Stability verification method, system and device, controller, medium and program product

Abstract

The invention relates to a stability verification method, system and device, a controller, a medium and a program product. The method comprises the following steps: acquiring the type of a to-be-verified target DC power transmission topology; according to the type of the target direct-current power transmission topology, a target equivalent subsystem corresponding to the target direct-current power transmission topology is built through a plurality of current converters in a direct-current equivalent system; a plurality of current converters in the direct current equivalent system are combined and connected through switches and are used for building equivalent subsystems corresponding to different types of direct current power transmission topologies; performing a simulation twin-trawling test on each converter in the target equivalent subsystem to obtain a plurality of simulation electrical parameters; and determining a stability verification result of the target DC power transmission topology according to the plurality of simulated electrical parameters. By adopting the method, stability verification can be more simply and conveniently carried out on various direct-current transmission topologies.

Description

Technical Field

[0001] The present application relates to the field of direct current transmission technology, and in particular to a stability verification method, system, device, controller, medium and program product. Background Art

[0002] For scenarios such as Shagohuang New Energy and integrated water, wind and solar bases, DC transmission needs to comprehensively consider grid constraints on the inverter side, grid support in multiple application scenarios, high and low voltage ride-through, and commutation failure resistance. The transmission topology in such scenarios includes a variety of different types of DC transmission topologies.

[0003] In the related art, for various DC transmission topologies, the reliability of the converter in each DC transmission topology is mainly verified respectively, and the stability of each DC transmission topology is determined based on the verification results. However, the reliability verification method is relatively complicated.

[0004] Therefore, there is an urgent need for a method that can more easily verify the stability of various DC transmission topologies. Summary of the invention

[0005] Based on this, it is necessary to provide a stability verification method, system, device, controller, medium and program product to address the above technical problems, which can more easily verify the stability of various DC transmission topologies.

[0006] In a first aspect, the present application provides a stability verification method, comprising:

[0007] Obtaining the type of target DC transmission topology to be verified;

[0008] According to the type of the target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is constructed by using multiple converters in the DC equivalent system; multiple converters in the DC equivalent system are combined and connected through switches to construct equivalent subsystems corresponding to different types of DC transmission topologies;

[0009] Conduct simulated parallel-drag tests on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters;

[0010] Based on multiple simulated electrical parameters, the stability verification results of the target DC transmission topology are determined.

[0011] In one embodiment, obtaining the type of the target DC transmission topology to be verified includes:

[0012] According to the topological structure of the target DC power transmission topology to be verified, at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC power transmission topology are determined.

[0013] In one of the embodiments, according to the type of the target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is constructed by using multiple converters in the DC equivalent system, including:

[0014] Screening out a rectifier-side target converter that matches the type of at least one converter on the rectifier side from a plurality of converters in the DC equivalent system, and screening out an inverter-side target converter that matches the type of at least one converter on the inverter side from a plurality of converters;

[0015] The switches between each rectifier-side target converter and each inverter-side target converter are controlled to be turned on, and the switches between other converters except the rectifier-side target converter and the inverter-side target converter are controlled to be turned off, so as to obtain a target equivalent subsystem corresponding to the target DC transmission topology.

[0016] In one of the embodiments, the plurality of converters in the target equivalent subsystem include a fixed converter and a converter to be verified;

[0017] Perform a simulated drag test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters, including:

[0018] The fixed converter in the target equivalent subsystem is controlled to perform a simulated towing test on the converter to be verified, so as to obtain a plurality of simulated electrical parameters of the converter to be verified under the test conditions.

[0019] In one embodiment, controlling a fixed converter in a target equivalent subsystem to perform a simulated towing test on a converter to be verified includes:

[0020] When the number of fixed converters is one, a simulated towing test is performed on the converter to be verified by towing the fixed converter at both ends;

[0021] When there are two fixed converters, a simulated pair-drag test is performed on the converter to be verified in a three-terminal pair-drag manner by two fixed converters connected in series; wherein the two fixed converters connected in series are two converters on the rectifier side or the inverter side.

[0022] In one embodiment, determining a stability verification result of a target DC transmission topology based on a plurality of simulated electrical parameters includes:

[0023] Determine a reliability verification result of the converter to be verified according to a plurality of simulated electrical parameters;

[0024] Based on the reliability verification results, the stability verification results of the target DC transmission topology are obtained.

[0025] In one embodiment, determining the reliability verification result of the converter to be verified according to a plurality of simulated electrical parameters includes:

[0026] comparing a plurality of simulated electrical parameters to preset threshold ranges;

[0027] If the multiple simulated electrical parameters are all within the preset threshold range, it is determined that the reliability verification of the converter to be verified has passed;

[0028] If any of the simulated electrical parameters is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has failed.

[0029] In one embodiment, the method further comprises:

[0030] Inputting voltage disturbance signals of different levels into the target equivalent subsystem;

[0031] Under the condition of voltage disturbance signal input at each level, the steps of performing a simulated towing test on each converter in the target equivalent subsystem are performed.

[0032] In a second aspect, the present application also provides a stability verification system, which includes a controller and a DC equivalent system, wherein the DC equivalent system includes a plurality of converters, and the plurality of converters are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies;

[0033] The controller is used to obtain the type of the target DC transmission topology to be verified; according to the type of the target DC transmission topology, build a target equivalent subsystem corresponding to the target DC transmission topology through multiple converters in the DC equivalent system; perform a simulated pair-drag test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters; and determine the stability verification result of the target DC transmission topology according to the multiple simulated electrical parameters.

[0034] In one of the embodiments, the plurality of converters in the target equivalent subsystem include a fixed converter and a converter to be verified;

[0035] The controller is used for controlling the conduction of switches between the fixed converters when the number of the fixed converters is two.

[0036] In one of the embodiments, the plurality of converters include at least one rectifier-side converter and at least one inverter-side converter;

[0037] Each converter in at least one rectifier-side converter is connected to each converter in at least one inverter-side converter via a first switch, the converters in at least one rectifier-side converter are connected to each other via a second switch, and the converters in at least one inverter-side converter are connected to each other via a third switch.

[0038] In one of the embodiments, the DC equivalent system further includes a ripple suppression device, and each converter of at least one rectifier-side converter and each converter of at least one inverter-side converter are connected to the ripple suppression device via a first switch;

[0039] The ripple suppression device is used to suppress the ripple in the output rectified voltage of the rectifier-side converter.

[0040] In one of the embodiments, the DC equivalent system further includes a voltage disturbance device, and the voltage disturbance device is connected to the output terminal of the inverter-side converter;

[0041] Voltage disturbance equipment, used to introduce voltage disturbance signals into the DC equivalent system;

[0042] The controller is used to verify the stability of the target equivalent subsystem when the inverter-side converter is disturbed by a voltage disturbance signal.

[0043] In one of the embodiments, the voltage disturbance device includes a voltage regulating device and a voltage regulating switch, and the voltage regulating device is connected to the inverter-side converter through the voltage regulating switch;

[0044] Voltage regulating equipment, used to adjust the amplitude and phase of the output voltage of the AC power supply;

[0045] The voltage regulating switch is used to adjust the magnitude of the adjusted AC voltage within a preset adjustment range to form a voltage disturbance signal.

[0046] In one of the embodiments, the DC equivalent system further includes an AC filter device, which is arranged on the AC bus and is respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter;

[0047] AC filtering equipment is used to filter out the harmonics generated by the DC equivalent system during the test.

[0048] In one of the embodiments, the AC filter device includes at least two filters, and the at least two filters are respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter;

[0049] At least two filters are used to filter out harmonics of different frequencies in the DC equivalent system.

[0050] In one of the embodiments, the DC equivalent system further includes a voltage conversion device, which is respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter;

[0051] Voltage conversion equipment is used to convert AC voltage into DC voltage and to insulate the DC voltage from the AC voltage.

[0052] In one of the embodiments, the voltage conversion device includes a first converter transformer and a second converter transformer, the first converter transformer is connected to the input end of the rectifier-side converter, and the second converter transformer is connected to the output end of the inverter-side converter.

[0053] In a third aspect, the present application also provides a stability verification device, comprising:

[0054] An acquisition module, used for acquiring the type of target DC transmission topology to be verified;

[0055] A building module is used to build a target equivalent subsystem corresponding to the target DC transmission topology through multiple converters in the DC equivalent system according to the type of the target DC transmission topology; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies;

[0056] A test module is used to perform a simulated towing test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters;

[0057] The determination module is used to determine the stability verification result of the target direct current transmission topology according to a plurality of simulated electrical parameters.

[0058] In a fourth aspect, the present application further provides a controller comprising a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, the content of any one of the stability verification methods in the first aspect is implemented.

[0059] In a fifth aspect, the present application further provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the content of any one of the stability verification methods in the first aspect above.

[0060] In a sixth aspect, the present application further provides a computer program product, including a computer program, which, when executed by a processor, implements the content of any one of the stability verification methods in the first aspect above.

[0061] The above stability verification method, system, device, controller, medium and program product obtain the type of target DC transmission topology to be verified; according to the type of target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is built through multiple converters in the DC equivalent system; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies; simulated pair-drag tests are performed on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters; and the stability verification result of the target DC transmission topology is determined according to the multiple simulated electrical parameters. The multiple converters in the DC equivalent system in the method can be connected in any combination through switches to build equivalent subsystems corresponding to different types of DC transmission topologies, that is, multiple equivalent subsystems of different types can be built through one DC equivalent system. Then, through this one DC equivalent system, multiple converters of multiple different types of target equivalent subsystems can be simulated pair-drag tests, which reduces the complexity of the reliability verification method of multiple DC transmission topologies, so that the stability of equivalent systems of multiple DC transmission topologies can be verified more easily. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] In order to more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the drawings required for use in the embodiments of the present application or related technical descriptions will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0063] Figure 1 An application environment diagram of a stability verification method in an embodiment;

[0064] Figure 2 A schematic diagram of a first process flow of a stability verification method in one embodiment;

[0065] Figure 3 A second flow chart of a stability verification method in one embodiment;

[0066] Figure 4a A first schematic diagram of a two-end drag test in one embodiment;

[0067] Figure 4b A second schematic diagram of a two-end drag test in one embodiment;

[0068] Figure 4c A third schematic diagram of a two-end drag test in one embodiment;

[0069] Figure 4d A schematic diagram of a three-terminal drag test in an embodiment;

[0070] Figure 5 A third flow chart of a stability verification method in one embodiment;

[0071] Figure 6 A fourth flow chart of a stability verification method in one embodiment;

[0072] Figure 7 A fifth flow chart of a stability verification method in one embodiment;

[0073] Figure 8 A sixth flow chart of a stability verification method in one embodiment;

[0074] Fig. 9 is a schematic diagram of a stability verification system in one embodiment;

[0075] Fig.10 A schematic diagram of the structure of an IGBT-MMC in one embodiment;

[0076] Fig.11 A schematic diagram of the structure of a 12-pulse LCC in one embodiment;

[0077] Fig.12 is a schematic structural diagram of a 12-pulse converter based on IGCT in one embodiment;

[0078] Fig.13 is a schematic structural diagram of a CSC based on IGCT in one embodiment;

[0079] Fig.14 is a first schematic diagram of a DC equivalent system in one embodiment;

[0080] Fig.15 is a second schematic diagram of a DC equivalent system in one embodiment;

[0081] Fig.16 FIG. 4 is a structural block diagram of a stability verification device in one embodiment.

[0082] Description of reference numerals:

[0083] 10: controller; 11: DC equivalent system; 12: multiple converters; 121: rectifier side converter; 122: inverter side converter; 13: switch; 131: first switch; 132: second switch; 133: third switch; 14: target equivalent subsystem; 15: ripple suppression device; 151: smoothing reactor; 16: voltage disturbance device; 161: voltage regulation device; 162: voltage regulating switch; 17: AC filtering device; 171: filter; 18: voltage conversion device; 181: first converter transformer; 182: second converter transformer. DETAILED DESCRIPTION

[0084] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0085] Before introducing the technical solution of the present application in detail, a brief introduction to the background technology of the present application is first given.

[0086] For scenarios such as Shagohuang New Energy and integrated water, wind and solar bases, the DC transmission process needs to comprehensively consider the grid constraints on the rectifier and inverter sides, grid support in multiple application scenarios, high and low voltage ride-through, and commutation failure resistance. The transmission topology in such scenarios includes many different types of DC transmission topologies.

[0087] In the related art, for various DC transmission topologies, the reliability of the converter in each DC transmission topology is mainly verified respectively, and the stability of each DC transmission topology is determined based on the verification result.

[0088] In the process of reliability verification of the converter in any DC transmission topology, the converter is usually directly subjected to a towing test to determine the reliability of the converter. For example, for conventional DC converters, a full-power 6-pulse back-to-back test circuit can be used for reliability verification. For flexible DC converters, a 48-hour power towing test is usually required before the technology is finalized. Since the flexible DC converter is composed of multiple cascaded submodules, all submodules need to undergo a 3-6-hour power towing test. For converters based on integrated gate commutated thyristors (IGCTs), compared with conventional DC converters and flexible DC converters, the devices, device-level protection circuits, valve assembly structures, valve assembly working modes, control and protection strategies in IGCT-based converters are designed with new technologies, and an equivalent system is urgently needed to conduct towing tests to verify the reliability of IGCT-based converters.

[0089] In addition, through research and analysis, most of the converters that are tested in domestic valve factories are of the same model, for example, Line Commuted Converter (LCC) to LCC, Modular Multilevel Converter (MMC) to MMC. The power of the converter is to test the conduction capacity of the current. The operating power of LCC and MMC is relatively small. The current of the towing device including MMC does not exceed 3000A, and the current of the towing device of LCC can reach 5000A. However, the voltage of each level of the device in the converter is relatively low, usually only a few hundred volts, which does not reach the actual operating voltage of the corresponding level of devices.

[0090] The existing towing test equipment is insufficient for the control function of DC transmission topology and transient stress assessment of valve components, and reliability verification is mainly carried out through low-voltage dynamic model experiments. However, the existing low-voltage dynamic model platform only supports the research of specific topology commutation equipment and has a limited scope of application. Due to the large differences in IGCTs and the lack of low-voltage and low-power IGCT devices for equivalent testing, the existing dynamic model platform cannot support the reliability verification process of new converters (for example, converters based on IGCTs).

[0091] According to the analysis of the statistical data of converter failure, it is not difficult to see that the failure caused by power device failure accounts for more than 33%, which is the component with the highest failure rate in the converter. IGCT devices are the core components of the new converter and are used for the first time in hybrid commutation converters (HCC). The reliability of IGCT devices directly affects the function of HCC. In order to fully evaluate the long-term operation function of IGCT devices and valve assemblies, it is necessary to conduct a continuous operation test of no less than 1000 hours with reference to the power device reliability test standard. And the device voltage and current in the test device should refer to the voltage and current during the actual operation process.

[0092] In response to the above problems, the present application provides a stability verification method, system, device, controller, medium and program product. Multiple converters in a DC equivalent system can be connected in any combination through switches to build equivalent subsystems corresponding to different types of DC transmission topologies. In this way, the operation of various DC transmission topologies can be simulated through a DC equivalent system to obtain the reliability of the converter of each DC transmission topology, thereby determining the stability of each DC transmission topology. That is, the DC equivalent system has the ability to verify the stability of various DC transmission topologies, and various DC transmission topologies include various types of converters, such as LCC, MMC and HCC. HCC is regarded as a new type of converter. Then, the stability verification method can perform full voltage and full current reliability verification on the new converter. In other words, the stability verification method provided by the present application can more easily verify the reliability of different types of converters, so that the stability of various DC transmission topologies can be verified based on the reliability verification results.

[0093] Of course, the technical solution provided in the embodiments of the present application is not limited to solving the above-mentioned problems, but also has other technical effects, which can be specifically described in the following embodiments.

[0094] The stability verification method provided in the embodiment of the present application can be applied to Figure 1 In the application environment shown. The controller in the application environment can be a server, a personal computer, a laptop, a smart phone, a tablet computer, a smart mobile phone, etc. The controller may include a processor, a memory and a network interface connected via a system bus or wirelessly. Among them, the processor of the controller is used to provide computing and control capabilities. The memory of the controller may include a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the controller is used to store data in the stability verification process. The network interface of the computer device is used to communicate with an external terminal through a network connection, and the computer program is executed by the processor to implement a stability verification method.

[0095] In an exemplary embodiment, Figure 2 As shown, a stability verification method is provided, which is applied to Figure 1 The controller in FIG. 1 is taken as an example to illustrate the method, which includes the following steps 201 to 204. Among them:

[0096] S201: Obtain the type of the target direct current transmission topology to be verified.

[0097] The type of the target DC transmission topology may be a high voltage DC transmission topology, a flexible DC transmission topology, etc.

[0098] In an embodiment of the present application, the controller may obtain the target DC transmission topology to be verified, and analyze the target DC transmission topology according to the classification rule of the DC transmission topology to determine the type of the target DC transmission topology. Alternatively, the target DC transmission topology may carry the corresponding type identifier in different ways, for example, in the form of text, a QR code, etc. The controller may identify the text or QR code of the target DC transmission topology to determine the type of the target DC transmission topology.

[0099] S202: According to the type of the target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is constructed by using multiple converters in the DC equivalent system; multiple converters in the DC equivalent system are combined and connected through switches to construct equivalent subsystems corresponding to different types of DC transmission topologies.

[0100] Among them, the multiple converters in the DC equivalent system may include all converter types corresponding to different types of DC transmission topologies, such as LCC, MMC, HCC, and current source converter (CSC), etc. Different types of converters can be combined into different types of DC transmission topologies. For example, when the converters on the rectifier side and the inverter side are both LCC, the DC transmission topology constructed is a high-voltage DC transmission topology; when the converters on the rectifier side and the inverter side are both MMC, the DC transmission topology constructed is a flexible DC transmission topology.

[0101] In an embodiment of the present application, there are switches between multiple converters in the DC equivalent system, and each switch is connected to a controller. The controller realizes the conduction and shutdown between different converters by controlling the conduction and shutdown of the switches, and multiple converters in the on state can form a DC transmission topology. When it is necessary to verify the stability of the target DC transmission topology, the controller can determine the target converter corresponding to the target DC transmission topology according to the type of the target DC transmission topology. And select the target converter from the multiple converters in the DC equivalent system, control the switch between the target converters to be turned on, and keep the switches between other converters in the off state, so that the construction of the target equivalent subsystem corresponding to the target DC transmission topology can be completed.

[0102] S203, performing a simulated pair-drag test on each converter in the target equivalent subsystem to obtain a plurality of simulated electrical parameters.

[0103] Among them, the simulated pair-drag test refers to the simulation process of the back-to-back pair-drag test, which means placing two converters in each converter of the target equivalent subsystem back to back, with one converter simulating the power supply side and the other converter simulating the load side, and simulating the converter on the load side through control signals and power flow to determine the actual operation of the converter in the target DC transmission topology. The simulated electrical parameters refer to the relevant parameter information of the converter, for example, the relevant parameter information can be the maximum operating voltage and maximum conduction current of the converter.

[0104] In the embodiment of the present application, since the converters for back-to-back tests include power supply side converters and load side converters, the controller can divide multiple converters into multiple groups according to the back-to-back test requirements. For any group of converters, the controller can add test conditions in the target equivalent subsystem based on the test conditions of the back-to-back drag test. And output different control signals to simulate the group of converters to obtain multiple simulated electrical parameters of the converters on the load side of the group.

[0105] S204: Determine a stability verification result of the target DC transmission topology according to the multiple simulated electrical parameters.

[0106] In the embodiment of the present application, since the multiple simulated electrical parameters refer to the parameters of the converter, the controller can determine whether the actual operation of the converter in the target DC transmission topology meets the operating conditions based on the multiple simulated electrical parameters of each converter. If the object of the simulated towing test is only one converter, and the actual operation of the converter in the target DC transmission topology meets the operating conditions, it is determined that the stability verification of the target DC transmission topology has passed; if the actual operation of the converter in the target DC transmission topology does not meet the operating conditions, it is determined that the stability verification of the target DC transmission topology has not passed.

[0107] In the above stability verification method, the type of the target DC transmission topology to be verified is obtained; according to the type of the target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is built through multiple converters in the DC equivalent system; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies; simulated pair-drag tests are performed on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters; and the stability verification result of the target DC transmission topology is determined according to the multiple simulated electrical parameters. The multiple converters in the DC equivalent system in this method can be connected in any combination through switches to build equivalent subsystems corresponding to different types of DC transmission topologies, that is, multiple equivalent subsystems of different types can be built through one DC equivalent system. Then, through this one DC equivalent system, multiple converters of multiple different types of target equivalent subsystems can be simulated pair-drag tests, which reduces the complexity of the reliability verification method of multiple DC transmission topologies, so that the stability of equivalent systems of multiple DC transmission topologies can be verified more easily.

[0108] Next, the specific content of obtaining the type of the target DC transmission topology to be verified is introduced, and the specific content includes:

[0109] According to the topological structure of the target DC power transmission topology to be verified, at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC power transmission topology are determined.

[0110] In an embodiment of the present application, after determining that a certain DC transmission topology is a target DC transmission topology to be verified, the controller can obtain the topological structure of the target DC transmission topology. The topological structure includes the converter on the rectifier side, the converter on the inverter side, and the smoothing reactor in the target DC transmission topology. Then, the controller can determine at least one converter type on the rectifier side and at least one converter type on the inverter side from the topological structure of the target DC transmission topology.

[0111] In the above stability verification method, at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC transmission topology are determined according to the topological structure of the target DC transmission topology to be verified. The topological structure of the target DC transmission topology in the method includes various transmission devices, so by analyzing the topological structure of the target DC transmission topology, at least one converter type on the rectifier side and at least one converter type on the inverter side can be accurately obtained from the topological structure.

[0112] In one embodiment, Figure 3As shown, the above-mentioned construction of a target equivalent subsystem corresponding to the target DC transmission topology by using multiple converters in the DC equivalent system according to the type of the target DC transmission topology includes the following steps:

[0113] S301, screening out a rectifier-side target converter that matches the type of at least one converter on the rectifier side from a plurality of converters in a DC equivalent system, and screening out an inverter-side target converter that matches the type of at least one converter on the inverter side from a plurality of converters.

[0114] In the embodiment of the present application, after obtaining at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC transmission topology, for the rectifier side, the controller can match at least one converter type on the rectifier side with the types of multiple converters in the DC equivalent system, and determine the target converter on the rectifier side according to the matching result. For the inverter side, the controller can match at least one converter type on the inverter side with the types of multiple converters in the DC equivalent system, and determine the target converter on the inverter side according to the matching result.

[0115] It should be noted that the rectifier-side target converter includes at least one converter, and the inverter-side target converter also includes at least one converter.

[0116] S302, controlling the switch between each rectifier-side target converter and each inverter-side target converter to be turned on, and controlling the switch between other converters except the rectifier-side target converter and the inverter-side target converter to be turned off, to obtain a target equivalent subsystem corresponding to the target DC transmission topology.

[0117] In an embodiment of the present application, there is a corresponding switch between each rectifier-side converter and each inverter-side converter in the DC equivalent system. Then, after the rectifier-side target converter and the inverter-side target converter are determined, the controller can control the switch between each rectifier-side target converter and each inverter-side target converter to be in the on state. For converters other than the rectifier-side target converter and the inverter-side target converter, the controller can control the switches between other converters to be turned off. In this way, the system composed of converters that are connected to each other in the DC equivalent system is the target equivalent subsystem corresponding to the target DC transmission topology.

[0118] In the above stability verification method, a target converter on the rectifier side that matches the type of at least one converter on the rectifier side is screened out from multiple converters in the DC equivalent system, and a target converter on the inverter side that matches the type of at least one converter on the inverter side is screened out from multiple converters; the switch between each target converter on the rectifier side and each target converter on the inverter side is controlled to be turned on, and the switch between other converters except the target converter on the rectifier side and the target converter on the inverter side is controlled to be turned off, so as to obtain the target equivalent subsystem corresponding to the target DC transmission topology. According to at least one converter type on the rectifier side and at least one converter type on the inverter side, this method can accurately screen out the target converter on the rectifier side and the target converter on the inverter side from multiple converters in the DC equivalent system, and by controlling the switch between the target converter on the rectifier side and the target converter on the inverter side to be turned on, and controlling the switch between other converters to be turned off, the target equivalent subsystem corresponding to the target DC transmission topology can be accurately constructed.

[0119] Assuming that the multiple converters in the target equivalent subsystem include fixed converters and converters to be verified, then, in one embodiment, the specific contents of performing the simulated towing test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters include:

[0120] The fixed converter in the target equivalent subsystem is controlled to perform a simulated towing test on the converter to be verified, so as to obtain a plurality of simulated electrical parameters of the converter to be verified under the test conditions.

[0121] Among them, the fixed converter can represent the converter on the simulated power supply side in the towing test, and the converter to be verified represents the converter on the simulated load side in the towing test. The fixed converter and the converter to be verified can be interchanged in different simulated towing tests. For example, in the high-voltage direct current transmission topology, both the rectifier side and the inverter side are LCCs. Then, when the LCC on the rectifier side is the converter to be verified, the LCC on the inverter side is the fixed converter; when the LCC on the inverter side is the converter to be verified, the LCC on the rectifier side is the fixed converter.

[0122] In the embodiment of the present application, for the simulated towing test, after the fixed converter and the to-be-verified converter in the target equivalent subsystem are determined, the controller can output different control signals to the fixed converter and the to-be-verified converter to perform the simulated towing test. During the simulated towing test, multiple simulated electrical parameters of the to-be-verified converter under the test conditions are collected through sensors.

[0123] In the above stability verification method, the fixed converter in the target equivalent subsystem is controlled to perform a simulated towing test on the converter to be verified, and multiple simulated electrical parameters of the converter to be verified under the test conditions are obtained. During the simulated towing test, multiple converters in the target equivalent subsystem are divided into fixed converters and converters to be verified, and the fixed converter in the target equivalent subsystem is used to perform a simulated towing test on the converter to be verified, so that multiple simulated electrical parameters under the test conditions can be accurately obtained.

[0124] For the equivalent subsystems corresponding to different types of DC transmission topologies, the types and quantities of converters included are different. Then, under different equivalent subsystems, different types of simulated towing tests can be selected to obtain the simulated electrical parameters of the converter to be verified. Next, the specific contents of the simulated towing test of the fixed converter in the control target equivalent subsystem on the converter to be verified are introduced through an embodiment, and the specific contents include:

[0125] When the number of fixed converters is one, a simulated pair-drag test is performed on the converter to be verified by using a fixed converter in a two-terminal pair-drag manner; when the number of fixed converters is two, a simulated pair-drag test is performed on the converter to be verified by using two fixed converters connected in series in a three-terminal pair-drag manner; wherein the two fixed converters connected in series are two converters on the rectifier side or the inverter side.

[0126] In an embodiment of the present application, the simulated pair-drag test includes a two-terminal pair-drag mode and a three-terminal pair-drag mode. During the simulated pair-drag test, the controller can select a two-terminal pair-drag mode or a three-terminal pair-drag mode to perform a simulated pair-drag test on the converter to be verified based on the number of fixed converters in the target equivalent subsystem. For example, if the number of fixed converters is one, one fixed converter can be selected to complete the simulated pair-drag test in a two-terminal pair-drag mode; if the number of fixed converters is two, two fixed converters can be selected to complete the simulated pair-drag test in a three-terminal pair-drag mode. It should be noted that the two fixed converters can be two converters on the rectifier side or two converters on the inverter side. Two fixed converters consisting of a rectifier side converter and an inverter side converter cannot achieve three-terminal pair-drag.

[0127] The towing test includes two-end towing and three-end towing, among which: Figure 4a A first schematic diagram showing a two-end towing test, A represents LCC, B represents HCC, and in the figure, LCC and HCC are subjected to a two-end simulated towing test. Figure 4b A second schematic diagram showing a two-end dragging test, wherein C represents MMC, and in the diagram, MMC and HCC are subjected to a two-end simulated dragging test. Figure 4c A third schematic diagram of a two-end towing test is shown, in which an LCC and an MMC perform a two-end towing test. Figure 4d A schematic diagram showing a three-terminal towing test. The MMC is used as reactive power compensation. After the MMC is connected in series with the LCC, a three-terminal simulated towing test is performed with the HCC.

[0128] In the above stability verification method, when the number of fixed converters is one, the fixed converter is used to simulate the pair-drag test on the converter to be verified in a two-terminal pair-drag mode; when the number of fixed converters is two, the two fixed converters connected in series are used to simulate the pair-drag test on the converter to be verified in a three-terminal pair-drag mode; wherein the two fixed converters connected in series are two converters on the rectifier side or the inverter side. This method can flexibly select the two-terminal pair-drag or three-terminal pair-drag mode for the simulated pair-drag test according to the number of fixed converters, making the reliability verification process of the converter to be verified more flexible.

[0129] The stability verification result of the target DC transmission topology is mainly based on the reliability verification result of the converter in the target equivalent subsystem. Figure 5 As shown, the specific contents of determining the stability verification result of the target DC transmission topology according to multiple simulated electrical parameters include the following steps:

[0130] S401, determining a reliability verification result of a converter to be verified according to a plurality of simulated electrical parameters.

[0131] In the embodiment of the present application, for any simulated electrical parameter, the controller can compare the simulated electrical parameter with a preset threshold range. If the simulated electrical parameter is within the preset threshold range, it is determined that the simulated electrical parameter meets the preset condition. If all simulated electrical parameters meet the preset conditions, it can be determined that the reliability verification of the converter to be verified has passed. If any simulated electrical parameter does not meet the preset conditions, it can be determined that the reliability verification result of the converter to be verified has not passed.

[0132] Alternatively, the controller may also calculate the ratio of the simulated electrical parameters that meet the preset conditions, and if the ratio is greater than or equal to the preset ratio threshold, it is determined that the reliability verification of the converter to be verified has passed. If the ratio is less than the preset ratio threshold, it is determined that the reliability verification of the converter to be verified has not passed.

[0133] S402: Based on the reliability verification result, a stability verification result of the target DC transmission topology is obtained.

[0134] In an embodiment of the present application, after the reliability verification result of the converter to be verified is obtained, if the number of converters to be verified is one and the reliability verification of the converter to be verified passes, it is determined that the stability verification of the target DC transmission topology passes; if the reliability verification of the converter to be verified fails, it is determined that the stability verification of the target DC transmission topology fails.

[0135] If there are multiple converters to be verified and the reliability verification of the multiple converters to be verified has passed, it is determined that the stability verification of the target DC transmission topology has passed; if the reliability verification of any one of the multiple converters to be verified has failed, it is determined that the stability verification of the target DC transmission topology has failed.

[0136] In the above stability verification method, the reliability verification result of the converter to be verified is determined according to multiple simulated electrical parameters; based on the reliability verification result, the stability verification result of the target DC transmission topology is obtained. This method can accurately verify the reliability of the converter to be verified through multiple simulated electrical parameters, and then accurately obtain the stability verification result of the target DC transmission topology based on the reliability verification result.

[0137] In one embodiment, Figure 6 As shown, the specific contents of determining the reliability verification result of the converter to be verified based on multiple simulated electrical parameters include:

[0138] S501, comparing a plurality of simulated electrical parameters with a preset threshold range.

[0139] The preset threshold range can be determined according to the actual operation situation, that is, the range in which no abnormality occurs during the actual operation can be used as the preset threshold range. Alternatively, the preset threshold range can also be determined based on historical experience.

[0140] In the embodiment of the present application, for different simulated electrical parameters, the range of safe operation is different. Therefore, the preset threshold range may include multiple threshold ranges corresponding to different simulated electrical parameters. Based on this, for any simulated electrical parameter, the controller may compare the simulated electrical parameter with the preset threshold range to determine whether the simulated electrical parameter is within the preset threshold range.

[0141] S502: If the plurality of simulated electrical parameters are all within the preset threshold range, it is determined that the reliability verification of the converter to be verified has passed.

[0142] In the embodiment of the present application, after the comparison result is obtained, if the comparison result is that multiple simulated electrical parameters are all within the preset threshold range, it is determined that the converter to be verified is within the safe range, that is, the reliability verification of the converter to be verified is passed.

[0143] S503: If any of the simulated electrical parameters is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has failed.

[0144] In an embodiment of the present application, after obtaining the comparison result, if the comparison result is that any one of the multiple simulated electrical parameters is not within the preset threshold range, it is determined that the converter to be verified is not within the safe range, that is, the reliability verification of the converter to be verified fails.

[0145] In the above stability verification method, multiple simulated electrical parameters are compared with preset threshold ranges; if the simulated electrical parameters are all within the preset threshold ranges, it is determined that the reliability verification of the converter to be verified has passed; if any simulated electrical parameter is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has not passed. This method can accurately determine whether the reliability verification process of the converter to be verified has passed by comparing the simulated electrical parameters with the preset threshold ranges and based on the comparison results.

[0146] In order to ensure that the converter can still operate normally under various fault conditions, stability verification must be performed under various conditions. Figure 7 As shown, the stability verification method also includes the following steps:

[0147] S601, inputting voltage disturbance signals of different levels into a target equivalent subsystem.

[0148] The voltage disturbance signals of different levels represent fault signals of different severity levels. For example, the voltage disturbance signal may include three levels of disturbances, namely, a severe level voltage disturbance signal, a normal level voltage disturbance signal, and a slight level voltage disturbance signal.

[0149] In an embodiment of the present application, the controller may output different control signals to the voltage disturbance device, so that the voltage disturbance device can input voltage disturbance signals of different levels to the target equivalent subsystem. Alternatively, the controller may also obtain voltage disturbance signals of different levels and input voltage disturbance signals of different levels to the target equivalent subsystem.

[0150] S602, when each level of voltage disturbance signal is input, executing the step of performing a simulated towing test on each converter in the target equivalent subsystem.

[0151] In an embodiment of the present application, in order to more accurately verify the stability of the target equivalent subsystem, it is necessary to perform stability verification when each level of voltage disturbance signal is input. Then, according to the stability verification results corresponding to the voltage disturbance signals of different levels, the stability verification results of the target DC transmission topology are determined. Then, for any level of voltage disturbance signal, the controller needs to perform a simulated towing test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters. Then, according to the multiple simulated electrical parameters, the stability verification result corresponding to the voltage disturbance signal of this level is determined.

[0152] In the above stability verification method, different levels of voltage disturbance signals are input to the target equivalent subsystem; when each level of voltage disturbance signal is input, the step of performing a simulated pair-drag test on each converter in the target equivalent subsystem is performed. This method inputs different levels of voltage disturbance signals to the target equivalent subsystem, and when each level of voltage disturbance signal is input, a simulated pair-drag test is performed on each converter in the target equivalent subsystem. In this way, the stability verification result corresponding to the voltage disturbance signal of that level can be accurately obtained, thereby realizing stability verification under various working conditions and improving the accuracy of the stability verification result of the target DC transmission topology.

[0153] As a specific embodiment of the present application, Figure 8 As shown, the stability verification method includes:

[0154] S701, determining at least one converter type on a rectifier side and at least one converter type on an inverter side in the target DC transmission topology according to a topology structure of the target DC transmission topology to be verified;

[0155] S702, screening out a rectifier-side target converter that matches the type of at least one converter on the rectifier side from a plurality of converters in the DC equivalent system, and screening out an inverter-side target converter that matches the type of at least one converter on the inverter side from a plurality of converters;

[0156] S703, controlling the switch between each rectifier-side target converter and each inverter-side target converter to be turned on, and controlling the switch between other converters except the rectifier-side target converter and the inverter-side target converter to be turned off, to obtain a target equivalent subsystem corresponding to the target DC transmission topology;

[0157] S704, controlling the fixed converter in the target equivalent subsystem to perform a simulated towing test on the converter to be verified, and obtaining a plurality of simulated electrical parameters of the converter to be verified under the test conditions;

[0158] S705, comparing a plurality of simulated electrical parameters with a preset threshold range;

[0159] S706, if the multiple simulated electrical parameters are all within the preset threshold range, it is determined that the reliability verification of the converter to be verified has passed;

[0160] S707, determining that the stability verification of the target DC transmission topology has passed;

[0161] S708, if any of the simulated electrical parameters is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has failed;

[0162] S709, determining that the stability verification of the target DC transmission topology has failed.

[0163] It should be understood that, although the steps in the flowcharts involved in the above embodiments are displayed in sequence according to the indication of the arrows, these steps are not necessarily executed in sequence according to the order indicated by the arrows. Unless there is a clear explanation in this article, the execution of these steps is not strictly limited in order, and these steps can be executed in other orders. Moreover, at least a part of the steps in the flowcharts involved in the above embodiments may include multiple steps or multiple stages, and these steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily carried out in sequence, but can be executed in turn or alternately with other steps or at least a part of the steps or stages in other steps.

[0164] Based on the same inventive concept, the embodiment of the present application further provides a stability verification system for implementing the stability verification method involved above. Next, the stability verification system is introduced in detail.

[0165] In one embodiment, Fig. 9 As shown, the stability verification system includes a controller 10 and a DC equivalent system 11, and the DC equivalent system 11 includes a plurality of converters 12; the plurality of converters 12 are combined and connected through switches 13 to build equivalent subsystems corresponding to different types of DC transmission topologies;

[0166] The controller 10 is used to obtain the type of the target DC transmission topology to be verified; according to the type of the target DC transmission topology, build a target equivalent subsystem 14 corresponding to the target DC transmission topology through multiple converters 12 in the DC equivalent system 11; perform a simulated pair-drag test on each converter in the target equivalent subsystem 14 to obtain multiple simulated electrical parameters; and determine the stability verification result of the target DC transmission topology according to the multiple simulated electrical parameters.

[0167] In an embodiment of the present application, the multiple converters 12 in the DC equivalent system 11 include converter 1, converter 2...converter N. The types of the multiple converters 12 may be hybrid commutation converters, flexible DC converters, controllable commutation converters, and the like. The current of the multiple converters 12 needs to be less than a preset voltage threshold, for example, the preset voltage threshold may be 5000 amperes (A). Different types of converters can be combined into different types of DC transmission topologies. For example, when both the rectifier side and the inverter side are LCC, the DC transmission topology constructed is a high-voltage DC transmission topology; when both the rectifier side and the inverter side are MMC, the DC transmission topology constructed is a flexible DC transmission topology.

[0168] Fig. 9 The target equivalent subsystem 14 in the embodiment includes converter 1 and converter 2, which is only an example. The target equivalent subsystem 14 may be composed of at least two converters among the multiple converters 12. Then, in one embodiment, the multiple converters in the target equivalent subsystem 14 include fixed converters and converters to be verified; the controller 10 is used to control the switch conduction between the fixed converters when the number of the fixed converters is two.

[0169] The number of fixed converters in the target equivalent subsystem 14 is two, that is, the three-terminal pairing situation, refer to Figure 4d In the schematic diagram of the three-terminal towing test, the two fixed converters are two converters on the rectifier side or the inverter side. In this case, the controller 10 needs to control the switch between the two fixed converters to be turned on to meet the requirements of the three-terminal towing test.

[0170] Fig.10 The schematic diagram of the structure of IGBT-MMC is shown in Figure 1. The Insulate-Gate Bipolar Transistor (IGBT)-MMC includes six bridge arms, which are used to realize the conversion between AC and DC. Each bridge arm is composed of multiple modular multilevel converter submodules connected in cascade. As can be seen from the figure, each bridge arm includes n multilevel converter submodules, namely SM1, SM2...SMn, and the n multilevel converter submodules are all connected in cascade. d Indicates the DC side voltage of the IGBT-MMC.

[0171] Fig.11 The schematic diagram of the structure of a 12-pulse LCC is shown. The 12-pulse LCC is composed of two 6-pulse LCCs connected in series, with a phase difference of 30°. A 6-pulse LCC is composed of 6 bridge arms, each of which includes multiple thyristors connected in series. d Indicates the DC side voltage of a 12-pulse LCC.

[0172] Fig.12 The schematic diagram of the structure of the HCC based on IGCT is that the HCC based on IGCT is a 12-pulse converter. The 12-pulse HCC is composed of two 6-pulse HCCs connected in series, with a phase difference of 30°. A 6-pulse HCC is composed of 6 bridge arms, each of which includes multiple IGCTs connected in series. d Indicates the DC side voltage of the HCC based on IGCT.

[0173] Fig.13 The topology of the CSC converter is shown in the figure. The converter contains 6 bridge arms, each of which is composed of several IGCTs in series. The CSC AC side is an LC low-pass filter, which can effectively filter out the high-order current harmonics generated by the converter. d Indicates the DC side voltage of CSC.

[0174] The controller 10 may be, but is not limited to, a microcontroller unit (MCU), a central processing unit (CPU), a digital signal processor (DSP), a field programmable gate array (FPGA), a single-chip microcomputer or other control devices.

[0175] The above stability verification system includes a controller 10 and a DC equivalent system 11. The DC equivalent system 11 includes a plurality of converters 12. The plurality of converters 12 are connected in combination through switches 13 to build equivalent subsystems corresponding to different types of DC transmission topologies. The controller 10 is used to obtain the type of the target DC transmission topology to be verified. According to the type of the target DC transmission topology, a target equivalent subsystem 14 corresponding to the target DC transmission topology is built through the plurality of converters 12 in the DC equivalent system 11. A simulated pair-drag test is performed on each converter in the target equivalent subsystem 14 to obtain a plurality of simulated electrical parameters. And according to the plurality of simulated electrical parameters, the stability verification result of the target DC transmission topology is determined. The plurality of converters 12 in the DC equivalent system 11 can be connected in any combination through switches 13 to build equivalent subsystems corresponding to different types of DC transmission topologies. That is, a plurality of different types of equivalent subsystems can be built through one DC equivalent system 11. Then, through this DC equivalent system 11, multiple converters of various different types of target equivalent subsystems can be simulated for dragging tests, reducing the complexity of the reliability verification method of various DC transmission topologies, so that the stability of equivalent systems of various DC transmission topologies can be verified more easily.

[0176] In one embodiment, Fig.14 is a first schematic diagram of a DC equivalent system, wherein the plurality of converters 12 include at least one rectifier-side converter 121 and at least one inverter-side converter 122;

[0177] Each converter in at least one rectifier-side converter 121 is connected to each converter in at least one inverter-side converter 122 via a first switch 131, and converters in at least one rectifier-side converter 121 are connected to each other via a second switch 132, and converters in at least one inverter-side converter 122 are connected to each other via a third switch 133.

[0178] Among them, the rectifier side in the DC transmission topology mainly utilizes the conduction characteristics of semiconductor devices (such as diodes and thyristors) to clip and rectify the input AC power, and output a certain level of DC power. The main function of the rectifier-side converter is to convert the electrical energy in the power supply into DC power to provide it to the DC load. The inverter side mainly utilizes the switching action of semiconductor switching devices to open and close the DC power in sections, converting the DC power into AC power of a certain frequency, amplitude and phase.

[0179] In the embodiment of the present application, the plurality of converters 12 may be divided into at least one rectifier-side converter 121 and at least one inverter-side converter 122. Fig.14 At least one rectifier-side converter 121 includes two converters, and at least one inverter-side converter 122 also includes two converters. In the process of building the target equivalent subsystem 14, the target equivalent subsystem 14 can be built by connecting some converters on the rectifier side and some converters on the inverter side through switches.

[0180] It is understandable that at least one rectifier-side converter 121 is responsible for AC rectification. If the rectifier-side converter is a 6-pulse converter, then the 6-pulse converter can be composed of 6 converters in a 3-phase full-bridge connection mode, and each converter is triggered alternately at the same interval to convert AC into DC current. Any one of the at least one inverter-side converter 122 can also be composed of 6 converters in a 3-phase full-bridge connection mode, which is responsible for converting DC into AC and connecting to the power supply system. At least one inverter-side converter 122 forms a circulation loop with at least one rectifier-side converter 121 to reduce the capacity requirement of the DC equivalent system 11. It should be noted that the converter to be verified can be used as both the rectifier side and the inverter side, and can be flexibly adjusted according to the test requirements.

[0181] The above-mentioned multiple converters 12 include at least one rectifier-side converter 121 and at least one inverter-side converter 122; each converter in at least one rectifier-side converter 121 is connected to each converter in at least one inverter-side converter 122 via a first switch 131, and the converters in at least one rectifier-side converter 121 are connected via a second switch 132, and the converters in at least one inverter-side converter 122 are connected via a third switch 133. By dividing the multiple converters into the rectifier side and the inverter side, the function of each converter can be clarified, and different switches can be set in the converters on the rectifier side and the inverter side. In the subsequent construction process of the equivalent subsystem, by controlling the conduction and shutdown of different switches, the construction of the target equivalent subsystem 14 can be accurately completed.

[0182] In order to suppress the ripple in the output DC voltage of the rectifier-side converter 121, a ripple suppression device 15 is introduced into the DC equivalent system 11. Next, the ripple suppression device 15 is described in detail through an embodiment. Fig.14 As shown, the DC equivalent system 11 further includes a ripple suppression device 15, and each converter in at least one rectifier-side converter 121 and each converter in at least one inverter-side converter 122 are connected to the ripple suppression device 15 via a first switch 131;

[0183] The ripple suppression device 15 is used to suppress the ripple in the output rectified voltage of the rectifier-side converter 121 .

[0184] In the embodiment of the present application, since the pulse number of the rectifier-side converter 121 is limited, the output DC voltage of the rectifier-side converter 121 always carries ripples, which need to be suppressed by the ripple suppression device 15. The ripple suppression device 15 may include energy storage inductors, filter capacitors, smoothing reactors, and the like.

[0185] Taking the ripple suppression device 15 as a smoothing reactor 151 as an example, in one embodiment, continue to refer to Fig.14 As shown, the ripple suppression device 15 includes a smoothing reactor 151, which is connected in series between the DC output terminal of each converter in at least one rectifier-side converter 121 and at least one inverter-side converter 122 and the DC line.

[0186] Among them, the smoothing reactor 151 is a device used to filter out DC harmonics in the DC transmission topology. The smoothing reactor 151 is composed of components such as inductors and capacitors. The parameters of the inductors and capacitors are adjusted to achieve attenuation and filtering of harmonics of a specific frequency.

[0187] In the embodiment of the present application, the converter of the DC transmission topology is equipped with a smoothing reactor 151 to make the output DC close to the ideal DC. The smoothing reactor 151 is generally connected in series between the DC output terminal of each converter and the DC line, which can smooth the ripple in the DC current, avoid the discontinuity of the current during low DC power transmission, and reduce the probability of commutation failure by limiting the current change rate caused by rapid voltage changes. The selection of the smoothing reactor 151 mainly considers the rise rate of the fault current, and its inductance value can be calculated by the rated DC voltage of the target equivalent subsystem 14.

[0188] It should be noted that the number of converters in the rectifier-side converter 121 and the inverter-side converter 122 is one or more, the number of smoothing reactors 151 is one, all converters on the rectifier side are connected to the input end of the smoothing reactor 151, and all converters on the inverter side are connected to the output end of the smoothing reactor 151.

[0189] The DC equivalent system 11 further includes a ripple suppression device 15, and each converter in at least one rectifier-side converter 121 and each converter in at least one inverter-side converter 122 are connected to the ripple suppression device 15 through a first switch 131; the ripple suppression device 15 is used to suppress the ripple in the output rectified voltage of the rectifier-side converter 121. The ripple suppression device 15 includes a smoothing reactor 151, which is connected in series between the DC output terminal of each converter in at least one rectifier-side converter 121 and at least one inverter-side converter 122 and the DC line. A smoothing reactor 151 is introduced between at least one rectifier-side converter 121 and at least one inverter-side converter 122. The smoothing reactor 151 can suppress the ripple in the output rectified voltage of the rectifier-side converter 121, so that the environment of the simulated towing test is closer to the actual target DC transmission topology environment.

[0190] In order to ensure that the converter can still operate normally under various fault conditions, stability verification must be performed under various conditions. Therefore, a voltage disturbance device 16 can be connected in series in the DC equivalent system 11 to simulate the fault condition and verify the stability of the DC equivalent system 11. Then, in one embodiment, continue to refer to Fig.14 As shown, the DC equivalent system 11 further includes a voltage disturbance device 16, and the voltage disturbance device 16 is connected to the output end of the inverter-side converter 122;

[0191] A voltage disturbance device 16, used for introducing a voltage disturbance signal into the DC equivalent system 11;

[0192] The controller 10 is used to verify the stability of the target equivalent subsystem 14 when the inverter-side converter 122 is disturbed by a voltage disturbance signal.

[0193] The voltage disturbance device 16 is used to simulate various fault conditions to verify the ability of the converter and the DC transmission topology to resist commutation failure. Commutation failure is a common fault, which is caused by a variety of faults, such as converter short circuit, loss of trigger pulse, inverter side AC system fault, etc.

[0194] In the embodiment of the present application, after the voltage disturbance device 16 is connected to the DC equivalent system 11 and the voltage disturbance device 16 generates a voltage disturbance signal, the inverter-side converter 122 generates a fault response to the voltage disturbance signal. The controller 10 can compare the fault response with the preset fault response, and determine whether the fault response action and the protection strategy are verified according to the comparison result.

[0195] In one embodiment, the voltage disturbance device 16 includes a voltage regulating device 161 and a voltage regulating switch 162, and the voltage regulating device 161 is connected to the inverter-side converter 122 through the voltage regulating switch 162;

[0196] A voltage regulating device 161, for adjusting the amplitude and phase of the output voltage of the AC power source;

[0197] The voltage regulating switch 162 is used to adjust the magnitude of the adjusted AC voltage within a preset regulating range to form a voltage disturbance signal.

[0198] The voltage disturbance device 16 is composed of a voltage regulating device 161 based on a fully controlled device and a wide range voltage regulating switch 162. The voltage regulating device 161 of the fully controlled device is used to rectify the industrial frequency periodic AC power supply, and then convert the DC into industrial frequency periodic AC through the inverter-side converter. Cooperating with the voltage regulating switch 162, the output voltage can be adjusted by 10%~100%, so that the size of the voltage disturbance signal can be flexibly adjusted. Among them, the voltage regulating device 161 can be composed of one or more converters, converter transformers, filters and main switches. The voltage regulating switch 162 can include a pressure controller, a transformer no-load voltage regulating switch or a voltage regulator, etc.

[0199] The above-mentioned DC equivalent system 11 also includes a voltage disturbance device 16, which is connected to the output end of the inverter-side converter 122; the voltage disturbance device 16 is used to introduce a voltage disturbance signal to the DC equivalent system 11; the controller 10 is used to verify the fault response action and protection strategy of the inverter-side converter 122 when the inverter-side converter 122 is under voltage disturbance interference. The voltage disturbance device 16 includes a voltage regulating device 161 and a voltage regulating switch 162, and the voltage regulating device 161 is connected to the inverter-side converter 122 through the voltage regulating switch 162; the voltage regulating device 161 is used to adjust the amplitude and phase of the output voltage of the AC power supply; the voltage regulating switch 162 is used to adjust the size of the adjusted AC voltage within a preset adjustment range to form a voltage disturbance signal. By introducing a voltage disturbance device 16 with a voltage regulating switch 162 into the DC equivalent system 11, disturbances of different sizes can be introduced during the simulation process of the equivalent system. In this way, the DC equivalent system 11 can simulate the operation of multiple DC transmission topologies under different disturbances, making the simulation process of the DC equivalent system 11 closer to the actual process, thereby making the stability verification result of the DC equivalent system 11 more accurate.

[0200] The DC equivalent system 11 is prone to generate harmonics during the test. In order to avoid adverse effects on AC power transmission and compensate for reactive power consumed by the DC transmission topology, an AC filter device 17 needs to be introduced during the simulation of the DC equivalent system 11. Next, the AC filter device 17 is introduced through an embodiment. Fig.14 As shown, the DC equivalent system 11 further includes an AC filter device 17, which is arranged on the AC busbar, and the AC filter device 17 is respectively connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122;

[0201] The AC filter device 17 is used to filter out the harmonics generated by the DC equivalent system 11 during the test process.

[0202] In the embodiment of the present application, the AC filter device 17 is arranged between the AC power supply and the input end of the rectifier-side converter 121 and between the input power supply and the output end of the inverter-side converter 122.

[0203] In one embodiment, the AC filter device 17 includes at least two filters 171, and the at least two filters 171 are respectively connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122;

[0204] At least two filters 171 are used to filter out harmonics of different frequencies in the DC equivalent system 11 .

[0205] In an embodiment of the present application, each filter 171 may be composed of a capacitor, a reactance, and a resistor connected in series and in parallel. Different types of converters correspond to harmonics of different frequencies. In order to achieve the purpose of filtering out harmonics, multiple filters 171 may be provided to filter out harmonics of different frequencies respectively. In the process of setting the filter 171, it may be provided based on the type of converter. For example, the DC equivalent system 11 includes a 6-pulse converter, a 12-pulse converter, and a 24-pulse converter, and 3 filters may be provided to filter out harmonics of different frequencies respectively. Among them, for a 6-pulse converter, the frequency of the harmonic may be a characteristic harmonic of 6K±1 or 6K. For a 12-pulse converter, the frequency of the harmonic may be a 12K commutation harmonic. For a 24-pulse converter, the frequency of the harmonic may be a 24K commutation harmonic.

[0206] The AC filter can be a ceramic capacitor, a metal foil capacitor or an organic electrolytic capacitor, etc. Different types of AC filters differ in filtering effect, operating temperature range, voltage resistance, etc., and selection needs to be made according to the types of multiple converters 12 in the DC equivalent system 11.

[0207] The above-mentioned DC equivalent system 11 also includes an AC filtering device 17, which is arranged on the AC busbar and is respectively connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122; the AC filtering device 17 is used to filter out the harmonics generated by the DC equivalent system 11 during the test process. The AC filtering device 17 includes at least two filters 171, which are respectively connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122; at least two filters 171 are used to filter out harmonics of different frequencies in the DC equivalent system 11. By arranging multiple filters 171 between the AC voltage and the converter, the harmonics of each component can be filtered out, thereby preventing the test process of the DC equivalent system 11 from being affected by the harmonics.

[0208] A voltage conversion device 18 is also required to be provided between the multiple filters 171 and the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122 to convert the AC voltage into the commutation voltage required by the converter, so that the DC part and the AC part can be insulated from each other to prevent the neutral point grounding of the AC part and the neutral point grounding of the DC part from affecting each other, making the commutation process impossible. Then, in one embodiment, continue to refer to Fig.14 As shown, the DC equivalent system 11 further includes a voltage conversion device 18, and the voltage conversion device 18 is respectively connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122;

[0209] The voltage conversion device 18 is used to convert the AC voltage into a DC voltage and to insulate the DC voltage from the AC voltage.

[0210] In the embodiment of the present application, the voltage conversion device 18 is mainly used for mutual conversion between AC voltage and DC voltage, so that the DC power transmission system can complete the power transmission process with DC voltage.

[0211] In one embodiment, the voltage conversion device 18 includes a first converter transformer 181 and a second converter transformer 182 , the first converter transformer 181 is connected to the input end of the rectifier-side converter 121 , and the second converter transformer 182 is connected to the output end of the inverter-side converter 122 .

[0212] In the embodiment of the present application, the first converter transformer 181 is used to connect the AC power supply and the rectifier-side converter 121 to convert the input AC voltage into a DC voltage. The second converter transformer 182 is used to connect the AC power supply and the inverter-side converter 122 to convert the DC voltage output by the inverter-side converter 122 into an AC voltage.

[0213] It is understandable that different connection methods of transformer windings can also be used to provide two sets of three-phase symmetrical commutation voltages with equal amplitudes and a phase difference of 30° for the series-connected rectifier-side converter 121 and inverter-side converter 122 to achieve twelve-pulse commutation. At the same time, the leakage reactance of the converter can limit the fault current and buffer and suppress the lightning impulse overvoltage wave that invades the converter station along the AC line.

[0214] The above-mentioned DC equivalent system 11 also includes a voltage conversion device 18, which is connected to the input end of the rectifier-side converter 121 and the output end of the inverter-side converter 122 respectively; the voltage conversion device 18 is used to convert the AC voltage into a DC voltage and insulate the DC voltage from the AC voltage. The voltage conversion device 18 includes a first converter transformer 181 and a second converter transformer 182. The first converter transformer 181 is connected to the input end of the rectifier-side converter 121, and the second converter transformer 182 is connected to the output end of the inverter-side converter 122. The conversion between AC and DC voltage is achieved by connecting converter transformers between the AC power supply and the input end of the rectifier-side converter 121 and between the input power supply and the output end of the inverter-side converter 122.

[0215] Fig.151 is a second schematic diagram of a DC equivalent system, in which the DC equivalent system 11 includes a rectifier-side converter 121 and an inverter-side converter 122. The input end of the rectifier-side converter 121 is connected to the first converter transformer 181, the output end of the inverter-side converter 122 is connected to the second converter transformer 182, and the rectifier-side converter 121, the inverter-side converter 122 and the smoothing reactor 151 are connected through a switch 13. The input power supply in the figure represents the input of the AC voltage, and the AC filter device 17 includes three filters of 6th filter, 12th filter and 24th filter. In addition, a voltage disturbance device 16 is introduced into the DC equivalent system 11 to make the simulation process of the DC equivalent system 11 closer to the actual operation process, so that the stability verification result of the DC equivalent system 11 is more accurate.

[0216] Based on the same inventive concept, the embodiment of the present application also provides a stability verification device for implementing the stability verification method involved above. The implementation scheme for solving the problem provided by the device is similar to the implementation scheme recorded in the above method, so the specific limitations in one or more stability verification device embodiments provided below can refer to the limitations on the stability verification method above, and will not be repeated here.

[0217] In an exemplary embodiment, Fig.16 As shown, a stability verification device is provided, including: an acquisition module 21, a construction module 22, a test module 23 and a determination module 24, wherein:

[0218] An acquisition module 21 is used to acquire the type of the target DC transmission topology to be verified;

[0219] A building module 22 is used to build a target equivalent subsystem corresponding to the target DC transmission topology through multiple converters in the DC equivalent system according to the type of the target DC transmission topology; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies;

[0220] A test module 23 is used to test each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters;

[0221] The determination module 24 is used to determine the stability verification result of the target DC transmission topology according to the multiple simulated electrical parameters.

[0222] In one embodiment, the acquisition module includes a type determination unit, wherein:

[0223] The type determination unit is used to determine at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC transmission topology according to the topological structure of the target DC transmission topology to be verified.

[0224] In one embodiment, the building module comprises: a screening unit and a control unit, wherein:

[0225] A screening unit, used to screen out a rectifier-side target converter that matches the type of at least one converter on the rectifier side from a plurality of converters in the DC equivalent system, and to screen out an inverter-side target converter that matches the type of at least one converter on the inverter side from a plurality of converters;

[0226] The control unit is used to control the switch conduction between each rectifier-side target converter and each inverter-side target converter, and control the switch disconnection between other converters except the rectifier-side target converter and the inverter-side target converter, so as to obtain a target equivalent subsystem corresponding to the target DC transmission topology.

[0227] In one embodiment, the test module comprises an acquisition unit, wherein:

[0228] The acquisition unit is used to control the fixed converter in the target equivalent subsystem to perform a simulated towing test on the converter to be verified, and obtain multiple simulated electrical parameters of the converter to be verified under the test conditions.

[0229] In one embodiment, the acquisition unit is also used to, when the number of fixed converters is one, perform a simulated pair-drag test on the converter to be verified by using the fixed converter in a two-terminal pair-drag manner; when the number of fixed converters is two, perform a simulated pair-drag test on the converter to be verified by using two fixed converters connected in series in a three-terminal pair-drag manner; wherein the two fixed converters connected in series are two converters on the rectifier side or the inverter side.

[0230] In one embodiment, the determination module includes: a result determination unit and a result acquisition unit, wherein:

[0231] A result determination unit, used for determining a reliability verification result of the converter to be verified according to a plurality of simulated electrical parameters;

[0232] The result acquisition unit is used to acquire the stability verification result of the target DC transmission topology based on the reliability verification result.

[0233] In one embodiment, the above-mentioned result determination unit is also used to compare multiple simulated electrical parameters with a preset threshold range; if multiple simulated electrical parameters are all within the preset threshold range, it is determined that the reliability verification of the converter to be verified has passed; if any simulated electrical parameter is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has failed.

[0234] In one embodiment, the stability verification device further includes: an input module and an execution module, wherein:

[0235] An input module, used for inputting voltage disturbance signals of different levels into the target equivalent subsystem;

[0236] The execution module is used to execute the steps of simulating the pair-drag test on each converter in the target equivalent subsystem when a voltage disturbance signal of each level is input.

[0237] Each module in the above stability verification device can be implemented in whole or in part by software, hardware, or a combination thereof. Each module can be embedded in or independent of a processor in a computer device in the form of hardware, or can be stored in a memory in a computer device in the form of software, so that the processor can call and execute operations corresponding to each module.

[0238] In an exemplary embodiment, a controller is provided, including a memory and a processor, wherein a computer program is stored in the memory, and the processor implements the content of any one of the embodiments of the above-mentioned stability verification method when executing the computer program.

[0239] In one embodiment, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed by a processor, the content of any one embodiment of the above-mentioned stability verification method is implemented.

[0240] In one embodiment, a computer program product is provided, including a computer program, which implements the content of any one of the embodiments of the above-mentioned stability verification method when executed by a processor.

[0241] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, stored data, displayed data, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties, and the collection, use and processing of relevant data must comply with relevant regulations.

[0242] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the embodiments of the above-mentioned methods. Among them, any reference to the memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical memory, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetic random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. Volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM). The database involved in each embodiment provided in this application may include at least one of a relational database and a non-relational database. Non-relational databases may include distributed databases based on blockchains, etc., but are not limited to this. The processor involved in each embodiment provided in this application may be a general-purpose processor, a central processing unit, a graphics processor, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., but are not limited to this.

[0243] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this application.

[0244] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A stability verification method, characterized in that: The method comprises: Obtain the type of target DC transmission topology to be verified; According to the type of the target DC transmission topology, a target equivalent subsystem corresponding to the target DC transmission topology is built through multiple converters in the DC equivalent system; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies; Performing a simulated pair-drag test on each converter in the target equivalent subsystem to obtain a plurality of simulated electrical parameters; A stability verification result of the target direct current power transmission topology is determined according to the multiple simulated electrical parameters.

2. The method according to claim 1, characterized in that The obtaining the type of the target DC transmission topology to be verified includes: According to the topological structure of the target DC power transmission topology to be verified, at least one converter type on the rectifier side and at least one converter type on the inverter side in the target DC power transmission topology are determined.

3. The method according to claim 2, characterized in that The method of building a target equivalent subsystem corresponding to the target DC transmission topology by using a plurality of converters in a DC equivalent system according to the type of the target DC transmission topology includes: Screening out a rectifier-side target converter that matches the type of at least one converter on the rectifier side from a plurality of converters in the DC equivalent system, and screening out an inverter-side target converter that matches the type of at least one converter on the inverter side from the plurality of converters; The switches between each of the rectifier-side target converters and each of the inverter-side target converters are controlled to be turned on, and the switches between other converters except the rectifier-side target converter and the inverter-side target converter are controlled to be turned off, so as to obtain a target equivalent subsystem corresponding to the target DC transmission topology.

4. The method according to any one of claims 1 to 3, characterized in that: The multiple converters in the target equivalent subsystem include fixed converters and converters to be verified; The simulated pair-drag test is performed on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters, including: The fixed converter in the target equivalent subsystem is controlled to perform a simulated towing test on the converter to be verified, and a plurality of simulated electrical parameters of the converter to be verified under the test conditions are obtained.

5. The method according to claim 4, characterized in that The controlling the fixed converter in the target equivalent subsystem to perform a simulated towing test on the converter to be verified includes: In the case where the number of the fixed converter is one, a simulated towing test is performed on the converter to be verified in a two-end towing manner by the fixed converter; When the number of the fixed converters is two, a simulated pair-drag test is performed on the converter to be verified in a three-terminal pair-drag manner by two fixed converters connected in series; wherein the two fixed converters connected in series are two converters on the rectifier side or the inverter side.

6. The method according to claim 4, characterized in that Determining the stability verification result of the target DC power transmission topology according to the multiple simulated electrical parameters includes: Determining a reliability verification result of the converter to be verified according to the multiple simulated electrical parameters; Based on the reliability verification result, a stability verification result of the target direct current transmission topology is obtained.

7. The method according to claim 6, characterized in that The step of determining the reliability verification result of the converter to be verified according to the multiple simulated electrical parameters includes: comparing the plurality of simulated electrical parameters to a preset threshold range; If the plurality of simulated electrical parameters are all within the preset threshold range, it is determined that the reliability verification of the converter to be verified has passed; If any one of the simulated electrical parameters is not within the preset threshold range, it is determined that the reliability verification of the converter to be verified has failed.

8. The method according to any one of claims 1 to 3, characterized in that: The method further comprises: Inputting voltage disturbance signals of different levels into the target equivalent subsystem; When a voltage disturbance signal of each level is input, the step of performing a simulated pair-drag test on each converter in the target equivalent subsystem is performed.

9. A stability verification system, characterized in that: The stability verification system includes a controller and a DC equivalent system, wherein the DC equivalent system includes a plurality of converters, wherein the plurality of converters are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies; The controller is used to obtain the type of the target DC transmission topology to be verified; according to the type of the target DC transmission topology, build a target equivalent subsystem corresponding to the target DC transmission topology through multiple converters in the DC equivalent system; perform a simulated pair-drag test on each converter in the target equivalent subsystem to obtain multiple simulated electrical parameters; and determine the stability verification result of the target DC transmission topology according to the multiple simulated electrical parameters.

10. The system according to claim 9, characterized in that The multiple converters in the target equivalent subsystem include fixed converters and converters to be verified; The controller is used to control the conduction of switches between the fixed converters when the number of the fixed converters is two.

11. The system according to claim 9, characterized in that The plurality of converters include at least one rectifier-side converter and at least one inverter-side converter; Each converter in the at least one rectifier-side converter is connected to each converter in the at least one inverter-side converter via a first switch, and the converters in the at least one rectifier-side converter are connected to each other via a second switch, and the converters in the at least one inverter-side converter are connected to each other via a third switch.

12. The system according to claim 11, characterized in that The DC equivalent system further includes a ripple suppression device, and each of the at least one rectifier-side converter and each of the at least one inverter-side converter are connected to the ripple suppression device via a first switch; The ripple suppression device is used to suppress the ripple in the output rectified voltage of the rectifier-side converter.

13. The system according to claim 9, characterized in that The DC equivalent system further includes a voltage disturbance device, which is connected to the output end of the inverter-side converter; The voltage disturbance device is used to introduce a voltage disturbance signal into the DC equivalent system; The controller is used to verify the stability of the target equivalent subsystem when the inverter-side converter is disturbed by a voltage disturbance signal.

14. The system according to claim 13, characterized in that The voltage disturbance device comprises a voltage regulating device and a voltage regulating switch, wherein the voltage regulating device is connected to the inverter-side converter via the voltage regulating switch; The voltage regulating device is used to adjust the amplitude and phase of the output voltage of the AC power supply; The voltage regulating switch is used to adjust the magnitude of the adjusted AC voltage within a preset regulating range to form the voltage disturbance signal.

15. The system according to claim 9, characterized in that The DC equivalent system further includes an AC filter device, which is arranged on the AC bus and is respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter; The AC filtering device is used to filter out harmonics generated by the DC equivalent system during the test process.

16. The system according to claim 15, characterized in that The AC filter device comprises at least two filters, and the at least two filters are respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter; The at least two filters are used to filter out harmonics of different frequencies in the DC equivalent system.

17. The system according to claim 9, characterized in that The DC equivalent system further includes a voltage conversion device, which is respectively connected to the input end of the rectifier-side converter and the output end of the inverter-side converter; The voltage conversion device is used to convert AC voltage into DC voltage and to insulate and isolate the DC voltage from the AC voltage.

18. The system according to claim 17, characterized in that The voltage conversion device includes a first converter transformer and a second converter transformer, the first converter transformer is connected to the input end of the rectifier-side converter, and the second converter transformer is connected to the output end of the inverter-side converter.

19. A stability verification device, characterized in that: The device comprises: An acquisition module, used for acquiring the type of target DC transmission topology to be verified; A building module, used to build a target equivalent subsystem corresponding to the target DC transmission topology through multiple converters in a DC equivalent system according to the type of the target DC transmission topology; multiple converters in the DC equivalent system are combined and connected through switches to build equivalent subsystems corresponding to different types of DC transmission topologies; A test module, used to perform a simulated towing test on each converter in the target equivalent subsystem to obtain a plurality of simulated electrical parameters; A determination module is used to determine a stability verification result of the target direct current transmission topology according to the multiple simulated electrical parameters.

20. A controller comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 8 are implemented.

21. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

22. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 8 are implemented.

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