Coal mine power grid route selection method, system, device and medium thereof

Abstract

The present application relates to the technical field of coal mine power grid leakage protection, and particularly relates to a coal mine power grid line selection method, system, device and medium thereof. The method comprises the following steps: obtaining zero sequence currents of each feeder in the coal mine power grid; after a single-phase grounding fault occurs, the EMD distance between the waveforms of the zero sequence currents of each feeder is calculated pairwise, and a comprehensive EMD distance matrix is calculated according to the EMD distance; abnormal values in the comprehensive EMD distance matrix are screened out based on the Grubbs criterion; it is determined whether there is an abnormal value; if there is an abnormal value, the feeder corresponding to the abnormal value is the fault feeder; if there is no abnormal value, the fault occurs at the bus. The present application provides a coal mine power grid line selection method, which has high accuracy and strong applicability, can avoid the influence of factors such as fault feeder, fault location, fault closing angle and grounding resistance, and effectively solves the problem that it is difficult to troubleshoot the fault feeder after a single-phase grounding fault occurs in the underground power grid.

Description

Technical Field

[0001] This invention relates to the field of leakage protection technology for coal mine power grids, and in particular to a method, system, equipment and medium for selecting lines in coal mine power grids. Background Technology

[0002] my country is a major coal producer, and coal production makes a significant contribution to the country's economic development. Therefore, ensuring the safety of power supply in coal mines is crucial. Single-phase grounding faults occur frequently in coal mine power grids, and accurate fault location is essential for maintaining safe power supply in these areas. Neutral-point grounding systems with arc-suppression coils are widely used in coal mine power grids. However, when a single-phase grounding fault occurs, the fault current is weak, and the fault characteristics are not obvious, making fault location in coal mine power grids a significant challenge.

[0003] Fault location methods mainly include steady-state and transient methods. The steady-state method analyzes steady-state quantities at power frequency, but its steady-state characteristics are affected by the arc suppression coil, making it difficult to apply to neutral-point grounded systems via the arc suppression coil. Since transient characteristics are unaffected by the arc suppression coil and provide rich fault information, current fault location research focuses primarily on extracting these transient characteristics. After a single-phase ground fault occurs in a neutral-point grounded system via the arc suppression coil, the zero-sequence current of non-faulty feeders is only related to the zero-sequence capacitance to ground of each feeder and the zero-sequence voltage of the busbar. Because all feeders are connected to the same busbar, the zero-sequence voltage is the same, resulting in high similarity between the zero-sequence currents of non-faulty feeders. However, the zero-sequence current of the faulty feeder is the sum of the transient zero-sequence capacitance current to ground of all feeders and the zero-sequence current flowing through the arc suppression coil. Its waveform differs significantly from the zero-sequence current of non-faulty feeders, allowing for fault location based on the difference in the zero-sequence current waveform after the fault. However, the fault location technology is affected by factors such as the fault feeder, fault location, fault closing angle and grounding resistance, which directly affects the accuracy and applicability of the fault location. Summary of the Invention

[0004] The technical problem this invention aims to solve is: to overcome the limitations of existing fault location methods, which are easily affected by factors such as fault feeders, fault locations, fault closing angles, and grounding resistance, resulting in poor accuracy and applicability of fault location. This invention provides a coal mine power grid fault location method with high accuracy and strong applicability. It can avoid the influence of factors such as fault feeders, fault locations, fault closing angles, and grounding resistance, and effectively solve the problem of difficulty in locating fault feeders after a single-phase grounding fault occurs in the underground power grid.

[0005] The technical solution adopted by this invention to solve its technical problem is: a method for selecting power grid lines in coal mines, the method comprising the following steps:

[0006] S1, obtain the zero-sequence current of each feeder in the coal mine power grid;

[0007] S2, after a single-phase ground fault occurs, calculate the EMD distance between the zero-sequence current waveforms of each feeder in pairs, and calculate the comprehensive EMD distance matrix based on the EMD distance;

[0008] S3, based on the Grubbs criterion, outliers in the comprehensive EMD distance matrix are filtered out;

[0009] S4, determine whether the abnormal value exists; if the abnormal value exists, the feeder corresponding to the abnormal value is the faulty feeder; if the abnormal value does not exist, the fault occurs at the bus.

[0010] Furthermore, specifically, step S2 includes the following steps:

[0011] S21, when the zero-sequence voltage of the bus exceeds the set value, a single-phase ground fault is determined to have occurred;

[0012] S22, collect the zero-sequence current data of each feeder within 1 / 4 cycle after the fault to perform line selection calculation;

[0013] S23, calculate the EMD distance between the zero-sequence current waveforms of each feeder pairwise to obtain the EMD distance matrix D = {d ij}, where d ij Let i be the EMD distance between feeder i and feeder j, i = 1, 2, ..., τ, j = 1, 2, ..., τ, and τ be the number of feeders connected to the busbar.

[0014] S24. According to the formula Calculate the integrated EMD distance matrix

[0015] Furthermore, specifically, step S23 includes the following steps:

[0016] S231, Suppose that after a fault, two zero-sequence current waveforms of a feeder are collected, namely S1 and S2, and let the data lengths of current waveform S1 and current waveform S2 be m and n, respectively, and the maximum value of the two current waveforms is s. max The minimum value is s min , the interval [s min ,s max The subspace is divided into σ subspaces in ascending order and labeled sequentially from 1 to σ. The formula for calculating the value of σ is:

[0017]

[0018] Where round(*) is the rounding function;

[0019] S232, calculate the frequency sequence P = {p1, p2, ..., p2} of the current waveform S1 and the current waveform S2 data samples in each subspace. σ} and Q = {q1,q2,…,q σ For the i-th subspace, the frequency p i and q i This is the ratio of the number of samples falling within this subspace to its data length;

[0020] S233, when calculating the EMD distance, the distribution of the current waveform S1 and the current waveform S2 is understood as two mounds containing σ pits. Let waveform S1 and waveform S2 correspond to the first mound and the second mound, respectively, and let p be the soil content of the i-th pit in the first mound. i The soil content of the j-th pit in the second mound is q. j If the distance from the i-th pit in the first mound to the j-th pit in the second mound is ij, then f in the i-th pit of the first mound... ij The workload of transporting one unit of soil to the j-th pit of the second soil pile is f. ij |ij|;

[0021] S234, calculate the ratio of the minimum workload of transporting all the soil from the soil pile corresponding to the current waveform S1 to the soil pile corresponding to the current waveform S2 to the total amount of soil transported, where the ratio is the EMD distance;

[0022] The minimum workload is calculated using linear programming, and its objective function is: The constraints are:

[0023]

[0024] S235, calculate f ij Value, according to f ij Value, the distance d of the EMD EMD The calculation formula is:

[0025]

[0026] Furthermore, specifically, in step S235, f ij The value is calculated using the simplex method, dual simplex method, or interior point method.

[0027] Furthermore, specifically, step S3 includes the following steps:

[0028] S31, Calculate the mean of the comprehensive EMD distance matrix based on the comprehensive EMD distance matrix. and standard deviation

[0029] S32, Calculate the residuals based on the mean and the standard deviation. According to the Grubbs criterion, the maximum residual value is e. max The corresponding measured value is the suspicious value.

[0030] S33, at a certain confidence level, consult the Grubbs coefficient table to find the critical value G(α, n);

[0031] S34, determine the suspicious value based on the critical value G(α, n). The formula for determining whether a value is outlier is as follows:

[0032]

[0033] Preferably, in step S33, the confidence level is selected as α = 0.05 or α = 0.01.

[0034] A coal mine power grid routing system, wherein the coal mine power grid routing system employs the coal mine power grid routing method as described in any one of claims 1 to 5, and the coal mine power grid routing system comprises:

[0035] The acquisition unit is used to acquire the zero-sequence current of each feeder in the coal mine power grid;

[0036] The EMD distance calculation unit is used to calculate the EMD distance between the zero-sequence current waveforms of each feeder after a single-phase ground fault occurs, and to calculate the comprehensive EMD distance matrix based on the EMD distance.

[0037] An outlier determination unit is used to filter out outliers in the integrated EMD distance matrix based on the Grubbs criterion.

[0038] The fault analysis unit is used to determine whether the abnormal value exists;

[0039] If an outlier exists, the feeder corresponding to that outlier is the faulty feeder.

[0040] If no abnormal value is found, the fault occurs at the busbar.

[0041] Furthermore, specifically, it also includes an alarm unit, used to generate alarm information based on the current fault analysis results, and to issue an alarm based on the alarm information.

[0042] A computer device includes: a processor; and a memory for storing executable instructions; wherein the processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the coal mine power grid routing method as described above.

[0043] A computer-readable storage medium storing a computer program that, when executed by a processor, causes the processor to implement the coal mine power grid line selection method as described above.

[0044] The beneficial effects of this invention are as follows: The coal mine power grid line selection method of this invention first uses EMD distance to fully reflect the differences in the zero-sequence current waveforms of each feeder, serving as a characteristic indicator for screening faulty feeders. EMD distance can be used to measure the degree of difference between two distributions. Compared with KL divergence and JS divergence, it can measure the distance even if the two distributions do not overlap, thus improving accuracy. Next, the Grubbs criterion is used to screen outliers in the comprehensive EMD distance matrix. If the comprehensive EMD distance matrix does not contain outliers, the fault point is located on the bus; otherwise, the feeder corresponding to the outlier is the faulty feeder. This embodiment has high robustness; the line selection accuracy is not affected by factors such as the faulty feeder, fault location, fault closing angle, and grounding resistance, effectively improving applicability. Furthermore, the method is simple, easy to implement, and has high line selection accuracy. Attached Figure Description

[0045] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0046] Figure 1 This is a flowchart illustrating one embodiment of the present invention.

[0047] Figure 2 This is a schematic diagram of a simulation test model for a single-phase grounding fault in a coal mine underground power grid, as implemented in this invention.

[0048] Figure 3 This is a structural schematic diagram of Embodiment 2 of the present invention.

[0049] Figure 4 This is a schematic diagram of the hardware structure of Embodiment 3 of the present invention.

[0050] In the figure, 21 is the acquisition unit; 22 is the EMD distance calculation unit; 23 is the outlier determination unit; 24 is the fault analysis unit; and 25 is the warning unit.

[0051] 10. Computer equipment; 1002. Processor; 1004. Memory; 1006. Transmission device. Detailed Implementation

[0052] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0053] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0054] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0055] Example 1

[0056] like Figure 1 As shown in the figure, this application provides a method for selecting power grid lines in a coal mine, the method including the following steps:

[0057] S1, obtain the zero-sequence current of each feeder in the coal mine power grid.

[0058] S2, after a single-phase ground fault occurs, calculate the EMD distance between the zero-sequence current waveforms of each feeder in pairs, and calculate the comprehensive EMD distance matrix based on the EMD distance.

[0059] S3, outliers in the comprehensive EMD distance matrix are selected based on the Grubbs criterion.

[0060] S4, determine if there is an outlier; if there is an outlier, the feeder corresponding to the outlier is the faulty feeder; if there is no outlier, the fault occurs at the busbar.

[0061] In this embodiment, step S2 specifically includes the following steps:

[0062] S21, when the zero-sequence voltage of the bus exceeds the set value, it is determined that a single-phase grounding fault has occurred; the set value is preferably 15% of the rated voltage, and the fault selection process is started when a single-phase grounding fault occurs.

[0063] S22, collect the zero-sequence current data of each feeder within 1 / 4 cycle after the fault to perform line selection calculation.

[0064] S23, calculate the EMD distance between the zero-sequence current waveforms of each feeder pairwise to obtain the EMD distance matrix D = {d ij}, where d ij Let be the EMD distance between feeder i and feeder j, i = 1, 2, ..., τ, j = 1, 2, ..., τ, and τ be the number of feeders connected to the bus.

[0065] S24. According to the formula Calculate the integrated EMD distance matrix

[0066] In this embodiment, step S23 specifically includes the following steps:

[0067] S231, Suppose that after a fault, two zero-sequence current waveforms of a feeder are collected, namely S1 and S2, and let the data lengths of current waveform S1 and current waveform S2 be m and n, respectively, and the maximum value of the two current waveforms be s. max The minimum value is s min , the interval [s min ,s max The subspace is divided into σ subspaces in ascending order and labeled sequentially from 1 to σ. The formula for calculating the value of σ is:

[0068]

[0069] Where round(*) is the rounding function; considering the lack of zero-sequence current sampling in the feeder, the data lengths of m and n may be different.

[0070] S232, calculate the frequency sequence P = {p1, p2, ..., p2} of the current waveform S1 and current waveform S2 data samples in each subspace. σ} and Q = {q1,q2,…,q σ For the i-th subspace, the frequency p i and q i It is the ratio of the number of samples falling within this subspace to its data length.

[0071] S233, When calculating the EMD distance, the distribution of current waveforms S1 and S2 is understood as two mounds containing σ pits. Let current waveforms S1 and S2 correspond to the first and second mounds respectively, and let p be the soil content of the i-th pit in the first mound. i The soil content of the j-th pit in the second mound is q. j Let |ij| be the distance from the i-th pit in the first mound to the j-th pit in the second mound. Then, let f be the distance from the i-th pit in the first mound.ij The workload of transporting one unit of soil to the j-th pit of the second soil pile is f. ij |ij|.

[0072] S234 calculates the ratio of the minimum workload of transporting all soil from the soil pile corresponding to current waveform S1 to the soil pile corresponding to current waveform S2 to the total amount of soil transported. The ratio is the EMD distance.

[0073] The minimum workload is calculated using linear programming, and its objective function is: The constraints are:

[0074]

[0075] S235, calculate f ij Value, according to f ij Value, EMD distance d EMD The calculation formula is:

[0076]

[0077] In this embodiment, in step S235, f ij The value is calculated using the simplex method, dual simplex method, or interior point method.

[0078] In this embodiment, step S3 specifically includes the following steps:

[0079] S31, Calculate the mean of the comprehensive EMD distance matrix based on the comprehensive EMD distance matrix. and standard deviation

[0080] S32, Calculate the residuals based on the mean and standard deviation. According to the Grubbs criterion, the maximum residual value is e. max The corresponding measured value is the suspicious value.

[0081] S33. At a certain confidence level, consult the Grubbs coefficient table as shown in the table below to find the critical value G(α, n); the confidence level is selected as α = 0.05 or α = 0.01.

[0082] Table 1. Grubbs Coefficient Table

[0083]

[0084] S34, Based on the critical value G(α, n), determine the suspicious value. The formula for determining whether a value is outlier is as follows:

[0085]

[0086] It should be noted that even if the zero-sequence current data is missing, the EMD distance calculation result will not be affected, thus improving the accuracy of the line selection method.

[0087] Test Analysis:

[0088] Building on the Simulink platform, such as Figure 2 A single-phase grounding fault simulation system for a coal mine power grid was used to verify the effectiveness of the proposed method. In this system, a 35kV surface substation supplies 6kV power to the underground mine via main transformer T0. The neutral point is drawn from the secondary side of T0 through a Z-type transformer TZ, and the neutral point is grounded via an arc suppression coil. The arc suppression coil compensation is 5%, L... N and R N The inductance and resistance of the arc suppression coil are shown. The 6kV busbar has four outgoing lines, supplying power to the downhole load through the shaft. All four feeders are modeled as cables, and their parameters are shown in Table 2. TA1 to TA4 are the current transformers near the busbar for the four feeders, with a current sampling rate of 10kHz.

[0089] Table 2 Cable feeder parameters

[0090]

[0091] A phase-A ground fault occurred on feeder 1 at a distance of 0.4 km from the busbar. The fault closing angle α0 was set to 30°, and the grounding resistance R... f Set to 2kΩ. After a fault occurs, collect zero-sequence current waveform data for one-quarter of a cycle of each feeder.

[0092] After a fault occurs, the EMD distance of the zero-sequence current waveforms of each feeder is calculated pairwise to obtain the EMD distance matrix. And calculate the integrated EMD distance matrix.

[0093] in, The calculated residuals corresponding to the four values ​​are 0.7268, 0.2894, 0.1487, and 0.2887, respectively, with the maximum residual being e. max It is 0.7268, therefore The first element, 1.6334, is a suspicious value. With a confidence level of α = 0.01, the table shows G(0.01,4) to be 1.492. This can be further calculated using the formula... The corresponding calculated result is 1.7161. According to Grubbs' criterion, The first value, 1.6334, is an outlier, which indicates that the faulty feeder is feeder 1. The line selection result is correct, and the line selection accuracy of this embodiment is high.

[0094] The feeder where the fault occurs, the location of the fault from the bus, the fault closing angle α0, and the fault grounding resistance R are all factors to consider. f The different route selection results are presented to fully illustrate the applicability of the proposed method under various fault scenarios. Table 3 shows the route selection results, where the Grubbs criterion judgment results are displayed as the integrated EMD distance matrix. The value is set to the nth outlier. If there are no outliers, the value is set to 0. The confidence level is set to α = 0.01.

[0095] Table 3 shows the route selection results of the proposed method under various fault scenarios.

[0096]

[0097] As shown in Table 3, this embodiment can achieve correct line selection under various fault scenarios, and the line selection results are highly robust to factors such as fault feeder, fault location, fault closing angle, and grounding resistance. This embodiment has strong applicability.

[0098] In summary, the EMD distance is first used to fully reflect the differences in the zero-sequence current waveforms of each feeder, serving as a characteristic indicator for screening faulty feeders. The EMD distance can measure the degree of difference between two distributions; compared to KL divergence and JS divergence, it can measure the distance even if the two distributions do not overlap, thus improving accuracy. Next, the Grubbs criterion is used to screen outliers in the comprehensive EMD distance matrix. If the comprehensive EMD distance matrix contains no outliers, the fault point is located on the bus; otherwise, the feeder corresponding to the outlier is the faulty feeder. This embodiment has high robustness; the accuracy of line selection is not affected by factors such as the faulty feeder, fault location, fault closing angle, and grounding resistance, effectively improving applicability. Furthermore, the method is simple, easy to implement, and has high line selection accuracy.

[0099] Example 2

[0100] like Figure 3 As shown in the figure, this application provides a coal mine power grid routing system. The coal mine power grid routing system adopts the above-mentioned coal mine power grid routing method and includes:

[0101] Acquisition unit 21 is used to acquire the zero-sequence current of each feeder in the coal mine power grid;

[0102] EMD distance calculation unit 22 is used to calculate the EMD distance between the zero-sequence current waveforms of each feeder after a single-phase ground fault occurs, and to calculate the comprehensive EMD distance matrix based on the EMD distance.

[0103] Outlier determination unit 23 is used to filter out outliers in the comprehensive EMD distance matrix based on the Grubbs criterion.

[0104] The fault analysis unit 24 is used to determine whether there is an abnormal value; if there is an abnormal value, the feeder corresponding to the abnormal value is the faulty feeder; if there is no abnormal value, the fault occurs at the bus.

[0105] In this embodiment, an alarm unit 25 is also included, which is used to generate alarm information based on the current fault analysis results and to issue an alarm based on the alarm information.

[0106] It should be noted that the system provided in the above embodiments is only illustrated by the division of the above functional modules when implementing its functions. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above. In addition, the system and method embodiments provided in the above embodiments belong to the same concept, and the specific implementation process can be found in the method embodiments, which will not be repeated here.

[0107] Example 3

[0108] This application provides a computer device including a processor and a memory. The memory stores at least one instruction or at least one program, which is loaded and executed by the processor to implement a coal mine power grid route selection method as provided in the above method embodiments.

[0109] Figure 4 A schematic diagram of the hardware structure of a device for implementing a coal mine power grid routing method provided in the embodiments of this application is shown. The device can participate in or include the apparatus or system provided in the embodiments of this application. Figure 4 As shown, the computer device 10 may include one or more processors 1002 (the processor may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.), a memory 1004 for storing data, and a transmission device 1006 for communication functions. In addition, it may also include: a display, an input / output interface (I / O interface), a universal serial bus (USB) port (which may be included as one of the ports of the I / O interface), a network interface, a power supply, and / or a camera. Those skilled in the art will understand that... Figure 4 The structure shown is for illustrative purposes only and does not limit the structure of the aforementioned electronic device. For example, computer device 10 may also include... Figure 4 The more or fewer components shown, or having the same Figure 4 The different configurations shown.

[0110] It should be noted that the aforementioned one or more processors and / or other data processing circuits are generally referred to herein as "data processing circuits". These data processing circuits may be embodied, in whole or in part, in software, hardware, firmware, or any other combination thereof. Furthermore, the data processing circuit may be a single, independent processing module, or may be integrated, in whole or in part, into any other element within the computer device 10 (or mobile device). As involved in the embodiments of this application, the data processing circuit serves as a processor control mechanism (e.g., selection of a variable resistor termination path connected to an interface).

[0111] The memory 1004 can be used to store software programs and modules for application software, such as the program instructions / data storage device corresponding to a coal mine power grid line selection method in this embodiment of the application. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory 1004, thereby implementing the aforementioned method. The memory 1004 may include high-speed random access memory, and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 1004 may further include memory remotely located relative to the processor, and these remote memories can be connected to the computer device 10 via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0112] The transmission device 1006 is used to receive or send data via a network. Specific examples of the network described above may include a wireless network provided by the communication provider of the computer device 10. In one example, the transmission device 1006 includes a network interface controller (NIC), which can connect to other network devices via a base station to communicate with the Internet. In another example, the transmission device 1006 may be a radio frequency (RF) module used for wireless communication with the Internet.

[0113] The display may be, for example, a touchscreen liquid crystal display (LCD) that allows the user to interact with the user interface of the computer device 10 (or mobile device).

[0114] Example 4

[0115] This application embodiment also provides a computer-readable storage medium, which can be disposed in a server to store at least one instruction or at least one program related to implementing a coal mine power grid line selection method in the method embodiment. The at least one instruction or at least one program is loaded and executed by the processor to implement the coal mine power grid line selection method provided in the above method embodiment.

[0116] Optionally, in this embodiment, the storage medium may be located at at least one of the multiple network servers in a computer network. Optionally, in this embodiment, the storage medium may include, but is not limited to, various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0117] Example 5

[0118] This invention also provides a computer program product or computer program, which includes computer instructions stored in a computer-readable storage medium. A processor of a computer device reads the computer instructions from the computer-readable storage medium and executes the computer instructions, causing the computer device to perform a coal mine power grid routing method provided in the various optional embodiments described above.

[0119] It should be noted that the order of the embodiments described above is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. Furthermore, the above description focuses on specific embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps described in the claims can be performed in a different order than that shown in the embodiments and still achieve the desired results. Additionally, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired results. In some implementations, multitasking and parallel processing are also possible or may be advantageous.

[0120] The various embodiments in this application are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the device, equipment, and storage medium embodiments are basically similar to the method embodiments, so the descriptions are relatively simple; relevant parts can be referred to the descriptions of the method embodiments.

[0121] Those skilled in the art will understand that all or part of the steps of the above embodiments can be implemented by hardware or by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as a read-only memory, a disk, or an optical disk.

[0122] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A method for selecting power grid lines in a coal mine, characterized in that, The method includes the following steps: S1, obtain the zero-sequence current of each feeder in the coal mine power grid; S2, after a single-phase ground fault occurs, calculate the EMD distance between the zero-sequence current waveforms of each feeder in pairs, and calculate the comprehensive EMD distance matrix based on the EMD distance; S3, based on the Grubbs criterion, outliers in the comprehensive EMD distance matrix are filtered out; S4, determine whether the abnormal value exists; If an outlier exists, the feeder corresponding to that outlier is the faulty feeder. If no abnormal values ​​are found, the fault occurs at the busbar. Specifically, step S2 includes the following steps: S21, when the zero-sequence voltage of the bus exceeds the set value, a single-phase ground fault is determined to have occurred; S22, collect the zero-sequence current data of each feeder within 1 / 4 cycle after the fault to perform line selection calculation; S23, calculate the EMD distance between the zero-sequence current waveforms of each feeder pairwise to obtain the EMD distance matrix. D ={ d ij },in, d ij For feeder i and feeder j EMD distance between i =1, 2, ..., τ , j =1, 2, …, τ , τ The number of feeders connected to the busbar; S24. According to the formula Calculate the integrated EMD distance matrix .

2. The coal mine power grid line selection method as described in claim 1, characterized in that, Step S23 specifically includes the following steps: S231, Suppose that the zero-sequence current waveforms of two feeders acquired after the fault are respectively... S 1 and S 2. Set the current waveform S 1 and current waveform S The data lengths of 2 are respectively m and n The maximum value of the two current waveforms is s max The minimum value is s min , will the interval [ s min , s max Divided into equal parts in ascending order σ Each subspace is sequentially labeled as 1~ σ , σ The formula for calculating the value of is: Where round(*) is the rounding function; S232, calculate the current waveforms respectively. S 1 and the current waveform S 2. Frequency sequence of data samples in each subspace P ={ p 1, p 2, …, p σ }and Q ={ q 1, q 2, …, q σ }, for the first i Subspace, frequency p i and q i This is the ratio of the number of samples falling within this subspace to its data length; S233, when calculating the EMD distance, the current waveform S 1 and the current waveform S The distribution of 2 can be understood as two elements containing σ The earthen mound of a pit, assuming the current waveform... S 1 and the current waveform S 2 corresponds to the first mound and the second mound, respectively. The first mound is... i The soil content of each pit is p i The second mound j The soil content of each pit is q j The first mound i From the first pit to the second mound j The distance between the pits is Then the first mound of earth will be... i In a pit f ij One unit of soil was transported to the second soil pile. j The workload for each pit is f ij ; S234, Calculate the current waveform S 1. The current waveform corresponds to the transport of all soil from the corresponding soil pile. S 2. The ratio of the minimum workload of the corresponding soil pile to the total amount of soil to be transported, wherein the ratio is the EMD distance; The minimum workload is calculated using linear programming, and its objective function is: The constraints are: ； S235, Calculation f ij Value, based on f ij Value, the distance of the EMD d EMD The calculation formula is: 。 3. The coal mine power grid line selection method as described in claim 2, characterized in that, In step S235 f ij The value is calculated using the simplex method, dual simplex method, or interior point method.

4. The coal mine power grid line selection method as described in claim 1, characterized in that, Step S3 specifically includes the following steps: S31, Calculate the mean of the comprehensive EMD distance matrix based on the comprehensive EMD distance matrix. and standard deviation ; S32, Calculate the residuals based on the mean and the standard deviation. e i = According to the Grubbs criterion, the maximum residual value is... e max The corresponding measured value is the suspicious value. ; S33. At a certain confidence level, consult the Grubbs coefficient table to find the critical value. G ( α , n ); S34, based on the critical value G ( α , n ), determine the suspicious value The formula for determining whether a value is outlier is as follows: 。 5. The coal mine power grid line selection method as described in claim 4, characterized in that, In step S33, the confidence level is selected as α = 0.05 or α = 0.

01.

6. A coal mine power grid line selection system, characterized in that, The coal mine power grid routing system employs the coal mine power grid routing method as described in any one of claims 1 to 5, and the coal mine power grid routing system comprises: The acquisition unit (21) is used to acquire the zero-sequence current of each feeder in the coal mine power grid; The EMD distance calculation unit (22) is used to calculate the EMD distance between the zero-sequence current waveforms of each feeder after a single-phase ground fault occurs, and to calculate the comprehensive EMD distance matrix based on the EMD distance. An outlier determination unit (23) is used to filter out outliers in the integrated EMD distance matrix based on the Grubbs criterion. The fault analysis unit (24) is used to determine whether the abnormal value exists; If an outlier exists, the feeder corresponding to that outlier is the faulty feeder. If no abnormal value is found, the fault occurs at the busbar.

7. The coal mine power grid line selection system as described in claim 6, characterized in that, It also includes an alarm unit (25) for generating alarm information based on the current fault analysis results and issuing an alarm based on the alarm information.

8. A computer device, characterized in that, include: processor; Memory, used to store executable instructions; The processor is configured to read the executable instructions from the memory and execute the executable instructions to implement the coal mine power grid route selection method as described in any one of claims 1 to 5.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, causes the processor to implement the coal mine power grid routing method as described in any one of claims 1 to 5.

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