Coordinated control method, device and medium of multi-terminal flexible DC transmission system based on average consistency

Abstract

The present invention discloses a coordinated control method, device, computer equipment and storage medium for a multi-terminal flexible direct current transmission system based on average consistency. The multi-terminal flexible direct current transmission system includes n flexible direct current converter stations. The method includes: collecting the frequency of the AC system connected to any flexible direct current converter station and the voltage of the DC system connected to it, respectively calculating the frequency difference and the first adjustment amount of the power reference value; determining the frequency over-limit mark according to the frequency difference, and then calculating the second adjustment amount of the power reference value; calculating the power reference value according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value; adjusting the power reference value according to the average consistency, and the flexible direct current converter station outputs the corresponding power according to the adjustment value. The present invention uses the method of adjusting the power reference value of the flexible direct current converter station according to the average consistency, without the need for a centralized controller, and avoiding system crashes caused by failure of the centralized controller. The method has strong applicability and application prospects.

Description

Technical Field

[0001] The present invention relates to a coordinated control method for a multi-terminal flexible direct current power transmission system, and in particular to a coordinated control method, device, computer equipment and storage medium for a multi-terminal flexible direct current power transmission system based on average consistency. Background Art

[0002] In order to meet the needs of long-distance and large-capacity transmission of renewable energy, more and more flexible DC transmission technology is being used in high-voltage transmission systems. In order to fully utilize DC channels to supply power to multiple load centers, more and more flexible transmission converter stations will be interconnected through common DC channels to form a multi-terminal flexible DC transmission system. The multi-terminal flexible DC transmission system has multiple independently regulated converter stations. It is a hot topic in current research to fully utilize the regulation capabilities of multiple converter stations, conduct research on coordinated control methods, and improve the overall reliability and safety of the system.

[0003] At present, some studies have proposed coordinated control methods for multi-terminal flexible DC transmission systems, but these methods all require a centralized coordinated controller to issue coordinated control instructions to each converter station. The system has poor scalability, large investment when the converter stations are distributed over a wide area, and difficult engineering implementation. When a failure occurs in the control center, the coordinated control capability will be lost, and the regulation capability of each converter station cannot be fully utilized to carry out emergency power support. The regulation capability of each converter station is not utilized, which reduces the safety and reliability of system operation. Summary of the invention

[0004] In order to solve the deficiencies of the above-mentioned prior art, the present invention provides a coordinated control method, device, computer equipment and storage medium for a multi-terminal flexible direct current transmission system based on average consistency. In the method, each converter station of the multi-terminal flexible direct current transmission system only needs to collect the frequency of the AC system and the voltage of the DC system to which it is connected, and divides the power reference value into three parts for calculation, wherein the calculation of the first adjustment amount of the power reference value only needs to use local measurement information, and the second adjustment amount of the power reference value adopts a consistency protocol for information exchange; finally, an average consistency control strategy is adopted to adjust the power reference by integrating the power reference values ​​of neighboring converter stations; the entire system has the characteristics of being fully distributed, and can make full use of the coordination of multiple converter stations for emergency power support, thereby improving the safety and reliability of system operation, and avoiding system crashes caused by failure of the centralized controller.

[0005] The first object of the present invention is to provide a coordinated control method for a multi-terminal flexible direct current transmission system based on average consistency.

[0006] The second object of the present invention is to provide a coordinated control device for a multi-terminal flexible direct current transmission system based on average consistency.

[0007] A third object of the present invention is to provide a computer device.

[0008] A fourth object of the present invention is to provide a storage medium.

[0009] The first object of the present invention can be achieved by adopting the following technical solutions:

[0010] A coordinated control method for a multi-terminal flexible direct current power transmission system based on average consistency, wherein the multi-terminal flexible direct current power transmission system comprises n flexible direct current converter stations, and the method comprises:

[0011] Collecting the frequency of the AC system connected to the i-th flexible DC converter station, and calculating the frequency difference of the AC system; i=1, ..., n;

[0012] Collect the voltage of the DC system connected to the i-th flexible DC converter station, and calculate the first adjustment amount of the power reference value;

[0013] Determining a frequency over-limit flag according to the frequency difference;

[0014] Calculating a second adjustment amount of the power reference value according to the frequency limit-crossing flag;

[0015] Calculating a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value;

[0016] Adjust the power reference value according to the average consistency to obtain an adjusted value of the power reference value;

[0017] According to the adjustment value, the i-th flexible DC converter station outputs corresponding power.

[0018] Further, the adjusting the power reference value according to the average consistency to obtain the adjusted value of the power reference value includes:

[0019] The adjustment value of the power reference value is calculated according to the following formula:

[0020]

[0021] Among them, P ref,new,i is the adjustment value of the power reference value of the i-th flexible DC converter station; P ref,i is the power reference value; P ref,j is the power reference value of the j-th flexible DC converter station, and i≠j; S i and S j are the capacities of the i-th and j-th flexible DC converter stations respectively; N iis the set of neighbors of the i-th flexible DC converter station, where the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that communicate directly with the flexible DC converter station; |N i | is the number of neighbors of the i-th flexible DC converter station.

[0022] Further, the calculating the power reference value of the i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value includes:

[0023] The power reference value of the i-th flexible DC converter station is calculated according to the following formula:

[0024] P ref,i =P ref,i,0 +ΔP ref,i,1 -ΔP ref,i,2

[0025] Among them, P ref,i is the power reference value of the i-th flexible DC converter station; ΔP ref,i,1 is the first adjustment amount of the power reference value, ΔP ref,i,2 is the second adjustment amount of the power reference value; ref,i,0 is the first set threshold, which represents the basic value of the power reference value of the i-th flexible DC converter station.

[0026] Further, the calculating the second adjustment amount of the power reference value according to the frequency limit crossing flag includes:

[0027] The second adjustment of the power reference value is calculated according to the following formula:

[0028]

[0029] Among them, ΔP ref,i,2 is the second adjustment value of the power reference value of the i-th flexible DC converter station; K DC,f,i is the frequency limit-exceeding mark; Δf j is the frequency difference of the AC system connected to the j-th flexible DC converter station, and i≠j; N i is the set of neighbors of the i-th flexible DC converter station, where the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that communicate directly with the flexible DC converter station; |N i | is the number of neighbors of the i-th flexible DC converter station; K f,i is the second set threshold, representing the adjustment coefficient of the second adjustment amount of the power reference value of the i-th flexible DC converter station.

[0030] Furthermore, assuming that the frequency difference is Δf i , the frequency limit flag is K DC,f,i ;

[0031] Determining the frequency limit crossing flag according to the frequency difference is specifically as follows:

[0032] If |Δf i |≤f lim , then K DC,f,i =0, otherwise K DC,f,i =1;

[0033] Among them, f lim It is the frequency variation limit of the AC system.

[0034] Furthermore, the collecting of the voltage of the DC system to which the i-th flexible DC converter station is connected and the calculation of the first adjustment amount of the power reference value include:

[0035] Calculate the first adjustment of the power reference value according to the following formula:

[0036]

[0037] Among them, ΔP ref,i,1 is the first adjustment value of the power reference value of the i-th flexible DC converter station; V DC,i and V ref,DC,i are the DC voltage and the reference value of the DC voltage of the DC system connected to the i-th flexible DC converter station respectively; K DC,i is the third set threshold, representing the adjustment coefficient of the first adjustment amount of the power reference value of the i-th flexible DC converter station.

[0038] Furthermore, collecting the frequency of the AC system to which the i-th flexible DC converter station is connected and calculating the frequency difference of the AC system includes:

[0039] The frequency difference of the AC system is calculated according to the following formula:

[0040] Δf i =f i -f N

[0041] Where Δf i is the frequency fluctuation of the AC system connected to the i-th flexible DC converter station; f i is the frequency of the AC system connected to the i-th flexible DC converter station; f N is the rated frequency of the AC system.

[0042] The second object of the present invention can be achieved by adopting the following technical solutions:

[0043] A coordinated control device for a multi-terminal flexible direct current power transmission system based on average consistency, wherein the multi-terminal flexible direct current power transmission system comprises n flexible direct current converter stations, and the device comprises:

[0044] A frequency acquisition module is used to acquire the frequency of the AC system connected to the i-th flexible DC converter station and calculate the frequency difference of the AC system; i=1, ..., n;

[0045] A voltage acquisition module is used to collect the voltage of the DC system connected to the i-th flexible DC converter station and calculate the first adjustment amount of the power reference value;

[0046] A determination module, used to determine a frequency limit-crossing flag according to the frequency difference;

[0047] A first calculation module, configured to calculate a second adjustment amount of the power reference value according to the frequency limit crossing flag;

[0048] A second calculation module, configured to calculate a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value;

[0049] A third calculation module, configured to adjust the power reference value according to the average consistency to obtain an adjusted value of the power reference value;

[0050] The power support module is used for the i-th flexible DC converter station to output corresponding power according to the adjustment value.

[0051] The third object of the present invention can be achieved by adopting the following technical solutions:

[0052] A computer device comprises a processor and a memory for storing a program executable by the processor, wherein when the processor executes the program stored in the memory, the above-mentioned coordinated control method of a multi-terminal flexible direct current transmission system is implemented.

[0053] The fourth object of the present invention can be achieved by adopting the following technical solutions:

[0054] A storage medium stores a program, and when the program is executed by a processor, the above-mentioned coordinated control method of a multi-terminal flexible direct current transmission system is implemented.

[0055] The present invention has the following beneficial effects compared with the prior art:

[0056] The coordinated control method of a multi-terminal flexible DC transmission system provided by the present invention only needs to collect the frequency of the AC system connected to any flexible DC converter station and the DC voltage of the connected DC system, adjust the reference power according to the frequency change, and calculate the new reference value using the average consistency method. This method effectively utilizes the power regulation capabilities of multiple flexible DC converter stations, can provide power support at the same time when a certain AC system fails, and improves the safety and robustness of system operation. By adjusting the power reference value of the flexible DC converter station according to the average consistency, there is no need for a centralized controller, which improves the applicability and scalability of the coordinated control method and avoids system crashes caused by failure of the centralized controller. The method is simple, easy to implement, and has good market application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0058] Figure 1 This is a flow chart of a coordinated control method for a multi-terminal flexible direct current transmission system based on average consistency according to Example 1 of the present invention.

[0059] Figure 2 This is a schematic diagram of the structure of a multi-terminal flexible direct current transmission system according to Embodiment 1 of the present invention.

[0060] Figure 3 This is a structural block diagram of a multi-terminal flexible direct current transmission system coordinated control device based on average consistency according to Example 2 of the present invention.

[0061] Figure 4 This is a structural block diagram of a computer device according to Embodiment 3 of the present invention. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. It should be understood that the specific embodiments described are only used to explain the present application and are not used to limit the present application.

[0063] Embodiment 1:

[0064] like Figure 1 As shown, this embodiment provides a coordinated control method for a multi-terminal flexible direct current transmission system based on average consistency. The multi-terminal flexible direct current transmission system is as follows: Figure 2 As shown in the figure, the system includes multiple flexible DC converter stations, each of which is connected to its own AC system and connected together through DC lines. During normal operation, each flexible DC converter station adjusts power exchange according to the difference between the frequency of its own AC system and the rated frequency; when the AC system of a flexible DC converter station fails, the stations exchange information with each other, use average consistency to generate additional control signals, and achieve frequency support under fault conditions through the coordinated cooperation of each flexible DC converter station, thereby improving the safety of system operation.

[0065] Assume that the multi-terminal flexible DC transmission system includes n flexible DC converter stations, and each converter station adopts the same control strategy. The control strategy of the converter station based on average consistency is explained by taking the i-th flexible DC converter station as an example, which specifically includes the following steps:

[0066] S101, collecting the frequency of the AC system connected to the i-th flexible DC converter station, and calculating the frequency difference:

[0067] Δf i =f i -f N (1)

[0068] Where Δf i is the frequency fluctuation of the AC system connected to the i-th flexible DC converter station; f i is the frequency of the AC system connected to the i-th flexible DC converter station; f N is the rated frequency, which is the same for all AC systems.

[0069] f N It is a constant of the power system, and the domestic value is 50Hz.

[0070] S102, collecting the voltage of the DC system connected to the i-th flexible DC converter station, and calculating the first adjustment amount of the power reference value:

[0071]

[0072] Among them, ΔP ref,i,1 is the first adjustment value of the power reference value of the i-th flexible DC converter station; V DC,i and V ref,DC,i are the DC voltage and the reference value of the DC voltage of the DC system connected to the i-th flexible DC converter station respectively; K DC,i is the adjustment coefficient of the first adjustment amount of the power reference value of the i-th flexible DC converter station, which is the set value.

[0073] K DC,iIt is set based on experience and remains unchanged during operation.

[0074] S103, determining a frequency over-limit flag according to the frequency difference:

[0075] If |Δf i |≤f lim , then set K DC,f,i =0, otherwise K DC,f,i =1;

[0076] Among them, f lim is the frequency variation limit, which is the same for all AC systems; K DC,f,i It is the frequency over-limit mark of the i-th flexible DC converter station.

[0077] f lim To determine the value, it is stipulated by national standards.

[0078] S104. Calculate the second adjustment amount of the power reference value according to the frequency limit-crossing flag:

[0079]

[0080] Among them, ΔP ref,i,2 is the second adjustment value of the power reference value of the i-th flexible DC converter station; Δf j is the frequency fluctuation of the AC system connected to the j-th flexible DC converter station, and i≠j; N i is the set of neighbors of the i-th flexible DC converter station, and the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that can directly communicate with the converter station; |N i | is the number of neighbors of the i-th flexible DC converter station; K f,i is the adjustment coefficient of the second adjustment amount of the power reference value of the i-th flexible DC converter station, which is the set value.

[0081] K f,i It is set based on experience and remains unchanged during operation.

[0082] S105. Calculate the power reference value of the i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value:

[0083] P ref,i =P ref,i,0 +ΔP ref,i,1 -ΔP ref,i,2 (4)

[0084] Among them, P ref,i is the power reference value of the i-th flexible DC converter station; P ref,i,0 is the basic quantity of the power reference value of the i-th flexible DC converter station, which is usually set in advance by the dispatcher.

[0085] S106. Adjust the power reference value according to the average consistency:

[0086]

[0087] Among them, P ref,new,i is the adjustment value of the power reference value of the i-th flexible DC converter station; P ref,j is the power reference value of the j-th flexible DC converter station; S i and S j are the capacities of the i-th and j-th flexible DC converter stations respectively.

[0088] S107. According to the adjustment value of the power reference value, the i-th flexible DC converter station outputs corresponding power.

[0089] The i-th flexible DC converter station outputs a corresponding power value according to the adjustment value of the power reference value calculated in step S106.

[0090] Those skilled in the art will appreciate that all or part of the steps in the method for implementing the above embodiments may be completed by instructing related hardware through a program, and the corresponding program may be stored in a computer-readable storage medium.

[0091] It should be noted that although the method operations of the above embodiments are described in a specific order in the accompanying drawings, this does not require or imply that these operations must be performed in this specific order, or that all the operations shown must be performed to achieve the desired results. On the contrary, the steps depicted can be performed in a different order. Additionally or alternatively, some steps can be omitted, multiple steps can be combined into one step, and / or one step can be decomposed into multiple steps.

[0092] Embodiment 2:

[0093] like Figure 3 As shown, this embodiment provides a coordinated control device for a multi-terminal flexible direct current transmission system based on average consistency, wherein the multi-terminal flexible direct current transmission system includes n flexible direct current converter stations, and the device includes a frequency acquisition module 301, a voltage acquisition module 302, a determination module 303, a first calculation module 304, a second calculation module 305, a third calculation module 306 and a power support module 307, wherein:

[0094] The frequency acquisition module 301 is used to acquire the frequency of the AC system connected to the i-th flexible DC converter station and calculate the frequency difference of the AC system; i=1, ..., n;

[0095] The voltage collection module 302 is used to collect the voltage of the DC system to which the i-th flexible DC converter station is connected, and calculate the first adjustment amount of the power reference value;

[0096] A determination module 303, configured to determine a frequency limit crossing flag according to the frequency difference;

[0097] A first calculation module 304, configured to calculate a second adjustment amount of the power reference value according to the frequency limit crossing flag;

[0098] A second calculation module 305 is used to calculate the power reference value of the i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value;

[0099] A third calculation module 306, configured to adjust the power reference value according to the average consistency to obtain an adjusted value of the power reference value;

[0100] The power support module 307 is used for the i-th flexible DC converter station to output corresponding power according to the adjustment value.

[0101] The specific implementation of each module in this embodiment can refer to the above-mentioned embodiment 1, which will not be described one by one here; it should be noted that the device provided in this embodiment is only illustrated by the division of the above-mentioned functional modules. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure can be divided into different functional modules to complete all or part of the functions described above.

[0102] Embodiment 3:

[0103] This embodiment provides a computer device, which may be a computer, such as Figure 4 As shown, a processor 402, a memory, an input device 403, a display 404 and a network interface 405 connected through a system bus 401, the processor is used to provide computing and control capabilities, the memory includes a non-volatile storage medium 406 and an internal memory 407, the non-volatile storage medium 406 stores an operating system, a computer program and a database, the internal memory 407 provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium, when the processor 402 executes the computer program stored in the memory, the coordinated control method of the multi-terminal flexible direct current transmission system of the above-mentioned embodiment 1 is implemented as follows:

[0104] Collecting the frequency of the AC system connected to the i-th flexible DC converter station, and calculating the frequency difference of the AC system; i=1, ..., n; n is the total number of flexible DC converter stations included in the multi-terminal flexible DC transmission system;

[0105] Collect the voltage of the DC system connected to the i-th flexible DC converter station, and calculate the first adjustment amount of the power reference value;

[0106] Determining a frequency over-limit flag according to the frequency difference;

[0107] Calculating a second adjustment amount of the power reference value according to the frequency limit-crossing flag;

[0108] Calculating a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value;

[0109] Adjust the power reference value according to the average consistency to obtain an adjusted value of the power reference value;

[0110] According to the adjustment value, the i-th flexible DC converter station outputs corresponding power.

[0111] Embodiment 4:

[0112] This embodiment provides a storage medium, which is a computer-readable storage medium, storing a computer program. When the computer program is executed by a processor, the coordinated control method of a multi-terminal flexible direct current transmission system in the above embodiment 1 is implemented as follows:

[0113] Collecting the frequency of the AC system connected to the i-th flexible DC converter station, and calculating the frequency difference of the AC system; i=1, ..., n; n is the total number of flexible DC converter stations included in the multi-terminal flexible DC transmission system;

[0114] Collect the voltage of the DC system connected to the i-th flexible DC converter station, and calculate the first adjustment amount of the power reference value;

[0115] Determining a frequency over-limit flag according to the frequency difference;

[0116] Calculating a second adjustment amount of the power reference value according to the frequency limit-crossing flag;

[0117] Calculating a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value;

[0118] Adjust the power reference value according to the average consistency to obtain an adjusted value of the power reference value;

[0119] According to the adjustment value, the i-th flexible DC converter station outputs corresponding power.

[0120] It should be noted that the computer-readable storage medium of the present embodiment may be a computer-readable signal medium or a computer-readable storage medium or any combination of the above two. The computer-readable storage medium may be, for example, but not limited to, an electrical, magnetic, optical, electromagnetic, infrared, or semiconductor system, device or device, or any combination of the above. More specific examples of computer-readable storage media may include, but are not limited to: an electrical connection with one or more wires, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the above.

[0121] In summary, any flexible DC converter station in the multi-terminal flexible DC transmission system of the present invention connects its own AC system to the public DC system, so that active power can be exchanged between the AC systems. During operation, each flexible DC converter station calculates the difference between the frequency of its own AC system and the rated frequency, and only calculates the first adjustment amount of the power reference value when the difference does not exceed the allowable limit, and also calculates the second adjustment amount of the power reference value when the difference exceeds the allowable limit; the basic amount, the first adjustment amount and the second adjustment amount of the power reference value are integrated to calculate the power reference value; the average consistency control strategy is adopted to adjust the power reference by integrating the power reference values ​​of adjacent flexible DC converter stations, and finally each flexible DC converter station adjusts the active power passing through itself according to the adjusted power reference value.

[0122] The above is only a preferred embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and inventive concept of the present invention within the scope disclosed by the present invention, which shall fall within the protection scope of the present invention.

Claims

1. A coordinated control method for a multi-terminal flexible direct current transmission system based on average consistency, wherein the multi-terminal flexible direct current transmission system comprises n flexible direct current converter stations, characterized in that: The method comprises: Collecting the frequency of the AC system connected to the i-th flexible DC converter station, and calculating the frequency difference of the AC system; i=1, ..., n; Collect the voltage of the DC system connected to the i-th flexible DC converter station, and calculate the first adjustment amount of the power reference value; Determining a frequency over-limit flag according to the frequency difference; Calculating a second adjustment amount of the power reference value according to the frequency limit-crossing flag; Calculating a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value; The power reference value is adjusted according to the average consistency, and the adjusted value of the power reference value is obtained by the following formula: Among them, P ref,new,i is the adjustment value of the power reference value of the i-th flexible DC converter station; P ref,i is the power reference value; P ref,j is the power reference value of the j-th flexible DC converter station, and i≠j; S i and S j are the capacities of the i-th and j-th flexible DC converter stations respectively; N i is the set of neighbors of the i-th flexible DC converter station, where the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that communicate directly with the flexible DC converter station; |N i | is the number of neighbors of the i-th flexible DC converter station; According to the adjustment value, the i-th flexible DC converter station outputs corresponding power.

2. The coordinated control method of a multi-terminal flexible direct current transmission system according to claim 1, characterized in that: The calculating the power reference value of the i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value includes: The power reference value of the i-th flexible DC converter station is calculated according to the following formula: P ref,i =P ref,i,0 +ΔP ref,i,1 -ΔP ref,i,2 Among them, P ref,i is the power reference value of the i-th flexible DC converter station; ΔP ref,i,1 is the first adjustment amount of the power reference value, ΔP ref,i,2 is the second adjustment amount of the power reference value; ref,i,0 is the first set threshold, which represents the basic value of the power reference value of the i-th flexible DC converter station.

3. The coordinated control method of a multi-terminal flexible direct current transmission system according to claim 1, characterized in that: The calculating the second adjustment amount of the power reference value according to the frequency limit crossing flag includes: The second adjustment of the power reference value is calculated according to the following formula: Among them, ΔP ref,i,2 is the second adjustment value of the power reference value of the i-th flexible DC converter station; K DC,f,i is the frequency limit-exceeding mark; Δf j is the frequency difference of the AC system connected to the j-th flexible DC converter station, and i≠j; N i is the set of neighbors of the i-th flexible DC converter station, where the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that communicate directly with the flexible DC converter station; |N i | is the number of neighbors of the i-th flexible DC converter station; K f,i is the second set threshold, representing the adjustment coefficient of the second adjustment amount of the power reference value of the i-th flexible DC converter station.

4. The coordinated control method for a multi-terminal flexible direct current transmission system according to claim 1 is characterized in that: The frequency difference is Δf i , the frequency limit flag is K DC,f,i ; Determining the frequency limit crossing flag according to the frequency difference is specifically as follows: If |Δf i |≤f lim , then K DC,f,i =0, otherwise K DC,f,i =1; Among them, f lim It is the frequency variation limit of the AC system.

5. The coordinated control method of a multi-terminal flexible direct current transmission system according to claim 1, characterized in that: The collecting the voltage of the DC system connected to the i-th flexible DC converter station and calculating the first adjustment amount of the power reference value includes: Calculate the first adjustment of the power reference value according to the following formula: Among them, ΔP ref,i,1 is the first adjustment value of the power reference value of the i-th flexible DC converter station; V DC,i and V ref,DC,i are the DC voltage and the reference value of the DC voltage of the DC system connected to the i-th flexible DC converter station respectively; K DC,i is the third set threshold, representing the adjustment coefficient of the first adjustment amount of the power reference value of the i-th flexible DC converter station.

6. The coordinated control method for a multi-terminal flexible direct current transmission system according to any one of claims 1 to 5, characterized in that: Collecting the frequency of the AC system connected to the i-th flexible DC converter station and calculating the frequency difference of the AC system include: The frequency difference of the AC system is calculated according to the following formula: Δf i =f i -f N Where Δf i is the frequency fluctuation of the AC system connected to the i-th flexible DC converter station; f i is the frequency of the AC system connected to the i-th flexible DC converter station; f N is the rated frequency of the AC system.

7. A coordinated control device for a multi-terminal flexible direct current transmission system based on average consistency, wherein the multi-terminal flexible direct current transmission system comprises n flexible direct current converter stations, characterized in that: The device comprises: A frequency acquisition module is used to acquire the frequency of the AC system connected to the i-th flexible DC converter station and calculate the frequency difference of the AC system; i=1, ..., n; A voltage acquisition module is used to collect the voltage of the DC system connected to the i-th flexible DC converter station and calculate the first adjustment amount of the power reference value; A determination module, used to determine a frequency limit-crossing flag according to the frequency difference; A first calculation module, configured to calculate a second adjustment amount of the power reference value according to the frequency limit crossing flag; A second calculation module, configured to calculate a power reference value of an i-th flexible DC converter station according to the first adjustment amount of the power reference value and the second adjustment amount of the power reference value; A third calculation module is used to adjust the power reference value according to the average consistency, and obtain the adjustment value of the power reference value through the following formula; Among them, P ref,new,i is the adjustment value of the power reference value of the i-th flexible DC converter station; P ref,i is the power reference value; P ref,j is the power reference value of the j-th flexible DC converter station, and i≠j; S i and S j are the capacities of the i-th and j-th flexible DC converter stations respectively; N i is the set of neighbors of the i-th flexible DC converter station, where the neighbors of the i-th flexible DC converter station refer to the flexible DC converter stations that communicate directly with the flexible DC converter station; |N i | is the number of neighbors of the i-th flexible DC converter station; The power support module is used for the i-th flexible DC converter station to output corresponding power according to the adjustment value.

8. A computer device comprising a processor and a memory for storing a program executable by the processor, characterized in that: When the processor executes the program stored in the memory, the coordinated control method of the multi-terminal flexible direct current transmission system according to any one of claims 1 to 6 is implemented.

9. A storage medium storing a program, characterized in that: When the program is executed by a processor, the coordinated control method of a multi-terminal flexible direct current transmission system according to any one of claims 1 to 6 is implemented.

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