Arc suppression coil single-phase grounding power distribution network fault diagnosis method and system

Abstract

The invention relates to the technical field of power grid fault diagnosis, in particular to an arc suppression coil single-phase grounding power distribution network fault diagnosis method and system. The method comprises the following steps of: judging whether a single-phase earth fault occurs or not by collecting a bus zero-sequence voltage and an arc suppression coil bias current and combining a threshold value; after a fault occurs, segmented isolation verification is performed according to the change amplitude of the zero-sequence voltage of each bus to position a suspected grounding line, and the positions of a grounding point and a fault point are further accurately determined through the change of the zero-sequence voltage and the zero-sequence current; and finally, adjusting the tapping point of the arc suppression coil gear by gear according to the position of the fault point, selecting the optimal compensation position and performing turn adjustment verification, thereby realizing rapid diagnosis and compensation of the single-phase earth fault. According to the invention, through multi-stage zero-sequence voltage / current analysis, topology segmentation isolation verification, time sequence curve comparison judgment and tap intelligent turn-adjusting compensation, accurate positioning and efficient arc extinction compensation of a single-phase earth fault are realized, and the diagnosis precision and the operation reliability of a power distribution network are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power grid fault diagnosis, and in particular to a method and system for diagnosing faults of an arc suppression coil single-phase grounding distribution network. BACKGROUND

[0002] The fault diagnosis technology of arc suppression coil single-phase grounding distribution network has experienced an evolution process from traditional manual detection to automatic measurement, and then to refined positioning and optimized compensation. In the early stage, fault diagnosis mainly relied on manual inspection or macroscopic measurement of bus zero sequence current and voltage, which had the problems of slow response and inaccurate positioning. With the development of distribution network automation, through real-time monitoring of bus zero sequence voltage and arc suppression coil bias current, the rapid identification of single-phase grounding fault was realized, and the suspected grounding line could be screened according to the change of bus zero sequence voltage and the topology of distribution network. Further development introduced the methods of zero sequence voltage time sequence curve analysis, comparison of reference curve and verification curve, and height and slope determination, which made the fault positioning more accurate.

[0003] However, the traditional zero sequence voltage monitoring and sectionalization method is difficult to accurately locate the fault point under the complex topology of multiple branches and multiple buses, and is prone to misjudgment or positioning delay. At the same time, the selection of arc suppression coil tapping point position mainly depends on experience or single measurement, and lacks systematic optimization adjustment means, which makes it difficult to ensure that the compensation effect reaches the best. SUMMARY

[0004] Therefore, it is necessary to provide a method and system for diagnosing faults of an arc suppression coil single-phase grounding distribution network to solve at least one of the above technical problems.

[0005] To achieve the above-mentioned purpose, a method and system for diagnosing faults of an arc suppression coil single-phase grounding distribution network, the method comprising the following steps: Step S1: obtaining bus zero sequence voltage and arc suppression coil bias current of the distribution network; and confirming whether a single-phase grounding fault occurs in the distribution network based on the comparison result of the bus zero sequence voltage and the arc suppression coil bias current with the preset voltage and current threshold value; Step S2: in response to the occurrence of single-phase grounding fault in the distribution network, confirming the change of bus zero sequence voltage of the distribution network and verifying the line segmentation isolation of the distribution network according to the change of bus zero sequence voltage, to obtain a suspected grounding line; Step S3: confirming the line grounding point based on the zero sequence voltage change of the suspected grounding line; and confirming the fault point position of the distribution network according to the zero sequence current change of the line grounding point; Step S4: confirming the best compensation position of the arc suppression coil tapping based on the fault point position and adjusting it, and verifying the turns of the adjusted arc suppression coil.

[0006] In the present specification, a fault diagnosis system for arc suppression coil single-phase grounding power distribution network is provided for implementing the above-mentioned fault diagnosis method for arc suppression coil single-phase grounding power distribution network, which comprises: A fault discrimination module is configured to acquire the bus zero sequence voltage and the arc suppression coil bias current of the power distribution network, and confirm whether the single-phase grounding fault occurs in the power distribution network based on the comparison result of the bus zero sequence voltage and the arc suppression coil bias current with the preset voltage and current threshold. A line isolation module is configured to confirm the bus zero sequence voltage change of the power distribution network and verify the line segmentation isolation of the power distribution network according to the bus zero sequence voltage change to obtain the suspected grounding line in response to the single-phase grounding fault occurring in the power distribution network. A fault point detection module is configured to confirm the line grounding point based on the zero sequence voltage change of the suspected grounding line, and confirm the fault point position of the power distribution network according to the zero sequence current change of the line grounding point. A position compensation module is configured to confirm the optimal compensation position of the arc suppression coil tap and adjust it based on the fault point position, and verify the turns of the adjusted arc suppression coil.

[0007] The present application has the following advantages: I. By combining the bus zero sequence voltage, the arc suppression coil bias current and the power distribution network topology, the single-phase grounding fault can be quickly identified and located, which can significantly improve the accuracy and real-time performance of the power distribution network fault diagnosis. Especially after the fault occurs, the fault-affected central bus can be quickly determined by comparing the change amplitude of the zero sequence voltage of each bus, and the segmentation isolation verification is carried out in combination with the topology information, so that the screening process of the suspected grounding line is more efficient and reliable, and the delay and misjudgment caused by relying on manual analysis in the traditional way are avoided.

[0008] II. By means of curve fitting based on the time sequence voltage curve, the reference curve and the verification curve are constructed, and the height difference and the slope difference are used to judge the grounding state of each line branch, which can effectively suppress noise interference and improve the sensitivity to the change of the bus zero sequence voltage, so as to accurately identify the fault line and its grounding point. This comparison and analysis mechanism not only realizes the quantitative determination of the segmentation isolation verification, but also has the advantages of clear parameter range and clear judgment standard, which is conducive to realizing automatic and intelligent diagnosis.

[0009] III. By means of step-by-step adjustment and record comparison of the tap based on the zero sequence voltage change, the optimal compensation position of the arc suppression coil is determined, and the accurate selection of the arc suppression coil tap position is realized. Through the fixed operations such as mechanical locking, position limiting protection and electrical contact confirmation, the compensation effect of the arc suppression coil after compensation is ensured to be up to standard, and the steady-state level of the power distribution network after fault recovery is improved.

[0010] Four, before the formal turn adjustment, introduce power frequency pulse signal injection and pulse response measurement mechanism, by comparing the change degree of response signal amplitude direction, can further correct fault point position, improve the accuracy of fault location result. Overall, the scheme through "fault determination - segmented isolation - grounding point confirmation - compensation adjustment - correction verification" whole process closed loop design, realizes the accurate diagnosis and efficient compensation of single-phase grounding fault, has the intelligent degree is high, the reliability is strong, the implementation effect is excellent and so on remarkable beneficial effect. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 It is a step flowchart of a fault diagnosis method and system for an arc suppression coil single-phase grounding power distribution network. Figure 2 It is Figure 1 It is a detailed implementation step flowchart of step S2. Figure 3 It is a functional module diagram of a fault diagnosis system for an arc suppression coil single-phase grounding power distribution network provided by an embodiment of the present application. The implementation of the present application, functional features and advantages will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0012] The technical method of the present application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of the present application.

[0013] In addition, the accompanying drawings are only schematic drawings of the present application, and are not necessarily drawn to scale. The same reference signs in the drawings represent the same or similar parts, and thus repeated description thereof will be omitted. Some block diagrams shown in the drawings are functional entities, which do not necessarily correspond to physically or logically independent entities. The functional entities can be implemented in software form, or in one or more hardware modules or integrated circuits, or in different network and / or processor methods and / or microcontroller methods.

[0014] It should be understood that, although the terms "first", "second" or the like can be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first element could be termed a second element, and, similarly, a second element could be termed a first element without departing from the scope of the example embodiments. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0015] To achieve the above object, please refer to Figures 1 to 3 A method for diagnosing single-phase grounding fault of arc suppression coil single-phase grounding power distribution network, the method comprising the following steps: Step S1: obtaining bus zero sequence voltage and arc suppression coil bias current of the power distribution network; and determining whether single-phase grounding fault occurs in the power distribution network based on comparison results of the bus zero sequence voltage and the arc suppression coil bias current with preset voltage and current thresholds; In an embodiment, the bus zero sequence voltage value can be collected in real time by a voltage sensor installed at the bus of the power distribution network, and the arc suppression coil bias current can be collected in real time by a current sensor in series with the arc suppression coil. The bus zero sequence voltage and the arc suppression coil bias current are sent to a fault judgment module for analysis and processing according to a fixed sampling period (for example, 100 milliseconds).

[0016] In some embodiments, the currently collected bus zero sequence voltage can be compared with a preset voltage threshold, and the arc suppression coil bias current can be compared with a preset current threshold. For example, when the value of the bus zero sequence voltage is greater than the upper limit of the voltage threshold, and the value of the arc suppression coil bias current is greater than the upper limit of the current threshold, the system determines that the power distribution network has a single-phase grounding fault; if at least one of them does not exceed the upper limit of the corresponding threshold, it is determined that the power distribution network is in a normal operating state.

[0017] For another example, in a preferred embodiment, the voltage threshold can be set to 80 volts to 120 volts, and the current threshold can be set to 2 amperes to 5 amperes. When the bus zero sequence voltage is detected to be 105 volts and the bias current is 3.1 amperes, neither of which exceeds the upper limit of the corresponding threshold, the system can determine that the power distribution network is in a normal operating state. Further, when the bus zero sequence voltage is detected to be 125 volts and the bias current is 5.5 amperes, both of which exceed the upper limit of the corresponding threshold, the fault judgment module can directly confirm that the power distribution network has a single-phase grounding fault. This setting not only ensures the reliability of fault identification, but also effectively avoids misjudgment caused by transient disturbance or transient surge.

[0018] Step S2: in response to the single-phase grounding fault of the power distribution network, confirming the change of the bus zero sequence voltage of the power distribution network and verifying the line segmentation isolation of the power distribution network according to the change of the bus zero sequence voltage to obtain a suspected grounding line; In an embodiment, after the single-phase-to-ground fault of the power distribution network is determined in step S1, the fault determination module continues to monitor the trend of the bus zero-sequence voltage to determine whether the voltage has a significant increase or decrease. The bus zero-sequence voltage can be sampled and recorded at fixed time intervals (e.g., 0.2 seconds).

[0019] The lines of the power distribution network are segmented and isolated according to a preset logic, for example, the switches of each branch are sequentially disconnected in the order of feeder. After a line segment is disconnected, the system re-detects the change of the bus zero-sequence voltage and compares the zero-sequence voltage at this time with the zero-sequence voltage before the fault occurs.

[0020] For example, when the first line branch is disconnected, if the decrease of the bus zero-sequence voltage is less than a preset decrease threshold (e.g., less than 3%), it is determined that the line branch is not a grounded line; when the second line branch is disconnected, if the decrease of the bus zero-sequence voltage is more than the preset decrease threshold (e.g., more than 3%), it is determined that the line branch is a suspected grounded line.

[0021] In a preferred embodiment, the segmentation and isolation sequence can be performed in the order of main line first and branch line second, so as to avoid mistakenly cutting off an important power supply line. When the segmentation and isolation process continuously monitors that the bus zero-sequence voltage rapidly decreases to the normal range after a line is disconnected, the system determines that the line is a suspected grounded line and takes it as an analysis object in the subsequent fault location process.

[0022] Step S3: confirming the line grounding point based on the change of the zero-sequence voltage of the suspected grounded line and confirming the fault point position of the power distribution network based on the change of the zero-sequence current of the line grounding point; In an embodiment, for the suspected grounded line determined in step S2, the system continues to collect the change data of the bus zero-sequence voltage of the line over time. By comparing the change amplitude and trend of the zero-sequence voltage before and after the grounding point, the position of the line where the change of the zero-sequence voltage is most significant is determined as a candidate position of the grounding point.

[0023] For example, the difference of the zero-sequence voltage at each node of the suspected grounded line can be calculated, and when the difference of the zero-sequence voltage exceeds a preset threshold (e.g., 5% to 10%), the node is marked as a suspected grounding point. The system can further screen the final line grounding point in combination with historical operation data and voltage fluctuation patterns.

[0024] After the grounding point is determined, the system collects the change data of the zero-sequence current of the arc suppression coil or the line for further positioning of the fault point. The specific method includes: measuring the current values of each segment along the suspected grounded line and determining the position where the current peak value appears. The zero-sequence current presents a significant increase near the fault point, which exceeds a preset current threshold (e.g., 2 to 5 amperes), and the position is determined as the actual fault point.

[0025] In a preferred embodiment, to improve the positioning accuracy, the combined analysis of zero sequence voltage and zero sequence current can be used, for example, the point where the grounding voltage changes significantly and the current reaches the peak is determined as the fault point to avoid misjudgment caused by relying on single parameter of voltage or current.

[0026] Step S4: Based on the fault point position, the optimal compensation position of the arc suppression coil tap is confirmed and adjusted, and the adjusted arc suppression coil is verified.

[0027] In an embodiment, first, the theoretical compensation current of each tap of the arc suppression coil is calculated according to the fault point position determined in step S3 and the line parameters (such as conductor length, reactance value, etc.), and the optimal compensation position of the tap is determined through an optimization algorithm (such as minimizing the bus zero sequence voltage fluctuation or zero sequence current peak). For example, the zero sequence voltage and zero sequence current response under different tap positions can be simulated or measured in real time, and by comparing the voltage deviation and current balance of each scheme, the tap position with the closest ideal zero sequence voltage and the smallest zero sequence current is selected as the optimal compensation position.

[0028] After confirming the optimal compensation position, the system controls the arc suppression coil to perform physical tap adjustment to adjust the tap to the optimal position. After adjustment, the real-time measurement of the bus zero sequence voltage and the arc suppression coil current verifies whether the tap effect meets the design requirements. If the zero sequence voltage returns to the allowable fluctuation range and the zero sequence current drops below the threshold, it is determined that the tap is successful; if it does not meet the requirements, fine tuning or re-optimization of the tap position can be performed.

[0029] In a preferred embodiment, to ensure the accuracy of the tap, a tap verification threshold can be set, for example, the zero sequence voltage deviation is not more than ±2% of the bus rated voltage, and the zero sequence current is not more than 2-5 amperes. This setting can avoid secondary zero sequence voltage fluctuation or incomplete compensation caused by improper tap adjustment, and ensure the stable operation of the distribution network.

[0030] As an example of the present application, referring to FIG. 1, in this example, step S2 includes: Figure 2 Step S21: In response to a single-phase ground fault occurring in the distribution network, collecting the zero sequence voltage change information of each bus of the distribution network and the topology structure of the distribution network; Step S22: According to the change amplitude of the zero sequence voltage change information of different buses, the bus with the maximum change amplitude is taken as the fault influence center bus; Step S23: Taking the fault influence center bus as the starting point, traversing each line branch connected to the fault influence center bus through the topology structure of the distribution network; Step S24: Each line branch is subjected to line segmentation isolation verification to obtain a suspected grounding line. ​

[0031] In an embodiment, bus zero sequence voltage data is collected in real time by each bus voltage sensor, and topology information of the power distribution network is obtained, including the connection relationship between buses, branch length, and branch conditions, to construct a power distribution network topology model and provide basic data for fault location.

[0032] The amplitude change of each bus zero sequence voltage before and after the fault occurs is calculated to obtain a zero sequence voltage change amplitude sequence. The system marks the bus with the largest change amplitude as the fault impact center bus. A zero sequence voltage change amplitude threshold is preferably set, for example, 2-5% of the rated voltage of the bus, to screen suspicious fault impact centers and avoid misjudgment due to minor fluctuations.

[0033] By breadth-first or depth-first traversal algorithm, the adjacent line branches of the fault impact center bus are scanned in turn, and the start and end nodes, length, connected buses, and branch conditions of each branch are recorded to provide a basis for subsequent line section isolation verification.

[0034] The line branches are segmented, and the zero sequence voltage and zero sequence current are measured at each segment. The zero sequence voltage fluctuation and current peak value of each segment are compared to screen out abnormal segments as suspected grounding lines. The voltage change threshold is preferably set to 3-7% of the rated voltage of the bus, and the current threshold is 2-5 A to balance the positioning accuracy and false alarm rate.

[0035] In a preferred embodiment, to improve the positioning reliability, the bus zero sequence voltage and branch zero sequence current can be combined for joint analysis. When the zero sequence voltage of a certain line branch changes significantly and the zero sequence current peak value is obvious, the branch is determined as a suspected grounding line. This method can effectively reduce the misjudgment caused by relying on a single parameter and improve the fault location accuracy.

[0036] Preferably, step S24 includes the following steps: Step S241: segmenting each line branch to obtain trunk area line branches and branch area line branches; Step S242: confirming the detection order according to the trunk area line branches and the branch area line branches, and sequentially opening the disconnecting switches corresponding to each line branch according to the detection order; Step S243: in response to the opening of the disconnecting switches, detecting the bus zero sequence voltage change of the corresponding line branch; Step S244: segmenting and isolating each line branch according to the bus zero sequence voltage change of the corresponding line branch to screen out suspected grounding lines.

[0037] In an embodiment, the line branches are divided into several sections according to the power distribution network topology and line length. The main section line branches refer to the main line sections directly connected to the fault-affected central bus, and the branch section line branches refer to the side branch line sections branched from the main section. This division helps to optimize the fault positioning sequence and reduce operation errors. Among them, the main section line branches are detected first, and then the branch section line branches are detected in turn to ensure that the fault impact along the power grid propagation path can be accurately captured. The isolation operation can be completed by remotely controlling or locally operating the isolation switch, and the isolation state of each line branch is recorded for comparative analysis of the zero sequence voltage change.

[0038] After each line branch is isolated, the bus zero sequence voltage data is collected in real time, and the voltage difference before and after isolation is calculated. If the bus zero sequence voltage recovers to the normal range or the change amplitude significantly decreases after a certain line branch is isolated, it means that the fault may be located in this section. The isolation verification results are comprehensively analyzed: if the zero sequence voltage change amplitude of the line section is still large after isolation, the section is retained as a suspected grounding line; if the change amplitude decreases or returns to normal, the section is excluded. It is preferable to set the zero sequence voltage change threshold to 3-7% of the bus rated voltage to ensure that the fault can be quickly located and misjudgment can be avoided.

[0039] In a preferred embodiment, to improve verification accuracy, the screening results can be reviewed in combination with the zero sequence current change before and after isolation. When both the zero sequence voltage and the zero sequence current change meet the abnormal characteristics, the line section is finally confirmed as a suspected grounding line. This method can effectively reduce the misjudgment caused by single parameter detection and improve the reliability of fault positioning.

[0040] Preferably, the segment isolation verification of each line branch is performed by the bus zero sequence voltage change of the corresponding line branch, including: drawing a time sequence voltage curve according to the bus zero sequence voltage change of the corresponding line branch; extracting the highest peak curve of the time sequence voltage curve and confirming the pull-apart time point corresponding to the highest peak curve; selecting time sequence windows before and after the highest peak curve based on the pull-apart time point, and confirming the sampling points in the front and rear time sequence windows; obtaining a reference curve and a verification curve through curve fitting of the sampling points in the front and rear time sequence windows; comparing the height and slope of the reference curve and the verification curve to determine the bus zero sequence voltage change of the corresponding line branch, and performing segment isolation verification on each line branch to screen out the suspected grounding line.

[0041] In an embodiment, the zero sequence voltage before and after the isolation operation of each line branch is continuously sampled, and a voltage-time curve is generated to show the dynamic change of the bus zero sequence voltage. The sampling frequency can be set to 1 Hz to 10 Hz to ensure that the short-time voltage fluctuation characteristics are captured. The highest voltage peak on the curve is automatically identified, and the corresponding time point is recorded as the triggering time of the line isolation. This time point is used to define the subsequent timing window to ensure that the analysis is focused on the key change section. The preferred timing window is set to 0.5-2 seconds before and after the highest peak, which can be adjusted according to the length of the line and the dynamic characteristics of the power grid. The continuous sampling points within the window are collected to provide data support for curve fitting.

[0042] The sampling points in the front window are fitted to obtain a reference curve representing the normal operation reference state, and the sampling points in the rear window are fitted to obtain a verification curve reflecting the dynamic change state after line isolation. The fitting method can use polynomial fitting or least squares method to ensure that the curve is smooth and can accurately extract the trend characteristics. If the peak height of the verification curve is significantly higher than that of the reference curve, and the curve slope change is greater than a set threshold (such as the slope change exceeds 0.5-1.0 V / s), it is determined that the line branch has an abnormality, and is marked as a suspected grounding line; otherwise, the section is excluded. Through this segmented isolation verification method, the fault influence of each line branch can be accurately judged, the misjudgment rate is reduced, and the positioning accuracy of the single-phase grounding fault of the distribution network is improved.

[0043] In a preferred embodiment, the superposition analysis of multiple sampling curves can be combined to further enhance the robustness to dynamic interference or transient fluctuations and ensure stable and reliable screening results.

[0044] Preferably, the height and slope of the reference curve and the verification curve are compared to determine the change of the bus zero sequence voltage of the corresponding line branch, and the segmented isolation verification of each line branch includes: The height difference determination range is set to 0.05-2.0 volts based on the height and slope of the reference curve and the verification curve, and the slope difference determination range is 0.01-0.5 volts / second; When the height difference of any line branch exceeds 0.5 volts or the slope difference exceeds 0.2 volts / second, it is determined that the line branch has an abnormality, and the line branch is marked as a suspected grounding line.

[0045] In an embodiment, the peak height and corresponding slope of the reference curve and the verification curve of each line branch are first calculated. The height difference determination range is preferably set to 0.05 to 2.0 volts to cover the normal fluctuations and slight disturbances of the power grid; the slope difference determination range is preferably set to 0.01 to 0.5 volts / second to identify the abnormality of the voltage change trend.

[0046] For each line branch, if the peak height difference of the curve compared with the reference curve exceeds 0.5 volts, or the slope difference exceeds 0.2 volts per second, it is determined that the line branch has an abnormality. The system marks the line branch meeting the condition as a suspected grounding line for subsequent fault positioning and processing. After comprehensive analysis of the height difference and slope difference of all detected line branches, the abnormal line is screened out and a suspected grounding line list is generated. This method can effectively exclude normal fluctuations of the power grid by combining voltage change amplitude and trend analysis, and improve the accuracy and reliability of single-phase grounding fault positioning.

[0047] It should be noted that the determination range of the height difference and the slope difference takes into account the normal operation fluctuations and measurement errors of the distribution network, ensuring that the system can both identify actual faults and avoid misjudgments. The preferred threshold (height difference 0.5 volts, slope difference 0.2 volts per second) is determined based on actual distribution network operation data statistics and experimental verification, and can balance sensitivity and robustness.

[0048] Preferably, step S4 comprises the following steps: Step S41: identifying the arc suppression coil tap and its corresponding bus branch that need to be adjusted according to the fault point position; Step S42: confirming the adjustment target line of the arc suppression coil based on the bus branch; implementing step-by-step adjustment of the arc suppression coil tap, and sequentially switching to different tap positions; observing the change of the zero sequence voltage of the bus corresponding to the adjustment target line and recording the voltage change data every time the tap position is switched; Step S43: selecting the optimal tap position according to the zero sequence voltage change, and fixing the arc suppression coil at the selected optimal tap position to complete the physical tap adjustment operation; Step S44: re-detecting the zero sequence voltage of the arc suppression coil after the physical tap adjustment operation to verify whether the compensation effect meets the predetermined standard, and recording the verification result.

[0049] In an embodiment, according to the fault point position of the distribution network, the topology of the distribution network and the zero sequence voltage change information of each bus, the bus branches affected by the fault are confirmed. For each affected bus branch, the connected arc suppression coil and the corresponding tap are identified, and a list of taps to be adjusted is generated. The step-by-step adjustment of the taps to be adjusted is implemented, and the zero sequence voltage change of the bus branch corresponding to the tap position is monitored and the voltage change data is recorded in real time every time the tap position is switched.

[0050] To ensure adjustment accuracy, the switching step and observation time interval of each step can be set, for example, 10-30 seconds after each step adjustment to ensure that the zero sequence voltage is stable before recording the data to exclude transient interference.

[0051] According to the recorded zero sequence voltage variation data, the compensation effect of each tapping point position is comprehensively analyzed, and the tapping point position with the minimum zero sequence voltage fluctuation and the best compensation effect is selected as the optimal tapping point. Physical fixing operation is performed at the selected optimal tapping point position to ensure that the arc suppression coil does not deviate during operation, thereby completing the physical turn operation.

[0052] After the turn is completed, the system again detects the zero sequence voltage of the bus branch corresponding to the arc suppression coil, compares the zero sequence voltage change before and after the turn, judges whether the compensation effect reaches the predetermined standard, and records the verification result. If the compensation effect does not reach the predetermined standard, steps S42-S44 can be repeated for fine tuning until the standard is reached.

[0053] Preferably, step S43 includes the following steps: Step S431: respectively adjust the arc suppression coil to each tapping point position, and measure the change value of the corresponding bus zero sequence voltage at each position; record the zero sequence voltage change value of each tapping point position and establish a comparison table; Step S432: when the zero sequence voltage change reaches the preset compensation standard position, mark the tapping point position as the optimal tapping point position and adjust the arc suppression coil to the optimal tapping point position; and fix the arc suppression coil adjusted to the optimal tapping point position.

[0054] In an embodiment, the arc suppression coil to be adjusted is switched to each tapping point position in turn. Each time the tapping point position is switched, the system measures the zero sequence voltage change value of the corresponding bus in real time, and records the measurement data. The measured zero sequence voltage change value of each tapping point position is archived, and a comparison table of tapping point position and zero sequence voltage change value is established for subsequent comparison and analysis. During the measurement process, in order to ensure the accuracy of the data, the sampling time of each measurement can be set to 5-15 seconds to ensure that the zero sequence voltage is recorded after it is stable, avoiding the influence of instantaneous fluctuation on judgment.

[0055] According to the comparison table, the zero sequence voltage change values corresponding to each tapping point position are compared, and when the zero sequence voltage change value of a certain tapping point position reaches the preset compensation standard, the position is marked as the optimal tapping point position. The arc suppression coil is adjusted to the optimal tapping point position, and physical fixing operation is performed to ensure that the arc suppression coil does not deviate or loosen during operation, thereby completing the turn operation. The fixing operation can include tightening the bolts, locking the mechanism or using a safety fixing device to ensure the stability and compensation effect during long-term operation.

[0056] By establishing the comparison table of tapping point position and zero sequence voltage change, the optimal compensation position can be determined systematically and quantitatively, and accurate turn can be realized; the fixing operation ensures the stability of the arc suppression coil, further improving the automatic compensation efficiency and reliability of single-phase ground fault of the distribution network.

[0057] In another embodiment, the arc suppression coil is sequentially adjusted to each tapping point position, and the change value of the corresponding bus zero sequence voltage is measured at each position. For example, assuming that the arc suppression coil has five tapping point positions A, B, C, D, and E, and the corresponding zero sequence voltage change values are 0.8 volts, 1.5 volts, 2.3 volts, 1.9 volts, and 1.2 volts, respectively, then these measurement data are established in a table for analysis and comparison. According to a preset compensation standard, the tapping point position with the zero sequence voltage change value closest to the ideal value is selected as the optimal tapping point position. For example, when the preset compensation standard is 2.0 volts, the zero sequence voltage change value at position D is 1.9 volts, with a difference of 0.1 volts from the ideal value, which is smaller than the difference at other positions. Therefore, position D is selected as the optimal tapping point position. Subsequently, the arc suppression coil is adjusted to this optimal position, and a fixing operation is performed on the arc suppression coil through a tightening bolt or a locking device to ensure that it does not deviate during long-term operation. At the same time, position C is recorded as the optimal tapping point position for subsequent maintenance and monitoring of the system. This method quantifies the zero sequence voltage change value to determine the compensation effect, avoids relying on experience, and ensures long-term stable operation of the arc suppression coil after adjustment by the fixing operation, thereby achieving effective compensation for single-phase ground faults.

[0058] Preferably, the fixing operation on the arc suppression coil adjusted to the optimal tapping point position includes: Mechanically locking the tapping piece of the arc suppression coil at the selected position, locking the tapping adjustment mechanism, and setting a limiting structure at the optimal tapping point position, while confirming the electrical contact state of the connection to complete position marking.

[0059] In an embodiment, the fixing operation on the arc suppression coil adjusted to the optimal tapping point position includes: first, after moving the tapping piece of the arc suppression coil to the selected optimal tapping point position, the tapping piece is fixed by a mechanical locking device to ensure that it does not slide or deviate during long-term operation; at the same time, a locking action is applied to the tapping adjustment mechanism to prevent accidental movement of the adjustment mechanism under the action of external force or vibration; a limiting structure is set at the optimal tapping point position to limit the maximum movement range of the tapping piece and ensure position accuracy; finally, the electrical contact state of the connection is detected, and after confirming reliable contact, position marking is performed on the arc suppression coil and the bus to facilitate identification and inspection by subsequent maintenance personnel.

[0060] In actual operation, the mechanical locking bolt can be selected as a bolt with a diameter of 6-10 mm, and the torque is controlled in the range of 15-25 N / m, to ensure that the tap is fixed firmly without damaging the structure; the allowable deviation of the limiting structure can be controlled within ±1 mm to ensure that the electrical characteristics of the arc suppression coil are not affected; the electrical contact resistance should be less than 50 mΩ to ensure stable current transmission. The reason for setting these numerical ranges is to balance mechanical stability and electrical performance, prevent the tap from shifting under vibration or thermal expansion, and at the same time ensure that the grounding compensation effect meets the expected standard.

[0061] By adjusting the gear by gear and combining with the zero sequence voltage feedback method, the optimal compensation position of the arc suppression coil can be accurately positioned, the single-phase ground fault can be efficiently compensated, the human adjustment error can be reduced, and the safety and reliability of the distribution network can be improved.

[0062] Preferably, step S4 further comprises: Injecting a power frequency pulse signal into the system on the bus side of the substation based on the fault point position; Measuring the pulse response along the line at the branch terminal of each suspected grounding line using a grounding detector to obtain a pulse response signal; Correcting the fault point position based on the degree of change in the amplitude and direction of the pulse response signal.

[0063] In an embodiment, first, a power frequency pulse signal is injected into the system on the bus side of the substation based on the fault point position, and the pulse signal is propagated along the bus and its branches by controlling the amplitude and duration of the injected voltage; then, the response of the pulse signal is measured along the branch terminal of each suspected grounding line using a grounding detector, and the pulse response signal data is collected, including signal amplitude, phase, and propagation time information; based on the collected pulse response signal, the change direction and degree of signal amplitude are analyzed, for example, whether the signal amplitude from the branch starting point to the terminal appears obvious attenuation or direction reversal, and the original fault point position is corrected to further accurately position the suspected fault point; this method determines the fault point position by the propagation characteristics of the pulse signal, effectively improves the accuracy of fault location, and provides a reliable reference for subsequent arc suppression coil tap adjustment.

[0064] In actual implementation, the power frequency pulse signal can be injected to the fault point at the bus side of the substation, the pulse amplitude is set to 20-50 volts, and the pulse duration is controlled in the range of 5-10 milliseconds to ensure that the signal can propagate along the suspected grounding line without damaging the equipment; the ground detection instrument is arranged along the line at the branch terminal of each suspected grounding line, and the sampling frequency is set to 1-2 kHz to accurately capture the amplitude change and direction change of the pulse response; based on the collected pulse response signal, if the amplitude change exceeds 10% or the direction deviation exceeds 10 degrees, the preliminary determined fault point position is corrected, thereby improving the accuracy of the grounding point positioning and ensuring the reliability and safety of the subsequent arc suppression coil adjustment operation.

[0065] Especially important is that the position correction of the fault point position based on the amplitude and direction change degree of the pulse response signal also includes: calculating the amplitude change rate of the pulse response signal; calculating the amplitude and direction change degree of the adjacent sampling points based on the amplitude change rate, and generating amplitude and direction change degree data; using the amplitude and direction change degree data to estimate the deviation amount of the fault point position, and generating fault point position deviation data; correcting the fault point position according to the fault point position deviation data, and generating corrected fault point position data.

[0066] In an embodiment, the pulse response signal amplitudes collected at each measurement point along the suspected grounding line are obtained, and the amplitude change rate of the pulse response signal is obtained by dividing the amplitude difference of adjacent sampling points by the time interval. The change rate reflects the speed of amplitude increase or attenuation in the signal propagation process, and is used to characterize the propagation characteristics of the signal at different positions. The signs of the amplitude change rates of adjacent sampling points are judged, and when the amplitude direction of adjacent sampling points changes from "increasing" to "decreasing" or from "decreasing" to "increasing", it is recorded as one direction change. Further, the cumulative number of direction changes of consecutive sampling points is counted to form amplitude and direction change degree data, which is used to determine the fluctuation region of signal propagation.

[0067] Since the number of direction changes near the grounding point increases significantly, the system determines the section with the most dense direction change degree by comparing the distribution of the direction change degree at different measurement points, calculates the distance between the section and the preliminary fault point as the deviation amount, and obtains the fault point position deviation data. The fault point position deviation data and the preliminary fault point position are superimposed or corrected to obtain the final corrected fault point position data, which is used as the actual reference position for subsequent arc suppression coil adjustment.

[0068] By introducing the degree of amplitude direction change of the impulse response signal, the position is corrected, the error influence of line length, impedance distribution and environmental noise factors on fault point positioning can be effectively eliminated, and the precision of fault positioning is improved, and reliable basis is provided for subsequent compensation operation.

[0069] Especially important, the acquisition of adjacent sampling points also includes: The impulse response signal is processed in time sequence, and the impulse response data in time sequence is generated; Based on the impulse response data in time sequence, the sampling point identification processing is performed, and the sequential number is added to each sampling point, and the sampling point number data is generated; The adjacent numbered sampling points are paired using the sampling point number data, and the adjacent sampling point pairing data is generated; According to the adjacent sampling point pairing data, the amplitude information of the adjacent sampling points is extracted, and the adjacent sampling points are obtained.

[0070] In an embodiment, the impulse response signals collected at each measurement point along the suspected grounding line are sorted according to the collection time to form a time-sequenced impulse response data sequence, which is used for subsequent pairing analysis of adjacent sampling points.

[0071] In some embodiments, the system can assign a unique sequential number to each sampling point in the order of sampling time, such as "sampling point 1, sampling point 2, sampling point 3", etc., to ensure the accuracy of subsequent adjacent relationship determination. Based on the sampling point number, "sampling point i" and "sampling point i+1" are paired in the order of adjacent numbering to generate adjacent sampling point pairing data, such as (sampling point 1, sampling point 2), (sampling point 2, sampling point 3), etc.

[0072] The amplitude information of the two sampling points in the pairing data is extracted respectively and used as the adjacent sampling points for subsequent calculation of amplitude change rate and amplitude direction change degree. This step ensures that the input data for amplitude change rate calculation has strict time sequence correlation, thereby improving the accuracy of fault point position correction.

[0073] As Figure 3 shown is a functional module diagram of the arc suppression coil single-phase grounding distribution network fault diagnosis system provided by an embodiment of the present application.

[0074] The arc suppression coil single-phase grounding power distribution network fault diagnosis system 100 can be installed in an electronic device. According to the functions implemented, the arc suppression coil single-phase grounding power distribution network fault diagnosis system 100 can include a fault discrimination module 101, a line isolation module 102, a fault point detection module 103, and a position compensation module 104. The modules in the present application can also be referred to as units, which refer to a series of computer program segments that can be executed by an electronic device processor and can complete a fixed function, which are stored in the memory of the electronic device.

[0075] The fault discrimination module 101 is configured to obtain bus zero sequence voltage and arc suppression coil bias current of the power distribution network; and confirm whether a single-phase grounding fault occurs in the power distribution network based on a comparison result of the bus zero sequence voltage and the arc suppression coil bias current with a preset voltage and current threshold. The line isolation module 102 is configured to, in response to the single-phase grounding fault occurring in the power distribution network, confirm bus zero sequence voltage variation of the power distribution network and verify line segmentation isolation of the power distribution network according to the bus zero sequence voltage variation, to obtain a suspected grounding line. The fault point detection module 103 is configured to confirm a line grounding point based on zero sequence voltage variation of the suspected grounding line; and confirm a fault point position of the power distribution network according to zero sequence current variation of the line grounding point. The position compensation module 104 is configured to confirm an optimal compensation position of an arc suppression coil tap based on the fault point position and adjust the arc suppression coil tap, and verify the adjusted arc suppression coil.

[0076] In detail, the modules in the arc suppression coil single-phase grounding power distribution network fault diagnosis system 100 in the embodiments of the present application adopt the same technical means as the arc suppression coil single-phase grounding power distribution network fault diagnosis method in the above-mentioned Figure 1 and can produce the same technical effects, which will not be described here.

[0077] Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting, and the scope of the present application is defined by the appended claims rather than the above description, and therefore all changes falling within the meaning and scope of the equivalent elements of the application file are intended to be included in the present application.

[0078] The above description is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for diagnosing arc suppression coil single-phase grounding distribution network faults, characterized in that: The following steps are involved: Step S1: Obtain the busbar zero-sequence voltage and arc suppression coil bias current of the distribution network; based on the comparison results of the busbar zero-sequence voltage and arc suppression coil bias current with preset voltage and current thresholds, determine whether a single-phase grounding fault occurs in the distribution network; Step S2: in response to a single-phase grounding fault occurring in the distribution network, confirming a busbar zero-sequence voltage change of the distribution network and performing line segmentation isolation verification on the distribution network according to the busbar zero-sequence voltage change to obtain a suspected grounding line; Step S3: confirming the line grounding point based on the zero-sequence voltage change of the suspected grounded line; Confirm the fault location of the distribution network based on the change of zero-sequence current at the line grounding point; Step S4: confirm the optimal compensation position of the arc suppression coil tap based on the fault point location and adjust it, and verify the turns of the adjusted arc suppression coil.

2. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 1 is characterized in that: Step S2 includes the following steps: Step S21: In response to a single-phase grounding fault occurring in the distribution network, zero-sequence voltage change information of each busbar of the distribution network and the topology of the distribution network are collected; Step S22: according to the variation amplitudes of the zero-sequence voltage variation information of different buses, the bus with the maximum variation amplitude is taken as the fault-affected central bus; Step S23: starting from the fault-affected central busbar, traverse the line branches connected to the fault-affected central busbar in turn through the distribution network topology structure; Step S24: perform segmented isolation verification on each line branch to obtain a suspected grounding line.

3. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 2 is characterized in that: Step S24 includes the following steps: Step S241: Divide each line branch into sections to obtain trunk area line branches and branch area line branches; Step S242: confirming the detection order based on the trunk area line branches and the branch area line branches, and opening the isolating switch corresponding to each line branch in turn according to the detection order; Step S243: In response to the disconnecting switch being opened, detecting a change in the busbar zero-sequence voltage of the corresponding line branch; Step S244: each line branch is isolated and verified in sections by comparing the busbar zero-sequence voltage change of the corresponding line branch, thereby screening out suspected grounded lines.

4. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 3 is characterized in that: Verification of segmented isolation of each line branch based on the busbar zero-sequence voltage change of the corresponding line branch includes: Draw a time sequence voltage curve diagram according to the change of the busbar zero sequence voltage of the corresponding line branch; Extract the highest peak curve of the timing voltage curve graph, and confirm the corresponding pull-off time point of the highest peak curve; Based on the time point of the pull-off, select the time windows before and after the highest peak curve, and confirm the sampling points in the time windows before and after. The baseline curve and the verification curve are obtained by curve fitting the sampling points in the front and back time series windows; By comparing the height and slope of the reference curve and the verification curve, the change in the busbar zero-sequence voltage of the corresponding line branch can be determined, and each line branch is isolated and verified in sections to screen out suspected grounding lines.

5. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 4 is characterized in that: By comparing the height and slope of the reference curve and the verification curve, the busbar zero-sequence voltage change of the corresponding line branch is determined, and each line branch is isolated and verified in sections, including: The height difference determination range is set to 0.05 to 2.0 volts based on the height and slope of the reference curve and the verification curve, and the slope difference determination range is set to 0.01 to 0.5 volts / second; When the height difference of any line branch exceeds 0.5 volts or the slope difference exceeds 0.2 volts / second, the line branch is determined to be abnormal and marked as a suspected ground line.

6. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 1 is characterized in that: Step S4 includes the following steps: Step S41: Identify the arc suppression coil tap and its corresponding busbar branch that need to be adjusted according to the fault point location; Step S42: confirming the target line for adjusting the arc suppression coil based on the busbar branch; adjusting the arc suppression coil tap position by position, switching to different tap positions in sequence; each time the tap position is switched, observing the change in the busbar zero-sequence voltage corresponding to the target line for adjustment, and recording the voltage change data; Step S43: selecting the optimal tapping point position according to the change of the zero-sequence voltage, and fixing the arc suppression coil at the selected optimal tapping point position to complete the physical turn adjustment operation; Step S44: performing zero-sequence voltage detection on the arc suppression coil after the physical turn adjustment operation again to verify whether the compensation effect meets the predetermined standard, and recording the verification result.

7. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 6 is characterized in that: Step S43 includes the following steps: Step S431: Adjust the arc suppression coil to each tapping point position, and measure the change value of the corresponding bus zero-sequence voltage at each position; record the change value of the zero-sequence voltage at each tapping point position and create a comparison table; Step S432: When the zero-sequence voltage variation reaches a preset compensation standard position, the tap position is marked as the optimal tap position and the arc suppression coil is adjusted to the optimal tap position; the arc suppression coil adjusted to the optimal tap position is fixed.

8. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 6 is characterized in that: The operation of fixing the arc suppression coil adjusted to the optimal tapping point position includes: The tapping piece of the arc suppression coil is mechanically locked at the selected position, the tap adjustment mechanism is locked, and a limit structure is set at the optimal tapping point position. At the same time, the electrical contact status of the connection is confirmed and the position marking is completed.

9. The arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 1, characterized in that: Before step S4, the following steps are also included: Inject power frequency pulse signal into the substation busbar lateral system based on the fault point location; Use a grounding detector to measure the impulse response along the line at the branch terminal of each suspected grounding line to obtain the impulse response signal; The position of the fault point is corrected based on the degree of change in the amplitude direction of the impulse response signal.

10. A fault diagnosis system for arc suppression coil single-phase grounding distribution network, characterized in that: Used to execute the arc suppression coil single-phase grounding distribution network fault diagnosis method according to claim 1, the arc suppression coil single-phase grounding distribution network fault diagnosis system comprises: A fault identification module is used to obtain the busbar zero-sequence voltage and arc suppression coil bias current of the distribution network; based on the comparison results of the busbar zero-sequence voltage and arc suppression coil bias current with preset voltage and current thresholds, it is determined whether a single-phase grounding fault has occurred in the distribution network; A line isolation module is used to confirm the change of the busbar zero-sequence voltage of the distribution network and perform line segmentation isolation verification on the distribution network according to the change of the busbar zero-sequence voltage in response to a single-phase grounding fault in the distribution network, so as to obtain a suspected grounding line; The fault point detection module is used to confirm the line grounding point based on the zero-sequence voltage change of the suspected grounded line; and to confirm the fault point location of the distribution network based on the zero-sequence current change of the line grounding point; The position compensation module is used to confirm the optimal compensation position of the arc suppression coil tap based on the fault point location and adjust it, and verify the turn adjustment of the adjusted arc suppression coil.

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