Out-phase two-point grounding fault handling method and system for small-current grounding system

Abstract

The invention belongs to the technical field of power distribution network protection and control, and particularly relates to a low-current grounding system out-of-phase two-point grounding fault handling method and system. The method comprises the following steps: acquiring and processing real-time data to obtain high-precision wide-area synchronous sampling data; based on high-precision wide-area synchronous sampling data, double-criterion starting and distributed cooperative verification are adopted, and a real grounding fault is judged; layered fault identification is carried out for an out-of-phase two-point grounding fault; according to a fault identification result, differential rapid processing is carried out, and a fault section is cut in a minimized mode. Based on a distribution network distributed protection framework, a hierarchical decision-making mechanism of local edge calculation and adjacent information interaction is established, a terminal edge calculation module is used for processing data in real time, the Beidou timing technology is combined to guarantee sampling synchronism, the fault detection sensitivity and accuracy are greatly improved, the out-of-phase two-point grounding fault detection and disposal problem is solved, and the fault detection efficiency is improved. The power failure range is reduced, and the power distribution network power supply reliability is improved.

Description

Technical Field

[0001] This invention belongs to the field of power distribution network protection and control technology, and in particular relates to a method and system for handling two-point grounding faults in a low-current grounding system. Background Technology

[0002] Low-current grounding systems are widely used in medium-voltage distribution networks due to their advantages of small grounding current during single-phase grounding faults and the ability to maintain power supply for short periods. However, when a metallic single-phase grounding fault occurs, the phase voltage rises to the line voltage level, easily triggering intermittent arcing or insulation breakdown, which can then evolve into a two-point grounding fault in a different phase. This type of fault results in a multi-source superposition characteristic of the zero-sequence current distribution. Traditional single-ended quantitative protection devices cannot distinguish the coupling effects of fault characteristics, leading to serious risks of misjudgment and missed detection. Statistics show that two-point grounding faults in different phases account for approximately 3%-5% of all faults in distribution networks, but the resulting power outage losses account for as much as 15%, seriously threatening the safe operation of the power grid.

[0003] In existing technologies, single-phase grounding fault detection methods, such as the zero-sequence power direction method, transient energy method, and zero-sequence admittance method, are relatively mature, but they generally lack the ability to detect and dynamically respond to secondary grounding faults. Furthermore, existing centralized protection systems in distribution networks rely on master station decisions, and communication delays make it difficult to meet the requirements for rapid fault isolation. Simultaneously, two-point grounding faults may trigger multiple activations of protection devices, while traditional differential protection systems lack sufficient timing accuracy, resulting in limited effectiveness in complex distribution networks and posing a risk of cascading zero-sequence protection activation by the main transformer or grounding transformer. Currently, distributed protection architectures for distribution networks have been proposed, providing new solutions to the problems of reliance on master station decisions and timing coordination; however, most distributed protection schemes still focus on handling single-line, single-point faults.

[0004] The current technological bottlenecks are mainly reflected in three aspects:

[0005] First, existing protection devices do not make full use of multi-point transient information, resulting in low fault identification accuracy;

[0006] Secondly, the lack of collaborative judgment of two-point grounding faults in different phases of power distribution lines based on distributed architecture makes it impossible to dynamically optimize tripping strategies.

[0007] Third, traditional solutions are sensitive to communication latency and data synchronization accuracy, and lack robustness in complex power distribution networks.

[0008] Therefore, in order to overcome the technical barriers in handling out-of-phase two-point grounding faults in low-current grounding systems, it is urgent to develop a new solution that integrates high-precision synchronous measurement, multi-point feature identification, and dynamic weight evaluation. Summary of the Invention

[0009] To address the shortcomings of the existing technologies, this invention provides a method and system for handling two-point grounding faults in a low-current grounding system. Its purpose is to quickly and effectively identify and locate two-point grounding faults in different locations and phases, achieving differentiated and rapid handling of two-point grounding faults in low-current grounding systems that are both in-line and out-of-line.

[0010] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0011] A method for handling out-of-phase two-point grounding faults in a low-current grounding system includes the following steps:

[0012] Real-time data acquisition and processing yield high-precision, wide-area synchronous sampling data;

[0013] Based on high-precision wide-area synchronous sampling data, dual-criteria initiation and distributed collaborative verification are used to determine the actual grounding fault.

[0014] For two-point grounding faults of different phases, hierarchical fault identification is performed;

[0015] Based on the fault identification results, differentiated and rapid handling is carried out to minimize the removal of faulty sections.

[0016] Furthermore, the real-time data acquisition and processing to obtain high-precision wide-area synchronous sampling data involves deploying distributed protection terminals at key nodes of the distribution network, using wide-area synchronous phasor measurement technology to collect voltage and current data at various points on the line, and preprocessing the data to obtain high-precision wide-area synchronous sampling data. The wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, ensuring that the time deviation of the sampling data from all distributed protection terminals is less than 1μs. The synchronous sampling frequency for collecting voltage and current data at various points on the line is 12.8KHz. The data preprocessing method employs a wavelet threshold denoising algorithm, selecting the db4 wavelet basis function for 4-level decomposition, and processing the scale coefficients by improving the threshold function.

[0017] Furthermore, the method of determining the actual grounding fault based on high-precision wide-area synchronous sampling data and using dual-criteria activation and distributed collaborative verification is to use steady-state and transient grounding protection activation dual criteria. When either criterion is met, the distributed collaborative verification of adjacent terminals is activated to determine the actual grounding fault.

[0018] Zero-sequence voltage amplitude and zero-sequence voltage change energy are selected as grounding protection activation criteria. When either criterion reaches a set value, the grounding protection is activated, i.e.:

[0019] U0>U 0set

[0020]

[0021] Where U0 is the zero-sequence voltage amplitude, U 0set Let u0 be the zero-sequence voltage setpoint, k be the sampling point number, E0 be the zero-sequence voltage change energy, u0[k] be the instantaneous voltage value at the kth sampling point, and E0 be the zero-sequence voltage change energy. 0set The zero-sequence voltage change energy is a set value, and N is the number of sampling points within the sampling interval;

[0022] The distributed collaborative verification eliminates the influence of single-point single-data error by synchronous data interaction and feature comparison between adjacent distributed protection terminals on the same line; when the grounding protection of the upstream terminal of a certain section is activated and the transient power grounding discrimination condition is met, if the collected zero-sequence current transient waveform shows a high degree of similarity and is significantly different from the waveform collected by the downstream terminal, it is determined that a real single-phase grounding fault has occurred in the section.

[0023] Set waveform similarity threshold H set As a criterion for distributed collaborative verification, the similarity H of the zero-sequence current transient waveform is calculated between adjacent terminals. When the H values ​​of all upstream terminals in a certain segment are below a threshold, i.e., H... 1,2,...,j <0.2H set Its downstream terminals are higher than the threshold H j+1 >H set At that time, determine the actual grounding fault and locate the faulty section;

[0024] Based on high-precision wide-area synchronous sampling data, the Hausdorff distance algorithm is selected to quantify the similarity of zero-sequence current transient waveforms. The principle of the Hausdorff distance algorithm is as follows: for distributed protection terminals m and n on the same line, 1 / 4 of the power frequency cycle after the fault is extracted as the data window, and the set of zero-sequence current sampling points for terminal m is M = {i 01 , ..., i 0m ...}, the set of terminal n zero-sequence current sampling points is N = {i 01 , ..., i 0n The Hausdorff distance calculation formula for the zero-sequence currents at terminals m and n is as follows:

[0025] H(M,N)=max(h(M,N),h(N,M))

[0026]

[0027] In the above formula: ||i 0m -i 0n ||、||i 0n -i 0m || represents the Euclidean distance between any two points in the sets M and N of zero-sequence current sampling points, and h(M,N) is the single-phase Hausdorff distance from set M to set N, representing the distance between any point i in set M. 0mFirst, calculate the Euclidean distance between it and all sampling points in set N, and take the minimum value of the distance. Then, take the maximum value of this minimum distance in set M. The same applies to h(N,M). H(M,N) can be used to measure the matching degree of the zero-sequence current waveforms of adjacent distributed protection terminals. The value range is [0,1]. When H(M,N) is closer to 0, the difference between the two waveforms is smaller. When it is closer to 1, the difference between the two waveforms is larger.

[0028] Furthermore, for the two-point grounding fault of different phases, hierarchical fault identification is performed. This involves cyclically monitoring the transient component of the zero-sequence current in the system, and combining this with fault characteristic information exchange based on horizontal and vertical end-to-end communication to distinguish between in-line and out-of-line fault types, including:

[0029] Step 3.1 Circularly monitor the transient component of the zero-sequence current in the system. When the amplitude is higher than the threshold, initiate the analysis of out-of-phase two-point grounding.

[0030] Step 3.2 Identification of co-line non-phase faults: If non-phase grounding fault characteristics appear on a line that has already been grounded, it is determined to be a co-line non-phase grounding fault, and the fault section is determined through lateral communication;

[0031] Choosing the zero-sequence current transient energy as a fault characteristic quantity, the terminal T j The transient zero-order energy is denoted as F. 0j Defined as:

[0032]

[0033] Where Δt is the sampling interval, and the number of sampling points within the interval is N, i 0j [k] represents terminal T j The instantaneous value of the zero-sequence current at the kth sampling point, u 0j [k] represents terminal T j The instantaneous value of zero-sequence voltage at the kth sampling point; the criterion has directional characteristics, and the positive direction of the current is defined as the line pointing to the bus. When the fault occurs in the downstream section of the terminal, the zero-sequence energy is positive.

[0034] Set the energy threshold to F. set The fault location criterion is: terminal T j Satisfy |F 0j |>F set Its upstream terminal T j-1 Satisfy |F 0,j-1 |>F set Its downstream adjacent terminal T j+1 Fault characteristic quantity | F 0,j+1 |<0.2F set And F 0,j+1 If the value is less than 0 and the above criteria are met simultaneously, then the ground fault section furthest from the power supply side is located at terminal T. j With terminal Tj_+1 between;

[0035] Step 3.3 Identification of cross-line and cross-phase faults: The terminals at the beginning of different lines exchange fault flag bits and fault characteristic quantities through longitudinal communication. When two lines simultaneously meet the fault characteristic conditions, it is determined to be a cross-line fault.

[0036] When the line detects zero-sequence current transient energy and it is greater than the energy threshold, the flag is set to 1, and Flag = 1 is recorded. When the zero-sequence current transient energy is positive, P = 1 is recorded, and when it is negative, P = -1 is recorded. The terminals at the beginning of different lines exchange the fault flag bits Flag and P through longitudinal communication. When both lines simultaneously satisfy Flag1 = 1 and Flag2 = 1, and P1·P2 = -1, it is determined to be a cross-line phase fault.

[0037] Furthermore, the differentiated rapid handling based on the fault identification results, minimizing the removal of faulty sections, specifically involves implementing selective fault handling strategies for co-line out-of-phase two-point grounding faults and cross-line out-of-phase two-point grounding faults, minimizing the removal of faulty sections, including:

[0038] Step 4.1 Handling faults with different phases on the same line;

[0039] If the fault point is on the main line and branch line, a tiered tripping strategy is adopted to prioritize the disconnection of the fault section on the branch line; if the grounding point is on the main line, the fault section far away from the power supply side is prioritized to be disconnected through lateral information transmission.

[0040] Step 4.2 Handling of cross-phase faults;

[0041] A multi-dimensional weighted evaluation model is constructed, and the line head-end terminal evaluates the protection tripping priority through local edge computing and cuts off the line with higher priority.

[0042] Based on the analytic hierarchy process (AHP), the tripping priority index is defined as follows:

[0043] P i =αS 位置 +βS 用户 +δS 负载率 +γS 能量

[0044] Among them, S 位置 Location indicates the tripping index of the topology where the terminal is located, S 用户 S represents the user importance tripping index. 负载率 S represents the line load factor tripping index. 能量 The normalized zero-order transient energy tripping index is represented by α, β, δ, and γ, which are weighting coefficients.

[0045] The fault point protection terminal calculates the tripping priority index at the local edge and compares them through longitudinal end-to-end communication at the first terminal, prioritizing the clearing of fault sections with higher priority indices.

[0046] Step 4.3 Retain the remaining grounding points and continue operation, continuously monitor the transient component of zero-sequence current, and push operation and maintenance alarms synchronously.

[0047] A system for handling out-of-phase two-point grounding faults in a low-current grounding system includes:

[0048] Distribution network distributed protection architecture: Each outgoing line of the same bus contains multiple distribution network distributed protection terminals;

[0049] The distributed protection terminals for distribution networks include: head-end terminals, main line terminals, and branch line terminals;

[0050] 5G end-to-end communication is used for horizontal information transmission between adjacent terminals on the same line, while fiber optic communication is used for vertical information transmission between terminals at the beginning of different lines.

[0051] Furthermore, the hardware architecture of the distributed protection terminal for the power distribution network consists of a power supply module, a high-precision measurement module, an edge computing module, and a communication module. The high-precision measurement module is connected to the edge computing module, and the edge computing module is bidirectionally connected to the communication module.

[0052] Furthermore, the power module has a rated operating voltage of AC 220V and includes battery power supply, PT power supply and emergency power supply methods.

[0053] The high-precision measurement module includes a BeiDou / GPS clock timing module, a data acquisition unit, an A / D conversion unit, and a phasor measurement unit. The BeiDou / GPS clock timing module is connected to the phasor measurement unit, the data acquisition unit is connected to the A / D conversion unit, the A / D conversion unit is connected to the phasor measurement unit, and the phasor measurement unit is connected to the data processing layer in the edge computing module.

[0054] The communication module integrates two physical channels: 5G wireless communication and fiber optic communication, and fully supports the IEC 60870-5-101 / 104 power communication protocol.

[0055] The edge computing module includes a data processing layer and an intelligent computing layer.

[0056] A computer device includes a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of any of the methods for handling out-of-phase two-point grounding faults in a low-current grounding system.

[0057] A computer storage medium storing a computer program, wherein when the computer program is executed by a processor, the steps of any of the methods for handling out-of-phase two-point grounding faults in a low-current grounding system are described above.

[0058] The present invention has the following beneficial effects and advantages:

[0059] This invention, based on a distributed protection architecture for distribution networks, establishes a hierarchical decision-making mechanism of "local edge computing + neighboring information interaction." Compared to traditional centralized solutions that rely on master station decision-making and suffer from limitations in hierarchical coordination, this invention utilizes terminal edge computing modules to process data in real time and combines BeiDou timing technology to ensure sampling synchronization, significantly improving the sensitivity and accuracy of fault detection. This invention solves the problem of detecting and handling out-of-phase two-point grounding faults, which helps reduce the scope of power outages and improve the reliability of power supply in distribution networks.

[0060] To address the issues of inaccurate identification and ambiguous positioning caused by existing grounding protection devices relying on single-ended electrical quantities, this invention proposes a "dual-criteria start-up + distributed collaborative verification" mechanism. This mechanism uses horizontal communication to compare waveform features of adjacent terminals, eliminating the influence of single-point measurement errors and improving the accuracy of grounding fault identification in low-current systems.

[0061] This invention also proposes a collaborative judgment and differentiated rapid handling strategy for two-point grounding faults in different phases of a low-current grounding system. For two-point grounding faults in different phases on the same line, a tiered and lateral positioning strategy is adopted to prioritize the removal of branch or remote faults. For two-point grounding faults in different phases on different lines, a multi-dimensional weight evaluation model is constructed to first remove the line with higher priority, minimize the removal of fault sections, and limit the power outage range. Attached Figure Description

[0062] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0063] Figure 1 This is a flowchart of a method for handling two-point grounding faults in a low-current grounding system according to the present invention.

[0064] Figure 2 This is a schematic diagram of a low-current grounding system for handling two-point grounding faults in different phases according to the present invention.

[0065] Figure 3 This is a schematic diagram illustrating the handling of two-point grounding faults in the same line but different phases according to an embodiment of the present invention;

[0066] Figure 4 This is a schematic diagram illustrating the handling of two-point grounding faults in different phases and along different lines according to an embodiment of the present invention;

[0067] Figure 5 This is a schematic diagram of hierarchical analysis in an embodiment of the present invention;

[0068] Figure 6 This is a schematic diagram of the hardware architecture of the distributed protection terminal for power distribution networks of the present invention. Detailed Implementation

[0069] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.

[0070] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein, and therefore the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0071] The following reference Figures 1-6 The technical solutions of some embodiments of the present invention are described below.

[0072] Example 1

[0073] This invention provides an embodiment of a method for handling two-point grounding faults in a low-current grounding system. For example... Figure 1 As shown, Figure 1 This is a flowchart of a method for handling two-point grounding faults in a low-current grounding system according to the present invention.

[0074] A method for handling out-of-phase two-point grounding faults in a low-current grounding system includes the following steps:

[0075] Step 1. Real-time data acquisition and processing. Distributed protection terminals are deployed at key nodes of the distribution network. Wide-area synchronous phasor measurement technology is used to collect voltage and current data at various points on the line. The data is preprocessed to obtain high-precision wide-area synchronous sampling data.

[0076] The wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, and the time deviation of the sampling data of all distributed protection terminals is less than 1μs.

[0077] The synchronous sampling frequency for voltage and current data at each point on the acquisition line is 12.8 kHz.

[0078] The sampled data is accompanied by precise time stamps for subsequent waveform alignment and feature comparison.

[0079] The data preprocessing method employs a wavelet threshold denoising algorithm, selects the db4 wavelet basis function for 4-level decomposition, and improves the threshold function to process the coefficients at each scale, effectively suppressing measurement noise while preserving the transient characteristics of the fault.

[0080] Step 2. Based on high-precision wide-area synchronous sampling data, a dual-criteria activation and distributed collaborative verification are used to determine the actual grounding fault. Dual criteria for steady-state and transient grounding protection activation are employed. When either criterion is met, distributed collaborative verification of adjacent terminals is initiated to determine the actual grounding fault.

[0081] Based on the principle of sensitive grounding protection activation, the zero-sequence voltage amplitude and zero-sequence voltage change energy are selected as grounding protection activation criteria. When either criterion reaches a set value, the grounding protection is activated, i.e.:

[0082] U0>U 0set

[0083]

[0084] Where U0 is the zero-sequence voltage amplitude, U 0set Let u0 be the zero-sequence voltage setpoint, k be the sampling point number, E0 be the zero-sequence voltage change energy, u0[k] be the instantaneous voltage value at the kth sampling point, and E0 be the zero-sequence voltage change energy. 0set The zero-sequence voltage change energy is a fixed value, and N is the number of sampling points within the sampling interval.

[0085] The distributed collaborative verification eliminates the impact of single-point, single-data errors through synchronous data interaction and feature comparison between adjacent distributed protection terminals on the same line. Specifically, when the grounding protection of an upstream terminal in a certain section is activated and meets the transient power grounding discrimination condition, if the acquired zero-sequence current transient waveform shows high similarity and significantly differs from the waveform acquired by the downstream terminal, it can be determined that a real single-phase grounding fault has occurred in that section. A waveform similarity threshold H is set. set As a criterion for distributed collaborative verification, the similarity H of the zero-sequence current transient waveform is calculated between adjacent terminals. When the H values ​​of all upstream terminals in a certain segment are below a threshold, i.e., H... 1,2,...,j <0.2H set Its downstream terminals are higher than the threshold H j+1 >H set In this way, a real grounding fault can be identified and the faulty section can be located.

[0086] Based on the high-precision wide-area synchronous sampling data in step 1, the Hausdorff distance algorithm is selected to quantify the similarity of the zero-sequence current transient waveform. The specific principle of the Hausdorff distance algorithm is as follows: for distributed protection terminals m and n on the same line, one-quarter of the power frequency cycle after the fault is extracted as a data window, and the set of zero-sequence current sampling points for terminal m is M = {i...} 01 , ..., i 0m ...}, the set of terminal n zero-sequence current sampling points is N = {i 01 , ..., i 0n The Hausdorff distance calculation formula for the zero-sequence currents at terminals m and n is as follows:

[0087] H(M,N)=max(h(M,N),h(N,M))

[0088]

[0089] In the above formula: ||i 0m -i 0n ||、||i 0n -i 0m || represents the Euclidean distance between any two points in the sets M and N of zero-sequence current sampling points, and h(M,N) is the single-phase Hausdorff distance from set M to set N, representing the distance between any point i in set M. 0m First, calculate the Euclidean distance between the sampled points and all sampling points in set N, and take the minimum distance among them. Finally, take the maximum value of this minimum distance in set M. The same applies to h(N,M). H(M,N) can be used to measure the matching degree of the zero-sequence current waveforms of adjacent distributed protection terminals. The value range is [0,1]. The closer H(M,N) is to 0, the smaller the difference between the two waveforms. The closer it is to 1, the greater the difference between the two waveforms.

[0090] Step 3. Layered Fault Identification. The system's zero-sequence current transient component is monitored cyclically. Combined with fault characteristic information exchange based on horizontal and vertical end-to-end communication, the system distinguishes between in-line out-of-phase and out-of-line out-of-phase fault types. This specifically includes the following steps:

[0091] Step 3.1 Circularly monitor the transient component of the zero-sequence current of the system. When the amplitude is higher than the threshold, initiate the analysis of out-of-phase two-point grounding.

[0092] Step 3.2 Identification of co-line non-phase faults: If non-phase grounding fault characteristics appear on a line that has already been grounded, it is determined to be a co-line non-phase grounding fault, and the fault section is determined through lateral communication.

[0093] Furthermore, in step 3.2, the zero-sequence current transient energy is selected as the fault characteristic quantity, and the terminal T... j The transient zero-order energy is denoted as F. 0j Defined as:

[0094]

[0095] Where Δt is the sampling interval, and the number of sampling points within the interval is N, i 0j [k] represents terminal T j The instantaneous value of the zero-sequence current at the kth sampling point, u 0j [k] represents terminal T j The instantaneous value of the zero-sequence voltage at the k-th sampling point. This criterion has a directional characteristic, stipulating that the positive direction of the current is from the line to the busbar, and the zero-sequence energy is positive when the fault occurs in the downstream section of the terminal.

[0096] Set the energy threshold to F. set The fault location criterion is: terminal T j Satisfy |F 0j |>F set Its upstream terminal T j-1 Satisfy |F 0,j-1 |>F set Its downstream adjacent terminal T j+1 Fault characteristic quantity | F 0,j+1 |<0.2F set And F 0,j+1 If the value is less than 0 and the above criteria are met simultaneously, then the ground fault section furthest from the power supply side is located at terminal T. j With terminal T j_+1 between.

[0097] Step 3.3 Identification of cross-line and cross-phase faults: The terminals at the beginning of different lines exchange fault flag bits and fault characteristic quantities through longitudinal communication. When two lines simultaneously meet the fault characteristic conditions, it is determined to be a cross-line fault.

[0098] Further, in step 3.3, when the line detects zero-sequence current transient energy and it is greater than the energy threshold, the flag bit is set to 1, and Flag = 1; when the zero-sequence current transient energy is positive, P = 1, and when it is negative, P = -1. The terminals at the beginning of different lines exchange fault flag bits Flag and P through longitudinal communication. When both lines simultaneously satisfy Flag1 = 1 and Flag2 = 1; and P1·P2 = -1, it is determined to be a cross-line, cross-phase fault.

[0099] Step 4. Differentiated Rapid Handling. Implement selective fault handling strategies for two-point grounding faults of different phases on the same line and different phases on different lines, minimizing the isolation of the faulty section. This includes the following steps:

[0100] Step 4.1 Handling faults of different phases on the same line. If the fault point is on the main line and the branch line, the fault section of the branch line should be disconnected first; if the grounding point is on the main line, the fault section away from the power source should be disconnected first.

[0101] When a fault occurs on the main line and branch lines, a tiered tripping strategy is adopted. The tripping time of the branch line is set to 0.2s, and the tripping time of the main line is set to 0.5s. After the branch switch is cut off first, the cross-phase two-point grounding protection of the main line is blocked.

[0102] When all faults occur on the main line, the grounding fault points located far from the power supply side in step 3.2 are preferentially cut off through horizontal information transmission.

[0103] Step 4.2 Handling of cross-line and cross-phase faults. Construct a multi-dimensional weighted evaluation model. The line's head-end terminal evaluates the protection tripping priority through local edge computing and disconnects the line with the higher priority.

[0104] Based on the analytic hierarchy process (AHP), the tripping priority index is defined as follows:

[0105] P i =αS 位置 +βS 用户 +δS 负载率 +γS 能量

[0106] Among them, S 位置 Location indicates the tripping index of the terminal's topology location; for example, the tripping index is higher for branch lines and switches crossing forest areas; S 用户 This indicates the tripping index based on user importance; for example, important users such as hospitals have a lower tripping index. 负载率 This represents the line load factor tripping index; the higher the load, the smaller the tripping index. (S) 能量 The normalized zero-sequence transient energy tripping index is represented by α, β, δ, and γ, which represent weighting coefficients. The lower the transient energy, the smaller the tripping index.

[0107] Among them, the fault point protection terminal calculates the tripping priority index at the local edge and compares it through longitudinal end-to-end communication at the first terminal, prioritizing the removal of fault sections with higher priority indices.

[0108] Step 4.3 Retain the remaining grounding points and continue operation, continuously monitor the transient component of zero-sequence current, and push operation and maintenance alarms synchronously.

[0109] Example 2

[0110] This invention provides another embodiment, which is a method for handling out-of-phase two-point grounding faults in a low-current grounding system. The wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, with the time deviation range of all distributed protection terminal sampling data being 0.5μs-5μs.

[0111] The recommended range for the synchronous sampling frequency of voltage and current data at various points on the acquisition line is 10KHz-20KHz, which needs to be selected according to the transient characteristic frequency of the fault.

[0112] The data preprocessing method employs a wavelet threshold denoising algorithm, selecting db4-db8 wavelet basis functions for 3-6 level decomposition, chosen according to real-time requirements and transient accuracy needs. By improving the threshold function to process coefficients at each scale, measurement noise is effectively suppressed while preserving transient fault characteristics.

[0113] Everything else is the same as in Example 1.

[0114] Example 3

[0115] This invention provides another embodiment, which is a method for handling two-point grounding faults in a low-current grounding system. For example... Figure 1 As shown, Figure 1 This is a flowchart of a method for handling two-point grounding faults in a low-current grounding system according to the present invention.

[0116] When two points of grounding occur in the same line but different phases, a method for handling two-point grounding faults in a low-current grounding system includes the following steps:

[0117] Step 1. Real-time data acquisition and processing: Deploy distributed protection terminals at key nodes of the distribution network, use wide-area synchronous phasor measurement technology to collect voltage and current data at various points on the line, preprocess the data to obtain high-precision wide-area synchronous sampling data.

[0118] Preferably, in step 1, the wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, and the time deviation of the sampling data of all distributed protection terminals is less than 1μs.

[0119] Preferably, in step 1, the synchronous sampling frequency for collecting voltage and current data at various points on the line is 12.8 kHz.

[0120] Preferably, in step 1, the data preprocessing method uses a wavelet thresholding denoising algorithm, selects the db4 wavelet basis function for 4-level decomposition, and processes the scale coefficients by improving the threshold function.

[0121] Specifically, such as Figure 3 As shown, Figure 3 This is a schematic diagram illustrating the handling of two-point grounding faults in different phases on the same line according to an embodiment of the present invention. In a certain 10kV distribution network, distributed protection terminals FTU1, FTU2, FTU3, FTU4, and FTU5 are installed on the main switches FD21, FD22, and FD23 and branch switches FZ21 and FZ22 of line L2.

[0122] exist Figure 3 In the middle, a phase A ground fault occurred at point K1 on line L2.

[0123] Step 2. Use both steady-state and transient grounding protection activation criteria. When either criterion is met, initiate distributed collaborative verification of adjacent terminals to determine the actual grounding fault.

[0124] Preferably, in step 2, the zero-sequence voltage amplitude and the zero-sequence voltage change energy are selected as grounding protection activation criteria. When either criterion reaches a set value, the grounding protection is activated.

[0125] U0>U 0set

[0126]

[0127] Where U0 is the zero-sequence voltage amplitude, U 0set Let u0 be the zero-sequence voltage setpoint, k be the sampling point number, E0 be the zero-sequence voltage change energy, u0[k] be the instantaneous voltage value at the kth sampling point, and E0 be the zero-sequence voltage change energy. 0set The zero-sequence voltage change energy is a fixed value, and N is the number of sampling points within a certain time window.

[0128] Preferably, in step 2, the distributed collaborative verification eliminates the influence of single-point, single-data errors through synchronous data interaction and feature comparison between adjacent distributed protection terminals on the same line. Specifically, when the grounding protection of an upstream terminal in a certain section is activated and meets the transient power grounding discrimination condition, if the acquired zero-sequence current transient waveform shows high similarity and significantly differs from the waveform acquired by the downstream terminal, it can be determined that a real single-phase grounding fault has occurred in that section. A waveform similarity threshold H is set. set As a criterion for distributed collaborative verification, the similarity H of the zero-sequence current transient waveform is calculated between adjacent terminals. When the H values ​​of all upstream terminals in a certain segment are below a threshold, i.e., H... 1,2,...,j <0.2H set Its downstream terminals are higher than the threshold H j+1 >H set In this way, a real grounding fault can be identified and the faulty section can be located.

[0129] Preferably, based on high-precision wide-area synchronous sampling data, the Hausdorff distance algorithm is selected to quantify the similarity of zero-sequence current transient waveforms. The specific principle of the Hausdorff distance algorithm is as follows: for distributed protection terminals m and n on the same line, one-quarter of the power frequency cycle after the fault is extracted as a data window, and the set of zero-sequence current sampling points for terminal m is M = {i...} 01 , ..., i 0m ...}, the set of terminal n zero-sequence current sampling points is N = {i 01 , ..., i 0n The Hausdorff distance calculation formula for the zero-sequence currents at terminals m and n is as follows:

[0130] H(M,N)=max(h(M,N),h(N,M))

[0131]

[0132] In the above formula: ||i 0m -i 0n ||、||i 0n -i 0m|| represents the Euclidean distance between any two points in the sets M and N of zero-sequence current sampling points, and h(M,N) is the single-phase Hausdorff distance from set M to set N, representing the distance between any point i in set M. 0m First, calculate the Euclidean distance between the sampled points and all sampling points in set N, and then take the minimum distance. Finally, take the maximum value of this minimum distance in set M. The same applies to h(N,M). H(M,N) can be used to measure the matching degree of the zero-sequence current waveforms of adjacent distributed protection terminals. The value range is [0,1]. The closer H(M,N) is to 0, the smaller the difference between the two waveforms; the closer it is to 1, the larger the difference between the two waveforms.

[0133] Specifically, when the zero-sequence voltage amplitude or zero-sequence voltage surge energy criterion of FTU1 and FTU2 reaches a predetermined value, the grounding protection is activated and the transient power grounding discrimination condition is met. Distributed collaborative verification of adjacent terminals is initiated, and the similarity of the zero-sequence current transient waveform is calculated based on the Hausdorff distance algorithm. If the similarity of the zero-sequence current transient waveform of FTU1 and FTU2 is below a threshold, i.e., H... FTU1,FTU2 <0.2H set The similarity of the zero-sequence current transient waveforms of FTU2 and FTU3 is higher than the threshold H. FTU2,FTU3 >H set It was determined that a single-phase ground fault had occurred on line L2, and the fault point was located between switches FD22 and FD23.

[0134] Step 3. Circularly monitor the transient component of the zero-sequence current of the system, and combine the fault characteristic information interaction based on horizontal and vertical end-to-end communication to distinguish between in-line and out-of-phase fault types.

[0135] Preferably, the zero-sequence current transient component of the cyclic monitoring system initiates out-of-phase two-point grounding analysis when its amplitude exceeds a threshold.

[0136] Preferably, the zero-sequence current transient energy is selected as the fault characteristic quantity, and the terminal T j The transient zero-order energy is denoted as F. 0j Defined as:

[0137]

[0138] Where Δt is the sampling interval, and the number of sampling points within the interval is N, i 0j [k] represents terminal T j The instantaneous value of the zero-sequence current at the kth sampling point, u 0j [k] represents terminal T j The instantaneous value of the zero-sequence voltage at the k-th sampling point. This criterion has a directional characteristic, stipulating that the positive direction of the current is from the line to the busbar, and the zero-sequence energy is positive when the fault occurs in the downstream section of the terminal.

[0139] Set the energy threshold to F.set The fault location criterion is: terminal T j Satisfy |F 0j |>F set Its upstream terminal T j-1 Satisfy |F 0,j-1 |>F set Its downstream adjacent terminal T j+1 Fault characteristic quantity | F 0,j+1 |<0.2F set And F 0,j+1 If the value is less than 0 and the above criteria are met simultaneously, then the ground fault section furthest from the power source is located at T. j With T j+1 between.

[0140] Specifically, when a phase-B ground fault occurs at point K2 on line L2, and the amplitude of the zero-sequence current transient component is found to be higher than the threshold, an out-of-phase two-point ground fault analysis is initiated, and the zero-sequence current transient energy |FTU4 is calculated. 0,FTU4 |>F set FTU5 zero-sequence current transient energy |F 0,FTU5 |<0.2F set And F 0,FZ22 If <0, then the K2 grounding point, which is furthest from the power supply side, is located between FZ21 and FZ22.

[0141] Step 4. Implement selective fault handling strategies for two-point grounding faults of different phases on the same line and two-point grounding faults of different phases on different lines, minimizing the removal of fault sections.

[0142] Handling faults of different phases on the same line: If the fault point is on the main line and the branch line, the fault section of the branch line should be cut off first; if the grounding point is on the main line, the fault section away from the power source should be cut off first.

[0143] When a fault occurs on the main line and branch lines, a tiered tripping strategy is adopted. The branch line tripping time is set to 0.2s, and the main line tripping time is set to 0.5s. After the branch switch is disconnected first, the main line's out-of-phase two-point grounding protection is blocked. More specifically, when a fault occurs on the main line and branch lines, the branch terminal trips with a 0.2s delay, disconnects branch switches FZ21 and FZ22, blocks the main line's out-of-phase two-point grounding protection, and the system continuously monitors the zero-sequence current of the remaining grounding points, uploading the grounding information and location of the K1 fault point to the operation and maintenance alarm.

[0144] Preferably, the remaining grounding points are retained for continued operation, the transient component of zero-sequence current is continuously monitored, and maintenance alarms are pushed out synchronously.

[0145] Example 4

[0146] This invention provides another embodiment, which is a method for handling two-point grounding faults in a low-current grounding system. For example... Figure 1 As shown, Figure 1 This is a flowchart of a method for handling two-point grounding faults in a low-current grounding system according to the present invention.

[0147] When two points of grounding occur in different phases and on different lines, the present invention provides a method for handling two-point grounding faults in a low-current grounding system, comprising the following steps:

[0148] Step 1. Real-time data acquisition and processing: Deploy distributed protection terminals at key nodes of the distribution network, use wide-area synchronous phasor measurement technology to collect voltage and current data at various points on the line, preprocess the data to obtain high-precision wide-area synchronous sampling data.

[0149] Preferably, in step 1, the wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, and the time deviation of the sampling data of all distributed protection terminals is less than 1μs.

[0150] Preferably, in step 1, the synchronous sampling frequency for collecting voltage and current data at various points on the line is 12.8 kHz.

[0151] Preferably, in step 1, the data preprocessing method uses a wavelet thresholding denoising algorithm, selects the db4 wavelet basis function for 4-level decomposition, and processes the scale coefficients by improving the threshold function.

[0152] Specifically, such as Figure 4 As shown, Figure 4 This is a schematic diagram of the handling of two-point grounding faults in different lines and phases according to an embodiment of the present invention. In a certain 10kV distribution network, distributed protection terminals FTU1, FTU2, FTU3, FTU4, FTU5, and FTU6 are arranged on the main switches FD11, FD12, FD13, FD21, FD22, and FD23 of lines L1 and L2.

[0153] exist Figure 4 In the middle, a phase A ground fault occurred at point K1 on line L1.

[0154] Step 2. Use both steady-state and transient grounding protection activation criteria. When either criterion is met, initiate distributed collaborative verification of adjacent terminals to determine the actual grounding fault.

[0155] Preferably, in step 2, the zero-sequence voltage amplitude and the zero-sequence voltage change energy are selected as grounding protection activation criteria. When either criterion reaches a set value, the grounding protection is activated.

[0156] U0>U 0set

[0157]

[0158] Where U0 is the zero-sequence voltage amplitude, U 0setLet u0 be the zero-sequence voltage setpoint, k be the sampling point number, E0 be the zero-sequence voltage change energy, u0[k] be the instantaneous voltage value at the kth sampling point, and E0 be the zero-sequence voltage change energy. 0set The zero-sequence voltage change energy is a fixed value, and N is the number of sampling points within a certain time window.

[0159] Preferably, in step 2, the distributed collaborative verification eliminates the influence of single-point, single-data errors through synchronous data interaction and feature comparison between adjacent distributed protection terminals on the same line. Specifically, when the grounding protection of an upstream terminal in a certain section is activated and meets the transient power grounding discrimination condition, if the acquired zero-sequence current transient waveform shows high similarity and significantly differs from the waveform acquired by the downstream terminal, it can be determined that a real single-phase grounding fault has occurred in that section. A waveform similarity threshold H is set. set As a criterion for distributed collaborative verification, the similarity H of the zero-sequence current transient waveform is calculated between adjacent terminals. When the H values ​​of all upstream terminals in a certain segment are below a threshold, i.e., H... 1,2,...,j <0.2H set Its downstream terminals are higher than the threshold H j+1 >H set In this way, a real grounding fault can be identified and the faulty section can be located.

[0160] Preferably, based on high-precision wide-area synchronous sampling data, the Hausdorff distance algorithm is selected to quantify the similarity of zero-sequence current transient waveforms. The specific principle of the Hausdorff distance algorithm is as follows: for distributed protection terminals m and n on the same line, one-quarter of the power frequency cycle after the fault is extracted as a data window, and the set of zero-sequence current sampling points for terminal m is M = {i...} 01 , ..., i 0m ...}, the set of terminal n zero-sequence current sampling points is N = {i 01 , ..., i 0n The Hausdorff distance calculation formula for the zero-sequence currents at terminals m and n is as follows:

[0161] H(M,N)=max(h(M,N),h(N,M))

[0162]

[0163] In the above formula: ||i 0m -i 0n ||、||i 0n -i 0m || represents the Euclidean distance between any two points in the sets M and N of zero-sequence current sampling points, and h(M,N) is the single-phase Hausdorff distance from set M to set N, representing the distance between any point i in set M. 0mFirst, calculate the Euclidean distance between the sampled points and all sampling points in set N, and then take the minimum distance. Finally, take the maximum value of this minimum distance in set M. The same applies to h(N,M). H(M,N) can be used to measure the matching degree of the zero-sequence current waveforms of adjacent distributed protection terminals. The value range is [0,1]. The closer H(M,N) is to 0, the smaller the difference between the two waveforms; the closer it is to 1, the larger the difference between the two waveforms.

[0164] Specifically, when the zero-sequence voltage amplitude or zero-sequence voltage surge energy criterion of FTU1 reaches a predetermined value, the grounding protection is activated and the transient power grounding discrimination condition is met. Distributed collaborative verification of adjacent terminals is initiated, and the similarity of the zero-sequence current transient waveform is calculated based on the Hausdorff distance algorithm. If the similarity of the zero-sequence current transient waveforms of FTU1 and FTU2 is higher than a threshold, i.e., H... FTU1,FTU2 >H set It was determined that a single-phase ground fault had occurred on line L1, and the fault point was located between switches FD11 and FD12.

[0165] Step 3. Circularly monitor the transient component of the zero-sequence current of the system, and combine the fault characteristic information interaction based on horizontal and vertical end-to-end communication to distinguish between in-line and out-of-phase fault types.

[0166] Preferably, the zero-sequence current transient component of the cyclic monitoring system initiates out-of-phase two-point grounding analysis when its amplitude exceeds a threshold.

[0167] Preferably, the zero-sequence current transient energy is selected as the fault characteristic quantity, and the terminal T j The transient zero-order energy is denoted as F. 0j Defined as:

[0168]

[0169] Where Δt is the sampling interval, and the number of sampling points within the interval is N, i 0j [k] represents terminal T j The instantaneous value of the zero-sequence current at the kth sampling point, u 0j [k] represents terminal T j The instantaneous value of the zero-sequence voltage at the k-th sampling point. This criterion has a directional characteristic, stipulating that the positive direction of the current is from the line to the busbar, and the zero-sequence energy is positive when the fault occurs in the downstream section of the terminal.

[0170] Set the energy threshold to F. set The fault location criterion is: terminal T j Satisfy |F 0j |>F set Its upstream terminal T j-1 Satisfy |F 0,j-1 |>F set Its downstream adjacent terminal T j+1Fault characteristic quantity | F 0,j+1 |<0.2F set And F 0,j+1 If the value is less than 0 and the above criteria are met simultaneously, then the ground fault section furthest from the power source is located at T. j With T j+1 between.

[0171] When a line detects a zero-sequence current transient energy that is greater than the energy threshold, the flag bit is set to 1, and Flag = 1; when the zero-sequence current transient energy is positive, P = 1, and when it is negative, P = -1. The terminals at the beginning of different lines exchange fault flag bits Flag and P through longitudinal communication. When both lines simultaneously satisfy Flag1 = 1 and Flag2 = 1, and P1·P2 = -1, it is determined to be a cross-line, cross-phase fault.

[0172] Specifically, when a phase-C ground fault occurs at point K2 on line L2, and the amplitude of the zero-sequence current transient component is found to be higher than the threshold, an out-of-phase two-point ground fault analysis is initiated. The zero-sequence current transient energy of FTU1 at the head end of line L1 is |F 0,FD11 |>F set Flag position 1, Flag1 = 1, zero-sequence current transient energy is positive, P1 = 1, denoted as zero-sequence current transient energy |F at the beginning and end of line L2, FTU4. 0,FD21 |>F set When the flag position is 1, Flag2 = 1. The transient energy of the zero-sequence current is negative, and P2 = -1. The two line terminals exchange information and satisfy Flag1 = 1 and Flag2 = 1. When P1·P2 = -1, it is determined to be a cross-line phase fault.

[0173] Step 4. Implement selective fault handling strategies for two-point grounding faults of different phases on the same line and two-point grounding faults of different phases on different lines, minimizing the removal of fault sections.

[0174] Handling of cross-line and cross-phase faults: Construct a multi-dimensional weighted evaluation model. The terminal at the beginning of the line evaluates the protection tripping priority through local edge computing and disconnects the line with higher priority.

[0175] Based on the analytic hierarchy process (AHP), the tripping priority index is defined as follows:

[0176] P i =αS 位置 +βS 用户 +δS 负载率 +γS 能量

[0177] Among them, S 位置 Location indicates the tripping index of the terminal's topology location; for example, the tripping index is higher for branch lines and switches crossing forest areas; S 用户This indicates the tripping index based on user importance; for example, important users such as hospitals have a lower tripping index. 负载率 This represents the line load factor tripping index; the higher the load, the smaller the tripping index. (S) 能量 The normalized zero-sequence transient energy tripping index is represented by α, β, δ, and γ, which represent weighting coefficients. The lower the transient energy, the smaller the tripping index.

[0178] Preferably, the remaining grounding points are retained for continued operation, the transient component of zero-sequence current is continuously monitored, and maintenance alarms are pushed out synchronously.

[0179] Specifically, such as Figure 5 As shown, Figure 5 This is a schematic diagram of hierarchical analysis in this embodiment of the invention, that is, a schematic diagram of the hierarchical model used by the hierarchical analysis method. The weight model parameters are: α = 0.3, β = 0.4, γ = 0.2, δ = 0.1. After calculation, the tripping priority index P1 of line L1 is 0.75, and the tripping priority index P2 of line L2 is 0.69. The fault point of line L1 is cut off first, and the switches FD11 and FD12 are disconnected. The system continuously monitors the zero-sequence current of the remaining grounding point and uploads the grounding information and location of the fault point K2 to the operation and maintenance alarm.

[0180] Example 5

[0181] This invention provides another embodiment, which is a system for handling out-of-phase two-point grounding faults in a low-current grounding system. For example... Figure 2 As shown, Figure 2 This is a schematic diagram of a low-current grounding system for handling two-point grounding faults in different phases according to the present invention.

[0182] This invention discloses a system for handling out-of-phase two-point grounding faults in a low-current grounding system, comprising:

[0183] Distribution network distributed protection architecture: Each outgoing line of the same bus contains multiple distribution network distributed protection terminals.

[0184] The distributed protection terminal of the distribution network includes: the head terminal, the main line terminal and the branch line terminal.

[0185] 5G end-to-end communication is used for horizontal information transmission between adjacent terminals on the same line.

[0186] Fiber optic communication is used for vertical information transmission between the first-end terminals of different lines.

[0187] Preferably, the hardware architecture of the distributed protection terminal for the power distribution network consists of a power supply module, a high-precision measurement module, an edge computing module, and a communication module. For example... Figure 6 As shown, Figure 6This is a schematic diagram of the hardware architecture of the distributed protection terminal for the power distribution network of the present invention. The high-precision measurement module is connected to the edge computing module, and the edge computing module is bidirectionally connected to the communication module.

[0188] Furthermore, the power module has a rated operating voltage of AC 220V and includes battery power supply, PT power supply and emergency power supply methods.

[0189] The high-precision measurement module includes a BeiDou / GPS clock timing module, a data acquisition unit, an A / D conversion unit, and a phasor measurement unit. The BeiDou / GPS clock timing module is connected to the phasor measurement unit, the data acquisition unit is connected to the A / D conversion unit, the A / D conversion unit is connected to the phasor measurement unit, and the phasor measurement unit is connected to the data processing layer in the edge computing module.

[0190] The communication module integrates two physical channels: 5G wireless communication (end-to-end mode) and fiber optic communication, and fully supports the IEC 60870-5-101 / 104 power communication protocol.

[0191] The edge computing module includes a data processing layer and an intelligent computing layer, and incorporates wavelet threshold denoising algorithm, Hausdorff distance algorithm, priority evaluation algorithm and fault decision logic.

[0192] The small current grounding system out-of-phase two-point grounding fault handling system described in this embodiment is used to implement the small current grounding system out-of-phase two-point grounding fault handling method of the present invention described in embodiment 1, 2, 3 or 4.

[0193] Example 6

[0194] Based on the same inventive concept, embodiments of the present invention also provide a computer device, including a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor. When the processor executes the computer program, it implements the steps of any one of the methods for handling out-of-phase two-point grounding faults in a low-current grounding system as described in Embodiments 1, 2, 3, or 4.

[0195] Example 7

[0196] Based on the same inventive concept, this embodiment of the invention also provides a computer storage medium storing a computer program, which, when executed by a processor, implements the steps of any one of the methods for handling out-of-phase two-point grounding faults in a small current grounding system as described in Embodiment 1, 2, 3, or 4.

[0197] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0198] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0199] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0200] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0201] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for handling two-point grounding faults in a low-current grounding system, characterized by: Includes the following steps: Real-time data acquisition and processing yield high-precision, wide-area synchronous sampling data; Based on high-precision wide-area synchronous sampling data, dual-criteria initiation and distributed collaborative verification are used to determine the actual grounding fault. For two-point grounding faults of different phases, hierarchical fault identification is performed; Based on the fault identification results, differentiated and rapid handling is carried out to minimize the removal of faulty sections.

2. The method for handling two-point grounding faults in a low-current grounding system according to claim 1, characterized in that: The real-time data acquisition and processing to obtain high-precision wide-area synchronous sampling data involves deploying distributed protection terminals at key nodes of the distribution network, using wide-area synchronous phasor measurement technology to collect voltage and current data at various points on the line, and preprocessing the data to obtain high-precision wide-area synchronous sampling data. Wide-area synchronous phasor measurement technology establishes a unified time scale system through BeiDou satellite timing, with the time deviation of all distributed protection terminal sampling data being less than 1μs; the synchronous sampling frequency for collecting voltage and current data at each point of the line is 12.8KHz; the data preprocessing method adopts the wavelet threshold denoising algorithm, selects the db4 wavelet basis function for 4-level decomposition, and processes the scale coefficients by improving the threshold function.

3. The method for handling two-point grounding faults in a low-current grounding system according to claim 1, characterized in that: The method of determining the actual grounding fault based on high-precision wide-area synchronous sampling data and using dual-criteria activation and distributed collaborative verification is to use steady-state and transient grounding protection activation dual criteria. When either criterion is met, the distributed collaborative verification of adjacent terminals is activated to determine the actual grounding fault. Zero-sequence voltage amplitude and zero-sequence voltage change energy are selected as grounding protection activation criteria. When either criterion reaches a set value, the grounding protection is activated, i.e.: U0>U 0set Where U0 is the zero-sequence voltage amplitude, U 0set Let u0 be the zero-sequence voltage setpoint, k be the sampling point number, E0 be the zero-sequence voltage change energy, u0[k] be the instantaneous voltage value at the kth sampling point, and E0 be the zero-sequence voltage change energy. 0set The zero-sequence voltage change energy is a set value, and N is the number of sampling points within the sampling interval; The distributed collaborative verification eliminates the influence of single-point single-data error by synchronous data interaction and feature comparison between adjacent distributed protection terminals on the same line; when the grounding protection of the upstream terminal of a certain section is activated and the transient power grounding discrimination condition is met, if the collected zero-sequence current transient waveform shows a high degree of similarity and is significantly different from the waveform collected by the downstream terminal, it is determined that a real single-phase grounding fault has occurred in the section. Set waveform similarity threshold H set As a criterion for distributed collaborative verification, the similarity H of the zero-sequence current transient waveform is calculated between adjacent terminals. When the H values ​​of all upstream terminals in a certain segment are below a threshold, i.e., H... 1,2,...,j <0.2H set Its downstream terminals are higher than the threshold H j+1 >H set At that time, determine the actual grounding fault and locate the faulty section; Based on high-precision wide-area synchronous sampling data, the Hausdorff distance algorithm is selected to quantify the similarity of zero-sequence current transient waveforms. The principle of the Hausdorff distance algorithm is as follows: for distributed protection terminals m and n on the same line, 1 / 4 of the power frequency cycle after the fault is extracted as the data window, and the set of zero-sequence current sampling points for terminal m is M = {i 01 , ..., i 0m The set of zero-sequence current sampling points for terminal n is N = {i} 01 , ..., i 0n The Hausdorff distance calculation formula for the zero-sequence currents at terminals m and n is as follows: H(M,N)=max(h(M,N),h(N,M)) In the above formula: ||i 0m -i 0n ||、||i 0n -i 0m || represents the Euclidean distance between any two points in the sets M and N of zero-sequence current sampling points, and h(M,N) is the single-phase Hausdorff distance from set M to set N, representing the distance between any point i in set M. 0m First, calculate the Euclidean distance between it and all sampling points in set N, and take the minimum value of the distance. Then, take the maximum value of this minimum distance in set M. The same applies to h(N,M). H(M,N) can be used to measure the matching degree of the zero-sequence current waveforms of adjacent distributed protection terminals. The value range is [0,1]. When H(M,N) is closer to 0, the difference between the two waveforms is smaller. When it is closer to 1, the difference between the two waveforms is larger.

4. The method for handling two-point grounding faults in a low-current grounding system according to claim 1, characterized in that: For the aforementioned two-point grounding fault of different phases, a hierarchical fault identification is performed. This involves cyclically monitoring the transient component of the zero-sequence current in the system, and combining this with fault characteristic information exchange based on horizontal and vertical end-to-end communication to distinguish between in-line and out-of-line fault types, including: Step 3.1 Circularly monitor the transient component of the zero-sequence current in the system. When the amplitude is higher than the threshold, initiate the analysis of out-of-phase two-point grounding. Step 3.2 Identification of co-line non-phase faults: If non-phase grounding fault characteristics appear on a line that has already been grounded, it is determined to be a co-line non-phase grounding fault, and the fault section is determined through lateral communication; Choosing the zero-sequence current transient energy as a fault characteristic quantity, the terminal T j The transient zero-order energy is denoted as F. 0j Defined as: Where Δt is the sampling interval, and the number of sampling points within the interval is N, i 0j [k] represents terminal T j The instantaneous value of the zero-sequence current at the k-th sampling point, u 0j [k] represents terminal T j The instantaneous value of zero-sequence voltage at the kth sampling point; the criterion has directional characteristics, and the positive direction of the current is defined as the line pointing to the bus. When the fault occurs in the downstream section of the terminal, the zero-sequence energy is positive. Set the energy threshold to F. set The fault location criterion is: terminal T j Satisfy |F 0j |>F set Its upstream terminal T j-1 Satisfy |F 0,j-1 |>F set Its downstream adjacent terminal T j+1 Fault characteristic quantity | F 0,j+1 |<0.2F set And F 0,j+1 If the value is less than 0 and the above criteria are met simultaneously, then the ground fault section furthest from the power supply side is located at terminal T. j With terminal T j_+1 between; Step 3.3 Identification of cross-line and cross-phase faults: The terminals at the beginning of different lines exchange fault flag bits and fault characteristic quantities through longitudinal communication. When two lines simultaneously meet the fault characteristic conditions, it is determined to be a cross-line fault. When the line detects zero-sequence current transient energy and it is greater than the energy threshold, the flag is set to 1, and Flag = 1 is recorded. When the zero-sequence current transient energy is positive, P = 1 is recorded, and when it is negative, P = -1 is recorded. The terminals at the beginning of different lines exchange the fault flag bits Flag and P through longitudinal communication. When both lines simultaneously satisfy Flag1 = 1 and Flag2 = 1, and P1·P2 = -1, it is determined to be a cross-line phase fault.

5. The method for handling two-point grounding faults in a low-current grounding system according to claim 1, characterized in that: The differentiated rapid handling based on fault identification results, minimizing the removal of faulty sections, specifically involves implementing selective fault handling strategies for co-phase and cross-phase two-point grounding faults, minimizing the removal of faulty sections, including: Step 4.1 Handling faults with different phases on the same line; If the fault point is on the main line and branch line, a tiered tripping strategy is adopted to prioritize the disconnection of the fault section on the branch line; if the grounding point is on the main line, the fault section far away from the power supply side is prioritized to be disconnected through lateral information transmission. Step 4.2 Handling of cross-phase faults; A multi-dimensional weighted evaluation model is constructed, and the line head-end terminal evaluates the protection tripping priority through local edge computing and cuts off the line with higher priority. Based on the analytic hierarchy process (AHP), the tripping priority index is defined as follows: P i =αS 位置 +βS 用户 +δS 负载率 +γS 能量 Among them, S 位置 Location indicates the tripping index of the topology where the terminal is located, S 用户 S represents the user importance tripping index. 负载率 S represents the line load factor tripping index. 能量 The normalized zero-order transient energy tripping index is represented by α, β, δ, and γ, which are weighting coefficients. The fault point protection terminal calculates the tripping priority index at the local edge and compares them through longitudinal end-to-end communication at the first terminal, prioritizing the clearing of fault sections with higher priority indices. Step 4.3 Retain the remaining grounding points and continue operation, continuously monitor the transient component of zero-sequence current, and push operation and maintenance alarms synchronously.

6. A system for handling out-of-phase two-point grounding faults in a low-current grounding system, characterized in that: include: Distribution network distributed protection architecture: Each outgoing line of the same bus contains multiple distribution network distributed protection terminals; The distributed protection terminals for distribution networks include: head-end terminals, main line terminals, and branch line terminals; 5G end-to-end communication is used for horizontal information transmission between adjacent terminals on the same line, while fiber optic communication is used for vertical information transmission between terminals at the beginning of different lines.

7. A system for handling out-of-phase two-point grounding faults in a low-current grounding system according to claim 6, characterized in that: The hardware architecture of the distributed protection terminal for the power distribution network consists of a power supply module, a high-precision measurement module, an edge computing module, and a communication module. The high-precision measurement module is connected to the edge computing module, and the edge computing module is bidirectionally connected to the communication module.

8. A system for handling out-of-phase two-point grounding faults in a low-current grounding system according to claim 7, characterized in that: The power module has a rated operating voltage of AC 220V and includes battery power supply, PT power supply and emergency power supply methods. The high-precision measurement module includes a BeiDou / GPS clock timing module, a data acquisition unit, an A / D conversion unit, and a phasor measurement unit. The BeiDou / GPS clock timing module is connected to the phasor measurement unit, the data acquisition unit is connected to the A / D conversion unit, the A / D conversion unit is connected to the phasor measurement unit, and the phasor measurement unit is connected to the data processing layer in the edge computing module. The communication module integrates two physical channels: 5G wireless communication and fiber optic communication, and fully supports the IEC 60870-5-101 / 104 power communication protocol. The edge computing module includes a data processing layer and an intelligent computing layer.

9. A computer device, comprising a storage medium, a processor, and a computer program stored on the storage medium and executable on the processor, characterized in that, When the processor executes the computer program, it implements the steps of the method for handling out-of-phase two-point grounding faults in a low-current grounding system as described in any one of claims 1-5.

10. A computer storage medium, characterized in that: The computer storage medium contains a computer program, which, when executed by a processor, implements the steps of a method for handling out-of-phase two-point grounding faults in a low-current grounding system as described in any one of claims 1-5.

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