Grounding fault location method using transient and steady state characteristics of pt cable grounding current

Abstract

The application relates to a grounding fault positioning method and device using PT cable grounding current transient and steady state characteristics, a server and a storage medium. The method comprises the following steps: acquiring a plurality of current setting values corresponding to a plurality of preset points in a power grid circuit; wherein the power grid circuit is a secondary loop circuit formed by connecting a PT cable and a plurality of secondary windings in a transformer substation; and determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point; wherein the branch parameters include cable parameters and capacitance parameters; determining whether a grounding fault exists in the power grid circuit based on the steady state characteristics corresponding to the plurality of current setting values and the transient state characteristics corresponding to the instantaneous current values of the preset points; wherein the grounding fault is used to represent that there is an abnormally connected cable point to the ground in the power grid circuit. By using the method, the loss of power grid load caused by power failure detection can be avoided, and the applicability and accuracy of fault detection are improved.

Description

Technical Field

[0001] This application relates to the field of computer technology, and in particular to a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, a ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current, a server, a storage medium, and a computer program product. Background Technology

[0002] Voltage transformers (PTs) play two roles in power system operation: first, they proportionally reduce the voltage of the measured line to provide voltage for subsequent protection and metering; second, they isolate insulated equipment from the PT's secondary circuit. Therefore, to prevent high voltage generated during system faults from damaging the insulated equipment and to ensure the safety of personnel, equipment, and the system, the PT's secondary circuit must be reliably and effectively grounded.

[0003] In actual operation, the secondary circuits of PTs are numerous and complex, with many intersecting and long lines. Multiple grounding points often occur due to factors such as design, construction, aging of secondary equipment, and wiring errors. Multiple grounding faults in the PT's secondary circuits can lead to errors in energy metering, abnormal indications by microprocessor-based protection devices, and incorrect operation of relay protection and automatic safety devices. Furthermore, multiple grounding faults in the PT's secondary circuits pose a significant threat to the power plant system. The fault can cause a shift in the self-generated zero-sequence voltage of the microprocessor-based protection device, potentially leading to misjudgments in the zero-sequence direction protection, further causing widespread cascading failures and severely impacting system stability.

[0004] Traditional detection of multi-point grounding faults in the secondary circuit of a PT requires power outage detection, which involves adding a DC voltage measuring resistor to the secondary circuit or adding a resistor in parallel and determining whether a two-point grounding fault has occurred by measuring the current flowing through the resistor.

[0005] However, shutting down the power grid to detect ground faults will result in a loss of load on the entire power grid. The longer the power outage lasts, the greater the load loss on the power grid and the greater the impact on the lives of residents covered by the power grid. Summary of the Invention

[0006] This disclosure provides a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, a ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current, a server, a storage medium, and a computer program product, to at least solve the problem of power grid load loss when detecting faults during power outages in related technologies. The technical solution of this disclosure is as follows:

[0007] According to a first aspect of the present disclosure, a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current is provided, comprising:

[0008] Multiple current setting values ​​are obtained corresponding to multiple preset points in the power grid circuit; the power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation, the PT cables being the wiring cables of voltage transformers, each preset point belonging to a cable point of a branch circuit in the power grid circuit, and different preset points belonging to different branch circuits; the current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded; and

[0009] Based on the branch parameters of the branch circuit corresponding to each preset point, the instantaneous current value of each preset point is determined; the branch parameters include cable parameters and capacitance parameters.

[0010] Based on the steady-state characteristics corresponding to the multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point, it is determined whether there is a ground fault in the power grid circuit; the ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit.

[0011] In one exemplary embodiment, the cable parameters include the cable length and resistance value corresponding to each of the branch circuits; the capacitance parameters include the capacitance value corresponding to the capacitor in each of the branch circuits, and the angular frequency and angular velocity generated by the capacitor after being connected to the AC power of the mains circuit.

[0012] The step of determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point includes:

[0013] Based on the input voltage value of the AC power connected to the power grid circuit and the angular frequency and angular velocity of the capacitors set in each of the branch circuits, the instantaneous voltage values ​​corresponding to the plurality of preset points are determined.

[0014] Based on the derivative relationship between the capacitance value, cable length, and resistance value in each branch circuit and the instantaneous voltage value corresponding to each of the multiple preset points, the instantaneous current value corresponding to each preset point in the branch circuit is determined.

[0015] In an exemplary embodiment, obtaining multiple current setting values ​​corresponding to multiple preset points in the power grid circuit includes:

[0016] The first zero-sequence current value leaked by the PT cable when grounded, the second zero-sequence current value leaked by the outdoor control circuit in the power grid circuit when grounded, and the third zero-sequence current value leaked by the indoor control circuit in the power grid circuit when grounded are obtained.

[0017] The first zero-sequence current value is used as the first current setting value among the plurality of preset points, the second zero-sequence current value is used as the second current setting value among the plurality of preset points, and the third zero-sequence current value is used as the third current setting value among the plurality of preset points.

[0018] In an exemplary embodiment, the branch circuit includes a branch circuit connecting the plurality of secondary windings, a first branch circuit belonging to the first secondary winding, a second branch circuit belonging to the second secondary winding, and a third branch circuit belonging to the third secondary winding; the branch circuit is an outdoor control circuit located in the power grid circuit, and the first branch circuit, the second branch circuit, and the third branch circuit are all indoor control circuits located in the power grid circuit.

[0019] The determination of whether a ground fault exists in each branch circuit based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point includes:

[0020] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all less than the steady-state amplitude characteristics of the third current setting value, and are all greater than the first current setting value, then there is no grounding fault in each of the power grid circuits.

[0021] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the second current setting value, then there is a grounding fault in the outdoor control circuit in the power grid circuit.

[0022] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value, and are all less than the steady-state amplitude characteristics of the second current setting value, then the first branch circuit in the power grid circuit has a ground fault.

[0023] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the second branch circuit and the third branch circuit are equal and are all greater than the instantaneous current value corresponding to the first branch circuit, then the second branch circuit in the power grid circuit has a ground fault.

[0024] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the first branch circuit and the second branch circuit are equal and are all less than the instantaneous current value corresponding to the third branch circuit, then the third branch circuit in the power grid circuit has a grounding fault.

[0025] In one exemplary embodiment, the method further includes:

[0026] Based on the branch parameters corresponding to the first branch circuit, the second branch circuit, and the third branch circuit, determine the instantaneous value of the first zero-sequence voltage when the first branch circuit has a ground fault, the instantaneous value of the second zero-sequence voltage when the second branch circuit has a ground fault, and the instantaneous value of the third zero-sequence voltage when the third branch circuit has a ground fault.

[0027] Time-domain analysis is performed on the first instantaneous value of zero-sequence voltage, the second instantaneous value of zero-sequence voltage, and the third instantaneous value of zero-sequence voltage respectively to obtain the first transient waveform data of zero-sequence current corresponding to the first instantaneous value of zero-sequence voltage, the second transient waveform data of zero-sequence current corresponding to the second instantaneous value of zero-sequence voltage, and the third transient waveform data of zero-sequence current corresponding to the third instantaneous value of zero-sequence voltage.

[0028] The first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data are all subjected to wavelet packet decomposition, meanization, and exponentiation respectively to obtain the first feature data corresponding to the first zero-sequence current transient waveform data, the second feature data corresponding to the second zero-sequence current transient waveform data, and the third feature data corresponding to the third zero-sequence current transient waveform data.

[0029] Based on the magnitudes of the first feature data, the second feature data, and the third feature data relative to their respective preset threshold values, it is determined whether a grounding fault exists in the first branch circuit, the second branch circuit, and the third branch circuit.

[0030] In an exemplary embodiment, the step of sequentially performing wavelet packet decomposition, mean averaging, and exponentiation on the first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data to obtain first feature data corresponding to the first zero-sequence current transient waveform data, second feature data corresponding to the second zero-sequence current transient waveform data, and third feature data corresponding to the third zero-sequence current transient waveform data includes:

[0031] Each zero-sequence current transient waveform data is processed by wavelet packet decomposition to separate the first characteristic value corresponding to the 6th harmonic of each zero-sequence current transient waveform data.

[0032] The first feature value of each zero-sequence current transient waveform data is centered in a preset period to obtain the second feature value corresponding to each zero-sequence current transient waveform data.

[0033] The second characteristic value of each zero-sequence current transient waveform data is averaged to obtain the third characteristic value corresponding to each zero-sequence current transient waveform data.

[0034] The third characteristic value of each zero-sequence current transient waveform data is multiplied by four powers to obtain the fourth characteristic value corresponding to each zero-sequence current transient waveform data.

[0035] According to a second aspect of the present disclosure, a ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current is provided, comprising:

[0036] The data acquisition unit is configured to acquire multiple current setting values ​​corresponding to multiple preset points in the power grid circuit; the power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation, the PT cables are the wiring cables of voltage transformers, each preset point belongs to a cable point of a branch circuit in the power grid circuit, and different preset points belong to different cable points of different branch circuits; the current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded;

[0037] The current determination unit is configured to determine the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point; the branch parameters include cable parameters and capacitance parameters.

[0038] The fault detection unit is configured to perform a determination based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point to determine whether there is a ground fault in the power grid circuit; the ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit.

[0039] According to a third aspect of the present disclosure, a server is provided, comprising:

[0040] processor;

[0041] Memory for storing the executable instructions of the processor;

[0042] The processor is configured to execute the executable instructions to implement the ground fault location method utilizing the transient and steady-state characteristics of the grounding current of a PT cable as described in any of the preceding claims.

[0043] According to a fourth aspect of the present disclosure, a computer-readable storage medium is provided, the computer-readable storage medium including a computer program that, when executed by a processor of a server, enables the server to perform the ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current as described in any of the preceding claims.

[0044] According to a fifth aspect of the present disclosure, a computer program product is provided, the computer program product including program instructions that, when executed by a processor of a server, enable the server to perform the ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current as described in any of the preceding claims.

[0045] The technical solutions provided by the embodiments of this disclosure bring at least the following beneficial effects:

[0046] The method first obtains multiple current setting values ​​corresponding to multiple preset points in the power grid circuit. The power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation. The PT cables are the wiring cables of voltage transformers. Each preset point belongs to a cable point in a branch circuit of the power grid circuit, and different preset points belong to cable points in different branch circuits. The current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded. Based on the branch parameters of the branch circuit corresponding to each preset point, the instantaneous current value of each preset point is determined. The branch parameters include cable parameters and capacitance parameters. Then, based on the steady-state characteristics corresponding to the multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point, it is determined whether a ground fault exists in the power grid circuit. The ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit. In this way, on the one hand, unlike the existing methods of detecting power outages in the power grid to determine the fault point, this application uses the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point to determine whether there is a fault in the power grid circuit. This avoids the need to shut down the power grid, thereby avoiding necessary power grid load losses and improving the applicability of fault detection. On the other hand, by determining the instantaneous current value of the branch circuit based on the cable and capacitor parameters of the circuit, and by determining whether there is a grounding fault in the power grid circuit based on the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point, the generation rules and process of fault detection in the power grid circuit are optimized, improving the convenience and accuracy of fault detection in the power grid circuit.

[0047] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0048] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure, and are not intended to unduly limit this disclosure.

[0049] Figure 1 This is an application environment diagram illustrating a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, according to an exemplary embodiment.

[0050] Figure 2 This is a flowchart illustrating a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, according to an exemplary embodiment.

[0051] Figure 3This is a flowchart illustrating a step for determining the instantaneous current value at a preset point according to an exemplary embodiment.

[0052] Figure 4 This is a circuit diagram illustrating a power grid circuit according to an exemplary embodiment.

[0053] Figure 5 This is a flowchart illustrating a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, according to another exemplary embodiment.

[0054] Figure 6 This is a flowchart illustrating a step for obtaining characteristic data corresponding to transient waveform data of zero-sequence current, according to an exemplary embodiment.

[0055] Figure 7 This is a block diagram illustrating a ground fault location device utilizing the transient and steady-state characteristics of the grounding current of a PT cable, according to an exemplary embodiment.

[0056] Figure 8 This is a block diagram illustrating a server for locating ground faults using the transient and steady-state characteristics of the grounding current of a PT cable, according to an exemplary embodiment.

[0057] Figure 9 This is a block diagram illustrating a computer-readable storage medium for locating ground faults using the transient and steady-state characteristics of PT cable grounding current, according to an exemplary embodiment.

[0058] Figure 10 This is a block diagram illustrating a computer program product for locating ground faults using the transient and steady-state characteristics of the grounding current of a PT cable, according to an exemplary embodiment. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0060] The term "and / or" in the embodiments of this application refers to any and all possible combinations including one or more of the associated listed items. It should also be noted that, when used in this specification, "including / comprising" specifies the presence of the stated features, integers, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, and / or components and / or groups thereof.

[0061] The terms "first," "second," etc., used in this application are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0062] Furthermore, although the terms "first," "second," etc., are used repeatedly in this application to describe various operations (or various components, or various applications, or various instructions, or various data), these operations (or components, or applications, or instructions, or data) should not be limited by these terms. These terms are only used to distinguish one operation (or component, or application, or instruction, or data) from another operation (or component, or application, or instruction, or data). For example, a first adjustment voltage value can be called a second adjustment voltage value, and a second adjustment voltage value can be called a first adjustment voltage value; the only difference is the scope they encompass, but it does not depart from the scope of this application. Both the first adjustment voltage value and the second adjustment voltage value are sets of corresponding adjustment voltage values ​​obtained after amplitude adjustment processing of the characteristic voltage values ​​corresponding to the long-term voltage values ​​described above; they are simply not sets of the same type of adjustment voltage values.

[0063] The fault detection method for power grid circuits provided in this application embodiment can be applied to, for example... Figure 1 In the application environment shown, terminal 102 communicates with server 104 via a communication network. A data storage system can store the data that server 104 needs to process. The data storage system can be integrated onto server 104, or it can be located in the cloud or on other network servers.

[0064] In some embodiments, reference Figure 1First, server 104 acquires multiple current setting values ​​corresponding to multiple preset points in the power grid circuit. The power grid circuit is a secondary circuit formed by voltage transformers and multiple secondary windings in a substation. Each preset point belongs to a cable point of a branch circuit in the power grid circuit, and different preset points belong to different cable points of different branch circuits. The current setting value is used to characterize the preset zero-sequence current value of the branch circuit corresponding to the preset point. Then, server 104 determines the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point. The branch parameters include cable parameters and capacitance parameters. Finally, server 104 determines whether there is a grounding fault in each branch circuit based on the magnitude between the multiple current setting values ​​and the instantaneous current value of the corresponding preset point. The grounding fault is used to characterize the abnormal connection of the cable point of the branch circuit to the ground.

[0065] In some embodiments, the terminal 102 (such as a mobile terminal or a fixed terminal) can be implemented in various forms. The terminal 102 can be a mobile terminal that includes a mobile detection device (such as a galvanometer, voltmeter, or capacitive probe) capable of determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point. Alternatively, the terminal 102 can be a fixed terminal that uses an automatic detection device (such as a current detection device or voltage detection device) capable of determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point.

[0066] Hereinafter, it is assumed that terminal 102 is a fixed terminal. However, those skilled in the art will understand that, if there are operations or elements specifically designed for mobile purposes, the construction according to the embodiments disclosed in this application can also be applied to mobile type terminal 102.

[0067] In some embodiments, the data processing component running on server 104 may load any of the various additional server applications and / or middleware applications being executed, such as HTTP (Hypertext Transfer Protocol), FTP (File Transfer Protocol), CGI (Common Gateway Interface), RDBMS (Relational Database Management System), etc.

[0068] In some embodiments, server 104 may be implemented using a standalone server or a server cluster consisting of multiple servers. Server 104 may be adapted to run one or more application services or software components that provide the terminal 102 described in the foregoing disclosure.

[0069] In some embodiments, the server 104 provides one or more application services or software components including a portal port that provides one-to-one application services to users in the foreground and multiple business systems that perform data processing in the background, so as to extend the multiple current setting values ​​corresponding to multiple preset points in the power grid circuit and the instantaneous current values ​​of each preset point to the device end or client end, so that users can perform power grid circuit fault detection operations at any time and any place.

[0070] In some embodiments, the resource file generation and / or resource file disclosure functions of the device or client can be computer programs running in user mode to perform one or more specific tasks, which can interact with the user and have a visual user interface. The device or client can include two parts: a graphical user interface (GUI) and an engine, which together provide users with a variety of application services in the form of a user interface in a digital client system.

[0071] In some embodiments, a user can input corresponding code data or control parameters to the device or client through the input device in the terminal 102 to execute the application services of the computer program in the server 104 and display the application services in the user interface.

[0072] In some embodiments, the operating system running on the device or client may include various versions of Microsoft operating systems. Apple and / or Linux operating system, various commercial or similar Operating systems (including but not limited to various GNU / Linux operating systems, Google) (etc.) and / or mobile operating systems, such as

[0073] Operating systems, as well as other online or offline operating systems, are not specifically limited here.

[0074] In one exemplary embodiment, such as Figure 2 As shown, a fault detection method for a power grid circuit is provided, which can be applied to... Figure 1 Taking server 104 as an example, the method includes the following steps:

[0075] Step S11: Obtain multiple current setting values ​​corresponding to multiple preset points in the power grid circuit.

[0076] In one embodiment, the power grid circuit is a secondary loop circuit formed by connecting a PT cable and multiple secondary windings in a substation. The PT cable is the wiring cable of a voltage transformer. Each preset point belongs to a cable point of a branch circuit in the power grid circuit, and different preset points belong to cable points of different branch circuits.

[0077] In some embodiments, multiple secondary windings are typically connected to the busbar of the N600 (voltage transformer N600) in the substation to form multiple secondary circuits. These secondary circuits are used by power meters, measuring devices, relay protection devices, and stability devices, respectively. The relay protection devices and stability devices share a single secondary winding (i.e., a secondary circuit).

[0078] In some embodiments, each secondary winding has 3 branch circuits, each branch circuit has 1 neutral point, and all neutral points and the N line of the secondary winding are grounded at a certain point in the control room of the substation through the busbar of N600 (voltage transformer N600).

[0079] In some embodiments, the cable length of the portion of the substation other than the secondary winding is L1, and the cable length from the neutral point of each branch circuit of the secondary winding in the control room to the grounding bus of N600 is L2, wherein L1 is much larger than L2.

[0080] In one embodiment, the server obtains multiple current setting values ​​corresponding to multiple preset points in the power grid circuit, including: firstly, obtaining the first zero-sequence current value I leaked by the PT cable when it is grounded. set1 The second zero-sequence current value I leaked from the outdoor control circuit in the power grid when it was grounded. set2 And the third zero-sequence current value I leaked by the control room circuit in the power grid when it was grounded. set3 Then, the first zero-sequence current value is used as the first current setting value among multiple preset points, the second zero-sequence current value is used as the second current setting value among multiple preset points, and the third zero-sequence current value is used as the third current setting value among multiple preset points.

[0081] In some embodiments, the branch circuits of the power grid circuit in the substation include a branch circuit connecting multiple secondary windings, a first branch circuit belonging to the first secondary winding, a second branch circuit belonging to the second secondary winding, and a third branch circuit belonging to the third secondary winding. The branch circuit is an outdoor control room circuit located within the power grid circuit; the first, second, and third branch circuits are all indoor control room circuits located within the power grid circuit.

[0082] In some embodiments, the cable parameters of the cables in the power grid circuit include the cable lengths (L1 and L2) and resistance values ​​R corresponding to each branch circuit; the capacitance parameters of the capacitors configured in the power grid circuit include the capacitance values ​​C corresponding to each branch circuit, and the angular frequency generated by the capacitors after being connected to the alternating current in the power grid circuit. and angular velocity α.

[0083] In another embodiment, the server first connects the first branch circuit in the control room to the grounding bus of N600, then disconnects the second and third branch circuits from the grounding bus of N600, and each of them is grounded through a current measuring instrument. Then, the server uses multiple preset points to determine the input voltage U0, capacitance C, and angular frequency of the corresponding branch circuits. Given the angular velocity α, determine the instantaneous current value I0 at each preset point, and use the instantaneous current value I0 as the current setting value I at the corresponding preset point. set .

[0084] As an example, if the server ignores the resistance R and inductive reactance of the cable in the secondary circuit, the current setting value I at the preset measurement point will be... set The expression is:

[0085]

[0086] Wherein, the instantaneous current value I0 is the current setting value I at the corresponding preset point. set C i =L i C0, L i Let C be the length of the i-th secondary cable, and C0 be the capacitance per meter of cable.

[0087] Among them, the current setting value of the preset point on branch circuit 1 is determined by I. set0 This indicates that the current setting value at the preset point on the first branch circuit is determined by I. set1 This indicates that the current setting value at the preset point on the second branch circuit is determined by I. set2 This indicates that the current setting value at the preset point on the third branch circuit is determined by I. set3 express.

[0088] In some embodiments, the current setting value is used to characterize the zero-sequence current value leaked in the branch circuit corresponding to the preset point when a ground fault occurs.

[0089] In some embodiments, during normal operation of the power grid circuit, the N600 busbar on the secondary circuit of the PT can only have one grounding point. Due to cable damage or other human factors, another grounding point may appear in the L1 section of the cable or the L2 section of each branch, resulting in a multi-point grounding fault. This can generate zero-sequence current in the power grid circuit and cause implicit faults in the secondary circuit of the relay protection, which may lead to relay protection malfunctions under certain circumstances.

[0090] In one embodiment, the zero-sequence current is generated as follows: due to the occurrence of a multi-point grounding fault, the current at the grounding point induces a voltage in the secondary circuit of the power grid circuit, resulting in a voltage difference between two adjacent grounding points. This causes a loop to be formed between the secondary circuit of the power grid circuit and the ground grid, thereby generating a zero-sequence current. The current flowing into the ground through the distributed capacitance in the circuit flows back from the grounding point and the fault point.

[0091] The more secondary circuits in the power grid circuit and the longer the cable, the greater the zero-sequence current generated.

[0092] Step S12: Determine the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point.

[0093] In one embodiment, a fault occurring on a cable outside the control room or on a grounding cable of a different branch inside the control room can create a multi-point grounding fault. In this case, the location of the fault point should be determined to facilitate maintenance of the secondary circuit.

[0094] For example, a ground fault may occur at a certain point on the N line of the secondary winding outside the control room, and a ground fault may occur at a certain point on the neutral line of the first branch, the neutral line of the second branch, and the neutral line of the third branch of the secondary winding inside the control room.

[0095] Therefore, by measuring the zero-sequence current (the instantaneous current value at the preset point) between the neutral line of each branch and the grounding point, the fault point can be located by measuring the magnitude of the zero-sequence current. Specifically, the detection of multi-point grounding faults in the secondary circuit is determined by monitoring whether zero-sequence current appears at each possible grounding point to identify whether multiple grounding points have occurred.

[0096] In one embodiment, the server first bases the input voltage U0 of the AC power connected to the mains circuit and the angular frequency of the capacitors installed in each branch circuit on the input voltage U0. Given the angular velocity α, the instantaneous voltage value u0 corresponding to multiple preset points is determined. Then, based on the derivative relationship between the capacitance value C, cable length (L1 and L2), and resistance value R in each branch circuit and the instantaneous voltage value u0 corresponding to each of the multiple preset points, the server determines the instantaneous current value I corresponding to each preset point in the branch circuit.

[0097] Among them, the instantaneous current value at the preset point on branch circuit 1 is transmitted through I. 00 This indicates that the instantaneous current value at the preset point on the first branch circuit is transmitted through I... 01 This indicates that the instantaneous current value at the preset point on the second branch circuit is transmitted through I. 02 This indicates that the instantaneous current value at the preset point on the third branch circuit is transmitted through I. 03 express.

[0098] Step S13: Based on the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point, determine whether there is a grounding fault in the power grid circuit.

[0099] In one embodiment, a ground fault is used to characterize a cable location in the power grid circuit that is abnormally connected to the ground.

[0100] In one embodiment, if the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit (i.e., I...) 01 I 02 I 03 The transient amplitude characteristics of all are smaller than the third current setting value (i.e., I). set3 The steady-state amplitude characteristics of the current, and both are greater than the first current setting value (i.e., I). set1 If the ground fault is not present in any of the power grid circuits, then there is no ground fault in any of the power grid circuits.

[0101] Specifically, since the zero-sequence voltage of each branch circuit to ground is generated by the current induction in the grounding grid, the zero-sequence voltage amplitude at the grounding point in the power grid circuit is the smallest, and the zero-sequence leakage current at the grounding point is the smallest. At this time, I = I 01 =I 02 =I 03 =I 00 .

[0102] Therefore, the formula for determining that there are no ground faults in the power grid circuit is: I set3 >I>I set1 .

[0103] In one embodiment, if the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit (i.e., I...) 01 I 02 I 03 The transient amplitude characteristics of all are greater than the second current setting value (i.e., I). set2 If the steady-state amplitude characteristics of the circuit are such that the outdoor control circuit in the power grid circuit has a grounding fault, then the circuit is located outside the control room.

[0104] Specifically, since the secondary circuit is led out from the distribution box to the protection control room, if there is a grounding point in the circuit outside the control room in the power grid circuit, there is a long distance between it and the grounding point of N600. The zero-sequence voltage amplitude and leakage zero-sequence current are at their maximum at the grounding point of the circuit outside the control room. At this time, I 01 =I 02 =I 03 .

[0105] Therefore, the formula for determining whether a ground fault exists in a circuit outside the control room of the power grid is: I 01 =I 02 =I 03 >I set2 .

[0106] In one embodiment, if the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit (i.e., I...) 01 I 02 I 03 The transient amplitude characteristics of all are greater than the third current setting value (i.e., I). set3 The steady-state amplitude characteristics of ) and both are less than the second current setting value (i.e., I) set2 If the steady-state amplitude characteristics of the circuit are such that the first branch circuit in the power grid circuit has a ground fault, then the circuit has a ground fault.

[0107] Specifically, if there is a fault point in the first branch circuit, it is closer to the grounding point of N600. Its leakage zero-sequence current amplitude is smaller than that of the leakage zero-sequence current amplitude of the circuit grounding point outside the control room in the power grid circuit, but larger than that when there is no fault.

[0108] Therefore, the formula for determining if the first branch circuit has a ground fault is: I set2 >I 01 =I 02 =I 03 >I set3 .

[0109] In one embodiment, if the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit (i.e., I...) 01 I 02 I 03 The transient amplitude characteristics of all are greater than the third current setting value (i.e., I). set3 The steady-state amplitude characteristics of the current are all less than the second current setting value (i.e., I). set2 The steady-state amplitude characteristics of the circuit, and the instantaneous current values ​​corresponding to the second and third branches are equal, and both are greater than the instantaneous current value corresponding to the first branch (i.e., I). 02 =I 03 >I 01If the second branch circuit in the power grid circuit has a ground fault, then the second branch circuit in the power grid circuit has a ground fault.

[0110] Specifically, if there is a fault point in the second branch circuit, it is closer to the grounding point of N600. Its leakage zero-sequence current amplitude is smaller than that of the leakage zero-sequence current amplitude of the circuit grounding point outside the control room in the power grid circuit, but larger than that when there is no fault.

[0111] Therefore, the formula for determining if the second branch circuit has a ground fault is: I set2 >I 02 =I 03 >I 01 >I set3 .

[0112] In one embodiment, if the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit (i.e., I...) 01 I 02 I 03 The transient amplitude characteristics of all are greater than the third current setting value (i.e., I). set3 The steady-state amplitude characteristics of the current are all less than the second current setting value (i.e., I). set2 The steady-state amplitude characteristics of the circuit, and the instantaneous current values ​​corresponding to the first and second branches are equal and both less than the instantaneous current value corresponding to the third branch (i.e., I). 03 >I 02 =I 01 If the third branch circuit in the power grid circuit has a grounding fault, then the third branch circuit in the power grid circuit has a grounding fault.

[0113] Specifically, if there is a fault point in the third branch circuit, it is closer to the grounding point of N600. Its leakage zero-sequence current amplitude is smaller than that of the leakage zero-sequence current amplitude of the circuit grounding point outside the control room in the power grid circuit, but larger than that when there is no fault.

[0114] Therefore, the formula for determining if the third branch circuit has a ground fault is: I set2 >I 03 >I 02 =I 01 >I set1 .

[0115] In the aforementioned ground fault location process utilizing the transient and steady-state characteristics of PT cable grounding current, the server first acquires multiple current setting values ​​corresponding to multiple preset points in the power grid circuit. The power grid circuit is a secondary circuit formed by PT cables and multiple secondary windings connected in the substation. The PT cables are the wiring cables of voltage transformers. Each preset point belongs to a cable point in a branch circuit of the power grid circuit, and different preset points belong to cable points in different branch circuits. The current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded. Based on the branch parameters of the branch circuit corresponding to each preset point, the instantaneous current value of each preset point is determined. The branch parameters include cable parameters and capacitance parameters. Then, based on the steady-state characteristics corresponding to the multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point, it is determined whether a ground fault exists in the power grid circuit. The ground fault characterizes the presence of a cable point abnormally connected to the ground in the power grid circuit. In this way, on the one hand, unlike the existing methods of detecting power outages in the power grid to determine the fault point, this application uses the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point to determine whether there is a fault in the power grid circuit. This avoids the need to shut down the power grid, thereby avoiding necessary power grid load losses and improving the applicability of fault detection. On the other hand, by determining the instantaneous current value of the branch circuit based on the cable and capacitor parameters of the circuit, and by determining whether there is a grounding fault in the power grid circuit based on the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point, the generation rules and process of fault detection in the power grid circuit are optimized, improving the convenience and accuracy of fault detection in the power grid circuit.

[0116] Those skilled in the art will understand that the methods disclosed in the above-described specific embodiments can be implemented in more specific ways. For example, the embodiment described above for determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point is merely illustrative.

[0117] For example, the server determines whether each branch circuit has a grounding fault based on the magnitude between the plurality of current setting values ​​and the instantaneous current value of the corresponding preset point. This is only one way of combining the values. In actual implementation, there may be other ways of dividing the values. For example, the plurality of current setting values ​​and the instantaneous current value of the corresponding preset point may be combined or combined into another system, or some features may be ignored or not executed.

[0118] In one exemplary embodiment, see Figure 3 , Figure 3This is a flowchart illustrating an embodiment of determining the instantaneous current value of a preset point in this application. In step S12, the process by which the server determines the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point can be implemented in the following way:

[0119] Step S121: Based on the input voltage value of the AC power connected to the power grid circuit and the angular frequency and angular velocity of the capacitors set in each branch circuit, determine the instantaneous voltage value corresponding to multiple preset points.

[0120] In some embodiments, due to the uneven current distribution in the grounding grid and its variation over time, as well as the distributed capacitance in the secondary circuit, the instantaneous waveform of the zero-sequence voltage of the cable to ground in the secondary circuit contains multiple frequency components, with the power frequency component being dominant. The waveform of its decaying instantaneous zero-sequence current exhibits a very small amplitude, and its power frequency component contains various noise components.

[0121] In some embodiments, when the secondary circuit is operating normally, the zero-sequence voltage of each branch circuit is very small, close to 0, so the zero-sequence current is close to 0.

[0122] In some embodiments, when a branch circuit in the secondary circuit experiences a multi-point grounding fault in a stable state, the amplitude of the zero-sequence voltage of the corresponding branch circuit is very large, and a large zero-sequence current appears.

[0123] In some embodiments, when there is a multi-point grounding fault with intermittent state in a branch circuit in the secondary circuit, the amplitude of the zero-sequence voltage of the corresponding branch circuit varies from 0 to the amplitude of the stable grounding voltage.

[0124] In one embodiment, if the input voltage value of the branch circuit corresponding to the preset point is U0 and the angular frequency is... Given an angular velocity of α, the expression for the instantaneous voltage value u0 corresponding to the preset measurement point is:

[0125] u0=U0sin(ωt+α).

[0126] Step S122: Based on the derivative relationship between the capacitance value, cable length and resistance value in each branch circuit and the instantaneous voltage value corresponding to each of the multiple preset points, determine the instantaneous current value corresponding to the preset point in each branch circuit.

[0127] In one embodiment, if the capacitance value in a branch circuit is C, the cable length is L, and the resistance value is R, then the instantaneous current value I corresponding to a preset point in each branch circuit can be obtained based on the following time-domain simultaneous formulas for zero-sequence current:

[0128]

[0129]

[0130] i 03 =i 01 -i 02 .

[0131] Among them, i 01 i represents the input current of the corresponding branch circuit. 01 i represents the output current of the corresponding branch circuit. 01 The instantaneous current value I (including I) at the preset point of the corresponding branch circuit. 00 I 01 I 02 I 03 ).

[0132] In one exemplary embodiment, see Figure 4 , Figure 4 This is a circuit diagram illustrating an embodiment of the power grid circuit in this application. The branch circuits in the power grid circuit include a branch circuit 1 (whose cable length can be represented by L1) connecting multiple secondary windings, a first branch circuit belonging to the first secondary winding (whose cable length can be represented by L2), a second branch circuit belonging to the second secondary winding (whose cable length can be represented by L2), and a third branch circuit belonging to the third secondary winding (whose cable length can be represented by L2). Specifically, K1 in branch circuit 1 may have a ground fault, K2 in the first branch circuit may have a ground fault, K3 in the second branch circuit may have a ground fault, and K4 in the third branch circuit may have a ground fault.

[0133] In one exemplary embodiment, such as Figure 5 As shown, another method for locating ground faults using the transient and steady-state characteristics of PT cable grounding current is provided. This method can be used in conjunction with the above method (i.e., steps S11-S13) or used alone. This method is applied to... Figure 1 Taking server 104 as an example, the method includes the following steps:

[0134] Step S21: Based on the branch parameters corresponding to the first branch circuit, the second branch circuit, and the third branch circuit, determine the instantaneous value of the first zero-sequence voltage when the first branch circuit has a ground fault, the instantaneous value of the second zero-sequence voltage when the second branch circuit has a ground fault, and the instantaneous value of the third zero-sequence voltage when the third branch circuit has a ground fault.

[0135] As an example, due to different power grid operating conditions, the current distribution in the grounding grid is different, so the zero-sequence voltage induced in the secondary circuit is also different. When a two-point grounding occurs, the expression for the instantaneous value of the zero-sequence voltage in the corresponding branch circuit when a grounding fault exists is as follows:

[0136]

[0137] Step S22: Perform time-domain analysis on the instantaneous values ​​of the first, second, and third zero-sequence voltages respectively to obtain the transient waveform data of the first zero-sequence current corresponding to the instantaneous value of the first zero-sequence voltage, the transient waveform data of the second zero-sequence current corresponding to the instantaneous value of the second zero-sequence voltage, and the transient waveform data of the third zero-sequence current corresponding to the instantaneous value of the third zero-sequence voltage.

[0138] As an example, due to the uneven current distribution in the grounding grid and its variation over time, as well as the distributed capacitance in the secondary circuit, the instantaneous zero-sequence voltage waveform of the PT secondary cable to ground should be a transient leakage zero-sequence current waveform containing multiple frequency components, with the power frequency component being dominant and attenuated. This is characterized by a very small amplitude, and the power frequency component including various noise components.

[0139] During normal operation, the zero-sequence voltage is very small, close to 0, so the zero-sequence current is close to 0. When a stable two-point grounding fault occurs, the zero-sequence voltage amplitude is very large, resulting in a large zero-sequence current. When an intermittent two-point grounding fault occurs, the zero-sequence voltage amplitude varies from 0 to the stable grounding voltage amplitude.

[0140] In some embodiments, the server performs time-domain analysis on the instantaneous values ​​of the first, second, and third zero-sequence voltages, respectively, to obtain the transient waveform data of the first zero-sequence current corresponding to the instantaneous value of the first zero-sequence voltage, the transient waveform data of the second zero-sequence current corresponding to the instantaneous value of the second zero-sequence voltage, and the transient waveform data of the third zero-sequence current corresponding to the instantaneous value of the third zero-sequence voltage, as follows:

[0141]

[0142]

[0143] i 03 =i 01 -i 02 .

[0144] Among them, i 01 For the transient waveform data of the first zero-sequence current corresponding to the instantaneous value of the first zero-sequence voltage, i 02 For the transient waveform data of the second zero-sequence current corresponding to the instantaneous value of the second zero-sequence voltage, i 03 This is the transient waveform data of the third zero-sequence current corresponding to the instantaneous value of the third zero-sequence voltage.

[0145] Step S23: Wavelet packet decomposition, mean averaging, and exponentiation are performed on the first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data respectively to obtain the first feature data corresponding to the first zero-sequence current transient waveform data, the second feature data corresponding to the second zero-sequence current transient waveform data, and the third feature data corresponding to the third zero-sequence current transient waveform data.

[0146] In one exemplary embodiment, see Figure 6 , Figure 6 This is a flowchart illustrating an embodiment of obtaining feature data corresponding to the transient waveform data of zero-sequence current in this application. In step S23, the server can be implemented in the following way:

[0147] Step S231: Wavelet packet decomposition is performed on each zero-sequence current transient waveform data in turn to separate the first characteristic value corresponding to the 6th harmonic of each zero-sequence current transient waveform data.

[0148] In some embodiments, the server sequentially performs wavelet packet decomposition (WPD) on each zero-sequence current transient waveform data to divide the frequency band data corresponding to the long-time voltage value into multiple levels, so as to separate the characteristic voltage value corresponding to each long-time voltage value at a frequency of 300Hz (i.e., below the 6th harmonic).

[0149] Step S232: The first feature value of each zero-sequence current transient waveform data is centered in a preset period to obtain the second feature value corresponding to each zero-sequence current transient waveform data.

[0150] In some embodiments, to eliminate the dimensional influence between different long-term voltage values ​​of faulty data, the server performs WPD processing on the zero-sequence current transient waveform data of each faulty data, and then centralizes the characteristic voltage value corresponding to the first characteristic value of each zero-sequence current transient waveform data of the obtained faulty data in a periodic unit:

[0151] u' = |u| - μ.

[0152] Where u' represents the second feature value of each zero-sequence current transient waveform data corresponding to each cycle after centering, u is the original data of the first feature value of each zero-sequence current transient waveform data corresponding to each cycle, and μ is the average value of the original data of |u| for each cycle.

[0153] Step S233: Average the second feature value of each zero-sequence current transient waveform data to obtain the third feature value corresponding to each zero-sequence current transient waveform data.

[0154] In some embodiments, the server performs mean averaging on the second feature value of each zero-sequence current transient waveform data containing faulty data after centralization to obtain the third feature value corresponding to each zero-sequence current transient waveform data:

[0155] u avgmax =mean[max(u')].

[0156] Step S234: The third characteristic value of each zero-sequence current transient waveform data is multiplied by four times to obtain the fourth characteristic value corresponding to each zero-sequence current transient waveform data.

[0157] In some embodiments, to improve the sensitivity of fault data identification, the server performs a fourth power operation on the third feature value of each obtained zero-sequence current transient waveform data to obtain the fourth feature value corresponding to each zero-sequence current transient waveform data.

[0158] Step S24: Based on the magnitudes of the first feature data, the second feature data, and the third feature data with their respective preset threshold values, determine whether there is a grounding fault in the first branch circuit, the second branch circuit, and the third branch circuit.

[0159] In one embodiment, the server performs the specific discrimination process according to the following formula:

[0160]

[0161] In this formula, the left side represents the characteristic value corresponding to the first characteristic data of the first branch circuit, the characteristic value corresponding to the second characteristic data of the second branch circuit, or the characteristic value corresponding to the third characteristic data of the third branch circuit, and the right side represents the preset threshold value of the server.

[0162] In one embodiment, if the characteristic value corresponding to the characteristic data of a branch circuit is greater than the corresponding preset threshold value, the server determines that the corresponding branch circuit has a grounding fault.

[0163] The above-mentioned solution, on the one hand, differs from existing methods of detecting power outages in the power grid to determine the fault point. This application utilizes the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point to determine whether a fault exists in the power grid circuit. This avoids the need for power outages, thereby preventing necessary power grid load losses and improving the applicability of fault detection. On the other hand, it determines the instantaneous current value of the branch circuit based on the cable and capacitor parameters of the circuit, and determines whether a grounding fault exists in the power grid circuit based on the steady-state characteristics corresponding to multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point. This optimizes the generation rules and process for fault detection in the power grid circuit, improving the convenience and accuracy of fault detection in the power grid circuit.

[0164] It should be understood that, although Figures 2-6 The steps in the flowchart are shown sequentially as indicated by the arrows, but these steps are not necessarily executed in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order in which these steps are executed, and they can be performed in other orders. Figures 2-6 At least some of the steps in the process may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but may be executed at different times. The execution order of these steps or stages is not necessarily sequential, but may be executed in turn or alternately with other steps or at least some of the steps or stages in other steps.

[0165] It is understood that the same / similar parts between the various embodiments of the methods described above in this specification can be referred to each other. Each embodiment focuses on the differences from other embodiments, and relevant parts can be referred to the description of other method embodiments.

[0166] Figure 7 This is a block diagram of a ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current, provided in an embodiment of this application. (Refer to...) Figure 7 The ground fault location device 10, which utilizes the transient and steady-state characteristics of the grounding current of a PT cable, includes: a data acquisition unit 11, a current determination unit 12, and a fault detection unit 13.

[0167] The data acquisition unit 11 is configured to acquire multiple current setting values ​​corresponding to multiple preset points in the power grid circuit. The power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation. The PT cables are the wiring cables of voltage transformers. Each preset point belongs to a cable point of a branch circuit in the power grid circuit, and different preset points belong to different cable points of different branch circuits. The current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded.

[0168] The current determination unit 12 is configured to determine the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point; the branch parameters include cable parameters and capacitor parameters.

[0169] The fault detection unit 13 is configured to perform a determination of whether there is a ground fault in the power grid circuit based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point; the ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit.

[0170] In some embodiments, the cable parameters include the cable length and resistance value corresponding to each of the branch circuits; the capacitance parameters include the capacitance value corresponding to the capacitor in each of the branch circuits, and the angular frequency and angular velocity generated by the capacitor after being connected to the AC power of the mains circuit.

[0171] In determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point, the ground fault location device 10 utilizing the transient and steady-state characteristics of PT cable grounding current is specifically used for:

[0172] Based on the input voltage value of the AC power connected to the power grid circuit and the angular frequency and angular velocity of the capacitors set in each of the branch circuits, the instantaneous voltage values ​​corresponding to the plurality of preset points are determined.

[0173] Based on the derivative relationship between the capacitance value, cable length, and resistance value in each branch circuit and the instantaneous voltage value corresponding to each of the multiple preset points, the instantaneous current value corresponding to each preset point in the branch circuit is determined.

[0174] In some embodiments, in obtaining multiple current setting values ​​corresponding to multiple preset points in a power grid circuit, the ground fault location device 10 utilizing the transient and steady-state characteristics of the PT cable grounding current is specifically used for:

[0175] The first zero-sequence current value leaked by the PT cable when grounded, the second zero-sequence current value leaked by the outdoor control circuit in the power grid circuit when grounded, and the third zero-sequence current value leaked by the indoor control circuit in the power grid circuit when grounded are obtained.

[0176] The first zero-sequence current value is used as the first current setting value among the plurality of preset points, the second zero-sequence current value is used as the second current setting value among the plurality of preset points, and the third zero-sequence current value is used as the third current setting value among the plurality of preset points.

[0177] In some embodiments, the branch circuit includes a branch circuit connecting the plurality of secondary windings, a first branch circuit belonging to the first secondary winding, a second branch circuit belonging to the second secondary winding, and a third branch circuit belonging to the third secondary winding; the branch circuit is an outdoor control circuit located in the power grid circuit, and the first branch circuit, the second branch circuit, and the third branch circuit are all indoor control circuits located in the power grid circuit; in determining whether each branch circuit has a ground fault based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point, the ground fault location device 10 utilizing the transient and steady-state characteristics of the PT cable grounding current includes:

[0178] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all less than the steady-state amplitude characteristics of the third current setting value, and are all greater than the first current setting value, then there is no grounding fault in each of the power grid circuits.

[0179] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the second current setting value, then there is a grounding fault in the outdoor control circuit in the power grid circuit.

[0180] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value, and are all less than the steady-state amplitude characteristics of the second current setting value, then the first branch circuit in the power grid circuit has a ground fault.

[0181] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the second branch circuit and the third branch circuit are equal and are all greater than the instantaneous current value corresponding to the first branch circuit, then the second branch circuit in the power grid circuit has a ground fault.

[0182] If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the first branch circuit and the second branch circuit are equal and are all less than the instantaneous current value corresponding to the third branch circuit, then the third branch circuit in the power grid circuit has a grounding fault.

[0183] In one embodiment, the ground fault location device 10 utilizing the transient and steady-state characteristics of PT cable grounding current further includes:

[0184] Based on the branch parameters corresponding to the first branch circuit, the second branch circuit, and the third branch circuit, determine the instantaneous value of the first zero-sequence voltage when the first branch circuit has a ground fault, the instantaneous value of the second zero-sequence voltage when the second branch circuit has a ground fault, and the instantaneous value of the third zero-sequence voltage when the third branch circuit has a ground fault.

[0185] Time-domain analysis is performed on the first instantaneous value of zero-sequence voltage, the second instantaneous value of zero-sequence voltage, and the third instantaneous value of zero-sequence voltage respectively to obtain the first transient waveform data of zero-sequence current corresponding to the first instantaneous value of zero-sequence voltage, the second transient waveform data of zero-sequence current corresponding to the second instantaneous value of zero-sequence voltage, and the third transient waveform data of zero-sequence current corresponding to the third instantaneous value of zero-sequence voltage.

[0186] The first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data are all subjected to wavelet packet decomposition, meanization, and exponentiation respectively to obtain the first feature data corresponding to the first zero-sequence current transient waveform data, the second feature data corresponding to the second zero-sequence current transient waveform data, and the third feature data corresponding to the third zero-sequence current transient waveform data.

[0187] Based on the magnitudes of the first feature data, the second feature data, and the third feature data relative to their respective preset threshold values, it is determined whether a grounding fault exists in the first branch circuit, the second branch circuit, and the third branch circuit.

[0188] In some embodiments, in performing wavelet packet decomposition, mean averaging, and exponentiation on the first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data respectively to obtain first feature data corresponding to the first zero-sequence current transient waveform data, second feature data corresponding to the second zero-sequence current transient waveform data, and third feature data corresponding to the third zero-sequence current transient waveform data, the adjustment unit 12A is further configured to:

[0189] Each zero-sequence current transient waveform data is processed by wavelet packet decomposition to separate the first characteristic value corresponding to the 6th harmonic of each zero-sequence current transient waveform data.

[0190] The first feature value of each zero-sequence current transient waveform data is centered in a preset period to obtain the second feature value corresponding to each zero-sequence current transient waveform data.

[0191] The second characteristic value of each zero-sequence current transient waveform data is averaged to obtain the third characteristic value corresponding to each zero-sequence current transient waveform data.

[0192] The third characteristic value of each zero-sequence current transient waveform data is multiplied by four powers to obtain the fourth characteristic value corresponding to each zero-sequence current transient waveform data.

[0193] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0194] Figure 8 This is a block diagram of a server 20 provided in an embodiment of this application. For example, server 20 can be an electronic device, an electronic component, or a server array, etc. (Refer to...) Figure 8 Server 20 includes processor 21, which may be a processor set, including one or more processors. Server 20 also includes memory resources represented by memory 22, on which computer programs, such as application programs, are stored. The computer programs stored in memory 22 may include one or more modules, each corresponding to a set of executable instructions. Furthermore, processor 21 is configured to implement, when executing the computer program, a ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, as described above.

[0195] In some embodiments, server 20 is an electronic device whose computing system can run one or more operating systems, including any of the operating systems discussed above and any commercially available server operating system. Server 20 can also run any of a variety of additional server applications and / or middleware applications, including HTTP (Hypertext Transfer Protocol) servers, FTP (File Transfer Protocol) servers, CGI (Common Gateway Interface) servers, super servers, database servers, etc. Exemplary database servers include, but are not limited to, commercially available database servers from companies such as IBM.

[0196] In some embodiments, processor 21 typically controls the overall operation of server 20, such as operations associated with display, data processing, data communication, and recording operations. Processor 21 may include one or more processors to execute computer programs to perform all or part of the steps of the methods described above. Furthermore, processor 21 may include one or more modules to facilitate interaction between processor 21 and other components. For example, processor 21 may include a multimedia module to facilitate control of the interaction between user server 20 and processor 21 using multimedia components.

[0197] In some embodiments, processor 21 may also be referred to as a CPU (Central Processing Unit). Processor 21 may be an electronic chip with signal processing capabilities. Processor 21 may also be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. The general-purpose processor may be a microprocessor, or processor 21 may be any conventional processor. Furthermore, the processor may be implemented using integrated circuit chips.

[0198] In some embodiments, memory 22 is configured to store various types of data to support the operation of electronic device 20. Examples of such data include instructions for any application or method operating on server 20, acquired data, messages, images, videos, etc. Memory 22 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, optical disk, or graphene storage.

[0199] In some embodiments, the memory 22 can be a memory module, TF card, etc., and can store all information in the server 20, including the input raw data, computer programs, intermediate running results, and final running results. In some embodiments, it stores and retrieves information according to the location specified by the processor 21. In some embodiments, the server 20 has a memory function and can ensure normal operation because of the memory 22. In some embodiments, the memory 22 of the server 20 can be classified into main memory (RAM) and auxiliary memory (external memory) according to its purpose, or it can be classified into external memory and internal memory. External memory is usually magnetic media or optical discs, which can store information for a long time. RAM refers to the storage component on the motherboard, which is used to store the currently executing data and programs, but it is only used to temporarily store programs and data. The data will be lost when the power is turned off or the power is cut off.

[0200] In some embodiments, server 20 may further include: a power supply component 23 configured to perform power management of server 20, a wired or wireless network interface 24 configured to connect electronic device 20 to a network, and an input / output (I / O) interface 25. Server 20 may operate on an operating system stored in memory 22, such as Windows Server, Mac OS X, Unix, Linux, FreeBSD, or similar.

[0201] In some embodiments, power supply component 23 provides power to various components of server 20. Power supply component 23 may include a power management system, one or more power supplies, and other components associated with generating, managing, and distributing power to server 20.

[0202] In some embodiments, the wired or wireless network interface 24 is configured to facilitate wired or wireless communication between the server 20 and other devices. The server 20 may access wireless networks based on communication standards, such as WiFi, carrier networks (such as 2G, 3G, 4G, or 5G), or combinations thereof.

[0203] In some embodiments, the wired or wireless network interface 24 receives broadcast signals or broadcast-related information from an external broadcast management system via a broadcast channel. In one exemplary embodiment, the wired or wireless network interface 24 also includes a near-field communication (NFC) module to facilitate short-range communication. For example, the NFC module may be implemented based on radio frequency identification (RFID) technology, Infrared Data Association (IrDA) technology, ultra-wideband (UWB) technology, Bluetooth (BT) technology, and other technologies.

[0204] In some embodiments, the input / output (I / O) interface 25 provides an interface between the processor 21 and peripheral interface modules, such as a keyboard, click wheel, buttons, etc. These buttons may include, but are not limited to, a home button, volume buttons, a power button, and a lock button.

[0205] Figure 9 This is a block diagram of a computer-readable storage medium 30 provided in an embodiment of this application. The computer-readable storage medium 30 stores a computer program 31, wherein when the computer program 31 is executed by a processor, it implements the ground fault location method using the transient and steady-state characteristics of the grounding current of a PT cable as described above.

[0206] If the integrated units of the various functional units in the various embodiments of this application are implemented as software functional units and sold or used as independent products, they can be stored in the computer-readable storage medium 30. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer-readable storage medium 30 includes a computer program 31, which includes several instructions to cause a computer device (which may be a personal computer, system server, or network device, etc.), an electronic device (e.g., MP3, MP4, etc., or a mobile phone, tablet computer, wearable device, etc., or a desktop computer, etc.) or a processor to execute all or part of the steps of the methods of the various embodiments of this application.

[0207] Figure 10 This is a block diagram of a computer program product 40 provided in an embodiment of this application. The computer program product 40 includes program instructions 41, which can be executed by the processor of server 20 to implement the ground fault location method using the transient and steady-state characteristics of PT cable grounding current as described above.

[0208] Those skilled in the art will understand that embodiments of this application may provide a fault detection method for a power grid circuit, a fault detection device 10 for a power grid circuit, a fault detection device 10A for a power grid circuit, a server 20, a computer-readable storage medium 30, or a computer program product 40. Therefore, this application may take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application may take the form of a computer program product 40 embodied on one or more computer program instructions 41 (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0209] This application is described with reference to flowchart illustrations and / or block diagrams of a power grid circuit fault detection method, a power grid circuit fault detection device 10, a power grid circuit fault detection device 10A, a server 20, a computer-readable storage medium 30, or a computer program product 40 according to embodiments of this application. It should be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by the computer program product 40. These computer program products 40 can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing device to produce a machine, such that program instructions 41, executable by the processor of the computer or other programmable data processing device, generate instructions for implementing the fault detection method in the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0210] These computer program products 40 may also be stored in a computer-readable storage medium capable of directing a computer or other programmable data processing device to function in a particular manner, such that program instructions 41 stored in the computer program product 40 produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0211] These program instructions 41 may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing the program instructions 41 that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0212] It should be noted that the above-mentioned methods for generating resource files, methods for disclosing resource files, resource file generation apparatus 10, resource file disclosure apparatus 10A, server 20, computer-readable storage medium 30, computer program product 40, etc., may include other implementation methods according to the description of the method embodiments. The specific implementation methods can be referred to the description of the relevant method embodiments, and will not be elaborated here.

[0213] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This disclosure is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the claims.

[0214] It should be understood that this disclosure 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 this disclosure is limited only by the appended claims.

Claims

1. A ground fault location method utilizing the transient and steady-state characteristics of PT cable grounding current, characterized in that, The method includes: Multiple current setting values ​​are obtained corresponding to multiple preset points in the power grid circuit; the power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation, the PT cables being the wiring cables of voltage transformers, each preset point belonging to a cable point of a branch circuit in the power grid circuit, and different preset points belonging to different branch circuits; the current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded; and Based on the branch parameters of the branch circuit corresponding to each preset point, the instantaneous current value of each preset point is determined; the branch parameters include cable parameters and capacitance parameters. Based on the steady-state characteristics corresponding to the multiple current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point, it is determined whether there is a ground fault in the power grid circuit; the ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit; The acquisition of multiple current setting values ​​corresponding to multiple preset points in the power grid circuit includes: The first zero-sequence current value leaked by the PT cable when grounded, the second zero-sequence current value leaked by the outdoor control circuit in the power grid circuit when grounded, and the third zero-sequence current value leaked by the indoor control circuit in the power grid circuit when grounded are obtained. The first zero-sequence current value is used as the first current setting value among the plurality of preset points, the second zero-sequence current value is used as the second current setting value among the plurality of preset points, and the third zero-sequence current value is used as the third current setting value among the plurality of preset points. The branch circuit includes a branch circuit connecting the plurality of secondary windings, a first branch circuit belonging to the first secondary winding, a second branch circuit belonging to the second secondary winding, and a third branch circuit belonging to the third secondary winding; the branch circuit is an outdoor control circuit located in the power grid circuit, and the first branch circuit, the second branch circuit, and the third branch circuit are all indoor control circuits located in the power grid circuit. The determination of whether a ground fault exists in each branch circuit based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point includes: If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all less than the steady-state amplitude characteristics of the third current setting value, and are all greater than the first current setting value, then there is no grounding fault in each of the power grid circuits. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the second current setting value, then there is a grounding fault in the outdoor control circuit in the power grid circuit. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value, and are all less than the steady-state amplitude characteristics of the second current setting value, then the first branch circuit in the power grid circuit has a ground fault. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the second branch circuit and the third branch circuit are equal and are all greater than the instantaneous current value corresponding to the first branch circuit, then the second branch circuit in the power grid circuit has a ground fault. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the first branch circuit and the second branch circuit are equal and are all less than the instantaneous current value corresponding to the third branch circuit, then the third branch circuit in the power grid circuit has a grounding fault.

2. The method according to claim 1, characterized in that, The cable parameters include the cable length and resistance value corresponding to each of the branch circuits; the capacitance parameters include the capacitance value corresponding to the capacitor in each of the branch circuits, and the angular frequency and angular velocity generated by the capacitor after being connected to the AC power of the mains circuit. The step of determining the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point includes: Based on the input voltage value of the AC power connected to the power grid circuit and the angular frequency and angular velocity of the capacitors set in each of the branch circuits, the instantaneous voltage values ​​corresponding to the plurality of preset points are determined. Based on the derivative relationship between the capacitance value, cable length, and resistance value in each branch circuit and the instantaneous voltage value corresponding to each of the multiple preset points, the instantaneous current value corresponding to each preset point in the branch circuit is determined.

3. The method according to claim 1, characterized in that, The method further includes: Based on the branch parameters corresponding to the first branch circuit, the second branch circuit, and the third branch circuit, determine the instantaneous value of the first zero-sequence voltage when the first branch circuit has a ground fault, the instantaneous value of the second zero-sequence voltage when the second branch circuit has a ground fault, and the instantaneous value of the third zero-sequence voltage when the third branch circuit has a ground fault. Time-domain analysis is performed on the first instantaneous value of zero-sequence voltage, the second instantaneous value of zero-sequence voltage, and the third instantaneous value of zero-sequence voltage respectively to obtain the first transient waveform data of zero-sequence current corresponding to the first instantaneous value of zero-sequence voltage, the second transient waveform data of zero-sequence current corresponding to the second instantaneous value of zero-sequence voltage, and the third transient waveform data of zero-sequence current corresponding to the third instantaneous value of zero-sequence voltage. The first zero-sequence current transient waveform data, the second zero-sequence current transient waveform data, and the third zero-sequence current transient waveform data are all subjected to wavelet packet decomposition, meanization, and exponentiation respectively to obtain the first feature data corresponding to the first zero-sequence current transient waveform data, the second feature data corresponding to the second zero-sequence current transient waveform data, and the third feature data corresponding to the third zero-sequence current transient waveform data. Based on the magnitudes of the first feature data, the second feature data, and the third feature data relative to their respective preset threshold values, it is determined whether a grounding fault exists in the first branch circuit, the second branch circuit, and the third branch circuit.

4. The method according to claim 3, characterized in that, The process of sequentially performing wavelet packet decomposition, mean averaging, and exponentiation on the first, second, and third zero-sequence current transient waveform data, respectively, yields first feature data corresponding to the first zero-sequence current transient waveform data, second feature data corresponding to the second zero-sequence current transient waveform data, and third feature data corresponding to the third zero-sequence current transient waveform data, including: Each zero-sequence current transient waveform data is processed by wavelet packet decomposition to separate the first characteristic value corresponding to the 6th harmonic of each zero-sequence current transient waveform data. The first feature value of each zero-sequence current transient waveform data is centered in a preset period to obtain the second feature value corresponding to each zero-sequence current transient waveform data. The second characteristic value of each zero-sequence current transient waveform data is averaged to obtain the third characteristic value corresponding to each zero-sequence current transient waveform data. The third characteristic value of each zero-sequence current transient waveform data is multiplied by four powers to obtain the fourth characteristic value corresponding to each zero-sequence current transient waveform data.

5. A ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current, characterized in that, The device includes: The data acquisition unit is configured to acquire multiple current setting values ​​corresponding to multiple preset points in the power grid circuit; the power grid circuit is a secondary circuit formed by connecting PT cables and multiple secondary windings in a substation, the PT cables are the wiring cables of voltage transformers, each preset point belongs to a cable point of a branch circuit in the power grid circuit, and different preset points belong to different cable points of different branch circuits; the current setting value is used to characterize the zero-sequence current value leaked when the branch circuit corresponding to the preset point is grounded; The current determination unit is configured to determine the instantaneous current value of each preset point based on the branch parameters of the branch circuit corresponding to each preset point; the branch parameters include cable parameters and capacitance parameters. The fault detection unit is configured to perform a determination based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​of each preset point to determine whether there is a ground fault in the power grid circuit; the ground fault is used to characterize the presence of a cable point abnormally connected to the ground in the power grid circuit; The ground fault location device utilizing the transient and steady-state characteristics of PT cable grounding current is used for: The first zero-sequence current value leaked by the PT cable when grounded, the second zero-sequence current value leaked by the outdoor control circuit in the power grid circuit when grounded, and the third zero-sequence current value leaked by the indoor control circuit in the power grid circuit when grounded are obtained. The first zero-sequence current value is used as the first current setting value among the plurality of preset points, the second zero-sequence current value is used as the second current setting value among the plurality of preset points, and the third zero-sequence current value is used as the third current setting value among the plurality of preset points. The branch circuit includes a branch circuit connecting the plurality of secondary windings, a first branch circuit belonging to the first secondary winding, a second branch circuit belonging to the second secondary winding, and a third branch circuit belonging to the third secondary winding; the branch circuit is an outdoor control circuit located in the power grid circuit, and the first branch circuit, the second branch circuit, and the third branch circuit are all indoor control circuits located in the power grid circuit. In determining whether a ground fault exists in each branch circuit based on the steady-state characteristics corresponding to the plurality of current setting values ​​and the transient characteristics corresponding to the instantaneous current values ​​at each preset point, the ground fault location device utilizing the transient and steady-state characteristics of the PT cable grounding current is used for: If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all less than the steady-state amplitude characteristics of the third current setting value, and are all greater than the first current setting value, then there is no grounding fault in each of the power grid circuits. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the second current setting value, then there is a grounding fault in the outdoor control circuit in the power grid circuit. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value, and are all less than the steady-state amplitude characteristics of the second current setting value, then the first branch circuit in the power grid circuit has a ground fault. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the second branch circuit and the third branch circuit are equal and are all greater than the instantaneous current value corresponding to the first branch circuit, then the second branch circuit in the power grid circuit has a ground fault. If the transient amplitude characteristics of the instantaneous current values ​​corresponding to the first branch circuit, the second branch circuit, and the third branch circuit are all greater than the steady-state amplitude characteristics of the third current setting value and are all less than the steady-state amplitude characteristics of the second current setting value, and the instantaneous current values ​​corresponding to the first branch circuit and the second branch circuit are equal and are all less than the instantaneous current value corresponding to the third branch circuit, then the third branch circuit in the power grid circuit has a grounding fault.

6. A server, characterized in that, include: processor; Memory for storing the executable instructions of the processor; The processor is configured to execute the executable instructions to implement the ground fault location method using the transient and steady-state characteristics of the grounding current of a PT cable as described in any one of claims 1 to 4.

7. A computer-readable storage medium comprising a computer program, characterized in that, When the computer program is executed by the server's processor, the server is able to perform the ground fault location method using the transient and steady-state characteristics of the grounding current of a PT cable as described in any one of claims 1 to 4.

8. A computer program product, the computer program product comprising program instructions, characterized in that, When the program instructions are executed by the server's processor, the server is able to perform the ground fault location method using the transient and steady-state characteristics of the grounding current of a PT cable as described in any one of claims 1 to 4.

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