How to connect a tether

Abstract

To prevent deterioration in the response of a winch.SOLUTION: A tether coupling method includes a step of coupling another tether different from one tether to the other end of the one tether whose one end is connected to a kite, in a separable manner during flight of the kite.SELECTED DRAWING: Figure 2

Description

[[Technical Field]]

[0001] The present invention relates to the technical field of a method for connecting a tether for mooring a kite. [[Background Art]]

[0002] As this type of method, for example, it has been proposed to connect one fixing rope having one end connected to a submersible power generation platform and another fixing rope having one end connected to a water channel (see Patent Document 1). [[Prior Art Literature]] [[Patent Literature]]

[0003] [[Patent Document 1]] Japanese Unexamined Patent Application Publication No. 2018-508712 [[Summary of the Invention]] [[Problem to be Solved by the Invention]]

[0004] A portion of a tether that moors a kite is often wound around, for example, a drum installed on the ground. The higher the target flight altitude of the kite, the longer the length of the tether that moors the kite. As a result, the size of the drum around which the tether is wound also increases. When the winch is enlarged accompanying the enlargement of the drum, there is a technical problem that the response of the winch deteriorates.

[0005] The present invention has been made in view of, for example, the above problems, and an object of the present invention is to provide a tether connecting method capable of suppressing deterioration of the response of the winch. [[Means for Solving the Problem]]

[0006] A tether connecting method according to one aspect of the present invention includes a step of, during flight of a kite, connecting another tether different from the one tether in a separable manner to the other end of one tether whose one end is connected to the kite. [[Brief Description of the Drawings]]

[0007] [Figure 1] This is a diagram showing an example of a wind power generation system. [Figure 2] This figure shows an example of how to connect tethers. [Figure 3] This flowchart shows an example of how to connect tethers. [Figure 4] This flowchart shows an example of a tether separation method. [Figure 5] This figure shows an example of how tethers are connected. [Modes for carrying out the invention]

[0008] Embodiments relating to the method of connecting tethers will be described with reference to Figures 1 to 5.

[0009] First, an overview of a tethered wind power generation system using a kite will be explained with reference to Figure 1. In Figure 1, the wind power generation system comprises a kite 1 and ground equipment 2. Ground equipment 2 may include a winch with a drum around which a tether for mooring the kite 1 is wound. Ground equipment 2 may further include a generator connected to the rotating shaft of the drum. Since ground equipment 2 moors the kite 1, it may also be called a mooring device. Note that the shape of the kite 1 shown in Figure 1 is just an example and is not limited to this. Note that in Figure 1, there is one tether for mooring the kite 1, but the kite 1 may be moored by multiple tethers.

[0010] In a wind power generation system, when kite 1 rises, a tether is released from the winch drum as the kite 1 rises. This tether release action causes the drum to rotate. As the drum rotates, the generator rotates, generating electricity. Once the tether has been released to a predetermined length, or after a predetermined time has elapsed, the motor in the winch rotates the drum in the direction of winding in the tether. As a result, the kite 1 descends due to the winding action of the tether. In a wind power generation system, electricity is generated by repeatedly performing the tether release and winding actions.

[0011] Next, the method of connecting the tethers for mooring kite 1 will be explained with reference to Figures 2 and 3. Here, we will explain how to extend the tethers for mooring kite 1 by connecting tether 32 to tether 31.

[0012] In Figure 2(a), the tether 31 extending from the drum 21 toward the kite 1 may pass through the lead section 51. One end of the tether 31 is connected to the kite 1. The other end of the tether 31 may be directly connected to the kite 1 or indirectly connected to the kite 1. Here, "indirectly connected" means that the kite 1 and one end of the tether 31 are connected via another component (for example, another tether). The lead section 51 and the lead section 52, which will be described later, may be referred to as fairleads.

[0013] A portion of the tether 31 is wrapped around the drum 21. In this case, the tether 31 may be wrapped around the drum 21 such that the other end 31a of the tether 31 protrudes from the drum 21. In the state shown in Figure 2(a), the rotation axis of the drum 21 may be connected to the generator. The end 31a of the tether 31 is placed in the coupling device 40. Note that if the length of the tether 31 wrapped around the drum 21 becomes shorter than a predetermined length, the end 31a may not be placed in the coupling device 40. In other words, if the length of the tether 31 wrapped around the drum 21 is longer than a predetermined length, the end 31a does not need to be placed in the coupling device 40.

[0014] The tether 32 has an end 32a and an end 32b. The end 32a of the tether 32 is positioned on the coupling device 40. The portion of the tether 32 extending from the drum 22 toward the end 32a may pass through the lead portion 52 and a plurality of guide pulleys. In other words, the end 32a that is drawn out from the drum 22 around which the tether 32 is wound may pass through the lead portion 52 and a plurality of guide pulleys and be positioned on the coupling device 40. As shown in Figure 2(a), the tether 32 may be wound around the drum 22 such that the end 32b of the tether 32 (i.e., the end opposite to the end 32a that is connected to the end 31a of the tether 31) protrudes from the drum 22. The drums 21 and 22 may constitute part of the ground equipment 2 shown in Figure 1. In the state shown in Figure 2(a), the rotating shaft of the drum 22 does not have to be connected to the generator.

[0015] The coupling device 40 may automatically connect tether 31 and tether 32 when, for example, the end 31a of tether 31 and the end 32a of tether 32 are positioned on the coupling device 40. For example, coupling mechanisms may be attached to each of the ends 31a of tether 31 and 32a of tether 32. In this case, the coupling device 40 may connect tether 31 and tether 32 by fitting together the coupling mechanism attached to end 31a and the coupling mechanism attached to end 32a. Examples of coupling mechanisms include mechanical couplings and buckles. In this case, the connected tethers 31 and 32 can be separated by releasing the fitted state of the coupling mechanisms. For example, coupling mechanisms do not need to be attached to each of the ends 31a of tether 31 and 32a of tether 32. In this case, the connecting device 40 may connect tether 31 and tether 32 by twisting together the vicinity of the end 31a of tether 31 and the vicinity of the end 32a of tether 32. In this case, the connected tethers 31 and 32 can be separated by untwisting the twisted tethers 31 and 32. Thus, the connecting mechanism 40 may connect tether 31 and tether 32 in a separable manner.

[0016] After tethers 31 and 32 are connected, for example, tethers 31 and 32 may be removed from the coupling device 40 and the guide pulley. Subsequently, the portion of tether 31 that is wound around the drum 21 may be unwound from the drum 21, thereby removing tether 31 from the lead portion 51 and the drum 21. As a result, as shown in Figure 2(b), tether 32 extends from the drum 22 toward the kite 1. In the state shown in Figure 2(b), the rotation axis of the drum 22 may be connected to a generator. In Figure 2(b), the reference numeral "33" indicates the connection between tether 31 and tether 32. Note that by connecting tether 32 to tether 31, the total length of the tether that moores the kite 1 increases. For this reason, tether 32 may be called an extension tether. Coupling mechanisms may be attached to each of the ends 32a and 32b of tether 32. In this case, the extension tether can be said to have connecting mechanisms at both ends.

[0017] The method of connecting the tethers will be explained with reference to the flowchart in Figure 3. In Figure 3, one end of one tether (for example, end 31a of tether 31) is placed in the connecting device 40 (step S101). In parallel with or immediately before or after the process in step S101, the other end of the tether (for example, end 32a of tether 32) is placed in the connecting device 40 (step S102). The connecting device 40 then connects one tether to the other (step S103).

[0018] In step S101, for example, the coupling device 40 may pull one tether's end into the coupling device 40, thereby positioning one tether's end in the coupling device 40. Similarly, in step S102, for example, the coupling device 40 may pull another tether's end into the coupling device 40, thereby positioning another tether's end in the coupling device 40. The coupling device 40 may connect two or more tethers to one tether.

[0019] Tether 31 and Tether 32 may be of the same type. Tether 31 and Tether 32 may be of different types. For example, connecting Tether 31 and Tether 32 allows Kite 1 to fly at a higher altitude. In other words, Tether 31 will be used at a higher altitude than Tether 32. As altitude increases, the temperature decreases, making the tether (for example, the moisture contained in the tether) more prone to freezing. In view of this, Tether 31 may be a tether with better freeze resistance than Tether 32. In other words, Tether 31 may be a freeze-resistant tether.

[0020] As described above, in a tethered wind power generation system, the tether is repeatedly subjected to paying-out and winding operations for power generation. As shown in FIG. 2(b), when the tether 32 is connected to the tether 31, the tether 32 is wound around the drum 22. In this case, the tether 32 is paid out from the drum 22 and wound onto the drum 22 for power generation. As a result, at least a portion of the tether 32 may be damaged by friction. In view of this point, the tether 32 may be a tether having superior wear resistance compared to the tether 31. In other words, the tether 32 may be a wear-resistant tether.

[0021] Next, a method for separating tethers will be described with reference to FIGS. 2 and 4. Here, a method of shortening the tether mooring the kite 1 by separating the tethers 31 and 32 that moor the kite 1 will be described.

[0022] For example, in the state shown in FIG. 2(b), the tether 32 may be wound onto the drum 22 until the distance from the drum 22 (in other words, the ground equipment 2) to the connecting portion 33 reaches a predetermined distance. Thereafter, the tether 31 may be wound onto the drum 21. This can suppress the tension applied to the tether 31 due to the kite 1 from acting on the connecting portion 33. Thereafter, the connecting portion 33 may be placed on the connecting device 40. Note that when excessive force is not applied to the connecting portion 33 and the connecting device 40, the tether 31 may be wound onto the drum 21 after the connecting portion 33 is placed on the connecting device 40.

[0023] The connecting device 40 may separate an end 31a of the tether 31 and an end 32a of the tether 32 that constitute the connecting portion 33. For example, after the tether 31 and the tether 32 are separated, a rotating shaft of the drum 21 may be connected to a generator. In addition, the drum 22 around which the tether 32 is wound may be removed from the ground equipment 2.

[0024] The method for separating the tethers will be explained with reference to the flowchart in Figure 4. In Figure 4, the tether that moores the kite 1 is wound onto, for example, the drum 22 (step S201). Then, the connecting portion of the tether (for example, the connecting portion 33) is placed on the coupling device 40 (step S202). Before the process in step 202, the tether on the kite 1 side of the connecting portion (for example, tether 31) may be wound onto a drum other than the drum 22 (for example, drum 21). After the process in step S202, the coupling device 40 separates one tether from the other (step S203).

[0025] (Technical effects) The higher the target flight altitude of kite 1, the longer the tethers used to moor kite 1 become. If the length of a single tether is increased to achieve the target flight altitude of kite 1, the size of the drum around which the tethers are wound also increases. In contrast, in this embodiment, the total length of the tethers used to moor kite 1 is increased by connecting tether 32 to tether 31 that moor kite 1. With this configuration, the length of each tether can be made significantly shorter than the length required to achieve the target flight altitude of kite 1. Therefore, the size of the drum around which the tethers (for example, at least one of tethers 31 and 32) are wound (for example, at least one of drums 21 and 22) can be suppressed. Consequently, according to this embodiment, deterioration of winch response can be suppressed.

[0026] In this embodiment, there is no limit to the number of tethers that can be connected. Therefore, in order to reduce the size of the drum around which the tethers are wound, the length of each tether may be shortened. In other words, in this embodiment, the drum may be made smaller by actively shortening the length of each tether. In this case, the winch response can be improved as a result of the smaller drum. In addition, the transportability of the drum (i.e., at least one of the drum around which the tethers are wound and the drum around which the tethers are not wound) can be improved as a result of the smaller drum.

[0027] Furthermore, some of the tethers connected to anchor Kite 1 may be separated. Additionally, new tethers may be attached to the anchoring tether to replace the separated tethers. In other words, some of the tethers anchoring Kite 1 may be replaced. This configuration allows for maintenance of the anchoring tether to Kite 1 while Kite 1 is in flight.

[0028] (First variation) A first modified example of the tether connection method will be described with reference to Figure 4. As described above, two or more tethers may be connected to one tether that moores the kite 1. In the example shown in Figure 5, tethers 32 and 34 are connected to tether 31. In this case, the connection part 33 may refer to the connection part between tether 31, tether 32, and tether 34. Here, tether 34 may be a tether with higher conductivity than tether 32. Furthermore, tether 34 may be grounded.

[0029] Depending on weather conditions, lightning may strike the kite 1 while it is in flight. In this case, if no countermeasures are taken, the current caused by the lightning may flow to the ground equipment 2 (see Figure 1) through the tether that moors the kite 1. In contrast, in the example shown in Figure 5, even if lightning strikes the kite 1 while it is in flight, it can be expected that most of the current caused by the lightning will flow through the tether 34. Therefore, according to the first modification, it is possible to suppress damage to the ground equipment 2 caused by the current caused by the lightning. In this case, the tether 34 may be called a lightning protection tether.

[0030] (Second variation) A second modification of the tether connection method will now be described. The kite 1 according to the second modification may be a kite used in a tethered wind power generation system, or it may be a kite not used in a tethered wind power generation system. Here, an example of a kite not used in a tethered wind power generation system is a kite for solar power generation that is equipped with solar panels.

[0031] In the second modified example, a sensor may be placed at the connection point between one tether and another (for example, the connection point 33 between tether 31 and tether 32 shown in Figure 2(b)). Examples of sensors include at least one of a temperature sensor, humidity sensor, altitude sensor, barometric pressure sensor, wind speed sensor, wind direction sensor, and GPS (Global Positioning System) sensor. The sensor placed at the connection point may also be a radiosonde.

[0032] According to the second modification, for example, weather observations can be performed by a sensor placed at the connection point between one tether and another. In addition, since kite 1 can remain in the air for a relatively long period of time, weather observations can be performed at a fixed point using the sensor.

[0033] Aspects of the invention derived from the embodiments and modifications described above are described below.

[0034] A method for connecting tethers according to one aspect of the invention includes the step of connecting, in a detachable manner, another tether different from the first tether to which one end is attached, to the other end of a tether that is attached to the kite, while the kite is in flight.

[0035] The first tether may be a freeze-resistant tether, and the other tether may be a wear-resistant tether. The other tether may also be a lightning protection tether. Before the first tether is connected to the other tether, a portion of the first tether may be wrapped around the drum such that its other end protrudes from the drum. A sensor may be placed at the connection point between the other end of the first tether and the other tether.

[0036] 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. Methods for connecting tethers that involve such modifications are also included within the technical scope of the present invention. [Explanation of Symbols]

[0037] 1... Kite, 31, 32... Tether

Claims

1. The process includes, during the flight of the kite, attaching, in a detachable manner, another tether, different from the first tether, to the other end of a tether already attached to the kite. A method for connecting tethers, characterized by the features described above.

2. The aforementioned tether is a freeze-resistant tether, The other tether is a wear-resistant tether. The method for connecting tethers according to feature 1.

3. The other tethers mentioned above are lightning protection tethers. The method for connecting tethers according to feature 1.

4. Before the first tether is connected to the other tether, a portion of the first tether is wrapped around the drum such that its other end protrudes from the drum. The method for connecting tethers according to feature 1.

5. A sensor is positioned at the connection point between the other end of the first tether and the other tether. The method for connecting tethers according to feature 1.

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