Direct current system restarting method and device based on extra-high voltage converter station

Abstract

The invention provides a direct current system restarting method and device based on an extra-high voltage converter station, and the method comprises the steps: receiving a line restarting instruction of a direct current system through the extra-high voltage converter station under the condition that a pole line of the direct current system breaks down; performing pole isolation on a low-end valve group in the extra-high voltage converter station in response to the line restart instruction; after the low-end valve group is subjected to pole isolation, a high-end valve group in the extra-high voltage converter station is restarted, and a sound valve group in the extra-high voltage converter station is unlocked and restarted; unlocking and restarting the sound valve group in the extra-high voltage converter station, and reestablishing pole connection; wherein in the process of pole isolation and pole connection, the pole bus isolation switch and the pole neutral bus isolation switch in the direct current system are switched on and switched off. Therefore, the risk of restart failure is reduced, and the restart success rate and the restart efficiency are improved.

Description

Technical Field

[0001] The present application relates to the field of electric power, and in particular to a method and device for restarting a direct current system based on an ultra-high voltage converter station. Background Art

[0002] With the continuous expansion of the scale of power systems and the improvement of the requirements for power transmission efficiency, UHV DC transmission technology has been widely used due to its advantages of long transmission distance, large capacity and low loss. As the core component of the DC transmission system, the configuration and control strategy of the UHV converter station are crucial to the stable operation of the system. Among them, the UHV converter station includes a bipolar structure, and each pole contains four valve groups, namely two high-end valve groups and two low-end valve groups. Corresponding to the bipolar four-valve structure of the UHV converter station, the control system of the UHV converter station includes system control, bipolar control pole control and valve group control. The restart logic function is an important protection measure in the UHV converter station, which is mainly used to handle the pole line fault of the DC system. It mainly includes full-voltage restart logic, step-down restart logic and pole locking logic.

[0003] In some scenarios, in order to transmit as much DC power as possible, the UHV converter station enables the REBOOT function. The REBOOT function includes three parts: fault isolation, sequential control steps, and equipment operation. Among them, fault isolation identifies and isolates the faulty valve group and selects the non-faulty valve group for restart. The sequential control step gradually unlocks the healthy valve group and reestablishes the pole connection. The equipment operation involves opening and closing the pole bus disconnector, the pole neutral bus disconnector, the large pole return disconnector, and the pole metal return disconnector. In the process of fault isolation and sequential control steps to unlock the healthy valve group, it is necessary to open and close the pole bus disconnector, the pole neutral bus NBS circuit breaker, the large pole return disconnector, and the pole metal return disconnector. Too many equipment actions result in a long restart time and low restart efficiency. In addition, due to the large number of equipment that needs to be opened and closed, if any of the equipment is not opened and closed in place, there is a risk of restart failure, resulting in a low restart success rate. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a method and device for restarting a DC system based on an ultra-high voltage converter station, so as to solve the problem of low accuracy and reliability of fault detection results of power transformers.

[0005] In order to solve the above technical problems, the embodiments of the present application are implemented as follows: In a first aspect, an embodiment of the present application provides a method for restarting a DC system based on an ultra-high voltage converter station, and the method for restarting a DC system based on an ultra-high voltage converter station includes: in the event of a fault in a pole line of the DC system, receiving a line restart instruction of the DC system through the ultra-high voltage converter station; in response to the line restart instruction, pole-isolating the low-end valve group in the ultra-high voltage converter station; after pole-isolating the low-end valve group, restarting the high-end valve group in the ultra-high voltage converter station and unlocking and restarting the healthy valve group in the ultra-high voltage converter station; unlocking and restarting the healthy valve group in the ultra-high voltage converter station, and re-establishing the pole connection; wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are opened and closed.

[0006] Optionally, unlocking and restarting the healthy valve group in the UHV converter station includes: unlocking and restarting the healthy valve group in the UHV converter station when any one of the unlocking start conditions is met; the unlocking start conditions include at least one of the following: high-end valve group protection locked pole; low-end valve group protection locked pole; restart after unsuccessful locking of the pole line fault of the DC system.

[0007] Optionally, in response to a line restart instruction, isolating the low-end valve group in the UHV converter station includes: starting a REBOOT function of the UHV converter station, and isolating the low-end valve group in the UHV converter station through the REBOOT function.

[0008] Optionally, before starting the REBOOT function of the UHV converter station and isolating the low-end valve group in the UHV converter station through the REBOOT function, the method also includes: judging the bipolar state of the UHV converter station; when the bipolar of the UHV converter station is unlocked and both the bipolars are in bipolar power mode, if the bipolar low-end valve group and the high-end valve group of the DC system are both in the unlocked state, in response to the line restart instruction, the faulty pole line of the DC system is restarted; starting the REBOOT function of the UHV converter station includes: after the restart of the faulty pole line of the DC system fails and the low-end valve group and the high-end valve group are locked, starting the REBOOT function of the UHV converter station.

[0009] Optionally, after the healthy valve group in the UHV converter station is unlocked and restarted, and the pole connection is re-established, the method also includes: simulating a metal grounding fault in the pole line of the DC system in a simulation system, and checking the operating status of the UHV converter station after the pole connection is re-established, wherein the UHV converter station after the pole connection is re-established operates in a full-voltage 0.5pu operating power forward transmission mode.

[0010] In the second aspect, an embodiment of the present application provides a DC system restarting device based on an ultra-high voltage converter station, and the DC system restarting device based on the ultra-high voltage converter station includes: a receiving module, which is used to receive a line restart instruction of the DC system through the ultra-high voltage converter station when a pole line of the DC system fails; an isolation module, which is used to pole-isolate the low-end valve group in the ultra-high voltage converter station in response to the line restart instruction; a restart module, which is used to restart the high-end valve group in the ultra-high voltage converter station and unlock and restart the healthy valve group in the ultra-high voltage converter station after pole isolating the low-end valve group; the restart module is also used to unlock and restart the healthy valve group in the ultra-high voltage converter station and re-establish the pole connection; wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are opened and closed.

[0011] Optionally, the restart module is also used to unlock and restart the healthy valve group in the UHV converter station when any one of the unlocking start conditions is met; the unlocking start conditions include at least one of the following: high-end valve group protection locked pole; low-end valve group protection locked pole; DC system pole line fault restart fails and then restarts after being locked.

[0012] Optionally, the isolation module is also used to start the REBOOT function of the UHV converter station, and to isolate the low-end valve group in the UHV converter station through the REBOOT function.

[0013] Optionally, it also includes: a judgment module, used to judge the bipolar state of the UHV converter station; a restart module, also used to, when the bipolar of the UHV converter station is unlocked and both the bipolars are in the bipolar power mode, if the bipolar low-end valve group and the high-end valve group of the DC system are in the unlocked state, respond to the line restart instruction to restart the faulty pole line of the DC system; the restart module is also used to start the REBOOT function of the UHV converter station after the restart of the faulty pole line of the DC system fails and the low-end valve group and the high-end valve group are locked.

[0014] Optionally, it also includes: an inspection module, used to simulate a metal grounding fault in the pole line of the DC system in the simulation system, and check the operating status of the UHV converter station after the pole connection is re-established, wherein the UHV converter station after the pole connection is re-established operates in a full-voltage 0.5pu operating power forward transmission mode.

[0015] Through the technical solution disclosed in the embodiment of the present application, in the case of a fault in the pole line of the DC system, the line restart instruction of the DC system is received through the UHV converter station; in response to the line restart instruction, the low-end valve group in the UHV converter station is pole-isolated; after the low-end valve group is pole-isolated, the high-end valve group in the UHV converter station is restarted and the healthy valve group in the UHV converter station is unlocked and restarted; the healthy valve group in the UHV converter station is unlocked and restarted, and the pole connection is reestablished. Wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are disconnected and connected. In this way, when restarting, the embodiment of the present application only needs to isolate the low-end valve group and unlock and restart the high-end valve group and the healthy valve group, and in the process of pole isolation and pole connection, only the pole bus disconnector and the pole neutral bus disconnector in the DC system need to be disconnected and connected, which reduces the number of devices that need to be disconnected and closed, reduces the restart time, and improves the restart efficiency. In addition, due to the reduction in the number of devices that need to be disconnected and closed, the risk of restart failure is reduced and the restart success rate is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application 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 recorded in the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0017] Figure 1A A schematic flow chart of a method for restarting a DC system based on an ultra-high voltage converter station provided in an embodiment of the present application.

[0018] Figure 1B A schematic diagram of the switch distribution structure for restarting a DC system in a UHV converter station disclosed in an embodiment of the present application.

[0019] Figure 2 A schematic diagram of the structure of a DC system restarting device based on an ultra-high voltage converter station provided in an embodiment of the present application.

[0020] Figure 3 A structural schematic diagram of a DC system restart system based on an ultra-high voltage converter station provided in an embodiment of the present application. DETAILED DESCRIPTION

[0021] The purpose of the embodiments of the present application is to provide a method and device for restarting a DC system based on an ultra-high voltage converter station, thereby improving the accuracy and reliability of fault detection results of a power transformer.

[0022] In order to enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are only part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0023] For example, Figure 1A As shown, an embodiment of the present application provides a method for restarting a DC system based on an ultra-high voltage converter station. The method for restarting a DC system based on an ultra-high voltage converter station may specifically include the following steps: In step S101, when a fault occurs in a pole line of a DC system, a line restart instruction of the DC system is received through an ultra-high voltage converter station.

[0024] Specifically, the DC system refers to a technology used for long-distance, large-capacity power transmission in the High Voltage Direct Current (HVDC) transmission system. It is mainly composed of UHV converter stations, DC transmission lines, control systems, and protection systems. The UHV converter station includes a bipolar structure, and each pole contains four valve groups, namely two high-end valve groups and two low-end valve groups. Corresponding to the bipolar four-valve structure of the UHV converter station, the control system of the UHV converter station includes system control, bipolar control pole control, and valve group control. The restart logic function is an important protection measure in the UHV converter station, which is mainly used to handle the pole line fault of the DC system. It mainly includes full-voltage restart logic, step-down restart logic, and pole blocking logic. When a fault occurs in the pole line of the DC system, a line restart DC of the DC system will be issued to restart the pole line of the DC system. The UHV converter station receives the line restart instruction and restarts the pole line of the DC system.

[0025] In step S102, in response to a line restart instruction, the low-end valve group in the UHV converter station is pole-isolated.

[0026] Specifically, after the UHV converter station receives the line restart instruction, in order to transmit as much DC power as possible, the UHV converter station will start the REBOOT function of the UHV converter station, and isolate the low-end valve group in the UHV converter station through the REBOOT function. Before the process of pole isolation through the REBOOT function, first determine the bipolar state of the UHV converter station; when the bipolar of the UHV converter station is unlocked and both the bipolars are in the bipolar power mode, if the bipolar low-end valve group and the high-end valve group of the DC system are both in the unlocked state, in response to the line restart instruction, restart the faulty pole line of the DC system; wherein, starting the REBOOT function of the UHV converter station includes: after the restart of the faulty pole line of the DC system fails and the low-end valve group and the high-end valve group are locked, start the REBOOT function of the UHV converter station.

[0027] Specifically, the UHV converter station includes a bipolar structure, and each pole includes four valve groups, namely two high-end valve groups and two low-end valve groups. The bipolar state of the UHV converter station refers to the state of the bipolar structure of the UHV converter station. If the bipolars of the bipolar structure of the UHV converter station are unlocked and the bipolars are in bipolar power mode, and the low-end valve group and the high-end valve group of the bipolar of the DC system are both in the unlocked state, the faulty pole line of the DC system is directly restarted. If the direct restart of the faulty pole line of the DC system fails, resulting in the locking of the low-end valve group and the high-end valve group, the REBOOT function of the UHV converter station is restarted. The REBOOT function of the UHV converter station is used to restart the pole line of the DC system. In this way, the success rate of restarting the pole line of the DC system is improved.

[0028] In step S103, after isolating the low-end valve group, the high-end valve group in the UHV converter station is restarted and the healthy valve group in the UHV converter station is unlocked and restarted.

[0029] Specifically, after isolating the low-end valve group, the REBOOT function of the UHV converter station can be used to restart the pole line of the DC system. Specifically, the high-end valve group in the UHV converter station can be restarted to achieve a 50% voltage reduction restart of the DC line of the DC system, and the healthy valve group in the UHV converter station can be unlocked and restarted.

[0030] Furthermore, when unlocking and restarting the healthy valve group in the UHV converter station, the healthy valve group in the UHV converter station is unlocked and restarted when any one of the unlocking start conditions is met; the unlocking start conditions include at least one of the following: high-end valve group protection locked pole; low-end valve group protection locked pole; pole line fault restart of the DC system fails and then restarts after being locked.

[0031] In step S104, the healthy valve groups in the UHV converter station are unlocked and restarted, and the pole connection is reestablished.

[0032] In the process of pole isolation and pole connection, the pole bus isolating switch and the pole neutral bus isolating switch in the DC system are opened and closed.

[0033] Specifically, during the pole isolation and pole connection process, only the pole bus isolating switch and the pole neutral bus isolating switch in the DC system are opened and closed. The pole return line isolating switch and the pole metal return line isolating switch are no longer opened and closed. This reduces the number of equipment actions and improves the restart success rate. Figure 1B As shown, Figure 1B This is a schematic diagram of the switch distribution structure of a UHV converter station restarting a DC system disclosed in an embodiment of the present application. Figure 1B As shown, Figure 1B The part marked with ① is the pole bus disconnector P1_WP_Q17. Figure 1B The ② in the figure is the pole neutral bus disconnector P1_WN_Q1. The ③ in the figure is the pole metal return disconnector WN_Q13. The ④ in the figure is the pole return disconnector WN_Q11. Figure 1B The description of the remaining structures can be found in the prior art, and the embodiments of the present application will not be repeated here.

[0034] Through the technical solution disclosed in the embodiment of the present application, in the case of a fault in the pole line of the DC system, the line restart instruction of the DC system is received through the UHV converter station; in response to the line restart instruction, the low-end valve group in the UHV converter station is pole-isolated; after the low-end valve group is pole-isolated, the high-end valve group in the UHV converter station is restarted and the healthy valve group in the UHV converter station is unlocked and restarted; the healthy valve group in the UHV converter station is unlocked and restarted, and the pole connection is reestablished. Wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are disconnected and connected. In this way, when restarting, the embodiment of the present application only needs to isolate the low-end valve group and unlock and restart the high-end valve group and the healthy valve group, and in the process of pole isolation and pole connection, only the pole bus disconnector and the pole neutral bus disconnector in the DC system need to be disconnected and connected, which reduces the number of devices that need to be disconnected and closed, reduces the restart time, and improves the restart efficiency. In addition, due to the reduction in the number of devices that need to be disconnected and closed, the risk of restart failure is reduced and the restart success rate is improved.

[0035] Furthermore, in an embodiment of the present application, after the healthy valve group in the UHV converter station is unlocked and restarted, and the pole connection is re-established, it also includes: simulating a metal grounding fault in the pole line of the DC system in a simulation system, and checking the operating status of the UHV converter station after the pole connection is re-established, wherein the UHV converter station after the pole connection is re-established operates in a full-voltage 0.5pu operating power forward transmission mode.

[0036] Specifically, the embodiment of the present application can simulate and detect the operating status of the UHV converter station after the re-establishment of the connection through the simulation system, thereby ensuring the stable and reliable operation of the UHV converter station after the pole connection is re-established.

[0037] Corresponding to the DC system restart method based on the UHV converter station provided in the above embodiment, based on the same technical concept, the embodiment of the present application also provides a DC system restart device based on the UHV converter station. Figure 2 A schematic diagram of a DC system restart device based on a UHV converter station provided in an embodiment of the present application, wherein the DC system restart device based on a UHV converter station is used to execute Figure 1A The DC system restart method based on the UHV converter station described in Figure 2 As shown, the DC system restart device 200 based on the UHV converter station includes: a receiving module 201, which is used to receive a line restart instruction of the DC system through the UHV converter station when a fault occurs in a pole line of the DC system; The isolation module 202 is used to pole-isolate the low-end valve group in the UHV converter station in response to the line restart instruction; the restart module 203 is used to restart the high-end valve group in the UHV converter station and unlock and restart the healthy valve group in the UHV converter station after pole-isolating the low-end valve group; the restart module 203 is also used to unlock and restart the healthy valve group in the UHV converter station and re-establish the pole connection; wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are opened and closed.

[0038] Through the technical solution disclosed in the embodiment of the present application, in the case of a fault in the pole line of the DC system, the line restart instruction of the DC system is received through the UHV converter station; in response to the line restart instruction, the low-end valve group in the UHV converter station is pole-isolated; after the low-end valve group is pole-isolated, the high-end valve group in the UHV converter station is restarted and the healthy valve group in the UHV converter station is unlocked and restarted; the healthy valve group in the UHV converter station is unlocked and restarted, and the pole connection is reestablished. Wherein, in the process of pole isolation and pole connection, the pole bus disconnector and the pole neutral bus disconnector in the DC system are disconnected and connected. In this way, when restarting, the embodiment of the present application only needs to isolate the low-end valve group and unlock and restart the high-end valve group and the healthy valve group, and in the process of pole isolation and pole connection, only the pole bus disconnector and the pole neutral bus disconnector in the DC system need to be disconnected and connected, which reduces the number of devices that need to be disconnected and closed, reduces the restart time, and improves the restart efficiency. In addition, due to the reduction in the number of devices that need to be disconnected and closed, the risk of restart failure is reduced and the restart success rate is improved.

[0039] Optionally, the restart module 203 is also used to unlock and restart the healthy valve group in the UHV converter station when any one of the unlocking start conditions is met; the unlocking start conditions include at least one of the following: high-end valve group protection locked pole; low-end valve group protection locked pole; pole line fault restart of the DC system fails and then restarts after being locked.

[0040] Optionally, the isolation module 202 is further used to start the REBOOT function of the UHV converter station, and to isolate the low-end valve group in the UHV converter station through the REBOOT function.

[0041] Optionally, a judgment module is used to judge the bipolar state of the UHV converter station; the restart module 203 is also used to, when the bipolar of the UHV converter station is unlocked and both the bipolars are in bipolar power mode, if the bipolar low-end valve group and the high-end valve group of the DC system are in the unlocked state, respond to the line restart instruction to restart the faulty pole line of the DC system; the restart module 203 is also used to start the REBOOT function of the UHV converter station after the restart of the faulty pole line of the DC system fails and the low-end valve group and the high-end valve group are locked.

[0042] Optionally, it also includes: an inspection module, used to simulate a metal grounding fault in the pole line of the DC system in the simulation system, and check the operating status of the UHV converter station after the pole connection is re-established, wherein the UHV converter station after the pole connection is re-established operates in a full-voltage 0.5pu operating power forward transmission mode.

[0043] It should be noted that the DC system restart device based on the ultra-high voltage converter station provided in the embodiment of the present application and the DC system restart method based on the ultra-high voltage converter station provided in the embodiment of the present application are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned DC system restart method based on the ultra-high voltage converter station, and has the same or similar beneficial effects, and the repeated parts will not be repeated.

[0044] Corresponding to the DC system restart system based on the UHV converter station provided in the above embodiment, based on the same technical concept, the embodiment of the present application further provides a DC system restart system based on the UHV converter station, the DC system restart system based on the UHV converter station is used to execute the above DC system restart system based on the UHV converter station, Figure 3 A schematic diagram of a DC system restart system based on a UHV converter station provided in an embodiment of the present application is shown in FIG. Figure 3The restart system of the DC system based on the UHV converter station may have relatively large differences due to different configurations or performances, and may include one or more processors 301 and memory 302, the memory 302 is used to store computer programs that can be run on the processor 301, and the processor 301 is used to execute the program stored in the memory 302 to achieve the above Figure 1A The various steps in the method embodiment. The memory 302 may be a temporary storage or a permanent storage. The application stored in the memory 302 may include one or more modules (not shown in the figure), each of which may include a series of computer executable instructions in the restart system of the DC system based on the ultra-high voltage converter station.

[0045] Furthermore, the processor 301 may be configured to communicate with the memory 302, and execute a series of computer executable instructions in the memory 302 on the DC system restart system based on the UHV converter station. The DC system restart system based on the UHV converter station may also include one or more power supplies 303, one or more wired or wireless network interfaces 304, one or more input and output interfaces 305, and one or more keyboards 306.

[0046] Specifically in this embodiment, the DC system restart system based on the UHV converter station includes a processor, a communication interface, a memory and a communication bus; wherein the processor, the communication interface and the memory communicate with each other through the bus; the memory is used to store computer programs; the processor is used to execute the programs stored in the memory to achieve the above Figure 1A The various steps in the method embodiment are similar to those in the method embodiment, and have the beneficial effects of the above method embodiments. To avoid repetition, the embodiments of the present application will not be described again here.

[0047] It should be noted that the DC system restart system based on the ultra-high voltage converter station provided in the embodiment of the present application and the DC system restart system based on the ultra-high voltage converter station provided in the embodiment of the present application are based on the same application concept. Therefore, the specific implementation of this embodiment can refer to the implementation of the aforementioned DC system restart system based on the ultra-high voltage converter station, and has the same or similar beneficial effects, and the repeated parts will not be repeated.

[0048] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0049] These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory produce a manufactured product including an instruction device that implements the functions specified in one or more processes in the flowchart and / or one or more boxes in the block diagram.

[0050] In a typical configuration, an electronic device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0051] Memory may include non-permanent storage in a computer-readable medium, in the form of random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM. Memory is an example of a computer-readable medium.

[0052] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0053] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, devices or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0054] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A method for restarting a DC system based on an ultra-high voltage converter station, characterized in that: The method comprises: In the event of a fault in a pole line of a DC system, receiving a line restart instruction of the DC system through the UHV converter station; In response to the line restart instruction, isolating the low-end valve group in the UHV converter station; After isolating the low-end valve group, restarting the high-end valve group in the UHV converter station and unlocking and restarting the healthy valve group in the UHV converter station; Unlocking and restarting the healthy valve group in the UHV converter station, and re-establishing the pole connection; In the process of pole isolation and pole connection, the pole bus isolating switch and the pole neutral bus isolating switch in the DC system are opened and closed.

2. The method for restarting a DC system based on a UHV converter station according to claim 1, characterized in that: The unlocking and restarting of the healthy valve group in the UHV converter station comprises: When any one of the unlocking start conditions is met, unlocking and restarting the healthy valve group in the UHV converter station; The unlocking start condition includes at least one of the following: The high-end valve group protects the locking pole; The low-end valve group protects the locking pole; The DC system restarts after a pole line fault fails and is locked out.

3. The method for restarting a DC system based on a UHV converter station according to claim 1, characterized in that: In response to the line restart instruction, isolating the low-end valve group in the UHV converter station comprises: The REBOOT function of the UHV converter station is started, and the low-end valve group in the UHV converter station is polarly isolated by the REBOOT function.

4. The method for restarting a DC system based on a UHV converter station according to claim 3, characterized in that: Before starting the REBOOT function of the UHV converter station and isolating the low-end valve group in the UHV converter station by the REBOOT function, the method further includes: Determining the bipolar state of the UHV converter station; When the bipolar of the UHV converter station is unlocked and both the bipolars are in bipolar power mode, if the low-end valve group and the high-end valve group of the bipolar of the DC system are both in unlocked state, in response to the line restart instruction, the faulty pole line of the DC system is restarted; The REBOOT function of starting the UHV converter station includes: After the faulty pole line of the DC system fails to restart and the low-end valve group and the high-end valve group are locked, the REBOOT function of the UHV converter station is started.

5. The method for restarting a DC system based on a UHV converter station according to claim 1, characterized in that: After unlocking and restarting the healthy valve group in the UHV converter station and reestablishing the pole connection, the method further includes: A metal grounding fault is simulated in a pole line of a DC system in a simulation system, and the operating status of the UHV converter station after the pole connection is reestablished is checked, wherein the UHV converter station after the pole connection is reestablished operates in a full-voltage 0.5pu operating power forward transmission mode.

6. A DC system restart device based on a UHV converter station, characterized in that: include: A receiving module, used for receiving a line restart instruction of the DC system through the UHV converter station when a fault occurs in a pole line of the DC system; An isolation module, configured to isolate the low-end valve group in the UHV converter station in response to the line restart instruction; A restart module, used to restart the high-end valve group in the UHV converter station and unlock and restart the healthy valve group in the UHV converter station after isolating the low-end valve group; The restart module is also used to unlock and restart the healthy valve group in the UHV converter station and re-establish the pole connection; In the process of pole isolation and pole connection, the pole bus isolating switch and the pole neutral bus isolating switch in the DC system are opened and closed.

7. The DC system restart device based on the UHV converter station according to claim 6, characterized in that: The restart module is further configured to unlock and restart the healthy valve group in the UHV converter station when any one of the unlocking start conditions is met; The unlocking start condition includes at least one of the following: The high-end valve group protects the locking pole; The low-end valve group protects the locking pole; The DC system restarts after a pole line fault fails and is locked out.

8. The DC system restart device based on the UHV converter station according to claim 6, characterized in that: The isolation module is also used to start the REBOOT function of the UHV converter station, and to isolate the low-end valve group in the UHV converter station through the REBOOT function.

9. The DC system restart device based on the UHV converter station according to claim 6, characterized in that: Also includes: A judgment module, used for judging the bipolar state of the UHV converter station; The restart module is further configured to, when the bipolar of the UHV converter station is unlocked and both the bipolars are in the bipolar power mode, if the low-end valve group and the high-end valve group of the bipolar of the DC system are both in the unlocked state, respond to the line restart instruction to restart the faulty pole line of the DC system; The restart module is further used to start the REBOOT function of the UHV converter station after the faulty pole line of the DC system fails to restart and the low-end valve group and the high-end valve group are locked.

10. The DC system restart device based on the UHV converter station according to claim 6, characterized in that: Also includes: The inspection module is used to simulate a metal grounding fault in the pole line of a DC system in a simulation system, and to check the operating status of the UHV converter station after the pole connection is reestablished, wherein the UHV converter station after the pole connection is reestablished operates in a full-voltage 0.5pu operating power forward transmission mode.

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