CN-122017316-A - Unified characterization method, device and sensor for sensitivity of non-invasive current detection scene

CN122017316ACN 122017316 ACN122017316 ACN 122017316ACN-122017316-A

Abstract

The invention discloses a unified characterization method and device for sensitivity of a non-invasive current detection scene and a sensor, and belongs to the technical field of electric power measurement. The method comprises the steps of taking measured current in a conductor as a research object, establishing a measured current density distribution model in the conductor, calculating three-dimensional space magnetic field distribution outside the conductor according to the current density distribution model, combining a three-dimensional space structure model of a sensor, projecting the three-dimensional space magnetic field distribution in the direction of a sensor main shaft to obtain effective magnetic induction intensity, calculating the effective magnetic flux, differentiating the effective magnetic flux to obtain coil induction voltage, integrating the coil induction voltage through a signal reduction circuit to obtain output voltage proportional to the effective magnetic flux, and obtaining a sensitivity function of the non-invasive current sensor. The unified sensitivity characterization method is suitable for any measuring device structure and coil structure, and can uniformly characterize the sensitivity at any position and in different application scenes.

Inventors

PENG HAN
HOU LIWEN

Assignees

华中科技大学

Dates

Publication Date: 20260512
Application Date: 20260206

Claims (9)

1. A method for uniformly characterizing the sensitivity of a non-invasive current detection scene, comprising the steps of: Taking the measured current in the conductor as a research object, taking the current direction of the measured current as a z axis, and taking the plane of the cross section of the conductor as an x-y plane, and establishing a space three-dimensional coordinate system so as to establish a measured current density distribution model in the conductor; calculating the three-dimensional space magnetic field distribution outside the conductor according to the current density distribution model; the method comprises the steps of combining a three-dimensional space structure model of a non-invasive current sensor, projecting the three-dimensional space magnetic field distribution in the direction of a sensor main shaft to obtain effective magnetic induction intensity, integrating the effective magnetic induction intensity on an effective section of a magnetic core to obtain effective magnetic flux; differentiating the effective magnetic flux, and calculating to obtain coil induced voltage in the non-invasive current sensor; Integrating the coil induced voltage through a signal reduction circuit to obtain an output voltage proportional to the effective magnetic flux, and obtaining a sensitivity function of the non-invasive current sensor; the sensitivity function is expressed as: Wherein f is the working frequency of the current to be measured in the conductor; r' is the position vector of any point in the section of the conductor, r is the position vector of the magnetic core position of the non-invasive current sensor in space; Is a unit vector of the main axis direction of the magnetic core, mu eff is the effective magnetic permeability of the magnetic core, A core is the effective sectional area of the magnetic core, K is the proportionality coefficient of the signal reduction circuit, and N is the number of turns of the coil.
2. The method of claim 1, wherein the modeling the current density distribution inside the conductor with the measured current in the conductor as the subject of investigation comprises: Under the working condition of f frequency, the current density inside the conductor is measured Affected by skin effect, satisfies electromagnetic diffusion equation: wherein ω=2pi f is angular frequency, μ is conductor permeability, σ is conductor conductivity; according to the constraint condition that the measured current density distribution in the conductor is consistent with the measured current of the conductor, carrying out normalization processing on the current density to obtain the current density distribution from the measured current i of the conductor to the inside of the conductor Mapping relation of (3); the constraint conditions are as follows: Wherein dS source is the infinitesimal area of the cross section of the conductor, S source is the measured current cross section area of the conductor; solving to obtain the distribution function of the current density measured in the conductor along with the change of frequency 。
3. The method of claim 2, wherein said calculating a three-dimensional spatial magnetic field distribution outside the conductor from said measured current density distribution model comprises: Based on the Biaoh-Saval law, establishing three-dimensional space magnetic field distribution of the measured current i of the conductor at any point in space according to the current density distribution model: Wherein, the For the measured current density in the conductor, The magnetic induction at the spatial position r at the frequency f, and V represents the volume area occupied by the sensor.
4. A method according to claim 3, wherein the three-dimensional space structure model of the combined non-invasive current sensor is used for projecting the sensor main axis direction of the three-dimensional space magnetic field distribution to obtain effective magnetic induction intensity; integrating the effective magnetic induction intensity over an effective cross section of the magnetic core to obtain an effective magnetic flux, comprising: based on magnetic core position parameter r c and attitude parameter of non-invasive current sensor Establishing a three-dimensional space structure model of the non-invasive current sensor by using parameters of magnetic core permeability characteristic mu r、 , effective permeability mu eff and effective sectional area A core ; With the main axis direction of the sensor core Projecting the three-dimensional spatial magnetic field distribution to the main axis direction of the magnetic core: The main shaft direction of the sensor magnetic core is an attitude parameter; permeability according to magnetic core material data manual Magnetic permeability of real part Magnetic permeability of imaginary part , And the effective magnetic permeability is obtained through the geometric demagnetizing factor N d : wherein N d is related to core shape and size; according to the complex permeability of the core And the cross-sectional area A core of the magnetic core is used for integrating the effective magnetic induction intensity on the effective section of the magnetic core to obtain effective magnetic flux: 。
5. the method of claim 4, wherein the coil induced voltage is expressed as: 。
6. the method of claim 5, wherein the output voltage is expressed as: ; Wherein, K is the proportionality coefficient of transfer function in the signal restoring circuit, which is determined by the resistance, capacitance and operational amplifier parameters in the signal restoring circuit.
7. The method of claim 1, wherein when the conductor is an oblong wire, the spatial magnetic field magnitude is related only to the measured current magnitude of the conductor and the geometric distance between the non-invasive current sensor and the conductor, and the sensitivity function is expressed as: The cross section of the long straight round conductor is a circle with radius R, the length extends along the z-axis direction, mu 0 is air permeability, and rho is the radial distance from the observation point to the axis of the round conductor.
8. A unified characterization device for sensitivity of a non-invasive current detection scenario, comprising: The current density calculation module is used for establishing a space three-dimensional coordinate system by taking the measured current in the conductor as a research object, the current direction of the measured current as a z-axis and the plane where the cross section of the conductor is positioned as an x-y plane, so as to establish a measured current density distribution model in the conductor; the spatial magnetic field distribution calculation module is used for calculating three-dimensional spatial magnetic field distribution outside the conductor according to the current density distribution model; The effective magnetic flux calculation module is used for combining a three-dimensional space structure model of the non-invasive current sensor, projecting the three-dimensional space magnetic field distribution in the direction of a main shaft of the sensor to obtain effective magnetic induction intensity; The induced voltage module is used for differentiating the effective magnetic flux and calculating to obtain coil induced voltage in the non-invasive current sensor; the sensitivity function construction module is used for carrying out integral processing on the coil induced voltage through the signal reduction circuit to obtain an output voltage proportional to the effective magnetic flux, and obtaining the sensitivity function of the non-invasive current sensor; the sensitivity function is expressed as: Wherein f is the working frequency of the current to be measured in the conductor; R is the position vector of the non-invasive current sensor magnetic core position in space; Is a unit vector of the main axis direction of the magnetic core, mu eff is the effective magnetic permeability of the magnetic core, A core is the effective sectional area of the magnetic core, K is the proportionality coefficient of the signal reduction circuit, and N is the number of turns of the coil.
9. A non-invasive current sensor, wherein the sensitivity of the non-invasive current sensor in a non-invasive current detection scenario is represented by the unified characterization method of the sensitivity of the non-invasive current detection scenario according to any one of claims 1-7.

Description

Unified characterization method, device and sensor for sensitivity of non-invasive current detection scene Technical Field The invention belongs to the technical field of electric power measurement, and particularly relates to a unified characterization method, a unified characterization device and a unified characterization sensor for sensitivity of a non-invasive current detection scene. Background The non-invasive current sensor realizes indirect measurement of current by sensing a magnetic field generated by a current-carrying conductor in space, and has the advantages of no need of damaging an original electrical structure, suitability for complex current-carrying fluid environments and the like. However, both sense magnetic fields in a different manner than invasive current sensors (e.g., rogowski coils). The invasive current sensor has rogowski coil around the conductor to be measured to integrate the loop path of the magnetic field produced by the current. The integration result is determined by the measured current only, according to ampere's loop law, regardless of the specific distribution of the magnetic field in space. Therefore, the sensitivity is only determined by the number of turns of the coil and the geometric dimension, and is irrelevant to the installation position and the gesture direction. The non-invasive current sensor does not surround a current carrying conductor, and can only sense a magnetic field generated by current in a space local area, so that the sensitivity is not an inherent parameter determined by a device structure, but a system response determined by magnetic field distribution and a space position together is difficult to accurately determine and uniformly characterize, and the difficulty of quantitative measurement of the current is increased. In the existing research of the sensitivity of the non-invasive current sensor, some efforts have been made to analyze the sensitivity of the non-invasive current sensor from the viewpoint of magnetic field modeling or experimental calibration. For example, some studies are based on a simple central model and establish a relationship between sensor output and magnetic field based thereon, while others are based on experimental calibration to obtain an empirical scaling factor between sensor output and current for subsequent current measurements under fixed mounting conditions. However, the above methods typically rely on specific structural assumptions or fixed conditions, the sensitivity descriptions of which are difficult to reflect the systematic effects of spatial position, attitude and frequency variations on sensor response. When the current carrying conductor structure, the installation condition or the working frequency are changed, the sensitivity is changed along with the change, and the current carrying conductor structure and the installation condition need to be re-characterized or re-calibrated, so that great inconvenience is brought to engineering application and system deployment. Therefore, on the basis of the existing research, a method for representing the sensitivity of the sensor with spatial characteristics, frequency characteristics and different frequency conditions is needed to realize unified representation of the sensitivity of the non-invasive current sensor under different carrier structures, different installation conditions and different frequency conditions, so as to ensure accurate monitoring of current signals. Disclosure of Invention Aiming at the defects of the related art, the invention aims to provide a unified characterization method, a unified characterization device and a unified characterization sensor for sensitivity of a non-invasive current detection scene, and aims to solve the problem of low current signal monitoring precision caused by the fact that the characterization of the sensitivity of the non-invasive current sensor cannot be unified under different carrier structures, different installation conditions and different frequency working conditions. In order to achieve the above object, the present invention provides a method for uniformly characterizing sensitivity of a non-invasive current detection scenario, including: Taking the measured current in the conductor as a research object, taking the current direction of the measured current as a z axis, and taking the plane of the cross section of the conductor as an x-y plane, and establishing a space three-dimensional coordinate system so as to establish a measured current density distribution model in the conductor; calculating the three-dimensional space magnetic field distribution outside the conductor according to the current density distribution model; the method comprises the steps of combining a three-dimensional space structure model of a non-invasive current sensor, projecting the three-dimensional space magnetic field distribution in the direction of a sensor main shaft to obtain effective magnetic induction intensi