CN113791313A - Partial discharge detection device and detection method thereof - Google Patents
Partial discharge detection device and detection method thereof Download PDFInfo
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- G01R31/1272—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing of components, parts or materials of solid or fluid materials, e.g. insulation films, bulk material; of semiconductors or LV electronic components or parts; of cable, line or wire insulation of cable, line or wire insulation, e.g. using partial discharge measurements
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Abstract
本申请涉及一种局部放电检测装置及其检测方法。所述装置包括信号生成模块，用于输出振荡波信号至待测的三相电缆，以分别形成各相的检测路径，振荡波信号用于激励各相电缆产生局部放电信号；信号提取模块，一端与信号生成模块连接，另一端用于连接三相电缆，信号提取模块用于提取各相检测路径上的局部放电信号，并生成与局部放电信号相对应的提取信号；采样模块，与信号提取模块连接，用于分别对各相提取信号进行采样，以获取各相提取信号的波形；降噪处理模块，与采样模块连接，用于对采样的各相提取信号的波形进行降噪处理，以获取降噪后的提取信号波形，并根据降噪后的提取信号的波形分析出三相电缆的局部放电状态。能够达到精准检测的目的。
The present application relates to a partial discharge detection device and a detection method thereof. The device includes a signal generation module for outputting oscillating wave signals to the three-phase cables to be tested to form detection paths for each phase respectively, and the oscillating wave signals are used to excite each phase cable to generate partial discharge signals; a signal extraction module, one end It is connected to the signal generation module, and the other end is used to connect the three-phase cable. The signal extraction module is used to extract the partial discharge signal on the detection path of each phase, and generate the extracted signal corresponding to the partial discharge signal; the sampling module, which is connected to the signal extraction module connection, used to sample the extracted signals of each phase respectively to obtain the waveform of the extracted signals of each phase; noise reduction processing module, connected to the sampling module, used to perform noise reduction processing on the waveforms of the sampled extracted signals of each phase to obtain The extracted signal waveform after noise reduction, and the partial discharge state of the three-phase cable is analyzed according to the waveform of the extracted signal after noise reduction. can achieve the purpose of accurate detection.
Description
Technical Field
The present disclosure relates to the field of insulation state detection technology for power cables, and more particularly, to a partial discharge detection device and a detection method thereof.
Background
With the development of urban distribution networks in China, the grounding cabling of overhead lines becomes one of important contents for urban power grid construction, and due to the good electrical performance and mechanical performance of cross-linked polyethylene (XLPE) cables, power cables mainly produced and operated in China are polyethylene (XLPE) cables. Partial discharge is an important cause of cable insulation degradation, and although partial discharge cannot form a through discharge channel to cause insulation breakdown, a large amount of space particles are caused to accelerate to impact an insulating medium, so that XLPE high molecular chemical bonds are broken, and the insulating performance of XLPE high molecular chemical bonds is reduced. Meanwhile, the discharge channel causes local temperature rise, chemical decomposition of the insulating medium is accelerated, high-energy rays are generated, XLPE high polymers are further cracked, and a large amount of oxides generated along with cracking can gradually corrode the insulating material. After long-time operation, partial discharge can finally cause cable insulation breakdown, causing power failure accidents.
The oscillation wave partial discharge detection is the most common field cable partial discharge off-line detection means at present. At present, oscillation wave partial discharge detection still needs phase-by-phase detection, even if the equipment capacity is enough, the three phases cannot be simultaneously tested due to the difficulty in distinguishing partial discharge signals, and in addition, a power cable still has larger background noise even if the power cable is subjected to offline test, so that the sensitivity of partial discharge detection can be greatly reduced.
Disclosure of Invention
In view of the above, it is desirable to provide a partial discharge detection apparatus and a partial discharge detection method that can simultaneously perform noise reduction processing on a three-phase cable.
A partial discharge detection device applied to partial discharge detection of a three-phase cable, the device comprising:
the signal generating module is used for outputting an oscillation wave signal to a three-phase cable to be detected so as to form a detection path of each phase respectively, and the oscillation wave signal is used for exciting each phase of cable to generate a partial discharge signal;
the signal extraction module is used for extracting partial discharge signals on each phase detection path and generating extraction signals corresponding to the partial discharge signals;
the sampling module is connected with the signal extraction module and is used for sampling the extracted signals of each phase respectively so as to obtain the waveform of the extracted signals of each phase;
and the noise reduction processing module is connected with the sampling module and used for carrying out noise reduction processing on the waveform of the sampled extraction signal of each phase so as to obtain the waveform of the extracted signal subjected to noise reduction and analyzing the partial discharge state of the three-phase cable according to the waveform of the extracted signal subjected to noise reduction.
In one embodiment, the signal extraction module includes a plurality of signal extraction submodules, one end of each signal extraction submodule is connected with the signal generation module, the other end of each signal extraction submodule is respectively used for connecting one phase cable of the three-phase cables, and each signal extraction submodule is used for extracting a partial discharge signal on a detection path of each phase cable and generating an extraction signal corresponding to the partial discharge signal.
In one embodiment, the signal extraction sub-module comprises:
the coupling unit is connected with the signal generation module and used for coupling the partial discharge signals on the cable detection paths of all phases to generate coupling signals;
and one end of the filtering unit is connected with the coupling unit, the other end of the filtering unit is used for grounding, and the filtering unit is used for filtering low-frequency signal components of the coupling signals and taking the filtered coupling signals as extraction signals.
In one embodiment, the filtering unit includes:
one end of the filter impedance is connected with the coupling unit, and the other end of the filter impedance is used for grounding;
and the input end of the high-pass filter is connected with one end of the filter impedance in parallel, and the output end of the high-pass filter is connected with the sampling module.
In one embodiment, the filter impedance is an RLC type parallel circuit.
In one embodiment, the high pass filter is a ninth order elliptic filter.
In one embodiment, the signal extraction module further comprises:
and one end of the blocking reactance is connected with the signal generation module, the other end of the blocking reactance is connected with the coupling unit, and the blocking reactance is used for blocking the partial discharge signal.
In one embodiment, the method further comprises the following steps:
the voltage divider is connected with the signal generation module and used for acquiring the oscillation wave signal and generating a divided voltage signal;
the sampling module is further connected with the voltage divider and is further used for sampling the voltage division signal so as to monitor the oscillation wave signal in real time.
A partial discharge detection method is applied to the device, and comprises the following steps:
outputting an oscillation wave signal to a three-phase cable to be detected to form a detection path of each phase respectively, wherein the oscillation wave signal is used for exciting each phase of cable to generate a partial discharge signal;
extracting partial discharge signals on each phase of detection paths, and generating extraction signals corresponding to the partial discharge signals;
sampling the extracted signals of each phase respectively to obtain the waveform of the extracted signals of each phase;
and carrying out noise reduction processing on the waveform of the sampled extraction signal of each phase to obtain the waveform of the extracted signal subjected to noise reduction, and analyzing the partial discharge state of the three-phase cable according to the waveform of the extracted signal subjected to noise reduction.
In one embodiment, the noise reduction processing is performed on the waveform of the sampled extracted signal of each phase to obtain a noise-reduced extracted signal waveform, and includes:
acquiring a background noise signal waveform according to the acquired extraction signals of each phase;
and acquiring the extracted signal waveform after noise reduction according to the background noise signal waveform and the extracted signal waveform of each phase.
The partial discharge detection device is applied to the partial discharge detection of the three-phase cable, and comprises a signal generation module, a partial discharge detection module and a signal processing module, wherein the signal generation module is used for outputting an oscillation wave signal to the three-phase cable to be detected so as to respectively form a detection path of each phase, and the oscillation wave signal is used for exciting each phase of cable to generate a partial discharge signal; the signal extraction module is used for extracting partial discharge signals on each phase detection path and generating extraction signals corresponding to the partial discharge signals; the sampling module is connected with the signal extraction module and is used for sampling the extracted signals of each phase respectively so as to obtain the waveform of the extracted signals of each phase; and the noise reduction processing module is connected with the sampling module and used for carrying out noise reduction processing on the waveform of the sampled extraction signal of each phase so as to obtain the waveform of the extracted signal subjected to noise reduction and analyzing the partial discharge state of the three-phase cable according to the waveform of the extracted signal subjected to noise reduction. The invention can test the three-phase cable at the same time, and reduce the influence of environmental noise on the partial discharge test, thereby effectively improving the test efficiency and the test sensitivity.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments or the conventional technologies of the present application, the drawings used in the descriptions of the embodiments or the conventional technologies will be briefly introduced below, it is obvious that the drawings in the following descriptions are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic diagram of an embodiment of a partial discharge detector;
FIG. 2 is one of the schematic structural diagrams of a signal extraction sub-module in one embodiment;
FIG. 3 is a schematic diagram of the structure of the filter impedance in one embodiment;
FIG. 4 is a schematic diagram of the structure of a high pass filter in one embodiment;
FIG. 5 is a second exemplary diagram of the signal extraction sub-module of the embodiment;
FIG. 6 is a second schematic structural diagram of an embodiment of a partial discharge detection apparatus;
FIG. 7 is a flow chart of a partial discharge detection method according to another embodiment;
FIG. 8 is a second flowchart of a partial discharge detection method according to another embodiment.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Embodiments of the present application are set forth in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
It will be understood that the terms "first," "second," and the like as used herein may be used herein to describe various signal extraction sub-modules, but these signal extraction sub-modules are not limited by these terms. These terms are only used to distinguish a first signal extraction sub-module from another signal extraction sub-module.
It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or be connected to the other element through intervening elements. Further, "connection" in the following embodiments is understood to mean "electrical connection", "communication connection", or the like, if there is a transfer of electrical signals or data between the connected objects.
As used herein, the singular forms "a", "an" and "the" may include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises/comprising," "includes" or "including," etc., specify the presence of stated features, integers, steps, operations, components, parts, or combinations thereof, but do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
In one embodiment, as shown in fig. 1, a partial discharge detection apparatus 100 is provided that includes a signal generation module 110, a signal extraction module 130, a sampling module 150, and a noise reduction processing module 170. The signal generating module 110 is configured to output an oscillation wave signal to a three-phase cable to be detected to form a detection path of each phase, where the oscillation wave signal is used to excite each phase of cable to generate a partial discharge signal; one end of the signal extraction module 130 is connected to the signal generation module 110, and the other end is used for connecting to a three-phase cable, and the signal extraction module 130 is used for extracting partial discharge signals on each phase detection path and generating extraction signals corresponding to the partial discharge signals; the sampling module 150 is connected to the signal extraction module 130, and is configured to sample the extracted signals of each phase respectively to obtain waveforms of the extracted signals of each phase; the noise reduction processing module 170 is connected to the sampling module, and is configured to perform noise reduction processing on the waveform of the sampled extracted signal of each phase to obtain a noise-reduced extracted signal waveform, and analyze a partial discharge state of the three-phase cable according to the noise-reduced extracted signal waveform. The three-phase voltage output by the three-phase cable to be tested is a combination of three symmetrical sinusoidal alternating currents with phase differences of 120 degrees, namely the three-phase voltage has the characteristic of high symmetry. Therefore, during the detection process, the partial discharge signal on the detection path is also characterized by high symmetry. The invention not only achieves the purpose of improving the detection efficiency by simultaneously carrying out the partial discharge detection on the three-phase cable, but also achieves the effect of improving the detection precision by carrying out noise reduction treatment by utilizing the high symmetry of the partial discharge signal generated by the detection.
In one embodiment, with continued reference to fig. 1, signal extraction module 130 includes a plurality of signal extraction sub-modules. In the three-phase cable detection of the present embodiment, three signal extraction sub-modules are included, namely, a first signal extraction sub-module 131, a second signal extraction sub-module 132, and a third signal extraction sub-module 133. One end of each signal extraction submodule is connected with the signal generation module 110, and the other end of each signal extraction submodule is respectively used for connecting one phase cable of three-phase cables, namely an A-phase cable, a B-phase cable or a C-phase cable. Each signal extraction submodule is used for extracting a partial discharge signal on each phase cable detection path and generating an extraction signal corresponding to the partial discharge signal.
In one embodiment, as shown in fig. 2, a schematic diagram of a signal extraction sub-module is provided, it should be noted that structures of the signal extraction sub-modules are the same, and the embodiment takes the third signal extraction sub-module 133 as an example, and includes a coupling unit 1331 and a filtering unit 1333. The coupling unit 1331 is connected to the signal generating module 110, and is configured to couple the partial discharge signal on the corresponding phase cable detection path to generate a coupling signal; the filter unit 1333 has one end connected to the coupling unit 1331 and the other end connected to ground, wherein the filter unit 1333 is connected to the sampling module 150. The filtering unit 1333 is configured to filter out a low-frequency signal component of the coupled signal, and use the filtered coupled signal as an extraction signal. The high-frequency signal component in the signal has a small distortion rate, so that the signal has strong recoverability and high anti-interference rate, and the low-frequency signal component is easily blocked by the ground and objects in the air to influence the property of the signal. Therefore, filtering out the low-frequency signal component can make the signal extracted by the signal extraction sub-module more favorable for the detection accuracy.
In one embodiment, the coupling unit is a coupling capacitor.
In one embodiment, the coupling capacitor is a ceramic capacitor with a capacitance value of 5 nF. Compared with other capacitors, the common ceramic capacitor has the advantages of higher use temperature, large specific capacity, good moisture resistance, smaller dielectric loss, large-range selectable capacitance temperature coefficient and the like. The durability of the detection device is facilitated.
In one embodiment, with continued reference to fig. 2, the filtering unit 1333 includes a filter impedance and a high pass filter. The filter impedance is connected with the coupling unit 1331, and the other end is used for grounding; the input end of the high-pass filter is connected in parallel with one end of the filter impedance, and the output end of the high-pass filter is connected with the sampling module 150. The filter impedance and the high-pass filter can ensure that the low-frequency signal component in the coupled signal can be completely filtered.
In one embodiment, a schematic diagram of a filter impedance structure is provided, as shown in fig. 3. The filter impedance is an RLC type parallel circuit, and comprises an inductor L0, a capacitor C0 and a resistor R0. The filter impedance formed by the RLC type parallel circuit can completely filter out low-frequency signal components in the coupled signal.
In one embodiment, a high pass filter architecture is provided as shown in fig. 4. The high pass filter is a ninth order elliptic filter. The three-phase inverter comprises nine capacitors and three inductors, wherein the capacitance value of the capacitor C1 is 8nF, the capacitance value of the capacitor C2 is 104nF, the capacitance value of the capacitor C3 is 2.54nF, the capacitance value of the capacitor C4 is 53.6nF, the capacitance value of the capacitor C5 is 57nF, the capacitance value of the capacitor C6 is 52.5nF, the capacitance value of the capacitor C7 is 50.6nF, the capacitance value of the capacitor C8 is 65.7nF, and the capacitance value of the capacitor C9 is 58.7 nF; inductance L1 is 125uH, inductance L2 is 115uH, and inductance L3 is 115 uH. The connection node of the capacitor C1 and the capacitor C4 and the connection node of the inductors L1 and L2 serve as input terminals of the elliptic filter, and the connection node of the capacitor C3 and the capacitor C9 and the connection node of the inductors L2 and L3 serve as output terminals of the elliptic filter. Compared with other types of filters, the elliptic filter has the minimum pass band and stop band fluctuation under the condition of the same order, so that the elliptic filter is beneficial to accurately filtering low-frequency signal components in the coupled signals.
In one embodiment, as shown in FIG. 5, a schematic diagram of a signal extraction sub-module is provided. The signal extraction submodule 130 further includes a blocking reactance 1335. The blocking reactance 1335 has one end connected to the signal generating module 110 and the other end connected to the coupling unit 1331, and the blocking reactance 1335 is used for blocking the partial discharge signal. This prevents the partial discharge signals of each phase from interfering with each other, which is beneficial to the accuracy of detection.
In one embodiment, an air core reactor is adopted as the blocking reactor, and the reactance value of the blocking reactor is selected to be 10mH, so that the saturation of the magnetic core of the three-phase cable in the detection process can be avoided.
In one embodiment, as shown in fig. 6, a partial discharge detection apparatus 100 is provided. The partial discharge detection apparatus 100 further includes a voltage divider 180. The voltage divider 180 is connected with the signal generation module 110, and the voltage divider 180 is used for acquiring the oscillation wave signal and generating a divided voltage signal; the sampling module 150 is further configured to sample the divided voltage signal to monitor the oscillation wave signal in real time.
In one embodiment, the voltage divider includes a high arm resistor R1And a low-voltage arm resistor R2, wherein the high-voltage arm resistor R1 and the low-voltage arm resistor R2 are connected in series, and the low-voltage arm resistor R2 is also used for grounding. The high-voltage arm resistor R1 is connected in parallel with a capacitor C1, and the low-voltage arm resistor is connected in parallel with a capacitor C2.
In one embodiment, the voltage divider is a resistance-capacitance voltage divider, the resistance of the high-voltage arm is selected to be 200M Ω, the capacitance is selected to be 100pF, the resistance of the low-voltage arm is selected to be 10k Ω, the capacitance is selected to be 1 μ F, and the transformation ratio of the voltage divider is 10000: 1. the device ensures a good voltage division ratio, is favorable for monitoring the oscillation wave signals in real time, reduces the accident rate of the detection device, and is favorable for further detecting the partial discharge signals subsequently. Such as dielectric loss, etc.
In one embodiment, the sampling rate of the sampling module is 250MHz, the sampling bit number is 16 bits, and the reasonability of the sampling data is ensured.
In one embodiment, as shown in fig. 6, a partial discharge detection apparatus is provided, which includes a signal generation module 110, a blocking reactance 114, a first signal extraction sub-module 131, a second signal extraction sub-module 132, a third signal extraction sub-module 133, a coupling unit 1331, a filtering unit 1333, a sampling module 150, a noise reduction processing module 170, and a voltage divider 180. The connection relationship and the function of the elements in the device are defined as above, and are not described herein again.
In one embodiment, as shown in fig. 7, a partial discharge detection method is provided, which is applied to the above partial discharge detection device, and the partial discharge detection method includes steps S100 to S400.
And S100, outputting an oscillation wave signal to the three-phase cable to be detected so as to form a detection path of each phase respectively, wherein the oscillation wave signal is used for exciting the cable of each phase to generate a partial discharge signal.
In step S200, the partial discharge signal on each phase detection path is extracted, and an extraction signal corresponding to the partial discharge signal is generated.
Step S300, sampling the extracted signals of each phase respectively to obtain waveforms of the extracted signals of each phase.
And step S400, performing noise reduction processing on the waveform of the sampled extraction signal of each phase to obtain the noise-reduced extraction signal waveform, and analyzing the partial discharge state of the three-phase cable according to the noise-reduced extraction signal waveform.
In one embodiment, as shown in fig. 8, a partial discharge detection method is provided, which is applied to the partial discharge detection device. In step S400, the method performs noise reduction on the waveform of the sampled extracted signal of each phase to obtain a noise-reduced extracted signal waveform, and includes steps S410 to S420.
Step S410, obtaining a background noise signal waveform according to the collected phase extraction signals.
Specifically, if signal fluctuation due to partial discharge does not occur in a certain section of the extracted signal, the average value obtained by adding the three-phase extracted signals is used as background noise, and if signal fluctuation due to partial discharge occurs in a certain section of the extracted signal, the average value obtained by adding the two-phase extracted signals without signal fluctuation due to partial discharge is used as background noise.
Step S420, obtaining the noise-reduced extracted signal waveform according to the background noise signal waveform and the extracted signal waveforms of each phase.
Specifically, after the extraction of the background noise is completed, the background noise signal waveform is subtracted from each phase extraction signal to obtain the noise-reduced extraction signal waveform.
By utilizing the high symmetry of the three-phase cable voltage, the background noise has strong symmetry, and the background noise can be extracted according to the characteristics. Compared with the traditional noise reduction method, the method has the advantages that steps of noise judgment, noise conversion and the like can be reduced, and the efficiency of partial discharge detection of the three-phase cable and the detection accuracy are greatly improved.
In one embodiment, with continued reference to fig. 8, a partial discharge detection method is provided for use in the partial discharge detection apparatus described above. Including steps S100, S200, S300, S410 and S420.
Step S100, outputting an oscillation wave signal to a three-phase cable to be detected to form a detection path of each phase respectively, wherein the oscillation wave signal is used for exciting the cable of each phase to generate a partial discharge signal;
step S200, extracting partial discharge signals on each phase of detection path, and generating extraction signals corresponding to the partial discharge signals;
step S300, sampling the extracted signals of each phase respectively to obtain the waveform of the extracted signals of each phase;
step S410, acquiring a background noise signal waveform according to the acquired extraction signals of each phase;
step S420, obtaining the noise-reduced extracted signal waveform according to the background noise signal waveform and the extracted signal of each phase.
It should be understood that, although the steps in the flowcharts of fig. 7 and 8 are shown in order as indicated by the arrows, the steps are not necessarily performed in order as indicated by the arrows. The steps are not performed in the exact order shown and described, and may be performed in other orders, unless explicitly stated otherwise. Moreover, at least some of the steps in fig. 7 and 8 may include multiple steps or multiple stages, which are not necessarily performed at the same time, but may be performed at different times, and the order of performing the steps or stages is not necessarily sequential, but may be performed alternately or alternately with other steps or at least some of the other steps or stages.
The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A partial discharge detection apparatus, for use in partial discharge detection of a three-phase cable, the apparatus comprising:
the signal generating module is used for outputting an oscillation wave signal to a three-phase cable to be detected so as to form a detection path of each phase respectively, and the oscillation wave signal is used for exciting each phase of cable to generate a partial discharge signal;
the signal extraction module is used for extracting the partial discharge signals on the detection paths of all phases and generating extraction signals corresponding to the partial discharge signals;
the sampling module is connected with the signal extraction module and is used for sampling the extraction signals of all phases respectively so as to obtain the waveforms of the extraction signals of all phases;
and the noise reduction processing module is connected with the sampling module and used for carrying out noise reduction processing on the waveform of the extracted signal of each sampled phase so as to obtain the waveform of the extracted signal after noise reduction, and analyzing the partial discharge state of the three-phase cable according to the waveform of the extracted signal after noise reduction.
2. The apparatus of claim 1, wherein the signal extraction module comprises a plurality of signal extraction submodules, each of the signal extraction submodules is connected to the signal generation module at one end and is respectively connected to one of three-phase cables at the other end, and each of the signal extraction submodules is configured to extract the partial discharge signal on the detection path of the cable of each phase and generate an extracted signal corresponding to the partial discharge signal.
3. The apparatus of claim 2, wherein the signal extraction sub-module comprises:
the coupling unit is connected with the signal generation module and used for coupling the partial discharge signals on the cable detection paths of all phases to generate coupling signals;
and one end of the filtering unit is connected with the coupling unit, the other end of the filtering unit is used for grounding, the filtering unit is used for filtering low-frequency signal components of the coupling signals, and the filtered coupling signals are used as the extraction signals.
4. The apparatus of claim 3, wherein the filtering unit comprises:
one end of the filter impedance is connected with the coupling unit, and the other end of the filter impedance is grounded;
and the input end of the high-pass filter is connected with one end of the filter impedance in parallel, and the output end of the high-pass filter is connected with the sampling module.
5. The apparatus of claim 4, wherein the filter impedance is an RLC-type parallel circuit.
6. The apparatus of claim 4, wherein the high pass filter is a ninth order elliptic filter.
7. The apparatus of claim 3, wherein the signal extraction module further comprises:
and one end of the blocking reactance is connected with the signal generation module, the other end of the blocking reactance is connected with the coupling unit, and the blocking reactance is used for blocking the partial discharge signal.
8. The apparatus of claim 1, further comprising:
the voltage divider is connected with the signal generation module and used for acquiring an oscillating wave signal and generating a divided voltage signal;
the sampling module is further connected with the voltage divider and is further used for sampling the divided voltage signal so as to monitor the oscillation wave signal in real time.
9. A partial discharge detection method applied to the apparatus according to any one of claims 1 to 8, the method comprising:
outputting an oscillation wave signal to a three-phase cable to be detected to form a detection path of each phase respectively, wherein the oscillation wave signal is used for exciting each phase of cable to generate a partial discharge signal;
extracting the partial discharge signals on the detection paths of the respective phases, and generating extraction signals corresponding to the partial discharge signals;
sampling the extraction signals of each phase respectively to obtain the waveform of the extraction signals of each phase;
and carrying out noise reduction treatment on the waveform of the sampled extraction signal of each phase to obtain the waveform of the noise-reduced extraction signal, and analyzing the partial discharge state of the three-phase cable according to the waveform of the noise-reduced extraction signal.
10. The method according to claim 9, wherein the performing noise reduction processing on the waveform of the extracted signal of each sampled phase to obtain a noise-reduced extracted signal waveform comprises:
acquiring a background noise signal waveform according to the acquired extraction signals of each phase;
and acquiring the extracted signal waveform after noise reduction according to the background noise signal waveform and the extracted signal waveform of each phase.
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