Mobile body and power transmission method

Abstract

A mobile body in a power transmission system in which a storage battery mounted on the mobile body is charged with power generated by a power generating facility, and power is supplied from the storage battery transferred by the mobile body to a power receiving facility. The mobile body is provided with a battery control device that charges the storage battery by power supply based on a voltage value that does not become the maximum voltage value of the DC power between the power generating facility and the power receiving facility.

Description

Technical Field

[0001] The present invention relates to a mobile object in a power transmission system and a power transmission method of the power transmission system. Background Art

[0002] Conventionally, as an offshore wind power generation system, there is known a power system structure in which a power transmission cable is laid on the seabed or in the sea, and electric power generated by offshore power generation equipment is transmitted to land via the power transmission cable on the seabed.

[0003] In recent years, the development of offshore wind power generation equipment has increased not only in areas with short offshore distances from land, but also in areas with offshore distances exceeding 50 km. The longer the offshore distance, the more it is required to suppress the loss of power caused by long-distance power transmission. Therefore, high-voltage DC cables are generally used for submarine power transmission cables.

[0004] Patent Document 1 listed below discloses a system for transmitting electric power generated by a wind turbine generator using a high-voltage DC cable.

[0005] (Prior art literature)

[0006] (Patent Document)

[0007] Patent Document 1: Japanese Patent Application Laid-Open No. 2018-107980 Summary of the invention

[0008] (Problems to be solved by the invention)

[0009] When using high-voltage DC cables for DC transmission, in order to suppress transmission losses, it is necessary to install a high-voltage output transformer at a collection station or offshore substation to step up the voltage.

[0010] Therefore, the electrical equipment in the power transmission system is required to be able to cope with high voltage specifications. In addition to expensive DC submarine transmission cables, the transmission and receiving ends also need AC-DC converters that can cope with high voltages and DC circuit breakers that ensure high reliability. In order to cope with these problems, the structure of the power transmission system is complicated and the cost increases accordingly.

[0011] Therefore, in the present disclosure, a technology capable of promoting simplification of structure and reduction of cost in a power transmission system is proposed.

[0012] (Measures taken to solve the problem)

[0013] The mobile body according to the present invention is a mobile body in a power transmission system, in which power generated by a power generation device is charged to a storage battery mounted on the mobile body, and power is supplied from the storage battery transferred by the mobile body to a power receiving device. The mobile body includes a battery control device, which charges the storage battery by supplying power based on a voltage value that does not become a maximum voltage value of DC power between the power generation device and the power receiving device.

[0014] That is, the charging voltage of the storage battery mounted on the mobile object is a predetermined voltage lower than the maximum voltage value of the electric power between the power generating facility and the power receiving facility.

[0015] (Effects of the Invention)

[0016] According to the present invention, by replacing power transmission based on a DC submarine cable with power transmission based on a mobile body equipped with a storage battery, it is not necessary to increase the voltage for suppressing power transmission loss. In addition, it is not necessary to have equipment to handle high voltage. Therefore, it is possible to greatly simplify the structure of the power transmission system and reduce costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is an explanatory diagram of a power transmission system according to an embodiment of the present invention.

[0018] Figure 2 This is a diagram for explaining the charging and discharging structure of the storage battery of the power transport ship according to the embodiment.

[0019] Figure 3 It is an explanatory diagram of a power transmission system using a high-voltage DC cable as a comparative example.

[0020] Figure 4 It is an explanatory diagram of the transition of the voltage level of the power transmission system according to the embodiment. DETAILED DESCRIPTION

[0021] Hereinafter, the embodiments will be described in the following order.

[0022] <1. Configuration of power transmission system according to embodiment>

[0023] <2. Comparative example of a power transmission system using a high-voltage DC cable>

[0024] <3. Voltage Transition of Power Transmission System According to Embodiment>

[0025] <4. Effects and Modifications of Embodiment>

[0026] <1. Configuration of power transmission system according to embodiment>

[0027] Figure 1The figure shows an overview of a power transmission system 1 according to an embodiment. In the figure, as main components of the power transmission system 1, a wind turbine 2, an array cable 3, an offshore converter station 4, an onshore substation 5, a cable 6, a power system 7, a connector cable 8, a connector cable 9, and a power carrier 10 are shown.

[0028] The wind turbine generator 2 is installed at sea. Although the sea area is not particularly limited, in the case of the power transmission system 1, the wind turbine generator 2 is preferably installed in a sea area that is more than 50 km from the shore, for example.

[0029] For example, one or more wind power generation devices 2 are provided in a floating structure, and an offshore converter station 4 is provided for one or more wind power generation devices 2 .

[0030] The AC power generated by each wind turbine generator 2 is converted into DC as described later and then transmitted to an offshore converter station 4 via an array cable 3 which is a DC cable.

[0031] The offshore converter station 4 functions as an offshore substation having facilities for supplying electric power generated by the wind turbine generator 2 to the electric power carrier 10 as a mobile body.

[0032] The power transfer ship 10 is a ship that carries a storage battery 14 .

[0033] The offshore converter station 4 has a device for connecting the connector cable 8 to the power transfer ship 10. Thus, the offshore converter station 4 can supply power for charging the storage battery 14 of the power transfer ship 10 based on the power generated by the wind turbine generator 2.

[0034] That is, when the power transfer ship 10 arrives near the offshore converter station 4, the offshore converter station 4 and the power transfer ship 10 are electrically connected via the connector cable 8, and the power collected from the wind turbine 2 to the offshore converter station 4 is supplied to the power transfer ship 10 via the charging connector cable 8. In the power transfer ship 10, the storage battery 14 is charged with the power.

[0035] The power transfer ship 10 that has completed charging of the storage battery 14 sails toward the onshore substation 5 that is a power receiving facility.

[0036] The land substation 5 has a device for connecting the connector cable 9 to the power carrier 10. Thus, the land substation 5 can receive the discharge current from the storage battery 14.

[0037] That is, when the power carrier 10 arrives near the onshore substation 5, the onshore substation 5 and the power carrier 10 are electrically connected via the connector cable 9, and the DC power is transmitted from the storage battery 14 to the onshore substation 5 via the connector cable 9. The onshore substation 5 converts the transmitted DC power into AC power and transmits it to the power system 7 via the cable 6.

[0038] In this way, the power transmission system 1 of the embodiment transmits electric energy from the offshore wind turbine 2 to the onshore substation 5 via the power carrier 10 equipped with the storage battery 14. That is, the power transmission system 1 transmits electric energy from the offshore wind turbine 2 to the power grid 7 via the stage of transmission from the storage battery 14.

[0039] Although it depends on the power source of the power carrier 10, even if it is a motor-type power carrier 10 powered by electricity, it can sail about 300 km to 500 km on the sea without charging. Therefore, the distance from the offshore wind power generation equipment 2 to the onshore substation 5 can also be about 300 km to 500 km.

[0040] Figure 2 Components related to the storage battery 14 in the power transport ship 10 are shown.

[0041] The power carrier ship 10 is a motor ship using electricity as a power source. However, the power carrier ship 10 may be an internal combustion engine ship using fossil fuel as a power source, or a hybrid ship using a motor and an internal combustion engine. In addition, the power carrier ship 10 may use hydrogen as a power source. For example, when hydrogen is used as a power source, the power carrier ship 10 may be a fuel cell ship that uses electricity generated by a fuel cell to drive a motor, or a hydrogen engine ship that obtains power by burning hydrogen in an internal combustion engine.

[0042] The power carrier 10 includes a charge / discharge port 11, a DC / DC converter 12, and a battery control device 13 as components directly related to the storage battery 14. The storage battery 14 is composed of a plurality of battery cells 14a.

[0043] The charge and discharge port 11 is an interface for charging and discharging each battery cell 14 a , and the connector cables 8 and 9 can be attached and detached for charging and discharging.

[0044] The DC / DC converter 12 receives the DC voltage supplied from the charging and discharging port 11 and performs voltage conversion.

[0045] The battery control device 13 is connected to each battery cell 14 a and includes a circuit for charging and discharging each battery cell 14 a and a control circuit for controlling the charge amount, discharge amount, charge speed, and discharge speed.

[0046] Specifically, the battery control device 13 is equipped with a charging and discharging circuit for each battery cell 14 a , a microprocessor, a memory storing a control program, a communication circuit with an external device, and a sensor for detecting the charging state of the battery cell 14 a .

[0047] When the power transfer ship 10 is connected to the connector cable 8 of the offshore converter station 4 , the battery control device 13 charges the battery unit 14 a based on the DC voltage converted by the DC / DC converter 12 .

[0048] When the power carrier 10 is connected to the connector cable 9 of the land substation 5, the battery control device 13 controls the discharge from the battery unit 14a. The discharged DC voltage is converted by the DC / DC converter 12 and sent from the connector cable 9 to the land substation 5.

[0049] In addition, the above-mentioned charging and discharging ports 11, DC / DC converter 12, battery control device 13 and storage battery 14 can also be set in a container that can be loaded and unloaded from the hull. Thus, for example, the container can be unloaded from the hull and transferred to the offshore converter station 4 to charge the storage battery 14. And, for example, the container can be unloaded from the hull and transferred to the onshore substation 5 to discharge from the storage battery 14 (transmission to the onshore substation 5).

[0050] The power transfer ship 10 has the same structure as a general motor-type ship using electricity as a power source, for example. That is, the power transfer ship 10 includes a driving battery 17, an inverter 15, a motor 16, and the like.

[0051] The driving battery 17 stores electric power consumed as a power source for the power carrier 10 or internal devices.

[0052] The inverter 15 controls or converts the electric power output from the driving battery 17 and supplies the electric power to the motor 16 .

[0053] The motor 16 converts the electric power received from the inverter 15 into motive power. For example, the motor 16 rotates a propeller via a shaft (not shown), thereby obtaining a propulsion force of the electric power transfer ship 10.

[0054] As described above, since the power transfer ship 10 includes the driving battery 17 separately from the storage battery 14 storing the power for transmission, the ship can sail without consuming the power in the storage battery 14 (battery unit 14a).

[0055] However, in the example shown in the figure, the driving battery 17 is electrically connected to the battery unit 14a via the battery control device 13. Therefore, in an emergency, the power in the battery unit 14a can be supplied to the driving battery 17. That is, the power carrier 10 can also sail using the power in the battery unit 14a as a power source.

[0056] <2. Comparative example of a power transmission system using a high-voltage DC cable>

[0057] As described above, the power transmission system 1 of the present embodiment transmits power via the power carrier 10 . Before describing voltage transition in the power transmission system 1 , a power transmission system 201 using a high-voltage DC cable will be described for comparison.

[0058] Figure 3 The structure related to voltage conversion of a power transmission system 201 based on a high voltage direct current cable and the transition of voltage levels are shown.

[0059] The power transmission system 201 collects the power generated by offshore wind power generation equipment 202 to an offshore AC collection station 204, and then further steps up the voltage and converts it into DC at an offshore AC / DC converter station 206. The power is then transmitted via a high-voltage DC submarine cable 207.

[0060] The transmission power is transmitted from the landing point 208 to the onshore substation 209 and then transmitted to the power system 7.

[0061] In the power transmission system 201, in the wind power generation equipment 202, the generator 221 extracts AC power of about 300V. Then, it is converted into DC by the AC / DC converter 222. Further, after being converted into AC by the DC / AC converter 223, it is stepped up to about 3kV by the transformer 224 and sent to the array cable 203 which is an AC cable.

[0062] In the wind power generation equipment 202, the AC / DC converter 222 and the DC / AC converter 223 temporarily convert the power into DC, and then convert the power into AC again for variable speed operation (output adjustment) of the wind turbine. In the case of the power transmission system 201, the generator 221 is always connected to the power system 7. Therefore, it is necessary to adjust the output according to the power demand and other conditions on the power system 7 side, and this adjustment is performed by controlling the DC stage.

[0063] The transformer 224 is provided to obtain AC voltage increased by power transmission of the array cable 3. The voltage increase by the transformer 224 also means stepwise voltage increase before reaching the high-voltage DC submarine cable 207 together with the transformers 241 and 261 at the subsequent stage.

[0064] The AC power transmitted by the array cable 203 to the offshore AC collection station 204 is further boosted to about 200 kV by the transformer 241 and transmitted to the offshore AC / DC conversion station 206 via the cable 205 .

[0065] In the offshore AC / DC conversion station 206 , the voltage is boosted to above 500 kV by the transformer 261 , converted into DC by the AC / DC converter 262 , and transmitted via the high-voltage DC submarine cable 207 .

[0066] In the onshore substation 209, the DC power transmitted by the high-voltage DC submarine cable 207 is converted into AC by the DC / AC converter 291 and stepped down to, for example, 66 kV by the transformer 292. The 66 kV AC power is transmitted to the power system 7.

[0067] In such a power transmission system 201, the voltage level changes during the power transmission process as shown in the lower part of the figure. In particular, in the power transmission stage of the high-voltage DC submarine cable 207, the voltage is extremely high above 500 kV. The reason for setting the voltage high is to suppress the loss during long-distance power transmission based on the cable. However, in order to achieve this high voltage, a multi-stage transformer structure, high-voltage withstand devices, components, cable structures, etc. are required.

[0068] Furthermore, as described above, in wind power generation equipment 202, the structure becomes complicated because the AC / DC converter 222 and the DC / AC converter 223 are used to temporarily convert the power into direct current before sending it to array cable 203, and then convert it into alternating current again to adjust the output.

[0069] <3. Voltage Transition of Power Transmission System According to Embodiment>

[0070] Based on the above, the voltage transition of the power transmission system 1 according to the present embodiment will be described.

[0071] Figure 4 The structure related to voltage conversion of the power transmission system 1 using the power carrier 10 and the transition of the voltage level are shown. Figure 4 In the voltage level transition in the lower part, the solid line represents the voltage transition of the power transmission system 1, and the dashed line represents the voltage transition of the power transmission system 1 for comparison. Figure 3 The voltage change of the power transmission system 201. In addition, the voltage values ​​listed in the following description are just examples for explanation.

[0072] In the power transmission system 1 of the embodiment, in the wind power generation equipment 2 , AC power below its rated voltage (eg, about 300 V to 6600 V) is obtained by the generator 21 and extracted as DC by the AC / DC converter 22 .

[0073] The DC / DC converter 23 converts the voltage into a DC voltage of about 10 kV and transmits it to the array cable 3 which is a DC cable. The DC / DC converter 23 is designed to increase the voltage level to a certain extent in order to reduce power transmission loss when power is transmitted by the array cable 3 which is a submarine cable.

[0074] In this way, in the wind power generation equipment 2, after being converted into direct current by the AC / DC converter 22, the power is sent out of the equipment by only performing voltage boosting matching the transmission of the array cable 3 while maintaining the direct current.

[0075] Furthermore, in the case of the power transmission system 1 , since the wind turbine generator 2 is not connected to the power system 7 , it is not necessary to perform output adjustment according to the situation on the power system 7 side.

[0076] In addition, the wind turbine generator 2 referred to in the present disclosure refers to the structure before the array cable 3 that transmits power from the generator 21 to the offshore converter station 4. The structure after the array cable 3 is the outside of the wind turbine generator 2.

[0077] Furthermore, although three wind turbine generators 2 are shown in the figure, the number of three is just an example for explanation. Although the AC / DC converter 22 and the DC / DC converter 23 of one wind turbine generator 2 are shown in the figure, the other wind turbine generators 2 have the same structure.

[0078] The DC power transmitted to the offshore converter station 4 through the array cable 3 is stepped down to about 1.5 kV by the DC / DC converter 41. Then, based on the stepped-down voltage, a charging current flows from a charging circuit (not shown) to the storage battery 42 for charging. The storage battery 42 is used to store the power generated by the wind turbine generator 2 during the period when the power carrier 10 has not reached the offshore converter station 4.

[0079] When the power carrier 10 reaches the offshore converter station 4 and the connector cable 8 is connected, the power is sent (discharged) from the storage battery 42. At this time, the DC voltage when the power is sent is converted by the DC / DC converter 43 to a voltage set according to the rated voltage of the connector cable 8 or the cable transmission efficiency, for example, about 10 kV. This is also a voltage increase to reduce the power transmission loss caused by the connector cable 8.

[0080] In the power carrier 10, the connector cable 8 is connected to the charging and discharging port 11, and the voltage of the power received from the connector cable 8 is stepped down to, for example, about 1.5 kV by the DC / DC converter 12. Then, based on the stepped-down voltage, a charging current flows to the storage battery 14 (battery unit 14a) through a charging circuit in the battery control device 13 to charge.

[0081] After charging, the power carrier 10 sails toward the onshore substation 209. When the power carrier 10 reaches the onshore substation 209, the connector cable 9 is connected, and power is sent (discharged) from the storage battery 14. At this time, the DC voltage when the power is sent is converted by the DC / DC converter 12 to a voltage set according to the rated voltage of the connector cable 9 or the cable transmission efficiency, for example, about 10 kV.

[0082] In the onshore substation 5, the DC power transmitted by the connector cable 9 is converted into AC power by the DC / AC converter 51 and then stepped up to, for example, 66 kV by the transformer 52. The 66 kV AC power is transmitted to the power system 7.

[0083] In such a power transmission system 1, the transmission power is transmitted at a low voltage level as shown in the lower part of the figure during the transmission process, and in particular, there is a large voltage difference as shown by the voltage difference VD when comparing the stages of the high-voltage DC submarine cable 207 and the storage battery 14. Therefore, in the case of the power transmission system 1, compared with the power transmission system 201, a multi-stage transformer structure, high-voltage withstand voltage devices, components, cable structures, etc. are not required.

[0084] In addition, considering the power transmission efficiency, it is desirable that the power carrier 10 can carry as much power as possible in one voyage. On the other hand, considering the handling of cables for the power charging and discharging system around the storage battery 14 or the battery control device 13 on the power carrier 10, it is desirable to use fewer and smaller cables. Considering these circumstances, it is preferable to set it to about 1.5 kV via the DC / DC converter 12.

[0085] <4. Effects and Modifications of Embodiment>

[0086] According to the power transmission system 1 of the above embodiment, the following effects can be obtained.

[0087] The power carrier 10 as a mobile body in the power transmission system 1 is equipped with a battery control device 13, which charges the storage battery 14 by supplying power at a voltage value that does not become the maximum voltage value of the DC power between the wind power generation equipment 2 and the onshore substation 209 as the power receiving equipment. That is, the charging voltage of the storage battery 14 carried by the power carrier 10 is a predetermined voltage lower than the maximum voltage value of the power between the wind power generation equipment 2 and the onshore substation 209. For example, Figure 4 In the case of the example, the voltage of the storage battery 14 during the charge and discharge phase is lower than the voltage when it is transmitted through the array cable 3 or the connector cable 8 and the connector cable 9.

[0088] That is, in the power transmission system 1, the system is designed so that the power transmission by the high-voltage DC submarine cable 207, such as the power transmission system 201 of the comparative example, is replaced by the power transmission by the power carrier 10, and the voltage during charging does not reach the maximum voltage value. Such a design is possible because there is no need for voltage boosting to suppress power transmission loss in the high-voltage DC submarine cable 207. As a result, there is no need for equipment to cope with high voltage around the storage battery 14 of the power carrier 10.

[0089] Therefore, in the power transmission system 1, it is possible to simplify the structure and reduce the cost.

[0090] The power carrier 10 is provided with a DC / DC converter 12 as a conversion unit, which receives power generated by the wind power generation equipment 2 and converted into a first DC voltage (e.g., a voltage of about 10 kV), and converts the power into a second DC voltage (e.g., a voltage of about 1.5 kV) having a voltage value lower than the first DC voltage. The battery control device 13 charges the storage battery 14 by supplying power at the second DC voltage.

[0091] That is, the power carrier 10 is configured to convert the DC voltage supplied from the offshore converter station 4 as a relay device into a voltage lower than that supplied to the battery 14. Thus, the battery 14 is charged at least at a voltage lower than that transmitted by the connector cable 8.

[0092] Since the storage of electricity in the storage battery 14 does not require high voltage, it is not necessary to significantly increase the voltage in the system as in the power transmission system 201 using the high-voltage DC submarine cable 207 of the comparative example. In other words, when transmitting electricity over long distances, it is not necessary to increase the voltage of the transmission medium. As a result, the need for equipment or cables that cope with high voltage can be eliminated, and the efficiency of the overall system structure and the reduction of costs can be promoted.

[0093] In the embodiment, an example is given in which the power transmission system 1 is constituted by the ship shown as the power carrier ship 10. This is applicable not only to land and coastal areas but also to the case of generating power at sea farther from land.

[0094] For example, it is possible to construct a power transmission system that achieves the efficiency of the above-mentioned structure while enjoying advantages such as not requiring a long-distance DC submarine cable or being able to eliminate problems such as noise caused by power generation.

[0095] Furthermore, as a movable body applicable to the power transmission system according to the present invention, it is not limited to ships, and vehicles, airplanes, etc. equipped with storage batteries are also conceivable.

[0096] In the embodiment, the power transmission system 1 of the present disclosure is applied to an example of offshore wind power generation equipment 2. As a result, it is applicable not only to land or coastal areas, but also to the case of generating electricity at sea with a long distance from the shore. As a result, a power transmission system can be constructed that realizes the efficiency of the above-mentioned structure and enjoys the effect of improved power generation efficiency brought about by stable wind at sea.

[0097] Furthermore, the power generation equipment involved in the invention disclosed herein is not limited to wind power generation equipment, and solar power generation equipment, tidal power generation equipment, geothermal power generation equipment, hydroelectric power generation equipment, biomass power generation equipment, and the like are also conceivable.

[0098] Furthermore, the power generation equipment involved in the invention disclosed in this disclosure is not limited to offshore equipment, but may also be land equipment. For example, it may also be a power transmission system between a land power generation equipment and a land power receiving equipment. Furthermore, the invention disclosed in this disclosure may also be applied to a power transmission system between an offshore power generation equipment and an offshore power receiving equipment.

[0099] The wind power generation equipment 2 as the power generation equipment in the power transmission system 1 of the embodiment is configured to include a generator 21 and an AC / DC converter (AC / DC converter 22) for converting AC power generated by the generator 21 into DC power, and to send the DC power to the outside of the equipment through the array cable 3. That is, if the generated power sent for the purpose of charging the storage battery 14 of the power carrier 10 is converted from AC to DC, it is not directly restored to AC, but sent to the outside of the power generation equipment as DC.

[0100] In the case of the power transmission system 1, the wind power generation equipment 2 is not always connected to the power system 7 via the power carrier 10, so there is no need to adjust the output on the side of the wind power generation equipment 2. This means that in the wind power generation equipment 2, it is not necessary to convert the generated power into DC for output adjustment and then return it to AC and output it outside the equipment.

[0101] In addition, in the case of the power transmission system 1, the array cable 3 transmits power in direct current. By assembling the power carrier 10 into the power transmission system 1 based on offshore wind power generation, it is possible to adopt the direct current extraction method from the offshore wind power generation equipment 2, and directly send out the power converted from AC to DC or send it out after necessary voltage conversion. Therefore, in the wind power generation equipment 2, the DC / AC converter 223 or the transformer 224 in the wind power generation equipment 202 of the comparative example is not required. In addition, by using the array cable 3 as a DC cable instead of the array cable 203 as an AC cable, the three-core cable is replaced by a two-core cable. As a result, the cost required for the array cable 3 can be greatly reduced.

[0102] This simplifies the structure of the power generation equipment, and for example, reduces the installation cost and driving cost of the wind power generation equipment 2 .

[0103] Furthermore, the array cable 3 is provided as a DC transmission line to the offshore converter station 4 as a relay device, and the offshore converter station 4 supplies power to the power transfer ship 10. Furthermore, the array cable 3 is configured as a DC cable, and transmits DC power to the offshore converter station 4 located at a relatively close position. By providing the offshore converter station 4 as a relay device, it is not necessary to provide a connection mechanism with the power transfer ship 10 in the wind turbine generator 2 itself. Therefore, it is possible to facilitate the simplification of the structure of a plurality of wind turbine generators 2.

[0104] Furthermore, when electric power is transmitted to the array cable 3 , it is converted to an appropriate voltage value by the direct current voltage converter (DC / DC converter 23 ), so that electric power can be transmitted to the offshore converter station 4 with little loss.

[0105] In addition, Figure 4 In the example of using the DC / DC converter 23 as the DC voltage converter, a transformer may be used instead of the DC / DC converter 23. In particular, when insulation is required in the power transmission stage of the wind power generation device 2, it is preferable to use a transformer to perform the necessary voltage conversion.

[0106] (Explanation of Reference Numerals)

[0107] 1: Transmission system; 2: Wind power generation equipment; 3: Array cables; 4: Offshore converter station;

[0108] 5: Onshore substation; 6: Cable; 7: Power system; 8, 9: Connector cable;

[0109] 10: Power transport ship; 11: Charging and discharging port; 12, 23, 41, 43: DC / DC converter;

[0110] 13: battery control device; 14: storage battery; 14a: battery unit; 21: generator;

[0111] 22: AC / DC converter; 42: battery; 51: DC / AC converter; 52: transformer.

Claims

1. A mobile body in a power transmission system, in which power generated by a power generation device is charged to a storage battery mounted on the mobile body, and power is supplied from the storage battery transferred by the mobile body to a power receiving device, wherein: The mobile object includes a battery control device configured to charge the storage battery by supplying electric power at a voltage value that does not become a maximum voltage value of direct current power from the power generating device to the power receiving device.

2. The mobile body according to claim 1, comprising a conversion unit that receives the power generated by the power generation device and converted into a first DC voltage, and converts the power into a second DC voltage having a voltage value lower than the first DC voltage, The battery control device charges the storage battery by supplying electric power at the second DC voltage.

3. The moving object according to claim 2, wherein: The first DC voltage is a voltage value converted for sending the electric power to the cable in the relay device when the relay device capable of storing the electric power from the power generation device is supplied with electric power through the cable.

4. The moving object according to any one of claims 1 to 3, wherein: The moving object is a ship.

5. The moving object according to any one of claims 1 to 3, wherein: The power generation equipment is a wind power generation equipment arranged at sea.

6. A power transmission method of a power transmission system, in which power generated by a power generation device is charged to a storage battery mounted on a moving body, and power is supplied from the storage battery transferred by the moving body to a power receiving device, wherein: The storage battery is charged by supplying electric power at a voltage value that does not become a maximum voltage value of the DC power from the power generating device to the power receiving device.

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