and the "power storage 273" correspond to one example of a "power holding portion", the "power distribution device 26" corresponds to one example of a "power supply unit", and the "control unit 25" corresponds to one example of a "control unit".

[0054] In the power storage system, the flying body can be tethered to a floating body that can sail on water via the tether.

[0055] In this mode, the power storage system can be provided with: a main storage system that has the power storage portion; and a sub storage system that can charge and discharge power used in use of the floating body, the sub storage system having the power holding portion. In the above-described embodiment, the "main storage 27" corresponds to one example of a "main storage system", and the "sub storage 28" corresponds to one example of a "sub storage system".

[0056] Alternatively, the power storage system can be provided with: a main storage system that has the power storage portion; and a sub storage system that can charge and discharge power used in use of the floating body, the main storage system having the power holding portion.

[0057] In the power storage system, the power holding portion can be an electric double layer capacitor or a flywheel battery.

[0058] The present application is not limited to the above-described embodiments, but can be appropriately changed within the scope that does not violate the gist or the idea of the present application read from the claims and the entire specification, and a power storage system accompanying such a change is also included in the technical scope of the present application.

[0059] Explanation of symbols

[0060] 10… transport ship; 20… power generating float; 21… sail; 22… kite; 23… sailing unit; 24… power generating unit; 25… control unit; 26… power distribution device; 27… main storage; 28… secondary storage; 271… hydrogen generating device; 272… hydrogen tank; 273, 281, 282… power storage.

Claims

1. An electricity storage system, comprising: The power supply unit supplies at least a portion of the generated electricity obtained by alternately and repeatedly unwinding and rewinding the tether of the tethered aircraft to the power storage unit and the power retention unit, wherein... The power storage unit stores electricity in a predetermined manner, and the power holding unit is capable of charging and discharging the electricity; A control unit controls the power holding section in such a way that power is supplied from the power holding section to the power storage section when the tether is wound up.

2. The power storage system as described in claim 1, wherein, The flying object is tethered to a floating body capable of navigating on water via the tether.

3. The power storage system as described in claim 2, wherein, have: The main storage system has the aforementioned power storage unit; A secondary storage system is provided, capable of charging and discharging the electricity used in the operation of the buoy. The secondary storage system includes the power retention unit.

4. The power storage system as described in claim 2, wherein, have: The main storage system has the aforementioned power storage unit; A secondary storage system is provided, capable of charging and discharging the electricity used in the operation of the buoy. The main storage system has the power retention unit.

5. The power storage system as described in claim 1, wherein, The power retention section is a double-layer capacitor or a flywheel battery.

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