A line selection method for active intervention arc extinguishing device considering busbar grounding fault

Abstract

The present invention relates to the technical field of relay protection for distribution networks, and discloses a line selection method for an active intervention type arc extinguishing device taking into account a busbar grounding fault, wherein the zero-sequence voltage 3U0 and the minimum line voltage U lmin When a single-phase grounding fault occurs in the 10kV distribution network, the startup criterion starts the fault handling procedure of the device, including the line selection procedure of the active intervention arc extinguishing device taking into account the busbar grounding fault. This program can quickly and accurately select the faulty line or faulty busbar, and reliably output the line selection result through the line selection result anti-shake calculation program.

Description

Technical Field

[0001] The invention relates to the technical field of relay protection for distribution networks, and in particular to a line selection method for an active intervention type arc extinguishing device taking into account a busbar grounding fault. Background Art

[0002] In recent years, a new switch-type arc extinguishing and line selection device has appeared in the power grid. It adopts a single-phase grounding fault phase steady-state grounding transfer method to achieve arc extinguishing, line selection, and personal protection functions. The device is not grounded during normal operation. When a single-phase grounding occurs in the line, the fault phase switch is quickly closed in the substation to directly ground the fault phase and shunt the fault point capacitive current in parallel to achieve natural arc extinguishing at the single-phase grounding point; the fault phase, human body, and earth are forced to be at the same potential to achieve personal step-by-step electric shock protection; a steady-state grounding method is used to limit intermittent grounding overvoltage. This new technology has significant advantages in principle, but further research is still needed in terms of line selection criteria and compatibility with existing grounding methods.

[0003] At present, the line selection technology based on the maximum increment method uses the change characteristics of the zero-sequence current before and after the grounding action of the phase-separated grounding switch of the switch-type arc extinguishing device to accurately select the grounding line. However, for scenarios such as high-resistance grounding or small system capacitance current, the line selection algorithm based on the maximum increment method is not applicable and has a low accuracy rate. A new single-phase grounding fault algorithm is urgently needed. Summary of the invention

[0004] Technical issues solved

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to propose a line selection method for an active intervention arc extinguishing device taking into account bus grounding faults, so as to solve the problem that the switch-type arc extinguishing line selection device fails based on the maximum increment method when it is high-resistance or broken grounding. This line selection algorithm is not only suitable for the working conditions of grounding faults such as metallic grounding, arc grounding, high-resistance grounding, and broken grounding, but also can adapt to the scenario of bus grounding faults, accurately and quickly select the faulty line, avoid misselecting and cutting the wrong line, resulting in loss of power supply reliability, and reduce user complaints.

[0006] Technical Solution

[0007] In order to achieve the above technical objectives and the above technical effects, the present invention is implemented through the following technical solutions:

[0008] A method for selecting a line for an active intervention type arc extinguishing device taking into account a busbar grounding fault, characterized in that: using three-phase voltage, the minimum line voltage U Lmin ≥90V, and zero sequence voltage 3U0≥15V, the line selection procedure is started according to the judgment. The line selection procedure steps are as follows:

[0009] Line selection program start input: each feeder zero sequence current sampling value 3I0 L1 、3I0L2 、3I0 L3 ……3I0 Ln ; The number of lines put into operation L; The two lines with the largest amplitude 3I0 max1 、3I0 max2 , the initial value is 0;

[0010] Step 1: Screening of effective sampling values: Screening of feeder L 1 ~L n The zero-sequence sampling value is the minimum linear range of the small CT (i.e., the current transformer) sampled by the control device as the sampling effective boundary value I lset , judge one by one 3I0<I lset The circuit, and the cycle L = L-1, 3I0 ≥ I lset , L remains unchanged, and after the screening and judgment is completed, go to step 2;

[0011] Step 2: Sampling sample determination: determine whether L≥1 is established; if established, proceed to step 3; if not established, directly output "line sampling sample abnormality, line selection failed", and the program ends;

[0012] Step 3: Amplitude comparison method 1: Select the largest line 3I0 Lx Assign the vector to Go to step 4;

[0013] Step 4: Comparison Method 1: Judgment Is it true, where 3I0 max1 is the line with the largest amplitude of zero-sequence current among all lines, and 3U0 is the zero-sequence voltage; if it is established, Lx is judged to be the fault line and the line selection is completed; if it is not established, go to step 5;

[0014] Step 5: Determine the number of sample elements twice: Determine whether the number of lines L≥2 is true; if not, proceed to step 6; if yes, proceed to step 7;

[0015] Step 6: Comparison Method 2: Judgment Is it true, where 3I0 max1 is the line with the largest amplitude of zero-sequence current among all lines, and 3U0 is the zero-sequence voltage; if it is established, it is judged as "busbar single-phase grounding fault" and the line selection process ends; if it is not established, it is judged as "line selection failure" and the line selection process ends;

[0016] Step 7: Amplitude comparison method 2: Select the largest line Ly except Lx and convert 3I0 Ly Assign the vector to Calculation Is it true, where 3I0 max2 is the line with the second largest amplitude among all the lines’ zero-sequence currents, and 3U0 is the zero-sequence voltage; if true, go to step 4; if not, go to step 8;

[0017] Step 8: Phase comparison method 3: Judgment Among them 3I0 max2 is the line with the second amplitude of zero-sequence current among all lines, and 3U0 is the zero-sequence voltage; if it is established, Ly is judged to be a single-phase grounding fault line; if it is not established, go to step 9;

[0018] Step 9: Judgement and Is it established? If established, it is judged that the busbar is single-phase grounding fault and the line selection process ends; if not established, it is judged as "line selection failure" and the line selection process ends;

[0019] If the line selection result is unique and remains for 10ms within 10ms after the line selection program is started, the line selection result is output;

[0020] In the above, the primary group amplitude comparison and monomer phase comparison method: select the maximum zero-sequence current Assign to At the same time is the reference phase, the line zero-sequence current with the maximum amplitude is The reference phase is in the range of -45° to -135°, and the fault line of the line with the maximum amplitude Lx is determined, otherwise a secondary amplitude and phase comparison is performed;

[0021] The two lines Lx and Ly with the largest secondary group ratio and amplitude are The second largest line of the starting amplitude is compared with the phase. As the reference phase, the fault line Ly with the second largest amplitude is determined in the range of -45° to -135°.

[0022] Preferably, the line selection procedure is started using the three-phase voltage, the minimum line voltage U Lmin ≥90V, and zero-sequence voltage, 3U0≥15V criterion to start the line selection procedure.

[0023] Preferably, the zero-sequence current data elements are cleaned to obtain the number L of sample elements of valid sampling values.

[0024] Preferably, if the primary and secondary group amplitude comparison and monomer phase comparison methods fail, the maximum amplitude and second largest line phase comparison method is used. As the reference phase, in the range of 45° to 135°, determine that the single-phase grounding fault element is the busbar single-phase grounding.

[0025] Preferably, after the device is started, the line is selected 20 times continuously within 10 ms at a sampling frequency of 2 kHz. The line selection program result is required to be unique and maintained for 10 ms within 10 ms after the line selection program is started, and then the line selection result is output.

[0026] The beneficial effects of the present invention are:

[0027] (1) The method of the present invention starts the line selection procedure through the three-phase voltage (minimum line voltage U_Lmin≥90V) and zero-sequence voltage (3U0≥15V) criteria, avoiding the false start of 3U0≥15V that may occur due to the phase-to-phase short circuit fault.

[0028] (2) The method of the present invention uses a small CT, i.e., the minimum value of the linear range of the current transformer, as a threshold, to clean the zero-sequence current data elements and obtain the number L of sample elements of valid sampling values.

[0029] (3) The method of the present invention adopts a progressive method: the group amplitude ratio method is used to select the line with the maximum amplitude of the zero-sequence current, and the single unit of this line is based on The phase comparison method is used to select the fault line, and the second largest zero-sequence current line is selected by the secondary group amplitude comparison method. Phase comparison method, select the fault line, through the zero sequence current maximum and second maximum value line based on Use the phase comparison method to determine whether there is a bus fault. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 A flow chart of a line selection method for an active intervention type arc extinguishing device taking into account a busbar grounding fault provided by an embodiment of the present invention;

[0031] Figure 2 A logic diagram of the start conditions of the line selection algorithm provided in an embodiment of the present invention;

[0032] Figure 3 A logic diagram of anti-shake design for line selection results provided by an embodiment of the present invention;

[0033] Figure 4 A wiring diagram of zero-sequence sampling and voltage sampling provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Those skilled in the art will appreciate that, unless otherwise stated, the singular forms "a", "an", "said" and "the" used herein may also include plural forms. It should be further understood that the term "comprising" used in the specification of the present application refers to the presence of the features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0036] It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as the general understanding of those skilled in the art to which this application belongs. It should also be understood that terms such as those defined in general dictionaries should be understood to have the same meaning as in the context of the prior art, and will not be interpreted with an idealized or overly formal meaning unless specifically defined as in the embodiments of this application.

[0037] See also Figure 1-4 , Figure 1 A flow chart of a method for selecting a line of an active intervention type arc extinguishing device taking into account a busbar grounding fault is provided in an embodiment of the present invention. The present invention provides a method for selecting a line of an active intervention type arc extinguishing device taking into account a busbar grounding fault, which specifically includes the following steps:

[0038] Reference Figure 2 , voltage criterion starts the line selection procedure:

[0039] Line selection program start input: zero-sequence current sampling value of each feeder

[0040] 3I0 L1 、3I0 L2 、3I0 L3 ……3I0 Ln ; The number of lines put into operation L; The two lines with the largest amplitude 3I0 max1 、3I0 max2 (The initial value is 0).

[0041] Step 1: Screening of effective sampling values: Screening of feeder L 1 ~L n The zero-sequence sampling value is the minimum linear range of the small CT (i.e., the current transformer) sampled by the control device as the sampling effective boundary value I lset . Judge 3I0<I one by one lset 3I0≥I lset , L remains unchanged. After the screening is completed, proceed to step 2.

[0042] Step 2: Sampling sample determination: determine whether L≥1 is established; if established, proceed to step 3; if not established, directly output "line sampling sample abnormality, line selection failed", and the program ends.

[0043] Step 3: Amplitude comparison method 1: Select the largest line 3I0 Lx Assign the vector to Go to step 4.

[0044] Step 4: Comparison Method 1: Judgment Is it true? If so, Lx is judged to be a faulty line and the line selection ends; if not, go to step 5.

[0045] Step 5: Determine the number of sample elements twice: Determine whether the number of lines L≥2 holds; if not, proceed to step 6; if so, proceed to step 7.

[0046] Step 6: Comparison Method 2: Judgment Is it true? If so, it is judged as "busbar single-phase grounding fault" and the line selection process ends; if not, it is judged as "line selection failure" and the line selection process ends.

[0047] Step 7: Amplitude comparison method 2: Select the largest line Ly except Lx and convert 3I0 Ly Assign the vector to Calculation Is it true? If so, go to step 4; if not, go to step 8.

[0048] Step 8: Phase comparison method 3: Judgment If so, Ly is judged to be a single-phase grounding fault line; if not, go to step 9.

[0049] Step 9: Judgement and Is it established? If established, it is judged that the busbar is in a single-phase grounding fault and the line selection process ends. If not established, it is judged as "line selection failure" and the line selection process ends.

[0050] Reference Figure 3 , set the anti-shake program, the line selection result is within 10ms after the line selection program is started, the line selection result is unique and maintained for 10ms, then the line selection result is output.

[0051] Reference Figure 4 The active intervention arc suppression line selection device collects the value of zero-sequence current of each feeder, as well as the secondary three-phase voltage, zero-sequence opening voltage, and grounding switch position signal as the starting conditions of the line selection program.

[0052] The line selection program is started by using the three-phase voltage (minimum line voltage U Lmin≥90V) and zero-sequence voltage (3U0≥15V) are used as the criteria to start the line selection program, thus avoiding false start due to 3U0≥15V that may occur due to phase-to-ground short-circuit fault.

[0053] Clean the zero-sequence current data elements and obtain the number L of sample elements of valid sampling values.

[0054] Primary group amplitude comparison and monomer phase comparison method: select the maximum zero-sequence current Assign to At the same time is the reference phase, the line zero-sequence current with the maximum amplitude is The reference phase is in the range of -45° to -135° to determine the fault line with the maximum amplitude Lx.

[0055] The two lines Lx and Ly with the largest secondary group ratio and amplitude are The second largest line of the starting amplitude is compared with the phase. As the reference phase, the fault line Ly with the second largest amplitude is determined in the range of -45° to -135°.

[0056] If the first and second group amplitude comparison and monomer phase comparison methods fail, the phase comparison method of the largest amplitude and the second largest line is used. As the reference phase, in the range of 45° to 135°, determine that the single-phase grounding fault element is the busbar single-phase grounding.

[0057] After the device is started, within a continuous 10ms, at a sampling frequency of 2kHz, the line selection is performed 20 times continuously. The line selection program result is required to be unique and maintained for 10ms within 10ms after the line selection program is started, and then the line selection result is output.

[0058] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for selecting a line for an active intervention type arc extinguishing device taking into account a busbar grounding fault, characterized in that: Using three-phase voltage, the minimum line voltage U Lmin ≥90V, and zero sequence voltage 3U0≥15V, the line selection procedure is started according to the judgment. The line selection procedure steps are as follows: Line selection program start input: zero-sequence current sampling value of each feeder 3I0 L1 、3I0 L2 、3I0 L3 ……3I0 Ln ; The number of lines put into operation L; The two lines with the largest amplitude 3I0 max1 、3I0 max2 , the initial value is 0; Step 1: Screening of effective sampling values: Screening of feeder lines L1 to L n The zero-sequence sampling value is the minimum linear range of the small CT (i.e., the current transformer) sampled by the control device as the sampling effective boundary value I lset , judge one by one 3I0<I lset The circuit, and the cycle L = L-1, 3I0 ≥ I lset , L remains unchanged, and after the screening and judgment is completed, go to step 2; Step 2: Sampling sample determination: determine whether L≥1 is established; if established, proceed to step 3; if not established, directly output "line sampling sample abnormality, line selection failed", and the program ends; Step 3: Amplitude comparison method 1: Select the largest line 3I0 Lx Assign the vector to Go to step 4; Step 4: Comparison Method 1: Judgment Is it true, where 3I0 max1 is the line with the largest amplitude of zero-sequence current among all lines, and 3U0 is the zero-sequence voltage; if it is established, Lx is judged to be the fault line, and the line selection is completed; If not, go to step 5; Step 5: Determine the number of sample elements twice: Determine whether the number of lines L≥2 is true; if not, proceed to step 6; if yes, proceed to step 7; Step 6: Comparison Method 2: Judgment Is it true, where 3I0 max1 is the line with the largest amplitude of zero-sequence current among all lines, and 3U0 is the zero-sequence voltage; if it is established, it is judged as "busbar single-phase grounding fault" and the line selection process ends; if it is not established, it is judged as "line selection failure" and the line selection process ends; Step 7: Amplitude comparison method 2: Select the largest line Ly except Lx and convert 3I0 Ly Assign the vector to Calculation Is it true, where 3I0 max2 is the line with the second largest amplitude among all the lines’ zero-sequence currents, and 3U0 is the zero-sequence voltage; if true, go to step 4; if not, go to step 8; Step 8: Phase comparison method 3: Judgment Among them 3I0 max2 is the line with the second largest amplitude among all the lines’ zero-sequence currents, and 3U0 is the zero-sequence voltage; if this is true, Ly is judged to be a single-phase grounding fault line; If not, go to step 9; Step 9: Judgement and Is it established? If established, it is judged that the busbar is in single-phase grounding fault and the line selection process ends; if not established, it is judged as "line selection failure" and the line selection process ends; If the line selection result is unique and remains for 10ms within 10ms after the line selection program is started, the line selection result is output; Primary group amplitude comparison and monomer phase comparison method: select the maximum zero-sequence current Assign to At the same time is the reference phase, the line zero-sequence current with the maximum amplitude is The reference phase is in the range of -45° to -135°, and the fault line of the line with the maximum amplitude Lx is determined, otherwise a secondary amplitude and phase comparison is performed; The two lines Lx and Ly with the largest secondary group ratio and amplitude are The second largest line of the starting amplitude is compared with the phase. As the reference phase, the fault line Ly with the second largest amplitude is determined in the range of -45° to -135°.

2. The method for selecting a line for an active intervention type arc extinguishing device taking into account a busbar grounding fault according to claim 1, characterized in that: The line selection program is started by using the three-phase voltage, the minimum line voltage U Lmin ≥90V, and zero-sequence voltage, 3U0≥15V criterion to start the line selection procedure.

3. The method for selecting a line for an active intervention type arc extinguishing device taking into account a busbar grounding fault according to claim 1, characterized in that: Clean the zero-sequence current data elements and obtain the number L of sample elements of valid sampling values.

4. The method for selecting a line for an active intervention type arc extinguishing device taking into account a busbar grounding fault according to claim 1, characterized in that: If the first and second group amplitude comparison and monomer phase comparison methods fail, the phase comparison method of the largest amplitude and the second largest line is used. As the reference phase, in the range of 45° to 135°, determine that the single-phase grounding fault element is the busbar single-phase grounding.

5. The line selection method of active intervention type arc extinguishing device taking into account busbar grounding fault according to claim 1 is characterized in that: After the device is started, within a continuous 10ms, at a sampling frequency of 2kHz, the line selection is performed 20 times continuously. The line selection program result is required to be unique and maintained for 10ms within 10ms after the line selection program is started, and then the line selection result is output.

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