Non-contact single-phase alternating-current voltage measuring device and method
By using a non-contact single-phase AC voltage measuring device and a probe with a multi-layer metal and insulation structure, combined with a capacitive coupling equivalent circuit model, voltage measurement without calibration is achieved. This solves the problems of high cost and complexity of traditional measuring devices and is suitable for flexible deployment in new energy power plants.
Patent Information
- Application Number
- CN202511321834.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-16
- Publication Date
- 2025-11-18
AI Technical Summary
Existing non-contact voltage measurement devices require calibration and are inconvenient to operate. Furthermore, traditional contact measurement equipment is costly and complex to install, making it difficult to meet the flexible deployment needs of new energy power plants.
A non-contact single-phase AC voltage measuring device is used, including a probe with a multi-layer metal and insulation structure. An equation system is constructed through a capacitive coupling equivalent circuit model, and the voltage to be measured is solved in reverse, avoiding direct metal contact and calibration process.
It enables efficient and convenient voltage measurement without damaging the insulation or making direct metal contact, reducing engineering complexity and safety risks, and is suitable for large-scale measurement deployment in areas with a high proportion of new energy sources.
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Figure CN120971804A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of voltage measurement, in particular to a non-contact single-phase alternating current voltage measurement device and method. BACKGROUND
[0002] With the large-scale access of high-proportion new energy to the power system, the complexity and dynamics of power grid operation are significantly enhanced, and higher requirements are put forward for real-time synchronous measurement of electrical quantities. However, the existing synchronous measurement devices are mostly configured in 220kV and above high-voltage transmission substations, and the voltage monitoring points need to be extended to the internal of the new energy high-penetration area. However, the new energy high-proportion area is widely distributed and has complex topology, and the number of required points is much higher than that of the high-voltage transmission network, and most of the areas are not installed with voltage transformers, and when voltage monitoring is performed, there are problems of few voltage transformers, complex electrical quantity characteristics, and many points. This puts high requirements on the low cost of the device.
[0003] Traditional contact-type measurement devices such as voltage transformers have problems of high manufacturing cost, large metal consumption, complicated installation process, and poor measurement accuracy, which are difficult to meet the needs of flexible deployment of distributed new energy stations. And for safety considerations, the installation of voltage transformers needs to cut off the power supply, and the operation convenience is poor.
[0004] The non-contact measurement method provides a basis for the measurement device to realize massive point deployment in the new energy area due to its flexibility and safety. Most of the existing non-contact voltage measurement systems need to be calibrated before being put into use, which affects the installation convenience of the device. Some voltage measurement methods need to be assisted by voltage sources with known parameters, which increases the complexity of the measurement device. SUMMARY
[0005] The purpose of the present application is to provide a non-contact single-phase alternating current voltage measurement device and method, which solves the problem of inconvenient measurement operation of the existing non-contact measurement which needs to be calibrated.
[0006] To achieve the above purpose, the present application provides a non-contact single-phase alternating current voltage measurement device, comprising:
[0007] The first probe comprises a first inner metal layer and a first outer metal layer, and a first insulating layer is arranged between the first inner metal layer and the first outer metal layer. The first inner metal layer is wrapped outside the insulating skin of the conductor, and the first outer metal layer is wrapped outside the first insulating layer;
[0008] The second probe comprises a second outer metal layer, a second outer insulating layer, a second inner metal layer and a second inner insulating layer which are sequentially wrapped from outside to inside. The second inner insulating layer is wrapped outside the insulating skin of the conductor;
[0009] The third probe comprises, from outside to inside, a third outer metal layer, a third outer insulating layer, a third inner metal layer, a third middle insulating layer, and a third inner insulating layer, and the third inner insulating layer is wrapped outside the wire insulating skin.
[0010] The conditioning circuit and the sampling circuit, the input end of the conditioning circuit is connected with the first inner metal layer, the second inner metal layer, and the third inner metal layer through wires, the output end of the conditioning circuit is connected with the input end of the sampling circuit, and the common reference terminal of the sampling circuit is grounded.
[0011] The first outer metal layer, the second outer metal layer, and the third outer metal layer are grounded through wires.
[0012] Preferably, the first insulating layer, the second inner insulating layer, the third inner insulating layer, the second outer insulating layer, the third outer insulating layer, and the third middle insulating layer have the same material and thickness.
[0013] Preferably, the first inner metal layer, the first outer metal layer, the second inner metal layer, the second outer metal layer, the third inner metal layer, and the third outer metal layer have the same material and thickness.
[0014] Preferably, the first inner metal layer and the first insulating layer are 0.8-1.2 times the thickness of the wire insulating skin.
[0015] The measurement method based on the above non-contact single-phase alternating voltage measurement device comprises the following steps:
[0016] S1, the radii of the first inner metal layer, the first outer metal layer, the second inner metal layer, the second outer metal layer, the third inner metal layer, the third outer metal layer, the first insulating layer, the second inner insulating layer, the third inner insulating layer, the second outer insulating layer, the third outer insulating layer, the third middle insulating layer, the wire insulating skin, and the wire core are measured respectively;
[0017] S2, the first probe, the second probe, and the third probe are constructed outside the single-phase cable to be measured including the wire core and the wire insulating skin;
[0018] S3, the first inner metal layer, the second inner metal layer, and the third inner metal layer are connected with the conditioning circuit through wires, the first outer metal layer, the second outer metal layer, and the third outer metal layer are grounded through wires, and the conditioning circuit is connected with the sampling circuit;
[0019] S4, the output voltage between the first inner metal layer and the first outer metal layer, the output voltage between the second inner metal layer and the second outer metal layer, and the output voltage between the third inner metal layer and the third outer metal layer are measured and recorded through the sampling circuit;
[0020] S5, an equation group is constructed based on a capacitance coupling equivalent circuit model, and the voltage to be measured is solved reversely.
[0021] Preferably, in S2, the specific process of constructing the first probe outside the single-phase cable to be measured is as follows:
[0022] The rectangular first inner metal layer is tightly wrapped around the conductor insulation skin to form a cylindrical structure without overlapping parts, and the first inner metal layer is connected to the conditioning circuit through the conductor;
[0023] A first insulating layer and a first outer metal layer with the same shape and size as the first inner metal layer are tightly wrapped outside the first inner metal layer from inside to outside to form a cylindrical structure, and the first outer metal layer is grounded through the conductor.
[0024] Preferably, in S2, the specific process of constructing the second probe outside the single-phase cable to be measured is as follows:
[0025] The rectangular second inner insulating layer is tightly wrapped around the conductor insulation skin to form a cylindrical structure without overlapping parts;
[0026] A second inner metal layer, a second outer insulating layer, and a second outer metal layer with the same shape and size as the second inner insulating layer are tightly wrapped outside the second inner insulating layer from inside to outside to form a cylindrical structure, the second outer metal layer is grounded through the conductor, and the second inner metal layer is connected to the conditioning circuit through the conductor.
[0027] Preferably, in S2, the specific process of constructing the third probe outside the single-phase cable to be measured is as follows:
[0028] The rectangular third inner insulating layer is tightly wrapped around the conductor insulation skin to form a cylindrical structure without overlapping parts;
[0029] A third inner metal layer, a third outer insulating layer, and a third outer metal layer with the same shape and size as the third inner insulating layer are tightly wrapped outside the third inner insulating layer from inside to outside to form a cylindrical structure, the third outer metal layer is grounded through the conductor, and the third inner metal layer is connected to the conditioning circuit through the conductor.
[0030] Preferably, in S5, the specific process of constructing the equation set based on the equivalent circuit model of capacitive coupling and inversely solving the measured voltage is as follows:
[0031] S51, the relationship between the first probe output voltage and the measured voltage is derived from the equivalent circuit model composed of the inner layer coupling capacitor and the outer layer coupling capacitor, and the expression of the inner layer capacitor C i and the outer layer capacitor C o is as follows:
[0032]
[0033] Wherein, R0 is the radius of the wire core, R1 is the inner radius of the first inner metal layer, R2 is the outer radius of the first inner metal layer, R3 is the inner radius of the first outer metal layer, L is the length of the probe along the direction of the measured wire, and ε is the dielectric constant of the first insulating layer and the second insulating layer.
[0034] S52, the impedance division relationship is used to obtain the equation group of the first probe.
[0035]
[0036] Wherein, D1 is the thickness of the first inner metal layer and the first outer metal layer, D2 is the thickness of the first insulating layer, U o1 is the output voltage of the first probe, U i is the measured voltage.
[0037] S53, the equation group of the second probe is:
[0038]
[0039] Wherein, U o2 is the output voltage of the second probe.
[0040] The equation group of the third probe is:
[0041]
[0042] Wherein, U o3 is the output voltage of the third probe.
[0043] S54, the first probe equation group and the second probe equation group are used to eliminate R0 to obtain the function relationship U i =f(R1),
[0044]
[0045] The first probe equation group and the third probe equation group are used to eliminate R0 to obtain the function relationship U i =g(R1),
[0046]
[0047] S55, the function F(R1)=f(R1)-g(R1) is constructed, and the zero point of F(R1) is numerically solved by using the dichotomy method.
[0048] S56, the zero point value is substituted into the first probe equation group, the second probe equation group and the third probe equation group in turn, and the transfer coefficient matrix K is calculated,
[0049]
[0050] Wherein, k1 is the transfer coefficient of the first probe, k2 is the transfer coefficient of the second probe, and k3 is the transfer coefficient of the third probe.
[0051] S57, calculating the final calculation value of the to-be-measured voltage by using k1, k2 and k3,
[0052]
[0053] The non-contact single-phase alternating current voltage measuring device and method have the following advantages and positive effects:
[0054] 1. The method does not need to damage the insulation skin of the to-be-measured conductor or directly contact the metal, can be deployed in situ on the live conductor, and greatly reduces the engineering complexity and safety risk.
[0055] 2. The application directly derives the voltage transfer coefficients k1, k2 and k3 through physical parameters, without the need for calibration, and improves the convenience of voltage measurement.
[0056] 3. The application overcomes the hindering effect of the insulation layer of the medium and low voltage line, and conveniently and efficiently realizes the non-contact measurement of the voltage at the massive to-be-measured nodes in the new energy high-occupancy area without the need for calibration process and additional power supply assistance.
[0057] The technical solutions of the application will be further described in detail below with reference to the drawings and examples. BRIEF DESCRIPTION OF DRAWINGS
[0058] Figure 1 It is a first probe structure schematic diagram of the embodiment of the application.
[0059] Figure 2 It is a second probe structure schematic diagram of the embodiment of the application.
[0060] Figure 3 It is a third probe structure schematic diagram of the embodiment of the application.
[0061] Figure 4 It is a measurement method flowchart of the embodiment of the application.
[0062] Figure 5 It is an equivalent circuit diagram of the probe when solving in reverse of the embodiment of the application.
[0063] Figure 6 It is a flowchart of solving the to-be-measured voltage value of the embodiment of the application.
[0064] REFERENCE NUMERALS
[0065] 1, first inner metal layer; 2, first insulating layer; 3, first outer metal layer; 4, conductor insulating skin; 5, conductor core; 6, second inner insulating layer; 7, second inner metal layer; 8, second outer insulating layer; 9, second outer metal layer; 10, third inner insulating layer; 11, third middle insulating layer; 12, third inner metal layer; 13, third outer insulating layer; 14, third outer metal layer. DETAILED DESCRIPTION
[0066] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In the description of the present application, it should be noted that, unless otherwise specified and limited, the terms "arrangement", "installation", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.
[0067] In the present application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as understood by those skilled in the art to which the present application belongs. If there is any inconsistency, the meaning described in the specification or derived from the content described in the specification shall prevail. In addition, the terms used herein are only for the purpose of describing the embodiments of the present application and are not intended to limit the present application.
[0068] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.
[0069] As shown in Figure 1 , Figure 2 , Figure 3 A non-contact single-phase alternating voltage measuring device, comprising:
[0070] The first probe comprises a first inner metal layer 1 and a first outer metal layer 3, and a first insulating layer 2 is arranged between the first inner metal layer 1 and the first outer metal layer 3. The first inner metal layer 1 is wrapped outside the conductor insulating skin 4, and the first outer metal layer 3 is wrapped outside the first insulating layer 2.
[0071] The second probe comprises a second outer metal layer 9, a second outer insulating layer 8, a second inner metal layer 7 and a second inner insulating layer 6 wrapped outside in turn, and the second inner insulating layer 6 is wrapped outside the conductor insulating skin 4.
[0072] The third probe includes a third outer metal layer 14, a third outer insulation layer 13, a third inner metal layer 13, a third middle insulation layer 11, and a third inner insulation layer 10, which are sequentially wrapped from the outside to the inside. The third inner insulation layer 10 is wrapped around the outside of the wire insulation sheath 4.
[0073] The conditioning circuit and the sampling circuit are connected by wires to the first inner metal layer 1, the second inner metal layer 7, and the third inner metal layer 13. The output of the conditioning circuit is connected to the input of the sampling circuit, and the common reference terminal of the sampling circuit is grounded.
[0074] The first outer metal layer 3, the second outer metal layer 9, and the third outer metal layer 14 are all grounded through wires.
[0075] The first insulating layer 2, the second inner insulating layer 6, the third inner insulating layer 10, the second outer insulating layer 8, the third outer insulating layer 13, and the third middle insulating layer 11 are made of the same material and have the same thickness.
[0076] The first inner metal layer 1, the first outer metal layer 3, the second inner metal layer 7, the second outer metal layer 9, the third inner metal layer 13, and the third outer metal layer 14 are made of the same material and have the same thickness. The metal layers can be made of copper or other conductive metal materials. The metal layers have a foil-like structure for easy wrapping.
[0077] The metal layer and insulation layer are 0.8-1.2 times the thickness of the conductor insulation layer 4, preferably equal to the thickness of the conductor insulation layer 4.
[0078] like Figure 4 As shown, the measurement method based on the above-mentioned non-contact single-phase AC voltage measuring device includes the following steps:
[0079] S1. Measure the radii of the first inner metal layer 1, the first outer metal layer 3, the second inner metal layer 7, the second outer metal layer 9, the third inner metal layer 13, the third outer metal layer 14, the first insulation layer 2, the second inner insulation layer 6, the third inner insulation layer 10, the second outer insulation layer 8, the third outer insulation layer 13, the third middle insulation layer 11, the conductor insulation sheath 4, and the conductor core 5, respectively.
[0080] S2. Construct a first probe, a second probe, and a third probe on the outside of the single-phase cable under test, including the conductor core 5 and the conductor insulation sheath 4.
[0081] S3. Connect the first inner metal layer 1, the second inner metal layer 7, and the third inner metal layer 13 to the conditioning circuit through wires. Ground the first outer metal layer 3, the second outer metal layer 9, and the third outer metal layer 14 through wires. Connect the conditioning circuit to the sampling circuit.
[0082] S4, measure and record the output voltage between the first inner metal layer 1 and the first outer metal layer 3, the output voltage between the second inner metal layer 7 and the second outer metal layer 9, and the output voltage between the third inner metal layer 13 and the third outer metal layer 14 through the sampling circuit.
[0083] S5, based on the equivalent circuit model of capacitive coupling, construct an equation group and inversely solve the measured voltage.
[0084] In S2, the specific process of constructing the first probe outside the single-phase cable to be measured is as follows:
[0085] The rectangular first inner metal layer 1 is tightly wrapped around the wire insulation 4 to form a cylindrical structure without overlapping parts, and the first inner metal layer 1 is connected to the conditioning circuit through the wire.
[0086] Outside the first inner metal layer 1, the first insulating layer 2 and the first outer metal layer 3 are tightly wrapped from inside to outside in order, and a cylindrical structure is formed, and the first outer metal layer 3 is grounded through the wire.
[0087] In S2, the specific process of constructing the second probe outside the single-phase cable to be measured is as follows:
[0088] The rectangular second inner insulating layer 6 is tightly wrapped around the wire insulation 4 to form a cylindrical structure without overlapping parts.
[0089] Outside the second inner insulating layer 6, the second inner metal layer 7, the second outer insulating layer 8 and the second outer metal layer 9 are tightly wrapped from inside to outside in order, and a cylindrical structure is formed, and the second outer metal layer 9 is grounded through the wire, and the second inner metal layer 7 is connected to the conditioning circuit through the wire.
[0090] In S2, the specific process of constructing the third probe outside the single-phase cable to be measured is as follows:
[0091] The rectangular third inner insulating layer 10 is tightly wrapped around the wire insulation 4 to form a cylindrical structure without overlapping parts.
[0092] Outside the third inner insulating layer 10, the third inner metal layer 13, the third outer insulating layer 13 and the third outer metal layer 14 are tightly wrapped from inside to outside in order, and a cylindrical structure is formed, and the third outer metal layer 14 is grounded through the wire, and the third inner metal layer 13 is connected to the conditioning circuit through the wire.
[0093] As shown in Figure 6 In S5, based on the equivalent circuit model of capacitive coupling, the specific process of constructing an equation group and inversely solving the measured voltage is as follows:
[0094] S51, measure the voltage between the first inner metal layer 1 and the first outer metal layer 3 in the first probe, the voltage between the second inner metal layer 7 and the second outer metal layer 9 in the second probe, and the voltage between the third inner metal layer 13 and the third outer metal layer 14 in the third probe as output voltage signals U o1 o2 o3 .
[0095] According to Gauss theorem, the radial electric field intensity distribution of the first probe is as follows:
[0096]
[0097] Wherein, E is the electric field intensity, k is the charge amount on the unit length conductor, ε is the dielectric constant of the first insulating layer 2, R0 is the radius of the conductor core 5, R1 is the inner radius of the first inner metal layer 1, R2 is the outer radius of the first inner metal layer 1, and R3 is the inner radius of the first outer metal layer 3.
[0098] Therefore, the output voltage of the first probe is:
[0099]
[0100] The measured voltage can be expressed as:
[0101]
[0102] The conductor core 5 and the first inner metal layer 1 form an inner coupling capacitor, and the first inner metal layer 1 and the first outer metal layer 3 form an outer coupling capacitor.
[0103] The expression of the inner capacitor C i and the outer capacitor C o is:
[0104]
[0105] Wherein, R0 is the radius of the conductor core 5, R1 is the inner radius of the first inner metal layer 1, R2 is the outer radius of the first inner metal layer 1, R3 is the inner radius of the first outer metal layer 3, L is the length of the probe along the measured conductor, ε is the dielectric constant of the first insulating layer 2 and the second insulating layer, and U i is the measured voltage.
[0106] S52, refer to Figure 5 , the inner capacitor C i and the outer capacitor C o are connected in series, and there is a capacitive reactance voltage division relationship between them:
[0107]
[0108] Wherein s is a complex variable. By substituting equation (4) and equation (5), the equation corresponding to the first probe can be obtained;
[0109]
[0110] Wherein, D1 is the first inner metal layer 1, the first outer metal layer 3 thickness, D2 is the first insulating layer 2 thickness.
[0111] S53, similarly, for the second probe, refer to Figure 2 , the wire core 5 and the second inner metal layer 7 constitute the inner layer coupling capacitor, the second inner metal layer 7 and the second outer metal layer 9 constitute the outer layer coupling capacitor, both are in series relationship, the size is respectively:
[0112]
[0113] Both exist voltage division relationship:
[0114]
[0115] Wherein s is a complex variable. The equation corresponding to the second probe can be obtained by substituting equation (8) and equation (9) into the above equation:
[0116]
[0117] For the third probe, refer to Figure 3 , the wire core 5 and the third inner metal layer 13 constitute the inner layer coupling capacitor, the third inner metal layer 13 and the third outer metal layer 14 constitute the outer layer coupling capacitor, both are in series relationship, the size is respectively:
[0118]
[0119] Both exist voltage division relationship:
[0120]
[0121] Wherein s is a complex variable. The equation corresponding to the third probe can be obtained by substituting equation (12) and equation (13) into the above equation:
[0122]
[0123] S54, using the first probe equation group (7) and the second probe equation group (11) to eliminate R0 to obtain the function relationship formula U i =f(R1),
[0124]
[0125] Using the first probe equation group (7) and the third probe equation group (15) to eliminate R0 to obtain the function relationship formula U i =g(R1),
[0126]
[0127] S55, construct a function F (R1) = f (R1) - g (R1), and solve the zero point of F (R1) by using the numerical method of dichotomy.
[0128] S56, substitute the zero point value into the first probe equation group, the second probe equation group and the third probe equation group in sequence, and calculate the transfer coefficient matrix K,
[0129]
[0130] Wherein, k1 is the transfer coefficient of the first probe, k2 is the transfer coefficient of the second probe, and k3 is the transfer coefficient of the third probe.
[0131] S57, calculate the final calculation value of the measured voltage by using k1, k2 and k3,
[0132]
[0133] Therefore, the non-contact single-phase alternating voltage measuring device and method can solve the problem of calibration and inconvenient operation of the existing non-contact measurement.
[0134] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: it can still modify or replace the technical solutions of the present application, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.
Claims
1. A non-contact single-phase AC voltage measuring device, characterized in that, include: The first probe includes a first inner metal layer and a first outer metal layer, with a first insulating layer disposed between the first inner metal layer and the first outer metal layer. The first inner metal layer is wrapped around the outside of the wire insulation, and the first outer metal layer is included outside the first insulating layer. The second probe includes a second outer metal layer, a second outer insulation layer, a second inner metal layer, and a second inner insulation layer, which are sequentially wrapped from the outside to the inside. The second inner insulation layer is wrapped around the outside of the wire insulation. The third probe includes a third outer metal layer, a third outer insulation layer, a third inner metal layer, a third middle insulation layer, and a third inner insulation layer, which are sequentially wrapped from the outside to the inside. The third inner insulation layer is wrapped around the outside of the wire insulation. The conditioning circuit and the sampling circuit are connected by wires to the first inner metal layer, the second inner metal layer and the third inner metal layer. The output of the conditioning circuit is connected to the input of the sampling circuit. The common reference terminal of the sampling circuit is grounded. The first outer metal layer, the second outer metal layer, and the third outer metal layer are all grounded through wires.
2. The non-contact single-phase AC voltage measuring device according to claim 1, characterized in that: The first insulating layer, the second inner insulating layer, the third inner insulating layer, the second outer insulating layer, the third outer insulating layer, and the third middle insulating layer are made of the same material and have the same thickness.
3. The non-contact single-phase AC voltage measuring device according to claim 2, characterized in that: The first inner metal layer, the first outer metal layer, the second inner metal layer, the second outer metal layer, the third inner metal layer, and the third outer metal layer are made of the same material and have the same thickness.
4. The non-contact single-phase AC voltage measuring device according to claim 3, characterized in that: The first inner metal layer and the first insulating layer are 0.8-1.2 times the thickness of the wire insulation.
5. A measurement method based on the non-contact single-phase AC voltage measuring device according to claim 4, characterized in that, Includes the following steps: S1. Measure the radii of the first inner metal layer, the first outer metal layer, the second inner metal layer, the second outer metal layer, the third inner metal layer, the third outer metal layer, the first insulation layer, the second inner insulation layer, the third inner insulation layer, the second outer insulation layer, the third outer insulation layer, the third middle insulation layer, the wire insulation sheath, and the wire core, respectively. S2. Construct a first probe, a second probe, and a third probe on the outside of the single-phase cable under test, including the conductor core and the conductor insulation. S3. Connect the first inner metal layer, the second inner metal layer, and the third inner metal layer to the conditioning circuit through wires, and ground the first outer metal layer, the second outer metal layer, and the third outer metal layer through wires. Connect the conditioning circuit to the sampling circuit. S4. Measure and record the output voltage between the first inner metal layer and the first outer metal layer, the output voltage between the second inner metal layer and the second outer metal layer, and the output voltage between the third inner metal layer and the third outer metal layer through the sampling circuit; S5. Construct a set of equations based on the equivalent circuit model of capacitive coupling, and solve the voltage to be measured in reverse.
6. The non-contact single-phase AC voltage measurement method according to claim 5, characterized in that: In step S2, the specific process of constructing the first probe outside the single-phase cable under test is as follows: The rectangular first inner metal layer is tightly wrapped around the wire insulation to form a cylindrical structure without overlapping parts. The first inner metal layer is connected to the conditioning circuit through the wire. A first insulating layer and a first outer metal layer, which are the same shape and size as the first inner metal layer, are tightly wrapped around the outside of the first inner metal layer from the inside out to form a cylindrical structure. The first outer metal layer is grounded through a wire.
7. The non-contact single-phase AC voltage measurement method according to claim 5, characterized in that: In step S2, the specific process of constructing a second probe outside the single-phase cable under test is as follows: The rectangular second inner insulation layer is tightly attached to the wire insulation layer to form a cylindrical structure with no overlapping parts; A second inner metal layer, a second outer insulation layer, and a second outer metal layer, all of the same shape and size as the second inner insulation layer, are tightly wrapped around the outside of the second inner insulation layer from the inside out, forming a cylindrical structure. The second outer metal layer is grounded through a wire, and the second inner metal layer is connected to the conditioning circuit through a wire.
8. The non-contact single-phase AC voltage measurement method according to claim 5, characterized in that: In step S2, the specific process of constructing a third probe outside the single-phase cable under test is as follows: The rectangular third inner insulation layer is tightly attached to the wire insulation to form a cylindrical structure with no overlapping parts; A cylindrical structure is formed by tightly wrapping a third middle insulation layer, a third inner metal layer, a third outer insulation layer, and a third outer metal layer, all of the same shape and size as the third inner insulation layer, from the inside out. The third outer metal layer is grounded through a wire, and the third inner metal layer is connected to the conditioning circuit through a wire.
9. The non-contact single-phase AC voltage measurement method according to claim 5, characterized in that, In step S5, the specific process of constructing a system of equations based on the capacitive coupling equivalent circuit model and solving for the voltage to be measured in reverse is as follows: S51. The relationship between the output voltage of the first probe and the voltage to be measured is derived from the equivalent circuit model composed of the inner and outer coupling capacitors. The inner capacitor C i With outer capacitance C o The expression is: Where R0 is the conductor core radius, R1 is the inner radius of the first inner metal layer, R2 is the outer radius of the first inner metal layer, R3 is the inner radius of the first outer metal layer, L is the length of the probe along the direction of the conductor to be tested, and ε is the dielectric constant of the first insulation layer and the second insulation layer. S52. Using the capacitive reactance voltage divider relationship, the equation set for the first probe is obtained; Where D1 is the thickness of the first inner metal layer and the first outer metal layer, D2 is the thickness of the first insulating layer, and U o1 U is the output voltage of the first probe. i The voltage to be measured; S53, The equation set for the second probe is: Among them, U o2 This is the output voltage of the second probe; The equations for the third probe are: Among them, U o3 This refers to the output voltage of the third probe. S54. Eliminate R0 using the equations of the first and second probes to obtain the functional relationship U. i =f(R1), By eliminating R0 using the equations from the first and third probes, the functional relationship U is obtained. i =g(R1), S55. Construct the function F(R1) = f(R1) - g(R1), and use the bisection method to numerically solve for the zeros of F(R1); S56. Substitute the zero-point value into the equations of the first probe, the second probe, and the third probe in sequence to calculate the transmission coefficient matrix K. Where k1 is the transmission coefficient of the first probe, k2 is the transmission coefficient of the second probe, and k3 is the transmission coefficient of the third probe. S57. Using k1, k2, and k3, the final calculated value of the voltage to be measured is obtained.