End screen signal processing circuit for on-line monitoring of insulation state of valve side bushing

Abstract

The utility model discloses an end screen signal processing circuit for valve side bushing insulation state on-line monitoring, which relates to the technical field of equipment detection, and comprises an end screen voltage dividing module, a voltage reducing circuit module, a voltage stabilizing circuit module, a voltage stabilizing circuit module and a power supply module, the step-down circuit module is connected with the signal isolation module through the low-pass filtering module. Compared with the prior art, the end screen signal processing circuit for on-line monitoring of the insulation state of the valve side sleeve has the advantages of being good in reliability and anti-interference capability.

Description

Technical Field

[0001] The utility model relates to the technical field of equipment detection, in particular to a signal processing circuit for the end screen of on-line monitoring of the insulation state of valve side bushings. Background Art

[0002] The insulation state of the valve side bushing of a converter transformer plays a key role in the safe operation of a converter station. There are many literatures on the monitoring methods of the insulation state of valve side bushings. For example, Chinese invention patent CN112305319A, "A Method and System for On-line Monitoring Parameters of Valve Side Bushings of Converter Transformers" and Chinese invention patent CN116643091A, "On-line Insulation Monitoring Method for Valve Side Bushings of Converter Transformers Based on Multi-dimensional Time Series Features" both perform a series of processes on the digital signals after the acquisition and conversion of the end screen signals of the valve side bushings to judge the insulation state of the valve side bushings. However, the literature does not describe the processing method of the end screen signal of the valve side bushing before acquisition and conversion.

[0003] The valve side bushing of a converter transformer can be equivalent to a capacitor CT. The end screen of the bushing is grounded through a capacitor CM. There is an AC voltage with an effective value between 60V and 100V and containing harmonics across the capacitor CM. The signal collected by the on-line monitoring device for the insulation state of the valve side bushing is derived from the voltage signal across this capacitor. The amplitude of this voltage signal is relatively large and cannot be directly connected to the acquisition unit. Therefore, voltage reduction processing is required. At the same time, the large current and high voltage flowing through the valve side bushing will generate a series of electromagnetic interferences. In order to prevent these electromagnetic interferences and other noises from being coupled to the acquisition unit through the wire and affecting the stable operation of the acquisition system, signal isolation processing is required.

[0004] The traditional AC voltage signal isolation method is to use a voltage transformer. This circuit structure is simple, but the voltage transformer is large in volume and occupies a certain space. At the same time, the primary side of the voltage transformer is connected to the capacitor, and resonance will occur under certain conditions, thus affecting the stable operation of the converter station system. Summary of the Utility Model

[0005] In this part, as well as in the abstract and title of the specification of this application, some simplifications or omissions may be made to avoid obscuring the purpose of this part, the abstract of the specification, and the title of the utility model. However, such simplifications or omissions cannot be used to limit the scope of the utility model.

[0006] In view of the problems existing in the above or the prior art, the present utility model is proposed.

[0007] To solve the above technical problems, the present utility model provides the following technical solution: an end screen voltage division module, the end screen voltage division module transmits the voltage signal across the capacitor CM to a voltage reduction circuit module, and the voltage reduction circuit module is connected to a signal isolation module through a low-pass filter module.

[0008] As a preferred solution of the signal processing circuit for the end screen of the on-line monitoring of the insulation state of the valve-side bushing of the present utility model, wherein: the step-down circuit module is composed of a resistor voltage-dividing network and a protection circuit;

[0009] The protection circuit includes a second resistor, a ninth resistor, a tenth resistor, and an eleventh resistor. The eleventh resistor is connected in parallel with the end screen voltage-dividing module. One end of the tenth resistor is connected to the end screen voltage-dividing module, and the other end is grounded;

[0010] The second resistor and the ninth resistor are respectively connected in series at both ends of the end screen voltage-dividing module.

[0011] As a preferred solution of the signal processing circuit for the end screen of the on-line monitoring of the insulation state of the valve-side bushing of the present utility model, wherein: the resistor voltage-dividing network includes a fifth resistor, a fourth capacitor, a seventh capacitor, a twelfth resistor, a first diode, and a second diode;

[0012] One end of the fifth resistor and the fourth capacitor in parallel is connected in series with the second resistor, and the other end is grounded;

[0013] One end of the twelfth resistor and the seventh capacitor in parallel is connected in series with the ninth resistor, and the other end is grounded;

[0014] The first diode and the second diode are respectively connected in parallel between the second resistor and the ninth resistor.

[0015] As a preferred solution of the signal processing circuit for the end screen of the on-line monitoring of the insulation state of the valve-side bushing of the present utility model, wherein: the resistor voltage-dividing network includes a fifth resistor, a fourth capacitor, a seventh capacitor, a twelfth resistor, a first TVS tube, and a second TVS tube;

[0016] One ends of the fifth resistor, the fourth capacitor, and the first TVS tube are respectively connected to the second resistor, and the other ends are grounded;

[0017] One ends of the twelfth resistor, the seventh capacitor, and the second TVS tube are respectively connected to the ninth resistor, and the other ends are grounded.

[0018] As a preferred solution of the signal processing circuit for the end screen of the on-line monitoring of the insulation state of the valve-side bushing of the present utility model, wherein: the low-pass filtering module includes a fifth amplifier. The VIN+ pin of the fifth amplifier is sequentially connected to the second resistor through a third resistor and a fourth resistor; the VIN- pin of the fifth amplifier is sequentially connected to the ninth resistor through a seventh resistor and a sixth resistor. A third capacitor is also connected across the VIN+ pin and the VOUT- pin of the fifth amplifier. A sixth capacitor is connected across the VIN- and VOUT+ of the fifth amplifier. The VOCM pin of the fifth amplifier is grounded;

[0019] A fifth capacitor is connected between the third resistor and the seventh resistor;

[0020] A first resistor is also connected in parallel across both ends of the third resistor and the third capacitor;

[0021] An eighth resistor is also connected in parallel across both ends of the seventh resistor and the sixth capacitor.

[0022] As a preferred solution of the terminal screen signal processing circuit for on-line monitoring of the insulation state of the valve side bushing in the present utility model, wherein: the low-pass filtering module includes a fifth amplifier, and the VIN+ pin of the fifth amplifier is sequentially connected to the second resistor through the third resistor and the fourth resistor; the VIN- pin of the fifth amplifier is sequentially connected to the ninth resistor through the seventh resistor and the sixth resistor, a third capacitor is connected across the VIN+ pin and the VOUT- pin of the fifth amplifier, a sixth capacitor is connected across the VIN- and VOUT+ of the fifth amplifier, the VOCM pin of the fifth amplifier is respectively connected to the fifteenth resistor and the sixteenth resistor, the other end of the fifteenth resistor is grounded, and the other end of the sixteenth resistor is connected to the signal conversion module;

[0023] A fifth capacitor is connected between the third resistor and the seventh resistor;

[0024] A first resistor is connected in parallel across both ends of the third resistor and the third capacitor;

[0025] An eighth resistor is connected in parallel across both ends of the seventh resistor and the sixth capacitor.

[0026] As a preferred solution of the terminal screen signal processing circuit for on-line monitoring of the insulation state of the valve side bushing in the present utility model, wherein: a signal conversion module is provided between the signal isolation module and the low-pass filtering module, the signal conversion module includes an analog-to-digital converter, the IN- pin of the analog-to-digital converter is connected to the VOUT- pin of the fifth amplifier through a thirteenth resistor, and the IN+ pin of the analog-to-digital converter is connected to the VOUT+ pin of the fifth amplifier through a fourteenth resistor;

[0027] A ninth capacitor is connected between the IN- pin of the analog-to-digital converter and the thirteenth resistor, and the other end of the ninth capacitor is grounded;

[0028] An eighth capacitor is connected between the IN+ pin of the analog-to-digital converter and the fourteenth resistor, and the other end of the eighth capacitor is grounded.

[0029] As a preferred solution of the terminal screen signal processing circuit for on-line monitoring of the insulation state of the valve side bushing in the present utility model, wherein: the analog signal isolation module includes an isolation amplifier, the VIN+ pin of the isolation amplifier is connected to the VOUT- pin of the fifth amplifier, and the VIN- pin of the isolation amplifier is connected to the VOUT+ pin of the fifth amplifier.

[0030] As a preferred solution of the end - screen signal processing circuit for on - line monitoring of the insulation state of the valve - side bushing of the present utility model, where: the analog - digital signal isolation module includes an isolation analog - to - digital converter, and the VIN - pin of the isolation analog - to - digital converter is connected to the VOUT - pin of the fifth amplifier; the VIN + pin of the isolation analog - to - digital converter is connected to the VOUT + pin of the fifth amplifier.

[0031] As a preferred solution of the end - screen signal processing circuit for on - line monitoring of the insulation state of the valve - side bushing of the present utility model, where: the digital signal isolation module includes a digital signal isolation chip, and the VO1 pin, VO2 pin, VO3 pin, and VIN4 pin of the digital signal isolation chip are respectively connected to the CNV pin, SDI pin, SCK pin, and SDO pin of the analog - to - digital converter.

[0032] The beneficial effects of the present utility model: Compared with the prior art, the end - screen signal processing circuit for on - line monitoring of the insulation state of the valve - side bushing proposed in this solution has good reliability and anti - interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the following - described drawings are only some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings. Among them:

[0034] Figure 1 is a block diagram of an end - screen signal processing circuit for on - line monitoring of the insulation state of a valve - side bushing based on analog signal isolation;

[0035] Figure 2 is a block diagram of an end - screen signal processing circuit for on - line monitoring of the insulation state of a valve - side bushing based on analog - digital signal isolation;

[0036] Figure 3 is a block diagram of an end - screen signal processing circuit for on - line monitoring of the insulation state of a valve - side bushing based on digital signal isolation;

[0037] Figure 4 is a schematic connection diagram of an end - screen signal processing circuit for on - line monitoring of the insulation state of a valve - side bushing based on analog signal isolation;

[0038] Figure 5 is a schematic connection diagram of an end - screen signal processing circuit for on - line monitoring of the insulation state of a valve - side bushing based on analog - digital signal isolation;

[0039] Figure 6It is a schematic connection diagram of the signal processing circuit for the end screen of on-line monitoring of the insulation state of the valve side bushing based on digital signal isolation.

[0040] 100. End screen voltage division module; 200. Step-down circuit module; 300. Low-pass filter module; 400. Signal isolation module; 401. Analog signal isolation module; 402. Analog-digital signal isolation module; 403. Digital signal isolation module; 500. Acquisition unit; 600. Signal conversion module; R1. First resistor; R2. Second resistor; R3. Third resistor; R4. Fourth resistor; R5. Fifth resistor; R6. Sixth resistor; R7. Seventh resistor; R8. Eighth resistor; R9. Ninth resistor; R10. Tenth resistor; R11. Eleventh resistor; R12. Twelfth resistor; R13. Thirteenth resistor; R14. Fourteenth resistor; R15. Fifteenth resistor; R16. Sixteenth resistor; C3. Third capacitor; C4. Fourth capacitor; C5. Fifth capacitor; C6. Sixth capacitor; C7. Seventh capacitor; C8. Eighth capacitor; C9. Ninth capacitor; D1. First diode; D2. Second diode; T1. First TVS tube; T2. Second TVS tube; U1. Isolated analog-to-digital converter; U2. Analog-to-digital converter; U3. Isolated amplifier; U4. Digital signal isolation chip; U5. Fifth amplifier. Detailed implementation manners

[0041] In order to make the above objects, features and advantages of the present utility model more obvious and understandable, the following will describe the detailed implementation manners of the present utility model in conjunction with the accompanying drawings of the specification.

[0042] In the following description, many specific details are set forth in order to fully understand the present utility model. However, the present utility model can also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the connotation of the present utility model. Therefore, the present utility model is not limited by the specific embodiments disclosed below.

[0043] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present utility model. The "in one embodiment" appearing in different places in this specification does not all refer to the same embodiment, nor is it an embodiment that is separate or selectively mutually exclusive with other embodiments.

[0044] Embodiment 1

[0045] Refer to Figures 1 to 3, which is the first embodiment of the present utility model. This embodiment provides a signal processing circuit for the end screen of on-line monitoring of the insulation state of the valve side bushing, which includes an end screen voltage dividing module 100. The end screen voltage dividing module 100 transmits the voltage signal across the capacitor CM to the step-down circuit module 200, and the step-down circuit module 200 is connected to the signal isolation module 400 through the low-pass filtering module 300.

[0046] Among them, the end screen voltage dividing module is installed on the valve side bushing by the valve side bushing manufacturer, and an outgoing line interface is reserved. The valve side bushing can be equivalent to a capacitor. One end of this capacitor is connected to the conductive rod in the bushing, and the other end is connected to one end of the capacitor CM of the end screen voltage divider of the bushing. The other end of the capacitor CM of the end screen voltage divider is connected to the metal shell of the bushing and finally connected to the ground.

[0047] The step-down circuit module is composed of a resistor voltage dividing network and a protection circuit. The resistor voltage dividing network is used to reduce the high voltage signal output by the end screen voltage divider to a certain voltage range, such as ±5V. The specific range is determined according to the input range of the subsequent processing circuit and then input to the subsequent circuit processing module. The protection circuit is composed of varistors, which clamp the signal input to the step-down circuit module to protect the components in the step-down circuit module from damage.

[0048] The low-pass filtering module 300 is composed of a source filter and is used to filter out the high-frequency components in the output signal of the previous stage module.

[0049] The signal isolation module 400 is composed of a signal isolation chip, which isolates the input signal and its power supply of the circuit from the output signal and its power supply, so that the two have no electrical connection, and prevents the noise and interference signals coupled from the outside at the input end from being transmitted to the output end. There are mainly three ways to achieve signal isolation: electromagnetic isolation, optoelectronic isolation and capacitive isolation.

[0050] Embodiment 2

[0051] Refer to Figure 1 and Figure 4 , which is the second embodiment of the present utility model. The difference from the first embodiment is that it further includes. In the previous embodiment,

[0052] The step-down circuit module is composed of a resistor voltage dividing network and a protection circuit;

[0053] The protection circuit includes a second resistor R2, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11. The eleventh resistor R11 is connected in parallel with the end screen voltage dividing module. One end of the tenth resistor R10 is connected to the end screen voltage dividing module, and the other end is grounded;

[0054] The second resistor R2 and the ninth resistor R9 are respectively connected in series across the end screen voltage dividing module.

[0055] The resistor voltage division network includes a fifth resistor R5, a fourth capacitor C4, a seventh capacitor C7, a twelfth resistor R12, a first diode D1, and a second diode D2;

[0056] One end of the fifth resistor R5 in parallel with the fourth capacitor C4 is connected in series with the second resistor R2, and the other end is grounded;

[0057] One end of the twelfth resistor R12 in parallel with the seventh capacitor C7 is connected in series with the ninth resistor R9, and the other end is grounded;

[0058] The first diode D1 and the second diode D2 are respectively connected in parallel between the second resistor R2 and the ninth resistor R9.

[0059] One end of the capacitor CM is connected to one end of the second resistor R2, the tenth resistor R10, and the eleventh resistor R11 through a wire, and both the tenth resistor R10 and the eleventh resistor R11 are varistors; the other end of the capacitor CM is connected to the ground, and at the same time is connected to the other end of the eleventh resistor R11 and one end of the ninth resistor R9 through a wire; the other end of the tenth resistor R10 is connected to the ground; the other end of the second resistor R2 is connected to one end of the fifth resistor R5, the fourth capacitor C4, the first diode D1, and the second diode D2, the other end of the fifth resistor R5 is connected to the other end of the fourth capacitor C4, and is simultaneously connected to GND_1; the other end of the ninth resistor R9 is connected to one end of the twelfth resistor R12 and the seventh capacitor C7, and is simultaneously connected to the other ends of the first diode D1 and the second diode D2; the other end of the twelfth resistor R12 is connected to the other end of the seventh capacitor C7, and is simultaneously connected to GND_1; the voltage across the two ends of the first diode D1 is the voltage after the voltage of the end screen voltage divider passes through the step-down circuit. Generally, the second resistor R2 is equal to the ninth resistor R9, the fifth resistor R5 is equal to the twelfth resistor R12, the fourth capacitor C4 is equal to the seventh C7, and the second resistor R2 and the fourth capacitor C4, the ninth resistor R9 and the seventh capacitor C7 form a low-pass filter circuit.

[0060] The low-pass filter module includes a fifth amplifier U5. The VIN+ pin of the fifth amplifier U5 is connected to the second resistor R2 through the third resistor R3 and the fourth resistor R4 in sequence; the VIN- pin of the fifth amplifier U5 is connected to the ninth resistor R9 through the seventh resistor R7 and the sixth resistor R6 in sequence. A third capacitor C3 is connected across the VIN+ pin and the VOUT- pin of the fifth amplifier U5, and a sixth capacitor C6 is connected across the VIN- and VOUT+ of the fifth amplifier U5. The VOCM pin of the fifth amplifier U5 is connected to the fifteenth resistor R15 and the sixteenth resistor R16 respectively. The other end of the fifteenth resistor R15 is grounded, and the other end of the sixteenth resistor R16 is connected to the signal conversion module 600;

[0061] A fifth capacitor C5 is connected between the third resistor R3 and the seventh resistor R7;

[0062] A first resistor R1 is connected in parallel across both ends of a third resistor R3 and a third capacitor C3;

[0063] An eighth resistor R8 is connected in parallel across both ends of a seventh resistor R7 and a sixth capacitor C6

[0064] Wherein, the other end of a fourth resistor R4 is connected to one ends of a fifth capacitor C5, the first resistor R1 and the third resistor R3; the other end of a sixth resistor R6 is connected to one ends of the fifth capacitor C5, the seventh resistor R7 and the eighth resistor R8; the other end of the third resistor R3 is connected to one end of the third capacitor C3 and they are jointly connected to the VIN+ pin of a fifth amplifier U5; the other end of the seventh resistor R7 is connected to one end of the sixth capacitor C6 and they are jointly connected to the VIN- pin of the fifth amplifier U5, and the fifth amplifier U5 is a fully differential operational amplifier; the other end of the first resistor R1 is connected to the other end of the third capacitor C3 and they are jointly connected to the VOUT- pin of the fifth amplifier U5; the other end of the eighth resistor R8 is connected to the other end of the sixth capacitor C6 and they are jointly connected to the VOUT+ pin of the fifth amplifier U5; the VOCM pin of the fifth amplifier U5 is connected to GND_1, the VCC+ pin is connected to VDD, and the VCC- pin is connected to VEE; VDD, GND_2, and VEE are respectively the positive electrode, common terminal, and negative electrode of the third DC power supply.

[0065] The analog signal isolation module 401 of the signal isolation module 400 includes an isolation amplifier U3. The VIN+ pin of the isolation amplifier U3 is connected to the VOUT- pin of the fifth amplifier U5, and the VIN- pin of the isolation amplifier U3 is connected to the VOUT+ pin of the fifth amplifier U5.

[0066] In addition, the VOUT- pin of the fifth amplifier U5 is connected to the VIN+ pin of the isolation amplifier U3, and the VOUT+ pin of the fifth amplifier U5 is connected to the VIN- pin of the isolation amplifier U3; the VDD1 pin of the isolation amplifier U3 is connected to the power supply VCC_1, and the GND1 pin of the isolation amplifier U3 is connected to GND_1; VCC_1 and GND_1 are respectively the positive and negative electrodes of the first DC power supply. The GND2 pin of the isolation amplifier U3 is connected to GND_2, and the VDD2 pin of the isolation amplifier U3 is connected to VCC_2; VCC_2 and GND_2 are respectively the positive and negative electrodes of the second DC power supply.

[0067] In summary, the last-stage voltage division module 100 reduces the AC high-voltage signal flowing through the conductive rod in the bushing to dozens of volts and outputs it to the step-down circuit module 200. The step-down circuit module 200 further reduces its input voltage and outputs it to the isolation amplifier U3. The isolation amplifier U3 electrically isolates its input signal and output signal to prevent the noise and interference signals coupled in the input signal from entering the circuit connected to its output signal, and amplifies the input signal by a certain multiple and outputs it to the low-pass filter module. The low-pass filter module 300 filters out high-frequency interference from the input signal and further amplifies it.

[0068] Embodiment 3

[0069] Referring to Figure 2 and Figure 5 , this is the third embodiment of the present invention. What is different from the previous two embodiments is that it includes

[0070] The step-down circuit module is composed of a resistor voltage division network and a protection circuit;

[0071] The protection circuit includes a second resistor R2, a ninth resistor R9, a tenth resistor R10, and an eleventh resistor R11. The eleventh resistor R11 is connected in parallel with the last-stage voltage division module. One end of the tenth resistor R10 is connected to the last-stage voltage division module, and the other end is grounded;

[0072] One ends of a fifth resistor R5, a fourth capacitor C4, and a first TVS tube T1 are respectively connected to the second resistor R2, and the other ends are grounded;

[0073] One ends of a twelfth resistor R12, a seventh capacitor C7, and a second TVS tube T2 are respectively connected to the ninth resistor R9, and the other ends are grounded.

[0074] One end of the capacitor CM is connected to one ends of the second resistor R2, the tenth resistor R10, and the eleventh resistor R11 through a wire. The other end of the capacitor CM is connected to the ground and is also connected to the other end of the eleventh resistor R11 and one end of the ninth resistor R9 through a wire; the other end of the tenth resistor R10 is connected to the ground; the other end of the second resistor R2 is connected to one ends of the fifth resistor R5, the fourth capacitor C4, and the first TVS tube T1. The other end of the fifth resistor R5 is connected to the other ends of the fourth capacitor C4 and the first TVS tube T1 and is simultaneously connected to GND_1; the other end of the ninth resistor R9 is connected to one ends of the twelfth resistor R12, the seventh capacitor C7, and the second TVS tube T2; the other end of the twelfth resistor R12 is connected to the other ends of the seventh capacitor C7 and the second TVS tube T2 and is simultaneously connected to GND_1. Generally, the second resistor R2 is equal to the ninth resistor R9, the fifth resistor R5 is equal to the twelfth resistor R12, the fourth capacitor C4 is equal to the seventh capacitor C7, and the second resistor R2 and the fourth capacitor C4, the ninth resistor R9 and the seventh capacitor C7 form a low-pass filter circuit.

[0075] In addition, the other end of the second resistor R2 is also connected to one end of the fourth resistor R4, and the other end of the ninth resistor R9 is also connected to one end of the sixth resistor R6; the other end of the fourth resistor R4 is connected to one end of the fifth capacitor C5, the first resistor R1, and the third resistor R3; the other end of the sixth resistor R6 is connected to the other end of the fifth capacitor C5 and one ends of the seventh resistor R7 and the eighth resistor R8; the other end of the third resistor R3 is connected to one end of the third capacitor C3 and is also connected to the VIN+ pin of the fifth amplifier U5; the other end of the seventh resistor R7 is connected to one end of the sixth capacitor C6 and is also connected to the VIN- pin of the fifth amplifier U5; the other end of the first resistor R1 is connected to the other end of the third capacitor C3 and is connected to the VOUT- pin of the fifth amplifier U5; the other end of the eighth resistor R8 is connected to the other end of the sixth capacitor C6 and is connected to the VOUT+ pin of the fifth amplifier U5; the VOCM pin of the fifth amplifier U5 is connected to GND_1, the VCC+ pin is connected to VDD, and the VCC- pin is connected to VEE; VDD, GND_1, and VEE are respectively the positive electrode, the common terminal, and the negative electrode of the first DC power supply.

[0076] The analog-digital signal isolation module 402 includes an isolated analog-to-digital converter U1. The VIN- pin of the isolated analog-to-digital converter U1 is connected to the VOUT- pin of the fifth amplifier U5; the VIN+ pin of the isolated analog-to-digital converter U1 is connected to the VOUT+ pin of the fifth amplifier U5.

[0077] Among them, the other end of the resistor R1 is also connected to the VIN- pin of the isolated analog-to-digital converter U1, and the other end of the eighth resistor R8 is also connected to the VIN+ pin of the isolated analog-to-digital converter U1. The VDD1 pin of the isolated analog-to-digital converter U1 is connected to VDD, the GND1 pin is connected to GND_1, the GND2 pin is connected to GND_2, the VDD2 pin is connected to VCC_2, and the MDAT pin and the MCLK pin are respectively connected to the corresponding pins of the acquisition unit 500. VCC_2 and GND_2 are respectively the positive electrode and the negative electrode of the second DC power supply.

[0078] In summary, Figure 2It is a circuit block diagram of the signal processing of the end screen for on-line monitoring of the insulation status of the valve side bushing based on analog-digital signal isolation proposed by this solution. In the figure, the end screen voltage dividing module 100 reduces the AC high voltage signal flowing through the conductive rod in the bushing to dozens of volts and outputs it to the step-down circuit module 200. The step-down circuit module 200 further reduces its input voltage and outputs it to the low-pass filter module 300. The low-pass filter module 300 filters out high-frequency interference from the input signal and transforms the input voltage signal to the range acceptable by the subsequent circuit for output. The analog-digital signal isolation module 402 converts the input analog signal into a digital signal and outputs the digital signal to the acquisition unit 500 through the internal isolation circuit.

[0079] Embodiment 4

[0080] Referring to Figure 3 and Figure 6 , which is the third embodiment of the present utility model. The difference from the previous three embodiments is that a signal conversion module 600 is provided between the signal isolation module 400 and the low-pass filter module 300. The signal conversion module 600 includes an analog-to-digital converter U2. The IN- pin of the analog-to-digital converter U2 is connected to the VOUT- pin of the fifth amplifier U5 through the thirteenth resistor R13, and the IN+ pin of the analog-to-digital converter U2 is connected to the VOUT+ pin of the fifth amplifier U5 through the fourteenth resistor R14; and the signal conversion module 600 is used to convert the input analog signal into a digital signal for output.

[0081] A ninth capacitor C9 is connected between the IN- pin of the analog-to-digital converter U2 and the thirteenth resistor R13, and the other end of the ninth capacitor C9 is grounded;

[0082] An eighth capacitor C8 is connected between the IN+ pin of the analog-to-digital converter U2 and the fourteenth resistor R14, and the other end of the eighth capacitor C8 is grounded.

[0083] Among them, one end of the first resistor R1 is connected to one end of the thirteenth resistor R13, and the other end of the eighth resistor R8 is also connected to one end of the fourteenth resistor R14; the other end of the thirteenth resistor R13 is connected to one end of the ninth capacitor C9 and is simultaneously connected to the IN- pin of the analog-to-digital converter U2, and the other end of the fourteenth resistor R14 is connected to one end of the eighth capacitor C8 and is simultaneously connected to the IN+ pin of the analog-to-digital converter U2; the other ends of the eighth capacitor C8 and the ninth capacitor C9 are simultaneously connected to GND_1; the REF pin of the analog-to-digital converter U2 is connected to the sixteenth resistor R16, the VDD pin is connected to VDD, the GND pin is connected to GND_1, and the CNV pin of the analog-to-digital converter U2 is connected to the digital signal isolation chip U4.

[0084] The digital signal isolation module 403 includes a digital signal isolation chip U4. The VO1 pin, VO2 pin, VO3 pin, and VIN4 pin of the digital signal isolation chip U4 are respectively connected to the CNV pin, SDI pin, SCK pin, and SDO pin of the analog-to-digital converter U2.

[0085] Among them, the VDD1 pin of the digital signal isolation chip U4 is connected to VDD, the GND1 pin is connected to GND_1, the GND2 pin is connected to GND_2, the VDD2 pin is connected to VDD_2, and the VIN1 pin, VIN2 pin, VIN3 pin, and VO4 pin are respectively connected to the corresponding pins of the acquisition unit 500; the VO1 pin of the digital signal isolation chip U4 is connected to the CNV pin of the analog-to-digital converter U2, the SDI pin of the analog-to-digital converter U2 is connected to the VO2 pin of the digital signal isolation chip U4, the SCK pin of the analog-to-digital converter U2 is connected to the VO3 pin of the digital signal isolation chip U4, and the SDO pin of the analog-to-digital converter U2 is connected to the VIN4 pin of the digital signal isolation chip U4.

[0086] VDD and GND_1 are the positive and negative poles of the first DC power supply, and VCC_2 and GND_2 are the positive and negative poles of the second DC power supply.

[0087] In summary, Figure 3 is a circuit block diagram of the end-screen signal processing for on-line monitoring of the insulation state of the valve-side bushing based on digital signal isolation proposed in this solution. In the figure, the end-screen voltage division module 100 reduces the AC high-voltage signal flowing through the conductive rod in the bushing to dozens of volts and outputs it to the step-down circuit module 200. The step-down circuit module 200 further reduces its input voltage and outputs it to the low-pass filter module 300. The low-pass filter module 300 filters out high-frequency interference from its input signal and transforms the input voltage signal to the range acceptable to the subsequent circuit for output. The signal conversion module 600 converts the input analog signal into a digital signal and outputs it to the next-level circuit. The digital signal isolation module 403 electrically isolates the digital signal and its power supply at the input end from the digital signal and its power supply at the output end, preventing the noise and interference signals at the input end from being transmitted to the acquisition unit 500. The output end of the digital signal isolation module 403 is connected to the acquisition unit 500.

[0088] In the above embodiment, the low-pass filter module 300 composed of the fully differential operational amplifier and its peripheral circuit can also be composed of a non-fully differential operational amplifier, a general-purpose operational amplifier, and its peripheral circuit, which will not be elaborated here.

[0089] Through this processing circuit, the isolation between the input signal and the output signal is achieved, preventing the noise and interference signals coupled at the input end from being transmitted to the acquisition unit 500, and improving the reliability of the acquisition unit 500.

[0090] Importantly, it should be noted that the construction and arrangement of the present application shown in multiple different exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those who refer to this disclosure should easily understand that many modifications are possible without materially departing from the novel teachings and advantages of the subject matter described in this application (e.g., changes in the dimensions, scales, structures, shapes and proportions of various elements, as well as parameter values (such as temperature, pressure, etc.), installation arrangements, use of materials, colors, orientations, etc.). For example, elements shown as integrally formed may be composed of multiple parts or elements, the positions of the elements may be inverted or otherwise changed, and the nature, number or position of discrete elements may be altered or changed. Accordingly, all such modifications are intended to be included within the scope of the present utility model. The order or sequence of any process or method steps may be changed or reordered according to alternative embodiments. In the claims, any "means-plus-function" clause is intended to cover the structures that perform the recited function herein, and not only structural equivalents but also equivalent structures. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present utility model. Therefore, the present utility model is not limited to specific embodiments, but extends to various modifications that still fall within the scope of the appended claims.

[0091] In addition, to provide a concise description of the exemplary embodiments, not all features of the actual embodiments may be described (i.e., those features that are not relevant to the currently contemplated best mode of carrying out the present utility model or those features that are not relevant to the implementation of the present utility model).

[0092] It should be understood that in the development of any actual implementation, as in any engineering or design project, numerous specific implementation decisions may be made. Such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from this disclosure, without undue experimentation, such development efforts will be a routine task of design, manufacturing and production.

[0093] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present utility model and not to limit them. Although the present utility model has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present utility model may be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present utility model, and all of them should be covered by the scope of the claims of the present utility model.

Claims

1. A terminal screen signal processing circuit for online monitoring of the insulation status of a valve side casing, characterized in that: include, An end-screen voltage-dividing module (100) transmits a voltage signal at both ends of a capacitor CM to a voltage-reducing circuit module (200), and the voltage-reducing circuit module (200) is connected to a signal isolation module (400) via a low-pass filtering module (300).

2. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status according to claim 1, characterized in that: The step-down circuit module (200) is composed of a resistor voltage divider network and a protection circuit; The protection circuit comprises a second resistor (R2), a ninth resistor (R9), a tenth resistor (R10), and an eleventh resistor (R11); the eleventh resistor (R11) is connected in parallel to the end-screen voltage-dividing module (100); one end of the tenth resistor (R10) is connected to the end-screen voltage-dividing module (100), and the other end is grounded; The second resistor (R2) and the ninth resistor (R9) are respectively connected in series at two ends of the end-screen voltage-dividing module (100).

3. The end screen signal processing circuit for online monitoring of the valve side bushing insulation status as claimed in claim 2, Features: The resistor voltage divider network includes a fifth resistor (R5), a fourth capacitor (C4), a seventh capacitor (C7), a twelfth resistor (R12), a first diode (D1) and a second diode (D2); The fifth resistor (R5) is connected in parallel with the fourth capacitor (C4), one end of which is connected in series with the second resistor (R2), and the other end is grounded; The twelfth resistor (R12) is connected in parallel with the seventh capacitor (C7), one end of which is connected in series with the ninth resistor (R9), and the other end is grounded; The first diode (D1) and the second diode (D2) are respectively connected in parallel between the second resistor (R2) and the ninth resistor (R9).

4. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status as claimed in claim 2, characterized in that: The resistor voltage divider network includes a fifth resistor (R5), a fourth capacitor (C4), a seventh capacitor (C7), a twelfth resistor (R12), a first TVS tube (T1) and a second TVS tube (T2); One end of the fifth resistor (R5), the fourth capacitor (C4) and the first TVS tube (T1) is respectively connected to the second resistor (R2), and the other end is grounded; One ends of the twelfth resistor (R12), the seventh capacitor (C7) and the second TVS tube (T2) are respectively connected to the ninth resistor (R9), and the other ends are grounded.

5. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status as claimed in claim 3, characterized in that: The low-pass filter module (300) comprises a fifth amplifier U5, wherein a VIN+ pin of the fifth amplifier U5 is connected to a second resistor (R2) via a third resistor (R3), a fourth resistor (R4) in sequence; a VIN- pin of the fifth amplifier U5 is connected to a ninth resistor (R9) via a seventh resistor (R7), a sixth resistor (R6) in sequence; a third capacitor (C3) is bridged between the VIN+ pin and the VOUT- pin of the fifth amplifier U5; a sixth capacitor (C6) is bridged between the VIN- and VOUT+ of the fifth amplifier U5; and a VOCM pin of the fifth amplifier U5 is grounded; A fifth capacitor (C5) is connected between the third resistor (R3) and the seventh resistor (R7); A first resistor (R1) is also connected in parallel between the third resistor (R3) and the third capacitor (C3); An eighth resistor (R8) is also connected in parallel between the seventh resistor (R7) and the sixth capacitor (C6).

6. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status as claimed in claim 4, characterized in that: The low-pass filter module (300) comprises a fifth amplifier U5, the VIN+ pin of the fifth amplifier U5 is connected to the second resistor (R2) via a third resistor (R3) and a fourth resistor (R4) in sequence; the VIN- pin of the fifth amplifier U5 is connected to the ninth resistor (R9) via a seventh resistor (R7) and a sixth resistor (R6) in sequence; a third capacitor (C3) is bridged between the VIN+ pin and the VOUT- pin of the fifth amplifier U5; a sixth capacitor (C6) is bridged between the VIN- and VOUT+ of the fifth amplifier U5; the VOCM pin of the fifth amplifier U5 is respectively connected to the fifteenth resistor (R15) and the sixteenth resistor (R16); the other end of the fifteenth resistor (R15) is grounded; and the other end of the sixteenth resistor (R16) is connected to the signal conversion module (600); A fifth capacitor (C5) is connected between the third resistor (R3) and the seventh resistor (R7); The first resistor (R1) is connected in parallel between the third resistor (R3) and the third capacitor (C3); An eighth resistor (R8) is connected in parallel between the seventh resistor (R7) and the sixth capacitor (C6).

7. The end-screen signal processing circuit for online monitoring of the insulation status of the valve-side bushing according to claim 6, characterized in that: A signal conversion module (600) is provided between the signal isolation module (400) and the low-pass filter module (300), the signal conversion module (600) comprising an analog-to-digital converter U2, an IN- pin of the analog-to-digital converter U2 being connected to a VOUT- pin of a fifth amplifier U5 via a thirteenth resistor (R13), and an IN+ pin of the analog-to-digital converter U2 being connected to a VOUT+ pin of the fifth amplifier U5 via a fourteenth resistor (R14); A ninth capacitor (C9) is connected between the IN-pin of the analog-to-digital converter U2 and the thirteenth resistor (R13), and the other end of the ninth capacitor (C9) is grounded; An eighth capacitor (C8) is connected between the IN+ pin of the analog-to-digital converter U2 and the fourteenth resistor (R14), and the other end of the eighth capacitor (C8) is grounded.

8. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status as claimed in claim 5, characterized in that: The analog signal isolation module (401) comprises an isolation amplifier U3, a VIN+ pin of the isolation amplifier U3 is connected to a VOUT- pin of a fifth amplifier U5, and a VIN- pin of the isolation amplifier U3 is connected to a VOUT+ pin of the fifth amplifier U5.

9. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status according to claim 6, characterized in that: The analog-digital signal isolation module (402) comprises an isolated analog-to-digital converter U1, wherein the VIN- pin of the isolated analog-to-digital converter U1 is connected to the VOUT- pin of the fifth amplifier U5; and the VIN+ pin of the isolated analog-to-digital converter U1 is connected to the VOUT+ pin of the fifth amplifier U5.

10. The end-screen signal processing circuit for online monitoring of the valve-side bushing insulation status according to claim 6, characterized in that: The digital signal isolation module (403) comprises a digital signal isolation chip U4, wherein the VO1 pin, VO2 pin, VO3 pin and VIN4 pin of the digital signal isolation chip U4 are respectively connected to the CNV pin, SDI pin, SCK pin and SDO pin of the analog-to-digital converter U2.

Images