Intermittent grounding fault identification method and system for power distribution network

Abstract

The invention discloses a power distribution network intermittent grounding fault identification method and system. The method comprises the steps of presetting a first zero-sequence voltage threshold, and establishing a second admittance threshold, a third conductance threshold and a fourth susceptance threshold based on the first zero-sequence voltage threshold; presetting sampling window time, and judging the relationship between the real-time zero-sequence voltage of the target power distribution network and a first zero-sequence voltage threshold value; and calculating an accumulation parameter in the corresponding sampling window time when the judgment condition is met, and judging whether the intermittent grounding fault occurs in the target power distribution network according to the accumulation parameter. According to the method, the amplitude and admittance parameters of the power frequency zero-sequence voltage are measured, and calculation and judgment are carried out based on accumulated intermittent arc fault duration. The method is suitable for non-grounding and arc suppression coil grounding systems, and intermittent grounding faults can be accurately identified.

Description

Technical Field

[0001] The present invention relates to the technical field of intermittent grounding fault identification in a distribution network, and in particular to a method and system for identifying intermittent grounding faults in a distribution network. Background Art

[0002] Intermittent ground faults in distribution networks occur during operation due to intermittent discharges from the line to the ground caused by factors such as line aging, poor contact, and insufficient insulation between branches. This can lead to abnormal line voltage and current. The hidden, complex, and random nature of intermittent ground faults pose significant challenges to fault diagnosis. Intermittent faults can render some ground fault protection methods, such as the zero-sequence admittance method, ineffective. Furthermore, unclear fault type identification can hinder further decision-making in systems such as line ground 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 harmonic power, or analyze traveling waves generated by arc faults to detect faults.

[0004] High-frequency component analysis methods are generally based on Fast Fourier Transform (FFT) analysis, wavelet analysis, or harmonic power calculation. These methods use signal sampling frequencies ranging from 6.4kHz to hundreds of kHz. These frequency methods are often accompanied by complex signal processing and decision-making algorithms, such as fuzzy logic, eigenvector and vector inference engines, statistical confidence methods, statistical variance estimation, Hilbert transform methods, and ANN techniques. High sampling frequencies and complex decision-making algorithms are computationally intensive, requiring high-performance hardware and placing high demands on on-site equipment.

[0005] In addition, since the grounding resistance of intermittent arc faults changes nonlinearly and randomly, and its resistance value is large, the above method cannot avoid its influence. Summary of the Invention

[0006] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

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

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

[0009] In order to solve the above technical problems, the present invention provides the following technical solutions:

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

[0011] Presetting a first zero-sequence voltage threshold, and establishing a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold;

[0012] Preset the sampling window time to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold;

[0013] The cumulative parameter in the sampling window time corresponding to the judgment condition is calculated, and whether an intermittent ground fault occurs in the target distribution network is judged according to the cumulative parameter.

[0014] As a preferred solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, 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:

[0015] The sampling window time is a preset interval for saving sampling 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 solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, the cumulative parameters in the corresponding sampling window time when the calculation meets the judgment conditions include:

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

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

[0020] The accumulation parameter is calculated according to the sampling data in combination with a first accumulation logic.

[0021] As a preferred solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, the first accumulation logic includes:

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

[0023] Accumulate the first variable values ​​at all second target sampling points in the sampling window.

[0024] As a preferred solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, the step of determining the first variable value at the second target sampling point within the sampling window time one by one includes:

[0025] If the real-time zero-sequence voltage at the first target sampling point is greater than a first zero-sequence voltage threshold, calculating the cumulative parameter in the sampling window time corresponding to 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, the accumulated parameter in the sampling window time corresponding to when the judgment condition is met is not calculated.

[0027] As a preferred solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, the step of determining the first variable value at the second target sampling point within the sampling window time one by one further comprises:

[0028] If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, determining a relationship between the real-time admittance value at the first target sampling point and the second admittance threshold, a relationship between the real-time conductance value at the first target sampling point and the third conductance threshold, and a relationship between 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 first target sampling point 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, the value of the first variable is recorded as 1, otherwise it is recorded as 0.

[0030] As a preferred solution of the method for identifying intermittent grounding faults in a distribution network according to the present invention, the step of determining whether an intermittent grounding fault occurs in the target distribution network according to the accumulated parameters includes:

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

[0032] If the cumulative result of the first variable values ​​at all the second target sampling points in the sampling window is greater than the first cumulative threshold, it is determined that an intermittent ground fault occurs in the target distribution network;

[0033] Otherwise, it is determined that no intermittent ground fault occurs in the target distribution network.

[0034] In a second aspect, the present invention provides a distribution network intermittent grounding fault identification system, comprising:

[0035] A threshold preset module, configured 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] A first judgment module is used to preset a sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and a first zero-sequence voltage threshold;

[0037] The second judgment module is used to calculate the cumulative parameter in the sampling window time corresponding to the judgment condition when the judgment condition is met, and judge whether an intermittent grounding fault occurs in the target distribution network according to the cumulative parameter.

[0038] In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the above-described method when executing the computer program.

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

[0040] Compared with the prior art, the present invention has the following beneficial effects: The present invention proposes a method and system for identifying intermittent grounding faults in a distribution network, presetting a first zero-sequence voltage threshold, establishing a second admittance threshold, a third conductance threshold, and a fourth admittance threshold based on the first zero-sequence voltage threshold; presetting a sampling window time, and judging the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold; calculating the cumulative parameters in the corresponding sampling window time when the judgment conditions are met, and judging whether an intermittent grounding fault occurs 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 and judgments based on the cumulative duration of the intermittent arc fault. This method is applicable to ungrounded and arc suppression coil grounding systems, and can accurately identify intermittent grounding faults. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0042] Figure 1 A flow chart of a method and system for identifying intermittent grounding faults in a distribution network provided by one embodiment of the present invention;

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

[0044] Figure 3 A detailed algorithm flow chart of a method and system for identifying intermittent grounding faults in a distribution network provided by one embodiment of the present invention;

[0045] Figure 4 This is a diagram of the internal structure of a computer device in a method and system for identifying intermittent grounding faults in a distribution network provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0046] To make the above-mentioned objects, features, and advantages of the present invention more clearly understood, the following detailed description of the specific embodiments of the present invention is given in conjunction with the accompanying drawings. It is obvious that the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary persons in this field without creative work should fall within the scope of protection of the present invention.

[0047] Example 1

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

[0049] There are some technical problems in the existing related technologies. For example, in complex 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 above-mentioned problems. Next, we will describe in detail how to implement the method for identifying intermittent grounding faults in a distribution network in combination with multiple embodiments.

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

[0052] S101, presetting a first zero-sequence voltage threshold, and establishing 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 grounding occurs in the distribution line, the arc suppression coil grounding system can be equivalent to Figure 2 , Figure 1 Medium L C , G c is the neutral point arc suppression coil compensation inductance and conductance, G 0F 、C 0F , G 0H 、C 0H are the conductance and capacitance of the fault line, the conductance and capacitance of the non-fault line, R F is the ground fault resistance, U ph It is an 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 is the conductance and capacitance of the entire system, and k is the compensation coefficient of the arc suppression coil.

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

[0058]

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

[0060]

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

[0062]

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

[0064]

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

[0066] In an optional embodiment, as shown in formula (4), the admittance calculation is independent of the grounding resistance at the fault point. This can adapt to the nonlinear random variation of the grounding resistance at the fault point during grounding, and has good high-resistance fault detection capabilities. However, intermittent grounding can cause errors in the admittance calculation. Therefore, methods are needed to improve the operation of ground 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, line material, etc.

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

[0069] In the embodiment of the present application, 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 an optional embodiment, there are various 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. The user-defined method allows the operator to set thresholds based on actual grid operation and historical data, while the empirical formula method is determined based on typical parameters of the distribution network and historical fault data. The statistical analysis method uses statistical methods to determine reasonable thresholds by collecting a large amount of data under normal operation and fault conditions.

[0071] In an optional embodiment, intermittent ground faults can be effectively identified by setting appropriate thresholds. For example, when the zero-sequence voltage is detected to exceed the preset first zero-sequence voltage threshold, the system will start the fault identification program. The program will calculate the current admittance, conductance, and susceptance values ​​and compare them with the corresponding thresholds. If the calculated parameter value exceeds the threshold, the system will determine that an intermittent ground fault exists and perform the corresponding

[0072] In the embodiment of the present application, the user definition 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 , the second admittance threshold Y 0Set , the third conductance threshold G 0Set and the fourth susceptance threshold B 0Set , the specific threshold settings are as follows:

[0073] The first zero-sequence voltage threshold U 0Set Generally take 10V;

[0074] Second admittance threshold:

[0075]

[0076] I ub This is the difference caused by the inconsistency of CT, which can generally be taken as 20~30mA. 0T is the sum of the capacitive currents of all lines. k is the reliability coefficient, which is 1.2 in this application.

[0077] The third conductance threshold G 0Set =kΔY, the fourth susceptance threshold B 0Set =kΔY.

[0078] It should be noted that presetting a first zero-sequence voltage threshold and establishing a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold can improve the sensitivity and accuracy of fault detection. When the zero-sequence voltage exceeds the first zero-sequence voltage threshold, the system immediately responds and initiates a fault identification program. By calculating the admittance, conductance, and susceptance values ​​in real time and comparing them with the preset thresholds, it can quickly and accurately determine whether an intermittent ground fault exists. This method not only effectively identifies high-resistance faults but also has good adaptability for detecting intermittent ground faults. In addition, the thresholds set through 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, presetting a sampling window time, and determining the relationship between the real-time zero-sequence voltage of the target distribution network and a first zero-sequence voltage threshold;

[0080] In the embodiment of the present application, the sampling window time is preset, and the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold is determined, including:

[0081] The sampling window time is the preset interval for saving the sampling 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 optional embodiment, monitoring equipment can be 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 busbar. The real-time monitoring system can also be used to continuously track changes in the zero-sequence voltage. Real-time data can also be obtained in other ways, for example, using a wireless sensor network or a remote monitoring system.

[0084] In an embodiment of the present 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 busbar.

[0085] In an optional embodiment, the preset interval can be designed based on the specific needs of technicians. For example, it can be set between 100ms and 500ms to ensure that the characteristic signals of intermittent ground faults are captured. The sampling window time should not be too long to avoid missing transient changes in the fault signal; nor should it be too short to avoid misjudgment due to noise interference. In actual applications, the sampling window time can be appropriately adjusted based on the specific conditions of the distribution network and the fault characteristics to achieve optimal fault detection results.

[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 the distribution network has multiple branch lines, the target sampling point can be set at the end of each branch line to capture fault signals from each branch line. In addition, the selection of sampling points should also take into account the protection strategy and fault location requirements of the distribution network to ensure that the fault point can be quickly and accurately located when a fault occurs.

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

[0088] In the embodiments of this application, Figure 3 As shown, the zero-sequence voltage U0 is sampled and calculated point by point and judged whether it crosses the line; if U0>U 0Set , then save the sampling data, the window time is T W , the total number is N, T W Determined by the coordination time with protection or other systems, for example: 0.5 seconds.

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

[0090] In an optional embodiment, the system performs a comprehensive analysis based on the stored sampled 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 ​​at multiple consecutive sampling points exceed the threshold within 0.5 seconds, the system will determine that a persistent fault exists and take appropriate protective measures. In this way, the system can not only effectively identify intermittent ground faults, but also distinguish the duration of the fault, thereby providing more reliable protection for the stable operation of the distribution network.

[0091] S103, calculating the cumulative parameter in the sampling window time corresponding to when the judgment condition is met, and judging whether an intermittent grounding fault occurs in the target distribution network according to the cumulative parameter.

[0092] In the embodiment of the present 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 and the first zero-sequence voltage threshold meet the judgment condition, then mark the first target sampling point;

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

[0095] The accumulation parameter is calculated based on the sampled data in combination with the first accumulation logic.

[0096] In an optional embodiment, the first accumulation logic is to calculate the cumulative parameters, and the methods that can be used include weighted average method, integral method or maximum method. The calculation results of the cumulative parameters will be 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 rule evaluates the severity of the fault by calculating the integral of the voltage value within the sampling window. The maximum rule focuses on the maximum voltage value within the sampling window to determine whether there is an abnormal peak. Through these methods, the system can comprehensively consider the voltage fluctuations, so as to more accurately judge the occurrence of intermittent grounding faults. The calculation and analysis of cumulative parameters are key steps in the embodiments of the present application. It not only improves the sensitivity of fault detection, but also helps to reduce false alarms and missed alarms, ensuring the stable operation of the distribution network.

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

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

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

[0100] In this embodiment of the present application, the second target sampling point has a different meaning from the first target sampling point. The first target sampling point is a sampling point in the distribution network defined by the user, while the second target sampling point is a sampling point generated after the sampling operation is performed during the window time. In this embodiment of the present application, determining the value of the first variable at the second target sampling point within the sampling window time one by one includes:

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

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

[0103] In the embodiment of the present application, determining the first variable value at the second target sampling point within the sampling window time one by one 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, determining 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 first target sampling point 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, the value of the first variable is recorded as 1, otherwise it is recorded as 0.

[0106] In the embodiment of the present application, determining whether an intermittent ground fault occurs in the target distribution network according to the accumulated parameters includes:

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

[0108] If the cumulative result of the first variable values ​​at all the second target sampling points in the sampling window is greater than the first cumulative threshold, it is determined that an intermittent ground fault occurs in the target distribution network;

[0109] Otherwise, it is determined that no intermittent ground fault occurs in the target distribution network.

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

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

[0112] 2) Use the user definition method 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 , the second admittance threshold Y 0Set , the third conductance threshold G 0Set and the fourth susceptance threshold B 0Set , the specific threshold settings are as follows:

[0113] The first zero-sequence voltage threshold U 0Set Generally take 10V;

[0114] Second admittance threshold:

[0115]

[0116] I ub This is the difference caused by the inconsistency of CT, which can generally be taken as 20~30mA. 0T is the sum of the capacitive currents of all lines. k is the reliability coefficient, which is 1.2 in this application.

[0117] The third conductance threshold G 0Set =kΔY, the 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 save the sampling data, the window time is T W , the total number is N, T W Determined by the coordination time 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 ) then Δ(n)=1, otherwise Δ(n)=0;

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

[0122]

[0123] Since N = f s T W , we can define:

[0124]

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

[0126] 6) If cnt>k a N is judged as an intermittent fault, where k a is the discrimination coefficient, which can be taken as 0.1<k a <0.5.

[0127] In an optional embodiment, if Figure 3As shown, the process starts. Zero sequence voltage, admittance and other fixed value settings 201: Here, it is necessary to pre-set the standard values ​​of zero sequence voltage, admittance and other related parameters. 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 zero sequence voltage 203: If U0>U 0Set , then proceed to the next step 204; otherwise return to step 202. Determine other parameters 204: Check zero sequence admittance |Y0|>Y 0Set 、Zero sequence conductance |G0|>G 0Set , and zero sequence susceptance B0>B 0Set Accumulative counter 205: If all the above conditions are met, the value of counter cnt is increased by cnt(n)=cnt(n-1)+Δ(n), and the count value is judged 206: whether the current sampling number n reaches or exceeds a predetermined threshold value N. If n does not meet the conditions, return to step 202 and continue the next data sampling and processing process. Output 207: whether the current counter value cnt reaches or exceeds a predetermined ratio k d N, if cnt exceeds k d N, then output the result, indicating that an abnormality has been detected. If cnt does not meet the conditions, then return to step 202 to continue the next data sampling and processing process.

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

[0129] A threshold preset module, configured 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] A first judgment module is used to preset a sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and a first zero-sequence voltage threshold;

[0131] The second judgment module is used to calculate the cumulative parameter in the corresponding sampling window time when the judgment condition is met, and judge whether an intermittent grounding fault occurs in the target distribution network according to the cumulative parameter.

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

[0133] This embodiment also provides a computer device, which may be a terminal, and its internal structure diagram may be as shown in FIG. Figure 4As shown. The computer device includes a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner can be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. When the computer program is executed by the processor, a method for identifying intermittent grounding faults in a distribution network is implemented. The display screen of the computer device can be a liquid crystal display screen or an electronic ink display screen, and the input device of the computer device can be a touch layer covering the display screen, or a button, trackball or touchpad provided on the computer device housing, or an external keyboard, touchpad or mouse.

[0134] This embodiment further provides a computer-readable storage medium having a computer program stored thereon. When the computer program is executed by a processor, the following steps are implemented:

[0135] Presetting a first zero-sequence voltage threshold, and establishing a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold;

[0136] Preset the sampling window time to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold;

[0137] The cumulative parameters in the corresponding sampling window time when the judgment conditions are met are calculated, and whether an intermittent ground fault occurs in the target distribution network is determined 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 the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

[0139] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the application can adopt 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.) that contain computer-usable program code. The scheme in the embodiment of the present application can be implemented in various computer languages, for example, object-oriented programming language Java and literal translation scripting language JavaScript, etc.

[0140] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0141] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0142] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0143] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present application.

[0144] Obviously, those skilled in the art may make various changes and modifications to this application without departing from the spirit and scope of this application. Thus, if these modifications and variations of this application fall within the scope of the claims of this application and their equivalents, this application is intended to include these modifications and variations.

Claims

1. A method for identifying intermittent grounding faults in a distribution network, characterized in that: include: Presetting a first zero-sequence voltage threshold, and establishing a second admittance threshold, a third conductance threshold, and a fourth susceptance threshold based on the first zero-sequence voltage threshold; Preset the sampling window time to determine the relationship between the real-time zero-sequence voltage of the target distribution network and the first zero-sequence voltage threshold; The cumulative parameter in the corresponding sampling window time when the judgment condition is met is calculated, and whether an intermittent grounding fault occurs in the target distribution network is judged according to the cumulative parameter.

2. The method for identifying intermittent grounding faults in a distribution network according to 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 sampling 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 according to claim 2, characterized in that: The calculation of the accumulated parameters in the corresponding sampling window time when the judgment condition is met includes: If the real-time zero-sequence voltage at the first target sampling point in the target distribution network and the first zero-sequence voltage threshold meet the judgment condition, then mark the first target sampling point; Acquire sampling data of the first target sampling point within the sampling window time; The accumulation parameter is calculated according to the sampling data in combination with a first accumulation logic.

4. The method for identifying intermittent grounding faults in a distribution network according to claim 3, characterized in that: The first accumulation logic includes: Determine the first variable value at the second target sampling point within the sampling window time one by one; The first variable values ​​at all the second target sampling points in the sampling window are accumulated.

5. The method for identifying intermittent grounding faults in a distribution network according to claim 4, characterized in that: The step of determining the first variable value at the second target sampling point within the sampling window time one by one comprises: If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, then calculating 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, the accumulated parameter in the corresponding sampling window time when the judgment condition is met is not calculated.

6. The method for identifying intermittent grounding faults in a distribution network according to claim 5, characterized in that: The step of determining the first variable value at the second target sampling point within the sampling window time one by one further includes: If the real-time zero-sequence voltage at the first target sampling point is greater than the first zero-sequence voltage threshold, determining 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 there is a real-time admittance value at any first target sampling point greater than the second admittance threshold, or a real-time conductance value at the first target sampling point greater than the third conductance threshold, or a real-time susceptance value at the first target sampling point greater than the fourth susceptance threshold, the value of the first variable is recorded as 1, otherwise it is recorded as 0.

7. The method for identifying intermittent grounding faults in a distribution network according to claim 6, characterized in that: The step of judging whether an intermittent ground fault occurs in the target distribution network according to the accumulated parameters comprises: Accumulating the first variable values ​​at all second target sampling points in the sampling window; If the cumulative result of the first variable values ​​at all the second target sampling points in the sampling window is greater than the first cumulative threshold, it is determined that an intermittent grounding fault occurs in the target distribution network; Otherwise, it is determined that no intermittent grounding fault occurs in the target distribution network.

8. A distribution network intermittent grounding fault identification system, characterized in that: include: A threshold preset module, 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; A first judgment module is used to preset a sampling window time and judge the relationship between the real-time zero-sequence voltage of the target distribution network and a first zero-sequence voltage threshold; The second judgment module is used to calculate the cumulative parameter in the corresponding sampling window time when the judgment condition is met, and judge whether an intermittent grounding fault occurs in the target distribution network according to the cumulative parameter.

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the method according to any one of claims 1 to 7 are implemented.

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

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