Switch cabinet partial discharge ultrasonic signal measuring and processing circuit

Abstract

The utility model discloses a partial discharge ultrasonic signal measuring and processing circuit for a switch cabinet. The partial discharge ultrasonic signal measuring and processing circuit comprises an ultrasonic probe, a voltage amplifying circuit, a filter circuit, an analog-to-digital conversion circuit, a voltage reverse circuit and a 5V power supply circuit, the voltage reverse circuit reversely outputs the + 5V power supply voltage to the filter circuit and the analog-to-digital conversion circuit and provides-5V power supply for the operational amplifier; the filter circuit is designed to be a 36-44kHz band-pass filter; the analog-to-digital conversion circuit is used for converting the filtered ultrasonic signals into 8-bit digital acquisition data; the output end of the ultrasonic probe is connected with the input end of the voltage amplifying circuit; the output end of the voltage amplifying circuit is connected with the input end of the filter circuit; the output end of the filter circuit is connected with the input end of the analog-to-digital conversion circuit; the output end of the voltage reverse circuit is respectively connected with the-5V power supply ends of the filter circuit and the analog-to-digital conversion circuit; the output end of the 5V power supply circuit is connected with the filter circuit and the + 5V power end of the analog-to-digital conversion circuit. According to the utility model, the ultrasonic detection technology is adopted, low-frequency electromagnetic wave interference generated by high-voltage equipment is effectively avoided, and the accuracy of partial discharge detection is improved.

Description

Technical Field

[0001] This utility model relates to the field of power equipment monitoring technology, specifically a circuit for measuring and processing ultrasonic signals of partial discharge in switchgear. Background Technology

[0002] Partial discharge is a common electrical fault phenomenon during the operation of high-voltage switchgear. When partial discharge occurs, the dielectric around the discharge source undergoes charge neutralization, generating a current pulse. This causes the partial discharge area to heat up instantaneously, increasing its volume. After the discharge is complete, the volume returns to normal, and this process generates ultrasonic signals. Because ultrasonic signals have a high frequency, they can effectively avoid low-frequency electromagnetic interference generated by high-voltage equipment. Therefore, ultrasonic detection technology has become an effective means of monitoring partial discharge in switchgear. Utility Model Content

[0003] To address the shortcomings of existing technologies, this invention proposes a partial discharge ultrasonic signal measurement and processing circuit for switchgear, aiming to achieve precise digital processing of the acquired ultrasonic signals to improve the accuracy and reliability of partial discharge detection.

[0004] The technical solution of this utility model is as follows:

[0005] A partial discharge ultrasonic signal measurement and processing circuit for switchgear includes an ultrasonic probe, a voltage amplification circuit, a filtering circuit, an analog-to-digital conversion circuit, a voltage inversion circuit, and a 5V power supply circuit; wherein,

[0006] The voltage inverting circuit inverts the +5V supply voltage and outputs it to the filter circuit and analog-to-digital converter circuit, providing a -5V power supply to the operational amplifier.

[0007] The filtering circuit is designed as a bandpass filter of 36–44 kHz;

[0008] The analog-to-digital converter circuit converts the filtered ultrasonic signal into 8-bit digital acquisition data.

[0009] The output terminal of the ultrasonic probe is connected to the input terminal of the voltage amplifier circuit.

[0010] The output of the voltage amplifier circuit is connected to the input of the filter circuit.

[0011] The output of the filter circuit is connected to the input of the analog-to-digital converter circuit.

[0012] The output of the voltage inverting circuit is connected to the -5V power supply of the filter circuit and the analog-to-digital converter circuit, respectively.

[0013] The output of the 5V power supply circuit is connected to the +5V power supply terminals of the filter circuit and the analog-to-digital conversion circuit, respectively.

[0014] The ultrasonic probe is used to collect ultrasonic signals generated by partial discharge and amplify them through a voltage amplification circuit. The ultrasonic probe includes a housing, a coupling surface, a piezoelectric ceramic, a signal guide rod, and a BNC connector. The piezoelectric ceramic connects to the signal guide rod, which is inserted into the BNC connector. The BNC connector is located on the top of the housing, and the coupling surface is located on the bottom of the housing, with the piezoelectric ceramic in close contact with the coupling surface. The piezoelectric ceramic converts ultrasonic waves into corresponding electrical signals. To ensure the probe can correctly collect ultrasonic signals generated by partial discharge, the materials and dimensions are designed so that the resonant frequency of the piezoelectric ceramic is near the ultrasonic signal frequency. A ring-shaped piezoelectric ceramic with an internal diameter of 13mm, an external diameter of 26mm, and a thickness of 5mm is fabricated using zirconium titanate material. Silver paste is uniformly applied to the surface of the ceramic, and it is kept at 600℃ for half an hour. Then, the piezoelectric ceramic is polarized at room temperature for 15 minutes using silicone oil at 180℃ and a DC electric field of 120kV / cm. Finally, the piezoelectric ceramic is tested and found to have a resonant frequency of 38.7kHz, a dielectric loss of 0.3%, and a coupling coefficient of 60%, meeting the detection requirements.

[0015] The filtering circuit uses a specially designed bandpass filter to ensure that only signals within the 3644kHz range are allowed to pass through. The filtering circuit is designed as a 36-44kHz bandpass filter to filter out impurity signals and retain ultrasonic signals within the target frequency range.

[0016] The voltage amplification circuit uses the AD8065 chip to construct a differential amplifier circuit, amplifying the voltage signal to the +1V to +3V range. The voltage inversion circuit uses the MC34063A power supply chip to convert +5VDC to -5VDC, providing negative power to the operational amplifiers in the filtering circuit and analog-to-digital converter circuit, ensuring the authenticity and accuracy of signal processing. The 5V power supply circuit uses the LM2596-5.0 power supply chip to convert 12VDC to 5VDC, providing a stable +5V power supply for the entire circuit.

[0017] The analog-to-digital conversion circuit uses the AD9226 high-speed analog-to-digital converter. Through voltage division by series resistors and the -2V reference voltage provided by the TL072 chip, the voltage signal is adjusted to the input range of the AD9226. The analog-to-digital conversion circuit converts the filtered ultrasonic signal into 8-bit digital acquisition data, which is convenient for subsequent processing by the microprocessor.

[0018] The beneficial effects of this utility model are:

[0019] 1. The use of ultrasonic testing technology effectively avoids low-frequency electromagnetic interference generated by high-voltage equipment, improving the accuracy of partial discharge detection.

[0020] 2. Through specially designed filtering circuits and analog-to-digital conversion circuits, accurate acquisition and processing of ultrasonic signals are achieved, providing reliable data support for subsequent analysis.

[0021] 3. The ultrasonic probe uses high-performance piezoelectric ceramic material, which has excellent resonant frequency, dielectric loss and coupling coefficient, improving the sensitivity and accuracy of signal acquisition.

[0022] In summary, the ultrasonic signal measurement and processing circuit for partial discharge in switchgear of this invention has broad application prospects and significant practical value. Attached Figure Description

[0023] Figure 1 This is a system block diagram of this utility model;

[0024] Figure 2 This is a structural diagram of an ultrasonic probe;

[0025] Figure 3 This is a schematic diagram of a filter circuit, a voltage amplifier circuit, and a digital-to-analog converter circuit.

[0026] Figure 4 It is a voltage reversal circuit;

[0027] Figure 5 It is a 12VDC to 5VDC circuit. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0029] like Figure 1 As shown, a partial discharge ultrasonic signal measurement and processing circuit for a switchgear includes an ultrasonic probe, a voltage amplification circuit, a filtering circuit, an analog-to-digital conversion circuit, a voltage inversion circuit, and a 5V power supply circuit; wherein,

[0030] The voltage inverting circuit inverts the +5V supply voltage and outputs it to the filter circuit and analog-to-digital converter circuit, providing a -5V power supply to the operational amplifier.

[0031] The filtering circuit is designed as a bandpass filter of 36–44 kHz;

[0032] The analog-to-digital converter circuit converts the filtered ultrasonic signal into 8-bit digital acquisition data.

[0033] The output terminal of the ultrasonic probe is connected to the input terminal of the voltage amplifier circuit.

[0034] The output of the voltage amplifier circuit is connected to the input of the filter circuit.

[0035] The output of the filter circuit is connected to the input of the analog-to-digital converter circuit.

[0036] The output of the voltage inverting circuit is connected to the -5V power supply of the filter circuit and the analog-to-digital converter circuit, respectively.

[0037] The output of the 5V power supply circuit is connected to the +5V power supply terminals of the filter circuit and the analog-to-digital conversion circuit, respectively.

[0038] An ultrasonic probe is used to collect ultrasonic signals generated by partial discharge and amplify them through a voltage amplification circuit. For example... Figure 2 As shown, the ultrasonic probe includes a housing 1, a coupling surface 2, a piezoelectric ceramic 3, a signal guide rod 4, and a BNC connector 5. The piezoelectric ceramic 3 is connected to the signal guide rod 4, which is inserted into the BNC connector 5. The BNC connector 5 is located on the top of the housing 1, and the coupling surface 2 is located on the bottom of the housing 1. The piezoelectric ceramic 3 is in close contact with the coupling surface 2. The piezoelectric ceramic 3 can convert ultrasonic waves into corresponding electrical signals. To ensure that the probe can correctly acquire ultrasonic signals generated by partial discharge, the resonant frequency of the piezoelectric ceramic is designed to be near the ultrasonic signal frequency. A ring-shaped piezoelectric ceramic with an internal diameter of 13 mm, an external diameter of 26 mm, and a thickness of 5 mm is fabricated using zirconium titanate material. Silver paste is uniformly applied to the surface of the ceramic, and it is kept at 600℃ for half an hour. Then, the piezoelectric ceramic is polarized at room temperature for 15 minutes using silicone oil at 180℃ and a DC electric field of 120 kV / cm. Finally, the piezoelectric ceramic is tested and found to have a resonant frequency of 38.7 kHz, a dielectric loss of 0.3%, and a coupling coefficient of 60%, which meets the detection requirements.

[0039] like Figure 3 As shown, the filtering circuit uses a specially designed bandpass filter to ensure that only signals within the 3644kHz range are allowed to pass through. The filtering circuit is designed as a 36-44kHz bandpass filter to filter out impurity signals and retain ultrasonic signals within the target frequency range.

[0040] The voltage amplifier circuit uses the AD8065 chip to construct a differential amplifier circuit, amplifying the voltage signal to the range of +1V to +3V. For example... Figure 4 As shown, the voltage inversion circuit uses the MC34063A power supply chip to convert +5VDC to -5VDC, providing a negative power supply to the operational amplifiers in the filter circuit and analog-to-digital conversion circuit, ensuring the authenticity and accuracy of signal processing. Figure 5 As shown, the 5V power supply circuit uses the LM2596-5.0 power chip to convert 12VDC to 5VDC, which is used to provide a stable +5V power supply for the entire circuit.

[0041] The analog-to-digital conversion circuit uses the AD9226 high-speed analog-to-digital converter. Through voltage division by series resistors and the -2V reference voltage provided by the TL072 chip, the voltage signal is adjusted to the input range of the AD9226. The analog-to-digital conversion circuit converts the filtered ultrasonic signal into 8-bit digital acquisition data, which is convenient for subsequent processing by the microprocessor.

[0042] The above description is only a preferred embodiment of the present utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present utility model, and these improvements and modifications should also be considered within the protection scope of the present utility model.

Claims

1. A circuit for measuring and processing ultrasonic signals of partial discharge in a switchgear, characterized in that, It includes an ultrasonic probe, voltage amplification circuit, filter circuit, analog-to-digital conversion circuit, voltage inversion circuit, and 5V power supply circuit; among which, The voltage inverting circuit inverts the +5V supply voltage and outputs it to the filter circuit and analog-to-digital converter circuit, providing a -5V power supply to the operational amplifier. The filtering circuit is designed as a bandpass filter of 36–44 kHz; The analog-to-digital converter circuit converts the filtered ultrasonic signal into 8-bit digital acquisition data. The output terminal of the ultrasonic probe is connected to the input terminal of the voltage amplifier circuit. The output of the voltage amplifier circuit is connected to the input of the filter circuit. The output of the filter circuit is connected to the input of the analog-to-digital converter circuit. The output of the voltage inverting circuit is connected to the -5V power supply of the filter circuit and the analog-to-digital converter circuit, respectively. The output of the 5V power supply circuit is connected to the +5V power supply terminals of the filter circuit and the analog-to-digital conversion circuit, respectively.

2. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The ultrasonic probe includes a housing, a coupling surface, a piezoelectric ceramic, a signal guide rod, and a BNC connector. The piezoelectric ceramic is connected to the signal guide rod, which is inserted into the BNC connector. The BNC connector is located on the top of the housing, and the coupling surface is located on the bottom of the housing. The piezoelectric ceramic is in close contact with the coupling surface, and the ultrasonic probe can convert ultrasonic waves into corresponding electrical signals.

3. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The voltage amplifier circuit uses the AD8065 chip to form a differential amplifier circuit, which converts the voltage signal into +1V to +3V.

4. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The filtering circuit uses a filter with a bandpass frequency of 36–44 kHz.

5. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The analog-to-digital conversion circuit uses the AD9226 high-speed analog-to-digital converter, and adjusts the voltage signal to the input range of the AD9226 through voltage division by series resistors and a -2V reference voltage provided by the TL072 chip.

6. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The voltage reversing circuit uses the MC34063A power chip to convert +5VDC to -5VDC.

7. The ultrasonic signal measurement and processing circuit for partial discharge in a switchgear according to claim 1, characterized in that, The 5V power supply circuit uses the LM2596-5.0 power chip to convert 12VDC to 5VDC.

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