Phase control method and device for deep-sea offshore power transmission system

Abstract

The application discloses a phase control method and device of a deep-sea offshore power transmission system. The method comprises the following steps: obtaining a first phase of a voltage of a first AC bus and a second phase of a voltage of a second AC bus of the deep-sea offshore power transmission system, determining a phase difference between a first wind farm and a second wind farm according to the first phase and the second phase, determining a deviation phase between the phase difference and a preset target phase angle difference, and sending an instruction for adjusting the deviation phase to the second wind farm so that the second wind farm adjusts the phase thereof. As can be seen, the voltage data of the AC bus can be obtained without equipping the deep-sea offshore power transmission system with an additional AC / DC filter device, the phase value required to be adjusted is calculated according to the target phase angle difference, and the instruction is fed back to the wind farm, so that the wind farm adjusts the phase, the deep-sea offshore power transmission system is ensured to realize phase control on the basis of lightness, and the larger harmonics on the AC side and the DC side are reduced.

Description

Technical Field

[0001] This application relates to the field of deep-sea offshore power transmission, and more specifically, to a phase control method and device for a deep-sea offshore power transmission system. Background Technology

[0002] With the continuous increase in electricity consumption, near-shore offshore wind power is gradually being exhausted, and deep-sea offshore wind power is the focus of my country's future offshore wind power development. In deep-sea power transmission schemes, AC transmission schemes cannot meet the needs of large-scale deep-sea offshore wind power development, while traditional DC transmission schemes are costly and cannot meet the needs of large-scale economic development of offshore wind power. Therefore, it is necessary to explore new low-cost transmission schemes to provide new technologies for deep-sea offshore wind power development. Current deep-sea offshore power transmission systems use diode-based unidirectional current-type uncontrolled rectifier converters (diode converters), which help to achieve lightweight deep-sea offshore power transmission systems.

[0003] However, deep-sea offshore power transmission systems exhibit significant harmonics on both the AC and DC sides, necessitating the addition of AC and DC filtering devices. These additional filters increase the system's weight, diminishing the advantages of lightweight diode converters and preventing the simultaneous reduction of high harmonics on both the AC and DC sides in a lightweight deep-sea offshore power transmission system. This hinders the realization of practical deep-sea offshore power transmission projects.

[0004] Therefore, how to achieve phase control while ensuring the lightweight nature of the deep-sea offshore power transmission system in order to reduce the large harmonics on the AC and DC sides is an issue that needs attention. Summary of the Invention

[0005] In view of the above problems, this application is made to provide a phase control method and device for a deep-sea offshore power transmission system, so as to achieve phase control while ensuring the lightweight nature of the deep-sea offshore power transmission system, thereby reducing large harmonics on the AC and DC sides.

[0006] To achieve the above objectives, the following specific solutions are proposed:

[0007] A phase control method for a deep-sea offshore power transmission system includes:

[0008] The system obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series.

[0009] Based on the first phase and the second phase, determine the phase difference between the first wind farm and the second wind farm;

[0010] Determine the phase deviation between the phase difference and the preset target phase angle difference;

[0011] Send a command to the second wind farm to adjust the biased phase, so that the second wind farm can adjust its phase.

[0012] Optionally, the method further includes:

[0013] Send a command to the first wind farm to adjust the biased phase, so that the first wind farm can adjust its phase.

[0014] Optionally, obtaining the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system includes:

[0015] Monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system;

[0016] The first phase of the voltage of the first AC bus is calculated using a phase-locked loop;

[0017] The second phase of the voltage of the second AC bus is calculated using a phase-locked loop.

[0018] Optionally, determining the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase includes:

[0019] Subtract the second phase from the first phase to obtain the first difference, and take the absolute value of the first difference as the phase difference between the first wind farm and the second wind farm;

[0020] or,

[0021] Subtracting the first phase from the second phase yields a second difference, and the absolute value of the second difference is taken as the phase difference between the first wind farm and the second wind farm.

[0022] Optionally, the method further includes:

[0023] When the target phase difference is updated to the updated phase difference, the update deviation phase between the phase difference and the updated phase difference is determined;

[0024] Send a command to the second wind farm to adjust the updated deviation phase, so that the second wind farm can adjust its phase.

[0025] Optionally, the grid-side module includes a first modular multilevel converter valve (MMC), a second MMC converter valve, a third transformer, a fourth transformer, and an AC grid equivalent power source. The first diode converter valve, the first MMC converter valve, the first MMC converter valve, and the second MMC converter valve are connected in series via a DC line. The third transformer is connected to the first MMC converter valve, and the fourth transformer is connected to the second MMC converter valve. Both the third transformer and the fourth transformer are connected to the AC grid equivalent power source.

[0026] A phase control device for a deep-sea offshore power transmission system includes:

[0027] A phase acquisition unit is used to acquire the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series.

[0028] A phase difference determination unit is used to determine the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase.

[0029] A deviation phase determination unit is used to determine the deviation phase between the phase difference and a preset target phase angle difference;

[0030] The first adjustment command sending unit is used to send an instruction to the second wind farm to adjust the deviation phase, so that the second wind farm can adjust its phase.

[0031] Optionally, the device may also include:

[0032] The second adjustment command sending unit is used to send a command to the first wind farm to adjust the deviation phase, so that the first wind farm can adjust its phase.

[0033] Optionally, the phase acquisition unit includes:

[0034] The bus voltage monitoring unit is used to monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system.

[0035] The first phase calculation unit is used to calculate the first phase of the voltage of the first AC bus through a phase-locked loop.

[0036] The second phase calculation unit is used to calculate the second phase of the voltage of the second AC bus through a phase-locked loop.

[0037] Optionally, the phase difference determination unit includes:

[0038] The first phase difference determination subunit is used to subtract the second phase from the first phase to obtain a first difference value, and to use the absolute value of the first difference value as the phase difference between the first wind farm and the second wind farm.

[0039] or,

[0040] The second phase difference determination subunit is used to subtract the first phase from the second phase to obtain a second difference value, and to use the absolute value of the second difference value as the phase difference between the first wind farm and the second wind farm.

[0041] Optionally, the device may also include:

[0042] The update deviation phase determination unit is used to determine the update deviation phase between the phase difference and the update phase difference when the target phase difference is updated to an update phase difference;

[0043] The update adjustment instruction sending unit is used to send an instruction to the second wind farm to adjust the update deviation phase, so that the second wind farm can adjust its phase.

[0044] By employing the above technical solution, this application obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the same system. Based on the first and second phases, it determines the phase difference between the first and second wind farms, determines the deviation phase between the phase difference and a preset target phase angle difference, and sends an instruction to the second wind farm to adjust the deviation phase, allowing the second wind farm to adjust its phase. Therefore, it is evident that without equipping the deep-sea offshore power transmission system with additional AC / DC filtering devices, it is possible to obtain the AC bus voltage data, calculate the required phase adjustment value based on the target phase angle difference, and feed this instruction back to the wind farm, enabling the wind farm to adjust its phase. This ensures that the deep-sea offshore power transmission system achieves phase control while remaining lightweight, thereby reducing significant harmonics on the AC / DC sides. Attached Figure Description

[0045] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0046] Figure 1 A schematic diagram of the phase control process for a deep-sea offshore power transmission system provided in this application embodiment;

[0047] Figure 2 A schematic diagram of a deep-sea offshore power transmission system provided in this application embodiment;

[0048] Figure 3 A schematic diagram of another deep-sea offshore power transmission system provided in this application embodiment;

[0049] Figure 4 A schematic diagram of a device for phase control of a deep-sea offshore power transmission system provided in an embodiment of this application;

[0050] Figure 5 This is a schematic diagram of the structure of a device for phase control of a deep-sea offshore power transmission system, provided as an embodiment of this application. Detailed Implementation

[0051] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0052] The proposed solution can be implemented based on a terminal with data processing capabilities, such as a computer, server, or cloud platform.

[0053] Next, combined Figure 1 The phase control method for the deep-sea offshore power transmission system of this application may include the following steps:

[0054] Step S110: Obtain the first phase of the voltage of the first AC bus of the deep-sea power transmission system and the second phase of the voltage of the second AC bus of the deep-sea power transmission system.

[0055] Specifically, such as Figure 3 As shown, the deep-sea offshore power transmission system may include a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module.

[0056] The first diode converter valve is connected to the first wind farm via the first transformer and the first AC bus, and the second diode converter valve is connected to the second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve and the grid-side module are connected in series.

[0057] Both the first AC bus and the second AC bus can be equipped with lightweight voltage measuring devices. The mass of the lightweight voltage measuring devices has a negligible impact on the mass of the deep-sea power transmission system. The lightweight voltage measuring devices can have communication functions, enabling them to acquire voltage data of the first AC bus and the second AC bus in real time.

[0058] Step S120: Determine the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase.

[0059] Specifically, the phase of the first AC bus connected to the first wind farm can represent the phase of the first wind farm, and the phase of the second AC bus connected to the second wind farm can represent the phase of the second wind farm. The difference between the phases of the two wind farms is the phase difference.

[0060] Step S130: Determine the deviation phase between the phase difference and the preset target phase angle difference.

[0061] It is understood that the deviation phase is the compensation value for the phase difference between the first wind farm and the second wind farm.

[0062] Specifically, considering that the target phase difference is used to reduce harmonics, the preset target phase difference can be set to 30°, that is, the phase difference is determined to be 30° away from the phase.

[0063] Step S140: Send an instruction to the second wind farm to adjust the deviation phase, so that the second wind farm can adjust its phase.

[0064] It is understandable that after the deviation phase is calculated, the deep-sea offshore power transmission system needs to perform the action of compensating for the deviation phase. Therefore, the instruction to adjust the deviation phase can be sent to the second wind farm through communication. The second wind farm is equipped with a device for adjusting the phase angle. Then, the device can respond to the instruction to adjust the deviation phase and change the phase of the second wind farm so that the phase difference between the first wind farm and the second wind farm is maintained at the target phase angle difference.

[0065] The phase control method for a deep-sea offshore power transmission system provided in this embodiment obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the same system. Based on the first and second phases, it determines the phase difference between the first and second wind farms, determines the deviation phase between the phase difference and a preset target phase angle difference, and sends an instruction to the second wind farm to adjust the deviation phase, allowing the second wind farm to adjust its phase. Therefore, it is possible to obtain the AC bus voltage data and calculate the required phase adjustment value based on the target phase angle difference without equipping the deep-sea offshore power transmission system with additional AC / DC filtering devices. This instruction is then fed back to the wind farm, enabling the wind farm to adjust its phase, ensuring that the deep-sea offshore power transmission system achieves phase control while remaining lightweight, thereby reducing significant harmonics on the AC / DC sides.

[0066] Considering that the purpose of the preset target phase angle difference is to keep the phase difference between the first wind farm and the second wind farm constant at this value, the phase of the first wind farm can also be adjusted. Based on this, the phase control method for deep-sea offshore power transmission provided in this application may further include:

[0067] A command to adjust the biased phase is sent to the first wind farm so that the first wind farm can adjust its phase.

[0068] Specifically, the first wind farm is equipped with a device for adjusting the phase angle. This device can respond to the command to adjust the phase deviation and change the phase of the first wind farm so that the phase difference between the first wind farm and the second wind farm is maintained at the target phase angle difference.

[0069] In some embodiments of this application, the process of obtaining the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system in step S110 is described. This process may include:

[0070] S1. Monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system.

[0071] Specifically, the voltage of the first AC bus can be determined by monitoring the voltage measured by the light-duty voltage measuring device equipped on the first AC bus, and the voltage of the second AC bus can be determined by monitoring the voltage measured by the light-duty voltage measuring device equipped on the second AC bus.

[0072] S2. Calculate the first phase of the voltage of the first AC bus using a phase-locked loop.

[0073] S3. Calculate the second phase of the voltage of the second AC bus using a phase-locked loop.

[0074] In some embodiments of this application, the process of determining the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase in step S120 is described. This process may include any one of the following two cases:

[0075] The first method involves subtracting the second phase from the first phase to obtain a first difference, and using the absolute value of the first difference as the phase difference between the first wind farm and the second wind farm.

[0076] The second method involves subtracting the first phase from the second phase to obtain a second difference, and using the absolute value of the second difference as the phase difference between the first wind farm and the second wind farm.

[0077] Considering that the deep-sea offshore power transmission system has other power demands, when it is necessary to change the phase difference between the first wind farm and the second wind farm, other target phase angle differences can be set. Based on this, the phase control method for deep-sea offshore power transmission provided in this application may also include:

[0078] S1. When the target phase angle difference is updated to the updated phase angle difference, determine the update deviation phase between the phase difference and the updated phase angle difference.

[0079] It is understandable that the target phase difference represents the value of keeping the phase difference between the first wind farm and the second wind farm constant in order to reduce harmonics on the AC and DC sides. When there are other power demands in the deep-sea offshore power transmission system, the target phase difference can be updated to the updated phase difference. Then the updated phase difference can represent the value of the phase difference between the first wind farm and the second wind farm that the deep-sea offshore power transmission system changes based on this power demand.

[0080] S2. Send an instruction to the second wind farm to adjust the updated deviation phase, so that the second wind farm can adjust its phase.

[0081] Specifically, the second wind farm can respond to the instruction to adjust the update deviation phase by changing the phase of the second wind farm, so that the phase difference between the first wind farm and the second wind farm remains at the update deviation phase.

[0082] In some embodiments of this application, the grid-side module of the deep-sea offshore power transmission system mentioned in the above embodiments is described, such as... Figure 3 As shown, the grid-side module may include a first modular multilevel converter (MMC) valve, a second MMC valve, a third transformer, a fourth transformer, and an AC grid equivalent power source.

[0083] The first diode converter valve, the first MMC converter valve, and the second MMC converter valve can be connected in series via a DC line. The third transformer can be connected to the first MMC converter valve, and the fourth transformer can be connected to the second MMC converter valve. Both the third transformer and the fourth transformer can be connected to the equivalent power source of the AC power grid.

[0084] The following describes the device for phase control of deep-sea power transmission provided in the embodiments of this application. The device for phase control of deep-sea power transmission described below and the phase control method for deep-sea power transmission described above can be referred to in correspondence.

[0085] See Figure 4 , Figure 4 This is a schematic diagram of a device for phase control in realizing deep-sea power transmission, as disclosed in an embodiment of this application.

[0086] like Figure 4 As shown, the device may include:

[0087] Phase acquisition unit 11 is used to acquire the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series.

[0088] The phase difference determination unit 12 is used to determine the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase.

[0089] The deviation phase determination unit 13 is used to determine the deviation phase between the phase difference and the preset target phase angle difference;

[0090] The first adjustment command sending unit 14 is used to send a command to the second wind farm to adjust the deviation phase, so that the second wind farm can adjust its phase.

[0091] Optionally, the device may also include:

[0092] The second adjustment command sending unit is used to send a command to the first wind farm to adjust the deviation phase, so that the first wind farm can adjust its phase.

[0093] Optionally, the phase acquisition unit includes:

[0094] The bus voltage monitoring unit is used to monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system.

[0095] The first phase calculation unit is used to calculate the first phase of the voltage of the first AC bus through a phase-locked loop.

[0096] The second phase calculation unit is used to calculate the second phase of the voltage of the second AC bus through a phase-locked loop.

[0097] Optionally, the phase difference determination unit includes:

[0098] The first phase difference determination subunit is used to subtract the second phase from the first phase to obtain a first difference value, and to use the absolute value of the first difference value as the phase difference between the first wind farm and the second wind farm.

[0099] or,

[0100] The second phase difference determination subunit is used to subtract the first phase from the second phase to obtain a second difference value, and to use the absolute value of the second difference value as the phase difference between the first wind farm and the second wind farm.

[0101] Optionally, the device may also include:

[0102] The update deviation phase determination unit is used to determine the update deviation phase between the phase difference and the update phase difference when the target phase difference is updated to an update phase difference;

[0103] The update adjustment instruction sending unit is used to send an instruction to the second wind farm to adjust the update deviation phase, so that the second wind farm can adjust its phase.

[0104] The phase control device for deep-sea power transmission provided in this application embodiment can be applied to phase control equipment for deep-sea power transmission, such as terminals like mobile phones and computers. Optionally, Figure 5 The hardware structure block diagram of the phase control equipment for deep-sea power transmission is shown, with reference to... Figure 5 The hardware structure of the phase control device for deep-sea power transmission may include: at least one processor 1, at least one communication interface 2, at least one memory 3 and at least one communication bus 4.

[0105] In this embodiment of the application, the number of processor 1, communication interface 2, memory 3, and communication bus 4 is at least one, and processor 1, communication interface 2, and memory 3 communicate with each other through communication bus 4;

[0106] Processor 1 may be a central processing unit (CPU), an application-specific integrated circuit (ASIC), or one or more integrated circuits configured to implement embodiments of the present invention.

[0107] Memory 3 may include high-speed RAM, and may also include non-volatile memory, such as at least one disk storage device;

[0108] The memory stores a program, which the processor can call. The program is used for:

[0109] The system obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series.

[0110] Based on the first phase and the second phase, determine the phase difference between the first wind farm and the second wind farm;

[0111] Determine the phase deviation between the phase difference and the preset target phase angle difference;

[0112] Send a command to the second wind farm to adjust the biased phase, so that the second wind farm can adjust its phase.

[0113] Optionally, the refined and extended functions of the program can be found in the description above.

[0114] This application embodiment also provides a storage medium that can store a program suitable for execution by a processor, the program being used for:

[0115] The system obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series.

[0116] Based on the first phase and the second phase, determine the phase difference between the first wind farm and the second wind farm;

[0117] Determine the phase deviation between the phase difference and the preset target phase angle difference;

[0118] Send a command to the second wind farm to adjust the biased phase, so that the second wind farm can adjust its phase.

[0119] Optionally, the refined and extended functions of the program can be found in the description above.

[0120] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0121] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0122] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A phase control method for a deep-sea offshore power transmission system, characterized in that, include: The system obtains the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series. Based on the first phase and the second phase, determine the phase difference between the first wind farm and the second wind farm; Determine the phase deviation between the phase difference and the preset target phase angle difference; Send a command to the second wind farm to adjust the biased phase, so that the second wind farm can adjust its phase.

2. The phase control method according to claim 1, characterized in that, Also includes: Send a command to the first wind farm to adjust the biased phase, so that the first wind farm can adjust its phase.

3. The method according to claim 1, characterized in that, The acquisition of the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system includes: Monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system; The first phase of the voltage of the first AC bus is calculated using a phase-locked loop; The second phase of the voltage of the second AC bus is calculated using a phase-locked loop.

4. The method according to claim 1, characterized in that, Determining the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase includes: Subtract the second phase from the first phase to obtain the first difference, and take the absolute value of the first difference as the phase difference between the first wind farm and the second wind farm; or, Subtracting the first phase from the second phase yields a second difference, and the absolute value of the second difference is taken as the phase difference between the first wind farm and the second wind farm.

5. The method according to claim 1, characterized in that, Also includes: When the target phase difference is updated to the updated phase difference, the update deviation phase between the phase difference and the updated phase difference is determined; Send a command to the second wind farm to adjust the updated deviation phase, so that the second wind farm can adjust its phase.

6. The method according to any one of claims 1-5, characterized in that, The grid-side module includes a first modular multilevel converter valve (MMC), a second MMC converter valve, a third transformer, a fourth transformer, and an AC grid equivalent power source. The first diode converter valve, the first MMC converter valve, and the second MMC converter valve are connected in series via a DC line. The third transformer is connected to the first MMC converter valve, and the fourth transformer is connected to the second MMC converter valve. Both the third transformer and the fourth transformer are connected to the AC grid equivalent power source.

7. A phase control device for a deep-sea offshore power transmission system, characterized in that, include: A phase acquisition unit is used to acquire the first phase of the voltage of the first AC bus of the deep-sea offshore power transmission system and the second phase of the voltage of the second AC bus of the deep-sea offshore power transmission system. The deep-sea offshore power transmission system includes a first diode converter valve, a second diode converter valve, a first transformer, a second transformer, and a grid-side module. The first diode converter valve is connected to a first wind farm via the first transformer and the first AC bus. The second diode converter valve is connected to a second wind farm via the second transformer and the second AC bus. The first diode converter valve, the second diode converter valve, and the grid-side module are connected in series. A phase difference determination unit is used to determine the phase difference between the first wind farm and the second wind farm based on the first phase and the second phase. A deviation phase determination unit is used to determine the deviation phase between the phase difference and a preset target phase angle difference; The first adjustment command sending unit is used to send an instruction to the second wind farm to adjust the deviation phase, so that the second wind farm can adjust its phase.

8. The apparatus according to claim 7, characterized in that, Also includes: The second adjustment command sending unit is used to send a command to the first wind farm to adjust the deviation phase, so that the first wind farm can adjust its phase.

9. The apparatus according to claim 7, characterized in that, The phase acquisition unit includes: The bus voltage monitoring unit is used to monitor the voltage of the first AC bus of the deep-sea offshore power transmission system and the voltage of the second AC bus of the deep-sea offshore power transmission system. The first phase calculation unit is used to calculate the first phase of the voltage of the first AC bus through a phase-locked loop. The second phase calculation unit is used to calculate the second phase of the voltage of the second AC bus through a phase-locked loop.

10. The apparatus according to claim 7, characterized in that, The phase difference determination unit includes: The first phase difference determination subunit is used to subtract the second phase from the first phase to obtain a first difference value, and to use the absolute value of the first difference value as the phase difference between the first wind farm and the second wind farm. or, The second phase difference determination subunit is used to subtract the first phase from the second phase to obtain a second difference value, and to use the absolute value of the second difference value as the phase difference between the first wind farm and the second wind farm.

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