Power distribution network three-core cable guide core-shielding layer arc fault positioning method and device and electronic equipment

Abstract

The invention discloses a power distribution network three-core cable guide core-shielding layer arc fault positioning method and device and electronic equipment. The method comprises the following steps: classifying cables according to a distance relationship between the cables and a system bus; after a fault is detected, direction features of the fault transient feature modulus are extracted, and the positions of nodes at the two ends of the fault cable are determined; a conducting core-shielding layer arc fault point is arranged on a fault cable according to a preset distance, the main component amplitude ratio of the inherent frequency of a fault transient state characteristic modulus of the fault point to the head end of a non-fault cable at the same level is extracted and serves as an input independent variable, and the corresponding fault position serves as an output dependent variable; a three-core cable conducting core-shielding layer arc fault section position sample library is constructed, and a neural network is used to fit the relationship between the fault position and the amplitude ratio. And after the system detects the nodes at the two ends of the fault cable, inputting the principal component amplitude ratio of the inherent frequency of the fault transient characteristic modulus to the corresponding fitting neural network to obtain a fault positioning result.

Description

Technical Field

[0001] This invention relates to the field of power distribution network technology, and in particular to a method, device and electronic equipment for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network. Background Technology

[0002] With the development of new power distribution networks, the improvement of power cable production technology, and the reduction of application costs, the transition from overhead lines to three-core underground cables has become the main development trend in power distribution network laying. Three-core cables may experience insulation material deterioration due to harsh working environments, internal defects, or long-term online operation. The electrical and water trees formed by this deterioration in the cable insulation layer are highly susceptible to developing into conductive channels under overvoltage, leading to internal breakdown and the generation of an electric arc between the conductor and the metal shielding layer, resulting in a single-phase grounding arc fault through the grounding wire. Therefore, compared to other types of faults, the special structure of three-core cables makes them more prone to internal arc faults. Grounding arc faults in three-core cables can easily cause electrical fires, resulting in serious economic losses and even endangering personal safety. Furthermore, if a single-phase grounding arc fault is not cleared in time, it may escalate into a two-phase or even three-phase fault, leading to more serious power outages, jeopardizing the safe operation of modern power grids, disrupting normal production and daily life, and causing significant social and economic impacts. Therefore, accurately and reliably locating arc faults in the conductor-shield layer of three-core cables is of great significance for reducing power outage losses and ensuring the safe and stable operation of the power distribution system. Summary of the Invention

[0003] This invention provides a method, device, and electronic equipment for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network. It can accurately and quickly determine the location of the fault section after detecting an arc fault, which can effectively improve the reliability of system operation.

[0004] According to one aspect of the present invention, a method for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network is provided, comprising:

[0005] Cables are classified according to the shortest distance between each cable and the busbar of the power distribution system and the busbar to which each cable is connected.

[0006] After a fault is detected, the directional features of the fault transient characteristic modulus are extracted to determine the locations of the nodes at both ends of the faulty cable.

[0007] According to the preset distance, set the conductor-shield layer arc fault point of the faulty cable, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to the beginning of the non-faulty cable of the same level.

[0008] A sample library of arc fault locations in a three-core cable conductor-shielding layer is constructed by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus.

[0009] Based on the sample library of arc fault locations in the conductor-shield layer of the three-core cable, a neural network is used to fit the relationship between the fault location and the ratio of the amplitude of the principal component of the natural frequency of the fault transient characteristic modulus, forming a fault location-principal component amplitude ratio curve.

[0010] After detecting the node locations at both ends of the faulty cable, based on the fault location-principal component amplitude ratio relationship curve, the amplitude ratio of the principal component of the natural frequency of the fault transient characteristic modulus corresponding to the fault point is input, and the location result of the arc fault section of the three-core cable conductor-shield layer is output.

[0011] Optionally, the classification of cables based on the shortest distance between each cable and the power distribution system busbar and the busbar to which each cable's head is connected includes:

[0012] If the shortest distance between the current cable and the power distribution system bus is a first preset distance, then the current cable is classified as a first-level cable;

[0013] If the shortest distance between the current cable and the power distribution system busbar is the second preset distance, then the current cable is classified as a secondary cable; the first preset distance is less than the second preset distance.

[0014] Among cables of the same class, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

[0015] Optionally, after a fault is detected, the directional features of the fault transient characteristic modulus are extracted to determine the locations of the nodes at both ends of the faulty cable, including:

[0016] After a fault is detected, a low-frequency filter is used to extract the fault transient characteristic modulus in the low-frequency band.

[0017] Solve for the directional characteristics of the transient characteristic modulus of the fault;

[0018] Based on the directional characteristics of the fault transient characteristic modulus, the positions of the nodes at both ends of the faulty cable are determined by a step-by-step comparison method.

[0019] Optionally, arc fault points are set at preset distances for the conductor-shield layer of the faulty cable, and the amplitude ratio of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of a non-faulty cable of the same level is extracted, including:

[0020] An arc fault is set in the conductor-shield layer of the faulty cable at a preset distance. The ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of the non-faulty cable of the same level is extracted using the adaptive generalized S-transform.

[0021] Optionally, a sample library of arc fault location sections in a three-core cable conductor-shield layer is constructed using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus, including:

[0022] Using the ratio of the magnitude of the principal components of the transient characteristic modulus and natural frequency of different fault points as input independent variables and the location of the fault point as output dependent variable, a sample library of arc fault section locations of the conductor-shielding layer of a three-core cable is constructed.

[0023] Optionally, the fault transient characteristic modulus is the fault transient current modulus, which is calculated by the sum of the three-phase conductor current and the grounding wire current.

[0024] Optionally, before extracting the directional features of the fault transient characteristic modulus to determine the locations of the nodes at both ends of the faulty cable after a fault is detected, the method further includes:

[0025] Obtain the grounding current and the maximum grounding current of the primary cable during normal operation of the distribution network;

[0026] Based on the maximum value of the grounding current within a preset time after a fault change and the maximum grounding current of the primary cable during normal operation of the distribution network, determine whether a conductor-shield arc fault has occurred in the power distribution system.

[0027] Optionally, based on the maximum value of the grounding current within a preset time after the fault change and the maximum grounding current of the primary cable during normal operation of the distribution network, the determination of whether a conductor-shield arc fault has occurred in the power distribution system includes:

[0028] The following formula can be used to determine whether a conductor-shielding layer arc fault has occurred in the power distribution system:

[0029] In the formula, I represents the maximum value of the grounding current within a preset time after a sudden fault change. gs_Ιmax t0 is the maximum grounding current of the primary cable during normal operation of the distribution network; t0 is the moment of sudden change in the grounding current; T A The shortest duration of arc fault in the conductor-shield layer; T P It is the power frequency cycle.

[0030] According to another aspect of the present invention, a device for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network is provided, comprising:

[0031] The classification module is used to classify cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar to which the first end of each cable is connected.

[0032] The determination module is used to extract the directional features of the transient characteristic modulus of the fault after the fault is detected, so as to determine the positions of the nodes at both ends of the faulty cable.

[0033] The extraction module is used to set conductor-shield arc fault points on the faulty cable at a preset distance, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of a non-faulty cable of the same level.

[0034] The construction module is used to construct a sample library of arc fault locations in the conductor-shield layer of a three-core cable by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus.

[0035] The fitting module is used to fit the relationship between the fault location and the ratio of the amplitude of the principal component of the natural frequency of the fault transient characteristic modulus based on the sample library of arc fault section locations of the conductor-shield layer of the three-core cable using a neural network, thereby forming a fault location-principal component amplitude ratio relationship curve.

[0036] The positioning module is used to, after detecting the node positions at both ends of the faulty cable, input the amplitude ratio of the natural frequency of the fault transient characteristic modulus corresponding to the fault point based on the fault location-principal component amplitude ratio relationship curve, and output the positioning result of the arc fault section of the three-core cable conductor-shielding layer.

[0037] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0038] At least one processor; and

[0039] A memory communicatively connected to the at least one processor; wherein,

[0040] The memory stores a computer program that can be executed by the at least one processor, which is then executed by the at least one processor to enable the at least one processor to perform the arc fault location method for the conductor-shield layer of a three-core cable in a power distribution network according to any embodiment of the present invention.

[0041] This invention provides a method, device, and electronic equipment for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network. The method includes: classifying cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar connected to the beginning of each cable; after detecting a fault, extracting the directional features of the fault transient characteristic modulus to determine the node positions at both ends of the faulty cable; setting conductor-shield arc fault points at preset distances for the faulty cable, and extracting the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus of each fault point with that of the beginning of a non-faulty cable of the same level; constructing a sample library of conductor-shield arc fault section locations for three-core cables using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus; fitting the relationship between the fault location and the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus using a neural network based on the sample library of conductor-shield arc fault section locations for three-core cables, forming a fault location-principal component amplitude ratio relationship curve; after detecting the node positions at both ends of the faulty cable, inputting the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus corresponding to the fault point based on the fault location-principal component amplitude ratio relationship curve, and outputting the location result of the conductor-shield arc fault section of the three-core cable. The technical solution provided by this invention utilizes the characteristic modulus that reflects the faulty cable to accurately detect the endpoints of the faulty cable. Simultaneously, it uses the time-frequency characteristics of the transient characteristic modulus of the three-core cable fault to locate the conductor-shield arc fault section. This invention can quickly and accurately locate the fault after detecting an arc fault in the conductor-shield of a three-core cable, which is of great significance for reducing power outage losses and ensuring the safe and stable operation of the power distribution system.

[0042] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0043] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart of a method for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network, provided by an embodiment of the present invention;

[0045] Figure 2 A flowchart illustrating the specific process for extracting the magnitude ratio of the principal components of the transient characteristic modulus of faults using the adaptive generalized S-transform;

[0046] Figure 3This is a simulation model diagram of a 10kV cable-type distribution network provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the structure of an arc fault location device for a three-core cable conductor-shielding layer in a power distribution network, provided by an embodiment of the present invention.

[0048] Figure 5 This is a schematic diagram of the electronic device used in an embodiment of the present invention to provide a method for locating arc faults in the conductor core-shielding layer of a three-core cable in a power distribution network. Detailed Implementation

[0049] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0050] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0051] Figure 1 This is a flowchart illustrating a method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network, provided by an embodiment of the present invention. This embodiment is applicable to accurately and reliably locating arc faults in the conductor-shield layer of a three-core cable. This method can be executed by a device for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network. This device can be implemented in hardware and / or software and can be configured in any electronic device with communication capabilities. Figure 1 As shown, the method includes:

[0052] S110. Classify cables according to the shortest distance between each cable and the busbar of the power distribution system and the busbar to which each cable is connected.

[0053] Three-core cables are a type of power cable containing three independent conductive cores, typically A, B, and C phase cores, wrapped in insulating material and equipped with a metallic shielding layer, such as copper tape or aluminum foil. Their structural feature is the coaxial arrangement of the three-phase cores and shielding layer, primarily used for transmitting three-phase alternating current in medium- and low-voltage distribution networks. Because three-core cables are usually buried underground or in cable trenches, their insulation layer is susceptible to environmental corrosion or mechanical damage, potentially leading to arcing faults between the cores and the shielding layer. In three-core cables, insulation deterioration, such as the development of electrical trees, water trees, or conductive channels formed by overvoltage breakdown, can cause arcing faults between the cores and the metallic shielding layer. Such faults can create single-phase grounding arcs through the grounding wire, potentially causing fires or escalating into three-phase short circuits, threatening the safety of the distribution network. This invention aims to accurately locate such faults. The distribution system busbar refers to the main conductor in the distribution system used for collecting, distributing, and transmitting electrical energy. The shortest distance refers to the physical shortest path length from each cable to the busbar in the system. It is usually the straight-line distance or the shortest distance in the actual cable path, rather than the electrically equivalent distance. It is used to reflect the spatial or path association between the cable and the busbar. The cable end refers to the starting end of the cable, usually on the power supply side or the end closest to the busbar.

[0054] Specifically, cables are classified according to their shortest distance from the power distribution system busbar. Cables with a shortest distance of 0 from the power distribution system busbar (i.e., the cable is directly connected to the main busbar) are classified as Class I cables, cables with a shortest distance of 1 from the power distribution system busbar (i.e., the cable is separated from the main busbar by one cable) are classified as Class II cables, and so on. Among cables of the same class, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

[0055] S120. After a fault is detected, the directional characteristics of the fault transient characteristic modulus are extracted to determine the location of the nodes at both ends of the faulty cable.

[0056] During an arc fault in a cable, specific transient components are generated in the current and voltage signals. Signal processing techniques, such as low-frequency filtering and modulus transformation, are used to extract the characteristics of these transient components, which are called fault transient characteristic moduli. Directional characteristics refer to the properties of the transient characteristic moduli in the direction of propagation. When a cable fault occurs, the transient signal propagates from the fault point to both ends of the cable, forming "forward" and "reverse" transient waves.

[0057] Specifically, after detecting an arc fault in the conductor-shield layer of a three-core cable, transient signals are collected using a low-frequency filter or current / voltage transformers installed at the cable nodes. An algorithm is then used to determine the directional characteristics of the transient characteristic modulus. Specifically, the directional characteristics of the fault transient characteristic modulus are as follows: the modulus direction at the beginning of all cables along the fault path from the fault current to the distribution system busbar is consistent, while the modulus direction at the beginning of other healthy cables is opposite. Since the transient signal propagates from the fault point to both endpoints, its directional characteristics clearly indicate "which two nodes are the endpoints of the faulty cable." For example, if the transient modulus direction collected at node X is "propagating from the fault point to X," and the transient modulus direction collected at node Y is "propagating from the fault point to Y," and no other nodes detect the transient wave of the fault, then the two endpoints of the faulty cable can be determined to be nodes X and Y.

[0058] S130. Set conductor-shield arc fault points for faulty cables at preset distances, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of a non-faulty cable of the same level.

[0059] The faulty cable refers to the faulty cable identified in step S120 or the target cable pre-set for simulating the fault, and is the research object of the experiment. The preset distance refers to the pre-set location parameters for setting fault points on the cable, such as different distances like 1m, 3m, and 5m from the cable's beginning, to study the impact of faults at different locations on signal characteristics. This part functions by creating multiple "conductor-shielding layer arc faults" at pre-planned distances on the faulty cable, providing fault samples with different conditions for subsequent signal analysis. Each fault point corresponds to a preset distance. The non-faulty cable of the same class refers to a normal cable of the same class as the faulty cable but without arc faults. The amplitude of the principal component of the fault transient characteristic modulus at the fault point and the beginning of the non-faulty cable of the same class, i.e., the maximum amplitude of the time-frequency analysis result in the mid-frequency band, is considered to be the ratio of the amplitude of the fault transient current modulus to the amplitude of the principal component of the natural frequency.

[0060] Specifically, on the faulty cable, "conductor-shield arc faults" are created at pre-set distances (e.g., 1m, 3m, 5m). For each fault point, the transient signal generated is collected, and the amplitude of the "principal component of the natural frequency" is extracted. Simultaneously, the transient signal from the beginning of a normal cable of the same grade is collected, and the amplitude of its "principal component of the natural frequency" is extracted. The ratio of the two amplitudes is calculated as a characteristic parameter of the fault point. This provides data support for subsequent research on the correlation between "fault location" and "transient signal amplitude ratio" in establishing a fault characteristic database.

[0061] S140. Construct a sample library of arc fault locations in the conductor-shield layer of a three-core cable by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus.

[0062] Specifically, multiple conductor-shield arc fault points are set at preset distances on the faulty cable to form different fault sections. For example, three fault points are set at the beginning of the section, three in the middle section, and three at the end. For each fault point, transient signals are collected, and the "amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus" is calculated. Each "amplitude ratio" is associated with its corresponding "fault section location" to form a "sample data". A large amount of sample data from different sections is accumulated, ultimately forming a "sample library of arc fault section locations for three-core cables". The "specific amplitude ratio" corresponding to "arc faults in different sections" is obtained through experiments, and the correspondence between the two is systematically stored to form a sample library. In subsequent actual working condition testing, only the "amplitude ratio" of the faulty cable needs to be measured and compared with the data in the sample library to quickly match the faulty section and achieve preliminary fault location. This sample library is the foundation for subsequent intelligent fault diagnosis, such as neural network model training, and can significantly improve the efficiency and accuracy of fault section identification.

[0063] S150. Based on the sample library of arc fault sections in the conductor-shield layer of a three-core cable, a neural network is used to fit the relationship between the fault location and the ratio of the amplitude of the principal component of the natural frequency of the fault transient characteristic modulus, forming a fault location-principal component amplitude ratio curve.

[0064] Specifically, based on the sample database of arc fault locations in the conductor-shield layer of a three-core cable, a mathematical formula is found through neural network training to characterize the relationship between the fault location and the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus. This forms a fault location-principal component amplitude ratio curve. Based on this curve, by inputting the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus under actual operating conditions, the location result of the arc fault section in the conductor-shield layer of the three-core cable can be obtained.

[0065] S160. After detecting the node positions at both ends of the faulty cable, based on the fault location-principal component amplitude ratio relationship curve, input the natural frequency principal component amplitude ratio of the fault transient characteristic modulus corresponding to the fault point, and output the arc fault section location result of the three-core cable conductor-shield layer.

[0066] Specifically, in actual operation, when an arc fault is detected in the conductor-shield layer of a three-core cable and the locations of the nodes at both ends of the faulty cable are determined, the extracted fault transient characteristic modulus natural frequency principal component amplitude ratio is input into the fitted fault location-principal component amplitude ratio curve, and the location result of the arc fault section of the three-core cable conductor-shield layer can be output.

[0067] This invention provides a method, device, and electronic equipment for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network. The method includes: classifying cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar connected to the beginning of each cable; after detecting a fault, extracting the directional features of the fault transient characteristic modulus to determine the node positions at both ends of the faulty cable; setting conductor-shield arc fault points at preset distances for the faulty cable, and extracting the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus of each fault point with that of the beginning of a non-faulty cable of the same level; constructing a sample library of conductor-shield arc fault section locations for three-core cables using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus; fitting the relationship between the fault location and the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus using a neural network based on the sample library of conductor-shield arc fault section locations for three-core cables, forming a fault location-principal component amplitude ratio relationship curve; after detecting the node positions at both ends of the faulty cable, inputting the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus corresponding to the fault point based on the fault location-principal component amplitude ratio relationship curve, and outputting the location result of the conductor-shield arc fault section of the three-core cable. The technical solution provided by this invention utilizes the characteristic modulus that reflects the faulty cable to accurately detect the endpoints of the faulty cable. Simultaneously, it uses the time-frequency characteristics of the transient characteristic modulus of the three-core cable fault to locate the conductor-shield arc fault section. This invention can quickly and accurately locate the fault after detecting an arc fault in the conductor-shield of a three-core cable, which is of great significance for reducing power outage losses and ensuring the safe and stable operation of the power distribution system.

[0068] In some other embodiments, optionally, step S110 specifically includes:

[0069] If the shortest distance between the current cable and the power distribution system busbar is the first preset distance, the current cable is classified as a first-level cable; if the shortest distance between the current cable and the power distribution system busbar is the second preset distance, the current cable is classified as a second-level cable; the first preset distance is less than the second preset distance; among cables of the same level, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

[0070] Specifically, cables are classified according to their shortest distance from the main busbar. Cables with a shortest distance of 0 from the main busbar (i.e., the cable is directly connected to the main busbar) are classified as Class I cables, cables with a shortest distance of 1 from the main busbar (i.e., there is a cable between the cable and the main busbar) are classified as Class II cables, and so on. Among cables of the same class, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

[0071] Optionally, step S120 specifically includes:

[0072] After a fault is detected, a low-frequency filter is used to extract the fault transient characteristic modulus in the low-frequency band; the directional characteristics of the fault transient characteristic modulus are solved; and the positions of the nodes at both ends of the fault cable are determined by a step-by-step comparison based on the directional characteristics of the fault transient characteristic modulus.

[0073] Specifically, a low-frequency filter is used to extract the transient characteristic modulus of the fault in the low-frequency band, and the directional characteristics of the transient characteristic modulus signal in this frequency band are solved. When a fault is detected, the faulty cable is inspected, starting with Class I cables. The directional characteristics of the modulus at the beginning of each cable line are compared. Class I cables with a different direction than the other cables are considered to be on the fault path. If the Class I cable has no branches, i.e., no lower-level cables, then this cable is the faulty cable. If the Class I cable has lower-level cables, the directional characteristics of the modulus at the beginning of the lower-level cables are compared. If the directional characteristics of the modulus at the beginning of each compared Class II cable are opposite to those of the Class I cable, it means that all Class II cables are not on the fault path, and the faulty cable is determined to be the Class I cable. If there is a cable with the same directional characteristics as the Class I cable, then the Class II cable is considered to be on the fault path, and the determination of whether the Class II cable has lower-level branches continues. The system proceeds step by step to determine the faulty cable. If the final cable connected to the load in the distribution network still has the same modulus direction characteristics as the first end of the upper-level cable, then the final cable is the faulty cable. After the determination is completed, the positions of the nodes at both ends of the faulty cable are output.

[0074] Optionally, step S130 specifically includes:

[0075] An arc fault is set in the conductor-shield layer of the faulty cable at a preset distance. The ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of the non-faulty cable of the same level is extracted using the adaptive generalized S-transform.

[0076] Optionally, step S140 specifically includes:

[0077] Using the ratio of the magnitude of the principal components of the transient characteristic modulus and natural frequency of different fault points as input independent variables and the location of the fault point as output dependent variable, a sample library of arc fault section locations of the conductor-shielding layer of a three-core cable is constructed.

[0078] Optionally, the fault transient characteristic modulus is the fault transient current modulus, which is calculated by the sum of the three-phase conductor current and the grounding wire current.

[0079] Optionally, before step S120, the method further includes:

[0080] Obtain the grounding current and the maximum grounding current of the primary cable during normal operation of the distribution network;

[0081] Based on the maximum value of the grounding current within a preset time after a fault change and the maximum grounding current of the primary cable during normal operation of the distribution network, determine whether a conductor-shield arc fault has occurred in the power distribution system.

[0082] The preset time is defined as the time from the moment of sudden change in the grounding current to the moment after the shortest duration of the arc fault in the conductor-shield layer, specifically as [t0, t0+T] in the following formula. A This time period.

[0083] Specifically, the following formula is used to determine whether a conductor-shield arcing fault has occurred in the power distribution system:

[0084] In the formula, I represents the maximum value of the grounding current within a preset time after a sudden fault change. gs_Ιmax t0 is the maximum grounding current of the primary cable during normal operation of the distribution network; t0 is the moment of sudden change in the grounding current; T A The shortest duration of arc fault in the conductor-shield layer; T P It is the power frequency cycle.

[0085] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0086] Step 1: Classify the cables according to the shortest distance from each cable to the power distribution system bus and the bus to which each cable is connected.

[0087] Step 2: After the fault is detected, the directional characteristics of the fault transient characteristic modulus are extracted, and the positions of the nodes at both ends of the faulty cable are determined by a step-by-step determination method based on these characteristics.

[0088] In practical implementation, the fault detection initiation criterion is set as follows:

[0089]

[0090] Step 3: After determining the node positions at both ends of the faulty cable, set the conductor-shield arc fault points at a preset distance on the faulty cable, and extract the amplitude ratio of the principal components of the fault transient characteristic modulus and natural frequency of each fault point with the beginning of the non-faulty cable of the same level.

[0091] Step 4: By constructing a sample library of arc fault locations in the conductor-shield layer of a three-core cable, the relationship between fault location and amplitude ratio is fitted.

[0092] Step 5: After the system detects the nodes at both ends of the faulty cable, the amplitude ratio of the principal components of the fault transient feature modulus and natural frequency is extracted by inputting the corresponding fitting neural network to obtain the fault location result.

[0093] In this example, the cable classification method is as follows:

[0094] Cables are classified according to their shortest distance from the main busbar. Cables with a shortest distance of 0 from the main busbar (i.e., the cable is directly connected to the main busbar) are classified as Class I cables, cables with a shortest distance of 1 from the main busbar (i.e., there is a cable between the cable and the main busbar) are classified as Class II cables, and so on. Among cables of the same class, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

[0095] In this example, the method for extracting the direction of the transient characteristic modulus of the fault is as follows:

[0096] A low-frequency filter is used to extract the fault transient characteristic modulus in the low-frequency band, and the directional characteristics of the fault transient characteristic modulus signal in this frequency band are solved.

[0097] In practical implementation, the fault transient characteristic modulus is the fault transient α current modulus, specifically the sum of the three-phase conductor current and the grounding wire current. Its calculation formula is as follows:

[0098] i α (t)=i A (t)+i B (t)+i C (t)+i g (t);

[0099] In the formula, i A (t), i B (t), i C (t), i g (t) represents the signal components of the three-phase conductor currents A, B, and C of the cable and the grounding current, respectively. α (t) represents the fault transient α current modulus.

[0100] The directional characteristics of the fault transient characteristic modulus are as follows:

[0101] The α-modulus direction characteristics of all cables along the fault path from the fault current to the power distribution system bus are consistent, while the α-modulus direction characteristics of other healthy cables are opposite.

[0102] In this example, the method for determining the step-by-step location of the nodes at both ends of the faulty cable is as follows:

[0103] Upon detecting a fault, the faulty cable is inspected, starting with Class I cables. The directional characteristics of the modulus at the beginning of each cable line are compared. Class I cables with a different directional modulus than the others are considered to be on the fault path. If a Class I cable has no branches (i.e., no lower-level cables), it is considered a faulty cable. If a Class I cable has lower-level cables, the directional characteristics of the modulus at the beginning of the lower-level cables are compared. If the directional characteristics of the modulus at the beginning of each compared Class II cable are opposite to those of the Class I cable, it means that all Class II cables are not on the fault path, and the faulty cable is identified as the Class I cable. If a cable with the same directional characteristics as a Class I cable exists, it is considered that the Class II cable is also on the fault path, and the system continues to determine if it has lower-level branches. This process is repeated level by level. If, when the final-level cable connecting to the load in the distribution network is reached, a cable with the same directional modulus at the beginning of its length as the upper-level cable still exists, then that final-level cable is considered a faulty cable. After completing the inspection, the locations of the nodes at both ends of the faulty cable are output.

[0104] In this example, the amplitude of the principal component of the fault transient characteristic modulus at the head end of the faulty and non-faulty cables of the same level, which is the maximum amplitude of the time-frequency analysis result in the mid-frequency band, is considered to be the ratio of the amplitude of the fault transient α current modulus to the amplitude of the principal component of the natural frequency.

[0105] In the specific implementation process, the amplitude ratio of the principal components of the natural frequency of the fault transient α current modulus is extracted using the adaptive generalized S-transform. The specific process is as follows: Figure 2 As shown, Figure 2 The flowchart for extracting the magnitude ratio of the principal components of the transient characteristic modulus of a fault using the adaptive generalized S-transform is as follows: First, the input time-domain signal x(n) is used; then, the time-domain signal is converted to a frequency-domain representation using a fast Fourier transform to obtain the signal's spectrum X(k); finally, the signal spectrum is smoothed by removing noise and fluctuations to make the spectrum smoother, and the smoothed spectrum X is output. nor_sm (k); Solve for the power spectral entropy, calculate the entropy value of the spectrum as a measure of signal complexity, and calculate the scaling factor r based on the magnitude of the entropy value through a mapping relationship; construct a standard deviation function σ based on the scaling factor r. AGST (X(k)) is used to control the width of the Gaussian window function; an adaptive Gaussian window function G is constructed based on the standard deviation function. AGST (k,mf); Finally, the frequency domain signal is converted back to the time domain by the Fast Fourier Transform to obtain the time-frequency domain representation, and the final time-frequency analysis results are presented.

[0106] In this example, the sample library construction and fitting method is as follows:

[0107] Arc faults are set at preset distances in the conductor-shield layer of the faulty cable. The ratio of the magnitude of the principal component of the transient current modulus of the fault to that of the non-faulty cable at the beginning of the same level is used as the input independent variable, and the corresponding fault location is used as the output dependent variable. A sample library of arc fault section locations in the conductor-shield layer of the three-core cable is constructed. The relationship between the fault location and the magnitude ratio is fitted by a neural network to form a curve showing the relationship between the fault location and the magnitude ratio of the principal component.

[0108] To verify the reliability and effectiveness of this invention, a system was built in PSCAD / EMTDC as follows: Figure 3 The simulation model of the 10kV cable-type distribution network shown is as follows. Figure 3 The following is a simulation model diagram of a 10kV cable-type distribution network provided in this embodiment of the invention. The three-core cable model is configured with parameters according to YJV22-6 / 10kV-3*70mm2, and the lengths of each cable line are shown in Table 1. By changing the arc model parameters and the fault occurrence time, arc faults in the cable conductor-shield layer are set under different initial conditions. The location results under different fault conditions are shown in Table 2.

[0109] Table 1

[0110] cable Two-end nodes Cable length cable Two-end nodes Cable length L1 1,2 5.1km L2 3,4 5.7km L3 5,6 6.4km L4 7,8 4.0km L5 9,10 6.0km L6 11,12 4.8km L7 13,14 6.5km L8 15,16 3.9km L9 17,18 6.6km L10 19,20 7.2km

[0111] Table 2

[0112]

[0113] In Table 2, x f M is the distance to the fault. GZ M represents the amplitude of the principal component of the transient characteristic modulus and natural frequency at the head of the faulty cable. TJ The amplitude of the principal component of the transient characteristic modulus of the cable head end is the natural frequency of the same level, and Mr is the ratio of the two amplitudes. As shown in Table 2, under different cable lengths, different fault conditions, and different fault locations, the arc fault location method of the conductor core-shield layer of the three-core cable in the distribution network proposed in this invention can achieve accurate detection of the arc fault section of the conductor core-shield layer of the three-core cable in the distribution network.

[0114] The technical solution provided by the embodiments of the present invention can adapt to complex and ever-changing arc fault conditions of three-core cables, thereby improving the safe operation level of cable-type distribution networks.

[0115] Figure 4 This is a schematic diagram of the structure of an arc fault location device for a three-core cable conductor-shielding layer in a power distribution network, provided in an embodiment of the present invention. (See attached diagram.) Figure 4 The device includes a classification module 410, a determination module 420, an extraction module 430, a construction module 440, a fitting module 450, and a localization module 460.

[0116] The classification module 410 is used to classify cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar to which the first end of each cable is connected.

[0117] The determination module 420 is used to extract the directional features of the transient characteristic modulus of the fault after a fault is detected, so as to determine the location of the nodes at both ends of the faulty cable.

[0118] The extraction module 430 is used to set the conductor-shield arc fault point of the faulty cable according to the preset distance, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to the beginning of the non-faulty cable of the same level.

[0119] Module 440 is used to construct a sample library of arc fault locations in the conductor-shield layer of a three-core cable by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus.

[0120] The fitting module 450 is used to fit the relationship between the fault location and the principal component amplitude ratio of the natural frequency of the fault transient characteristic modulus based on the sample library of arc fault section locations of the conductor-shield layer of a three-core cable using a neural network, thereby forming a fault location-principal component amplitude ratio relationship curve.

[0121] The positioning module 460 is used to, after detecting the node positions at both ends of the faulty cable, input the amplitude ratio of the natural frequency of the fault transient characteristic modulus corresponding to the fault point based on the fault location-principal component amplitude ratio relationship curve, and output the location result of the arc fault section of the three-core cable conductor-shielding layer.

[0122] The arc fault location device for the conductor-shielding layer of a three-core cable in a power distribution network provided in this embodiment can execute the arc fault location method for the conductor-shielding layer of a three-core cable in a power distribution network provided in any embodiment of this invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0123] Figure 5 This is a schematic diagram of the electronic device used in an embodiment of the present invention to provide a method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workbenches, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0124] like Figure 5As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 may also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0125] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0126] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, central processing unit (CPU), graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, digital signal processors (DSPs), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as a method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network.

[0127] In some embodiments, the method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or installed on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the method for locating arc faults in the conductor-shield layer of a three-core cable in a power distribution network by any other suitable means (e.g., by means of firmware).

[0128] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0129] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0130] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0131] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0132] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or computing systems that include middleware components (e.g., application servers), or computing systems that include frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0133] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0134] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0135] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network, characterized in that, include: Cables are classified according to the shortest distance between each cable and the busbar of the power distribution system and the busbar to which each cable is connected. After a fault is detected, the directional features of the fault transient characteristic modulus are extracted to determine the locations of the nodes at both ends of the faulty cable. According to the preset distance, set the conductor-shield layer arc fault point of the faulty cable, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to the beginning of the non-faulty cable of the same level. A sample library of arc fault locations in a three-core cable conductor-shielding layer is constructed by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus. Based on the sample library of arc fault locations in the conductor-shield layer of the three-core cable, a neural network is used to fit the relationship between the fault location and the ratio of the amplitude of the principal component of the natural frequency of the fault transient characteristic modulus, forming a fault location-principal component amplitude ratio curve. After detecting the node locations at both ends of the faulty cable, based on the fault location-principal component amplitude ratio relationship curve, the amplitude ratio of the principal component of the natural frequency of the fault transient characteristic modulus corresponding to the fault point is input, and the location result of the arc fault section of the three-core cable conductor-shield layer is output.

2. The method according to claim 1, characterized in that, The classification of cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar to which each cable's head is connected includes: If the shortest distance between the current cable and the power distribution system bus is a first preset distance, then the current cable is classified as a first-level cable; If the shortest distance between the current cable and the power distribution system busbar is the second preset distance, then the current cable is classified as a secondary cable; the first preset distance is less than the second preset distance. Among cables of the same class, cables whose starting ends are connected to the same busbar are classified as the same type of busbar.

3. The method according to claim 1, characterized in that, After a fault is detected, the directional characteristics of the fault transient characteristic modulus are extracted to determine the locations of the nodes at both ends of the faulty cable, including: After a fault is detected, a low-frequency filter is used to extract the fault transient characteristic modulus in the low-frequency band. Solve for the directional characteristics of the transient characteristic modulus of the fault; Based on the directional characteristics of the fault transient characteristic modulus, the positions of the nodes at both ends of the faulty cable are determined by a step-by-step comparison method.

4. The method according to claim 1, characterized in that, According to a preset distance, arc fault points are set in the conductor-shield layer of the faulty cable. The amplitude ratio of the principal component of the transient characteristic modulus of each fault point and the natural frequency of the non-faulty cable of the same level is extracted, including: An arc fault is set in the conductor-shield layer of the faulty cable at a preset distance. The ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of the non-faulty cable of the same level is extracted using the adaptive generalized S-transform.

5. The method according to claim 1, characterized in that, Based on the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus, a sample library of arc fault location sections in a three-core cable conductor-shield layer is constructed, including: Using the ratio of the magnitude of the principal components of the transient characteristic modulus and natural frequency of different fault points as input independent variables and the location of the fault point as output dependent variable, a sample library of arc fault section locations of the conductor-shielding layer of a three-core cable is constructed.

6. The method according to claim 3, characterized in that, The fault transient characteristic modulus is the fault transient current modulus, which is calculated by the sum of the three-phase conductor current and the grounding wire current.

7. The method according to claim 1, characterized in that, Before extracting the directional features of the fault transient characteristic modulus to determine the locations of the nodes at both ends of the faulty cable after fault detection, the process also includes: Obtain the grounding current and the maximum grounding current of the primary cable during normal operation of the distribution network; Based on the maximum value of the grounding current within a preset time after a fault change and the maximum grounding current of the primary cable during normal operation of the distribution network, determine whether a conductor-shield arc fault has occurred in the power distribution system.

8. The method according to claim 7, characterized in that, Determining whether a conductor-shield arc fault has occurred in the power distribution system based on the maximum value of the grounding current within a preset time after a sudden fault change and the maximum grounding current of the primary cable during normal operation of the power distribution network includes: The following formula can be used to determine whether a conductor-shielding layer arc fault has occurred in the power distribution system: In the formula, I represents the maximum value of the grounding current within a preset time after a sudden fault change. gs_Ιmax t0 is the maximum grounding current of the primary cable during normal operation of the distribution network; t0 is the moment of sudden change in the grounding current; T A The shortest duration of arc fault in the conductor-shield layer; T P It is the power frequency cycle.

9. A device for locating arc faults in the conductor-shielding layer of a three-core cable in a power distribution network, characterized in that, include: The classification module is used to classify cables based on the shortest distance between each cable and the busbar of the power distribution system and the busbar to which the first end of each cable is connected. The determination module is used to extract the directional features of the transient characteristic modulus of the fault after the fault is detected, so as to determine the positions of the nodes at both ends of the faulty cable. The extraction module is used to set conductor-shield arc fault points on the faulty cable at a preset distance, and extract the ratio of the amplitude of the principal component of the fault transient characteristic modulus and natural frequency of each fault point to that of the beginning of a non-faulty cable of the same level. The construction module is used to construct a sample library of arc fault locations in the conductor-shield layer of a three-core cable by using the amplitude ratio of the principal components of the natural frequency of the fault transient characteristic modulus. The fitting module is used to fit the relationship between the fault location and the ratio of the amplitude of the principal component of the natural frequency of the fault transient characteristic modulus based on the sample library of arc fault section locations of the conductor-shield layer of the three-core cable using a neural network, thereby forming a fault location-principal component amplitude ratio relationship curve. The positioning module is used to, after detecting the node positions at both ends of the faulty cable, input the amplitude ratio of the natural frequency of the fault transient characteristic modulus corresponding to the fault point based on the fault location-principal component amplitude ratio relationship curve, and output the positioning result of the arc fault section of the three-core cable conductor-shielding layer.

10. An electronic device, characterized in that, The electronic device includes: At least one processor; and A memory communicatively connected to the at least one processor; wherein, The memory stores a computer program that can be executed by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the arc fault location method for the conductor-shield layer of a three-core cable in a power distribution network as described in any one of claims 1-8.

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