Method and device for monitoring asymmetric fault of corner joint converter transformer, equipment and storage medium
By monitoring the zero-sequence current of the angle-connected converter transformer, it is determined whether it has a slight asymmetric fault, and the fault type is judged based on the current amplitude, the problem of difficult to identify minor faults in the existing technology is solved, early identification and fault isolation are achieved, and the risk of serious faults is reduced.
Patent Information
- Application Number
- CN202411813627.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-10
- Publication Date
- 2025-02-25
AI Technical Summary
The prior art is difficult to effectively monitor and identify minor asymmetric failures in angular converter transformers, resulting in the possibility of developing serious failures and the inability to start or alarm in traditional electrical quantity protection.
By collecting the three-phase current on the grid side or valve side of the angular converter transformer, calculate the fundamental effective value of the zero-sequence current, and judge whether an asymmetric fault occurs based on the set threshold and duration, and then determine the fault phase and fault type.
It realizes early identification and monitoring of minor asymmetric faults of diagonal converter transformers, and can issue alarms or isolate faults before the fault develops to serious problems, reducing the risk of serious consequences such as detonation and ignition, and is low in cost and high feasibility.
Smart Images
Figure CN119511152A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the field of high-voltage direct current transmission control technology, and in particular to a method and apparatus, device and storage medium for monitoring asymmetric faults of a delta-connected converter transformer. Background Art
[0002] The converter transformer is a vital device in DC transmission projects. It is an important connecting device between AC and DC transmission systems, and plays an important role in AC and DC isolation and providing commutation voltage. Due to the combined effects of AC and DC electric and magnetic fields, the structure of the converter transformer is special and complex, and the key technology is difficult. The fault identification of the converter transformer, especially the early identification technology of minor faults, is a hot research issue.
[0003] The converter transformer is generally equipped with non-electrical quantity protection such as body gas and oil flow relay; electrical quantity protection such as differential protection, saturation protection, overcurrent protection, overvoltage protection. The above electrical quantity and non-electrical quantity protection can only be activated after a serious fault occurs in the converter transformer, thereby eliminating the fault. From the operating experience, when a serious fault occurs in the converter transformer, even if the protection can be quickly activated, serious consequences such as explosion may still occur. When a minor fault occurs in the converter transformer, the main characteristic is the asymmetry of the three-phase impedance, such as a minor turn-to-turn short circuit or an abnormal gear adjustment resulting in inconsistent three-phase ratios. The grid side of the delta-connected converter transformer is star-connected and the neutral point is grounded, while the valve side is delta-connected with the neutral point not grounded. If a slight asymmetric fault occurs, zero-sequence current will flow through both the grid side and the valve side, but this zero-sequence current is relatively small, generally between 40-70A. Traditional related electrical quantity protections include saturation protection and zero-sequence overcurrent protection, and the setting values are generally hundreds or even thousands of amperes. Therefore, when the converter transformer has a slight asymmetric fault, the traditional electrical quantity protection cannot be started or alarmed. However, after a slight asymmetric fault occurs in the converter transformer, it may gradually develop into a serious fault as the operating time increases. Summary of the invention
[0004] In order to solve at least one of the above problems, the present application proposes a method and apparatus, a device and a storage medium for monitoring asymmetric faults of a delta-connected converter transformer.
[0005] According to the first aspect of the present application, at least one embodiment of the present application provides a monitoring method for an asymmetric fault of a delta-connected converter transformer, comprising: collecting the three-phase current on the grid side or valve side of the delta-connected converter transformer; calculating the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer based on the three-phase current on the grid side or valve side; judging whether the fundamental effective value of the zero-sequence current exceeds a first set threshold; when the fundamental effective value of the zero-sequence current exceeds the first set threshold, judging whether the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold exceeds a first set time; when the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold exceeds the first set time, determining that an asymmetric fault occurs in the delta-connected converter transformer; when an asymmetric fault occurs in the delta-connected converter transformer, judging the fault phase and fault type based on the amplitude of the three-phase current on the grid side or valve side.
[0006] For example, in some embodiments of the present application, the fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer is calculated according to the following formula:
[0007] I0=I a +I b +I c
[0008] Among them, I a ,I b ,I c is the three-phase current on the grid side or valve side of the delta-connected converter transformer, and I0 is the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer.
[0009] For example, in some embodiments of the present application, the first set threshold is less than the fundamental effective value of the zero-sequence current on the grid side or the valve side of the delta-connected converter transformer when there is a one-level difference in phase difference between the three phases of the delta-connected converter transformer.
[0010] For example, in some embodiments of the present application, the first set time is greater than the duration of the inherent asymmetric transient process generated by the delta-connected converter transformer when shifting gears.
[0011] For example, in some embodiments of the present application, when an asymmetric fault occurs in the delta-connected converter transformer, the fault phase and fault type are judged according to the amplitude of the three-phase current on the grid side or valve side, including: among the three-phase current on the grid side or valve side, if the absolute value of the difference between the grid-side or valve-side current amplitude of one phase and the grid-side or valve-side current amplitudes of the other two phases is greater than a second set threshold, then it is determined that the converter transformer of the one phase is faulty.
[0012] For example, in some embodiments of the present application, when an asymmetric fault occurs in the delta-connected converter transformer, the fault phase and the fault type are judged according to the amplitude of the three-phase current on the grid side or the valve side, and it also includes: when the grid-side or valve-side current amplitude of the fault phase is greater than the grid-side or valve-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-down gear adjustment abnormality and / or a valve-side turn-to-turn short circuit; when the grid-side or valve-side current amplitude of the fault phase is less than the grid-side or valve-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-up gear adjustment abnormality and / or a grid-side or valve-side turn-to-turn short circuit.
[0013] For example, in some embodiments of the present application, it also includes: in the event of an asymmetric fault in the delta-connected converter transformer, issuing an alarm signal and / or disconnecting the AC switch of the delta-connected converter transformer.
[0014] According to the second aspect of the present application, at least one embodiment of the present application provides a monitoring device for an asymmetric fault of a delta-connected converter transformer, which is used to execute the monitoring method described in any one of the first aspects, and the monitoring device includes: a current monitoring unit, which is used to collect the three-phase current on the grid side or valve side of the delta-connected converter transformer, and calculate the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer according to the three-phase current on the grid side or valve side; a judgment unit, which is used to judge whether the fundamental effective value of the zero-sequence current exceeds a first set threshold; and when the fundamental effective value of the zero-sequence current exceeds the first set threshold, judge whether the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold exceeds a first set time; and is also used to determine that an asymmetric fault occurs in the delta-connected converter transformer when the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold exceeds the first set time; and when an asymmetric fault occurs in the delta-connected converter transformer, judge the fault phase and fault type according to the amplitude of the three-phase current on the grid side or valve side.
[0015] According to the third aspect of the present application, at least one embodiment of the present application provides an electronic device, comprising: one or more processors; a memory for storing one or more programs; when the one or more programs are executed by the one or more processors, the one or more processors execute a method as described in any one of the first aspects.
[0016] According to a fourth aspect of the present application, at least one embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, wherein the program, when executed by a processor, implements the method as described in any one of the first aspects.
[0017] Through the above-mentioned example embodiments, the present application provides a method and device for monitoring asymmetric faults of delta-connected converter transformers. By monitoring the zero-sequence current on the grid side or the valve side, it is determined whether a slight asymmetric fault occurs in the converter transformer. The fault phase and fault type can be determined based on the current amplitude of each phase, and an alarm can be issued or the AC switch can be tripped to isolate the faulty converter transformer before a serious fault develops. Compared with the existing electrical quantity protection, no additional voltage or current is added, and the implementation cost is low and the feasibility is high.
[0018] It should be understood that the foregoing general description and the following detailed description are exemplary only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] By describing in detail exemplary embodiments thereof with reference to the accompanying drawings, the above and other objects, features and advantages of the present application will become more apparent. The accompanying drawings described below are only some embodiments of the present application, and are not intended to limit the present application.
[0020] Figure 1 A wiring diagram showing an exemplary delta-connected converter transformer;
[0021] Figure 2 A flow chart showing a method for monitoring an asymmetric fault of a delta-connected converter transformer according to an exemplary embodiment;
[0022] Figure 3 A schematic diagram of a monitoring device for an asymmetric fault of a delta-connected converter transformer according to an exemplary embodiment is shown;
[0023] Figure 4 A structural diagram of an electronic device provided by the present application is shown. DETAILED DESCRIPTION
[0024] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this application will be comprehensive and complete and will fully convey the concepts of the example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar parts, and thus their repeated description will be omitted.
[0025] The described features, structures or characteristics may be combined in one or more embodiments in any suitable manner. In the following description, many specific details are provided to provide a full understanding of the embodiments of the present disclosure. However, those skilled in the art will appreciate that the technical solutions of the present disclosure may be practiced without one or more of these specific details, or other modes, components, materials, devices, etc. may be adopted. In these cases, known structures, methods, devices, implementations, materials or operations will not be shown or described in detail.
[0026] The flowcharts shown in the accompanying drawings are only exemplary and do not necessarily include all the contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps can be decomposed, and some operations / steps can be combined or partially combined, so the actual execution order may change according to actual conditions.
[0027] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, methods, products or devices.
[0028] Those skilled in the art will appreciate that the drawings are merely schematic diagrams of example embodiments, and the modules or processes in the drawings are not necessarily necessary for implementing the present application, and therefore cannot be used to limit the scope of protection of the present application.
[0029] Figure 1 A connection diagram of an exemplary delta-connected converter transformer is shown.
[0030] like Figure 1 As shown, the delta-connected converter transformer includes three phases, the grid side of which is star-connected and the neutral point is directly grounded, and the valve side is delta-connected and the neutral point is not grounded.
[0031] Figure 2 A flow chart of a method for monitoring an asymmetric fault of a delta-connected converter transformer according to an exemplary embodiment is shown.
[0032] like Figure 2 As shown, the monitoring method for asymmetric faults of delta-connected converter transformers includes steps S201-S205:
[0033] In step S201, the grid-side three-phase current of the delta-connected converter transformer is collected.
[0034] According to the embodiment, the grid-side three-phase current I of the delta-connected converter transformer is collected. a ,I b ,I c .
[0035] In step S202, the fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer is calculated according to the three-phase current on the grid side.
[0036] According to an exemplary embodiment, the fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer is calculated according to the following formula:
[0037] I0=I a +I b +I c
[0038] Among them, I a ,I b ,I c is the three-phase current on the grid side of the delta-connected converter transformer, and I0 is the fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer.
[0039] In step S203, it is determined whether the fundamental effective value of the zero-sequence current exceeds a first set threshold.
[0040] According to the exemplary embodiment, it is determined whether the fundamental effective value I0 of the zero-sequence current exceeds the first set threshold value. If it exceeds, it goes to step S204; if it does not exceed, it goes to step S201. The first set threshold value is less than the fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer when there is a one-stage difference between the three phases of the delta-connected converter transformer. The first set threshold value can be selected as a typical value of 60A, and this application only takes this as an example, but is not limited to this.
[0041] In step S204, it is determined whether the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold exceeds the first set time.
[0042] According to the example embodiment, it is determined whether the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold value exceeds the first set time: when the fundamental effective value of the zero-sequence current exceeds the first set threshold value and lasts for the first set time, it is determined that an asymmetric fault has occurred in the delta-connected converter transformer, and the process goes to step S205; when the fundamental effective value of the zero-sequence current exceeds the first set threshold value but does not last for the first set time, the process goes to step S201.
[0043] According to an exemplary embodiment, the first set time is greater than the duration of the inherent asymmetric transient process generated by the delta-connected converter transformer when the converter transformer is shifted. The first set time can be selected as a typical value of 5s, which is only taken as an example in this application, but is not limited thereto.
[0044] In step S205, when an asymmetric fault occurs in the delta-connected converter transformer, the fault phase and the fault type are determined according to the amplitude of the three-phase current on the grid side.
[0045] According to an exemplary embodiment, in the case of an asymmetric fault in a delta-connected converter transformer, judging the fault phase and fault type according to the amplitude of the three-phase current on the grid side includes: judging whether the absolute value ΔM of the difference between the grid-side current amplitude of one phase and the grid-side current amplitude of the other two phases is greater than a second set threshold value in the three-phase current on the grid side. If so, it is determined that the converter transformer of the phase is faulty and the phase is a faulty phase.
[0046] The second set threshold value may be a typical value of 10A, and this application only takes this as an example, but is not limited thereto.
[0047] According to some embodiments, when the grid-side current amplitude of the faulty phase is greater than the grid-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-down gear adjustment abnormality and / or a valve-side turn-to-turn short circuit; when the grid-side current amplitude of the faulty phase is less than the grid-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-up gear adjustment abnormality and / or a grid-side turn-to-turn short circuit.
[0048] According to some embodiments, the monitoring method of the present application further includes: in the event of an asymmetric fault in the delta-connected converter transformer, issuing an alarm signal and / or disconnecting the AC switch of the delta-connected converter transformer to isolate the faulty delta-connected converter transformer.
[0049] According to some embodiments, Figure 2 In the monitoring method for asymmetric faults of a delta-connected converter transformer in the embodiment, the grid-side current can be completely replaced by the valve-side current, and the first set threshold and the second set threshold are adjusted according to the transformation ratio.
[0050] The monitoring method using valve side current as an alternative includes the following steps:
[0051] Collect the three-phase current on the valve side of the delta-connected converter transformer;
[0052] Calculate the fundamental effective value of the zero-sequence current on the valve side of the delta-connected converter transformer according to the three-phase current on the valve side;
[0053] Determining whether the fundamental effective value of the zero-sequence current exceeds a first set threshold;
[0054] If it does not exceed, continue to collect the three-phase current on the valve side of the delta-connected converter transformer;
[0055] If exceeded, determining whether the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold value exceeds the first set time;
[0056] When the fundamental effective value of the zero-sequence current exceeds the first set threshold value but does not continue for the first set time, the valve-side three-phase current of the delta-connected converter transformer continues to be collected;
[0057] When the fundamental effective value of the zero-sequence current exceeds a first set threshold value and lasts for a first set time, it is determined that an asymmetric fault occurs in the delta-connected converter transformer;
[0058] In the event of an asymmetric fault in a delta-connected converter transformer, the fault phase and fault type are determined based on the amplitude of the three-phase current on the valve side.
[0059] Among them, the valve side three-phase current I of the delta-connected converter transformer is collected a ,I b ,I c .
[0060] The fundamental effective value of the zero-sequence current on the valve side of the delta-connected converter transformer is calculated according to the following formula:
[0061] I0=I a +I b +I c
[0062] Among them, I a ,I b ,I c is the three-phase current on the valve side of the delta-connected converter transformer, and I0 is the fundamental effective value of the zero-sequence current on the valve side of the delta-connected converter transformer.
[0063] The first set threshold is less than the fundamental effective value of the zero-sequence current on the valve side of the delta-connected converter transformer when the phase difference between the three phases of the delta-connected converter transformer is one level difference. The first set threshold can be selected as a typical value of 60A, which is used as an example in this application, but is not limited thereto.
[0064] According to some embodiments, in the case of an asymmetric fault in a delta-connected converter transformer, judging the fault phase and fault type according to the amplitude of the three-phase current on the valve side includes: judging whether the absolute value ΔM of the difference between the valve side current amplitude of one phase and the valve side current amplitude of the other two phases is greater than a second set threshold value in the three-phase current on the valve side. If so, it is determined that the converter transformer of the phase is faulty and the phase is a faulty phase.
[0065] According to some embodiments, when the valve-side current amplitude of the faulty phase is greater than the valve-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-down gear adjustment abnormality and / or a valve-side turn-to-turn short circuit; when the valve-side current amplitude of the faulty phase is less than the valve-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-up gear adjustment abnormality and / or a grid-side turn-to-turn short circuit.
[0066] The present application also provides a monitoring device for asymmetric faults of a delta-connected converter transformer.
[0067] like Figure 3 As shown, the monitoring device includes: a current monitoring unit 301 and a judgment unit 302 .
[0068] The current monitoring unit 301 is used to collect the three-phase current on the grid side or valve side of the delta-connected converter transformer, and calculate the fundamental effective value of the zero-sequence current of the delta-connected converter transformer according to the three-phase current on the grid side or valve side.
[0069] The judgment unit 302 is used to judge whether the fundamental effective value of the zero-sequence current exceeds the first set threshold value; and when the fundamental effective value of the zero-sequence current exceeds the first set threshold value, judge whether the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold value exceeds the first set time; it is also used to determine that an asymmetric fault has occurred in the delta-connected converter transformer when the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold value exceeds the first set time; and when an asymmetric fault has occurred in the delta-connected converter transformer, judge the fault phase and fault type according to the amplitude of the three-phase current on the grid side or the valve side.
[0070] According to some embodiments, the monitoring device further comprises an action unit 303. The action unit 303 is used to send an alarm signal and / or disconnect the AC switch of the delta-connected converter transformer to isolate the faulty delta-connected converter transformer when an asymmetric fault occurs in the delta-connected converter transformer.
[0071] The monitoring device is used to execute the monitoring method for asymmetric faults of delta-connected converter transformers as described above, so it will not be described in detail here.
[0072] The present application provides a monitoring method and device for asymmetric faults of a delta-connected converter transformer. By monitoring the zero-sequence current on the grid side or the valve side, it is determined whether a slight asymmetric fault has occurred in the converter transformer. The faulty phase and fault type can be determined based on the current amplitude of each phase. An alarm can be issued or an AC switch can be tripped to isolate the faulty converter transformer before a serious fault develops. Compared with existing electrical quantity protection, no additional voltage or current is added, and the implementation cost is low and the feasibility is high.
[0073] Figure 4 A structural diagram of an electronic device provided by the present application is shown.
[0074] See also Figure 4 , Figure 4 An electronic device is provided, comprising a processor and a memory. The memory stores computer instructions. When the computer instructions are executed by the processor, the processor executes the computer instructions to achieve the following Figure 2 The method and refinement scheme shown.
[0075] It should be understood that the above-mentioned device embodiments are only illustrative, and the device disclosed in the present application can also be implemented in other ways. For example, the division of units / modules in the above-mentioned embodiments is only a logical function division, and there may be other division methods in actual implementation. For example, multiple units, modules or components can be combined, or can be integrated into another system, or some features can be ignored or not executed.
[0076] In addition, unless otherwise specified, each functional unit / module in each embodiment of the present application may be integrated into one unit / module, each unit / module may exist physically separately, or two or more units / modules may be integrated together. The above-mentioned integrated unit / module may be implemented in the form of hardware or in the form of a software program module.
[0077] If the integrated unit / module is implemented in the form of hardware, the hardware may be a digital circuit, an analog circuit, etc. The physical implementation of the hardware structure includes but is not limited to transistors, memristors, etc. Unless otherwise specified, the processor or chip may be any appropriate hardware processor, such as CPU, GPU, FPGA, DSP, and ASIC, etc. Unless otherwise specified, the on-chip cache, off-chip memory, and storage may be any appropriate magnetic storage medium or magneto-optical storage medium, such as Resistive Random Access Memory (RRAM), Dynamic Random Access Memory (DRAM), Static Random Access Memory (SRAM), Enhanced Dynamic Random Access Memory (EDRAM), High-Bandwidth Memory (HBM), Hybrid Memory Cube (HMC), etc.
[0078] If the integrated unit / module is implemented in the form of a software program module and sold or used as an independent product, it can be stored in a computer-readable memory. Based on this understanding, the technical solution of the present application, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, which is stored in a memory and includes several instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the various embodiments of the present disclosure. The aforementioned memory includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk, etc. Various media that can store program codes.
[0079] The present application also provides a non-transitory computer storage medium storing a computer program. When the computer program is executed by multiple processors, the processors execute the following Figure 2 The method and refinement scheme shown.
[0080] It should be clearly understood that the present application describes how to form and use specific examples, but the present application is not limited to any details of these examples. On the contrary, based on the teaching of the content disclosed in the present application, these principles can be applied to many other embodiments.
[0081] In addition, it should be noted that the above figures are only schematic illustrations of the processes included in the method according to the exemplary embodiments of the present application, and are not intended to be limiting. It is easy to understand that the processes shown in the above figures do not indicate or limit the time sequence of these processes. In addition, it is also easy to understand that these processes can be performed synchronously or asynchronously, for example, in multiple modules.
[0082] The exemplary embodiments of the present application are specifically shown and described above. It should be understood that the present application is not limited to the detailed structures, configurations or implementations described herein; on the contrary, the present application is intended to cover various modifications and equivalent configurations included in the ideas and scope of the appended claims.
Claims
1. A method for monitoring asymmetric faults of delta-connected converter transformers, characterized in that: include: Collecting the three-phase current on the grid side or valve side of the delta-connected converter transformer; Calculating the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer according to the three-phase current on the grid side or valve side; Determining whether the fundamental effective value of the zero-sequence current exceeds a first set threshold; In the case where the fundamental effective value of the zero-sequence current exceeds the first set threshold, determining whether the duration for which the fundamental effective value of the zero-sequence current exceeds the first set threshold exceeds a first set time; When the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold value exceeds the first set time, it is determined that an asymmetric fault occurs in the delta-connected converter transformer; In the event of an asymmetric fault occurring in the delta-connected converter transformer, the fault phase and the fault type are determined based on the amplitude of the three-phase current on the grid side or the valve side.
2. The monitoring method according to claim 1, characterized in that: The fundamental effective value of the zero-sequence current on the grid side of the delta-connected converter transformer is calculated according to the following formula: I0=I a +I b +I c Among them, I a ,I b ,I c is the three-phase current on the grid side or valve side of the delta-connected converter transformer, and I0 is the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer.
3. The monitoring method according to claim 1, characterized in that: The first set threshold is smaller than the fundamental effective value of the zero-sequence current on the grid side or the valve side of the delta-connected converter transformer when there is one level difference in phase difference between the three phases of the delta-connected converter transformer.
4. The monitoring method according to claim 1, characterized in that: The first set time is greater than the duration of the inherent asymmetric transient process generated by the delta-connected converter transformer when the transformer is shifted.
5. The monitoring method according to claim 1, characterized in that: In the case where an asymmetric fault occurs in the delta-connected converter transformer, judging the fault phase and the fault type according to the amplitude of the three-phase current on the grid side or the valve side includes: If, among the three-phase currents on the grid side or valve side, the absolute value of the difference between the grid side or valve side current amplitude of one phase and the grid side or valve side current amplitudes of the other two phases is greater than the second set threshold, it is determined that the converter transformer of the one phase is faulty.
6. The monitoring method according to claim 5, characterized in that: In the case where an asymmetric fault occurs in the delta-connected converter transformer, judging the fault phase and the fault type according to the amplitude of the three-phase current on the grid side or the valve side, further comprising: When the grid-side or valve-side current amplitude of the faulty phase is greater than the grid-side or valve-side current amplitudes of the other two phases, it is determined that the delta-connected converter transformer has a step-down gear adjustment abnormality and / or a valve-side turn-to-turn short circuit; When the grid-side or valve-side current amplitude of the faulty phase is smaller than the grid-side or valve-side current amplitudes of other two phases, it is determined that the delta-connected converter transformer has a step-up gear adjustment abnormality and / or a grid-side or valve-side turn-to-turn short circuit.
7. The monitoring method according to claim 1, characterized in that: Also includes: In the event of an asymmetric fault occurring in the delta-connected converter transformer, an alarm signal is issued and / or an AC switch of the delta-connected converter transformer is disconnected.
8. A monitoring device for asymmetric faults of delta-connected converter transformers, characterized in that: Used to perform the monitoring method according to any one of claims 1 to 7, the monitoring device comprises: A current monitoring unit, used for collecting the three-phase current on the grid side or valve side of the delta-connected converter transformer, and calculating the fundamental effective value of the zero-sequence current on the grid side or valve side of the delta-connected converter transformer according to the three-phase current on the grid side or valve side; A judgment unit is used to judge whether the fundamental effective value of the zero-sequence current exceeds a first set threshold value; and when the fundamental effective value of the zero-sequence current exceeds the first set threshold value, judge whether the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold value exceeds a first set time; and is also used to determine that an asymmetric fault occurs in the delta-connected converter transformer when the duration of the fundamental effective value of the zero-sequence current exceeding the first set threshold value exceeds the first set time; and when an asymmetric fault occurs in the delta-connected converter transformer, judge the fault phase and fault type according to the amplitude of the three-phase current on the grid side or the valve side.
9. An electronic device, characterized in that: include: one or more processors; A memory for storing one or more programs; When the one or more programs are executed by the one or more processors, the one or more processors perform the method according to any one of claims 1 to 7.
10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the method according to any one of claims 1 to 7 is implemented.