A grid-connected protection method, device, and medium for distributed photovoltaic power generation.

Abstract

This invention relates to the field of relay protection technology. It discloses a grid-connected protection method, device, and medium for distributed photovoltaic (PV) systems, comprising: generating a transient phasor matrix of feeder nodes; constructing a topology map of fault current propagation based on the transient phasor matrix of feeder nodes, and extracting the phasor trajectory offset features of feeder nodes in the topology map to determine the initial faulty feeder node; using the initial faulty feeder node as a reference, tracing the topological propagation path of the node's transient phasor trajectory to reconstruct a feeder topology clustering structure for the fault area; based on the feeder topology clustering structure, analyzing the topological bifurcation and intersection features of the feeder node's transient phasor trajectory, formulating a differential tripping sequence for the protection device, and outputting a tripping command for the protection device according to this sequence. This invention is beneficial for improving the reliability and stability of relay protection in distribution networks under distributed PV access conditions.

Description

Technical Field

[0001] This invention relates to the field of relay protection technology, and more specifically, to a grid-connected protection method, device, and medium for distributed photovoltaic systems. Background Technology

[0002] With the rapid development of new energy sources, distributed photovoltaic (PV) power generation is gradually becoming an important part of the power grid. However, with the large-scale integration of PV power sources into the distribution network, the feeder network structure is becoming increasingly complex, with diverse current interaction characteristics between lines and prominent non-steady-state features, making it difficult for traditional relay protection technologies to fully adapt. Specifically, existing methods mostly rely on steady-state current characteristics, ignoring the topological relationships between node trajectories during the transient current propagation process, resulting in unclear fault line identification and even malfunctions or failures of protection devices.

[0003] Therefore, in response to the problems of complex feeder network topology, diverse fault current paths, and difficulty in capturing transient characteristics after the large-scale integration of distributed photovoltaics, it is urgent to develop a relay protection method that can fully consider the spatial topological association of feeder nodes, the transient change trajectory characteristics of node current phasors, and propagation paths, so as to improve the reliability and response speed of power grid protection devices under complex operating conditions and ensure the safe and stable operation of the distribution network. Summary of the Invention

[0004] To overcome the above-mentioned deficiencies of the prior art, embodiments of the present invention provide a grid-connected protection method, device, and medium for distributed photovoltaic systems.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A grid-connected protection method for distributed photovoltaic power generation includes:

[0007] Collect transient current data of the feeder and establish the feeder topology; perform phasor rotation processing on the transient current data based on the feeder topology to generate the transient phasor matrix of the feeder nodes;

[0008] A topology map of fault current propagation is constructed based on the transient phasor matrix of the feeder node, and the phasor trajectory offset features of the feeder node in the topology map are extracted to determine the initial fault feeder node.

[0009] Using the initial faulty feeder node as a reference, the topological propagation path of the node's transient phasor trajectory is traced to reconstruct the feeder topological clustering structure in the fault region.

[0010] Based on the feeder topology clustering structure, the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes are analyzed, the differential tripping sequence of protection devices is formulated, and the tripping command of protection devices is output according to the sequence.

[0011] An electronic device includes a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor executes the computer program to implement the method described in any of the preceding claims.

[0012] A computer-readable storage medium having a computer program stored thereon, wherein the computer program, when executed, implements the method described in any of the preceding claims.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] This invention obtains the transient phasor matrix of the feeder node under a unified reference phase by constructing a feeder node topology and adopting a phasor rotation processing method for node joint. This overcomes the shortcomings of traditional protection methods that ignore the spatial differences in the transient current trajectory of nodes, and realizes the effective aggregation and unified representation of the transient information of the feeder node, providing a reliable data foundation for the accurate determination of subsequent fault nodes.

[0015] Furthermore, by identifying the topological propagation path and spatial intersection characteristics of the phasor trajectories of feeder nodes, the initial faulty feeder node was determined, and a feeder topology clustering structure for the fault area was constructed. This solved the problem that traditional protection schemes are difficult to accurately identify fault propagation paths and are prone to protection maloperation or leakage, thereby improving the efficiency and accuracy of identifying fault areas in feeder networks with complex topology structures.

[0016] Furthermore, by analyzing the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes, and based on this, the differential tripping sequence of the protection device is formulated, enabling the protection device to respond quickly under complex transient current propagation characteristics, effectively avoiding false tripping in non-fault areas, and ensuring the operational reliability and stability of the distribution network under distributed photovoltaic access conditions. Attached Figure Description

[0017] Figure 1 A flowchart of a grid-connected protection method for distributed photovoltaic power generation provided by the present invention;

[0018] Figure 2 A schematic diagram of the structure of an electronic device provided by the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of a computer-readable storage medium provided by the present invention. Detailed Implementation

[0020] 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.

[0021] Example 1

[0022] Please see Figure 1 As shown in the figure, this embodiment discloses a grid-connected protection method for distributed photovoltaic power generation, the method comprising:

[0023] S101: Collect feeder transient current data and establish feeder topology; perform phasor rotation processing on the transient current data based on the feeder topology to generate feeder node transient phasor matrix;

[0024] S102: Construct a topology map of fault current propagation based on the transient phasor matrix of the feeder node, and extract the phasor trajectory offset features of the feeder node in the topology map to determine the initial fault feeder node.

[0025] S103: Using the initial faulty feeder node as a reference, trace the topological propagation path of the node's transient phasor trajectory to reconstruct the feeder topological clustering structure in the faulty region.

[0026] S104: Based on the feeder topology clustering structure, analyze the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes, formulate the differential tripping sequence of protection devices, and output the tripping command of protection devices according to the sequence.

[0027] Specifically, the feeder transient current data refers to the measured transient current value generated by the feeder at the moment of a fault. It should be understood that this transient current data is acquired in real time by current transformers installed at the feeder nodes. The current transformers at each node simultaneously acquire the three-phase current signals of the feeder at the same sampling frequency, and the obtained data constitutes the three-phase transient current time-domain data sequence of each node.

[0028] For example, with feeder nodes For example, the transient current data acquired at the moment of a fault can be represented as a three-phase current time-domain data sequence: ;in, Representing nodes respectively The transient currents of phases A, B, and C as a function of time

[0029] The change in t Indicates the time when the fault occurred. This indicates the duration of transient data acquisition; the specific value is set according to the actual protection requirements on site.

[0030] Furthermore, the feeder topology refers to the spatial connection relationships between feeder network nodes. Specifically, the topology is obtained based on the actual wiring method of the feeder network and is defined as a graph structure. ,in: For the set of feeder nodes; This is the set of connecting edges between feeder nodes, and the connection method of the edges corresponds to the actual wiring of the feeder.

[0031] For example, if the feeder network contains nodes The connection between nodes is a node Connecting nodes and nodes The topological structure is then represented as: .

[0032] Specifically, the transient current data is subjected to node-joint phasor rotation processing based on the feeder topology, including:

[0033] Extract the spatial node connection relationships of the feeder topology, divide the topologically associated node clusters, and determine the topological spatial positional relationships of the nodes within each cluster.

[0034] Specifically, according to the feeder topology diagram The spatial connectivity between nodes is extracted, and the topology is partitioned into clusters using a graph partitioning algorithm to form a set of node clusters. Each cluster The included nodes satisfy the topological connection tightness constraint, that is, the topological connection path length of nodes within the same cluster meets the preset threshold requirement.

[0035] For example, if the preset node topology connection path length threshold is 2, then the node With nodes The path length between them is 1, which satisfies the constraint condition, so they can be assigned to the same cluster; if the node With nodes If the path length is greater than 2, the nodes will be assigned to different clusters. Based on the above principle, the topology clustering of each node can be achieved.

[0036] Furthermore, based on the cluster partitioning and the actual spatial layout of the feeders, the topological spatial relationship of each node within the cluster is determined, including the connection order and direction between nodes, thus obtaining a spatial connection structure diagram within the cluster. .

[0037] Calculate the spatial phase difference of transient current data of nodes in the node cluster, and determine a unified reference phase based on the spatial distribution characteristics of the node phase difference;

[0038] Specifically, the spatial phase difference of transient current data between nodes within a node cluster is defined as the difference between the initial phases of the transient current between any two nodes within the same cluster. The initial phase is determined by the moment when the transient current first crosses zero, that is, the moment when the transient current first changes from negative to positive and crosses zero is used as the reference moment. The initial spatial phase difference of the corresponding node is calculated by the difference between this reference moment and the zero-crossing moment of the reference node.

[0039] Specifically, let's set up a node cluster. The set of nodes is Select one of the nodes This serves as a reference node within the cluster. Define the node. The initial zero-crossing time of the transient current is Then the node With reference node Initial phase difference between for: ;in, This indicates the rated power frequency of the feeder, typically 50Hz; and Representing nodes respectively and reference node The initial zero-crossing time of the transient current is extracted from the measured transient current data of each node.

[0040] Among them, determining the unified reference phase based on the spatial distribution characteristics of the node phase difference includes:

[0041] Identify the spatial distribution characteristics of transient current zero-crossing moments of each node in the node cluster and exclude data at abnormal zero-crossing moments.

[0042] Specifically, for clusters The initial zero-crossing time data of all nodes are analyzed to determine their spatial statistical characteristics. Specifically, statistical methods are used to identify outliers and eliminate abnormal zero-crossing time data caused by measurement errors or interference. The specific outlier elimination method can be implemented as follows:

[0043] First, calculate the mean of the zero-crossing times for each node in the cluster. and standard deviation ,node The zero crossing time is The calculation expression is: ;

[0044] Then, the range of normal zero-crossing times is determined using the statistical outlier discrimination method. Data outside this range is considered abnormal and is therefore excluded.

[0045] Based on the effective spatial distribution characteristics of node zero-crossing times, spatial clustering fitting is performed on the spatial phase difference of nodes to determine the unified reference phase of the node cluster.

[0046] Specifically, spatial clustering analysis is performed using the initial phase difference data of nodes after excluding outliers. The density-based clustering algorithm (DBSCAN) is used to cluster the initial phase differences of the nodes, and a cluster radius parameter is set. The cluster center with a cluster point count threshold MinPts is defined as the unified reference phase of the node cluster, where the spatial distribution is concentrated and the number of data points meets the threshold condition. .

[0047] In the above process, the cluster radius parameter The specific value of the cluster point threshold MinPts is determined based on the actual transient characteristics of the feeder and the protection accuracy requirements, and is obtained through offline training or field verification before the protection device is deployed.

[0048] Based on a unified reference phase, the node transient current data is calibrated by a node-by-node spatial phasor rotation to generate the feeder node transient phasor matrix.

[0049] Specifically, in determining the unified reference phase of the node cluster Subsequently, to achieve consistency in the spatial reference of transient current data from each node, phasor rotation calibration needs to be performed on the transient current data of each node within the cluster. This phasor rotation calibration, based on dynamic phasor analysis theory, projects the time-series current signals from nodes at different physical locations onto a unified rotating reference coordinate system. The specific processing method for phasor rotation calibration is as follows:

[0050] First, extract the initial phase of the raw transient current data for each node. The initial phase is calculated using the same method as defined above, i.e., it is determined based on the moment when the transient current first crosses zero.

[0051] Furthermore, the transient current data of the nodes is expressed in phasor form, that is, the transient current phasor of each node. Represented as: In the formula, For nodes The transient current amplitude data; j is the imaginary unit; This represents the initial phase of the transient current data for this node.

[0052] Furthermore, to unify the phasors of each node under a reference phase for comparison and analysis, the transient current phasors of the nodes undergo rotation calibration. Specifically, the nodes... Rotationally calibrated transient current phasor The calculation expression is: In the formula: The aforementioned unified reference phase for the node cluster.

[0053] The essence of the above-mentioned rotation calibration process is to compensate for the initial phase of the transient current data of each node, thereby eliminating the influence of the initial phase difference between different nodes and realizing a spatially unified reference system for the transient current data of nodes.

[0054] Finally, the rotated-calibrated transient current phasors of all cluster nodes are arranged in the node space topology order to form the feeder node transient phasor matrix. Assuming the total number of feeder nodes is N and the number of sampling points is T, then the node transient phasor matrix... The structure is as follows:

[0055]

[0056] In the formula, each row represents the transient current data of a certain node under a unified reference phase, and each column represents the transient current data of different nodes at the same time, realizing the centralized expression of transient information of the feeder network.

[0057] Specifically, a topology diagram of fault current propagation is constructed based on the transient phasor matrix of the feeder nodes, including:

[0058] Extract the spatial anomaly offset region of the phasor trajectory of the feeder node, and determine the node anomaly offset set based on the spatial topological correlation characteristics of the node anomaly offset region.

[0059] Specifically, based on the aforementioned generated feeder node transient phasor matrix The trajectory information of transient phasors at each node is extracted to identify spatial regions with abnormal offset characteristics in the node trajectory. It should be understood that the abnormal offset characteristics of the phasor trajectory here specifically refer to the continuous deviation of the phasor position relative to the steady-state operating trajectory during the time-series change of the node transient current phasor.

[0060] In the specific processing, the nodes are first extracted. Transient current phasor trajectory during steady-state operation before the fault occurs To improve the sensitivity and anti-interference capability of offset recognition, the reference trajectory Taken from the time of the failure The moving average of the transient phasor sequence of at least two complete power frequency cycles is used as the spatial reference trajectory for normal operation.

[0061] Furthermore, the phasor trajectory of the computing node during the actual operational phase after the fault occurs. The degree of offset from the aforementioned reference trajectory is obtained by calculating the Euclidean distance between the phasor endpoints in the complex plane, specifically using the phasor trajectory offset exponent. The calculation process is as follows: In the formula, It represents the modulus of a complex number, reflecting the offset of the phasor trajectory of the transient current at the node relative to the normal operating trajectory.

[0062] Furthermore, by giving a preset offset exponent threshold Extract the abnormal offset regions from all node data that meet the following conditions:

[0063] If and only if the phasor trajectory offset exponent of the node For a continuous period of time, the values ​​are greater than or equal to a given threshold. When this happens, the spatial location corresponding to the node is determined to be the abnormal offset region of the node.

[0064] Among them, threshold The selection is based on historical operating data or simulation analysis results of the feeder network to ensure that it can accurately reflect the offset characteristics of the node's trajectory under fault conditions.

[0065] After extracting the abnormal offset regions of all nodes, further, based on the spatial connection relationships between nodes in the feeder topology, the abnormal offset regions of nodes with spatial adjacency are spatially topologically associated and aggregated to form a set of abnormal node offsets. .

[0066] For example, suppose node ,node ,node If the three nodes are spatially adjacent and all exhibit abnormal trajectory offset characteristics, then the abnormal offset regions corresponding to these three nodes can collectively constitute a set of abnormal node offsets. .

[0067] Based on the spatial relationship between the set of abnormal node offsets and the nodes in the feeder topology, the propagation path of abnormal node offsets is identified.

[0068] Specifically, regarding the above-obtained set of abnormal node offsets The propagation path of abnormal offset is determined based on the spatial connection relationship of nodes in the feeder topology, and the propagation path represents the actual diffusion process of abnormal offset phenomenon in the spatial topology network.

[0069] It should be understood that the identification process of abnormal offset propagation paths specifically includes: First, taking each node in the set of abnormal offset nodes as the initial node, traversing its neighboring nodes one by one according to the spatial connection relationship of the feeder topology; further, for the initial node... Each adjacent node Analyze the phasor trajectory offset exponent of adjacent nodes Based on the temporal change characteristics, if the occurrence time of the abnormal offset characteristic of the adjacent node is equal to or later than the occurrence time of the abnormal offset characteristic of the initial node, then it is determined that the abnormal offset phenomenon exists originating from the initial node. to adjacent nodes The spatial topology of propagation; propagation path.

[0070] Specifically, for any initial node and its neighboring nodes Let the initial node be... The time when the abnormal offset feature first appears is Adjacent nodes The time when the abnormal offset feature first appears is If the following conditions are met: Then the initial node is determined. To adjacent nodes There are abnormal offset propagation paths;

[0071] Furthermore, based on the above process, traverse the entire set of abnormal node offsets. The set of all abnormal offset propagation paths of nodes is determined by the spatial adjacent nodes, denoted as . ;

[0072] For example, if the initial node set In the middle, node neighboring nodes The abnormal offset features appeared later than the node. The occurrence time indicates the presence of an abnormal node offset propagation path. .

[0073] Spatial topological association is performed between the propagation path and the set of abnormal node offsets to form a topological map of fault current propagation;

[0074] Specifically, based on the aforementioned set of node anomaly offset propagation paths obtained... Combined with the set of abnormal node offsets By analyzing the topological relationships between the nodes, a complete fault current propagation topology map can be constructed. .

[0075] It should be understood that the fault current propagation topology diagram The graph is a directed graph structure. The nodes in the graph represent feeder nodes exhibiting abnormal offset characteristics, and the directed edges represent the spatial propagation direction of the abnormal offset characteristics in the topology network. The specific graph construction process is disclosed as follows:

[0076] First, the set of abnormal node offsets All nodes within are considered as the node set in the topology graph; further, the set of propagation paths for abnormal node offsets is used. The paths in the topology are represented as the set of directed edges in the topology graph, and the propagation paths are... Represents the nodes in the topology graph Pointing to node A directed edge;

[0077] In cases where multiple topological paths point to the same node, i.e. when a node has multiple in-degrees, the corresponding paths are merged according to the topological connection relationship to ensure that the spatial propagation direction of the topological graph is consistent and clear.

[0078] Specifically, for nodes If multiple in-degree topological paths exist: Then all of the above paths will be retained in the topology graph. In, and with nodes As a topological spatial association node, it ensures that the topological graph structure fully reflects the multipath spatial propagation phenomenon of current anomaly offset characteristics;

[0079] Furthermore, through the above spatial topology correlation processing, the fault current propagation topology map is finally obtained. ;

[0080] For example, a set of nodes There are node propagation paths: In the final constructed fault current propagation topology, the nodes As a spatial propagation node, it has multiple in-degree paths, forming a node-based network. The topological association structure centered on this.

[0081] Specifically, the phasor trajectory offset features of the feeder nodes in the topology graph are extracted to determine the initial faulty feeder node, including:

[0082] Extract the duration stability of node trajectory offsets and filter the valid trajectory offset regions based on the stability duration threshold;

[0083] Specifically, to determine the validity of node trajectory offsets, the stability index of the node trajectory offset features in the duration dimension is first calculated. Among them, stability indicators The calculation process is as follows:

[0084] First, based on the phasor change curves of the nodal trajectory offset characteristics, the positions where the phasor trajectories deviate from the initial steady state are determined, and the duration of each offset position is recorded, defined as the offset duration. Furthermore, the duration of the offset With respect to the preset stability duration threshold By comparing the data, the node trajectory offset regions that meet the following conditions are selected as valid regions: ;

[0085] Among them, the predetermined stability duration threshold It is obtained through experimental or historical operational data statistical analysis based on the actual feeder topology and transient current propagation characteristics.

[0086] Analyze the topological spatial distribution concentration characteristics of the effective trajectory offset region to determine the concentrated region of node trajectory offset;

[0087] Specifically, based on the aforementioned determined effective trajectory offset regions, the concentration characteristics of each effective region in the topological space are further analyzed. The topological spatial distribution concentration index is defined as the spatial distance between adjacent nodes in the topological network in terms of node trajectory offset:

[0088] First, construct a spatial adjacency matrix based on the topological positional relationships of the nodes. Matrix elements Define as a node With nodes The topological connections between nodes; if there are direct topological connections between nodes, then... ,otherwise Furthermore, based on the node set corresponding to the effective trajectory offset region Calculation node concentration index The calculation method is as follows: ,in, Represents a node The degree of topological spatial concentration within the effective offset region; the larger the value, the more concentrated the spatial positions of the node are with other offset nodes.

[0089] Furthermore, based on the calculated concentration index Set a concentration threshold Select nodes that meet the following conditions as the core node set of the trajectory offset concentration region. : Among them, the threshold for the degree of concentration in the topological space. It can be obtained based on historical operational statistics or simulation analysis.

[0090] The initial faulty feeder node is determined based on the topological spatial location of the concentrated region of node trajectory offset.

[0091] Specifically, based on the aforementioned determined set of core nodes Further analysis of its topological spatial relationships is needed to determine the initial faulty feeder node:

[0092] First, construct the core node set. Topological shortest path matrix between internal nodes , of which elements Represents a node With nodes The topological shortest path length between them;

[0093] Furthermore, calculate the average shortest path length from each core node to other core nodes. The calculation formula is as follows: ,in, The smaller the value, the closer the node is to the center of the fault location;

[0094] Furthermore, from the core node set Select the average shortest path length The smallest node is used as the initial fault feeder node. .

[0095] Specifically, taking the initial faulty feeder node as a reference, the topology propagation path of the node's transient phasor trajectory is traced to reconstruct the feeder topology clustering structure in the fault region, including:

[0096] Based on the spatial topological similarity between the initial fault feeder node and the trajectory propagation paths of adjacent nodes, candidate topological directions for node trajectory propagation are determined.

[0097] Specifically, based on the initial faulty feeder node determined above... Starting from this point, we analyze the phasor trajectory propagation paths of adjacent nodes to determine candidate topological directions for node trajectory propagation:

[0098] First, extract the initial faulty feeder node. set of neighboring nodes The transient phasor trajectory data, specifically the trajectory data sequence of corresponding nodes in the transient phasor matrix, is used in this embodiment to construct a feature vector composed of complex phasors from consecutive sampling times to achieve high-dimensional feature extraction. ;

[0099] Furthermore, the trajectory propagation similarity index between the initial faulty feeder node and each adjacent node is calculated. The specific calculation process is as follows:

[0100] With the initial faulty feeder node Using the phasor trajectory data as a reference trajectory, calculate its relationship with adjacent nodes. Cosine similarity between phasor trajectories: ,in, This represents the conjugate transpose of the eigenvectors. This indicates taking the real part, thereby characterizing the synergy of the two node transient phasors in temporal evolution and spatial deflection;

[0101] Furthermore, based on the trajectory propagation similarity index obtained from the above calculations... Set a similarity threshold From the set of adjacent nodes Nodes that meet the following conditions are selected as the set of nodes for candidate topology propagation directions. : Among them, the similarity threshold Obtained through simulation verification or historical data analysis.

[0102] Furthermore, based on the determined candidate topology propagation direction node set Based on this, the propagation direction of the next node is determined layer by layer, and the initial framework structure of the candidate topology propagation path is formed.

[0103] Based on the analysis of candidate topological directions, the spatial aggregation characteristics of adjacent node trajectories are analyzed to identify potential regions where node trajectories intersect topologically.

[0104] Among them, identifying potential regions where node trajectories intersect topologically includes:

[0105] Extract the spatial topological overlap region of the node trajectory, and determine the candidate nodes for topological intersection based on the spatial distribution density of the overlap region;

[0106] Specifically, to identify potential topological intersection regions of node trajectories, the spatial overlap of node trajectories in the candidate topological propagation direction node set within the feeder topology should first be analyzed. The spatial topological overlap region is defined as the region within the feeder diagram... In the context of a network, the set of shared edges covered by the propagation paths of multiple candidate direction nodes and their associated nodes are defined.

[0107] Further, define nodes With nodes Topological overlap index for: In the formula: For nodes With nodes The length of the overlapping path of the trajectory in the feeder topology; For nodes With nodes The sum of the lengths of the trajectory paths.

[0108] Furthermore, by calculating the topological overlap index of any two nodes within the candidate direction node set, a preset spatial topological overlap threshold is applied. Based on the criteria, node pairs that satisfy the following formula are selected to determine the spatial topological overlap region: ;

[0109] For example, determining node pairs through calculation and The topological overlap indexes are all greater than or equal to the threshold. Then the set of nodes The topological path region is determined to be a spatial topological overlap region.

[0110] Furthermore, to accurately screen candidate nodes for topological intersections, it is also necessary to analyze the spatial distribution density of the aforementioned topological overlap regions. Define spatial distribution density. The calculation formula is: In the formula: This represents the number of nodes within the spatial topological overlap region. This represents the node range occupied by the topological overlap region in the feeder topology.

[0111] Furthermore, a spatial distribution density threshold is set. Filter regions that satisfy the following formula to determine the set of candidate nodes for topological intersection: .

[0112] Based on the spatial topological association strength of candidate node trajectories, potential regions of topological intersection of node trajectories are determined;

[0113] Specifically, to further clarify the potential regions of topological intersection of node trajectories, it is necessary to analyze the topological association strength between nodes within the candidate node set. The topological association strength describes the tightness of the trajectory propagation paths between candidate nodes in the spatial topology.

[0114] Specifically, the topological association strength matrix is ​​defined as follows: , where matrix elements For nodes To the node The topological association strength between them is calculated using the following expression: In the formula: Represents a node To the node The actual number of existing trajectory propagation paths; Represents a node To the node The total number of all possible paths in the topology.

[0115] Furthermore, a threshold for topological association strength is set. For the correlation strength matrix Perform filtering when matrix elements When the following formula is satisfied, the corresponding nodes are confirmed to constitute a potential topological intersection region: .

[0116] By integrating the potential intersection region of node trajectory topology with the spatial relationship of feeder topology, a feeder topology clustering structure for the fault region is formed;

[0117] Specifically, in order to construct a feeder topology clustering structure for the fault area, the accurate topology clustering of the fault area should be completed based on the previously determined potential intersection areas of node trajectory topologies and the spatial connection relationships of the feeder topology.

[0118] It should be noted that the potential intersection region of node trajectory topology refers to the region in which the node trajectory exhibits high-intensity spatial aggregation characteristics within the feeder topology network. The spatial topological positional relationship of the nodes in this region reflects the actual intersection of abnormal current propagation, and therefore serves as an important basis for subsequent topological clustering.

[0119] In the specific implementation process, the feeder topology clustering structure in the fault area is defined as a topology clustering subgraph. , where the set of nodes The set of nodes and edges determined within the potential region of topological intersection. This represents the actual connection relationships between the nodes within the node set in the feeder topology.

[0120] Furthermore, based on the node set By establishing the correspondence between the topology and the feeder topology, spatial topological connection information between nodes is extracted one by one to construct a complete set of topological clustering edges. The specific construction process is as follows:

[0121] First, traverse the node set. For each node, extract the set of that node and its sibling nodes. The spatial topological connections between other nodes; secondly, for nodes ,node If and only if the feeder topology When direct connections exist in the edge set, meaning the connections are real, then the edges in the cluster are considered as follows: Add corresponding topology connection edges to Then, repeat the above process until the node set is complete. Extract spatial topology connection information of all nodes.

[0122] Furthermore, complete the above topological clustering edge set. After construction, a complete feeder topology clustering structure subgraph of the fault area is obtained. This topological clustering subgraph reflects the precise topological relationships of the fault region, providing a clear topological spatial basis for subsequent protection actions.

[0123] For example, suppose a set of nodes The node connections in the feeder topology are as follows: With nodes ,node With nodes If direct connections exist, the topological clustering subgraph can be specifically represented as: .

[0124] Specifically, the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes are analyzed to determine the differential tripping sequence of protection devices, including:

[0125] Extract the set of bifurcation nodes in the topological space of the node trajectory and analyze the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory;

[0126] Specifically, in the aforementioned fault region feeder topology clustering structure Based on this, a joint analysis is performed on the topological connectivity between nodes and the propagation characteristics of phasor trajectories to identify the set of topological bifurcation nodes.

[0127] It should be understood that a topological bifurcation node refers to a node in a topological clustering structure whose number of adjacent nodes is greater than or equal to 2 and whose corresponding phasor trajectory propagation direction shows a tendency to separate. This type of node reflects the shunting location of the fault current propagation path.

[0128] Furthermore, for the node set any node Its topological connectivity is defined as: ,in, Represents a node With nodes The connectivity indicator in the cluster structure takes a value of 1 when a connectivity exists, and a value of 0 otherwise.

[0129] Furthermore, nodes that satisfy the following condition are selected to form a set of topological bifurcation nodes. : ;

[0130] For example, if node Simultaneously with nodes ,node If a connection exists, then the node It was identified as a topological bifurcation node.

[0131] Furthermore, in order to analyze the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory, it is necessary to quantify the propagation direction of the phasor trajectory between the bifurcation node and its adjacent nodes.

[0132] Specifically, define nodes Its neighboring nodes The trajectory propagation direction vector is: ,in, Representing nodes respectively ,node The position vector in the topological space.

[0133] Furthermore, to characterize the spatial relationships between different propagation directions, a directional correlation coefficient is defined. for: ,in, This represents the vector dot product operation. This represents the magnitude of a vector.

[0134] Furthermore, by calculating the bifurcation nodes The set of directional correlation coefficients pointing to different adjacent nodes identifies the degree of spatial separation between the directions of trajectory propagation. When the distribution of directional correlation coefficient values ​​exhibits a multi-directional dispersion characteristic, it indicates that there is a multi-path propagation relationship at the bifurcation node.

[0135] Based on the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory, the topology level of the protection device is classified;

[0136] Specifically, in obtaining the set of bifurcation nodes After considering the spatial correlation characteristics of its trajectory propagation direction, and combining the feeder topology clustering structure of the fault area, the corresponding nodes of each protection device are classified into topology levels.

[0137] It should be noted that the topology level of the protection devices is used to describe each protection device relative to the initial fault feeder node. Spatial hierarchical relationship.

[0138] Specifically, firstly, a topological distance function from a node to the initial fault node is constructed based on the clustering structure. This distance represents the length of the shortest topological path between nodes.

[0139] Furthermore, the protection devices are hierarchically divided based on node topological distances, and a protection device level function is defined. ;

[0140] It should be understood that the smaller the topological distance of a node, the closer its corresponding protection device is to the fault source in the fault propagation path.

[0141] Furthermore, within the same topological distance level, the protection devices at the same level are further subdivided based on the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory.

[0142] Specifically, the refined division determines the priority relationship of nodes within the same level by analyzing the directional consistency between the node trajectory propagation direction and the main fault propagation path. directional consistency is determined by the angle between the node trajectory propagation direction vector and the main fault propagation direction vector; a smaller angle indicates higher directional consistency.

[0143] In one specific embodiment, if node With nodes Located at the same topological distance level, but nodes If the direction of propagation is closer to the main propagation path, then the node has higher priority than the node at that level. .

[0144] Based on the topology level of the protection device and the spatial relationship of the corresponding nodes, a differential tripping sequence of the protection device is formed;

[0145] Specifically, in order to achieve rapid and accurate fault area isolation, it is necessary to construct a complete differential tripping sequence for the protection devices based on the aforementioned protection device topology level results and the spatial positional relationship of the corresponding nodes of each protection device in the feeder topology clustering structure.

[0146] It should be understood that the differential tripping sequence refers to the step-by-step execution of tripping operations according to the topology level of the protection device, so as to ensure the rapid isolation of the fault area and minimize the impact on the power supply of the non-fault area.

[0147] In the specific implementation process, firstly, based on the topology level function of the corresponding node of each protection device... The topology levels are sorted in ascending order to obtain the basic protection device topology sequence.

[0148] Furthermore, based on the topology hierarchy sequence, protection devices of the same topology level need to be reordered in a secondary manner, taking into account the spatial correlation of each node.

[0149] Specifically, the spatial location correlation of nodes is defined as the topological path length between adjacent nodes. Nodes that are closer to the initial fault node and have shorter topological path lengths have higher priority within the same level.

[0150] For nodes with the same topology level and Calculate its relationship with the initial fault node. Shortest path length in spatial topology between and The sorting relationships between nodes are determined according to the following rules:

[0151] If the following conditions are met: Then the node Within the same topology level, the order is higher than the node. .

[0152] By using the above method, the differential tripping sequence of all protection devices at each corresponding node is completed step by step, thereby obtaining a complete differential tripping sequence of protection devices: In the formula, the earlier the protection device is in the sequence, the higher its tripping execution priority is.

[0153] For example, if the node corresponding to the protection device with topology level 1 is The node with topology level 2 is and The calculated shortest path length in the spatial topology satisfies: The specific sequence of differential tripping is as follows: ;

[0154] Furthermore, the protection device executes tripping actions sequentially according to the above differential tripping sequence to achieve precise and rapid isolation of the fault area.

[0155] Ultimately, each protection device trips according to the differential trip sequence. The tripping action is executed in a coordinated manner. Specifically, the protection devices output tripping commands in sequence and monitor current changes or the status of circuit breaker auxiliary contacts in real time to determine the tripping result. After the current protection device is detected to have tripped successfully, the tripping execution of the subsequent protection devices is immediately terminated. Only when the current protection device fails to trip or does not respond will the tripping commands of the subsequent protection devices be executed in sequence.

[0156] The aforementioned differential tripping process achieves rapid sharing of tripping status among nodes through a distributed protection communication network (such as GOOSE communication based on the IEC61850 standard), thereby ensuring rapid and accurate isolation of faulty lines and effectively preventing unnecessary tripping of non-faulty lines, thus maximizing the reliability and stability of the power supply of the distribution network.

[0157] Example 2

[0158] Please see Figure 2 As shown, this embodiment discloses an electronic device, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, it implements any of the grid-connected protection methods for distributed photovoltaic systems provided by the above methods.

[0159] Since the electronic device described in this embodiment is the electronic device used to implement the grid-connected protection method for distributed photovoltaic power generation in the embodiments of this application, those skilled in the art can understand the specific implementation methods and various variations of the electronic device in this embodiment based on the grid-connected protection method for distributed photovoltaic power generation described in the embodiments of this application. Therefore, how the electronic device implements the method in the embodiments of this application will not be described in detail here. Any electronic device used by those skilled in the art to implement the grid-connected protection method for distributed photovoltaic power generation in the embodiments of this application falls within the scope of protection intended for this application.

[0160] Example 3

[0161] Please see Figure 3 As shown, this embodiment discloses a computer-readable storage medium, including a memory, a processor, and a computer program stored on the memory and running on the processor. When the processor executes the computer program, it implements any of the grid-connected protection methods for distributed photovoltaic systems provided by the above methods.

[0162] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters, weights, and thresholds in the formulas are set by those skilled in the art according to the actual situation.

[0163] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of the present invention are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via a wired or wireless network. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that includes one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0164] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed in this invention can be implemented in electronic hardware or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0165] Those skilled in the art will understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0166] In the several embodiments provided by this invention, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of units is only one method, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0167] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0168] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0169] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

[0170] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. 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 grid-connected protection method for distributed photovoltaic power generation, characterized in that, include: Collect transient current data of the feeder and establish the feeder topology; Based on the feeder topology, the transient current data is subjected to node joint phasor rotation processing to generate a feeder node transient phasor matrix. A topology map of fault current propagation is constructed based on the transient phasor matrix of the feeder node, and the phasor trajectory offset features of the feeder node in the topology map are extracted to determine the initial fault feeder node. Using the initial faulty feeder node as a reference, the topological propagation path of the node's transient phasor trajectory is traced to reconstruct the feeder topological clustering structure in the fault region. Based on the feeder topology clustering structure, the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes are analyzed, the differential tripping sequence of protection devices is formulated, and the tripping command of protection devices is output according to the sequence.

2. The method according to claim 1, characterized in that, Based on the feeder topology, the transient current data undergoes node-joint phasor rotation processing, including: Extract the spatial node connection relationships of the feeder topology, divide the topologically associated node clusters, and determine the topological spatial positional relationships of the nodes within each cluster. Calculate the spatial phase difference of transient current data of nodes in the node cluster, and determine a unified reference phase based on the spatial distribution characteristics of the node phase difference; Based on a unified reference phase, node-by-node spatial phasor rotation calibration is performed on the transient current data of the nodes to generate the transient phasor matrix of the feeder nodes.

3. The method according to claim 2, characterized in that, Determining a unified reference phase based on the spatial distribution characteristics of node phase differences includes: Identify the spatial distribution characteristics of transient current zero-crossing moments of each node in the node cluster and exclude data at abnormal zero-crossing moments. Based on the effective spatial distribution characteristics of node zero-crossing times, spatial clustering fitting is performed on the spatial phase difference of nodes to determine the unified reference phase of the node cluster.

4. The method according to claim 1, characterized in that, A topology diagram of fault current propagation is constructed based on the transient phasor matrix of the feeder nodes, including: Extract the spatial anomaly offset region of the phasor trajectory of the feeder node, and determine the node anomaly offset set based on the spatial topological correlation characteristics of the node anomaly offset region. Based on the spatial relationship between the set of abnormal node offsets and the nodes in the feeder topology, the propagation path of abnormal node offsets is identified. Spatial topological association is performed between the propagation path and the set of abnormal node offsets to form a topological map of fault current propagation.

5. The method according to claim 1, characterized in that, Extracting the phasor trajectory offset features of feeder nodes in the topology graph to determine the initially faulty feeder node includes: Extract the duration stability of node trajectory offsets and filter the valid trajectory offset regions based on the stability duration threshold; Analyze the topological spatial distribution concentration characteristics of the effective trajectory offset region to determine the concentrated region of node trajectory offset; The initial faulty feeder node is determined based on the topological spatial location of the concentrated area of ​​node trajectory offset.

6. The method according to claim 1, characterized in that, Using the initial faulty feeder node as a reference, the topological propagation path of the node's transient phasor trajectory is traced to reconstruct the feeder topological clustering structure in the fault region, including: Based on the spatial topological similarity between the initial fault feeder node and the trajectory propagation paths of adjacent nodes, candidate topological directions for node trajectory propagation are determined. Based on the analysis of candidate topological directions, the spatial aggregation characteristics of adjacent node trajectories are analyzed to identify potential regions where node trajectories intersect topologically. By integrating the potential intersection region of node trajectory topology with the spatial relationship of feeder topology, a feeder topology clustering structure for fault areas is formed.

7. The method according to claim 6, characterized in that, Identify potential regions where node trajectories intersect topologically, including: Extract the spatial topological overlap region of the node trajectory, and determine the candidate nodes for topological intersection based on the spatial distribution density of the overlap region; Based on the spatial topological association strength of candidate node trajectories, potential regions where node trajectories intersect are determined.

8. The method according to claim 1, characterized in that, Analyze the topological bifurcation and intersection characteristics of the transient phasor trajectories of feeder nodes, and formulate the differential tripping sequence of protection devices, including: Extract the set of bifurcation nodes in the topological space of the node trajectory and analyze the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory; Based on the spatial correlation characteristics of the propagation direction of the bifurcation node trajectory, the topology level of the protection device is classified; Based on the topology level of the protection device and the spatial relationship of the corresponding nodes, a differential tripping sequence of the protection device is formed.

9. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that, When the processor executes the computer program, it implements the method according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed, implements the method described in any one of claims 1 to 8.

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