Test case configuration method and device for single-phase earth fault identification function of power distribution network

Abstract

The invention relates to the technical field of power system protection, and particularly provides a power distribution network single-phase earth fault identification function test case configuration method and device, and the method comprises the steps: obtaining a fault identification difficulty factor of a power distribution network single-phase earth fault identification function test case and a corresponding difficulty level; configuring a test case set for the power distribution network single-phase earth fault identification function test experiment in the power distribution network single-phase earth fault identification function test case library according to the grounding mode of the power distribution network and the different difficulty levels corresponding to the fault identification difficulty factors; wherein the test cases in the test case set at least comprise different difficulty levels corresponding to the fault identification difficulty factors in different grounding modes. According to the technical scheme provided by the invention, the fault identification difficulty influence factor of the fault waveform case characteristic of the test case is calibrated, and the reliability of the fault identification function of the power distribution equipment can be comprehensively verified based on the fault identification difficulty influence factor.

Description

Technical Field

[0001] The present invention relates to the technical field of power system protection, and in particular to a test case configuration method and device for a single-phase grounding fault identification function of a distribution network. Background Art

[0002] At present, the distribution network has installed distribution terminals, line fault indicators and other distribution automation equipment on a large scale to identify single-phase grounding in the distribution network. According to statistics, the number of distribution terminals has exceeded 1.4 million, but the accuracy of judging grounding faults is only high within the grounding transition resistance of 1kΩ, reaching more than 90%. However, most of the real grounding faults in the distribution network are high-resistance grounding, instantaneous grounding and arc grounding faults, and there are many types of grounding faults in the distribution network. The accuracy of identifying single-phase grounding faults of distribution automation equipment actually connected to the grid is less than 30%.

[0003] The main reasons for the low accuracy of single-phase grounding fault identification in distribution networks are:

[0004] (1) The steady-state electrical quantity of the distribution network grounding fault is weak and easily submerged by the load current signal. Therefore, the fault identification sensitivity and reliability of the steady-state method are low. At present, the transient method is mostly used in practical engineering. However, since the amplitude of the transient signal is significantly reduced when the voltage crosses zero, the characteristic signal of the grounding fault is similar to the characteristic signal of the power quality problem of the distribution network, which can easily cause the fault to be unable to be identified or misjudged.

[0005] (2) The actual operating conditions of the distribution network are complex, and the faults are highly random. The characteristics of electrical quantities during faults are usually affected by factors such as the system operation mode and the nature of the fault point, presenting different fault characteristics. Traditional fault diagnosis methods that use different identification and judgment principles have high accuracy for identifying certain specific transient characteristics, but have poor accuracy for identifying single-phase grounding faults in complex and changeable distribution networks.

[0006] (3) Distribution networks widely use ungrounded or arc-suppression coil grounding methods. Small current grounding faults occur more frequently. The fault current is small, the fault quantity is not prominent, and the arc is unstable. Especially after compensation by the arc-suppression coil, the zero-sequence current of the fault line is often smaller than that of the non-fault line. At the same time, about 15% of small current grounding faults have intermittent arcing phenomena and unstable fault currents. The traditional fault diagnosis method that relies on analyzing the change trend of the voltage and current characteristic vectors of the fault line to determine whether a fault has occurred is difficult to accurately identify.

[0007] At present, the verification of the grounding fault identification function of distribution equipment mainly relies on configuring a certain number of distribution network grounding fault test cases to verify whether it has the fault identification function. Considering that there are many types of distribution network grounding faults and the fault waveform characteristics are complex and changeable, the test cases used for grounding fault identification function verification should cover all types of distribution network grounding faults and characteristic information. However, the existing grounding fault identification function verification test cases are only configured according to two dimensions: simple neutral point grounding method and transition resistance size, and cannot truly cover all fault types and complex changing characteristics of the distribution network. In addition, the neutral point grounding method and transition resistance size are used to divide the fault types based on the steady-state quantity characteristics of the fault waveform, without the complex transient characteristics that are difficult to identify and easy to cause misjudgment. Therefore, the factory verification fault handling accuracy rate is 100%, while the actual engineering application fault handling accuracy rate is only 50-60%. Summary of the invention

[0008] In order to overcome the above-mentioned defects, the present invention proposes a test case configuration method and device for the single-phase grounding fault identification function of a distribution network.

[0009] In a first aspect, a test case configuration method for a single-phase grounding fault identification function of a distribution network is provided, the test case configuration method for a single-phase grounding fault identification function of a distribution network comprising:

[0010] Obtain the fault identification difficulty factor and its corresponding difficulty level of the distribution network single-phase grounding fault identification function test case;

[0011] According to the grounding mode of the distribution network and the different difficulty levels corresponding to each fault identification difficulty factor, a test case set is configured for the distribution network single-phase grounding fault identification function test experiment in the distribution network single-phase grounding fault identification function test case library;

[0012] The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes.

[0013] Preferably, the fault identification difficulty factor includes at least one of the following: zero-pressure transient mutation amount, zero-pressure steady-state mutation amount, zero-flow transient mutation amount, zero-flow steady-state mutation amount, fault mutation duration, zero-flow waveform distortion rate, zero-pressure steepness, zero-pressure harmonic high-frequency content, zero-flow harmonic high-frequency content, zero-pressure mutation amount time composite amount, zero-flow mutation amount time composite amount, zero-pressure steepness time composite amount, multi-cycle zero-pressure composite increment, multi-cycle zero-flow composite increment.

[0014] Preferably, the grounding methods of the distribution network include: neutral point ungrounded system, grounding through arc suppression coil and low resistance grounding.

[0015] Furthermore, the process of obtaining the zero-pressure transient mutation amount includes:

[0016] Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz;

[0017] Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform;

[0018] Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform;

[0019] Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform;

[0020] Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform;

[0021] Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

[0022] Furthermore, the process of obtaining the zero-pressure steady-state mutation amount includes:

[0023] Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform;

[0024] The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

[0025] Furthermore, the process of obtaining the fault mutation duration includes:

[0026] Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform;

[0027] Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula:

[0028]

[0029] In the above formula, T Uk is the fault mutation duration, N Uk2 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0030] Furthermore, the process of obtaining the zero-flow waveform distortion rate includes:

[0031] The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform;

[0032] The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic;

[0033] The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate;

[0034] The zero pressure steepness is determined by the following formula:

[0035]

[0036] In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

[0037] Furthermore, the process of obtaining the high-frequency content of zero-voltage harmonics includes:

[0038] The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0039] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

[0040] Furthermore, the process of obtaining the high frequency content of zero-current harmonics includes:

[0041] The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0042] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

[0043] Furthermore, the zero-pressure mutation time composite quantity is as follows:

[0044] S UT =U △max ×T Uk

[0045] In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

[0046] Furthermore, the zero flow mutation time composite quantity is as follows:

[0047] S IT =I △max ×T Uk

[0048] In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

[0049] Furthermore, the zero pressure steepness time composite quantity is as follows:

[0050] S DT =D N ×T D

[0051] In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

[0052] Furthermore, the process of obtaining the zero-pressure steepness time is as follows:

[0053] Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula:

[0054]

[0055] In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0056] Furthermore, the multi-cycle zero-pressure compound increment is as follows:

[0057]

[0058] In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0059] Furthermore, the multi-cycle zero-current composite increment is as follows:

[0060]

[0061] In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0062] Furthermore, the difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

[0063] In a second aspect, a test case configuration device for a single-phase grounding fault identification function of a distribution network is provided, wherein the test case configuration device for a single-phase grounding fault identification function of a distribution network comprises:

[0064] An acquisition module, used to obtain a fault identification difficulty factor and a corresponding difficulty level of a test case of a single-phase grounding fault identification function of a distribution network;

[0065] A configuration module, for configuring a test case set for a distribution network single-phase grounding fault identification function test experiment in a distribution network single-phase grounding fault identification function test case library according to the grounding mode of the distribution network and different difficulty levels corresponding to each fault identification difficulty factor;

[0066] The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes.

[0067] Preferably, the fault identification difficulty factor includes at least one of the following: zero-pressure transient mutation amount, zero-pressure steady-state mutation amount, zero-flow transient mutation amount, zero-flow steady-state mutation amount, fault mutation duration, zero-flow waveform distortion rate, zero-pressure steepness, zero-pressure harmonic high-frequency content, zero-flow harmonic high-frequency content, zero-pressure mutation amount time composite amount, zero-flow mutation amount time composite amount, zero-pressure steepness time composite amount, multi-cycle zero-pressure composite increment, multi-cycle zero-flow composite increment.

[0068] Preferably, the grounding methods of the distribution network include: neutral point ungrounded system, grounding through arc suppression coil and low resistance grounding.

[0069] Furthermore, the process of obtaining the zero-pressure transient mutation amount includes:

[0070] Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz;

[0071] Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform;

[0072] Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform;

[0073] Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform;

[0074] Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform;

[0075] Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

[0076] Furthermore, the process of obtaining the zero-pressure steady-state mutation amount includes:

[0077] Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform;

[0078] The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

[0079] Furthermore, the process of obtaining the fault mutation duration includes:

[0080] Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform;

[0081] Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula:

[0082]

[0083] In the above formula, T Uk is the fault mutation duration, N Uk2To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0084] Furthermore, the process of obtaining the zero-flow waveform distortion rate includes:

[0085] The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform;

[0086] The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic;

[0087] The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate;

[0088] The zero pressure steepness is determined by the following formula:

[0089]

[0090] In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

[0091] Furthermore, the process of obtaining the high-frequency content of zero-voltage harmonics includes:

[0092] The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0093] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

[0094] Furthermore, the process of obtaining the high frequency content of zero-current harmonics includes:

[0095] The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0096] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

[0097] Furthermore, the zero-pressure mutation time composite quantity is as follows:

[0098] S UT =U △max ×T Uk

[0099] In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

[0100] Furthermore, the zero flow mutation time composite quantity is as follows:

[0101] S IT =I △max ×T Uk

[0102] In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

[0103] Furthermore, the zero pressure steepness time composite quantity is as follows:

[0104] S DT =D N ×T D

[0105] In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

[0106] Furthermore, the process of obtaining the zero-pressure steepness time is as follows:

[0107] Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula:

[0108]

[0109] In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0110] Furthermore, the multi-cycle zero-pressure compound increment is as follows:

[0111]

[0112] In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0113] Furthermore, the multi-cycle zero-current composite increment is as follows:

[0114]

[0115] In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0116] Furthermore, the difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

[0117] In a third aspect, a computer device is provided, comprising: one or more processors;

[0118] The processor is configured to execute one or more programs;

[0119] When the one or more programs are executed by the one or more processors, the test case configuration method for the single-phase grounding fault identification function of the distribution network is implemented.

[0120] In a fourth aspect, a computer-readable storage medium is provided, on which a computer program is stored. When the computer program is executed, a test case configuration method for the single-phase grounding fault identification function of the distribution network is implemented.

[0121] The above one or more technical solutions of the present invention have at least one or more of the following beneficial effects:

[0122] The present invention provides a test case configuration method and device for the single-phase grounding fault identification function of a distribution network, including: obtaining the fault identification difficulty factor and its corresponding difficulty level of the test case of the single-phase grounding fault identification function of the distribution network; configuring a test case set for the test experiment of the single-phase grounding fault identification function of the distribution network in the test case library of the single-phase grounding fault identification function of the distribution network according to the grounding mode of the distribution network and the different difficulty levels corresponding to each fault identification difficulty factor; wherein the test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes. The technical solution provided by the present invention calibrates the fault identification difficulty influence factor of the fault waveform case characteristics of the test case, and based on the fault identification difficulty influence factor, the reliability of the fault identification function of the distribution equipment can be fully verified. BRIEF DESCRIPTION OF THE DRAWINGS

[0123] Figure 1 It is a flowchart of the main steps of the test case configuration method for the single-phase grounding fault identification function of the distribution network according to an embodiment of the present invention. DETAILED DESCRIPTION

[0124] The specific implementation modes of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0125] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution 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 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 are within the scope of protection of the present invention.

[0126] As disclosed in the background technology, at present, the distribution network has installed distribution terminals, line fault indicators and other distribution automation equipment on a large scale to identify single-phase grounding in the distribution network. According to statistics, the number of distribution terminals has exceeded 1.4 million, but the accuracy of judging grounding faults within the grounding transition resistance of 1kΩ is relatively high, reaching more than 90%. However, most of the real grounding faults in the distribution network are high-resistance grounding, instantaneous grounding and arc grounding faults, and there are many types of grounding faults in the distribution network. The accuracy of identifying single-phase grounding faults of the distribution automation equipment actually connected to the network is less than 30%.

[0127] The main reasons for the low accuracy of single-phase grounding fault identification in distribution networks are:

[0128] (1) The steady-state electrical quantity of the distribution network grounding fault is weak and easily submerged by the load current signal. Therefore, the fault identification sensitivity and reliability of the steady-state method are low. At present, the transient method is mostly used in practical engineering. However, since the amplitude of the transient signal is significantly reduced when the voltage crosses zero, the characteristic signal of the grounding fault is similar to the characteristic signal of the power quality problem of the distribution network, which can easily cause the fault to be unable to be identified or misjudged.

[0129] (2) The actual operating conditions of the distribution network are complex, and the faults are highly random. The characteristics of electrical quantities during faults are usually affected by factors such as the system operation mode and the nature of the fault point, presenting different fault characteristics. Traditional fault diagnosis methods that use different identification and judgment principles have high accuracy for identifying certain specific transient characteristics, but have poor accuracy for identifying single-phase grounding faults in complex and changeable distribution networks.

[0130] (3) Distribution networks widely use ungrounded or arc-suppression coil grounding methods. Small current grounding faults occur more frequently. The fault current is small, the fault quantity is not prominent, and the arc is unstable. Especially after compensation by the arc-suppression coil, the zero-sequence current of the fault line is often smaller than that of the non-fault line. At the same time, about 15% of small current grounding faults have intermittent arcing phenomena and unstable fault currents. The traditional fault diagnosis method that relies on analyzing the change trend of the voltage and current characteristic vectors of the fault line to determine whether a fault has occurred is difficult to accurately identify.

[0131] At present, the verification of the grounding fault identification function of distribution equipment mainly relies on configuring a certain number of distribution network grounding fault test cases to verify whether it has the fault identification function. Considering that there are many types of distribution network grounding faults and the fault waveform characteristics are complex and changeable, the test cases used for grounding fault identification function verification should cover all types of distribution network grounding faults and characteristic information. However, the existing grounding fault identification function verification test cases are only configured according to two dimensions: simple neutral point grounding method and transition resistance size, and cannot truly cover all fault types and complex changing characteristics of the distribution network. In addition, the neutral point grounding method and transition resistance size are used to divide the fault types based on the steady-state quantity characteristics of the fault waveform, without the complex transient characteristics that are difficult to identify and easy to cause misjudgment. Therefore, the factory verification fault handling accuracy rate is 100%, while the actual engineering application fault handling accuracy rate is only 50-60%.

[0132] In order to improve the above problems, the present invention provides a test case configuration method and device for the single-phase grounding fault identification function of the distribution network, including: obtaining the fault identification difficulty factor and its corresponding difficulty level of the test case of the single-phase grounding fault identification function of the distribution network; configuring a test case set for the single-phase grounding fault identification function test experiment of the distribution network in the test case library of the single-phase grounding fault identification function of the distribution network according to the grounding method of the distribution network and the different difficulty levels corresponding to each fault identification difficulty factor; wherein the test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding methods. The technical solution provided by the present invention calibrates the fault identification difficulty influence factor of the fault waveform case characteristics of the test case, and based on the fault identification difficulty influence factor, the reliability of the fault identification function of the distribution equipment can be fully verified.

[0133] The above scheme is described in detail below.

[0134] Example 1

[0135] See attached Figure 1 , Figure 1 FIG. 1 is a flow chart showing the main steps of a test case configuration method for a single-phase ground fault identification function of a distribution network according to an embodiment of the present invention. Figure 1 As shown, the test case configuration method for the single-phase grounding fault identification function of the distribution network in the embodiment of the present invention mainly includes the following steps:

[0136] Step S101: obtaining a fault identification difficulty factor and a corresponding difficulty level of a test case of a single-phase grounding fault identification function of a distribution network;

[0137] Step S102: configuring a test case set for a distribution network single-phase grounding fault identification function test experiment in a distribution network single-phase grounding fault identification function test case library according to the grounding mode of the distribution network and the different difficulty levels corresponding to each fault identification difficulty factor;

[0138] The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding methods. The fault identification difficulty factor includes at least one of the following: zero-voltage transient mutation, zero-voltage steady-state mutation, zero-current transient mutation, zero-current steady-state mutation, fault mutation duration, zero-current waveform distortion rate, zero-voltage steepness, zero-voltage harmonic high-frequency content, zero-current harmonic high-frequency content, zero-voltage mutation time composite, zero-current mutation time composite, zero-voltage steepness time composite, multi-cycle zero-voltage composite increment, multi-cycle zero-current composite increment.

[0139] In this embodiment, the grounding methods of the distribution network include: neutral point ungrounded system, grounding through arc suppression coil and small resistance grounding.

[0140] In one embodiment, the process of obtaining the zero-pressure transient mutation amount includes:

[0141] Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz;

[0142] Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform;

[0143] Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform;

[0144] Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform;

[0145] Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform;

[0146] Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

[0147] The difficulty level classification method of zero-voltage transient mutation is as follows in Table 1:

[0148] Table 1

[0149]

[0150] The method for extracting zero-flow transient mutation quantity of single influencing factor of fault identification difficulty is the same as the method for extracting zero-voltage transient mutation quantity.

[0151] The difficulty level classification method of zero-flow transient mutation is as follows in Table 2:

[0152] Table 2

[0153]

[0154]

[0155] In one embodiment, the process of obtaining the zero-pressure steady-state mutation amount includes:

[0156] Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform;

[0157] The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

[0158] The difficulty level classification method of zero-pressure steady-state mutation is as follows in Table 3:

[0159] Table 3

[0160]

[0161] The method for extracting the zero-flow steady-state mutation quantity of a single influencing factor of fault identification difficulty is the same as the method for extracting the zero-pressure steady-state mutation quantity.

[0162] The method for dividing the difficulty level of zero-flow steady-state mutation is as follows in Table 4:

[0163] Table 4

[0164]

[0165] In one embodiment, the process of obtaining the fault mutation duration includes:

[0166] Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform;

[0167] Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula:

[0168]

[0169] In the above formula, T Uk is the fault mutation duration, N Uk2 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0170] The difficulty level classification method of fault mutation duration is as follows in Table 5:

[0171] Table 5

[0172] condition Difficulty level <![CDATA[T Uk ≤2ms]]> 3 <![CDATA[2ms<T Uk <5ms]]> 2 <![CDATA[T Uk ≥5ms]]> 1

[0173] In one embodiment, the process of obtaining the zero flow waveform distortion rate includes:

[0174] The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform;

[0175] The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic;

[0176] The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate;

[0177] The difficulty level classification method of zero-current waveform harmonic distortion rate is as follows in Table 6:

[0178] Table 6

[0179]

[0180] In one embodiment, the zero pressure steepness is determined as follows:

[0181]

[0182] In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

[0183] The zero-pressure steepness difficulty level classification method is as follows in Table 7:

[0184] Table 7

[0185] condition Difficulty level <![CDATA[D N ≤500V / ms]]> 3 <![CDATA[500V / ms<D N ≤3000V / ms]]> 2 <![CDATA[D N >3000V / ms]]> 1

[0186] In one embodiment, the process of acquiring the high-frequency content of zero-voltage harmonics includes:

[0187] The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0188] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

[0189] The difficulty level classification method of zero-voltage high-frequency harmonic content is as follows in Table 8:

[0190] Table 8

[0191]

[0192] In one embodiment, the process of obtaining the high frequency content of zero-current harmonics includes:

[0193] The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0194] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

[0195] The method for dividing the difficulty level of zero-current high-frequency harmonic content is as shown in Table 9:

[0196] Table 9

[0197]

[0198] In one embodiment, the zero-pressure mutation time composite amount is as follows:

[0199] S UT =U △max ×T Uk

[0200] In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

[0201] The difficulty level classification method of zero-pressure mutation and time compound quantity is as follows in Table 10:

[0202] Table 10

[0203] condition Difficulty level <![CDATA[S UT ≤2000]]> 3 <![CDATA[2000<S UT ≤16000]]> 2 <![CDATA[S UT >40000]]> 1

[0204] In one embodiment, the zero flow mutation time composite quantity is as follows:

[0205] S IT =I △max ×T Uk

[0206] In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

[0207] The difficulty level classification method of zero flow mutation quantity and time composite quantity is as follows in Table 11:

[0208] Table 11

[0209] condition Difficulty level <![CDATA[S IT ≤2]]> 3 <![CDATA[2<S IT ≤6]]> 2 <![CDATA[S IT >6]]> 1

[0210] In one embodiment, the zero pressure steepness time composite is as follows:

[0211] S DT =D N ×T D

[0212] In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

[0213] In one embodiment, the zero pressure steepness time is obtained as follows:

[0214] Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula:

[0215]

[0216] In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0217] The method for dividing the difficulty level of zero-pressure steepness time composite quantity is as follows in Table 12:

[0218] Table 12

[0219]

[0220]

[0221] In one embodiment, the multi-cycle zero-pressure compound increment is as follows:

[0222]

[0223] In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0224] The method for dividing the difficulty level of multi-cycle zero-pressure compound increment is as follows in Table 13:

[0225] Table 13

[0226] condition Difficulty level <![CDATA[U AVG ≤1000]]> 3 <![CDATA[1000<U AVG ≤6000]]> 2 <![CDATA[U AVG >6000]]> 1

[0227] In one embodiment, the multi-cycle zero-flow composite increment is as follows:

[0228]

[0229] In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0230] The method for dividing the difficulty level of multi-cycle zero-pressure compound increment is as shown in Table 14:

[0231] Table 14

[0232] condition Difficulty level <![CDATA[I AVG ≤2]]> 3 <![CDATA[2<I AVG ≤6]]> 2 <![CDATA[I AVG >6]]> 1

[0233] In one embodiment, the difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

[0234] In a specific implementation, it is assumed that a single-phase grounding fault waveform database of the distribution network is available, and a test case set that can effectively verify the grounding fault identification function needs to be extracted from the database. Assuming that a minimum number of test case sets are configured, the configured test case set should include three grounding methods: a neutral point ungrounded system, a grounding system through an arc suppression coil, and a low-resistance grounding system. Each grounding method covers different difficulty levels of different fault difficulty identification factors, that is, each grounding method should include at least three zero-voltage transient mutation difficulty levels and three zero-voltage steady-state mutation difficulty levels. , 3 difficulty levels of zero-current transient mutation, 3 difficulty levels of zero-current steady-state mutation, 3 difficulty levels of fault mutation duration, 2 difficulty levels of zero-current waveform distortion rate, 3 difficulty levels of zero-voltage steepness, 2 difficulty levels of zero-voltage harmonic high-frequency content, 2 difficulty levels of zero-current harmonic high-frequency content, and 3 difficulty levels of zero-voltage mutation time composite, 3 difficulty levels of zero-current mutation time composite, 3 difficulty levels of zero-voltage steepness time composite, 3 difficulty levels of multi-cycle zero-voltage composite increment, 3 difficulty levels of multi-cycle zero-current composite increment, a total of 42 test cases. A total of 126 test cases under 3 grounding methods.

[0235] Example 2

[0236] Based on the same inventive concept, the present invention also provides a test case configuration device for a single-phase grounding fault identification function of a distribution network, the test case configuration device for a single-phase grounding fault identification function of a distribution network comprising:

[0237] An acquisition module, used to obtain a fault identification difficulty factor and a corresponding difficulty level of a test case of a single-phase grounding fault identification function of a distribution network;

[0238] A configuration module, for configuring a test case set for a distribution network single-phase grounding fault identification function test experiment in a distribution network single-phase grounding fault identification function test case library according to the grounding mode of the distribution network and different difficulty levels corresponding to each fault identification difficulty factor;

[0239] The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes.

[0240] Preferably, the fault identification difficulty factor includes at least one of the following: zero-pressure transient mutation amount, zero-pressure steady-state mutation amount, zero-flow transient mutation amount, zero-flow steady-state mutation amount, fault mutation duration, zero-flow waveform distortion rate, zero-pressure steepness, zero-pressure harmonic high-frequency content, zero-flow harmonic high-frequency content, zero-pressure mutation amount time composite amount, zero-flow mutation amount time composite amount, zero-pressure steepness time composite amount, multi-cycle zero-pressure composite increment, multi-cycle zero-flow composite increment.

[0241] Preferably, the grounding methods of the distribution network include: neutral point ungrounded system, grounding through arc suppression coil and low resistance grounding.

[0242] Furthermore, the process of obtaining the zero-pressure transient mutation amount includes:

[0243] Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz;

[0244] Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform;

[0245] Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform;

[0246] Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform;

[0247] Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform;

[0248] Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

[0249] Furthermore, the process of obtaining the zero-pressure steady-state mutation amount includes:

[0250] Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform;

[0251] The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

[0252] Furthermore, the process of obtaining the fault mutation duration includes:

[0253] Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform;

[0254] Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula:

[0255]

[0256] In the above formula, T Uk is the fault mutation duration, N Uk2 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0257] Furthermore, the process of obtaining the zero-flow waveform distortion rate includes:

[0258] The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform;

[0259] The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic;

[0260] The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate;

[0261] The zero pressure steepness is determined by the following formula:

[0262]

[0263] In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

[0264] Furthermore, the process of obtaining the high-frequency content of zero-voltage harmonics includes:

[0265] The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0266] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

[0267] Furthermore, the process of obtaining the high frequency content of zero-current harmonics includes:

[0268] The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz;

[0269] The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

[0270] Furthermore, the zero-pressure mutation time composite quantity is as follows:

[0271] S UT =U △max ×T Uk

[0272] In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

[0273] Furthermore, the zero flow mutation time composite quantity is as follows:

[0274] S IT =I △max ×T Uk

[0275] In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

[0276] Furthermore, the zero pressure steepness time composite quantity is as follows:

[0277] S DT =D N ×T D

[0278] In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

[0279] Furthermore, the process of obtaining the zero-pressure steepness time is as follows:

[0280] Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula:

[0281]

[0282] In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

[0283] Furthermore, the multi-cycle zero-pressure compound increment is as follows:

[0284]

[0285] In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0286] Furthermore, the multi-cycle zero-current composite increment is as follows:

[0287]

[0288] In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

[0289] Furthermore, the difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

[0290] Example 3

[0291] Based on the same inventive concept, the present invention also provides a computer device, which includes a processor and a memory, the memory is used to store a computer program, the computer program includes program instructions, and the processor is used to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gates or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, which is suitable for implementing one or more instructions, and is specifically suitable for loading and executing one or more instructions in the computer storage medium to implement the corresponding method flow or corresponding function, so as to implement the steps of the test case configuration method for the single-phase grounding fault identification function of the distribution network in the above embodiment.

[0292] Example 4

[0293] Based on the same inventive concept, the present invention also provides a storage medium, specifically a computer-readable storage medium (Memory), which is a memory device in a computer device for storing programs and data. It can be understood that the computer-readable storage medium here can include both built-in storage media in a computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides a storage space, which stores the operating system of the terminal. In addition, one or more instructions suitable for being loaded and executed by a processor are also stored in the storage space, and these instructions can be one or more computer programs (including program codes). It should be noted that the computer-readable storage medium here can be a high-speed RAM memory or a non-volatile memory, such as at least one disk memory. The processor can load and execute one or more instructions stored in the computer-readable storage medium to implement the steps of a test case configuration method for a single-phase grounding fault identification function of a distribution network in the above embodiment.

[0294] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0295] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0296] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0297] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0298] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A test case configuration method for the single-phase grounding fault identification function of a distribution network, characterized in that: The method comprises: Obtain the fault identification difficulty factor and its corresponding difficulty level of the distribution network single-phase grounding fault identification function test case; According to the grounding mode of the distribution network and the different difficulty levels corresponding to each fault identification difficulty factor, a test case set is configured for the distribution network single-phase grounding fault identification function test experiment in the distribution network single-phase grounding fault identification function test case library; The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes.

2. The method according to claim 1, characterized in that The fault identification difficulty factor includes at least one of the following: zero-pressure transient mutation amount, zero-pressure steady-state mutation amount, zero-flow transient mutation amount, zero-flow steady-state mutation amount, fault mutation duration, zero-flow waveform distortion rate, zero-pressure steepness, zero-pressure harmonic high-frequency content, zero-flow harmonic high-frequency content, zero-pressure mutation amount time composite amount, zero-flow mutation amount time composite amount, zero-pressure steepness time composite amount, multi-cycle zero-pressure composite increment, multi-cycle zero-flow composite increment.

3. The method according to claim 1, characterized in that The grounding methods of the distribution network include: a neutral point ungrounded system, grounding via an arc suppression coil, and grounding with a small resistance.

4. The method according to claim 2, characterized in that The process of obtaining the zero-voltage transient mutation amount includes: Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz; Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform; Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform; Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform; Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform; Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

5. The method according to claim 4, characterized in that The process of obtaining the zero-pressure steady-state mutation amount includes: Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform; The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

6. The method according to claim 4, characterized in that The process of obtaining the fault mutation duration includes: Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform; Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula: In the above formula, T Uk is the fault mutation duration, N Uk2 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

7. The method according to claim 6, characterized in that The process of obtaining the zero-flow waveform distortion rate includes: The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform; The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic; The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate; The zero pressure steepness is determined by the following formula: In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

8. The method according to claim 4, characterized in that The process of obtaining the high-frequency content of zero-voltage harmonics includes: The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz; The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

9. The method according to claim 4, characterized in that The process of obtaining the high frequency content of zero-current harmonics includes: The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz; The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

10. The method according to claim 6, characterized in that The zero-pressure mutation time composite quantity is as follows: WITH UT =U △max ×T Uk In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

11. The method according to claim 6, characterized in that The zero flow mutation time composite quantity is as follows: S IT =I △max ×T Uk In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

12. The method according to claim 7, characterized in that The zero pressure steepness time composite quantity is as follows: S DT =D N ×T D In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

13. The method according to claim 7, characterized in that The process of obtaining the zero-pressure steepness time is as follows: Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula: In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

14. The method according to claim 4, characterized in that The multi-cycle zero-pressure compound increment is as follows: In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

15. The method according to claim 4, characterized in that The multi-cycle zero-current composite increment is as follows: In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

16. The method according to claim 2, characterized in that The difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

17. A test case configuration device for a single-phase ground fault identification function of a distribution network, characterized in that: The device comprises: An acquisition module, used to obtain a fault identification difficulty factor and a corresponding difficulty level of a test case of a single-phase grounding fault identification function of a distribution network; A configuration module, for configuring a test case set for a distribution network single-phase grounding fault identification function test experiment in a distribution network single-phase grounding fault identification function test case library according to the grounding mode of the distribution network and different difficulty levels corresponding to each fault identification difficulty factor; The test cases in the test case set at least include different difficulty levels corresponding to each fault identification difficulty factor under different grounding modes.

18. The device according to claim 17, characterized in that The fault identification difficulty factor includes at least one of the following: zero-pressure transient mutation amount, zero-pressure steady-state mutation amount, zero-flow transient mutation amount, zero-flow steady-state mutation amount, fault mutation duration, zero-flow waveform distortion rate, zero-pressure steepness, zero-pressure harmonic high-frequency content, zero-flow harmonic high-frequency content, zero-pressure mutation amount time composite amount, zero-flow mutation amount time composite amount, zero-pressure steepness time composite amount, multi-cycle zero-pressure composite increment, multi-cycle zero-flow composite increment.

19. The device according to claim 17, characterized in that The grounding methods of the distribution network include: a neutral point ungrounded system, grounding via an arc suppression coil, and grounding with a small resistance.

20. The device according to claim 18, characterized in that The process of obtaining the zero-voltage transient mutation amount includes: Digital filtering is performed on the zero-sequence voltage waveform, and the filtering frequency band is 150-600Hz; Starting from the second cycle of the filtered zero-sequence voltage waveform, subtract the sampling point data corresponding to the previous cycle from each sampling point data of each cycle, and set the first cycle data to 0 to obtain the zero-sequence voltage mutation waveform; Taking one cycle as the integration unit, the zero-sequence voltage mutation amount waveform is integrated and the first cycle data is set to 0 to obtain the zero-sequence voltage mutation amount integral waveform; Performing a first-order difference operation on the zero-sequence voltage mutation amount integral waveform to obtain a zero-sequence voltage mutation amount integral first-order difference waveform; Taking half a cycle as the integration unit, the first-order differential waveform of the zero-sequence voltage mutation is integrated to obtain a secondary integral waveform; Find the fault mutation point on the secondary integral waveform, take the point corresponding to the fault mutation point on the zero-sequence voltage waveform as the starting point, calculate the root mean square of one cycle after the starting point of the zero-sequence voltage waveform, and obtain the zero-voltage transient mutation amount.

21. The device according to claim 20, characterized in that The process of obtaining the zero-pressure steady-state mutation amount includes: Starting from the second cycle after the starting point of the zero-sequence voltage waveform, calculate the root mean square value of each cycle of the zero-sequence voltage waveform; The average value corresponding to the root mean square value of each cycle of the zero-sequence voltage waveform is taken as the zero-voltage steady-state mutation amount.

22. The device according to claim 20, characterized in that The process of obtaining the fault mutation duration includes: Obtain the sampling point number corresponding to the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform; Taking the extreme point in the first cycle after the starting point of the zero-sequence voltage waveform as the reference, search forward and backward for the sampling point number corresponding to when the sampling value is less than or equal to the fault current starting value, and determine the duration of the fault mutation according to the following formula: In the above formula, T Uk is the fault mutation duration, N Uk2 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, N Uk1 To find the sampling point number corresponding to the sampling value less than or equal to the fault current starting value, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

23. The device according to claim 22, characterized in that The process of obtaining the zero-flow waveform distortion rate includes: The effective value of the zero-sequence current fundamental wave and the effective value of each harmonic of the zero-sequence current are obtained by Fourier transform; The effective value of each harmonic of the zero-sequence current is squared and then squared to obtain the effective value of the zero-sequence current harmonic; The ratio of the effective value of the zero-sequence current harmonic to the effective value of the zero-sequence current fundamental wave is taken as the zero-current waveform distortion rate; The zero pressure steepness is determined by the following formula: In the above formula, D N is the zero pressure steepness, U N+1 It is the data of the N+1th sampling point in the first cycle after the starting point of the zero-sequence voltage waveform, U N It is the Nth sampling point data in the first cycle after the starting point of the zero-sequence voltage waveform, and K is the number of sampling points in the first cycle.

24. The device according to claim 20, characterized in that The process of obtaining the high-frequency content of zero-voltage harmonics includes: The zero-sequence voltage waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz; The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence voltage waveform is taken as the high-frequency content of the zero-voltage harmonic.

25. The device according to claim 20, characterized in that The process of obtaining the high frequency content of zero-current harmonics includes: The zero-sequence current waveform after the starting point is filtered by a digital filter and divided into five frequency bands: 1600Hz-3200Hz, 800Hz-1600Hz, 400Hz-800Hz, 200Hz-400Hz, and 0Hz-100Hz; The ratio of the sum of the effective values ​​corresponding to each frequency band to the effective value of the zero-sequence current waveform is taken as the high-frequency content of the zero-current harmonic.

26. The device according to claim 22, characterized in that The zero-pressure mutation time composite quantity is as follows: WITH UT =U △max ×T Uk In the above formula, S UT is the time compound quantity of zero-pressure mutation, U △max is the zero-voltage transient mutation, T Uk is the fault mutation duration.

27. The device according to claim 22, characterized in that The zero flow mutation time composite quantity is as follows: S IT =I △max ×T Uk In the above formula, S IT is the time composite quantity of zero flow mutation, I △max is the zero flow transient mutation, T Uk is the fault mutation duration.

28. The device according to claim 23, characterized in that The zero pressure steepness time composite quantity is as follows: S DT =D N ×T D In the above formula, S DT is the zero pressure steepness time composite quantity, D N is the zero pressure steepness, T D is the zero pressure steepness time.

29. The device according to claim 23, characterized in that The process of obtaining the zero-pressure steepness time is as follows: Let the sampling point number of the first cycle after the starting point of the zero-sequence voltage waveform when the zero-voltage steepness is greater than 500V / ms be N D1 , from N D1 Start searching and obtain the sampling point number N when the zero voltage steepness is less than 500V / ms D2 , and the zero pressure steepness time is determined by the following formula: In the above formula, f is the waveform sampling frequency, fs is the power frequency, and t is the duration of one cycle.

30. The device according to claim 20, characterized in that The multi-cycle zero-pressure compound increment is as follows: In the above formula, U AVG is a multi-cycle zero-pressure compound increment, U X It is the RMS value of the Xth cycle after the starting point of the zero-sequence voltage waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

31. The device according to claim 20, characterized in that The multi-cycle zero-current composite increment is as follows: In the above formula, I AVG is the multi-cycle zero-current composite increment, I X It is the RMS value of the Xth cycle after the starting point of the zero-sequence current waveform, and X is the total number of cycles after the starting point of the zero-sequence voltage waveform.

32. The device according to claim 18, characterized in that The difficulty level corresponding to the fault identification difficulty factor is divided based on the value of the fault identification difficulty factor.

33. A computer device, characterized in that: include: one or more processors; The processor is configured to execute one or more programs; When the one or more programs are executed by the one or more processors, the test case configuration method for the single-phase grounding fault identification function of the distribution network as described in any one of claims 1 to 16 is implemented.

34. A computer-readable storage medium, characterized in that: A computer program is stored thereon, and when the computer program is executed, a test case configuration method for a single-phase grounding fault identification function of a distribution network is implemented as claimed in any one of claims 1 to 16.

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