A method and apparatus for cable voltage determination

Abstract

The application discloses a kind of cable voltage determination method and device, the method comprises: obtaining the differential voltage between each pair of probes in three pairs of probes in different directions around target cable;Determine the voltage U of target cable based on the three differential voltages obtained.This application is based on the principle of electric field radiation to induce the electric field intensity generated around the cable to be measured, and obtains the voltage signal of the line to be measured, with good adaptability, which can be applied to AC and DC voltage monitoring;The pair of metal detection points eliminates the potential error to ground and other errors in the measurement process caused by the measurement circuit itself.

Description

Technical Field

[0001] This invention relates to the field of non-contact voltage measurement technology, and in particular to a method and apparatus for determining cable voltage. Background Technology

[0002] Traditional cable voltage measurement mainly utilizes resistive voltage dividers or voltage transformers. This method requires direct electrical connection to the circuit being tested, which has drawbacks in terms of electrical isolation, on-site implementation, user requirements, and power loss. Furthermore, the equipment is relatively large, has relatively high manufacturing costs, and is difficult to maintain. Therefore, non-contact voltage measurement devices are needed for voltage measurement at points where it is neither possible nor convenient to damage the insulation layer, and where real-time voltage monitoring is required.

[0003] Non-contact voltage measurement systems are not limited by power grid levels. Non-contact voltage sensors generally have small output voltage values, are safe and reliable in operation, and have a long service life. Non-contact voltage measurement equipment has a simple structure, is easy to carry, and can be used for measurements without geographical restrictions. Non-contact measurement systems have no ferromagnetic parts, no saturation or other nonlinearities, and have good frequency response. Non-contact measurement systems have no direct electrical connection with the power transmission system, reducing electromagnetic interference during the measurement process and ensuring measurement accuracy.

[0004] Currently, non-contact voltage measurement methods based on the principle of electric field coupling between electrode plates are widely used. However, at some measurement points requiring high accuracy, traditional non-contact voltage measurement methods can introduce significant errors due to interference from the measurement environment. Therefore, current research on this measurement principle focuses on eliminating measurement errors. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for determining cable voltage. By using three pairs of centrally symmetrical metal detection points to sense the spatial electric field intensity generated by the cable under test, three induced differential voltages are obtained. These are then used to derive three algebraic equations concerning the voltage under test and the two-dimensional position parameters of the electric field center point. Solving these equations yields the voltage signal of the line under test, completing the non-contact measurement of the line voltage. To achieve the above objective, this invention provides the following technical solution:

[0006] A method for determining cable voltage, the method comprising:

[0007] Obtain the differential voltage between each pair of probes in three pairs of probes in different directions around the target cable;

[0008] The voltage U of the target cable is determined based on the three differential voltages obtained.

[0009] Furthermore, the voltage U of the target cable is determined based on the three acquired differential voltages, including:

[0010] Based on the distance R between the probe closest to the cable and the center of the cable in each of the three probe pairs, i The electric field strength E at the probe furthest from the cable in each of the three probe pairs. i (R i The dielectric constants of the conductor insulation layer (ε1), air (ε2), and insulating medium (ε3) are: the radius r0 of the cable aluminum core, the radius r1 of the cable containing the insulation layer, the distance d2 between the preceding probe and the shielding layer for each probe pair, and the angle θ between the line connecting the i-th probe pair and the center point of the cable's electric field intensity and the longitudinal axis y. i Establish a correlation with the voltage U of the target cable;

[0011] The voltage U of the target cable is determined based on the aforementioned correlation.

[0012] Furthermore, the aforementioned relationship is as follows:

[0013]

[0014] In the formula, R i E represents the distance between the probe closest to the cable and the center of the cable in the i-th probe pair; i (R i ) represents the electric field strength at the probe furthest from the cable in the i-th probe pair; ε1 represents the dielectric constant of the conductor insulation, ε2 represents the dielectric constant of air, ε3 represents the dielectric constant of the insulating medium, r0 represents the radius of the cable aluminum core, r1 represents the radius of the cable including the insulation layer, r2 represents the inner diameter of the sensor, d2 represents the distance between the preceding probe and the shielding layer in each probe pair, and θ i This represents the angle by which the line connecting the i-th probe pair to the center point of the cable's electric field strength deviates from the vertical axis y.

[0015] Furthermore, E i (R i The formula for calculating ) is:

[0016]

[0017] In the formula, d1 is the distance between each pair of probes.

[0018] Furthermore, R i The calculation formula is as follows:

[0019]

[0020] In the formula, x and y represent the position coordinates of the target cable axis P.

[0021] Furthermore, the target cable voltage U and the electric field strength E at the inner probes in the three directions R1, R2, and R3 are compared.i (R i By combining the relationship between R1, R2, and R3, the voltage U of the target cable can be obtained. The calculation formula is expressed as:

[0022]

[0023] A cable voltage determination device includes a sensor and a signal processing unit, wherein the sensor includes three pairs of probes.

[0024] Each of the three pairs of probes is distributed in a different direction around the target cable and is used for the voltage between each pair of probes.

[0025] The signal processing unit is used to determine the voltage U of the target cable based on the three acquired voltages.

[0026] Furthermore, the voltage U of the target cable is determined based on the three acquired voltages, including:

[0027] Based on the distance R between the probe closest to the cable and the center of the cable in each of the three probe pairs, i The electric field strength E at the probe furthest from the cable in each of the three probe pairs. i (R i The dielectric constants of the conductor insulation layer (ε1), air (ε2), and insulating medium (ε3) are: the radius r0 of the cable aluminum core, the radius r1 of the cable containing the insulation layer, the distance d2 between the preceding probe and the shielding layer for each probe pair, and the angle θ between the line connecting the i-th probe pair and the center point of the cable's electric field intensity and the longitudinal axis y. i Establish a correlation with the voltage U of the target cable;

[0028] The voltage U of the target cable is determined based on the aforementioned correlation.

[0029] Furthermore, the signal processing unit includes a bandpass filter, an analog-to-digital converter, and a data processor, wherein...

[0030] The bandpass filter is used to bandpass filter the differential voltage from the three pairs of probes.

[0031] The analog-to-digital converter is used to convert the signal output from the bandpass filter into an analog-to-digital signal.

[0032] The data processor is used to determine the voltage U of the target cable based on the three acquired differential voltages.

[0033] Furthermore, the sensor also includes an insulating separator layer, a metal shielding layer, and an insulating plastic housing, wherein,

[0034] The insulating separation layer is made of foam and is distributed between each pair of probes and between the probes and the metal shielding layer;

[0035] The metal shielding layer is a cylindrical copper foil, used to shield the cable from the influence of other sources around it.

[0036] The insulating plastic shell consists of a pair of semi-cylindrical surfaces that can be fastened together to form a complete cylindrical surface, with the metal shielding layer bonded to its inner surface.

[0037] The technical effects and advantages of this invention are as follows:

[0038] 1. This invention senses the electric field strength generated around the cable under test based on the principle of electric field radiation, and obtains the voltage signal of the line under test accordingly. It has good adaptability and can be applied to AC and DC voltage monitoring. The paired metal detection points eliminate potential ground errors caused by the measurement circuit itself and other errors in the measurement process.

[0039] 2. The voltage sensor of the present invention includes 2×3 (3 pairs) metal detection points and a metal shielding grounding layer. It has the characteristics of small size, easy to carry, and low manufacturing cost, which is conducive to large-scale production and application. Even if the cable to be measured is located at any position rather than the center of the sensor, the accuracy can be ensured to reach an acceptable level.

[0040] 3. The digital display platform used in the sensor of this invention is built based on MATLAB and C language, and can display the measured voltage value and waveform information.

[0041] This invention, based on the principle of electric field radiation, constructs a three-plate, dual-detection-point ring cable voltage measurement structure. The voltage of the cable under test and the location of its electric field center point are deduced from the differential voltage detected at the detection points. The advantages of this measurement system are: based on the theoretical analysis of the electric field around the cable, a system of three equations containing the coordinates of the center point is established to solve for the voltage to be measured. This eliminates the errors caused by the electric field center point of the cable not being at the geometric center of the cable, as well as the errors induced by the environmental electric field at the detection points, resulting in high measurement accuracy.

[0042] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures pointed out in the description and the drawings. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of the cable voltage determination device system of the present invention;

[0044] Figure 2This is a structural model of a three-electrode dual-detection-point sensor in a specific embodiment of the present invention;

[0045] Figure 3 The spatial medium distribution when the cable is located at the center of the sensor in a specific embodiment of the present invention;

[0046] Figure 4 This is a specific embodiment of the invention showing the eccentricity measurement of a three-pole dual-detection-point sensor;

[0047] Figure 5a This is an equivalent diagram of the electric field distribution along the direction of the first pole of the sensor when the cable is eccentric in a specific embodiment of the present invention;

[0048] Figure 5b This is an equivalent diagram of the electric field distribution along the direction of the second pole of the sensor when the cable is eccentric in a specific embodiment of the present invention;

[0049] Figure 5c This is an equivalent diagram of the electric field distribution in the direction of the third pole of the sensor when the cable is eccentric in a specific embodiment of the present invention;

[0050] Figure 6 This is a flowchart illustrating the formula derivation in a specific embodiment of the present invention;

[0051] Figure 7 This is a circuit diagram of a non-contact voltage measurement system based on a three-electrode dual-detection-point voltage sensor in a specific embodiment of the present invention.

[0052] Figure 8 This is a physical test scenario of the measurement system hardware device in a specific embodiment of the present invention. Detailed Implementation

[0053] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0054] To address the shortcomings of existing technologies, this invention discloses a method for determining cable voltage, the method comprising:

[0055] The sensor uses metal probes to acquire induced voltage signals between each of three pairs of probes in different directions around the target cable, and processes these induced voltage signals to obtain at least three sets of differential voltage signals for the target cable. The voltage U of the target cable is determined based on these at least three sets of differential voltage signals. The measured voltage result of the target cable is displayed on a digital platform.

[0056] In one specific embodiment of the present invention, combined with Figure 1 The signal processing includes:

[0057] In non-contact voltage measurement, the induced voltage signal acquired by each pair of probes in the sensor is filtered by a bandpass filter to obtain a well-structured analog voltage signal. The filtered analog voltage signal is then converted into a digital voltage signal via an analog-to-digital converter (A / D converter). Based on the digital voltage signal, the corresponding differential voltage is acquired. The number of metal probes in the sensor is greater than or equal to three. The number of differential voltages is the same as the number of metal probe pairs in the sensor, and the differential voltage acquired by the i-th metal probe pair is u. i The values ​​of i are 1, 2, 3, ... . The differential voltage is processed by the MCU to obtain the target cable voltage.

[0058] Figure 2 The figure illustrates a structural model of a three-electrode dual-detection-point voltage sensor according to a specific embodiment of the present invention. In the figure, the low-voltage transmission cable is a long, straight cylindrical conductor. The three-electrode dual-detection-point structure consists of three pairs of radially arranged, ring-shaped metal detection points (A, B, and C), an insulating separator layer, a metal shielding layer, and an insulating plastic shell. The three metal detection points are symmetrically distributed about the sensor center. Each metal detection point is composed of 3×2 identical iron probes. Each pair of probes is isolated by a separator layer and connected to a PCB circuit board for filtering, analog-to-digital conversion, and then processed by an MCU to calculate the voltage value to be measured. The insulating separator layer is made of foam and is distributed between each pair of probes and between the probes and the metal shielding layer. The metal shielding layer is a cylindrical copper foil, which can shield the influence of other sources around the cable. The insulating plastic shell consists of a pair of semi-cylindrical surfaces that can be fastened together to form a complete cylindrical surface, with the shielding copper foil adhered to its inner surface. The cable voltage determination method of the present invention highly relies on the key technical principles of this voltage sensor, the theoretical basis of which is described below.

[0059] First, the equation concerning the electric displacement vector in Maxwell's equations is: For Hamiltonian operators, The electric displacement vector, its equation can be integrated to obtain ρ f It is charge density, S is a closed surface, and q f This represents the total amount of free charge within the curved surface, and Gauss's law describes how charges generate an electric field. In reality, we can consider low-voltage transmission cables as long, straight cylindrical conductors. Ignoring the influence of the radial conduction time of the electromagnetic field, we can consider the electric field around the conductor as a quasi-electrostatic field. We can take a closed cylindrical Gaussian surface of length l and radius R, coaxially enclosing a unit length of conductor. Based on Gauss's law, integrating the electric displacement vector with respect to the Gaussian surface at radius R yields... Therefore, the electric displacement vector is From the corresponding property equation It can be seen that the electric field strength at a location R, a distance R from the center of the conductor, is: Where q is the total Gaussian surface charge of the conductor, ρ is the volume charge density of a single conductor in an overhead line, and ε is the dielectric constant of the medium at point R.

[0060] Taking low-voltage power transmission aluminum core cables as an example, Figure 3 The dielectric distribution of the sensor's spatial range is shown when the cable is located at the center of the sensor. Figure 3 In the diagram, r0 represents the radius of the cable's aluminum core, r1 represents the radius of the cable including the insulation layer, r2 is the inner diameter of the sensor, R is the radius of the metal wire core, d1 is the distance between each pair of probes, d2 is the distance between the preceding probe and the shielding layer of each pair of probes, ε1 is the dielectric constant of the wire insulation layer, ε2 is the dielectric constant of air, and ε3 is the dielectric constant of the insulating medium.

[0061] Figure 6 The process of deriving this system of equations is shown, and the derivation logic of the theory can be intuitively seen. Figure 6 :

[0062] Assuming the radius of the aluminum core conductor inside the cable is r0, the electric field distribution around the conductor is as follows.

[0063]

[0064] Depend on It can be seen that the potential difference between any two points in the space surrounding the cable can be expressed in the form of an electric field integral. That is:

[0065] In actual measurements, we wrap the three-pair pole-dual-probe electric field sensor with cable and ground the shielding layer. However, under normal circumstances, we cannot guarantee that the cable will be centered on the sensor, so we will explain the situation as a general case where the cable is off-center from the sensor.

[0066] Figure 4 The diagram illustrates an eccentric measurement using a three-pole dual-probe voltage sensor. In the figure, with the conductor's central axis positioned within the sensor center, the electric field distribution around the conductor differs along the three directions R1, R2, and R3. However, we can assume that the electric field intensity E near the probe in each direction is the same. i The electric field strength near the probe when the wire is at the center of the sensor, with R1, R2, and R3 being the radii of the shielding layer, can be considered as three equivalent cases, such as... Figures 5a-5c As shown, and satisfying the following functional relationship:

[0067]

[0068] From these relations (1) and formula (2), the voltage U of the target cable and its electric field strength E at the inner probe in three directions can be derived. i (R i The relationship between )

[0069]

[0070] In the formula, U represents the voltage of the target cable. Through formula (3), we determined the relationship between the voltage of the conductor to ground and the electric field strength around it.

[0071] Next, we measure the electric field strength E at the plate. i (R i The calculation of ) is as follows. Taking the sensor dual-probe substructure at point A as an example, we can obtain Figure 4 The electric field intensity at probe a.

[0072]

[0073] The voltage u1 between probe pair (dual probe) a and a' can be measured by an external sampling circuit, and the voltages u1′ and u1″ between the dual probe and the ground plane can be obtained by the following relationship.

[0074]

[0075]

[0076]

[0077] Therefore, we can obtain the electric field strength E1(R1) at the probe a position.

[0078]

[0079] Similarly, we can obtain the electric field intensity E in other directions. i (R i ).

[0080]

[0081] Combining equations (3) and (9), we can obtain a preliminary expression for the voltage U of the target cable, as shown below:

[0082]

[0083] Next, we analyze the position of the cable shaft center relative to the sensor center. To further simplify the positional relationships and more easily derive the mathematical relationship between distances R1, R2, and R3 and the relative position coordinates (x, y) of the cable shaft center. Figure 4 In the diagram, P is the cable axis, O is the sensor center point, and points A, B, and C represent the dual-probe substructures of voltage sensors ①, ②, and ③, respectively. We establish a Cartesian coordinate system with O as the origin, the line containing OA as the y-axis, and the line perpendicular to OA and passing through point O as the x-axis. The distances from the probes closest to the cable at the three points to the cable center P are R1, R2, and R3, respectively. The coordinates of the cable axis P are (x, y). ∠AOB = ∠BOC = ∠COA = 120°. Through geometric analysis, we can apply the Pythagorean theorem to obtain the relationship between the axis coordinates (x, y) and R1, R2, and R3.

[0084]

[0085] Based on the above theoretical formulas, we can obtain the following system of equations, which has three unknowns: U, x, and y, and satisfies the uniqueness of the solution.

[0086]

[0087] The voltage of the line under test is finally obtained by solving a system of equations. The solution formula is based on the theory of electric field radiation, and has only three unknowns: U, x, and y, which satisfies the condition that the system of equations has a unique solution.

[0088] Figure 6 The process of deriving this system of equations is shown, and the derivation logic of the theory can be seen intuitively.

[0089] The present invention also provides a cable voltage determination device, such as... Figure 1 As shown, the device includes a sensor and a signal processing unit. The sensor includes three pairs of probes, an insulating separator, a metal shielding layer, and an insulating plastic shell. The probe pairs are made of iron needles of the same shape, and each pair is symmetrically distributed about the center of the sensor. The insulating separator is made of foam and is distributed between each pair of probes and between the probes and the metal shielding layer. The metal shielding layer is a cylindrical copper foil used to shield the cable from the influence of other sources. The insulating plastic shell consists of a pair of semi-cylindrical surfaces that can be fastened together to form a complete cylindrical surface, with the metal shielding layer bonded to its inner surface.

[0090] Each of the three probe pairs is distributed in a different direction around the target cable and is used for the voltage between each probe pair; the signal processing unit is used to determine the voltage U of the target cable based on the three acquired voltages.

[0091] In one specific embodiment of the present invention, the determining device further includes a digital display platform, which is built based on MATLAB and C language, and is used to display information such as measured voltage values ​​and waveforms.

[0092] In one specific embodiment of the present invention, determining the voltage U of the target cable based on the three acquired voltages includes: determining the distance R between the probe closest to the cable and the center of the cable in each of the three probe pairs. i The electric field strength E at the probe furthest from the cable in each of the three probe pairs. i (R i The dielectric constants of the conductor insulation layer (ε1), air (ε2), and insulating medium (ε3) are: the radius r0 of the cable aluminum core, the radius r1 of the cable containing the insulation layer, the distance d2 between the preceding probe and the shielding layer for each probe pair, and the angle θ between the line connecting the i-th probe pair and the center point of the cable's electric field intensity and the longitudinal axis y. i Establish a correlation with the voltage U of the target cable;

[0093] The voltage U of the target cable is determined based on the aforementioned correlation.

[0094] In one specific embodiment of the present invention, the signal processing unit includes a bandpass filter, an analog-to-digital converter, and a data processor, wherein the bandpass filter is used to bandpass filter the voltage preceding each probe pair; the analog-to-digital converter is used to perform analog-to-digital conversion on the signal output from the bandpass filter; and the data processor is used to determine the voltage U of the target cable based on the three acquired voltages.

[0095] The present invention provides a device that ensures acceptable accuracy even when the cable to be measured is located anywhere other than the center of the sensor; the differential voltage measured by the paired detection points (probe pairs) eliminates potential ground errors caused by the measurement circuit itself and other errors in the measurement process; the sensor is suitable for AC and DC voltage monitoring; and the measurement results are ultimately displayed on a digital platform.

[0096] The three-pole dual-probe electric field sensor used in this invention infers the cable voltage by acquiring the electric field at the probe near the cable. In practice, it uses the electric field strength at the probe surface near the cable side. Furthermore, the cable selected for the measurement model is general; for some special cables, the voltage measured by this system will inevitably differ significantly. Moreover, the accuracy of the measurement results is independent of the cable position; even if the cable to be measured is located anywhere other than the center of the sensor, the accuracy can still be ensured to reach an acceptable level. Compared to traditional fixed-parameter non-contact measurement devices, the measurement results of this testing system are more accurate.

[0097] Figure 7 This shows that if there is an interfering electric field source A in the measurement environment, with coordinates (x', y') and electric field strength E, then... r, and its distance from the center point of the cable to be measured is D0. Taking the a-a' detection point as an example, the distance between point A and a is D1, and the distance between a' is D2. Then the interference electric field intensity sensed by the detection point is:

[0098]

[0099] Since D0 >> R0 (sensor radius), and the spacing between a-a' << D1 and D2, this makes D1 ≈ D2, then E ra ≈ E ra’ , from which we can obtain:

[0100]

[0101] Among them, E ra , E ra’ are the interference electric field intensities sensed at the detection points a and a' respectively; u′ error1 , u″ error1 are the interference voltages to the ground measured at the detection points a and a' respectively; u error 1 is the interference differential voltage measured at the detection point a-a'; D1' is the distance from the connection line between the detection point a' and the interference electric field source A to the shielding layer; D2' is the distance from the connection line between the detection point a and the interference electric field source A to the shielding layer.

[0102] From the above analysis, it can be seen that by using the method of the present invention for non-contact voltage measurement, the measurement environment error signal in this embodiment can be eliminated, and the measurement accuracy can be effectively improved.

[0103] Figure 8 shows a non-contact voltage measurement circuit diagram based on a three-pole - double-probe voltage sensor.

[0104] The sensor's three pairs of probes acquire the potential difference between each pair in the electric field space, serving as the input voltage signals for the circuit processing module, named u1, u2, and u3 respectively. Next, the three voltage signals undergo a series of processing steps in the signal processing circuit, including a filtering module, an A / D conversion module, and an MCU digital processing module. The filtering module contains three identical filtering circuits, each with its input connected to a dual probe to receive the input voltage signal. After filtering by these three circuits, the signal is output to the A / D conversion module. The filtered output voltage signal is an analog signal. To facilitate data processing by the MCU data processing module, the A / D conversion module converts this analog signal into a digital signal. In this embodiment, an analog-to-digital converter (ADC) is used to digitize the analog signal. For the nominal 50Hz input signal, the ADC can sample the output signal from the signal processing circuit at a sampling frequency of 10.24kHz for convenience, providing 1024 samples in 100ms to prepare for Fast Fourier Transform and voltage reconstruction algorithm processing in the MCU data processing module. The MCU data processing module acquires the digital signal output from the digital-to-analog converter module, and uses a computer program to solve the voltage under test by writing a voltage reconstruction equation set, obtaining and displaying the accurate measurement result. This measurement system performs non-contact voltage measurement via a single wire, and can measure both DC and AC voltages, making it convenient to operate and highly practical.

[0105] This invention, based on the principle of electric field radiation, constructs a three-plate, dual-detection-point ring cable voltage measurement structure. The voltage of the cable under test and the location of its electric field center point are deduced from the differential voltage detected at the detection points. The advantages of this measurement system are: based on the theoretical analysis of the electric field around the cable, a system of three equations containing the coordinates of the center point is established to solve for the voltage to be measured. This eliminates the errors caused by the electric field center point of the cable not being at the geometric center of the cable, as well as the errors induced by the environmental electric field at the detection points, resulting in high measurement accuracy.

[0106] The physical test scenario of the hardware device of the voltage non-contact measurement system described in this invention.

[0107] The hardware of this measurement system consists of a sensor probe and two circuit boards connected by an HDMI interface. One circuit board contains a signal input interface and signal processing circuitry, while the other circuit board contains data processing circuitry, a data transmission interface, and a power interface.

[0108] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining cable voltage, characterized in that, The method includes: Obtain the differential voltage between each pair of probes in three pairs of probes in different directions around the target cable; The voltage U of the target cable is determined based on the three acquired differential voltages, where, Where i = 1, 2, 3, In the formula, R i E represents the distance between the probe closest to the cable and the center of the cable in the i-th probe pair; i (R i ) represents the electric field strength at the probe furthest from the cable in the i-th probe pair; ε1 represents the dielectric constant of the conductor insulation, ε2 represents the dielectric constant of air, ε3 represents the dielectric constant of the insulating medium, r0 represents the radius of the cable aluminum core, r1 represents the radius of the cable including the insulation layer, r2 represents the inner diameter of the sensor, d2 represents the distance between the preceding probe and the shielding layer in each probe pair, and θ i This represents the angle by which the line connecting the i-th probe pair to the center point of the cable's electric field strength deviates from the vertical axis y; E i (R i The formula for calculating ) is: ，i=1,2,3， In the formula, d1 represents the distance between each pair of probes, u i This represents the differential voltage acquired by the i-th probe pair; R i The calculation formula is as follows: In the formula, x and y represent the position coordinates of the target cable axis P, and R0 represents the radius of the sensor shielding layer; The target cable voltage U and the electric field intensity E at the inner probes in the three directions R1, R2, and R3 are compared. i (R i By combining the relationship between R1, R2, and R3, the voltage U of the target cable can be obtained. The calculation formula is expressed as: 。 2. A cable voltage determining device, characterized in that, The device is used in the cable voltage determination method of claim 1, and the device includes a sensor and a signal processing unit, wherein the sensor includes three pairs of probes. Each of the three probe pairs is distributed in different directions around the target cable and is used to obtain the differential voltage between each probe pair. The signal processing unit is used to determine the voltage U of the target cable based on the three acquired differential voltages.

3. The determining device according to claim 2, characterized in that, The voltage U of the target cable is determined based on the three acquired voltages, including: Based on the distance R between the probe closest to the cable and the center of the cable in each of the three probe pairs, i The electric field strength E at the probe furthest from the cable in each of the three probe pairs. i (R i The dielectric constants of the conductor insulation layer (ε1), air (ε2), and insulating medium (ε3) are: the radius r0 of the cable aluminum core, the radius r1 of the cable containing the insulation layer, the distance d2 between the preceding probe and the shielding layer for each probe pair, and the angle θ between the line connecting the i-th probe pair and the center point of the cable's electric field intensity and the longitudinal axis y. i Establish a correlation with the voltage U of the target cable; The voltage U of the target cable is determined based on the aforementioned correlation.

4. The determining device according to claim 2 or 3, characterized in that, The signal processing unit includes a bandpass filter, an analog-to-digital converter, and a data processor, wherein... The bandpass filter is used to bandpass filter the differential voltage from the three pairs of probes. The analog-to-digital converter is used to convert the signal output from the bandpass filter into an analog-to-digital signal. The data processor is used to determine the voltage U of the target cable based on the three acquired differential voltages.

5. The determining device according to claim 2 or 3, characterized in that, The sensor also includes an insulating separator layer, a metal shielding layer, and an insulating plastic housing, wherein, The insulating separation layer is made of foam and is distributed between each pair of probes and between the probes and the metal shielding layer; The metal shielding layer is a cylindrical copper foil, used to shield the cable from the influence of other sources around it. The insulating plastic shell consists of a pair of semi-cylindrical surfaces that can be fastened together to form a complete cylindrical surface, with the metal shielding layer bonded to its inner surface.

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