Cable fault current detection method, electronic device, and storage medium

Abstract

This application provides a cable fault current detection method, electronic device, and storage medium. Multiple distinct cable subsets are located within a cable trench, each containing the same number of cables. Each cable subset is monitored by a flexible current transformer group. The method includes: acquiring high-frequency mixed current signals and power frequency mixed current signals output by each flexible current transformer group; determining the high-frequency current component of the target cable based on the high-frequency mixed current signals and a first mathematical model, and using the high-frequency current component as the high-frequency fault current component of the target cable; determining the power frequency current component of the target cable based on the power frequency mixed current signals and a second mathematical model; and extracting the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable. This enables independent, real-time detection of the fault current of each cable in a clustered, submerged cable laying scenario, improving cable fault detection coverage.

Description

Technical Field

[0001] This application relates to the field of power detection technology, and in particular to a cable fault current detection method, electronic device and storage medium. Background Technology

[0002] In urban power distribution networks, with the increasing urbanization and rapid growth in power supply demand, underground cable lines have become a core component of the transmission network due to their advantages such as stable laying environment, strong resistance to weather interference, and reduced ground space occupation. However, transmission channel resources are limited, and cable lines are often laid in clusters, that is, multiple cables are laid side by side or stacked in the same cable trench to maximize space utilization. While this cluster laying mode improves the utilization rate of transmission channels, it also brings significant heat dissipation problems, accelerates the aging and breakage of cable supports, and ultimately leads to the phenomenon of cables being laid at the bottom. This bottom laying further worsens the heat dissipation conditions of the cable trench, increases the risk of thermal defects in cables, and may even cause cable breakdown accidents, greatly threatening the safe operation of the power grid. Therefore, how to achieve accurate detection of fault current in each cable under the complex scenario of clustered bottom laying has become a key technical challenge to ensure the safe operation of the power distribution network.

[0003] In related technologies, the detection of cable fault current mainly relies on rigid current transformers. Specifically, a rigid current transformer is installed independently for each cable in the cable trench. The current signal of the cable is collected by the current transformer, and this current signal is used to analyze the characteristics of cable faults.

[0004] However, due to the limitations of the physical structure and installation conditions of current transformers, the above-mentioned scheme is difficult to achieve independent and real-time detection of fault current for each cable in clustered underground laying scenarios, which affects the cable fault detection coverage and cannot meet the urgent needs of high-reliability distribution networks for panoramic status perception and accurate fault diagnosis. Summary of the Invention

[0005] This application provides a cable fault current detection method, electronic device, and storage medium to solve the problem in related technologies that it is difficult to achieve independent and real-time detection of fault current for each cable in clustered underground laying scenarios, which affects the cable fault detection coverage and fails to meet the urgent needs of high-reliability distribution networks for panoramic status perception and accurate fault diagnosis.

[0006] In a first aspect, this application provides a cable fault current detection method, wherein multiple distinct cable subsets are provided in the cable trench, each cable subset contains the same number of cables, and each cable subset is monitored by a flexible current transformer group, the number of flexible current transformer groups is equal to the total number of cables in the cable trench, and the flexible current transformer group includes flexible high-frequency current transformers and flexible power frequency current transformers.

[0007] Methods for detecting cable fault current include:

[0008] Acquire the high-frequency mixed current signal output by each flexible high-frequency current transformer, and the power frequency mixed current signal output by each flexible power frequency current transformer.

[0009] Based on the various high-frequency mixed current signals and the first mathematical model, the high-frequency current component of the target cable is determined, and the high-frequency current component is used as the high-frequency fault current component of the target cable. The first mathematical model is constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable.

[0010] Based on the mixed power frequency current signals and the second mathematical model, the power frequency current component of the target cable is determined. The second mathematical model is constructed based on the coverage relationship between the flexible power frequency current transformer and each cable.

[0011] The fault component is extracted from the power frequency current component to obtain the power frequency fault current component of the target cable.

[0012] In one possible implementation, the first mathematical model is a set of first linear equations with the high-frequency current components of each cable as unknowns. Based on each high-frequency mixed current signal and the first mathematical model, the high-frequency current components of the target cable are determined, including:

[0013] Each high-frequency mixed current signal is input into the first linear equation set. By solving the first linear equation set, the high-frequency current component of the target cable is obtained.

[0014] In the first system of linear equations, the first... The equation represents the first... The high-frequency hybrid current signal output by the flexible high-frequency current transformer is equal to the first... The sum of the high-frequency current components of each cable within the subset of cables monitored by each flexible high-frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0015] In one possible implementation, the second mathematical model is a set of second linear equations with the power frequency current components of each cable as unknowns. Based on the mixed power frequency current signals and the second mathematical model, the power frequency current components of the target cable are determined, including:

[0016] The mixed power frequency current signals are input into the second linear equation set, and the power frequency current components of the target cable are obtained by solving the second linear equation set.

[0017] In the second system of linear equations, the first... The equation represents the first... The power frequency hybrid current signal output by the flexible power frequency current transformer is equal to the first... The sum of the power frequency current components of each cable within the subset of cables monitored by each flexible power frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0018] In one possible implementation, fault component extraction is performed on the power frequency current component to obtain the power frequency fault current component of the target cable, including:

[0019] Obtain the three-phase load current of the target cable;

[0020] The three-phase unbalanced current of the target cable is calculated based on the three-phase load current.

[0021] The difference between the power frequency current component and the three-phase unbalanced current is determined as the power frequency fault current component of the target cable.

[0022] In one possible implementation, the cable fault current detection method further includes:

[0023] The fault state of the target cable is determined based on the power frequency fault current component and / or the high frequency fault current component.

[0024] In one possible implementation, determining the high-frequency current component and the power frequency current component of the target cable further includes:

[0025] Obtain environmental parameters within the cable trench, including temperature and humidity;

[0026] Based on environmental parameters, the high-frequency current component and / or power frequency current component are dynamically corrected.

[0027] In one possible implementation, the high-frequency current component and / or power frequency current component are dynamically corrected based on environmental parameters, including:

[0028] Environmental parameters, high-frequency mixed current signals, and power frequency mixed current signals are input into a trained neural network model, which then predicts the corrected high-frequency current components and / or power frequency current components.

[0029] Secondly, this application provides a cable fault current detection device, in which multiple different cable subsets are provided in the cable trench, each cable subset contains the same number of cables, each cable subset is monitored by a flexible current transformer group, the number of flexible current transformer groups is equal to the total number of cables in the cable trench, and the flexible current transformer group includes flexible high-frequency current transformers and flexible power frequency current transformers.

[0030] The cable fault current detection device includes:

[0031] The acquisition module is used to acquire the high-frequency mixed current signal output by each flexible high-frequency current transformer and the power frequency mixed current signal output by each flexible power frequency current transformer.

[0032] The first determining module is used to determine the high-frequency current component of the target cable based on each high-frequency mixed current signal and the first mathematical model, and to use the high-frequency current component as the high-frequency fault current component of the target cable. The first mathematical model is constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable.

[0033] The second determining module is used to determine the power frequency current component of the target cable based on each power frequency mixed current signal and the second mathematical model. The second mathematical model is constructed based on the coverage relationship between the flexible power frequency current transformer and each cable.

[0034] The processing module is used to extract the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable.

[0035] In one possible implementation, the first mathematical model is a first set of linear equations with the high-frequency current components of each cable as unknowns. The first determining module is specifically used to: input each high-frequency mixed current signal into the first set of linear equations, and obtain the high-frequency current components of the target cable by solving the first set of linear equations; wherein, in the first set of linear equations, the first... The equation represents the first... The high-frequency hybrid current signal output by the flexible high-frequency current transformer is equal to the first... The sum of the high-frequency current components of each cable within the subset of cables monitored by each flexible high-frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0036] In one possible implementation, the second mathematical model is a second set of linear equations with the power frequency current components of each cable as unknowns. The second determining module is specifically used to: input each power frequency mixed current signal into the second set of linear equations, and obtain the power frequency current components of the target cable by solving the second set of linear equations; wherein, in the second set of linear equations, the first... The equation represents the first... The power frequency hybrid current signal output by the flexible power frequency current transformer is equal to the first... The sum of the power frequency current components of each cable within the subset of cables monitored by each flexible power frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0037] In one possible implementation, the processing module is specifically used to: obtain the three-phase load current of the target cable; calculate the three-phase unbalanced current of the target cable based on the three-phase load current; and determine the difference between the power frequency current component and the three-phase unbalanced current as the power frequency fault current component of the target cable.

[0038] In one possible implementation, the processing module is further configured to: determine the fault state of the target cable based on the power frequency fault current component and / or the high frequency fault current component.

[0039] In one possible implementation, the processing module is further configured to: acquire environmental parameters within the cable trench, including temperature and humidity; and dynamically correct the high-frequency current component and / or power frequency current component based on the environmental parameters.

[0040] In one possible implementation, the processing module is further configured to: input environmental parameters, high-frequency mixed current signals, and power frequency mixed current signals into a trained neural network model, and predict the corrected high-frequency current components and / or power frequency current components through the neural network model.

[0041] Thirdly, this application provides an electronic device, including: a memory and a processor;

[0042] The memory stores instructions that the computer executes;

[0043] The processor executes computer execution instructions stored in memory, causing the processor to perform the first aspect and / or various possible implementations of the first aspect as described above.

[0044] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the first aspect and / or various possible embodiments of the first aspect.

[0045] Fifthly, this application provides a computer program product, including a computer program that, when executed by a processor, implements the first aspect and / or various possible implementations of the first aspect.

[0046] The cable fault current detection method, electronic device, and storage medium provided in this application involve multiple distinct cable subsets within a cable trench, each containing the same number of cables. Each cable subset is monitored by a flexible current transformer group, the number of flexible current transformer groups equal to the total number of cables in the cable trench, and the flexible current transformer groups include flexible high-frequency current transformers and flexible power frequency current transformers. The cable fault current detection method includes: acquiring high-frequency mixed current signals output by each flexible high-frequency current transformer and power frequency mixed current signals output by each flexible power frequency current transformer; determining the high-frequency current component of the target cable based on each high-frequency mixed current signal and a first mathematical model, and using the high-frequency current component as the high-frequency fault current component of the target cable; determining the power frequency current component of the target cable based on each power frequency mixed current signal and a second mathematical model, the second mathematical model being constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable; and extracting the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable. This application utilizes multiple distinct cable subsets within a cable trench, each containing the same number of cables. Each subset is monitored by a flexible current transformer group. Specifically, flexible current transformers are grouped and wrapped around different cable bundles using a cross-over installation rule, eliminating the need for individual current transformers for each cable. This overcomes the physical space limitations imposed by tightly packed cables and submerged installations, enabling full coverage monitoring of all cables even in congested, submerged cable clusters, effectively improving cable fault detection coverage. Furthermore, mathematical modeling accurately derives the independent high-frequency and power-frequency current components of each cable from the mixed current signals measured by each group of flexible current transformers. This achieves signal decoupling and source tracing in environments with strong electromagnetic coupling across multiple cables, providing effective data support for cable condition assessment, early fault warning, and precise fault location. This meets the urgent need for comprehensive condition perception and accurate fault diagnosis in high-reliability distribution networks, ensuring the safe operation of the distribution network. Attached Figure Description

[0047] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0048] Figure 1 A schematic diagram illustrating a scenario for the cable fault current detection method provided in this application embodiment;

[0049] Figure 2 A flowchart illustrating the cable fault current detection method provided in this application embodiment. Figure 1 ;

[0050] Figure 3 A flowchart illustrating the cable fault current detection method provided in this application embodiment. Figure 2 ;

[0051] Figure 4 A schematic diagram showing the correspondence between flexible current transformer groups and cable bundles provided in an embodiment of this application;

[0052] Figure 5 This is a schematic diagram of the cable fault current detection device provided in the embodiments of this application;

[0053] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0054] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concepts of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0055] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0056] The terms “first,” “second,” etc., used in the specification and claims of this application 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 this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, 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, products, or apparatus.

[0057] It should be noted that the user information (including but not limited to user device information, user personal information, etc.) and data (including but not limited to data used for analysis, data stored, data displayed, etc.) involved in this application are all information and data authorized by the user or fully authorized by all parties. Furthermore, the collection, use and processing of the relevant data must comply with relevant laws, regulations and standards, and corresponding operation entry points are provided for users to choose to authorize or refuse.

[0058] With the increasing density of urban electricity loads, but limited urban power transmission channel resources, distribution network cables are currently mostly laid in clusters to make full use of urban power transmission channels. However, the excessive number of cables in the cable channels and the poor heat dissipation environment within the trenches lead to high temperatures within the distribution network cable trenches. This causes the supports for the distribution network cables to age and break rapidly, eventually resulting in clustered cables sinking to the bottom of the trench. This clustered sinking exacerbates the problem of poor heat dissipation within the cable trenches, leading to frequent thermal defects in the distribution network cables and ultimately causing cable breakdown accidents.

[0059] The copper tape shielding of the distribution network cable body, and the copper mesh and braided tape of the cable joints, ensure that the ground fault current can flow back to the system side and trigger zero-sequence protection measures when a ground fault occurs at the cable joint. If the copper mesh and braided tape of the cable joint are broken, the ground fault current passing through the copper tape shielding of the cable body will not be able to be conducted back to the system side, and the zero-sequence protection tripping measures in the relay protection system will not be activated. However, the laying environment of distribution network cables is generally humid, and there is a high risk of severe corrosion of the copper mesh and braided tape at the joints. Furthermore, distribution network cables are generally equipped with reclosing systems, and the inrush current during reclosing can easily cause the copper mesh and braided tape to burn out, leading to insulation failure. Therefore, it is necessary to monitor distribution network cables online to prevent unreasonable tripping and closing actions from causing accidents to escalate.

[0060] The primary task in online monitoring of distribution network cable lines is to install sensors along the lines. For electrical signals, the most commonly used sensors are high-frequency current transformers and power-frequency current transformers. However, the issue of clustered, underground cable laying limits the installation location of current transformers, making it potentially impossible to install an individual current transformer for each cable. Therefore, limited by the physical structure and installation conditions of current transformers, the above-mentioned solutions cannot achieve independent, real-time detection of fault current for each cable in clustered, underground cable laying scenarios, affecting cable fault detection coverage and failing to meet the urgent needs of high-reliability distribution networks for comprehensive status perception and accurate fault diagnosis.

[0061] In addition, some solutions can only provide the total current information of a single cable, which cannot distinguish between the high-frequency and low-frequency components of the fault current. The signal analysis capability is insufficient, which limits the accuracy of fault location and type identification.

[0062] To address the aforementioned technical challenges, this application provides a cable fault current detection solution. Through the flexible installation of flexible current transformers and the joint processing of grouped data from multiple flexible current transformers, it achieves independent analysis of the fault current in each cable within a clustered, submerged cable installation. This concept, based on the physical characteristics of flexible current transformers (i.e., they can wrap around multiple cables) and mathematical modeling methods, overcomes the installation limitations and signal analysis bottlenecks of traditional rigid current transformers. Specifically, flexible current transformers can adapt to the physical space constraints of densely arranged cables. By grouping installations and jointly processing data from multiple flexible current transformers, combined with a high-frequency and power frequency signal separation algorithm, it achieves independent extraction of the high-frequency and low-frequency components of the fault current in each cable, thereby improving the accuracy of fault location and type identification.

[0063] Next, we will first introduce the application scenarios of this application.

[0064] This application is particularly applicable to fault current monitoring in urban power distribution networks where cables are laid underground in clusters. It monitors the fault current of each cable in real time (where the high-frequency fault current component corresponds to partial discharge or grounding fault, and the power frequency fault current component corresponds to overload or insulation failure), and distinguishes the cable fault type to trigger targeted protection measures.

[0065] For example, Figure 1 This is a schematic diagram of a scenario for the cable fault current detection method provided in the embodiments of this application, such as... Figure 1 As shown, this application scenario includes a central processing unit 11 (i.e., an electronic device 11 that performs the cable fault current detection method), one or more data acquisition units 12, and multiple flexible current transformer groups 13 deployed in the cable trench. Each group of flexible current transformers is installed on a different cable bundle (i.e., a cable subset). The signal output terminal of each group of flexible current transformers is connected to the nearby deployed data acquisition unit 12 through a shielded signal cable. The data acquisition unit 12 is responsible for synchronously and at high speed acquiring the analog signals of all the flexible current transformers it is connected to. Through industrial fiber optic ring networks, Ethernet, or wireless communication networks (such as 5G private networks, LoRa), the massive real-time data is aggregated to the central processing unit 11 in the power distribution station or dispatch center. The cable fault current detection method deployed on the central processing unit 11 performs high-speed calculation on the mixed current signals from all data acquisition units 12 to separate the high-frequency fault current component and the power frequency fault current component of each cable. Furthermore, the central processing unit 11 can also identify the current health status of each cable through the built-in fault diagnosis module, and provide early warning of potential partial discharge activities or grounding fault risks. Finally, it can provide real-time feedback to power grid operation and maintenance personnel through graphical human-machine interface or mobile terminal push, so as to guide them to carry out precise inspections or preventive maintenance.

[0066] It should be noted that there can be multiple data acquisition units 12, and their deployment follows the principle of proximity access to optimize cabling and reduce interference in long-distance analog signal transmission. Each data acquisition unit 12 can access the signals of one or more flexible current transformer groups 13. The data acquisition unit 12 can be an embedded industrial control module, intelligent acquisition terminal, or dedicated data concentrator with multi-channel synchronous sampling function. The central processing unit 11 can be a server with a certain computing power, an industrial control computer, a server cluster, a high-performance workstation, or a desktop computer. This application embodiment does not limit the specific number, physical form, or product form of the data acquisition units 12 and the central processing unit 11.

[0067] The technical solution of this application and how the technical solution of this application solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments. The embodiments of this application will now be described with reference to the accompanying drawings.

[0068] Before describing the cable fault current detection method according to the embodiments of this application, the installation method of the current transformer in the cable trench will be described first.

[0069] The cable trench contains multiple distinct cable subsets, each containing the same number of cables. Each cable subset is monitored by a flexible current transformer group. The number of flexible current transformer groups is equal to the total number of cables in the cable trench. The flexible current transformer groups include flexible high-frequency current transformers and flexible power frequency current transformers.

[0070] In other words, multiple flexible current transformer groups are installed in the cable trench. These flexible current transformer groups are installed on the cable bundles in a cross-over manner, so that the cable bundles surrounded by each flexible current transformer group are different, and the number of cables in each cable bundle is the same and less than the total number of cables in the cable trench.

[0071] The cross-over method ensures that the subset of cables (cable bundles) monitored by each flexible current transformer group is unique. This means that for any two different groups, at least one cable in the cable bundles they enclose is different. Assuming the total number of cables in the cable trench is n, this method allows a finite number of n flexible current transformer groups to obtain n different perspectives on n cables, maximizing the information acquisition capabilities of sensing resources. Furthermore, the independent current signal of each cable can be uniquely retrieved, which is a prerequisite for achieving "single cable separation".

[0072] The number of cables in each cable bundle is the same, enabling all flexible current transformers to operate in similar electromagnetic coupling environments and load conditions, which is conducive to unifying their transformation coefficients (turn ratios) and reducing measurement errors caused by installation differences.

[0073] Within each group of flexible current transformers, the flexible high-frequency current transformer and the flexible power-frequency current transformer are physically adjacent or integrated in design to ensure that both sense exactly the same cable bundle.

[0074] The flexible high-frequency current transformer is used to capture nanosecond-microsecond pulse currents such as partial discharges and is an early warning sensor for cable insulation defects; the flexible power-frequency current transformer is used to monitor steady-state or slowly varying faults such as ground fault currents and load unbalanced currents.

[0075] Exemplarily, prepare n flexible high-frequency current transformers of the same specification and n flexible power-frequency current transformers of the same specification according to the number of cables in the cable trench, and determine the maximum number of cables that the current transformer can monitor (i.e., physically surround) according to the environmental conditions. , generally, < n. Pair up all the flexible high-frequency current transformers and flexible power-frequency current transformers one by one to form n groups of flexible current transformers. Install each group of flexible current transformers into the cables in the cable trench and ensure that the number of cables surrounded by each group of flexible current transformers is , and at least one cable surrounded by each group of flexible current transformers is different.

[0076] Next, the cable fault current detection method of the embodiment of the present application will be described through Figure 2 the following.

[0077] Figure 2 is a schematic flow of the cable fault current detection method provided by the embodiment of the present application Figure 1 , as Figure 2 shown, the cable fault current detection method includes:

[0078] S201, Obtain the high-frequency mixed current signals output by each flexible high-frequency current transformer and the power-frequency mixed current signals output by each flexible power-frequency current transformer.

[0079] Among them, the high-frequency mixed current signal is the time-domain waveform measured by each flexible high-frequency current transformer. This high-frequency mixed current signal is the vector sum generated after the high-frequency current components (such as partial discharge pulses, switching operation transients, etc.) in all cable conductors within the cable bundle surrounded by the flexible high-frequency current transformer are coupled to its shielding layer or grounding wire through electromagnetic induction. This high-frequency mixed current signal is mixed and unseparated original measurement data.

[0080] The power frequency hybrid current signal is the effective value or waveform of the current measured by each flexible power frequency current transformer. This power frequency hybrid current signal is the vector sum of the currents generated by the power frequency components (such as the 50Hz fundamental wave, 60Hz fundamental wave, and major low-order harmonics) of all cables within the cable bundle surrounded by the flexible power frequency current transformer on the common grounding path of the flexible power frequency current transformer.

[0081] For example, the central processing unit 11 sends a global synchronization sampling trigger signal to all data acquisition units 12 to ensure that all flexible high-frequency current transformers and flexible power frequency current transformers start acquiring data at the same time. Each data acquisition unit 12 adds a timestamp to the raw waveform data acquired within a time window (e.g., one power frequency cycle or 10ms data containing multiple pulses) and uploads it to the central processing unit 11 via the communication network. The central processing unit 11 aligns the data packets from different data acquisition units that belong to the same sampling time according to the timestamp, forming a complete, time-synchronized n-dimensional high-frequency mixed signal vector and an n-dimensional power frequency mixed signal vector.

[0082] S202. Based on each high-frequency mixed current signal and the first mathematical model, determine the high-frequency current component of the target cable, and use the high-frequency current component as the high-frequency fault current component of the target cable. The first mathematical model is constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable.

[0083] Among them, the high-frequency current component is an independent current signal belonging to a single cable, which is calculated from the mixed signal through a mathematical model and represents the cable's own transient insulation activities such as partial discharge.

[0084] The first mathematical model is a mathematical abstraction of the physical relationships formed by cross-coverage installations. This first mathematical model establishes a mapping relationship between n high-frequency mixed current signals (known observations) and the high-frequency current components of each of the n cables (unknown quantities to be determined).

[0085] For example, the central processing unit 11 inputs the acquired n-dimensional high-frequency mixed signal vector into the constructed first mathematical model. The first mathematical model processes and transforms the input signal according to its preset operational rules, ultimately outputting an n-dimensional solution vector. Each element in the n-dimensional solution vector corresponds to an independent high-frequency current component of a cable. The n-dimensional solution vector contains the independent high-frequency current components of the target cable.

[0086] Since the high-frequency components of the normal operating current are extremely weak and can be ignored, the calculated high-frequency current components are almost entirely generated by the transient processes of insulation defect faults such as partial discharge, and can therefore be directly regarded as high-frequency fault current components.

[0087] S203. Based on the mixed power frequency current signals and the second mathematical model, determine the power frequency current component of the target cable. The second mathematical model is constructed based on the coverage relationship between the flexible power frequency current transformer and each cable.

[0088] Among them, the power frequency current component is an independent current signal belonging to a single cable, which is calculated from the mixed signal through a mathematical model, and represents the power frequency fault current (such as single-phase ground fault current) in the cable grounding system.

[0089] This step is symmetrical to the S202 principle and aims to achieve signal decoupling in the power frequency band. The second mathematical model is also based on the cross-coverage installation relationship, but its parameters may differ from the first mathematical model due to the sensor type (power frequency current transformer) and frequency band characteristics.

[0090] For example, the central processing unit 11 inputs an n-dimensional power frequency mixed signal vector into the second mathematical model. Through the corresponding operations embedded in the second mathematical model, it reverse-calculates the independent power frequency current component of each cable, thus outputting an n-dimensional solution vector, where each element corresponds to an independent power frequency current component of a cable. The n-dimensional solution vector contains the independent power frequency current component of the target cable. This power frequency current component is the sum of all power frequency currents flowing in the cable grounding wire.

[0091] S204. Extract the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable.

[0092] This step involves removing the inherent unbalanced current under normal operating conditions from the total power frequency current component of the target cable, thereby obtaining the portion of the power frequency current purely generated by faults (such as ground faults). Essentially, it distinguishes between the "background current" that characterizes normal operation and the "abnormal incremental current" that characterizes faults.

[0093] For example, the central processing unit 11 acquires reference information reflecting the power frequency grounding current that should exist in the target cable under normal operating conditions without faults. Subsequently, according to the set calculation rules, the reference information is processed together with the actual power frequency current component calculated by S203, and the output result is the power frequency current caused purely by the fault after stripping the normal background, that is, the power frequency fault current component.

[0094] In one implementation, a direct differential method is used, for example, by subtracting a calculated or learned normal state reference current (i.e., reference information) from the measured power frequency current component to obtain the power frequency fault current component of the target cable.

[0095] Another implementation method uses the model residual method. For example, a normal state model of a cable grounding system is established, the power frequency current component is input into the model, and the model output (predicted normal current) is compared with the power frequency current component. The residual is the power frequency fault current component.

[0096] In another implementation, a feature stripping method is used, for example, in the frequency domain or time-frequency domain, to filter out the current characteristics that characterize normal operation (such as specific harmonic components and fluctuation modes) from the power frequency current component, and the remaining components are regarded as the power frequency fault current component.

[0097] This application employs flexible current transformers, which are grouped and wrapped around different cable bundles using a cross-over installation rule. This eliminates the need for individual current transformers for each cable, overcoming the physical space limitations imposed by tightly packed cables and recessed installations. This allows for full coverage monitoring of all cables even in congested, clustered, recessed installation scenarios, effectively improving cable fault detection coverage. Furthermore, through mathematical modeling, the independent high-frequency and power-frequency current components of each cable are accurately derived from the mixed current signals measured by each group of flexible current transformers. This enables signal decoupling and source tracing in environments with strong electromagnetic coupling across multiple cables, providing effective data support for cable condition assessment, early fault warning, and precise fault location. This meets the urgent needs of high-reliability distribution networks for comprehensive condition perception and accurate fault diagnosis, ensuring the safe operation of the distribution network.

[0098] In some embodiments, the first mathematical model is a first set of linear equations with the high-frequency current components of each cable as unknowns. Based on each high-frequency mixed current signal and the first mathematical model, determining the high-frequency current components of the target cable includes: inputting each high-frequency mixed current signal into the first set of linear equations, and obtaining the high-frequency current components of the target cable by solving the first set of linear equations; wherein, in the first set of linear equations, the first... The equation represents the first... The high-frequency hybrid current signal output by the flexible high-frequency current transformer is equal to the first... The sum of the high-frequency current components of each cable within the subset of cables monitored by each flexible high-frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0099] Understandably, the first system of linear equations can be expressed as: In this system, Y_H is a vector composed of various high-frequency mixed current signals, A_H is the first coefficient matrix constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable, and X_H is a vector composed of the high-frequency current components of each cable to be determined. Solving the first linear equation system yields the high-frequency current component X_H. The installation rules that "the cable subsets monitored by each flexible current transformer group are different" and "the number of cables in each cable subset is the same" ensure that the first coefficient matrix has good mathematical properties (such as full rank), thus guaranteeing that the first linear equation system has a unique and stable solution.

[0100] For example, based on the pre-entered cross-coverage installation configuration table of the system, the coefficient matrix A_H (i.e., the high-frequency correlation matrix) of the first mathematical model is generated. For instance, if the system has... Root cables (C1, C2, C3, ..., Cn) and A group of flexible current transformers, with a maximum number of cables that can be enclosed. for If group 1 encloses {C2,C3,……,Cn}, then the first row of matrix A_H is [0,1,1,……,1].

[0101] Establish a system of linear equations Where X_H is the variable to be determined, which is composed of the high-frequency current components of each cable. The column vector consists of Y_H, which is a high-frequency mixed current signal. The column vector formed by these.

[0102] The first system of linear equations can be expressed as:

[0103]

[0104] Solving this system of equations, for example, by using any one of the least squares method, direct matrix inversion method, or iterative method, directly yields the solution vector X_H.

[0105] In this embodiment, by transforming physical installation constraints into a solvable system of linear equations, the independent high-frequency current components of each cable are accurately extracted from the mixed signal in engineering, providing a precise data foundation for subsequent cable insulation status assessment and fault early warning.

[0106] In some embodiments, the second mathematical model is a set of second linear equations with the power frequency current components of each cable as unknowns. Based on the mixed power frequency current signals and the second mathematical model, determining the power frequency current components of the target cable includes: inputting the mixed power frequency current signals into the second linear equation set, and obtaining the power frequency current components of the target cable by solving the second linear equation set; wherein, in the second linear equation set, the first... The equation represents the first... The power frequency hybrid current signal output by the flexible power frequency current transformer is equal to the first... The sum of the power frequency current components of each cable within the subset of cables monitored by each flexible power frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0107] Understandably, the second system of linear equations can be expressed as: In this system, Y_L is a vector composed of various mixed power frequency current signals, A_L is a second coefficient matrix constructed based on the coverage relationship between the flexible power frequency current transformer and each cable, and X_L is a vector composed of the power frequency current components of each cable to be determined. Solving the second linear equation system yields the power frequency current component X_L. The installation rules that "the cable subsets monitored by each flexible current transformer group are different" and "the number of cables in each cable subset is the same" ensure that the second coefficient matrix has good mathematical properties (such as full rank), thus guaranteeing that the second linear equation system has a unique and stable solution.

[0108] For example, based on the pre-entered cross-coverage installation configuration table of the system, the coefficient matrix A_L (i.e., the power frequency correlation matrix) of the second mathematical model is generated. For instance, if the system has... Root cables (C1, C2, C3, ..., Cn) and A group of flexible current transformers, with a maximum number of cables that can be enclosed. for If group 1 encloses {C2,C3,……,Cn}, then the first row of matrix A_L is [0,1,1,……,1].

[0109] Establish a system of linear equations Where X_L is the variable to be determined, which is composed of the power frequency current components of each cable. The column vector consists of Y_L, which is the power frequency mixed current signal. The column vector formed by these.

[0110] The second system of linear equations can be expressed as:

[0111]

[0112] Solving this system of equations, for example, by using any one of the least squares method, direct matrix inversion method, or iterative method, directly yields the solution vector X_L.

[0113] In this embodiment, by transforming physical installation constraints into a solvable system of linear equations, the independent power frequency current component of each cable is accurately derived from the mixed signal in engineering, providing a precise data foundation for subsequent cable insulation status assessment and fault early warning.

[0114] In some embodiments, fault component extraction is performed on the power frequency current component to obtain the power frequency fault current component of the target cable, including:

[0115] S2041. Obtain the three-phase load current of the target cable.

[0116] Among them, the three-phase load current is the normal operating current passing through the three-phase conductors (phase A, phase B, and phase C) of the cable.

[0117] For example, the central processing unit reads the instantaneous values ​​of the three-phase current at the same moment from the switchgear protection device or energy meter connected to the target cable via the station's communication network. (t), (t), (t), or obtain its effective value and phase angle within one cycle. Time alignment is performed on the read current data. Since there may be millisecond-level time differences between different systems, the three-phase current data and the power frequency current component calculated by S203 need to be aligned to the same time segment according to the timestamp.

[0118] S2042. Calculate the three-phase unbalanced current of the target cable based on the three-phase load current.

[0119] In this step, the three-phase unbalanced current is the power frequency current induced in the cable shield or grounding wire under normal operating and fault-free conditions, due to factors such as asymmetrical geometric arrangement of the three-phase conductors and incomplete load balance. The theoretical value of the three-phase unbalanced current is equal to the vector sum of the three-phase load currents and is the inherent background noise of the cable.

[0120] For example, the three-phase unbalanced current of the target cable .

[0121] S2043. The difference between the power frequency current component and the three-phase unbalanced current is determined as the power frequency fault current component of the target cable.

[0122] For example, the power frequency fault current component of the target cable , The power frequency current component of the target cable.

[0123] In this embodiment, a real-time three-phase unbalanced current compensation mechanism is introduced to remove the inherent background current generated by normal load asymmetry from the calculated power frequency current component, thereby effectively eliminating its submerging interference in fault current feature extraction. This improves the detection signal-to-noise ratio of the power frequency fault current component and the detection sensitivity of high-impedance grounding faults, helping to accurately capture and warn of early weak grounding faults.

[0124] In some embodiments, the cable fault current detection method further includes: determining the fault state of the target cable based on the power frequency fault current component and / or the high frequency fault current component.

[0125] The fault status includes not only the binary judgment of normal and fault, but also: fault type (such as partial discharge, high resistance grounding, metallic grounding), severity level (such as minor, attention, abnormal, severe), development trend (stable, increasing, sudden), risk category (immediate power outage, planned maintenance, continuous monitoring), etc.

[0126] For example, power frequency features can be extracted based on the power frequency fault current component, such as for M consecutive power frequency cycles (e.g., M=100, corresponding to 2 seconds). Sequence, calculate effective values Peak Duration (i.e., effective value) (Percentage of time exceeding the threshold) and phase angle (Phase difference relative to phase A voltage). High-frequency characteristics are extracted based on high-frequency fault current components, focusing on high-frequency fault current components within the same time period. Perform time-frequency analysis, extract all pulses, and count the maximum pulse amplitude. Average pulse amplitude Pulse repetition rate Generate a phase distribution spectrum and count the number of pulses and average amplitude in each power frequency phase interval (e.g., 1° interval).

[0127] Then, based on preset judgment rules, the fault status of the target cable is determined.

[0128] For example, the determination of power frequency grounding faults includes the following rules: For example, the determination of metallic grounding faults includes the following rules: If > 50A and >95%, phase If the voltage phase of a phase is close to that of another phase (e.g., within ±15°), it is determined to be a metallic ground fault in that phase, classified as severe, and immediate power outage is recommended. For high-resistance ground fault determination, the corresponding rules include: if 10A < ≤ 50A, and >80%, with obvious phase characteristics, indicating a high-resistance grounding fault, classified as abnormal, and scheduled maintenance is recommended. For intermittent grounding fault determination, the corresponding rules include: if 2A < ≤10A, and 30% < If the grounding rate is ≤80%, it is considered intermittent grounding, with a severity level of "caution," and it is recommended to strengthen monitoring.

[0129] For example, the determination of partial discharge faults includes the following rules: For instance, for the determination of severe partial discharge, the corresponding rules include: if >1000pC and A partial discharge exceeding 100 pps, with a phase distribution spectrum exhibiting typical internal / external discharge characteristics, is classified as severe partial discharge, with a severity level of abnormal. Prompt repair is recommended. For moderate partial discharge assessment, the corresponding rules include: if 200 pC < ≤1000pC, Moderate discharge is classified as moderate, with a severity level of "caution." For weak discharges or noise, the corresponding rules include: if... If the discharge rate is ≤200pC and there are no typical phase characteristics, it is determined to be environmental noise or weak discharge, with a severity level of slight. Continuous monitoring is recommended.

[0130] Furthermore, time-series correlation analysis can be performed on power frequency faults and high-frequency faults. For example, if high-frequency discharge activity ( ) occurs several hours to several days before a power frequency ground fault, , If the signal shows a significant increasing trend, it is judged to be a process of insulation deterioration leading to breakdown. Based on the above criteria, a unified fault status report is generated, with a format such as: Cable ID: C-10kV-003, Time: 2023-10-27 14:30:00, Overall Status: Abnormal, Fault Type: Phase B high resistance grounding (20.5A, =-125°) with moderate partial discharge ( =650pC), recommended action: arrange a power outage for maintenance within 72 hours, confidence level: 92%.

[0131] Optionally, warnings can be issued through methods such as color-changing monitoring system interfaces (e.g., green, yellow, orange, red), audible and visual alarms, and SMS push notifications. The location of the faulty cable can also be highlighted on a GIS map or cable trench profile, with key characteristic parameters displayed in a floating position.

[0132] This application's embodiments achieve deep intelligent diagnosis of cable insulation status by simultaneously analyzing power frequency fault current components and high-frequency fault current components. It can not only accurately identify serious defects such as grounding faults, but also detect early hidden dangers such as partial discharge, transforming the operation and maintenance mode from reactive post-event repairs to proactive pre-event warnings. This significantly improves the comprehensiveness and timeliness of fault detection, providing core data support for building a highly reliable intelligent distribution network.

[0133] In some embodiments, when determining the high-frequency current component and the power frequency current component of the target cable, the method further includes: acquiring environmental parameters within the cable trench, including temperature and humidity; and dynamically correcting the high-frequency current component and / or the power frequency current component based on the environmental parameters.

[0134] Temperature directly affects the resistivity (positive temperature coefficient) of the cable's metallic conductor and the dielectric properties of the insulation material. Humidity mainly affects the surface conductivity of cable accessories and defects.

[0135] In other words, environmental parameters directly affect the resistance characteristics of cables and the measurement accuracy of flexible current transformers. For example, in high-temperature environments, increased cable resistance may cause the measured value of the power frequency current transformer to deviate from the true value; in humid environments, corrosion of cable joints may cause high-frequency signal attenuation.

[0136] For example, a network of temperature and humidity sensors can be deployed at key locations in the cable trench to collect average temperature and relative humidity data within the trench at 1-minute intervals. A unified time stamp can be established to strictly align environmental parameters with current sampling data, ensuring the synchronization of cross-sectional data at the same time.

[0137] For example, based on the temperature compensation model, the first compensation amount of the power frequency current component is calculated. The temperature compensation model is, for example: ,in, , The reference temperature is 20℃. The power frequency current component is calculated using the second mathematical model. This refers to the actual ambient temperature. This refers to the temperature coefficient of resistance. The power frequency current component after temperature compensation. = - .

[0138] For example, based on a humidity compensation model, the second compensation amount for the power frequency current component is calculated. The humidity compensation model is, for example, as follows: ,in and The coefficients are those calibrated through experiments. This is the phase voltage. The power frequency current component after humidity compensation. = - .

[0139] The dynamic correction of high-frequency current components based on environmental parameters may include the following steps: performing a first compensation on the time-domain waveform of the high-frequency current component based on humidity to obtain a humidity-compensated waveform; identifying partial discharge pulses from the humidity-compensated waveform and extracting their amplitude and waveform features; normalizing the amplitude features based on temperature to obtain a normalized discharge amplitude; and reconstructing the standardized high-frequency current component waveform under standard environmental parameters based on the normalized discharge amplitude and waveform features, as the corrected high-frequency current component.

[0140] For example, the high-frequency current component calculated by the first numerical sequence model. Humidity compensation is performed to obtain the humidity-compensated high-frequency current component. For example, based on the current humidity, the humidity attenuation compensation factor corresponding to the current humidity is obtained by looking up a pre-calibrated mapping table of humidity-humidity attenuation compensation factors and combining it with linear interpolation. Then, a humidity attenuation compensation factor is applied to compensate the time-domain waveform of the high-frequency current component. .

[0141] It should be noted that the mapping table of humidity and humidity attenuation compensation factor can be obtained in the following way: In the laboratory, the ambient humidity is controlled. At multiple humidity levels (e.g., 30%, 50%, 70%, 85%, 95%), a high-frequency calibration pulse of known amplitude is injected into the same cable (or using a stable intrinsically discharged power source). At each humidity point, the response amplitude of the calibration pulse is measured and recorded. With a certain dry reference point (e.g.) =30% amplitude Based on this, calculate the compensation factor for each humidity point: This forms a mapping table of humidity and humidity attenuation compensation factors.

[0142] Furthermore, from the humidity-compensated high-frequency current component All pulses were detected, and a complete set of features was extracted from each pulse, including the high-frequency pulse amplitude and waveform features (which can carry information such as pulse shape and oscillation). Assuming the high-frequency pulse amplitude is... Applying temperature normalization to the amplitude of each high-frequency pulse, we obtain... Normalization satisfies the following: .in, This is a coefficient representing the current temperature range, a calibration coefficient characterizing the rate of change of discharge quantity with temperature. This can be pre-calibrated experimentally. For example, in a temperature-controlled laboratory, standard defects (such as internal air gaps) are created on samples of the same type of cable. At multiple stable temperature points (such as 10℃, 20℃, 30℃, 40℃, 50℃), the discharge quantity Q is measured using a standard partial discharge calibrator, and a discharge quantity-temperature curve is fitted. The slope of this curve is the discharge quantity-temperature curve. ; The reference temperature is 20℃. This refers to the actual ambient temperature. This is the normalized discharge amplitude after temperature compensation. Then, the high-frequency current component is reconstructed in reverse based on the normalized discharge amplitude after temperature compensation to obtain the high-frequency current component after environmental parameter correction.

[0143] In this embodiment, by introducing a dynamic sensing and compensation mechanism, environmental parameters within the cable trench are sensed in real time, and the high-frequency current component and / or power frequency current component are dynamically compensated. This makes the calculated high-frequency current component and / or power frequency current component closer to the true value under standard operating conditions, eliminates systematic errors introduced by environmental changes, ensures the reliability of monitoring data, and adapts to the fault current analysis requirements under complex environments.

[0144] In some embodiments, the dynamic correction of the high-frequency current component and / or the power frequency current component based on environmental parameters can also be achieved by inputting the environmental parameters, the high-frequency mixed current signal, and the power frequency mixed current signal into a trained neural network model, and then using the neural network model to predict the corrected high-frequency current component and / or the power frequency current component.

[0145] The trained neural network model can be obtained in the following way: In the cable trench, under various combinations of environmental parameters, high-frequency mixed current signals and power frequency mixed current signals are collected, and the real high-frequency current components and power frequency current components of each cable are measured or calibrated simultaneously to form a training sample set; using environmental parameters, high-frequency mixed current signals and power frequency mixed current signals as input features, and the real high-frequency current components and power frequency current components as training targets, the neural network model is supervised and trained to obtain the trained neural network model.

[0146] For example, environmental parameters, high-frequency mixed current signals, and power frequency mixed current signals are input into a trained neural network model. This neural network model is based on the learned complex mapping relationship from multi-sensor mixed observation data to the real current component of a single cable, as well as the systematic influence of environmental parameters on this mapping relationship. Through its internal multi-layer nonlinear transformation and feature decoupling mechanism, it outputs the corrected high-frequency current component and / or power frequency current component.

[0147] In this embodiment, a neural network model is used to directly learn from and eliminate environmental interference from mixed signals, achieving integrated intelligent processing of environmental compensation and signal separation. Compared with traditional step-by-step methods, it eliminates the need for manual derivation of complex compensation formulas, and can adaptively fit the nonlinear coupling relationship between temperature and humidity and the measurement system, significantly improving correction accuracy and system robustness. In particular, it can maintain stable and reliable single-cable current monitoring capabilities even in extreme or rapidly changing environments.

[0148] Based on the above embodiments, combined with Figure 3 The cable fault current detection method of this application is described in detail. In this embodiment, an example of five cables existing in a cable trench is used for illustrative purposes.

[0149] For example, five flexible high-frequency current transformers and five flexible power frequency current transformers of the same specifications are installed in the cable trench. All the flexible high-frequency current transformers and flexible power frequency current transformers are paired one by one to form five sets of flexible high-frequency current transformer-flexible power frequency current transformer pairs. Each set of flexible high-frequency current transformer-flexible power frequency current transformer pairs monitors two cables.

[0150] Figure 4 The diagram illustrates the correspondence between flexible current transformer groups and cable bundles provided in this application embodiment. Figure 4 As shown, the first group of flexible current transformers monitors cables 1 and 2 (i.e., the cable bundle corresponding to the first group of flexible current transformers contains cables 1 and 2); the second group of flexible current transformers monitors cables 2 and 3 (i.e., the cable bundle corresponding to the second group of flexible current transformers contains cables 2 and 3); the third group of flexible current transformers monitors cables 3 and 4 (i.e., the cable bundle corresponding to the third group of flexible current transformers contains cables 3 and 4); the fourth group of flexible current transformers monitors cables 4 and 5 (i.e., the cable bundle corresponding to the fourth group of flexible current transformers contains cables 4 and 5); and the fifth group of flexible current transformers monitors cables 5 and 1 (i.e., the cable bundle corresponding to the fifth group of flexible current transformers contains cables 5 and 1).

[0151] Figure 3 A flowchart illustrating the cable fault current detection method provided in this application embodiment. Figure 2 ,like Figure 3 As shown, the cable fault current detection method includes:

[0152] S301. Obtain the high-frequency mixed current signal output by each flexible high-frequency current transformer and the power frequency mixed current signal output by each flexible power frequency current transformer.

[0153] For details, please refer to step S201, which will not be repeated here.

[0154] For example, high-frequency mixed current signals Power frequency mixed current signal .

[0155] S302. Input each high-frequency mixed current signal into the first linear equation set, and obtain the high-frequency current component of the target cable by solving the first linear equation set.

[0156] For example, the first system of linear equations can be expressed as:

[0157]

[0158] High-frequency mixed current signal Substituting into the first system of linear equations above, solve for the high-frequency current components of each cable. .

[0159] S303. The high-frequency current component of the target cable is determined as the high-frequency fault current component of the target cable.

[0160] S304. Input each power frequency mixed current signal into the second linear equation set, and obtain the power frequency current component of the target cable by solving the second linear equation set.

[0161] For example, the second system of linear equations can be expressed as:

[0162]

[0163] mixed power frequency current signal Substituting into the second system of linear equations above, solve for the power frequency current components of each cable. .

[0164] S305. Extract the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable.

[0165] For example, obtain the three-phase load current of the target cable, and calculate the three-phase unbalanced current of the target cable based on the three-phase load current. The difference between the power frequency current component and the three-phase unbalanced current is determined as the power frequency fault current component of the target cable. , The power frequency current component of the target cable.

[0166] S306. Determine the fault state of the target cable based on the power frequency fault current component and / or high frequency fault current component.

[0167] For example, the determination of power frequency grounding faults includes the following rules: For example, the determination of metallic grounding faults includes the following rules: If > 50A and >95%, phase If the voltage phase of a phase is close to that of another phase (e.g., within ±15°), it is determined to be a metallic ground fault in that phase, classified as severe, and immediate power outage is recommended. For high-resistance ground fault determination, the corresponding rules include: if 10A < ≤ 50A, and >80%, with obvious phase characteristics, indicating a high-resistance grounding fault, classified as abnormal, and scheduled maintenance is recommended. For intermittent grounding fault determination, the corresponding rules include: if 2A < ≤10A, and 30% < If the grounding rate is ≤80%, it is considered intermittent grounding, with a severity level of "caution," and it is recommended to strengthen monitoring.

[0168] For example, the determination of partial discharge faults includes the following rules: For instance, for the determination of severe partial discharge, the corresponding rules include: if >1000pC and A partial discharge exceeding 100 pps, with a phase distribution spectrum exhibiting typical internal / external discharge characteristics, is classified as severe partial discharge, with a severity level of abnormal. Prompt repair is recommended. For moderate partial discharge assessment, the corresponding rules include: if 200 pC < ≤1000pC, Moderate discharge is classified as moderate, with a severity level of "caution." For weak discharges or noise, the corresponding rules include: if... If the discharge rate is ≤200pC and there are no typical phase characteristics, it is determined to be environmental noise or weak discharge, with a severity level of slight. Continuous monitoring is recommended.

[0169] Furthermore, time-series correlation analysis can be performed on power frequency faults and high-frequency faults. For example, if high-frequency discharge activity ( ) occurs several hours to several days before a power frequency ground fault, , If the signal shows a significant increasing trend, it is judged to be a process of insulation deterioration leading to breakdown. Based on the above criteria, a unified fault status report is generated, with a format such as: Cable ID: C-10kV-003, Time: 2023-10-27 14:30:00, Overall Status: Abnormal, Fault Type: Phase B high resistance grounding (20.5A, =-125°) with moderate partial discharge ( =650pC), recommended action: arrange a power outage for maintenance within 72 hours, confidence level: 92%.

[0170] In summary, this application has at least the following advantages:

[0171] I. Flexible current transformers are employed, grouped and wrapped around different cable bundles using a cross-over installation rule. This eliminates the need for individual current transformers for each cable, overcoming the physical space limitations imposed by tightly packed cables and recessed installations. This allows for full coverage monitoring of all cables even in congested, clustered, recessed installation scenarios, effectively improving cable fault detection coverage. Furthermore, mathematical modeling accurately extracts the independent high-frequency and power-frequency current components of each cable from the mixed current signals measured by each group of flexible current transformers. This enables signal decoupling and source tracing in environments with strong electromagnetic coupling across multiple cables, providing effective data support for cable condition assessment, early fault warning, and precise fault location. This meets the urgent needs of high-reliability distribution networks for comprehensive condition awareness and accurate fault diagnosis, ensuring the safe operation of the distribution network.

[0172] Second, by introducing a real-time three-phase unbalanced current compensation mechanism, the inherent background current generated by normal load asymmetry is removed from the calculated power frequency current component, thereby effectively eliminating its submerging interference on fault current feature extraction. This improves the detection signal-to-noise ratio of the power frequency fault current component and the detection sensitivity of high-impedance grounding faults, helping to accurately capture and warn of early weak grounding faults.

[0173] Third, by simultaneously analyzing the power frequency fault current components and high-frequency fault current components, a deep intelligent diagnosis of cable insulation status can be achieved. This not only accurately identifies serious defects such as grounding faults but also detects early-stage hazards such as partial discharge, transforming the operation and maintenance model from reactive post-event repairs to proactive pre-event warnings. This significantly improves the comprehensiveness and timeliness of fault detection, providing core data support for building a highly reliable smart distribution network.

[0174] Fourth, by introducing a dynamic sensing and compensation mechanism, the environmental parameters in the cable trench are sensed in real time, and the high-frequency current component and / or power frequency current component are dynamically compensated, so that the calculated high-frequency current component and / or power frequency current component are closer to the true value under standard operating conditions, eliminating the systematic error introduced by environmental changes, ensuring the reliability of monitoring data, and adapting to the fault current analysis needs in complex environments.

[0175] Figure 5 This is a schematic diagram of the cable fault current detection device provided in the embodiment of this application. There are multiple different cable subsets in the cable trench. Each cable subset contains the same number of cables. Each cable subset is monitored by a flexible current transformer group. The number of flexible current transformer groups is equal to the total number of cables in the cable trench. The flexible current transformer group includes flexible high-frequency current transformers and flexible power frequency current transformers.

[0176] like Figure 5 As shown, the cable fault current detection device 50 provided in this embodiment includes: an acquisition module 51, a first determination module 52, a second determination module 53, and a processing module 54. Wherein:

[0177] The acquisition module 51 is used to acquire the high-frequency mixed current signal output by each flexible high-frequency current transformer and the power frequency mixed current signal output by each flexible power frequency current transformer.

[0178] The first determining module 52 is used to determine the high-frequency current component of the target cable based on each high-frequency mixed current signal and the first mathematical model, and to use the high-frequency current component as the high-frequency fault current component of the target cable. The first mathematical model is constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable.

[0179] The second determining module 53 is used to determine the power frequency current component of the target cable based on each power frequency mixed current signal and the second mathematical model. The second mathematical model is constructed based on the coverage relationship between the flexible power frequency current transformer and each cable.

[0180] Processing module 54 is used to extract the fault component from the power frequency current component to obtain the power frequency fault current component of the target cable.

[0181] In one possible implementation, the first mathematical model is a first set of linear equations with the high-frequency current components of each cable as unknowns. The first determining module 52 is specifically used to: input each high-frequency mixed current signal into the first set of linear equations, and obtain the high-frequency current components of the target cable by solving the first set of linear equations; wherein, in the first set of linear equations, the first... The equation represents the first... The high-frequency hybrid current signal output by the flexible high-frequency current transformer is equal to the first... The sum of the high-frequency current components of each cable within the subset of cables monitored by each flexible high-frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0182] In one possible implementation, the second mathematical model is a second set of linear equations with the power frequency current components of each cable as unknowns. The second determining module 53 is specifically used to: input each power frequency mixed current signal into the second set of linear equations, and obtain the power frequency current components of the target cable by solving the second set of linear equations; wherein, in the second set of linear equations, the first... The equation represents the first... The power frequency hybrid current signal output by the flexible power frequency current transformer is equal to the first... The sum of the power frequency current components of each cable within the subset of cables monitored by each flexible power frequency current transformer. =1,2,……, , This represents the total number of cables in the cable trench.

[0183] In one possible implementation, the processing module 54 is specifically used to: acquire the three-phase load current of the target cable; calculate the three-phase unbalanced current of the target cable based on the three-phase load current; and determine the difference between the power frequency current component and the three-phase unbalanced current as the power frequency fault current component of the target cable.

[0184] In one possible implementation, the processing module 54 is further configured to: determine the fault state of the target cable based on the power frequency fault current component and / or the high frequency fault current component.

[0185] In one possible implementation, the processing module 54 is further configured to: acquire environmental parameters within the cable trench, including temperature and humidity; and dynamically correct the high-frequency current component and / or the power frequency current component based on the environmental parameters.

[0186] In one possible implementation, the processing module 54 is further configured to: input environmental parameters, high-frequency mixed current signal and power frequency mixed current signal into a trained neural network model, and predict the corrected high-frequency current component and / or power frequency current component through the neural network model.

[0187] The cable fault current detection device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and will not be described in detail here.

[0188] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 6 As shown, the electronic device 11 provided in this embodiment (i.e. Figure 1 The central processing unit 11 includes at least one processor 111 and a memory 112. Optionally, the electronic device 11 also includes a communication component 113. The processor 111, the memory 112, and the communication component 113 are connected via a bus 114.

[0189] In a specific implementation, at least one processor 111 executes computer execution instructions stored in memory 112, causing at least one processor 111 to perform the above-described method.

[0190] The specific implementation process of processor 111 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0191] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0192] The memory may include random access memory (RAM) and may also include non-volatile memory (NVM), such as at least one disk storage device.

[0193] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0194] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0195] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0196] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0197] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0198] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0199] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0200] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0201] If a function is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0202] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0203] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A method for detecting cable fault current, characterized in that, The cable trench contains multiple distinct cable subsets, each containing the same number of cables. Each cable subset is monitored by a flexible current transformer group, and the number of flexible current transformer groups is equal to the total number of cables in the cable trench. Each flexible current transformer group includes flexible high-frequency current transformers and flexible power frequency current transformers. The cable fault current detection method includes: The high-frequency mixed current signal output by each of the flexible high-frequency current transformers and the power frequency mixed current signal output by each of the flexible power frequency current transformers are obtained. Based on the high-frequency mixed current signals and the first mathematical model, the high-frequency current component of the target cable is determined, and the high-frequency current component is used as the high-frequency fault current component of the target cable. The first mathematical model is constructed based on the coverage relationship between the flexible high-frequency current transformer and each cable. Based on the aforementioned power frequency hybrid current signals and the second mathematical model, the power frequency current component of the target cable is determined. The second mathematical model is constructed based on the coverage relationship between the flexible power frequency current transformer and each cable. The power frequency current component is extracted to obtain the power frequency fault current component of the target cable.

2. The cable fault current detection method according to claim 1, characterized in that, The first mathematical model is a set of first linear equations with the high-frequency current components of each cable as unknowns. The step of determining the high-frequency current components of the target cable based on the high-frequency mixed current signals and the first mathematical model includes: Each of the high-frequency mixed current signals is input into the first linear equation set, and the high-frequency current component of the target cable is obtained by solving the first linear equation set. In the first system of linear equations, the first... The equation represents the first... The high-frequency hybrid current signal output by the flexible high-frequency current transformer is equal to the first... The sum of the high-frequency current components of each cable within the subset of cables monitored by each flexible high-frequency current transformer. =1,2,……, , The total number of cables in the cable trench.

3. The cable fault current detection method according to claim 1, characterized in that, The second mathematical model is a set of second linear equations with the power frequency current components of each cable as unknowns. The determination of the power frequency current components of the target cable based on the aforementioned power frequency mixed current signals and the second mathematical model includes: Each of the aforementioned power frequency mixed current signals is input into the second linear equation set, and the power frequency current component of the target cable is obtained by solving the second linear equation set; In the second system of linear equations, the first... The equation represents the first... The power frequency hybrid current signal output by the flexible power frequency current transformer is equal to the first... The sum of the power frequency current components of each cable within the subset of cables monitored by each flexible power frequency current transformer. =1,2,……, , The total number of cables in the cable trench.

4. The cable fault current detection method according to any one of claims 1 to 3, characterized in that, The step of extracting fault components from the power frequency current component to obtain the power frequency fault current component of the target cable includes: Obtain the three-phase load current of the target cable; Based on the three-phase load current, the three-phase unbalanced current of the target cable is calculated; The difference between the power frequency current component and the three-phase unbalanced current is determined as the power frequency fault current component of the target cable.

5. The cable fault current detection method according to any one of claims 1 to 3, characterized in that, Also includes: The fault state of the target cable is determined based on the power frequency fault current component and / or the high frequency fault current component.

6. The cable fault current detection method according to any one of claims 1 to 3, characterized in that, In determining the high-frequency current component and the power frequency current component of the target cable, the method further includes: The environmental parameters within the cable trench are obtained, including temperature and humidity. The high-frequency current component and / or the power frequency current component are dynamically corrected based on the environmental parameters.

7. The cable fault current detection method according to claim 6, characterized in that, The step of dynamically correcting the high-frequency current component and / or the power frequency current component based on the environmental parameters includes: The environmental parameters, the high-frequency mixed current signal, and the power frequency mixed current signal are input into a trained neural network model, and the neural network model is used to predict the corrected high-frequency current component and / or the power frequency current component.

8. An electronic device, characterized in that, include: Memory, processor; The memory stores computer-executed instructions; The processor executes computer execution instructions stored in the memory, causing the processor to perform the cable fault current detection method as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed, are used to implement the cable fault current detection method as described in any one of claims 1 to 7.

10. A computer program product, characterized in that, It includes a computer program, which, when executed, implements the cable fault current detection method according to any one of claims 1 to 7.

Images