Grounding distance protection setting method, system, medium and product suitable for new energy

Abstract

The application discloses a new energy applicable grounding distance protection setting method, system, medium and product, belongs to the grounding protection setting field, and the method is: constructing equivalent models of a plurality of new energies accessed to a target power grid respectively: in a positive sequence network, equivalent to a constant current source, in a negative sequence network, equivalent to a circuit breaker, a constant current source or a constant impedance according to a control strategy, and in a zero sequence network, equivalent to a circuit breaker; a synchronous power source is equivalent to a voltage source branch with a grounding impedance in the positive sequence network, a constant impedance in the negative sequence, and a circuit breaker in the zero sequence. Combining line parameters to construct each sequence power grid system model and generate a node impedance matrix, extracting three types of parameters according to to-be-set protections, cooperating protections, fault points and new energy access positions, and calculating positive, negative and zero sequence auxiliary increase coefficients under each fault type, the minimum value is taken to calculate a grounding distance protection setting value. Through implementation of the application, the problem that the applicability of the grounding distance protection setting value after the new energy is accessed in the prior art is not clear can be solved.

Description

Technical Field

[0001] This invention belongs to the field of grounding protection setting, and relates to a grounding distance protection setting method, system, medium and product applicable to new energy. Background Technology

[0002] In AC power grids containing a high proportion of new energy sources such as wind and solar power, when a single-phase or two-phase-to-ground short-circuit fault occurs on a line, grounding distance protection is required to quickly isolate the fault area and ensure the safe and stable operation of the system. The setting value of this protection must accurately reflect the grid topology and power source characteristics to ensure reliable operation under various operating conditions.

[0003] Existing technologies typically construct positive-sequence, negative-sequence, and zero-sequence network models based on traditional synchronous power sources, and select auxiliary coefficients for setting calculations based on these models. However, when a large number of new energy sources are connected to the power grid, their fault electrical characteristics differ significantly from those of synchronous power sources, and the equivalent forms of new energy sources in each sequence network are inconsistent under different control strategies. Traditional setting methods cannot reflect the impact of new energy sources, which may lead to erroneous setting values ​​in actual operation, making it difficult to guarantee applicability. Summary of the Invention

[0004] This application provides a grounding distance protection setting method, system, medium, and product applicable to new energy sources, which can solve the problem of unclear applicability of grounding distance protection setting values ​​after new energy sources are connected in the prior art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a grounding distance protection setting method applicable to new energy sources, comprising: Based on multiple new energy sources connected to the target AC power grid, equivalent models for each new energy source are constructed. Based on these equivalent models, synchronous power sources, and line parameters, power grid system models for each sequence network are constructed. The equivalent models for each new energy source include: in the positive sequence network, they are equivalent to a constant current source; in the negative sequence network, they are equivalent to an open circuit, a constant current source, or a constant impedance source depending on the control strategy type; and in the zero sequence network, they are equivalent to an open circuit. The synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, a constant impedance source in the negative sequence network, and an open circuit in the zero sequence network. Based on the power grid system model of each sequence, the corresponding node impedance matrix is ​​generated, and according to the protection to be set, the coordinated protection, the fault point and the access location of the new energy, the first parameter, the second parameter and the third parameter are extracted from the node impedance matrix, the equivalent model of the new energy and the line parameters respectively. Based on the first, second, and third parameters, the positive-sequence amplification coefficient, negative-sequence amplification coefficient, and zero-sequence amplification coefficient corresponding to each fault type are calculated respectively. The smallest amplification coefficient is then selected to calculate the grounding distance protection setting value of the protection to be set.

[0006] Compared with the prior art, the embodiments of this application have the following beneficial effects: Equivalent models of new energy sources are constructed for each of the multiple new energy sources connected to the target AC grid, and the differentiated electrical responses of different new energy sources under fault conditions are characterized; in the positive sequence network, new energy sources are equivalent to constant current sources; in the negative sequence network, they are equivalent to circuit breakers / constant current sources / constant impedance sources according to the control strategy type; and in the zero sequence network, they are equivalent to circuit breakers. Simultaneously, the synchronous power source is adopted in an equivalent form that conforms to its physical characteristics in each sequence network, so that the constructed grid system model of each sequence network truly reflects the fault sequence component characteristics of the grid containing new energy sources; at the same time, corresponding node impedance matrices are generated based on the grid system model of each sequence, and the first parameter is extracted from this matrix, the equivalent model of the new energy source, and the line parameters. The system utilizes a number of parameters, a second parameter, and a third parameter to achieve structured acquisition of multi-source heterogeneous data required for setting calculations. Furthermore, by calculating the positive-sequence, negative-sequence, and zero-sequence amplification coefficients for each fault type based on these three types of parameters, it comprehensively covers various grounding fault conditions that may occur after the integration of new energy sources. Then, by selecting the minimum value among all calculated amplification coefficients and using it to calculate the grounding distance protection setting value, it ensures that the protection can reliably operate without malfunctioning even under the most severe amplification effect. The synergistic effect of these features means that the setting method no longer relies on a unified simplified assumption for new energy sources. Instead, through a complete technical chain of sequence modeling, multi-source parameter fusion, and selection of the most unfavorable operating conditions, it fundamentally solves the technical problem of unclear applicability of grounding distance protection setting values ​​after the integration of new energy sources.

[0007] In some embodiments of the first aspect of this application, the construction of the power grid system model for each sequence network based on the equivalent models of each new energy source, synchronous power source, and line parameters includes: In each sequence network, an initial power grid system model is constructed based on synchronous power sources and line parameters, and the initial node impedance matrix corresponding to each initial power grid system model is calculated. Based on the initial node impedance matrix corresponding to the positive sequence network, and the output current of each new energy source in the positive sequence network equivalent constant current source, the influence factor of each new energy source on the fault point in the initial power grid system model is calculated, and the first few new energy sources with the influence factors sorted from largest to smallest are selected. The equivalent branches of several selected new energy sources are embedded into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

[0008] Compared with existing technologies, the above embodiments have the following advantages: By constructing an initial power grid system model based solely on synchronous power sources and line parameters in each sequence network and calculating the corresponding initial node impedance matrix, a baseline network state without new energy interference is established; further, based on the initial node impedance matrix under positive sequence and the equivalent constant current source output current of each new energy source in the positive sequence network, the influence factor of each new energy source on the fault point is calculated, quantifying the local influence of a single new energy source in a specific sequence network; simultaneously, by sorting and selecting several new energy sources according to the size of the influence factor, the key new energy sources that play a dominant role in protection setting are effectively focused on, avoiding computational redundancy caused by including a large number of low-impact new energy sources in the model; and then, by embedding the equivalent branches of the selected new energy sources into the initial power grid system model of each sequence network to form the final model, the refined correction of each sequence network model is realized, thereby improving the model's representation accuracy of actual power grid fault characteristics while ensuring computational efficiency.

[0009] In some embodiments of the first aspect of this application, the calculation of the influence factor of each new energy source on the fault point in the initial power grid system model based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each new energy source equivalent constant current source in the positive sequence network includes: Based on the initial node impedance matrix corresponding to the positive sequence network, the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point are extracted. Combined with the magnitude of the equivalent constant current source output current of the new energy in the positive sequence network, the influence factor of each new energy in each sequence network is calculated.

[0010] Compared with existing technologies, the above embodiments have the following beneficial effects: Based on the positive sequence network, the mutual impedance between the new energy access node and the fault point and the self-impedance of the fault point are extracted from the initial node impedance matrix, thus obtaining the electrical coupling relationship between the new energy and the fault point; further, the influence factor is calculated by combining the output current of the equivalent constant current source of the new energy in the positive sequence network, so that the calculation of the influence factor is directly related to the actual fault injection capability of the new energy in the sequence network; the method uses the positive sequence network with a relatively unified equivalent model as the benchmark for screening, ensuring that the influence factor of the new energy in the network has the same calculation standard for different control strategies, reducing the amount of calculation while avoiding the screening differences caused by different evaluation systems under different sequence networks.

[0011] In some embodiments of the first aspect of this application, the step of extracting the first parameter, the second parameter, and the third parameter from the impedance matrix of each node, the equivalent model of the new energy source, and the line parameters according to the protection to be set, the coordinated protection, the fault point, and the location of the new energy source access includes: The first parameter is extracted from the impedance matrix of each node; wherein the first parameter includes: the positive-sequence self-impedance, negative-sequence self-impedance and zero-sequence self-impedance of the fault point, the positive-sequence mutual impedance and negative-sequence mutual impedance between the new energy access node and the fault point, the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the protection to be set is located and the fault point, and the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the coordination protection is located and the fault point. The second parameter is extracted from the equivalent model of each selected new energy source; wherein the second parameter includes: the positive sequence output current of each new energy source, and the negative sequence output current or negative sequence equivalent impedance of each new energy source. A third parameter is extracted from the line parameters corresponding to the line where the protection to be set is located and the line where the cooperating protection is located; wherein, the third parameter includes: the positive sequence impedance and zero sequence impedance of the line where the protection to be set is located, and the positive sequence impedance and zero sequence impedance of the line where the cooperating protection is located.

[0012] Compared with existing technologies, the above embodiments have the following beneficial effects: By extracting a complete first parameter set from the impedance matrix of each node, including the fault point self-impedance, the mutual impedance between new energy sources and fault points, and the mutual impedance between protection and fault points, comprehensive grid topology impedance information is provided for the calculation of the boosting coefficient; furthermore, the positive-sequence output current and negative-sequence output current or negative-sequence equivalent impedance of the selected new energy equivalent model are extracted as the second parameter, accurately characterizing the fault current injection characteristics of key new energy sources in different sequence networks; at the same time, by extracting the positive-sequence and zero-sequence impedances of the lines where the protection to be set and the coordinated protection are located as the third parameter, the constraints of the physical characteristics of the lines themselves are incorporated; the structured extraction of the three types of parameters jointly ensures the integrity and accuracy of the input data for the subsequent boosting coefficient calculation, laying the foundation for the reliability of the setting value.

[0013] In some embodiments of the first aspect of this application, the step of calculating the positive-sequence amplification coefficient, negative-sequence amplification coefficient, and zero-sequence amplification coefficient corresponding to each fault type based on the first parameter, the second parameter, and the third parameter includes: Substituting the first, second, and third parameters into the expressions for the positive, negative, and zero sequence amplification coefficients under a single-phase-to-ground short-circuit fault, the positive, negative, and zero sequence amplification coefficients under a single-phase-to-ground short-circuit fault are calculated. Substituting the first, second, and third parameters into the expressions for the positive, negative, and zero-sequence amplification coefficients under a two-phase-to-ground short-circuit fault, the positive, negative, and zero-sequence amplification coefficients under a two-phase-to-ground short-circuit fault are calculated.

[0014] Compared with existing technologies, the above embodiments have the following beneficial effects: by substituting the first, second, and third parameters into the calculation logic of the positive, negative, and zero sequence amplification coefficients under a single-phase ground fault, a complete three-sequence amplification coefficient for this fault type is generated; furthermore, by calculating the three-sequence amplification coefficient under a two-phase ground fault in the same way, the most typical two types of asymmetrical ground fault scenarios that ground distance protection should deal with are covered; the amplification coefficient calculation mechanism of this fault type and sequence network ensures that the setting method can adapt to the dynamic changes of the amplification effect under different fault modes after the access of new energy sources, and avoids the setting deviation caused by a single fault assumption.

[0015] Secondly, the present invention also provides a grounding distance protection setting system applicable to new energy sources, comprising: a model building module, a parameter extraction module, and a solution module; The model building module is used to construct equivalent models for multiple new energy sources connected to the target AC power grid, and to construct power grid system models for each sequence network based on the equivalent models of each new energy source, synchronous power sources, and line parameters. The equivalent models of the new energy sources include: equivalent to a constant current source in the positive sequence network; equivalent to an open circuit, constant current source, or constant impedance source in the negative sequence network depending on the control strategy type; and equivalent to an open circuit in the zero sequence network. The synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, equivalent to constant impedance in the negative sequence network, and equivalent to an open circuit in the zero sequence network. The parameter extraction module is used to generate corresponding node impedance matrices based on the power grid system model of each sequence, and extract the first parameter, the second parameter, and the third parameter from the node impedance matrices, the equivalent model of the new energy source, and the line parameters respectively according to the protection to be set, the coordinated protection, the fault point, and the access location of the new energy source. The solution module is used to calculate the positive sequence amplification coefficient, negative sequence amplification coefficient, and zero sequence amplification coefficient corresponding to each fault type based on the first parameter, the second parameter, and the third parameter, and to select the smallest amplification coefficient to calculate the ground distance protection setting value of the protection to be set.

[0016] Compared with the prior art, the above embodiments of this application have the following beneficial effects: Equivalent models of new energy sources are constructed for each of the multiple new energy sources connected to the target AC power grid, and the differentiated electrical responses of different new energy sources under fault conditions are characterized; in the positive sequence network, new energy sources are equivalent to constant current sources; in the negative sequence network, they are equivalent to circuit breakers / constant current sources / constant impedance sources according to the control strategy type; and in the zero sequence network, they are equivalent to circuit breakers. Simultaneously, the synchronous power source is adopted in an equivalent form that conforms to its physical characteristics in each sequence network, so that the constructed power grid system model of each sequence network truly reflects the fault sequence component characteristics of the power grid containing new energy sources; at the same time, corresponding node impedance matrices are generated based on each sequence power grid system model, and the first impedance is extracted from this matrix, the equivalent model of the new energy source, and the line parameters. The first, second, and third parameters enable the structured acquisition of multi-source heterogeneous data required for setting calculations. Furthermore, by calculating the positive-sequence, negative-sequence, and zero-sequence amplification coefficients for each fault type based on these three types of parameters, comprehensive coverage of various grounding fault conditions that may occur after new energy access is achieved. Then, by selecting the minimum value among all calculated amplification coefficients and using it to calculate the grounding distance protection setting value, reliable and erroneous protection is ensured even under the most severe amplification effect. The synergistic effect of these features means that the setting method no longer relies on a unified simplified assumption for new energy, but fundamentally solves the technical problem of unclear applicability of grounding distance protection setting values ​​after new energy access through a complete technical chain of sequence modeling, multi-source parameter fusion, and selection of the most unfavorable operating conditions.

[0017] In some embodiments of the second aspect of this application, the model building module includes: a matrix calculation unit, a filtering unit, and an embedding unit; The matrix calculation unit is used to construct an initial power grid system model based on synchronous power sources and line parameters in each sequence network, and to calculate the initial node impedance matrix corresponding to each initial power grid system model. The filtering unit is used to calculate the influence factor of each new energy source on the fault point in the initial power grid system model based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each new energy source equivalent constant current source in the positive sequence network, and to filter out the new energy sources with the influence factors sorted from largest to smallest. The embedding unit is used to embed the equivalent branches of several selected new energy sources into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

[0018] Compared with existing technologies, the above embodiments have the following advantages: By constructing an initial power grid system model based solely on synchronous power sources and line parameters in each sequence network and calculating the corresponding initial node impedance matrix, a baseline network state without new energy interference is established; further, based on the initial node impedance matrix under positive sequence and the equivalent constant current source output current of each new energy source in the positive sequence network, the influence factor of each new energy source on the fault point is calculated, quantifying the local influence of a single new energy source in a specific sequence network; simultaneously, by sorting and selecting several new energy sources according to the size of the influence factor, the key new energy sources that play a dominant role in protection setting are effectively focused on, avoiding computational redundancy caused by including a large number of low-impact new energy sources in the model; and then, by embedding the equivalent branches of the selected new energy sources into the initial power grid system model of each sequence network to form the final model, the refined correction of each sequence network model is realized, thereby improving the model's representation accuracy of actual power grid fault characteristics while ensuring computational efficiency.

[0019] In some embodiments of the second aspect of this application, the screening unit includes: a factor calculation subunit; The factor calculation subunit is used to extract the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point in the positive sequence network based on the initial node impedance matrix corresponding to the positive sequence network, and calculate the influence factor of each new energy in each sequence network by combining the equivalent constant current source output current of the new energy in the positive sequence network.

[0020] Compared with existing technologies, the above embodiments have the following beneficial effects: Based on the positive sequence network, the mutual impedance between the new energy access node and the fault point and the self-impedance of the fault point are extracted from the initial node impedance matrix, thus obtaining the electrical coupling relationship between the new energy and the fault point; further, the influence factor is calculated by combining the output current of the equivalent constant current source of the new energy in the positive sequence network, so that the calculation of the influence factor is directly related to the actual fault injection capability of the new energy in the sequence network; the method uses the positive sequence network with a relatively unified equivalent model as the benchmark for screening, ensuring that the influence factor of the new energy in the network has the same calculation standard for different control strategies, reducing the amount of calculation while avoiding the screening differences caused by different evaluation systems under different sequence networks.

[0021] Thirdly, the present invention also provides a computer program product, including a computer program or instructions, characterized in that, when the computer program or instructions are executed, they implement any one of the grounding distance protection setting methods applicable to new energy sources according to the present invention.

[0022] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, implements any of the grounding distance protection setting methods applicable to new energy sources according to the present invention. Attached Figure Description

[0023] Figure 1 This is a flowchart illustrating a grounding distance protection setting method applicable to new energy sources, provided in some embodiments of the present invention.

[0024] Figure 2 This is a schematic diagram of a grounding distance protection setting system applicable to new energy sources, provided in some embodiments of the present invention. Detailed Implementation

[0025] The technical solutions of 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.

[0026] Example 1: Please refer to Figure 1 To address the problem of unclear applicability of grounding distance protection setting values ​​after new energy access in existing technologies, an embodiment of the present invention provides a grounding distance protection setting method applicable to new energy, comprising steps S1 to S3: Step S1: Based on the multiple new energy sources connected to the target AC power grid, construct equivalent models for each new energy source, and based on the equivalent models of each new energy source, synchronous power sources, and line parameters, construct power grid system models for each sequence network; wherein, the equivalent model of the new energy source includes: equivalent to a constant current source in the positive sequence network, equivalent to an open circuit, constant current source, or constant impedance in the negative sequence network according to the control strategy type, and equivalent to an open circuit in the zero sequence network; the synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, equivalent to constant impedance in the negative sequence network, and equivalent to an open circuit in the zero sequence network.

[0027] Furthermore, the power grid system model for constructing each sequence network can be implemented through the following preferred embodiments, including steps S11-S13, as follows: S11: In each sequence network, construct an initial power grid system model based on synchronous power sources and line parameters, and calculate the initial node impedance matrix corresponding to each initial power grid system model; S12: Based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each new energy source in the positive sequence network equivalent constant current source, calculate the influence factor of each new energy source on the fault point in the initial power grid system model, and select the new energy sources with the influence factors sorted from largest to smallest. S13: Embed the equivalent branches of several selected new energy sources into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

[0028] In this preferred embodiment, an initial power grid system model is constructed based solely on synchronous power sources and line parameters in each sequence network, and the corresponding initial node impedance matrix is ​​calculated to establish a baseline network state free from new energy interference. Furthermore, based on the initial node impedance matrix in the positive sequence and the equivalent constant current source output current of each new energy source in the positive sequence network, the influence factor of each new energy source on the fault point is calculated, quantifying the local influence of a single new energy source in a specific sequence network. Simultaneously, by sorting and selecting several new energy sources according to the magnitude of their influence factors, key new energy sources that play a dominant role in protection setting are effectively focused on, avoiding computational redundancy caused by including a large number of low-impact new energy sources in the model. Finally, by embedding the equivalent branches of the selected new energy sources into the initial power grid system model of each sequence network to form the final model, the refined correction of each sequence network model is achieved, thereby improving the model's representation accuracy of actual power grid fault characteristics while ensuring computational efficiency.

[0029] Furthermore, in step S12, the influence factor can be calculated through the following preferred implementation method, including step S121, as follows: S121: Based on the initial node impedance matrix corresponding to the positive sequence network, extract the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point in the positive sequence network, and calculate the influence factor of each new energy in each sequence network by combining the equivalent constant current source output current of the new energy in the positive sequence network.

[0030] In this preferred embodiment, using the positive sequence network as a benchmark, the mutual impedance between the new energy access node and the fault point and the self-impedance of the fault point are extracted from the initial node impedance matrix to obtain the electrical coupling relationship between the new energy and the fault point. Furthermore, the influence factor is calculated by combining the output current of the equivalent constant current source of the new energy in the positive sequence network, so that the calculation of the influence factor is directly related to the actual fault injection capability of the new energy in the sequence network. This method uses the positive sequence network with a relatively uniform equivalent model as a benchmark for screening, ensuring that the influence factor of the new energy in the network has the same calculation standard for different control strategies, reducing the amount of calculation while avoiding the screening differences caused by different evaluation systems under different sequence networks.

[0031] Step S2: Generate the corresponding node impedance matrix based on the power grid system model of each sequence, and extract the first parameter, second parameter and third parameter from the node impedance matrix, the equivalent model of the new energy and the line parameters according to the protection to be set, the coordinated protection, the fault point and the access location of the new energy.

[0032] Furthermore, step S2 can be implemented through the following preferred embodiments, including steps S21-S23, as follows: S21: Extract the first parameter from the impedance matrix of each node; wherein the first parameter includes: the positive-sequence self-impedance, negative-sequence self-impedance and zero-sequence self-impedance of the fault point, the positive-sequence mutual impedance and negative-sequence mutual impedance between the new energy access node and the fault point, the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the protection to be set is located and the fault point, and the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the coordination protection is located and the fault point. S22: Extract the second parameter from the equivalent model of each new energy source obtained by screening; wherein, the second parameter includes: the positive sequence output current of each new energy source, and the negative sequence output current or negative sequence equivalent impedance of each new energy source. S23: Extract the third parameter from the line parameters corresponding to the line where the protection to be set is located and the line where the cooperating protection is located; wherein, the third parameter includes: the positive sequence impedance and zero sequence impedance of the line where the protection to be set is located, and the positive sequence impedance and zero sequence impedance of the line where the cooperating protection is located.

[0033] In this preferred embodiment, a complete first parameter set, including fault point self-impedance, new energy-fault point mutual impedance, and protection-fault point mutual impedance, is extracted from the impedance matrix of each node, providing comprehensive grid topology impedance information for the calculation of the boosting coefficient. Furthermore, the positive-sequence output current and negative-sequence output current or negative-sequence equivalent impedance of the selected new energy equivalent model are extracted as the second parameter, accurately characterizing the fault current injection characteristics of key new energy sources in different sequence networks. Simultaneously, the positive-sequence and zero-sequence impedances of the lines where the protection to be set and the cooperating protection are located are extracted as the third parameter, incorporating the constraints of the line's own physical characteristics. The structured extraction of these three types of parameters jointly ensures the integrity and accuracy of the input data for the subsequent boosting coefficient calculation, laying the foundation for the reliability of the setting value.

[0034] Step S3: Based on the first parameter, the second parameter, and the third parameter, calculate the positive sequence amplification coefficient, the negative sequence amplification coefficient, and the zero sequence amplification coefficient for each fault type, and select the smallest amplification coefficient to calculate the ground distance protection setting value of the protection to be set.

[0035] Furthermore, in step S3, the calculation of each coefficient can be implemented through the following preferred embodiments, including steps S31-S32, as follows: S31: Substitute the first parameter, the second parameter, and the third parameter into the expressions for the positive sequence, negative sequence, and zero sequence boosting coefficients corresponding to a single-phase-to-ground short-circuit fault to calculate the positive sequence boosting coefficient, negative sequence boosting coefficient, and zero sequence boosting coefficient corresponding to a single-phase-to-ground short-circuit fault. S32: Substitute the first, second, and third parameters into the expressions for the positive, negative, and zero sequence boosting coefficients corresponding to the two-phase-to-ground short-circuit fault to calculate the positive, negative, and zero sequence boosting coefficients corresponding to the two-phase-to-ground short-circuit fault.

[0036] In this preferred embodiment, by substituting the first, second, and third parameters into the calculation logic of the positive, negative, and zero-sequence amplification coefficients corresponding to a single-phase ground fault, a complete three-sequence amplification coefficient for this fault type is generated. Furthermore, the three-sequence amplification coefficient for a two-phase ground fault is calculated in the same way, covering the two most typical asymmetrical ground fault scenarios that ground distance protection should deal with. This amplification coefficient calculation mechanism based on fault type and sequence network ensures that the setting method can adapt to the dynamic changes in the amplification effect under different fault modes after the access of new energy sources, and avoids setting deviations caused by a single fault assumption.

[0037] In practical implementation, within the power grid, "new energy" refers to a clean and renewable energy system that replaces traditional fossil fuels in the power system through technological advancements and energy structure transformation. This mainly includes solar, wind, and hydropower. The term "new energy" simplifies the representation of all equipment connected to the grid, including but not limited to converters, wind turbines, photovoltaic power generation equipment, reactive power regulation equipment, and auxiliary equipment. "Traditional power" simplifies the representation of power facilities including main transformers, switchgear, distribution panels, and automation control systems, as well as the supporting structures required for these facilities. Traditional power plants convert energy sources such as coal into electricity, involving numerous, large-scale, and complex wiring systems, with high safety and stringent environmental requirements. In the combined operation modes of AC power grid substations, it is equivalent to a grounded branch with resistance, i.e., a grounded branch with the series impedance of the power source.

[0038] In this application, grounding distance protection is mainly used to deal with single-phase grounding faults and two-phase grounding faults that occur on the line, referred to as grounding faults. In AC power grids, setting calculations need to be based on short-circuit calculations to obtain parameters. The short-circuit calculation of grounding faults usually adopts the asymmetrical component method, which decomposes the asymmetrical fault component after a grounding fault occurs into three symmetrical components: positive sequence, negative sequence, and zero sequence, for calculation.

[0039] Specifically, in the positive sequence network, traditional power sources (i.e., synchronous power sources) are equivalent to impedance-grounded branches, and new energy sources are equivalent to constant current sources; in the negative sequence network, traditional power sources are equivalent to constant impedance, and new energy sources are equivalent to constant impedance, constant current sources, or open circuits depending on the control strategy type; in the zero sequence network, both traditional power sources and new energy sources are equivalent to open circuits, in order to construct the power grid system model under each sequence network.

[0040] In steps S1-S2 above, when obtaining the node impedance matrix of the power grid system model, the process is elaborated as follows: 1. Establish an equivalent system model and record the equivalent output current of the new energy source, the node number of the new energy source, and the node number corresponding to the fault location during the protection setting calculation process; 2. Considering only synchronous power supply access, construct the correlation matrix and branch impedance matrix based on the connection relationships of each branch and node in the power grid system model.

[0041] 3. Based on the correlation matrix and the branch impedance matrix, calculate the first node impedance matrix (i.e., the initial node impedance matrix in step S11). IV. Based on the impedance matrix of the first node and combined with the parameters of the new energy source, select the new energy sources in the AC power grid that have a greater impact on the protection to be set. V. Based on the new energy model, modify the first node impedance matrix to generate the second node impedance matrix of each sequence network (i.e., the node impedance matrix in step S2).

[0042] In power grid systems, the node impedance matrix is ​​an important tool for analyzing current and voltage relationships. The elements of the node impedance matrix represent the impedance between any two nodes in the power grid system. First, an correlation matrix is ​​constructed based on the connection relationships between branches and nodes in the power grid system model to describe the connections between branches and nodes. If branch k is connected to node i, then... The specific value depends on the direction of the branch and the node numbering rules; if they are not connected, then Then, based on the correlation matrix, the branch impedance matrix is ​​calculated. The branch impedance matrix is ​​a diagonal matrix, and the elements on the diagonal are the impedance values ​​of each branch. If there are n branches in the power grid system, then the branch impedance matrix is ​​an n×n diagonal matrix.

[0043] Finally, based on the correlation matrix and branch impedance matrix, the node impedance matrix is ​​calculated using the following formula: Where A represents the correlation matrix and B represents the branch impedance matrix. This represents the transpose of the correlation matrix A.

[0044] Based on the impedance matrix of the first node and the parameters of the new energy source, new energy sources with a significant impact on protection are selected. In AC power grids, due to the distributed access of new energy sources and their smaller power capacity compared to traditional power sources, only new energy sources with a significant impact on protection are typically considered in setting calculations. The impact of new energy sources on protection is evaluated through relevant parameters. First, in the positive-sequence network, the impact factors of new energy sources on protection are constructed: Where j represents the new energy access node, This represents the positive-sequence mutual impedance between the fault point and the new energy node in the first-node impedance matrix. This represents the positive-sequence self-impedance at the fault point in the first-node impedance matrix. This represents the output current of the new energy source in the positive sequence network, and is usually taken as the maximum value.

[0045] Next, based on the magnitude of the influence factor, relevant thresholds are set to select new energy sources with a significant impact on the fault point. Then, in the positive-sequence and zero-sequence networks, the impedance matrix of the second node considering the influence of new energy sources is considered to be the same as the impedance matrix of the first node. In the negative-sequence network, the control strategy types of the selected new energy sources are further analyzed. If they are not included in the new energy sources that are equivalent to constant impedance in the negative-sequence network, then the impedance matrix of the second node considering the influence of new energy sources is the same as the impedance matrix of the first node; otherwise, based on the negative-sequence equivalent impedance of new energy sources, the parameters in the impedance matrix of the first node are modified sequentially, as follows: Where i and j represent any node in the network, , , This represents the mutual impedance between the renewable energy node and any two arbitrary nodes, as well as the self-impedance of the renewable energy grid-connected node, in the first node impedance matrix of the negative order. This represents the negative-sequence equivalent impedance of new energy sources.

[0046] The second node impedance matrix includes at least the fault node, the new energy node, the node where the protection to be set and the coordinated protection are located.

[0047] Next, based on the impedance matrix of the second node in the positive sequence, negative sequence, and zero sequence networks, and in combination with the protection to be set, the coordinated protection, the fault point, and the location of the new energy access, the first, second, and third parameters required for the setting calculation are determined.

[0048] The first parameter includes the positive-sequence self-impedance, negative-sequence self-impedance, and zero-sequence self-impedance of the node where the fault is located; the positive-sequence mutual impedance and negative-sequence mutual impedance between the new energy access node and the fault node; and the positive-sequence mutual impedance, negative-sequence mutual impedance, and zero-sequence mutual impedance between the node where the protection to be set and the coordinated protection are located and the fault point. The second parameter includes the positive sequence output current of the new energy source, which is usually taken as the maximum value of the possible output current of the new energy source; the negative sequence equivalent impedance of the new energy source, or the negative sequence output current of the new energy source. The third parameter includes the positive sequence impedance and zero sequence impedance of the line where the protection to be set is located; and the positive sequence impedance and zero sequence impedance of the line where the coordination protection is located.

[0049] In AC power grids, grounding distance protection serves as backup protection for lines in response to grounding faults, typically employing a three-stage protection principle. Stages II and III of the protection are collectively referred to as the delay period, and their settings require coordination with adjacent lines. In traditional power grids, the setting approach for stage II of grounding distance protection is as follows: First, select the fault point as the end of the line and calculate the measuring impedance of the protection to be set when a single-phase ground fault occurs at that location. The protection setting should be set to be less than this measuring impedance. ; Then, calculate the measuring impedance of the protection to be set when a two-phase ground fault occurs at that location, and set the protection setting to be less than this measuring impedance: ; In this case, considering that the faults are A-phase ground fault and AB-phase ground fault respectively, the setting is carried out using the measuring element that measures the voltage and current of A-phase as an example. Indicates protection The fixed value of the grounding distance in section II; and These represent the phase A voltage and phase A current of the line where the protection is located at the point to be set during a phase-to-phase short circuit, respectively. Represents the reliability coefficient; The zero-sequence current of the protected line is represented by ; k represents the zero-sequence compensation coefficient; the superscripts (1) and (1,1) indicate that the fault type is a single-phase ground fault and a two-phase ground fault, respectively, and the subsequent variables are also labeled according to the same rules. Finally, the smaller of the two equations is selected as the final setting value.

[0050] The calculations using the above approach require consideration of phase voltage and line current under different fault conditions, making the calculations quite complex. This can be simplified through derivation. First, the two equations above are equivalent. Here, removing the superscripts (1) and (1,1) indicates that the same transformation can be performed under both fault types: ; In the formula: The voltage drop of phase A of the line where the protection to be set is located; To match the phase A voltage at the protection point; , , These are the phase current of phase A, the zero-sequence current, and the zero-sequence compensation coefficient flowing through the coordinated protection system, respectively. Considering that the positive and negative sequence impedances of the line are equal, we can... and The ratio is simplified to the positive sequence impedance of the line where the protection to be set is located. Furthermore, as the protection principle states, when a fault occurs at the end of the line where the protection is located, and The ratio is equivalent to protection The fixed value of grounding distance segment I Based on this, the equation can be further equivalently represented as follows: ; Assuming that the zero-sequence compensation coefficients of the line where the protection to be set is located and the line where the coordinated protection is located are the same, this condition can usually be satisfied in AC power grids. Then the above formula can be rewritten in the following three forms.

[0051] Represented by the positive order boosting coefficient: ; Represented by negative order boosting coefficient: ; Represented by the zero-order boosting coefficient: ; Based on the above three setting forms, since the delay setting value of the ground distance protection needs to be the minimum value under different fault conditions, a certain simplification can be adopted in the setting calculation process by comparing the numerical values ​​of each sequence increment coefficient. The values ​​of the positive sequence increment coefficient, negative sequence increment coefficient, and zero sequence increment coefficient corresponding to the protection under different fault types are calculated. First, the expressions for each increment coefficient are derived, specifically: When a two-phase-to-ground short circuit occurs, the expression for the positive-sequence boosting coefficient is: ; When a two-phase-to-ground short circuit occurs, and a constant current source exists in the negative-sequence equivalent model of the new energy source, the expression for the negative-sequence boosting coefficient is: ; When a two-phase-to-ground short circuit occurs and there is no constant current source in the negative-sequence equivalent model of the new energy source, the expression for the negative-sequence boosting coefficient is: ; When a two-phase-to-ground short circuit occurs, the expression for the zero-sequence boosting coefficient is: ; When a single-phase-to-ground short circuit occurs, the expression for the positive sequence boosting factor is: ; When a single-phase-to-ground short circuit occurs, and a constant current source exists in the negative-sequence equivalent model of the new energy source, the expression for the negative-sequence boosting coefficient is: ; When a single-phase-to-ground short circuit occurs and there is no constant current source in the negative-sequence equivalent model of the new energy source, the expression for the negative-sequence boosting coefficient is: ; When a single-phase-to-ground short circuit occurs, the expression for the zero-sequence amplification factor is: ; In the formula, using Indicates the amplification factor. The node where the fault occurred. Indicates the grid connection node for new energy sources. Represents the set of new energy grid-connected nodes. Indicates the self-impedance at the fault point. , and These represent the mutual impedances between the node where the protection to be set is located, the node where the coordinated protection is located, the fault node, and the new energy grid connection point, respectively. This represents the injected current at the new energy grid connection node. and These represent the impedances of the line where the protection to be set is located and the line where the cooperating protection is located, respectively. In each formula, the superscript (1) and (1,1) indicate that the fault type is a single-phase ground fault and a two-phase ground fault, respectively. The subscripts 1, 2, and 0 indicate that the corresponding parameters are taken from the positive, negative, and zero-sequence networks, respectively.

[0052] Using the selected first, second, and third parameters, substitute them into the expressions for the amplification coefficients under different sequence networks and different fault types to calculate the specific values ​​of each amplification coefficient. Then, select the minimum value of the amplification coefficient under different sequence networks and different fault types, and construct the tuning calculation formula based on this.

[0053] When the amplification coefficients under different sequence networks and different fault types satisfy different magnitude relationships, the calculation formulas to be used for tuning calculations are shown in the table below: In the table, This refers to the setting value of the grounding distance protection stage II, which is to be adjusted. This generally refers to the first-stage setting value of grounding distance protection in conjunction with other protection measures.

[0054] In summary, compared with the prior art, the above embodiments of this application have the following beneficial effects: Equivalent models of new energy sources are constructed for each of the multiple new energy sources connected to the target AC power grid, and the differentiated electrical responses of different new energy sources under fault conditions are characterized; in the positive sequence network, new energy sources are equivalent to constant current sources; in the negative sequence network, they are equivalent to circuit breakers / constant current sources / constant impedance sources according to the control strategy type; and in the zero sequence network, they are equivalent to circuit breakers. Simultaneously, the synchronous power source is adopted in each sequence network with an equivalent form conforming to its physical characteristics, so that the constructed power grid system model of each sequence network truly reflects the fault sequence component characteristics of the power grid containing new energy sources; at the same time, corresponding node impedance matrices are generated based on each sequence power grid system model, and the corresponding impedance matrices are extracted from these matrices, the equivalent models of new energy sources, and the line parameters. The first, second, and third parameters enable the structured acquisition of multi-source heterogeneous data required for setting calculations. Furthermore, by calculating the positive-sequence, negative-sequence, and zero-sequence amplification coefficients for each fault type based on these three parameters, comprehensive coverage of various grounding fault conditions that may occur after new energy access is achieved. Then, by selecting the minimum value among all calculated amplification coefficients and using it to calculate the grounding distance protection setting value, reliable and erroneous protection is ensured even under the most severe amplification effect. The synergistic effect of these features means that the setting method no longer relies on a unified simplified assumption for new energy, but fundamentally solves the technical problem of unclear applicability of grounding distance protection setting values ​​after new energy access through a complete technical chain of sequence modeling, multi-source parameter fusion, and selection of the most unfavorable operating conditions.

[0055] Example 2: Please refer to Figure 2 Based on the same inventive concept, the present invention discloses a grounding distance protection setting system applicable to new energy sources, comprising: a model building module M1, a parameter extraction module M2, and a solution module M3; The model construction module M1 is used to construct equivalent models for each of the multiple new energy sources connected to the target AC power grid, and to construct power grid system models for each sequence network based on the equivalent models of each new energy source, the synchronous power source, and the line parameters. The equivalent models of the new energy sources include: equivalent to a constant current source in the positive sequence network, equivalent to an open circuit, a constant current source, or a constant impedance source in the negative sequence network depending on the control strategy type, and equivalent to an open circuit in the zero sequence network. The synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, equivalent to a constant impedance source in the negative sequence network, and equivalent to an open circuit in the zero sequence network.

[0056] Furthermore, the model building module M1 includes: a matrix calculation unit, a filtering unit, and an embedding unit; The matrix calculation unit is used to construct an initial power grid system model based on synchronous power sources and line parameters in each sequence network, and to calculate the initial node impedance matrix corresponding to each initial power grid system model. The filtering unit is used to calculate the influence factor of each new energy source on the fault point in the initial power grid system model based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each new energy source equivalent constant current source in the positive sequence network, and to filter out the new energy sources with the influence factors sorted from largest to smallest. The embedding unit is used to embed the equivalent branches of several selected new energy sources into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

[0057] In this preferred embodiment, an initial power grid system model is constructed based solely on synchronous power sources and line parameters in each sequence network, and the corresponding initial node impedance matrix is ​​calculated to establish a baseline network state free from new energy interference. Furthermore, based on the initial node impedance matrix in the positive sequence and the equivalent constant current source output current of each new energy source in the positive sequence network, the influence factor of each new energy source on the fault point is calculated, quantifying the local influence of a single new energy source in a specific sequence network. Simultaneously, by sorting and selecting several new energy sources according to the magnitude of their influence factors, key new energy sources that play a dominant role in protection setting are effectively focused on, avoiding computational redundancy caused by including a large number of low-impact new energy sources in the model. Finally, by embedding the equivalent branches of the selected new energy sources into the initial power grid system model of each sequence network to form the final model, the refined correction of each sequence network model is achieved, thereby improving the model's representation accuracy of actual power grid fault characteristics while ensuring computational efficiency.

[0058] Furthermore, the screening unit includes: a factor calculation subunit; The factor calculation subunit is used to extract the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point in the positive sequence network based on the initial node impedance matrix corresponding to the positive sequence network, and calculate the influence factor of each new energy in each sequence network by combining the equivalent constant current source output current of the new energy in the positive sequence network.

[0059] In this preferred embodiment, using the positive sequence network as a benchmark, the mutual impedance between the new energy access node and the fault point and the self-impedance of the fault point are extracted from the initial node impedance matrix to obtain the electrical coupling relationship between the new energy and the fault point. Furthermore, the influence factor is calculated by combining the output current of the equivalent constant current source of the new energy in the positive sequence network, so that the calculation of the influence factor is directly related to the actual fault injection capability of the new energy in the sequence network. This method uses the positive sequence network with a relatively uniform equivalent model as a benchmark for screening, ensuring that the influence factor of the new energy in the network has the same calculation standard for different control strategies, reducing the amount of calculation while avoiding the screening differences caused by different evaluation systems under different sequence networks.

[0060] The parameter extraction module M2 is used to generate corresponding node impedance matrices based on the power grid system model of each sequence, and extract the first parameter, the second parameter, and the third parameter from the node impedance matrices, the equivalent model of the new energy source, and the line parameters according to the protection to be set, the coordinated protection, the fault point, and the access location of the new energy source.

[0061] Furthermore, the parameter extraction module M2 includes: a first extraction unit, a second extraction unit, and a third extraction unit; The first extraction unit is used to extract a first parameter from the impedance matrix of each node; wherein the first parameter includes: the positive-sequence self-impedance, negative-sequence self-impedance and zero-sequence self-impedance of the fault point, the positive-sequence mutual impedance and negative-sequence mutual impedance between the new energy access node and the fault point, the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the protection to be set is located and the fault point, and the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the coordination protection is located and the fault point. The second extraction unit is used to extract a second parameter from the equivalent model of each new energy source obtained by screening; wherein, the second parameter includes: the positive sequence output current of each new energy source, and the negative sequence output current or negative sequence equivalent impedance of each new energy source. The third extraction unit is used to extract a third parameter from the line parameters corresponding to the line where the protection to be set is located and the line where the cooperating protection is located; wherein, the third parameter includes: the positive sequence impedance and zero sequence impedance of the line where the protection to be set is located, and the positive sequence impedance and zero sequence impedance of the line where the cooperating protection is located.

[0062] In this preferred embodiment, a complete first parameter set, including fault point self-impedance, new energy-fault point mutual impedance, and protection-fault point mutual impedance, is extracted from the impedance matrix of each node, providing comprehensive grid topology impedance information for the calculation of the boosting coefficient. Furthermore, the positive-sequence output current and negative-sequence output current or negative-sequence equivalent impedance of the selected new energy equivalent model are extracted as the second parameter, accurately characterizing the fault current injection characteristics of key new energy sources in different sequence networks. Simultaneously, the positive-sequence and zero-sequence impedances of the lines where the protection to be set and the cooperating protection are located are extracted as the third parameter, incorporating the constraints of the line's own physical characteristics. The structured extraction of these three types of parameters jointly ensures the integrity and accuracy of the input data for the subsequent boosting coefficient calculation, laying the foundation for the reliability of the setting value.

[0063] The solution module M3 is used to calculate the positive sequence amplification coefficient, negative sequence amplification coefficient and zero sequence amplification coefficient corresponding to each fault type based on the first parameter, the second parameter and the third parameter, and to select the smallest amplification coefficient to calculate the ground distance protection setting value of the protection to be set.

[0064] Furthermore, the solution module M3 includes: a first calculation unit and a second calculation unit; The first calculation unit is used to substitute the first parameter, the second parameter and the third parameter into the expressions for the positive sequence, negative sequence and zero sequence boosting coefficients corresponding to the single-phase ground short-circuit fault, and calculate the positive sequence boosting coefficient, negative sequence boosting coefficient and zero sequence boosting coefficient corresponding to the single-phase ground short-circuit fault. The second calculation unit is used to substitute the first parameter, the second parameter, and the third parameter into the expressions for the positive sequence, negative sequence, and zero sequence boosting coefficients corresponding to the two-phase-to-ground short-circuit fault, and to calculate the positive sequence boosting coefficient, negative sequence boosting coefficient, and zero sequence boosting coefficient corresponding to the two-phase-to-ground short-circuit fault.

[0065] In this preferred embodiment, by substituting the first, second, and third parameters into the calculation logic of the positive, negative, and zero-sequence amplification coefficients corresponding to a single-phase ground fault, a complete three-sequence amplification coefficient for this fault type is generated. Furthermore, the three-sequence amplification coefficient for a two-phase ground fault is calculated in the same way, covering the two most typical asymmetrical ground fault scenarios that ground distance protection should deal with. This amplification coefficient calculation mechanism based on fault type and sequence network ensures that the setting method can adapt to the dynamic changes in the amplification effect under different fault modes after the access of new energy sources, and avoids setting deviations caused by a single fault assumption.

[0066] In summary, compared with the prior art, the embodiments of this application have the following beneficial effects: Equivalent models of new energy sources are constructed for each of the multiple new energy sources connected to the target AC grid, and the differentiated electrical responses of different new energy sources under fault conditions are characterized; in the positive sequence network, new energy sources are equivalent to constant current sources; in the negative sequence network, they are equivalent to circuit breakers / constant current sources / constant impedance sources according to the control strategy type; and in the zero sequence network, they are equivalent to circuit breakers. Simultaneously, the synchronous power source is adopted in each sequence network with an equivalent form conforming to its physical characteristics, so that the constructed grid system model of each sequence network truly reflects the fault sequence component characteristics of the grid containing new energy sources; at the same time, the corresponding node impedance matrix is ​​generated based on the grid system model of each sequence, and the first node impedance is extracted from this matrix, the equivalent model of the new energy source, and the line parameters. The first, second, and third parameters enable the structured acquisition of multi-source heterogeneous data required for setting calculations. Furthermore, by calculating the positive-sequence, negative-sequence, and zero-sequence amplification coefficients for each fault type based on these three parameters, comprehensive coverage of various grounding fault conditions that may occur after new energy access is achieved. Then, by selecting the minimum value among all calculated amplification coefficients and using it to calculate the grounding distance protection setting value, reliable and erroneous protection is ensured even under the most severe amplification effects. The synergistic effect of these features means that the setting method no longer relies on a unified simplified assumption for new energy, but fundamentally solves the technical problem of unclear applicability of grounding distance protection setting values ​​after new energy access through a complete technical chain of sequence modeling, multi-source parameter fusion, and selection of the most unfavorable operating conditions.

[0067] Example 3: This invention also provides a computer program product, including a computer program or instructions, capable of running on a computing device or stored in any available medium. When the computer program product is run on at least one computing device, it causes the at least one computing device to execute any of the grounding distance protection setting methods applicable to new energy sources according to this invention.

[0068] Example 4: This invention also provides a computer-readable storage medium storing at least one executable instruction. When the executable instruction is run on a grounding distance protection setting system applicable to new energy sources, the system causes the system to perform one of the grounding distance protection setting methods applicable to new energy sources described in any of the above method embodiments.

[0069] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of this application may be practiced without these specific details. Similarly, for the purpose of simplification and aiding understanding of one or more aspects of the invention, in the above description of exemplary embodiments of this application, various features of the embodiments are sometimes grouped together in a single embodiment, figure, or description thereof. The claims, which follow the detailed description, are hereby expressly incorporated into that detailed description, wherein each claim itself is a separate embodiment of this application.

[0070] Those skilled in the art will understand that the modules in the system of the embodiments can be adaptively changed and placed in one or more systems different from that embodiment. Modules, units, or components in the embodiments can be combined into a single module, unit, or component, and further, they can be divided into multiple sub-modules, sub-units, or sub-components, except that at least some of such features and / or processes or units are mutually exclusive.

Claims

1. A grounding distance protection setting method applicable to new energy sources, characterized in that, include: Based on multiple new energy sources connected to the target AC power grid, equivalent models for each new energy source are constructed. Based on these equivalent models, synchronous power sources, and line parameters, power grid system models for each sequence network are constructed. The equivalent models for each new energy source include: in the positive sequence network, they are equivalent to a constant current source; in the negative sequence network, they are equivalent to an open circuit, a constant current source, or a constant impedance source depending on the control strategy type; and in the zero sequence network, they are equivalent to an open circuit. The synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, a constant impedance source in the negative sequence network, and an open circuit in the zero sequence network. Based on the power grid system model of each sequence, the corresponding node impedance matrix is ​​generated, and according to the protection to be set, the coordinated protection, the fault point and the access location of the new energy, the first parameter, the second parameter and the third parameter are extracted from the node impedance matrix, the equivalent model of the new energy and the line parameters respectively. Based on the first, second, and third parameters, the positive-sequence amplification coefficient, negative-sequence amplification coefficient, and zero-sequence amplification coefficient corresponding to each fault type are calculated respectively. The smallest amplification coefficient is then selected to calculate the grounding distance protection setting value of the protection to be set.

2. The grounding distance protection setting method applicable to new energy sources as described in claim 1, characterized in that, The construction of power grid system models for each sequence network based on the equivalent models of each new energy source, synchronous power sources, and line parameters includes: In each sequence network, an initial power grid system model is constructed based on synchronous power sources and line parameters, and the initial node impedance matrix corresponding to each initial power grid system model is calculated. Based on the initial node impedance matrix corresponding to the positive sequence network, and the output current of each new energy source in the positive sequence network equivalent constant current source, the influence factor of each new energy source on the fault point in the initial power grid system model is calculated, and the new energy sources with the largest influence factors are selected in descending order. The equivalent branches of several selected new energy sources are embedded into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

3. The grounding distance protection setting method applicable to new energy sources as described in claim 2, characterized in that, Based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each renewable energy source equivalent to a constant current source in the positive sequence network, the influence factor of each renewable energy source on the fault point in the initial power grid system model is calculated, including: Based on the initial node impedance matrix corresponding to the positive sequence network, the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point are extracted. Combined with the magnitude of the equivalent constant current source output current of the new energy in the positive sequence network, the influence factor of each new energy in each sequence network is calculated.

4. The grounding distance protection setting method applicable to new energy sources as described in claim 2, characterized in that, The step of extracting the first parameter, second parameter, and third parameter from the impedance matrix of each node, the equivalent model of the new energy source, and the line parameters based on the protection to be adjusted, the coordinated protection, the fault point, and the location of the new energy source connection includes: The first parameter is extracted from the impedance matrix of each node; wherein the first parameter includes: the positive-sequence self-impedance, negative-sequence self-impedance and zero-sequence self-impedance of the fault point, the positive-sequence mutual impedance and negative-sequence mutual impedance between the new energy access node and the fault point, the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the protection to be set is located and the fault point, and the positive-sequence mutual impedance, negative-sequence mutual impedance and zero-sequence mutual impedance between the node where the coordination protection is located and the fault point. The second parameter is extracted from the equivalent model of each selected new energy source; wherein the second parameter includes: the positive sequence output current of each new energy source, and the negative sequence output current or negative sequence equivalent impedance of each new energy source. A third parameter is extracted from the line parameters corresponding to the line where the protection to be set is located and the line where the cooperating protection is located; wherein, the third parameter includes: the positive sequence impedance and zero sequence impedance of the line where the protection to be set is located, and the positive sequence impedance and zero sequence impedance of the line where the cooperating protection is located.

5. The grounding distance protection setting method applicable to new energy sources as described in claim 1, characterized in that, The step of calculating the positive-sequence amplification coefficient, negative-sequence amplification coefficient, and zero-sequence amplification coefficient for each fault type based on the first parameter, the second parameter, and the third parameter includes: Substituting the first, second, and third parameters into the expressions for the positive, negative, and zero sequence amplification coefficients under a single-phase-to-ground short-circuit fault, the positive, negative, and zero sequence amplification coefficients under a single-phase-to-ground short-circuit fault are calculated. Substituting the first, second, and third parameters into the expressions for the positive, negative, and zero-sequence amplification coefficients under a two-phase-to-ground short-circuit fault, the positive, negative, and zero-sequence amplification coefficients under a two-phase-to-ground short-circuit fault are calculated.

6. A grounding distance protection setting system applicable to new energy sources, characterized in that, include: Model building module, parameter extraction module, and solution module; The model building module is used to construct equivalent models for multiple new energy sources connected to the target AC power grid, and to construct power grid system models for each sequence network based on the equivalent models of each new energy source, synchronous power sources, and line parameters. The equivalent models of the new energy sources include: equivalent to a constant current source in the positive sequence network; equivalent to an open circuit, constant current source, or constant impedance source in the negative sequence network depending on the control strategy type; and equivalent to an open circuit in the zero sequence network. The synchronous power source is equivalent to a voltage source branch with grounding impedance in the positive sequence network, equivalent to constant impedance in the negative sequence network, and equivalent to an open circuit in the zero sequence network. The parameter extraction module is used to generate corresponding node impedance matrices based on the power grid system model of each sequence, and extract the first parameter, the second parameter, and the third parameter from the node impedance matrices, the equivalent model of the new energy source, and the line parameters respectively according to the protection to be set, the coordinated protection, the fault point, and the access location of the new energy source. The solution module is used to calculate the positive sequence amplification coefficient, negative sequence amplification coefficient, and zero sequence amplification coefficient corresponding to each fault type based on the first parameter, the second parameter, and the third parameter, and to select the smallest amplification coefficient to calculate the ground distance protection setting value of the protection to be set.

7. A grounding distance protection setting system applicable to new energy sources as described in claim 6, characterized in that, The model building module includes: a matrix calculation unit, a filtering unit, and an embedding unit; The matrix calculation unit is used to construct an initial power grid system model based on synchronous power sources and line parameters in each sequence network, and to calculate the initial node impedance matrix corresponding to each initial power grid system model. The filtering unit is used to calculate the influence factor of each new energy source on the fault point in the initial power grid system model based on the initial node impedance matrix corresponding to the positive sequence network and the output current of each new energy source equivalent constant current source in the positive sequence network, and to filter out the new energy sources with the influence factors sorted from largest to smallest. The embedding unit is used to embed the equivalent branches of several selected new energy sources into the initial power grid system model to obtain the power grid system model corresponding to each sequence network.

8. The grounding distance protection setting system applicable to new energy sources as described in claim 7, characterized in that, The screening unit includes: a factor calculation subunit; The factor calculation subunit is used to extract the mutual impedance between each new energy access node and the fault point and the self-impedance of the fault point in the positive sequence network based on the initial node impedance matrix corresponding to the positive sequence network, and calculate the influence factor of each new energy in each sequence network by combining the equivalent constant current source output current of the new energy in the positive sequence network.

9. A computer program product, comprising a computer program or instructions, characterized in that, When the computer program or instructions are executed, they implement a grounding distance protection setting method applicable to new energy sources as described in any one of claims 1-5.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements a grounding distance protection setting method applicable to new energy sources as described in any one of claims 1-5.

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