Method for determining grounding fault of power distribution network, electronic equipment and program product

Abstract

The embodiment of the invention provides a method for determining a grounding fault of a power distribution network, electronic equipment and a program product. The method comprises the following steps: acquiring a sequence of zero-sequence voltage differential values of a bus of a power distribution network; when the sequence of the zero-sequence voltage difference values meets a fault detection starting requirement, obtaining a sequence of zero-sequence current of each distribution line of the power distribution network; wherein the fault detection starting requirement is used for determining whether ground fault detection needs to be carried out or not; according to the sequence of the zero-sequence voltage differential values and the sequence of the zero-sequence current, determining a ratio fluctuation coefficient of a zero-sequence current and bus zero-sequence voltage differential ratio corresponding to each distribution line; and determining a ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient. The method is used for achieving the effect of improving the accuracy of determining the grounding fault of the power distribution network.

Description

Technical Field

[0001] The present application relates to the technical field of distribution network, and in particular to a method for determining a ground fault in a distribution network, an electronic device, and a program product. Background Art

[0002] The 10kV distribution network directly serves end users and is often a hybrid of overhead lines and cables. Due to its long total line length, multiple branches, complex environment, and relatively weak insulation, short-circuit faults are frequent. Among them, single-phase grounding short-circuit faults account for 60% to 80% of the total distribution network faults and are the most common fault type. If not handled in a timely manner, they may evolve into phase-to-phase short circuits, leading to larger-scale power outages. In addition, the faults may cause overvoltage, damage equipment insulation, and increase maintenance costs.

[0003] In the prior art, whether a distribution network needs to be detected for a ground fault is usually determined based on a preset voltage threshold and the zero-sequence voltage of the busbar, and during the detection process, whether each distribution line has a ground fault is determined based on the zero-sequence current of each distribution line based on a preset current threshold.

[0004] However, during the actual operation of the power grid, if external interference factors such as load fluctuations and weather changes occur, the zero-sequence voltage of the bus and the zero-sequence current of the distribution line will fluctuate, resulting in poor accuracy and low efficiency in determining ground faults. Summary of the Invention

[0005] The embodiments of the present application provide a method for determining a ground fault in a distribution network, an electronic device, and a program product, so as to improve the accuracy and efficiency of determining a ground fault in the distribution network.

[0006] In a first aspect, an embodiment of the present application provides a method for determining a ground fault in a distribution network, comprising:

[0007] Obtaining a sequence of zero-sequence voltage differential values of a busbar of a distribution network;

[0008] When the sequence of zero-sequence voltage differential values satisfies a fault detection start requirement, obtaining a sequence of zero-sequence currents of each distribution line of the distribution network; wherein the fault detection start requirement is used to determine whether ground fault detection is required;

[0009] According to the sequence of the zero-sequence voltage differential values and the sequence of the zero-sequence current, the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the bus zero-sequence voltage differential ratio is determined; and the grounding fault detection result of the corresponding distribution line is determined according to the ratio fluctuation coefficient.

[0010] In a possible implementation manner, according to the sequence of the zero-sequence voltage difference values and the sequence of the zero-sequence currents, determining the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus includes: according to the sequence of the zero-sequence currents and the sequence of the zero-sequence voltage difference values, determining the sequence of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus; obtaining the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, and according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, determining the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus; wherein, the first time window is less than the power frequency period of the distribution network, and the first time window is greater than or equal to a preset ratio of the power frequency period of the distribution network.

[0011] In a possible implementation manner, according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, determining the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus includes: according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, calculating the average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus; according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, and the average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, determining the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus.

[0012] In a possible implementation manner, the ground fault detection result indicates whether there is a ground fault in the corresponding distribution line; determining the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient includes: obtaining the fluctuation coefficient threshold corresponding to the distribution network; wherein, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus pre-calibrated for the distribution lines of the distribution network when no ground fault occurs; if the ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold, it is determined that there is a ground fault in the corresponding distribution line; otherwise, it is determined that there is no ground fault in the corresponding distribution line.

[0013] In a possible implementation manner, the method further includes: obtaining the reliability coefficient corresponding to the distribution network, and performing a correction process on the fluctuation coefficient threshold according to the reliability coefficient; wherein, the reliability coefficient is a pre-calibrated coefficient for correcting the influence of the short-circuit fault transient process on the fluctuation coefficient threshold.

[0014] In a possible implementation manner, the length of the sampling window based on which the fluctuation coefficient threshold corresponding to the distribution network is calibrated during the calibration process is a second time window; wherein, the second time window is the length of the sampling window based on which the ratio fluctuation coefficient of the difference ratio between the zero-sequence current and the bus zero-sequence voltage corresponding to each distribution line is determined.

[0015] In a possible implementation manner, the fault detection start requirement indicates a detection start threshold; the method further includes: extracting a first zero-sequence voltage difference value and a second zero-sequence voltage difference value from the sequence of zero-sequence voltage difference values of the bus of the distribution network based on a third time window; wherein, the third time window is equal to the power frequency period of the distribution network; the first zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the current third time window; the second zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the next third time window; if the difference between the first zero-sequence voltage difference value and the second zero-sequence voltage difference value is greater than the detection start threshold, it is determined that the sequence of zero-sequence voltage difference values satisfies the fault detection start requirement.

[0016] In a second aspect, an embodiment of the present application provides a device for determining a grounding fault of a distribution network, including:

[0017] An acquisition module, configured to acquire a sequence of zero-sequence voltage difference values of the bus of the distribution network;

[0018] A processing module, configured to acquire a sequence of zero-sequence currents of each distribution line of the distribution network when the sequence of zero-sequence voltage difference values satisfies the fault detection start requirement; wherein, the fault detection start requirement is used to determine whether a grounding fault needs to be detected;

[0019] A determination module, configured to determine a ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the bus zero-sequence voltage difference value according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents; and determine the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient.

[0020] In a possible implementation manner, the determining module is specifically configured to determine a sequence of ratios of the zero-sequence current to the zero-sequence voltage difference of each distribution line according to the sequence of the zero-sequence current and the sequence of the zero-sequence voltage difference values; obtain the sequence of ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window, and determine a ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of each distribution line according to the sequence of ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window; wherein, the first time window is less than the power frequency period of the distribution network and greater than or equal to a preset ratio of the power frequency period of the distribution network.

[0021] In a possible implementation manner, the determining module is further specifically configured to calculate an average value of the ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window according to the sequence of ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window; and determine the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of each distribution line according to the sequence of ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window and the average value of the ratios of the zero-sequence current to the zero-sequence voltage difference corresponding to the first time window.

[0022] In a possible implementation manner, the grounding fault detection result indicates whether there is a grounding fault in the corresponding distribution line; the determining module is further specifically configured to obtain a fluctuation coefficient threshold corresponding to the distribution network; wherein, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference pre-calibrated for the distribution lines of the distribution network when no grounding fault occurs; if the ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold, it is determined that there is a grounding fault in the corresponding distribution line; otherwise, it is determined that there is no grounding fault in the corresponding distribution line.

[0023] In a possible implementation manner, the determining module is further specifically configured to obtain a reliability coefficient corresponding to the distribution network and perform a correction process on the fluctuation coefficient threshold according to the reliability coefficient; wherein, the reliability coefficient is a pre-calibrated coefficient for correcting the influence of the short-circuit fault transient process on the fluctuation coefficient threshold.

[0024] In a possible implementation manner, the length of the sampling window based on which the fluctuation coefficient threshold corresponding to the distribution network is calibrated is the second time window; wherein, the second time window is the length of the sampling window based on which the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of each distribution line is determined.

[0025] In a possible implementation manner, the fault detection start requirement indicates a detection start threshold; the obtaining module is further configured to extract a first zero-sequence voltage difference value and a second zero-sequence voltage difference value from a sequence of zero-sequence voltage difference values of a bus of the distribution network based on a third time window; wherein, the third time window is equal to the power frequency period of the distribution network; the first zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the current third time window; the second zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the next third time window; if the difference between the first zero-sequence voltage difference value and the second zero-sequence voltage difference value is greater than the detection start threshold, it is determined that the sequence of zero-sequence voltage difference values meets the fault detection start requirement.

[0026] In a third aspect, an embodiment of the present application provides an electronic device, including: a memory, a processor;

[0027] The memory stores computer execution instructions;

[0028] The processor executes the computer execution instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementation manners of the first aspect.

[0029] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer execution instructions are stored, and when the computer execution instructions are executed by a processor, they are used to implement the above first aspect and / or various possible implementation manners of the first aspect.

[0030] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, and when the computer program is executed by a processor, it implements the above first aspect and / or various possible implementation manners of the first aspect.

[0031] The method, electronic device, and program product for determining the grounding fault of a distribution network provided by the embodiments of the present application obtain a sequence of zero-sequence voltage difference values of the busbars of the distribution network. When the sequence of zero-sequence voltage difference values meets the requirements for starting fault detection, it obtains the sequences of zero-sequence currents of each distribution line in the distribution network. According to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, it determines the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar; and determines the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient. Among them, if the distribution network is interfered by external interference factors such as load fluctuations and weather changes, the zero-sequence voltage of the busbar will fluctuate greatly. Among them, by calculating the zero-sequence voltage difference value, the influence of external interference factors can be excluded. At the same time, the zero-sequence voltage difference value can still be detected when the change in the zero-sequence voltage caused by the grounding fault is small, and the accuracy is higher. Therefore, in the process of determining whether the distribution network needs to perform grounding fault detection, according to the sequence of zero-sequence voltage difference values of the busbar to determine the requirements for whether the distribution network needs to perform grounding fault detection can improve the accuracy of this determination process, and further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Among them, in the process of determining the grounding fault detection result of the corresponding distribution line according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, considering the correlation between the zero-sequence voltage difference value and the zero-sequence current and the capacitance value to the ground of the distribution line, and aggregating the ratio fluctuation coefficients of the ratios of the zero-sequence currents corresponding to each distribution line to the zero-sequence voltage difference of the busbar can further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Based on the above description, the method for determining the grounding fault of the distribution network provided by the present application can improve the accuracy and efficiency of the determination of the grounding fault of the distribution network. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0033] Figure 1 Schematic flow of the method for determining the grounding fault of the distribution network provided by the present application Figure 1 ;

[0034] Figure 2 Schematic flow of the method for determining the grounding fault of the distribution network provided by the present application Figure 2 ;

[0035] Figure 3 Schematic flow of the method for determining the grounding fault of the distribution network provided by the present application Figure 3 ;

[0036] Figure 4 Schematic structural diagram of the device for determining the grounding fault of the distribution network provided by the present application;

[0037] Figure 5 This is a schematic structural diagram of the electronic device provided by this application.

[0038] Through the above-mentioned drawings, specific embodiments of this application have been shown, and there will be more detailed descriptions hereinafter. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but to illustrate the concept of this application to those skilled in the art by referring to specific embodiments. Specific Embodiments

[0039] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. On the contrary, they are merely examples of devices and methods consistent with some aspects of this application as detailed in the appended claims.

[0040] First, the terms involved in this application are explained:

[0041] The distribution network refers to the section of the system from the outlet of the step-down distribution substation (high-voltage distribution substation) to the user end, which is mainly responsible for distributing electric energy. Among them, the distribution network includes a busbar and at least one distribution line;

[0042] The busbar refers to the conductor that connects each current-carrying branch circuit in the electrical device and is used to collect and distribute electric power;

[0043] The distribution line refers to the line that delivers electric power from the step-down substation to the distribution transformer or delivers the electric power of the distribution substation to the power-consuming unit;

[0044] The zero-sequence voltage is the voltage component generated in the three-phase power system due to asymmetric faults (such as single-phase grounding or two-phase grounding short circuits);

[0045] The zero-sequence current is the current component generated when the three-phase currents in the distribution line are unbalanced.

[0046] In the prior art, it is usually determined whether the distribution network needs to detect ground faults based on a preset voltage threshold and the zero-sequence voltage of the busbar, and during the detection process, it is determined whether there are ground faults in each distribution line based on the zero-sequence current of each distribution line and a preset current threshold. However, in the actual operation process of the power grid, if external interference factors such as load fluctuations and weather changes occur, they will cause fluctuations in the zero-sequence voltage of the busbar and the zero-sequence current of the distribution line, resulting in poor accuracy and low efficiency in determining ground faults.

[0047] The method for determining the grounding fault of a distribution network provided by this application obtains the sequence of zero-sequence voltage difference values of the bus of the distribution network. When the sequence of zero-sequence voltage difference values meets the requirements for starting fault detection, it obtains the sequence of zero-sequence currents of each distribution line in the distribution network. According to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, it determines the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus; and determines the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient. Among them, if the distribution network is interfered by external interference factors such as load fluctuations and weather changes, the zero-sequence voltage of the bus will fluctuate greatly. Among them, by calculating the zero-sequence voltage difference value, the influence of external interference factors can be excluded. At the same time, the zero-sequence voltage difference value can still be detected when the change in zero-sequence voltage caused by the grounding fault is small, and the accuracy is higher. Therefore, in the process of determining whether the distribution network needs to perform grounding fault detection, according to the sequence of zero-sequence voltage difference values of the bus to determine the requirements for whether the distribution network needs to perform grounding fault detection can improve the accuracy of this determination process, and further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Among them, compared with the zero-sequence current, the zero-sequence current of the distribution line can more accurately reflect the fault characteristics of the distribution line. Therefore, according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, the grounding fault detection result of the corresponding distribution line can be determined more accurately. Among them, in the process of determining the grounding fault detection result of the corresponding distribution line according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, considering the correlation between the zero-sequence voltage difference value and the zero-sequence current and the capacitance value to the ground of the distribution line, aggregating the ratio fluctuation coefficients of the ratios of the zero-sequence currents corresponding to each distribution line to the zero-sequence voltage difference of the bus can further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Based on the above description, the method for determining the grounding fault of the distribution network provided by this application can improve the accuracy and efficiency of the determination of the grounding fault of the distribution network.

[0048] The following uses specific embodiments to detail the technical solution of this application and how the technical solution of this application solves the above technical problems. These several specific embodiments below can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The following will describe the embodiments of this application in conjunction with the drawings.

[0049] Figure 1 Flow schematic of the method for determining the grounding fault of the distribution network provided by this application Figure 1 As Figure 1 shown, the method includes:

[0050] Step S101, obtain the sequence of zero-sequence voltage difference values of the bus of the distribution network.

[0051] Specifically, a sequence of zero-sequence voltage difference values of the busbars of the distribution network can be obtained.

[0052] Among them, the zero-sequence voltage difference value refers to the difference between the zero-sequence voltages of the busbars measured at different time points. For example, it is the difference between the zero-sequence voltages detected at adjacent sampling time points. The formula corresponding to the zero-sequence voltage difference value is as follows:

[0053] u d (n) = u0(n) - u0(n - 1)

[0054] Among them, u d (n) is the zero-sequence voltage difference value corresponding to the nth sampling point, u0(n) is the zero-sequence voltage of the busbar detected at the nth sampling point, and u0(n - 1) is the zero-sequence voltage of the busbar detected at the (n - 1)th sampling point.

[0055] Among them, the sequence of zero-sequence voltage difference values refers to the sequence composed of the zero-sequence voltage values corresponding to each sampling point. Specifically, if the formula of the zero-sequence voltage value is as shown above, the sequence of zero-sequence voltage difference values includes: the zero-sequence voltage difference value u d (n) corresponding to the nth sampling point, ……, the zero-sequence voltage difference value u d (j) corresponding to the jth sampling point, ……, the zero-sequence voltage difference value u d (1) corresponding to the first sampling point.

[0056] Step S102: When the sequence of zero-sequence voltage difference values meets the fault detection start requirement, obtain the sequence of zero-sequence currents of each distribution line in the distribution network.

[0057] Among them, the fault detection start requirement is used to determine whether it is necessary to detect the ground fault. Specifically, this application does not limit the fault detection start requirement. Any requirement that can determine whether the distribution network needs to detect the ground fault according to the sequence of zero-sequence voltage difference values of the busbars can be used as the fault detection start requirement provided by this application. Optionally, the fault detection start requirement provided by this application may include at least one analysis method such as threshold analysis, change trend analysis, deviation value analysis, and comparison analysis. Among them, if the zero-sequence voltage meets the requirements corresponding to each analysis method in the fault detection start requirement, it is determined that the zero-sequence voltage meets the fault detection start requirement.

[0058] Among them, if the distribution network is interfered by external interference factors such as load fluctuations and weather changes, the zero-sequence voltage of the bus will fluctuate greatly. Among them, by calculating the differential value of the zero-sequence voltage, the influence of external interference factors can be excluded. At the same time, the differential value of the zero-sequence voltage can still be detected when the change of the zero-sequence voltage caused by the ground fault is small, and the accuracy is higher. Therefore, in the process of determining whether the distribution network needs to detect ground faults, according to the sequence of the differential value of the zero-sequence voltage of the bus to determine the requirement of whether the distribution network needs to detect ground faults can improve the accuracy of this determination process and further improve the efficiency and accuracy of the detection of ground faults in the distribution network.

[0059] Specifically, when the sequence of the differential value of the zero-sequence voltage does not meet the fault detection start requirement, it is determined that the distribution network does not need to detect ground faults. At this time, there is no need to perform subsequent analysis and processing. At the same time, the sequence of the differential value of the zero-sequence voltage can be continuously monitored to timely detect that the distribution network needs to detect ground faults, improving the efficiency and accuracy of the determination of ground faults in the distribution network.

[0060] Specifically, when the sequence of the differential value of the zero-sequence voltage meets the fault detection start requirement, the sequence of the zero-sequence current of each distribution line of the distribution network can be obtained.

[0061] Among them, the zero-sequence current refers to the zero-sequence current of the distribution line measured at different time points. The sequence of the zero-sequence current of each distribution line is the sequence composed of the zero-sequence current corresponding to each sampling point of each distribution line. For example, in the kth distribution line, the zero-sequence current corresponding to the nth sampling point is i 0k (n), and the sequence of the zero-sequence current of the kth distribution line includes: the zero-sequence current corresponding to the nth sampling point is i 0k (n), ……, the zero-sequence current corresponding to the jth sampling point is i 0k (j), ……, the zero-sequence current corresponding to the 1st sampling point is i 0k (1).

[0062] Step S103: According to the sequence of the differential value of the zero-sequence voltage and the sequence of the zero-sequence current, determine the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus; and determine the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient.

[0063] Specifically, according to the sequence of the differential value of the zero-sequence voltage of the bus obtained in step S101 and the sequence of the zero-sequence current of each distribution line obtained in step S102, the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus can be determined; and the ground fault detection result of the corresponding distribution line is determined according to the ratio fluctuation coefficient.

[0064] Specifically, after determining the distribution line with a grounding fault in the distribution network, since there is a difference between the sequences of zero-sequence currents of the distribution line with a grounding fault and the distribution line without a grounding fault, the relationships between the two and the zero-sequence voltage of the bus are also different. Therefore, it is possible to determine whether there is a grounding fault in each distribution line by determining the relationship between the zero-sequence current and the zero-sequence voltage of each distribution line.

[0065] Specifically, in the process of determining the grounding fault detection result of the corresponding distribution line according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, it is achieved by determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus. Among them, in the distribution network, if the distribution line is a non-faulty line, the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus is approximately equal to the capacitance value to the ground of this distribution line. Since this capacitance value to the ground is a constant, the corresponding waveform fluctuations of the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus at different sampling points are small. Among them, in the distribution network, if the distribution line is a faulty line, the corresponding waveform of the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus at different sampling points is approximately equal to the cotangent function, and the waveform fluctuations are large. Therefore, it is possible to determine the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, and determine the grounding fault detection result of the corresponding distribution line according to the determined ratio fluctuation coefficient.

[0066] The method for determining the grounding fault of a distribution network provided by an embodiment of the present application obtains a sequence of zero-sequence voltage difference values of the busbars of the distribution network. When the sequence of zero-sequence voltage difference values meets the requirements for starting fault detection, it obtains the sequences of zero-sequence currents of each distribution line of the distribution network. According to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, it determines the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar; and determines the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient. Among them, if the distribution network is interfered by external interference factors such as load fluctuations and weather changes, the zero-sequence voltage of the busbar will fluctuate greatly. Among them, by calculating the zero-sequence voltage difference value, the influence of external interference factors can be excluded. At the same time, the zero-sequence voltage difference value can still be detected when the change in the zero-sequence voltage caused by the grounding fault is small, and the accuracy is higher. Therefore, in the process of determining whether the distribution network needs to perform grounding fault detection, according to the sequence of zero-sequence voltage difference values of the busbar to determine the requirements for whether the distribution network needs to perform grounding fault detection can improve the accuracy of this determination process, and further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Among them, in the process of determining the grounding fault detection result of the corresponding distribution line according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, considering the correlation between the zero-sequence voltage difference value and the zero-sequence current and the capacitance value to the ground of the distribution line, and aggregating the ratio fluctuation coefficients of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar can further improve the efficiency and accuracy of the grounding fault detection of the distribution network. Based on the above description, the method for determining the grounding fault of the distribution network provided by the present application can improve the accuracy and efficiency of the determination of the grounding fault of the distribution network.

[0067] Figure 2 is a schematic flow chart of the method for determining the grounding fault of the distribution network provided by the present application Figure 2 , such as Figure 2 shown, on the basis of the Figure 1 embodiment, it details the determination of the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar according to the sequence of zero-sequence currents and the sequence of zero-sequence voltage difference values. The method includes:

[0068] Step S201: Determine the sequence of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar according to the sequence of zero-sequence currents and the sequence of zero-sequence voltage difference values.

[0069] Specifically, according to the sequence of zero-sequence currents and the sequence of zero-sequence voltage difference values, the sequence of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the busbar can be determined.

[0070] Among them, the differential ratio of zero-sequence current to zero-sequence bus voltage is the ratio between the zero-sequence current and the differential value of zero-sequence voltage. For example, if the differential value of zero-sequence voltage corresponding to the nth sampling point is u d (n), and the zero-sequence current corresponding to the head end of the kth distribution line at the nth sampling point is i 0k (n), then the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to the kth distribution line at the nth sampling point is x k (n) = i 0k (n) / u d (n).

[0071] Among them, the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage is the sequence composed of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to each sampling point. For example, the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to the kth distribution line includes: the differential ratio of zero-sequence current to zero-sequence bus voltage x k (n) corresponding to the kth distribution line at the nth sampling point, ……, the differential ratio of zero-sequence current to zero-sequence bus voltage x k (j) corresponding to the kth distribution line at the jth sampling point, ……, the differential ratio of zero-sequence current to zero-sequence bus voltage x k (1) corresponding to the kth distribution line at the first sampling point.

[0072] Step S202, obtain the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to the first time window, and determine the ratio fluctuation coefficient of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to each distribution line according to the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to the first time window.

[0073] Specifically, based on the description of the differential ratio of zero-sequence current to zero-sequence bus voltage in step S103, in the process of determining whether there is a grounding fault in the distribution line, based on the fluctuation characteristics of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to each distribution line. Therefore, the efficiency of grounding fault determination can be improved by selecting a part of the sequence from the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage. At the same time, the selected part of the sequence should also ensure that it can accurately reflect the fluctuation characteristics of the differential ratio.

[0074] Specifically, the sequence of the differential ratio of zero-sequence current to zero-sequence bus voltage corresponding to the first time window can be obtained.

[0075] Among them, the first time window is less than the power frequency period of the distribution network, and the first time window is greater than or equal to a preset ratio of the power frequency period of the distribution network.

[0076] Specifically, by setting a sampling time window smaller than the power frequency period of the distribution network, the amount of data on which the calculation of the ratio fluctuation coefficient is based can be reduced, and the efficiency of grounding fault detection in the distribution network can be improved.

[0077] Specifically, by setting a time greater than a preset ratio of the power frequency period of the distribution network, for example, 1 / 4 power frequency period, it can be ensured that the amount of data on which the calculation of the ratio fluctuation coefficient is based is not too small, so as to improve the accuracy of grounding fault detection in the distribution network on the basis of improving the efficiency of grounding fault detection in the distribution network. The power frequency period refers to the time required for alternating current to complete a full change within one cycle. For example, if the number of sampling points corresponding to the power frequency period is N, and the first time window corresponds to 1 / 4 power frequency period, then the number of sampling points N' corresponding to the first time window is N / 4.

[0078] For example, if the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the kth distribution line is as shown in step S201, and N' is the number of sampling points corresponding to the first time window, and N' < N, then the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window includes: the differential ratio x k (N′) of the zero-sequence current to the bus zero-sequence voltage corresponding to the kth distribution line at the N'th sampling point, ……, the differential ratio x k (j) of the zero-sequence current to the bus zero-sequence voltage corresponding to the kth distribution line at the jth sampling point, ……, the differential ratio x k (1) of the zero-sequence current to the bus zero-sequence voltage corresponding to the kth distribution line at the first sampling point.

[0079] Specifically, after obtaining the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window, the ratio fluctuation coefficient of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to each distribution line can be determined according to the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window.

[0080] Specifically, the present application does not limit the process of determining the ratio fluctuation coefficient of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to each distribution line according to the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window. Optionally, determining the ratio fluctuation coefficient of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to each distribution line according to the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window includes:

[0081] Calculating the average value of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window according to the sequence of the differential ratio of the zero-sequence current to the bus zero-sequence voltage corresponding to the first time window.

[0082] Determine the ratio fluctuation coefficient of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to each distribution line according to the sequence of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window and the average value of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window.

[0083] Specifically, if the sequence of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window of the k-th distribution line is as shown above, the formula for the average value of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window of the k-th distribution line is as follows:

[0084]

[0085] Wherein, is the average value of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window of the k-th distribution line.

[0086] Specifically, if the formula for the average value of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window of the k-th distribution line is as shown above, the formula for the ratio fluctuation coefficient of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the k-th distribution line determined according to the sequence of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window and the average value of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window is as follows:

[0087]

[0088] Wherein, P k is the ratio fluctuation coefficient of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the k-th distribution line.

[0089] Wherein, in the process of determining the ratio fluctuation coefficient of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to each distribution line according to the sequence of the differential ratio of zero-sequence current to bus zero-sequence voltage corresponding to the first time window, by calculating the average value of the differential ratio and calculating the difference between the differential ratio and the average value, the calculated ratio fluctuation coefficient can efficiently and accurately reflect the fluctuation characteristics of the differential ratio, thereby improving the accuracy and efficiency of determining the grounding fault of the distribution network.

[0090] The process provided in the embodiments of the present application for determining the ratio fluctuation coefficient of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus according to the sequence of the zero-sequence current and the sequence of the differential values of the zero-sequence voltage is as follows: by determining the sequence of the ratio of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus according to the sequence of the zero-sequence current and the sequence of the differential values of the zero-sequence voltage, obtaining the sequence of the ratio of the zero-sequence current corresponding to the first time window to the differential value of the zero-sequence voltage of the bus, and determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the differential value of the zero-sequence voltage of the bus. Among them, the efficiency of grounding fault determination is improved by selecting a part of the sequence from the sequence of the ratio of the zero-sequence current to the differential value of the zero-sequence voltage of the bus. At the same time, a preset ratio is used to ensure that the selected part of the sequence can accurately reflect the fluctuation characteristics of the differential ratio, so as to ensure the accuracy of grounding fault determination on the basis of improving the efficiency of grounding fault determination. Based on the above description, the process provided in the embodiments of the present application for determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the differential value of the zero-sequence voltage of the bus can improve the accuracy and efficiency of grounding fault determination in the distribution network.

[0091] Figure 3 It is a schematic flow chart of the method for determining the grounding fault of the distribution network provided by the present application Figure 3 , as Figure 3 shown, based on the embodiment of Figure 1 or Figure 2 embodiment, a detailed description is given of determining the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient. The method includes:

[0092] Step S301: Obtain the fluctuation coefficient threshold corresponding to the distribution network.

[0093] Specifically, the fluctuation coefficient threshold corresponding to the distribution network can be obtained. Among them, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the ratio of the zero-sequence current to the differential value of the zero-sequence voltage of the bus pre-calibrated for the distribution lines of the distribution network when no grounding fault occurs.

[0094] Among them, based on the description of the ratio fluctuation coefficient of the difference ratio between the zero-sequence current and the zero-sequence bus voltage in step S103, in a distribution network, if the distribution line is a non-faulty line, the ratio of the zero-sequence current to the difference of the zero-sequence bus voltage is approximately equal to the capacitance value to the ground of the distribution line. Among them, since the capacitance value to the ground is a constant, therefore, the corresponding waveforms of the ratio of the zero-sequence current to the difference of the zero-sequence bus voltage at different sampling points fluctuate less. Therefore, the fluctuation coefficient threshold can be determined by pre-calibrating the ratio fluctuation coefficient in this case. Among them, due to the different structural compositions of different distribution networks, the corresponding fluctuation coefficient thresholds may also be different. Therefore, during the pre-calibration process, the pre-calibration can be performed based on the corresponding distribution network.

[0095] Step S302: If the ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold, it is determined that the corresponding distribution line has a ground fault; otherwise, it is determined that the corresponding distribution line does not have a ground fault.

[0096] Among them, the ground fault detection result indicates whether the corresponding distribution line has a ground fault.

[0097] Specifically, if the calculated ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold in step S301, it is determined that the corresponding distribution line has a ground fault; if the calculated ratio fluctuation coefficient is less than the fluctuation coefficient threshold in step S301, it is determined that the corresponding distribution line does not have a ground fault.

[0098] Optionally, the process of determining the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient may further include the following process:

[0099] Obtain the reliability coefficient corresponding to the distribution network, and correct the fluctuation coefficient threshold according to the reliability coefficient.

[0100] Among them, the reliability coefficient is a pre-calibrated coefficient used to correct the influence of the short-circuit fault transient process on the fluctuation coefficient threshold.

[0101] Among them, a short-circuit fault is a common and serious fault in a power system, which occurs when a low-impedance path is formed between different parts of the power system. The short-circuit fault transient process refers to the change process of electrical quantities such as current, voltage, and power from the moment when the short-circuit fault occurs until the system reaches a new stable state (or the fault is removed).

[0102] Among them, the process of obtaining the reliability coefficient corresponding to the distribution network may include the following process:

[0103] First, analyze the system characteristics of the distribution network.

[0104] Specifically, the system scale of the distribution network can be analyzed: large-scale power systems may have stronger stability and redundancy, so it is possible to consider appropriately reducing the reliability coefficient; while small-scale systems may be more vulnerable and require a higher reliability coefficient to ensure safety. The line type of the distribution network can also be analyzed: different types of lines (such as overhead lines, cables, etc.) have different electrical characteristics and failure rates, so the reliability coefficient needs to be adjusted according to the line type. Additionally, the fault history of the distribution network can be analyzed: analyzing historical fault data and understanding the fault modes and frequencies of the system helps to determine an appropriate reliability coefficient.

[0105] Secondly, analyze the fault characteristics of the transient process of short-circuit faults in the distribution network.

[0106] Specifically, the fault type can be analyzed first: different types of short-circuit faults (such as single-phase grounding, two-phase short circuit, three-phase short circuit, etc.) have different transient processes and different effects on electrical quantities. Therefore, the value of the reliability coefficient needs to be evaluated according to the fault type. The fault duration can also be analyzed: the duration of short-circuit faults also has different effects on electrical quantities. Long-duration faults may lead to more serious changes in electrical quantities, so a higher reliability coefficient is required to ensure safety. Additionally, the magnitude of the fault current can be analyzed: the magnitude of the fault current directly affects the thermal and mechanical effects of electrical equipment, so the reliability coefficient needs to be adjusted according to the magnitude of the fault current.

[0107] Then, combine experimental and simulation data.

[0108] Specifically, experimental verification is to measure the changes in electrical quantities under different conditions through actual power system experiments and calculate the fluctuation coefficient. According to the experimental results, the value range of the reliability coefficient can be initially determined. Simulation analysis is to use power system simulation software to simulate the changes in electrical quantities under different fault scenarios and calculate the fluctuation coefficient. By comparing the simulation results with the experimental results, the value of the reliability coefficient can be further verified and adjusted.

[0109] Finally, determine the reliability coefficient based on the system characteristics of the distribution network, the fault characteristics of the transient process of short-circuit faults, and experimental and simulation data.

[0110] Specifically, based on comprehensively considering the characteristics of the power system, the transient process of short-circuit faults, and experimental and simulation data, a suitable value range of the reliability coefficient can be determined.

[0111] Optionally, the reliability coefficient can be any value between 1.5 and 2.

[0112] Specifically, after obtaining the reliability coefficient corresponding to the distribution network, the fluctuation coefficient threshold can be corrected according to the reliability coefficient. For example, if the obtained reliability coefficient of the distribution network is K rel , and P non.max, the fluctuation coefficient threshold after calibration processing is P set = K rel ×P non.max .

[0113] Among them, by calibrating the fluctuation coefficient threshold through the reliability coefficient, the accurate determination of the fluctuation coefficient threshold can be improved, and further improve the accuracy of the detection of the grounding fault in the distribution network. Among them, in the process of calibrating the fluctuation coefficient threshold, the reliability coefficient is used to correct the influence of the short-circuit fault transient process on the fluctuation coefficient threshold. Therefore, the accurate determination of the fluctuation coefficient threshold can be further improved, thereby improving the accuracy of the detection of the grounding fault in the distribution network. Based on the above description, the calibration process of the fluctuation coefficient threshold provided by the embodiments of the present application can improve the accuracy of the detection of the grounding fault in the distribution network.

[0114] Optionally, the length of the sampling window based on which the fluctuation coefficient threshold corresponding to the distribution network is calibrated is the second time window. Among them, the second time window is the length of the sampling window based on which the ratio fluctuation coefficient of the difference ratio between the zero-sequence current corresponding to each distribution line and the zero-sequence voltage of the bus is determined.

[0115] Specifically, based on the description of the first time window in step S202, in the process of calculating the ratio fluctuation coefficient of the difference ratio between the zero-sequence current and the zero-sequence voltage of the bus, the first time window can improve the efficiency and accuracy of the ratio fluctuation coefficient of the difference ratio between the zero-sequence current and the zero-sequence voltage of the bus. And since the fluctuation coefficient threshold is used to compare with the calculated fluctuation coefficient, the length of the sampling window based on which the pre-calibration process of the fluctuation coefficient threshold is carried out can be determined to be the same time length as the length of the sampling window based on which the ratio fluctuation coefficient of the difference ratio between the zero-sequence current corresponding to each distribution line and the zero-sequence voltage of the bus is determined, which can improve the accuracy of the calibrated fluctuation coefficient threshold, thereby improving the accuracy of the determination of the grounding fault in the distribution network.

[0116] In the process of determining the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient provided by the embodiments of the present application, it can be determined through the fluctuation coefficient threshold, which can improve the efficiency of the grounding fault detection in the distribution network. Among them, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the difference ratio between the zero-sequence current and the zero-sequence voltage of the bus pre-calibrated when the distribution line of the distribution network does not have a grounding fault, so that it can be accurately determined whether there is a grounding fault in the distribution line based on this fluctuation coefficient threshold. At the same time, since the obtained fluctuation coefficient threshold corresponds to the distribution network here, it can also further improve the accuracy of the grounding fault determination. Based on the above description, the process of determining the grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient provided by the embodiments of the present application can improve the accuracy and efficiency of the grounding fault determination.

[0117] In a possible embodiment, the method for determining a ground fault in a distribution network further includes:

[0118] Extract a first zero-sequence voltage difference value and a second zero-sequence voltage difference value from a sequence of zero-sequence voltage difference values of the busbars of the distribution network based on a third time window.

[0119] Wherein, the third time window is equal to the power frequency period of the distribution network. The first zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the current third time window. The second zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the next third time window.

[0120] If the difference between the first zero-sequence voltage difference value and the second zero-sequence voltage difference value is greater than the detection start threshold, it is determined that the sequence of zero-sequence voltage difference values meets the fault detection start requirement.

[0121] The fault detection start requirement indicates the detection start threshold.

[0122] Specifically, in the process of determining whether the sequence of zero-sequence voltage difference values meets the fault detection start requirement, it is possible to efficiently determine whether the sequence of zero-sequence voltage difference values meets the fault detection start requirement by means of a preset threshold and calculating the difference between two zero-sequence voltage difference values in the sequence of zero-sequence voltage difference values.

[0123] Wherein, on this basis, in order to improve the accuracy of fault detection start, in the process of calculating the difference between two zero-sequence voltage difference values in the sequence of zero-sequence voltage difference values, it is possible to ensure that there is a power frequency period of the distribution network between the two sampling points based on the third time window equal to the power frequency period of the distribution network. Therefore, on the basis of better reflecting whether there is a ground fault in the distribution network, the shortest sampling time window length is selected, which improves the accuracy of fault detection start of the distribution network and further improves the efficiency and accuracy of determining the ground fault of the distribution network.

[0124] Figure 4 The following is a schematic structural diagram of the device for determining a ground fault in a distribution network provided by this application, as Figure 4 shown, the device 40 for determining a ground fault in a distribution network provided in this embodiment includes:

[0125] An acquisition module 401, configured to acquire a sequence of zero-sequence voltage difference values of the busbars of the distribution network;

[0126] A processing module 402, configured to acquire a sequence of zero-sequence currents of each distribution line of the distribution network when the sequence of zero-sequence voltage difference values meets the fault detection start requirement; wherein, the fault detection start requirement is used to determine whether it is necessary to perform ground fault detection;

[0127] A determination module 403, configured to determine a ratio fluctuation coefficient of a ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to a sequence of zero-sequence voltage difference values and a sequence of zero-sequence currents; and determine a grounding fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient.

[0128] In a possible embodiment, the determination module 403 is specifically configured to determine a sequence of ratios of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of zero-sequence currents and the sequence of zero-sequence voltage difference values; obtain a sequence of ratios of the zero-sequence current corresponding to a first time window to the zero-sequence voltage difference of the bus, and determine a ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of ratios of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus; wherein, the first time window is less than the power frequency period of the distribution network and greater than or equal to a preset ratio of the power frequency period of the distribution network.

[0129] In a possible embodiment, the determination module 403 is further specifically configured to calculate an average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus according to the sequence of ratios of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus; and determine a ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of ratios of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus and the average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus.

[0130] In a possible embodiment, the grounding fault detection result indicates whether there is a grounding fault in the corresponding distribution line; the determination module 403 is further specifically configured to obtain a fluctuation coefficient threshold corresponding to the distribution network; wherein, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus pre-calibrated for the distribution lines of the distribution network when no grounding fault occurs; if the ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold, it is determined that there is a grounding fault in the corresponding distribution line; otherwise, it is determined that there is no grounding fault in the corresponding distribution line.

[0131] In a possible embodiment, the determination module 403 is further specifically configured to obtain a reliability coefficient corresponding to the distribution network and perform a correction process on the fluctuation coefficient threshold according to the reliability coefficient; wherein, the reliability coefficient is a pre-calibrated coefficient for correcting the influence of the short-circuit fault transient process on the fluctuation coefficient threshold.

[0132] In a possible embodiment, the length of the sampling window based on which the fluctuation coefficient threshold corresponding to the distribution network is calibrated is a second time window; wherein, the second time window is the length of the sampling window based on which the ratio fluctuation coefficient of the difference ratio between the zero-sequence current corresponding to each distribution line and the zero-sequence bus voltage is determined.

[0133] In a possible embodiment, the fault detection start requirement indicates a detection start threshold; the obtaining module 401 is further configured to extract a first zero-sequence voltage difference value and a second zero-sequence voltage difference value from the sequence of zero-sequence voltage difference values of the bus of the distribution network based on a third time window; wherein, the third time window is equal to the power frequency period of the distribution network; the first zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the current third time window; the second zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the next third time window; if the difference between the first zero-sequence voltage difference value and the second zero-sequence voltage difference value is greater than the detection start threshold, it is determined that the sequence of zero-sequence voltage difference values meets the fault detection start requirement.

[0134] The device for determining the grounding fault of the distribution network provided in this embodiment can execute the method provided in the above method embodiment, and its implementation principle and technical effect are similar, which will not be elaborated here in this embodiment.

[0135] Figure 5 It is a schematic structural diagram of the electronic device provided in this application. As Figure 5 shown, the electronic device 50 provided in this embodiment includes: at least one processor 501 and a memory 502. Optionally, the electronic device 50 further includes a communication component 503. Wherein, the processor 501, the memory 502, and the communication component 503 are connected through a bus 504.

[0136] In a specific implementation process, at least one processor 501 executes the computer execution instructions stored in the memory 502, so that at least one processor 501 executes the above method.

[0137] The specific implementation process of the processor 501 can refer to the above method embodiment, and its implementation principle and technical effect are similar, which will not be elaborated here in this embodiment.

[0138] In the above embodiments, it should be understood that the processor may be a central processing unit (CPU for short), or may also be other general-purpose processors, digital signal processors (DSP for short), application specific integrated circuits (ASIC for short), etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The steps of the method disclosed in combination with the invention can be directly implemented by the execution of the hardware processor, or can be implemented by the combination of hardware and software modules in the processor.

[0139] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include non-volatile memory (Non-volatile Memory, NVM), such as at least one disk memory.

[0140] The bus may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For the convenience of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0141] This application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0142] This application also provides a computer-readable storage medium, in which computer-executable instructions are stored, and when the processor executes the computer-executable instructions, the above method is implemented.

[0143] The above-readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, a magnetic disk or an optical disk. The readable storage medium can be any available medium accessible by a general-purpose or special-purpose computer.

[0144] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an Application Specific Integrated Circuit (ASIC). Of course, the processor and the readable storage medium can also exist as discrete components in a device.

[0145] The division of units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Additionally, the couplings or direct couplings or communication connections shown or discussed between each other can be indirect couplings or communication connections through some interfaces, devices or units, and can be in electrical, mechanical or other forms.

[0146] The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0147] Furthermore, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit.

[0148] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art or a part of this technical solution can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods in each embodiment of the present invention. And the aforementioned storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks or optical discs that can store program codes.

[0149] Those of ordinary skill in the art will understand that all or part of the steps of implementing the above method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps including those of the above method embodiments; and the aforementioned storage medium includes: various media such as ROM, RAM, magnetic disks, or optical discs that can store program codes.

[0150] Finally, it should be noted that: after considering the specification and practicing the invention disclosed herein, those skilled in the art will readily conceive of other embodiments of the present invention. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed by the present invention. It is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.

Claims

1. A method for determining a grounding fault in a distribution network, characterized in that, Including: Obtaining a sequence of zero-sequence voltage difference values of the buses of the distribution network; When the sequence of zero-sequence voltage difference values meets the fault detection start requirement, obtaining a sequence of zero-sequence currents of each distribution line in the distribution network; wherein, the fault detection start requirement is used to determine whether it is necessary to detect a ground fault; According to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, determining a ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus; and determining the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient.

2. The method according to claim 1, wherein Determining a ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, including: According to the sequence of zero-sequence currents and the sequence of zero-sequence voltage difference values, determining a sequence of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus; Obtaining the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, and determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus; wherein, the first time window is less than the power frequency period of the distribution network, and the first time window is greater than or equal to a preset ratio of the power frequency period of the distribution network.

3. The method according to claim 2, wherein Determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus, including: Calculating an average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus; Determining the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence voltage difference of the bus according to the sequence of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus and the average value of the ratio of the zero-sequence current corresponding to the first time window to the zero-sequence voltage difference of the bus.

4. The method according to claim 1, characterized in that The ground fault detection result indicates whether there is a ground fault in the corresponding distribution line; determining the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient, including: Obtaining the fluctuation coefficient threshold corresponding to the distribution network; wherein, the fluctuation coefficient threshold is the maximum value of the ratio fluctuation coefficient of the ratio of the zero-sequence current to the zero-sequence voltage difference of the bus pre-calibrated for the distribution lines of the distribution network when no ground fault occurs; If the ratio fluctuation coefficient is greater than or equal to the fluctuation coefficient threshold, determining that there is a ground fault in the corresponding distribution line; otherwise, determining that there is no ground fault in the corresponding distribution line.

5. The method according to claim 4, characterized in that, The method further includes: Obtaining the reliability coefficient corresponding to the distribution network, and performing a correction process on the fluctuation coefficient threshold according to the reliability coefficient; Wherein, the reliability coefficient is a pre-calibrated coefficient for correcting the influence of the short-circuit fault transient process on the fluctuation coefficient threshold.

6. The method according to claim 4, wherein The length of the sampling window based on which the fluctuation coefficient threshold corresponding to the distribution network is calibrated is the second time window; wherein, the second time window is the length of the sampling window based on which the ratio fluctuation coefficient of the difference ratio between the zero-sequence current corresponding to each distribution line and the zero-sequence bus voltage is determined.

7. The method according to any one of claims 1-6, characterized in that, The fault detection start requirement indicates a detection start threshold; the method further includes: Extracting a first zero-sequence voltage difference value and a second zero-sequence voltage difference value from a sequence of zero-sequence voltage difference values of the bus of the distribution network based on a third time window; Wherein, the third time window is equal to the power frequency period of the distribution network; the first zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the current third time window; the second zero-sequence voltage difference value is the zero-sequence voltage difference value corresponding to the first sampling point in the next third time window; If the difference between the first zero-sequence voltage difference value and the second zero-sequence voltage difference value is greater than the detection start threshold, it is determined that the sequence of zero-sequence voltage difference values satisfies the fault detection start requirement.

8. An apparatus for determining a grounding fault in a distribution network, characterized in that, Including: An acquisition module for acquiring a sequence of zero-sequence voltage difference values of the bus of the distribution network; A processing module for, when the sequence of zero-sequence voltage difference values satisfies the fault detection start requirement, acquiring a sequence of zero-sequence currents of each distribution line of the distribution network; wherein, the fault detection start requirement is used to determine whether it is necessary to perform ground fault detection; A determination module for determining, according to the sequence of zero-sequence voltage difference values and the sequence of zero-sequence currents, the ratio fluctuation coefficient of the ratio of the zero-sequence current corresponding to each distribution line to the zero-sequence bus voltage difference; and determining the ground fault detection result of the corresponding distribution line according to the ratio fluctuation coefficient.

9. An electronic device, characterized in that, Including: A memory, a processor; The memory stores computer execution instructions; The processor executes the computer execution instructions stored in the memory, so that the processor executes the method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, Computer execution instructions are stored in the computer-readable storage medium, and when the computer execution instructions are executed by a processor, they are used to implement the method according to any one of claims 1-7.

11. A computer program product, characterized in that, Including a computer program, which when executed by a processor implements the method according to any one of claims 1-7.

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