A high-level voltage detection device based on power frequency notch

Abstract

The application relates to a high-grade voltage detection device based on a power frequency notch, which comprises an upper plate, a lower plate and a voltage detection assembly. The upper plate is used for contacting a measured wire. The lower plate is connected with the upper plate and forms a measurement loop. The voltage detection assembly comprises a micro control unit, a signal injection module, a signal acquisition module and a frequency selection network module. The signal injection module is used for injecting a first detection signal and a second detection signal into the measurement loop under the control of the micro control unit. The signal acquisition module is used for acquiring a displacement current signal in the measurement loop. The frequency selection network module is used for filtering the displacement current signal and obtaining a frequency current signal. The micro control unit is used for determining a to-be-measured voltage according to the frequency current signal. The frequency selection network module is arranged to filter the displacement current signal, the power frequency current signal in the displacement current signal can be suppressed, the signal-to-noise ratio of an alien frequency signal is improved, and weak alien frequency displacement current can be extracted.

Description

Technical Field

[0001] This application relates to the field of power detection technology, and in particular to a high-level voltage detection device based on power frequency notch filtering. Background Technology

[0002] With the integration of renewable energy and the increasing number of electric vehicles, the variability of parameters such as voltage, current, and power flow in high-voltage power grids will increase in the foreseeable future. To ensure the normal operation of the power system, it is usually necessary to monitor the voltage and current of power transmission lines to guarantee stable operation or provide early warning of faults. In non-invasive measurements of high-voltage systems (10kV to 750kV), obtaining the inter-frequency displacement current signal under the action of a reference voltage is crucial. However, due to limitations in device power consumption and insulation levels, the amplitude of the reference signal generated by the voltage detection device is often only a few hundred volts, which is 3 to 4 orders of magnitude different from the measured power frequency voltage. Therefore, extracting the weak inter-frequency displacement current from the strong power frequency displacement current signal is extremely difficult. Summary of the Invention

[0003] Therefore, it is necessary to provide a high-level voltage detection device based on power frequency notch filtering that can accurately extract weak heterogeneous displacement currents, addressing the aforementioned technical problems.

[0004] In one embodiment, this application provides a high-level voltage detection device based on power frequency notch filtering. The device includes: an upper electrode plate, a lower electrode plate, and a voltage detection component. The upper electrode plate is used to contact the conductor under test; the lower electrode plate is connected to the upper electrode plate to form a measurement circuit. The voltage detection component includes: a microcontroller unit, a signal injection module, a signal acquisition module, and a frequency selection network module. The microcontroller unit is connected to both the signal injection module and the frequency selection network module. The signal injection module and the signal acquisition module are respectively connected to the measurement circuit. The frequency selection network module is connected to both the microcontroller unit and the signal acquisition module. The signal injection module, under the control of the microcontroller unit, injects a first detection signal and a second detection signal into the measurement circuit. The signal acquisition module acquires a displacement current signal in the measurement circuit. The frequency selection network module filters the displacement current signal to obtain a frequency current signal. The microcontroller unit determines the voltage to be measured based on the frequency current signal.

[0005] In one embodiment, the microcontroller unit is used to perform a Fourier transform on the frequency current signal to obtain a first detection current, a second detection current, and a rated current. The microcontroller unit is used to determine the voltage to be measured based on the first detection current, the second detection current, the rated current, and the detection voltage.

[0006] In one embodiment, the frequency selection network module includes: a first-stage notch filter circuit and a second-stage notch filter circuit, wherein the input terminal of the first-stage notch filter circuit is used to receive the displacement current signal, the output terminal of the first-stage notch filter circuit is connected to the input terminal of the second-stage notch filter circuit, and the output terminal of the second-stage notch filter circuit is used to output the frequency current signal.

[0007] In one embodiment, the first-stage notch filter circuit includes: a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a third capacitor. One end of the first resistor is used to receive the displacement current signal, and the other end of the first resistor is connected to a first node. One end of the second resistor is connected to the first node, and the other end of the second resistor is connected to the second-stage notch filter circuit. One end of the first capacitor is used to receive the displacement current signal, and the other end of the first capacitor is connected to a second node. One end of the second capacitor is connected to the second node, and the other end of the second capacitor is connected to the second-stage notch filter circuit. One end of the third capacitor is connected to the first node, and the other end of the third capacitor is grounded. One end of the third resistor is connected to the second node, and the other end of the third resistor is grounded.

[0008] In one embodiment, the second-stage notch filter circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. One end of the fourth resistor is connected to the first-stage notch filter circuit, and the other end of the fourth resistor is connected to a third node. One end of the fifth resistor is connected to the third node, and the other end of the fifth resistor is used to output the frequency current signal. One end of the fourth capacitor is connected to the first-stage notch filter circuit, and the other end of the fourth capacitor is connected to a fourth node. One end of the fifth capacitor is connected to the fourth node, and the other end of the fifth capacitor is used to output the frequency current signal. One end of the sixth capacitor is connected to the third node, and the other end of the sixth capacitor is grounded. One end of the sixth resistor is connected to the fourth node, and the other end of the sixth resistor is grounded.

[0009] In one embodiment, the voltage detection component further includes: an energy harvesting magnetic core, an energy harvesting coil, a protection module, and a power supply module. The energy harvesting magnetic core is used to be sleeved on the conductor under test. The energy harvesting coil is connected to the energy harvesting magnetic core. The protection module is connected to the energy harvesting coil and is used to acquire the induced voltage. The power supply module is connected to the protection module and is used to rectify the induced voltage to obtain a supply voltage.

[0010] In one embodiment, the voltage detection component further includes a backup battery connected to the power module, the backup battery being used to store or provide electrical energy.

[0011] In one embodiment, the voltage detection component further includes a wireless communication module connected to the microcontroller unit, the wireless communication module being used to wirelessly transmit the voltage to be measured.

[0012] In one embodiment, the device further includes: an upper latching arm and a lower latching arm, the upper latching arm being provided with an upper latching pad; the lower latching arm being rotatably connected to the upper latching arm, the lower latching arm being provided with a lower latching pad, the upper latching pad and the lower latching pad being used to form an accommodating space, the accommodating space being used to accommodate the conductor under test.

[0013] In one embodiment, the upper locking pad is connected to the upper arm of the buckle via a first spring, and the lower locking pad is connected to the lower arm of the buckle via a second spring.

[0014] The aforementioned high-level voltage detection device based on power frequency notch filtering filters filters the displacement current signal by setting a frequency selection network module in the voltage detection component. This can suppress the power frequency current signal in the displacement current signal, thereby improving the signal-to-noise ratio of the different frequency signals and facilitating the extraction of weak different frequency displacement currents. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the conventional technology, the drawings used in the description of the embodiments or the conventional technology will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a voltage detection device module in one embodiment;

[0017] Figure 2 This is a schematic diagram illustrating the principle of voltage detection in one embodiment;

[0018] Figure 3 This is a simplified circuit diagram for voltage detection in one embodiment;

[0019] Figure 4 This is a circuit diagram of a frequency selection network module in one embodiment;

[0020] Figure 5 for Figure 4 Waveform diagram of the original waveform in the embodiment;

[0021] Figure 6 for Figure 4 Voltage waveform diagram across the voltage divider capacitor in the embodiment;

[0022] Figure 7for Figure 4 Bode plot of the two-stage notch filter circuit in the embodiment;

[0023] Figure 8 for Figure 4 The waveform of the output voltage after passing through two notch filter circuits in the embodiment;

[0024] Figure 9 This is a schematic diagram of a voltage detection device module in another embodiment;

[0025] Figure 10 This is a schematic diagram of the voltage detection device in another embodiment;

[0026] Explanation of reference numerals in the attached figures:

[0027] Upper electrode plate 100, lower electrode plate 200, voltage detection component 300, test lead wire 400, microcontroller unit 310, signal injection module 320, signal acquisition module 330, frequency selection network module 340, energy harvesting magnetic core 350, energy harvesting coil 360, protection module 370, power supply module 380, wireless communication module 390, backup battery 311, upper latch arm 312, upper latching pad 313, lower latch arm 314, lower latching pad 315, first-stage notch filter circuit 341, second-stage notch filter circuit 342. Detailed Implementation

[0028] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0030] It is understood that the terms "first," "second," etc., used herein may be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first resistor may be referred to as a second resistor, and similarly, a second resistor may be referred to as a first resistor. Both the first resistor and the second resistor are resistors, but they are not the same resistor.

[0031] It is understood that the term "connection" in the following embodiments should be understood as "electrical connection," "communication connection," etc., if the connected circuits, modules, units, etc., have electrical signal or data transmission with each other.

[0032] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “comprising / including” or “having,” etc., specify the presence of the stated features, wholes, steps, operations, components, parts, or combinations thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, steps, operations, components, parts, or combinations thereof. Meanwhile, the term “and / or” as used in this specification includes any and all combinations of the associated listed items.

[0033] In one embodiment, such as Figure 1 As shown, this application proposes a high-level voltage detection device based on power frequency notch filtering. The voltage detection device includes: an upper electrode plate 100, a lower electrode plate 200, and a voltage detection component 300. The upper electrode plate 100 is used to contact the conductor 400 under test; the lower electrode plate 200 is connected to the upper electrode plate 100 and forms a measurement circuit; the voltage detection component 300 includes: a microcontroller unit 310, a signal injection module 320, a signal acquisition module 330, and a frequency selection network module 340. The microcontroller unit 310 is connected to the signal injection module 320 and the frequency selection network module 340 respectively. Module 320 and signal acquisition module 330 are respectively connected to the measurement circuit, and frequency selection network module 340 is respectively connected to microcontroller 310 and signal acquisition module 330; wherein, signal injection module 320 is used to inject a first detection signal and a second detection signal into the measurement circuit under the control of microcontroller 310, signal acquisition module 330 is used to acquire displacement current signal in the measurement circuit, frequency selection network module 340 is used to filter displacement current signal and obtain frequency current signal, and microcontroller 310 is used to determine the voltage to be measured based on frequency current signal.

[0034] Specifically, the upper electrode 100 and lower electrode 200 are probes made of copper foil. The upper electrode 100 is in close contact with the wire being measured 400, and the upper electrode 100 can be configured as a ring. For example... Figure 2 As shown, this is a schematic diagram of the voltage detection device in this application performing voltage detection. A first coupling capacitor C1 is formed between the upper plate 100 and the conductor 400 being measured, and a second coupling capacitor C2 is formed between the lower plate 200 and the ground.

[0035] The signal injection module 320 is controlled by the microcontroller unit 310 (MCU) to modulate high-frequency voltage. According to the instructions sent by the microcontroller unit 310, the signal injection module 320 generates different types of high-frequency voltages, namely a first detection signal and a second detection signal. These first and second detection signals clamp the potential between the upper plate 100 and the lower plate 200 to a specific electromotive force, thus disregarding the capacitance effect between the two plates. Figure 3 The diagram shown is a simplified circuit diagram for voltage detection. The frequency f of the injected signal is adjusted... r To inject a first detection signal and a second detection signal, wherein the first detection signal has a first frequency f r1 The second frequency f of the second detection signal r2 All are related to the voltage to be measured, U s The rated frequency f s Unlike other methods, when using dual-frequency injection, the first frequency f r1 With the second frequency f r2 The sum of these two frequencies equals twice the rated frequency f. s That is, satisfying: f r1 +f r2 =2f s The voltages of both the first and second detection signals are the detection voltage U. r .

[0036] The voltage detection device acquires the displacement current signal I in the measurement circuit through the signal acquisition module 330. 总 Displacement current signal I 总 The signal includes the displacement current formed by the superposition of the first detection signal, the second detection signal, and the voltage to be measured. After receiving the displacement current signal, the frequency selection network module 340 filters it to obtain a frequency current signal. It can be understood that during filtering, the frequency selection network module 340 suppresses the displacement current formed by the voltage to be measured, highlighting the displacement current formed by the first and second detection signals, thereby improving the signal-to-noise ratio of the different frequency signals and facilitating the extraction of weak different frequency displacement currents. After the frequency selection network module 340 sends the processed frequency current signal to the microcontroller unit 310, the microcontroller unit 310 determines the magnitude of the voltage to be measured based on the frequency current signal, thus completing the voltage magnitude detection.

[0037] In one embodiment, the microcontroller unit 310 is used to perform a Fourier transform on the frequency current signal to obtain a first detection current, a second detection current, and a rated current. The microcontroller unit 310 is used to determine the voltage to be measured based on the first detection current, the second detection current, the rated current, and the detection voltage.

[0038] Specifically, the microcontroller unit 310 performs a Fourier transform on the frequency current signal and obtains the first detection current I based on its frequency magnitude. r1 Second detection current I r2 and rated current I s It is understandable that the displacement current signal I... 总 =I s +I r1 +I r2 First detection current I r1 The frequency is the first frequency f r1 The second detection current I r2 The frequency is the second frequency f r2 Rated current I s The frequency is the rated frequency f s According to the superposition theorem of currents, we can obtain:

[0039]

[0040] At the same time, due to f r1 +f r2 =2f s Therefore, the voltage to be measured U s It can be calculated using the following formula:

[0041]

[0042] Among them, I s I r1 and I r2 f can be obtained through current detection and calculation. r1 f r2 and f s It is fixed, U r It is a pre-set value; therefore, the voltage U to be measured can be calculated using the above formula. s The specific value is determined to complete the measurement of the 400V voltage of the conductor being tested.

[0043] In one embodiment, such as Figure 4 As shown, the frequency selection network module 340 includes a first-stage notch filter circuit 341 and a second-stage notch filter circuit 342. The input terminal of the first-stage notch filter circuit 341 is used to receive the displacement current signal, and the output terminal of the first-stage notch filter circuit 341 is connected to the input terminal of the second-stage notch filter circuit 342. The output terminal of the second-stage notch filter circuit 342 is used to output the frequency current signal. Specifically, in this embodiment, the displacement current signal is notched using two stages of notch filter circuits to suppress the power frequency, improve the signal-to-noise ratio of the dual-frequency signal, and thus facilitate clearer separation of the first detection current and the second detection current.

[0044] In one embodiment, such as Figure 4 As shown, the first-stage notch filter circuit 341 includes: a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a third capacitor. One end of the first resistor is used to receive the displacement current signal, and the other end of the first resistor is connected to the first node. One end of the second resistor is connected to the first node, and the other end of the second resistor is connected to the second-stage notch filter circuit 342. One end of the first capacitor is used to receive the displacement current signal, and the other end of the first capacitor is connected to the second node. One end of the second capacitor is connected to the second node, and the other end of the second capacitor is connected to the second-stage notch filter circuit 342. One end of the third capacitor is connected to the first node, and the other end of the third capacitor is grounded. One end of the third resistor is connected to the second node, and the other end of the third resistor is grounded.

[0045] In one embodiment, such as Figure 4 As shown, the second-stage notch filter circuit 342 includes: a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. One end of the fourth resistor is connected to the first-stage notch filter circuit 341, and the other end of the fourth resistor is connected to the third node. One end of the fifth resistor is connected to the third node, and the other end of the fifth resistor is used to output a frequency current signal. One end of the fourth capacitor is connected to the first-stage notch filter circuit 341, and the other end of the fourth capacitor is connected to the fourth node. One end of the fifth capacitor is connected to the fourth node, and the other end of the fifth capacitor is used to output a frequency current signal. One end of the sixth capacitor is connected to the third node, and the other end of the sixth capacitor is grounded. One end of the sixth resistor is connected to the fourth node, and the other end of the sixth resistor is grounded.

[0046] The frequency selection network module 340 of this application is described in detail below with reference to a specific embodiment. Figure 4 The coupling capacitor C8 is set to 2pF, the voltage to be measured is 110kV, 50Hz industrial frequency AC, and the voltage divider capacitor C7 is set to 1nF. A first detection signal of 1kV, 40Hz and a second detection signal of 1kV, 60Hz are injected into the measurement circuit. The voltage across the voltage divider capacitor C7 is a composite waveform of 50Hz, 40Hz, and 60Hz. The oscilloscope XSC3 is used to detect the original waveform of the dual-frequency injected signals, which is a superimposed waveform of two voltage signals with an amplitude of 1kV and frequencies of 40Hz and 60Hz respectively. The waveform is as follows. Figure 5 As shown. The voltage waveform across the voltage divider capacitor C7 can be measured using an oscilloscope XSC2, and its waveform is as follows. Figure 6 As shown. By Figure 6As can be seen from the waveform, the dual-frequency injected signals (first detection signal and second detection signal) are submerged under the power frequency signal. This is because the amplitude of the power frequency signal is 110kV, while the amplitude of the dual-frequency injected signal is 1kV. At this point, it is difficult for the voltage detection component 300 to separate the displacement current signal using conventional signal processing circuits. The 50Hz power frequency signal has a significant impact on the acquisition of the 40+60Hz signal. Therefore, this embodiment of the application uses a two-stage power frequency notch filter circuit to suppress the power frequency signal and improve the signal-to-noise ratio of the dual-frequency injected signal.

[0047] like Figure 7 As shown, this is the gain result of the two-stage notch filter circuit detected by XBP1. The output of the two-stage notch filter circuit is the output signal after notch filtering, which can be detected by XSC4. Its waveform is as follows. Figure 8 As shown in the waveform diagram above, the 50Hz power frequency component is suppressed by nearly -105dB through the two-stage notch filter circuit. While the 40Hz and 60Hz components are also suppressed to some extent (approximately -45dB), the suppression effect is not significant compared to the 50Hz power frequency component. In other words, the two-stage notch filter circuit successfully suppresses the 50Hz signal, leaving the effective signal at 40+60Hz, thus improving the signal-to-noise ratio of the signal processing.

[0048] After performing a Fourier transform on the frequency current signal obtained through notch filtering, the magnitude of the first detection current at 40Hz is 2.73nA, the magnitude of the second detection current at 60Hz is 5.01nA, and the magnitude of the rated current at 50Hz is 390nA, which is I. r1 =2.73nA, I r2 =5.01nA, I s =390nA, and U r =1000V, substitute into the formula to calculate U s =U r *I s *(I r1 +I r2 ) / 2 / I r1 / I r2 =110350V, with an error of about 0.3% compared to its true value of 110kV. Therefore, the voltage detection device of this application embodiment can accurately detect the magnitude of the voltage to be measured.

[0049] In one embodiment, such as Figure 9As shown, the voltage detection component 300 further includes: an energy harvesting magnetic core 350, an energy harvesting coil 360, a protection module 370, and a power supply module 380. The energy harvesting magnetic core 350 is used to be sleeved on the conductor 400 under test. The energy harvesting coil 360 is connected to the energy harvesting magnetic core 350. The protection module 370 is connected to the energy harvesting coil 360 and is used to acquire the induced voltage. The power supply module 380 is connected to the protection module 370 and is used to rectify the induced voltage to obtain the supply voltage.

[0050] Specifically, the energy harvesting core 350 and the energy harvesting coil 360 constitute the energy harvesting module of the voltage detection component 300. Its principle is to utilize electromagnetic induction to convert the magnetic field energy generated by the current in the tested conductor 400 into the electrical energy required by the voltage detection component 300. The protection module 370 is used to protect the voltage detection component 300, especially in cases where the current in the tested conductor 400 suddenly increases due to various faults such as lightning strikes, misoperation, or short circuits. The protection module 370 can promptly activate and disconnect the energy harvesting coil 360, thereby protecting subsequent circuits. The power supply module 380 is used to rectify the acquired induced voltage, converting the induced AC electromotive force into a DC electromotive force and maintaining its stability, thereby outputting a supply voltage to provide stable power to the circuits in the voltage detection component 300. The supply voltage output by the power supply module 380 is typically 5V or 3.3V.

[0051] In one embodiment, such as Figure 9 As shown, the voltage detection component 300 also includes a backup battery 311, which is connected to the power module 380. The backup battery 311 is used to store or provide electrical energy. Specifically, the backup battery 311 is generally a lithium battery or a supercapacitor. When the current of the tested wire 400 is small and the output power of the power module 380 is small, the backup battery 311 can be used to supply power. When the current of the tested wire 400 is large and the output power of the power module 380 is large, the backup battery 311 can also be charged to store electrical energy in advance.

[0052] In one embodiment, such as Figure 9 As shown, the voltage detection component 300 also includes a wireless communication module 390, which is connected to the microcontroller unit 310. The wireless communication module 390 is used to wirelessly transmit the voltage to be measured. Specifically, the wireless communication module 390 can be a Bluetooth module, etc., and can periodically send the detected voltage to be measured to the detection platform through an antenna.

[0053] In one embodiment, such as Figure 10As shown, the voltage detection device further includes: an upper latching arm 312 and a lower latching arm 314. The upper latching arm 312 is provided with an upper locking pad 313; the lower latching arm 314 is rotatably connected to the upper latching arm 312 and is provided with a lower locking pad 315. The upper locking pad 313 and the lower locking pad 315 form a receiving space for accommodating the conductor 400 under test. Specifically, the upper latching arm 312 is a movable structure, and it can be rotatably connected to the lower latching arm 314 via a rotating shaft. To install it onto the conductor 400 under test, the upper latching arm 312 and the lower latching arm 314 need to be opened, and then the voltage detection device is latched onto the conductor 400 under test. The upper latching arm 312 and the lower latching arm 314 can be secured with hooks. The upper locking pad 313 and the lower locking pad 315 are respectively arranged on the upper arm 312 and the lower arm 314 of the buckle. The material of the locking pad can be rubber or plastic.

[0054] In some other embodiments, the upper locking pad 313 is connected to the upper latch arm 312 via a first spring, and the lower locking pad 315 is connected to the lower latch arm 314 via a second spring. Specifically, due to the action of the metal springs, the voltage detection device can adapt to wires of different diameters. For example, when clamped on a thicker transmission line, the metal spring will compress, and the locking pads will sink into the upper latch arm 312 and the lower latch arm 314, ensuring that the voltage detection device can be tightly clamped onto the wire, thus making it suitable for transmission lines of different diameters. The depth to which the locking pads sink into the upper latch arm 312 and the lower latch arm 314 can adaptively change according to the thickness of the wire.

[0055] In the description of this specification, the references to terms such as "some embodiments," "other embodiments," and "specific embodiments" refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example that are included in at least one embodiment or example of this application. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0056] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0057] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A high-level voltage detection device based on power frequency notch filtering, characterized in that, The device includes: Upper electrode plate, which is used to contact the conductor being tested; The lower electrode plate is connected to the upper electrode plate to form a measurement circuit; A voltage detection component, comprising: a microcontroller unit, a signal injection module, a signal acquisition module, and a frequency selection network module; the microcontroller unit is connected to the signal injection module and the frequency selection network module respectively; the signal injection module and the signal acquisition module are connected to the measurement circuit respectively; and the frequency selection network module is connected to the microcontroller unit and the signal acquisition module respectively. The signal injection module is used to inject a first detection signal and a second detection signal into the measurement circuit under the control of the microcontroller unit. The first frequency of the first detection signal and the second frequency of the second detection signal are both different from the rated frequency of the voltage to be measured. The voltages of the first detection signal and the second detection signal are both detection voltages. The voltage to be measured is power frequency AC. The signal acquisition module is used to acquire the displacement current signal in the measurement circuit. The displacement current signal includes the displacement current formed by the superposition of the first detection signal, the second detection signal, and the voltage to be measured. The frequency selective network module is used to filter the displacement current signal, suppress the displacement current formed by the voltage to be measured, so as to highlight the displacement current formed by the first detection signal and the second detection signal, and obtain the frequency current signal. The microcontroller unit is used to determine the voltage to be measured based on the frequency current signal.

2. The apparatus according to claim 1, characterized in that, The microcontroller unit is used to perform Fourier transform on the frequency current signal to obtain a first detection current, a second detection current and a rated current, wherein the frequency of the first detection current is the first frequency, the frequency of the second detection current is the second frequency, and the frequency of the rated current is the rated frequency. The microcontroller unit is used to determine the voltage to be measured based on the first detection current, the second detection current, the rated current, and the detection voltage.

3. The apparatus according to claim 1, characterized in that, The frequency selection network module includes: a first-stage notch filter circuit and a second-stage notch filter circuit. The input terminal of the first-stage notch filter circuit is used to receive the displacement current signal, the output terminal of the first-stage notch filter circuit is connected to the input terminal of the second-stage notch filter circuit, and the output terminal of the second-stage notch filter circuit is used to output the frequency current signal.

4. The apparatus according to claim 3, characterized in that, The first-stage notch filter circuit includes: a first resistor, a second resistor, a third resistor, a first capacitor, a second capacitor, and a third capacitor. One end of the first resistor is used to receive the displacement current signal, and the other end of the first resistor is connected to a first node. One end of the second resistor is connected to the first node, and the other end of the second resistor is connected to the second-stage notch filter circuit. One end of the first capacitor is used to receive the displacement current signal, and the other end of the first capacitor is connected to a second node. One end of the second capacitor is connected to the second node, and the other end of the second capacitor is connected to the second-stage notch filter circuit. One end of the third capacitor is connected to the first node, and the other end of the third capacitor is grounded. One end of the third resistor is connected to the second node, and the other end of the third resistor is grounded.

5. The apparatus according to claim 3, characterized in that, The second-stage notch filter circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a fourth capacitor, a fifth capacitor, and a sixth capacitor. One end of the fourth resistor is connected to the first-stage notch filter circuit, and the other end of the fourth resistor is connected to a third node. One end of the fifth resistor is connected to the third node, and the other end of the fifth resistor is used to output the frequency current signal. One end of the fourth capacitor is connected to the first-stage notch filter circuit, and the other end of the fourth capacitor is connected to a fourth node. One end of the fifth capacitor is connected to the fourth node, and the other end of the fifth capacitor is used to output the frequency current signal. One end of the sixth capacitor is connected to the third node, and the other end of the sixth capacitor is grounded. One end of the sixth resistor is connected to the fourth node, and the other end of the sixth resistor is grounded.

6. The apparatus according to any one of claims 1 to 5, characterized in that, The voltage detection component further includes: an energy harvesting magnetic core, an energy harvesting coil, a protection module, and a power supply module. The energy harvesting magnetic core is used to be sleeved on the conductor under test. The energy harvesting coil is connected to the energy harvesting magnetic core. The protection module is connected to the energy harvesting coil and is used to acquire the induced voltage. The power supply module is connected to the protection module and is used to rectify the induced voltage to obtain the supply voltage.

7. The apparatus according to claim 6, characterized in that, The voltage detection component further includes a backup battery connected to the power module, the backup battery being used to store or provide electrical energy.

8. The apparatus according to claim 6, characterized in that, The voltage detection component further includes a wireless communication module, which is connected to the microcontroller unit and is used to wirelessly transmit the voltage to be measured.

9. The apparatus according to claim 6, characterized in that, The device further includes: The upper arm of the buckle is provided with an upper locking pad; The lower arm of the latch is rotatably connected to the upper arm of the latch. The lower arm of the latch is provided with a lower locking pad. The upper locking pad and the lower locking pad are used to form a receiving space for accommodating the wire to be tested.

10. The apparatus according to claim 9, characterized in that, The upper locking pad is connected to the upper arm of the buckle via a first spring, and the lower locking pad is connected to the lower arm of the buckle via a second spring.

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