Mains-frequency current transformer-based high-frequency discharge signal detection apparatus and method

Abstract

The present application provides a mains-frequency current transformer-based high-frequency discharge signal detection apparatus and method, applicable in the field of power device online monitoring. The apparatus comprises a signal acquisition module and a signal processing module; the signal processing module comprises a frequency divider circuit and an intelligent device; the signal acquisition module is arranged on a secondary junction box of a mains-frequency current transformer of a transformer and is connected to the frequency divider circuit, the signal acquisition module is configured to acquire a signal of the transformer and transmit the signal to the frequency divider circuit, and the signal comprises a mains-frequency signal and a high-frequency discharge signal; the frequency divider circuit is connected to the intelligent device, and the frequency divider circuit is configured to separate the mains-frequency signal from the high-frequency discharge signal and transmit the high-frequency discharge signal to the intelligent device; and the intelligent device is configured to analyze the high-frequency discharge signal.

Description

A high-frequency discharge signal detection device and method based on power frequency current transformer

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on January 10, 2024, with application number 202410034550.9, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of online monitoring of electrical equipment, for example, to a high-frequency discharge signal detection device and method based on an industrial frequency current transformer. Background Art

[0003] Transformers are core equipment in power grids. However, in recent years, numerous transformer explosion accidents have occurred, seriously affecting the reliable supply of electricity and the safety of the power grid, causing huge economic losses and adverse social impacts, and becoming a major hidden danger in the power system. Such accidents are caused by internal insulation failures in the transformer, which gradually develop from local discharge to insulation breakdown, ultimately generating huge discharge energy, causing the transformer to explode. The transformer differential protection in related technologies only activates after a significant short-circuit current appears, and gas protection only activates after rapid oil flow caused by insulation breakdown. The main protection is not activated until insulation breakdown occurs, which cannot effectively prevent transformer explosion accidents.

[0004] High-frequency discharge signals are commonly used for power transformer fault detection. In related technologies, as shown in Figure 14, sensors for high-frequency partial discharge online monitoring are mostly located in the core or clamps. This results in relatively poor discharge coupling characteristics for bushings and high-voltage lead-out devices, which are prone to transformer explosions. Furthermore, for measurement methods that draw signals from the bushing end shield grounding, the existing bushing end shield grounding method must be modified, which can lead to hidden dangers such as poor grounding and moisture at the bushing end shield. This modification can also easily cause new bushing failures, thereby adding additional risks to the transformer. For example, installing new sensors can reduce the stability and sealing of the end shield connection, potentially causing water ingress and moisture-damaged insulation during operation, leading to bushing explosions.

[0005] Summary of the Invention

[0006] The embodiments of the present application provide a high-frequency discharge signal detection device and method based on an industrial frequency current transformer, which avoids changes to the structure of parts such as the grounding of the transformer bushing end screen, and can at least partially solve the problems existing in the related art.

[0007] In a first aspect, the present application provides a high-frequency discharge signal detection device based on a power frequency current transformer, comprising: a signal acquisition module and a signal processing module;

[0008] The signal processing module includes a frequency division circuit and an intelligent device;

[0009] The signal acquisition module is arranged on the secondary junction box of the power frequency current transformer of the transformer and is connected to the frequency dividing circuit. It is configured to collect the signal of the transformer and transmit the signal to the frequency dividing circuit. The signal includes the power frequency signal and the high-frequency discharge signal.

[0010] The frequency dividing circuit is connected to the smart device, configured to separate the power frequency signal from the high-frequency discharge signal, and transmit the high-frequency discharge signal to the smart device;

[0011] The smart device is configured to analyze the high-frequency discharge signal.

[0012] Optionally, the smart device includes:

[0013] a polarity determination module, configured to perform polarity determination on the high-frequency discharge signal;

[0014] The position determination module is configured to determine the position where the discharge fault occurs based on the result of the polarity discrimination.

[0015] Optionally, the polarity determination module includes:

[0016] a denoising module, configured to denoise the high-frequency discharge signal;

[0017] an alignment module, configured to align high-frequency discharge signals obtained at different power frequency current transformers to obtain an alignment result;

[0018] a polarity information generating module, configured to generate polarity information according to the alignment result;

[0019] The result generating module is configured to obtain a polarity determination result according to the polarity information and a preset threshold value.

[0020] Optionally, the alignment module includes:

[0021] a factor generation submodule configured to generate weighting factors using a cross-power spectrum of high-frequency discharge signals obtained at different power frequency current transformers;

[0022] a function generation submodule, configured to generate a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signal obtained at different power frequency current transformers;

[0023] The signal alignment submodule is configured to align the high-frequency discharge signals obtained at different power frequency current transformers according to the extreme values ​​of the generalized cross-correlation function.

[0024] Optionally, the smart device further includes:

[0025] The early warning protection module is configured to perform fault early warning or protection according to the location where the discharge fault occurs.

[0026] Optionally, the signal acquisition module includes:

[0027] A signal shielding terminal is provided on the secondary junction box and is configured to prevent leakage of high-frequency signals;

[0028] A coaxial cable is connected to the signal shielding terminal and the frequency dividing circuit, and is configured to transmit the signal to the frequency dividing circuit.

[0029] Optionally, the signal shielding terminal includes a high-frequency terminal and a grounding terminal, the high-frequency terminal is provided on the common terminal of the secondary junction box, and the grounding terminal is provided on a terminal other than the common terminal of the secondary junction box.

[0030] Optionally, the high-frequency terminal includes a copper conductor layer, a polyethylene insulation layer, a copper grounding layer, a connecting bolt, an impedance matching device and a BNC connector.

[0031] Optionally, the signal acquisition module further includes: a ground connection lead, connected to the high-frequency terminal and the ground terminal, and configured to achieve signal shielding.

[0032] Optionally, the coaxial cable is a BNC coaxial cable, connecting the high-frequency terminal and the frequency division circuit.

[0033] Optionally, the frequency dividing circuit includes a first low-pass filter and a high-frequency band-pass filter connected in parallel with the first low-pass filter and consisting of a second low-pass filter and a high-pass filter;

[0034] The first low-pass filter is configured to separate the power frequency signal from the signal;

[0035] The high-frequency bandpass filter is connected to the smart device and is configured to separate the high-frequency discharge signal from the signal and transmit the high-frequency discharge signal to the smart device.

[0036] In a second aspect, the present application provides a method for detecting a high-frequency discharge signal based on a power frequency current transformer, comprising:

[0037] The signal acquisition module collects the signal of the transformer and transmits the signal to the frequency division circuit. The signal includes the power frequency signal and the high-frequency discharge signal. The signal acquisition module is arranged on the secondary junction box of the power frequency current transformer of the transformer and is connected to the frequency division circuit.

[0038] The frequency dividing circuit separates the power frequency signal from the high-frequency discharge signal, and transmits the high-frequency discharge signal to the smart device;

[0039] The smart device analyzes the high-frequency discharge signal.

[0040] Optionally, the frequency dividing circuit includes a first low-pass filter and a high-frequency band-pass filter connected in parallel with the first low-pass filter. The frequency dividing circuit separates the power frequency signal from the high-frequency discharge signal and transmits the high-frequency discharge signal to the smart device, including:

[0041] A first low-pass filter separates the power frequency signal from the signal;

[0042] The high-frequency bandpass filter separates the high-frequency discharge signal from the signal and transmits the high-frequency discharge signal to the smart device.

[0043] Optionally, the smart device analyzes the high-frequency discharge signal, including:

[0044] The intelligent device performs polarity determination on the high-frequency discharge signal;

[0045] The intelligent device determines the location where the discharge fault occurs according to the result of polarity discrimination.

[0046] Optionally, the smart device performs polarity discrimination on the high-frequency discharge signal, including:

[0047] The smart device performs denoising on the high-frequency discharge signal;

[0048] The intelligent device aligns high-frequency discharge signals obtained at different power frequency current transformers to obtain an alignment result;

[0049] The smart device generates polarity information according to the alignment result;

[0050] The smart device is configured to obtain a polarity determination result based on the polarity information and a preset threshold.

[0051] Optionally, the smart device aligns high-frequency discharge signals obtained at different power frequency current transformers, including:

[0052] The intelligent device generates a weighting factor using the cross power spectrum of high frequency discharge signals obtained at different power frequency current transformers;

[0053] The intelligent device generates a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signal obtained at different power frequency current transformers;

[0054] The intelligent device aligns the high-frequency discharge signals obtained at different power-frequency current transformers according to extreme values ​​of a generalized cross-correlation function.

[0055] Optionally, it also includes:

[0056] The intelligent device performs fault warning or protection according to the location where the discharge fault occurs. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] FIG1 is a schematic structural diagram of a high-frequency discharge signal detection device based on an industrial frequency current transformer provided in one embodiment of the present application;

[0058] FIG2 is a schematic diagram of the structure of a smart device provided in an embodiment of the present application;

[0059] FIG3 is a schematic diagram of the structure of a smart device provided in an embodiment of the present application;

[0060] FIG4 is a schematic diagram of the structure of a smart device provided in an embodiment of the present application;

[0061] FIG5 is a schematic diagram of the structure of a smart device provided in an embodiment of the present application;

[0062] FIG6 is a structural diagram of a high-frequency discharge signal detection device based on an industrial frequency current transformer provided in one embodiment of the present application;

[0063] FIG7 is a schematic structural diagram of a high-frequency terminal and a grounding terminal provided in one embodiment of the present application;

[0064] FIG8 is a schematic structural diagram of a frequency division circuit provided in one embodiment of the present application;

[0065] FIG9 is a flow chart of a method for detecting a high-frequency discharge signal based on a power frequency current transformer according to an embodiment of the present application;

[0066] FIG10 is a flow chart of a method for detecting a high-frequency discharge signal based on a power frequency current transformer according to an embodiment of the present application;

[0067] FIG11 is a flow chart of a method for detecting a high-frequency discharge signal based on a power frequency current transformer according to an embodiment of the present application;

[0068] FIG12 is a flow chart of a high-frequency discharge signal detection method based on a power frequency current transformer according to an embodiment of the present application;

[0069] FIG13 is a flow chart of a method for detecting a high-frequency discharge signal based on a power frequency current transformer according to an embodiment of the present application;

[0070] FIG14 is a schematic diagram of a high-frequency pulse current method in the related art;

[0071] FIG15 is a curve comparison of the transmission impedance of the bushing power frequency current transformer and the high frequency current transformer;

[0072] FIG16 is a schematic diagram of an internal discharge fault according to an embodiment of the present application;

[0073] FIG17 is a schematic diagram of an external discharge fault provided by an embodiment of the present application;

[0074] FIG18 is a schematic diagram of pulse polarity provided by an embodiment of the present application;

[0075] FIG19 is a schematic diagram of a process for aligning high-frequency discharge signals obtained at current transformers with different power frequencies, provided by an embodiment of the present application;

[0076] FIG20 is a schematic diagram of a flow chart of various signals collected in an alignment transformer according to an embodiment of the present application;

[0077] FIG21 is a flowchart illustrating a fault location process according to an embodiment of the present application. DETAILED DESCRIPTION

[0078] To make the purpose, technical solutions, and advantages of the embodiments of the present application more clearly understood, the embodiments of the present application are described in detail below with reference to the accompanying drawings. The illustrative embodiments of the present application and their descriptions are used to explain the present application but are not intended to limit the present application. It should be noted that, unless there is a conflict, the embodiments and features in the embodiments of the present application may be combined with each other in any manner.

[0079] In one embodiment, as shown in FIG1 , the high-frequency discharge signal detection device based on the power frequency current transformer provided by the present application includes: a signal acquisition module 101 and a signal processing module 102 .

[0080] The signal processing module 102 includes a frequency division circuit 1021 and a smart device 1022 .

[0081] The signal acquisition module 101 is set on the secondary junction box of the power frequency current transformer of the transformer and connected to the frequency division circuit 1021. It is configured to collect the signal of the transformer and transmit the signal to the frequency division circuit 1021; the signal includes the power frequency signal and the high-frequency discharge signal.

[0082] As shown in Figure 15, this application is based on the comparison curve of the transmission impedance of the bushing power frequency current transformer and the high-frequency current transformer measured in the laboratory. It is concluded that the transformer bushing power frequency current transformer used for power frequency current monitoring can obtain a high response (above 1mV / mA) in the 3-30MHz high-frequency band where the high-frequency partial discharge signal is located, which is sufficient to meet the monitoring needs of the high-frequency current caused by the partial discharge fault inside the transformer. In order to avoid the problem of poor coupling effect of the external high-frequency current transformer on the high-frequency discharge signal and the safety problems caused by the modification of the bushing end screen in the high-frequency discharge signal detection, this application proposes that the high-frequency current transformer used in the traditional partial discharge fault detection can be replaced by the transformer bushing power frequency current transformer, and the transformer high voltage, medium voltage, low voltage and neutral point are all equipped with bushing power frequency current transformers, which can perform all-round monitoring of the high-frequency discharge signal inside the transformer to protect the transformer in advance and prevent explosion.

[0083] The transformer's power-frequency current transformer senses the high-frequency discharge signal within the transformer. A signal acquisition module 101, mounted on the power-frequency current transformer, collects the high-frequency discharge signal and transmits it to a signal processing module 102 for processing. The power-frequency current transformer can obtain information such as the apparent discharge amount, discharge phase, and discharge frequency. Signal acquisition module 101 can acquire transformer signals, which are multi-band signals, including the power-frequency signal and the high-frequency discharge signal. Furthermore, signal acquisition module 101 can also transmit signals from the transformer's power-frequency current transformer terminals to the frequency divider circuit 1021.

[0084] The frequency dividing circuit 1021 is connected to the smart device 1022 , configured to separate the power frequency signal from the high-frequency discharge signal, and transmit the high-frequency discharge signal to the smart device 1022 .

[0085] Exemplarily, the frequency dividing circuit 1021 may be composed of a low-pass filter and a high-pass filter to separate the power frequency signal from the partial discharge pulse signal and process them separately.

[0086] The smart device 1022 is configured to analyze the high-frequency discharge signal.

[0087] For example, the intelligent electronic device 1022 (IED) first analyzes the high-frequency discharge signal, that is, determines the polarity of the high-frequency discharge signal, and distinguishes whether the discharge fault is an internal discharge fault or an external discharge fault according to the result of the polarity determination.

[0088] In one embodiment, as shown in FIG. 2 , the smart device 1022 includes a polarity determination module 201 and a position determination module 202 .

[0089] The polarity determination module 201 is configured to perform polarity determination on the high-frequency discharge signal.

[0090] For example, transformer discharge faults are classified into internal discharge faults and external discharge faults based on the fault location. Since the pulse current polarities generated by internal and external discharge faults in the power frequency current transformers of each transformer bushing differ, the smart device 1022 can be used to distinguish and locate internal and external faults. For example, a fault analysis is performed on a 500kV (or above 500kV) power transformer using a single-phase autocoupler, the structure of which is shown in FIG16 .

[0091] The location determination module 202 is configured to determine the location where the discharge fault occurs according to the result of the polarity determination.

[0092] For example, the transformer can include multiple power frequency current transformers, and high-frequency current monitoring can be performed simultaneously during operation. As shown in Figure 16, when an internal fault occurs, the secondary side of each winding power frequency current transformer and the secondary side of the neutral point grounding power frequency current transformer can sense partial discharge pulses, and the polarities of the two are opposite. Conversely, as shown in Figure 17, when an external fault occurs, the fault current is a through current, and the pulse polarity sensed by the winding power frequency current transformer and the neutral point grounding power frequency current transformer is the same. Based on this characteristic, the position determination module 202 can locate the discharge fault by detecting the polarity of the high-frequency discharge signal during the operation of the transformer. The same polarity pulse and the opposite polarity pulse are shown in Figure 18.

[0093] In one embodiment, as shown in FIG3 , the polarity determination module 201 includes: a denoising module 301 , an alignment module 302 , a polarity information generation module 303 and a result generation module 304 .

[0094] The denoising module 301 is configured to denoise the high-frequency discharge signal.

[0095] For example, since the distance between the fault point and the power frequency current transformer is uncertain, the high-frequency discharge signals collected by different power frequency current transformers have a certain delay and are mixed with a certain amount of noise. Therefore, it is first necessary to denoise the high-frequency discharge signals collected by different power frequency current transformers. The denoising module 301 of the smart device 1022 can denoise the high-frequency discharge signals through methods such as wavelet soft threshold, empirical mode decomposition or smoothing denoising.

[0096] The alignment module 302 is configured to align high-frequency discharge signals obtained at different power frequency current transformers to obtain an alignment result.

[0097] For example, due to the different distances between the location of the partial discharge fault and different power-frequency current transformers, the received pulses will have a certain delay, and direct polarity determination may result in anomalies. After the denoising module 301 of the smart device 1022 denoises the high-frequency discharge signal, the alignment module 302 of the smart device 1022 can align the high-frequency discharge signals obtained at the different power-frequency current transformers to obtain an alignment result. The alignment of the high-frequency discharge signals obtained at the different power-frequency current transformers can be achieved based on phase or using a generalized cross-correlation method (GCC), but this application is not limited to this.

[0098] The polarity information generating module 303 is configured to generate polarity information according to the alignment result and the high-frequency discharge signal.

[0099] For example, after the alignment module 302 of the smart device 1022 aligns the partial discharge pulse signals collected by different power frequency current transformers, the polarity information generation module 303 of the smart device 1022 generates polarity information based on the alignment result. The polarity information is the distribution of the same polarity pulses or opposite polarity pulses within a cycle.

[0100] The result generating module 304 is configured to obtain a polarity determination result according to the polarity information and a preset threshold.

[0101] Exemplarily, the results of the polarity discrimination of the high-frequency discharge signal are divided into two results: same polarity and opposite polarity. The result generation module 304 of the smart device 1022 can count the pulse polarity distribution within a cycle and distinguish between internal and external faults according to a preset threshold. For example, the threshold is set to 75%. When the polarity information shows that the same polarity pulses within a cycle exceed 75%, the result of the polarity discrimination is same polarity, and the fault is determined to be an external discharge fault; when the polarity information shows that the opposite polarity pulses within a cycle exceed 75%, the result of the polarity discrimination is opposite polarity, and the fault is determined to be an internal discharge fault.

[0102] In one embodiment, as shown in FIG4 , the alignment module 302 includes: a factor generation submodule 401 , a function generation submodule 402 , and a signal alignment submodule 403 .

[0103] The factor generation submodule 401 is configured to generate weighting factors using the cross-power spectra of high-frequency discharge signals obtained at different power frequency current transformers.

[0104] For example, in order to align the high-frequency discharge signals obtained from different power frequency current transformers for analysis, the smart device 1022 can use a generalized cross-correlation method to process the high-frequency discharge signals. In actual situations, due to the influence of reverberation and noise, the generalized cross-correlation function The peak value is not obvious, which reduces the accuracy of multi-channel signal alignment. Therefore, the generalized cross-correlation method uses the frequency domain weighting factor to filter the signal to highlight the spectral components of the response signal part and suppress the spectral components of the noise part. Then, the inverse Fourier transform IFFT is performed to the time domain to sharpen the generalized cross-correlation function. The peak at the delay is more conducive to peak detection, thereby improving the delay estimation performance.

[0105] Select weighting factors As shown in the following formula:

[0106] Where ω represents the angular frequency, represents the cross power spectrum between the high frequency discharge signals x1(t) and x2(t) obtained at different power frequency current transformers, Represents the autopower spectrum between the high-frequency discharge signals x1(t) and x1(t) obtained at different power frequency current transformers, Represents the autopower spectrum between the high-frequency discharge signals x2(t) and x2(t) obtained at different power frequency current transformers.

[0107] The function generation submodule 402 is configured to generate a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signals obtained at different power frequency current transformers.

[0108] For example, the generalized cross-correlation function describes the correlation between the values ​​of random high-frequency discharge signals x1(s) and x2(t) at any two different times s and t, and is defined as:

[0109] R(s,t)=E(X1(s)×X2(t)) (2)

[0110] Where X1(s) represents the random variable corresponding to x1(s), and X2(t) represents the random variable corresponding to x2(t).

[0111] According to the Wiener-Schinchin theorem, the generalized cross-correlation function and its cross-power spectral density are Fourier transform pairs, so the generalized cross-correlation function of x1(t) and x2(t) is It can also be expressed as:

[0112] Where j represents the imaginary unit, ω represents the angular frequency, X1(ω) and X2(ω) represent the Fourier transform of the high-frequency discharge signals x1(t) and x2(t), respectively. It represents the cross power spectrum between high frequency discharge signals x1(t) and x2(t), X2 * (ω) is the complex conjugate of X2(ω).

[0113] Then use the weighting factor to sharpen the peak of the generalized cross-correlation function at the time delay, and the obtained generalized cross-correlation function Expressed as:

[0114] Where j represents the imaginary unit, ω represents the angular frequency, X1(ω) and X2(ω) represent the Fourier transform of the high-frequency discharge signals x1(t) and x2(t), respectively. represents the weighting factor, X2 * (ω) is the complex conjugate of X2(ω).

[0115] The signal alignment submodule 403 is configured to align the high-frequency discharge signals obtained at different power frequency current transformers according to the extreme values ​​of the generalized cross-correlation function.

[0116] For example, the generalized cross-correlation function The time delay between the two high-frequency signals corresponding to the extreme value of the , that is, the horizontal axis at the corresponding maximum peak, represents the estimated time delay required to align the high-frequency discharge signals obtained from different power-frequency current transformers. Alignment between the different signals can be achieved by shifting the signals according to the time delay value. The process for aligning the high-frequency discharge signals obtained from different power-frequency current transformers is shown in Figure 19.

[0117] For example, a transformer is equipped with multiple current transformers. One of these is arbitrarily selected as the time reference, designated as sensor 1, and the remaining sensors are numbered sequentially. The overall signal alignment process for the entire transformer is shown in FIG20 . Smart device 1022 aligns the high-frequency discharge signals obtained from different power-frequency current transformers to determine polarity.

[0118] In one embodiment, as shown in FIG5 , the smart device 1022 further includes:

[0119] The early warning and protection module 501 is configured to perform fault early warning or protection according to the location where the discharge fault occurs.

[0120] For example, as shown in FIG21 , the early warning and protection module 501 of the smart device 1022 can provide fault warning or protection based on the location of the discharge fault. When the discharge fault is determined to be an internal fault, the early warning and protection module 501 of the smart device 1022 determines whether the discharge fault has reached the alarm threshold based on multiple parameters such as the set discharge threshold (e.g., amplitude, number of pulses, and growth rate). If the discharge fault has reached the alarm threshold, the early warning or protection action signal is issued; otherwise, monitoring continues. When the discharge fault is determined to be an external fault, the early warning and protection module 501 of the smart device 1022 does not take action and continues normal monitoring.

[0121] In addition, when a fault occurs in the transformer that is neither an internal fault nor an external fault, the early warning protection module 501 of the smart device 1022 will count the abnormalities, and when the abnormality count reaches 50, a monitoring abnormality alarm signal will be issued.

[0122] In one embodiment, as shown in FIG6 , the signal acquisition module 101 includes: a signal shielding terminal and a coaxial cable.

[0123] The signal shielding terminal is arranged on the secondary junction box and is configured to prevent leakage of high-frequency signals.

[0124] For example, the secondary junction box of the industrial frequency current transformer is usually only used to lead out the industrial frequency current. Its output terminals are not specially designed for high-frequency signals. Direct use will cause high-frequency signal leakage and crosstalk, greatly attenuate the high-frequency current, and have poor lead-out effect. Moreover, its terminal impedance only matches the rated secondary side load value required at the industrial frequency, and cannot meet the 50 ohm load matching required for high-frequency signal acquisition. Therefore, a signal shielding terminal is set to better lead out multi-band signals and realize the synchronous acquisition of industrial frequency signals and high-frequency signals.

[0125] In one embodiment, the housing of the signal shielding terminal is an aluminum shielding cover, the outlet is a Bayonet Nut Connector (BNC) female connector, and a connecting bolt is provided on one side to effectively prevent high-frequency signal leakage.

[0126] A coaxial cable is connected to the signal shielding terminal and the frequency dividing circuit 1021 , and is configured to transmit the signal to the frequency dividing circuit 1021 .

[0127] Exemplarily, the cross-sectional area of ​​the central conductor of the coaxial cable is selected according to the frequency-rated current of the power frequency current transformer multiplied by the overcurrent coefficient k. For example, the overcurrent coefficient k can be set between 1.2 and 1.5.

[0128] In one embodiment, as shown in FIG6 , the signal shielding terminal includes a high-frequency terminal 601 and a grounding terminal 602 ; the high-frequency terminal 601 is provided on the common terminal S1 of the secondary junction box; the grounding terminal 602 is provided on a terminal other than the common terminal of the secondary junction box.

[0129] For example, a high-frequency terminal 601 located on the common terminal S1 of the secondary junction box and a ground terminal 602 located on a terminal outside the common terminal of the secondary junction box jointly implement signal shielding to prevent high-frequency signal leakage and crosstalk, effectively extracting high-frequency discharge signals. The secondary junction box of a power-frequency current transformer has multiple output terminals. For example, as shown in Figure 6, in addition to the common terminal S1, the secondary junction box also has an output terminal S2 and another output terminal S3. The ground terminal is located on an output terminal outside the common terminal based on the transformer parameters.

[0130] In one embodiment, as shown in FIG. 7 , the high-frequency terminal includes a copper conductor layer 701 , a polyethylene insulation layer 702 , a copper grounding layer 703 , a connecting bolt 704 , an impedance matching device 705 and a BNC connector 706 .

[0131] For example, the structures of high-frequency terminal 601 and grounding terminal 602 are shown in Figure 7. Both high-frequency terminal 601 and grounding terminal 602 have internal threads that can be screwed directly onto the outlet terminals within the secondary terminal box of the transformer's bushing power-frequency current transformer, facilitating connection to the secondary terminal box. The impedance matching device 705 of high-frequency terminal 601 ensures that the transformer's secondary side meets the secondary load requirements of its rated value at power frequency and that it can achieve 50-ohm output impedance matching within the high-frequency range. The BNC connector 706 of high-frequency terminal 601 is female, facilitating connection to a signal line (coaxial cable).

[0132] In one embodiment, as shown in FIG6 , the signal acquisition module 101 further includes a ground connection lead 603 , which connects the high-frequency terminal 601 and the ground terminal 602 and is configured to ensure a good shielding effect.

[0133] Exemplarily, one side of the high-frequency terminal 601 and the grounding terminal 602 is provided with a connecting bolt. Using a grounding connecting lead 603 to connect the high-frequency terminal 601 and the grounding terminal 602 can achieve a better signal shielding effect to ensure the collection of high-frequency discharge signals. At the same time, the grounding connecting lead 603 can also meet the requirement of grounding during the operation of the secondary side of the current transformer at the industrial frequency. The grounding connecting lead 603 can be a metal wire.

[0134] In one embodiment, as shown in FIG. 6 , the coaxial cable is a BNC coaxial cable 604 , which connects the high-frequency terminal 601 and the frequency dividing circuit 1021 .

[0135] Exemplarily, one end of the BNC coaxial cable 604 is connected to the high-frequency terminal 601 set in the secondary junction box through the BNC connector 706 of the high-frequency terminal 601, and the other end is connected to the frequency division circuit 1021 of the signal processing module 102 to transmit the multi-band signal of the transformer (including the industrial frequency signal and the high-frequency discharge signal) to the frequency division circuit 1021 for separation of the industrial frequency signal and the high-frequency discharge signal.

[0136] In one embodiment, as shown in FIG. 8 , the frequency dividing circuit 1021 includes a first low-pass filter 801 and a high-frequency band-pass filter 802 connected in parallel with the first low-pass filter 801 and consisting of a second low-pass filter 8021 and a high-pass filter 8022 .

[0137] The first low-pass filter 801 is configured to separate the power frequency signal from the signal.

[0138] For example, a low-pass filter is an electronic filter that is primarily configured to remove high-frequency components from a signal while retaining low-frequency components. It is typically configured to filter out noise and interfering signals in fields such as audio, video, and communications, thereby improving signal quality and reliability.

[0139] The main components of a low-pass filter are capacitors and resistors. Capacitors block high-frequency signals while allowing low-frequency signals to pass through. Resistors limit current flow and adjust the signal amplitude. The cutoff frequency of a low-pass filter is the highest frequency the filter allows to pass; signals exceeding this frequency are filtered out.

[0140] The low-pass filter can be a Butterworth filter or a Bessel filter. The filter order can be selected based on actual needs, generally controlled between 2 and 4 orders to achieve a balance between the steepness of the filter transition band and circuit complexity. The cutoff frequency can be set to 300Hz. The power frequency signal obtained after frequency band separation using the low-pass filter can be directly fed into differential protection equipment, current recording equipment, or measurement equipment without additional processing.

[0141] The high-frequency bandpass filter 802 is connected to the smart device 1022 , and is configured to separate the high-frequency discharge signal from the signal and transmit the high-frequency discharge signal to the smart device 1022 .

[0142] For example, high-pass filter 8022 uses a low-pass filter with a cutoff frequency of 30 MHz connected in series with a high-pass filter 8022 with a cutoff frequency of 3 MHz to separate signals within the 3 MHz to 30 MHz range. The filter can be a Butterworth filter or a Bessel filter, for example. The filter order can be selected based on actual needs, generally controlled between 2nd and 4th order to achieve a balance between the steepness of the filter transition band and circuit complexity. The high-frequency discharge signal obtained after frequency band separation using high-frequency bandpass filter 802, which is composed of a second low-pass filter 8021 and a high-pass filter 8022 connected in series, can be first sent to a partial discharge analyzer for processing and then sent to smart device 1022 for analysis, or it can be sent directly to smart device 1022 for analysis.

[0143] The high-frequency discharge signal detection device based on the power frequency current transformer provided in the present application includes a signal acquisition module and a signal processing module; the signal processing module includes a frequency division circuit and an intelligent device; the signal acquisition module is arranged on the secondary junction box of the power frequency current transformer of the transformer and is connected to the frequency division circuit, configured to collect the signal of the transformer and transmit the signal to the frequency division circuit; the signal includes a power frequency signal and a high-frequency discharge signal; the frequency division circuit is connected to the intelligent device, configured to separate the power frequency signal from the high-frequency discharge signal, and transmit the high-frequency discharge signal to the intelligent device; the intelligent device is configured to analyze the high-frequency discharge signal, thereby realizing the analysis of the high-frequency discharge signal of the transformer and the positioning of the partial discharge fault. Among them, the signal acquisition module is used to achieve the elimination of the need to add additional sensors or modify the transformer end screen, and only the secondary terminals of the bushing power frequency current transformer in the relevant technology are used to sense the high-frequency partial discharge current; the frequency division circuit is used to achieve the synchronous acquisition of multi-band signals at the secondary terminals of the power frequency current transformer and the separation of the power frequency signal and the high-frequency discharge signal; the intelligent device is used to achieve the polarity discrimination of the high-frequency discharge signal, and combined with the set multi-parameter discharge threshold, the transformer fault is distinguished and warned; the high-frequency discharge signal is detected by the transformer's bushing power frequency current transformer, and simultaneous online partial discharge monitoring of the high-voltage end and neutral point of each winding of the transformer is achieved. The detection range effectively covers the transformer, greatly improving the detection sensitivity of partial discharge signals that may be generated inside the transformer.

[0144] In addition, the present application also provides a high-frequency discharge signal detection method based on an industrial frequency current transformer, which completes the transformer high-frequency discharge signal analysis by using the high-frequency discharge signal detection device based on an industrial frequency current transformer described in the above embodiment.

[0145] FIG9 is a flow chart of a high-frequency discharge signal detection method based on an industrial frequency current transformer provided in an embodiment of the present application. As shown in FIG9 , the high-frequency discharge signal detection method based on an industrial frequency current transformer provided in the present application includes S901 - S903 .

[0146] S901: The signal acquisition module acquires a signal from the transformer and transmits the signal to a frequency dividing circuit; the signal includes an industrial frequency signal and a high-frequency discharge signal.

[0147] Exemplarily, the signal acquisition module collects the signal of the transformer, which is a multi-band signal including an industrial frequency signal and a high-frequency discharge signal. At the same time, the signal acquisition module transmits the multi-band signal from the terminal of the transformer's industrial frequency current transformer to the frequency division circuit.

[0148] S902: The frequency dividing circuit separates the power frequency signal from the high-frequency discharge signal, and transmits the high-frequency discharge signal to the smart device.

[0149] Exemplarily, the frequency dividing circuit separates the power frequency signal and the partial discharge pulse signal and processes them separately, and may be composed of a low-pass filter and a high-pass filter.

[0150] FIG10 is a flow chart of a high-frequency discharge signal detection method based on an industrial frequency current transformer provided in an embodiment of the present application. As shown in FIG10 , S902 includes S1001 - S1002 .

[0151] S1001: A first low-pass filter separates the power frequency signal from the signal.

[0152] For example, a low-pass filter is an electronic filter that is primarily configured to remove high-frequency components from a signal while retaining low-frequency components. It is typically configured to filter out noise and interfering signals in fields such as audio, video, and communications, thereby improving signal quality and reliability.

[0153] The main components of a low-pass filter are capacitors and resistors. Capacitors block high-frequency signals while allowing low-frequency signals to pass through. Resistors limit current flow and adjust the signal amplitude. The cutoff frequency of a low-pass filter is the highest frequency the filter allows to pass; signals exceeding this frequency are filtered out.

[0154] The low-pass filter can be a Butterworth filter or a Bessel filter. The filter order can be selected based on actual needs, generally controlled between 2 and 4 orders to achieve a balance between the steepness of the filter transition band and circuit complexity. The cutoff frequency can be set to 300Hz. The power frequency signal obtained after frequency band separation using the low-pass filter can be directly fed into differential protection equipment, current recording equipment, or measurement equipment without additional processing.

[0155] S1002: A high-frequency bandpass filter separates the high-frequency discharge signal from the signal, and transmits the high-frequency discharge signal to the smart device.

[0156] For example, a high-pass filter uses a low-pass filter with a cutoff frequency of 30MHz connected in series with a high-pass filter with a cutoff frequency of 3MHz to separate signals within the range of 3MHz to 30MHz. The filter can be a Butterworth filter or a Bessel filter, etc. The filter order can be selected according to actual needs, generally controlled between 2nd and 4th orders to achieve a balance between the steepness of the filter transition band and the complexity of the circuit. The high-frequency discharge signal obtained after frequency band separation using a high-frequency bandpass filter composed of a second low-pass filter and a high-pass filter in series can be first sent to a partial discharge analyzer for processing and then sent to an intelligent device for analysis, or it can be directly sent to the intelligent device for analysis.

[0157] S903: The smart device analyzes the high-frequency discharge signal.

[0158] For example, the intelligent electronic device (IED) first analyzes the high-frequency discharge signal, that is, determines the polarity of the high-frequency discharge signal, and distinguishes whether the discharge fault is an internal discharge fault or an external discharge fault according to the result of the polarity determination.

[0159] FIG11 is a flow chart of a high-frequency discharge signal detection method based on an industrial frequency current transformer provided in an embodiment of the present application. As shown in FIG11 , S903 includes S1101 - S1102 .

[0160] S1101: The smart device determines the polarity of the high-frequency discharge signal.

[0161] For example, transformer discharge faults are categorized as internal and external discharge faults based on the fault location. Due to the different polarities of the pulse currents in the bushing power frequency current transformer and the neutral-grounded power frequency current transformer for internal and external discharge faults, intelligent devices can be used to distinguish and locate internal and external faults. For example, a fault analysis of a 500kV (or above) power transformer using a single-phase autocoupler is performed, as shown in Figure 16.

[0162] FIG12 is a flow chart of a high-frequency discharge signal detection method based on an industrial frequency current transformer provided in an embodiment of the present application. As shown in FIG12 , S1101 includes S1201 - S1204 .

[0163] S1201: The smart device denoises the high-frequency discharge signal.

[0164] For example, since the distance between the fault point and the power frequency current transformer is uncertain, the high-frequency discharge signals collected by different power frequency current transformers have a certain delay and are mixed with a certain amount of noise. Therefore, it is first necessary to denoise the high-frequency discharge signals collected by different power frequency current transformers. The denoising module of the smart device can denoise the high-frequency discharge signals through methods such as wavelet soft threshold, empirical mode decomposition or smoothing denoising.

[0165] S1202: The smart device aligns high-frequency discharge signals obtained at different power frequency current transformers to obtain an alignment result.

[0166] For example, due to the different distances between the location of the partial discharge fault and different power-frequency current transformers, the received pulses will have a certain delay, and direct polarity comparison may cause anomalies. After the denoising module of the smart device denoises the high-frequency discharge signal, the alignment module of the smart device can align the high-frequency discharge signals obtained at different power-frequency current transformers to obtain an alignment result. The alignment of the high-frequency discharge signals obtained at different power-frequency current transformers can be achieved based on phase or using a generalized cross-correlation method (GCC), but this application is not limited to this.

[0167] FIG13 is a flow chart of a high-frequency discharge signal detection method based on an industrial frequency current transformer provided in an embodiment of the present application. As shown in FIG13 , S1202 includes S1301 - S1303 .

[0168] S1301: The intelligent device generates a weighting factor using the cross-power spectrum of high-frequency discharge signals obtained at different power frequency current transformers.

[0169] For example, in order to align the high-frequency discharge signals obtained from different power frequency current transformers for analysis, the smart device can use the generalized cross-correlation method to process the high-frequency discharge signals. In actual situations, due to the influence of reverberation and noise, the generalized cross-correlation function The peak value is not obvious, which reduces the accuracy of multi-channel signal alignment. Therefore, the generalized cross-correlation method uses the frequency domain weighting factor to filter the signal to highlight the spectral components of the response signal part and suppress the spectral components of the noise part. Then, the inverse Fourier transform IFFT is performed to the time domain to sharpen the generalized cross-correlation function. The peak at the delay is more conducive to peak detection, thereby improving the delay estimation performance.

[0170] Select weighting factors As shown in the following formula:

[0171] Where ω represents the angular frequency, represents the cross power spectrum between the high frequency discharge signals x1(t) and x2(t) obtained at different power frequency current transformers, Represents the autopower spectrum between the high-frequency discharge signals x1(t) and x1(t) obtained at different power frequency current transformers, Represents the autopower spectrum between the high-frequency discharge signals x2(t) and x2(t) obtained at different power frequency current transformers.

[0172] S1302: The smart device generates a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signals obtained at different power frequency current transformers.

[0173] For example, the generalized cross-correlation function describes the correlation between the values ​​of random high-frequency discharge signals x1(s) and x2(t) at any two different times s and t, and is defined as:

[0174] R(s, t)=E(X1(s)× X 2(t)) (2)

[0175] Where X1(s) represents the random variable corresponding to x1(s), and X2(t) represents the random variable corresponding to x2(t).

[0176] According to the Wiener-Schinchin theorem, the generalized cross-correlation function and its cross-power spectral density are Fourier transform pairs, so the generalized cross-correlation function of x1(t) and x2(t) is It can also be expressed as:

[0177] Where j represents the imaginary unit, ω represents the angular frequency, X1(ω) and X2(ω) represent the Fourier transform of the high-frequency discharge signals x1(t) and x2(t), respectively. It represents the cross power spectrum between high frequency discharge signals x1(t) and x2(t), X2 * (ω) is the complex conjugate of X2(ω).

[0178] Then use the weighting factor to sharpen the peak of the generalized cross-correlation function at the time delay, and the obtained generalized cross-correlation function Expressed as:

[0179] Where j represents the imaginary unit, ω represents the angular frequency, X1(ω) and X2(ω) represent the Fourier transform of the high-frequency discharge signals x1(t) and x2(t), respectively. represents the weighting factor, X2 * (ω) is the complex conjugate of X2(ω).

[0180] S1303: The smart device aligns the high-frequency discharge signals obtained at different power frequency current transformers according to extreme values ​​of the generalized cross-correlation function.

[0181] For example, the generalized cross-correlation function The time delay between the two high-frequency signals corresponding to the extreme value of the , that is, the horizontal axis at the corresponding maximum peak, represents the estimated time delay required to align the high-frequency discharge signals obtained from different power-frequency current transformers. Alignment between the different signals can be achieved by shifting the signals according to the time delay value. The process for aligning the high-frequency discharge signals obtained from different power-frequency current transformers is shown in Figure 19.

[0182] For example, a transformer is equipped with multiple current transformers. One of these is arbitrarily selected as the time reference, designated as sensor 1, and the remaining sensors are numbered sequentially. Figure 20 shows the overall signal alignment process for the entire transformer. The intelligent device aligns the high-frequency discharge signals obtained from current transformers at different power frequencies to determine polarity.

[0183] S1203: The smart device generates polarity information according to the alignment result and the high-frequency discharge signal.

[0184] For example, after the alignment module of the smart device aligns the phases of the partial discharge pulse signals collected by different industrial frequency current transformers, the polarity information generation module of the smart device generates polarity information based on the alignment results and the high-frequency discharge signal. The polarity information is the distribution of pulses of the same polarity or pulses of different polarity within a cycle.

[0185] S1204: The smart device obtains a polarity determination result according to the polarity information and a preset threshold.

[0186] Exemplarily, the results of high-frequency discharge signal polarity discrimination are divided into two types: same polarity and opposite polarity. The result generation module of the intelligent device counts the pulse polarity distribution within a cycle, and distinguishes between internal and external faults according to a preset threshold. For example, the threshold is set to 75%. When the polarity information shows that the same polarity pulses within a cycle exceed 75%, the result of the polarity discrimination is same polarity, and the fault is determined to be an external discharge fault; when the polarity information shows that the opposite polarity pulses within a cycle exceed 75%, the result of the polarity discrimination is opposite polarity, and the fault is determined to be an internal discharge fault.

[0187] S1102: The smart device determines the location where the discharge fault occurs based on the result of polarity determination.

[0188] For example, the transformer can include multiple power frequency current transformers and perform current monitoring simultaneously. As shown in Figure 16, when an internal fault occurs, the secondary side of the winding power frequency current transformer and the secondary side of the neutral point grounding power frequency current transformer can both sense partial discharge pulses, and the two have opposite polarities. Conversely, as shown in Figure 17, when an external fault occurs, the fault current is a through current, and the pulse polarity sensed by the winding power frequency current transformer and the neutral point grounding power frequency current transformer is the same. Based on this feature, the location determination module of the intelligent device can locate the discharge fault by detecting the polarity of the high-frequency discharge signal during the operation of the transformer. The same polarity pulse and the opposite polarity pulse are shown in Figure 18.

[0189] In one embodiment, the high-frequency discharge signal detection method based on the power frequency current transformer further includes, after S903:

[0190] The intelligent device performs fault warning or protection according to the location where the discharge fault occurs.

[0191] For example, as shown in Figure 21, the early warning and protection module of the intelligent device can provide fault warning or protection based on the location of the discharge fault. When the discharge fault is determined to be an internal fault, the early warning and protection module of the intelligent device determines whether the discharge fault has reached the alarm threshold based on multiple parameters such as the set discharge threshold (such as amplitude, number of pulses, and growth rate). If the discharge fault has reached the alarm threshold, the early warning or protection action signal is issued; otherwise, monitoring continues. When the discharge fault is determined to be an external fault, the early warning and protection module of the intelligent device does not take action and continues normal monitoring.

[0192] In addition, when a transformer fault occurs that is neither an internal fault nor an external fault, the early warning protection module of the intelligent device will count the abnormalities and issue a monitoring abnormality alarm signal when the abnormality count reaches 50.

[0193] The high-frequency discharge signal detection method based on the industrial frequency current transformer provided in the present application collects the signal of the transformer through the signal acquisition module and transmits the signal to the frequency division circuit; the signal includes the industrial frequency signal and the high-frequency discharge signal; the frequency division circuit separates the industrial frequency signal from the high-frequency discharge signal, and transmits the high-frequency discharge signal to the smart device; the smart device analyzes the high-frequency discharge signal, thereby realizing the analysis of the high-frequency discharge signal and the positioning of the local discharge fault. Among them, the signal of the transformer is collected by the signal acquisition module and the signal is transmitted to the frequency division circuit, so that there is no need to add additional sensors and modify the transformer end screen, and only the secondary terminals of the bushing power frequency current transformer in the related technology are used to sense the high-frequency partial discharge current; the power frequency signal and the high-frequency discharge signal are separated by the frequency division circuit, so as to realize the synchronous acquisition of multi-band signals at the secondary terminals of the power frequency current transformer and the separation of the power frequency signal and the high-frequency discharge signal; the high-frequency discharge signal is analyzed by the intelligent device, so as to realize the polarity discrimination of the high-frequency discharge signal, and combine with the set multi-parameter discharge threshold to distinguish and warn the transformer fault; the high-frequency discharge signal is detected by the bushing power frequency current transformer of the transformer, so as to realize the simultaneous online partial discharge monitoring of the high-voltage end and neutral point of each winding of the transformer, and the detection range effectively covers the transformer, which greatly improves the detection sensitivity of the partial discharge signal that may be generated inside the transformer.

[0194] In the description of this specification, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on this application. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0195] The descriptions with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. The order of steps involved in each embodiment is used to schematically illustrate the implementation of the present application, and the order of steps therein is not limited and can be appropriately adjusted as needed.

[0196] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on specific circumstances.

[0197] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A high-frequency discharge signal detection device based on a power frequency current transformer, comprising: Signal acquisition module and signal processing module; The signal processing module includes a frequency division circuit and an intelligent device; The signal acquisition module is arranged on the secondary junction box of the power frequency current transformer of the transformer and is connected to the frequency division circuit. The signal acquisition module is configured to acquire the signals of the transformer and transmit the signals to the frequency division circuit. The signals include power frequency signals and high-frequency discharge signals; The frequency division circuit is connected to the intelligent device. The frequency division circuit is configured to separate the power frequency signal from the high-frequency discharge signal and transmit the high-frequency discharge signal to the intelligent device; The intelligent device is configured to analyze the high-frequency discharge signal.

2. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 1, wherein, The intelligent device includes: A polarity discrimination module configured to perform polarity discrimination on the high-frequency discharge signal; A position determination module configured to determine the position where the discharge fault occurs according to the result of the polarity discrimination.

3. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 2, wherein, The polarity discrimination module includes: A denoising module configured to denoise the high-frequency discharge signal; An alignment module configured to align the high-frequency discharge signals obtained at different power frequency current transformers to obtain an alignment result; A polarity information generation module configured to generate polarity information according to the alignment result; A result generation module configured to obtain the result of the polarity discrimination according to the polarity information and a preset threshold.

4. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 3, wherein, The alignment module includes: A factor generation sub-module configured to generate a weighting factor by using the cross-power spectrum of the high-frequency discharge signals obtained at different power frequency current transformers; A function generation sub-module configured to generate a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signals obtained at different power frequency current transformers ; A signal alignment sub-module configured to align the high-frequency discharge signals obtained at different power frequency current transformers according to the extreme value of the generalized cross-correlation function.

5. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 2, wherein, The intelligent device further includes: An early warning and protection module configured to perform fault early warning or protection according to the position where the discharge fault occurs.

6. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 1, wherein, The signal acquisition module includes: A signal shielding terminal arranged on the secondary junction box. The signal shielding terminal is configured to prevent high-frequency signal leakage; A coaxial cable connecting the signal shielding terminal and the frequency division circuit. The coaxial cable is configured to transmit the signal to the frequency division circuit.

7. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 6, wherein, The signal shielding terminal includes a high-frequency terminal and a grounding terminal. The high-frequency terminal is arranged on the common terminal of the secondary junction box, and the grounding terminal is arranged on the terminal outside the common terminal of the secondary junction box.

8. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 7, wherein, The high-frequency terminal includes a copper conductor layer, a polyethylene insulation layer, a copper grounding layer, a connecting bolt, an impedance matching device, and a bayonet nut connector BNC joint.

9. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 7, wherein, The signal acquisition module further includes: a grounding connection lead connecting the high-frequency terminal and the grounding terminal. The grounding connection lead is configured to achieve signal shielding.

10. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 7, wherein, The coaxial cable is a BNC coaxial cable connecting the high-frequency terminal and the frequency division circuit.

11. The high-frequency discharge signal detection device based on a power frequency current transformer according to claim 1, wherein, The frequency division circuit includes a first low-pass filter and a high-frequency band-pass filter connected in parallel with the first low-pass filter. The high-frequency band-pass filter is composed of a second low-pass filter and a high-pass filter; The first low-pass filter is configured to separate the power frequency signal from the signal; The high-frequency band-pass filter is connected to the intelligent device. The high-frequency band-pass filter is configured to separate the high-frequency discharge signal from the signals and transmit the high-frequency discharge signal to the intelligent device.

12. A method for detecting high-frequency discharge signals based on a power-frequency current transformer, comprising: A signal acquisition module acquires signals of a transformer and transmits the signals to a frequency division circuit. The signals include power-frequency signals and high-frequency discharge signals. The signal acquisition module is disposed on a secondary junction box of a power-frequency current transformer of the transformer and is connected to the frequency division circuit; The frequency division circuit separates the power-frequency signal from the high-frequency discharge signal and transmits the high-frequency discharge signal to the intelligent device; The intelligent device analyzes the high-frequency discharge signal.

13. The high-frequency discharge signal detection method based on a power frequency current transformer according to claim 12, wherein, The frequency division circuit includes a first low-pass filter and a high-frequency band-pass filter connected in parallel with the first low-pass filter. The frequency division circuit separates the power-frequency signal from the high-frequency discharge signal and transmits the high-frequency discharge signal to the intelligent device, including: The first low-pass filter separates the power-frequency signal from the signals; The high-frequency band-pass filter separates the high-frequency discharge signal from the signals and transmits the high-frequency discharge signal to the intelligent device.

14. The high-frequency discharge signal detection method based on a power frequency current transformer according to claim 12, wherein, The intelligent device analyzes the high-frequency discharge signal, including: The intelligent device performs polarity discrimination on the high-frequency discharge signal; The intelligent device determines the location where a discharge fault occurs according to the result of the polarity discrimination.

15. The high-frequency discharge signal detection method based on a power frequency current transformer according to claim 14, wherein, The intelligent device performs polarity discrimination on the high-frequency discharge signal, including: The intelligent device denoises the high-frequency discharge signal; The intelligent device aligns the high-frequency discharge signals obtained at different power-frequency current transformers to obtain an alignment result; The intelligent device generates polarity information according to the alignment result; The intelligent device obtains the result of the polarity discrimination according to the polarity information and a preset threshold.

16. The high-frequency discharge signal detection method based on a power frequency current transformer according to claim 15, wherein, The intelligent device aligns the high-frequency discharge signals obtained at different power-frequency current transformers, including: The intelligent device generates a weighting factor by using the cross-power spectrum of the high-frequency discharge signals obtained at different power-frequency current transformers; The intelligent device generates a generalized cross-correlation function according to the weighting factor and the high-frequency discharge signals obtained at different power-frequency current transformers; The intelligent device aligns the high-frequency discharge signals obtained at different power-frequency current transformers according to the extreme value of the generalized cross-correlation function.

17. The method for detecting high-frequency discharge signals based on a power-frequency current transformer according to claim 14, further comprising: The intelligent device performs fault warning or protection according to the location where the discharge fault occurs.

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