Programmable ultrasonic partial discharge signal conditioning circuit and ultrasonic partial discharge sensor

Abstract

The invention relates to the technical field of signal processing and sensing, and provides a programmable ultrasonic partial discharge signal conditioning circuit and an ultrasonic partial discharge sensor. The programmable ultrasonic partial discharge signal conditioning circuit comprises an input signal protection circuit, a programmable filter circuit and a programmable gain amplification circuit which are sequentially connected in series. The input signal protection circuit is used for limiting an input ultrasonic partial discharge signal within a preset voltage range; the programmable filter circuit comprises a low-pass filter circuit, a high-pass filter circuit and a multi-path change-over switch, and the multi-path change-over switch is used for conducting path switching under program control so as to change the cut-off frequency of the low-pass filter circuit and the cut-off frequency of the high-pass filter circuit; the programmable gain amplification circuit comprises a programmable gain amplifier which is used for outputting different gains under program control. According to the invention, the bandwidth of the filter circuit can be modulated and the gain amplitude of the output signal can be adjusted while overvoltage protection of the input signal is realized.

Description

Technical Field

[0001] The invention relates to the field of signal processing and sensing technology, and in particular to a programmable ultrasonic partial discharge signal conditioning circuit and an ultrasonic partial discharge sensor. Background Art

[0002] The main fault of primary power equipment is partial discharge caused by insulation defects. Monitoring partial discharge signals is the most direct and fastest means to determine whether there are insulation defects in primary power equipment. Ultrasonic principle is usually used to monitor partial discharge faults in primary power equipment, and relevant standards also stipulate the effective ultrasonic monitoring bandwidth for different equipment. For example, contact ultrasonic sensors are used to monitor partial discharge signals for SF6 switchgear, and the sensor signal bandwidth is 20kHz to 80kHz; air ultrasonic sensors are used to monitor partial discharge signals for air switchgear, and the sensor signal bandwidth is 20kHz to 60kHz; contact ultrasonic sensors are used to monitor partial discharge signals for oil-filled equipment such as transformers, and the sensor signal bandwidth is 80kHz to 200kHz.

[0003] Traditional partial discharge monitoring equipment uses processing circuits with fixed parameters. A specific bandwidth corresponds to a specific circuit. Different signal processing circuits need to be designed for different signal bandwidths. One signal processing circuit cannot be compatible with different signal bandwidths. Traditional partial discharge monitoring equipment has the following defects:

[0004] 1) Increased product variety and management costs;

[0005] 2) For scenarios where multi-channel ultrasonic partial discharge is collected simultaneously, the bandwidth of each channel needs to be determined in advance before configuration and production can be performed. Changes are not supported on site.

[0006] 3) Since the circuit may be changed at any time according to the on-site configuration requirements and there is no version that has been fully verified for mass application, the reliability of the circuit is questionable. Summary of the invention

[0007] In order to solve the above technical problems, the present invention provides a programmable ultrasonic partial discharge signal conditioning circuit and an ultrasonic partial discharge sensor.

[0008] The present invention provides a programmable ultrasonic partial discharge signal conditioning circuit, comprising: an input signal protection circuit, a programmable filtering circuit and a programmable gain amplifier circuit which are sequentially connected in series;

[0009] The input signal protection circuit is used to limit the input ultrasonic partial discharge signal to a preset voltage range;

[0010] The programmable filter circuit is used to filter the ultrasonic partial discharge signal output by the input signal protection circuit, and output the filtered ultrasonic partial discharge signal; the programmable filter circuit includes: a low-pass filter circuit, a high-pass filter circuit, and a multi-way switch connected to the low-pass filter circuit and the high-pass filter circuit, and the multi-way switch is used to switch the paths under program control to change the cutoff frequencies of the low-pass filter circuit and the high-pass filter circuit;

[0011] The programmable gain amplifier circuit is used to amplify the filtered ultrasonic partial discharge signal output by the programmable filter circuit and output the amplified ultrasonic partial discharge signal; the programmable gain amplifier circuit includes a programmable gain amplifier, and the programmable gain amplifier is used to output different gains under program control.

[0012] In an embodiment of the present invention, the input signal protection circuit includes: a bidirectional breakdown diode, one end of which inputs an ultrasonic partial discharge signal and is connected to a low-pass filter circuit of a programmable filter circuit, and the other end of the bidirectional breakdown diode is connected to a signal ground.

[0013] In an embodiment of the present invention, the low-pass filter circuit includes: a first group of resistors and a first operational amplifier;

[0014] The output end of the input signal protection circuit is respectively connected to multiple selection ports on one side of the multi-way switch through multiple resistors in the first group of resistors, and the control port on one side of the multi-way switch is connected to the positive input end of the first operational amplifier;

[0015] The negative input terminal and the output terminal of the first operational amplifier are connected in parallel and then connected to the control port on the other side of the multi-way switch.

[0016] In the embodiment of the present invention, the low-pass filter circuit further includes: a first capacitor, and a control port on one side of the multi-way switch is connected to a signal ground through the first capacitor.

[0017] In an embodiment of the present invention, the high-pass filter circuit includes: a second group of resistors and a second operational amplifier;

[0018] The positive input terminal of the second operational amplifier is respectively connected to the multiple selection ports on the other side of the multi-way switch through multiple resistors in the second group of resistors;

[0019] The negative input terminal and the output terminal of the second operational amplifier are connected in parallel and then connected to the input terminal of the programmable gain amplifier.

[0020] In an embodiment of the present invention, the high-pass filter circuit includes: a second capacitor;

[0021] The negative input terminal and the output terminal of the first operational amplifier are connected in parallel and then connected to the control port on the other side of the multi-way switch through the second capacitor.

[0022] In an embodiment of the present invention, the programmable gain amplifier circuit further includes: a first clamping diode, wherein an anode of the first clamping diode is connected to a signal ground, and a cathode of the first clamping diode is connected to an output end of the programmable gain amplifier.

[0023] In an embodiment of the present invention, the programmable gain amplifier circuit further includes: a second clamping diode, wherein an anode of the second clamping diode is connected to an output end of the programmable gain amplifier, and a cathode of the second clamping diode is connected to a power supply end.

[0024] In an embodiment of the present invention, the first group of resistors of the low-pass filter circuit includes: a first resistor, a second resistor and a third resistor;

[0025] The output end of the input signal protection circuit is connected to three selection ports on one side of the multi-way switch through a first resistor, a second resistor and a third resistor respectively;

[0026] The second group of resistors of the high-pass filter circuit includes: a fourth resistor, a fifth resistor and a sixth resistor;

[0027] The positive input terminal of the second operational amplifier is connected to the three selection ports on the other side of the multi-way switch through a fourth resistor, a fifth resistor and a sixth resistor respectively.

[0028] In the embodiment of the present invention, the programmable gain amplifier circuit further includes: a seventh resistor and an eighth resistor;

[0029] The negative input terminal and the output terminal of the second operational amplifier are connected in parallel and then connected to the input terminal of the programmable gain amplifier through the seventh resistor;

[0030] An anode of the second clamping diode is connected to an output end of the programmable gain amplifier through the eighth resistor.

[0031] The present invention also provides an ultrasonic partial discharge sensor, which comprises: a microprocessor and the above-mentioned programmable ultrasonic partial discharge signal conditioning circuit;

[0032] The microprocessor is used to control the multi-way switch of the programmable ultrasonic partial discharge signal conditioning circuit to switch the paths so as to adjust the bandwidth and gain of the programmable ultrasonic partial discharge signal conditioning circuit.

[0033] In the embodiment of the present invention, the microprocessor controls the pin level of the multi-way switch to implement path switching of the multi-way switch;

[0034] The microprocessor controls the pin level of the programmable gain amplifier to control the amplifier to output different gains.

[0035] The programmable ultrasonic partial discharge signal conditioning circuit of the present invention realizes input signal overvoltage protection while realizing filter circuit bandwidth modulation and output signal gain amplitude adjustment. The working bandwidth and gain of the ultrasonic partial discharge signal conditioning circuit can be flexibly configured through program control to meet the optimal signal-to-noise ratio requirements of signal measurement and partial discharge monitoring requirements for different primary devices and different sensors. At the same time, a circuit can be applied to different scenarios, and the reliability of the circuit is also improved through mass application verification.

[0036] Other features and advantages of the technical solution of the present invention will be described in detail in the specific implementation section below. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0038] Figure 1 It is a schematic diagram of the structure of a programmable ultrasonic partial discharge signal conditioning circuit provided in an embodiment of the present invention;

[0039] Figure 2 is a circuit diagram of an input signal protection circuit provided by an embodiment of the present invention;

[0040] Figure 3 1 is a schematic diagram of the circuit principle of a programmable filter circuit provided by an embodiment of the present invention;

[0041] Figure 4 is a schematic diagram of a multi-way switch of a programmable filter circuit provided by an embodiment of the present invention;

[0042] Figure 5 It is a schematic diagram of the circuit principle of a high-pass filter circuit and a programmable gain amplifier circuit provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0043] In order to make the technical solutions and advantages of the embodiments of the present invention more clearly understood, the exemplary embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

[0044] In the description of the present invention, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0045] In the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", "connected" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0046] Terminology explanation:

[0047] Partial discharge: refers to the discharge that occurs between electrodes but does not penetrate the electrodes. It is caused by the existence of weak electricity inside the insulation of the equipment or defects caused during the production process, and it causes repeated breakdown and extinction under the action of high electric field strength.

[0048] Ultrasonic partial discharge sensor: The sensor is connected to the outside of the electrical equipment, and the ultrasonic signal generated by the partial discharge is converted into an electrical signal. The signal is subsequently processed to obtain the characteristic quantity that characterizes the partial discharge.

[0049] As described in the background technology, traditional partial discharge monitoring equipment uses processing circuits with fixed parameters. A specific bandwidth corresponds to a specific circuit. Different signal processing circuits need to be designed for different signal bandwidths. One signal processing circuit cannot be compatible with different signal bandwidths.

[0050] In view of the above problems, the embodiments of the present invention provide a programmable ultrasonic partial discharge signal conditioning circuit. Figure 1 As shown, the programmable ultrasonic partial discharge signal conditioning circuit includes: an input signal protection circuit, a programmable filter circuit and a programmable gain amplifier circuit, which are connected in series in sequence. The input signal protection circuit, the programmable filter circuit and the programmable gain amplifier circuit are in a signal chain, and the input and output of each circuit module are connected end to end, together forming an input signal conditioning circuit for ultrasonic partial discharge signals.

[0051] The input signal protection circuit is used to limit the input ultrasonic partial discharge signal within a preset voltage range to achieve input signal overvoltage protection. The programmable filter circuit is used to filter the ultrasonic partial discharge signal output by the input signal protection circuit and output the filtered ultrasonic partial discharge signal. The programmable filter circuit includes a low-pass filter circuit, a high-pass filter circuit, and a multi-way switch connected to the low-pass filter circuit and the high-pass filter circuit. The multi-way switch switches the paths under program control to change the cutoff frequencies of the low-pass filter circuit and the high-pass filter circuit to achieve modulatable bandwidth of the filter circuit. The programmable gain amplifier circuit is used to amplify the filtered ultrasonic partial discharge signal output by the programmable filter circuit and output the amplified ultrasonic partial discharge signal. The programmable gain amplifier circuit includes a programmable gain amplifier, and the output gain of the programmable gain amplifier is changed under program control to achieve adjustable output signal gain amplitude. The programmable ultrasonic partial discharge signal conditioning circuit provided in the embodiment of the present invention realizes modulatable bandwidth of the filter circuit and adjustable output signal gain amplitude while realizing input signal overvoltage protection.

[0052] In a specific embodiment, Figure 2 As shown, the input signal protection circuit includes a bidirectional breakdown diode (transient voltage suppression diode) D1, one end of the bidirectional breakdown diode D1 inputs the ultrasonic partial discharge signal AE_In and is connected to the low-pass filter circuit (first resistor R1, second resistor R2, third resistor R3) of the programmable filter circuit, and the other end of the bidirectional breakdown diode D1 is connected to the signal ground AGND. The ultrasonic external input signal AE_In is connected to the left side of the parallel circuit of the first resistor R1, the second resistor R2, and the third resistor R3 of the low-pass filter circuit through the bidirectional breakdown diode D1 to ensure that the input voltage does not exceed ±15V.

[0053] In one embodiment, the programmable filter circuit includes: a low-pass filter circuit, a high-pass filter circuit, and a multi-way switch connected to the low-pass filter circuit and the high-pass filter circuit, and the multi-way switch switches the paths under program control to change the cutoff frequencies of the low-pass filter circuit and the high-pass filter circuit. Specifically, the low-pass filter circuit includes: a first group of resistors and a first operational amplifier, the output end of the input signal protection circuit is respectively connected to multiple selection ports on one side of the multi-way switch through multiple resistors in the first group of resistors, the control port on one side of the multi-way switch is connected to the positive input end of the first operational amplifier, and the negative input end and the output end of the first operational amplifier are connected in parallel to the control port on the other side of the multi-way switch. The high-pass filter circuit includes: a second group of resistors and a second operational amplifier, the positive input end of the second operational amplifier is respectively connected to multiple selection ports on the other side of the multi-way switch through multiple resistors in the second group of resistors, and the negative input end and the output end of the second operational amplifier are connected in parallel to the input end of the programmable gain amplifier.

[0054] Figure 3 It is a schematic diagram of the circuit principle of the programmable filter circuit. Figure 3 Mainly shows a part of the low-pass filter circuit and a part of the high-pass filter circuit, and does not show the multi-way switch. Figure 2 Another part of the low-pass filter circuit is shown. Figure 4 The structure of a multi-way switch is shown. Figure 2 , Figure 3 and Figure 4 As shown, the low-pass filter circuit includes: a first resistor R1, a second resistor R2, a third resistor R3, a first capacitor C1 and a first operational amplifier U1. The output end of the input signal protection circuit (i.e., one end of the bidirectional breakdown diode D1) is connected to the three selection ports SEL Y1 (pin 1 of U3), SEL Y2 (pin 5 of U3), and SEL Y3 (pin 2 of U3) on the Y side of the multi-way switch U3 through the first resistor R1, the second resistor R2, and the third resistor R3, respectively. The control port YCOM (pin 3 of U3) on the Y side of the multi-way switch U3 is connected to the positive input end of the first operational amplifier U1, and the negative input end and the output end of the first operational amplifier U1 are connected to the control port XCOM (pin 13 of U3) on the X side of the multi-way switch U3. The control port YCOM (pin 3 of U3) on the Y side of the multi-way switch U3 is connected to the signal ground AGND through the first capacitor C1.

[0055] Figure 5 Another part of the high-pass filter circuit and the overall programmable gain amplifier circuit are shown. Figure 4 and Figure 5 As shown, the high-pass filter circuit includes: a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a second capacitor C2, and a second operational amplifier U2. The positive input terminal of the second operational amplifier U2 is connected to the three selection ports SELX1 (pin 12 of U3), SELX2 (pin 14 of U3), and SELX3 (pin 15 of U3) on the X side of the multi-way switch U3 through the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6. The negative input terminal and the output terminal of the second operational amplifier U2 are connected to the input terminal IN (pin 3 of U4) of the programmable gain amplifier U4. The negative input terminal and the output terminal of the first operational amplifier U1 are connected in parallel and then connected to the control port XCOM (pin 13 of U3) on the X side of the multi-way switch U3 through the second capacitor C2.

[0056] like Figure 5As shown, the programmable gain amplifier circuit includes: a programmable gain amplifier U4, a first clamping diode D2, and a second clamping diode D3. The anode of the first clamping diode D2 is connected to the signal ground, and the cathode of the first clamping diode D2 is connected to the output terminal OUT (pin 1 of U4) of the programmable gain amplifier U4. The anode of the second clamping diode D3 is connected to the output terminal OUT (pin 1 of U4) of the programmable gain amplifier U4, and the cathode of the second clamping diode D3 is connected to the power supply terminal VDD3.3V.

[0057] The programmable gain amplifier circuit also includes: a seventh resistor R7 and an eighth resistor R8. The negative input terminal and the output terminal of the second operational amplifier U2 are connected in parallel and then connected to the input terminal IN (pin 3 of U4) of the programmable gain amplifier U4 through the seventh resistor R7. The anode of the second clamping diode D3 is connected to the output terminal OUT (pin 1 of U4) of the programmable gain amplifier U4 through the eighth resistor R8.

[0058] In the embodiment of the present invention, the multi-way switch U3 is a 4-channel double-throw analog switch, and the A and B pin levels of the multi-way switch U3 are controlled by the microprocessor MCU to realize the control of the multi-way switch U3. The low-pass filter circuit and the high-pass filter circuit are respectively connected to different resistors to form different filter bandwidths of 20KHz to 60KHz, 20KHz to 80KHz, and 80KHz to 200KHz. The G0, G1, and G2 pin levels of the programmable gain amplifier U4 are controlled by the microprocessor MCU to control the amplifier to output different gains, which can be adaptively adjusted by sampling the voltage amplitude. The amplified voltage is clamped by a diode to ensure that the voltage does not exceed the limit and the MCU pin is not damaged.

[0059] Specifically, the MCU controls the level of the 10 and 9 pins (i.e., A and B signals) of the multi-way switch U3 to realize the path switching control of the multi-way switch U3. When AB is 00, the 1st and 3rd pins, 12th and 13th pins of the multi-way switch U3 are turned on, and the first resistor R1 and the fourth resistor R4 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 20KHz to 60KHz passband of the overall circuit. When AB is 01, the 5th and 3rd pins, 14th and 13th pins of the multi-way switch U3 are turned on, and the second resistor R2 and the fifth resistor R5 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 20KHz to 80KHz passband of the overall circuit. When AB is 10, the 2nd and 3rd pins, 15th and 13th pins of the multi-way switch U3 are turned on, and the third resistor R3 and the sixth resistor R6 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 80KHz to 200KHz passband of the overall circuit.

[0060] The programmable ultrasonic partial discharge signal conditioning circuit of the present invention realizes input signal overvoltage protection while realizing filter circuit bandwidth modulation and output signal gain amplitude adjustment. The working bandwidth and gain of the ultrasonic partial discharge signal conditioning circuit can be flexibly configured through program control to meet the optimal signal-to-noise ratio requirements of signal measurement and partial discharge monitoring requirements for different primary devices and different sensors. At the same time, a circuit can be applied to different scenarios, and the reliability of the circuit is also improved through large-scale application verification. Compared with the existing technology, it has the following advantages:

[0061] 1. The input signal protection circuit is a bidirectional overvoltage TVS protection tube, and the bidirectional protection breakdown voltage is the chip protection voltage ±15V.

[0062] 2. The programmable high-pass circuit is composed of resistors, capacitors, operational amplifiers and multi-way switches. The cut-off frequency of the high-pass circuit can be changed by program control of the multi-way switch to achieve programmable switching of the cut-off frequency between 20kHz and 80kHz.

[0063] 3. The programmable low-pass circuit is composed of resistors, capacitors, operational amplifiers and multi-way switches. The cut-off frequency of the low-pass circuit can be changed by program control of the multi-way switch to achieve programmable switching of the cut-off frequency of 60kHz, 80kHz and 200kHz.

[0064] 4. The programmable gain amplifier circuit is composed of resistors, capacitors, operational amplifiers and multi-way switches. The gain of the gain amplifier circuit can be changed by program control of the multi-way switch, so that the gain can be switched between 4, 16, 64 and 128 times.

[0065] The embodiment of the present invention further provides an ultrasonic partial discharge sensor, which includes: a microprocessor and the above-mentioned programmable ultrasonic partial discharge signal conditioning circuit. The microprocessor is used to control the multi-way switch of the programmable ultrasonic partial discharge signal conditioning circuit to switch the paths, so as to adjust the bandwidth and gain of the programmable ultrasonic partial discharge signal conditioning circuit.

[0066] The microprocessor controls the pin level of the multi-way switch to realize the path switching of the multi-way switch. When AB is 00, the 1st and 3rd pins, 12th and 13th pins of the multi-way switch U3 are turned on, and the first resistor R1 and the fourth resistor R4 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 20KHz~60KHz passband of the overall circuit. When AB is 01, the 5th and 3rd pins, 14th and 13th pins of the multi-way switch U3 are turned on, and the second resistor R2 and the fifth resistor R5 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 20KHz~80KHz passband of the overall circuit. When AB is 10, the 2nd and 3rd pins, 15th and 13th pins of the multi-way switch U3 are turned on, and the third resistor R3 and the sixth resistor R6 are respectively connected to the low-pass filter circuit and the high-pass filter circuit to realize the 80KHz~200KHz passband of the overall circuit.

[0067] The microprocessor controls the G0, G1, and G2 pin levels of the programmable gain amplifier U4 to control the amplifier to output different gains. The voltage amplitude can be adaptively adjusted by sampling, and the amplified voltage is clamped by a diode to ensure that the voltage does not exceed the limit and the MCU pin is not damaged.

[0068] The optional embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above embodiments. Within the technical concept of the embodiments of the present invention, a variety of simple modifications can be made to the technical solutions of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention. It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction, and as long as the combination does not violate the concept of the embodiments of the present invention, it should also be regarded as the content disclosed in the embodiments of the present invention.

Claims

1. A programmable ultrasonic partial discharge signal conditioning circuit, characterized in that: include: An input signal protection circuit, a programmable filtering circuit and a programmable gain amplifier circuit are connected in series in sequence; The input signal protection circuit is used to limit the input ultrasonic partial discharge signal to a preset voltage range; The programmable filter circuit is used to filter the ultrasonic partial discharge signal output by the input signal protection circuit, and output the filtered ultrasonic partial discharge signal; the programmable filter circuit includes: a low-pass filter circuit, a high-pass filter circuit, and a multi-way switch connected to the low-pass filter circuit and the high-pass filter circuit, and the multi-way switch is used to switch the paths under program control to change the cutoff frequencies of the low-pass filter circuit and the high-pass filter circuit; The programmable gain amplifier circuit is used to amplify the filtered ultrasonic partial discharge signal output by the programmable filter circuit and output the amplified ultrasonic partial discharge signal; the programmable gain amplifier circuit includes a programmable gain amplifier, and the programmable gain amplifier is used to output different gains under program control.

2. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 1, characterized in that: The input signal protection circuit comprises: a bidirectional breakdown diode, one end of which inputs an ultrasonic partial discharge signal and is connected to a low-pass filter circuit of the programmable filter circuit, and the other end of which is connected to a signal ground.

3. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 1, characterized in that: The low-pass filter circuit comprises: a first group of resistors and a first operational amplifier; The output end of the input signal protection circuit is respectively connected to multiple selection ports on one side of the multi-way switch through multiple resistors in the first group of resistors, and the control port on one side of the multi-way switch is connected to the positive input end of the first operational amplifier; The negative input terminal and the output terminal of the first operational amplifier are connected in parallel and then connected to the control port on the other side of the multi-way switch.

4. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 3, characterized in that: The low-pass filter circuit further includes: a first capacitor, and a control port on one side of the multi-way switch is connected to a signal ground through the first capacitor.

5. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 3, characterized in that: The high-pass filter circuit includes: a second group of resistors and a second operational amplifier; The positive input terminal of the second operational amplifier is respectively connected to the multiple selection ports on the other side of the multi-way switch through multiple resistors in the second group of resistors; The negative input terminal and the output terminal of the second operational amplifier are connected in parallel and then connected to the input terminal of the programmable gain amplifier.

6. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 3, characterized in that: The high-pass filter circuit includes: a second capacitor; The negative input terminal and the output terminal of the first operational amplifier are connected in parallel and then connected to the control port on the other side of the multi-way switch through the second capacitor.

7. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 3, characterized in that: The programmable gain amplifier circuit further includes: a first clamping diode, wherein an anode of the first clamping diode is connected to a signal ground, and a cathode of the first clamping diode is connected to an output end of the programmable gain amplifier.

8. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 5, characterized in that: The programmable gain amplifier circuit further includes: a second clamping diode, wherein an anode of the second clamping diode is connected to an output end of the programmable gain amplifier, and a cathode of the second clamping diode is connected to a power supply end.

9. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 3, characterized in that: The first group of resistors of the low-pass filter circuit includes: a first resistor, a second resistor and a third resistor; The output end of the input signal protection circuit is connected to three selection ports on one side of the multi-way switch through a first resistor, a second resistor and a third resistor respectively.

10. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 5, characterized in that: The second group of resistors of the high-pass filter circuit includes: a fourth resistor, a fifth resistor and a sixth resistor; The positive input terminal of the second operational amplifier is connected to the three selection ports on the other side of the multi-way switch through a fourth resistor, a fifth resistor and a sixth resistor respectively.

11. The programmable ultrasonic partial discharge signal conditioning circuit according to claim 8, characterized in that: The programmable gain amplifier circuit further includes: a seventh resistor and an eighth resistor; The negative input terminal and the output terminal of the second operational amplifier are connected in parallel and then connected to the input terminal of the programmable gain amplifier through the seventh resistor; An anode of the second clamping diode is connected to an output end of the programmable gain amplifier through the eighth resistor.

12. An ultrasonic partial discharge sensor, characterized in that: The ultrasonic partial discharge sensor comprises: a microprocessor and a programmable ultrasonic partial discharge signal conditioning circuit according to any one of claims 1 to 11; The microprocessor is used to control the multi-way switch of the programmable ultrasonic partial discharge signal conditioning circuit to switch the paths so as to adjust the bandwidth and gain of the programmable ultrasonic partial discharge signal conditioning circuit.

13. The ultrasonic partial discharge sensor according to claim 12, characterized in that: The microprocessor controls the pin level of the multi-way switch to implement path switching of the multi-way switch; The microprocessor controls the pin level of the programmable gain amplifier to control the amplifier to output different gains.

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