Partial discharge detection circuit and partial discharge detection device

Abstract

The invention relates to a partial discharge detection circuit and partial discharge detection equipment. The circuit comprises a magnetic sensing module, a compensation module and a signal conditioning module, the magnetic sensing module is connected with the compensation module, the magnetic sensing module is connected with the signal conditioning module, and the compensation module is connected with the signal conditioning module; the magnetic sensing module is arranged at a preset position in a preset range of a detected object and is used for acquiring a partial discharge signal of the detected object; the compensation module is used for compensating an external magnetic field of the magnetic sensing module; and the signal conditioning module is used for filtering and amplifying the partial discharge signal to obtain a detection result. The partial discharge detection circuit provided by the invention can realize non-contact partial discharge detection.

Description

Technical Field

[0001] The present application relates to the field of power electronics, and in particular to a partial discharge detection circuit and a partial discharge detection device. Background Art

[0002] Partial discharge detection is a key technology for evaluating the insulation condition of power equipment. In power systems, partial discharge is often an early indicator of insulation material degradation and potential failure. Traditional partial discharge detection technology relies on direct contact sensors, such as high-frequency current transformers, which need to be connected in series with the circuit being tested, limiting its application in remote and mobile sensing technologies. Summary of the invention

[0003] Based on this, it is necessary to provide a non-contact partial discharge detection circuit that can realize partial discharge detection without being connected to the circuit under test.

[0004] A partial discharge detection circuit comprises: a magnetic sensing module, a compensation module and a signal conditioning module, wherein the magnetic sensing module is connected to the compensation module, the magnetic sensing module is connected to the signal conditioning module, and the compensation module is connected to the signal conditioning module;

[0005] The magnetic sensor module is arranged at a preset position within a preset range of the measured object, and is used to obtain a partial discharge signal of the measured object;

[0006] The compensation module is used to compensate the external magnetic field of the magnetic sensor module;

[0007] The signal conditioning module is used to filter and amplify the partial discharge signal to obtain a detection result.

[0008] In one of the embodiments, the compensation module includes a first amplification unit, a first compensation unit, and a second compensation unit;

[0009] The output end of the first amplifying unit is connected to the first end of the first compensation unit, the second end of the first compensation unit is connected to the first end of the second compensation unit, and the second end of the second compensation unit is grounded;

[0010] The first amplifying unit is used to provide driving currents for the first compensation unit and the second compensation unit.

[0011] In one embodiment, the magnetic sensing module includes a full-bridge magnetoresistive sensor, a first output end of the full-bridge magnetoresistive sensor is connected to a positive input end of the first amplifying unit, and a second output end of the full-bridge magnetoresistive sensor is connected to an inverting input end of the first amplifying unit.

[0012] In one embodiment, the compensation module further includes a first current limiting unit and a second current limiting unit, wherein the first end of the first current limiting unit is connected to the first output end of the full-bridge magnetoresistive sensor, and the second end of the first current limiting unit is connected to the positive input end of the first amplifying unit; the first end of the second current limiting unit is connected to the second output end of the full-bridge magnetoresistive sensor, and the second end of the second current limiting unit is connected to the negative input end of the first amplifying unit.

[0013] In one embodiment, the signal conditioning module includes an AC coupling submodule, a first input end of the AC coupling submodule is connected to a first output end of the full-bridge magnetoresistive sensor, and a second input end of the AC coupling submodule is connected to a second output end of the full-bridge magnetoresistive sensor.

[0014] In one embodiment, the AC coupling submodule includes a first filtering unit, a second filtering unit, a third current limiting unit and a fourth current limiting unit:

[0015] The first end of the first filtering unit is connected to the first output end of the full-bridge magnetoresistive sensor, the second end of the first filtering unit is connected to the first end of the third current limiting unit, and the second end of the third current limiting unit is grounded;

[0016] A first end of the second filtering unit is connected to a second output end of the full-bridge magnetoresistive sensor, a second end of the second filtering unit is connected to a first end of the fourth current limiting unit, and a second end of the fourth current limiting unit is grounded.

[0017] In one embodiment, the signal conditioning module further includes a second amplifying unit, a non-phase input terminal of the second amplifying unit is connected to the first output terminal of the AC coupling submodule, and an inverting input terminal of the second amplifying unit is connected to the second output terminal of the AC coupling submodule.

[0018] In one of the embodiments, the signal conditioning module further includes a collection submodule, an input end of the collection submodule is connected to an output end of the second amplification unit, and an output end of the collection submodule is connected to a back-end device.

[0019] In one embodiment, the acquisition submodule includes a coaxial cable and a protection unit, the first end of the coaxial cable is connected to the output end of the second amplification unit, the second end of the coaxial cable is connected to the first end of the protection unit, and the second end of the protection unit is connected to the back-end device.

[0020] A partial discharge detection device comprises the partial discharge detection circuit described in any one of the above embodiments.

[0021] The above partial discharge detection circuit realizes non-contact detection of partial discharge events through a highly sensitive magnetoresistive sensor, a compensation module and a signal conditioning module. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the conventional technology, the drawings required for use in the embodiments or the conventional technology descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0023] Figure 1 A partial discharge detection circuit module according to an embodiment;

[0024] Figure 2 is an electrical schematic diagram of a partial discharge detection circuit of an embodiment;

[0025] Figure 3 A schematic diagram of the structure of a full-bridge magnetoresistive sensor according to an embodiment;

[0026] Figure 4 is a module schematic diagram of a partial discharge detection circuit according to an embodiment;

[0027] Figure 5 One of the experimental data for a specific implementation method;

[0028] Figure 6 This is the second experimental data of a specific implementation method;

[0029] Figure 7 This is the third experimental data of a specific implementation method;

[0030] Figure 8 This is the fourth of experimental data for a specific implementation method. DETAILED DESCRIPTION

[0031] In order to facilitate understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. Embodiments of the present application are provided in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0032] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0033] It is understood that the terms "first", "second", etc. used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish a first element from another element. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0034] It can be understood that the “connection” in the following embodiments should be understood as “electrical connection”, “communication connection”, etc. if the connected circuits, modules, units, etc. have electrical signals or data transmission between each other.

[0035] It can be understood that “at least one” means one or more, “plurality” means two or more, and “at least a portion of an element” means a part or all of an element.

[0036] When used herein, the singular forms "a", "an", and "said / the" may also include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "include / comprise" or "have" and the like specify the presence of stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not exclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. At the same time, the term "and / or" used in this specification includes any and all combinations of the relevant listed items.

[0037] Partial discharge detection is a key technology for evaluating the insulation condition of power equipment. In power systems, partial discharge phenomena (PD phenomena) are often early indicators of insulation material degradation and potential failures. Traditional partial discharge detection technologies rely on direct contact sensors, such as high-frequency current transformers, which need to be connected in series with the circuit being tested, limiting their application in remote and mobile sensing technologies. As power systems move toward intelligence and remote monitoring, the demand for non-contact partial discharge detection technology is growing.

[0038] Existing technologies have a series of challenges and shortcomings in the field of partial discharge (PD) detection. Although traditional contact PD detection methods, such as using high-frequency current transformers (HFCT), have proven their effectiveness in certain applications, they require direct connection to the circuit under test, which limits the flexibility of detection and the ability of remote monitoring.

[0039] Existing non-contact partial discharge detection technologies are mainly based on electromagnetic field measurement, including the use of Hall sensors, fluxgate sensors and various magnetoresistive sensors. Although these technologies have shown certain effects in some applications, they have limitations in sensitivity, dynamic range and environmental adaptability. For example, although the superconducting quantum interference device (SQUID) has extremely high sensitivity, it needs to be cooled to low temperatures, which is costly and complex. Compared with giant magnetoresistive (GMR) sensors, anisotropic magnetoresistive (AMR) and Hall sensors perform poorly in sensitivity and dynamic range. In addition, although the tunnel magnetoresistive (TMR) sensor has superior performance, it has a relatively high noise level, which affects the signal-to-noise ratio.

[0040] Since its discovery in the 1980s, GMR giant magnetoresistance sensors have been widely used in a variety of applications due to their high sensitivity, small size, good thermal stability and wide dynamic range. However, the bandwidth of GMR systems in practical applications is limited, which restricts their ability to detect PD pulse currents. In addition, the dynamic range of GMR sensors is significantly reduced under high external magnetic fields, affecting their performance in complex electromagnetic environments. Therefore, the development of new non-contact PD detection technologies, especially magnetoresistive sensors with high sensitivity, wide dynamic range and good environmental adaptability that can overcome the limitations of existing technologies, is of great significance for improving the reliability and safety of power equipment.

[0041] like Figure 1 and Figure 2 As shown, Figure 1 A schematic diagram of a module of a partial discharge detection circuit provided in this application. Figure 2 The electrical schematic diagram of the partial discharge detection circuit provided in the present application, the present embodiment provides a partial discharge detection circuit, comprising: a magnetic sensing module 100, a compensation module 200 and a signal conditioning module 300, the magnetic sensing module 100 is connected to the compensation module 200, the magnetic sensing module 100 is connected to the signal conditioning module 300, the compensation module 200 is connected to the signal conditioning module 300;

[0042] The magnetic sensing module 100 is arranged at a preset position within a preset range of the measured object, and is used to obtain the local discharge signal of the measured object; the compensation module 200 is used to compensate the external magnetic field of the magnetic sensing module 100; and the signal conditioning module 300 is used to filter and amplify the local discharge signal to obtain the detection result.

[0043] Exemplarily, the object to be measured can be an electric power device such as a high-voltage cable. Since the partial discharge detection circuit provided in this embodiment is contactless, it does not need to be connected to the circuit of the object to be measured, and only needs to be placed within a certain preset range of the object to be measured. In order to ensure the accuracy of the detection result, in actual application, the magnetic sensor module 100 can be placed at multiple preset positions within the preset range to respond to the partial discharge signal of the object to be measured.

[0044] The compensation circuit is used to compensate and calibrate the signal collected by the magnetic sensor module 100 to improve the accuracy and stability of the signal. The signal conditioning module is used to further process the signal collected by the magnetic sensor module 100, including filtering, amplification and other operations to ensure the reliability and stability of the signal.

[0045] In one embodiment, the magnetic sensing module 100 includes a full-bridge magnetoresistive sensor, a first output end of the full-bridge magnetoresistive sensor is connected to a non-inverting input end of the first amplifying unit, and a second output end of the full-bridge magnetoresistive sensor is connected to an inverting input end of the first amplifying unit.

[0046] Exemplarily, the full-bridge magnetoresistive sensor can be a GMR sensor. The GMR effect refers to the significant change in resistance caused by the relative direction of the magnetization vector in a multilayer structure, in which ferromagnetic layers are separated by non-magnetic spacer layers. Depending on the materials and structures used, GMR structures can be divided into multilayer (ML), spin valve (SV), granular alloy (GA) and magnetic tunnel junction (MTJ, also known as TMR). In practical applications, GMR elements are connected in a bridge manner, which includes additional elements such as magnetic shielding and flux concentrators.

[0047] The bridge structure of the GMR sensor is divided into a full-bridge structure and a half-bridge structure. By removing the magnetic shield and the magnetic flux concentrator, the full-bridge structure is obtained. Figure 3 As shown, all four resistor elements are "active", but in different directions relative to the external magnetic field. A full bridge is called a gradiometer and is particularly useful in applications where the gradient of a magnetic field is measured. In addition, the full bridge output is bipolar and twice as large as a half bridge configuration. Exemplarily, this embodiment uses a full bridge GMR sensor consisting of 4 GMR resistors.

[0048] Exemplarily, the present application also provides an independent battery ( ) to power the full-bridge magnetoresistive sensor. A capacitor C8 is connected in parallel between the battery and the full-bridge magnetoresistive sensor, which can temporarily store or release charges and act as a buffer to prevent the impact of spike voltage or current caused by rapid changes on the sensor and battery, while reducing the noise between the battery and the sensor.

[0049] like Figure 4As shown, in one embodiment, the compensation module 200 includes a first amplifying unit 201, a first compensation unit L1 and a second compensation unit L2; the output end of the first amplifying unit 201 is connected to the first end of the first compensation unit L1, the second end of the first compensation unit L1 is connected to the first end of the second compensation unit L2, and the second end of the second compensation unit L2 is grounded; the first amplifying unit 201 is used to provide driving current for the first compensation unit L1 and the second compensation unit L2.

[0050] Exemplarily, the main purpose of the compensation module 200 is to improve the dynamic range of the GMR (Giant Magnetoresistance) sensor under high external magnetic fields. The first compensation unit L1 is an inductor coil, which is used to compensate for the external magnetic field, improve linearity, reduce hysteresis and reduce temperature drift, which helps to offset the influence of the external magnetic field on the GMR sensor, so that the sensor can work more accurately when the external magnetic field changes; in addition, it can also improve the linearity of the relationship between the sensor output and input, making the measurement results easier to analyze and predict, and reducing hysteresis can improve the response speed and accuracy of the sensor; reducing temperature drift means that the performance of the sensor is more stable at different temperatures.

[0051] The effective frequency range of the compensation module 200 is from DC (0 Hz) to the cut-off frequency fcut = 27.67 kHz. This means that within this frequency range, the compensation circuit can function.

[0052] The first amplifying unit 201 uses a low-offset, precision operational amplifier OPA to drive the current required by the compensation coil. The operational amplifier has a small input offset voltage and high precision, which helps to accurately provide the compensation coil with a suitable current, thereby achieving the compensation function.

[0053] The second compensation unit L2 further adjusts the frequency response of the compensation module 200. By adding L2, the 0dB frequency is reduced to 27.67 kHz, so that above the cut-off frequency fcut, the compensation can be almost ignored. This characteristic allows the GMR sensor to selectively respond to the magnetic field generated by a fast pulse signal (such as a PD signal or a transient signal). That is, within a specific frequency range (above 27.67 kHz), the GMR sensor mainly responds to the magnetic field generated by the fast pulse signal without being excessively interfered by the compensation circuit. Exemplarily, the size of L1 can be 36uH, the size of L2 can be 1.8mH, and a resistor R12 can be connected in series after L2 to ground to reduce interference from the ground. The resistance value of R12 can be 50Ω.

[0054] In one embodiment, the compensation module 200 further includes a first current limiting unit R1 and a second current limiting unit R2, wherein the first end of the first current limiting unit R1 is connected to the first output end of the full-bridge magnetoresistive sensor, and the second end of the first current limiting unit R1 is connected to the positive input end of the first amplifying unit 201; the first end of the second current limiting unit R2 is connected to the second output end of the full-bridge magnetoresistive sensor, and the second end of the second current limiting unit R2 is connected to the negative input end of the first amplifying unit 201.

[0055] Exemplarily, the first current limiting unit R1 and the second current limiting unit R2 may use resistors with relatively large resistance values ​​(such as 1 kΩ resistors), which can limit the current in the circuit to a smaller range to prevent component damage.

[0056] In addition, the compensation module 200 also includes resistors R3 and R4, and capacitors C1, C2, and C3; the above components play a role in filtering and reducing noise of the operational amplifier OPA, further improving the accuracy of the operational amplifier OPA.

[0057] In one embodiment, the signal conditioning module includes an AC coupling submodule 301, wherein a first input end of the AC coupling submodule 301 is connected to a first output end of the full-bridge magnetoresistive sensor, and a second input end of the AC coupling submodule 301 is connected to a second output end of the full-bridge magnetoresistive sensor. The AC coupling submodule 301 is mainly used to isolate and eliminate AC interference to ensure the purity and accuracy of the signal.

[0058] In one embodiment, the AC coupling submodule 301 includes a first filtering unit C4, a second filtering unit C5, a third current limiting unit R6 and a fourth current limiting unit R7: the first end of the first filtering unit C4 is connected to the first output end of the full-bridge magnetoresistive sensor, the second end of the first filtering unit C4 is connected to the first end of the third current limiting unit R6, and the second end of the third current limiting unit R6 is grounded; the first end of the second filtering unit C5 is connected to the second output end of the full-bridge magnetoresistive sensor, the second end of the second filtering unit C5 is connected to the first end of the fourth current limiting unit R7, and the second end of the fourth current limiting unit R7 is grounded.

[0059] The AC coupling submodule 301 utilizes the DC isolation and AC passing characteristics of the capacitor to isolate the DC current of the previous stage and couple the AC signal to the next stage amplifier. The AC coupling submodule 301 includes a first filter unit C4 and a third current limiting unit R6 connected in series, and a second filter unit C5 and a fourth current limiting unit R7 connected in series. The capacitor is used to transmit the voltage signal, and the resistor is used to limit the current.

[0060] In addition, the AC coupling submodule 301 can also isolate the DC component, helping to reduce the impact of the DC bias on the circuit. In addition, it can also isolate external and internal AC interference signals, while improving the quality and stability of the signal, making data processing more accurate and reliable. The AC coupling submodule 301 also includes a protection resistor R8, which is connected in series with the third current limiting unit R6 and the fourth current limiting unit R7.

[0061] In one embodiment, the signal conditioning module further includes a second amplifying unit 302, a non-phase input terminal of the second amplifying unit 302 is connected to the first output terminal of the AC coupling submodule 301, and an inverting input terminal of the second amplifying unit 302 is connected to the second output terminal of the AC coupling submodule 301.

[0062] The second amplifying unit 302 uses an operational amplifier of the AD8429 model, which is an instrument amplifier suitable for measuring extremely small signals and can achieve precise measurement of small signals. A resistor R9 is connected in series between the non-inverting input terminal and the inverting input terminal of the second amplifying unit 302 to reduce the offset voltage caused by the input bias current of the operational amplifier. The power supply supplies power to the second amplifying unit 302. Capacitors C6 and C7 are also provided between the power supply to reduce the mutual influence between the power supply and the second amplifying unit 302. A resistor R10 is also provided between the second amplifying unit 302 and the acquisition submodule 303 to play a protective role.

[0063] In one embodiment, the signal conditioning module further includes a collection submodule 303, the input end of the collection submodule 303 is connected to the output end of the second amplification unit 302, and the output end of the collection submodule 303 is connected to the back-end device. In one embodiment, the collection submodule 303 includes a coaxial cable and a protection unit R11, the first end of the coaxial cable is connected to the output end of the second amplification unit 302, the second end of the coaxial cable is connected to the first end of the protection unit R11, and the second end of the protection unit R11 is connected to the back-end device. Data collection and transmission are performed through the coaxial cable, which is convenient for subsequent analysis and processing.

[0064] After the partial discharge detection circuit is built, frequency response and time domain response tests can be performed to verify the performance of the partial discharge detection circuit. Use a vector network analyzer (VNA) to measure the frequency response, and measure the response of the GMR system at different frequencies by applying a sine wave excitation to a rectangular coil. The time domain response test uses a standard pulse calibrator to inject fast pulses into the same rectangular coil, and uses an oscilloscope to record the output of the AD8429 and the pulse calibrator to evaluate the sensitivity of the GMR system to PD pulses. The above experimental method is for illustration only. In actual applications, other experimental methods can be used for verification.

[0065] It is understood that the partial discharge detection circuit can also be in other forms, not limited to the forms mentioned in the above embodiments, as long as it can achieve the function of completing partial discharge detection. The above circuit can be applied to partial discharge detection of electrical equipment.

[0066] In order to describe the partial discharge detection circuit provided by the present application in more detail, a most detailed embodiment is used for explanation. Exemplarily, this embodiment provides an experimental verification of the partial discharge detection circuit, and the magnetic sensor used in the experiment is a GMR sensor.

[0067] Specifically, using HFCT as a reference signal, when the signal peak detected by the GMR system occurs almost simultaneously with the HFCT signal peak and its peak amplitude is approximately twice that of the background noise, it is considered a PD signal. The PDflex software tool was used to process 200 waveform data sets to compare the PRPD patterns of the HFCT and GMR systems. Among them, the PRPD diagram (Phase Resolved Partial Discharge) is an important tool for analyzing partial discharge activity.

[0068] Analyze the PRPD patterns of the GMR system and the HFCT system to verify the GMR system's ability to detect PD signals. Compare the amplitudes of HFCT and GMR signals at different voltages and distances to evaluate the GMR system's response to the PD signal amplitude.

[0069] Specifically, the following experimental equipment and materials can be used:

[0070] Partial discharge detection circuit: includes GMR sensor, signal conditioning module and compensation module.

[0071] High-frequency current transformer (HFCT): used to acquire PD signals, with a bandwidth of 40 kHz to 130 MHz and a gain of 9.1mV / mA.

[0072] Oscilloscope: 500 MHz bandwidth and 625 MS / s sampling rate for signal acquisition.

[0073] PD model: including corona and surface discharge models.

[0074] XLPE cable: A high-voltage cable with artificial defects to simulate actual PD situations.

[0075] Coupling capacitor: provides a low impedance and high frequency path for the PD signal.

[0076] Based on this, surface discharge experiments based on GMR sensors were conducted, which involved crown and surface discharge models, as well as comparisons with high-frequency current transformers (HFCT). In the experiments, two coupling capacitors were used to provide a low impedance and high-frequency path for PD signals, and HFCT was used to collect PD signals with a bandwidth of 40 kHz to 130 MHz and a gain of 9.1 mV / mA. In the experiments, GMR sensors were placed in different positions to test their response to PD signals.

[0077] During the experiment, follow these steps to set up the PD model:

[0078] Use two 2 nF coupling capacitors in series with the PD model to capture the PD signal;

[0079] The HFCT is connected in series with the PD model to collect PD signals;

[0080] Use an oscilloscope to record the signals of the HFCT and GMR sensors.

[0081] For details, see Figure 5 and Figure 6 , Figure 5 , Figure 6 is the experimental result of PD model, Figure 5 , Figure 6 The horizontal axis represents the experimental results of HFCT, and the vertical axis represents the experimental results of the partial discharge detection circuit based on xMR (magnetoresistive sensor, here GMR sensor). The PRPD mode of corona and surface discharge is very close to the results of HFCT, which verifies the effectiveness of the GMR system. The output voltage of the GMR system is proportional to the amplitude of the PD signal and has a good correlation with the amplitude of the HFCT signal. Among them, 401, 402, and 403 respectively represent the experimental results at different voltages; 404, 405, and 406 are the same.

[0082] To further verify the practicality of the partial discharge detection circuit, this application also includes PD experiments in XLPE cables with artificial discharge defects. The cable was tested and confirmed to be PD-free (<5 pC) below 3U0 (18 kVrms). A cavity that causes internal discharge was created by inserting a plastic tie at the interface between the XLPE insulation and the main insulation of the cable joint. The experimental setup is similar to the PD model, with the GMR sensor placed at the joint close to the grounded copper screen.

[0083] During the experiment, the XLPE cable was set up as follows:

[0084] An artificial defect was introduced into a 3-meter-long 6 / 10 kV XLPE cable, and a cavity was created by inserting a plastic tie at the cable joint, which induced internal discharge.

[0085] Connect a 1056 pF coupling capacitor in parallel with the cable;

[0086] Place the GMR sensor near the grounded copper screen (i.e., the preset position) to detect the PD signal;

[0087] Keep the coaxial cable lengths of the HFCT and GMR sensors similar to synchronize the peaks of the two sensor outputs. Record the HFCT and GMR signals simultaneously to ensure that the signal triggered by the GMR system corresponds to an actual PD event.

[0088] See also Figure 7 and Figure 8 , Figure 7 , Figure 8 The experimental results of XLPE cables are shown in Figure 1, namely the PRPD diagrams of HFCT and GMR systems. Figure 7 , Figure 8 The horizontal axis represents the phase, Figure 7 The vertical axis represents the experimental results of HFCT. Figure 8 The vertical axis represents the experimental results of the partial discharge detection circuit based on xMR (magnetoresistive sensor, here GMR sensor). The GMR system is able to detect the PD signal generated from the artificial defects of the XLPE cable, and the PRPD pattern is similar to the results of HFCT. The position and direction of the GMR sensor have a significant impact on the detection results and need to be adjusted to obtain the best signal.

[0089] Through the above technical solution, the non-contact partial discharge detection circuit of the present application can effectively detect and evaluate PD events, and can measure the magnetic field generated by PD even at a distance of up to 50 cm, and has a good correlation with the HFCT signal, providing a new solution for non-contact PD detection of power equipment. From the above experiments, it can be obtained that the sensitivity of the partial discharge detection using GMR sensors in the present application to PD events is very high even when far away from the PD source, which provides a basis for non-contact PD detection of high-voltage cables.

[0090] In one embodiment, a partial discharge detection device is provided, comprising the partial discharge detection circuit described in any one of the above embodiments.

[0091] In the description of this specification, the description with reference to the terms "some embodiments", "other embodiments", etc. means 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 description of the above terms does not necessarily refer to the same embodiment or example.

[0092] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0093] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A partial discharge detection circuit, characterized in that: The circuit comprises: a magnetic sensing module, a compensation module and a signal conditioning module, wherein the magnetic sensing module is connected to the compensation module, the magnetic sensing module is connected to the signal conditioning module, and the compensation module is connected to the signal conditioning module; The magnetic sensor module is arranged at a preset position within a preset range of the measured object, and is used to obtain a partial discharge signal of the measured object; The compensation module is used to compensate the external magnetic field of the magnetic sensor module; The signal conditioning module is used to filter and amplify the partial discharge signal to obtain a detection result.

2. The partial discharge detection circuit according to claim 1, characterized in that: The compensation module includes a first amplification unit, a first compensation unit and a second compensation unit; The output end of the first amplifying unit is connected to the first end of the first compensation unit, the second end of the first compensation unit is connected to the first end of the second compensation unit, and the second end of the second compensation unit is grounded; The first amplifying unit is used to provide driving currents for the first compensation unit and the second compensation unit.

3. The partial discharge detection circuit according to claim 2, characterized in that: The magnetic sensing module includes a full-bridge magnetoresistive sensor, a first output end of the full-bridge magnetoresistive sensor is connected to a non-inverting input end of the first amplifying unit, and a second output end of the full-bridge magnetoresistive sensor is connected to an inverting input end of the first amplifying unit.

4. The partial discharge detection circuit according to claim 3, characterized in that: The compensation module also includes a first current limiting unit and a second current limiting unit, wherein the first end of the first current limiting unit is connected to the first output end of the full-bridge magnetoresistive sensor, and the second end of the first current limiting unit is connected to the positive input end of the first amplifying unit; the first end of the second current limiting unit is connected to the second output end of the full-bridge magnetoresistive sensor, and the second end of the second current limiting unit is connected to the negative input end of the first amplifying unit.

5. The partial discharge detection circuit according to claim 3, characterized in that: The signal conditioning module comprises an AC coupling submodule, a first input end of the AC coupling submodule is connected to a first output end of the full-bridge magnetoresistive sensor, and a second input end of the AC coupling submodule is connected to a second output end of the full-bridge magnetoresistive sensor.

6. The partial discharge detection circuit according to claim 5, characterized in that: The AC coupling submodule includes a first filtering unit, a second filtering unit, a third current limiting unit and a fourth current limiting unit: The first end of the first filtering unit is connected to the first output end of the full-bridge magnetoresistive sensor, the second end of the first filtering unit is connected to the first end of the third current limiting unit, and the second end of the third current limiting unit is grounded; A first end of the second filtering unit is connected to a second output end of the full-bridge magnetoresistive sensor, a second end of the second filtering unit is connected to a first end of the fourth current limiting unit, and a second end of the fourth current limiting unit is grounded.

7. The partial discharge detection circuit according to claim 5, characterized in that: The signal conditioning module further includes a second amplifying unit, a non-phase input terminal of the second amplifying unit is connected to the first output terminal of the AC coupling submodule, and an inverting input terminal of the second amplifying unit is connected to the second output terminal of the AC coupling submodule.

8. The partial discharge detection circuit according to claim 7, characterized in that: The signal conditioning module further includes a collection submodule, an input end of the collection submodule is connected to an output end of the second amplifying unit, and an output end of the collection submodule is connected to a back-end device.

9. The partial discharge detection circuit according to claim 8, characterized in that: The acquisition submodule includes a coaxial cable and a protection unit, the first end of the coaxial cable is connected to the output end of the second amplification unit, the second end of the coaxial cable is connected to the first end of the protection unit, and the second end of the protection unit is connected to the back-end device.

10. A partial discharge detection device, characterized in that: The method comprises a partial discharge detection circuit according to any one of claims 1 to 9.

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