Non-contact measurement of dc voltage polarity circuit and method

Abstract

This application provides a non-contact circuit and method for measuring the positive and negative poles of DC voltage. The circuit includes: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller. The non-contact modulation structure includes a motion modulator and a sensing plate. The standard square wave generation circuit includes an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in sequence. The polarity voltage determination circuit includes a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in sequence. The controller is used to determine the voltage polarity of the conductor of the test plate by comparing the polarity waveform signal with a standard reference waveform signal. This application utilizes the synchronous vibration of an infrared transmitter and the measuring object to accurately acquire the physical changes of the measuring object, then converts the physical changes into a standard waveform signal, and determines the positive and negative poles of the DC voltage through comparison. This method is suitable for live detection scenarios in substation DC control circuits, improving the intelligence level of the distribution network.

Description

Technical Field

[0001] This application relates to the field of intelligent power distribution systems, and is applicable to DC control circuits in power distribution switch control equipment such as switchgear and ring main units, for realizing live state detection. Specifically, it relates to a non-contact circuit and method for measuring the positive and negative poles of DC voltage. Background Technology

[0002] With the accelerated construction of new power systems, substations are continuously transforming towards intelligent and unmanned operation. As the core link of relay protection and switch operation, the DC control circuit's output voltage plate activation / deactivation is a critical aspect of power operation and maintenance. Under normal operating conditions, there is often a DC potential difference of opposite polarity across the two ends of an unactivated output voltage plate. Forcibly activating the voltage plate with an opposite polarity voltage will directly short-circuit the DC positive and negative poles, causing serious safety accidents such as erroneous switch tripping. Accurate voltage polarity detection before voltage plate activation / deactivation is a core prerequisite for ensuring the safety of distribution network operation and maintenance.

[0003] In existing substations, voltage measurement of outlet pressure plates often relies on maintenance personnel using a multimeter in DC mode to measure the DC voltage at the top and bottom of the pressure plate. This method requires maintenance personnel to possess certain professional knowledge, standardized operating procedures, and appropriate measuring tools. Another non-contact DC measurement method, such as the rotating blade non-contact DC voltage measurement scheme, while solving the short circuit and DC grounding problems caused by direct contact, can only measure the voltage on the line and cannot reliably determine the polarity of the DC voltage. Even if the polarity can be measured, after voltage switching on the pressure plate line, operators often need to go to the site to recalibrate the DC voltage polarity before accurately measuring the polarity, which cannot meet the needs of abnormal polarity determination before pressure plate commissioning or decommissioning.

[0004] As power systems transition towards intelligent and unmanned operation, existing measurement solutions are ineffective, hindering the reliability and safety of intelligent distribution switch control equipment. Therefore, a novel non-contact DC voltage polarity detection technology is urgently needed to achieve stable and accurate determination of DC positive and negative polarity while ensuring measurement safety. Summary of the Invention

[0005] In view of this, the purpose of this application is to provide a non-contact circuit and method for measuring the positive and negative poles of DC voltage, so as to improve the problem of poor DC voltage polarity measurement effect in the prior art.

[0006] To address the aforementioned issues, in a first aspect, embodiments of this application provide a non-contact DC voltage positive and negative polarity measurement circuit, applied to the outlet pressure plate of a protective cabinet. The circuit includes: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller. The non-contact modulation structure includes a motion modulator and a sensing plate. The motion modulator is disposed between the test plate wire and the sensing plate. The motion modulator changes the coupling state of the DC electric field of the test plate wire on the sensing plate through periodic movement, thus modulating the DC electric field into an AC electric field. The standard square wave generation circuit includes an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in sequence. The infrared detection circuit is used to detect the motion process of the motion modulator and generate an initial reference waveform signal. The waveform shaping circuit is used to shape and filter the initial reference waveform signal to obtain a shaped reference waveform signal. The hysteresis comparison circuit is used to perform hysteresis comparison on the shaped reference waveform signal and output a standard reference waveform signal to the controller. The polarity voltage determination circuit includes a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in sequence. The voltage sampling circuit is connected to the induction plate and is used to collect the induced signal corresponding to the AC electric field and output an AC voltage signal. The signal amplification circuit is used to amplify and high-pass filter the AC voltage signal to obtain an amplified AC signal. The zero-crossing hysteresis comparison circuit is used to perform zero-crossing detection and waveform inversion on the amplified AC signal and output a polarity waveform signal to the controller. The controller is used to determine the voltage polarity of the conductor of the pressure plate under test by comparing the polarity waveform signal with the standard reference waveform signal.

[0007] In the above implementation process, the periodic movement of the motion modulator in the non-contact modulation structure alters the coupling state of the DC electric field of the test plate wire on the induction plate, thereby modulating the DC electric field of the test plate wire into an AC electric field for signal detection and processing by the standard square wave generation circuit and the polarity voltage judgment circuit. This achieves a non-contact measurement effect, eliminating the need for contact measurement and effectively improving safety during measurement. Furthermore, the infrared detection circuit in the standard square wave generation circuit detects the movement of the motion modulator in the non-contact modulation structure, generating a corresponding initial reference waveform signal. The waveform shaping circuit then shapes and filters the initial reference waveform signal to obtain a shaped reference waveform signal. A hysteresis comparison circuit compares the shaped reference waveform signal with the set reference voltage value to shift the entire shaped reference waveform signal to the left, achieving a hysteresis effect in the square wave output and a steep high and low level, thus outputting a stable standard reference waveform signal to the controller. In actual measurement, the voltage sampling circuit connected to the induction plate in the polarity voltage judgment circuit collects the induced signal generated by the AC electric field during the movement of the moving modulator, and outputs the corresponding AC voltage signal. The AC voltage signal is amplified and high-pass filtered by the signal amplification circuit to obtain an amplified AC signal. The amplified AC signal is then zero-crossing detected and waveform-flipped by the zero-crossing hysteresis comparator circuit to output a polarity waveform signal to the controller. The controller can compare the polarity waveform signal obtained during the measurement process with a determined standard reference waveform signal to determine the voltage polarity of the test plate conductor based on the difference between the waveform signals. It can accurately collect the physical changes of the measured object (i.e., the test plate conductor) based on the synchronous vibration of the infrared beam tube and the measured object, and then convert these physical changes into a standard waveform signal. The positive and negative poles of the DC voltage are determined by comparison, effectively improving the safety, accuracy, and efficiency of substation pressure plate measurement, thereby optimizing the measurement effect of substation pressure plates and meeting the needs of various practical testing scenarios.

[0008] Optionally, the infrared detection circuit includes: an infrared photodiode and a pull-up resistor; The optical path of the infrared photodiode corresponds to the motion change region of the motion modulator. The output pin of the infrared photodiode is connected to one end of the pull-up resistor and the input pin of the waveform shaping circuit, respectively. The other end of the pull-up resistor is connected to the positive terminal of the DC power supply. The infrared photodiode is in a conducting state and a closed state as the motion modulator periodically blocks it. The output pin of the infrared photodiode generates the periodic initial reference waveform signal and outputs it to the waveform shaping circuit. The pull-up resistor is used to adjust the initial reference waveform signal to a high level signal when the motion modulator does not move.

[0009] In the above implementation process, the infrared detection circuit may include an infrared photodiode capable of detecting motion and a pull-up resistor for adjusting the waveform signal. The optical path of the infrared photodiode corresponds to the motion change region of the motion modulator. Since the motion modulator has different motion states, different motion states will have different effects on the infrared photodiode. Therefore, the infrared photodiode can be in a conducting state and a closed state based on the periodic blocking motion of the motion modulator, and based on the conducting state and the closed state, it generates a periodic initial reference waveform signal at its output pin to output the initial reference waveform signal to the waveform shaping circuit. In order to reduce the inaccuracy of the initial reference waveform signal when the motion modulator does not move, a pull-up resistor is also provided, with one end connected to the output pin of the infrared photodiode and the other end connected to the positive terminal of the DC power supply. Through the pull-up resistor, the initial reference waveform signal is adjusted to a high level signal when the motion modulator does not move, effectively reducing the false triggering of the standard waveform of the initial reference waveform signal.

[0010] Optionally, the waveform shaping circuit includes: a first operational amplifier and a first feedback resistor; The non-inverting input pin of the first operational amplifier is connected to the output pin of the infrared photodiode. The two ends of the first feedback resistor are respectively connected to the inverting input pin and the output pin of the first operational amplifier. The output pin of the first operational amplifier is connected to the hysteresis comparator circuit.

[0011] In the above implementation process, the waveform shaping circuit can be equipped with a first operational amplifier and a first feedback resistor. The non-inverting input pin of the first operational amplifier is connected to the output pin of the infrared photodiode to receive the initial reference waveform signal sent by the infrared photodiode. The two ends of the first feedback resistor are connected to the inverting input pin and the output pin of the first operational amplifier, respectively, to achieve negative feedback. The output pin of the first operational amplifier is connected to a hysteresis comparator circuit, which can filter out interference signals such as waveform glitches in the initial reference waveform signal and obtain a shaped reference waveform signal with a relatively regular waveform shape, which is then output to the hysteresis comparator circuit.

[0012] Optionally, the hysteresis comparator circuit includes: a hysteresis comparator and a voltage divider resistor; The reference pin of the hysteresis comparator is connected to the voltage divider resistor and generates a reference voltage value based on the voltage divider resistor; The input pin of the hysteresis comparator is connected to the output pin of the first operational amplifier. The hysteresis comparator is used to compare the reference voltage value and the shaped reference waveform signal, and output the standard reference waveform signal to the controller.

[0013] In the above implementation, the hysteresis comparator circuit includes a hysteresis comparator and a voltage divider resistor. The reference pin of the hysteresis comparator is connected to the voltage divider resistor to determine the reference voltage value corresponding to the hysteresis comparison. The input pin of the hysteresis comparator is connected to the output pin of the first operational amplifier. The hysteresis comparator can perform a hysteresis comparison based on the determined reference voltage value and the received shaped reference waveform signal, thereby shifting the output of the shaped reference waveform signal to the left based on the reference voltage value. This achieves a hysteresis square wave output with steep high and low levels, resulting in a standard reference waveform signal that is output to the controller. The hysteresis comparator circuit's output inertia, strong anti-interference capability, and fast response speed can eliminate input oscillations and jitter, reducing reference waveform distortion caused by unstable operation of the non-contact modulation structure. This significantly improves the square wave stability of the standard reference waveform signal, increasing the fault tolerance probability for subsequent waveform comparison.

[0014] Optionally, the voltage sampling circuit includes: a sampling resistor and a sampling capacitor; The sampling resistor and the sampling capacitor are connected in parallel. One end of the sampling resistor and one end of the sampling capacitor are connected to the sensing plate. The other end of the sampling resistor and the other end of the sampling capacitor are both grounded. The sampling resistor is used to collect the induced current of the AC electric field during the motion of the motion modulator, and convert the induced current into an induced voltage to output the AC voltage signal; The sampling capacitor is used to increase the induced voltage.

[0015] In the above implementation process, the voltage sampling circuit may include a sampling resistor and a sampling capacitor connected in parallel. One end of the sampling resistor and one end of the sampling capacitor are connected to the induction plate, and the other ends of the sampling resistor and the sampling capacitor are grounded. The sampling resistor collects the induced current signal of the AC electric field during the motion of the motion modulator, converts the induced current into an induced voltage, and outputs an AC voltage signal. Considering the weak characteristics of the induced voltage, in order to facilitate signal processing, the induced voltage at the front end can be increased by the sampling capacitor to achieve amplification and filtering, thereby increasing the voltage amplitude of the AC voltage signal.

[0016] Optionally, the signal amplification circuit includes: a non-inverting amplifier and a high-pass filter; The non-inverting amplifier includes: a precision operational amplifier, a second feedback resistor, and a first capacitor. The non-inverting input pin of the precision operational amplifier is connected to the voltage sampling circuit. The two ends of the second feedback resistor and the first capacitor are respectively connected to the inverting input pin and the output pin of the precision operational amplifier. The high-pass filter includes a high-pass filter resistor and a high-pass filter capacitor. The first end of the high-pass filter resistor is connected to the inverting input pin of the precision operational amplifier, the second end of the high-pass filter resistor is connected to the first end of the high-pass filter capacitor, and the second end of the high-pass filter capacitor is grounded. The in-phase amplifier is used to amplify the AC voltage signal to obtain an amplified AC signal. The high-pass filter is used to suppress interference signals in the amplified AC signal.

[0017] In the above implementation process, the signal amplification circuit may include a non-inverting amplifier and a high-pass filter. The non-inverting amplifier, consisting of a precision operational amplifier, a second feedback resistor, and a first capacitor, has a magnification factor of 6 to further amplify the received AC voltage signal and obtain an amplified AC signal. Considering that during the signal amplification process, power frequency interference signals in the environment may also be coupled to the front end of the voltage sampling circuit through the movement of the motion modulator, a high-pass filter including a high-pass filter resistor and a high-pass filter capacitor can also be set to filter the amplified AC signal, suppress the power frequency interference signal in the amplified interference signal, and improve the accuracy of the amplified AC signal.

[0018] Optionally, the zero-crossing hysteresis comparator circuit includes: a second operational amplifier and a third feedback resistor; The non-inverting input pin of the second operational amplifier is connected to the output pin of the precision operational amplifier; The two ends of the third feedback resistor are respectively connected to the non-inverting input pin and the output pin of the second operational amplifier; The output pin of the second operational amplifier is connected to the controller; The reference input pin of the second operational amplifier is grounded, with 0V as the comparison reference level. When the amplified AC signal passes through 0V, the second operational amplifier flips the waveform of the amplified AC signal and outputs the polarity waveform signal with the same frequency and phase to the controller.

[0019] In the above implementation, the zero-crossing hysteresis comparator circuit can include a second operational amplifier and a third feedback resistor. The non-inverting input pin of the second operational amplifier is connected to the output pin of the precision operational amplifier. The two ends of the third feedback resistor are connected to the non-inverting input pin and the output pin of the second operational amplifier, respectively, to achieve positive feedback. The reference input pin of the second operational amplifier is grounded, and the output pin is connected to the controller. Thus, the second operational amplifier can use 0V as the comparison reference level. When the received amplified AC signal crosses 0V, the second operational amplifier can reverse the waveform of the amplified AC signal and output a waveform signal with the same frequency and phase to the controller as the polarity waveform signal for voltage polarity determination. A specific zero-crossing hysteresis comparator can be constructed based on the second operational amplifier and the third feedback resistor, taking into account both zero-crossing detection and noise immunity. The output inertia, strong anti-interference capability, and fast response speed of the zero-crossing hysteresis comparator are used to eliminate oscillations and jitters at the input end, resulting in higher accuracy of the positive / negative voltage polarity waveform signal output.

[0020] Optionally, the non-contact DC voltage positive and negative terminal measurement circuit further includes: an output voltage amplitude determination circuit; The output voltage amplitude determination circuit is connected to the polarity voltage determination circuit; The output voltage amplitude determination circuit includes: a third operational amplifier, a differential operational amplifier, a diode device, a fourth feedback resistor, two input resistors, and a low-pass filter; The inverting input pin of the third operational amplifier is connected to the non-inverting input pin of the differential operational amplifier. The non-inverting input pin of the third operational amplifier is grounded. The two ends of the diode device are respectively connected to the output pin of the third operational amplifier and the inverting input pin of the third operational amplifier. The conduction direction of the diode device is from the output pin of the third operational amplifier to the inverting input pin of the third operational amplifier. The two input resistors are respectively connected to the non-inverting input pin and the inverting input pin of the differential operational amplifier, and the two ends of the fourth feedback resistor are respectively connected to the inverting input pin and the output pin of the differential operational amplifier. The low-pass filter includes a low-pass filter resistor and a low-pass filter capacitor; the first end of the low-pass filter resistor is connected to the output pin of the differential operational amplifier, the second end of the low-pass filter resistor is connected to the first end of the low-pass filter capacitor and the controller, and the second end of the low-pass filter capacitor is grounded; The third operational amplifier is used to flip the negative half-axis portion of the sine wave of the amplified AC signal to the positive half-axis portion to obtain a flipped signal, and input the flipped signal into the non-inverting input pin of the differential operational amplifier. The differential operational amplifier is used to differentially amplify the flip signal by one time and then output the DC voltage amplitude signal of the test plate wire to the controller.

[0021] In the above implementation process, due to the change in voltage level on the tested conductor, the positive and negative charges also change during the detection process. The polarity waveform signal output by the polarity voltage judgment circuit includes the amplitude and phase of the DC voltage. In order to measure the amplitude of the DC voltage, the non-contact DC voltage polarity measurement circuit can also be equipped with an output voltage amplitude judgment circuit. The output voltage amplitude judgment circuit is connected to the polarity voltage judgment circuit and can receive the polarity waveform signal output by the polarity voltage judgment circuit. The output voltage amplitude judgment circuit can include a third operational amplifier, a differential operational amplifier, a diode device, a fourth feedback resistor, two input resistors, and a low-pass filter. The third operational amplifier can flip the negative half-axis part of the amplified AC signal sine wave to the positive half-axis part to obtain the flipped signal. The flipped signal is input to the non-inverting input pin of the differential operational amplifier, which differentially amplifies the flipped signal by one time and outputs the DC voltage amplitude signal of the conductor of the test plate. The low-pass filter filters out interference signals, thereby achieving a high-precision measurement effect of voltage amplitude.

[0022] Optionally, the motion modulator is a rotary blade mechanism or a vibrating capacitor mechanism; The rotating blade mechanism includes a rotating blade with a hollowed-out area and a driving component. The driving component drives the rotating blade to rotate at a constant speed, periodically blocking the electric field between the wire of the pressure plate to be tested and the induction plate, thereby achieving electric field modulation. The vibration capacitor mechanism includes a vibration plate and a driving component. The driving component drives the vibration plate to reciprocate, periodically changing the equivalent capacitance between the test plate wire and the sensing plate, thereby achieving electric field modulation.

[0023] In the above implementation process, the motion modulator in the non-contact modulation structure may include a rotating blade mechanism or a vibrating capacitor mechanism, which can modulate the DC electric field of the conductor under test into an AC electric field through its own movement, and cause the infrared photodiode to change periodically through its own movement, without making substantial contact with the conductor under test.

[0024] Secondly, embodiments of this application also provide a non-contact method for measuring the positive and negative poles of DC voltage. The method is applied to a non-contact circuit for measuring the positive and negative poles of DC voltage. The circuit includes: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller. The method includes: The non-contact modulation structure includes a motion modulator and a sensing plate. The motion modulator is disposed between the test plate wire and the sensing plate. The motion modulator changes the coupling state of the DC electric field of the test plate wire on the sensing plate through periodic movement. The non-contact modulation structure modulates the DC electric field of the test plate wire into an AC electric field. The standard square wave generation circuit includes: an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in series. The infrared detection circuit detects the motion process of the motion modulator and generates an initial reference waveform signal. The waveform shaping circuit shapes and filters the initial reference waveform signal to obtain a shaped reference waveform signal. The hysteresis comparison circuit performs a hysteresis comparison on the shaped reference waveform signal and outputs a standard reference waveform signal to the controller. The polarity voltage determination circuit includes: a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in series. The voltage sampling circuit is connected to the induction plate and collects the induced signal corresponding to the AC electric field, outputting an AC voltage signal. The signal amplification circuit amplifies and high-pass filters the AC voltage signal to obtain an amplified AC signal. The zero-crossing hysteresis comparison circuit performs zero-crossing detection and waveform inversion on the amplified AC signal, outputting a polarity waveform signal to the controller. The controller compares the polarity waveform signal with the standard reference waveform signal to determine the voltage polarity of the conductor of the pressure plate under test.

[0025] In the above implementation process, the periodic movement of the motion modulator in the non-contact modulation structure alters the coupling state of the DC electric field of the test plate wire on the induction plate, thereby modulating the DC electric field of the test plate wire into an AC electric field for signal detection and processing by the standard square wave generation circuit and the polarity voltage judgment circuit. This achieves a non-contact measurement effect, eliminating the need for contact measurement and effectively improving safety during measurement. Furthermore, the infrared detection circuit in the standard square wave generation circuit detects the movement of the motion modulator in the non-contact modulation structure, generating a corresponding initial reference waveform signal. The waveform shaping circuit then shapes and filters the initial reference waveform signal to obtain a shaped reference waveform signal. A hysteresis comparison circuit compares the shaped reference waveform signal with the set reference voltage value to shift the entire shaped reference waveform signal to the left, achieving a hysteresis effect in the square wave output and a steep high and low level, thus outputting a stable standard reference waveform signal to the controller. In the actual measurement process, the voltage sampling circuit connected to the induction plate in the polarity voltage judgment circuit collects the induced signal generated by the AC electric field during the movement of the moving modulator, and outputs the corresponding AC voltage signal. The AC voltage signal is amplified and high-pass filtered by the signal amplification circuit to obtain the amplified AC signal. The zero-crossing hysteresis comparator circuit performs zero-crossing detection and waveform inversion on the amplified AC signal to output the polarity waveform signal to the controller. The controller can compare the polarity waveform signal during the measurement process with the determined standard reference waveform signal, and thus determine the voltage polarity of the conductor of the pressure plate under test based on the difference between the waveform signals.

[0026] Optionally, determining the voltage polarity of the test plate wire by comparing the polarity waveform signal and the standard reference waveform signal through the controller includes: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If the polarity waveform signal is high-level within a preset window period after the falling edge is generated, the test plate wire is determined to be positive polarity voltage.

[0027] In the above implementation process, the controller can use the falling edge of the standard reference waveform signal within one cycle as the reference point for polarity determination. When the polarity waveform signal acquired within the preset window period after the falling edge is a high level potential, the polarity waveform signal is the same as the polarity of the reference waveform signal and the waveform is ahead, which is a positive voltage waveform. Therefore, the DC voltage on the current test plate wire is determined to be a positive polarity voltage.

[0028] Optionally, determining the voltage polarity of the test plate wire by comparing the polarity waveform signal and the standard reference waveform signal through the controller includes: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If the polarity waveform signal is low-level within a preset window period after the falling edge is generated, the test plate wire is determined to be negative polarity voltage.

[0029] In the above implementation process, the controller can use the falling edge of the standard reference waveform signal within one cycle as the reference point for polarity determination. When the polarity waveform signal acquired within the preset window period after the falling edge is a low level potential, the polarity of the polarity waveform signal is opposite to that of the reference waveform signal and the waveform is ahead, which is a negative voltage waveform. Therefore, the DC voltage on the current test plate wire is determined to be a negative polarity voltage.

[0030] In summary, the embodiments of this application provide a non-contact circuit and method for measuring the positive and negative poles of DC voltage. Based on the synchronous vibration of the infrared photodiode and the measuring object, i.e., the conductor of the pressure plate under test, the physical changes of the measuring object can be accurately collected. These physical changes are then converted into standard waveform signals, and the positive and negative poles of the DC voltage are determined by comparison. This method can effectively replace the traditional manual contact measurement scheme, meet the requirements of live detection and anti-misoperation of DC control circuits in substations, and is compatible with the intelligent and unattended upgrade direction of intelligent power distribution switch control equipment. Attached Figure Description

[0031] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This application provides a schematic diagram of a non-contact DC voltage measurement circuit for embodiments of the present application. Figure 2 A schematic diagram of the specific structure of a standard square wave generating circuit provided in this application embodiment; Figure 3 This is a schematic diagram of a polarity voltage determination circuit provided in an embodiment of this application; Figure 4 This is a schematic diagram of an output voltage amplitude determination circuit provided in an embodiment of this application; Figure 5 A flowchart illustrating a non-contact method for measuring the positive and negative terminals of DC voltage, provided in an embodiment of this application; Figure 6 A detailed flowchart of step S240 provided for an embodiment of this application; Figure 7 A waveform comparison diagram of a positive voltage provided for an embodiment of this application; Figure 8 This is a waveform comparison diagram of a negative polarity voltage provided in an embodiment of this application.

[0033] Icons: 110 - Non-contact modulation structure; 120 - Standard square wave generation circuit; 130 - Polarity voltage judgment circuit; 140 - Controller; A - Wire of the pressure plate under test; 111 - Motion modulation component; 112 - Sensing electrode plate; 113 - Driving component; 121 - Infrared detection circuit; 122 - Waveform shaping circuit; 123 - Hysteresis comparison circuit; 131 - Voltage sampling circuit; 132 - Signal amplification circuit; 133 - Zero-crossing hysteresis comparison circuit; U2 - Infrared photodiode; R2 - Pull-up resistor; U3 - First operational amplifier; R7 - Second operational amplifier; Feedback resistor; U1 - Hysteresis comparator; R12 - Sampling resistor; C10 - Sampling capacitor; U4 - Precision operational amplifier; R15 - Second feedback resistor; C14 - First capacitor; R14 - High-pass filter resistor; C13 - High-pass filter capacitor; 1321 - High-pass filter; U5 - Second operational amplifier; R13 - Third feedback resistor; U2A - Third operational amplifier; U2B - Differential operational amplifier; D1 - Diode device; R20 - Fourth feedback resistor; R21 - Low-pass filter resistor; C17 - Low-pass filter capacitor. Detailed Implementation

[0034] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of the embodiments of this application.

[0035] Against the backdrop of the comprehensive construction of new power systems and the upgrading of substations to unmanned and intelligent operation, the DC control circuit output pressure plate, as a core control node for preventing misoperation of relay protection, requires pre-commissioning polarity voltage detection as a necessary preliminary procedure to ensure the safety of power grid equipment and maintenance personnel. The protection output pressure plate acts as a "switch" for tripping or closing circuits. Normally, when not in operation, if the internal contacts of the protection device are closed, one end of the pressure plate will be connected to the DC negative terminal (commonly -110V or -220V), while the other end will be connected to the DC positive terminal (+110V or +220V) through a load such as a trip coil, thus creating a voltage difference between the two ends of the pressure plate. This potential difference is the normal physical state of the circuit. Operation is only permitted when there is no voltage or the voltage is of the same polarity at both ends of the pressure plate; forcibly engaging the circuit with a voltage of opposite polarity is equivalent to directly short-circuiting the positive and negative terminals, causing a sudden current flow through the trip coil and resulting in a false trip of the switch.

[0036] In existing substation outlet voltage measurement solutions, using a multimeter for contact measurement requires prior knowledge of the current DC voltage range on the outlet circuit and manual switching of the measurement range. Using continuity or low-impedance circuit settings can cause short circuits, triggering malfunctions and causing outlet circuit malfunctions. The multimeter's internal contact resistance voltage divider method is susceptible to short circuits, which can lead to grounding and tripping of protection devices. While non-contact measurement methods address short circuits and DC grounding issues caused by direct contact, they lack accurate polarity determination, leading to incorrect outlet circuit closures. In short, existing solutions only measure the presence or absence of DC voltage or determine its polarity, resulting in low safety, low accuracy, and an inability to precisely determine polarity, leading to poor outlet circuit measurement performance and failing to meet practical application requirements.

[0037] To address the aforementioned issues, this application provides a non-contact circuit and method for measuring the positive and negative poles of DC voltage. Based on the synchronous vibration of an infrared beam transmitter and the measuring object (i.e., the conductor of the test plate), it accurately acquires the physical changes of the measuring object, converts these physical changes into standard waveform signals, and determines the positive and negative poles of the DC voltage through comparison. This effectively improves the safety, accuracy, and efficiency of substation test plate measurements, thereby optimizing the measurement results and meeting the needs of various practical testing scenarios. It can be embedded into switchgear and ring main unit live-line detection units, providing stable digital detection data for unattended operation and maintenance and anti-misoperation forced interlocking in new power systems, comprehensively improving the inherent safety, polarity identification accuracy, and field adaptability of substation test plate detection.

[0038] Please see Figure 1 , Figure 1 This is a schematic diagram of a non-contact DC voltage positive and negative polarity measurement circuit provided in an embodiment of this application. The non-contact DC voltage positive and negative polarity measurement circuit may include: a non-contact modulation structure 110, a standard square wave generation circuit 120, a polarity voltage judgment circuit 130, and a controller 140.

[0039] The non-contact modulation structure 110 includes a motion modulator 111 and a sensing plate 112. The motion modulator 111 is disposed between the test plate wire A and the sensing plate 112. The motion modulator 111 changes the coupling state of the DC electric field of the test plate wire A on the sensing plate 112 through periodic movement, modulating the DC electric field into an AC electric field. The non-contact modulation structure 110 can modulate the DC electric field of the test plate wire into an AC electric field based on its own movement, so that the standard square wave generation circuit 120 and the polarity voltage judgment circuit 130 can perform signal detection and processing. It can achieve non-contact measurement effect, eliminating the need for contact measurement and effectively improving the safety during measurement.

[0040] Optionally, the motion modulator 111 in the non-contact modulation structure 110 may include a rotating blade mechanism or a vibrating capacitor mechanism, which can modulate the DC electric field of the test plate wire A into an AC electric field through its own movement, and cause the infrared photodiode to change periodically through its own movement, without making substantial contact with the test plate wire A.

[0041] For example, the rotating blade mechanism includes a rotating blade with a hollowed-out area and a driving member 113. The driving member 113 drives the rotating blade to rotate at a constant speed, periodically blocking the electric field between the test plate wire and the sensing electrode, thereby achieving electric field modulation. The vibration capacitor mechanism includes a vibration electrode and a driving member 113. The driving member 113 drives the vibration electrode to reciprocate, periodically changing the equivalent capacitance between the test plate wire and the sensing electrode, thereby achieving electric field modulation.

[0042] For example, the rotating blade structure may include a motion modulator 111 having a solid region and a clearance region. Figure 1 The motion modulator 111 shown is a blade structure, and the sensing electrode 112 has the same shape and structure as the motion modulator 111. The motion modulator 111 can be configured with a solid-hollow-solid alternating structure, and the solid areas can be configured with various shapes, such as triangles or sectors, so that the rotation of the motion modulator 111 affects the charge around the conductor A of the pressure plate under test, thereby generating an alternating electric field between it and the sensing electrode 112. A driving element 113 (such as a motor or other devices) can also be provided to drive the motion modulator 111 to rotate. The driving element 113 can drive the motion modulator 111 to rotate at a constant speed in a direction parallel to the sensing electrode 112, and can also control the starting position, ending position and rotation speed of the motion modulator 111, further improving the stability and effectiveness of the standard reference waveform signal.

[0043] For example, the vibrating capacitor mechanism may include a back-and-forth vibrating or up-and-down vibrating electrode plate, and a sensing electrode plate 112, so as to affect the charge around the test pressure plate wire A through the vibrating electrode plate, thereby generating an alternating electric field between the electrode plate and the sensing electrode plate 112.

[0044] It should be noted that the embodiments provided in this application take the non-contact modulation structure 110 as a rotating blade mechanism as an example for illustration. The implementation principle of the corresponding embodiment of the vibration capacitor mechanism is similar to that of the non-contact modulation structure 110, and the embodiments of the vibration capacitor mechanism will not be described in detail.

[0045] Optionally, the standard square wave generation circuit 120 includes an infrared detection circuit 121, a waveform shaping circuit 122, and a hysteresis comparison circuit 123 connected in sequence. The infrared detection circuit 121 is used to detect the motion process of the motion modulator 111 and generate an initial reference waveform signal. The waveform shaping circuit 122 is used to shape and filter the initial reference waveform signal to obtain a shaped reference waveform signal. The hysteresis comparison circuit 123 is used to perform hysteresis comparison on the shaped reference waveform signal to shift the shaped reference waveform signal to the left as a whole, so as to achieve a square wave output hysteresis and a steep high and low level effect, obtain a stable standard reference waveform signal, and output the standard reference waveform signal to the controller 140.

[0046] Optionally, the polarity voltage determination circuit 130 includes a voltage sampling circuit 131, a signal amplification circuit 132, and a zero-crossing hysteresis comparison circuit 133 connected in sequence. The voltage sampling circuit 131 is connected to the induction plate 112 and is used to collect the induced signal corresponding to the AC electric field and output an AC voltage signal. The signal amplification circuit 132 is used to amplify and high-pass filter the AC voltage signal to obtain an amplified AC signal. The zero-crossing hysteresis comparison circuit 133 is used to perform zero-crossing detection and waveform reversal on the amplified AC signal and output a polarity waveform signal to the controller 140. The controller 140 can compare the polarity waveform signal with the standard reference waveform signal and determine the voltage polarity of the DC voltage on the conductor of the test plate based on the difference between the waveform signals. The overall circuit of this application adopts a fully electrically isolated non-contact architecture, which eliminates the need for manual range switching and on-site polarity calibration. It can be directly integrated into switch cabinets and ring main units. One set of hardware synchronously completes the DC voltage amplitude quantization and polarity determination, providing standardized digital criteria for intelligent power distribution integrated anti-misoperation interlocking.

[0047] Optionally, the initial reference waveform signal, the shaping reference waveform signal, the standard reference waveform signal, and the polarity waveform signal can all be corresponding periodic square wave signals.

[0048] For example, symmetrical rotating blades are detected by an infrared photodiode. When the blades move at a constant speed, the infrared photodiode on the sensing plate 112 detects the blade rotation and generates a blocking-exposure-blocking-exposure motion trajectory. This generates an initial reference waveform signal with a duty cycle of 50% at the signal acquisition end of the sensing plate 112. This signal is affected by the motor speed and the flatness of the blade installation. Therefore, the interference signal on the square wave signal can be filtered out by the waveform shaping circuit 122. The square wave distortion caused by uneven blade installation or loose blades during rotation can be filtered out by the hysteresis comparison circuit 123. The standard square wave can also be shaped into a square wave with a steeper falling or rising edge, which is convenient for comparison with subsequent polarity waveform signals.

[0049] For example, controller 140 can be a Microcontroller Unit, i.e., a device such as an MCU.

[0050] Optionally, please refer to Figure 2 , Figure 2 This is a schematic diagram of the specific structure of a standard square wave generating circuit 120 provided in an embodiment of this application.

[0051] Optionally, the infrared detection circuit 121 may include an infrared photodiode U2 and a pull-up resistor R2. The optical path of the infrared photodiode U2 corresponds to the motion change region of the motion modulator 111. The output pin of the infrared photodiode U2 is connected to one end of the pull-up resistor R2 and the input pin of the waveform shaping circuit 122, respectively; the other end of the pull-up resistor R2 is connected to the positive terminal of the DC power supply. The infrared photodiode U2 is in a conducting state and a closed state as the motion modulator 111 periodically blocks and moves. A periodic initial reference waveform signal is generated at the output pin of the infrared photodiode U2 and output to the waveform shaping circuit 122; the pull-up resistor R2 is used to adjust the initial reference waveform signal to a high-level signal when the motion modulator 111 is not moving.

[0052] Since the motion modulator 111 has different motion states, these different motion states will have different effects on the infrared photodiode U2. Therefore, the optical path of the infrared photodiode U2 is set within the motion change area of ​​the motion modulator 111. The infrared photodiode U2 is in a conducting state and a closed state based on the periodic blocking motion of the motion modulator 111, and a periodic initial reference waveform signal is generated at the output pin of the infrared photodiode U2 based on the conducting state and the closed state. In order to reduce the inaccuracy of the initial reference waveform signal when the motion modulator 111 does not move, a pull-up resistor R2 is also provided, with one end connected to the output pin of the infrared photodiode U2 and the other end connected to the positive terminal of the DC power supply. Through the pull-up resistor R2, when the motion modulator 111 does not move, the initial reference waveform signal is adjusted to a high level signal, effectively reducing the false triggering of the standard waveform of the initial reference waveform signal.

[0053] For example, when pin 2 (DRVCTR2) of the infrared photodiode U2 is low, after the symmetrical blades in the rotating blade mechanism rotate, the infrared photodiode U2 cycles through on-off-on-off, thereby generating a periodic square wave signal at pin 3 (i.e., the output pin) as the initial reference waveform signal. Pin 3 of the infrared photodiode U2 is connected to a pull-up resistor R2, and the other end of the pull-up resistor R2 is connected to Vcc, i.e., the positive terminal of the DC power supply. The pull-up resistor R2 can adjust the initial reference waveform signal input to the waveform shaping circuit 122 to a high level when blade rotation is not detected, i.e., when the non-contact modulation structure 110 is not moving, to prevent the standard waveform from being generated incorrectly. Pin 1 of the infrared photodiode U2 is connected to Vcc through resistor R4, and pin 4 is grounded. Resistor R4 can act as a current-limiting resistor to limit the adverse situation where excessive current in the infrared photodiode U2 could cause it to burn out.

[0054] Optionally, the waveform shaping circuit 122 may include: a first operational amplifier U3 and a first feedback resistor R7; the non-inverting input pin of the first operational amplifier U3 is connected to the output pin of the infrared photodiode U2, the two ends of the first feedback resistor R7 are respectively connected to the inverting input pin and the output pin of the first operational amplifier U3, and the output pin of the first operational amplifier U3 is connected to the hysteresis comparator circuit 123. The first operational amplifier U3 can filter out interference signals such as waveform glitches in the initial reference waveform signal, and obtain a shaped reference waveform signal with a more regular waveform shape.

[0055] For example, the first operational amplifier U3 and the first feedback resistor R7 can form a follower as a waveform shaping circuit 122 to filter out interference signals (such as waveform glitches) on the initial reference waveform signal. The waveform shaping circuit 122 may also include capacitors C1 and C2, with one end of capacitors C1 and C2 grounded and the other end connected to Vcc, which can serve as bypass capacitors to ensure that the first operational amplifier U3 inside the waveform shaping circuit 122 outputs a clean waveform with steep edges, no jitter, and no glitches. The first feedback resistor R7 is connected to pin 1 (output pin) and pin 4 (inverting input pin) of the first operational amplifier U3 to serve as a negative feedback resistor, which can compress the very large open-loop gain of the first operational amplifier U3 into a controllable closed-loop gain, thereby ensuring that the output waveform is stable and undistorted.

[0056] Optionally, the hysteresis comparator circuit 123 may include a hysteresis comparator U1 and a voltage divider resistor. The reference pin of the hysteresis comparator U1 is connected to the voltage divider resistor, and a reference voltage value is generated based on the voltage divider resistor. The input pin of the hysteresis comparator U1 is connected to the output pin of the first operational amplifier U3. The hysteresis comparator U1 is used to compare the reference voltage value with the shaped reference waveform signal to obtain a standard reference waveform signal, and outputs the standard reference waveform signal to the controller 140. The hysteresis comparator circuit 123 can eliminate input oscillations and jitter based on its output inertia, strong anti-interference capability, and fast response speed, thereby reducing the distortion of the reference waveform caused by the unstable operation of the non-contact modulation structure 110, greatly improving the square wave stability of the standard reference waveform signal, and increasing the fault tolerance probability for subsequent waveform comparison.

[0057] For example, in the hysteresis comparator circuit 123, a reference voltage value VREF of 1 / 2*VCC is generated at pin 4 of the hysteresis comparator U1 through the two voltage divider resistors R5 and R8. This reference voltage value VREF is compared with the shaped reference waveform signal transmitted from the waveform shaping circuit 122 at pin 3 (input pin) of the hysteresis comparator U1. This reference voltage value VREF can shift the output of the shaped reference waveform signal to the left, achieving the effect of hysteresis in the square wave output and steep high and low levels. The hysteresis comparator circuit 123 may also include capacitors C3, C4, and C5, and resistors R1, R3, R5, R6, and R8. Capacitors C3, C4, and C5 are grounded at one end and connected to Vcc at the other, serving as bypass capacitors to ensure that the hysteresis comparator U1 outputs a clean waveform with steep edges, no jitter, and no glitches. Resistor R3 is placed between the output pin of the waveform shaping circuit 122 and the input pin of the hysteresis comparator U1. Resistors R3, R10, and R11 are the input resistors matching the first operational amplifier U3, and all three have the same impedance. Resistor R1 connects the output pin of the hysteresis comparator U1 to Vcc, enabling it to pull the output pin to a defined high level (Vcc) when the output stage of the hysteresis comparator U1 is cut off (turned off), thereby generating a standard, complete digital square wave signal for output to the subsequent circuitry. Resistor R6 is the positive feedback resistor for hysteresis comparator U1, and resistors R5 and R8 are the negative feedback resistors for hysteresis comparator U1. When there is no voltage waveform input, the output pin of hysteresis comparator U1 is 0V to improve the output accuracy of the op-amp. The formula for calculating hysteresis comparator U1 is: Vcc = 3.3V. make , and thus Threshold voltage at the input terminal = The waveform at pin 3 of the hysteresis comparator U1 is similar to... Threshold comparison is performed to achieve the purpose of square wave hysteresis comparison output.

[0058] Optionally, in Figure 2 In the illustrated embodiment, the parameter ranges for each device may include: R2 and R4 with a range of 1K to 20K; R7 with a range of 1K to 47K; R1 and R3 with a range of 100K to 576K; and R5, R6, and R8 with a range of 1M to 2M. The hysteresis comparator U1 can be a low-noise TLV3401IDBVT operational amplifier.

[0059] Optionally, please refer to Figure 3 , Figure 3 This is a schematic diagram of a polarity voltage determination circuit 130 provided in an embodiment of this application.

[0060] The voltage sampling circuit 131 may include a sampling resistor R12 and a sampling capacitor C10. The sampling resistor R12 and the sampling capacitor C10 are connected in parallel. One end of the sampling resistor R12 and one end of the sampling capacitor C10 are both connected to the induction plate 112, and the other ends of the sampling resistor R12 and the sampling capacitor C10 are both grounded. The sampling resistor R12 is used to collect the induced current of the AC electric field during the movement of the motion modulator 111, and converts the induced current into an induced voltage, outputting an AC voltage signal. The sampling capacitor C10 is used to amplify the induced voltage. Considering the weak characteristics of the induced voltage, to facilitate signal processing, the sampling capacitor C10 can be used to amplify and filter the induced voltage at the front end, thereby increasing the voltage amplitude of the AC voltage signal.

[0061] Optionally, due to the symmetry of the blades and sensing plate 112 in the rotating blade mechanism, an AC electric field is superimposed on the sensing plate 112 during the rotation of the blades (PAD1, PAD2, and PAD3). The stronger the superimposed AC electric field, the weak AC voltage signal at the sampling resistor R12 will be generated. The front-end sampling resistor R12 samples the induced current and performs I / V conversion to convert it into the corresponding induced voltage before subsequent amplification and filtering. The impedance of the parallel connection of the sampling resistor R12 and the sampling capacitor C10 increases the front-end induced voltage, thereby increasing the amplitude of the sensor output voltage. Resistor R9 is placed between the rotating blade and the sampling resistor R12, and resistor R9 can filter out high-frequency interference signals generated by the rotating blade. The induced current on the sensing plate 112 is an AC signal with a certain frequency of approximately 350Hz; therefore, the influence of the capacitive reactance of the sampling capacitor C10 needs to be considered, i.e., the sampling impedance calculation formula is: ; However, based on the actual debugging situation, the amplitude of the interference signal (such as 50Hz power frequency interference) will also increase accordingly after the sampling impedance increases. Therefore, the resistance value of the sampling resistor R12 cannot be too large. The final parameters of each device in the voltage sampling circuit 131 can include: R9=1MΩ, R12=10MΩ, C10=220pF.

[0062] Optionally, the signal amplification circuit 132 may include a non-inverting amplifier and a high-pass filter 1321.

[0063] The non-inverting amplifier includes a precision operational amplifier U4, a second feedback resistor R15, and a first capacitor C14. The non-inverting input pin of the precision operational amplifier U4 is connected to the voltage sampling circuit 131, and the two ends of the second feedback resistor R15 and the first capacitor C14 are respectively connected to the inverting input pin and the output pin of the precision operational amplifier U4. The high-pass filter 1321 includes a high-pass filter resistor R14 and a high-pass filter capacitor C13. The first end of the high-pass filter resistor R14 is connected to the inverting input pin of the precision operational amplifier U4, the second end of the high-pass filter resistor R14 is connected to the first end of the high-pass filter capacitor C13, and the second end of the high-pass filter capacitor C13 is grounded.

[0064] A non-inverting amplifier with a gain of 6 is formed by a precision operational amplifier U4, a second feedback resistor R15, and a first capacitor C14 to further amplify the received AC voltage signal to obtain an amplified AC signal. Considering that during the signal amplification process, power frequency interference signals in the environment will also be coupled to the front end of the voltage sampling circuit 131 through the movement of the motion modulator 111, a high-pass filter 1321 can also be set to filter the amplified AC signal to suppress the power frequency interference signal in the amplified interference signal and improve the accuracy of the amplified AC signal.

[0065] For example, the AC signal passes through resistor R10, precision operational amplifier U4, second feedback resistor R15, and first capacitor C14 to form a non-inverting amplifier with a gain of 6. During signal amplification, a 50Hz power frequency interference signal in the environment will also couple to the sampling front end through the rotating blades. Therefore, a high-pass filter 1321, composed of a high-pass filter resistor R14 and a high-pass filter capacitor C13, is added to the feedback loop of the amplifier circuit to suppress the 50Hz power frequency interference signal. The cutoff frequency of the high-pass filter 1321 is: Calculation formula: ; Formula for calculating the comparison factor of the non-inverting amplifier composed of precision operational amplifier U4: =(1+ )× ;in, This refers to the output voltage of the precision operational amplifier U4. This is the input voltage.

[0066] For example, the signal amplification circuit 132 may also include bypass capacitors C11, C12, C6 and C7.

[0067] Optionally, the zero-crossing hysteresis comparator circuit 133 may include a second operational amplifier U5 and a third feedback resistor R13.

[0068] The non-inverting input of the second operational amplifier U5 is connected to the output of the precision operational amplifier U4; the two ends of the third feedback resistor R13 are connected to the non-inverting input and the output of the second operational amplifier U5, respectively; the output of the second operational amplifier U5 is connected to the controller 140; the reference input of the second operational amplifier U5 is grounded, using 0V as the comparison reference level. When the amplified AC signal crosses 0V, the second operational amplifier U5 flips the waveform of the amplified AC signal and outputs a polarity waveform signal with the same frequency and phase to the controller 140. A specific zero-crossing hysteresis comparator can be constructed based on the second operational amplifier U5 and the third feedback resistor R13, balancing zero-crossing detection and noise immunity. Utilizing the output inertia, strong anti-interference capability, and fast response speed of the zero-crossing hysteresis comparator, it eliminates input oscillations and jitter, resulting in higher accuracy of the positive / negative voltage polarity waveform signal output.

[0069] For example, the amplified AC signal enters the zero-crossing hysteresis comparator circuit 133. Pin 4 of the second operational amplifier U5 is used as the reference input pin, and grounded 0V serves as the comparison reference level. When the amplified AC signal crosses 0V, the waveform flips, outputting a square wave signal with the same frequency and phase. Resistor R11, acting as an isolation resistor, together with the second operational amplifier U5 and the positive feedback resistor R13, constitute the specific zero-crossing hysteresis comparator. Bypass capacitors C8 and C9 can also be included in the zero-crossing hysteresis comparator circuit 133.

[0070] Optionally, in Figure 3 In the illustrated embodiment, the parameter ranges for each device may include: resistors R9 and R12 with values ​​of 510KΩ to 10MΩ; capacitors C10 and C14 with values ​​of 68pF to 220pF; resistors R10, R11, R15, and R14 with values ​​of 510Ω to 10KΩ; capacitors C13 and C14 with values ​​of 0.1uF to 10uF; resistor R13 with values ​​of 100KΩ to 5MΩ; and the operational amplifier U4 of the precision operational amplifier may use a common rail-to-rail width power supply and a low-noise OPA2171AIDCUR.

[0071] Optionally, since the voltage level on the conductor A of the pressure plate under test changes, the positive and negative charges also change during the detection process. The polarity waveform signal output by the polarity voltage determination circuit 130 includes the amplitude and phase of the DC voltage. The non-contact DC voltage polarity measurement circuit may also include: an output voltage amplitude determination circuit, which is connected to the polarity voltage determination circuit 130.

[0072] Optionally, please refer to Figure 4 , Figure 4 The present invention provides a schematic diagram of an output voltage amplitude determination circuit, which may include: a third operational amplifier U2A, a differential operational amplifier U2B, a diode device D1, a fourth feedback resistor R20, two input resistors and a low-pass filter.

[0073] The inverting input of the third operational amplifier U2A is connected to the non-inverting input of the differential operational amplifier U2B. The non-inverting input of the third operational amplifier U2A is grounded. The two ends of diode D1 are connected to the output and inverting input of the third operational amplifier U2A, respectively, with the diode D1 conducting from the output to the inverting input of the third operational amplifier U2A. Two input resistors, R22 and R28, are connected to the non-inverting and inverting inputs of the differential operational amplifier U2B, respectively. The two ends of the fourth feedback resistor R20 are connected to the inverting and output of the differential operational amplifier U2B, respectively. The low-pass filter includes a low-pass filter resistor R21 and a low-pass filter capacitor C17. The first end of the low-pass filter resistor R21 is connected to the output pin of the differential operational amplifier U2B, the second end of the low-pass filter resistor R21 is connected to the first end of the low-pass filter capacitor C17 and the controller 140, and the second end of the low-pass filter capacitor C17 is grounded.

[0074] The third operational amplifier U2A can flip the negative half-axis portion of the amplified AC signal sine wave to the positive half-axis portion to obtain the flipped signal. The flipped signal is then input to the non-inverting input pin of the differential operational amplifier U2B. The differential operational amplifier U2B amplifies the flipped signal by one time and outputs the DC voltage amplitude signal of the conductor A of the test plate. The interference signal is filtered out by a low-pass filter, thereby achieving a high-precision measurement effect of the voltage amplitude.

[0075] For example, a weak AC voltage signal can be converted into a DC voltage using a precision full-wave rectifier circuit. Figure 4In the circuit, U2A forms a half-wave rectifier circuit, flipping the negative half-axis of the sine wave to the positive half-axis and simultaneously sending the signal to pin 5 of U2B, the non-inverting input pin, so that the differential operational amplifier U2B can differentially amplify the output DC amplitude signal by one time. D1 is a fast recovery Schottky diode (MMBD4148TS) used for rapid waveform flipping. Resistors R22, R18, the fourth feedback resistor R20, and U2B constitute the differential operational amplifier module. Low-pass filter resistor R21 and low-pass filter capacitor C17 form a first-order low-pass filter used to filter out interference signals. Resistor R19 provides a DC path for the input bias current, and capacitors C19 and C20 are bypass capacitors. When the resistance values ​​R20 = R22 = R18, the amplification factor is calculated as follows: = ,in, For the output voltage of U2B, This is the in-phase input pin. This is the inverting input pin.

[0076] For example, the values ​​of resistors R20, R22, and R18 are in the range of 1K to 10K; U2A and U2B can be selected from low-noise operational amplifiers OPA377AIDBVT.

[0077] Based on polarity discrimination, the device simultaneously achieves quantitative detection of DC voltage amplitude, enabling it to not only identify positive and negative polarities but also output a quantized amplitude signal corresponding to the measured DC voltage level. Combined with low-pass filtering, it can reduce ripple and interference, improve measurement stability at different voltage levels, and provide multi-dimensional criteria for risk assessment of opposite polarity voltages before the pressure plate is engaged or disengaged.

[0078] Optionally, when the voltage level on the test plate wire A is different, the amplitude of the converted DC voltage will also be different. The DC voltage level on the test plate wire A and the amplitude of the output DC voltage have the following correspondence:

[0079] Please see Figure 5 , Figure 5This is a flowchart illustrating a non-contact method for measuring the positive and negative poles of DC voltage, provided in an embodiment of this application. The method is applied to a non-contact DC voltage positive and negative pole measurement circuit, which includes: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller. The non-contact modulation structure includes a motion modulator and a sensing plate. The motion modulator is positioned between the conductor of the pressure plate under test and the sensing plate. The motion modulator changes the coupling state of the DC electric field of the conductor on the sensing plate through periodic movement. The standard square wave generation circuit includes: an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in series. The polarity voltage determination circuit includes: a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in series; the voltage sampling circuit is connected to the sensing plate. The method may include steps S210-S240.

[0080] Step S210: The DC electric field of the conductor of the pressure plate under test is modulated into an AC electric field through a non-contact modulation structure. Step S220: The motion process of the motion modulator is detected by the infrared detection circuit to generate an initial reference waveform signal; the initial reference waveform signal is shaped and filtered by the waveform shaping circuit to obtain a shaped reference waveform signal; the shaped reference waveform signal is compared by the hysteresis comparison circuit to output a standard reference waveform signal to the controller. Step S230: The voltage sampling circuit acquires the induced signal corresponding to the AC electric field and outputs an AC voltage signal; the signal amplification circuit amplifies and high-pass filters the AC voltage signal to obtain an amplified AC signal; the zero-crossing hysteresis comparison circuit performs zero-crossing detection and waveform inversion on the amplified AC signal and outputs a polarity waveform signal to the controller. Step S240: The voltage polarity of the conductor of the pressure plate under test is determined by comparing the polarity waveform signal with the standard reference waveform signal through the controller.

[0081] Since the principle of the non-contact method for measuring the positive and negative poles of DC voltage in this embodiment is similar to that of the aforementioned non-contact circuit for measuring the positive and negative poles of DC voltage, the implementation of the non-contact method for measuring the positive and negative poles of DC voltage in this embodiment can refer to the description in the aforementioned embodiment of the non-contact circuit for measuring the positive and negative poles of DC voltage, and the repeated parts will not be described again.

[0082] Optionally, please refer to Figure 6 , Figure 6 The following is a detailed flowchart of step S240 provided in an embodiment of this application. The method may include steps S241-S242.

[0083] Step S241: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If a polarity waveform signal is acquired as a high-level potential within a preset window period after the falling edge is generated, it is determined that the current test plate wire is a positive polarity voltage.

[0084] The controller can use the falling edge of the standard reference waveform signal within one cycle as the reference point for polarity determination. When the polarity waveform signal acquired within the preset window period after the falling edge is a high-level potential, the polarity waveform signal is the same as the polarity of the reference waveform signal and the waveform is ahead, which is a positive voltage waveform. Therefore, the DC voltage on the current test plate wire is determined to be a positive polarity voltage.

[0085] For example, the preset window period can be set based on the actual situation; for instance, it can be set to 10ms.

[0086] Optionally, please refer to Figure 7 , Figure 7 This is a waveform comparison diagram of a positive voltage provided in an embodiment of this application. During the rotation of the blade, the positive electric field on the induction plate is converted into a small DC voltage by a sampling resistor. The small DC voltage is then amplified and fed into a zero-crossing hysteresis comparison circuit to generate a polarity waveform signal that is identical in polarity to the standard reference square wave signal (the high and low levels of the waveform are consistent) but leads the waveform. The falling edge of the standard reference square wave signal within one cycle time T is used as the reference point. If the controller collects 10 high-level potentials within a 10ms window period after the falling edge of one cycle is generated, it is determined that the DC voltage on the measured wire at this time is a positive voltage.

[0087] Step S242: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If a low-level potential polarity waveform signal is acquired within the preset window period after the falling edge is generated, the current test plate wire is determined to be a negative polarity voltage.

[0088] The controller can use the falling edge of the standard reference waveform signal within one cycle as the reference point for polarity determination. When the polarity waveform signal acquired within the preset window period after the falling edge is a low level potential, the polarity waveform signal is opposite to the polarity of the reference waveform signal and the waveform is ahead, which is a negative voltage waveform. Therefore, the DC voltage on the current test plate wire is determined to be a negative polarity voltage.

[0089] Optionally, please refer to Figure 8 , Figure 8This is a waveform comparison diagram of a negative polarity voltage provided in an embodiment of this application. During the rotation of the blade, the negative polarity electric field on the induction plate is converted into a small DC voltage through a sampling resistor. The small DC voltage is then amplified and fed into a zero-crossing hysteresis comparison circuit to generate a polarity waveform signal that is opposite in polarity to the standard reference square wave signal (the high and low levels of the waveform are the same) but leads the waveform. The falling edge of the standard reference square wave signal within one cycle time T is used as the reference point. If the controller collects 10 low-level potentials within a 10ms window period after the falling edge of one cycle is generated, it is determined that the DC voltage on the measured wire at this time is a negative polarity voltage.

[0090] In summary, this application provides a non-contact circuit and method for measuring the positive and negative poles of DC voltage. It utilizes a non-contact modulation structure, such as rotating blades, to modulate a DC electric field into an AC electric field. During the process of the mechanical movement of the main body driving the blades to rotate and modulate the AC electric field, an infrared photodiode is added to detect and generate a standard reference waveform signal based on the actual rotation speed of the blades. This standard reference waveform signal is then compared with the sampled and modulated polarity waveform signal. An algorithm is used to calculate the positive or negative pole of the DC voltage on the measured conductor. It leverages the characteristics of DC voltage during the modulation of the DC electric field into an AC electric field. When the positive and negative electric fields are applied to the sensing electrodes, they generate a pair of signals with opposite polarities and a 180-degree phase difference. By amplifying and comparing the small AC signal at zero crossings, a set of square wave signals is generated as the polarity waveform signal. The measurement process does not rely on signal acquisition from external sensors. It utilizes the inherent motion changes of the non-contact modulation structure to directly collect the related portion of the two polarities from the source. A stable standard waveform is generated using the commonalities of the two polarities and compared with the modulated positive and negative polarity waveforms, ensuring the reliability and accuracy of polarity determination. This application can detect low, medium, and high DC voltages. The higher the DC voltage, the higher the measurement accuracy. Combined with a simple algorithm, it can automatically identify the positive and negative polarities of the DC voltage. Compared with traditional contact-type DC voltage measurements such as resistor voltage dividers and transformer measurements, it has higher safety and reliability and can replace existing contact-type voltage measurement methods. It does not rely on external sensors for measurement. It uses a non-contact modulation structure and infrared photodiode detection to construct a standard square wave. Compared with other non-contact DC voltage measurement methods, the technology is simpler, the accuracy is higher, and fewer components are used.

[0091] This application embodiment enables non-contact polarity determination and voltage amplitude detection before the DC control circuit pressure plate of a substation is engaged or disengaged, without electrical contact, repeated on-site calibration, or complex external sensors. It solves the safety problems of short circuits, grounding, and false tripping that are easily caused by contact measurement, and makes up for the defects of unstable polarity determination and insufficient on-site adaptability of traditional non-contact solutions. It can be directly embedded in switch cabinets, ring main units, or voltage testing devices, providing reliable technical support for intelligent operation and maintenance of new power systems, safety management and control of unattended substations, and anti-misoperation interlocking of distribution networks.

[0092] In the several embodiments provided in this application, it should be understood that the disclosed device can also be implemented in other ways. The device embodiments described above are merely illustrative; for example, the block diagrams in the accompanying drawings illustrate the possible architecture, functions, and operations of the device according to various embodiments of this application. In this regard, each block in the block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram, and combinations of block diagrams, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

[0093] In addition, the functional modules in the various embodiments of this application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0094] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0095] The above description is merely an embodiment of this application and is not intended to limit the scope of protection of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application. It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0096] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

[0097] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A non-contact circuit for measuring the positive and negative terminals of DC voltage, applied to the outlet pressure plate of a protective enclosure, characterized in that, The circuit includes: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller. The non-contact modulation structure includes a motion modulator and a sensing plate. The motion modulator is disposed between the test plate wire and the sensing plate. The motion modulator changes the coupling state of the DC electric field of the test plate wire on the sensing plate through periodic movement, thus modulating the DC electric field into an AC electric field. The standard square wave generation circuit includes an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in sequence. The infrared detection circuit is used to detect the motion process of the motion modulator and generate an initial reference waveform signal. The waveform shaping circuit is used to shape and filter the initial reference waveform signal to obtain a shaped reference waveform signal. The hysteresis comparison circuit is used to perform hysteresis comparison on the shaped reference waveform signal and output a standard reference waveform signal to the controller. The polarity voltage determination circuit includes a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in sequence. The voltage sampling circuit is connected to the induction plate and is used to collect the induced signal corresponding to the AC electric field and output an AC voltage signal. The signal amplification circuit is used to amplify and high-pass filter the AC voltage signal to obtain an amplified AC signal. The zero-crossing hysteresis comparison circuit is used to perform zero-crossing detection and waveform inversion on the amplified AC signal and output a polarity waveform signal to the controller. The controller is used to determine the voltage polarity of the conductor of the pressure plate under test by comparing the polarity waveform signal with the standard reference waveform signal.

2. The circuit according to claim 1, characterized in that, The infrared detection circuit includes: an infrared photodiode and a pull-up resistor; The optical path of the infrared photodiode corresponds to the motion change region of the motion modulator. The output pin of the infrared photodiode is connected to one end of the pull-up resistor and the input pin of the waveform shaping circuit, respectively. The other end of the pull-up resistor is connected to the positive terminal of the DC power supply. The infrared photodiode is in a conducting state and a closed state as the motion modulator periodically blocks it. The output pin of the infrared photodiode generates the periodic initial reference waveform signal and outputs it to the waveform shaping circuit. The pull-up resistor is used to adjust the initial reference waveform signal to a high level signal when the motion modulator does not move.

3. The circuit according to claim 2, characterized in that, The waveform shaping circuit includes: a first operational amplifier and a first feedback resistor; The non-inverting input pin of the first operational amplifier is connected to the output pin of the infrared photodiode. The two ends of the first feedback resistor are respectively connected to the inverting input pin and the output pin of the first operational amplifier. The output pin of the first operational amplifier is connected to the hysteresis comparator circuit.

4. The circuit according to claim 3, characterized in that, The hysteresis comparator circuit includes: a hysteresis comparator and a voltage divider resistor; The reference pin of the hysteresis comparator is connected to the voltage divider resistor and generates a reference voltage value based on the voltage divider resistor; The input pin of the hysteresis comparator is connected to the output pin of the first operational amplifier. The hysteresis comparator is used to compare the reference voltage value and the shaped reference waveform signal, and output the standard reference waveform signal to the controller.

5. The circuit according to claim 1, characterized in that, The voltage sampling circuit includes: a sampling resistor and a sampling capacitor; The sampling resistor and the sampling capacitor are connected in parallel. One end of the sampling resistor and one end of the sampling capacitor are connected to the sensing plate. The other end of the sampling resistor and the other end of the sampling capacitor are both grounded. The sampling resistor is used to collect the induced current of the AC electric field during the motion of the motion modulator, and convert the induced current into an induced voltage to output the AC voltage signal; The sampling capacitor is used to increase the induced voltage.

6. The circuit according to claim 5, characterized in that, The signal amplification circuit includes: a non-inverting amplifier and a high-pass filter; The non-inverting amplifier includes: a precision operational amplifier, a second feedback resistor, and a first capacitor. The non-inverting input pin of the precision operational amplifier is connected to the voltage sampling circuit. The two ends of the second feedback resistor and the first capacitor are respectively connected to the inverting input pin and the output pin of the precision operational amplifier. The high-pass filter includes a high-pass filter resistor and a high-pass filter capacitor. The first end of the high-pass filter resistor is connected to the inverting input pin of the precision operational amplifier, the second end of the high-pass filter resistor is connected to the first end of the high-pass filter capacitor, and the second end of the high-pass filter capacitor is grounded. The in-phase amplifier is used to amplify the AC voltage signal to obtain an amplified AC signal. The high-pass filter is used to suppress interference signals in the amplified AC signal.

7. The circuit according to claim 6, characterized in that, The zero-crossing hysteresis comparator circuit includes: a second operational amplifier and a third feedback resistor; The non-inverting input pin of the second operational amplifier is connected to the output pin of the precision operational amplifier; The two ends of the third feedback resistor are respectively connected to the non-inverting input pin and the output pin of the second operational amplifier; The output pin of the second operational amplifier is connected to the controller; The reference input pin of the second operational amplifier is grounded, with 0V as the comparison reference level. When the amplified AC signal passes through 0V, the second operational amplifier flips the waveform of the amplified AC signal and outputs the polarity waveform signal with the same frequency and phase to the controller.

8. The circuit according to claim 1, characterized in that, The non-contact DC voltage measurement circuit also includes: an output voltage amplitude determination circuit; The output voltage amplitude determination circuit is connected to the polarity voltage determination circuit; The output voltage amplitude determination circuit includes: a third operational amplifier, a differential operational amplifier, a diode device, a fourth feedback resistor, two input resistors, and a low-pass filter; The inverting input pin of the third operational amplifier is connected to the non-inverting input pin of the differential operational amplifier. The non-inverting input pin of the third operational amplifier is grounded. The two ends of the diode device are respectively connected to the output pin of the third operational amplifier and the inverting input pin of the third operational amplifier. The conduction direction of the diode device is from the output pin of the third operational amplifier to the inverting input pin of the third operational amplifier. The two input resistors are respectively connected to the non-inverting input pin and the inverting input pin of the differential operational amplifier, and the two ends of the fourth feedback resistor are respectively connected to the inverting input pin and the output pin of the differential operational amplifier. The low-pass filter includes a low-pass filter resistor and a low-pass filter capacitor; the first end of the low-pass filter resistor is connected to the output pin of the differential operational amplifier, the second end of the low-pass filter resistor is connected to the first end of the low-pass filter capacitor and the controller, and the second end of the low-pass filter capacitor is grounded; The third operational amplifier is used to flip the negative half-axis portion of the sine wave of the amplified AC signal to the positive half-axis portion to obtain a flipped signal, and input the flipped signal into the non-inverting input pin of the differential operational amplifier. The differential operational amplifier is used to differentially amplify the flip signal by one time and then output the DC voltage amplitude signal of the test plate wire to the controller.

9. The circuit according to any one of claims 1-8, characterized in that, The motion modulation component is a rotating blade mechanism or a vibrating capacitor mechanism; The rotating blade mechanism includes a rotating blade with a hollowed-out area and a driving component. The driving component drives the rotating blade to rotate at a constant speed, periodically blocking the electric field between the wire of the pressure plate to be tested and the induction plate, thereby achieving electric field modulation. The vibration capacitor mechanism includes a vibration plate and a driving component. The driving component drives the vibration plate to reciprocate, periodically changing the equivalent capacitance between the test plate wire and the sensing plate, thereby achieving electric field modulation.

10. A non-contact method for measuring the positive and negative terminals of DC voltage, characterized in that, The method is applied to a non-contact DC voltage polarity measurement circuit, the circuit comprising: a non-contact modulation structure, a standard square wave generation circuit, a polarity voltage determination circuit, and a controller; the method comprises: The non-contact modulation structure includes a motion modulator and a sensing plate. The motion modulator is disposed between the test plate wire and the sensing plate. The motion modulator changes the coupling state of the DC electric field of the test plate wire on the sensing plate through periodic movement. The non-contact modulation structure modulates the DC electric field of the test plate wire into an AC electric field. The standard square wave generation circuit includes: an infrared detection circuit, a waveform shaping circuit, and a hysteresis comparison circuit connected in series. The infrared detection circuit detects the motion process of the motion modulator and generates an initial reference waveform signal. The waveform shaping circuit shapes and filters the initial reference waveform signal to obtain a shaped reference waveform signal. The hysteresis comparison circuit performs a hysteresis comparison on the shaped reference waveform signal and outputs a standard reference waveform signal to the controller. The polarity voltage determination circuit includes: a voltage sampling circuit, a signal amplification circuit, and a zero-crossing hysteresis comparison circuit connected in series. The voltage sampling circuit is connected to the induction plate and collects the induced signal corresponding to the AC electric field, outputting an AC voltage signal. The signal amplification circuit amplifies and high-pass filters the AC voltage signal to obtain an amplified AC signal. The zero-crossing hysteresis comparison circuit performs zero-crossing detection and waveform inversion on the amplified AC signal, outputting a polarity waveform signal to the controller. The controller compares the polarity waveform signal with the standard reference waveform signal to determine the voltage polarity of the conductor of the pressure plate under test.

11. The method according to claim 10, characterized in that, The step of determining the voltage polarity of the test plate wire by comparing the polarity waveform signal with the standard reference waveform signal through the controller includes: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If the polarity waveform signal is high-level within a preset window period after the falling edge is generated, the test plate wire is determined to be positive polarity voltage.

12. The method according to claim 10, characterized in that, The step of determining the voltage polarity of the conductor of the pressure plate under test by comparing the polarity waveform signal with the standard reference waveform signal through the controller includes: The controller determines the falling edge of the standard reference waveform signal within one cycle as the reference point. If the polarity waveform signal is low-level within a preset window period after the falling edge is generated, the test plate wire is determined to be negative polarity voltage.

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