Converter station short-circuit current collaborative suppression method and system, terminal equipment and storage medium

Abstract

The invention discloses a converter station short-circuit current collaborative suppression method and system, terminal equipment and a storage medium. The method comprises the following steps: acquiring node short-circuit current of a to-be-tested flexible direct-current back-to-back converter station; constructing a short-circuit current loop model of the to-be-tested flexible direct current back-to-back converter station based on the electromagnetic transient simulation model and the node short-circuit current; selecting a target node from each converter station node based on the simulation configuration data, the fault working condition data and the short-circuit current loop model; performing impedance acquisition processing on the converter station nodes to obtain initial total impedance of the target nodes; performing impedance acquisition processing on the to-be-introduced node set and the converter station nodes to obtain a to-be-updated total impedance set of the target node; and selecting a target to-be-introduced node from the to-be-introduced node set based on the initial total impedance and the to-be-updated total impedance set, enabling the target to-be-introduced node to be connected with the target node, and carrying out short-circuit current suppression on the to-be-tested flexible direct current back-to-back converter station so as to suppress the excessive short-circuit current of the flexible direct current back-to-back converter station and improve the reliability.

Description

Technical Field

[0001] This invention relates to the field of coordinated suppression of short-circuit current in flexible DC back-to-back converter stations, and particularly to a method, system, terminal equipment, and storage medium for coordinated suppression of short-circuit current in converter stations. Background Technology

[0002] A power transmission network is a network that connects power plants, substations, or substations, and its main task is to transmit electrical energy. Based on the transmission voltage, it can be divided into high-voltage transmission networks (110-220 kV), ultra-high-voltage transmission networks (330-750 kV), and extra-high-voltage transmission networks (1000 kV and above).

[0003] Driven by the continuous development and improvement of the 500kV grid, urban power grids have gradually formed a network structure with a 500kV ring network as the main grid and 220kV grids as regional grids. With the rapid development of the power system, the power transmission capacity demand of existing 500kV lines is increasing, approaching their thermal stability limits. The grid structure on both sides of the transmission line is relatively dense, resulting in high short-circuit current levels at the busbars. If conventional methods of constructing new interconnecting lines are adopted, it may lead to excessive short-circuit currents at both busbars. Furthermore, some sections, such as those crossing rivers, present significant construction challenges, making it impossible to increase the transmission capacity by adding AC transmission lines.

[0004] Back-to-back DC transmission systems do not have DC transmission lines and can be used for interconnection or power transmission between two asynchronous AC power systems. The rectifier and inverter sides of a back-to-back DC transmission system are typically located in a single converter station, hence the name back-to-back converter station. Flexible back-to-back DC projects are a typical application of AC grid regional interconnection. Short-circuit current levels are a bottleneck restricting the operation and development of flexible DC grids. Currently, converter stations have dense loads and complex grid structures, and the problem of excessive short-circuit currents has long existed, making it difficult to simultaneously meet future power load development needs and improve the system's flexible control capabilities. Therefore, how to solve the problem of excessively high short-circuit currents in flexible back-to-back DC converter stations is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] This invention provides a method, system, terminal equipment, and storage medium for collaborative suppression of short-circuit current in converter stations, which can suppress excessively high or exceeding short-circuit currents in flexible DC back-to-back converter stations and improve the reliability of such stations.

[0006] To address the aforementioned technical problems, this invention provides a method for coordinated suppression of short-circuit current in converter stations, comprising the following steps:

[0007] Obtain the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test.

[0008] Based on the preset electromagnetic transient simulation model and the node short-circuit current, a short-circuit current loop model of the flexible DC back-to-back converter station under test is constructed.

[0009] Based on the preset simulation configuration data, the fault condition data of the converter station nodes, and the short-circuit current loop model, a target node is selected from each of the converter station nodes;

[0010] The converter station node is subjected to impedance acquisition processing to obtain the initial total impedance of the target node;

[0011] Impedance acquisition processing is performed on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set of the target nodes to be updated.

[0012] Based on the initial total impedance and the set of total impedances to be updated, a target node to be introduced is selected from the set of nodes to be introduced, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

[0013] In the above scheme, the short-circuit current of each converter station node is obtained to reflect the short-circuit current distribution of the flexible DC back-to-back converter station, providing a data foundation for subsequent steps. The short-circuit current of each converter station node and a preset electromagnetic transient simulation model are used to simulate the flexible DC back-to-back converter station under test, constructing a near-realistic short-circuit current loop model of the station. This facilitates obtaining the corresponding short-circuit current situation when introducing the set of nodes to be introduced. Based on the preset simulation configuration data, the fault condition data of the converter station nodes, and the short-circuit current loop model, the most dangerous target node with the highest short-circuit level is selected from the converter station nodes. This is used to locate key nodes when suppressing short-circuit current. By calculating the initial total impedance of the target node using the converter station nodes, the impact of the target node on the short-circuit current under the current network structure can be obtained. By considering the introduction of a set of nodes to be introduced, the total impedance set to be updated for the target node under different new network structures is calculated. This allows us to obtain the impact of different network structure changes under the influence of different introduced nodes on the short-circuit current, facilitating the subsequent selection of the optimal target node to be introduced and the construction of the most suitable network structure. By comparing the initial total impedance and the set of total impedance to be updated, the target node to be introduced that minimizes the short-circuit current of the target node is selected, thus achieving network structure optimization of the flexible DC back-to-back converter station under test. By introducing new branches to suppress the short-circuit current of the flexible DC back-to-back converter station under test, the reliability of the flexible DC back-to-back converter station under test is improved.

[0014] In the above scheme, by obtaining the equivalent reactance and equivalent resistance of the converter station, as well as the current direction characteristics under different power output types, the target power output type can be determined, thereby calculating the short-circuit current of each converter station node. This information is then used to construct a realistic short-circuit current loop model.

[0015] Furthermore, the selection of target nodes from among the various converter station nodes based on preset simulation configuration data, fault condition data of the converter station nodes, and the short-circuit current loop model includes:

[0016] Based on the preset simulation configuration data, the fault condition data of the converter station nodes and the short-circuit current loop model, the transient characteristic current of each converter station node is obtained.

[0017] Based on preset screening rules and the transient characteristic current, target nodes are selected from each of the converter station nodes.

[0018] In the above scheme, by utilizing simulation configuration data, fault condition data, and short-circuit current loop models, the transient characteristic current of each converter station node can be calculated, and target nodes can be selected based on screening rules. This allows for the accurate identification of the target node with the highest (most dangerous) short-circuit current level, thus determining the target node that needs to be suppressed.

[0019] Further, the impedance acquisition process performed on the converter station node to obtain the initial total impedance of the target node includes:

[0020] One candidate node is selected sequentially from the converter station nodes;

[0021] The node impedance of each candidate node and the target node is obtained to obtain the initial total impedance.

[0022] In the above scheme, the initial total impedance of the target node can be calculated through the converter station node. The initial total impedance can reflect the electrical characteristics of the target node under the current network structure.

[0023] Further, obtaining the node impedance of each candidate node and the target node to obtain the initial total impedance includes:

[0024] For each of the candidate nodes:

[0025] The branch between the target node and the candidate node is taken as the target node branch, and the branch between the target node and the other converter station nodes is taken as the first node branch.

[0026] The first node branch is updated to a short circuit or an open circuit to obtain the second node branch;

[0027] The node impedance of the target node branch is obtained based on the second node branch.

[0028] In the above scheme, by updating the branch of the first node to short-circuit or open-circuit, the node impedance between each candidate node and the target node can be calculated, and thus the corresponding node impedance can be obtained. This allows for a more accurate assessment of the impact of network structure changes on short-circuit current.

[0029] Further, the impedance acquisition process performed on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set to be updated for the target nodes includes:

[0030] Obtain the impedance to be updated for each node to be introduced in the set of nodes to be introduced and the target node;

[0031] The impedances to be updated of each of the nodes to be introduced are collected to obtain the total impedance set to be updated.

[0032] In the above scheme, by obtaining the impedance to be updated for each node to be introduced and the target node in the set of nodes to be introduced, a total impedance set to be updated can be constructed. This is used to subsequently modify the current network structure, thereby determining how to suppress short-circuit current.

[0033] Further, the step of selecting a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so as to connect the target node to the target node, and thereby suppress the short-circuit current of the flexible DC back-to-back converter station under test, includes:

[0034] Based on the ratio of each impedance to be updated in the total impedance set to be updated to the voltage of the target node, the short-circuit current set to be updated is obtained;

[0035] The initial short-circuit current is obtained based on the ratio of the initial total impedance to the voltage of the target node;

[0036] The difference between the initial short-circuit current and the short-circuit current to be updated in the set of short-circuit currents to be updated is obtained sequentially. The short-circuit current with the largest difference is selected from the set of short-circuit currents to be updated and used as the suppressed short-circuit current. The node to be introduced corresponding to the suppressed short-circuit current is taken as the target node to be introduced.

[0037] In the above scheme, the node to be introduced that can most effectively suppress the short-circuit current is determined by sequentially obtaining the difference between the initial short-circuit current and the short-circuit current to be updated in the set of short-circuit currents to be updated.

[0038] Further, the step of selecting a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so as to connect the target node to the target node, and thereby suppress the short-circuit current of the flexible DC back-to-back converter station under test, includes:

[0039] Connect the target node to be introduced to the target node, and obtain the short-circuit suppression current after the connection;

[0040] When the suppressed short-circuit current exceeds a preset limit, the power flow control of the flexible DC back-to-back converter station under test is stopped, and the interconnection channel of the target node is disconnected.

[0041] In the above scheme, the short-circuit current suppression effect can be optimized by connecting the target node to the target node. If the suppressed short-circuit current still exceeds the preset limit, measures such as stopping power flow regulation and performing disconnection are taken to ensure the safe and stable operation of the system.

[0042] Another embodiment of the present invention provides a converter station short-circuit current cooperative suppression system, comprising:

[0043] The acquisition module is used to acquire the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test.

[0044] The construction module is used to construct the short-circuit current loop model of the flexible DC back-to-back converter station under test based on the preset electromagnetic transient simulation model and the node short-circuit current.

[0045] The selection module is used to select a target node from each of the converter station nodes based on preset simulation configuration data, fault condition data of the converter station nodes, and the short-circuit current loop model.

[0046] The initial total impedance module is used to perform impedance acquisition processing on the converter station node to obtain the initial total impedance of the target node.

[0047] The total impedance set to be updated is used to perform impedance acquisition processing on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set to be updated for the target node.

[0048] The suppression module is used to select a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

[0049] Another embodiment of the present invention provides a terminal device, including: a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the steps of the converter station short-circuit current collaborative suppression method of the present invention.

[0050] Another embodiment of the present invention provides a computer-readable storage medium, comprising: a stored computer program, wherein when the computer program is executed, the device on which the computer-readable storage medium is located executes the steps of a converter station short-circuit current collaborative suppression method of the present invention. Attached Figure Description

[0051] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0052] Figure 1 This is a schematic flowchart of a method for collaborative suppression of short-circuit current in a converter station according to an embodiment of the present invention;

[0053] Figure 2 This is a schematic diagram of a converter station short-circuit current collaborative suppression system architecture provided in an embodiment of the present invention. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0055] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0056] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0057] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0058] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0059] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0060] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0061] See Figure 1 To suppress excessively high or exceeding short-circuit currents in flexible DC back-to-back converter stations and improve their reliability, an embodiment of the present invention provides a method for coordinated suppression of short-circuit currents in converter stations, comprising:

[0062] Step S1: Obtain the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test.

[0063] Step S2: Based on the preset electromagnetic transient simulation model and node short-circuit current, construct the short-circuit current loop model of the flexible DC back-to-back converter station under test;

[0064] Step S3: Based on the preset simulation configuration data, fault condition data of converter station nodes and short-circuit current loop model, select the target node from each converter station node;

[0065] Step S4: Perform impedance acquisition processing on the converter station nodes to obtain the initial total impedance of the target node;

[0066] Step S5: Perform impedance acquisition processing on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set of the target nodes to be updated;

[0067] Step S6: Based on the initial total impedance and the set of total impedances to be updated, select the target node to be introduced from the set of nodes to be introduced, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

[0068] In the above scheme, the short-circuit current of each converter station node is obtained to reflect the short-circuit current distribution of the flexible DC back-to-back converter station, providing a data foundation for subsequent steps. The short-circuit current of each converter station node and a preset electromagnetic transient simulation model are used to simulate the flexible DC back-to-back converter station under test, constructing a near-realistic short-circuit current loop model of the station. This facilitates obtaining the corresponding short-circuit current situation when introducing the set of nodes to be included. Based on the preset simulation configuration data, fault condition data of the converter station nodes, and the short-circuit current loop model, the most dangerous target node with the highest short-circuit level is selected from all converter station nodes. This is used to locate key nodes when suppressing short-circuit current. By calculating the initial total impedance of the target node using the converter station nodes, the impact of the target node on the short-circuit current under the current network structure can be obtained. By considering the introduction of a set of nodes to be introduced, the total impedance set to be updated for the target node under different new network structures is calculated. This allows us to obtain the impact of different network structure changes on the short-circuit current under the influence of different introduced nodes, facilitating the subsequent selection of the optimal target node to be introduced and the construction of the most suitable network structure. By comparing the initial total impedance and the set of total impedance to be updated, the target node to be introduced that minimizes the short-circuit current of the target node is selected, thus achieving network structure optimization of the flexible DC back-to-back converter station under test. By introducing new branches to suppress the short-circuit current of the flexible DC back-to-back converter station under test, the reliability of the flexible DC back-to-back converter station under test is improved.

[0069] Furthermore, when a three-phase low-resistance grounding or single-phase grounding fault occurs at the PCC point (point of common coupling), it is assumed that the direction of the AC system injection current to the PCC point lags behind the PCC point voltage by 90° under the fault condition, that is, Xeq>>Req. Since reactance dominates, the AC system injection current lags behind the PCC point voltage by 90°, thus obtaining the first current direction characteristic.

[0070] The selectable power output types include active power output and reactive power output. If the flexible DC power supply only outputs active power during a fault, meaning the output short-circuit current is in phase with the PCC point voltage, considering the shunting of the short-circuit current after the fault, when the grounding resistance is close to 0, the flexible DC current flowing into the grounding point is in phase with the PCC point voltage. This means the output current of the flexible DC converter station differs from the current injected into the short-circuit point by 90°, and in this case, the flexible DC power supply has no effect on the amplitude of the short-circuit current at the fault point. If only reactive power output is available, the flexible DC output current is in phase with the current injected into the short-circuit point by the AC system, and in this case, the flexible DC power supply affects the amplitude of the short-circuit current at the fault point. Therefore, the second current direction characteristic includes: when there is active power output, the flexible DC power supply has no effect on the amplitude of the short-circuit current at the fault point; and when there is reactive power output, the flexible DC power supply affects the amplitude of the short-circuit current at the fault point. Therefore, when constructing the short-circuit current loop model later, only the reactive power output case needs to be configured.

[0071] In another embodiment, based on preset simulation configuration data, fault condition data of converter station nodes, and short-circuit current loop models, a target node is selected from each converter station node, including:

[0072] Based on the preset simulation configuration data, fault condition data of converter station nodes and short-circuit current loop model, the transient characteristic current of each converter station node is obtained.

[0073] Based on preset screening rules and transient characteristic current, target nodes are selected from each converter station node.

[0074] It should be noted that, based on the preset electromagnetic transient simulation model and node short-circuit current, the short-circuit current loop model of the flexible DC back-to-back converter station to be tested is constructed. Specifically: the preset electromagnetic transient simulation model can be executed using the electromagnetic transient simulation software PSCAD. The specific implementation process of constructing the short-circuit current loop model in it is divided into the following stages: (1) Basic network architecture construction: call the standard power grid template from the component library, or manually construct the following core components: synchronous generator, three-phase transformer, transmission line, and load module.

[0075] (2) Fault Module Implantation: Drag and drop components simulating fault conditions in the power system to the target location (i.e., the specific location where the fault is desired to occur, usually set at the end of the bus or line) under the signal source classification. Key parameter configuration points:

[0076] Fault type selection: Three-phase metallic short circuit (ABC-G) is set as the default baseline condition;

[0077] Transition resistance settings: 0.001Ω for metallic grounding, and 5-20Ω for arc faults;

[0078] Triggering sequence: The preset initial fault time is 0.2 seconds, and the duration is 0.08 seconds (corresponding to the circuit breaker tripping time).

[0079] (3) Measurement system configuration:

[0080] A current measurement module should be installed 0.5 km downstream of the fault point, with a recommended sampling frequency of 100 kHz to capture transient processes. Using the simulation software's tools for displaying simulation results, create a monitoring panel containing the following parameters: instantaneous three-phase current values, zero-sequence current component, and short-circuit capacity.

[0081] (4) Model validation:

[0082] Power flow calculations were performed using a module with power flow calculation capabilities to ensure that the system voltage deviation before the fault was <±2%. At the same time, the fault distance was modified in batches (10%-90% of the line length) to verify the sensitivity of the short-circuit current loop model.

[0083] The following steps involve solving for the transient short-circuit currents at each converter station node:

[0084] PSCAD's short-circuit current calculation uses time-domain simulation to accurately simulate the dynamic characteristics of the entire fault process. The calculation process consists of three stages:

[0085] (1) Simulation parameter settings (i.e., simulation configuration data):

[0086] Configuration: Simulation duration, step size selection, and solver selection: Dommel implicit integration method (suitable for rigid systems).

[0087] Simulation duration: Covering the entire process of fault occurrence, development, and stabilization, it is usually set to 0.1s before the fault occurs to 0.5s after the fault is cleared, in order to fully capture the transient and steady-state characteristics of the short-circuit current.

[0088] Step size selection: The size of the step size has a significant impact on simulation accuracy and computational load. It is generally determined based on the system's time constant. For systems with rapidly changing transient processes, a smaller step size should be chosen, typically between 10⁻⁵ s and 10⁻³ s.

[0089] The choice of step size Δt must satisfy Shannon's sampling theorem, i.e. Where fmax is the highest frequency component that may occur in the system.

[0090] Solver selection: The Dommel implicit integration method is chosen, which is particularly suitable for rigid systems. Its core formula is based on the trapezoidal rule of integration. For inductive elements, the discretized equation in the time domain is:

[0091]

[0092] Where L is the inductance value, i k and i k+1 The currents at steps k and (k+1) are respectively, u k and u k+1 These are the voltages at step k and step (k+1), respectively. It's understandable that the above data represents the fault conditions of the converter station nodes.

[0093] (2) Eigenvalue current extraction:

[0094] After running the simulation, key parameters (transient characteristic currents) can be captured through the waveform analysis interface: peak impulse current, steady-state short-circuit current, and DC attenuation component. These parameters can comprehensively reflect the characteristics of the short-circuit current.

[0095] Peak inrush current I peak IC is the maximum current value that occurs instantaneously after a short circuit, and it has a significant impact on the dynamic stability of electrical equipment. Its magnitude is related to factors such as the system's short-circuit capacity, the distance to the short-circuit point, and the system's reactance, and can be expressed as IC. peak =K×I sym Where K is the impact factor, and for infinite capacity systems, K is typically taken as 1.8-2.5. sym This represents the effective value of the symmetrical short-circuit current.

[0096] Steady-state short-circuit current I ss Once the short-circuit process reaches a steady state, the value of the short-circuit current tends to stabilize; this current is called the steady-state short-circuit current. For a three-phase short circuit, its effective value... Where U is the effective value of the system line voltage, and Z is the equivalent impedance from the short-circuit point to the power supply.

[0097] DC attenuation component i dc (t): At the instant a short circuit occurs, due to the presence of inductance, a DC component is generated to maintain the continuity of the current. This component gradually decays over time. Its expression is i dc (t)=I dc0 e -t / τ , among which, I dc0 Let τ be the initial value of the DC component, τ be the time constant, τ = RL, L be the equivalent inductance of the system, and R be the equivalent resistance of the system.

[0098] After obtaining the aforementioned transient characteristic current, target nodes can be selected from each converter station node based on preset screening rules and transient characteristic current. The preset screening rules can be based primarily on steady-state short-circuit current: first, converter station nodes with steady-state short-circuit current greater than a preset steady-state short-circuit current threshold are screened; second, converter station nodes with peak impulse current greater than a preset peak impulse current threshold are screened; and finally, converter station nodes with DC attenuation component greater than a preset DC attenuation component threshold are screened a third time. If more than one converter station node is obtained after the final screening, the converter station node with the highest steady-state short-circuit current is selected as the target node.

[0099] (3) Results analysis: It can generate a short-circuit current report in a standard format.

[0100] In another embodiment, impedance acquisition processing is performed on the converter station nodes to obtain the initial total impedance of the target node, including:

[0101] One candidate node is selected sequentially from the converter station nodes;

[0102] Obtain the node impedance of each candidate node and the target node to get the initial total impedance.

[0103] In another embodiment, the node impedance of each candidate node and the target node is obtained to obtain the initial total impedance, including:

[0104] For each candidate node:

[0105] The branch between the target node and the candidate node is taken as the target node branch, and the branch between the target node and other converter station nodes is taken as the first node branch.

[0106] Update the first node branch to a short circuit or open circuit to obtain the second node branch;

[0107] The node impedance of the target node branch is obtained based on the second node branch.

[0108] It should be noted that the impedance acquisition process for converter station nodes specifically refers to the following branch addition method: All converter station nodes except the target node are considered candidate nodes; the target node is sequentially connected to one of the candidate nodes via a branch, and this branch is designated as the first node branch; the branches connecting the other candidate nodes to the target node are designated as second node branches, and these second node branches are replaced with short circuits or open circuits; the node impedance at this point is then obtained. After obtaining the node impedances corresponding to all candidate nodes, they are summed to obtain the initial total impedance of the target node.

[0109] In another embodiment, impedance acquisition processing is performed on a preset set of nodes to be introduced and converter station nodes to obtain a set of total impedances to be updated for the target nodes, including:

[0110] Obtain the impedance to be updated for each node to be introduced and the target node in the set of nodes to be introduced;

[0111] The impedances to be updated for each node to be introduced are collected to obtain the total impedance set to be updated.

[0112] It should be noted that, based on the initial total impedance, new branches are introduced from the nodes to be introduced to connect each node in the set of nodes to be introduced. Similar to the method described above, for each node to be introduced: the branch between the target node and the node to be introduced is taken as the target node to be introduced branch, and the branch between the target node and other nodes to be introduced is taken as the first node to be introduced branch; the first node to be introduced branch is updated to a short circuit or an open circuit to obtain the second node to be introduced branch; the impedance to be updated for the target node branch is obtained based on the second node to be introduced branch. The impedances to be updated for each node to be introduced are then set to obtain the set of total impedances to be updated.

[0113] In another embodiment, based on the initial total impedance and the set of total impedances to be updated, a target node to be introduced is selected from the set of nodes to be introduced, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test, including:

[0114] The set of short-circuit currents to be updated is obtained based on the ratio of each impedance to be updated in the total impedance set to be updated to the voltage of the target node.

[0115] The initial short-circuit current is obtained based on the ratio of the initial total impedance to the voltage of the target node;

[0116] The difference between the initial short-circuit current and the short-circuit current to be updated in the set of short-circuit currents to be updated is obtained sequentially. The short-circuit current with the largest difference is selected from the set of short-circuit currents to be updated and used as the suppressed short-circuit current. The node to be introduced corresponding to the suppressed short-circuit current is taken as the target node to be introduced.

[0117] It should be noted that the short-circuit current to be updated is obtained based on the voltage of the target node and the impedance to be updated. For the entire set of nodes to be introduced, a corresponding set of short-circuit currents to be updated is obtained. The short-circuit current with the smallest value is selected as the suppressed short-circuit current, and the node to be introduced corresponding to the suppressed short-circuit current is selected as the target node to be introduced. This indicates that when the target node to be introduced is introduced, a new network structure is constructed, and the short-circuit current of the flexible DC back-to-back converter station under test is suppressed.

[0118] In another embodiment, based on the initial total impedance and the set of total impedances to be updated, a target node to be introduced is selected from the set of nodes to be introduced, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test, including:

[0119] Connect the target node to be introduced to the target node, and obtain the short-circuit suppression current after the connection;

[0120] When the suppressed short-circuit current exceeds the preset limit, the power flow control of the flexible DC back-to-back converter station under test is stopped, and the interconnection channel of the target node is disconnected.

[0121] It should be noted that, based on existing knowledge, it can be first determined whether a short-circuit fault has occurred in the target node. If so, the decision on whether to implement a preset interruption strategy for the interconnection channel corresponding to the target node with the short-circuit fault is made based on the suppression of the short-circuit current: when the suppression of the short-circuit current exceeds a preset limit, power flow control of the tested flexible DC back-to-back converter station is stopped, and the interconnection channel of the target node is interrupted. Furthermore, upon determining that a short-circuit fault has occurred, power flow control of the target node with the short-circuit fault can be stopped first, and then it can be determined whether to interrupt the interconnection channel of the target node.

[0122] like Figure 2 As shown, based on the above method embodiments, corresponding system embodiments are provided;

[0123] An embodiment of the present invention provides a converter station short-circuit current cooperative suppression system, comprising:

[0124] The acquisition module is used to acquire the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test.

[0125] The module is used to construct a short-circuit current loop model of the flexible DC back-to-back converter station under test based on a preset electromagnetic transient simulation model and node short-circuit current.

[0126] The selection module is used to select a target node from each converter station node based on preset simulation configuration data, fault condition data of converter station nodes, and short-circuit current loop model.

[0127] The initial total impedance module is used to acquire the impedance of the converter station nodes and obtain the initial total impedance of the target node.

[0128] The total impedance set to be updated is used to perform impedance acquisition processing on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set to be updated for the target node.

[0129] The suppression module is used to select a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

[0130] It is understood that the above system embodiments correspond to the method embodiments of the present invention, and can implement the converter station short-circuit current collaborative suppression method provided by any of the above method embodiments of the present invention.

[0131] It should be noted that the system embodiments described above are merely illustrative, and some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the system embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0132] Based on the above embodiments of the converter station short-circuit current collaborative suppression method, another embodiment of the present invention provides a terminal device, which includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the converter station short-circuit current collaborative suppression method of any embodiment of the present invention.

[0133] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the terminal device.

[0134] The terminal device can be a desktop computer, laptop, handheld computer, or cloud server, etc. The terminal device may include, but is not limited to, a processor and memory.

[0135] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the terminal device, connecting all parts of the terminal device via various interfaces and lines.

[0136] The modules / units integrated into the system / terminal device, if implemented as software functional units and sold or used as independent products, can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the above embodiments of the present invention can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include: any entity or system capable of carrying the computer program code, recording media, USB flash drives, portable hard drives, magnetic disks, optical disks, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0137] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for coordinated suppression of short-circuit current in a converter station, characterized in that, include: Obtain the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test. Based on the preset electromagnetic transient simulation model and the node short-circuit current, a short-circuit current loop model of the flexible DC back-to-back converter station under test is constructed. Based on the preset simulation configuration data, the fault condition data of the converter station nodes, and the short-circuit current loop model, a target node is selected from each of the converter station nodes; The converter station node is subjected to impedance acquisition processing to obtain the initial total impedance of the target node; Impedance acquisition processing is performed on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set of the target nodes to be updated. Based on the initial total impedance and the set of total impedances to be updated, a target node to be introduced is selected from the set of nodes to be introduced, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

2. The method for coordinated suppression of short-circuit current in a converter station according to claim 1, characterized in that, The selection of target nodes from among the various converter station nodes, based on preset simulation configuration data, fault condition data of the converter station nodes, and the short-circuit current loop model, includes: Based on the preset simulation configuration data, the fault condition data of the converter station nodes and the short-circuit current loop model, the transient characteristic current of each converter station node is obtained. Based on preset screening rules and the transient characteristic current, target nodes are selected from each of the converter station nodes.

3. The method for coordinated suppression of short-circuit current in a converter station according to claim 1, characterized in that, The impedance acquisition process for the converter station node to obtain the initial total impedance of the target node includes: One candidate node is selected sequentially from the converter station nodes; The node impedance of each candidate node and the target node is obtained to obtain the initial total impedance.

4. The method for coordinated suppression of short-circuit current in a converter station according to claim 3, characterized in that, The step of obtaining the node impedance of each candidate node and the target node to obtain the initial total impedance includes: For each of the candidate nodes: The branch between the target node and the candidate node is taken as the target node branch, and the branch between the target node and the other converter station nodes is taken as the first node branch. The first node branch is updated to a short circuit or an open circuit to obtain the second node branch; The node impedance of the target node branch is obtained based on the second node branch.

5. The method for coordinated suppression of short-circuit current in a converter station according to claim 1, characterized in that, The process of obtaining impedance data from the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set to be updated for the target nodes includes: Obtain the impedance to be updated for each node to be introduced in the set of nodes to be introduced and the target node; The impedances to be updated of each of the nodes to be introduced are collected to obtain the total impedance set to be updated.

6. The method for coordinated suppression of short-circuit current in a converter station according to claim 5, characterized in that, The step of selecting a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so as to connect the target node to the target node, and then suppressing the short-circuit current of the flexible DC back-to-back converter station under test, includes: Based on the ratio of each impedance to be updated in the total impedance set to be updated to the voltage of the target node, the short-circuit current set to be updated is obtained; The initial short-circuit current is obtained based on the ratio of the initial total impedance to the voltage of the target node; The difference between the initial short-circuit current and the short-circuit current to be updated in the set of short-circuit currents to be updated is obtained sequentially. The short-circuit current with the largest difference is selected from the set of short-circuit currents to be updated and used as the suppressed short-circuit current. The node to be introduced corresponding to the suppressed short-circuit current is taken as the target node to be introduced.

7. The method for coordinated suppression of short-circuit current in a converter station according to claim 6, characterized in that, The step of selecting a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so as to connect the target node to the target node, and then suppressing the short-circuit current of the flexible DC back-to-back converter station under test, includes: Connect the target node to be introduced to the target node, and obtain the short-circuit suppression current after the connection; When the suppressed short-circuit current exceeds a preset limit, the power flow control of the flexible DC back-to-back converter station under test is stopped, and the interconnection channel of the target node is disconnected.

8. A converter station short-circuit current collaborative suppression system, characterized in that, include: The acquisition module is used to acquire the node short-circuit current of each converter node in the flexible DC back-to-back converter station under test. The construction module is used to construct the short-circuit current loop model of the flexible DC back-to-back converter station under test based on the preset electromagnetic transient simulation model and the node short-circuit current. The selection module is used to select a target node from each of the converter station nodes based on preset simulation configuration data, fault condition data of the converter station nodes, and the short-circuit current loop model. The initial total impedance module is used to perform impedance acquisition processing on the converter station node to obtain the initial total impedance of the target node. The total impedance set to be updated is used to perform impedance acquisition processing on the preset set of nodes to be introduced and the converter station nodes to obtain the total impedance set to be updated for the target node. The suppression module is used to select a target node to be introduced from the set of nodes to be introduced based on the initial total impedance and the set of total impedances to be updated, so that the target node to be introduced is connected to the target node, thereby suppressing the short-circuit current of the flexible DC back-to-back converter station under test.

9. A terminal device, characterized in that, The device includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements a converter station short-circuit current collaborative suppression method as described in any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, include: A stored computer program, wherein, when the computer program is executed, it controls the device containing the computer-readable storage medium to perform a converter station short-circuit current collaborative suppression method as described in any one of claims 1-7.

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