Single-phase earth fault detection method and device, electronic equipment and storage medium

Abstract

The invention discloses a single-phase earth fault detection method and device, electronic equipment and a storage medium. The single-phase earth fault detection method comprises the following steps: when the zero-sequence voltage break variable of a bus is greater than or equal to a voltage change threshold value, determining that a feeder line has a single-phase earth fault; wherein the voltage change threshold value is the ratio of the preset voltage break variable to the reliability coefficient; determining a plurality of instantaneous phase powers of each phase of each feeder line in a preset time period, and determining a power mean value index of the corresponding phase according to the plurality of instantaneous phase powers of each phase in the preset time period so as to determine a power mean value index of each phase of each feeder line; wherein the preset time period comprises a fault time point; and determining a fault criterion value of each feeder line according to the power mean value index of each phase of each feeder line, and determining that the feeder line corresponding to the fault criterion value is a fault line when the fault criterion value is greater than or equal to an action threshold value. According to the technical scheme, the accuracy of single-phase earth fault detection is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fault detection, and in particular to a single-phase grounding fault detection method, device, electronic equipment and storage medium. Background Art

[0002] Most of the existing ground fault detection methods compare the voltage and current zero-sequence information of all feeders. With the development of power systems, the scale of distribution networks continues to expand, the number of substation feeders continues to increase, and the fault conditions become increasingly complex. The efficiency and accuracy of such methods cannot be guaranteed.

[0003] Single-phase grounding fault is a common fault in distribution network, accounting for more than 80% of all faults, and high-resistance faults occur from time to time. If the fault is not handled in time, it will affect the stability of power supply of the power system and may even endanger personal safety. Therefore, it is particularly important to study its fault detection technology. For low-resistance grounding system, the zero-sequence current amplitude is very small during high-resistance grounding fault, making it difficult to detect the fault, that is, the detection accuracy is low. Summary of the invention

[0004] The present invention provides a single-phase ground fault detection method, device, electronic equipment and storage medium to solve the problem of low accuracy of existing ground fault detection methods.

[0005] According to one aspect of the present invention, a single-phase grounding fault detection method is provided, and the single-phase grounding fault detection method comprises:

[0006] When the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, it is determined that a single-phase grounding fault occurs in the feeder; wherein the voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient;

[0007] Determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine the power mean index of the corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes the fault time point;

[0008] The fault criterion value of each feeder is determined according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, the feeder corresponding to the fault criterion value is determined to be a fault line.

[0009] Optionally, the preset time period is the first half of the power frequency cycle and the second half of the power frequency cycle at the fault time point.

[0010] Optionally, determining a power mean index of a corresponding phase according to a plurality of instantaneous phase powers of each phase within the preset time includes:

[0011] For each phase, the power mean index is determined according to the following formula:

[0012]

[0013] Among them, Δp(m) is the power mean index, N s is the number of sampling points within half of the power frequency cycle, t is the time, and m is the fault time point.

[0014] Optionally, determining a fault criterion value of each feeder according to a power mean index of each phase of each feeder includes:

[0015] The sum of the power mean indexes of each phase corresponding to the feeder is used as the fault criterion value of the corresponding feeder.

[0016] Optionally, determining a plurality of instantaneous phase powers of each phase of each feeder within a preset time period includes:

[0017] Acquire multiple phase voltages and multiple phase currents of each phase of each feeder within the preset time period;

[0018] The product of the phase voltage and the phase current corresponding to each sampling point in the preset time period is used as the instantaneous phase power corresponding to the sampling point to obtain multiple instantaneous phase powers of the corresponding phase.

[0019] Optionally, when the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, before determining that a single-phase grounding fault occurs in the feeder, the method further includes:

[0020] The current zero-sequence voltage is determined according to the current phase voltage of the bus, and the difference between the current zero-sequence voltage and the zero-sequence voltage determined last time is used as the zero-sequence voltage mutation amount.

[0021] Optionally, the action threshold is greater than zero;

[0022] The reliability coefficient is greater than or equal to 1.1 and less than or equal to 1.2.

[0023] According to another aspect of the present invention, a single-phase grounding fault detection device is provided, and the single-phase grounding fault detection device comprises:

[0024] An initial judgment module is used to determine that a single-phase grounding fault occurs in the feeder when the zero-sequence voltage mutation amount of the bus is greater than or equal to a voltage change threshold; wherein the voltage change threshold is a ratio of a preset voltage mutation amount to a reliability coefficient;

[0025] A power mean index determination module, used to determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine the power mean index of the corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes the fault time point;

[0026] The fault judgment module is used to determine the fault criterion value of each feeder according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, determine that the feeder corresponding to the fault criterion value is a fault line.

[0027] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0028] at least one processor; and

[0029] a memory communicatively connected to the at least one processor; wherein,

[0030] The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can execute the single-phase grounding fault detection method described in any embodiment of the present invention.

[0031] According to another aspect of the present invention, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the single-phase grounding fault detection method described in any embodiment of the present invention when executed.

[0032] According to another aspect of the present invention, a computer program product is provided. The computer program product comprises a computer program. When the computer program is executed by a processor, the single-phase grounding fault detection method according to any embodiment of the present invention is implemented.

[0033] The technical solution of the embodiment of the present invention determines that a single-phase grounding fault occurs in the feeder when the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, and the voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient, and the preset voltage mutation amount is the zero-sequence voltage mutation amount of the bus when the high-resistance grounding fault occurs. By setting the voltage change threshold to the ratio of the preset voltage mutation amount to the reliability coefficient, when the grounding resistance is large, that is, when the high-resistance grounding fault occurs, it can still be determined according to the voltage change threshold whether a single-phase grounding fault occurs, thereby improving the accuracy of single-phase grounding fault detection. After determining that there is a single-phase grounding fault in the line, the fault criterion value of each feeder can be determined by determining the power mean index of each phase of each feeder. According to the fault criterion value, it can be determined whether the corresponding feeder is faulty, so that it can be determined which feeder has a single-phase grounding fault. In this way, there is no need to obtain multiple zero-sequence current information of all feeders, which can reduce the difficulty of fault detection. And by judging through the power mean index determined by the instantaneous phase power, when a ground fault occurs, the instantaneous phase power may change greatly. The instantaneous phase power is related to the voltage and current of the phase. Even when the zero-sequence current is small, the instantaneous phase power can be large, which makes it easier to detect fault information and improves the accuracy of fault detection.

[0034] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 is a flow chart of a single-phase grounding fault detection method provided by an embodiment of the present invention;

[0037] Figure 2 is a flow chart of another single-phase grounding fault detection method provided by an embodiment of the present invention;

[0038] Figure 3 is a schematic diagram of a circuit structure of a power distribution network system provided by an embodiment of the present invention;

[0039] Figure 4 It is a structural schematic diagram of a single-phase grounding fault detection device provided by an embodiment of the present invention;

[0040] Figure 5It is a structural schematic diagram of an electronic device provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0042] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0043] An embodiment of the present invention provides a single-phase grounding fault detection method, which can be applied to single-phase grounding fault detection in a low-resistance grounding system, for example.

[0044] Figure 1 is a flow chart of a single-phase ground fault detection method provided by an embodiment of the present invention, referring to Figure 1 , the single-phase grounding fault detection method includes:

[0045] S110. When the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, determine that a single-phase grounding fault occurs in the feeder; wherein the voltage change threshold is the ratio of a preset voltage mutation amount to a reliability coefficient.

[0046] Specifically, when the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, it indicates that the zero-sequence voltage mutation amount is large, and it can be determined that there is a single-phase grounding fault in the line. Among them, the voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient. The preset voltage mutation amount is the bus zero-sequence voltage mutation amount during a high-resistance grounding fault. By setting the voltage change threshold to the ratio of the preset voltage mutation amount to the reliability coefficient, when the grounding resistance is large, that is, when there is a high-resistance grounding fault, it can still be determined whether a single-phase grounding fault occurs according to the voltage change threshold, thereby improving the accuracy of single-phase grounding fault detection.

[0047] Furthermore, by introducing a reliability coefficient, for example, the reliability coefficient is greater than 1, the voltage change threshold is set to be slightly greater than the preset voltage mutation amount, which can ensure the accuracy of fault judgment and avoid misjudgment, thereby further improving the accuracy of fault detection.

[0048] S120. Determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine a power mean index of a corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes a fault time point.

[0049] Specifically, after determining that there is a single-phase grounding fault in the line, it is necessary to determine which feeder has the single-phase grounding fault. The distribution network includes multiple feeders, each of which includes at least one phase line, for example, each feeder includes three phase lines, that is, includes three-phase electricity.

[0050] For each phase line, multiple instantaneous phase powers within a preset time period are calculated, that is, the instantaneous phase power corresponding to each sampling point within the preset time period is calculated, so that the power mean index of the corresponding phase can be calculated based on the multiple instantaneous phase powers, so as to judge whether the corresponding feeder is faulty based on the power mean index of each phase. In addition, if the preset time period includes the fault time point, it is possible to determine whether the corresponding feeder is faulty based on the multiple instantaneous phase powers near the fault time point, so as to better judge whether the feeder is faulty. In this way, each feeder can be judged to determine which feeder has a single-phase grounding fault.

[0051] S130, determining a fault criterion value of each feeder according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, determining the feeder corresponding to the fault criterion value as a fault line.

[0052] Specifically, the fault criterion value of each feeder is determined according to the power mean index of each phase of each feeder. For example, for each feeder, the fault criterion value of the corresponding feeder is determined according to the power mean of the three phases, and the fault criterion value is compared with the action threshold. When the fault criterion value is greater than or equal to the action threshold, it indicates that the fault criterion of the corresponding feeder is large, that is, the power mean index is large, that is, within the preset time period, the change of the instantaneous phase power is large, so as to determine the corresponding feeder fault. In this way, each feeder can be judged to determine which feeder has a single-phase grounding fault. In addition, there is no need to obtain multiple zero-sequence current information of all feeders, which can reduce the difficulty of fault detection, reduce the amount of calculation, and is fast and easy to implement. And the power mean index determined by the instantaneous phase power is used for judgment. When a grounding fault occurs, the change of the instantaneous phase power may be large. The instantaneous phase power is related to the voltage and current of the phase. Even when the zero-sequence current is small, the instantaneous phase power can be large, so that it is easy to detect the fault information and improve the accuracy of fault detection.

[0053] The technical solution of this embodiment determines that a single-phase grounding fault occurs in the feeder when the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold. The voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient. The preset voltage mutation amount is the zero-sequence voltage mutation amount of the bus when a high-resistance grounding fault occurs. By setting the voltage change threshold to the ratio of the preset voltage mutation amount to the reliability coefficient, when the grounding resistance is large, that is, when a high-resistance grounding fault occurs, it can still be determined according to the voltage change threshold whether a single-phase grounding fault occurs, thereby improving the accuracy of single-phase grounding fault detection. After determining that a single-phase grounding fault exists in the line, the fault criterion value of each feeder can be determined by determining the power mean index of each phase of each feeder. According to the fault criterion value, it can be determined whether the corresponding feeder is faulty, so that it can be determined which feeder has a single-phase grounding fault. In this way, there is no need to obtain multiple zero-sequence current information of all feeders, which can reduce the difficulty of fault detection. And by judging through the power mean index determined by the instantaneous phase power, when a ground fault occurs, the instantaneous phase power may change greatly. The instantaneous phase power is related to the voltage and current of the phase. Even when the zero-sequence current is small, the instantaneous phase power can be large, which makes it easier to detect fault information and improves the accuracy of fault detection.

[0054] On the basis of the above technical solution, optionally, the preset time period is the first half of the power frequency cycle and the second half of the power frequency cycle of the fault time point. In this way, it can be ensured that the preset time period includes the fault time point and includes an entire power frequency cycle, and the change in instantaneous phase power within a power frequency cycle can be determined, thereby facilitating the improvement of the accuracy of fault judgment.

[0055] On the basis of the above technical solution, optionally, determining the power mean index of the corresponding phase according to multiple instantaneous phase powers of each phase within a preset time includes:

[0056] For each phase, the power mean index is determined according to the following formula:

[0057]

[0058] Among them, Δp(m) is the power mean index, N s is the number of sampling points within half a power frequency cycle, t is the time, and m is the fault time point.

[0059] Specifically, by calculating p(t)-p(tN s ), the difference between the instantaneous phase power of the sampling point corresponding to time t in the second half of the power frequency cycle and the instantaneous phase power of the sampling point before half of the power frequency cycle can be calculated. By summing and then dividing by the number of sampling points, the mean of the power difference can be calculated, thereby determining the power mean index. In this way, according to the power mean index formula, the power mean index of each phase can be calculated, and the change in the instantaneous phase power of each phase can be determined, so as to determine whether the corresponding feeder is faulty according to the change in the instantaneous phase power.

[0060] In some embodiments, the power mean index of any phase can be expressed as:

[0061]

[0062] Wherein, j=1, 2, ..., n, j represents the line number of the feeder, and n is an integer; Indicates a phase, for example, phase A, phase B, or phase C. In this way, the power average index of each phase can be determined according to the power average index of any phase.

[0063] On the basis of the above technical solutions, Figure 2 is a flowchart of another single-phase grounding fault detection method provided by an embodiment of the present invention. Optionally, refer to Figure 2 , single-phase ground fault methods include:

[0064] S210, determining a current zero-sequence voltage according to the current phase voltage of the bus, and taking the difference between the current zero-sequence voltage and the zero-sequence voltage determined last time as a zero-sequence voltage mutation amount.

[0065] Specifically, a voltage transformer can be set at the bus to measure the bus phase voltage in real time, and a current transformer can be set at the head end of each feeder to measure the phase current of each feeder in real time. The current phase voltage of the bus can be decomposed to obtain the current zero-sequence voltage of the bus. The difference between the current zero-sequence voltage and the zero-sequence voltage determined last time is taken as the zero-sequence voltage mutation amount.

[0066] S220. When the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, determine that a single-phase grounding fault occurs in the feeder; wherein the voltage change threshold is the ratio of a preset voltage mutation amount to a reliability coefficient.

[0067] S230. Acquire multiple phase voltages and multiple phase currents of each phase of each feeder within a preset time period.

[0068] Specifically, a voltage transformer is set at the busbar to measure the busbar phase voltage in real time, and a current transformer is set at the head end of each feeder to measure the phase current of each feeder in real time. Multiple phase voltages and multiple phase currents of each phase of each feeder within a preset time period are recorded to facilitate determination of the instantaneous phase power of each feeder within the preset time period.

[0069] S240: taking the product of the phase voltage and the phase current corresponding to each sampling point in the preset time period as the instantaneous phase power corresponding to the sampling point, so as to obtain a plurality of instantaneous phase powers of the corresponding phases.

[0070] For example, the instantaneous phase power of each line is The phase voltage of each line is The phase current of each line is Then the instantaneous phase power of each line at time t is Wherein, j=1, 2, ..., n, j represents the line number of the feeder, and n is an integer; Indicates a phase, for example, phase A, phase B, or phase C. In this way, the instantaneous phase power corresponding to each phase line can be calculated, which is convenient for calculating the power mean index corresponding to each phase line.

[0071] S250. Determine a power average index of a corresponding phase according to multiple instantaneous phase powers of each phase within a preset time to determine a power average index of each phase of each feeder; wherein the preset time period includes a fault time point.

[0072] S260: taking the sum of the power mean indexes of each phase corresponding to the feeder as the fault criterion value of the corresponding feeder.

[0073] Specifically, for each feeder, the power mean index of each phase is added to obtain the fault criterion value of the corresponding feeder. The fault criterion value can represent the total power change of the feeder, that is, the total power change of the corresponding feeder can be determined according to the power change of all phases. Then, based on the total power change of the feeder, it can be judged whether the power on the feeder changes greatly, thereby determining whether the feeder is faulty.

[0074] For example, the fault criterion value corresponding to feeder j is A j , for example, each feeder includes three phases A, B, and C, then

[0075] S270, determine whether there is a fault criterion value greater than or equal to the action threshold, if so, execute step S280; if not, return to execute step S210.

[0076] Specifically, by comparing the fault criterion value of each feeder with the action threshold, it is possible to determine whether each feeder is faulty, thereby finding the feeder where the single-phase grounding fault occurs. If the fault criterion values ​​of all feeders are less than the action threshold, the process returns to step S210 to continue to determine the zero-sequence voltage.

[0077] S280. Determine that the feeder corresponding to the fault criterion value that is greater than or equal to the action threshold is a faulty line.

[0078] Specifically, when there is a fault criterion value greater than or equal to the action threshold, the feeder corresponding to the fault criterion value greater than or equal to the action threshold is the fault line, so that the feeder where the single-phase grounding fault occurs can be accurately determined, facilitating timely maintenance.

[0079] Based on the above technical solutions, optionally, the action threshold is greater than zero;

[0080] The reliability coefficient is greater than or equal to 1.1 and less than or equal to 1.2.

[0081] Specifically, when a ground fault occurs in the feeder, the resistance is large, the phase voltage is large, the phase power is large, the instantaneous phase power changes greatly, and the fault judgment value is large. By setting the action threshold to be greater than zero, it is possible to accurately determine whether the feeder is faulty. By setting the reliability coefficient to be greater than or equal to 1.1 and less than or equal to 1.2, so that the voltage change threshold is slightly larger than the preset voltage mutation amount (the bus zero-sequence voltage mutation amount during a high-resistance ground fault), the accuracy of fault judgment can be guaranteed, misjudgment can be avoided, and the accuracy of fault detection can be further improved.

[0082] For example, Figure 3 is a schematic diagram of a circuit structure of a power distribution network system provided by an embodiment of the present invention, such as Figure 3 As shown, the distribution network system is a 10kV low-resistance grounding system. The distribution network system includes a busbar 1 and four feeder lines (i.e., feeders) connected to the busbar 1, namely, the first feeder L1, the second feeder L2, the third feeder L3, and the fourth feeder L4. Each feeder line includes overhead lines and cable lines of different lengths. The first feeder L1 includes the first cable line, the second cable line, and the third cable line. The length of the first cable line is l 11 =3km, the length of the second cable line l 12 =3km, the length of the third cable line l 13=3km. The second feeder line L2 includes a first overhead line, a second overhead line and a third overhead line. The length of the first overhead line is l 21 =4km, the length of the second overhead line l 22 =5km, the length of the third overhead line l 23 =6km. The third feeder line L3 includes a fourth cable line, a fourth overhead line and a fifth overhead line. The length of the fourth cable line is l 31 =3km, the length of the fourth overhead line l 32 =6km, the length of the fifth overhead line l 33 =4km. The fourth feeder line L4 includes a sixth overhead line, a fifth cable line and a sixth cable line. The length of the sixth overhead line is l 41 =5km, the length of the fifth cable line l 42 =5km, the length of the sixth cable line l 43 =2km.

[0083] The distribution network system includes a power supply 2, a first transformer 3, multiple second transformers 4 and a current transformer 5; the power supply 2 is connected to the first side of the first transformer 3, and the second side of the first transformer 3 is connected to the bus 1; each feeder is connected to the first side of the second transformer 4; the current transformer 5 is arranged at the head end of the feeder.

[0084] Table 1 is a schematic table of line parameters. As shown in Table 1, the cable line is set according to the resistance value, inductance value and capacitance value to the ground of the cable line shown in Table 1, and the overhead line is set according to the resistance value, inductance value and capacitance value to the ground of the overhead line shown in Table 1.

[0085] Table 1 Line parameter diagram

[0086]

[0087] For example, the sampling frequency is set to 5 kHz to obtain the phase voltage and phase current, wherein the voltage change threshold is 0.1 kV and the action threshold is 10.

[0088] Taking the fault line as the first feeder L1 as an example, the fault point F1 is set, the fault grounding resistance is 100Ω, the fault initial phase angles are 0°, 45° and 90° respectively (that is, the time of the fault occurrence is different), and the single-phase grounding fault detection device provided by any implementation scheme of the present invention is calculated to obtain the fault criterion value A1 of the first feeder L1, the fault criterion value A2 of the second feeder L2, the fault criterion value A3 of the third feeder L3 and the fault criterion value A4 of the fourth feeder L4.

[0089] Table 2 Test results corresponding to different fault initial phase angles

[0090] Fault initial phase angle <![CDATA[A1 / kW]]> <![CDATA[A2 / kW]]> <![CDATA[A3 / kW]]> <![CDATA[A4 / kW]]> Test results 0° 198.32 -0.09 -0.10 -0.09 1 45° 191.65 -1.28 -1.27 -1.04 1 90° 190.98 -1.78 -1.77 -1.47 1

[0091] Table 2 shows the test results corresponding to different fault initial phase angles. As shown in Table 2, no matter what the fault initial phase angle is, the fault criterion value A1 of the first feeder L1 is greater than the action threshold, and the fault criterion value of the non-fault line is smaller, less than the action threshold. Therefore, it can be determined that the detection result is 1, that is, the fault line is the first feeder L1. Therefore, the single-phase grounding fault detection method provided in this embodiment is applicable to the case of different fault initial phase angles.

[0092] Taking the third feeder L3 as an example, the fault points are set to F2, F3 and F4, the fault grounding resistance is 100Ω, the fault initial phase angle is 90°, and the fault criterion values ​​of each feeder are calculated when the fault points are F2, F3 and F4 according to the single-phase grounding fault detection method provided by any implementation scheme of the present invention. The test results of different fault points are shown in Table 3.

[0093] Table 3 Test results corresponding to different fault points

[0094] Failure Point <![CDATA[A1 / kW]]> <![CDATA[A2 / kW]]> <![CDATA[A3 / kW]]> <![CDATA[A4 / kW]]> Test results F -1.75 -1.78 191.13 -1.47 3 F -1.75 -1.78 176.87 -1.47 3 F -1.75 -1.77 167.57 -1.47 3

[0095] Table 3 shows the test results corresponding to different fault points. As shown in Table 3, the fault criterion value A3 of the third feeder L3 is greater than the action threshold, and the detection result can be determined to be 3, that is, a single-phase grounding fault occurs in the third feeder L3. When the fault position changes, the fault criterion value A3 of the third feeder L3 is still greater than the action threshold, and the single-phase grounding fault detection method provided by the embodiment of the present invention is not affected by the fault position and can accurately detect the fault.

[0096] Taking the fault line as the first feeder L1 as an example, the fault point F1 is set, the fault grounding resistance is 0Ω, 50Ω, 100Ω, 1000Ω and 2000Ω respectively, the fault initial phase angle is 90°, and the single-phase grounding fault detection method provided by any embodiment of the present invention is used to calculate the fault criterion values ​​of each feeder when the fault grounding resistance is 0Ω, 50Ω, 100Ω, 1000Ω and 2000Ω respectively. The test results of different fault grounding resistances are shown in Table 4.

[0097] Table 4 Test results corresponding to different fault resistances

[0098]

[0099] Table 4 shows the test results corresponding to different fault resistances. As shown in Table 4, no matter how much the fault resistance is, the fault criterion value A1 of the first feeder L1 is greater than the action threshold, and the fault criterion value of the non-fault line is smaller, less than the action threshold. Therefore, it can be determined that the detection result is 1, that is, the fault line is the first feeder L1. Therefore, the single-phase grounding fault detection method provided in this embodiment is applicable to situations with different fault resistances. Even when the grounding resistance reaches 2000Ω, the fault can still be accurately identified, and it has good applicability. The single-phase grounding fault detection method provided in this embodiment has the advantage of strong tolerance to transition resistance.

[0100] In summary, the single-phase grounding fault detection method provided by the embodiment of the present invention can accurately identify the fault under different fault initial phase angles, different fault locations, and different fault resistances, and has good performance.

[0101] The present invention also provides a single-phase grounding fault detection device, which can be used to execute the single-phase grounding fault detection method provided by any embodiment of the present invention. Figure 4 Schematic diagram of a single-phase ground fault detection device provided by an embodiment of the present invention. Figure 4 As shown, the single-phase grounding fault detection device includes: an initial judgment module 101, a power average index determination module 102 and a fault judgment module 103;

[0102] The initial judgment module 101 is used to determine that a single-phase grounding fault occurs in the feeder when the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold; wherein the voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient;

[0103] The power mean index determination module 102 is used to determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine the power mean index of the corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes the fault time point;

[0104] The fault judgment module 103 is used to determine the fault criterion value of each feeder according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, determine that the feeder corresponding to the fault criterion value is a fault line.

[0105] The single-phase grounding fault detection device provided in the embodiment of the present invention can execute the single-phase grounding fault detection method provided in any embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0106] Figure 5 is a schematic diagram of the structure of an electronic device provided by an embodiment of the present invention. Figure 5A schematic diagram of the structure of an electronic device 10 that can be used to implement an embodiment of the present invention is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processing, cellular phones, smart phones, wearable devices (such as helmets, glasses, watches, etc.) and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely examples and are not intended to limit the implementation of the present invention described and / or required herein.

[0107] like Figure 5 As shown, the electronic device 10 includes at least one processor 11, and a memory connected to the at least one processor 11, such as a read-only memory (ROM) 12, a random access memory (RAM) 13, etc., wherein the memory stores a computer program that can be executed by at least one processor, and the processor 11 can perform various appropriate actions and processes according to the computer program stored in the read-only memory (ROM) 12 or the computer program loaded from the storage unit 18 to the random access memory (RAM) 13. In the RAM 13, various programs and data required for the operation of the electronic device 10 can also be stored. The processor 11, the ROM 12, and the RAM 13 are connected to each other through a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0108] A number of components in the electronic device 10 are connected to the I / O interface 15, including: an input unit 16, such as a keyboard, a mouse, etc.; an output unit 17, such as various types of displays, speakers, etc.; a storage unit 18, such as a disk, an optical disk, etc.; and a communication unit 19, such as a network card, a modem, a wireless communication transceiver, etc. The communication unit 19 allows the electronic device 10 to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0109] The processor 11 may be a variety of general and / or special processing components with processing and computing capabilities. Some examples of the processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any appropriate processor, controller, microcontroller, etc. The processor 11 executes the various methods and processes described above, such as a single-phase ground fault detection method.

[0110] In some embodiments, the single-phase ground fault detection method may be implemented as a computer program, which is tangibly contained in a computer-readable storage medium, such as a storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or installed on the electronic device 10 via the ROM 12 and / or the communication unit 19. When the computer program is loaded into the RAM 13 and executed by the processor 11, one or more steps of the single-phase ground fault detection method described above may be performed. Alternatively, in other embodiments, the processor 11 may be configured to perform the single-phase ground fault detection method in any other appropriate manner (e.g., by means of firmware).

[0111] Various implementations of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), systems on chips (SOCs), load programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various implementations can include: being implemented in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which can be a special purpose or general purpose programmable processor that can receive data and instructions from a storage system, at least one input device, and at least one output device, and transmit data and instructions to the storage system, the at least one input device, and the at least one output device.

[0112] Computer programs for implementing the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, so that when the computer program is executed by the processor, the functions / operations specified in the flow chart and / or block diagram are implemented. The computer program may be executed entirely on the machine, partially on the machine, partially on the machine and partially on a remote machine as a stand-alone software package, or entirely on a remote machine or server.

[0113] In the context of the present invention, a computer-readable storage medium may be a tangible medium that may contain or store a computer program for use by or in combination with an instruction execution system, device or equipment. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices or equipment, or any suitable combination of the foregoing. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. A more specific example of a machine-readable storage medium may include an electrical connection based on one or more lines, a portable computer disk, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber, a portable compact disk read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0114] To provide interaction with a user, the systems and techniques described herein may be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and a pointing device (e.g., a mouse or trackball) through which the user can provide input to the electronic device. Other types of devices may also be used to provide interaction with the user; for example, the feedback provided to the user may be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user may be received in any form (including acoustic input, voice input, or tactile input).

[0115] The systems and techniques described herein may be implemented in a computing system that includes backend components (e.g., as a data server), or a computing system that includes middleware components (e.g., an application server), or a computing system that includes frontend components (e.g., a user computer with a graphical user interface or a web browser through which a user can interact with implementations of the systems and techniques described herein), or a computing system that includes any combination of such backend components, middleware components, or frontend components. The components of the system may be interconnected by any form or medium of digital data communication (e.g., a communication network). Examples of communication networks include: a local area network (LAN), a wide area network (WAN), a blockchain network, and the Internet.

[0116] A computing system may include a client and a server. The client and the server are generally remote from each other and usually interact through a communication network. The client and server relationship is generated by computer programs running on the corresponding computers and having a client-server relationship with each other. The server may be a cloud server, also known as a cloud computing server or cloud host, which is a host product in the cloud computing service system to solve the defects of difficult management and weak business scalability in traditional physical hosts and VPS services.

[0117] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the present invention can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solution of the present invention can be achieved, and this document does not limit this.

[0118] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A single-phase ground fault detection method, characterized in that: include: When the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, it is determined that a single-phase grounding fault occurs in the feeder; wherein the voltage change threshold is the ratio of the preset voltage mutation amount to the reliability coefficient; Determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine the power mean index of the corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes the fault time point; The fault criterion value of each feeder is determined according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, the feeder corresponding to the fault criterion value is determined to be a fault line.

2. The method according to claim 1, characterized in that The preset time period is the first half of the power frequency cycle and the second half of the power frequency cycle at the fault time point.

3. The method according to claim 2, characterized in that Determining a power average index of a corresponding phase according to a plurality of instantaneous phase powers of each phase within the preset time includes: For each phase, the power mean index is determined according to the following formula: Among them, Δp(m) is the power mean index, N s is the number of sampling points within half of the power frequency cycle, t is the time, and m is the fault time point.

4. The method according to claim 1, characterized in that: Determining a fault criterion value of each feeder according to a power average index of each phase of each feeder includes: The sum of the power mean indexes of each phase corresponding to the feeder is used as the fault criterion value of the corresponding feeder.

5. The method according to claim 1, characterized in that: Determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, including: Acquire multiple phase voltages and multiple phase currents of each phase of each feeder within the preset time period; The product of the phase voltage and the phase current corresponding to each sampling point in the preset time period is used as the instantaneous phase power corresponding to the sampling point to obtain multiple instantaneous phase powers of the corresponding phase.

6. The method according to claim 1, characterized in that When the zero-sequence voltage mutation amount of the bus is greater than or equal to the voltage change threshold, before determining that a single-phase grounding fault occurs in the feeder, the method further includes: The current zero-sequence voltage is determined according to the current phase voltage of the bus, and the difference between the current zero-sequence voltage and the zero-sequence voltage determined last time is used as the zero-sequence voltage mutation amount.

7. The method according to any one of claims 1 to 6, characterized in that: The action threshold is greater than zero; The reliability coefficient is greater than or equal to 1.1 and less than or equal to 1.

2.

8. A single-phase grounding fault detection device, characterized in that: include: An initial judgment module is used to determine that a single-phase grounding fault occurs in the feeder when the zero-sequence voltage mutation amount of the bus is greater than or equal to a voltage change threshold; wherein the voltage change threshold is a ratio of a preset voltage mutation amount to a reliability coefficient; A power mean index determination module, used to determine multiple instantaneous phase powers of each phase of each feeder within a preset time period, and determine the power mean index of the corresponding phase according to the multiple instantaneous phase powers of each phase within the preset time, so as to determine the power mean index of each phase of each feeder; wherein the preset time period includes the fault time point; The fault judgment module is used to determine the fault criterion value of each feeder according to the power average index of each phase of each feeder, and when the fault criterion value is greater than or equal to the action threshold, determine that the feeder corresponding to the fault criterion value is a fault line.

9. An electronic device, characterized in that: The electronic device comprises: at least one processor; and a memory communicatively connected to the at least one processor; wherein, The memory stores a computer program executable by the at least one processor, and the computer program is executed by the at least one processor so that the at least one processor can perform the single-phase grounding fault detection method according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer instructions, and the computer instructions are used to enable a processor to implement the single-phase grounding fault detection method according to any one of claims 1 to 7 when executed.

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