A power distribution network topology identification and fault location method based on zero sequence current characteristics

Abstract

This invention discloses a method for distribution network topology identification and fault location based on multi-dimensional zero-sequence current characteristics. By fusing transient high-frequency information, steady-state phase, and amplitude characteristics of zero-sequence current, and combining this with the standardized configuration of zero-sequence current transformers in ring main units, this invention achieves rapid and accurate identification of single-phase grounding faults and precise inference of the distribution network topology at the time of the fault. This invention belongs to the field of power system distribution network technology, specifically providing a solution to the problems of insufficient accuracy, slow response speed, and weak anti-interference capability in single-phase grounding fault location in distribution networks.

Description

Technical Field

[0001] This invention belongs to the field of power system distribution network technology, specifically referring to a method for distribution network topology identification and fault location based on zero-sequence current characteristics. Background Technology

[0002] In distribution networks, single-phase grounding faults are the most frequent type of fault, typically accounting for over 80%. In recent years, with the widespread integration of distributed power sources and new loads, the electrical characteristics of distribution networks have become increasingly complex, leading to dynamic changes in network structure and frequent fluctuations in operating status. This poses a significant challenge to traditional fault diagnosis methods. Under ring network power supply and complex grounding conditions, the accurate location, isolation, and rapid recovery strategies for zero-sequence faults highly depend on the accuracy and real-time performance of distribution network topology identification.

[0003] However, the widely used distribution feeder terminals (DTUs) and distribution automation terminals (DFUs) mainly rely on zero-sequence current overcurrent monitoring for fault diagnosis. Their inherent limitation is that they cannot directly identify the real-time topology of the distribution network. This significantly limits the sensitivity and accuracy of zero-sequence fault identification in low-current grounding systems, making it difficult to provide reliable diagnostic results.

[0004] Therefore, real-time identification of distribution network topology has a significant impact on the accuracy and adaptability of fault diagnosis. Existing topology identification methods mainly include: ① methods based on voltage correlation analysis, which rely on synchronous voltage sampling of a large number of measurement points, and their reliability decreases when the distribution of points is uneven or the power supply path is complex; ② methods based on smart terminal (STU) information interaction, which require additional communication devices and information fusion mechanisms, increasing system deployment costs and being susceptible to communication delays and data anomalies; ③ methods based on machine learning, which can achieve topology inference through model training, but are sensitive to changes in parameters such as operating mode and grounding method, and the model's generalization ability is insufficient, making it difficult to guarantee the adaptability and robustness of online applications.

[0005] However, in practical engineering applications, especially in zero-sequence fault diagnosis devices that rely on zero-sequence current signals for line selection and location, it is often impossible to obtain synchronous voltage signals or deploy them extensively at terminals. Therefore, the above topology identification methods are difficult to directly apply. Currently, there is a lack of a topology identification method that relies solely on zero-sequence current information, can quickly adapt to changes in distribution network topology, and possesses good fault-finding capabilities. If the directionality and transient amplitude distribution characteristics of zero-sequence current can be utilized in the early stages of a fault, combined with the differences in flow direction between lines, to determine the actual structure of the distribution network, efficient and accurate topology identification can be achieved without relying on voltage measurement points and external equipment. This would greatly improve the application scope, real-time performance, and engineering practicality of zero-sequence fault diagnosis devices. Summary of the Invention

[0006] To address the problems of insufficient accuracy, slow response speed, and weak anti-interference capability in the existing technology for locating single-phase grounding faults in distribution networks, this invention provides a distribution network topology identification and fault location method based on zero-sequence current characteristics. By integrating the transient high-frequency information, steady-state phase and amplitude characteristics of zero-sequence current, and combining it with the standardized configuration of zero-sequence current transformers in ring main units, this method enables rapid and accurate identification of single-phase grounding faults and precise inference of the distribution network topology at the time of the fault.

[0007] The technical solution adopted in this invention is as follows:

[0008] On one hand, this invention discloses a method for distribution network topology identification and fault location based on zero-sequence current characteristics, applied to a power system distribution network. The distribution network includes multiple distribution lines and multiple ring main units or nodes located on these lines. Each ring main unit (or node) is equipped with a zero-sequence current transformer, with the P1 terminal of the zero-sequence current transformer uniformly facing the internal busbar side of the ring main unit, and the P2 terminal uniformly facing the external line side. The method includes the following steps:

[0009] Step S0: High-speed synchronous acquisition of instantaneous zero-sequence current data of each node in the distribution network;

[0010] The acquisition employs a high sampling rate (e.g., not less than 12.8kHz, preferably above 50kHz, more preferably above 100kHz) and a high-precision analog-to-digital converter (e.g., 16-bit or higher bit depth) to ensure sufficient capture of the high-frequency transient components of the zero-sequence current (e.g., signals up to 10kHz). The acquired raw data undergoes preprocessing such as filtering and denoising, and the precise timestamps of each sampling point are recorded synchronously.

[0011] Step S1: Monitor the zero-sequence current data, and capture the initial zero-sequence current response signal of each line after a fault is detected;

[0012] The zero-sequence voltage and zero-sequence current signals are continuously monitored. When the amplitude or change (e.g., differential value) of either signal exceeds a preset threshold, a single-phase ground fault is determined to have occurred in the system. The transient zero-sequence current signal within the first half-wave or the first few cycles after the fault occurs is captured as the initial response signal for the fault.

[0013] Step S2: Extract multi-dimensional features of the zero-sequence current of each line from the initial fault response signal. The multi-dimensional features include high-frequency transient features, steady-state phase features, and steady-state amplitude features.

[0014] High-frequency transient extraction method: Wavelet packet decomposition (WPT) is used to decompose the signal into multiple frequency bands, and the high-frequency channel coefficients of 5kHz to 20kHz are selected; the high-frequency zero-sequence current envelope of each branch is extracted, and its first steep change point is calculated as FirstArrival Time (FAT);

[0015] Wavefront steepness can be calculated using the extreme values ​​of derivatives:

[0016] ;

[0017] Step S3: Based on the unified polarity configuration of the zero-sequence current transformer and the steady-state phase characteristics, determine the physical direction of the zero-sequence current in each distribution network line;

[0018] Accurate determination of the direction of zero-sequence current flow specifically includes:

[0019] 1. Acquire two types of signals:

[0020] Based on the standardized configuration of the zero-sequence current transformers in the ring main unit, where the P1 terminal faces the internal busbar side and the P2 terminal faces the external line side, and combined with the steady-state phase characteristics extracted in step S2, the actual flow direction of the zero-sequence current in each distribution network line is accurately determined (by judging the phase of the current relative to the zero-sequence voltage).

[0021] Direction criterion formula: ;

[0022] 2. Extract the fundamental component (using window function + FFT):

[0023] For discrete sampled signals u[n], i[n], their complex spectral components at 50Hz can be calculated:

[0024] ;

[0025] ;

[0026] Where fs is the sampling frequency (e.g., 12800Hz, 50000Hz, etc.); N is the window length (number of samples); U50 and I50 are the amplitude and phase information in complex form.

[0027] 3. Calculate the phase difference:

[0028] Voltage phase: ;

[0029] Current phase: ;

[0030] The phase difference between the current and the voltage is:

[0031] ;

[0032] if >0, current lags behind voltage;

[0033] if <0, the current leads the voltage.

[0034] 4. Determine whether the incoming, outgoing, and load lines of each ring main unit are on the main path of the fault current:

[0035] Healthy line criterion: If the steady-state phase angle of the zero-sequence current of a certain distribution network line leads its zero-sequence voltage by about 90 degrees (for example, within the range of 80°~100°), then the line is determined to be a healthy line, and its zero-sequence current flows "from the internal busbar of the ring main unit to the external line" (i.e. "flows out" of the ring main unit).

[0036] Fault line judgment criteria: If the steady-state phase angle of the zero-sequence current of a certain distribution network line is significantly deviated by about 90 degrees leading (for example, it is close to being in phase or lagging, such as within the range of -90°~0°), and this phase characteristic is unique among all the distribution network lines, then the line is initially judged to be a fault line, and its zero-sequence current physical flow direction is "from the external line to the internal bus of the ring main unit" (i.e. "flowing into" the ring main unit).

[0037] The direction of the current can also be determined by calculating the time derivative of the transient current at the moment of grounding. When the steady-state amplitude is too small to accurately determine the phase, the transient zero-sequence current amplitude of each line in the ring main unit is compared, and the line with the largest amplitude is selected as the faulty line.

[0038] Step S4: Combining the multi-dimensional features and the physical flow direction, identify the faulty line from all lines according to the preset fault criteria;

[0039] The fault criteria include: the zero-sequence current of the faulty line must simultaneously satisfy the following: a) the high-frequency transient waveform of the zero-sequence current arrives earliest, has the largest wavefront steepness, and the largest transient amplitude; b) the steady-state phase angle of the zero-sequence current of the faulty line deviates significantly from the zero-sequence voltage by about 90 degrees, and this phase characteristic is unique among all the distribution network lines; c) the direction of the faulty zero-sequence current flow is at least two of the following: from the external line to the internal busbar of the ring main unit.

[0040] Among the initially selected lines, the distribution network lines that exhibit a unique zero-sequence current steady-state phase characteristic that "significantly deviates from the lead of approximately 90 degrees" are further selected.

[0041] Further verification: The distribution network line with the earliest arrival of the high-frequency transient waveform, the largest wavefront steepness, and the largest transient current amplitude was selected.

[0042] Consistency constraint criterion: used to suppress interference from abnormal points, such as when multiple branches have signals that are "incompatible in direction" at the same time, the maximum transient amplitude value is used.

[0043] Robust judgment algorithm: When the steady-state phase is unavailable, the direction of the instantaneous rate of change is used instead. Only the current rate of change on the line closest to the fault point is opposite to the direction of other lines (for a single-phase ground fault).

[0044] Step S5: Based on the identification results of the faulty line, the zero-sequence current amplitude and flow direction information of each line, derive and update the real-time topology of the distribution network, and mark the location of the fault point in the topology.

[0045] Graph algorithms for deriving topology: Using minimum spanning tree (MST), connected component analysis, or threshold pruning, valid connection paths in the current network are identified, and the "possible topology graph" of the network is derived. Further annotation of the directionality between nodes (such as current direction) can establish a directed graph.

[0046] Precise fault location: By analyzing the convergence path of zero-sequence current in other healthy lines, and combining the attenuation characteristics and delay information of high-frequency transient wave propagation, the faulty line is highlighted on the distribution network topology map, and the precise location of the fault point is marked.

[0047] Step S6: Fault Location and Topology Output: Combining the identified network structure and current flow, further determine the fault branch affiliation (whether it is a certain load or a connection line between two ring main units), switch disconnection point (such as the ring main unit opening point), and islanded section, etc., generate a fault diagnosis report and output a visual topology map.

[0048] Furthermore, in step S0, a sampling rate of not less than 50kHz and an analog-to-digital converter with a precision of not less than 16 bits are used for data acquisition in order to capture the high-frequency transient component of the zero-sequence current.

[0049] Furthermore, in step S2, the high-frequency transient features are extracted by wavelet packet transform or Hilbert-Huang transform, with the frequency band of interest being 5kHz to 20kHz; the high-frequency transient features include one or more of the following: first arrival time (FAT), maximum wavefront steepness, and peak transient amplitude.

[0050] Further, in step S3, determining the physical flow direction specifically involves calculating the phase difference between the fundamental component of the zero-sequence current and the fundamental component of the zero-sequence voltage for each line:

[0051] If the phase difference is within the first preset range (80°~100°), then the direction of the zero-sequence current of the line is determined to be the outflow node;

[0052] If the phase difference is within the second preset range (-90°~0°) and the phase characteristic is unique in all lines, then the direction of the zero-sequence current of the line is determined to be the inflow node.

[0053] Furthermore, in step S4, if the physical flow direction of multiple lines is determined to be flowing into the busbar, then the line with the largest transient amplitude is selected as the faulty line.

[0054] Furthermore, in step S5, a graph theory algorithm is used to derive the real-time topology structure, including the minimum spanning tree algorithm or the connected component analysis algorithm.

[0055] The location of the fault point is estimated by analyzing the convergence path of the zero-sequence current in the healthy line, and combining the propagation attenuation characteristics and arrival delay information of the high-frequency transient wave.

[0056] Furthermore, in step S5, locating the fault point specifically involves: marking the faulty line on the topology map, and estimating the specific location of the fault point along the line based on the transient wavefront arrival time or attenuation characteristics of the faulty line.

[0057] On the other hand, this application also discloses a distribution network topology identification and fault location system for implementing the above method, the system comprising:

[0058] The data acquisition module is used to execute step S0, which synchronously acquires the zero-sequence current data of each node at high speed.

[0059] The fault detection module is used to perform step S1, monitor data, and capture the initial fault response signal;

[0060] The feature extraction module is used to perform step S2, extracting multi-dimensional zero-sequence current features from the response signal;

[0061] The flow direction determination module is used to execute step S3, which determines the physical flow direction of the zero-sequence current in each line based on polarity configuration and phase characteristics.

[0062] The fault identification module is used to execute step S4, which identifies faulty lines based on multi-dimensional features and flow direction, according to fault criteria.

[0063] The topology construction and location module is used to execute step S5, derive the real-time topology structure, and mark the location of the fault point.

[0064] On the other hand, a computer-readable storage medium is also disclosed, on which a computer program is stored, which, when executed by a processor, implements the steps of the method described above.

[0065] The beneficial effects achieved by the present invention using the above solution are as follows:

[0066] 1. High precision: By integrating the transient high-frequency characteristics of zero-sequence current with steady-state phase and amplitude characteristics, and especially by utilizing the unique criteria of steady-state phase deviation characteristics and high-frequency transient waveform analysis, the accuracy of single-phase grounding fault location is effectively improved. It is particularly suitable for high-resistance grounding faults that are difficult to handle by traditional methods.

[0067] 2. High speed: By utilizing the rapid response characteristics of transient signals and the first arrival time of high-frequency transient waves, it can achieve preliminary fault location at the millisecond or even microsecond level, significantly shortening the fault handling time.

[0068] 3. Strong anti-interference capability: By extracting and analyzing high-frequency transient signals, the influence of interference such as power frequency unbalanced current and background harmonics on line selection accuracy is effectively avoided.

[0069] 4. Topology Adaptability: By comprehensively judging the current direction and multi-node information, it can better adapt to the complex ring network or radial topology of the distribution network without relying on complex impedance or admittance calculations.

[0070] 5. Intuitive Results: Not only does it provide the faulty line, but it can also intuitively locate the fault point on the topology map and provide the topology status at the time of the fault, which facilitates quick decision-making and fault isolation by maintenance personnel. Attached Figure Description

[0071] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.

[0072] Figure 1 This is a schematic diagram of the overall process of the method provided by the present invention;

[0073] Figure 2 This is a schematic diagram of the fault detection and initial response capture process in this invention;

[0074] Figure 3 This is a schematic diagram of the multi-dimensional zero-sequence current feature extraction process in this invention;

[0075] Figure 4 This is a logical diagram illustrating the determination of the physical flow direction of zero-sequence current and the identification of faulty circuits in this invention.

[0076] Figure 5 This is a schematic diagram of a typical 10kV ring network power distribution system;

[0077] Figure 6 A schematic diagram showing the configuration of zero-sequence voltage and zero-sequence current transformers for a single ring main unit.

[0078] Figure 6In the middle, 1. Line zero-sequence current transformer ZCT; 2. Ring main unit bus three-phase and zero-sequence current transformer ZPT0; 3. Incoming or outgoing line switch; 4. Incoming or outgoing line switch; 5. Feeder switch. Detailed Implementation

[0079] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0080] To more clearly illustrate the technical solution of the present invention, the following is combined with... Figures 1-6 The invention also describes in detail the specific implementation of a distribution network topology identification and fault location method based on zero-sequence current characteristics, as well as typical grounding fault scenarios in ring network distribution systems.

[0081] I. System Structure and Data Configuration:

[0082] This implementation method, such as Figure 5 The diagram illustrates a typical 10kV ring network power distribution system. The system includes multiple ring network cabinets (RMU1, RMU2, RMU3, RMU4), interconnected via overhead lines or cables. Figure 6 As shown, each ring main unit contains two incoming and outgoing line interfaces and one load line. Zero-sequence current transformers (ZCTs) are uniformly installed on the incoming and outgoing lines and the load side. A current transformer (ZPT) that can detect zero-sequence voltage is installed on the bus. The polarity of the ZPTs is uniformly configured so that P1 points to the internal bus of the ring main unit and P2 points to the external line.

[0083] The zero-sequence current signals acquired by each ZCT are synchronously sampled by a high-speed acquisition terminal at a sampling frequency of no less than 50kHz. The sampled data is uploaded to the central fault diagnosis unit via industrial Ethernet. The system does not rely on external time synchronization such as GPS or PTP; it only ensures relative synchronization of data sampling.

[0084] II. Fault Scenario Setting:

[0085] Assume that a phase A ground fault occurs in the load-side branch of RMU3, with a grounding resistance of 100Ω, and the fault occurs at time t=0s. After the fault occurs, each non-faulty branch in the distribution network will feed capacitive current to the fault point, forming a transient zero-sequence current response.

[0086] III. Implementation details of each step:

[0087] Step S0: Acquisition and preprocessing of zero-sequence current data:

[0088] The system synchronously acquires zero-sequence current data of each ZCT at a sampling rate of 50kHz and records the corresponding sampling point number. The acquired data is bandpass filtered (2kHz~20kHz) to remove power frequency and noise before being stored in matrix form for subsequent analysis.

[0089] Step S1, Fault Detection and Initial Response Capture:

[0090] When the instantaneous amplitude of the zero-sequence current in any branch exceeds a set threshold (e.g., 2A) or its rate of change (dI / dt) exceeds the normal fluctuation range (e.g., 1000 A / s), the system determines that a fault has occurred. Subsequently, a high-speed buffer data analysis program is started to perform transient analysis on the signal within the first 10ms after the fault.

[0091] Step S2, Feature Extraction:

[0092] For the zero-sequence current signal of each branch, the features are extracted using the following method:

[0093] 2.1 First wave maximum amplitude Ai: Directly take the point with the largest absolute value:

[0094] ;

[0095] 2.2 Wavefront steepness ki: The maximum rate of change is extracted using first-order difference.

[0096] ;

[0097] 2.3 FAT (Optional): If the system has time synchronization capability, the first rise point of the signal wavefront is extracted using the high-frequency wavelet packet envelope.

[0098] These features are used to initially identify the line with the "strongest response," that is, the branch closest to the fault point.

[0099] Step S3, Current Direction and Phase Analysis:

[0100] The fundamental frequency phase is extracted by performing a window function weighted FFT on the sampled signals of each branch:

[0101] Let the fundamental phase of the zero-sequence voltage be φu, and the fundamental phase of each zero-sequence current be φi, then their phase difference is:

[0102] ;

[0103] like A value of approximately 90° indicates a healthy circuit, with current flowing outward from the busbar.

[0104] like If the deviation from this range is significant (such as lag or phase reversal), then the fault is flowing into the line.

[0105] Step S4, Fault Branch Determination:

[0106] The system determines the faulty branch according to the following strategy:

[0107] 1. Identify the line with the largest transient peak value Ai;

[0108] 2. Verify whether its steady-state phase is "current flowing into the busbar";

[0109] 3. If the amplitude and phase characteristics match, it is determined to be a faulty branch;

[0110] 4. If multiple branches meet the inflow conditions, but the amplitude is significantly smaller than the maximum value (<70%), exclude them (consider the possibility of line polarity mismatch).

[0111] For example, in this case, the RMU3 load branch exhibits the largest zero-sequence current amplitude (5.1A), the steepest wavefront (dI / dt=2800A / s), and a phase angle of -60°, while the phase angle of other branches is +88°. Therefore, the RMU3 load branch can be uniquely identified as the faulty line.

[0112] Table 1 Data Response of Specific Implementation Cases:

[0113]

[0114] Step S5, Topology Identification:

[0115] The system abstracts all lines as a graph G(V,E), where:

[0116] V represents each ring main unit; E represents the line connection; the edge weight is taken as the transient zero-sequence current amplitude or propagation index of each branch; the current direction is used as the directionality of the edge.

[0117] Based on this, the system constructs an effective network topology graph for the current moment by using minimum spanning tree (MST) or connected subgraph analysis, combined with fault flow constraints and non-zero response lines. Simultaneously, it highlights faulty branch paths and marks the fault point as the end of the RMU3 load.

[0118] Inference result:

[0119] Faulty line A: RMU3 outgoing line;

[0120] B topology status: RMU1–RMU2 connected, RMU2–RMU3 connected, RUM3–RUM4 disconnected;

[0121] Fault location C: downstream of RMU3 outgoing line; the system is a single-source power supply open-loop structure.

[0122] Step S6, Visualization Output:

[0123] The system generates the following visual output:

[0124] 1) Faulty branch number and ring main unit name;

[0125] 2) Zero-sequence current amplitude, wavefront slope, and direction indication for each branch;

[0126] 3) Current topology graph structure;

[0127] 4) Geographical location of the fault point (can be combined with GIS or line number);

[0128] 5) Fault report documents (including timestamps, data screenshots, graphs, etc.).

[0129] This embodiment does not require precise time synchronization such as GPS synchronization; the topology can be determined by amplitude and direction. It is suitable for low-current systems and applicable to distribution networks of 35kV and below. It only uses zero-sequence voltage and zero-sequence current signals, without the need for ring main unit switch sampling, and is compatible with existing ring main units. It has strong robustness and can adapt to short-term disturbances, data errors and other operating conditions. It is suitable for open-loop operation or multi-opening operation modes.

[0130] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0131] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0132] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention; the actual structure is not limited thereto. In conclusion, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the invention, such designs should fall within the protection scope of the present invention.

Claims

1. A method for topology identification and fault location of a distribution network based on zero-sequence current characteristics, applied to a power system distribution network, wherein the distribution network includes multiple distribution lines and multiple ring main units or nodes located on the distribution lines, wherein each ring main unit or node is equipped with a zero-sequence current transformer, and the P1 terminal of the zero-sequence current transformer uniformly faces the internal busbar side of the ring main unit, and the P2 terminal uniformly faces the external line side, characterized in that... The method includes the following steps: Step S0: High-speed synchronous acquisition of instantaneous zero-sequence current data at each node in the distribution network; Step S1: Monitor the instantaneous value data of zero-sequence current, and capture the initial zero-sequence current response signal of each line after a fault is detected; Step S2: Extract multi-dimensional features of the zero-sequence current of each line from the initial zero-sequence current response signal of the fault. The multi-dimensional features include high-frequency transient features, steady-state phase features, and steady-state amplitude features. Step S3: Based on the unified polarity configuration of the zero-sequence current transformer and the steady-state phase characteristics, determine the physical direction of the zero-sequence current in each distribution network line; Step S4: Combining the multi-dimensional features and the physical flow direction, identify the faulty line from all lines according to the preset fault criteria; The fault criteria include: the zero-sequence current of the faulty line must simultaneously satisfy the following: a) the high-frequency transient waveform of the zero-sequence current arrives earliest, has the largest wavefront steepness, and the largest transient amplitude; b) the steady-state phase angle of the zero-sequence current of the faulty line deviates significantly from the zero-sequence voltage by 90 degrees and lags behind, and this phase characteristic is unique among all the distribution network lines; c) the direction of the faulty zero-sequence current flow is at least two of the following: from the external line to the internal busbar of the ring main unit. Step S5: Based on the identification results of the faulty line, the zero-sequence current amplitude and flow direction information of each line, derive and update the real-time topology of the distribution network, and mark the location of the fault point in the topology. In step S5, a graph theory algorithm is used to derive the real-time topology structure. The graph theory algorithm includes the minimum spanning tree algorithm or the connected component analysis algorithm. The location of the fault point is estimated by analyzing the convergence path of the zero-sequence current in the healthy line, and combining the propagation attenuation characteristics and arrival delay information of the high-frequency transient wave.

2. The method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In step S0, a sampling rate of not less than 50kHz and an analog-to-digital converter with a precision of not less than 16 bits are used for data acquisition in order to capture the high-frequency transient components of the zero-sequence current.

3. The method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In step S2, high-frequency transient features are extracted by wavelet packet transform or Hilbert-Huang transform, with the frequency band of interest being 5kHz to 20kHz; the high-frequency transient features include one or more of the following: first wave arrival time, maximum wavefront steepness, and peak transient amplitude.

4. The method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In step S3, determining the physical flow direction specifically involves calculating the phase difference between the fundamental component of the zero-sequence current and the fundamental component of the zero-sequence voltage for each line: If the phase difference is within the first preset range (80°~100°), then the direction of the zero-sequence current of the line is determined to be the outflow node; If the phase difference is within the second preset range (-90°~0°) and the phase characteristic is unique in all lines, then the direction of the zero-sequence current of the line is determined to be the inflow node.

5. The method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In step S4, if the physical flow direction of multiple lines is determined to be flowing into the busbar, then the line with the largest transient amplitude is selected as the faulty line.

6. The method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In step S5, locating the fault point specifically involves: marking the faulty line on the topology and estimating the specific location of the fault point along the line based on the transient wavefront arrival time or attenuation characteristics of the faulty line.

7. A distribution network topology identification and fault location system for implementing the method of any one of claims 1-6, characterized in that, include: The data acquisition module is used to execute step S0, which synchronously acquires the zero-sequence current data of each node at high speed. The fault detection module is used to perform step S1, monitor data, and capture the initial fault response signal; The feature extraction module is used to perform step S2, extracting multi-dimensional zero-sequence current features from the response signal; The flow direction determination module is used to execute step S3, which determines the physical flow direction of the zero-sequence current in each line based on polarity configuration and phase characteristics. The fault identification module is used to execute step S4, which identifies faulty lines based on multi-dimensional features and flow direction, according to fault criteria. The topology construction and location module is used to execute step S5, derive the real-time topology structure, and mark the location of the fault point.

8. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the program is executed by the processor, it implements the steps of the method as described in any one of claims 1-6.

Images