Offshore wind power ac transmission system reactive power compensation capacity configuration method and system

Abstract

The application provides a method and system for configuring reactive power compensation capacity of an offshore wind power AC transmission system. The method comprises: obtaining system reactive power demand based on equipment parameters of the offshore wind power AC transmission system; obtaining an initial range of reactive power compensation capacity configuration based on voltage limitation at a grid connection point of the offshore wind farm and overvoltage limitation along the offshore cable; obtaining a range of reactive power compensation capacity configuration based on current limitation along the offshore cable of the offshore wind power AC transmission; and determining a reactive power compensation capacity configuration scheme based on the range of reactive power compensation capacity configuration and the system reactive power demand. The application is based on the reactive power configuration and voltage criteria that should be followed when the offshore wind farm is connected to the onshore power grid, considers the voltage and current along the offshore cable satisfying the voltage and current limitation conditions, and takes into account the system economy, so that the configuration of the high resistance capacity of the system is more economical and reliable.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power system analysis, and relates to a reactive power compensation capacity configuration method and system for an offshore wind power alternating current transmission system. BACKGROUND

[0002] With the proposal of the "double carbon" strategy, the proportion of new energy dominated by wind power is increasing, offshore wind power resources are rich and have great potential, and are close to the load center in the east, which is convenient for local consumption. Developing offshore wind power has become an important strategic support for the transformation of China's energy structure.

[0003] Offshore wind power technology is relatively complex. With the increase of offshore distance, the reactive power generated by the submarine cable is large, and the system needs to be compensated. The traditional compensation method of onshore wind power cannot be applied to offshore wind power. Offshore wind power reactive power compensation adopts the principle of hierarchical zoning, and the voltage and current along the submarine cable after compensation meet the limit conditions. At the same time, the economy of the compensation scheme also needs to be considered. There are many factors to consider in the offshore wind power reactive power compensation scheme. Reasonable selection of an economic and reliable reactive power compensation scheme can effectively improve the economy of the system and provide strong support for the flat-rate grid connection of offshore wind power. SUMMARY

[0004] The application provides a reactive power compensation capacity configuration method and system for an offshore wind power alternating current transmission system, which is used to solve the technical problem of how to provide a more economic and reliable reactive power compensation capacity configuration scheme.

[0005] In a first aspect, the application provides a reactive power compensation capacity configuration method for an offshore wind power alternating current transmission system, which includes: obtaining system reactive power demand based on device parameters of the offshore wind power alternating current transmission system; obtaining an initial range of reactive power compensation capacity configuration based on voltage limits of a grid connection point of an offshore wind farm and overvoltage limits along a submarine cable; obtaining a range of reactive power compensation capacity configuration based on current limits along the submarine cable of the offshore wind power alternating current transmission; and determining a reactive power compensation capacity configuration scheme based on the range of reactive power compensation capacity configuration and the system reactive power demand.

[0006] In an implementation form of the first aspect, the device parameters include offshore medium-voltage power collection line parameters, box-type transformer parameters, main transformer parameters, high-voltage submarine cable parameters, and high-voltage land cable parameters.

[0007] In an implementation form of the first aspect, obtaining system reactive power demand based on device parameters of the offshore wind power alternating current transmission system includes: performing cumulative calculation based on the reactive power generated by the offshore medium-voltage power collection line, the box-type transformer, the main transformer, the high-voltage submarine cable, and the high-voltage land cable to obtain the system reactive power demand.

[0008] In an implementation form of the first aspect, obtaining the initial range of the reactive power compensation capacity configuration based on the offshore wind farm grid connection point voltage limit and the overvoltage limit along the sea cable comprises: preliminarily determining a reactive power compensation capacity configuration scheme based on the grid connection point voltage limit; and performing overvoltage limit analysis on the reactive power compensation capacity configuration scheme to obtain the initial range of the reactive power compensation capacity configuration.

[0009] In an implementation form of the first aspect, performing overvoltage limit analysis on the reactive power compensation capacity configuration scheme to obtain the initial range of the reactive power compensation capacity configuration comprises: obtaining power frequency overvoltage and operating overvoltage of the offshore wind farm sending-out system under full load and no load; and performing overvoltage limit analysis based on the power frequency overvoltage and the operating overvoltage to obtain the initial range of the reactive power compensation capacity configuration.

[0010] In an implementation form of the first aspect, the current limit along the offshore wind power AC sending-out sea cable comprises: allowable current carrying capacity of the offshore wind power AC sending-out system sea cable in air, J-type pipe, seabed depth, and landing beach.

[0011] In an implementation form of the first aspect, obtaining the range of the reactive power compensation capacity configuration based on the current limit along the offshore wind power AC sending-out sea cable comprises: obtaining current values of the offshore wind power AC sending-out system sea cable in air, J-type pipe, seabed depth, and landing beach under full load; and obtaining the range of the reactive power compensation capacity configuration based on the current values and the allowable current carrying capacity.

[0012] In an implementation form of the first aspect, the offshore wind power AC sending-out system reactive power compensation capacity configuration method further comprises economic evaluation of the reactive power compensation capacity configuration scheme.

[0013] In a second aspect, the present application provides an offshore wind power AC sending-out system reactive power compensation capacity configuration system, comprising: an obtaining module configured to obtain system reactive power demand based on device parameters of an offshore wind power AC sending-out system; a voltage constraint module configured to obtain an initial range of reactive power compensation capacity configuration based on offshore wind farm grid connection point voltage limit and overvoltage limit along a sea cable; a current constraint module configured to obtain a range of reactive power compensation capacity configuration based on current limit along the offshore wind power AC sending-out sea cable; and a reactive power capacity configuration module configured to determine a reactive power compensation capacity configuration scheme based on the range of the reactive power compensation capacity configuration and the system reactive power demand.

[0014] In an implementation form of the second aspect, the offshore wind power AC sending-out system reactive power compensation capacity configuration system further comprises an investment comparison and selection module; and the investment comparison and selection module is configured to perform economic evaluation of the reactive power compensation capacity configuration scheme.

[0015] The offshore wind power AC transmission system reactive power compensation capacity configuration method, system, device and medium provided by the present application have the following beneficial effects:

[0016] Firstly, the present application considers the voltage and current constraints along the submarine cable and the grid connection point voltage constraint, and performs economic verification on the reactive power compensation scheme, so that the reliability and economy are considered in the selection of the reactive power compensation scheme.

[0017] Secondly, the present application uses the submarine cable grid connection point constraint, submarine cable overvoltage constraint and submarine cable current constraint to gradually narrow the high resistance and dynamic reactive power compensation capacity configuration range, and improves the accuracy of system reactive power compensation.

[0018] Thirdly, compared with the prior art, the present application can obtain the offshore wind power 220kV AC transmission reactive power compensation capacity configuration more quickly and accurately, improve the energy utilization rate, and reduce the equipment cost. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flowchart of a method for configuring the reactive power compensation capacity of an offshore wind power AC transmission system according to an embodiment of the present application is shown.

[0020] Figure 2 A flowchart of a method for configuring the reactive power compensation capacity of an offshore wind power AC transmission system according to an embodiment of the present application is shown.

[0021] Figure 3 A flowchart of a method for configuring the reactive power compensation capacity of an offshore wind power AC transmission system according to an embodiment of the present application is shown.

[0022] Figure 4 A flowchart of a method for configuring the reactive power compensation capacity of an offshore wind power AC transmission system according to an embodiment of the present application is shown.

[0023] Figure 5 A schematic diagram of the architecture of a system for configuring the reactive power compensation capacity of an offshore wind power AC transmission system according to an embodiment of the present application is shown.

[0024] Figure 6 A schematic diagram of the architecture of an electronic device according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0025] Following, the embodiments of the present application are illustrated by specific examples, and other advantages and effects of the present application can be easily understood by those skilled in the art from the disclosure of the present specification. The present application can also be implemented or applied by other different specific embodiments, and various modifications or changes can be made to the details in the specification without departing from the spirit of the present application. It should be noted that the following examples and features in the examples can be combined with each other without conflict.

[0026] It should be noted that the diagrams provided in the following examples only illustrate the basic concepts of the present application in a schematic manner, and only the components related to the present application are shown in the diagrams, not the number, shape and size of the components when actually implemented. The actual implementation of each component may be a random change in type, number and proportion, and the component layout pattern may also be more complex.

[0027] The present application provides a method and system for configuring reactive power compensation capacity of an offshore wind power AC transmission system. The method and system comply with the reactive power configuration and voltage criteria for connecting offshore wind farms to onshore power grids, take into account the voltage and current along the cable to meet the voltage and current limit conditions, and consider the system economy to make the configuration of high resistance capacity more economical and reliable.

[0028] Referring to FIG. 1, Figure 1 The method for configuring reactive power compensation capacity of an offshore wind power AC transmission system provided by an embodiment of the present application includes the following steps S1 to S4:

[0029] S1: Obtain the system reactive power demand based on the equipment parameters of the offshore wind power AC transmission system.

[0030] Specifically, the equipment parameters include offshore medium-voltage power collection line parameters, box-type transformer parameters, main transformer parameters, high-voltage submarine cable parameters, and high-voltage land cable parameters.

[0031] Specifically, the implementation of obtaining the system reactive power demand based on the equipment parameters of the offshore wind power AC transmission system includes: adding up the reactive power generated by the offshore medium-voltage power collection line, the box-type transformer, the main transformer, the high-voltage submarine cable, and the high-voltage land cable to obtain the system reactive power demand. That is:

[0032]

[0033] Q 总 is the system reactive power demand, and Q i represents the reactive power generated by the medium-voltage power collection line, the box-type transformer, the main transformer, the high-voltage submarine cable, and the high-voltage land cable.

[0034] Specifically, the main transformer is a step-up main transformer.

[0035] S2: obtaining an initial range of reactive power compensation capacity configuration based on the voltage limit of the offshore wind farm grid connection point and the overvoltage limit along the cable.

[0036] Specifically, as shown in Figure 2 , step S2 includes steps S21-S22.

[0037] S21: preliminarily determining the reactive power compensation capacity configuration scheme through the voltage limit of the grid connection point.

[0038] Specifically, the voltage limit of the offshore wind farm grid connection point includes that the voltage of the offshore wind farm grid connection point is within the range of 97% to 107% of the nominal value voltage.

[0039] Specifically, the calculation formula of the grid connection point voltage can be expressed as:

[0040]

[0041] wherein E is the grid connection point voltage, U is the high-voltage side voltage of the wind farm booster transformer, P Pcc and Q Pcc are the active power and reactive power output by the wind turbine, respectively, and θ is the phase angle of the AC cable impedance.

[0042] S22: performing overvoltage limit analysis on the reactive power compensation capacity configuration scheme to obtain the initial range of reactive power compensation capacity configuration.

[0043] Specifically, it is judged whether the overvoltage along the cable in the reactive power compensation capacity configuration scheme determined in step S21 meets the access limit requirement, and then the initial range of reactive power compensation capacity configuration is obtained.

[0044] Specifically, as shown in Figure 3 , step S22 includes steps S221-S222.

[0045] S221: obtaining the power frequency overvoltage and operating overvoltage of the offshore wind farm sending-out system under full load and no load.

[0046] The overvoltage limit of the offshore wind farm AC sending-out includes that the operating overvoltage along the cable does not exceed 3.0 p.u. of the standard voltage, and the power frequency overvoltage along the cable does not exceed 1.3 p.u. of the standard voltage.

[0047] Specifically, the standard voltage takes the maximum value of the three-phase voltage amplitudes at both ends of the cable, and the amplitude of the highest operating voltage of 220kV is converted into a p.u. value.

[0048] Specifically, the power frequency overvoltage and operating overvoltage can be obtained through simulation tests by establishing an electromagnetic transient simulation model of the offshore wind farm AC sending-out.

[0049] S222: Perform overvoltage limiting analysis based on the power frequency overvoltage and the operational overvoltage to obtain the initial range of the reactive power compensation capacity configuration.

[0050] Specifically, if both the power frequency overvoltage and the switching overvoltage meet the overvoltage limits, the current reactive power compensation configuration scheme will be determined as the preliminary scheme. If they do not meet the overvoltage limits, the current reactive power compensation configuration scheme will be excluded.

[0051] It should be noted that steps S21 to S22 are executed sequentially to obtain the initial range of reactive power compensation capacity configuration.

[0052] S3: Obtain the reactive power compensation capacity configuration range based on the current limitation along the offshore wind power AC transmission cable.

[0053] Specifically, the current limit along the offshore wind power AC transmission cable includes the allowable current carrying capacity of the offshore wind power AC transmission system cable in various sections: air, J-tube, seabed burial depth, and landing mudflats.

[0054] Specifically, such as Figure 4 As shown, step S3 includes steps S31 to S32.

[0055] S31: Obtain the current values ​​of the submarine cable of the offshore wind farm AC transmission system under full load in air, J-tube, seabed burial depth, and landing mudflat.

[0056] Specifically, the seabed burial depth is divided into sections at a depth of 2 meters.

[0057] Specifically, the landing mudflats are divided into sections at a depth of 1.5 meters.

[0058] Specifically, by establishing a transient simulation model of the electromechanical system for offshore wind power AC transmission, the current values ​​of each segment of the submarine cable of the offshore wind farm AC transmission system are calculated using power flow.

[0059] S32: Obtain the reactive power compensation capacity configuration range based on the current value of each segment and the allowable current carrying capacity of each segment.

[0060] Specifically, if the current value of each segment is lower than the allowable current carrying capacity of each segment, then the current reactive power compensation configuration scheme is determined as the configuration scheme. If the current value of each segment is not lower than the allowable current carrying capacity of each segment, then the current reactive power compensation configuration scheme is excluded.

[0061] It should be noted that steps S31 to S32 are executed sequentially to obtain the reactive power compensation capacity configuration range.

[0062] S4: Determine the reactive power compensation capacity configuration scheme based on the reactive power compensation capacity configuration range and the system reactive power demand.

[0063] Specifically, within the range of accurate reactive power compensation capacity configuration, the reactive power compensation capacity configuration scheme is determined based on the system reactive power demand.

[0064] It should be noted that the offshore wind power AC transmission system reactive power compensation is based on the principle of zero reactive power exchange between the wind farm and the power grid. Therefore, step S4 also needs to combine the system reactive power compensation principle to dynamically configure the reactive power compensation capacity.

[0065] It should be noted that the offshore wind power AC transmission system reactive power compensation device includes a high-voltage shunt reactor, a low-voltage shunt reactor, a dynamic reactive power compensation device, and a load-voltage-regulating reactive power compensation device.

[0066] In an embodiment, the application adopts the most commonly used high-voltage shunt reactor and dynamic reactive power compensation device in engineering.

[0067] In addition, the offshore wind power AC transmission system reactive power compensation capacity configuration method provided by the application also performs economic verification on the reactive power compensation capacity configuration scheme. That is, the economy of the offshore wind power AC transmission reactive power compensation system is considered to verify the reactive power compensation capacity configuration scheme with the minimum investment as a constraint.

[0068] Specifically, the total system cost is calculated according to the unit cost of dynamic reactive power compensation and high resistance, and the most economical reactive power compensation scheme is determined according to the minimum total system cost.

[0069] The protection scope of the offshore wind power AC transmission system reactive power compensation capacity configuration method described in the embodiments of the application is not limited to the execution order of the steps listed in the embodiments. Any scheme realized by increasing, reducing, or replacing the steps of the prior art according to the principles of the application is included in the protection scope of the application.

[0070] The embodiments of the application also provide an offshore wind power AC transmission system reactive power compensation capacity configuration system, which can implement the offshore wind power AC transmission system reactive power compensation capacity configuration method described in the application. However, the implementation device of the offshore wind power AC transmission system reactive power compensation capacity configuration method described in the application includes but is not limited to the structure of the offshore wind power AC transmission system reactive power compensation capacity configuration system listed in the embodiments. Any structure deformation and replacement of the prior art according to the principles of the application is included in the protection scope of the application.

[0071] As shown in Figure 5 The offshore wind power AC transmission system reactive power compensation capacity configuration system provided by the embodiments includes an acquisition module 10, a voltage constraint module 20, a current constraint module 30, and a reactive power capacity configuration module 40.

[0072] The acquisition module 10 is configured to acquire the reactive power demand based on the equipment parameters of the offshore wind power AC transmission system.

[0073] The voltage constraint module 20 is configured to acquire the initial range of the reactive power compensation capacity configuration based on the offshore wind farm grid-connected point voltage limit and the overvoltage limit along the submarine cable.

[0074] The current constraint module 30 is configured to acquire the range of the reactive power compensation capacity configuration based on the offshore wind power AC transmission submarine cable current limit.

[0075] The reactive power capacity configuration module 40 is configured to determine the reactive power compensation capacity configuration scheme based on the range of the reactive power compensation capacity configuration and the system reactive power demand.

[0076] Specifically, after the acquisition module 10 acquires the system reactive power demand according to the equipment parameters, the voltage constraint module 20 and the current constraint module 30 accurately acquire the range of the reactive power compensation capacity configuration by using the submarine cable grid-connected point voltage limit, the submarine cable overvoltage limit, and the submarine cable current limit along the line, and then the reactive power capacity configuration module 40 synchronously configures the dynamic reactive power compensation capacity according to the configuration range and the system reactive power demand.

[0077] The offshore wind power AC transmission system reactive power compensation capacity configuration system provided in the application further comprises an investment comparison and selection module 50.

[0078] The application further provides an electronic device. Figure 6 As shown in the figure, the electronic device 90 provided in the embodiment comprises a memory 901 configured to store a computer program, and a processor 902 connected in communication with the memory 901 and configured to invoke the computer program to execute the method of the offshore wind power AC transmission system reactive power compensation capacity configuration.

[0079] The memory 901 comprises various media capable of storing program codes, such as ROM (Read Only Memory image), RAM (Random Access Memory), a magnetic disk, a U disk, a memory card, or an optical disk.

[0080] The processor 902 is connected with the memory 901 and is configured to execute the computer program stored in the memory 901, so that the electronic device executes the method of the offshore wind power AC transmission system reactive power compensation capacity configuration.

[0081] Preferably, the processor 902 can be a general processor, including a central processing unit (CPU), a network processor (NP), etc.; can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component.

[0082] In several embodiments provided in the present application, it should be understood that the disclosed system, device or method can be implemented in other ways. For example, the above-described device embodiments are only illustrative, for example, the division of the module / unit is only a logical function division, and actual implementation can have another division manner, for example, a plurality of modules or units can be combined or integrated into another system, or some features can be ignored or not executed.

[0083] The module / unit described as a separate component can be or can not be physically separated, and the component displayed as a module / unit can be or can not be a physical module, that is, can be located in one place, or can be distributed to a plurality of network units. According to actual needs, part or all of the modules / units can be selected to achieve the purpose of the embodiments of the present application. For example, the functional modules / units in each embodiment of the present application can be integrated in one processing module, or each module / unit can be physically present alone, or two or more modules / units can be integrated in one module / unit.

[0084] Those of ordinary skill in the art should further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized in electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in general terms in the above description. Whether the functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. A skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present application.

[0085] The embodiments of the present application further provide a computer readable storage medium. Those skilled in the art can understand that all or part of the steps of the methods described in the above embodiments can be instructed by a program to complete the processor, and the program can be stored in the computer readable storage medium. The storage medium is a non-transitory medium, such as a random access memory, a read-only memory, a flash memory, a hard disk, a solid state disk, a magnetic tape, a floppy disk, an optical disc, and any combination thereof. The storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, a data center, and the like, which includes one or more available media sets. The available medium can be a magnetic medium (for example, a floppy disk, a hard disk, a magnetic tape), an optical medium (for example, a digital video disc (DVD)), or a semiconductor medium (for example, a solid state disk (SSD)), and the like.

[0086] The embodiments of the present application can also provide a computer program product, which includes one or more computer instructions. When the computer instructions are loaded and executed on a computing device, all or part of the processes or functions described in the embodiments of the present application are generated. The computer instructions can be stored in a computer readable storage medium or transmitted from one computer readable storage medium to another, for example, the computer instructions can be transmitted from one website, computer or data center to another website, computer or data center through a wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) manner.

[0087] When the computer program product is executed by a computer, the computer executes the method described in the foregoing method embodiments. The computer program product can be a software installation package, and when the foregoing method is needed, the computer program product can be downloaded and executed on the computer.

[0088] The description of the corresponding processes or structures of each of the above figures has its own emphasis, and the parts not described in detail in a certain process or structure can be referred to the related description of other processes or structures.

[0089] The above embodiments are only illustrative of the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical idea of the present application should be covered by the claims of the present application.

Claims

1. A method for configuring reactive power compensation capacity of an offshore wind farm AC power transmission system, characterized in that, The method comprises the following steps: obtaining system reactive power demand based on equipment parameters of an offshore wind power AC transmission system; obtaining an initial range of reactive power compensation capacity configuration based on voltage limit of a grid-connected point of an offshore wind farm and overvoltage limit along a submarine cable; obtaining a range of reactive power compensation capacity configuration based on current limit along the submarine cable of the offshore wind power AC transmission system; the current limit along the submarine cable of the offshore wind power AC transmission system comprises allowable current carrying capacity of the submarine cable of the offshore wind power AC transmission system in air, J-type pipe, submarine burial depth and landing beach; determining a reactive power compensation capacity configuration scheme based on the range of reactive power compensation capacity configuration and the system reactive power demand; wherein, obtaining the initial range of reactive power compensation capacity configuration based on the voltage limit of the grid-connected point of the offshore wind farm and the overvoltage limit along the submarine cable comprises: preliminarily determining the reactive power compensation capacity configuration scheme based on the voltage limit of the grid-connected point; performing overvoltage limit analysis on the reactive power compensation capacity configuration scheme to obtain the initial range of reactive power compensation capacity configuration, including obtaining power frequency overvoltage and operating overvoltage of the offshore wind power transmission system under full load and no load; performing overvoltage limit analysis based on the power frequency overvoltage and the operating overvoltage to obtain the initial range of reactive power compensation capacity configuration.

2. The offshore wind farm AC transmission system reactive power compensation capacity configuration method of claim 1, wherein, The equipment parameters comprise offshore medium-voltage power collection line parameters, box-type transformer parameters, main transformer parameters, high-voltage submarine cable parameters and high-voltage land cable parameters.

3. The offshore wind farm AC transmission system reactive power compensation capacity configuration method of claim 2, wherein, Obtaining system reactive power demand based on equipment parameters of an offshore wind power AC transmission system comprises: cumulatively calculating reactive power generated by offshore medium-voltage power collection lines, box-type transformers, main transformers, high-voltage submarine cables and high-voltage land cables to obtain system reactive power demand.

4. The offshore wind farm AC transmission system reactive power compensation capacity configuration method of claim 1, wherein, Obtaining a range of reactive power compensation capacity configuration based on current limit along the submarine cable of the offshore wind power AC transmission system comprises: obtaining current values of the submarine cable of the offshore wind power AC transmission system in air, J-type pipe, submarine burial depth and landing beach under full load; obtaining the range of reactive power compensation capacity configuration based on the current values of the segments and the allowable current carrying capacity of the segments.

5. The offshore wind power AC transmission system reactive power compensation capacity configuration method of claim 1, further characterized by, Performing economicity check on the reactive power compensation capacity configuration scheme.

6. A system for configuring reactive power compensation capacity for an offshore wind farm AC transmission system, characterized in that, The method comprises the following steps: a obtaining module for obtaining system reactive power demand based on equipment parameters of an offshore wind power AC transmission system; a voltage constraint module for obtaining an initial range of reactive power compensation capacity configuration based on voltage limit of a grid-connected point of an offshore wind farm and overvoltage limit along a submarine cable; a current constraint module for obtaining a range of reactive power compensation capacity configuration based on current limit along the submarine cable of the offshore wind power AC transmission system; the current limit along the submarine cable of the offshore wind power AC transmission system comprises allowable current carrying capacity of the submarine cable of the offshore wind power AC transmission system in air, J-type pipe, submarine burial depth and landing beach; a reactive power capacity configuration module for determining a reactive power compensation capacity configuration scheme based on the range of reactive power compensation capacity configuration and the system reactive power demand; wherein, obtaining the initial range of reactive power compensation capacity configuration based on the voltage limit of the grid-connected point of the offshore wind farm and the overvoltage limit along the submarine cable comprises: preliminarily determining the reactive power compensation capacity configuration scheme based on the voltage limit of the grid-connected point; The overvoltage limiting analysis is performed on the reactive power compensation capacity configuration scheme to obtain an initial range of the reactive power compensation capacity configuration, including obtaining power frequency overvoltage and operating overvoltage of the offshore wind farm sending-out system under full load and no load; the overvoltage limiting analysis is performed based on the power frequency overvoltage and the operating overvoltage to obtain the initial range of the reactive power compensation capacity configuration.

7. The offshore wind farm AC transmission system reactive compensation capacity configuration system of claim 6, wherein, The offshore wind farm AC sending-out system reactive power compensation capacity configuration system further comprises an investment comparison and selection module; the investment comparison and selection module is used for performing economicity check on the reactive power compensation capacity configuration scheme.

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