A method and system for diagnosing single-phase grounding fault of arc suppression coil distribution network

Abstract

The present application relates to the technical field of power grid fault diagnosis, and particularly relates to a method and system for diagnosing single-phase grounding fault of arc suppression coil distribution network. The method comprises the following steps: collecting bus zero sequence voltage and arc suppression coil bias current, and combining threshold value to determine whether single-phase grounding fault occurs; after the fault occurs, suspected grounding line is verified and positioned by segmenting and isolating according to the change amplitude of each bus zero sequence voltage, and the grounding point and fault point position are further accurately determined by zero sequence voltage and zero sequence current change; finally, the arc suppression coil tap is adjusted according to the fault point position, the best compensation position is selected and verified by adjusting the number of turns, so that the single-phase grounding fault is quickly diagnosed and compensated. Through multi-stage zero sequence voltage / current analysis, topological segmenting and isolating verification, time sequence curve comparison judgment and tap intelligent adjustment and compensation, the present application realizes accurate positioning and efficient arc suppression compensation of single-phase grounding fault, and improves the diagnosis accuracy and the operation reliability of distribution network.

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 for arc suppression coil single-phase grounding distribution networks has evolved from traditional manual detection to automated 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, real-time monitoring of bus zero-sequence voltage and arc suppression coil bias current was realized to quickly identify single-phase grounding faults, and suspected grounding lines could be screened according to bus zero-sequence voltage changes and distribution network topology for line segment isolation. Further development introduced methods such as zero-sequence voltage time sequence curve analysis, comparison of reference curve and verification curve, and height and slope determination, which made fault positioning more accurate.

[0003] However, the traditional zero-sequence voltage monitoring and segment isolation method is difficult to accurately locate the fault point under complex topologies with multiple branches and multiple buses, and is prone to misjudgment or delayed positioning. At the same time, the selection of arc suppression coil tap point position is mostly dependent on experience or single measurement, lacking systematic optimization adjustment means, and it is 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 purpose, a method and system for diagnosing faults of an arc suppression coil single-phase grounding distribution network, the method comprising the following steps:

[0006] 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 comparison results of the bus zero-sequence voltage and the arc suppression coil bias current with preset voltage and current thresholds;

[0007] Step S2: in response to the occurrence of a single-phase grounding fault in the distribution network, confirming changes in bus zero-sequence voltage of the distribution network and verifying line segment isolation of the distribution network according to the changes in bus zero-sequence voltage to obtain a suspected grounding line;

[0008] Step S3: confirming a line grounding point based on zero-sequence voltage changes of the suspected grounding line; and confirming a fault point position of the distribution network according to zero-sequence current changes of the line grounding point;

[0009] Step S4: Confirm the optimal compensation position of the arc suppression coil tap based on the fault point position and adjust it, and verify the turns of the adjusted arc suppression coil.

[0010] In the present specification, a kind of arc suppression coil single-phase grounding distribution network fault diagnosis system is provided for carrying out the arc suppression coil single-phase grounding distribution network fault diagnosis method described above, the arc suppression coil single-phase grounding distribution network fault diagnosis system includes:

[0011] Fault discrimination module, for obtaining the bus zero sequence voltage and arc suppression coil bias current of distribution network;Distribution network whether single-phase grounding fault occurs is confirmed based on the comparison result of bus zero sequence voltage and arc suppression coil bias current and pre-set voltage current threshold;

[0012] Line isolation module, for confirming the bus zero sequence voltage variation of distribution network and according to bus zero sequence voltage variation, line section isolation verification is carried out to distribution network, to obtain suspected grounding line in response to distribution network single-phase grounding fault;

[0013] Fault point detection module, for confirming the line grounding point based on the zero sequence voltage variation of suspected grounding line;According to the zero sequence current variation of line grounding point, the fault point position of distribution network is confirmed;

[0014] Position compensation module, for confirming the optimal compensation position of the arc suppression coil tap based on the fault point position and adjusting it, and verifying the turns of the adjusted arc suppression coil.

[0015] The beneficial effects of the present application are:

[0016] I. By combining bus zero sequence voltage, arc suppression coil bias current and distribution network topology, the single-phase grounding fault is quickly identified and positioned, which can significantly improve the accuracy and real-time performance of distribution network fault diagnosis. Especially after the fault occurs, the variation amplitude of each bus zero sequence voltage is compared, the fault-affected central bus is quickly determined, and the topology information is used for section isolation verification, so that the screening process of suspected grounding line is more efficient and reliable, and the delay and misjudgment caused by relying on manual analysis in traditional way are avoided.

[0017] II. By means of curve fitting based on time sequence voltage curve, reference curve and verification curve are constructed, and height difference and slope difference are used to judge the grounding state of each line branch, which can effectively suppress noise interference and improve the sensitivity to bus zero sequence voltage variation, so as to accurately identify the fault line and its grounding point. This comparison and analysis mechanism not only realizes the quantitative determination of section isolation verification, but also has the advantages of clear parameter range and clear judgment standard, which is conducive to realizing automatic intelligent diagnosis.

[0018] III. Through the step-by-step regulation of the tap based on the change of the zero sequence voltage and the contrast recording mode, 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 operation of mechanical locking, limiting protection and electrical contact confirmation, the running stability and electrical reliability of the compensated arc suppression coil are ensured. At the same time, after the optimal tap position is confirmed, the compensation effect is further verified through zero sequence voltage detection, which can ensure that the compensation effect meets the standard and improve the steady state level of the power distribution network after fault recovery.

[0019] IV. Before the formal turn adjustment, the power frequency pulse signal injection and pulse response measurement mechanism are introduced, the change degree of the response signal amplitude and direction is compared, the fault point position is further corrected, and the accuracy of the fault location result is improved. Overall, the scheme realizes the accurate diagnosis and efficient compensation of the single-phase grounding fault through the whole-process closed-loop design of "fault determination - sectional isolation - grounding point confirmation - compensation adjustment - correction verification", and has the advantages of high intelligent degree, strong reliability and excellent implementation effect. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a step flowchart of a single-phase grounding power distribution network fault diagnosis method and system of an arc suppression coil.

[0021] Figure 2 It is Figure 1 It is a detailed implementation step flowchart of step S2.

[0022] Figure 3 It is a functional module diagram of the single-phase grounding power distribution network fault diagnosis system of the arc suppression coil provided by an embodiment of the application.

[0023] The implementation of the object, functional characteristics and advantages of the application will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION

[0024] The technical method of the application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the application, not all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor belong to the protection scope of the application.

[0025] Further, the accompanying drawings are included to provide a further understanding of the present application, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the present application and, together with the description, serve to explain the principles of the present application. In the drawings:

[0026] It is to be understood that, although terms such as "first", "second", and so on 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, without departing from the scope of the exemplary embodiments, a first element can be referred to as a second element, and similarly a second element can be referred to as a first element. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] To achieve the above object, there is provided 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:

[0028] Step S1: acquiring bus zero sequence voltage and arc suppression coil bias current of the power distribution network; 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;

[0029] 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).

[0030] 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 single-phase grounding fault occurs in the power distribution network; 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.

[0031] For example, in a preferred embodiment, the voltage threshold can be set to 80-120 volts, and the current threshold can be set to 2-5 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 occurred 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.

[0032] Step S2: In response to the occurrence of a single-phase grounding fault in the power distribution network, the bus zero-sequence voltage change of the power distribution network is confirmed, and line segment isolation verification is performed on the power distribution network according to the bus zero-sequence voltage change, to obtain a suspected grounding line;

[0033] In an embodiment, after the power distribution network is determined to have occurred a single-phase grounding fault in step S1, the fault judgment module continuously monitors the change trend of the bus zero-sequence voltage, to confirm whether the voltage change has a significant rising or falling characteristic. The bus zero-sequence voltage can be sampled and recorded at a fixed time interval (for example, 0.2 seconds).

[0034] 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 units of feeder lines. 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 moment with the zero-sequence voltage before the fault occurs.

[0035] For example, when the first line branch is disconnected, if the decrease in the bus zero-sequence voltage is less than a preset decrease threshold (for example, less than 3%), it can be determined that the line branch is not a grounding line; when the second line branch is disconnected, if the decrease in the bus zero-sequence voltage is detected to exceed the preset decrease threshold (for example, more than 3%), it can be determined that the line branch is a suspected grounding line.

[0036] In a preferred embodiment, the segmentation and isolation sequence can be performed in a manner that the main line is prioritized and the branch line is sequentially processed, so as to avoid mistakenly cutting an important power supply line. When the segmentation and isolation process continuously monitors that the bus zero-sequence voltage rapidly decreases to a normal range after a line is disconnected, the system determines that the line is a suspected grounding line, and takes it as an analysis object in the subsequent fault location process.

[0037] 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 power distribution network according to the zero-sequence current change of the line grounding point;

[0038] In one embodiment, for the suspected grounding line determined in step S2, the system continues to collect the bus zero sequence voltage variation data over time for this line. By comparing the zero sequence voltage variation amplitude and trend before and after the grounding point, the position of the line with the most significant zero sequence voltage variation is identified as the candidate grounding point.

[0039] For example, the zero sequence voltage difference at each node of the suspected grounding line can be calculated, and when the zero sequence voltage difference exceeds a preset threshold (e.g., 5-10%), 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.

[0040] After the grounding point is confirmed, the system collects zero sequence current variation data on the arc suppression coil or line for further fault point positioning. The specific method includes measuring the current value of each segment along the suspected grounding line and determining the position of the current peak. The zero sequence current shows a significant rise near the fault point, exceeding a preset current threshold (e.g., 2-5 A), and the position is determined as the actual fault point.

[0041] In a preferred embodiment, to improve positioning accuracy, a combined analysis of zero sequence voltage and zero sequence current can be used, for example, the node where the voltage variation at the grounding point is significant and the current reaches a peak is determined as the fault point, avoiding misjudgment caused by relying on a single parameter of voltage or current.

[0042] 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 for turns.

[0043] In one embodiment, first, based on the fault point position determined in step S3 and the line parameters (such as conductor length, reactance value, etc.), the theoretical compensation current of each tap of the arc suppression coil is calculated, and the optimal compensation position of the tap is determined through an optimization algorithm (such as minimizing bus zero sequence voltage fluctuation or zero sequence current peak). For example, simulation or real-time measurement methods can be used to simulate the zero sequence voltage and zero sequence current response under different tap positions, 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.

[0044] After the optimal compensation position is confirmed, the system controls the arc suppression coil to perform physical turns adjustment, adjusting the tap to the optimal position. After adjustment, the real-time measurement of bus zero sequence voltage and arc suppression coil current verifies whether the turns adjustment meets the design requirements. If the zero sequence voltage returns to the allowable fluctuation range and the zero sequence current drops below the threshold, the turns adjustment is considered successful; if it does not meet the requirements, fine tuning or re-optimization of the tap position can be performed.

[0045] In a preferred embodiment, to ensure tap adjustment accuracy, a tap adjustment verification threshold can be set, for example, the zero-sequence voltage deviation should not exceed ±2% of the bus rated voltage, and the zero-sequence current should not exceed a set threshold of 2-5 amps. This setting can avoid secondary zero-sequence voltage fluctuations or incomplete compensation caused by improper tap adjustment, ensuring the stable operation of the distribution network.

[0046] As an example of the present invention, reference is made to Figure 2 As shown, step S2 in this example includes:

[0047] Step S21: In response to a single-phase ground fault in the distribution network, collect information on the zero-sequence voltage change of each bus in the distribution network and the distribution network topology;

[0048] Step S22: Based on the change amplitude of the zero-sequence voltage change information of different buses, the bus with the largest change amplitude is taken as the fault-affected center bus;

[0049] Step S23: Starting from the fault-affected center bus, traverse each line branch connected to the fault-affected center bus in sequence through the distribution network topology;

[0050] Step S24: Perform line segment isolation verification on each line branch to obtain suspected grounding lines.

[0051] In one embodiment, zero-sequence voltage data of each bus is collected in real time by voltage sensors on each bus, and distribution network topology information, including the connection relationship between buses, branch length and branching status, is obtained at the same time to construct a distribution network topology model and provide basic data for fault location.

[0052] The amplitude changes of the zero-sequence voltage of each bus before and after the fault occur are calculated to obtain a sequence of zero-sequence voltage change amplitudes. The system marks the bus with the largest change amplitude as the fault-affected center bus. It is preferable to set a threshold for the zero-sequence voltage change amplitude, for example, exceeding the rated voltage of the bus by 2-5%, to screen suspected fault-affected centers and avoid misjudgment due to small fluctuations.

[0053] By using breadth-first or depth-first traversal algorithms, the adjacent line branches affecting the central busbar are scanned sequentially, and the start and end nodes, length, connecting busbars and branch information of each branch are recorded, providing a basis for subsequent line segment isolation verification.

[0054] The line branch is divided into sections, and the zero-sequence voltage and zero-sequence current are measured in each section. The fluctuations in zero-sequence voltage and the peak current of each section are compared to screen out abnormal sections as suspected grounding lines. It is preferable to set the voltage change threshold to 3-7% of the rated bus voltage and the current threshold to 2-5 amps to balance the positioning accuracy and false alarm rate.

[0055] In a preferred embodiment, to improve the positioning reliability, the bus zero sequence voltage and branch zero sequence current are combined for analysis. When the zero sequence voltage of a certain line branch changes significantly and the zero sequence current peak value is obvious, it is determined that the branch is a suspected grounding line. This method can effectively reduce the misjudgment caused by relying on a single parameter and improve the fault positioning accuracy.

[0056] Preferably, step S24 comprises the following steps:

[0057] Step S241: dividing each line branch into sections to obtain main trunk area line branches and branch area line branches;

[0058] Step S242: confirming a detection sequence according to the main trunk area line branches and the branch area line branches, and sequentially opening the corresponding disconnectors of each line branch according to the detection sequence;

[0059] Step S243: in response to the opening of the disconnectors, detecting the bus zero sequence voltage change of the corresponding line branch;

[0060] Step S244: segmenting and isolating each line branch according to the bus zero sequence voltage change of the corresponding line branch to verify, thereby screening out the suspected grounding line.

[0061] In an embodiment, the line branches are divided into sections according to the distribution network topology and the line length. The main trunk area line branch refers to the main line section directly connected to the fault-affected center bus, and the branch area line branch refers to the side branch line section branched from the main trunk area. This division helps to optimize the fault positioning sequence and reduce the operation error. The main trunk area line branch is detected first, and then the branch area line branch is detected in sequence to ensure that the fault influence along the power grid propagation path can be accurately captured. The isolation operation can be completed by remotely controlling or locally operating the disconnectors, and the isolation state of each line branch is recorded for comparison and analysis of the zero sequence voltage change.

[0062] After isolating each line branch, 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 of a certain line branch returns to the normal range or the change amplitude significantly decreases after isolation, it means that the fault may be located in this section. The isolation verification results are comprehensively analyzed: if the zero sequence voltage of the line section still changes significantly after isolation, the section is retained as a suspected grounding line; if the change amplitude decreases or returns to normal, the section is excluded. Preferably, the zero sequence voltage change threshold is set to 3-7% of the bus rated voltage, which ensures that the fault can be quickly located and misjudgment can be avoided.

[0063] In a preferred embodiment, to improve the verification accuracy, the screening result can be reviewed in combination with the zero sequence current change before and after isolation. When the zero sequence voltage and the zero sequence current change both conform to 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 location.

[0064] Preferably, the segment isolation verification of each line branch based on the bus zero sequence voltage change of the corresponding line branch includes:

[0065] drawing a time sequence voltage curve based on the bus zero sequence voltage change of the corresponding line branch;

[0066] extracting the highest peak curve of the time sequence voltage curve and confirming the corresponding pull-off time point;

[0067] selecting time sequence windows before and after the pull-off time point based on the pull-off time point, and confirming the sampling points in the front and rear time sequence windows;

[0068] obtaining a reference curve and a verification curve through curve fitting based on the sampling points in the front and rear time sequence windows;

[0069] 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, thereby screening a suspected grounding line.

[0070] In an embodiment, the zero sequence voltage before and after the isolation operation of each line branch is continuously sampled, and a curve of voltage change over time 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 time point corresponding to the highest voltage peak is recorded as the trigger time of line isolation. This time point is used for subsequent time window setting to ensure that the analysis is concentrated in the key change section. The preferred time sequence window is set to 0.5-2 seconds before and after the highest peak, which can be adjusted according to the line length and power grid dynamic characteristics. The continuous sampling points are collected in the window to provide data support for curve fitting.

[0071] The sampling points in the front window are fitted to obtain a reference curve representing a normal operation reference state, and the sampling points in the back window are fitted to obtain a verification curve reflecting a dynamic change state after line isolation. The fitting method can be polynomial fitting or least square method to ensure that the curve is smooth and the trend characteristics can be accurately extracted. If the peak height of the verification curve is obviously higher than that of the reference curve, and the curve slope change is greater than a set threshold (such as the slope change is more than 0.5-1.0 V / s), it is determined that the line branch exists 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.

[0072] 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 to ensure that the screening results are stable and reliable.

[0073] Preferably, by comparing the height and slope of the reference curve and the verification curve, the change of the bus zero sequence voltage of the corresponding line branch is judged, and the segmented isolation verification of each line branch includes:

[0074] The determination range of the height difference based on the height and slope of the reference curve and the verification curve is set to 0.05-2.0 volts, and the determination range of the slope difference is 0.01-0.5 volts / s;

[0075] When the height difference of any line branch exceeds 0.5 volts or the slope difference exceeds 0.2 volts / s, it is determined that the line branch exists an abnormality, and the line branch is marked as a suspected grounding line.

[0076] In an embodiment, the peak height and the corresponding slope of the reference curve and the verification curve of each line branch are first calculated. The determination range of the height difference is preferably set to 0.05-2.0 volts to cover the normal fluctuations and slight interference of the power grid; the determination range of the slope difference is preferably set to 0.01-0.5 volts / s to identify the abnormality of the voltage change trend.

[0077] For each line branch, if the peak height of the verification curve exceeds 0.5 volts compared with the reference curve, or the curve slope difference exceeds 0.2 volts / s, it is determined that the line branch exists 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 the 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 the normal fluctuation interference of the power grid by combining the voltage change amplitude and trend analysis, and improve the accuracy and reliability of single-phase grounding fault positioning.

[0078] It should be noted that the determination range of the height difference and the slope difference is set considering the conventional operation fluctuation and measurement error of the power distribution network, so as to ensure that the system can identify the actual fault and avoid misjudgment. The preferred threshold (height difference 0.5 volts, slope difference 0.2 volts / second) is determined on the basis of actual power distribution network operation data statistics and experimental verification, and can balance sensitivity and robustness.

[0079] Preferably, the step S4 comprises the following steps:

[0080] Step S41: identifying the arc suppression coil tap and the corresponding bus branch to be adjusted according to the fault point position;

[0081] 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 point 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 point position is switched;

[0082] Step S43: selecting the optimal tap point position according to the zero sequence voltage change, and fixing the arc suppression coil at the selected optimal tap point position to complete the physical turn operation;

[0083] Step S44: detecting the zero sequence voltage of the arc suppression coil after the physical turn operation again to verify whether the compensation effect reaches the predetermined standard, and recording the verification result.

[0084] In an embodiment, according to the fault point position of the power distribution network, the topology structure of the power 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 arc suppression coil connected thereto and the corresponding tap are identified, and a list of taps to be adjusted is generated. The taps to be adjusted are implemented step-by-step adjustment, and the zero sequence voltage change of the bus branch corresponding to the tap point is monitored and the voltage change data is recorded in real time every time the tap point position is switched.

[0085] In order to ensure the adjustment accuracy, the switching step of each step and the observation time interval can be set, for example, the observation time is 10-30 seconds after each step adjustment, so as to ensure that the data is recorded after the zero sequence voltage is stable, so as to exclude the influence of transient interference.

[0086] According to the recorded zero sequence voltage change data, the compensation effect of each tap point position is comprehensively analyzed, and the tap point position with the smallest zero sequence voltage fluctuation and the best compensation effect is selected as the optimal tap point. Physical fixing operation is performed at the selected optimal tap point position, so as to ensure that the arc suppression coil does not deviate during operation, thereby completing the physical turn operation.

[0087] After the turns are adjusted, the system again detects the zero sequence voltage of the bus branch corresponding to the arc suppression coil, compares the zero sequence voltage before and after the turns are adjusted, determines whether the compensation effect reaches the predetermined standard, and records the verification result. If the compensation effect does not reach the predetermined standard, the steps S42-S44 can be repeated for fine adjustment until the standard is reached.

[0088] Preferably, the step S43 comprises the following steps:

[0089] Step S431: Adjust the arc suppression coil to each tapping point position respectively, and measure the change value of the zero sequence voltage of the corresponding bus at each position; record the change value of the zero sequence voltage at each tapping point position and establish a comparison table;

[0090] Step S432: When the zero sequence voltage change reaches the preset compensation standard position, the tapping point position is marked as the optimal tapping point position, and the arc suppression coil is adjusted to the optimal tapping point position; the arc suppression coil adjusted to the optimal tapping point position is fixed.

[0091] 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 change value of the zero sequence voltage of the corresponding bus in real time, and records the measurement data. The measured change value of the zero sequence voltage at each tapping point position is archived, and a comparison table of the tapping point position and the change value of the zero sequence voltage is established for subsequent comparison and analysis. During the measurement process, in order to ensure the accuracy of the data, the sampling time for each measurement can be set to 5-15 seconds to ensure that the zero sequence voltage is stable before recording, so as to avoid the influence of instantaneous fluctuations on the judgment.

[0092] According to the comparison table, the change value of the zero sequence voltage corresponding to each tapping point position is compared, and when the change value of the zero sequence voltage at 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 a physical fixing operation is performed to ensure that the arc suppression coil does not shift or loosen during operation, thereby completing the turn adjustment 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.

[0093] By establishing the comparison table of the tapping point position and the change of the zero sequence voltage, the optimal compensation position can be determined systematically and quantitatively, and accurate turn adjustment can be realized. The fixing operation ensures the stability of the arc suppression coil, and further improves the automatic compensation efficiency and reliability of the single-phase ground fault of the distribution network.

[0094] In another embodiment, the arc suppression coil is sequentially adjusted to each tapping point position, and the corresponding bus zero sequence voltage change value is measured at each position. For example, assuming that the arc suppression coil has five tapping point positions A, B, C, D, and E, 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, which has a difference of 0.1 volts from the ideal value, smaller than the differences at other positions. Therefore, position D is selected as the optimal tapping point position. Subsequently, the arc suppression coil is adjusted to the 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 in long-term operation. At the same time, position C is recorded as the optimal tapping point position for subsequent maintenance and monitoring system use. This method quantifies the zero sequence voltage change value to judge the compensation effect, avoids relying on experience, and ensures the long-term stable operation of the arc suppression coil after tap adjustment through the fixing operation, thereby realizing effective compensation for single-phase ground faults.

[0095] Preferably, the fixing operation on the arc suppression coil adjusted to the optimal tapping point position comprises:

[0096] The tapping piece of the arc suppression coil is mechanically locked at the selected position, the tapping adjustment mechanism is locked, a limiting structure is arranged at the optimal tapping point position, and the position marking is completed after confirming the electrical contact state of the connection.

[0097] In an embodiment, the fixing operation on the arc suppression coil adjusted to the optimal tapping point position comprises: 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 the tapping piece does not slide or deviate in 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 arranged 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 the position marking is performed on the arc suppression coil and the bus after confirming the reliable contact, so as to be identified and checked by subsequent operation and maintenance personnel.

[0098] 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, to prevent the tap from shifting under vibration or thermal expansion, while ensuring that the grounding compensation effect meets the expected standard.

[0099] 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.

[0100] Preferably, step S4 further comprises:

[0101] Based on the fault point position, a power frequency pulse signal is injected into the system from the bus side of the substation;

[0102] The pulse response is measured along the line at the branch terminal of each suspected grounding line using a grounding detector, and the pulse response signal is obtained;

[0103] The fault point position is corrected based on the degree of change in the amplitude and direction of the pulse response signal.

[0104] In an embodiment, first, based on the fault point position, a power frequency pulse signal is injected into the system from the bus side of the substation, 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.

[0105] In actual implementation, a power frequency pulse signal can be injected at the fault point on the side of the bus 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; a grounding detector 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 position of the initially determined fault point 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.

[0106] 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:

[0107] calculating the amplitude change rate of the pulse response signal;

[0108] calculating the amplitude and direction change degree of adjacent sampling points based on the amplitude change rate to generate amplitude and direction change degree data;

[0109] estimating the deviation amount of the fault point position using the amplitude and direction change degree data to generate fault point position deviation data;

[0110] correcting the fault point position according to the fault point position deviation data to generate corrected fault point position data.

[0111] 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 sequence 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 during signal propagation 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 determined, 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. The cumulative number of direction changes of consecutive sampling points is further counted to form amplitude and direction change degree data, which is used to determine the fluctuation region of signal propagation.

[0112] 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 initially determined fault point as the deviation amount, and obtains the fault point position deviation data. The fault point position deviation data and the initially determined 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.

[0113] 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.

[0114] Especially important is that the acquisition of adjacent sampling points also includes:

[0115] The impulse response signal is processed in time sequence, and the impulse response data in time sequence is generated;

[0116] 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;

[0117] The adjacent numbered sampling points are paired using the sampling point number data, and the adjacent sampling point pairing data is generated;

[0118] 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.

[0119] 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 sequence of impulse response data in time sequence, which is used for subsequent pairing analysis of adjacent sampling points.

[0120] In some embodiments, the system can assign a unique sequential number to each sampling point according to the sampling time sequence, 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, and adjacent sampling point pairing data is generated, such as: (sampling point 1, sampling point 2), (sampling point 2, sampling point 3), etc.

[0121] The amplitude information of the two sampling points in the pairing data is extracted respectively, and is used as the adjacent sampling point 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.

[0122] As Figure 3 shown is a functional module diagram of the arc suppression coil single-phase grounding power distribution network fault diagnosis system provided by an embodiment of the application.

[0123] 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 of 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.

[0124] The fault discrimination module 101 is configured to obtain the bus zero sequence voltage and the 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.

[0125] The line isolation module 102 is configured to, in response to the single-phase grounding fault occurring in the power distribution network, confirm the bus zero sequence voltage change of the power distribution network and perform line segmentation isolation verification on the power distribution network according to the bus zero sequence voltage change, to obtain a suspected grounding line.

[0126] The fault point detection module 103 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.

[0127] The position compensation module 104 is configured to confirm the optimal compensation position of the arc suppression coil tap based on the fault point position and adjust the same, and perform turn verification on the adjusted arc suppression coil.

[0128] 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 Figure 1 , and can produce the same technical effects, which will not be described here.

[0129] 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.

[0130] The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and it is intended to embrace all such modifications and changes that fall within the scope of the application. Accordingly, the application is not to be restricted in scope to the specific embodiments disclosed herein but is to be accorded the full scope that the principles and novel features request appropriately granted.

Claims

1. A method for diagnosing a fault of a single-phase grounding distribution network with an arc suppression coil, characterized in that, The method comprises the following steps: Step S1: acquiring the bus zero sequence voltage and the arc suppression coil bias current of the power distribution network; and determining 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 preset voltage and current thresholds; Step S2: in response to the single-phase grounding fault occurring in the power distribution network, determining the bus zero sequence voltage change of the power distribution network and verifying the line section isolation of the power distribution network according to the bus zero sequence voltage change, to obtain a suspected grounding line; Step S3: determining the line grounding point based on the zero sequence voltage change of the suspected grounding line; determining the fault point position of the power distribution network according to the zero sequence current change of the line grounding point; Step S4: determining the optimal compensation position of the arc suppression coil tap based on the fault point position and adjusting the arc suppression coil, and verifying the turns of the adjusted arc suppression coil, wherein step S4 comprises the following steps: Step S41: identifying the arc suppression coil tap to be adjusted and the corresponding bus branch thereof according to the fault point position; Step S42: determining the adjustment target line of the arc suppression coil based on the bus branch; implementing step-by-step adjustment on the arc suppression coil tap, and sequentially switching to different tap positions; each time the tap position is switched, the change of the bus zero sequence voltage of the adjustment target line is observed, and the voltage change data is recorded; 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 turns adjustment operation; Step S44: detecting the zero sequence voltage of the arc suppression coil after the physical turns adjustment operation again to verify whether the compensation effect reaches the predetermined standard, and recording the verification result; wherein step S43 comprises the following steps: Step S431: respectively adjusting the arc suppression coil to each tap position, and measuring the change value of the corresponding bus zero sequence voltage at each position; recording the zero sequence voltage change values of each tap position and establishing a comparison table; Step S432: when the zero sequence voltage change reaches the 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; and the arc suppression coil adjusted to the optimal tap position is fixed.

2. The method of claim 1, wherein, Step S2 comprises the following steps: Step S21: in response to the single-phase grounding fault occurring in the power distribution network, collecting the zero sequence voltage change information of each bus of the power distribution network and the topology structure of the power distribution network; Step S22: taking the bus with the maximum change amplitude of the zero sequence voltage change information as the fault influence center bus according to the change amplitudes of the zero sequence voltage change information of different buses; Step S23: taking the fault influence center bus as the starting point, and sequentially traversing each line branch connected to the fault influence center bus through the topology structure of the power distribution network; Step S24: verifying the line section isolation of each line branch to obtain a suspected grounding line.

3. The method of claim 2, wherein, Step S24 comprises the following steps: Step S241: dividing each line branch into sections to obtain main area line branches and branch area line branches; Step S242: determining the detection sequence according to the main area line branches and the branch area line branches, and sequentially opening the disconnecting switches corresponding to each line branch according to the detection sequence; Step S243: in response to the disconnector being pulled open, detecting the bus zero sequence voltage change of the corresponding line branch; Step S244: verifying each line branch by the bus zero sequence voltage change of the corresponding line branch, thereby screening the suspected grounding line.

4. The method of claim 3, wherein, Verifying each line branch by the bus zero sequence voltage change of the corresponding line branch includes: Drawing a time sequence voltage curve based on 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 highest peak curve corresponding to the pull-open time point; Selecting a time sequence window before and after the pull-open time point based on the highest peak curve, and confirming the sampling points in the front and rear time sequence windows; Obtaining a reference curve and a verification curve through curve fitting based on 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 verifying each line branch, thereby screening the suspected grounding line.

5. The method of claim 4, wherein, 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 includes: Setting the height difference judgment range to 0.05-2.0 volts and the slope difference judgment range to 0.01-0.5 volts / second based on the height and slope of the reference curve and the verification curve; 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.

6. The method of claim 1, wherein, The fixing operation on the arc-extinguishing coil adjusted to the optimal tap point position includes: Mechanically locking the tap piece of the arc-extinguishing coil at the selected position, locking the tap adjustment mechanism, setting a limit structure at the optimal tap point position, and completing position marking after confirming the electrical contact state of the connection.

7. The method of claim 1, wherein, Before step S4, it further includes: 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 the grounding detector to obtain a pulse response signal; Position correcting the fault point position based on the amplitude direction change degree of the pulse response signal.

8. A system for diagnosing faults in a single-phase grounded distribution network with arc suppression coil, characterized in that, The arc-extinguishing coil single-phase grounding power distribution network fault diagnosis system for executing the arc-extinguishing coil single-phase grounding power distribution network fault diagnosis method includes: A fault discrimination module for obtaining the bus zero sequence voltage and the arc-extinguishing coil bias current of the power distribution network, and confirming whether the power distribution network has a single-phase grounding fault based on the comparison result of the bus zero sequence voltage and the arc-extinguishing coil bias current with a preset voltage and current threshold; A line isolation module for confirming the bus zero sequence voltage change of the power distribution network and verifying the line segmentation isolation of the power distribution network based on the bus zero sequence voltage change to obtain a suspected grounding line in response to the single-phase grounding fault of the power distribution network; A fault point detection module for 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 power distribution network based on 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 based on the fault point position and to adjust the arc suppression coil, and to perform turn verification on the adjusted arc suppression coil.

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