A power distribution network intermittent ground fault identification method and system

Abstract

The application discloses a kind of power distribution network intermittent ground fault identification method and system, comprising: preset first zero sequence voltage threshold, establish the second admittance threshold based on first zero sequence voltage threshold, third conductance threshold and fourth admittance threshold;Preset sampling window time, judge the relationship between target power distribution network real-time zero sequence voltage and first zero sequence voltage threshold;Cumulative parameters in corresponding sampling window time when meeting the condition of judgment are calculated, and whether the intermittent ground fault of target power distribution network occurs is judged according to cumulative parameters.This method measures the amplitude and admittance parameter of power frequency zero sequence voltage, and discriminates based on cumulative intermittent arc fault duration.This method is suitable for ungrounded and arc suppression coil grounding system, and can accurately identify intermittent ground fault.

Description

Technical Field

[0001] This invention relates to the field of intermittent grounding fault identification technology in power distribution networks, and in particular to a method and system for intermittent grounding fault identification in power distribution networks. Background Technology

[0002] Intermittent grounding faults in distribution networks are phenomena caused by intermittent discharges between the line and ground due to factors such as line aging, poor contact, and insufficient tree branch insulation distance during distribution network operation, resulting in abnormal line voltage and current. The concealed, complex, and random nature of intermittent grounding faults poses significant challenges to fault diagnosis. The existence of intermittent faults can render some grounding fault protection methods ineffective, such as the zero-sequence admittance method. Furthermore, unclear fault type identification also affects further decision-making by systems such as line grounding fault monitoring.

[0003] Existing methods for detecting intermittent arc faults mainly use high-frequency components of phase current and voltage, high-frequency components of neutral current, increments of selected even-order harmonic power, or analyze traveling waves generated by the arc fault to detect the fault.

[0004] High-frequency component analysis methods are generally based on Fast Fourier Transform (FFT) analysis, wavelet analysis, or harmonic power calculation. These methods typically employ signal sampling frequencies ranging from 6.4 kHz to hundreds of kHz. The frequency-based methods used are usually accompanied by complex signal processing and decision-making algorithms, such as fuzzy logic, eigenvectors and vector inference machines, statistical confidence methods, statistical variance estimation, Hilbert transform methods, and ANN techniques. High sampling frequencies and complex decision-making algorithms involve large computational demands, requiring high-performance hardware and placing high demands on field equipment.

[0005] Furthermore, due to the nonlinear and highly random variation of the grounding resistance during intermittent arc faults, coupled with its large resistance value, the aforementioned methods cannot avoid its influence. Summary of the Invention

[0006] The purpose of this section is to outline some aspects of embodiments of the present invention and to briefly describe some preferred embodiments. Simplifications or omissions may be made in this section, as well as in the abstract and title of this application, to avoid obscuring the purpose of these documents; however, such simplifications or omissions should not be construed as limiting the scope of the invention.

[0007] In view of the aforementioned existing problems, the present invention is proposed.

[0008] Therefore, the present invention provides a method and system for identifying intermittent grounding faults in a power distribution network, which can solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] In a first aspect, the present invention provides a method for identifying intermittent grounding faults in a distribution network, comprising:

[0011] A first zero-sequence voltage threshold is preset, and a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold are established based on the first zero-sequence voltage threshold.

[0012] The sampling window time is preset to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold.

[0013] Calculate the cumulative parameters in the corresponding sampling window time when the judgment condition is met, and determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

[0014] As a preferred embodiment of the intermittent grounding fault identification method for distribution networks according to the present invention, the preset sampling window time for determining the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold includes:

[0015] The sampling window time is a preset interval for saving the sampled data;

[0016] Determine the relationship between the real-time zero-sequence voltage at the first target sampling point in the target distribution network and the first zero-sequence voltage threshold.

[0017] As a preferred embodiment of the intermittent grounding fault identification method for distribution networks described in this invention, the calculation of the cumulative parameters in the corresponding sampling window time when the judgment conditions are met includes:

[0018] If the real-time zero-sequence voltage at the first target sampling point in the target distribution network meets the judgment condition, then mark this first target sampling point;

[0019] Obtain the sampling data of the first target sampling point within the sampling window time;

[0020] The cumulative parameter is calculated based on the sampled data and the first cumulative logic.

[0021] In a preferred embodiment of the intermittent grounding fault identification method for distribution networks described in this invention, the first accumulation logic includes:

[0022] Determine the value of the first variable at the second target sampling point within the sampling window time;

[0023] The values ​​of the first variable at all second target sampling points in the sampling window are accumulated.

[0024] In a preferred embodiment of the intermittent grounding fault identification method for distribution networks described in this invention, the step of determining the first variable value at the second target sampling point within the sampling window time includes:

[0025] If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then calculate the cumulative parameter in the corresponding sampling window time when the judgment condition is met;

[0026] If the real-time zero-sequence voltage at the first target sampling point is not greater than the first zero-sequence voltage threshold, then the cumulative parameters in the corresponding sampling window time when the judgment condition is met are not calculated.

[0027] As a preferred embodiment of the intermittent grounding fault identification method for distribution networks according to the present invention, the step of judging the first variable value at the second target sampling point within the sampling window time further includes:

[0028] If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then determine the relationship between the real-time admittance value at the first target sampling point and the second admittance threshold, the real-time conductance value at the first target sampling point and the third conductance threshold, and the real-time susceptance value at the first target sampling point and the fourth susceptance threshold.

[0029] If the real-time admittance value at any of the first target sampling points is greater than the second admittance threshold, or the real-time conductance value at the first target sampling point is greater than the third conductance threshold, or the real-time susceptance value at the first target sampling point is greater than the fourth susceptance threshold, then the first variable value is recorded as 1; otherwise, it is recorded as 0.

[0030] As a preferred embodiment of the intermittent grounding fault identification method for distribution networks according to the present invention, the step of determining whether an intermittent grounding fault has occurred in the target distribution network based on the accumulated parameters includes:

[0031] Accumulate the first variable values ​​at all second target sampling points in the sampling window;

[0032] If the cumulative result of the first variable value at all second target sampling points in the sampling window is greater than the first cumulative threshold, then it is determined that an intermittent grounding fault has occurred in the target distribution network.

[0033] Otherwise, it is determined that no intermittent grounding fault has occurred in the target distribution network.

[0034] Secondly, the present invention provides a system for identifying intermittent grounding faults in a power distribution network, comprising:

[0035] The threshold preset module is used to preset a first zero-sequence voltage threshold and establish a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold.

[0036] The first judgment module is used to preset the sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold.

[0037] The second judgment module is used to calculate the cumulative parameters in the corresponding sampling window time when the judgment conditions are met, and to determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

[0038] Thirdly, the present invention provides a computer device including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps of the method described above.

[0039] Fourthly, the present invention provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the steps of the method described above.

[0040] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention proposes a method and system for identifying intermittent grounding faults in distribution networks. It presets a first zero-sequence voltage threshold and establishes a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold. It presets a sampling window time and determines the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold. It calculates the cumulative parameters within the corresponding sampling window time when the judgment conditions are met, and determines whether an intermittent grounding fault has occurred in the target distribution network based on the cumulative parameters. This method measures the amplitude and admittance parameters of the power frequency zero-sequence voltage and performs calculations based on the cumulative duration of the intermittent arc fault. This method is applicable to ungrounded and arc-suppression coil grounded systems and can accurately identify intermittent grounding faults. Attached Figure Description

[0041] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. Wherein:

[0042] Figure 1 A flowchart illustrating a method and system for identifying intermittent grounding faults in a power distribution network, as provided in one embodiment of the present invention;

[0043] Figure 2 A schematic diagram of the equivalent circuit for a single-phase grounding fault in an arc suppression coil grounding system of a distribution network intermittent grounding fault identification method and system provided in one embodiment of the present invention;

[0044] Figure 3 A detailed algorithm flowchart of a method and system for identifying intermittent grounding faults in a power distribution network, provided as an embodiment of the present invention;

[0045] Figure 4 This is an internal structural diagram of a computer device for a method and system for identifying intermittent grounding faults in a power distribution network, provided as an embodiment of the present invention. Detailed Implementation

[0046] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present invention.

[0047] Example 1

[0048] Reference Figures 1-4 This is the first embodiment of the present invention, which provides a method and system for identifying intermittent grounding faults in a distribution network, including:

[0049] Existing technologies have some technical problems. For example, in complex power distribution networks, due to the wide distribution of lines and frequent load changes, intermittent grounding faults are difficult to detect and locate accurately and quickly.

[0050] This application provides a method that can effectively solve the problems mentioned above. The following will describe in detail how to implement the intermittent grounding fault identification method for the power distribution network using multiple embodiments.

[0051] Figure 1 A flowchart of a method and system for identifying intermittent grounding faults in a distribution network is shown, including:

[0052] S101, preset a first zero-sequence voltage threshold, and establish a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold;

[0053] In an optional embodiment, when a single-phase ground fault occurs in the power distribution line, the arc suppression coil grounding system can be equivalent to... Figure 2 , Figure 1 L C G c It is a neutral point arc suppression coil that compensates for inductance and conductance, G 0F C 0F G 0H C 0H These are the conductance and capacitance of the faulty circuit and the conductance and capacitance of the non-faulty circuit, respectively. R F It is the ground fault resistance, U ph It is the additional power supply at the fault point.

[0054] In an optional embodiment, the zero-sequence voltage after a fault can be expressed as:

[0055]

[0056] In the formula, G 0T C 0T It represents the conductivity and capacitance of the entire system, and k is the compensation coefficient of the arc suppression coil.

[0057] In an optional embodiment, the corresponding zero-sequence current of the faulty line can be expressed as:

[0058]

[0059] In an optional embodiment, the zero-sequence current of the i-th non-faulty line can be expressed as:

[0060]

[0061] In an optional embodiment, the admittance of the faulty line after the fault can be expressed as:

[0062]

[0063] In an optional embodiment, the admittance of the i-th non-faulty line can be expressed as:

[0064]

[0065] The above formula is based on the arc suppression coil grounding system. If k = 0, G c If =0, then the above formula is the corresponding calculation formula for a neutral point ungrounded system.

[0066] In an optional embodiment, as shown in Equation (4), the admittance calculation is independent of the grounding resistance value at the fault point, which can adapt to the nonlinear random changes in the grounding resistance at the fault point during grounding and has good high-resistance fault detection capability. However, intermittent grounding can lead to errors in the admittance calculation. Therefore, a method is needed to improve the operation of grounding fault protection under such conditions.

[0067] In an optional embodiment, based on the above analysis, it can be known that zero-sequence voltage, admittance, conductance, and susceptance are important parameters affecting intermittent grounding. Of course, in addition to these parameters, there are other parameters that affect intermittent grounding, such as load current, line length, and line material.

[0068] In this embodiment of the application, only zero-sequence voltage, admittance, conductance, and susceptance are selected as the important parameters affecting intermittent grounding for analysis;

[0069] In this embodiment, a first zero-sequence voltage threshold is preset, and a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold are established based on the first zero-sequence voltage threshold.

[0070] In one alternative embodiment, there are many ways to set the first zero-sequence voltage threshold, the second admittance threshold, the third conductance threshold, and the fourth susceptance threshold. For example, user-defined methods, empirical formula methods, and statistical analysis methods can be used. User-defined methods allow operators to set thresholds based on the actual operation of the power grid and historical data, while empirical formula methods determine thresholds based on typical parameters of the distribution network and historical fault data. Statistical analysis methods collect a large amount of data under normal and fault conditions and use statistical methods to determine reasonable thresholds.

[0071] In an optional embodiment, intermittent ground faults can be effectively identified by setting appropriate thresholds. For example, when the zero-sequence voltage exceeds a preset first zero-sequence voltage threshold, the system initiates a fault identification procedure. This procedure calculates the current admittance, conductance, and susceptance values ​​and compares them with the corresponding thresholds. If the calculated parameter values ​​exceed the thresholds, the system determines that an intermittent ground fault exists and performs corresponding actions.

[0072] In this embodiment, a user-defined method is used to set the first zero-sequence voltage threshold, the second admittance threshold, the third conductance threshold, and the fourth susceptance threshold. The first zero-sequence voltage threshold U 0Set Second admittance threshold Y 0Set The third conductivity threshold G 0Set and the fourth susceptance threshold B 0Set The specific threshold settings are as follows:

[0073] First zero-sequence voltage threshold U 0Set Generally, 10V is used;

[0074] Second admittance threshold:

[0075]

[0076] I ub This is due to inconsistencies in CT scans, and the value can generally be taken as 20-30mA. 0T It is the sum of the capacitive currents of all lines. k is the reliability coefficient, which is taken as 1.2 in this application.

[0077] Third conductivity threshold G 0Set =kΔY, fourth susceptance threshold B 0Set =kΔY.

[0078] It should be noted that setting a first zero-sequence voltage threshold and establishing a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on this threshold can improve the sensitivity and accuracy of fault detection. When the zero-sequence voltage exceeds the first zero-sequence voltage threshold, the system will immediately respond and initiate a fault identification procedure. By calculating the admittance, conductance, and susceptance values ​​in real time and comparing them with the preset thresholds, the system can quickly and accurately determine whether an intermittent grounding fault exists. This method can not only effectively identify high-resistance faults but also has good adaptability to the detection of intermittent grounding faults. Furthermore, the thresholds set by the user-defined method can be optimized for the actual conditions of a specific power grid, further improving the accuracy and reliability of fault detection.

[0079] S102, preset sampling window time, determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold;

[0080] In this embodiment of the application, the preset sampling window time and the determination of the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold include:

[0081] The sampling window time is a preset interval for saving the sampled data;

[0082] Determine the relationship between the real-time zero-sequence voltage at the first target sampling point in the target distribution network and the first zero-sequence voltage threshold.

[0083] In an alternative embodiment, real-time data such as the zero-sequence current of each feeder and arc suppression coil and the zero-sequence current of the bus can be sampled by installing monitoring equipment in the substation. Alternatively, the changes in zero-sequence voltage can be continuously tracked through a real-time monitoring system. Real-time data can also be obtained in other ways, such as by using a wireless sensor network or a remote monitoring system.

[0084] In this embodiment of the application, monitoring equipment is installed in the substation to sample real-time data such as the zero-sequence current of each feeder and arc suppression coil and the zero-sequence current of the bus.

[0085] In an optional embodiment, the preset interval can be designed according to the specific needs of the technicians, for example, set between 100ms and 500ms, to ensure that the characteristic signals of intermittent grounding faults can be captured. The sampling window time should not be too long to avoid missing the instantaneous changes in the fault signal; at the same time, it should not be too short to avoid misjudgment due to noise interference. In practical applications, the sampling window time can be appropriately adjusted according to the specific conditions of the distribution network and the fault characteristics to achieve the best fault detection effect.

[0086] In an optional embodiment, the first target sampling point is a set of target sampling points in the target distribution network. The specific sampling point locations can be customized or selected based on the structure and operating characteristics of the distribution network. For example, if there are multiple branch lines in the distribution network, the target sampling point can be set at the end of each branch line to facilitate the capture of fault signals from each branch line. Furthermore, the selection of sampling points should also consider the protection strategy and fault location requirements of the distribution network to ensure that the fault point can be located quickly and accurately when a fault occurs.

[0087] In this embodiment, the system determines the relationship between the real-time zero-sequence voltage at the first target sampling point in the target distribution network and a first zero-sequence voltage threshold. If the real-time zero-sequence voltage exceeds the first zero-sequence voltage threshold, the system triggers a fault identification procedure. This procedure calculates the admittance, conductance, and susceptance values ​​of the target sampling point in real time and compares them with preset second admittance thresholds, third conductance thresholds, and fourth susceptance thresholds. If any parameter value in the calculation result exceeds its corresponding threshold, the system determines that an intermittent grounding fault exists and executes corresponding fault handling measures. In this way, the system can respond promptly and accurately identify intermittent grounding faults, thereby ensuring the safe and stable operation of the distribution network.

[0088] In the embodiments of this application, such as Figure 3 As shown, the zero-sequence voltage U0 is sampled point by point and calculated to determine whether the line has been crossed; if U0 > U 0Set Then the sampled data is saved, with a window time of T. W The total number is N, T W Determined based on the time required to coordinate with protection or other systems, for example: 0.5 seconds.

[0089] It should be noted that setting a preset sampling window time and determining the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold ensures that the system can promptly detect abnormal changes in the zero-sequence voltage when a fault occurs and react quickly by comparing it with the preset threshold. Furthermore, by sampling and calculating the zero-sequence voltage point by point, the system can more accurately pinpoint the specific time of the fault occurrence, which is of great significance for subsequent fault analysis and handling.

[0090] In an optional embodiment, the system performs a comprehensive analysis based on the saved sampling data, combined with the window time and the total number of sampling points, to determine the nature and scope of the fault. For example, if the zero-sequence voltage values ​​of multiple consecutive sampling points exceed the threshold within 0.5 seconds, the system will determine that a persistent fault exists and take corresponding protective measures. In this way, the system can not only effectively identify intermittent grounding faults but also distinguish the duration of the fault, thereby providing a more reliable guarantee for the stable operation of the distribution network.

[0091] S103, calculate the cumulative parameters in the corresponding sampling window time when the judgment condition is met, and determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

[0092] In this embodiment of the application, calculating the cumulative parameter in the corresponding sampling window time when the judgment condition is met includes:

[0093] If the real-time zero-sequence voltage at the first target sampling point in the target distribution network meets the judgment condition, then mark this first target sampling point;

[0094] Obtain the sampling data of the first target sampling point within the sampling window time;

[0095] Based on the sampled data, the cumulative parameters are calculated using the first cumulative logic.

[0096] In an optional embodiment, the first accumulation logic is used to calculate the accumulation parameters, which can be achieved using methods such as weighted average, integral, or maximum value methods. The calculation results of the accumulation parameters are directly related to the judgment of intermittent grounding faults. For example, when using the weighted average method, different weights can be assigned to the data within the sampling window to reflect the importance of data at different time points. The integral method assesses the severity of the fault by calculating the integral of the voltage values ​​within the sampling window. The maximum value method focuses on the maximum voltage value within the sampling window to determine whether there are abnormal peak values. Through these methods, the system can comprehensively consider voltage fluctuations, thereby more accurately judging the occurrence of intermittent grounding faults. The calculation and analysis of accumulation parameters are key steps in the embodiments of this application. They not only improve the sensitivity of fault detection but also help reduce false alarms and missed alarms, ensuring the stable operation of the distribution network.

[0097] In this embodiment of the application, the first accumulation logic includes:

[0098] Determine the value of the first variable at the second target sampling point within the sampling window time;

[0099] Accumulate the values ​​of the first variable at all second target sampling points in the sampling window.

[0100] In this embodiment, the second target sampling point and the first target sampling point have different meanings. The first target sampling point is a user-defined sampling point in the distribution network, while the second target sampling point is a sampling point generated after sampling operations are performed within a window time. In this embodiment, determining the first variable value at the second target sampling point within each sampling window time includes:

[0101] If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then calculate the cumulative parameter in the corresponding sampling window time when the judgment condition is met;

[0102] If the real-time zero-sequence voltage at the first target sampling point is not greater than the first zero-sequence voltage threshold, then the cumulative parameters in the corresponding sampling window time when the judgment condition is met are not calculated.

[0103] In this embodiment of the application, determining the value of the first variable at the second target sampling point within the sampling window time step by step further includes:

[0104] If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then determine the relationship between the real-time admittance value at the first target sampling point and the second admittance threshold, the real-time conductance value at the first target sampling point and the third conductance threshold, and the real-time susceptance value at the first target sampling point and the fourth susceptance threshold.

[0105] If the real-time admittance value at any of the first target sampling points is greater than the second admittance threshold, or the real-time conductance value at the first target sampling point is greater than the third conductance threshold, or the real-time susceptance value at the first target sampling point is greater than the fourth susceptance threshold, then the first variable value is recorded as 1; otherwise, it is recorded as 0.

[0106] In this embodiment of the application, determining whether an intermittent ground fault has occurred in the target distribution network based on cumulative parameters includes:

[0107] Accumulate the values ​​of the first variable at all second target sampling points in the sampling window;

[0108] If the cumulative result of the first variable value at all second target sampling points in the sampling window is greater than the first cumulative threshold, then it is determined that an intermittent grounding fault has occurred in the target distribution network.

[0109] Otherwise, it is determined that no intermittent grounding fault has occurred in the target distribution network.

[0110] In an optional embodiment, intermittent arc fault identification is achieved by calculating the cumulative duration of intermittent arc faults within a set window time. The specific steps are as follows:

[0111] 1) Install monitoring equipment in the substation to sample the zero-sequence current of each feeder and arc suppression coil, as well as the zero-sequence current of the busbar;

[0112] 2) The first zero-sequence voltage threshold, the second admittance threshold, the third conductance threshold, and the fourth susceptance threshold are set using the user-defined method. The first zero-sequence voltage threshold U 0Set Second admittance threshold Y 0Set The third conductivity threshold G 0Set and the fourth susceptance threshold B 0Set The specific threshold settings are as follows:

[0113] First zero-sequence voltage threshold U 0Set Generally, 10V is used;

[0114] Second admittance threshold:

[0115]

[0116] I ub This is due to inconsistencies in CT scans, and the value can generally be taken as 20-30mA. 0T It is the sum of the capacitive currents of all lines. k is the reliability coefficient, which is taken as 1.2 in this application.

[0117] Third conductivity threshold G 0Set =kΔY, fourth susceptance threshold B 0Set =kΔY.

[0118] 3) Sample and calculate the zero-sequence voltage U0 point by point and determine whether it crosses the line; if U0 > U 0Set Then the sampled data is saved, with a window time of T. W The total number is N, T W Determined based on the time required to coordinate with protection or other systems, for example: 0.5 seconds.

[0119] 4) In T W Calculate point by point in the sampled data, if

[0120] (U0>U 0Set )&&(|Y0|>Y 0Set |||G0|>G 0Set ||B0>B 0Set If Δ(n) = 1, then Δ(n) = 0; otherwise, Δ(n) = 0.

[0121] 5) Calculate the cumulative duration of intermittent arc faults in the data window:

[0122]

[0123] Since N = f s T W , can be defined as:

[0124]

[0125] Calculate cnt(n) point by point: cnt(n-1) + Δ(n);

[0126] 6) If cnt > k a N is then determined to be an intermittent fault, where k a The discriminant coefficient can be set to 0.1 < k. a <0.5.

[0127] In an optional embodiment, such as Figure 3As shown, the process begins. Zero-sequence voltage, admittance, and other setpoints 201: Here, the standard values ​​for relevant parameters such as zero-sequence voltage and admittance need to be preset. Data sampling and processing 202: For each cycle, first check whether the zero-sequence voltage U0 is greater than the preset threshold U. 0Set Determine the zero-sequence voltage 203: If U0 > U 0Set If yes, proceed to step 204; otherwise, return to step 202. Determine other parameters 204: Check the zero-sequence admittance |Y0|>Y. 0Set Zero-sequence conductance |G0|>G 0Set And zero-sequence susceptance B0 > B 0Set Check if each condition exceeds its corresponding threshold. Accumulator 205: If all the above conditions are met, increment the counter cnt by cnt(n) = cnt(n-1) + Δ(n). Check the count value 206: Determine if the current sampling count n has reached or exceeded a predetermined threshold N. If n does not meet the condition, return to step 202 and continue the next data sampling and processing. Output 207: Determine if the current counter value cnt has reached or exceeded a predetermined proportion k. d N, if cnt exceeds k d If N is found, the output result indicates that an anomaly has been detected. If cnt does not meet the condition, return to step 202 to continue the next data sampling and processing.

[0128] This embodiment also provides a distribution network intermittent grounding fault identification system, including:

[0129] The threshold preset module is used to preset a first zero-sequence voltage threshold and establish a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold.

[0130] The first judgment module is used to preset the sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold.

[0131] The second judgment module is used to calculate the cumulative parameters in the corresponding sampling window time when the judgment conditions are met, and to determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

[0132] The above-mentioned unit modules can be embedded in the processor of the computer device in hardware form or independent of it, or they can be stored in the memory of the computer device in software form, so that the processor can call and execute the corresponding operations of the above modules.

[0133] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as follows. Figure 4As shown, the computer device includes a processor, memory, communication interface, display screen, and input devices connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs stored in the non-volatile storage media. The communication interface is used for wired or wireless communication with external terminals; wireless communication can be achieved through Wi-Fi, carrier networks, NFC (Near Field Communication), or other technologies. When executed by the processor, the computer program implements a method for identifying intermittent grounding faults in a power distribution network. The display screen can be an LCD screen or an e-ink screen. The input devices can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0134] This embodiment also provides a computer-readable storage medium on which a computer program is stored, and when the computer program is executed by a processor, it performs the following steps:

[0135] A first zero-sequence voltage threshold is preset, and a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold are established based on the first zero-sequence voltage threshold.

[0136] The sampling window time is preset to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold.

[0137] Calculate the cumulative parameters in the sampling window time corresponding to the judgment condition, and determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

[0138] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

[0139] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product implemented 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. The solutions in the embodiments of this application can be implemented in various computer languages, such as the object-oriented programming language Java and the interpreted scripting language JavaScript.

[0140] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. 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... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0141] 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.

[0142] 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.

[0143] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

[0144] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for identifying intermittent grounding faults in a distribution network, characterized in that, include: A first zero-sequence voltage threshold is preset, and a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold are established based on the first zero-sequence voltage threshold. The sampling window time is preset to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold. Calculate the cumulative parameters in the sampling window time corresponding to the judgment condition, and determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters; The cumulative parameters in the corresponding sampling window time when the calculation satisfies the judgment condition include: If the real-time zero-sequence voltage at the first target sampling point in the target distribution network meets the judgment condition, then mark this first target sampling point; Obtain the sampling data of the first target sampling point within the sampling window time; The cumulative parameter is calculated based on the sampled data and the first cumulative logic. The first accumulation logic includes: Determine the value of the first variable at the second target sampling point within the sampling window time; Accumulate the first variable values ​​at all second target sampling points in the sampling window; The step of determining the value of the first variable at the second target sampling point within the sampling window time includes: If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then calculate the cumulative parameter in the corresponding sampling window time when the judgment condition is met; If the real-time zero-sequence voltage at the first target sampling point is not greater than the first zero-sequence voltage threshold, then the cumulative parameters in the corresponding sampling window time when the judgment condition is met are not calculated. The step of judging the value of the first variable at the second target sampling point within the sampling window time also includes: If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then determine the relationship between the real-time admittance value at the first target sampling point and the second admittance threshold, the real-time conductance value at the first target sampling point and the third conductance threshold, and the real-time susceptance value at the first target sampling point and the fourth susceptance threshold. If the real-time admittance value at any of the first target sampling points is greater than the second admittance threshold, or the real-time conductance value at the first target sampling point is greater than the third conductance threshold, or the real-time susceptance value at the first target sampling point is greater than the fourth susceptance threshold, then the first variable value is recorded as 1; otherwise, it is recorded as 0.

2. The method for identifying intermittent grounding faults in a distribution network as described in claim 1, characterized in that, The preset sampling window time, and the determination of the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold, include: The sampling window time is a preset interval for saving the sampled data; Determine the relationship between the real-time zero-sequence voltage at the first target sampling point in the target distribution network and the first zero-sequence voltage threshold.

3. The method for identifying intermittent grounding faults in a distribution network as described in claim 2, characterized in that, The step of determining whether an intermittent ground fault has occurred in the target distribution network based on the accumulated parameters includes: Accumulate the first variable values ​​at all second target sampling points in the sampling window; If the cumulative result of the first variable value at all second target sampling points in the sampling window is greater than the first cumulative threshold, then it is determined that an intermittent grounding fault has occurred in the target distribution network. Otherwise, it is determined that no intermittent grounding fault has occurred in the target distribution network.

4. A distribution network intermittent grounding fault identification system applying the method described in claim 1, characterized in that, include: The threshold preset module is used to preset a first zero-sequence voltage threshold and establish a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold. The first judgment module is used to preset the sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold. The second judgment module is used to calculate the cumulative parameters in the corresponding sampling window time when the judgment conditions are met, and to determine whether the target distribution network has an intermittent grounding fault based on the cumulative parameters.

5. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that, When the processor executes the computer program, it implements the steps of the method according to any one of claims 1 to 3.

6. A computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by a processor, it implements the steps of the method according to any one of claims 1 to 3.

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