Offshore wind turbine system

Abstract

The objective is to provide an offshore wind turbine system capable of transforming the voltage of electricity generated by offshore wind turbines. [Solution] The invention is characterized by comprising a lower structure 20 that supports the offshore wind turbine 10, a storage battery 30 that stores the electricity generated by the offshore wind turbine 10, a converter 50 that converts the electricity discharged from the storage battery 30 into alternating current, and a transformer 40 that transforms the voltage of the electricity converted by the converter 50.

Description

Technical Field

[0001] The present disclosure relates to an offshore windmill system.

Background Art

[0002] Conventionally, electricity generated by offshore wind power has been stored in a battery. Patent Document 1 discloses storing energy generated by a wind power generation device in a battery, and the battery being installed on a floating body.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When storing wind power generated energy in a storage battery, it is necessary to convert from alternating current to direct current by a converter. However, the alternating current voltage of the electricity generated by the wind power generation device may be higher than the alternating current voltage that can be processed by the converter. In this case, before performing the conversion from alternating current to direct current by the converter, it is necessary to transform the alternating current voltage of the electricity generated by the wind power generation device by a transformer. In Patent Document 1, such transformation is not assumed.

[0005] The present disclosure has been made in view of the above circumstances, and an object thereof is to provide an offshore windmill system capable of transforming the electricity generated by an offshore windmill.

Means for Solving the Problems

[0006] An offshore wind turbine system according to one aspect of the present disclosure comprises a substructure that supports an offshore wind turbine, a transformer that transforms the voltage of electricity generated by the offshore wind turbine, and a transmission cable connected to the transformer, wherein the substructure includes a transition piece that supports the tower of the offshore wind turbine. [Effects of the Invention]

[0007] According to this disclosure, it is possible to provide an offshore wind turbine system that can transform the voltage of the electricity generated by the offshore wind turbine. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of the offshore wind turbine system 1 according to an embodiment. [Figure 2] This is a front view of a first example of an offshore wind turbine system 1 according to an embodiment. [Figure 3] This is a plan view of the transition piece 21 in Figure 2. [Figure 4] This is a front view of a second example of the offshore wind turbine system 1 according to the embodiment. [Figure 5] This is a front view of a third example of the offshore wind turbine system 1 according to the embodiment. [Figure 6] This is a cross-sectional view showing the internal structure of the transition piece 21 provided in the lower structure 20 according to the embodiment. [Figure 7] This is a schematic diagram of a first example of the circuit of the offshore wind turbine system 1 according to the embodiment. [Figure 8] This is a schematic diagram of a second example of the circuit of the offshore wind turbine system 1 according to the embodiment. [Modes for carrying out the invention]

[0009] Hereinafter, an offshore wind turbine system according to one embodiment of this disclosure will be described with reference to the drawings. The offshore wind turbine system according to this embodiment may be installed as a single unit or in multiple units in the same sea area or wind farm. If multiple offshore wind turbine systems are installed, for example, adjacent offshore wind turbines may be connected by power transmission cables to exchange electricity generated by each other.

[0010] (Overview of offshore wind turbine systems) Figure 1 is a perspective view of the offshore wind turbine system 1 according to an embodiment. Figure 2 is a front view of a first example of an offshore wind turbine system 1 according to an embodiment. Figure 3 is a plan view of the transition piece 21 in Figure 2. Figure 4 is a front view of a second example of the offshore wind turbine system 1 according to the embodiment. Figure 5 is a front view of a third example of the offshore wind turbine system 1 according to the embodiment. Figure 6 is a cross-sectional view showing the internal structure of the transition piece 21 provided in the lower structure 20 according to the embodiment. As shown in Figures 1 to 6, the offshore wind turbine system 1 includes an offshore wind turbine 10, a substructure 20, a battery 30, a transformer 40, a converter 50, and a transmission cable 60.

[0011] The offshore wind turbine 10 has a known configuration. As shown in Figure 1, the offshore wind turbine 10 consists of blades 11, a hub 12, a nacelle 13, and a tower 14. The offshore wind turbine 10 is located offshore and generates electricity by transmitting the rotation of the blades 11 to a generator. The electricity generated by the offshore wind turbine 10 in this way is transmitted to the outside of the offshore wind turbine system 1. That is, for example, the electricity generated by the offshore wind turbine 10 is transmitted to another offshore wind turbine 10 located one side away, or to a power plant on land.

[0012] In this embodiment, in addition to the above configuration, the offshore wind turbine 10 includes a first generator G1 and a second generator G2, as shown in Figures 1, 7, and 8. The first generator G1 and the second generator G2 are installed inside the nacelle 13 of the offshore wind turbine 10, for example, as shown in Figure 1. Alternatively, the first generator G1 and the second generator G2 may be installed inside the tower 14 of the offshore wind turbine 10. Furthermore, a transformer for transforming the electricity generated by the first generator G1 and the second generator G2 may also be installed inside the tower 14 of the offshore wind turbine 10. This is preferable so that the first generator G1 and the second generator G2 and the transformer are not exposed to the outside air at sea. The transmission routes for the electricity generated by the first generator G1 and the second generator G2 will be described later. Hereafter, the power generation by either the first generator G1 or the second generator G2 of the offshore wind turbine 10 will simply be referred to as power generation by the offshore wind turbine 10.

[0013] The substructure 20 is a structure that supports the offshore wind turbine 10. The substructure 20 can preferably be any known configuration. For example, the substructure 20 can preferably be any of the following: a jacket-type foundation as shown in Figure 2, a monopile-type foundation as shown in Figure 4, or a floating-type foundation as shown in Figure 5. The monopile foundation shown in Figure 4 is constructed by providing a transition piece 21 on top of a monopile 20M driven into the seabed. The monopile foundation shown in Figure 4 has a configuration corresponding to the center pipe 21a described later. The center pipe 21a in the monopile foundation shown in Figure 4 is, for example, cylindrical. Alternatively, the center pipe 21a in the monopile foundation shown in Figure 4 may have a shape that widens in diameter from top to bottom. The floating foundation shown in Figure 5 consists of a floating body 20F that floats on the sea surface, supported by wires 20W connected to the seabed. The floating foundation shown in Figure 5 includes a configuration corresponding to a center pipe 21a. In the floating foundation shown in Figure 5, the center pipe 21a is supported on the sea surface by the buoyancy acting on the floating body 20F. In this embodiment, as shown in FIG. 2, the substructure 20 is a jacket foundation. That is, the substructure 20 includes at least a transition piece 21 to which the lower end of the tower 14 of the offshore wind turbine 10 is connected and which supports the tower 14 of the offshore wind turbine 10, and legs 22 that support the transition piece 21. As shown in FIG. 2, the substructure 20 is arranged offshore by connecting the legs 22 to the piles P driven into the seabed.

[0014] The transition piece 21 includes a center pipe 21a to which the lower end of the tower 14 of the offshore wind turbine 10 is connected at the upper end. The transition piece 21 also includes flanges 21b arranged above and below the center pipe 21a, and webs 21c that reinforce the connection between the center pipe 21a and the flanges 21b.

[0015] The center pipe 21a is provided at the center of the transition piece 21. The center pipe 21a is a tubular member, and its pipe axis extends in the vertical direction. The diameter of the center pipe 21a is the same as the diameter of the portion of the tower 14 of the offshore wind turbine 10 that is connected to the center pipe 21a. The flanges 21b are plate-like members provided above and below the center pipe 21a, respectively. The flanges 21b connect the center pipe 21a and the legs 22 above and below the center pipe 21a. In this embodiment, the substructure 20, which is a jacket foundation, includes four legs 22. Therefore, in this embodiment, the flanges 21b are preferably formed in a cross shape as shown in FIG. 3, for example. The web 21c reinforces the connection between the center pipe 21a and the flange 21b, and the connection between the flange 21b and the leg 22. In this way, the web 21c reinforces the connection between the center pipe 21a and the leg 22, and also reinforces the overall structure of the transition piece 21. As shown in Figure 3, two webs 21c are provided between the center pipe 21a and one of the legs 22. In this way, the transition piece 21 has a closed region 21A between the center pipe 21a and each of the legs 22. The closed region 21A refers to the portion enclosed by the center pipe 21a, the flanges 21b positioned above and below the center pipe 21a, and the web 21c.

[0016] As shown in Figure 6, the transition piece 21 is provided with a first floor F1, a second floor F2, and a third floor F3. The first floor F1, the second floor F2, and the third floor F3 are all provided inside the center pipe 21a. Providing these floors inside the center pipe 21a is common to both the monopile foundation shown in Figure 4 and the floating foundation shown in Figure 5.

[0017] As shown in Figure 6, the first floor F1 is one of the floors of the transition piece 21, and is the floor to which the lower end of the tower 14 of the offshore wind turbine 10 is connected. The first floor F1 is the floor located at the very top of the center pipe 21a in the transition piece 21. An interface flange IF is provided at the upper end of the first floor F1, that is, at the upper end of the center pipe 21a, for connecting to the lower end of the tower 14 of the offshore wind turbine 10. A similar interface flange IF is also provided at the lower end of the tower 14 of the offshore wind turbine 10. The lower end of the tower 14 of the offshore wind turbine 10 and the first floor F1 are connected by fastening these interface flanges IF with bolts B, as shown in Figure 6.

[0018] As shown in Figure 6, the second floor F2 is one of the floors of the transition piece 21 and is located below the first floor F1. The second floor F2 is the floor one level below the first floor F1 in the transition piece 21. In this embodiment, the second floor F2 is provided with a battery 30, a transformer 40, and a converter 50 (details will be described later).

[0019] As shown in Figure 6, the third floor F3 is one of the floors of the transition piece 21 and is located below the second floor F2. That is, in the transition piece 21, the first floor F1, the second floor F2, and the third floor F3 are provided in order from top to bottom. Various cables C, including submarine cables, which are deployed in the sea area where the substructure 20 is installed, are placed on the third floor F3. For this reason, it is preferable that no components other than cables C are placed on the third floor F3. However, this is not limited to this, and various equipment such as a storage battery 30, a transformer 40, and a converter 50 may be installed on the third floor F3. In this case, the heights of the first floor F1, the second floor F2, and the third floor F3 may be adjusted as appropriate.

[0020] The battery 30 stores the electricity generated by the offshore wind turbine 10. Here, the voltage of the electricity generated by the offshore wind turbine 10 may change due to changes in wind strength at the installation site of the offshore wind turbine 10, or changes in the frequencies of the first generator G1 and the second generator G2. In this case, if the power generated by the offshore wind turbine 10 becomes high, it may exceed the capacity of the first transmission cable 61 (described later) that transmits the electricity generated by the offshore wind turbine 10 to the outside. In other words, the electricity generated by the offshore wind turbine 10 may add a current to the first transmission cable 61 that exceeds the allowable range. A portion of the electricity generated by the offshore wind turbine 10 is stored in the battery 30. The remaining electricity is then transmitted to the first transmission cable 61. In this way, the current flowing through the first transmission cable 61 is adjusted. After the current flowing through the first transmission cable 61 is adjusted, the electricity stored in the battery 30 is discharged to adjust the power output of the offshore wind turbine 10 and transmitted through the first transmission cable 61. By transmitting the electricity generated by the offshore wind turbine 10 in this manner, it is possible to prevent the first transmission cable 61 from receiving a current that exceeds the permissible range.

[0021] The battery 30 is provided in the lower structure 20. More specifically, the battery 30 is provided inside the lower structure 20. In this embodiment, the battery 30 is provided inside the transition piece 21 of the lower structure 20. In other words, the battery 30 is installed on the second floor F2 of the center pipe 21a in the transition piece 21, as shown in Figure 6, for example. Alternatively, the battery 30 may be placed in the enclosed region 21A formed in the transition piece 21 as described above, as shown in Figure 3, for example. This is preferable to prevent the battery 30 from being exposed to the outside air at sea.

[0022] The converter 50 converts the electricity transmitted by the transmission cable 60 from alternating current (AC) to direct current (DC), or from direct current to AC. For example, when storing electricity generated by the offshore wind turbine 10 in the battery 30, the converter 50 converts AC to DC. Then, when discharging the electricity stored in the battery 30, it converts it back from DC to AC. In other words, the electricity stored in the battery 30 is discharged as DC. For example, a known Power Conditioning System (PCS) is preferably used for the converter 50.

[0023] The converter 50 is provided in the substructure 20. More specifically, the converter 50 is provided inside the substructure 20. In this embodiment, the converter 50 is provided inside the transition piece 21 of the substructure 20. In other words, as shown in Figure 6, the converter 50 is installed on the second floor F2 of the center pipe 21a in the transition piece 21. This is preferable so that the converter 50 is not exposed to the outside air at sea. Alternatively, the converter 50 may be placed in a closed region 21A, for example, as shown in Figure 3.

[0024] The transformer 40 transforms, for example, the voltage of the electricity generated by the offshore wind turbine 10, and the voltage of the electricity discharged from the battery 30 and converted by the converter. The transformer 40 also transforms the voltage of the electricity transmitted through the transmission cable 60. In this embodiment, the voltage of the electricity generated by the offshore wind turbine 10 is higher than the voltage that the converter 50 can process. Therefore, the transformer 40 steps down the voltage of the electricity generated by the offshore wind turbine 10 to a voltage that the converter 50 can process when storing the electricity in the battery 30 via the converter 50. This prevents an excessive voltage from being applied to the converter 50. The transformer 40 may step up the voltage of the electricity discharged from the battery 30 and converted from DC to AC by the converter 50. This may improve the efficiency of power transmission within the offshore wind turbine system 1. Alternatively, the transformer 40 may boost the voltage of the electricity transmitted when transmitting the electricity generated by the offshore wind turbine 10 to the outside. This may improve the efficiency of transmitting power from the offshore wind turbine system 1 to the outside.

[0025] In this embodiment, the transformer 40 is provided on the offshore wind turbine 10, for example, as shown in Figure 1. Alternatively, the transformer 40 may be provided on the substructure 20, as shown in Figure 6. More specifically, the transformer 40 may be provided inside the substructure 20. Furthermore, in this embodiment, the transformer 40 includes a first transformer 41 and a second transformer 42, as shown in Figure 1 or Figures 7 and 8. When these are not distinguished, they are referred to as the transformer 40.

[0026] The first transformer 41 is installed in the offshore wind turbine 10. More specifically, the first transformer 41 is installed inside the nacelle 13 of the offshore wind turbine 10, as shown in Figure 1. Alternatively, the first transformer 41 may be installed inside the tower 14 of the offshore wind turbine 10. This is preferable so that the first transformer 41 is not exposed to the open air at sea. The first transformer 41, arranged in this manner, is used, for example, to boost the voltage of the electricity transmitted when the offshore wind turbine 10 is sent to the outside. In other words, the first transformer 41 is a so-called extra-high voltage transformer capable of boosting a voltage of 690V to 66000V.

[0027] The second transformer 42 is provided in the substructure 20. More specifically, the second transformer 42 is provided inside the substructure 20. In this embodiment, the second transformer 42 is provided inside the transition piece 21 of the substructure 20. In other words, the second transformer 42 is installed on the second floor F2 of the center pipe 21a in the transition piece 21, as shown in Figure 6. This is preferable so that the second transformer 42 is not exposed to the outside air at sea. Alternatively, the second transformer 42 may be placed in the enclosed region 21A shown in Figure 3, for example. The second transformer 42, arranged in this manner, is used, for example, to step down the electricity generated by the offshore wind turbine 10 to a voltage that the converter 50 can process. That is, for example, the second transformer 42 is a transformer capable of stepping down a voltage of 66,000V to 400V or 500V, or a transformer capable of stepping down a voltage of 690V to 400V or 500V. Alternatively, the second transformer 42 may be used to step up the electricity discharged from the battery 30 and converted from DC to AC by the converter 50. Furthermore, if the electricity generated by the offshore wind turbine 10 is at a voltage that the converter 50 can process without stepping down the voltage, the second transformer 42 does not need to be provided.

[0028] The transmission cable 60 is a power transmission cable that connects the above-described components in the offshore wind turbine system 1. The transmission cable 60 can transmit, for example, the electricity generated by the offshore wind turbine 10 and the electricity discharged by the battery 30. That is, the transmission cable 60 has the performance to handle the voltage of the electricity generated by the offshore wind turbine 10 and the electricity discharged by the battery 30, and transmits the electricity generated by the offshore wind turbine 10 and the electricity discharged by the battery 30. More specifically, for example, the transmission cable 60 has a diameter that can handle the voltage of the electricity discharged by the battery 30. In this embodiment, the transmission cable 60 includes a first transmission cable 61 and a second transmission cable 62. Hereinafter, when these are not distinguished, they will be referred to as the transmission cable 60. The first transmission cable 61 is capable of handling a voltage of, for example, 690V. As shown in Figure 6, the first transmission cable 61 passes through the interface flange IF of the transition piece 21 and inside the tower 14 of the offshore wind turbine 10. That is, the first transmission cable 61 extends vertically in the offshore wind turbine system 1, for example. In this way, the first transmission cable 61 is connected to the first generator G1 and the second generator G2 of the offshore wind turbine 10, or to the first transformer 41 located in the nacelle 13 of the offshore wind turbine 10. As described above, the battery 30, converter 50, and transformer 40 are all located on the second floor F2 of the transition piece 21. Therefore, the first transmission cable 61 may be arranged horizontally on the second floor F2 of the transition piece 21, as shown in Figure 6. In this way, the battery 30, converter 50, and transformer 40 may be connected to each other by the first transmission cable 61. The second transmission cable 62 is capable of handling a voltage of, for example, 66,000V. The second transmission cable 62 is connected to, for example, the first transformer 41 or the second transformer 42 and used to transmit power to the outside of the offshore wind turbine system 1.

[0029] (Circuit configuration of offshore wind turbine system) Next, the circuit configuration of the offshore wind turbine system 1 of this embodiment will be described using Figures 7 and 8. Figure 7 is a schematic diagram of a first example of the circuit of the offshore wind turbine system 1 according to the embodiment. In the first example shown in Figure 7, the first generator G1 and the second generator G2 are each connected to the first transformer 41 via a first transmission cable 61. The first transformer 41 is also connected to a second transmission cable 62 for transmitting power to the outside of the offshore wind turbine system 1. Thus, the electricity generated by the first generator G1 and the second generator G2 is transmitted to the first transformer 41 via the first transmission cable 61. After being boosted by the first transformer 41, the electricity is then transmitted to the outside via the second transmission cable 62. In the first example, the first transmission cable 61 connected to the first generator G1 branches off at the first branching point B1. For example, a circuit breaker (not shown) is provided at the first branching point B1. The first transmission cable 61 that branches off at the first branching point B1 is connected to the in-house power supply that operates the offshore wind turbine system 1. In the first example, the first transmission cable 61 connected to the second generator G2 branches off at the second branching point B2. For example, a circuit breaker (not shown) is provided at the second branching point B2. The first transmission cable 61 that branches off at the second branching point B2 is connected to the second transformer 42. In this embodiment, the first generator G1 and the second generator G2 continuously measure the wind speed at the installation site of the offshore wind turbine 10 and predict and calculate the power generated.

[0030] In the first example with such a circuit configuration, the voltage and frequency of the electricity generated by the first generator G1 and the second generator G2 may differ from arbitrarily set reference values. In this case, the electricity generated by the first generator G1 and the second generator G2 is converted from AC to DC, and then from DC to AC voltage and frequency by a converter. After this, the voltage and frequency of the electricity generated by the first generator G1 and the second generator G2 are matched, and then the electricity generated by the first generator G1 and the second generator G2 is transmitted to the first transformer 41 via the first transmission cable 61. The first transformer 41 then boosts the voltage of the electricity thus transmitted and transmits it to the outside via the second transmission cable 62. Furthermore, if strong winds occur at the installation site of the offshore wind turbine 10, and it is anticipated that the voltage of the electricity generated by the first generator G1 and the second generator G2 will exceed an arbitrarily set standard value, a portion of the electricity generated by the first generator G1 will be supplied to the in-house power supply via the first branching point B1. In addition, a portion of the electricity generated by the second generator G2 will be transmitted to the second transformer 42 via the second branching point B2. The second transformer 42 will step down the voltage of the electricity thus transmitted. The stepped-down electricity will be converted from AC to DC by the converter 50 and stored in the storage battery 30. Note that strong winds are defined as wind speeds within the operating range of the offshore wind turbine 10. If the wind speed exceeds the wind speed at which the rated capacity appears within the operating range of the offshore wind turbine 10, the offshore wind turbine 10 will change the angle of its blades 11 to reduce the force of the wind and suppress the rotation speed of the blades 11. This reduces the power output of the first generator G1 and the second generator G2. In addition, by reducing the rotation speed of the blades 11 in the above-mentioned cases, excessive load on the offshore wind turbine 10 is prevented. Furthermore, even if the power of the electricity generated by the first generator G1 does not exceed an arbitrarily set standard value, a portion of the electricity generated by the first generator G1 may be supplied to the in-house power supply via the first branch point B1. For example, electricity may be transmitted externally less during times when the electricity selling price is low, and more during times when the electricity selling price is high.

[0031] Figure 8 is a schematic diagram of a second example of the circuit of the offshore wind turbine system 1 according to the embodiment. In the second example shown in Figure 8, the first generator G1 and the second generator G2 are each connected to the first transformer 41 via a first transmission cable 61. The first transformer 41 is also connected to a second transmission cable 62 for transmitting power to the outside of the offshore wind turbine system 1. Thus, the electricity generated by the first generator G1 and the second generator G2 is transmitted to the first transformer 41 via the first transmission cable 61. After being boosted by the first transformer 41, the electricity is then transmitted to the outside via the second transmission cable 62. In the second example, the first transmission cable 61 connected to the first generator G1 branches off at the first branching point B1. The branched first transmission cable 61 at the first branching point B1 is connected to the in-house power supply of the power plant operating the offshore wind turbine system 1. In the respects described above, the second example is similar to the first example. In the second example, the first transmission cable 61 connected to the second generator G2 does not have a branch point. Also in the second example, the second transmission cable 62 connected to the outside via the first transformer 41 has a third branch point B3. For example, a circuit breaker (not shown) is provided at the third branch point B3. The second transmission cable 62 that branches off at the third branch point B3 is connected to the second transformer 42. In the respects described above, the second example differs from the first example.

[0032] In the second example with such a circuit configuration, the voltage and frequency of the electricity generated by the first generator G1 and the second generator G2 may differ from arbitrarily set reference values. In this case, the electricity generated by the first generator G1 and the second generator G2 is converted from AC to DC and from DC to AC by a converter. After this, the voltage and frequency of the electricity generated by the first generator G1 and the second generator G2 are matched, and then the electricity generated by the first generator G1 and the second generator G2 is transmitted to the first transformer 41 via the first transmission cable 61. The first transformer 41 then boosts the voltage of the electricity thus transmitted and transmits it to the outside via the second transmission cable 62. Furthermore, if strong winds occur at the installation site of the offshore wind turbine 10, and it is anticipated that the power of the electricity generated by the first generator G1 will exceed a arbitrarily set standard value, a portion of the electricity generated by the first generator G1 will be supplied to the plant's power supply via the first branch point B1. In the respects described above, the second example is similar to the first example. In the second example, even if it is assumed that the power of the electricity generated by the second generator G2 exceeds an arbitrarily set standard value, the electricity generated by the second generator G2 is transmitted to the first transformer 41. Then, a portion of the electricity that is stepped up by the first transformer 41 and transmitted to the outside is transmitted to the second transformer 42 via the third branch point B3. The second transformer 42 steps down the electricity thus transmitted. The stepped-down electricity is converted from AC to DC by the converter 50 and stored in the battery 30. In the respects described above, the second example differs from the first example.

[0033] As described above, the offshore wind turbine system 1 according to this embodiment includes a battery 30 for storing electricity generated by the offshore wind turbine 10, a converter 50 for converting the electricity discharged from the battery 30 into alternating current, and a transformer 40 for transforming the voltage of the electricity converted by the converter 50. Here, the amount of electricity generated by the offshore wind turbine 10 may vary depending on the wind speed at the installation site of the offshore wind turbine 10. In this case, for example, if the transmission cable 60 (second transmission cable 62) that transmits the electricity generated by the offshore wind turbine 10 to the outside is to be able to handle the peak value of the current (allowable current) due to the power generated by the offshore wind turbine 10, a larger diameter second transmission cable 62 will be required, which will increase costs. The offshore wind turbine system 1 has a battery 30, which allows the electricity generated by the offshore wind turbine 10 to be stored in the battery 30. For example, when strong winds blow at the installation site of the offshore wind turbine 10 and the power generated by the offshore wind turbine 10 increases, a portion of the electricity generated by the offshore wind turbine 10 is transmitted, and the remainder is stored in the battery 30. Then, after the power generated by the offshore wind turbine 10 decreases, the electricity stored in the battery 30 is transmitted. By transmitting the electricity generated by the offshore wind turbine 10 in this way, it becomes possible to handle peak current reduction in the second transmission cable 62. In other words, the second transmission cable 62 can be made thinner than the one that can handle the peak power generated by the offshore wind turbine 10. Therefore, the cost of the transmission cable 60 (second transmission cable 62) can be reduced. Furthermore, the battery 30 can replace the emergency generator during a power outage. Therefore, it becomes unnecessary to install a separate emergency generator. Furthermore, the offshore wind turbine system 1 has a transformer 40, which allows the voltage of the electricity stored in the battery 30 to be appropriately transformed to a suitable value when transmitting it. In addition, the transformer 40 can transform the voltage of the electricity generated by the offshore wind turbine 10 to a voltage that can be processed by a converter located outside the offshore wind turbine system 1, which has a different operating voltage than the converter 50.

[0034] Furthermore, the transformer 40 is installed on the offshore wind turbine 10. This allows the transformer 40, which adjusts the voltage of the electricity generated by the generator of the offshore wind turbine 10, to also be used to adjust the power (output) when transmitting the electricity stored in the battery 30.

[0035] Furthermore, the transformer 40 includes a first transformer 41 installed on the offshore wind turbine 10 and a second transformer 42 installed on the substructure 20. This allows the offshore wind turbine 10 to transmit electricity to the outside, that is, for example, when transmitting electricity generated by one of several offshore wind turbines 10 installed offshore to an offshore wind turbine 10 located next to that one, the first transformer 41 can boost the voltage for transmission, and the second transformer 42 can lower the voltage for storage in the battery 30. Thus, for example, the offshore wind turbine system 1 can efficiently perform power storage and transmission.

[0036] Furthermore, the transformer 40 is installed in the substructure 20. This allows, for example, the transformer 40 and the battery 30 to be placed close to each other. Therefore, for example, both the transformer 40 and the battery 30 can be easily placed inside the substructure 20 that supports the offshore wind turbine 10. Consequently, for example, the exposure of the transformer 40 and the battery 30 to the outside air at sea can be reduced. Therefore, it is possible to contribute to corrosion prevention of the transformer 40 and the battery 30.

[0037] Furthermore, the transformer 40 is installed inside the substructure 20. This prevents the transformer 40 from being exposed to the outside air, for example, when at sea. Therefore, it contributes to preventing corrosion of the transformer 40.

[0038] Furthermore, the substructure 20 includes a transition piece 21 that supports the tower 14 of the offshore wind turbine 10. The transformer 40 is installed inside the transition piece 21. This makes it possible to prevent the transformer 40 from being exposed to the outside air, for example, offshore. Thus, it can contribute to preventing corrosion of the transformer 40.

[0039] Furthermore, the battery 30 is installed inside the lower structure 20. This prevents the battery 30 from being exposed to the outside air, for example, when at sea. Thus, it contributes to preventing corrosion of the battery 30.

[0040] Furthermore, the substructure 20 has a transition piece 21 that supports the tower 14 of the offshore wind turbine 10. The battery 30 is installed inside the transition piece 21. This makes it possible to prevent the battery 30 from being exposed to the outside air, for example, when it is offshore. Thus, it can contribute to preventing corrosion of the battery 30.

[0041] Furthermore, the battery 30 is located on one of the floors of the transition piece 21, on a floor (second floor F2) below the floor to which the lower end of the tower 14 of the offshore wind turbine 10 is connected. This allows the battery 30 to be positioned at a relatively low location within the transition piece 21. For example, if the substructure 20 is a monopile foundation, the battery 30 can be positioned close to the top of the grout at the point where the pile P and the transition piece 21 are grout-jointed. This makes it easier to connect the cable C for transmitting the electricity stored in the battery 30 from below the transition piece 21.

[0042] Furthermore, the substructure 20 includes a transition piece 21 that supports the tower 14 of the offshore wind turbine 10. The battery 30 is located on one of the floors of the transition piece 21, on a floor (second floor F2) below the floor to which the lower end of the tower 14 of the offshore wind turbine 10 is connected. The second floor F2 is also where the transformer 40 is located. In other words, in the transition piece 21, the battery 30 and the transformer 40 are located on the same floor. This allows, for example, the transmission cable 60 (first transmission cable 61) connecting the battery 30 and the transformer 40 to be shortened. Thus, the volume of the first transmission cable 61 located inside the transition piece 21 can be reduced. Consequently, the proportion of the internal space of the transition piece 21 occupied by the first transmission cable 61 can be reduced. In addition, the cost of the transmission cable 60 (first transmission cable 61) can be reduced.

[0043] Furthermore, the substructure 20 includes a transition piece 21 that supports the tower 14 of the offshore wind turbine 10. The battery 30 is installed inside the transition piece 21. The transmission cable 60 passes through the interface flange IF of the transition piece 21 and inside the tower 14. By arranging the transmission cable 60 as described above, bending of the transmission cable 60 can be suppressed. Therefore, for example, the load on the transmission cable 60 can be suppressed. Consequently, the lifespan of the transmission cable 60 can be extended.

[0044] The technical scope of this disclosure is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of this disclosure. For example, the battery 30, converter 50, and transformer 40 may be provided on an external work platform (not shown) provided on the transition piece 21. In this case, it is preferable that the battery 30, converter 50, and transformer 40 are housed inside a rust-proofed box. Alternatively, the battery 30, converter 50, and transformer 40 may be installed at an onshore power plant that operates the offshore wind turbine system 1. Furthermore, the electricity discharged from the battery 30 may be used for corrosion protection. In other words, the current flowing from the battery 30 may be used as a corrosion protection current for the lower structure 20.

[0045] Furthermore, it is possible to replace the components in the above embodiments with well-known components as appropriate, without departing from the spirit of this disclosure, and the above-described modifications may be combined as appropriate.

[0046] (Note) The offshore wind turbine system according to the above embodiment can be understood, for example, as follows: <1> An offshore wind turbine system according to one aspect of the present disclosure is characterized by comprising: a substructure that supports an offshore wind turbine; a battery for storing electricity generated by the offshore wind turbine; a converter for converting the electricity discharged by the battery into alternating current; and a transformer for transforming the voltage of the electricity converted by the converter.

[0047] The above-described offshore wind turbine system includes a battery for storing the electricity generated by the offshore wind turbine, a converter for converting the electricity discharged from the battery into alternating current, and a transformer for changing the voltage of the electricity converted by the converter. Here, the amount of electricity generated by an offshore wind turbine can vary depending on factors such as wind speed at the turbine's installation location. In this case, for example, if the transmission cable used to transmit the electricity generated by the offshore wind turbine to the outside is to be able to handle the peak value of the current (allowable current) generated by the offshore wind turbine, a larger diameter transmission cable will be required, which will increase costs. An offshore wind turbine system equipped with a battery allows the electricity generated by the offshore wind turbine to be stored in the battery. Therefore, for example, when strong winds blow at the installation site and the power generated by the offshore wind turbine increases, a portion of the electricity generated by the offshore wind turbine is transmitted, and the remainder is stored in the battery. Then, after the power generated by the offshore wind turbine decreases, the electricity stored in the battery is transmitted. By transmitting the electricity generated by the offshore wind turbine in this way, it becomes possible to handle peak current reduction in the transmission cable. In other words, the transmission cable can be made thinner than the one required to handle the peak power generated by the offshore wind turbine. Therefore, the cost of the transmission cable can be reduced. Furthermore, the battery can replace the emergency generator during a power outage. Therefore, it becomes unnecessary to install a separate emergency generator. Furthermore, the presence of a transformer in the offshore wind turbine system allows for the appropriate voltage transformation of the electricity transmitted from the battery to a suitable value. Additionally, the transformer can transform the voltage of the electricity generated by the offshore wind turbine to a voltage that can be processed by a converter located outside the offshore wind turbine system, which operates at a different voltage than the aforementioned converter.

[0048] <2> the above <1> In the offshore wind turbine system relating to this, a configuration may be adopted in which the transformer is installed on the offshore wind turbine.

[0049] Furthermore, the transformer is installed on the offshore wind turbine. This allows the transformer, which adjusts the voltage of the electricity generated by the offshore wind turbine's generator, to also be used to adjust the power (output) when transmitting electricity stored in the battery.

[0050] <3> the above <1> or <2> In the offshore wind turbine system relating to the above, the transformer may be configured to include a first transformer provided on the offshore wind turbine and a second transformer provided on the substructure.

[0051] Furthermore, the transformer includes a first transformer installed on the offshore wind turbine and a second transformer installed in the substructure. This allows the electricity generated by the offshore wind turbine to be transmitted to the outside, that is, for example, when transmitting electricity generated by one of several offshore wind turbines installed offshore to an offshore wind turbine located next to that one, the first transformer can be used to boost the voltage for transmission, and the second transformer can be used to lower the voltage for storage in the battery. Thus, for example, the offshore wind turbine system can efficiently perform energy storage and transmission.

[0052] <4> the above <1> from <3> In an offshore wind turbine system according to any one of these embodiments, the transformer may be provided in the substructure.

[0053] Furthermore, the transformer is installed in the substructure. This allows, for example, the transformer and the battery to be placed close to each other. Therefore, for example, both the transformer and the battery can be easily placed inside the substructure that supports the offshore wind turbine. Consequently, for example, the exposure of the transformer and the battery to the open air at sea can be reduced. Therefore, it is easier to prevent corrosion of the transformer and the battery.

[0054] <5> the above <1> from <4> In an offshore wind turbine system according to any one of the above embodiments, the transformer may be provided inside the substructure.

[0055] Furthermore, the transformer is installed inside the substructure. This helps to prevent the transformer from being exposed to the outside air, for example, when at sea. Therefore, it contributes to preventing corrosion of the transformer.

[0056] <6> the above <1> from <5> An offshore wind turbine system according to any one of the above embodiments may be configured such that the substructure includes a transition piece that supports the tower of the offshore wind turbine, and the transformer is provided inside the transition piece.

[0057] Furthermore, the substructure includes a transition piece that supports the tower of the offshore wind turbine. The transformer is installed inside the transition piece. This helps to prevent the transformer from being exposed to the open air, for example, when it is offshore. Therefore, it can contribute to preventing corrosion of the transformer.

[0058] <7> the above <1> from <6> In an offshore wind turbine system according to any one of the embodiments, the storage battery may be provided inside the substructure.

[0059] Furthermore, the battery is installed inside the substructure. This helps to minimize exposure of the battery to the outside air, for example, when at sea. Therefore, it contributes to preventing corrosion of the battery.

[0060] <8> the above <1> from <7> An offshore wind turbine system according to any one of the above embodiments may be configured such that the substructure has a transition piece that supports the tower of the offshore wind turbine, and the battery is provided inside the transition piece.

[0061] Furthermore, the substructure includes a transition piece that supports the tower of the offshore wind turbine. The battery is installed inside the transition piece. This helps to prevent the battery from being exposed to the outside air, for example, when operating offshore. Therefore, it can contribute to preventing corrosion of the battery.

[0062] <9> the above <7> or <8> In the offshore wind turbine system relating to the above, the battery may be configured to be located on one of the floors of the transition piece, on a floor below the floor to which the lower end of the offshore wind turbine tower is connected.

[0063] Furthermore, the battery is installed on one of the floors of the transition piece, below the floor to which the lower end of the offshore wind turbine tower is connected. This allows the battery to be positioned at a relatively low location within the transition piece. For example, if the substructure is a monopile foundation, the battery can be positioned close to the top of the grout at the point where the pile and the transition piece are grout-jointed. This makes it easier to connect the cables for transmitting the electricity stored in the battery from below the transition piece.

[0064] <10> An offshore wind turbine system according to one aspect of the present disclosure comprises a substructure that supports an offshore wind turbine, a battery for storing electricity generated by the offshore wind turbine, and a transformer for transforming the voltage of the electricity discharged by the battery, wherein the substructure includes a transition piece that supports the tower of the offshore wind turbine, the battery is provided on one of the floors of the transition piece, which is below the floor to which the lower end of the tower of the offshore wind turbine is connected, and the transformer is provided on the lower floor.

[0065] Furthermore, the substructure includes a transition piece that supports the offshore wind turbine tower. The battery is located on one of the floors of the transition piece, below the floor to which the lower end of the offshore wind turbine tower is connected. A transformer is also located on this floor. In other words, the battery and transformer are located on the same floor within the transition piece. This allows, for example, the transmission cable connecting the battery and the transformer to be shortened. Thus, the volume of the transmission cable located inside the transition piece can be reduced. Consequently, the proportion of the internal space occupied by the transmission cable within the transition piece can be reduced. In addition, the cost of the transmission cable can be reduced.

[0066] <11>The off - shore wind turbine system according to one aspect of the present disclosure includes a substructure that supports an off - shore wind turbine, a storage battery that stores electricity generated by the off - shore wind turbine, a transmission cable capable of transmitting electricity discharged from the storage battery, and a transformer that transforms the voltage of the electricity transmitted by the transmission cable. The substructure includes a transition piece that supports the tower of the off - shore wind turbine. The storage battery is provided inside the transition piece. The transmission cable passes through the interface flange of the transition piece and the inside of the tower.

[0067] Also, the substructure includes a transition piece that supports the tower of the off - shore wind turbine. The storage battery is provided inside the transition piece. And the transmission cable passes through the interface flange of the transition piece and the inside of the tower. By arranging the transmission cable as described above, it is possible to suppress the bending of the transmission cable. Therefore, for example, it is possible to suppress the load applied to the transmission cable. Thus, the service life of the transmission cable can be extended.

Description of Signs

[0068] 1 Off - shore wind turbine system 10 Off - shore wind turbine 11 Blade 12 Hub 13 Nacelle 14 Tower 20 Substructure 21 Transition piece 21a Center pipe 21b Flange 21c Web 22 Leg 30 Storage battery 40 Transformer 41 First transformer 42 Second transformer 50 Converter 60 Transmission cable 61 First transmission cable 62 Second transmission cable B1 First branch point B2 Second Junction B3 Third Junction C Cable F1 1st Floor F2 2nd Floor F3 3rd Floor G1 Generator 1 G2 Second Generator IF Interface Flange

Claims

1. The lower structure that supports the offshore wind turbine, A transformer that transforms the voltage of the electricity generated by the offshore wind turbine, The system includes a transmission cable connected to the transformer, The substructure includes a transition piece that supports the tower of the offshore wind turbine. An offshore wind turbine system characterized by the following features.

2. The transmission cable extends from above the transition piece. The offshore wind turbine system according to claim 1, characterized in that...

3. The transmission cable passes through the interface flange of the transition piece. The offshore wind turbine system according to claim 2, characterized in that...

4. The transmission cable passes through the interface flange of the transition piece and the inside of the tower. The offshore wind turbine system according to claim 3, characterized in that...

5. The transformer is provided in the lower structure, An offshore wind turbine system according to any one of claims 1 to 4, characterized by the features described herein.

6. The transformer is provided inside the lower structure, The offshore wind turbine system according to feature 5.

7. The transformer is provided inside the transition piece. The offshore wind turbine system according to claim 6.

8. The transformer is located on one of the floors of the transition piece, on a floor below the floor to which the lower end of the tower is connected. An offshore wind turbine system according to any one of claims 1 to 4, characterized by the features described herein.

9. The transformer includes a first transformer installed in the offshore wind turbine and a second transformer installed in the substructure. An offshore wind turbine system according to any one of claims 1 to 4, characterized by the features described herein.

10. The transformer is installed on the offshore wind turbine, An offshore wind turbine system according to any one of claims 1 to 4, characterized by the features described herein.

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