A fault current limiter site selection method and system for a multi-infeed dc receiving end power grid

Abstract

This invention discloses a method and system for selecting fault current limiters in multi-infeed DC receiving-end power grids, relating to the field of fault current limiter technology. The method includes the following steps: constructing a network model of the multi-infeed DC receiving-end power grid, the network model including the topology relationship between the AC and DC sides, converter station connection relationships, line parameters, and candidate locations for setting fault current limiters; determining network structure information under various operating conditions based on the network model; and acquiring the power grid's operating data and fault data; and generating a scenario set covering different operating conditions based on the operating data and fault data. This invention improves upon the traditional method of fault current limiter location selection in DC receiving-end power grids, which largely relies on experience-based judgment and suffers from low accuracy and poor deployment efficiency due to a lack of systematic quantitative analysis.

Description

Technical Field

[0001] This invention relates to the field of fault current limiter technology, and in particular to a fault current limiter location method and system in a multi-feed DC receiving-end power grid. Background Technology

[0002] With the widespread application of DC power grids in high-voltage DC transmission, multi-infeed receiving-end grids, distributed energy integration, and smart grids, the operational scale and topological complexity of power grids have increased significantly. Especially in multi-infeed DC receiving-end systems, multiple converter stations and DC feeders simultaneously connect to the same receiving-end network, forming a highly coupled power transmission structure that makes the correlation between power flow, fault current distribution, and voltage response more complex. Furthermore, with the increasing proportion of renewable energy integration, intensified load fluctuations, and the development of microgrids and distributed energy storage systems, the dynamic characteristics and transient responses of the power grid have become more difficult to predict. This complex grid structure not only places higher demands on operation control and protection strategies but also presents new challenges to grid security, stability, and fault handling capabilities.

[0003] The location selection of fault current limiters at the receiving end of traditional DC power grids mostly relies on experience-based judgment. Due to the lack of systematic and quantitative analysis, the location selection scheme has low accuracy and poor deployment efficiency. Summary of the Invention

[0004] To overcome the above shortcomings, this invention provides a method for selecting fault current limiters in multi-feed DC receiving-end power grids. It aims to improve the problem that the selection of fault current limiters in traditional DC receiving-end power grids mostly relies on experience-based judgment. Due to the lack of systematic quantitative analysis, the selection scheme has low accuracy and poor deployment efficiency.

[0005] This invention provides the following technical solution: a method for selecting a fault current limiter in a multi-feed DC receiving-end power grid, comprising the following steps: A network model of a multi-infeed DC receiving-end power grid is constructed. The network model includes the topological relationship between the AC side and the DC side, the connection relationship of the converter station, the line parameters, and the candidate locations of the configurable fault current limiter. Based on the network model, the network structure information under each operating state is determined, and the operating data and fault data of the power grid are obtained. The network structure information provides basic network data support for subsequent scenario set generation, disturbance calculation, and transient simulation. Based on the operational data and fault data, a scenario set covering different operational conditions is generated. The scenario set includes power flow states formed for different operational modes and fault state samples formed for different fault types. The parameters of the candidate locations are perturbed to determine the influence of the candidate locations on the fault current distribution and electrical coupling between regions. The influence relationship provides a quantitative analysis basis for the subsequent optimization algorithm to select the location combination. An optimization algorithm is used to select a combination of locations that meet the preset constraints from the candidate location set to form a primary fault current limiter layout scheme. The network transient behavior is simulated under the operating conditions and fault conditions corresponding to the scenario set, and the initial layout scheme is adjusted according to the simulation results to obtain a set of feasible layout schemes. The set of feasible layout schemes provides a basis for candidate schemes for subsequent protection zone division, regional boundary verification and final site selection. Based on the changes in electrical quantities caused by the installation of the fault current limiter, the division of the protection zone and the boundary of the area are checked, and the final fault current limiter location scheme is determined based on the check results.

[0006] By adopting the above technical solution, a network model of a multi-infeed DC receiving-end power grid is constructed and a scenario set covering different operating conditions is generated based on the model. Then, by performing parameter disturbance calculation and optimization screening on candidate locations, a fault current limiter layout scheme is obtained. This improves the problem that the traditional DC receiving-end power grid fault current limiter location selection mostly relies on experience judgment. Due to the lack of systematic quantitative analysis, the location scheme has low accuracy and poor layout efficiency.

[0007] Furthermore, the steps of constructing the network model of the multi-infeed DC receiving-end power grid and determining the corresponding network structure information include the following sub-steps: Collect topology information of the power grid, including the connection relationships of AC buses, DC buses, converter stations and lines; Electrical parameters, including impedance, reactance, capacitance, rated power, and rated current, are labeled for the lines and converter station nodes. Determine the locations where fault current limiters can be set and compile them into a candidate location set; An equivalent model of the coupling relationship between power and fault energy between converter stations is established, forming a coupling matrix between nodes; Based on the network topology and parameters, the power flow distribution, voltage level and branch load under each operating state are calculated to form network structure information; Historical operating data and fault data of the power grid are acquired and correlated with network structure information for subsequent analysis.

[0008] Furthermore, generating a scene set covering different operating conditions includes the following steps: Collect the power grid's operational and fault data; The operational data and fault data are preprocessed to form a dataset in a unified format; Extract operating status features from the operating data, and extract fault status features from the fault data; Cluster analysis is performed on the aforementioned operational status characteristics to obtain typical operational scenarios; Cluster analysis is performed on the fault state characteristics to obtain typical fault state samples; The typical operating scenarios are combined with the typical fault state samples to form a scenario set covering different operating conditions.

[0009] Furthermore, the perturbation calculation of the parameters at the candidate positions includes the following steps: Key network parameters for determining candidate locations are used as perturbation targets. Apply small positive or negative perturbations to the parameters at each candidate position; After applying the disturbance, calculate the fault current of each node in the network and the electrical coupling index between regions. Record the changes in electrical quantities at each node before and after the disturbance; The perturbation calculation results of all candidate locations are organized into a matrix showing the relationship between the candidate locations and the fault current distribution and coupling.

[0010] Furthermore, the step of selecting a combination of positions that satisfies preset constraints using an optimization algorithm includes the following steps: Based on the candidate location set and the analysis results of each location on the fault current distribution and inter-regional coupling relationship, an optimization objective function is constructed; Set constraints, including network power flow constraints, voltage stability constraints, and candidate location number constraints; Generate an initial set of location combination schemes from the candidate location set; The position combination scheme is iteratively updated according to the preset optimization algorithm rules; During the iteration process, combinations that do not meet the constraints are eliminated; Output the set of primary fault current limiter layout schemes that meet the constraints, obtained through iterative filtering.

[0011] Furthermore, the simulated network transient behavior includes the following steps: Obtain the operating conditions and fault conditions in the scenario set; Load the candidate location parameters of the primary fault current limiter layout scheme into the network model; Transient simulations were performed for each combination of operating and fault conditions to calculate the changes in voltage at each node, line current, and converter station status over time. Calculate the voltage changes of each node over time, including bus voltage dips, converter station commutation status, and changes in electrical coupling between regions; Record candidate locations and node information that pose a transient risk; Adjust the initial layout scheme based on the simulation results to form a set of feasible layout schemes.

[0012] Furthermore, the verification of the protected area segment division and regional boundaries includes the following steps: Obtain the set of feasible layout schemes and the corresponding power grid parameters; Calculate the impedance, fault current direction, and protection criterion changes for each protected section under each candidate layout scheme; Verify that each protection setting meets the selectivity and operating time requirements; Analyze the boundary currents of the zones and the coupling between zones to check for potential risks of protection maloperation or failure to operate; Record the parameters that need to be adjusted for the protected areas or boundaries where problems exist; Output the verification results to guide the final site selection.

[0013] Furthermore, determining the final fault current limiter location scheme includes the following steps: Combine the set of feasible layout schemes with the verification results; Each candidate scheme is ranked based on its fault current suppression effect, transient response, zonal coordination, and compliance with protection setting requirements. The optimal solution that satisfies all constraints is selected based on the sorting results. Output the final site selection plan, including the determined installation location of the fault current limiter, the division of the protection zone, and the information on the area boundaries.

[0014] This invention also provides a fault current limiter location system in a multi-feed DC receiving-end power grid, comprising the following modules: The network modeling initialization module is used to construct a network model of a multi-infeed DC receiving-end power grid. The network model includes the topological relationship between the AC side and the DC side, the connection relationship of the converter station, the line parameters, and the candidate positions of the configurable fault current limiter. Based on the network model, the module determines the network structure information under each operating state and obtains the operating data and fault data of the power grid. The scenario set generation module is used to generate a scenario set covering different operating conditions based on the operating data and fault data. The scenario set includes power flow states formed for different operating modes and fault state samples formed for different fault types. The disturbance impact analysis module is used to perform disturbance calculations on the parameters of candidate locations and determine the impact of candidate locations on fault current distribution and electrical coupling between regions. The optimization and screening module is used to select a combination of positions that meet preset constraints from the candidate position set using an optimization algorithm, thereby forming a primary fault current limiter arrangement scheme. The transient simulation verification module is used to simulate the transient behavior of the network under the operating conditions and fault conditions corresponding to the scenario set, and adjust the primary layout scheme according to the simulation results to obtain a set of feasible layout schemes. The protection zone verification module is used to verify the division of protection zones and the boundaries of the zones based on the changes in electrical quantities caused by the setting of the fault current limiter, and to determine the final fault current limiter location scheme based on the verification results.

[0015] The present invention has the following beneficial effects: 1. In this invention, a network model of a multi-infeed DC receiving-end power grid is constructed and a scenario set covering different operating conditions is generated based on the model. Then, a fault current limiter arrangement scheme is obtained by performing parameter perturbation calculation and optimization screening on candidate locations. This improves the problem that the location of fault current limiters in traditional DC receiving-end power grids mostly relies on experience judgment. Due to the lack of systematic quantitative analysis, the location scheme has low accuracy and poor arrangement efficiency.

[0016] 2. In this invention, by simulating the transient behavior of the network under multiple operating conditions and fault conditions on the preliminary layout scheme, and then adjusting the scheme based on the simulation results to form a set of feasible layout schemes, the traditional method usually ignores transient response in the site selection process. Since the transient behavior is not fully considered, the site selection scheme may have transient risks in actual operation.

[0017] 3. In this invention, by verifying the division of the protection zone and the regional boundary and combining feasible layout schemes to screen the final site selection scheme, the traditional method is improved by the lack of protection coordination verification after the fault current limiter is arranged. Due to the lack of systematic verification of the section protection and boundary settings, the site selection scheme may cause the protection to malfunction or fail to operate. Attached Figure Description

[0018] Figure 1 This is a flowchart of a fault current limiter location method in a multi-feed DC receiving-end power grid proposed in this invention; Figure 2 This is an architecture diagram of a fault current limiter in a multi-feed DC receiving-end power grid, as proposed in an embodiment of the present invention. Detailed Implementation

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0020] In a first embodiment of the present invention, the present invention provides a method for selecting a fault current limiter in a multi-feed DC receiving-end power grid, such as... Figure 1As shown, the process includes the following steps: constructing a network model of a multi-infeed DC receiving-end power grid, including the topological relationship between the AC and DC sides, the connection relationship of converter stations, line parameters, and candidate locations for configurable fault current limiters; determining the network structure information under each operating state based on the network model; and acquiring the power grid's operating data and fault data. Furthermore, the steps for constructing a network model of a multi-infeed DC receiving-end power grid and determining the corresponding network structure information include the following sub-steps: Collect topology information of the power grid, including the connection relationships of AC buses, DC buses, converter stations and lines; Label the electrical parameters for line and converter station nodes, including impedance, reactance, capacitance, rated power and rated current; Determine the locations where fault current limiters can be set and compile them into a candidate location set; An equivalent model of the coupling relationship between power and fault energy between converter stations is established, forming a coupling matrix between nodes; Based on the network topology and parameters, the power flow distribution, voltage level and branch load under each operating state are calculated to form network structure information; Historical operating and fault data of the power grid are acquired and correlated with network structure information for subsequent analysis.

[0021] Specifically, a network model of a multi-infeed DC receiving-end power grid is constructed to obtain the basic network structure quantities required for subsequent site selection calculations. This model is formed by first acquiring the connection relationships of AC buses, DC buses, converter stations, and lines based on information collection, and then generating a set of nodes and branches for the network topology. Furthermore, parameters such as impedance, reactance, capacitance, rated power, and rated current are labeled for each line and converter station node. Line impedance is expressed in complex form as a combination of resistance and reactance, and the operating capacity of the converter station is described by rated power and commutation capacity. Based on the power exchange characteristics between converter stations and the propagation path of fault energy in the network, an equivalent model describing the node coupling relationships is constructed, forming a node coupling matrix, which is represented by the symbol... ; where matrix elements Determined based on the equivalent relationships of line parameters and power flow paths between nodes, used to characterize nodes. With nodes The degree of coupling between nodes in terms of power and fault energy transfer; based on topology and parameter information, calculations are performed on the power flow distribution under each operating mode, and the power flow balance equations include the node injection power balance equation. and reactive power balancing ;in and These represent the active and reactive power injections of the nodes, respectively. and The node voltage amplitude, To determine the phase angle difference of node voltages, the power flow distribution, voltage level, and branch load of each node are obtained by solving this set of equations, forming network structure information under different operating conditions. Subsequently, historical operating data and fault data of the power grid are collected and correlated with the aforementioned network structure information to ensure that operating quantities, fault quantities, and model quantities correspond within a unified data framework. This allows the model construction results to be used for subsequent scenario set construction, parameter disturbance analysis, and location scheme calculation. The network model output obtained through the above processing includes the topology of the AC and DC sides, electrical parameters of lines and converter stations, node coupling matrices, and power flow and voltage states under multiple operating conditions. Subsequent steps use these results as inputs to generate scenario sets, perform disturbance calculations, perform optimized location selection, and conduct transient simulations, thereby achieving effective derivation of fault current limiter placement schemes in the network.

[0022] Based on operational data and fault data, a scenario set covering different operational conditions is generated. The scenario set includes power flow states formed for different operational modes and fault state samples formed for different fault types. Furthermore, generating a set of scenarios covering different operating conditions includes the following steps: Collect power grid operation data and fault data; The operational and fault data are preprocessed to form a dataset in a unified format; Extract operational status features from operational data, and extract fault status features from fault data; Cluster analysis of operational status characteristics yields typical operational scenarios; Cluster analysis was performed on the fault state characteristics to obtain typical fault state samples; Typical operating scenarios are combined with typical fault state samples to form a scenario set covering different operating conditions.

[0023] Specifically, the input data consists of power grid operation data and fault data. After collection, this data undergoes denoising, format normalization, and time scale alignment to form a unified dataset suitable for subsequent analysis. Based on this, operation status features characterizing power flow distribution, voltage levels, and line load conditions are extracted from the operation data, and fault status features characterizing fault location, fault type, and transient electrical quantity change patterns are extracted from the fault data. These features are represented as feature vectors. The operation status feature vector can be represented as follows: The fault state feature vector can be represented as To obtain typical operating scenarios that statistically cover different operating modes, cluster analysis is performed on the operating state feature vectors. Several operating state cluster centers are obtained by minimizing intra-cluster distances. These cluster centers can be represented as... ;in For the first The sample set contained in the class, The number of samples in the set; similarly, by performing clustering on the fault state feature vectors, several fault state class centers are obtained, which can be represented as... ,in For the first The class contains a set of fault samples. Let be the number of samples in the set; combine the obtained operational class centers and fault class centers to form a scenario set for subsequent verification and simulation calculations. The combination method can be represented as follows: Each scenario record consists of a typical operating state and a typical fault state sample. This scenario set is used in subsequent steps to evaluate the changes in electrical quantities after the fault current limiter is set, verify the area division and the zoning scheme, so that the evaluation process can cover multiple operating modes and multiple fault conditions, and improve the reliability of the zoning verification.

[0024] The parameters of the candidate locations are perturbed to determine the influence of the candidate locations on the fault current distribution and the electrical coupling between regions. Furthermore, the perturbation calculation of the parameters at the candidate locations includes the following steps: Key network parameters for determining candidate locations are used as perturbation targets. Apply small positive or negative perturbations to the parameters at each candidate position; After applying the disturbance, calculate the fault current of each node in the network and the electrical coupling index between regions. Record the changes in electrical quantities at each node before and after the disturbance; The perturbation calculation results of all candidate locations are organized into a matrix showing the relationship between the candidate locations and the fault current distribution and coupling.

[0025] Specifically, the input data consists of key network parameters corresponding to candidate locations obtained from the power grid model and operational records. These parameters can be expressed as follows: This is derived from the extraction of power grid topology, line parameters, and device ratings. After determining the key network parameters, small positive and negative perturbations are applied to the parameters at each candidate location. The perturbed parameters can be expressed as follows: and ;in For the disturbance amplitude, For small-amplitude positive and negative disturbances, the disturbance amplitude The reference electrical parameter values ​​for the candidate locations are 0.5% to 5%, with a preferred value of 1% to 3%. The reference electrical parameters are the nominal parameters of the corresponding lines and components under rated power grid operating conditions. After applying the disturbance, the fault current at each node is calculated based on the power grid fault calculation model. The fault current can be expressed as... ;in This demonstrates the fault current calculation model and simultaneously obtains the electrical coupling index between regions. The coupling index can be expressed as: ; the electrical quantity before the disturbance By differentiating the electrical quantities after the disturbance, the change in nodal electrical quantities can be obtained. and Similarly, the coupling change amount is obtained. and The perturbation calculation results for all candidate locations are organized, and the candidate location indices are matched with their corresponding indices. Composition matrix Each row in the matrix corresponds to the disturbance response characteristics of a candidate location. This matrix serves as the input for subsequent area division verification and device location optimization. It is used to quantify the impact of changes in candidate location parameters on the fault current distribution and electrical coupling relationship between areas, enabling subsequent location decisions to be sorted and screened based on the disturbance sensitivity of different candidate locations, thereby improving the rationality of the zoning scheme determination process.

[0026] An optimization algorithm is used to select a combination of locations that meet the preset constraints from the candidate location set to form a primary fault current limiter layout scheme. Furthermore, selecting the combination of positions that satisfies the preset constraints using an optimization algorithm includes the following steps: Based on the candidate location set and the analysis results of each location on the fault current distribution and inter-regional coupling relationship, an optimization objective function is constructed; Set constraints, including network power flow constraints, voltage stability constraints, and candidate location number constraints; Generate an initial set of location combination schemes from the candidate location set; The position combination scheme is iteratively updated according to the preset optimization algorithm rules; During the iteration process, combinations that do not meet the constraints are eliminated; Output the set of primary fault current limiter layout schemes that meet the constraints, obtained through iterative filtering.

[0027] Specifically, the input data consists of an index set of candidate locations and the quantification results of the relationship between each candidate location and the fault current distribution and inter-regional coupling, obtained from perturbation calculation and network analysis. These quantification results can be represented as a response matrix. ;based on and Construct an optimization objective function, which can be expressed as reducing the peak fault current or weakening the coupling between regions. The objective function can be expressed in the form of: ,in This represents the candidate position selection vector. Indicates the first Whether each candidate position is selected. and Respectively represent the first The influence of fault current and coupling effect at each candidate location and The weight parameters are defined; constraints are set for the optimization process, including network power flow constraints, which can be expressed as follows: The voltage stability constraint can be expressed as The constraint on the number of candidate positions can be expressed as follows: Based on this, an initial set of position combination schemes is generated from the candidate position set, which can be represented as follows: The location combination scheme is iteratively updated according to the preset optimization algorithm rules. The update method can be expressed as follows: ,in This represents the transformation rules used to update the combined schemes; as the iteration progresses, constraint checks are performed on each generated scheme, eliminating schemes that do not meet power flow constraints, voltage stability constraints, or quantity constraints; finally, the output is a set of primary fault current limiter placement schemes that meet the constraints after iterative filtering. This set of schemes serves as input for the next step of zoning verification and final site selection decision. It is used to further evaluate multiple constrained layout schemes based on zoning effects, coupling reduction effects, and operational feasibility, thereby achieving a complete closed-loop process for device site selection.

[0028] Simulate the transient behavior of the network under the corresponding operating conditions and fault conditions in the scenario set, and adjust the initial layout scheme based on the simulation results to obtain a set of feasible layout schemes; Furthermore, simulating network transient behavior includes the following steps: Obtain the operating conditions and fault conditions in the scenario set; Load the candidate location parameters of the primary fault current limiter layout scheme into the network model; Transient simulations were performed for each combination of operating and fault conditions to calculate the changes in voltage at each node, line current, and converter station status over time. Calculate the voltage changes of each node over time, including bus voltage dips, converter station commutation status, and changes in electrical coupling between regions; Record candidate locations and node information that pose a transient risk; Adjust the initial layout scheme based on the simulation results to form a set of feasible layout schemes.

[0029] Specifically, the input data is a set of runtime conditions within the scenario set. With fault condition set And the parameter set of each candidate location in the initial layout scheme. The operating conditions include power flow distribution, node voltage levels, and converter station power allocation; the fault conditions include fault type, fault location, and fault clearing sequence; and the parameter set... Derived from the output of the aforementioned optimization and screening steps; the parameter set is loaded into the network model consisting of network topology and line electrical parameters, and transient simulation is performed under each combination of operating and fault conditions. During the transient solution process, the voltage state vector is used as the output. With current state vector As the solution variable, the network transient model, expressed in the form of a system of difference equations, is used for numerical calculation. The equation expression can be written as follows: ;in This represents the state vector of node voltage and line current. The matrix represents the external excitation determined by both operating conditions and failure conditions. and Determined by network parameters; node voltage sequences are obtained during the calculation process. and line current sequence Simultaneously, the time-varying sequence of converter station state variables is obtained, such as the commutation angle. Commutation failure risk indicators; voltage changes at each node during transient processes are recorded based on simulation output. The coupling change was obtained by combining the electrical coupling relationship between regions. Under all combinations of operating and fault conditions, the transient quantities mentioned above are analyzed to identify nodes where voltage dips, line current surges, and converter station state changes exceed preset thresholds, along with their corresponding candidate locations. Based on these transient risk results, the initial layout scheme is adjusted, eliminating location combinations that do not meet transient safety requirements and retaining schemes that do meet transient safety requirements, ultimately forming a set of feasible layout schemes. This set of feasible layout schemes is used for the next step of protection section verification and final site selection decision, realizing a closed-loop process from initial screening to feasible configuration verification.

[0030] Based on the changes in electrical quantities caused by the installation of the fault current limiter, the division of the protection zone and the boundary of the zone are checked, and the final fault current limiter location scheme is determined based on the check results. Furthermore, the verification of the protected area segment division and regional boundaries includes the following steps: Obtain a set of feasible layout schemes and corresponding power grid parameters; Calculate the impedance, fault current direction, and protection criterion changes for each protected section under each candidate layout scheme; Verify that each protection setting meets the selectivity and operating time requirements; Analyze the boundary currents of the zones and the coupling between zones to check for potential risks of protection maloperation or failure to operate; Record the parameters that need to be adjusted for the protected areas or boundaries where problems exist; Output the verification results to guide the final site selection.

[0031] Specifically, the input data is a set of feasible layout schemes. and the corresponding power grid parameter set The feasible arrangement scheme set is derived from the output of the aforementioned transient simulation screening step. The power grid parameter set includes line impedance, node voltage, short-circuit capacity, relay protection settings, and regional topology. For each arrangement scheme in the feasible arrangement scheme set, the corresponding fault current limiter parameters are loaded into the power grid model, and the impedance values ​​of each protected section are obtained through fault calculation methods. and the distribution of fault current caused by the fault point The direction of the fault current is obtained by combining the node voltage sequence and branch parameters. The typical current calculation process can be expressed as follows: ,in For nodal potential, For the node equivalent impedance, The equivalent impedance at the fault point; the changes in each protection criterion are analyzed based on the fault current results. The results are compared with the original values ​​to verify whether the selectivity and operating time of each protection device meet the requirements, and the time setting equation is used. The adjusted operating time is calculated to determine whether reliable coordination can still be maintained; based on this, the boundary current of each region is further calculated. Inter-regional coupling index From the current difference value and the change value of coupling index Identify potential risks of protection malfunctions or failures to operate, and record the section parameters and zone boundaries that need to be readjusted under each layout scheme; after completing the verification of all layout schemes, compile the verification results for each scheme into a verification information set. This verification information set serves as the input for determining the next site selection scheme. In the final decision-making process, it is used to eliminate schemes with protection coordination risks, thereby ensuring that the final location selection can meet the requirements of protection zone division and regional boundary stability, and realizing a complete closed loop of power grid protection adaptability verification and scheme selection logic.

[0032] Furthermore, determining the final fault current limiter location scheme includes the following steps: Combine the set of feasible layout schemes with the verification results; Each candidate scheme is ranked based on its fault current suppression effect, transient response, zonal coordination, and compliance with protection setting requirements. The optimal solution that satisfies all constraints is selected based on the sorting results. Output the final site selection plan, including the determined installation location of the fault current limiter, the division of the protection zone, and the information on the area boundaries.

[0033] Specifically, the input data is a set of feasible layout schemes. and the corresponding verification result set The feasible layout scheme set is derived from the transient simulation screening step, and the verification result set is derived from the protection section and regional boundary verification step. Its contents include fault current variation, protection setting matching status, regional boundary current variation, and potential risk markers. By associating the feasible layout scheme set with the verification results, a comprehensive evaluation quantity is constructed for each scheme. The evaluation metrics are calculated jointly by fault current suppression performance, transient response characteristics, zonal coordination indicators, and protection setting satisfaction. A typical comprehensive evaluation can be expressed as follows: ,in The degree of fault current suppression, It is a characteristic quantity of transient electrical quantity change. For the coordination indicators of the zones, To protect the degree of satisfaction of the set value, and The weighting coefficients are used to ensure consistency of the indicator dimensions; all candidate solutions are ranked based on the comprehensive evaluation quantity, and the optimal solution set is obtained by screening solutions whose evaluation quantities satisfy the constraints. The system extracts the fault current limiter location parameters, protection zone division results, and regional boundary information corresponding to the final location scheme from the scheme set, forming the final location scheme output, which is used for the subsequent implementation of fault current limiter engineering configuration and protection setting of multi-infeed DC receiving-end system.

[0034] Example 2: In a second embodiment of the present invention, the present invention provides a fault current limiter addressing system in a multi-feed DC receiving-end power grid, such as... Figure 2 As shown, it includes the following modules: The network modeling initialization module is used to construct a network model of a multi-infeed DC receiving-end power grid. The network model includes the topological relationship between the AC side and the DC side, the connection relationship of the converter station, the line parameters, and the candidate positions of the configurable fault current limiter. Based on the network model, the module determines the network structure information under each operating state and obtains the operating data and fault data of the power grid. The scenario set generation module is used to generate a scenario set covering different operating conditions based on the operating data and fault data. The scenario set includes power flow states formed for different operating modes and fault state samples formed for different fault types. The disturbance impact analysis module is used to perform disturbance calculations on the parameters of candidate locations and determine the impact of candidate locations on fault current distribution and electrical coupling between regions. The optimization and screening module is used to select a combination of positions that meet preset constraints from the candidate position set using an optimization algorithm, thereby forming a primary fault current limiter arrangement scheme. The transient simulation verification module is used to simulate the transient behavior of the network under the operating conditions and fault conditions corresponding to the scenario set, and adjust the primary layout scheme according to the simulation results to obtain a set of feasible layout schemes. The protection zone verification module is used to verify the division of protection zones and the boundaries of the zones based on the changes in electrical quantities caused by the setting of the fault current limiter, and to determine the final fault current limiter location scheme based on the verification results.

[0035] A coastal region is planning to construct a multi-infeed DC receiving-end power grid. Because multiple DC lines converge simultaneously in the same receiving-end area, the electrical coupling relationships are complex, and fault current paths change frequently. This makes it difficult for traditional experience-based current limiter placement methods to ensure transient stability and consistency with protected area divisions. To solve these problems, this invention provides a fault current limiter location system for multi-infeed DC receiving-end power grids, the structure of which is as follows: Figure 2 As shown. The specific implementation process of this system is as follows: The network modeling initialization module first constructs a global network model including the AC and DC side topologies, converter station connections, and line parameters, and includes all locations where fault current limiters can be configured in the candidate set. Based on the model, the module automatically identifies network structure characteristics under different operating modes, retrieves corresponding operating and fault data, and ensures that the structural state of the entire power grid under various operating conditions can be accurately represented. This provides a consistent data foundation for subsequent analysis and avoids information gaps and judgment biases caused by manual modeling.

[0036] The scenario set generation module uses the acquired operational and fault data to generate a complete scenario set covering multiple operating modes. The scenario set includes both power flow distribution status and typical fault scenarios. By integrating multiple types of operating conditions, the module enables the system to maintain analytical consistency under conditions such as load fluctuations, DC blocking, and line maintenance. This avoids the problem of overly specific solutions resulting from traditional single-condition-based judgments, ensuring that subsequent deployment results have universality and adaptability.

[0037] The disturbance impact analysis module performs parameter disturbance calculations on candidate locations, obtaining changes in fault current distribution and the degree of electrical coupling between areas by adjusting local parameters at the set locations. During the calculation process, the module can automatically identify the influence intensity of different candidate locations on critical current paths, allowing effective installation points to naturally emerge from all candidate points. This avoids errors caused by manual selection based on experience, making the effect of the current limiter clearer and more quantifiable.

[0038] The optimization and layout module uses a multi-objective optimization algorithm to select layout combinations from the candidate location set that meet current limits, safety constraints, cost limitations, and construction conditions based on the disturbance analysis results. During the search process, the module dynamically balances the current limiting effect, system safety margin, and economy, ensuring that the initial layout scheme is feasible without favoring any single indicator, thus overcoming the limitation of traditional designs that over-rely on single-point indicators.

[0039] The transient simulation verification module performs power grid transient simulations on the primary scheme under the corresponding operating and fault conditions in the scenario set, and evaluates the effectiveness of the scheme based on the fault current decay rate, inter-regional power exchange changes, and system stability performance. By comparing the results of different dynamic responses, the module eliminates combinations that do not meet the transient stability requirements, ensuring that the remaining layout schemes all have the ability to maintain regional boundary stability under sudden faults, thereby ensuring that the schemes can adapt to the rapid changes in actual operation.

[0040] The protection zone verification module automatically verifies the protection zone division and boundary conditions based on the changes in electrical quantities after setting the fault current limiter, and adjusts the relay protection setting range to ensure that the final layout scheme maintains consistency between current limiting effect and protection coordination. The module ensures that electrical zones remain clear and independent under the action of the current limiter, fundamentally avoiding protection dead zones and out-of-zone malfunctions, ultimately resulting in a fault current limiter location scheme that can be directly used for engineering implementation.

[0041] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for selecting a fault current limiter in a multi-feed DC receiving-end power grid, characterized in that, Includes the following steps: A network model of a multi-infeed DC receiving-end power grid is constructed. The network model includes the topological relationship between the AC side and the DC side, the connection relationship of the converter station, the line parameters, and the candidate locations of the fault current limiter. Based on the network model, the network structure information under each operating state is determined, and the operating data and fault data of the power grid are obtained. Based on the network structure information, operational data, and fault data, a scenario set covering different operational conditions is generated. The scenario set includes power flow states formed for different operational modes and fault state samples formed for different fault types. The parameters of the candidate locations are perturbed to determine the influence of the candidate locations on the fault current distribution and the electrical coupling between regions. Based on the influence of the candidate locations on the fault current distribution and inter-regional electrical coupling, an optimization algorithm is used to select a combination of locations that meet the preset constraints from the candidate location set to form a primary fault current limiter arrangement scheme. Simulate network transient behavior under the operating and fault conditions corresponding to the scenario set, and adjust the primary fault current limiter layout scheme according to the simulation results to obtain a set of feasible layout schemes; Based on the set of feasible layout schemes, the division of the protection zone and the boundary of the area are checked according to the changes in electrical quantities caused by the installation of the fault current limiter, and the final fault current limiter location scheme is determined based on the check results.

2. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The steps for constructing a network model of a multi-infeed DC receiving-end power grid and determining the corresponding network structure information include the following sub-steps: Collect topology information of the power grid, including the connection relationships of AC buses, DC buses, converter stations and lines; Electrical parameters, including impedance, reactance, capacitance, rated power, and rated current, are labeled for the lines and converter station nodes. Determine the locations where fault current limiters can be set and compile them into a candidate location set; An equivalent model of the coupling relationship between power and fault energy between converter stations is established, forming a coupling matrix between nodes; Based on the network topology and parameters, the power flow distribution, voltage level and branch load under each operating state are calculated to form network structure information; Historical operating data and fault data of the power grid are acquired and correlated with network structure information for subsequent analysis.

3. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The process of generating a scene set covering different operating conditions includes the following steps: Collect the power grid's operational and fault data; The operational data and fault data are preprocessed to form a dataset in a unified format; Extract operating status features from the operating data, and extract fault status features from the fault data; Cluster analysis is performed on the aforementioned operational status characteristics to obtain typical operational scenarios; Cluster analysis is performed on the fault state characteristics to obtain typical fault state samples; The typical operating scenarios are combined with the typical fault state samples to form a scenario set covering different operating conditions.

4. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The perturbation calculation of the parameters at the candidate positions includes the following steps: Key network parameters for determining candidate locations are used as perturbation targets. Apply small positive or negative perturbations to the parameters at each candidate position; After applying the disturbance, calculate the fault current of each node in the network and the electrical coupling index between regions. Record the changes in electrical quantities at each node before and after the disturbance; The perturbation calculation results of all candidate locations are organized into a matrix showing the relationship between the candidate locations and the fault current distribution and coupling.

5. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The step of selecting a combination of positions that meets preset constraints using an optimization algorithm includes the following steps: Based on the candidate location set and the analysis results of each location on the fault current distribution and inter-regional coupling relationship, an optimization objective function is constructed; Set constraints, including network power flow constraints, voltage stability constraints, and candidate location number constraints; Generate an initial set of location combination schemes from the candidate location set; The position combination scheme is iteratively updated according to the preset optimization algorithm rules; During the iteration process, combinations that do not meet the constraints are eliminated; Output the set of primary fault current limiter layout schemes that meet the constraints, obtained through iterative filtering.

6. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The simulated network transient behavior includes the following steps: Obtain the operating conditions and fault conditions in the scenario set; Load the candidate location parameters of the primary fault current limiter layout scheme into the network model; Transient simulations were performed for each combination of operating and fault conditions to calculate the changes in voltage at each node, line current, and converter station status over time. Calculate the voltage changes of each node over time, including bus voltage dips, converter station commutation status, and changes in electrical coupling between regions; Record candidate locations and node information that pose a transient risk; Adjust the initial layout scheme based on the simulation results to form a set of feasible layout schemes.

7. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The verification of the protected area segment division and regional boundaries includes the following steps: Obtain the set of feasible layout schemes and the corresponding power grid parameters; Calculate the impedance, fault current direction, and protection criterion changes for each protected section under each candidate layout scheme; Verify that each protection setting meets the selectivity and operating time requirements; Analyze the boundary currents of the zones and the coupling between zones to check for potential risks of protection maloperation or failure to operate; Record the parameters that need to be adjusted for the protected areas or boundaries where problems exist; Output the verification results to guide the final site selection.

8. The method for selecting a fault current limiter in a multi-feed DC receiving-end power grid according to claim 1, characterized in that, The process of determining the final fault current limiter location scheme includes the following steps: Combine the set of feasible layout schemes with the verification results; Each candidate scheme is ranked based on its fault current suppression effect, transient response, zonal coordination, and compliance with protection setting requirements. Based on the sorting results, select the solutions that satisfy all constraints; Output the final site selection plan, including the determined installation location of the fault current limiter, the division of the protection zone, and the information on the area boundaries.

9. A fault current limiter addressing system for a multi-feed DC receiving-end power grid that implements the method of any one of claims 1-8, characterized in that, Includes the following modules: The network modeling initialization module is used to construct a network model of a multi-infeed DC receiving-end power grid. The network model includes the topological relationship between the AC side and the DC side, the connection relationship of the converter station, the line parameters, and the candidate positions of the configurable fault current limiter. Based on the network model, the module determines the network structure information under each operating state and obtains the operating data and fault data of the power grid. The network structure information provides basic network data support for subsequent scenario set generation, disturbance calculation, and transient simulation. The scenario set generation module is used to generate a scenario set covering different operating conditions based on the operating data and fault data. The scenario set includes power flow states formed for different operating modes and fault state samples formed for different fault types. The disturbance impact analysis module is used to perform disturbance calculations on the parameters of candidate locations and determine the influence relationship of candidate locations on fault current distribution and electrical coupling between regions. The influence relationship provides a quantitative analysis basis for subsequent optimization algorithms to select location combinations. The optimization and screening module is used to select a combination of positions that meet preset constraints from the candidate position set using an optimization algorithm, thereby forming a primary fault current limiter arrangement scheme. The transient simulation verification module is used to simulate the transient behavior of the network under the operating conditions and fault conditions corresponding to the scenario set, and adjust the primary layout scheme according to the simulation results to obtain a set of feasible layout schemes. The set of feasible layout schemes provides a basis for candidate schemes for subsequent protection zone division, regional boundary verification and final site selection. The protection zone verification module is used to verify the division of protection zones and the boundaries of the zones based on the changes in electrical quantities caused by the setting of the fault current limiter, and to determine the final fault current limiter location scheme based on the verification results.

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