An internal pressure non-intrusive monitoring system and method for an oil-immersed mutual inductor arc process based on acoustic wave information

Abstract

The application relates to the field of high-voltage tests of power equipment, and discloses a non-invasive monitoring system and method for internal pressure of an oil-immersed mutual inductor during an arc process based on acoustic wave information, which comprises a pulse signal generator, an ultrasonic wave transmitting probe connected to a pulse signal output end of the pulse signal generator, an ultrasonic wave receiving probe arranged at a position opposite to the ultrasonic wave transmitting probe and used for receiving ultrasonic signals, a data acquisition card connected to the ultrasonic wave receiving probe, and a data processing unit connected to the data acquisition card, wherein the data processing unit can obtain pressure information in the oil-immersed mutual inductor according to data output by the data acquisition card. The application can detect the pressure change during the mutual inductor test process by using the non-invasive detection method, does not cause damage to the equipment structure, and guarantees the reliability of the test result; the ultrasonic wave sensing probe is arranged outside the mutual inductor and is not affected by the strong electromagnetic interference caused by the electric arc in the equipment during the test.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of high voltage test of power equipment, in particular to a non-invasive monitoring system and method for internal pressure of oil-immersed mutual inductor during arc process based on acoustic wave information. BACKGROUND

[0002] When a serious arc fault occurs in the oil-immersed mutual inductor, the transformer oil in the oil tank will rapidly crack under the action of high-temperature arc in a short time, generating a large amount of mixed gas such as hydrocarbon, hydrogen and carbon dioxide, so that the internal pressure of the oil tank rises sharply. Under the action of internal pressure, the tank body will have a certain degree of elastic or even plastic deformation, and when the local stress exceeds the strength limit of the tank body material, the tank body will rupture, causing a combustion and explosion accident and causing serious economic losses. Therefore, it is necessary to carry out internal arc test of oil-immersed power equipment and accurately detect the internal pressure change of the mutual inductor during the arc process, so as to effectively evaluate the reliability and safety of the oil-immersed mutual inductor under arc fault and ensure the safe and stable operation of the power equipment.

[0003] The conventional pressure testing instrument needs to punch holes on the mutual inductor shell to enable the pressure sensor to directly contact with the internal liquid to complete the pressure measurement. However, during the arc test of the mutual inductor, the punching holes on the shell will cause a weak structure, causing the shell to burst under the internal pressure. Therefore, it is necessary to research a non-invasive internal pressure detection technology for the oil-immersed mutual inductor to provide key technical support for the arc test evaluation of the oil-immersed mutual inductor. SUMMARY

[0004] To solve the problems in the prior art, the present application provides a non-invasive monitoring system and method for internal pressure of oil-immersed mutual inductor during arc process based on acoustic wave information, which does not need to punch holes on the mutual inductor shell to measure the internal pressure of the mutual inductor shell.

[0005] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A non-invasive monitoring system for internal pressure of oil-immersed mutual inductor during arc process based on acoustic wave information, comprising a pulse signal generator, the pulse signal output end of the pulse signal generator is connected with an ultrasonic wave transmitting probe, an ultrasonic wave receiving probe for receiving the ultrasonic signal emitted by the output end of the ultrasonic wave transmitting probe is arranged at a position opposite to the ultrasonic wave transmitting probe, the ultrasonic wave receiving probe is connected to a data acquisition card, the data card is connected to a data processing unit, and the data processing unit can obtain the pressure information in the oil-immersed mutual inductor according to the data output by the data acquisition card.

[0007] Preferably, the pulse signal output end of the pulse signal generator is also connected with an external trigger interface of the data acquisition card, for triggering the data acquisition card clock to zero.

[0008] Preferably, the data processing unit comprises a fiber data transmitting module, a fiber data receiving module and a calculation unit connected in sequence, the fiber data transmitting module is used for converting the electrical signal output by the data acquisition card into an optical signal, the fiber data receiving module is used for converting the optical signal output by the fiber data transmitting module into an electrical signal, and the calculation unit can obtain the pressure information in the oil-immersed mutual inductor according to the optical signal output by the fiber data receiving module.

[0009] The application also provides an oil-immersed mutual inductor arc burning process internal pressure non-intrusive monitoring method based on sound wave information, which is carried out by using the monitoring system as described above, and the detection method comprises the following steps:

[0010] The ultrasonic wave transmitting probe is arranged on the shell of the measured mutual inductor sample, and the ultrasonic wave receiving probe is arranged on the other side of the shell of the measured mutual inductor sample, and the ultrasonic wave receiving probe is opposite to the ultrasonic wave transmitting probe.

[0011] The ultrasonic wave transmitting probe is excited by the pulse signal generator to emit a pulse ultrasonic signal, the ultrasonic wave receiving probe receives the pulse ultrasonic signal emitted by the ultrasonic wave transmitting probe, the data acquisition card collects the waveform of the pulse ultrasonic signal received by the ultrasonic wave receiving probe, and the data processing unit obtains the pressure information in the oil-immersed mutual inductor according to the waveform of the pulse ultrasonic signal collected by the data acquisition card.

[0012] Preferably, the repetition period T of the periodic pulse emitted by the pulse signal generator satisfies the following relationship:

[0013]

[0014] In the formula, L is the diameter of the measured mutual inductor sample, c C0 is the sound velocity of the transformer oil of the measured mutual inductor sample under normal temperature and pressure.

[0015] Preferably, the pulse width of the periodic pulse emitted by the pulse signal generator satisfies the following relationship:

[0016]

[0017] In the formula, L is the diameter of the measured mutual inductor sample, c C0 is the sound velocity of the transformer oil of the measured mutual inductor sample under normal temperature and pressure.

[0018] Preferably, the pressure in the measured mutual inductor sample P and the sound velocity c satisfy the following relationship:

[0019] c = f ( P )

[0020] In the formula, P The internal pressure of the current transformer sample under test. c Let be the speed of sound under that pressure.

[0021] Preferably, the pressure in the tested transformer sample P With the speed of sound c The calibration methods include:

[0022] Transformer oil is filled into a cylindrical pressure vessel, and ultrasonic transmitting and receiving probes are placed on both sides of the pressure vessel. By applying different pressures to the pressure vessel, the sound velocity in the transformer oil under the corresponding pressure conditions is measured, the variation law of the sound velocity is analyzed, and a calibration curve between sound velocity and pressure is established. The pressure information in the oil-immersed instrument transformer can be obtained through the calibration curve between sound velocity and pressure.

[0023] Preferably, the data acquisition card adopts a communication serial bus format.

[0024] Preferably, the analog bandwidth of the data acquisition card is not less than 150 MHz.

[0025] The present invention has the following beneficial effects:

[0026] This invention relates to a non-invasive monitoring system for the internal pressure of an oil-immersed instrument transformer during arcing, based on acoustic wave information. A pulse signal generator enables an ultrasonic transmitting probe to emit pulsed ultrasonic signals, and an ultrasonic receiving probe receives these signals. In use, the ultrasonic transmitting probe is placed on the housing of the instrument transformer sample under test, and the ultrasonic receiving probe is placed on the opposite side of the sample housing, directly opposite the transmitting probe. This invention utilizes the signal changes as the pulsed ultrasonic signal passes through the instrument transformer sample to obtain pressure information within the sample, thus providing crucial technical support for the evaluation of arcing tests on oil-immersed instrument transformers. This invention enables the detection of pressure changes during instrument transformer testing using a non-invasive method, without damaging the equipment structure and ensuring the reliability of the test results. The ultrasonic sensing probes (i.e., the transmitting and receiving probes) are located outside the instrument transformer, unaffected by the strong electromagnetic interference from the arcing generated inside the equipment during testing, thereby improving the accuracy and stability of pressure change sensing. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the overall system layout of the non-intrusive monitoring system for the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, according to the present invention.

[0028] Figure 2 Fig. 1 is a curve chart of ultrasonic pulse emission, receiving waveform and pressure change in the embodiment of the present application.

[0029] In the figure, 1-pulse signal generator, 2-transmitting probe tail cable, 3-ultrasonic wave transmitting probe, 4-measured transformer sample, 5-ultrasonic wave receiving probe, 6-receiving probe tail cable, 7-data acquisition card, 8-signal transmission coaxial cable, 9-output USB line, 10-optical fiber data transmitting module, 11-signal transmission optical fiber, 12-optical fiber data receiving module, 13-optical fiber receiver output USB line, 14-upper computer display system. DETAILED DESCRIPTION

[0030] The present application will be described in detail below in connection with the drawings and embodiments of the present application. The described embodiments are only a part of the embodiments of the present application, and are not all the embodiments.

[0031] The oil-immersed transformer arc process internal pressure non-intrusive monitoring system and method based on sound wave information provided by the present application can monitor the internal pressure change of the transformer during the arc process in real time and reliably, and reliably transmit the signal to the control room for real-time reading and display, so as to solve the technical problem that the internal pressure change of the equipment cannot be effectively measured in the current transformer arc test, and thus it is difficult to complete the evaluation of the arc resistance reliability of the transformer, and also avoid the problem that the conventional pressure testing instrument needs to punch holes on the transformer shell to make the pressure sensor directly contact with the internal liquid to complete the pressure measurement.

[0032] The exemplary embodiments of the present application are implemented by the following technical solutions:

[0033] Reference Figure 1In the oil-immersed mutual inductor arc process internal pressure non-intrusive monitoring system based on acoustic wave information, the ultrasonic emission probe 3 is connected with the pulse signal generator 1 through the emission probe cable tail cable 2, the ultrasonic emission probe 3 is tightly attached to the shell of the measured mutual inductor sample 4, the ultrasonic receiving probe 5 is tightly attached to the other side of the measured mutual inductor sample 4 and is opposite to the ultrasonic emission probe 3. The ultrasonic receiving probe 5 receives the ultrasonic signal after passing through the measured mutual inductor sample 4 and is connected to the data acquisition card 7 through the receiving probe tail cable 6, and the data acquisition card 7 collects the ultrasonic signal received by the ultrasonic receiving probe 5. The external trigger signal of the data acquisition card 7 is connected to the pulse signal generator 1 through the signal transmission coaxial cable 8. The output USB line 9 of the data acquisition card 7 is connected to the optical fiber data emission module 10, the optical fiber data emission module 10 converts the electrical signal collected by the data acquisition card 7 into an optical signal and transmits it through the signal transmission optical fiber 11, and finally the optical fiber data receiving module 12 receives and converts it into an electrical signal, and the electrical signal converted by the optical fiber data receiving module 12 is connected to the upper computer display system 14 through the optical fiber receiver output USB line 13.

[0034] During the test, the ultrasonic emission probe 3 and the ultrasonic receiving probe 5 are arranged on the opposite sides of the oil-immersed mutual inductor shell, and the sound wave emitted by the ultrasonic emission probe 3 passes through the oil-immersed mutual inductor and is received by the ultrasonic receiving probe 5.

[0035] The ultrasonic emission probe 3 is excited by the pulse signal generator 1 to emit periodic and high-frequency pulse sound waves. In order to realize high-performance pressure detection, the repetition period T of the periodic pulse emitted by the pulse signal generator 1 satisfies the following conditions:

[0036]

[0037] In the formula, L is the diameter of the mutual inductor to be measured, c 0 is the sound velocity of the transformer oil at normal temperature and pressure;

[0038] The pulse width of the periodic pulse emitted by the pulse signal generator 1 T p satisfies the following conditions:

[0039]

[0040] The output of the pulse signal generator 1 is divided into two paths, one signal is input to the ultrasonic emission probe 3 through the emission probe tail cable 2 to excite periodic pulse ultrasonic waves, and the other signal is input to the external trigger interface of the data acquisition card 7 through the signal transmission cable 8 to trigger the clock of the data acquisition card 7 to zero.

[0041] The data acquisition card 7 collects the pulse ultrasonic wave received by the ultrasonic receiving probe 5 and transmits it to the upper computer through the optical fiber transmission device for analysis.

[0042] The pressure monitoring principle of the above monitoring system is that the propagation speed of sound waves in a medium is related to the density of the substance. When the internal pressure of the transformer increases, the density of the transformer oil therein will change, and the propagation speed of sound waves therein will also change accordingly, in a monotonic function relationship:

[0043] c f P

[0044] P is the internal pressure of the transformer, c is the sound speed under the pressure, and the function relationship is obtained through calibration. By analyzing the sound speed of the sound waves transmitted in the transformer, the pressure can be analyzed.

[0045] The transmission speed of sound waves in the transformer oil in the transformer can be obtained by analyzing the time at which the ultrasonic receiving probe 5 receives each ultrasonic pulse, and the specific implementation method is as follows: the ultrasonic transmitting probe 3 and the ultrasonic receiving probe 5 are respectively tightly attached to the two sides of the transformer shell and are in the same radial direction, and the distance between the two ultrasonic transmitting probes 3 and the ultrasonic receiving probe 5 is the diameter of the transformer. The transmitting probe transmits a column of ultrasonic pulse signals with a repetition period of T and a pulse width of T p The receiving probe receives the column of pulse ultrasonic waves in turn to obtain the transmission time of each pulse in the column, which is represented as

[0046]

[0047] According to the formula of the relationship between the transmission speed of sound waves and the distance:

[0048]

[0049] The corresponding sound speed can be obtained:

[0050]

[0051] According to c f P the corresponding pressure value is obtained:

[0052]

[0053] In the formula, R is the transmission time data set of each ultrasonic pulse in the transformer, t n represents the transmission time of the nth pulse in the column of pulses, L is the transmission distance of the sound waves, t is the transmission time of the sound waves,​​​​​C a transmission speed data set of each acoustic wave pulse in the transformer, c n represents the transmission speed of the n-th pulse in the column of pulses, P a pressure data set in the transformer corresponding to the transmission time of each pulse is calculated, P n represents the pressure value in the transformer when the n-th pulse in the column of pulses is transmitted in the transformer.

[0054] The c = f ( P ) calibration method is as follows: filling the cylindrical pressure vessel with transformer oil, and placing the ultrasonic wave transmitting probe 3 and the ultrasonic wave receiving probe 5 on both sides of the pressure vessel, measuring the acoustic speed in the transformer oil under different pressure conditions by applying different pressures to the pressure vessel, analyzing the change rule of the test acoustic speed, and establishing the calibration curve between the acoustic speed and the pressure.

[0055] Considering that the high-voltage test hall and the control room are generally far away, the signal transmission should adopt digital quantity transmission, and high-low voltage insulation isolation should be completed to ensure the insulation safety in the control room. The application proposes to use an optical fiber data transmission system to complete the signal transmission of the output signal of the ultrasonic wave receiving probe to the host computer in the control room, and the control of the collection system in the test hall. The specific implementation is as follows: when the sensing signal is transmitted, the output voltage signal of the ultrasonic wave receiving probe 5 is collected and converted into a digital signal by the data acquisition card 7, the data acquisition card 7 adopts a communication serial bus format, and the data is transmitted to the optical fiber data transmission module 10 through USB. The optical fiber data transmission module 10 converts the digital signal into an optical digital signal, and transmits it to the optical data receiving module 12 in the control room along the signal transmission optical fiber. Preferably, the analog bandwidth of the data acquisition card 7 used in the application is not less than 150 MHz, so as to ensure the wideband collection of the vibration signal, the communication bandwidth of the two optical fiber communication modules is not less than 500 MHz, and the transmission optical fiber length is greater than 1 km. The optical fiber receiver end transmits the received signal to the host computer for display, data processing and analysis. The optical fiber receiver end can also send control signals to the sensing system on the host computer to control the start and stop of the system collection.

[0056] The embodiment detects the internal pressure signal of the arc process of a 220 kV oil-immersed current transformer. The ultrasonic emission probe 3 is connected with the pulse signal generator 1 through the emission probe tail cable 2, the ultrasonic emission probe 3 is tightly attached to the shell of the measured transformer sample 4, and the ultrasonic receiving probe 5 is tightly attached to the other side of the measured transformer 4 and is opposite to the ultrasonic emission probe 3. The ultrasonic receiving probe 5 receives the ultrasonic signal and is connected to the data acquisition card 7 through the receiving probe tail cable 6 for collection. The external trigger signal of the data acquisition card 7 is connected to the pulse signal generator 1 through the signal transmission coaxial cable 7. The USB line 9 output by the data acquisition card 7 is connected to the optical fiber data transmission module 10, the optical fiber data transmission module 10 converts the electrical signal of the data acquisition card into an optical signal, and transmits the signal through the transmission optical fiber 11. The optical fiber data receiving module 12 receives the signal, converts it into an electrical signal, and outputs the USB line 13 to the host computer display system 14.

[0057] The repetition period of the pulse signal generated by the pulse signal generator 1 in the embodiment is , and the pulse signal width is . In the embodiment, the diameter of the transformer is 500 mm, so the repetition of the pulse signal is 0.4 ms, and the pulse signal width is 0.004 ms.

[0058] The pulse waveform of the pulse signal generator 1 and the ultrasonic receiving probe 5 and the pressure change curve are displayed in the host computer display system 14 as shown in Figure 2 . Since the excitation source of the ultrasonic emission probe 3 is the pulse signal generator 1, the output signal frequencies of the two are the same, so the waveform of the pulse signal generator 1 can be regarded as the ultrasonic input waveform. When there is no arc in the transformer, the internal pressure does not change, and at this time the time interval between the ultrasonic input pulse and the output pulse remains constant; after the arc is generated in the transformer, the mixed gas is generated due to the cracking of the transformer oil, which causes the change of the pressure in the transformer, and the change of the sound speed in the transformer, the time interval between the ultrasonic input pulse and the output pulse changes, and according to the functional relationship between the sound speed and the pressure, the pressure change curve can be drawn.

[0059] In the above scheme of the application, the optical fiber communication system is used for transmission of sensing signals and sending of control signals, which not only completes high and low voltage insulation isolation, but also realizes bidirectional communication of information. The operator in the control room can realize control of the acquisition system and real-time reading of the vibration data of the field test, without the need for on-site operation, thereby avoiding the danger to the operator and improving the anti-interference ability, the control precision and the reliability of the internal arc process record.

[0060] Finally, it should be noted that the above preferred embodiments are merely illustrative of the technical solutions of the present application and are not limited thereto. For those skilled in the art, various changes in form, details, modifications, substitutions or optimizations can be made without departing from the scope of the technical solutions defined by the claims.

Claims

1. A non-invasive method for monitoring the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, characterized in that, The monitoring method employs a non-invasive monitoring system for the internal pressure of an oil-immersed transformer during the arcing process based on acoustic information. This system includes a pulse signal generator (1), the pulse signal output terminal of which is connected to an ultrasonic transmitting probe (3). Opposite to the ultrasonic transmitting probe (3) is an ultrasonic receiving probe (5) for receiving the ultrasonic signal emitted by the output terminal of the ultrasonic transmitting probe (3). The ultrasonic receiving probe (5) is connected to a data acquisition card (7), which is connected to a data processing unit. The data processing unit can obtain the pressure information in the oil-immersed transformer based on the data output by the data acquisition card (7). The monitoring method includes: The ultrasonic transmitting probe (3) is placed on the housing of the current transformer sample (4) under test, and the ultrasonic receiving probe (5) is placed on the other side of the housing of the current transformer sample (4) under test, with the ultrasonic receiving probe (5) facing the ultrasonic transmitting probe (3). The ultrasonic transmitter (3) is excited by the pulse signal generator (1) to emit a pulse ultrasonic signal, the ultrasonic receiver (5) receives the pulse ultrasonic signal emitted by the ultrasonic transmitter (3), the data acquisition card (7) acquires the waveform of the pulse ultrasonic signal received by the ultrasonic receiver (5), and the data processing unit obtains the pressure information in the oil-immersed transformer based on the waveform of the pulse ultrasonic signal acquired by the data acquisition card (7). The repetition period T of the periodic pulses emitted by the pulse signal generator (1) satisfies the following relationship: The pulse width of the periodic pulses emitted by the pulse signal generator (1) satisfies the following relationship: In the formula, L is the diameter of the outer shell of the current transformer sample (4) under test. c 0 is the sound velocity of the transformer oil in the tested instrument transformer sample (4) at normal temperature and pressure.

2. The non-invasive monitoring method for the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, as described in claim 1, is characterized in that... The pulse signal output terminal of the pulse signal generator (1) is also connected to the external trigger interface of the data acquisition card (7) to trigger the clock of the data acquisition card (7) to be zero.

3. The non-invasive monitoring method for the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, as described in claim 1, is characterized in that... The data processing unit includes an optical fiber data transmitting module (8), an optical fiber data receiving module (12), and a computing unit connected in sequence. The optical fiber data transmitting module (8) is used to convert the electrical signal output by the data acquisition card (7) into an optical signal. The optical fiber data receiving module (12) is used to convert the optical signal output by the optical fiber data transmitting module (8) into an electrical signal. The computing unit can obtain the pressure information in the oil-immersed transformer based on the optical signal output by the optical fiber data receiving module (12).

4. The non-invasive monitoring method for the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, as described in claim 1, is characterized in that... Pressure in the tested instrument transformer sample (4) P With the speed of sound c The following relationship must be satisfied: c = f ( P ) In the formula, P The internal pressure of the tested current transformer sample (4) is... c Let be the speed of sound under that pressure.

5. The non-invasive monitoring method for internal pressure of an oil-immersed instrument transformer during arcing process based on acoustic wave information according to claim 1, characterized in that, Pressure in the tested instrument transformer sample (4) P With the speed of sound c The calibration methods include: Transformer oil is filled into a cylindrical pressure vessel, and ultrasonic transmitting and receiving probes are placed on both sides of the pressure vessel. By applying different pressures to the pressure vessel, the sound velocity in the transformer oil under the corresponding pressure conditions is measured, the variation law of the sound velocity is analyzed, and a calibration curve between sound velocity and pressure is established. The pressure information in the oil-immersed instrument transformer can be obtained through the calibration curve between sound velocity and pressure.

6. The non-invasive monitoring method for internal pressure during the arcing process of an oil-immersed instrument transformer based on acoustic wave information according to claim 1, characterized in that, The data acquisition card (7) adopts a communication serial bus format.

7. The non-invasive monitoring method for the internal pressure of an oil-immersed instrument transformer during the arcing process based on acoustic wave information, as described in claim 1, is characterized in that... The analog bandwidth of the data acquisition card (7) is not less than 150 MHz.

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