Sound signal and radio frequency signal integrated sensor, built-in sensor and detection device

Abstract

The invention provides a sound signal and radio frequency signal integrated sensor. The sound signal and radio frequency signal integrated sensor comprises a packaging unit and a detection unit, the packaging unit is a closed shell, and one end face of the closed shell is closed by an insulating plate; the detection unit comprises a radio frequency sensor fixed in the closed shell and a fiber bragg grating sensor embedded in the outer surface of the insulating plate, the receiving end of the fiber bragg grating sensor faces outwards, the radio frequency sensor transmits a signal to the outside of the closed shell through a radio frequency signal transmission line, and the fiber bragg grating sensor penetrates through the closed shell from the insulating plate through an optical fiber for signal transmission; the optical fiber is away from the receiving end of the radio-frequency sensor. The sound signal and radio frequency signal integrated sensor provided by the invention is simple in structure, long in service life, good in external interference resistance and accurate and reliable in monitoring result, and holes do not need to be formed in a transformer oil tank for many times when the sensor is used for partial discharge detection of a power transformer.

Description

Technical Field

[0001] The present invention relates to the field of electrical equipment and measurement technology, and in particular to an acoustic signal and radio frequency signal integrated sensor, a built-in sensor and a detection device. Background Art

[0002] Power transformers are the core equipment of power systems, and their safe and stable operation is of great significance to the reliability and economy of power systems. Accurate monitoring of partial discharge inside transformers and other phenomena is of great significance to the operation safety, service life prediction and maintenance cycle setting of power transformers. Therefore, exploring and finding more accurate monitoring methods has great engineering application value for monitoring acoustic and electrical phenomena such as partial discharge inside transformers, monitoring partial discharge phenomena of power transformers, and effectively identifying power transformer faults. At present, partial discharge and other phenomena in the operation of power transformers are mainly monitored by ultrasonic signals, radio frequency signal monitoring, high-frequency signal monitoring and other methods. As one of the means of detecting partial discharge inside transformers, ultrasonic sensors mainly use magnetic PTZ sensors to adsorb them on the transformer casing. Due to the attenuation of the acoustic signal by the box wall, their detection sensitivity is low. On the other hand, their casing is a metal structure. When they are built in, the electric field distribution inside the transformer will be changed, which will pose a great threat to the insulation of the transformer. Radio frequency sensors are divided into built-in and external types. Among them, built-in radio frequency sensors have strong resistance to external electromagnetic signal interference and high detection sensitivity with the help of the magnetic shielding structure of the transformer. In recent years, they have been gradually applied to transformer partial discharge detection. However, RF sensors can usually only distinguish a single signal and cannot accurately determine the sum of the partial discharge signals of a three-phase transformer. Therefore, there are limitations in the detection of partial discharge of a three-phase transformer. Although increasing the number of RF sensors can improve the judgment accuracy to a certain extent, discharge signals of different phases may interfere with or couple with each other, causing changes in the signal characteristics received by the RF sensor. When multiple RF sensors work at the same time, these electromagnetic fields may overlap with each other, thereby interfering with the normal operation of the transformer. This interference may affect the voltage and current waveforms of the transformer and even cause the transformer to degrade in performance or malfunction. In addition, holes need to be drilled in the wall of the transformer box when installing built-in sensors, and multiple holes need to be drilled in the wall when installing different built-in sensors, which will cause the mechanical strength of the oil tank to decrease. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides an integrated acoustic signal and radio frequency signal sensor which does not require multiple holes to be opened on the transformer oil tank, has a simple structure, has a long service life, has good resistance to external interference, and produces accurate and reliable monitoring results.

[0004] To achieve the above-mentioned object, the technical solution adopted by the present invention is as follows: an acoustic signal and radio frequency signal integrated sensor, comprising a packaging unit and a detection unit;

[0005] The packaging unit is a closed shell, one end surface of which is closed by an insulating plate;

[0006] The detection unit includes a first sensor and a second sensor;

[0007] The first sensor includes a radio frequency sensor and a radio frequency signal transmission line; the radio frequency sensor is fixed in the closed shell, one end of the radio frequency signal transmission line is connected to the radio frequency sensor, and the other end of the radio frequency signal transmission line passes through the side wall of the closed shell and extends to the outside of the closed shell;

[0008] The second sensor includes a fiber grating sensor and an optical fiber; the fiber grating sensor is embedded in the outer surface of the insulating plate, the receiving end of the fiber grating sensor faces outward, and the receiving end of the fiber grating sensor is flush with the outer surface of the insulating plate, one end of the optical fiber is connected to the fiber grating sensor, and the other end of the optical fiber passes through the insulating plate, the radio frequency sensor and the other end surface of the closed shell in sequence, or the other end of the optical fiber passes through the insulating plate and the other end surface of the closed shell in sequence, and the optical fiber is far away from the receiving end of the radio frequency sensor.

[0009] Furthermore, the radio frequency sensor includes a double-arm Archimedean spiral antenna.

[0010] Furthermore, the optical fiber passes through the gap between the spiral lines near the edge of the double-arm Archimedean spiral antenna.

[0011] Further, the packaging unit includes a mounting portion, a packaging shell and the insulating plate;

[0012] One end of the encapsulation shell is open and the other end of the encapsulation shell is closed, a first through hole is formed at the closed end of the encapsulation shell, and a second through hole is formed on the side wall of the encapsulation shell; the optical fiber passes through the first through hole, and the radio frequency signal transmission line passes through the second through hole;

[0013] The mounting portion is sealed and fixed at the open end edge of the packaging shell;

[0014] The insulating plate is sealingly mounted on the mounting portion, and the insulating plate is used to close the open end of the packaging shell.

[0015] Furthermore, the packaging shell includes a packaging tube and a packaging cover;

[0016] The two ends of the packaging tube are connected, and the second through hole is provided on the side wall of the packaging tube;

[0017] The packaging cover is sealed and fixed to one end of the packaging tube, and the first through hole is formed in the packaging cover.

[0018] Furthermore, a first sealing interface is installed in the first through hole, and the optical fiber passes through the first through hole through the first sealing interface; a second sealing interface is installed in the second through hole, and the RF signal transmission line passes through the second through hole through the second sealing interface.

[0019] Furthermore, the insulating plate is provided with a first mounting groove, a second mounting groove and a third through hole; the second mounting groove is connected and arranged between the first mounting groove and the third through hole; the first mounting groove and the second mounting groove are provided on the outer surface of the insulating plate;

[0020] The fiber grating sensor is fixed in the first installation groove; the middle part of the optical fiber passes through the third through hole, and the end of the optical fiber connected to the fiber grating sensor is embedded in the second installation groove.

[0021] Furthermore, a third sealing interface is installed in the third through hole, and the optical fiber passes through the third through hole through the third sealing interface.

[0022] A built-in sensor for partial discharge detection of a power transformer, comprising a packaging unit and a detection unit;

[0023] The packaging unit is a closed shell, one end surface of which is closed by an insulating plate;

[0024] The detection unit includes a first sensor and a second sensor;

[0025] The first sensor includes a radio frequency sensor and a radio frequency signal transmission line; the radio frequency sensor is fixed in the closed shell, one end of the radio frequency signal transmission line is connected to the radio frequency sensor, and the other end of the radio frequency signal transmission line passes through the side wall of the closed shell and extends to the outside of the closed shell;

[0026] The second sensor comprises a fiber grating sensor and an optical fiber; the fiber grating sensor is embedded in the outer surface of the insulating plate, the receiving end of the fiber grating sensor faces outward, and the receiving end of the fiber grating sensor is flush with the outer surface of the insulating plate, one end of the optical fiber is connected to the fiber grating sensor, and the other end of the optical fiber passes through the insulating plate, the radio frequency sensor and the other end surface of the closed shell in sequence, or the other end of the optical fiber passes through the insulating plate and the other end surface of the closed shell in sequence, and the optical fiber is far away from the receiving end of the radio frequency sensor;

[0027] When in use, the closed shell is fixed on the inner wall of the oil tank of the power transformer, and the outer surface of the insulating plate is in contact with the inner wall of the oil tank.

[0028] A detection device for detecting partial discharge of a power transformer, comprising the acoustic signal and radio frequency signal integrated sensor, and a signal processing unit;

[0029] The other end of the radio frequency signal transmission line and the other end of the optical fiber are respectively connected to the input end of the signal processing unit.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] (1) In practical application, the present invention does not require multiple holes to be drilled in the transformer oil tank, thereby ensuring the structural strength and service life of the transformer oil tank, and has a simple structure, which can be easily installed and used;

[0032] (2) The present invention integrates the fiber Bragg grating sensor and the radio frequency sensor through a closed unit, which can ensure that the fiber Bragg grating sensor and the radio frequency sensor respectively operate stably and reliably for a long time, and the signals between the two sensors will not interfere with each other, nor will they interfere with the operation of the transformer;

[0033] (3) The present invention integrates the fiber grating sensor with the radio frequency sensor to improve the monitoring sensitivity of the partial discharge signal inside the transformer and improve the limitations;

[0034] (4) The present invention has better resistance to external interference through the built-in form, which is beneficial to improving the accuracy and reliability of transformer partial discharge monitoring. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a cross-sectional view of the present invention cut along the flange axis;

[0036] Figure 2 A perspective view of the present invention;

[0037] Figure 3 It is a front view of the present invention;

[0038] Figure 4 It is a structural schematic diagram of the detection device in the present invention;

[0039] Figure 5 These are the test results of Example 2 of the present invention, (a) is the RF signal waveform detected by the sensor integrating acoustic signal and RF signal, (b) is the signal waveform detected by a single RF sensor, (c) is the acoustic signal waveform of the sensor integrating acoustic signal and RF signal, and (d) is the signal waveform detected by a single fiber Bragg grating sensor.

[0040] Among them, the figure markings are: 100, packaging unit; 110, flange; 111, spacer; 112, mounting hole; 120, packaging tube; 130, packaging cover; 140, insulating plate; 150, first sealing interface; 160, second sealing interface; 170, third sealing interface; 180, sealing gasket; 211, fiber grating sensor; 212, optical fiber; 221, radio frequency sensor; 222, radio frequency signal transmission line; 300, signal processing unit. DETAILED DESCRIPTION

[0041] Compared with ultrasonic sensors, fiber grating sensors based on the grating demodulation principle have higher utilization value. When placed in the complex environment inside the transformer, they will not pose a threat to the transformer insulation. However, fiber grating sensors usually need to be installed by drilling holes in the oil tank, and there may be high temperature and high pressure environments in the transformer tank. It is necessary to ensure that the fiber grating sensor can withstand these extreme conditions. At the same time, the transformer oil may contain impurities or corrosive substances. It is necessary to ensure that the sensor surface is not affected by the oil quality, and clean the sensor surface regularly to prevent dirt accumulation.

[0042] In order to clearly illustrate the technical features of this solution, this solution is described below through a specific implementation method.

[0043] See also Figure 1-3 , an acoustic signal and radio frequency signal integrated sensor, comprising a packaging unit 100 and a detection unit; the packaging unit 100 is used to install the acoustic signal and radio frequency signal integrated sensor on the inner wall of the transformer oil tank on the one hand, and on the other hand, it can ensure the stability and reliability of the sensor, improve the performance of the sensor, and adapt to the harsh environment in the transformer oil tank;

[0044] The packaging unit 100 is a closed shell, one end surface of which is closed by an insulating plate 140;

[0045] The packaging unit 100 includes a mounting portion, a packaging shell and an insulating plate 140; preferably, the insulating plate 140 is made of epoxy resin;

[0046] One end of the encapsulation shell is open and the other end of the encapsulation shell is closed, a first through hole is formed at the closed end of the encapsulation shell, and a second through hole is formed on the side wall of the encapsulation shell;

[0047] The mounting portion is sealed and fixed at the edge of the open end of the packaging shell;

[0048] The insulating plate 140 is sealingly mounted on the mounting portion, and the insulating plate 140 is used to close the open end of the packaging shell.

[0049] The packaging shell includes a packaging tube 120 and a packaging cover 130;

[0050] The two ends of the packaging tube 120 are connected, and a second through hole is provided on the side wall of the packaging tube 120;

[0051] The packaging cover 130 is sealed and fixed to one end of the packaging tube 120, and a first through hole is provided on the packaging cover 130; the packaging cover 130 is connected to the packaging tube 120 by bolts, and the connection is sealed to ensure the sealing of the connection, and a sealing gasket can be used for sealing;

[0052] See also Figure 1 , the mounting portion is a flange 110, a plurality of mounting holes 112 are provided on the flange 110, a packaging tube 120 is connected to the edge of one side of the flange 110 near the flange hole, the flange 110 and the packaging tube 120 are connected by welding, the flange hole is closed by an insulating plate 140 on the other side of the flange 110, and a sealing gasket 180 is provided at the connection between the insulating plate 140 and the flange 110 to ensure the sealing of the connection; preferably, the packaging tube 120 is cylindrical, and since the flange 110 is annular and the radio frequency sensor 221 is disc-shaped, the packaging tube 120 is set to be cylindrical, which can minimize the volume of the integrated sensor; specifically, fixing grooves are provided on both sides of the flange 110 near the flange hole, the fixing groove on one side of the flange 110 is used to fix the packaging tube 120, and the fixing groove on the other side of the flange 110 is used to fix the insulating plate 140;

[0053] The detection unit includes a first sensor and a second sensor;

[0054] The first sensor includes a radio frequency sensor 221 and a radio frequency signal transmission line 222; preferably, the radio frequency sensor 221 includes a double-arm Archimedean spiral antenna, and the center line of the radio frequency sensor 221 is colinear with the center line of the flange 110, that is, the radio frequency sensor 221 is laid flat on the flange hole of the flange 110, preferably, the outer diameter of the radio frequency sensor 221 matches the inner diameter of the side wall of the packaging shell, that is, the outer diameter of the radio frequency sensor 221 matches the inner diameter of the packaging tube 120, which can minimize the volume of the integrated sensor; the radio frequency sensor 221 is fixed in the closed shell, and the radio frequency sensor 22 1 is colinear with the center line of the packaging tube 120, the RF sensor 221 is installed on the corresponding fixing groove and is located on the inner side of the packaging tube 120, one end of the RF signal transmission line 222 is connected to the RF sensor 221, and the other end of the RF signal transmission line 222 passes through the second through hole on the side wall of the closed shell and extends to the outside of the closed shell; the second sealing interface 160 is installed in the second through hole, and the RF signal transmission line 222 passes through the second through hole through the second sealing interface 160, and the second sealing interface is a RF signal interface, that is, the RF signal transmission line 222 is led out of the closed shell through the RF signal interface.

[0055] The second sensor includes a fiber grating sensor 211 and an optical fiber 212; the fiber grating sensor 211 is embedded in the outer surface of the insulating plate 140, the receiving end of the fiber grating sensor 211 faces outward, and the receiving end of the fiber grating sensor 211 is flush with the outer surface of the insulating plate 140 to ensure that when in use, the receiving end of the fiber grating sensor 211 can directly contact the transformer oil; preferably, the packaging base of the fiber grating sensor 211 is made of glass fiber board, and the optical fiber 212 is made of polyimide material;

[0056] When the outer diameter of the RF sensor 221 matches the inner diameter of the side wall of the encapsulation shell, that is, the RF signal transmission line 222 is fully laid inside the encapsulation shell, one end of the optical fiber 212 is connected to the fiber grating sensor 211, and the other end of the optical fiber 212 sequentially penetrates the insulating plate 140, the RF sensor 221 and the other end surface of the closed shell, that is, the encapsulation cover 130, and the optical fiber 212 penetrates the spiral line gap near the edge of the double-arm Archimedean spiral antenna, and the optical fiber 212 is far away from the receiving end of the RF sensor 221;

[0057] When the outer diameter of the RF sensor 221 does not match the inner diameter of the side wall of the packaging shell, one end of the optical fiber 212 is connected to the fiber grating sensor 211, and the optical fiber 212 can pass through the packaging shell from the outside of the RF sensor 221. At this time, the other end of the optical fiber 212 sequentially passes through the insulating plate 140 and the other end surface of the closed shell. The optical fiber 212 can also pass through the packaging shell from where the RF sensor 221 is located. At this time, the other end of the optical fiber 212 sequentially passes through the insulating plate 140, the RF sensor 221 and the other end surface of the closed shell, i.e., the packaging cover 130, and the optical fiber 212 is far away from the receiving end of the RF sensor 221.

[0058] The insulating plate 140 is provided with a first mounting groove, a second mounting groove and a third through hole; the second mounting groove is connected and arranged between the first mounting groove and the third through hole; the first mounting groove and the second mounting groove are provided on the outer surface of the insulating plate 140;

[0059] The fiber grating sensor 211 is fixed in the first installation groove; the middle part of the optical fiber 212 passes through the third through hole, and the end of the optical fiber 212 connected to the fiber grating sensor 211 is embedded in the second installation groove.

[0060] A third sealing interface is installed in the third through hole, and the optical fiber passes through the third through hole through the third sealing interface. The third sealing interface is a cast-type optical fiber sealing port, that is, the optical fiber 212 is introduced into the closed shell through the cast-type optical fiber sealing port.

[0061] A first sealing interface is installed in the first through hole, and the optical fiber 212 passes through the first through hole through the first sealing interface. The first sealing interface is an optical fiber through-hole, that is, the optical fiber 212 is led out of the closed housing through the optical fiber through-hole;

[0062] That is, after the optical fiber 212 is introduced into the closed housing through the cast optical fiber sealing port, it passes through the radio frequency sensor 221 or does not pass through the radio frequency sensor 221, and then is led out of the closed housing through the optical fiber through-hole;

[0063] The fiber grating sensor 211 is integrated with the radio frequency sensor 221 to achieve the same-point measurement of the local discharge acoustic signal and the radio frequency electromagnetic signal inside the transformer, thereby improving the reliability and accuracy of the detection result. Preferably, the center line of the radio frequency sensor 221 runs through the center of the fiber grating sensor 211. When in use, the receiving part of the radio frequency sensor 221 is at the same height as the receiving part of the fiber grating sensor 211, thereby further improving the reliability and accuracy of the detection result, and at the same time making the integrated sensor structure layout reasonable and beautiful in appearance;

[0064] The fiber grating sensor 211 is an optical broadband acoustic sensor. When the optical broadband acoustic sensor uses a Bragg grating, the period and refractive index of the grating will change when the external physical quantity including the acoustic wave pressure changes, thereby changing the wavelength of the light wave passing through the grating, and realizing the detection of the acoustic signal of the audible sound and ultrasonic frequency band of the local discharge inside the transformer. When the optical broadband acoustic sensor receives the acoustic signal, the change rate of the central wavelength of the Bragg grating is shown in Formula 1, which is:

[0065] Δλ B =λ B [(1-p ε )ε+(α Λ +α n )ΔT];

[0066] In the formula, Δλ B It represents the rate of change of the central wavelength of the Bragg grating when the optical broadband acoustic sensor receives the acoustic signal, λ B represents the central wavelength of the Bragg grating in the initial state of the optical broadband acoustic sensor, ε is the applied strain, which appears as an acoustic wave in the optical broadband acoustic sensor, and p ε is the strain optical coefficient of the optical fiber, ΔT is the temperature change, α Λ represents the thermal expansion coefficient of the optical fiber, α n Represents the thermo-optical coefficient of the optical fiber.

[0067] It can be seen that the measurement of the acoustic signal by the optical broadband acoustic sensor, i.e., the fiber Bragg grating sensor 211, is not affected by the electromagnetic signal. The reliability of the signal collected by the fiber Bragg grating sensor 211 can be ensured as long as the received signal is not affected by the electromagnetic signal during the transmission process. The middle of the radio frequency sensor 221 is the signal receiving end. Therefore, the optical fiber 212 needs to be far away from the signal receiving end in the middle of the radio frequency sensor 221.

[0068] The radio frequency sensor 221 is a radio frequency electromagnetic signal sensor. The radio frequency electromagnetic signal sensor receives electromagnetic signals of a specific frequency through a radio frequency antenna. The radio frequency antenna of the radio frequency electromagnetic signal sensor receives electromagnetic signals of a specific bandwidth by changing the inner and outer diameters of the antenna. Taking the double-arm Archimedean spiral antenna as an example, the upper and lower limits of the receiving frequency of the double-arm Archimedean spiral antenna are respectively as shown in Formula 2: Formula 2 is:

[0069]

[0070] In the formula, R out is the outer diameter of the double-arm Archimedean spiral antenna; R in is the inner diameter of the double-arm Archimedean spiral antenna; f L is the lower limit of the receiving frequency of the double-arm Archimedean spiral antenna; π is the circumference of a circle, f U is the upper limit of the receiving frequency of the double-arm Archimedean spiral antenna, c represents the speed of light, and its value is 3×10 8 m / s.

[0071] Therefore, it can be seen that the upper and lower limits of the receiving frequency of the radio frequency electromagnetic signal are only related to the inner and outer diameters of the antenna of the radio frequency electromagnetic signal.

[0072] Through the principle analysis of the above-mentioned fiber grating sensor 211 and radio frequency sensor 221, it can be known that when the fiber grating sensor 211 senses the partial discharge signal, it is only related to the change of the central wavelength of the grating area caused by the intensity of the acoustic signal. When the radio frequency sensor 221 senses the partial discharge, it is only related to the inner and outer diameters of the antenna. This theoretically verifies that the integrated sensors of broadband acoustic signals and radio frequency electromagnetic signals do not interfere with each other during measurement.

[0073] By integrating the fiber grating sensor 211 and the radio frequency sensor 221, it is not necessary to drill holes in the transformer oil tank for many times, thereby ensuring the structural strength and service life of the transformer oil tank, and the fiber grating sensor 211 is fixedly embedded in the middle of the insulating plate 140, which can avoid the fiber grating sensor 211 from directly contacting the high temperature and high pressure environment in the transformer oil tank to the greatest extent, and at the same time ensure the quality of the oil in contact with the fiber grating sensor 211, avoid the accumulation of impurities or corrosive substances on the fiber grating sensor 211, and ensure the accuracy and service life of the data collected by the fiber grating sensor 211; at the same time, The RF sensor 221 is packaged through a packaging unit to ensure the long-term stability, reliability and service life of the RF sensor 221; at the same time, the integration of the fiber grating sensor 211 and the RF sensor 221 will not cause mutual interference or coupling between the detection signals, nor will it interfere with the normal operation of the transformer. In addition, the built-in fiber grating sensor 211 and the RF sensor 221 have higher sensitivity for monitoring the partial discharge signal inside the transformer and better resistance to external interference. The monitoring method integrated by the fiber grating sensor 211 and the RF sensor 221 is conducive to improving the accuracy and reliability of transformer partial discharge monitoring.

[0074] Experimental Example 1

[0075] In order to verify the sealing of the overall structure of the integrated sensor for acoustic signals and radio frequency signals, the integrated sensor was installed on a metal test oil tank, and 0.35MPa of transformer oil was injected into the test oil tank (the pressure in a normally operating transformer is between 0.2-0.3MPa). According to the relevant standards for factory tests of transformer oil tanks, the test oil tank with the integrated sensor installed was left to stand for 24 hours to observe whether there was oil leakage at each connection and each connection of the integrated sensor, such as the connection between the flange 110 and the insulating plate 140, the connection between the packaging cover 130 and the packaging tube 120, the first through hole, the second through hole, the third through hole, etc. According to the test results, no transformer oil leakage was found.

[0076] A built-in sensor for partial discharge detection of a power transformer, comprising a packaging unit 100 and a detection unit;

[0077] The packaging unit 100 is a closed shell, one end surface of which is closed by an insulating plate 140;

[0078] The detection unit includes a first sensor and a second sensor;

[0079] The first sensor includes a radio frequency sensor 221 and a radio frequency signal transmission line 222; the radio frequency sensor 221 is fixed in the closed shell, one end of the radio frequency signal transmission line 222 is connected to the radio frequency sensor 221, and the other end of the radio frequency signal transmission line 222 passes through the side wall of the closed shell and extends to the outside of the closed shell;

[0080] The second sensor includes a fiber grating sensor 211 and an optical fiber 212; the fiber grating sensor 211 is embedded in the outer surface of the insulating plate 140, the receiving end of the fiber grating sensor 211 faces outward, and the receiving end of the fiber grating sensor 211 is flush with the outer surface of the insulating plate 140, one end of the optical fiber 212 is connected to the fiber grating sensor 211, and the other end of the optical fiber 212 passes through the insulating plate 140, the radio frequency sensor 221 and the other end surface of the closed shell in sequence, or the other end of the optical fiber 212 passes through the insulating plate 140 and the other end surface of the closed shell in sequence, and the optical fiber 212 is far away from the receiving end of the radio frequency sensor 221;

[0081] When in use, the closed shell is fixed on the inner wall of the oil tank of the power transformer, and the outer surface of the insulating plate 140 is in contact with the inner wall of the oil tank.

[0082] See also Figure 4 , a detection device for partial discharge detection of a power transformer, comprising an integrated sensor for acoustic signals and radio frequency signals, and a signal processing unit;

[0083] The other end of the RF signal transmission line 222 and the other end of the optical fiber 212 are respectively connected to the input end of the signal processing unit 300. Preferably, the other end of the optical fiber 212 is connected to the signal processing unit 300 via an optical fiber jumper.

[0084] Experimental Example 2

[0085] A square test oil tank is designed according to the actual transformer size ratio. The internal setting of the test oil tank can generate typical defect models in transformer oil (including: high-voltage spikes in oil, metal particles in oil, and transformer oil degradation), and obtain local discharge signals of different defect models. An oil tank mounting hole complementary to the mounting hole 112 on the flange 110 is opened on the side wall of the test oil tank, and the height of the oil tank mounting hole is the same as the typical defect model; secondly, the integrated sensor is installed on the oil tank mounting hole corresponding to the test oil tank. During installation, the packaging cover 130 is built into the test oil tank outside the transformer to detect the discharge signal generated by the typical local discharge model; the two side walls adjacent to the side wall for installing the integrated sensor are the first side wall and the second side wall, respectively, wherein the first side wall is only installed with radio frequency sensors of the same specification, and the second side wall is only installed with fiber grating sensors of the same manufacturing process, and the installation height of the radio frequency sensor on the first side wall and the installation height of the fiber grating sensor on the second side wall are respectively consistent with the typical defect model.

[0086] The detection of the discharge acoustic signal collected by the integrated sensor is performed by connecting the optical fiber through-hole and the photoelectric conversion circuit for back-end collection through an optical fiber jumper, and converting the optical signal detected by the fiber grating sensor 211 into a voltage signal. The detection of the radio frequency electromagnetic signal uses a wide-band radio frequency line to connect the radio frequency signal transmission line 222 to lead out the voltage signal detected by the radio frequency sensor 221. The first signal obtained by the fiber grating sensor 211 and the second signal obtained by the radio frequency sensor 221 are respectively connected to the signal processing unit, and can be connected to the same oscilloscope, ensuring that the wiring methods of the measurement circuits for obtaining the first signal and the second signal are independent of each other, ensuring that the signal transmission circuits do not interfere with each other during measurement;

[0087] The outside of the test tank is connected to a high-voltage test power supply, and the electric field strength near the typical defect model inside the test tank is increased by a step-by-step voltage increase method, so that a partial discharge signal is generated. The waveforms of the partial discharge acoustic signal and radio frequency electromagnetic signal are displayed using an oscilloscope. By continuously increasing the voltage, the waveforms of the acoustic signal and radio frequency electromagnetic signal of different typical defects under different severity levels of partial discharge are obtained, see Figure 5 , by comparing the first signal detected by the integrated sensor proposed in the present disclosure Figure 5 (c) Second signal Figure 5 (a) and the signal detected by the single RF sensor on the first side wall (referred to as the third signal) Figure 5 (b) Signal detected by a single fiber Bragg grating sensor on the second side wall (referred to as the fourth signal) Figure 5 (d), and the waveforms, peak values, and peak occurrence times of the second and third signals, according to Figure 5 It can be seen from the test waveform that the integrated sensor proposed in this patent disclosure is designed to prevent the acoustic signal and the radio frequency signal from interfering with each other during partial discharge detection.

[0088] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. An integrated acoustic signal and radio frequency signal sensor, characterized in that: It includes a packaging unit and a detection unit; The packaging unit is a closed shell, one end surface of which is closed by an insulating plate; The detection unit includes a first sensor and a second sensor; The first sensor includes a radio frequency sensor and a radio frequency signal transmission line; the radio frequency sensor is fixed in the closed shell, one end of the radio frequency signal transmission line is connected to the radio frequency sensor, and the other end of the radio frequency signal transmission line passes through the side wall of the closed shell and extends to the outside of the closed shell; The second sensor includes a fiber grating sensor and an optical fiber; the fiber grating sensor is embedded in the outer surface of the insulating plate, the receiving end of the fiber grating sensor faces outward, and the receiving end of the fiber grating sensor is flush with the outer surface of the insulating plate, one end of the optical fiber is connected to the fiber grating sensor, and the other end of the optical fiber passes through the insulating plate, the radio frequency sensor and the other end surface of the closed shell in sequence, or the other end of the optical fiber passes through the insulating plate and the other end surface of the closed shell in sequence, and the optical fiber is far away from the receiving end of the radio frequency sensor.

2. The acoustic signal and radio frequency signal integrated sensor according to claim 1, characterized in that: The radio frequency sensor includes a double-arm Archimedean spiral antenna.

3. The acoustic signal and radio frequency signal integrated sensor according to claim 2, characterized in that: The optical fiber runs through the spiral line gaps near the edge of the double-arm Archimedean spiral antenna.

4. The acoustic signal and radio frequency signal integrated sensor according to claim 1, characterized in that: The packaging unit comprises a mounting portion, a packaging shell and the insulating plate; One end of the encapsulation shell is open and the other end of the encapsulation shell is closed, a first through hole is formed at the closed end of the encapsulation shell, and a second through hole is formed on the side wall of the encapsulation shell; the optical fiber passes through the first through hole, and the radio frequency signal transmission line passes through the second through hole; The mounting portion is sealed and fixed at the open end edge of the packaging shell; The insulating plate is sealingly mounted on the mounting portion, and the insulating plate is used to close the open end of the packaging shell.

5. The acoustic signal and radio frequency signal integrated sensor according to claim 4, characterized in that: The packaging shell comprises a packaging tube and a packaging cover; The two ends of the packaging tube are connected, and the second through hole is provided on the side wall of the packaging tube; The packaging cover is sealed and fixed to one end of the packaging tube, and the first through hole is formed in the packaging cover.

6. The acoustic signal and radio frequency signal integrated sensor according to claim 4 or 5, characterized in that: A first sealing interface is installed in the first through hole, and the optical fiber passes through the first through hole through the first sealing interface; a second sealing interface is installed in the second through hole, and the radio frequency signal transmission line passes through the second through hole through the second sealing interface.

7. The acoustic signal and radio frequency signal integrated sensor according to claim 4, characterized in that: The insulating plate is provided with a first mounting groove, a second mounting groove and a third through hole; the second mounting groove is connected and arranged between the first mounting groove and the third through hole; the first mounting groove and the second mounting groove are provided on the outer surface of the insulating plate; The fiber grating sensor is fixed in the first installation groove; the middle part of the optical fiber passes through the third through hole, and the end of the optical fiber connected to the fiber grating sensor is embedded in the second installation groove.

8. The acoustic signal and radio frequency signal integrated sensor according to claim 7, characterized in that: A third sealing interface is installed in the third through hole, and the optical fiber passes through the third through hole through the third sealing interface.

9. A built-in sensor for partial discharge detection of power transformers, characterized in that: It includes a packaging unit and a detection unit; The packaging unit is a closed shell, one end surface of which is closed by an insulating plate; The detection unit includes a first sensor and a second sensor; The first sensor includes a radio frequency sensor and a radio frequency signal transmission line; the radio frequency sensor is fixed in the closed shell, one end of the radio frequency signal transmission line is connected to the radio frequency sensor, and the other end of the radio frequency signal transmission line passes through the side wall of the closed shell and extends to the outside of the closed shell; The second sensor comprises a fiber grating sensor and an optical fiber; the fiber grating sensor is embedded in the outer surface of the insulating plate, the receiving end of the fiber grating sensor faces outward, and the receiving end of the fiber grating sensor is flush with the outer surface of the insulating plate, one end of the optical fiber is connected to the fiber grating sensor, and the other end of the optical fiber passes through the insulating plate, the radio frequency sensor and the other end surface of the closed shell in sequence, or the other end of the optical fiber passes through the insulating plate and the other end surface of the closed shell in sequence, and the optical fiber is far away from the receiving end of the radio frequency sensor; When in use, the closed shell is fixed on the inner wall of the oil tank of the power transformer, and the outer surface of the insulating plate is in contact with the inner wall of the oil tank.

10. A detection device for partial discharge detection of power transformers, characterized in that: A sensor comprising an integrated acoustic signal and radio frequency signal according to any one of claims 1 to 8, and a signal processing unit; The other end of the radio frequency signal transmission line and the other end of the optical fiber are respectively connected to the input end of the signal processing unit.

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