Single-phase earth fault line selection method and device and computer readable storage medium

Abstract

The invention belongs to the technical field of power system fault line selection, and relates to a single-phase earth fault line selection method and device and a computer readable storage medium, and the method comprises the steps: collecting zero-sequence current time sequence data of each line within a preset time after a fault occurs, and calculating a zero-sequence current variance value, a zero-sequence current amplitude value and a zero-sequence current phase of each line; selecting the maximum zero-sequence current variance value from the zero-sequence current variance values of all the lines, and judging the size of the maximum zero-sequence current variance value and a preset threshold value; if the maximum zero-sequence current variance value is smaller than a preset threshold value, determining a grounding fault line based on the zero-sequence current amplitudes and the zero-sequence current phases of all lines; and if the maximum zero-sequence current variance value is greater than or equal to a preset threshold value, determining a grounding fault line based on the zero-sequence current variance values and the zero-sequence current phases of all lines. According to the scheme, the problem that the ground fault line selection result is wrong due to the fact that zero-sequence current acquisition is wrong due to installation errors of the zero-sequence current transformer is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of power system fault line selection, and particularly to a single-phase grounding fault line selection method, device and computer-readable storage medium. Background Art

[0002] Single-phase grounding faults are high-frequency faults in 10 kV distribution networks. As a small current grounding system, when a single-phase grounding fault occurs in the distribution network, the load current and line voltage are still symmetrical. Therefore, in traditional power systems, it is stipulated that the distribution network can continue to operate for no more than 2 hours after a single-phase grounding fault occurs. With the gradual expansion of the scale of cable applications, the elevated phase voltage during single-phase grounding may break down the weak points of the cable, triggering group injuries such as fires in the same trench cables. Therefore, it is necessary to quickly locate and isolate the grounded line after a single-phase grounding fault occurs.

[0003] When a single-phase grounding fault occurs, a zero-sequence voltage will appear at the fault point. Under the action of the zero-sequence voltage, a zero-sequence current will be generated in the distribution network. Since the zero-sequence current in the fault line flows from the fault point to the bus, its magnitude is equal to the sum of the capacitive currents of all non-fault lines, and the zero-sequence current of the non-fault line flows from the bus to the line, and its magnitude is equal to the capacitive current of that line. Therefore, the grounding fault line selection methods in the prior art utilize this characteristic to install zero-sequence current transformers on each line of the distribution network, collect the zero-sequence current in each line in real time, and determine the line with the opposite phase to other lines among the lines with larger zero-sequence current amplitudes as the fault line by calculating the zero-sequence current amplitudes of each line. If the phases of the lines with larger amplitudes are the same, it is determined that the bus has a fault.

[0004] However, the prior art ignores that in an actual fault scenario, the zero-sequence current of the fault line is divided into two parts. As Figure 1 shown, when a ground fault occurs in phase A of the cable line, most of the zero-sequence current passes through the ground to the cable joint grounding wire, then through the shielding layer and the fault point into the bus. The value of this part of the zero-sequence current is , and a small part of the zero-sequence current directly flows into the bus through the ground and the fault point. The value of this part of the zero-sequence current is . When collecting the zero-sequence current of the line, if the zero-sequence current transformer of the line where the fault point is located does not wrap the cable joint grounding wire of this line during installation, only a small part of the zero-sequence current on this line can be collected , resulting in a wrong line selection when judging the fault line based on the amplitude of the zero-sequence current, thereby prolonging the single-phase grounding fault location and isolation time and affecting the safe and stable operation of the distribution network.

[0005] In summary, the existing single-phase grounding fault line selection methods ignore the problem that due to the incorrect installation of zero-sequence current transformers, only a small part of the zero-sequence current on the line can be collected, which in turn leads to incorrect grounding fault line selection results based on zero-sequence current. Summary of the Invention

[0006] For this reason, the technical problem to be solved by the present invention is to overcome the problem in the existing single-phase grounding fault line selection method that due to the incorrect installation of zero-sequence current transformers, only a small part of the zero-sequence current on the line can be collected, which in turn leads to incorrect grounding fault line selection results based on zero-sequence current.

[0007] To solve the above technical problem, the present invention provides a single-phase grounding fault line selection method, including: Collect the zero-sequence current time series data of each line in the distribution network within a preset time after a fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line; Select the maximum zero-sequence current variance value among the zero-sequence current variance values of all lines, and judge the size relationship between the maximum zero-sequence current variance value and a preset threshold; If the maximum zero-sequence current variance value is less than the preset threshold, determine the grounding fault line based on the zero-sequence current amplitude and zero-sequence current phase of all lines; If the maximum zero-sequence current variance value is greater than or equal to the preset threshold, determine the grounding fault line based on the zero-sequence current variance value and zero-sequence current phase of all lines.

[0008] Preferably, determining the grounding fault line based on the zero-sequence current variance value and zero-sequence current phase of all lines includes: Compare the zero-sequence current phases of the k lines with the largest zero-sequence current variance values; If there exists a th line whose zero-sequence current phase is opposite to the zero-sequence current phases of the remaining k - 1 lines, then determine the th line as the grounding fault line; ; If the zero-sequence current phases of the k lines are all the same, then determine a bus grounding fault.

[0009] Preferably, the value range of the preset threshold is [0.04, 0.06].

[0010] Preferably, the value range of the preset time is [1s, 10s].

[0011] Preferably, the value range of k is [3, 5].

[0012] Preferably, determining the grounding fault line based on the zero-sequence current amplitude and zero-sequence current phase of all lines includes: Compare the zero-sequence current phases of the m lines with the largest zero-sequence current amplitudes; If there exists the th line whose zero-sequence current phase is opposite to that of the remaining m - 1 lines, then determine that the th line is the grounding fault line; ; If the zero-sequence current phases of the m lines are all the same, then determine a bus grounding fault.

[0013] Preferably, the value range of m is [3, 5].

[0014] Preferably, the calculation formula for the zero-sequence current variance value is: , wherein, represents the zero-sequence current variance value; represents the number of zero-sequence currents in the collected zero-sequence current time series data; represents the th zero-sequence current in the collected zero-sequence current time series data; represents the average value of all zero-sequence currents in the collected zero-sequence current time series data; , represents the sampling frequency.

[0015] The present invention also provides a single-phase grounding fault line selection device, including: A data acquisition and calculation module, configured to acquire the zero-sequence current of each line in the distribution network and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line within a preset time; A data comparison module, configured to select the largest zero-sequence current variance value among the zero-sequence current variance values of all lines and determine the magnitude relationship between the largest zero-sequence current variance value and a preset threshold; A first grounding fault line selection module, configured to, if the largest zero-sequence current variance value is less than the preset threshold, determine the grounding fault line based on the zero-sequence current amplitudes and zero-sequence current phases of all lines; A second grounding fault line selection module, configured to, if the largest zero-sequence current variance value is greater than or equal to the preset threshold, determine the grounding fault line based on the zero-sequence current variance values and zero-sequence current phases of all lines.

[0016] The present invention also provides a computer-readable storage medium, on which a computer program is stored, and when the computer program is executed by a processor, the steps of the above single-phase grounding fault line selection method are implemented.

[0017] The single-phase grounding fault line selection method provided by this application has the following beneficial effects: 1. In this application, it is found that when a single-phase grounding fault occurs, although the total zero-sequence current value on the faulty line is a constant value and always equal to the capacitive current of all non-faulty lines, due to the unstable resistance value between the fault point and the ground, both the part of the zero-sequence current that flows through the ground to the grounding wire of the cable joint, then through the shielding layer and the fault point into the bus, and the part of the zero-sequence current that directly flows through the fault point into the bus after passing through the ground will show relatively frequent fluctuations. Based on this, in the preset time when a single-phase grounding fault occurs, this application collects the zero-sequence current of each line, calculates the variance value, amplitude, and phase of the zero-sequence current of each line, uses the variance value of the zero-sequence current to reflect the fluctuation of the zero-sequence current of each line, and determines whether the maximum variance value of the zero-sequence current exceeds the preset threshold. If the maximum variance value of the zero-sequence current is less than the preset threshold, it indicates that the zero-sequence current of all lines is relatively stable, that is, the zero-sequence current collected from each line is the total zero-sequence current value, and the zero-sequence current is collected correctly. Therefore, the faulty line can be directly selected based on the amplitude and phase of the zero-sequence current. If the maximum variance value of the zero-sequence current is greater than or equal to the preset threshold, it indicates that the zero-sequence current collected from some lines is partial zero-sequence current and has large fluctuations. At this time, the faulty line cannot be accurately selected based on the amplitude and phase of the zero-sequence current. Therefore, it is necessary to select the faulty line based on the variance value and phase of the zero-sequence current of each line. This application can accurately determine the grounding fault line based on the stability of the zero-sequence current even when the zero-sequence current transformer is installed incorrectly, resulting in incorrect zero-sequence current collection.

[0018] 2. Due to the influence of the transition resistance at the fault point, the fluctuations of the two parts of the zero-sequence current on the faulty line will be significantly greater than those of other non-faulty lines. Therefore, when the zero-sequence current collected from some lines is partial zero-sequence current, the line with the largest zero-sequence current fluctuation is the grounding fault line. To ensure the accuracy of the line selection result, this application determines the grounding fault line by comparing the phases of multiple lines with relatively large zero-sequence current fluctuations, further ensuring the accuracy of the grounding fault line selection. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to make the content of the present invention easier to be clearly understood, the following further describes the present invention in detail according to the specific embodiments of the present invention and in combination with the accompanying drawings, where: Figure 1 is a schematic diagram of a single-phase grounding fault provided by this application; Figure 2 is a flowchart of a method for selecting a single-phase grounding fault line provided by this application; Figure 3 is a schematic structural diagram of a device for selecting a single-phase grounding fault line provided by this application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0020] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments given are not intended to limit the present invention.

[0021] As Figure 1 shown, when the insulation layer of phase A of the cable line is punctured, a ground short circuit is formed with the metal shielding layer and its grounding wire, resulting in the voltage of phase A of the cable line being 0. If the voltage of the load current on the line impedance is ignored, the voltage of phase A and the capacitive current of phase A of all lines in the entire distribution network are both 0. However, there is still capacitive current in phases B and C of the line, and these capacitive currents ultimately flow to the grounding point of the faulty cable line. Therefore, the zero-sequence current of the faulty line is the phasor sum of the capacitive currents of all non-faulty lines in the entire distribution network. Most of the zero-sequence current will pass through the ground to the grounding wire of the cable joint, then through the shielding layer and the fault point into the distribution network, and a small part of the zero-sequence current will directly flow into the distribution network from the ground through the fault point. Therefore, when using a zero-sequence current transformer to detect the zero-sequence current of the line, only by wrapping the zero-sequence current transformer around the grounding wire of the cable joint can all the zero-sequence current on the line be collected.

[0022] In the actual detection process, since the zero-sequence current transformers are all installed manually, there will be problems of partial incorrect installation. If the zero-sequence current transformer on the faulty line is installed incorrectly, only a small part of the zero-sequence current can be detected. At this time, when selecting the grounding fault line by comparing the amplitudes and phases of the zero-sequence currents of each line, due to the incorrect collection of the zero-sequence current of the faulty line, its zero-sequence current amplitude is small and it is directly determined as a non-faulty line. The zero-sequence current amplitudes of multiple non-faulty lines are large, so their zero-sequence current phases are the same, thus directly determining a bus fault, resulting in incorrect line selection.

[0023] To solve the above problems, the present application provides a single-phase grounding fault line selection method, as Figure 2 shown, the method specifically includes: S10: Collect the zero-sequence current time series data of each line in the distribution network within a preset time after the fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line.

[0024] Specifically, a zero-sequence current transformer is used to collect the zero-sequence current of each line at a preset sampling frequency. For example, the sampling frequency can be 0.1 s.

[0025] The calculation formula for the zero-sequence current variance value is: , where represents the zero-sequence current variance value; represents the number of zero-sequence currents in the collected zero-sequence current time series data; represents the th zero-sequence current in the collected zero-sequence current time series data; represents the mean value of all zero-sequence currents in the collected zero-sequence current time series data; , represents the sampling frequency.

[0026] S20: Select the maximum zero-sequence current variance value among the zero-sequence current variance values of all lines, and judge the magnitude relationship between the maximum zero-sequence current variance value and the preset threshold.

[0027] S30: If the maximum zero-sequence current variance value is less than the preset threshold, determine the faulty line based on the zero-sequence current amplitude and zero-sequence current phase of all lines.

[0028] S40: If the maximum zero-sequence current variance value is greater than or equal to the preset threshold, determine the faulty line based on the zero-sequence current variance value and zero-sequence current phase of all lines.

[0029] This application finds that although the total zero-sequence current on the faulty line is always equal to the sum of the capacitive currents of the non-faulty lines, due to the unstable resistance value between the fault point and the ground, the two parts of the zero-sequence current on the faulty line fluctuate relatively frequently. Therefore, this application utilizes this characteristic to first calculate the zero-sequence current variance of each line to reflect the fluctuation of the zero-sequence current on each line. If the maximum zero-sequence current variance is less than the preset threshold, it indicates that the zero-sequence currents of all lines are relatively stable, proving that the zero-sequence current acquisition is correct, and the faulty line can be directly selected based on the amplitude and phase of the zero-sequence current. If the maximum zero-sequence current variance is greater than or equal to the preset threshold, it indicates that there is a large fluctuation in the zero-sequence current of some lines. At this time, there is a problem that the zero-sequence current transformer on the faulty line is installed incorrectly, resulting in the acquisition of partial zero-sequence current. Therefore, it is necessary to jointly determine the faulty line based on the zero-sequence current variance and phase.

[0030] Further, determining the faulty line based on the zero-sequence current amplitude and zero-sequence current phase of all lines includes: Comparing the zero-sequence current phases of the m lines with the largest zero-sequence current amplitudes.

[0031] Specifically, the value range of m is [3, 5]. For example: the 3, 4, or 5 lines with the largest zero-sequence current amplitudes can be selected, and their zero-sequence current phases are compared. Preferably, the value of m is 3. By comparing the 3 lines with the largest zero-sequence current amplitudes as candidate lines, the faulty line can be reliably selected without making the calculation and judgment process too cumbersome.

[0032] If there is a If the zero-sequence current phase of one line is opposite to the zero-sequence current phases of the remaining m - 1 lines, then it is determined that the th line is the line with a ground fault; .

[0033] If the zero-sequence current phases of all m lines are the same, then it is determined that there is a busbar ground fault.

[0034] Furthermore, due to the influence of the transition resistance between the fault point and the ground, the fluctuation of the zero-sequence current on the fault line will be significantly greater than that of the zero-sequence current on other lines. Therefore, when the maximum zero-sequence current variance is greater than or equal to the preset threshold, generally, it can be directly determined that the line corresponding to the maximum zero-sequence current variance is the line with a ground fault. However, in order to further ensure the accuracy of the line selection result, the method for determining the line with a ground fault based on the zero-sequence current variances and zero-sequence current phases of all lines in this application includes: Compare the zero-sequence current phases of the k lines with the largest zero-sequence current variances.

[0035] Specifically, similar to the ground fault line selection based on the zero-sequence current amplitude, the value range of k is [3, 5]. For example: the 3, 4, or 5 lines with the largest zero-sequence current variances can be selected, and their zero-sequence current phases are compared. Preferably, the value of k is 3. By comparing the 3 lines with the largest zero-sequence current variances as candidate lines, the line with a ground fault can be reliably selected, and the calculation and judgment process will not be too cumbersome.

[0036] If there is a th line whose zero-sequence current phase is opposite to the zero-sequence current phases of the remaining k - 1 lines, then it is determined that the th line is the line with a ground fault; .

[0037] If the zero-sequence current phases of all k lines are the same, then it is determined that there is a busbar ground fault.

[0038] Furthermore, in some embodiments of this application, the value range of the preset threshold is [0.04, 0.06]. For example: the value of the preset threshold can be 0.04, 0.05, or 0.06. When the value of the preset threshold is relatively small, the normal fluctuation of the zero-sequence current may be regarded as the zero-sequence current fluctuation caused by acquisition errors. When the value of the preset threshold is too large, the zero-sequence current fluctuation caused by the installation error of the zero-sequence current transformer will not be accurately identified, and it is mistakenly considered that the zero-sequence currents of all lines are collected correctly, thus leading to incorrect line selection. Through a large number of experiments in this application, it is found that when the value of the preset threshold is 0.05, the accuracy of the ground fault line selection result reaches the highest.

[0039] Further, the value range of the preset time is [1 s, 10 s]. For example, the zero-sequence current of the line can be collected within 1 s, 2 s, 3 s, 4 s, 5 s, 6 s, 7 s, 8 s, 9 s, and 10 s after the occurrence of the grounding fault. As a specific example of the present application, the zero-sequence current of each line within 1 s after the occurrence of the grounding fault is collected. This is because within a short time after the occurrence of the grounding fault, the characteristics of the zero-sequence current on the faulty line and the non-faulty line are significantly different. As time goes by, the situation at the fault point tends to be stable, which will increase the difficulty of selecting the grounding fault line. Through experiments, the present application found that generally, the grounding fault line can be accurately determined based on the zero-sequence current within 10 s after the occurrence of the fault.

[0040] Based on the single-phase grounding fault line selection method provided in the above embodiment, an embodiment of the present application further provides a single-phase grounding fault line selection device, as Figure 3 shown. The device specifically includes: A data acquisition and calculation module 10, configured to collect the zero-sequence current of each line in the distribution network and calculate the variance value, amplitude, and phase of the zero-sequence current of each line within the preset time.

[0041] A data comparison module 20, configured to select the maximum zero-sequence current variance value among the zero-sequence current variance values of all lines and determine the magnitude relationship between the maximum zero-sequence current variance value and the preset threshold.

[0042] A first grounding fault line selection module 30, configured to, if the maximum zero-sequence current variance value is less than the preset threshold, determine the grounding fault line based on the amplitude and phase of the zero-sequence current of all lines.

[0043] A second grounding fault line selection module 40, configured to, if the maximum zero-sequence current variance value is greater than or equal to the preset threshold, determine the grounding fault line based on the zero-sequence current variance value and the phase of the zero-sequence current of all lines.

[0044] An embodiment of the present application further provides a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the steps of the above single-phase grounding fault line selection method are implemented.

[0045] The technical solution of the present application will be described in more detail below with reference to multiple embodiments. It should be understood that the following embodiments are only for explaining and illustrating the technical solution and do not limit the scope of the present application.

[0046] Embodiment 1

[0047] This embodiment provides a single-phase grounding fault line selection method, which includes: S100: Collect the zero-sequence current time series data of each line in the distribution network within 1 s after a fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line.

[0048] S200: Select the maximum zero-sequence current variance value from the zero-sequence current variance values of all lines, and determine the magnitude relationship between the maximum zero-sequence current variance value and the preset threshold; the value of the preset threshold is 0.05.

[0049] S300: If the maximum zero-sequence current variance value is less than the preset threshold, compare the zero-sequence current phases of the 3 lines with the largest zero-sequence current amplitudes, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 3 lines are the same, determine a bus fault.

[0050] S400: If the maximum zero-sequence current variance value is greater than or equal to the preset threshold, compare the zero-sequence current phases of the 3 lines with the largest zero-sequence current variance values, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 3 lines are the same, determine a bus fault.

[0051] Embodiment 2

[0052] This embodiment provides a method for selecting a single-phase ground fault line, and the method includes: S100: Collect the zero-sequence current time series data of each line in the distribution network within 5 s after a fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line.

[0053] S200: Select the maximum zero-sequence current variance value from the zero-sequence current variance values of all lines, and determine the magnitude relationship between the maximum zero-sequence current variance value and the preset threshold; the value of the preset threshold is 0.04.

[0054] S300: If the maximum zero-sequence current variance value is less than the preset threshold, compare the zero-sequence current phases of the 4 lines with the largest zero-sequence current amplitudes, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 4 lines are the same, determine a bus fault.

[0055] S400: If the maximum zero-sequence current variance value is greater than or equal to the preset threshold, compare the zero-sequence current phases of the 4 lines with the largest zero-sequence current variance values, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 4 lines are the same, determine a bus fault.

[0056] Embodiment 3

[0057] This embodiment provides a method for selecting a single-phase ground fault line, and the method includes: S100: Collect the zero-sequence current time series data of each line in the distribution network within 10 s after a fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude, and zero-sequence current phase of each line.

[0058] S200: Select the maximum zero-sequence current variance value among the zero-sequence current variance values of all lines, and judge the magnitude relationship between the maximum zero-sequence current variance value and a preset threshold; the value of the preset threshold is 0.06.

[0059] S300: If the maximum zero-sequence current variance value is less than the preset threshold, compare the zero-sequence current phases of the 5 lines with the largest zero-sequence current amplitudes, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 5 lines are all the same, determine a bus fault.

[0060] S400: If the maximum zero-sequence current variance value is greater than or equal to the preset threshold, compare the zero-sequence current phases of the 5 lines with the largest zero-sequence current variance values, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 5 lines are all the same, determine a bus fault.

[0061] Comparative example This comparative example provides a single-phase ground fault line selection method, and the method includes: S100: Collect the zero-sequence current time series data of each line in the distribution network within 1 s after a fault occurs, and calculate the zero-sequence current amplitude and zero-sequence current phase of each line.

[0062] S200: Compare the zero-sequence current phases of the 3 lines with the largest zero-sequence current amplitudes, and determine the line with the zero-sequence current phase opposite to that of other lines as the ground fault line. If the zero-sequence current phases of the 3 lines are all the same, determine a bus fault.

[0063] Based on the methods provided in the above-mentioned Embodiments 1 to 3, this application has conducted a large number of experiments, and respectively calculated the ground fault line selection accuracy rate of the methods provided in each embodiment and the time duration from the occurrence of the ground fault to the determination of the fault line, and obtained the results shown in Table 1 below: Table 1 Line selection accuracy Line selection duration Example 1 98.7% 1.1s Example 2 98.2% 1.7s Example 3 97.6% 2.1s Comparative example 89% 0.67s As can be seen from the data in the table, the line selection accuracy of the single-phase grounding fault line selection method provided in this application is greater than 97%, while the accuracy of the existing grounding fault line selection method based on the zero-sequence current amplitude and zero-sequence current phase given in the comparative example is only 89%. It can be seen that the existing grounding fault line selection method is greatly affected by the incorrect installation of the zero-sequence current transformer, while the method provided in this application avoids the influence of this factor on the line selection result; by comparing the line selection accuracies of Examples 1 to 3, it can be found that when the value of the preset threshold is 0.05, the line selection accuracy reaches the maximum, indicating that 0.05 can accurately reflect the zero-sequence current fluctuation characteristics caused by the grounding of the fault point; by comparing the line selection duration, it can be found that as the number of candidate lines increases, the judgment process of the zero-sequence current phase becomes more complex, so the line selection duration gradually increases.

[0064] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present 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.

[0065] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of the processes and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0066] These computer program instructions can 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 generate a manufactured article including an instruction device, and the instruction device realizes the specified functions in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0067] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus, so that a series of operation steps are performed on the computer or other programmable apparatus to produce a computer-implemented process, and thus the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one process or a plurality of processes and / or blocks Figure 1 one process or a plurality of processes and / or blocks Figure 1 steps of a block or a plurality of blocks.

[0068] Obviously, the above embodiments are only examples for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to exhaustively list all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A single-phase ground fault line selection method, characterized in that: include: Collect zero-sequence current time series data of each line in the distribution network within a preset time after the fault occurs, and calculate the zero-sequence current variance value, zero-sequence current amplitude and zero-sequence current phase of each line; Selecting the largest zero-sequence current variance value from the zero-sequence current variance values ​​of all lines, and determining the magnitude between the largest zero-sequence current variance value and a preset threshold value; If the maximum zero-sequence current variance value is less than a preset threshold, the ground fault line is determined based on the zero-sequence current amplitude and zero-sequence current phase of all lines; If the maximum zero-sequence current variance value is greater than or equal to a preset threshold, the ground fault line is determined based on the zero-sequence current variance values ​​and zero-sequence current phases of all lines.

2. The single-phase ground fault line selection method according to claim 1 is characterized in that: The ground fault lines determined based on the zero-sequence current variance value and zero-sequence current phase of all lines include: Compare the zero-sequence current phases of k lines with the largest zero-sequence current variance values; If there is The zero-sequence current phase of the line is opposite to the zero-sequence current phase of the remaining k-1 lines, then the The line is a ground fault line; ; If the zero-sequence current phases of k lines are the same, it is determined that the busbar is grounded.

3. The single-phase ground fault line selection method according to claim 1, characterized in that: The preset threshold value range is [0.04, 0.06].

4. The single-phase ground fault line selection method according to claim 1 is characterized in that: The preset time value range is [1s, 10s].

5. The single-phase ground fault line selection method according to claim 2 is characterized in that: The value range of k is [3, 5].

6. The single-phase ground fault line selection method according to claim 1, characterized in that: The ground fault lines determined based on the zero-sequence current amplitude and zero-sequence current phase of all lines include: Compare the zero-sequence current phases of the m lines with the largest zero-sequence current amplitudes; If there is The zero-sequence current phase of the first line is opposite to the zero-sequence current phase of the remaining m-1 lines, then the The line is a ground fault line; ; If the zero-sequence current phases of the m lines are the same, a busbar grounding fault is determined.

7. The single-phase ground fault line selection method according to claim 6 is characterized in that: The value range of m is [3, 5].

8. The single-phase ground fault line selection method according to claim 1, characterized in that: The calculation formula of zero-sequence current variance is: ， in, Indicates the zero-sequence current variance value; Indicates the amount of zero-sequence current in the collected zero-sequence current time series data; Indicates the collected zero-sequence current time series data. Zero sequence current; Represents the mean value of all zero-sequence currents in the collected zero-sequence current time series data; , Indicates the sampling frequency.

9. A single-phase ground fault line selection device, characterized in that: include: The data acquisition and calculation module is used to collect the zero-sequence current of each line in the distribution network, and calculate the zero-sequence current variance value, zero-sequence current amplitude and zero-sequence current phase of each line within a preset time; A data comparison module is used to select the largest zero-sequence current variance value from the zero-sequence current variance values ​​of all lines, and to determine the magnitude of the largest zero-sequence current variance value and a preset threshold value; A first ground fault line selection module is used to determine the ground fault line based on the zero-sequence current amplitude and zero-sequence current phase of all lines if the maximum zero-sequence current variance value is less than a preset threshold; The second ground fault line selection module is used to determine the ground fault line based on the zero-sequence current variance values ​​and zero-sequence current phases of all lines if the maximum zero-sequence current variance value is greater than or equal to a preset threshold.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the single-phase grounding fault line selection method according to any one of claims 1 to 8 are implemented.

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