Method, device, equipment and medium for extracting resistive current of metal oxide arrester

Abstract

The present application relates to the technical field of arrester detection, and discloses a method, device, equipment and medium for extracting resistive current of a metal oxide arrester. In this method, ideal voltage data and ideal current data are first obtained, standard resistive current and standard capacitive current are determined, and the wavelet packet tree method is used to calculate the resistive current and capacitive current, and the target wavelet packet basis is further determined. Then, actual voltage data and actual current data are obtained. After removing white noise, according to the target wavelet packet basis, the harmonics in the high and low frequencies are reconstructed to determine the resistive current of each harmonic, and finally the total resistive current is determined. The present application uses wavelet packets for harmonic analysis of each order, overcomes the defect of frequency aliasing of Fourier transform, and effectively improves the accuracy of extracting the resistive current of metal oxide arresters.

Description

Technical Field

[0001] The present application relates to the technical field of arrester detection, and particularly to a method, device, equipment and medium for extracting resistive current of a metal oxide arrester. Background Art

[0002] Metal oxide arresters (MOAs) are widely used in the protection of lightning overvoltage and switching overvoltage in power systems, providing a reliable guarantee for the continuous and safe operation of the system. When operating online, metal oxide arresters are not only threatened by lightning overvoltage, switching overvoltage, etc., but also affected by external environmental factors such as temperature, humidity, chemical pollution, and fouling. As the operating time increases, the metal oxide arrester shows aging and deterioration phenomena, usually manifested as a decrease in the varistor voltage, an increase in the leakage current, a change in the volt-ampere characteristic curve, etc. In severe cases, thermal runaway may occur, seriously affecting the performance of the metal oxide arrester and the safety of the system.

[0003] During the online operation of the arrester, the leakage current will increase due to aging and moisture absorption. The leakage current consists of capacitive current and resistive current. Among them, the resistive component in the leakage current of the metal oxide arrester can well reflect the aging condition of the metal oxide arrester. However, there are harmonic voltages and various noises in the actual power grid, so the resistive current of the metal oxide arrester cannot be accurately extracted. Summary of the Invention

[0004] The present application discloses a method, device, equipment and medium for extracting resistive current of a metal oxide arrester, which is used to solve the technical problem that the extraction of resistive current of a metal oxide arrester in the prior art is inaccurate.

[0005] The first aspect of the present application discloses a method for extracting resistive current of a metal oxide arrester, including:

[0006] Obtaining ideal voltage data and ideal current data;

[0007] Determining standard resistive current and standard capacitive current according to the ideal current data;

[0008] Determining resistive current and capacitive current according to the ideal voltage data and the ideal current data;

[0009] Determining a target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current and the standard capacitive current;

[0010] Obtaining actual voltage data and actual current data;

[0011] Based on the target wavelet packet basis, reconstruct the harmonics of each order in the high and low frequencies of the actual voltage data and the actual current data, and determine the resistive current of each order of harmonic with the first peak of each order of harmonic of the actual voltage data as the comparison standard.

[0012] Determine the total resistive current according to the resistive current of each order of harmonic.

[0013] Optionally, the ideal voltage data is a 0.4-second laboratory voltage pulse data sequence, and the ideal current data is a 0.4-second laboratory current pulse sequence.

[0014] Optionally, the determining the standard resistive current and the standard capacitive current according to the ideal current data includes:

[0015] Determine the standard resistive current and the standard capacitive current according to the ideal current data and the time-domain calculation formula of the pre-constructed arrester equivalent model.

[0016] Optionally, the determining the standard resistive current and the standard capacitive current according to the ideal current data and the time-domain calculation formula of the pre-constructed arrester equivalent model includes:

[0017] Obtain the model equation, which is pre-established according to the ideal current data and the time-domain calculation formula of the arrester equivalent model;

[0018] Perform parameter estimation using the least squares method according to the model equation to determine the estimated parameters;

[0019] Determine the standard resistive current and the standard capacitive current according to the estimated parameters.

[0020] Optionally, the determining the resistive current and the capacitive current according to the ideal voltage data and the ideal current data includes:

[0021] Calculate the resistive current and the capacitive current using the wavelet packet tree method according to the ideal voltage data and the ideal current data.

[0022] Optionally, the calculating the resistive current and the capacitive current using the wavelet packet tree method according to the ideal voltage data and the ideal current data includes:

[0023] Extract the harmonic components of each order of the ideal voltage data and the ideal current data respectively using the pre-determined wavelet packet basis to determine each voltage component and each current component;

[0024] Taking the first wave peak of each voltage component as the reference, determine the phase angle between each order of voltage harmonic and each order of current harmonic;

[0025] Determine the resistive current and the capacitive current according to each current component and the phase angle.

[0026] Optionally, the determining the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current includes:

[0027] Obtain the total resistive current and the total capacitive current according to the resistive current and the capacitive current;

[0028] Determine a first error and a second error, where the first error is the error between the total resistive current and the standard resistive current, and the second error is the error between the total capacitive current and the standard capacitive current;

[0029] Determine the target wavelet packet basis, where the target wavelet packet basis is the wavelet packet basis when the sum of the first error and the second error is the smallest.

[0030] Optionally, the actual voltage data is a 0.4-second voltage pulse data sequence, and the actual current data is a 0.4-second current pulse sequence.

[0031] Optionally, before reconstructing each harmonic in the high and low frequencies of the actual voltage data and the actual current data according to the target wavelet packet basis, it further includes:

[0032] Perform white noise removal processing on the actual voltage data and the actual current data.

[0033] Optionally, the performing white noise removal processing on the actual voltage data and the actual current data includes:

[0034] Use wavelets to denoise the actual voltage data and the actual current data, with the decomposition level being 4 and the threshold function being the soft threshold. Decompose the actual voltage data and the actual current data respectively and perform white noise suppression.

[0035] Optionally, the reconstructing each harmonic in the high and low frequencies according to the target wavelet packet basis includes:

[0036] Perform target wavelet packet decomposition on the actual voltage data and the actual current data after white noise removal, extract each harmonic component from the high and low frequency bands, and reconstruct each harmonic signal.

[0037] Optionally, the determining the resistive current of each harmonic with the first peak of each harmonic of the voltage as the comparison standard includes:

[0038] With the first peak of each harmonic of the voltage as the comparison standard, determine the phase difference between each harmonic of the current waveform and the voltage waveform;

[0039] Determine the resistive current of each harmonic according to the phase difference.

[0040] The second aspect of the present application discloses a device for extracting the resistive current of a metal oxide arrester. The device for extracting the resistive current of a metal oxide arrester is applied to the method for extracting the resistive current of a metal oxide arrester disclosed in the first aspect of the present application. The device for extracting the resistive current of a metal oxide arrester includes:

[0041] An ideal data acquisition module for acquiring ideal voltage data and ideal current data;

[0042] A standard data determination module for determining the standard resistive current and the standard capacitive current according to the ideal current data;

[0043] A resistive current and capacitive current determination module for determining the resistive current and the capacitive current according to the ideal voltage data and the ideal current data;

[0044] A target wavelet packet basis determination module for determining the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current;

[0045] An actual data acquisition module for acquiring actual voltage data and actual current data;

[0046] A harmonic reconstruction module for reconstructing each harmonic of the actual voltage data and the actual current data according to the target wavelet packet basis, and determining the resistive current of each harmonic with the first peak of each harmonic of the actual voltage data as the comparison standard;

[0047] A total resistive current determination module for determining the total resistive current according to the resistive current of each harmonic.

[0048] The third aspect of the present application discloses a device for extracting the resistive current of a metal oxide arrester, including a memory and a processor. The memory stores a computer program, and the processor executes the method for extracting the resistive current of a metal oxide arrester as described in the first aspect.

[0049] The fourth aspect of the present application discloses a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the processor executes the method for extracting the resistive current of a metal oxide arrester as described in the first aspect.

[0050] The present application relates to the technical field of arrester detection, and discloses a method, device, equipment and medium for extracting resistive current of a metal oxide arrester. In this method, first, ideal voltage data and ideal current data are obtained, standard resistive current and standard capacitive current are determined, and wavelet packet tree method is used to calculate the resistive current and capacitive current, and the target wavelet packet basis is further determined. Then, actual voltage data and actual current data are obtained, and after removing white noise, according to the target wavelet packet basis, each harmonic in the high and low frequencies is reconstructed to determine the resistive current of each harmonic, and finally the total resistive current is determined. The present application uses wavelet packets for harmonic analysis, overcomes the defect of frequency aliasing of Fourier transform, and effectively improves the accuracy of extracting the resistive current of metal oxide arresters. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the technical solutions of the present application, the accompanying drawings required for the embodiments will be briefly introduced below. Obviously, for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0052] Figure 1 FIG. is a schematic flowchart of the working process of a method for extracting resistive current of a metal oxide arrester disclosed in an embodiment of the present application;

[0053] Figure 2 FIG. is a schematic waveform diagram after extracting the resistive current in a method for extracting resistive current of a metal oxide arrester disclosed in an embodiment of the present application;

[0054] Figure 3 FIG. is a schematic structural diagram of a device for extracting resistive current of a metal oxide arrester disclosed in an embodiment of the present application.

[0055] Figure 4 FIG. is a structural block diagram of a device for extracting resistive current of a metal oxide arrester disclosed in an embodiment of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0056] In order to solve the technical problem of inaccurate extraction of resistive current of metal oxide arresters in the prior art, the present application discloses a method, device, equipment and medium for extracting resistive current of metal oxide arresters through the following embodiments.

[0057] The first embodiment of the present application discloses a method for extracting resistive current of a metal oxide arrester. Refer to Figure 1 the schematic flowchart of the working process shown, the method for extracting resistive current of the metal oxide arrester includes:

[0058] Step S1, obtain ideal voltage data and ideal current data.

[0059] Further, the ideal voltage data is a 0.4-second laboratory voltage pulse data sequence, and the ideal current data is a 0.4-second laboratory current pulse sequence. Specifically, collect a 0.4-second laboratory voltage pulse data sequence U (i), current pulse sequence I (i).

[0060] Step S2, determine the standard resistive current and the standard capacitive current according to the ideal current data.

[0061] In some embodiments of the present application, the determining the standard resistive current and the standard capacitive current according to the ideal current data includes:

[0062] Determine the standard resistive current and the standard capacitive current according to the ideal current data and the pre-constructed time-domain calculation formula of the arrester equivalent model.

[0063] Further, the determining the standard resistive current and the standard capacitive current according to the ideal current data and the pre-constructed time-domain calculation formula of the arrester equivalent model includes:

[0064] Obtain the model equation, which is pre-established according to the ideal current data and the time-domain calculation formula of the arrester equivalent model.

[0065] According to the model equation, use the least squares method for parameter estimation to determine the estimated parameters.

[0066] According to the estimated parameters, determine the standard resistive current and the standard capacitive current.

[0067] Specifically, estimate the capacitance and resistance parameters of the equivalent circuit model, and calculate the standard resistive current and the standard capacitive current based on the circuit parameters. First, establish the time-domain calculation formula of the arrester equivalent model, then establish the model equation based on the current signal collected in the laboratory and the fitting data of the equivalent circuit, further perform parameter estimation based on the least squares method, and finally calculate the standard resistive current I R , standard capacitive current I C .

[0068] Step S3, determine the resistive current and the capacitive current according to the ideal voltage data and the ideal current data.

[0069] In some embodiments of the present application, the determining the resistive current and the capacitive current according to the ideal voltage data and the ideal current data includes:

[0070] Calculate the resistive current and the capacitive current by using the wavelet packet tree method according to the ideal voltage data and the ideal current data.

[0071] Further, calculating the resistive current and the capacitive current by using the wavelet packet tree method according to the ideal voltage data and the ideal current data includes:

[0072] Extracting the harmonic components of the ideal voltage data and the ideal current data respectively by using a pre-determined wavelet packet basis to determine each voltage component and each current component.

[0073] Taking the first wave peak of each voltage component as a reference to determine the phase angle between each voltage harmonic and each current harmonic.

[0074] Determining the resistive current and the capacitive current according to each current component and the phase angle.

[0075] Specifically, different wavelet packet bases are selected to extract the harmonic components of the collected laboratory voltage pulse data sequence U (i), current pulse sequence I (i) respectively to obtain U k1 (i), U k3 (i), U k5 (i)..., I k1 (i), I k2 (i), I k5 (i)...; taking the first wave peak of each voltage component as a reference to calculate the phase angle between each voltage harmonic and each current harmonic ψ kj ; according to the formula I Rkj I(i)= I kj I(i)*cos( ψ kj ) to calculate the resistive current, and according to the formula I Ckj I(i)= I kj I(i)*sin( ψ kj ) to calculate the capacitive current.

[0076] Step S4, determining the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current.

[0077] In some embodiments of the present application, determining the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current includes:

[0078] Obtain the total resistive current and the total capacitive current according to the resistive current and the capacitive current.

[0079] Determine a first error and a second error, where the first error is the error between the total resistive current and the standard resistive current, and the second error is the error between the total capacitive current and the standard capacitive current;

[0080] Determine a target wavelet packet basis, where the target wavelet packet basis is the wavelet packet basis when the sum of the first error and the second error is the smallest.

[0081] Specifically, calculate the total resistive current according to the resistive current of each harmonic and the capacitive current of each harmonic I Rk , the total capacitive current I Ck ; calculate the first error I R ε k= I Rk - I R , the second error I C ε k= I Ck - I C , and select the wavelet packet basis when the sum of the errors is the smallest ψ .

[0082] Step S5, obtain actual voltage data and actual current data.

[0083] Furthermore, the actual voltage data is a 0.4-second voltage pulse data sequence, and the actual current data is a 0.4-second current pulse sequence. Specifically, in actual use, collect a 0.4-second voltage pulse data sequence U 1(i), current pulse sequence I 1(i).

[0084] Step S6, according to the target wavelet packet basis, reconstruct each harmonic in the high and low frequencies of the actual voltage data and the actual current data, and determine the resistive current of each harmonic with the first peak value of each harmonic of the actual voltage data as the comparison standard.

[0085] In some embodiments of the present application, before reconstructing each harmonic in the high and low frequencies of the actual voltage data and the actual current data according to the target wavelet packet basis, it further includes:

[0086] Perform white noise removal processing on the actual voltage data and the actual current data.

[0087] Further, the processing of removing white noise from the actual voltage data and the actual current data includes:

[0088] Wavelet is used to denoise the actual voltage data and the actual current data, the decomposition level is 4, the threshold function is the soft threshold, the actual voltage data and the actual current data are decomposed respectively, and white noise suppression is performed.

[0089] Specifically, software is used to remove white noise, and wavelet is used to process the voltage signal U 1(i), current signal I 1(i) for denoising, the decomposition level is selected as 4, the threshold function is the soft threshold, the signals are decomposed respectively, and white noise suppression is performed on the decomposed signals.

[0090] In some embodiments of the present application, the reconstruction of each harmonic in the high and low frequencies according to the target wavelet packet basis includes:

[0091] The actual voltage data and the actual current data after removing white noise are decomposed by the target wavelet packet, and each harmonic component is extracted from the high and low frequency bands and each harmonic signal is reconstructed.

[0092] Specifically, the filtered voltage and current signals are decomposed by the selected target wavelet packet, and each harmonic component is extracted from the high and low frequency bands and each harmonic signal is reconstructed. The decomposition level is selected as 3 layers. According to the frequency bands where the resistive current harmonics are located: the fundamental wave is at 0 - 75 Hz, the 3rd harmonic is at 75 - 150 Hz, etc., based on the system sampling rate, the frequency bands after wavelet packet decomposition where the harmonics are located are respectively selected to reconstruct the harmonic signals.

[0093] In some embodiments of the present application, determining the resistive current of each harmonic with the first peak of each harmonic of the voltage as the comparison standard includes:

[0094] With the first peak of each harmonic of the voltage as the comparison standard, determine the phase difference between each harmonic of the current waveform and the voltage waveform.

[0095] According to the phase difference, determine the resistive current of each harmonic.

[0096] Step S7, determine the total resistive current according to the resistive current of each harmonic.

[0097] Specifically, taking the first peak P 1 of the time domain waveform of each harmonic of the voltage as the comparison standard, calculate the phase difference between each harmonic of the current waveform and the voltage waveform, and then calculate the resistive current of each harmonic I R1 、 I R3、I R5 ,..., and finally obtain the total resistive current I R = I R1 + I R3 + ....

[0098] In this embodiment, starting from the principle of the equivalent circuit model of the lightning arrester, the target wavelet packet basis is selected and only the harmonic signals of each order are reconstructed, so that the resistive current of the metal oxide lightning arrester can be accurately extracted.

[0099] See Figure 2 , which is a schematic diagram of the waveform after the resistive current is extracted.

[0100] A method for extracting the resistive current of a metal oxide lightning arrester disclosed in the above embodiment of the present application first obtains ideal voltage data and ideal current data, determines the standard resistive current and the standard capacitive current, and calculates the resistive current and the capacitive current by using the wavelet packet tree method, and further determines the target wavelet packet basis. Then, the actual voltage data and the actual current data are obtained, and after removing the white noise, according to the target wavelet packet basis, the harmonics of each order in the high and low frequencies are reconstructed to determine the resistive current of each order, and finally the total resistive current is determined. The present application uses wavelet packets to perform harmonic analysis of each order, overcomes the defect of frequency aliasing of Fourier transform, and starting from the principle of the equivalent circuit model of the lightning arrester, selects the target wavelet packet basis and only reconstructs the harmonic signals of each order, so that the resistive current of the metal oxide lightning arrester can be accurately extracted.

[0101] It should be understood that although Figure 1 the steps in the flowchart of Figure 1 are shown in sequence according to the indication of the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless there is a clear indication in this article, the execution of these steps has no strict order limit, and these steps can be executed in other orders. Moreover,

[0102] At least a part of the steps in

[0103] The second embodiment of the present application discloses a device for extracting resistive current of a metal oxide arrester. The device for extracting resistive current of the metal oxide arrester is applied to the method for extracting resistive current of the metal oxide arrester disclosed in the first embodiment of the present application. Refer to Figure 3 the structural schematic diagram shown in

[0104] The ideal data acquisition module 10 is configured to acquire ideal voltage data and ideal current data;

[0105] The standard data determination module 20 is configured to determine standard resistive current and standard capacitive current according to the ideal current data;

[0106] The resistive current and capacitive current determination module 30 is configured to determine resistive current and capacitive current according to the ideal voltage data and the ideal current data;

[0107] The target wavelet packet basis determination module 40 is configured to determine a target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current;

[0108] The actual data acquisition module 50 is configured to acquire actual voltage data and actual current data;

[0109] The harmonic reconstruction module 60 is configured to reconstruct each harmonic of the actual voltage data and the actual current data according to the target wavelet packet basis, and determine the resistive current of each harmonic with the first peak of each harmonic of the actual voltage data as a comparison standard;

[0110] The total resistive current determination module 70 is configured to determine the total resistive current according to the resistive current of each harmonic.

[0111] Optionally, the ideal voltage data is a 0.4-second laboratory voltage pulse data sequence, and the ideal current data is a 0.4-second laboratory current pulse sequence.

[0112] Optionally, the standard data determination module 20 is configured to: determine standard resistive current and standard capacitive current according to the ideal current data and a time-domain calculation formula of a pre-constructed arrester equivalent model.

[0113] Optionally, the standard data determination module 20 includes:

[0114] The model equation pre-establishment unit is configured to acquire a model equation, and the model equation is pre-established according to the ideal current data and the time-domain calculation formula of the arrester equivalent model;

[0115] The estimated parameter determination unit is configured to perform parameter estimation using the least squares method according to the model equation to determine estimated parameters;

[0116] A standard current determination unit for determining the standard resistive current and the standard capacitive current according to the estimated parameters.

[0117] Optionally, the resistive current and capacitive current determination module 30 is configured to: calculate the resistive current and the capacitive current according to the ideal voltage data and the ideal current data by using the wavelet packet tree method.

[0118] Optionally, the resistive current and capacitive current determination module 30 includes:

[0119] A component determination unit for respectively extracting each harmonic component of the ideal voltage data and the ideal current data by using a pre-determined wavelet packet basis to determine each voltage component and each current component;

[0120] A phase angle determination unit for determining the phase angle between each voltage harmonic and each current harmonic with the first wave peak of each voltage component as a reference;

[0121] A current determination unit for determining the resistive current and the capacitive current according to each current component and the phase angle.

[0122] Optionally, the target wavelet packet basis determination module 40 includes:

[0123] A total current determination unit for obtaining the total resistive current and the total capacitive current according to the resistive current and the capacitive current;

[0124] An error determination unit for determining a first error and a second error, where the first error is the error between the total resistive current and the standard resistive current, and the second error is the error between the total capacitive current and the standard capacitive current;

[0125] A target wavelet packet basis determination unit for determining a target wavelet packet basis, where the target wavelet packet basis is the wavelet packet basis when the sum of the first error and the second error is the smallest.

[0126] Optionally, the actual voltage data is a 0.4-second voltage pulse data sequence, and the actual current data is a 0.4-second current pulse sequence.

[0127] Optionally, the harmonic reconstruction module 60 is further configured to: perform white noise removal processing on the actual voltage data and the actual current data before reconstructing each harmonic in the high and low frequencies of the actual voltage data and the actual current data according to the target wavelet packet basis.

[0128] Optionally, the harmonic reconstruction module 60 is configured to: denoise the actual voltage data and the actual current data by using wavelets, with the decomposition level being 4 and the threshold function being the soft threshold, decompose the actual voltage data and the actual current data respectively, and suppress white noise.

[0129] Optionally, the harmonic reconstruction module 60 is configured to: perform target wavelet packet decomposition on the actual voltage data and the actual current data after removing white noise, extract harmonic components of each order from high and low frequency bands, and reconstruct harmonic signals of each order.

[0130] Optionally, the harmonic reconstruction module 60 includes:

[0131] a phase difference determination unit, configured to determine the phase difference between the harmonic components of the current waveform and the voltage waveform by using the first peak of each harmonic of the voltage as a comparison standard;

[0132] a resistive current determination unit for each harmonic, configured to determine the resistive current of each harmonic according to the phase difference.

[0133] The following is an apparatus embodiment of the present application, which can be used to execute the method embodiment of the present application. For details not disclosed in the apparatus embodiment of the present application, please refer to the method embodiment of the present application.

[0134] In one embodiment, a computer device is provided. The computer device may be a server, and its internal structure diagram may be as Figure 4 shown. The computer device includes a processor, a memory, and a network interface connected through a system bus. Among them, the processor of the computer device is used to provide computing and control capabilities. The memory of the computer device includes a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system, a computer program, and a database. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The database of the computer device is used to store data. The network interface of the computer device is used to communicate with an external terminal through a network connection. When the computer program is executed by the processor, it implements a method for extracting the resistive current of a metal oxide arrester.

[0135] In one embodiment, an apparatus for extracting the resistive current of a metal oxide arrester is disclosed, including a memory and a processor. The memory stores a computer program, and the processor executes the method for extracting the resistive current of a metal oxide arrester as described in the first embodiment.

[0136] The following is a medium embodiment of the present application, which can be used to execute the method embodiment of the present application. For details not disclosed in the medium embodiment of the present application, please refer to the method embodiment of the present application.

[0137] In one embodiment, a computer-readable storage medium is disclosed, on which a computer program is stored. When the computer program is executed by a processor, the processor is caused to execute the method for extracting the resistive current of a metal oxide arrester as described in the first embodiment.

[0138] Those of ordinary skill in the art can understand that all or part of the processes in the above-described embodiment methods can be completed by instructing relevant hardware through a computer program. The computer program can be stored in a non-volatile computer-readable storage medium. When the computer program is executed, it can include the processes of the above-described method embodiments. Among them, any reference to a memory, storage, database, or other medium used in the various embodiments provided in the present application can include at least one of non-volatile and volatile memories. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, or optical memory, etc. Volatile memory can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc.

[0139] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the various technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0140] The present application has been described in detail above in conjunction with specific embodiments and exemplary examples. However, these descriptions should not be construed as limiting the present application. Those skilled in the art understand that without departing from the spirit and scope of the present application, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present application, and these all fall within the scope of the present application. The protection scope of the present application is subject to the appended claims.

Claims

1. A method for extracting resistive current of a metal oxide arrester, characterized in that, it includes: Obtain ideal voltage data and ideal current data; Determine the standard resistive current and the standard capacitive current according to the ideal current data; Determine the resistive current and the capacitive current according to the ideal voltage data and the ideal current data; Determine the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current and the standard capacitive current; Obtain actual voltage data and actual current data; According to the target wavelet packet basis, reconstruct each harmonic in the high and low frequencies of the actual voltage data and the actual current data, and determine the resistive current of each harmonic with the first peak value of each harmonic of the actual voltage data as the comparison standard; Determine the total resistive current according to the resistive current of each harmonic; The determining the target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current and the standard capacitive current includes: Obtain the total resistive current and the total capacitive current according to the resistive current and the capacitive current; Determine the first error and the second error, where the first error is the error between the total resistive current and the standard resistive current, and the second error is the error between the total capacitive current and the standard capacitive current; Determine the target wavelet packet basis, where the target wavelet packet basis is the wavelet packet basis when the sum of the first error and the second error is the smallest.

2. The method for extracting resistive current of a metal oxide arrester according to claim 1, characterized in that, The ideal voltage data is a 0.4-second laboratory voltage pulse data sequence, and the ideal current data is a 0.4-second laboratory current pulse sequence.

3. The method for extracting resistive current of a metal oxide arrester according to claim 1, characterized in that, The determining the standard resistive current and the standard capacitive current according to the ideal current data includes: Determine the standard resistive current and the standard capacitive current according to the ideal current data and the time-domain calculation formula of the pre-constructed arrester equivalent model.

4. The method for extracting resistive current of a metal oxide arrester according to claim 3, characterized in that, The determining the standard resistive current and the standard capacitive current according to the ideal current data and the time-domain calculation formula of the pre-constructed arrester equivalent model includes: Obtain the model equation, which is pre-established according to the ideal current data and the time-domain calculation formula of the arrester equivalent model; Perform parameter estimation using the least squares method according to the model equation to determine the estimated parameters; Determine the standard resistive current and the standard capacitive current according to the estimated parameters.

5. The method for extracting resistive current of a metal oxide arrester according to claim 1, characterized in that, The determining the resistive current and the capacitive current according to the ideal voltage data and the ideal current data includes: Calculate the resistive current and the capacitive current using the wavelet packet tree method according to the ideal voltage data and the ideal current data.

6. The method for extracting resistive current of a metal oxide arrester according to claim 5, characterized in that, Calculating the resistive current and capacitive current according to the ideal voltage data and the ideal current data by using the wavelet packet tree method includes: Using a pre-determined wavelet packet basis to extract the harmonic components of the ideal voltage data and the ideal current data respectively, and determining each voltage component and each current component; Taking the first wave peak of each voltage component as a reference to determine the phase angle between each voltage harmonic and each current harmonic; Determining the resistive current and the capacitive current according to each current component and the phase angle.

7. The method for extracting the resistive current of a metal oxide arrester according to claim 1, wherein, the actual voltage data is a 0.4-second voltage pulse data sequence, and the actual current data is a 0.4-second current pulse sequence.

8. The method for extracting the resistive current of a metal oxide arrester according to claim 1, wherein, before reconstructing each harmonic in the high and low frequencies of the actual voltage data and the actual current data according to the target wavelet packet basis, it further includes: Performing white noise removal processing on the actual voltage data and the actual current data.

9. The method for extracting the resistive current of a metal oxide arrester according to claim 8, wherein, the performing white noise removal processing on the actual voltage data and the actual current data includes: Using wavelets to denoise the actual voltage data and the actual current data, with the decomposition level being 4 and the threshold function being the soft threshold. Decompose the actual voltage data and the actual current data respectively, and perform white noise suppression.

10. The method for extracting the resistive current of a metal oxide arrester according to claim 1, wherein, the reconstructing each harmonic in the high and low frequencies according to the target wavelet packet basis includes: Performing target wavelet packet decomposition on the actual voltage data and the actual current data after white noise removal, extracting each harmonic component from the high and low frequency bands, and reconstructing each harmonic signal.

11. The method for extracting the resistive current of a metal oxide arrester according to claim 1, wherein, the determining the resistive current of each harmonic with the first peak of each harmonic of the actual voltage data as a comparison standard includes: Taking the first peak of each voltage harmonic as a comparison standard to determine the phase difference between each harmonic of the current waveform and the voltage waveform; Determining the resistive current of each harmonic according to the phase difference.

12. An apparatus for extracting the resistive current of a metal oxide arrester, wherein, using the method according to any one of claims 1 to 11, the apparatus for extracting the resistive current of a metal oxide arrester includes: An ideal data acquisition module for acquiring ideal voltage data and ideal current data; A standard data determination module for determining a standard resistive current and a standard capacitive current according to the ideal current data; A resistive current and capacitive current determination module for determining a resistive current and a capacitive current according to the ideal voltage data and the ideal current data; A target wavelet packet basis determination module, configured to determine a target wavelet packet basis according to the resistive current, the capacitive current, the standard resistive current, and the standard capacitive current; An actual data acquisition module, configured to acquire actual voltage data and actual current data; A harmonic reconstruction module, configured to reconstruct each harmonic of the actual voltage data and the actual current data according to the target wavelet packet basis, and determine the resistive current of each harmonic by using the first peak value of each harmonic of the actual voltage data as a comparison standard; A total resistive current determination module, configured to determine a total resistive current according to the resistive currents of each harmonic.

13. An extraction device for the resistive current of a metal oxide arrester, comprising a memory and a processor, characterized in that the memory stores a computer program, and the processor executes the method for extracting the resistive current of the metal oxide arrester according to any one of claims 1-11.

14. A computer-readable storage medium, on which a computer program is stored, characterized in that when the computer program is executed by a processor, the processor is caused to execute the method for extracting the resistive current of the metal oxide arrester according to any one of claims 1-11.

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