Fault ride-through method of flexible direct current power transmission system and related device

Abstract

The invention discloses a fault ride-through method of a flexible direct-current power transmission system and a related device. The method comprises the following steps: detecting the flexible direct-current power transmission system; when the offshore converter station detects a fault signal, calling an unloading circuit to input and consume surplus power, and enabling an energy self-balancing converter valve of the offshore converter station to input or quit according to an input fixed value and a quit fixed value so as to consume the surplus power; and when the onshore converter station detects a fault signal, responding to the fault signal sent by the onshore converter station, calling the unloading circuit to input and consume surplus power, and enabling the energy self-balancing converter valves of the offshore converter station and the onshore converter station to input or quit according to the input fixed value and the quit fixed value to consume the surplus power. According to the method, a centralized direct-current energy consumption device does not need to be configured, surplus power is consumed through cooperation of the energy self-balancing converter valve and the unloading circuit, alternating-current faults and direct-current faults can be dealt with, and the construction cost can be greatly reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible direct current power transmission, and in particular to a fault ride-through method and related devices for a flexible direct current power transmission system. Background Art

[0002] The flexible direct current transmission technology based on voltage source converter (VSC-HVDC) has a small footprint, compact modular structure, and low cost for long-distance transmission. It is the best choice for offshore wind power grid connection.

[0003] To ensure the safe and reliable operation of the system, the offshore wind power grid-connected system should have the ability to ride through AC faults. In the project, a centralized DC energy consumption is generally configured on the DC side of the receiving onshore converter station. Large-scale deep-sea wind power bases should adopt a cable-overhead line hybrid line solution to directly send power to the load center. The submarine cables are collected on land and sent to the load center by overhead lines. Compared with the traditional solution of using submarine cables for transmission, the project cost can be greatly reduced. However, DC overhead lines are prone to short-circuit faults. Therefore, in addition to the AC fault ride-through capability, the flexible DC transmission system is also required to have the ability to ride through DC faults. However, the centralized DC energy consumption device has a complex structure, involves a large number of controllable power devices, is expensive, requires additional land, and can only deal with AC power grid faults, but cannot handle DC overhead line faults. Summary of the invention

[0004] The present invention provides a fault ride-through method and related devices for a flexible direct current transmission system, which are used to solve the problem that the prior art requires the consumption of surplus power through a centralized direct current energy consumption device, resulting in high construction costs and can only cope with AC power grid faults but cannot handle DC overhead line faults.

[0005] In view of this, the first aspect of the present application provides a fault ride-through method for a flexible direct current transmission system, the flexible direct current transmission system comprising: an offshore converter station and an onshore converter station respectively equipped with energy self-balancing converter valves, and a wind power converter provided with a load shedding circuit;

[0006] Methods include:

[0007] S1, setting the input constant value when the energy self-balancing converter valve is put into use to consume the remaining surplus power, and the exit constant value when the energy self-balancing converter valve is exited from consuming the remaining surplus power, and determining the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve;

[0008] S2, detecting the flexible DC power transmission system through the offshore converter station and the onshore converter station respectively, and executing step S3 when the offshore converter station detects a fault signal, and executing step S4 when the onshore converter station detects a fault signal;

[0009] S3. Based on the allocation ratio, the unloading circuit is called to consume the surplus power, and at the same time, the energy self-balancing converter valve of the offshore converter station is put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power;

[0010] S4. In response to the fault signal sent by the onshore converter station, based on the allocation ratio, the unloading circuit is called to consume the surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power.

[0011] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0012] Setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to the fault type judgment method;

[0013] The fault type determination method is: when the flexible DC power transmission system fails, the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0014] in, is a coefficient, determined by the type of fault detected, It is the actual power of the offshore wind power flexible DC transmission system before the fault.

[0015] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0016] According to the surplus power ratio allocation method, setting the allocation ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve;

[0017] The surplus power ratio allocation method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0018] in, is the coefficient.

[0019] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0020] According to the surplus power fixed reduction method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve;

[0021] The surplus power fixed reduction method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0022] in, It is the power consumption setting value of the energy self-balancing converter valve.

[0023] A second aspect of the present application provides a fault ride-through system of a flexible direct current transmission system, the flexible direct current transmission system comprising: an offshore converter station and an onshore converter station each equipped with an energy self-balancing converter valve, and a wind power converter provided with a load shedding circuit;

[0024] The system comprises:

[0025] a setting unit, used to set a starting constant value when the energy self-balancing converter valve is started to consume the remaining surplus power, and a quitting constant value when the energy self-balancing converter valve is quit to consume the remaining surplus power, and determine a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve;

[0026] a detection unit, configured to detect the flexible DC power transmission system through the offshore converter station and the onshore converter station respectively, triggering a first control unit when the offshore converter station detects a fault signal, and triggering a second control unit when the onshore converter station detects a fault signal;

[0027] A first control unit is used to call the unloading circuit to consume surplus power based on the allocation ratio, and at the same time, to make the energy self-balancing converter valve of the offshore converter station be put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power;

[0028] The second control unit is used to respond to the fault signal sent by the onshore converter station and, based on the allocation ratio, call the unloading circuit to consume surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into operation or exited according to the input constant value and the exit constant value to consume the remaining surplus power.

[0029] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0030] Setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to the fault type judgment method;

[0031] The fault type determination method is: when the flexible DC power transmission system fails, the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0032] in, is a coefficient, determined by the type of fault detected, It is the actual power of the offshore wind power flexible DC transmission system before the fault.

[0033] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0034] According to the surplus power ratio allocation method, the allocation ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve is set;

[0035] The surplus power ratio allocation method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0036] in, is the coefficient.

[0037] Optionally, the determining a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

[0038] According to the surplus power fixed reduction method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve;

[0039] The surplus power fixed reduction method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0040] in, It is the power consumption setting value of the energy self-balancing converter valve.

[0041] A third aspect of the present invention provides a fault ride-through device for a flexible direct current transmission system, the device comprising a processor and a memory:

[0042] The memory is used to store program code and transmit the program code to the processor;

[0043] The processor is used to execute the steps of the fault ride-through method of the flexible direct current transmission system as described in the first aspect according to the instructions in the program code.

[0044] A fourth aspect of the present invention provides a computer-readable storage medium, wherein the computer-readable storage medium is used to store program code, and the program code is used to execute the fault ride-through method of the flexible direct current transmission system described in the first aspect above.

[0045] It can be seen from the above technical solutions that the present invention has the following advantages:

[0046] The present invention provides a fault ride-through method for a flexible DC power transmission system, which does not require the configuration of a centralized DC energy consumption device. The energy self-balancing converter valve and the unloading circuit cooperate to consume surplus power, which can cope with AC faults and DC faults and can significantly reduce the project cost. This solves the problem that the existing technology needs to consume surplus power through a centralized DC energy consumption device, resulting in high construction costs and can only cope with AC power grid faults, but cannot handle DC overhead line faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] 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 these drawings without paying creative labor.

[0048] Figure 1 A schematic flow chart of a fault ride-through method for a flexible direct current transmission system provided by an embodiment of the present invention;

[0049] Figure 2An offshore wind power energy self-balancing flexible direct current transmission system provided by an embodiment of the present invention;

[0050] Figure 3 A schematic diagram of a control strategy for a fault ride-through method for a flexible DC power transmission system provided by an embodiment of the present invention;

[0051] Figure 4 A schematic structural diagram of a fault ride-through system of a flexible direct current transmission system provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0052] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions 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 embodiments described below are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of 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.

[0053] See also Figure 1 A fault ride-through method for a flexible direct current transmission system is provided in an embodiment of the present invention. The flexible direct current transmission system comprises: an offshore converter station and an onshore converter station each equipped with an energy self-balancing converter valve, and a wind power converter provided with a load shedding circuit.

[0054] It should be noted that the structure of the flexible DC transmission system of this embodiment is as follows: Figure 2 As shown, including: offshore wind turbines ( Figure 2 The wind turbines in the power plant), wind power converters, offshore converter stations, and onshore converter stations. Among them, the wind power converter is equipped with a load shedding circuit, and the offshore converter station and onshore converter station use energy self-balancing flexible DC converter valves, both of which are equipped with energy self-balancing branches. The load shedding circuit and energy self-balancing branch can consume the surplus power caused by the fault. The offshore converter station is connected to the onshore converter station through a DC submarine cable and a DC overhead line.

[0055] like Figure 1 and 3 As shown, the method includes:

[0056] Step 101, setting an input constant value when the energy self-balancing converter valve is put into use to consume the remaining surplus power, and an exit constant value when the energy self-balancing converter valve is exited to consume the remaining surplus power, and determining the distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve.

[0057] It should be noted that if Figure 3 As shown, is the power module voltage of the energy self-balancing converter valve, is the set input value, The exit value to be set.

[0058] Step 102: Detect the flexible DC transmission system through the offshore converter station and the onshore converter station respectively. When the offshore converter station detects a fault signal, execute step 103; when the onshore converter station detects a fault signal, execute step 104.

[0059] Step 103: Based on the allocation ratio, the unloading circuit is called to consume the surplus power. At the same time, the energy self-balancing converter valve of the offshore converter station is put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power.

[0060] It is understandable that if Figure 2 and 3 As shown in Figure 1, when a DC transmission line fails, the offshore converter station detects the fault signal of the DC transmission line and actively calls the unloading circuit based on the allocation ratio to consume the surplus power. At the same time, due to the surplus power, the power module voltage of the offshore energy self-balancing converter valve at the sending end Therefore, the energy self-balancing converter valve at the sending end is set according to the set input value. , Exit fixed value Autonomously consumes the remaining surplus power.

[0061] Step 104, in response to the fault signal sent by the onshore converter station, based on the allocation ratio, the unloading circuit is called to consume the surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into or out of operation according to the input setting value and the exit setting value to consume the remaining surplus power.

[0062] It is understandable that if Figure 2 and 3 As shown in Figure 1, when a fault occurs in the receiving AC system, the onshore converter station detects the fault signal of the receiving AC system and sends the fault signal to the offshore converter station. The offshore converter station actively calls the unloading circuit to consume the surplus power. At the same time, due to the surplus power, the power module voltage of the onshore converter valve at the receiving end , DC transmission line voltage, power module voltage of the sending end offshore converter valve The energy self-balancing converter valves at the sending and receiving ends are increased according to the set input values. , Exit fixed value Autonomously consumes the remaining surplus power.

[0063] In one embodiment, the determination of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve in step 102 includes: a fault type judgment method, a surplus power ratio distribution method, and a surplus power fixed reduction method.

[0064] 1) The fault type judgment method is: when a fault occurs in the flexible DC transmission system, the surplus power consumed by calling the unloading circuit is: , the surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0065] in, is a coefficient, determined by the type of fault detected, It is the actual power of the offshore wind power flexible DC transmission system before the fault.

[0066] It should be noted that when the fault type is a DC line fault or a three-phase grounding fault in the receiving AC system, The typical value range is 80-100%. When the fault type is a single-phase grounding fault in the receiving AC system, Typical values ​​range from 20-40%.

[0067] 2) The surplus power ratio allocation method is to calculate the surplus power caused by the failure of the flexible DC transmission system in real time. , the surplus power consumed by calling the unloading circuit is: , the surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;in, is the coefficient.

[0068] It should be noted that Typical values ​​range from 70-90%.

[0069] 3) The surplus power fixed reduction method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: , the surplus power consumed by the energy self-balancing converter valve is: surplus power minus ;

[0070] in, It is the power consumption setting value of the energy self-balancing converter valve, which is determined by the design parameters of the energy self-balancing converter valve.

[0071] The present invention provides a fault ride-through method for a flexible direct current transmission system, which does not require the configuration of a centralized direct current energy consumption device. By consuming surplus power through the cooperation of an energy self-balancing converter valve and a load-shedding circuit, it can cope with direct current line faults and receiving-end alternating current system faults, thereby greatly reducing costs.

[0072] The above is a fault ride-through method of a flexible DC power transmission system provided in an embodiment of the present invention, and the following is a fault ride-through system of a flexible DC power transmission system provided in an embodiment of the present invention.

[0073] See also Figure 4 , a fault ride-through system of a flexible direct current transmission system provided in an embodiment of the present invention, the flexible direct current transmission system comprising: an offshore converter station and an onshore converter station respectively equipped with energy self-balancing converter valves, and a wind power converter provided with a load shedding circuit;

[0074] The system includes:

[0075] The setting unit 201 is used to set the input constant value when the energy self-balancing converter valve is put into use to consume the remaining surplus power, and the exit constant value when the energy self-balancing converter valve is exited to consume the remaining surplus power, and determine the distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve.

[0076] The detection unit 202 is used to detect the flexible DC transmission system through the offshore converter station and the onshore converter station respectively, and trigger the first control unit 203 when the offshore converter station detects a fault signal, and trigger the second control unit 204 when the onshore converter station detects a fault signal.

[0077] The first control unit 203 is used to call the unloading circuit to consume surplus power based on the allocation ratio, and at the same time, enable the energy self-balancing converter valve of the offshore converter station to be put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power.

[0078] The second control unit 204 is used to respond to the fault signal sent by the onshore converter station, and based on the allocation ratio, call the unloading circuit to consume the surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into or exited according to the input setting value and the exit setting value to consume the remaining surplus power.

[0079] Furthermore, an embodiment of the present invention also provides a fault ride-through device for a flexible direct current transmission system, the device comprising a processor and a memory:

[0080] The memory is used to store program code and transmit the program code to the processor;

[0081] The processor is used to execute the steps of the fault ride-through method of the flexible direct current transmission system as described in the above method embodiment according to the instructions in the program code.

[0082] Furthermore, an embodiment of the present invention also provides a computer-readable storage medium, which is used to store program codes, and the program codes are used to execute the fault ride-through method of the flexible direct current transmission system described in the above method embodiment.

[0083] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0084] In the several embodiments provided by the present invention, it should be understood that the disclosed systems, devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0085] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0086] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0087] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0088] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A fault ride-through method for a flexible direct current transmission system, characterized in that: The flexible direct current power transmission system comprises: an offshore converter station and an onshore converter station each equipped with an energy self-balancing converter valve, and a wind power converter provided with a load shedding circuit; Methods include: S1, setting the input constant value when the energy self-balancing converter valve is put into use to consume the remaining surplus power, and the exit constant value when the energy self-balancing converter valve is exited from consuming the remaining surplus power, and determining the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; S2, detecting the flexible DC power transmission system through the offshore converter station and the onshore converter station respectively, and executing step S3 when the offshore converter station detects a fault signal, and executing step S4 when the onshore converter station detects a fault signal; S3. Based on the allocation ratio, the unloading circuit is called to consume the surplus power, and at the same time, the energy self-balancing converter valve of the offshore converter station is put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power; S4. In response to the fault signal sent by the onshore converter station, based on the allocation ratio, the unloading circuit is called to consume the surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power.

2. The fault ride-through method of a flexible direct current transmission system according to claim 1, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes: Setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to the fault type judgment method; The fault type determination method is: when the flexible DC power transmission system fails, the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, is a coefficient, determined by the type of fault detected, It is the actual power of the offshore wind power flexible DC transmission system before the fault.

3. The fault ride-through method of a flexible DC transmission system according to claim 1, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes: According to the surplus power ratio allocation method, the allocation ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve is set; The surplus power ratio allocation method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, is the coefficient.

4. The fault ride-through method of a flexible DC transmission system according to claim 1, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve comprises: According to the surplus power fixed reduction method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; The surplus power fixed reduction method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, It is the power consumption setting value of the energy self-balancing converter valve.

5. A fault ride-through system for a flexible DC transmission system, characterized in that: The flexible direct current power transmission system comprises: an offshore converter station and an onshore converter station each equipped with an energy self-balancing converter valve, and a wind power converter provided with a load shedding circuit; The system includes: a setting unit, used to set a starting constant value when the energy self-balancing converter valve is started to consume the remaining surplus power, and a quitting constant value when the energy self-balancing converter valve is quit to consume the remaining surplus power, and determine a distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; a detection unit, configured to detect the flexible DC power transmission system through the offshore converter station and the onshore converter station respectively, triggering a first control unit when the offshore converter station detects a fault signal, and triggering a second control unit when the onshore converter station detects a fault signal; A first control unit is used to call the unloading circuit to consume surplus power based on the allocation ratio, and at the same time, to make the energy self-balancing converter valve of the offshore converter station be put into operation or withdrawn according to the input setting value and the withdrawal setting value to consume the remaining surplus power; The second control unit is used to respond to the fault signal sent by the onshore converter station and, based on the allocation ratio, call the unloading circuit to consume surplus power. At the same time, the energy self-balancing converter valves of the offshore converter station and the onshore converter station are put into operation or exited according to the input constant value and the exit constant value to consume the remaining surplus power.

6. The fault ride-through system of the flexible direct current transmission system according to claim 5, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve comprises: Setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to the fault type judgment method; The fault type determination method is: when the flexible DC power transmission system fails, the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, is a coefficient, determined by the type of fault detected, It is the actual power of the offshore wind power flexible DC transmission system before the fault.

7. The fault ride-through system of the flexible direct current transmission system according to claim 5, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve comprises: According to the surplus power ratio allocation method, the allocation ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve is set; The surplus power ratio allocation method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, is the coefficient.

8. The fault ride-through system of the flexible direct current transmission system according to claim 5, characterized in that: The determining of the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve comprises: According to the surplus power fixed reduction method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; The surplus power fixed reduction method is: real-time calculation of the surplus power caused by the failure of the flexible DC transmission system , the surplus power consumed by calling the unloading circuit is: The surplus power consumed by the energy self-balancing converter valve is: surplus power minus ; in, It is the power consumption setting value of the energy self-balancing converter valve.

9. A fault ride-through device for a flexible DC transmission system, characterized in that: The device comprises a processor and a memory: The memory is used to store program codes and transmit the program codes to the processor; The processor is used to execute the fault ride-through method of the flexible direct current transmission system according to any one of claims 1 to 4 according to the instructions in the program code.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium is used to store program codes, and the program codes are used to execute the fault ride-through method of the flexible direct current transmission system according to any one of claims 1 to 4.

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