Direct current line fault processing method, module, system and electronic device

Abstract

This application discloses a DC line fault handling method, module, system, and electronic device. Upon detecting a DC line fault, in response to the fault signal, it controls a first converter station to reduce its corresponding first DC current value and controls a second converter station to reduce its corresponding second DC current value. Then, it controls the first converter station to be locked based on the first DC current value and the second converter station to be restarted based on the second DC current value. Finally, if the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than a preset voltage, it unlocks the first converter station and controls it to resume operation. This application can reliably control the DC line to restart during a fault, ensuring the reliability of power transmission and improving the safety and stability of the DC transmission system.

Description

Technical Field

[0001] This application relates to the field of flexible DC transmission technology, specifically to a DC line fault handling method, module, system, and electronic equipment. Background Technology

[0002] Flexible DC transmission technology can autonomously adjust parameters such as voltage, current, and frequency according to the load conditions of the power system to adapt to the power transmission needs under different load conditions. Employing flexible DC transmission technology enables long-distance, high-capacity power transmission across different AC power grids, solving the problem of uneven distribution of energy resources and load centers.

[0003] External factors such as harsh natural environments and internal factors such as equipment aging can both lead to faults in DC transmission lines within flexible DC transmission systems during operation. Traditional DC line fault control methods involve controlling the voltage at both converter stations to reduce the DC line current to zero after receiving a line protection activation, and then restarting the DC line after deionization is complete, based on inter-station communication results. However, traditional DC line fault control methods require mutual information exchange between the two converter stations, which is impossible in the event of inter-station communication failure. This results in low reliability of current DC line fault restart methods, impacting the safety and stability of flexible DC transmission systems. Summary of the Invention

[0004] This application provides a DC line fault handling method, module, system, and electronic device, which can restart the DC transmission system when inter-station communication fails, thereby improving the safety and stability of the flexible DC transmission system.

[0005] To achieve the above objectives, according to a first aspect of this application, a DC line fault handling method is proposed, applied to a DC transmission system, the DC transmission system including a DC line, and a first converter station and a second converter station connected to the DC line: the fault handling method includes:

[0006] In response to a fault signal in the DC line, the first converter station is controlled to reduce the first DC current value corresponding to the first converter station, and the second converter station is controlled to reduce the second DC current value corresponding to the second converter station.

[0007] The first converter station is locked down based on the first DC current value, and the second converter station is restarted based on the second DC current value.

[0008] When the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than the preset voltage, the first converter station is unlocked and controlled to resume operation.

[0009] Optionally, controlling the blocking of the first converter station based on the first DC current value includes:

[0010] When the first DC current value drops to the preset current, the first converter station is locked out.

[0011] Optionally, the first converter station includes a converter, and the DC line fault handling method also includes:

[0012] By controlling the switching state of the power modules in the converter, the interlocking control of the first converter station can be achieved.

[0013] Optionally, the second converter station is restarted based on the second DC current value, including:

[0014] If the second DC current value decreases to the preset current, the current state is maintained;

[0015] After the second DC current value is maintained at its current state for a first time, the second converter station is controlled to increase the corresponding second DC voltage value to restart the second converter station; wherein, the first time is greater than the fault recovery time of the DC line.

[0016] Optionally, controlling the first converter station to resume operation includes:

[0017] Control the first converter station to increase its corresponding output power so that the first converter station can resume operation when the output power is increased to the target power.

[0018] Optionally, the DC line fault handling method also includes:

[0019] In response to a fault signal in the DC line, the current power of the DC line is obtained and used as the target power.

[0020] In a second aspect of this application, a DC line fault handling module is proposed, applied to a DC transmission system, the DC transmission system including a DC line, and a first converter station and a second converter station connected to the DC line: the DC line fault handling module includes:

[0021] The current control module is configured to: in response to a fault signal of the DC line, control the first converter station to reduce the first DC current value corresponding to the first converter station, and control the second converter station to reduce the second DC current value corresponding to the second converter station.

[0022] The first restart module is configured to: control the blocking of the first converter station based on the first DC current value, and control the restart of the second converter station based on the second DC current value;

[0023] The second restart module is configured to: unlock the first converter station and control the first converter station to resume operation when the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than the preset voltage.

[0024] In a third aspect of this application, a DC transmission system is proposed, comprising:

[0025] The first converter station is used to acquire the first AC signal and convert the first AC signal into a first DC signal;

[0026] A DC line, connected to the first converter station, is used to transmit the first DC signal to obtain the second DC signal;

[0027] The second converter station is connected to the DC line and is used to convert the second DC signal into a second AC signal and output the second AC signal.

[0028] In the event of a DC line fault in a DC transmission system, the DC line fault handling method described in the first aspect above shall be adopted.

[0029] Optionally, the first converter station and / or the second converter station includes:

[0030] Modular multilevel converters consist of multiple power modules, which can be half-bridge or full-bridge modules.

[0031] In a fourth aspect of this application, an electronic device is proposed, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the DC line fault handling method provided in the first aspect above.

[0032] In summary, the DC line fault handling method, module, system, and electronic device of this application are applied to a DC transmission system, which includes a DC line and a first converter station and a second converter station connected to the DC line. In the case of a detected fault in the DC line, in response to the fault signal of the DC line, the first converter station is controlled to reduce its corresponding first DC current value, and the second converter station is controlled to reduce its corresponding second DC current value. Then, the first converter station is locked based on the first DC current value, and the second converter station is restarted based on the second DC current value. Upon restarting the second converter station and if the first DC voltage value corresponding to the first converter station is greater than a preset voltage, the first converter station is unlocked and its operation is restored.

[0033] The DC line fault handling method of this application optimizes the DC line fault handling method without adjusting the hardware structure of the DC transmission system, and can still achieve fault restart operation of the DC transmission system in the event of communication failure. The DC line fault handling method of this application embodiment can reliably control the DC line to restart during DC line faults, ensuring the reliability of power transmission and improving the safety and stability of the DC transmission system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a DC power transmission system provided in an embodiment of this application;

[0035] Figure 2 This is a schematic diagram of the topology of a converter provided in an embodiment of this application;

[0036] Figure 3 This is a flowchart of a DC line fault handling method provided in an embodiment of this application;

[0037] Figure 4 This is a flowchart of another DC line fault handling method provided in the embodiments of this application;

[0038] Figure 5 This is a schematic diagram of a DC line fault handling module provided in an embodiment of this application;

[0039] Figure 6 This is a structural diagram of an electronic device provided in an embodiment of this application. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] Furthermore, in the embodiments of this application, "multiple" refers to two or more. In the embodiments of this application, "first" and "second," etc., are used to distinguish different technical features and do not indicate any order, quantity, or importance. In the embodiments of this application, "comprising" and "including" indicate the presence of the described feature, whole, step, operation, element, and / or component, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or sets thereof.

[0042] The various embodiments provided in this application are similar, and features in different embodiments can be combined with each other.

[0043] The order in which the following embodiments are described is not intended to limit the preferred order of the embodiments.

[0044] Flexible direct current (DC) transmission systems are systems capable of transmitting large amounts of electricity over long distances. Flexible DC transmission technology can bridge different AC power grids, solving the problem of uneven distribution of energy resources and load centers. However, various faults are inevitable during DC transmission. From an external perspective, harsh natural environments are a common cause of faults. For example, lightning strikes can instantly generate overvoltages, breaking down the insulation layer of the line and causing short-circuit faults; extreme weather such as strong winds, heavy rain, and blizzards can damage towers, insulators, and other equipment, causing line interruptions. Furthermore, birds nesting on towers or foreign objects dangling from conductors can also cause transmission line faults, affecting power transmission. From an internal perspective, equipment aging, deterioration of insulation performance, and manufacturing defects can all lead to DC line faults.

[0045] DC line faults can lead to prolonged power outages, impacting the reliability and stability of power supply and causing significant socio-economic losses. For users with extremely high power supply reliability requirements, such as hospitals, data centers, and financial institutions, extended power outages can have severe consequences. Therefore, to quickly restore power and minimize the impact of faults on the power system and users, timely fault handling is necessary when DC line faults occur.

[0046] To address the aforementioned issues, this application provides a DC line fault handling method that can reliably and stably handle faults when they occur in a DC line, ensuring reliable power transmission in the DC line.

[0047] First, a brief introduction to the DC power transmission system of this application embodiment is given. A DC power transmission system is a power transmission system that transmits DC signals on transmission lines to achieve power transmission. The DC power transmission system includes a first converter station and a second converter station, as well as DC lines connected to the first and second converter stations respectively. When the power signal is transmitted in the DC power transmission system, the AC signal from the AC power source is first converted from AC to DC at the first converter station to obtain a first DC signal. This first DC signal is then transmitted through the DC lines. The DC signal output from the DC lines is defined as a second DC signal. The transmitted second DC signal is then converted from AC to DC at the second converter station to obtain a second AC signal, which is then transmitted to a second AC power source or load.

[0048] Figure 1 This is a flowchart of a DC line fault handling method proposed in an embodiment of this application. The DC line fault handling method proposed in this application is applied to a DC transmission system, which includes a DC line and a first converter station and a second converter station connected to the DC line. Figure 1 As shown, the DC line fault handling method of this application embodiment includes the following steps S110 to S130.

[0049] In step S110, in response to the fault signal of the DC line, the first converter station is controlled to reduce the first DC current value corresponding to the first converter station, and the second converter station is controlled to reduce the second DC current value corresponding to the second converter station.

[0050] Fault signals are signals issued by a DC transmission system when a fault is detected in a DC line. For example, a DC line fault signal can indicate anomalies such as overload, short circuit, open circuit, or insulation failure. Upon detecting a DC line fault signal, the DC transmission system must promptly handle the fault.

[0051] In this embodiment, after receiving a fault signal from the DC line, the first converter station and the second converter station are controlled to reduce the current value on the DC side, so as to reduce the safety hazards caused by the DC line fault by reducing the current value on the DC line.

[0052] Specifically, this step involves reducing the first and second DC current values ​​with the goal of reducing the DC current value to zero through current control. The reduction of DC current includes controlling the first converter station to reduce its corresponding first DC current value, and controlling the second converter station to reduce its corresponding second DC current value.

[0053] Step S120: Control the first converter station to be locked according to the first DC current value, and control the second converter station to be restarted according to the second DC current value.

[0054] As the DC current corresponding to the first converter station and the second converter station decreases, the first converter station is controlled according to the first DC current value. For example, when the first DC current value decreases for a period of time, or when the first DC current value decreases to a certain threshold, the first converter station is locked to maintain the state of the first converter station and ensure its stability and reliability.

[0055] The second converter station is restarted based on the second DC current value. When a fault occurs in the DC line, the second converter station is restarted first, which can avoid overvoltage and overcurrent in the DC transmission system and reduce the impact on the AC system, thereby improving the reliability of the DC transmission system.

[0056] Step S130: When the second converter station is restarted and the first DC voltage value corresponding to the first converter station is greater than the preset voltage, the first converter station is unlocked and the first converter station is controlled to resume operation.

[0057] The second converter station and the first converter station are connected via a DC line, therefore the DC voltage corresponding to the second converter station is equal to that of the first converter station. After the second converter station restarts, its corresponding DC voltage rises, and the voltage corresponding to the first converter station rises synchronously. When the first DC voltage value corresponding to the first converter station is detected to be greater than a preset voltage, the first converter station is unlocked and controlled to return to its operating state before the DC line fault. It can be understood that if a fault still exists in the DC line when the DC voltage corresponding to the second converter station rises, the second converter station will be directly blocked and tripped.

[0058] The DC line fault handling method of this application optimizes the DC transmission system fault handling method without adjusting the hardware structure of the DC transmission system, and can still realize the fault restart operation of the DC transmission system in the event of a communication failure. The DC line fault handling method of this application can reliably control the DC line to restart during a DC line fault, ensuring the reliability of power transmission and improving the safety and stability of the DC transmission system.

[0059] In some embodiments, controlling the blocking of the first converter station based on the first DC current value includes: blocking the first converter station when the first DC current value drops to a preset current.

[0060] The initial DC current value is related to operational anomalies such as load fluctuations and short-circuit faults. When the initial DC current value drops to a preset current, the first converter station is blocked to protect it. In some implementations, the preset current can be determined using operating data such as the rated current of the first converter station and the system's safety margin.

[0061] In some specific embodiments, the first converter station includes a converter, and the DC line fault handling method further includes: controlling the switching state of the power module in the converter to achieve interlocking control of the first converter station.

[0062] The first converter station achieves power conversion through converters, which can be used for AC-to-DC conversion or DC-to-AC conversion. Each converter includes several power modules. By controlling the switching states of these power modules, current can be controlled, thus achieving power conversion.

[0063] When the power modules of the corresponding converter at the first converter station are turned off, the first converter station can be considered locked, and it cannot perform power conversion. When the power modules of the corresponding converter at the first converter station are turned on according to a certain pattern, the first converter station can be considered unlocked, and it can resume power conversion.

[0064] In some embodiments, controlling the restart of the second converter station based on the second DC current value includes: maintaining the current state when the second DC current value decreases to a preset current; and controlling the second converter station to increase the corresponding second DC voltage value after the second DC current value maintains the current state for a first time, so as to restart the second converter station; wherein the first time is greater than the fault recovery time of the DC line.

[0065] Before restarting the second converter station, the corresponding second DC current value of the second converter station is reduced. In some implementations, the reduction rate of the second DC current value per unit time can be the same as or different from the reduction rate of the first DC current value. For ease of control, the rate of change of the first and second DC current values ​​is generally controlled to be the same.

[0066] The fault recovery time of a DC line refers to the time from when the fault current is interrupted to when the line insulation performance recovers to the point where it can withstand normal voltage after a fault occurs. The fault recovery time of a DC circuit can also be called the deionization time. When a fault occurs in a DC transmission line, after the fault current is interrupted, the electric arc in the line will extinguish, the charged particles will gradually recombine, and the dielectric strength of the air will gradually recover. The deionization time represents the time required for the corresponding recovery process.

[0067] For example, the preset current is typically zero current, or a current close to zero. When the second DC current value drops to the preset current, it remains in a zero-current state for a period of time, allowing the DC line to recover from the fault state. After the second DC current value corresponding to the second converter station maintains its current state for a first time, the second converter station is controlled to increase its corresponding second DC voltage value to restart the second converter station. Specifically, when increasing the second DC voltage value, the rated voltage corresponding to the second converter station is obtained, and the increase in the second DC voltage value stops once it reaches the rated voltage.

[0068] In some other embodiments, controlling the first converter station to resume operation includes: controlling the first converter station to increase the corresponding output power of the first converter station, so that the first converter station resumes operation when the output power is increased to the target power.

[0069] The first converter station, as the power transmitting end in the power transmission system, is used to control the power level of the DC lines. When the first converter station restarts, the corresponding output power of the first converter station is increased to achieve the restart.

[0070] In some specific embodiments, the DC line fault handling method further includes: in response to a fault signal of the DC line, obtaining the current power of the DC line and using the current power as the target power.

[0071] The current power of a DC line represents the power transmitted on the DC line during normal operation of the DC transmission system before a fault occurs. In the event of a DC line fault, the first converter station responds to the fault signal of the DC line, acquires the current power of the DC line, and uses the acquired current power as the target power. When the first converter station restarts, the corresponding output power of the first converter station is increased to the target power.

[0072] In some specific embodiments, a DC line fault handling method is proposed, such as... Figure 2 As shown, the DC line fault handling method of this application embodiment includes the following steps S210 to S250.

[0073] In step S210, in response to a fault signal in the DC line, the current power of the DC line is obtained and used as the target power.

[0074] In step S220, the first converter station is controlled to reduce the first DC current value corresponding to the first converter station, and the second converter station is controlled to reduce the second DC current value corresponding to the second converter station.

[0075] Step S230: When the first DC current value drops to the preset current, the first converter station is locked.

[0076] For example, the first converter station can be locked out by disconnecting the power module in the converter.

[0077] Step S240: When the second DC current value decreases to the preset current, maintain the current state; after the second DC current value maintains the current state for a first time, control the second converter station to increase the corresponding second DC voltage value of the second converter station so as to restart the second converter station; wherein, the first time is greater than the fault recovery time of the DC line.

[0078] Step S250: Control the first converter station to increase the corresponding output power of the first converter station so that the first converter station can resume operation when the output power is increased to the target power.

[0079] It is understood that the DC line fault handling method of this application embodiment has no limitation on the number of converter stations and can be applied to flexible DC transmission systems with two or even more ends, thereby improving the stability and reliability of the DC transmission system.

[0080] This application's embodiments optimize the DC line fault handling method based on existing hardware structures, making it highly practical. Using the DC circuit fault handling method described above, even under complex conditions such as inter-station communication failures, the safety and stability of DC line fault restart can still be effectively guaranteed, ensuring reliable power transmission and providing solid technical support for the safe, stable, and efficient operation of flexible DC transmission systems.

[0081] Based on the same inventive concept, this application also provides a DC line fault handling device for implementing the DC line fault handling method described above. The solution provided by this device is similar to the solution described in the above method; therefore, the specific limitations in one or more DC line fault handling device embodiments provided below can be found in the limitations of the DC line fault handling method described above, and will not be repeated here.

[0082] In one exemplary embodiment, such as Figure 3 As shown, a DC line fault handling device is provided, including: a current control module 310, a first restart module 320, and a second restart module 330. Wherein:

[0083] The current control module 310 is configured to: in response to a fault signal of the DC line, control the first converter station to reduce the first DC current value corresponding to the first converter station, and control the second converter station to reduce the second DC current value corresponding to the second converter station.

[0084] The first restart module 320 is configured to: control the blocking of the first converter station according to the first DC current value, and control the restart of the second converter station according to the second DC current value;

[0085] The second restart module 330 is configured to: unlock the first converter station and control the first converter station to resume operation when the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than the preset voltage.

[0086] The modules in the DC line fault handling device provided in this application can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device in hardware form, or stored in the memory of a computer device in software form, so that the processor can call and execute the operations corresponding to each module.

[0087] Figure 4 This is a schematic diagram of the structure of a DC power transmission system provided in an embodiment of this application. Figure 4 As shown, the DC transmission system 100 includes a first converter station 110, a DC line 120, and a second converter station 130. The first converter station 110 acquires a first AC signal and converts it into a first DC signal. The DC line 120 is connected to the first converter station 110 and transmits the first DC signal to obtain a second DC signal. The second converter station 130 is connected to the DC line 120 and converts the second DC signal into a second AC signal, then outputs the second AC signal.

[0088] like Figure 4As shown, the first converter station 110 is a rectifier station and is the power transmitting end in the DC transmission system, used to control the power level of the DC line. The first converter station 110 is connected to the first AC power source, converts the first AC signal corresponding to the first AC power source into a first DC signal, and transmits the first DC signal to the second converter station 130 through the DC line 120.

[0089] The second converter station 130 is an inverter station, serving as the power receiving end in the DC transmission system, used to control the voltage level of the DC line. The second converter station 130 is connected to the DC line 120, converting the second DC signal obtained after the first DC signal is transmitted through the DC line 120 into a second AC signal, and outputting the second AC signal to the second AC power source. In some implementations, the second converter station 130 can also output the second AC signal to a local load.

[0090] The first converter station 110 and the second converter station 130 are power conversion devices with identical structures. Please continue reading. Figure 1 Taking the first converter station 110 as an example, the first converter station 110 includes an AC switch, a converter transformer, a converter, and a DC switch connected in sequence. The AC switch connects the second AC side of the converter station to the AC power grid, and the DC switch connects the DC side of the converter station to the DC line. The DC side of the converter station and the DC line can also be connected by a switch.

[0091] It is understood that the AC switch in the embodiment of this application is always closed in the DC line fault handling method, that is, even when the first converter station is locked and the power module in the converter is turned off, the AC switch remains closed.

[0092] In some embodiments, the first converter station 110 and / or the second converter station 130 include a modular multilevel converter (MMC). Figure 5 As shown, the modular multilevel converter includes multiple power modules, which can be half-bridge or full-bridge modules.

[0093] A power module is a sub-module that makes up an MMC. A sub-module typically contains one capacitor and two power semiconductors (such as IGBTs or MOSFETs). Figure 5 As shown, the MMC includes six arms, corresponding to three-phase electrical signals. Each phase includes an upper arm and a lower arm, and each arm is composed of multiple cascaded power modules.

[0094] The power module can be either a half-bridge sub-module or a full-bridge sub-module. For example... Figure 5 As shown, each full-bridge submodule consists of four IGBT turn-off devices and capacitors, and each half-bridge submodule consists of two IGBT turn-off devices and capacitors.

[0095] In some exemplary embodiments, such as Figure 6 As shown, an electronic device is provided, including a memory and a processor. The memory stores a computer program, and the processor executes the computer program to implement the steps in the above-described method embodiments.

[0096] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0097] The above provides a detailed description of a DC line fault handling method, module, system, and electronic device provided in the embodiments of this application. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of this application. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A method for handling DC line faults, characterized in that, An application in a direct current (DC) transmission system, the DC transmission system comprising a DC line and a first converter station and a second converter station connected to the DC line: the method includes: In response to a fault signal in the DC line, the first converter station is controlled to reduce the first DC current value corresponding to the first converter station, and the second converter station is controlled to reduce the second DC current value corresponding to the second converter station. The first converter station is locked based on the first DC current value, and the second converter station is restarted based on the second DC current value. When the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than the preset voltage, the first converter station is unlocked and controlled to resume operation.

2. The method according to claim 1, characterized in that, The step of controlling the blocking of the first converter station based on the first DC current value includes: When the first DC current value drops to a preset current, the first converter station is locked out.

3. The method according to claim 2, characterized in that, The first converter station includes a converter, and the method further includes: By controlling the switching state of the power modules in the converter, the interlocking control of the first converter station can be achieved.

4. The method according to claim 2, characterized in that, The step of controlling the restart of the second converter station based on the second DC current value includes: If the second DC current value decreases to the preset current, the current state is maintained; After the second DC current value is maintained at its current state for a first time, the second converter station is controlled to increase the corresponding second DC voltage value to restart the second converter station; wherein, the first time is greater than the fault recovery time of the DC line.

5. The method according to claim 1, characterized in that, The control of the first converter station to resume operation includes: Control the first converter station to increase the corresponding output power of the first converter station, so that the first converter station can resume operation when the output power is increased to the target power.

6. The method according to claim 5, characterized in that, The method further includes: In response to a fault signal in the DC line, the current power of the DC line is obtained and used as the target power.

7. A DC line fault handling module, characterized in that, An application in a direct current (DC) transmission system, the DC transmission system comprising a DC line and a first converter station and a second converter station connected to the DC line: the module comprises: The current control module is configured to: in response to a fault signal of the DC line, control the first converter station to reduce the first DC current value corresponding to the first converter station, and control the second converter station to reduce the second DC current value corresponding to the second converter station. The first restart module is configured to: control the blocking of the first converter station according to the first DC current value, and control the restart of the second converter station according to the second DC current value; The second restart module is configured to: when the second converter station restarts and the first DC voltage value corresponding to the first converter station is greater than a preset voltage, unlock the first converter station and control the first converter station to resume operation.

8. A DC transmission system, characterized in that, include: The first converter station is used to acquire the first AC signal and convert the first AC signal into a first DC signal; A DC line, connected to the first converter station, is used to transmit the first DC signal to obtain a second DC signal; The second converter station is connected to the DC line and is used to convert the second DC signal into a second AC signal and output the second AC signal. In the event of a DC line fault, the DC transmission system employs the DC line fault handling method as described in any one of claims 1 to 6.

9. The system according to claim 8, characterized in that, The first converter station and / or the second converter station include: A modular multilevel converter, comprising multiple power modules, wherein the power modules are half-bridge modules or full-bridge modules.

10. An electronic device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 6.

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