Metallic grounding fault processing method and device

Abstract

The invention provides a processing method and device for a metallic grounding fault, and relates to the technical field of offshore converter stations, and the method comprises the steps: determining the type of a grounding fault currently occurring at a network side of a transformer according to the network side voltage of the offshore transformer and the voltage amplitude value of a grid-connected point; controlling the DC voltage based on an onshore converter station so as to maintain the DC voltage in a first range; controlling the transmission power to be at a corresponding power value according to the type of the grounding fault; and recovering the operation of the offshore converter station based on the processing mode corresponding to the grounding fault type. Therefore, targeted fault recovery can be carried out on different types of grounding faults such as a single-phase grounding fault, a double-phase grounding fault and a three-phase grounding fault in time and reliably, stable operation of the system is recovered, overvoltage and overcurrent conditions are avoided, and the fault processing process is improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of offshore converters, and in particular to a method and device for processing a metallic ground fault. Background Art

[0002] Current technologies for handling metallic ground faults on the AC grid side of offshore wind farms have limitations. Typically, the type of ground fault is determined by monitoring the grid-side voltage of the offshore transformer. However, existing technologies face challenges in handling metallic ground faults. Therefore, effectively addressing metallic ground faults on the AC grid side of offshore wind farms and improving system stability and reliability remain pressing challenges. Summary of the Invention

[0003] The present disclosure aims to solve one of the technical problems in the related art at least to a certain extent.

[0004] The first embodiment of the present disclosure provides a method for handling a metallic ground fault, including:

[0005] Determining the type of ground fault currently occurring on the grid side of the offshore transformer based on the grid-side voltage and the grid connection point voltage amplitude;

[0006] controlling the DC voltage based on the onshore converter station so as to maintain the DC voltage within a first range;

[0007] According to the ground fault type, controlling the transmission power to be at a corresponding power value;

[0008] Based on the processing method corresponding to the ground fault type, the operation of the offshore converter station is restored.

[0009] A second embodiment of the present disclosure provides a device for processing a metallic ground fault, comprising:

[0010] A determination module, configured to determine the type of ground fault currently occurring on the grid side of the offshore transformer based on the grid side voltage and the grid connection point voltage amplitude value;

[0011] A first control module is configured to control a DC voltage based on an onshore converter station so as to maintain the DC voltage within a first range;

[0012] a second control module, configured to control the transmission power to be at a corresponding power value according to the ground fault type;

[0013] The recovery module is used to restore the operation of the offshore converter station based on a processing method corresponding to the ground fault type.

[0014] The third aspect of the present disclosure provides an electronic device, comprising: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for handling metallic grounding faults as provided in the first aspect of the present disclosure is implemented.

[0015] The fourth embodiment of the present disclosure proposes a non-temporary computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method for handling metallic grounding faults as proposed in the first embodiment of the present disclosure.

[0016] The method, device, equipment, and storage medium for handling metallic ground faults provided by the present disclosure have the following beneficial effects:

[0017] In the disclosed embodiment, the type of ground fault currently occurring on the offshore transformer grid side is first determined based on the grid-side voltage and the grid connection point voltage amplitude. The DC voltage is then controlled based on the onshore converter station to maintain the DC voltage within a first range. The transmission power is then controlled to a corresponding power value based on the ground fault type. Finally, operation of the offshore converter station is restored based on the corresponding handling method for the ground fault type. This allows for timely and reliable targeted fault recovery for different types of ground faults, such as single-phase, double-phase, and three-phase ground faults, restoring stable system operation while avoiding overvoltage and overcurrent conditions and improving the fault handling process.

[0018] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The above and / or additional aspects and advantages of the present disclosure will become apparent and readily understood from the following description of the embodiments in conjunction with the accompanying drawings, in which:

[0020] Figure 1 A flowchart of a method for handling a metallic ground fault provided by an embodiment of the present disclosure;

[0021] Figure 2 This is a structural block diagram of a device for processing a metallic ground fault provided by an embodiment of the present disclosure;

[0022] Figure 3 A block diagram of an exemplary computer device suitable for implementing embodiments of the present disclosure is shown. DETAILED DESCRIPTION

[0023] The following describes in detail embodiments of the present disclosure, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present disclosure, and should not be construed as limiting the present disclosure.

[0024] The following describes a method, apparatus, computer device, and storage medium for processing a metallic ground fault according to embodiments of the present disclosure with reference to the accompanying drawings.

[0025] It should be noted that the execution body of the method for handling metallic ground faults in the embodiment of the present disclosure is a processing device for metallic ground faults, which can be implemented by software and / or hardware and can be configured in any electronic device.

[0026] Figure 1 This is a flowchart of a method for processing a metallic ground fault provided by the first embodiment of the present disclosure.

[0027] like Figure 1 As shown, the method for handling the metallic ground fault may include the following steps:

[0028] Step 101: Determine the type of ground fault currently occurring on the grid side of the offshore transformer based on the grid side voltage and the grid connection point voltage amplitude.

[0029] Among them, the system initially operates stably at the rated power level.

[0030] Specifically, if any phase voltage of the offshore transformer grid-side voltage drops to zero and the grid connection point voltage amplitude value drops to a first threshold, it is determined that the current grounding fault type occurring on the transformer grid-side is a single-phase grounding fault.

[0031] For example, if the phase a voltage of the offshore transformer grid-side voltage Vac1_grid drops rapidly to 0 and the grid connection point voltage amplitude Vrms1_grid drops to 80%, that is, when the first threshold is 80%, it is determined that the current ground fault type occurring on the transformer grid-side is a single-phase ground fault.

[0032] A single-phase ground fault is a metallic ground fault occurring on the grid side of an offshore transformer, where only one phase (A, B, or C) is connected to ground, while the other two phases are not. This creates unbalanced current and voltage. In this fault condition, the voltage on the unfaulted phase typically rises rapidly, while the voltage on the faulted phase quickly drops to zero.

[0033] If any two phase voltages of the offshore transformer grid-side voltage drop to zero, and the grid connection point voltage amplitude value drops to a second threshold, the ground fault type is determined to be a double-phase ground fault.

[0034] For example, if the a and b phase voltages of the offshore transformer grid-side voltage Vac1_grid drop rapidly to 0, and the grid connection point voltage amplitude Vrms1_grid drops to between 20% and 30%, the ground fault type is determined to be a double-phase ground fault.

[0035] A double-phase grounding fault occurs when two phases (usually Phase A and Phase B, or Phase B and Phase C) in a power system are simultaneously short-circuited to ground. A three-phase grounding fault occurs when at least one of the three phases (i.e., Phase A, Phase B, and Phase C) in a power system is short-circuited to ground.

[0036] If the grid-side voltage of the offshore transformer drops to zero and the voltage amplitude value of the grid connection point drops to a third threshold, the ground fault type is determined to be a three-phase ground fault, wherein the third threshold is less than the second threshold, and the second threshold is less than the third threshold.

[0037] For example, if the grid-side voltage Vac1_grid of the offshore transformer drops rapidly to 0 and the grid connection point voltage amplitude Vrms1_grid drops to 0, the ground fault type is determined to be a three-phase ground fault.

[0038] During a single-phase fault, the wind turbine generates a certain amount of reactive power. Due to the voltage drop on the grid side of the wind turbine converter, the wind turbine still maintains a certain amount of active power and outputs reactive power during this period.

[0039] During the recovery period after the fault is cleared, the reactive power of the wind turbine changes from providing reactive power to absorbing reactive power to not providing reactive power, and the active power output also returns to the pre-fault level.

[0040] During a two-phase fault, the wind turbine generates a certain amount of reactive power, Q_GS, to counteract the drop in grid-side voltage, V_GS, of the wind turbine converter. During this period, the wind turbine power drops to near zero. After the fault is cleared and the wind turbine recovers, its reactive power output changes from providing reactive power to absorbing reactive power to not providing reactive power, and its active power output also returns to pre-fault levels.

[0041] During a three-phase fault, the wind turbine generates a certain amount of reactive power Q_GS during the fault period. Due to the voltage drop of the grid-side voltage V_GS of the wind turbine converter, the wind turbine power drops to near zero during this period.

[0042] During the recovery period after the fault is cleared, the reactive power of the wind turbine changes from providing reactive power to absorbing reactive power to not providing reactive power, and the active power output also returns to the pre-fault level.

[0043] Step 102: Control the DC voltage based on the onshore converter station to maintain the DC voltage within a first range.

[0044] It should be noted that the DC voltage Edc1 is controlled by the onshore converter station during the fault period and is basically controlled around 1 pu, where 1 pu can be a unit of rated voltage. In the embodiment of the present disclosure, the first range can be the voltage range corresponding to 1 pu, such as [0.95 pu, 1.05 pu].

[0045] Specifically, the onshore converter station controls the DC voltage by adjusting the converter's control parameters. During a fault, the onshore converter station monitors the DC voltage and takes appropriate adjustments to maintain the DC voltage within the first range. The specific operation includes the following steps:

[0046] Monitoring DC voltage: The onshore converter station will monitor the DC voltage value in real time.

[0047] Control parameter adjustment: Based on the deviation of the DC voltage value from the target range, the onshore converter station will adjust the converter control parameters accordingly, such as changing the converter modulation instructions, so that the DC voltage gradually approaches the target value.

[0048] Stability control: The onshore converter station will continuously monitor and adjust the DC voltage until the DC voltage stabilizes within the first range.

[0049] Optionally, you can also consider adding safety protection functions, such as overvoltage protection, overcurrent protection, etc., as well as interlocking mechanisms with other systems to ensure that the system can operate safely under abnormal circumstances.

[0050] Optionally, you can also consider adding backup equipment or redundant control strategies to improve the reliability and robustness of the system.

[0051] Optionally, a remote monitoring and control system can be introduced, allowing operators to monitor the DC voltage status at any time and perform remote control. In short, the DC voltage control solution based on the onshore converter station maintains the DC voltage within a specified range by real-time monitoring and adjusting the converter's control parameters. Furthermore, extended functions such as safety protection, reliability optimization, and remote monitoring may be added as needed.

[0052] Step 103: Control the transmission power to a corresponding power value according to the type of the ground fault.

[0053] Transmission power refers to the power consumed or transferred during signal or energy transmission.

[0054] When the ground fault type is a single-phase ground fault, controlling the transmission power to be in the first interval;

[0055] When the ground fault type is a double-phase ground fault, controlling the transmission power to be in the second interval;

[0056] In the case where the ground fault type is a three-phase ground fault, the transmission power is controlled to be zero, wherein the value of the first interval is greater than that of the second interval.

[0057] The first range may be about 0.6 pu, such as (0.58 pu, 0.63 pu), and the second range may be 0 to 0.1 pu.

[0058] Step 104: Restore the operation of the offshore converter station based on the processing method corresponding to the ground fault type.

[0059] Optionally, when the ground fault type is a single-phase ground fault,

[0060] Providing reactive power support within a preset range to the offshore converter station based on the offshore converter during a fault;

[0061] The AC side voltage is controlled to be raised, and the grid side voltage of the offshore transformer is controlled to be lower than the first voltage.

[0062] For example, under the control of the converter voltage outer loop, the AC side voltage can rise rapidly and recover to above 0.9 pu within 50 ms. During the entire recovery process, Vac1_grid does not exhibit significant overvoltage and is controlled within 1.05 pu. The DC voltage is then restored to 1 pu under the control of the onshore converter station. The first voltage is 1.05 pu. The 1 pu in the disclosed embodiments can be determined based on practical experience.

[0063] Optionally, when the ground fault type is a double-phase ground fault or a three-phase ground fault,

[0064] The converter voltage outer loop is controlled to raise the AC side voltage, and the offshore transformer grid side voltage is controlled to be less than the first voltage. In response to the controller triggering the DC voltage dynamic response, the DC energy consumption device is started.

[0065] It should be noted that the AC side voltage can be increased through the converter voltage outer loop control. At the same time, to ensure that the offshore transformer grid-side voltage is less than the first voltage, the controller may cause a dynamic response in the DC voltage. During this process, a DC energy dissipation device is triggered to dissipate excess DC voltage.

[0066] In the disclosed embodiment, the type of ground fault currently occurring on the offshore transformer grid side is first determined based on the grid-side voltage and the grid connection point voltage amplitude. Then, the DC voltage is controlled at the onshore converter station to maintain the DC voltage within a first range. The transmission power is then controlled to a corresponding power value based on the ground fault type. Finally, operation of the offshore converter station is restored based on the corresponding handling method for the ground fault type. This allows for timely and reliable fault recovery for different types of ground faults, such as single-phase, double-phase, and three-phase ground faults, restoring stable system operation while avoiding overvoltage and overcurrent conditions and improving the fault handling process. This solution proposes a DC voltage control method based on the onshore converter station to maintain the DC voltage within a safe range. Based on the different ground fault types, the transmission power is controlled to operate at the corresponding power value. Furthermore, relevant measures are implemented based on the ground fault handling method to restore normal operation of the offshore converter station. This method effectively addresses the issue of handling metallic ground faults on the AC grid side of offshore wind farms, improving system stability and reliability.

[0067] In order to implement the above embodiment, the present disclosure further provides a device for processing a metallic ground fault.

[0068] Figure 2 This is a structural block diagram of a processing device for a metallic ground fault provided by the second embodiment of the present disclosure.

[0069] like Figure 2 As shown, the processing device 200 for the metallic ground fault may include:

[0070] A determination module 210 is configured to determine the type of ground fault currently occurring on the grid side of the offshore transformer based on the grid side voltage and the grid connection point voltage amplitude value;

[0071] A first control module 220 is configured to control the DC voltage based on the onshore converter station so as to maintain the DC voltage within a first range;

[0072] A second control module 230 is configured to control the transmission power to be at a corresponding power value according to the ground fault type;

[0073] The recovery module 240 is configured to restore the operation of the offshore converter station based on a processing method corresponding to the ground fault type.

[0074] Optionally, the determining module is specifically configured to:

[0075] If any phase voltage of the offshore transformer grid-side voltage drops to zero, and the grid connection point voltage amplitude value drops to a first threshold, it is determined that the type of the grounding fault currently occurring on the transformer grid-side is a single-phase grounding fault;

[0076] If any two phase voltages of the offshore transformer grid-side voltage drop to zero, and the grid connection point voltage amplitude value drops to a second threshold, it is determined that the ground fault type is a double-phase ground fault;

[0077] If the grid-side voltage of the offshore transformer drops to zero and the grid-connection point voltage amplitude value drops to a third threshold, it is determined that the ground fault type is a three-phase ground fault.

[0078] The third threshold is smaller than the second threshold, and the second threshold is smaller than the third threshold.

[0079] Optionally, the second control module is specifically configured to:

[0080] When the ground fault type is a single-phase ground fault, controlling the transmission power to be within a first interval;

[0081] When the ground fault type is a double-phase ground fault, controlling the transmission power to be within a second interval;

[0082] When the ground fault type is a three-phase ground fault, the transmission power is controlled to be zero, wherein the value of the first interval is greater than that of the second interval.

[0083] Optionally, the recovery module is specifically configured to:

[0084] When the ground fault type is a single-phase ground fault,

[0085] Providing reactive power support within a preset range to the offshore converter station based on the offshore converter during a fault;

[0086] The AC side voltage is controlled to be raised, and the grid side voltage of the offshore transformer is controlled to be lower than the first voltage.

[0087] Optionally, the recovery module is specifically configured to:

[0088] When the ground fault type is a double-phase ground fault or a three-phase ground fault,

[0089] By controlling the converter voltage outer loop, the AC side voltage is raised, and the grid side voltage of the offshore transformer is controlled to be less than the first voltage;

[0090] In response to the controller triggering the DC voltage dynamic response, the DC energy consumption device is started.

[0091] In the disclosed embodiment, the type of ground fault currently occurring on the offshore transformer grid side is first determined based on the grid-side voltage and the grid connection point voltage amplitude. The DC voltage is then controlled based on the onshore converter station to maintain the DC voltage within a first range. The transmission power is then controlled to a corresponding power value based on the ground fault type. Finally, operation of the offshore converter station is restored based on the corresponding handling method for the ground fault type. This allows for timely and reliable targeted fault recovery for different types of ground faults, such as single-phase, double-phase, and three-phase ground faults, restoring stable system operation while avoiding overvoltage and overcurrent conditions and improving the fault handling process.

[0092] In order to implement the above embodiments, the present disclosure further proposes a computer device, including: a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, the method for handling metallic ground faults proposed in the above embodiments of the present disclosure is implemented.

[0093] In order to implement the above embodiments, the present disclosure further proposes a non-transitory computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the method for handling metallic ground faults proposed in the above embodiments of the present disclosure is implemented.

[0094] To implement the above embodiments, the present disclosure further proposes a computer program product. When an instruction processor in the computer program product executes the method for handling metallic ground faults proposed in the above embodiments of the present disclosure, the method is executed.

[0095] Figure 3 A block diagram of an exemplary computer device suitable for implementing embodiments of the present disclosure is shown. Figure 3 The computer device 12 shown is only an example and should not bring any limitation to the functionality and scope of use of the embodiments of the present disclosure.

[0096] like Figure 3 As shown, computer device 12 is implemented as a general-purpose computing device. Components of computer device 12 may include, but are not limited to, one or more processors or processing units 16, system memory 28, and a bus 18 that connects various system components (including system memory 28 and processing unit 16).

[0097] Bus 18 represents one or more of several types of bus structures, including a memory bus or memory controller, a peripheral bus, an accelerated graphics port, a processor, or a local bus using any of a variety of bus architectures. Examples of such architectures include, but are not limited to, the Industry Standard Architecture (ISA) bus, the Micro Channel Architecture (MAC) bus, the Enhanced ISA bus, the Video Electronics Standards Association (VESA) local bus, and the Peripheral Component Interconnection (PCI) bus.

[0098] The computer device 12 typically includes a variety of computer system readable media. These media can be any available media that can be accessed by the computer device 12, including volatile and non-volatile media, removable and non-removable media.

[0099] The memory 28 may include computer system readable media in the form of volatile memory, such as random access memory (RAM) 30 and / or cache memory 32. The computer device 12 may further include other removable / non-removable, volatile / non-volatile computer system storage media. By way of example only, the storage system 34 may be configured to read and write non-removable, non-volatile magnetic media ( Figure 3 Not shown, often called a "hard drive"). Although Figure 3 Although not shown, a disk drive for reading and writing to a removable non-volatile disk (e.g., a "floppy disk"), and an optical disk drive for reading and writing to a removable non-volatile optical disk (e.g., a Compact Disc Read Only Memory (hereinafter referred to as: CD-ROM), a Digital Video Disc Read Only Memory (hereinafter referred to as: DVD-ROM), or other optical media) may be provided. In these cases, each drive may be connected to the bus 18 via one or more data medium interfaces. The memory 28 may include at least one program product having a set (e.g., at least one) of program modules configured to perform the functions of the various embodiments of the present disclosure.

[0100] A program / utility 40 having a set (at least one) of program modules 42 may be stored, for example, in memory 28. Such program modules 42 include, but are not limited to, an operating system, one or more application programs, other program modules, and program data, each of which, or some combination thereof, may include an implementation of a network environment. Program modules 42 generally implement the functions and / or methods of the embodiments described herein.

[0101] The computer device 12 can also communicate with one or more external devices 14 (e.g., a keyboard, pointing device, display 24, etc.), one or more devices that enable a user to interact with the computer device 12, and / or any device that enables the computer device 12 to communicate with one or more other computing devices (e.g., a network card, a modem, etc.). This communication can occur via an input / output (I / O) interface 22. Furthermore, the computer device 12 can communicate with one or more networks (e.g., a local area network (LAN), a wide area network (WAN), and / or a public network such as the Internet) via a network adapter 20. As shown, the network adapter 20 communicates with the other modules of the computer device 12 via a bus 18. It should be understood that, although not shown, other hardware and / or software modules can be used in conjunction with the computer device 12, including but not limited to microcode, device drivers, redundant processing units, external disk drive arrays, RAID systems, tape drives, and data backup storage systems.

[0102] The processing unit 16 executes various functional applications and data processing by running programs stored in the system memory 28, such as implementing the methods mentioned in the above embodiments.

[0103] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification and features of different embodiments or examples, unless they are mutually inconsistent.

[0104] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0105] Any process or method description in a flowchart or otherwise described herein may be understood to represent a module, segment or portion of code comprising one or more executable instructions for implementing the steps of a custom logical function or process, and the scope of the preferred embodiments of the present disclosure includes additional implementations in which functions may be performed out of the order shown or discussed, including performing functions in a substantially simultaneous manner or in the reverse order depending on the functions involved, which should be understood by those skilled in the art to which the embodiments of the present disclosure belong.

[0106] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device (e.g., a computer-based system, a system including a processor, or other system that can fetch and execute instructions from an instruction execution system, apparatus, or device). For purposes of this specification, a "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of computer-readable media include the following: an electrical connection with one or more wires (electronic devices), a portable computer disk cartridge (magnetic device), random access memory (RAM), read-only memory (ROM), erasable and programmable read-only memory (EPROM or flash memory), fiber optic devices, and a portable compact disc read-only memory (CDROM). Furthermore, the computer-readable medium may even be paper or other suitable medium on which the program is printed, since the program may be obtained electronically, for example, by optically scanning the paper or other medium and then editing, interpreting or processing it in another suitable manner if necessary, and then storing it in a computer memory.

[0107] It should be understood that various parts of the present disclosure can be implemented using hardware, software, firmware, or a combination thereof. In the above embodiments, multiple steps or methods can be implemented using software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented using hardware, as in another embodiment, any one of the following technologies known in the art or a combination thereof can be used to implement: a discrete logic circuit having a logic gate circuit for implementing a logic function on a data signal, an application-specific integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0108] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0109] In addition, the functional units in the various embodiments of the present disclosure may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

[0110] The storage medium mentioned above may be a read-only memory, a magnetic disk, or an optical disk, etc. Although the embodiments of the present disclosure have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present disclosure. A person of ordinary skill in the art may make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present disclosure.

Claims

1. A method for handling metallic ground faults. It is characterized in that include: Determine the type of grounding fault currently occurring on the grid side of the transformer according to the grid side voltage of the offshore transformer and the voltage amplitude value of the grid connection point; Controlling the DC voltage based on the onshore converter station so that the DC voltage is maintained in a first range; According to the ground fault type, controlling the transmission power to be at a corresponding power value; Based on the processing method corresponding to the ground fault type, the operation of the offshore converter station is restored.

2. The method according to claim 1, It is characterized in that The determining, according to the grid-side voltage of the offshore transformer and the voltage amplitude value of the grid connection point, the type of ground fault currently occurring on the grid-side of the transformer comprises: If any phase voltage of the offshore transformer grid-side voltage drops to zero, and the grid-connection point voltage amplitude value drops to a first threshold value, it is determined that the type of ground fault currently occurring on the transformer grid-side is a single-phase ground fault; If any two phase voltages of the offshore transformer grid-side voltage drop to zero, and the grid connection point voltage amplitude value drops to a second threshold, it is determined that the ground fault type is a double-phase ground fault; If the grid-side voltage of the offshore transformer drops to zero, and the voltage amplitude value of the grid connection point drops to a third threshold, it is determined that the ground fault type is a three-phase ground fault. The third threshold is smaller than the second threshold, and the second threshold is smaller than the third threshold.

3. The method according to claim 1, It is characterized in that According to the ground fault type, controlling the transmission power to be at a corresponding power value includes: When the ground fault type is a single-phase ground fault, controlling the transmission power to be in a first interval; When the ground fault type is a double-phase ground fault, controlling the transmission power to be in a second interval; When the ground fault type is a three-phase ground fault, the transmission power is controlled to be zero, wherein the value of the first interval is greater than that of the second interval.

4. The method according to claim 1, It is characterized in that The method of restoring the operation of the offshore converter station based on the processing method corresponding to the ground fault type includes: When the ground fault type is a single-phase ground fault, During a fault, providing reactive power support within a preset range to the offshore converter station based on the offshore converter; The AC side voltage is controlled to be raised, and the grid side voltage of the offshore transformer is controlled to be lower than the first voltage.

5. The method according to claim 1, It is characterized in that The method of restoring the operation of the offshore converter station based on the processing method corresponding to the ground fault type includes: When the ground fault type is a two-phase ground fault or a three-phase ground fault, By controlling the converter voltage outer loop, the AC side voltage is raised, and the grid side voltage of the offshore transformer is controlled to be less than the first voltage; In response to the controller triggering the DC voltage dynamic response, the DC energy consumption device is started.

6. A device for handling metallic ground faults. It is characterized in that include: A determination module, used to determine the type of grounding fault currently occurring on the grid side of the transformer according to the grid side voltage of the offshore transformer and the voltage amplitude value of the grid connection point; A first control module, configured to control a DC voltage based on an onshore converter station so as to maintain the DC voltage within a first range; A second control module, configured to control the transmission power to be at a corresponding power value according to the ground fault type; The recovery module is used to restore the operation of the offshore converter station based on the processing method corresponding to the ground fault type.

7. The device according to claim 6, It is characterized in that The determining module is specifically used for: If any phase voltage of the offshore transformer grid-side voltage drops to zero, and the grid-connection point voltage amplitude value drops to a first threshold value, it is determined that the type of ground fault currently occurring on the transformer grid-side is a single-phase ground fault; If any two phase voltages of the offshore transformer grid-side voltage drop to zero, and the grid connection point voltage amplitude value drops to a second threshold, it is determined that the ground fault type is a double-phase ground fault; If the grid-side voltage of the offshore transformer drops to zero, and the voltage amplitude value of the grid connection point drops to a third threshold, it is determined that the ground fault type is a three-phase ground fault. The third threshold is smaller than the second threshold, and the second threshold is smaller than the third threshold.

8. The device according to claim 6, It is characterized in that The second control module is specifically used for: When the ground fault type is a single-phase ground fault, controlling the transmission power to be in a first interval; When the ground fault type is a double-phase ground fault, controlling the transmission power to be in a second interval; When the ground fault type is a three-phase ground fault, the transmission power is controlled to be zero, wherein the value of the first interval is greater than that of the second interval.

9. The device according to claim 6, It is characterized in that The recovery module is specifically used for: When the ground fault type is a single-phase ground fault, During a fault, providing reactive power support within a preset range to the offshore converter station based on the offshore converter; The AC side voltage is controlled to be raised, and the grid side voltage of the offshore transformer is controlled to be lower than the first voltage.

10. The device according to claim 6, It is characterized in that The recovery module is specifically used for: When the ground fault type is a two-phase ground fault or a three-phase ground fault, By controlling the converter voltage outer loop, the AC side voltage is raised, and the grid side voltage of the offshore transformer is controlled to be less than the first voltage; In response to the controller triggering the DC voltage dynamic response, the DC energy consumption device is started.

Images