A fault ride-through method and related device for a flexible direct current transmission system

Abstract

The present invention discloses a fault ride-through method and related devices for a flexible direct current (DC) transmission system. The method comprises: detecting the flexible DC transmission system; when an offshore converter station detects a fault signal, calling an unloading circuit to consume surplus power, and simultaneously causing the energy self-balancing converter valve of the offshore converter station to be put into operation or withdrawn according to an input fixed value and an exit fixed value to consume the remaining surplus power; when an onshore converter station detects a fault signal, responding to the fault signal sent by the onshore converter station, calling an unloading circuit to consume surplus power, and simultaneously causing the energy self-balancing converter valves of the offshore converter station and the onshore converter station to be put into operation or withdrawn according to an input fixed value and an exit fixed value to consume the remaining surplus power. The method of the present invention does not require the configuration of a centralized DC energy consumption device. By consuming surplus power through the cooperation of the energy self-balancing converter valve and the unloading circuit, it can cope with both AC and DC faults, and can significantly reduce the project cost.

Description

Technical Field

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

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

[0003] To ensure safe and reliable system operation, the offshore wind power grid-connected flexible direct current (FDC) system should have AC fault ride-through capability. In this project, a centralized DC energy consumption system is generally configured on the DC side of the receiving onshore converter station. Large-scale deep-sea wind power bases that directly transmit power to the load center should adopt a hybrid cable-overhead line solution. Submarine cables are collected on land and sent to the load center via overhead lines. This can significantly reduce project costs compared to traditional submarine cable transmission solutions. However, DC overhead lines are prone to short-circuit faults, so in addition to AC fault ride-through capability, the flexible direct current transmission system also needs to have DC fault ride-through capability. However, centralized DC energy consumption devices have a complex structure, involve a large number of controllable power devices, are expensive, require additional space, and can only handle AC grid faults, not 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 existing technology requires the consumption of surplus power through centralized direct current energy consumption devices, 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, a 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, each of which is equipped with an energy self-balancing converter valve, and a wind power converter provided with a load shedding circuit;

[0006] Methods include:

[0007] S1. Setting a fixed value for the energy self-balancing converter valve when it is put into operation to consume the remaining surplus power, and a fixed value for the energy self-balancing converter valve when it is stopped from consuming the remaining surplus power, and determining a distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve;

[0008] S2. Detecting the flexible HVDC system through the offshore converter station and the onshore converter station respectively. When the offshore converter station detects a fault signal, execute step S3; and when the onshore converter station detects a fault signal, execute step S4.

[0009] S3. Based on the allocation ratio, the unloading circuit is activated to consume the surplus power. Simultaneously, the energy self-balancing converter valve of the offshore converter station is activated or deactivated according to the activation setting value and the deactivation 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 be put into operation 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, determining a distribution ratio of surplus power consumed between the unloading circuit and the energy self-balancing converter valve includes:

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

[0013] The fault type determination method is as follows: 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 valve is: surplus power minus ;

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

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

[0016] According to the surplus power ratio distribution method, setting the distribution 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 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 valve is: surplus power minus ;

[0018] in, is the coefficient.

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

[0020] According to the surplus power fixed deduction 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 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 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 for a flexible direct current (HVDC) transmission system, the flexible direct current (HVDC) 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, configured to set a start-up constant value when the energy self-balancing converter valve is started to consume the remaining surplus power, and a stop-down constant value when the energy self-balancing converter valve is stopped to consume the remaining surplus power, and determine a distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve;

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

[0027] a first control unit, configured to activate the unloading circuit based on the allocation ratio to consume surplus power, and simultaneously activate or deactivate the energy self-balancing converter valve of the offshore converter station according to the activation setting value and the deactivation 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 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 exited according to the input constant value and the exit constant value to consume the remaining surplus power.

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

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

[0031] The fault type determination method is as follows: 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 valve is: surplus power minus ;

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

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

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

[0035] 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 valve is: surplus power minus ;

[0036] in, is the coefficient.

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

[0038] According to the surplus power fixed deduction 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 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 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 configured to execute the steps of the fault ride-through method for a 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.

[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 transmission system. This method eliminates the need for centralized DC energy dissipation devices. Instead, it utilizes self-balancing converter valves and unloading circuits to dissipate excess power, effectively addressing both AC and DC faults and significantly reducing project costs. This method addresses the existing problem of requiring centralized DC energy dissipation devices to dissipate excess power, resulting in high construction costs and limited ability to address AC grid faults, while failing to 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 following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 any creative work.

[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 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 HVDC 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 making creative work are within the scope of protection of the present invention.

[0053] See also Figure 1 , an embodiment of the present invention provides a fault ride-through method for a flexible direct current transmission system, wherein the flexible direct current transmission system includes: an offshore converter station and an onshore converter station, each of which is equipped with an energy self-balancing converter valve, and a wind power converter provided with a unloading 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 are connected to the offshore converter station, which is connected to the onshore converter station. The wind turbine converter is equipped with a load shedding circuit. Both the offshore and onshore converter stations use self-balancing HVDC flexible converter valves and are equipped with self-balancing branches. Both the load shedding circuit and the self-balancing branch can dissipate excess power caused by faults. The offshore converter station is connected to the onshore converter station via a HVDC submarine cable and overhead lines.

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

[0056] Step 101: Set an input constant value when the energy self-balancing converter valve is put into use to consume the remaining surplus power, and set an exit constant value when the energy self-balancing converter valve is stopped from consuming 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.

[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 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 activated or deactivated according to the activation setting and the deactivation setting to consume the remaining surplus power.

[0060] It is understandable that if Figure 2 and 3 As shown in the figure, 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 valve at the sending end is set according to the set input value. , exit constant 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 activated or deactivated according to the activation setting and the deactivation setting 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 set according to the set input values. , exit constant value Autonomously consumes the remaining surplus power.

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

[0064] 1) Fault type judgment method: When a fault occurs in the flexible DC transmission system, the surplus power consumed by 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, 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 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 ;

[0070] in, The power consumption setting value of the energy self-balancing converter valve 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. This method 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 an unloading circuit, it can cope with direct current line faults and receiving-end AC system faults, greatly reducing costs.

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

[0073] See also Figure 4 In an embodiment of the present invention, a fault ride-through system of a flexible direct current transmission system is provided. The flexible direct current transmission system includes: an offshore converter station and an onshore converter station, each of which is equipped with an energy self-balancing converter valve, 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 from consuming the remaining surplus power, and to 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. When the offshore converter station detects a fault signal, the first control unit 203 is triggered, and when the onshore converter station detects a fault signal, the second control unit 204 is triggered.

[0077] The first control unit 203 is used to call the unloading circuit to consume the 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, it enables the energy self-balancing converter valves of the offshore converter station and the onshore 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.

[0079] Furthermore, an embodiment of the present invention provides a fault ride-through device for a flexible direct current transmission system, the device including 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 configured to execute the steps of the fault ride-through method for a 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 code, and the program code is 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 will 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 merely illustrative. For example, the division of units is merely a logical function division. In actual implementation, there may be other division methods, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed can be through some interface, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

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

[0086] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing unit, each unit may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units.

[0087] If the integrated unit is implemented as 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, or the portion that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the various embodiments of the method of the present invention. The aforementioned storage medium includes various media that can store program code, such as USB flash drives, mobile hard drives, read-only memories (ROMs), random access memories (RAMs), magnetic disks, or optical disks.

[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 they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. 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 various 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 transmission system includes: an offshore converter station and an onshore converter station, each equipped with an energy self-balancing converter valve, and a wind power converter equipped with a load shedding circuit; Methods include: S1. Setting a fixed value for the energy self-balancing converter valve when it is put into operation to consume the remaining surplus power, and a fixed value for the energy self-balancing converter valve when it is stopped from consuming the remaining surplus power, and determining a distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve; S2. Detecting the flexible HVDC system through the offshore converter station and the onshore converter station respectively. When the offshore converter station detects a fault signal, execute step S3; and when the onshore converter station detects a fault signal, execute step S4. S3. Based on the allocation ratio, the unloading circuit is activated to consume the surplus power. Simultaneously, the energy self-balancing converter valve of the offshore converter station is activated or deactivated according to the activation setting value and the deactivation 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 be put into operation 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 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: Setting a distribution ratio of surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to a fault type judgment method; The fault type determination method is as follows: 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 valve is: surplus power minus ; in, is a coefficient determined by the type of fault detected, 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 distribution method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; 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 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 includes: According to the surplus power fixed deduction 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 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 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 direct current transmission system, characterized in that: The flexible direct current transmission system includes: an offshore converter station and an onshore converter station, each equipped with an energy self-balancing converter valve, and a wind power converter equipped with a load shedding circuit; The system includes: a setting unit, configured to set a start-up constant value when the energy self-balancing converter valve is started to consume the remaining surplus power, and a stop-down constant value when the energy self-balancing converter valve is stopped to consume the remaining surplus power, and determine a distribution ratio of the surplus power consumption between the unloading circuit and the energy self-balancing converter valve; a detection unit, configured to detect the flexible DC transmission system through the offshore converter station and the onshore converter station, respectively, and trigger a first control unit when the offshore converter station detects a fault signal, and trigger a second control unit when the onshore converter station detects a fault signal; a first control unit, configured to activate the unloading circuit based on the allocation ratio to consume surplus power, and simultaneously activate or deactivate the energy self-balancing converter valve of the offshore converter station according to the activation setting value and the deactivation 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 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 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 DC 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 includes: Setting a distribution ratio of surplus power consumed between the unloading circuit and the energy self-balancing converter valve according to a fault type judgment method; The fault type determination method is as follows: 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 valve is: surplus power minus ; in, is a coefficient determined by the type of fault detected, 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 DC 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 includes: According to the surplus power ratio distribution method, setting the distribution ratio of the surplus power consumed between the unloading circuit and the energy self-balancing converter valve; 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 valve is: surplus power minus ; in, is the coefficient.

8. The fault ride-through system of the flexible DC 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 includes: According to the surplus power fixed deduction 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 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 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 includes a processor and a memory: The memory is used to store program code and transmit the program code to the processor; The processor is configured to execute the fault ride-through method for a flexible direct current transmission system according to any one of claims 1 to 4 according to instructions in the program code.

10. A computer-readable storage medium, characterized in that 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 according to any one of claims 1 to 4.

Images