Power distribution network topology identification and fault location method based on zero-sequence current characteristics

Abstract

The invention discloses a power distribution network topology identification and fault location method based on multi-dimensional zero-sequence current characteristics, and the method comprises the steps: fusing the transient high-frequency information, steady-state phase and amplitude characteristics of zero-sequence current, and combining the standardized configuration of a zero-sequence current transformer of a ring main unit; and rapid and accurate identification of the single-phase earth fault and accurate inference of the topological structure of the power distribution network when the fault occurs are realized. The invention belongs to the technical field of power distribution networks of power systems, and particularly provides a method for solving the problems of insufficient precision, slow response speed and weak anti-interference capability in single-phase earth fault positioning of a power distribution network.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of power distribution network of power system, and particularly relates to a distribution network topology identification and fault positioning method based on zero sequence current characteristics. BACKGROUND

[0002] In the distribution network, single-phase grounding fault is the fault type with the highest occurrence frequency, and its proportion usually exceeds 80%. In recent years, with the wide access of distributed power sources and new types of loads, the electrical characteristics of the distribution network are increasingly complex, which leads to dynamic changes in the network structure and frequent fluctuations in the operation state, thus bringing severe challenges to the traditional fault diagnosis method. Under the power supply of looped networks and complex grounding modes, the accurate positioning, isolation and rapid recovery strategy of zero sequence faults highly depend on the accuracy and real-time performance of the topology identification of the distribution network.

[0003] However, the currently widely used distribution feeder terminal (DTU) and distribution automation terminal (DFU) mainly rely on zero sequence current overcurrent monitoring for fault diagnosis, and the inherent limitation thereof is that the real-time topology structure of the distribution network cannot be directly identified. This leads to the fact that in a small current grounding system, the sensitivity and accuracy of zero sequence fault identification are significantly limited, and it is difficult to provide reliable diagnosis results.

[0004] Therefore, the real-time identification of the topology structure of the distribution network has an important influence on the accuracy and adaptability of fault diagnosis. The existing topology identification methods mainly include: ① a method based on voltage correlation analysis, which relies on synchronous sampling of the voltage of a large number of measuring points, and the reliability thereof decreases when the distribution of the point is uneven or the power supply path is complex; ② a method based on information interaction of intelligent terminals (STU), which needs to rely on additional communication devices and information fusion mechanisms, thus increasing the deployment cost of the system and being susceptible to communication time delay and data anomalies; and ③ a method based on machine learning, which can realize topology reasoning through a trained model, but is sensitive to changes in operating modes, grounding modes and other parameters, and the generalization ability of the model is insufficient, thus being difficult to guarantee the adaptability and robustness of online application.

[0005] However, in actual engineering applications, especially in zero sequence fault diagnosis devices that realize line selection and positioning based on zero sequence current signals, it is often impossible to obtain synchronous voltage signals or to widely deploy terminals, and therefore the above topology identification methods cannot be directly transplanted and applied. At present, there is still a lack of a topology identification method that only relies on zero sequence current information, can quickly adapt to changes in the topology of the distribution network, and has good fault pointing capability. If the directionality, transient amplitude distribution characteristics and other laws of the zero sequence current at the initial stage of the fault can be utilized to determine the actual structure of the distribution network in combination with the flow differences between lines, without relying on voltage measuring points and external equipment, efficient and accurate topology identification can be realized, and the application range, real-time performance and engineering practicability of the zero sequence fault diagnosis device can be greatly improved. SUMMARY

[0006] In view of the problems of insufficient precision, slow response speed and weak anti-interference ability in the single-phase grounding fault positioning of the existing power distribution network, the application provides a power distribution network topology identification and fault positioning method based on zero sequence current characteristics, which realizes rapid and accurate identification of single-phase grounding faults and accurate inference of the topology structure of the power distribution network at the time of fault occurrence by fusing the transient high-frequency information, steady-state phase and amplitude characteristics of the zero sequence current and combining the standardized configuration of the zero sequence current transformer of the ring network cabinet.

[0007] The technical solutions adopted by the application are as follows:

[0008] In one aspect, the application discloses a power distribution network topology identification and fault positioning method based on zero sequence current characteristics, which is applied to a power system power distribution network, the power distribution network includes multiple power distribution network lines and multiple ring network cabinets or nodes located on the power distribution network lines, the ring network cabinet (or node) is configured with a zero sequence current transformer, and the P1 end of the zero sequence current transformer is uniformly directed to the internal bus side of the ring network cabinet, and the P2 end is uniformly directed to the external line side, the method includes the following steps:

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

[0010] The acquisition adopts a high sampling rate (for example, not less than 12.8 kHz, preferably more than 50 kHz, and more preferably more than 100 kHz) and a high-precision analog-to-digital converter (for example, 16 bits or higher bit depth) to ensure sufficient capture of high-frequency transient components (for example, signals up to 10 kHz) of the zero sequence current. The acquired raw data is preprocessed by filtering, denoising and the like, and the accurate time stamps of each sampling point are recorded synchronously.

[0011] Step S1: monitoring the zero sequence current data, and capturing the initial zero sequence current response signal of each line after detecting the occurrence of a fault;

[0012] The zero sequence voltage and zero sequence current signals are continuously monitored, and when the amplitude or change amount (for example, differential value) of any signal exceeds a preset threshold value, it is determined that a single-phase grounding fault occurs. The zero sequence current transient signal within the first half wave or the first several cycles after the fault occurs is captured as the initial response signal of the fault.

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

[0014] High-frequency transient extraction method: use wavelet packet decomposition (WPT) to decompose the signal into multiple frequency bands, select 5kHz-20kHz high-frequency channel coefficients; extract the envelope line of each branch high-frequency zero sequence current, calculate the first steep point as FirstArrival Time (FAT);

[0015] Wave front steepness can be calculated by derivative extreme value:

[0016] ;

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

[0018] The accurate judgment of the zero sequence current flow direction specifically includes:

[0019] 1. Obtain two types of signals:

[0020] Based on the standardized configuration of the P1 end of the zero sequence current transformer in the ring network cabinet facing the internal bus side and the P2 end facing the external line side, combined with the steady-state phase characteristics extracted in step S2, accurately judge the actual flow direction of the zero sequence current of each distribution network line (judged by the phase of the current relative to the zero sequence voltage).

[0021] Direction criterion formula: ;

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

[0023] For discrete sampling signals u[n],i[n], the complex spectrum components at 50Hz can be calculated:

[0024] ;

[0025] ;

[0026] Where, fs is the sampling frequency (such as 12800Hz, 50000Hz, etc.); N is the window length (the number of samples); U50, 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 of the current relative to the voltage is:

[0031] ;

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

[0033] If < 0, current leads ahead of voltage.

[0034] 4. Determine whether each ring net cabinet incoming line, outgoing line and load line is on the main path of fault current:

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

[0036] Fault line criterion: If the steady-state phase angle of the zero sequence current of a certain distribution network line deviates significantly from about 90 degrees ahead (for example, close to in-phase or lagging, such as within the range of -90°~0°), and this phase characteristic is unique among all the distribution network lines, it is preliminarily determined that the line is a fault line, and the physical flow direction of the zero sequence current is "from the external line to the internal bus of the ring net cabinet" (i.e. "into" the ring net cabinet).

[0037] The direction of the current can also be determined by calculating the derivative of the transient current with respect to time at the moment of grounding. When the steady-state amplitude is too small to accurately determine the phase, the transient zero sequence current amplitudes of the ring net cabinet lines are compared, and the one with the largest amplitude is selected as the fault line.

[0038] Step S4: Based on the multi-dimensional characteristics and the physical flow direction, a fault line is identified from all lines according to a preset fault criterion;

[0039] The fault criterion includes that the zero sequence current of the fault line needs to meet at least two of the following conditions: a, the high-frequency transient waveform arrives earliest, the wave front has the largest steepness, and the transient amplitude is the largest, b, the steady-state phase angle of the fault line zero sequence current lags significantly behind the zero sequence voltage by about 90 degrees, and this phase characteristic is unique among all the distribution network lines, c, the flow direction of the fault zero sequence current is from the external line to the internal bus of the ring net cabinet.

[0040] Among the preliminarily screened lines, the distribution network line whose steady-state phase characteristic shows "significant deviation from about 90 degrees ahead" and has uniqueness is further screened out.

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

[0042] Consistency constraint criterion: used to suppress abnormal point interference, such as when multiple branches exist with simultaneous "inconsistent direction" signals, the transient maximum amplitude is adopted.

[0043] Robust judgment algorithm: when the steady-state phase is not available, the instantaneous change rate direction is used, and only the current change rate on the line closest to the fault point is opposite to the direction of other lines (single single-phase ground fault).

[0044] Step S5: based on the identification result of the fault line, the zero sequence current amplitude and flow direction information of each line, the real-time topology structure of the distribution network is derived and updated, and the fault point position is marked in the topology structure;

[0045] Graph algorithm to derive the topology structure: using the minimum spanning tree (MST), connected component analysis, or threshold pruning based method, the effective connection path of the current network is identified, and the "possible topology graph" of the network is derived. If further mark the directionality between nodes (such as current direction), a directed graph can be established.

[0046] Fault point accurate positioning: by analyzing the convergence path of the zero sequence current of other healthy lines, combined with the attenuation characteristics and delay information of high-frequency transient wave propagation, the fault line is highlighted on the distribution network topology graph, and the accurate fault point position is marked.

[0047] Step S6: fault location and topology output: combined with the identified network structure and current flow direction, further judge the fault branch attribution (whether it is a certain load or a connection line between two ring network cabinets), switch opening point (such as ring network cabinet opening point) and island section, etc. Generate fault diagnosis report and output visual topology graph.

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

[0049] Further, in the step S2, the high-frequency transient feature is extracted by wavelet packet transform or Hilbert-Huang transform, and the frequency band of interest is 5 kHz to 20 kHz; the high-frequency transient feature includes one or more of the first wave arrival time (FAT), the wave head steepness maximum value and the transient amplitude peak value.

[0050] Further, in the step S3, the physical flow direction is specifically calculated as the phase difference of the zero sequence current fundamental component relative to the zero sequence voltage fundamental component:

[0051] If the phase difference is in a first preset range (80°~100°), it is determined that the flow direction of the line zero sequence current is out of the node;

[0052] If the phase difference is in a second preset range (-90°~0°) and the phase characteristic is unique in all lines, it is determined that the flow direction of the line zero sequence current is into the node.

[0053] Further, in the step S4, if the physical flow directions of multiple lines are all determined to be into the bus, the line with the largest transient amplitude is selected as the fault line.

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

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

[0056] Further, in the step S5, the fault point positioning specifically includes: identifying the fault line on the topology graph, and estimating the specific position of the fault point along the line based on the transient wave head arrival time or attenuation characteristic of the fault line.

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

[0058] A data acquisition module is configured to perform the step S0 and acquire zero sequence current data of each node at high speed and synchronously.

[0059] A fault detection module is configured to perform the step S1 and monitor data and capture a fault initial response signal.

[0060] A feature extraction module is configured to perform the step S2 and extract multi-dimensional zero sequence current features from the response signal.

[0061] A flow direction judgment module is configured to perform the step S3 and judge the physical flow direction of the zero sequence current of each line based on the polarity configuration and the phase characteristic.

[0062] A fault identification module is configured to perform the step S4 and identify the fault line according to the fault criterion based on the multi-dimensional features and the flow direction.

[0063] A topology construction and positioning module is configured to perform the step S5 and derive the real-time topology structure and mark the fault point position.

[0064] On the other hand, a computer readable storage medium is also disclosed, and a computer program is stored on the computer readable storage medium, and the program is executed by a processor to implement the steps of the above method.

[0065] The above scheme has the following beneficial effects.

[0066] 1. High precision: By fusing the transient high-frequency characteristics of zero-sequence current and the steady-state phase and amplitude characteristics, especially using the unique criterion of steady-state phase deviation characteristics and high-frequency transient waveform analysis, the accuracy of single-phase ground fault line selection is effectively improved, especially for high-impedance ground faults that are difficult to handle by traditional methods.

[0067] 2. High speed: Using the fast response characteristics of transient signals and the first arrival time of high-frequency transient waves, the fault is preliminarily located within milliseconds or even microseconds, greatly shortening the fault handling time.

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

[0069] 4. Topology adaptability: Through the comprehensive judgment of current direction and multi-node information, it can better adapt to the complex ring network or radial topology structure of distribution network, without relying on complex impedance or admittance calculation.

[0070] 5. Intuitive results: Not only the fault line is given, but also the fault point is located on the topology graph, and the topology state at the time of fault occurrence is provided, which facilitates the rapid decision and isolation of faults by operation and maintenance personnel. BRIEF DESCRIPTION OF DRAWINGS

[0071] The accompanying drawings are used to provide a further understanding of the present application, and constitute a part of the specification, together with embodiments of the present application, to explain the present application, and do not constitute a limitation of the present application.

[0072] Figure 1 The overall flowchart of the method provided by the present application is shown in the figure;

[0073] Figure 2 The flowchart of fault occurrence detection and initial response capture in the present application is shown in the figure;

[0074] Figure 3 The flowchart of multi-dimensional zero-sequence current feature extraction in the present application is shown in the figure;

[0075] Figure 4 The logic diagram of zero-sequence current physical flow direction judgment and fault line identification in the present application is shown in the figure;

[0076] Figure 5 The schematic diagram of a typical 10kV ring network power distribution system is shown in the figure;

[0077] Figure 6 The configuration schematic diagram of a single ring network cabinet zero-sequence voltage and zero-sequence current transformer is shown in the figure.

[0078] Figure 6In the specific embodiments, 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 DESCRIPTION

[0079] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application; based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the present application.

[0080] In order to more clearly illustrate the technical solutions of the present application, the following describes the technical solutions of the present application in conjunction with Figures 1-6 and the typical ring network power distribution system grounding fault situation, the specific embodiments of a power distribution network topology identification and fault location method based on zero sequence current characteristics are described in detail.

[0081] I. System structure and data configuration:

[0082] In this embodiment, as shown in Figure 5 based on a typical 10kV ring network power supply distribution system, multiple ring main units (RMU1, RMU2, RMU3, RMU4) are provided in the system and are connected to each other through overhead lines or cables. As shown in Figure 6 each ring main unit includes two incoming and outgoing line interfaces and one load line, and zero sequence current transformers (ZCT) are uniformly installed on the incoming and outgoing lines and the load side, and current transformers (ZPT) that can detect zero sequence voltage are installed on the bus, the polarity of which is uniformly configured as P1 pointing to the internal bus of the ring main unit and P2 pointing to the external line.

[0083] The zero sequence current signals collected by each ZCT are synchronously sampled by a high-speed collection terminal, the sampling frequency is not less than 50kHz, and the sampling data is uploaded to the central fault diagnosis unit through industrial Ethernet. The system does not rely on external time synchronization such as GPS or PTP, but only guarantees relative synchronization of data sampling.

[0084] II. Fault situation setting:

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

[0086] III. Implementation details of each step:

[0087] Step S0, collection and preprocessing of zero sequence current data:

[0088] The system synchronously collects the zero sequence current data of each ZCT at a sampling rate of 50 kHz, and records the corresponding sampling point number. After band-pass filtering (2 kHz~20 kHz) to remove power frequency and noise, the collected data is stored in matrix form for subsequent analysis.

[0089] Step S1, fault detection and initial response capture:

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

[0091] Step S2, feature extraction:

[0092] For each branch of zero sequence current signal, the following method is used to extract features:

[0093] 2.1 First wave maximum amplitude Ai: directly take the absolute value maximum point:

[0094] ;

[0095] 2.2 Wave head steepness ki: use first-order difference to extract the maximum rate of change:

[0096] ;

[0097] 2.3 FAT (optional): if the system has time capability, use high-frequency wavelet packet envelope to extract the first rising point of the signal wave head:

[0098] These features are used to preliminarily distinguish the "strongest response" line, i.e. the branch closest to the fault point.

[0099] Step S3, current direction and phase analysis:

[0100] Perform window function weighted FFT on each branch sampling signal to extract the fundamental frequency phase:

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

[0102] ;

[0103] If ≈90°, it means a healthy line, and the current flows out of the bus;

[0104] If Significantly deviates from this range (such as lag or reverse phase), it is a fault inflow line.

[0105] Step S4, Fault Branch Determination:

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

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

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

[0109] 3. If the amplitude and phase characteristics match, it is determined as the fault branch;

[0110] 4. If there are multiple branches that meet the inflow condition, 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 has the largest zero-sequence current amplitude (5.1A), the largest wave steepness (dI / dt=2800A / s), and the phase angle is -60°, while the other branches have a phase angle of +88°. Therefore, it is uniquely determined that the RMU3 load branch is the fault line.

[0112] Table 1: Specific implementation case data response:

[0113] Step S5, Topology Identification:

[0114] The system abstracts all lines into a graph G(V, E), where:

[0115] V is each ring network cabinet; E is 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.

[0116] Based on this, the system constructs the effective network topology graph at the current time through the minimum spanning tree (MST) or connected subgraph analysis, combined with the fault flow direction constraint and non-zero response line. At the same time, the fault branch path is highlighted and the fault point is marked as the RMU3 load end.

[0117] Inference results:

[0118] A Fault line: RMU3 outgoing line;

[0119] B Topology state: RMU1-RMU2 connected, RMU2-RMU3 connected, RUM3-RUM4 disconnected;

[0120] C Fault point location: downstream of RMU3 outgoing line, system is a single-source open-loop structure.

[0121] Step S6, Visual Output:

[0122] The system generates the following visual output content:

[0123] 1) Fault branch number and ring network cabinet name;

[0124] 2) Zero sequence current amplitude, wave head slope, and direction identification of each branch;

[0125] 3) Current topological structure diagram;

[0126] 4) Geographic location of fault point (may be combined with GIS or line number);

[0127] 5) Fault report document (including timestamp, data screenshot, atlas, etc.).

[0128] The embodiment does not need precise time synchronization such as GPS synchronization, and can determine topology through amplitude + direction; is suitable for small current systems, and is suitable for 35 kV and below distribution networks; only uses zero sequence voltage and zero sequence current signals, does not need to add ring network cabinet switch quantity sampling, and is suitable for existing ring network cabinets; has strong robustness, and can adapt to short-time disturbance, data error, and other working conditions; and is suitable for open-loop operation or multi-opening operation mode.

[0129] It should be noted that, in the present text, relational terms such as first and second are used merely to distinguish one entity or action from another entity or action, without necessarily requiring or implying that there is any such actual relationship or order between these entities or actions. Moreover, the terms "comprises", "comprising", or any other variant thereof are intended to cover non-exclusive inclusions, so that a process, method, article, or apparatus that comprises a list of elements does not only include those elements, but also includes other elements not explicitly listed, or other elements inherent to such a process, method, article, or apparatus.

[0130] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the application, the scope of which is defined by the following claims and their equivalents.

[0131] The above describes the present application and its embodiments, which are not restrictive, and the drawings only show one of the embodiments of the present application, and the actual structure is not limited thereto. In general, if a person of ordinary skill in the art is inspired thereby, without departing from the principles and spirit of the present application, without creative design, similar structural modes and embodiments to the technical solution are not creative, and all should belong to the protection scope of the present application.

Claims

1. A distribution network topology identification and fault location method based on zero-sequence current characteristics, applied to a power system distribution network, wherein the distribution network includes multiple distribution lines and multiple ring network cabinets or nodes located on the distribution lines, wherein the ring network cabinets or nodes are configured with zero-sequence current transformers, and the P1 end of the zero-sequence current transformer is uniformly oriented toward the internal bus side of the ring network cabinet, and the P2 end is uniformly oriented toward the external line side, characterized in that: The method comprises the following steps: Step S0: synchronously collecting instantaneous zero-sequence current data of each node in the distribution network at high speed; Step S1: monitoring the instantaneous value data of zero-sequence current, and after detecting the occurrence of a fault, capturing the initial zero-sequence current response signal of each line; Step S2: extracting multi-dimensional features of the zero-sequence current of each line from the initial zero-sequence current response signal of the fault, wherein the multi-dimensional features include high-frequency transient features, steady-state phase features, and steady-state amplitude features; Step S3: determining the physical flow direction of the zero-sequence current of each distribution network line based on the uniform polarity configuration of the zero-sequence current transformer and the steady-state phase characteristics; Step S4: Combining the multi-dimensional features and the physical flow direction, and according to a preset fault criterion, identifying the faulty line from all lines; The fault judgment criteria include: the zero-sequence current of the fault line must simultaneously meet at least two of the following conditions: a) the zero-sequence current high-frequency transient waveform arrives earliest, has the steepest wave front, and has the largest transient amplitude; b) the steady-state phase angle of the zero-sequence current of the fault line significantly deviates from the zero-sequence voltage by 90 degrees, and this phase characteristic is unique among all the distribution network lines; c) the direction of the fault zero-sequence current is from the external line to the internal busbar of the ring main unit; Step S5: Based on the identification result of the fault 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 fault point location in the topology.

2. A method for distribution network topology identification and fault location based on zero-sequence current characteristics according to claim 1, characterized in that: In the step S0, data is collected using an analog-to-digital converter with a sampling rate of not less than 50 kHz and a precision of not less than 16 bits to capture the high-frequency transient component 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, and the frequency band of interest is 5kHz to 20kHz; the high-frequency transient features include one or more of the first wave arrival time, the maximum wave head steepness and the transient amplitude peak value.

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, the physical flow direction is determined by calculating the phase difference between the fundamental component of the zero-sequence current of each line and the fundamental component of the zero-sequence voltage: If the phase difference is within a first preset range (80° to 100°), it is determined that the direction of the zero-sequence current of the line is flowing out of the node; If the phase difference is within a second preset range (-90° to 0°) and the phase characteristic is unique among all lines, it is determined that the flow direction of the zero-sequence current of the line is to flow into the 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 directions of multiple lines are all determined to be flowing into the bus, the line with the largest transient amplitude is selected as the fault 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, a graph theory algorithm is used to derive a real-time topology structure, wherein the graph theory algorithm includes a minimum spanning tree algorithm or a connected component analysis algorithm; The fault point location is estimated by analyzing the convergence path of the zero-sequence current of the healthy line and combining the propagation attenuation characteristics and arrival delay information of the high-frequency transient wave.

7. 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 includes: marking the fault line on the topological structure, and estimating the specific position of the fault point along the line based on the transient wave front arrival time or attenuation characteristics of the fault line.

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

9. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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