Non-intrusive hard strap voltage monitoring system and method

Abstract

The invention relates to a non-intrusive hard strap voltage monitoring system and method, and the system comprises an induction electrode which is used for forming a capacitor with a to-be-detected wire, and is parallel to the to-be-detected wire; the vibration mechanism enables the distance between the induction electrode and the wire to be measured to change according to a sine rule; and the signal processing circuit is used for detecting the charge change generated by the capacitance change on the induction electrode, converting the charge change into a voltage signal, and calculating the voltage value of the wire to be detected according to the peak-to-peak value of the voltage signal. According to the invention, there is no need to form electrical connection with a hard pressing plate wire, thereby preventing electric shock risks, short circuit hidden troubles and physical damages to a terminal structure caused by conventional intrusive measurement, and guaranteeing the safety of operation and maintenance personnel. The induction electrode is actively driven to periodically vibrate, so that the capacitance between the induction electrode and the wire to be measured dynamically changes according to a sine rule.

Description

Technical Field

[0001] This invention relates to the field of hard plate monitoring, and in particular to a non-invasive hard plate voltage monitoring system and method. Background Technology

[0002] Hardened circuit boards, as key control components in power system relay protection, automatic safety devices, and secondary circuits, are widely used in substations, power plants, and other scenarios to enable and disable protection functions. Their operating status (voltage amplitude, polarity, and on / off state) directly affects the safe and stable operation of the power grid. Real-time and accurate monitoring of the conductor voltage of the hardened circuit board is of great significance for preventing misoperation, identifying poor contact, and detecting hidden faults such as circuit breaks.

[0003] Current measurement methods involve directly connecting instruments such as multimeters and voltmeters to the hard-plate circuit. This method requires physical wiring while the circuit is energized, posing a risk of electric shock and short circuit; frequent plugging and unplugging can also lead to terminal wear and increased contact resistance. Summary of the Invention

[0004] In view of this, the present invention aims to provide a non-invasive hard plate voltage monitoring system and method to solve the problems in the prior art.

[0005] To achieve the above objectives, the technical solution of the present invention is implemented as follows: As a first aspect of the present invention, a non-invasive hard plate voltage monitoring system is disclosed, characterized in that: Includes: a sensing electrode for forming a capacitance with the wire under test, wherein the sensing electrode is arranged parallel to the wire under test; The vibration mechanism causes the distance between the sensing electrode and the conductor to be measured to change according to a sinusoidal law. The signal processing circuit is used to detect the charge change on the sensing electrode caused by the capacitance change, convert the charge change into a voltage signal, and calculate the voltage value of the conductor under test by the peak-to-peak value of the voltage signal.

[0006] Furthermore, the vibration mechanism includes a cantilever beam and a driving device, the sensing electrode is fixed on the cantilever beam, and the driving device is used to drive the cantilever beam to perform periodic vibration.

[0007] Furthermore, the driving device is a magnetoelectric driving device, comprising: A permanent magnet is fixed to the cantilever beam; An electromagnet, coaxially arranged with the permanent magnet, is used to generate an alternating magnetic field to drive the permanent magnet to vibrate.

[0008] Furthermore, the driving device is a piezoelectric driving device, comprising: A piezoelectric element, fixed to the cantilever beam, is used to drive the cantilever beam to vibrate when an AC voltage is applied.

[0009] Furthermore, the signal processing circuit includes: The field-effect transistor has its gate connected to the sensing electrode, its source grounded, and its drain connected to the power supply through a resistor. Capacitor 3 is connected between the drain of the field-effect transistor and ground, and is used to detect the voltage signal generated by the change in charge.

[0010] Furthermore, the peak-to-peak value of the AC voltage output from capacitor three is proportional to the magnitude of the voltage of the conductor under test.

[0011] Furthermore, the system also includes a polarity determination module, used to determine the polarity of the voltage to be measured based on the phase difference between the voltage signal and the drive signal.

[0012] As a second aspect of the present invention, a non-invasive hard plate voltage monitoring method is disclosed, the method being applied to the above-mentioned system, the method comprising the following steps: S1, the induction electrode is driven to vibrate periodically by the vibration mechanism, so that the distance between the induction electrode and the conductor to be measured changes according to a sinusoidal law; S2, detect the charge change on the sensing electrode caused by the capacitance change, and convert the charge change into a voltage signal; S3, calculate the voltage value of the conductor under test by using the peak-to-peak value of the voltage signal.

[0013] Compared with the prior art, the present invention has the following advantages: In this invention, there is no need to form an electrical connection with the hard plate wires, which avoids the risk of electric shock, short circuit hazards and physical damage to the terminal structure caused by traditional invasive measurement, and ensures the safety of maintenance personnel.

[0014] By actively driving the induction electrode to vibrate periodically, the capacitance between the induction electrode and the conductor under test changes dynamically according to a sinusoidal law, transforming the originally weak and static parasitic capacitance effect into an alternating induction signal with significantly enhanced amplitude. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the model analysis of the present invention; Figure 2 This is a schematic diagram of the actual model of the present invention; Figure 3 This is a schematic diagram of the magnetoelectric driven cantilever beam of the present invention; Figure 4 This is a schematic diagram of the connection of the induction electrode in the magnetoelectric drive of the present invention; Figure 5 This is a schematic diagram of the piezoelectric driven cantilever beam of the present invention; Figure 6 This is a circuit diagram of the electromagnet drive circuit of the present invention. Figure 7 This is a piezoelectric element driving circuit diagram of the present invention; Figure 8 This is a schematic diagram of the phase difference determination method when VS>0 in this invention; Figure 9 This is a schematic diagram of the phase difference determination method for VS<0 according to the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. First metal plate; 2. Second metal plate; 3. Capacitor 3; 4. Resistor 4; 5. Resistor 5; 6. Field-effect transistor; 7. Wire under test; 9. Cantilever arm; 10. Permanent magnet; 11. Electromagnet; 12. Induction electrode; 13. Piezoelectric element; 15. Resistor 15; 16. Resistor 16; 17. First operational amplifier; 18. First diode; 19. Second diode; 21. Transistor; 22. Resistor 22; 23. Resistor 23; 24. Resistor 24; 25. Resistor 25; 26. Resistor 26; 27. Resistor 27; 28. Second operational amplifier; 29. ​​Resistor 29; 30. Resistor 30; 32. Resistor 32; 33. Resistor 33; 34. Resistor 34; 35. Resistor 35. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0018] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," and "back," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0019] Furthermore, in the description of this invention, unless otherwise explicitly defined, the terms "installation," "connection," "linking," and "connector" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention in light of the specific circumstances.

[0020] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Example 1 Overall, this invention discloses a non-invasive hard plate voltage monitoring system, comprising: a sensing electrode 12 for forming a capacitance with a wire 7 under test, wherein the sensing electrode 12 is arranged parallel to the wire 7 under test; a vibration mechanism that causes the distance between the sensing electrode 12 and the wire 7 under test to change according to a sinusoidal law; and a signal processing circuit for detecting the charge change on the sensing electrode caused by the capacitance change, converting the charge change into a voltage signal, and calculating the voltage value of the wire under test by the peak-to-peak value of the voltage signal.

[0022] In this embodiment, there is no need to form an electrical connection with the hard plate wires, which avoids the risk of electric shock, short circuit, and physical damage to the terminal structure caused by traditional invasive measurement, thus ensuring the safety of maintenance personnel.

[0023] By actively driving the induction electrode to vibrate periodically, the capacitance between the induction electrode and the conductor under test changes dynamically according to a sinusoidal law, transforming the originally weak and static parasitic capacitance effect into an alternating induction signal with significantly enhanced amplitude. This overcomes the problems of weak signal and susceptibility to interference found in fixed electrode schemes.

[0024] It should be noted that the technical principle of this invention is as follows: like Figure 1 As shown, the distance between two parallel metal plates 1 and 2 is D, and their facing area is S. Then the capacitance between the first metal plate 1 and the second metal plate 2 is: C = ε0εᵣS / D (Equation 1) C: Capacitance value, measured in farads (F).

[0025] ε0: Vacuum permittivity, a fixed value of approximately 8.85 × 10⁻⁶. -12 F / m (substitute directly during calculation).

[0026] εᵣ: The relative permittivity of the medium between the plates (unitless), for example, εᵣ≈1 for air.

[0027] S: The area of ​​the first metal plate 1 and the second metal plate 2 facing each other, in square meters (m²). 2 ).

[0028] D: The distance between the first metal plate 1 and the second metal plate 2 (i.e., the thickness of the medium), in meters (m).

[0029] A voltage VS is applied to the first metal plate 1, and the second metal plate 2 is connected to a resistor of 5V, resulting in 0V. The voltage between the first metal plate 1 and the second metal plate 2 is VS. Therefore, the amount of charge Q stored between the first metal plate 1 and the second metal plate 2 is: Q = VSC (Equation 2) Substituting equation 1 into equation 2, we get: Q = VSε0εᵣS / D (Equation 3) Keeping the area of ​​the first metal plate 1 and the second metal plate 2 facing each other and the medium unchanged, then ε0εᵣS remains unchanged, so let A=ε0εᵣS; Then Q = VSA / D (Equation 4) If the first metal plate 1 remains stationary, and the second metal plate 2 moves up and down with a frequency of d*sin(ωt) (d is the amplitude of the change, and ω is the angular frequency); Then Q = VSA / (D + d*sin(ωt)) (Equation 5) As can be seen from Equation 5, the sinusoidal up-and-down movement of the second metal plate 2 will cause Q to change in a sinusoidal manner. If d is a constant value, then the peak-to-peak value of Q is proportional to the voltage VS between the two plates. Therefore, if the area A is kept constant, the average distance D between the two plates is kept constant, and the amplitude d of the movement of the metal plate 2 is kept constant, the magnitude of VS can be calculated by observing the peak-to-peak value of Q.

[0030] The signal processing circuit includes a field-effect transistor 6, whose gate is connected to the sensing electrode, its source is grounded, and its drain is connected to the power supply through a resistor 4. A capacitor, connected between the drain of the field-effect transistor 6 and ground, is used to detect the voltage signal generated by the change in charge.

[0031] Furthermore, the second metal plate 2 is connected to the gate of the field-effect transistor 6, the source of the field-effect transistor 6 is grounded, and the drain is connected to resistor 4 and then to Vdd. Changes in the charge Q stored between the first metal plate 1 and the second metal plate 2 will cause current to flow through resistor 5. Resistor 5 has a voltage drop, which causes a change in the gate voltage of the field-effect transistor 6, and consequently a change in the drain-to-source current of the field-effect transistor 6. The voltage drop across resistor 4 causes a change in the drain voltage. Since only the amount of change is of interest, capacitor 3 is connected to the drain of the field-effect transistor 6. The change in the voltage UO between the other end of capacitor 3 and ground can characterize the change in the charge Q stored between the first metal plate 1 and the second metal plate 2. Therefore, the magnitude of VS can be calculated by measuring the peak-to-peak value of UO.

[0032] It should be noted that, as Figure 2 and Figure 3 As shown, the first metal plate 1 is equivalent to the wire to be tested 7, and the second metal plate 2 is equivalent to the sensing electrode 12.

[0033] like Figure 3 As shown, the vibration mechanism includes a cantilever beam 9 and a driving device. The sensing electrode 12 is fixed on the cantilever beam 9, and the driving device is used to drive the cantilever beam 9 to perform periodic vibration.

[0034] As a preferred structure, the driving device is a magnetoelectric driving device, including: a permanent magnet 10, fixed on the cantilever beam 9; and an electromagnet 11 coaxially arranged with the permanent magnet 10, used to generate an alternating magnetic field to drive the permanent magnet 10 to vibrate.

[0035] In detail, such as Figure 3 and Figure 4 As shown, the induction electrode 12 is attached to the cantilever beam 9 and can move together with the cantilever beam. The induction electrode 12 is equivalent to the metal plate 2. The permanent magnet 10 is fixed to the cantilever beam 9. The electromagnet 11 and the permanent magnet 10 are coaxial. An alternating current is passed through the electromagnet 11 to generate an alternating magnetic field, causing the permanent magnet to move, which in turn drives the cantilever beam to vibrate. When a DC voltage is applied to the conductor 8 to be measured, and the cantilever beam 9 vibrates up and down in a sinusoidal pattern, a changing voltage will be generated on the induction electrode 12. The voltage on the conductor 8 to be measured can be calculated by the peak-to-peak value of the voltage change.

[0036] Circuit control such as Figure 5As shown, the DAC pin of the microcontroller outputs a voltage that varies sinusoidally. This voltage is filtered by a low-pass filter consisting of resistor 1515 and capacitor 2525 to remove noise. After being divided by resistors 1616 and 2424, the voltage is input to the positive input of the first operational amplifier 17. The output of the first operational amplifier 17 is connected to the base of NPN transistor 21 via resistor 2323. The collector of transistor 21 is connected to the cathode of the second diode 19 via electromagnet 11. The anode of the second diode 19 is connected to the power supply VDD. To eliminate the reverse current generated by electromagnet 11, a first diode 18 is connected in parallel across it. The emitter of transistor 21 is connected to ground via resistor 222. In addition, the emitter of transistor 21 is also connected to the inverting input of the first operational amplifier 17. Operational amplifier 17 operates in a deep negative feedback state, so the voltage at its inverting input is equal to the voltage at its non-inverting input. Since the inverting input of operational amplifier 17 is connected to the emitter of transistor 21, the emitter voltage of transistor 21 is also equal to the voltage at the non-inverting input of operational amplifier 17. The current flowing through resistor 22 is equal to the emitter voltage of transistor 21 divided by the resistance of resistor 22. Because the current flowing into the inverting input of operational amplifier 17 is close to zero (virtual short), and the current flowing through the collector and emitter of transistor 21... Since the difference in magnitude is approximately equal, the current flowing through electromagnet 11 is roughly equal to the current flowing through resistor 22. Therefore, the current flowing through electromagnet 11 can be controlled by controlling the current flowing through resistor 22. With the resistance value of resistor 22 fixed, the current flowing through resistor 22 is determined by the voltage at the positive input terminal of the first operational amplifier 17. Therefore, when the microcontroller's DAC pin outputs an AC voltage, a current of the same frequency will flow through electromagnet 20, and the peak-to-peak value of the current will be determined by the peak-to-peak value of the AC voltage output by the microcontroller's DAC pin.

[0037] As another preferred structure, the driving device is a piezoelectric driving device, including: a piezoelectric sheet 13, fixed on the cantilever beam 9, for driving the cantilever beam 9 to vibrate when an AC voltage is applied.

[0038] like Figure 5 As shown, the piezoelectric sheet 13 is fixed to the cantilever beam 9 with conductive adhesive, and the cantilever beam 9 can be driven to vibrate by applying an AC voltage to the piezoelectric sheet 13.

[0039] The driving circuit is shown in Figure 7. The voltage output from the DAC pin of the microcontroller changes sinusoidally. First, it passes through capacitor 35 to remove the DC bias. Then, it passes through a low-pass filter composed of resistor 26 and capacitor 34 to filter out noise. After being divided by resistors 27 and 33, it is input to the positive input of the second operational amplifier 28. The inverting input of the second operational amplifier 28 is connected to ground via resistor 32. The inverting input of the second operational amplifier 28 is also connected to its output via resistor 29. The output of the second operational amplifier 28 is connected to piezoelectric element 13 via resistor 30. The other end of piezoelectric element 13 is grounded. The function of this circuit is to amplify the voltage output from the DAC pin of the microcontroller and connect it to piezoelectric element 13 to drive it, thereby causing the cantilever beam 9 to vibrate.

[0040] The above analysis shows that the peak-to-peak value UO of the AC output voltage on capacitor 3 is directly proportional to the voltage VS of the conductor under test.

[0041] Furthermore, the system also includes a polarity determination module, used to determine the polarity of the voltage to be measured based on the phase difference between the voltage signal and the drive signal.

[0042] Based on the above settings, when VS > 0, U0 will increase when d*sin(ωt) increases and decrease when d*sin(ωt) decreases, and the phase of U0 d*sin(ωt) is the same. When VS < 0, U0 will decrease when d*sin(ωt) increases and increase when d*sin(ωt) decreases, and the phase of U0 d*sin(ωt) differs by 180 degrees. Therefore, the polarity of VS can be determined based on the phase difference. Both piezoelectric and magnetoelectric driven cantilever beams are driven by sinusoidal signals. Once the driving parameters are determined, the phase difference between the driving signal and the cantilever beam vibration is also basically determined. Therefore, the phase difference between the cantilever beam driving signal and UO can be measured for the two polarities of the voltage VS, and then the range of the phase difference for positive and negative polarities can be determined by combining the test results. This range can then be written into the code for determining the polarity of the voltage VS during actual testing.

[0043] Polarity determination is visible Figure 8 and Figure 9The drive signal for cantilever beam 9 is provided by the microcontroller's DAC pin, while UO is generated by the vibration of the cantilever beam. Therefore, the two signals have the same frequency. When measuring voltages of different polarities, the phase difference of UO is 180°. Thus, the phase difference between UO and the microcontroller's DAC output signal is also 180°. Therefore, the polarity of the voltage VS under test can be determined by the phase difference between UO and the microcontroller's DAC output signal. In actual production, the phase difference between UO and the microcontroller's DAC output signal will differ when measuring the same VS using different sensors. Therefore, through extensive sensor experiments, the maximum phase θ1MAX and minimum phase difference θ1MIN when VS > 0 can be found. When the measured phase difference θ1MIN < θ < θ1MAX, VS > 0 is determined. Similarly, the maximum phase θ2MAX and minimum phase difference θ2MIN when VS < 0 can be experimentally measured. When the measured phase difference θ2MIN < θ < θ2MAX, VS < 0 is determined.

[0044] Example 2 This embodiment discloses a non-invasive hard plate voltage monitoring method, which is applied to the monitoring system disclosed in Embodiment 1, and includes the following steps: The system according to any one of claims 1 to 7, the method comprising the following steps: S1, the induction electrode is driven to vibrate periodically by the vibration mechanism, so that the distance between the induction electrode and the conductor to be measured changes according to a sinusoidal law; S2, detects the charge change on the sensing electrode caused by the change in capacitance, and converts the charge change into a voltage signal; S3 calculates the voltage value of the conductor under test by using the peak-to-peak value of the voltage signal.

[0045] In summary, this invention adopts a completely non-contact and non-invasive measurement method. There is no need for electrical connection between the measuring probe and the wire of the hard pressure plate under test. This avoids the risk of short circuit or false connection of the control circuit caused by incorrect range or accidental contact of the probes when measuring with a traditional multimeter. It ensures the personal safety of the operator and protects the monitoring device itself from overvoltage impact.

[0046] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A non-invasive hard plate voltage monitoring system, characterized in that: include: A sensing electrode is used to form a capacitance with the wire under test, wherein the sensing electrode is arranged parallel to the wire under test; The vibration mechanism causes the distance between the sensing electrode and the conductor to be measured to change according to a sinusoidal law. The signal processing circuit is used to detect the charge change on the sensing electrode caused by the capacitance change, convert the charge change into a voltage signal, and calculate the voltage value of the conductor under test by the peak-to-peak value of the voltage signal.

2. The non-invasive hard plate voltage monitoring system according to claim 1, characterized in that: The vibration mechanism includes a cantilever beam and a driving device. The sensing electrode is fixed on the cantilever beam, and the driving device is used to drive the cantilever beam to perform periodic vibration.

3. The non-invasive hard plate voltage monitoring system according to claim 2, characterized in that: The driving device is a magnetoelectric driving device, comprising: A permanent magnet is fixed to the cantilever beam; An electromagnet, coaxially arranged with the permanent magnet, is used to generate an alternating magnetic field to drive the permanent magnet to vibrate.

4. The non-invasive hard plate voltage monitoring system according to claim 1, characterized in that: The driving device is a piezoelectric driving device, comprising: A piezoelectric element, fixed to the cantilever beam, is used to drive the cantilever beam to vibrate when an AC voltage is applied.

5. The non-invasive hard plate voltage monitoring system according to claim 1, characterized in that: The signal processing circuit includes: The field-effect transistor has its gate connected to the sensing electrode, its source grounded, and its drain connected to the power supply through a resistor four. Capacitor 3 is connected between the drain of the field-effect transistor and ground, and is used to detect the voltage signal generated by the change in charge.

6. The non-invasive hard plate voltage monitoring system according to claim 5, characterized in that: The peak-to-peak value of the AC voltage output from capacitor three is proportional to the magnitude of the voltage of the conductor under test.

7. The non-invasive hard plate voltage monitoring system according to claim 1, characterized in that: The system also includes a polarity determination module, used to determine the polarity of the voltage to be measured based on the phase difference between the voltage signal and the drive signal.

8. A non-invasive method for monitoring voltage on a hard plate, characterized in that, The method is applied to the system according to any one of claims 1 to 7, and the method includes the following steps: S1, the induction electrode is driven to vibrate periodically by the vibration mechanism, so that the distance between the induction electrode and the conductor to be measured changes according to a sinusoidal law; S2, detect the charge change on the sensing electrode caused by the capacitance change, and convert the charge change into a voltage signal; S3, calculate the voltage value of the conductor under test by using the peak-to-peak value of the voltage signal.

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