CN116932977A - Three-phase cable current non-contact rapid measurement method, device and system - Google Patents
Three-phase cable current non-contact rapid measurement method, device and system Download PDFInfo
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Abstract
The invention discloses a non-contact rapid measurement method, device and system for three-phase cable current, and belongs to the technical field of cable detection tests. The method comprises the following steps: constructing a three-phase cable circumferential magnetic field analysis calculation model; acquiring a circumferential magnetic field discrete value of a cable to be tested through an annular magnetic sensing array, and reconstructing and expanding the circumferential magnetic field discrete value into a circumferential magnetic field measured value by utilizing an interpolation algorithm in combination with the spatial position information of the magnetic sensing array; the initial value of the polar angle of the three-phase cable core wire is obtained through analysis of the circumferential magnetic field measured value, and the three-phase core wire polar diameter and the three-phase current optimal parameter which enable the difference between the cable circumferential magnetic field calculated value and the circumferential magnetic field measured value to be minimum are searched and determined by utilizing an intelligent optimization algorithm and are output as measurement results. The position information of the three-phase core wire is obtained through analyzing the discrete magnetic field measurement data and is used as priori knowledge to be embedded into an optimization algorithm program, so that the algorithm is guided to quickly converge to an optimal solution, and the stability and the rapidity of a solving result are improved.
Description
Technical Field
The invention belongs to the technical field of cable detection tests, and particularly relates to a three-phase cable current non-contact rapid measurement method, device and system.
Background
The construction and construction of smart power grids are becoming more and more important in the current society, and as a result, three-phase power cables are increasingly applied to cable transmission and distribution engineering of a three-phase power system, and real-time monitoring of the three-phase cables is a basis for guaranteeing safe, stable and economic operation of the smart power grids.
The current is used as an electrical parameter directly reflecting the state of the cable, and accurate measurement is particularly important for reliable operation of the cable. Currently, non-contact current measurement for a single-core cable is mature, however, since the sum of current vectors of three-phase cables is zero, the conventional current transformer cannot be directly applied to current measurement of three-phase conductors. For the non-contact measurement of the currents of the multiphase conductors, a magnetic sensor array method is mainly adopted, a multi-conductor system model is established through analysis of sensor measured values, optimization solving is carried out through an algorithm, and the positions and the currents of the core wires in the three-phase cable core wires are determined, so that the solving is completed. And the optimization algorithm solution is a key step for accurately measuring the three-phase cable current.
At present, the optimization algorithm for three-phase cable measurement mainly comprises the following two types: can be divided into heuristic and meta-heuristic algorithms. Among heuristic algorithms, quasi-newton, adam and root mean square propagation are three common algorithms that are efficiently optimized using gradient information. However, these heuristic algorithms may fall into a local optimum and may not accurately obtain the target value. For the globally optimized meta-heuristic algorithm, inspired by biological evolution in the nature, an improved multi-operator differential evolution algorithm is provided, and the algorithm utilizes the advantages of a plurality of differential evolution operators to more emphasize the operator with the best performance. However, the evolutionary algorithm has the problems that the convergence speed is low, the optimal solution cannot be converged when solving the multi-conductor current back calculation problem, and the like, so that the development of multi-conductor non-contact measurement is limited. Therefore, in the method for measuring the three-phase cable in the prior art, the problem that the measurement result is misaligned because the solution is in a locally optimal solution or can not be converged due to a wide solution range exists.
Disclosure of Invention
Aiming at the defects of the related art, the invention aims to provide a three-phase cable current non-contact rapid measurement method, device and system, and aims to solve the problem that the existing method is in a local optimal solution or can not be converged due to a wide solution range, so that a measurement result is out of alignment.
In order to achieve the above object, the present invention provides a method for non-contact rapid measurement of three-phase cable current, comprising:
taking the center of the three-phase cable to be measured as the origin of a polar coordinate system, and constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be measured;
the circumferential magnetic field measurement data of the three-phase cable to be measured is obtained through measurement through an annular magnetic sensor array arranged on the three-phase cable to be measured；
From the circumferential magnetic field measurement dataThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, and changing the polar diameter and the three-phase current of the three-phase core wire to obtain a corresponding valueCircumferential magnetic field calculation data of (2)；
Calculating the data of the circumferential magnetic fieldAnd the circumferential magnetic field measurement data +.>And (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
Optionally, the constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be tested includes:
based on the Biaoh-Saval law and the cosine theorem, calculating the calculated strength of a circumferential magnetic field generated by a single core wire in the three-phase cable to be measured on the surface of the cable, wherein the calculated strength is as follows:
in the method, in the process of the invention,is of vacuum permeability->For the polar parameter corresponding to the measuring point in the magnetic field data acquired by the magnetic sensor, < >>For the polar parameters of the core wire, < >>Is the cable current;
according to the superposition theorem, calculating the calculated intensity of the circumferential magnetic field generated on the cable surface by the three-phase core wire in the three-phase cable to be testedThe method comprises the following steps:
in the method, in the process of the invention,core polar coordinate parameters of A phase, B phase and C phase respectively, +.>The current of the phase A, the phase B and the phase C are respectively.
Optionally, the circumferential magnetic field measurement data of the three-phase cable to be measured is obtained by measurement through an annular magnetic sensor array arranged on the three-phase cable to be measuredComprising:
discrete magnetic field data are obtained through measurement of an annular magnetic sensor array arranged on the three-phase cable to be measured;
reconstructing and expanding the discrete magnetic field data through an interpolation algorithm to obtain circumferential magnetic field measurement data of the three-phase cable to be measuredAnd based on said circumferential magnetic field measurement data +.>A maximum measurement of the circumferential magnetic field is determined.
Optionally, the center of the annular magnetic sensor array coincides with the center of the three-phase cable to be tested.
Optionally, the number N of magnetic field sensors of the annular magnetic sensor array satisfies the following condition:
where n is the number of supply phases.
Optionally, the circumferential magnetField measurement dataThe number of the contained measured values is not less than +.>Wherein N is the number of magnetic sensors in the annular magnetic sensing array.
In a second aspect, the present invention also provides a device for non-contact rapid measurement of three-phase cable current, including:
the model construction module is used for constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be tested by taking the center of the three-phase cable to be tested as the origin of the polar coordinate system;
the magnetic field measurement data acquisition module is used for measuring and obtaining circumferential magnetic field measurement data of the three-phase cable to be measured through an annular magnetic sensor array arranged on the three-phase cable to be measured；
An initial value determining module for measuring data according to the circumferential magnetic fieldThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
the magnetic field calculation data acquisition module is used for substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, changing the polar diameter and the three-phase current of the three-phase core wire, and obtaining corresponding circumferential magnetic field calculation data；
An optimal parameter determining module for determining the optimal parametersCircumferential magnetic field calculation dataAnd the circumferential magnetic field measurement data +.>And (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
In a third aspect, the present invention also provides a system for non-contact rapid measurement of three-phase cable current, including: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions;
the processor is configured to read executable instructions stored in the computer readable storage medium and perform the method of any one of the first aspects.
Compared with the prior art, the technical scheme of the invention has the following beneficial effects:
1. the invention provides a three-phase cable current non-contact rapid measurement method, which takes the relation of position information of an inner core wire of a three-phase cable (the polar angle of the polar coordinate of the maximum value of a circumferential magnetic field is equal to the polar angle of the polar coordinate of the three-phase cable core wire) as priori knowledge to be embedded into an optimization algorithm program, and determines the position coordinate of the inner core wire of the three-phase cable according to the maximum measured value coordinate of the circumferential magnetic field as an initial value of the optimization algorithm. Therefore, the current inverse calculation solving process is converted into a single-objective optimization problem, the search space of the algorithm is reduced, the algorithm can be converged to an optimal result, the problem of misalignment of the measurement result of the existing algorithm is solved, and the accuracy of the solving result and the calculation speed of the algorithm are improved.
2. The invention provides a non-contact rapid measurement method for three-phase cable current, which comprises the steps of reconstructing and expanding discrete magnetic field information into a circumferential magnetic field of a three-phase cable by using an interpolation algorithm, and obtaining complete circumferential magnetic field data of the three-phase cable by using a small number of magnetic sensors. The method provided by the invention only depends on the magnetic field outside the cable to solve, is irrelevant to the type selection of the sensor, can be applied to the data solving and calculating of various magnetic sensor arrays, is not limited to a single magnetic sensor type, and has wider applicability.
3. The invention provides a three-phase cable current non-contact rapid measurement method, which converts a current inverse calculation solving process into a single-target optimization problem, wherein the single-target optimization problem and an optimization algorithm can be used not only under the condition that a three-phase cable inner core wire conductor is symmetrical, but also under the condition that the cable inner core wire conductor is asymmetrical, namely under the condition that the conductor is asymmetrical, a current measurement result obtained by the method still has high accuracy and wide applicability.
Drawings
Fig. 1 is a schematic flow chart of a method for non-contact rapid measurement of three-phase cable current according to an embodiment of the present invention.
Fig. 2 is a schematic diagram of a three-phase cable circumferential magnetic field calculation analytical model constructed in an embodiment of the invention.
Fig. 3 is a schematic diagram of another three-phase cable circumferential magnetic field calculation analytical model constructed according to an embodiment of the present invention.
FIG. 4 is a graph showing the results of evaluation times during a solution process using different optimization algorithms for the working conditions in the embodiment of the present invention.
Fig. 5 is a graph of evaluation frequency results in a solving process of a second working condition by using different optimization algorithms in the embodiment of the invention.
Fig. 6 is a graph of the evaluation frequency result in the solving process of the third working condition by adopting different optimization algorithms in the embodiment of the invention.
Fig. 7 is a graph of evaluation frequency results in a solution process of a fourth working condition by using different optimization algorithms in the embodiment of the invention.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention. In addition, the technical features of the embodiments of the present invention described below may be combined with each other as long as they do not collide with each other.
The description of the contents of the above embodiment will be given below in connection with a preferred embodiment.
As shown in fig. 1, a method for non-contact rapid measurement of three-phase cable current includes:
s1, taking the center of a three-phase cable to be detected as an origin of a polar coordinate system, and constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be detected;
s2, measuring circumferential magnetic field measurement data of the three-phase cable to be measured through an annular magnetic sensor array arranged on the three-phase cable to be measured；
S3, measuring data according to the circumferential magnetic fieldThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
s4, substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, and changing the polar diameter and the three-phase current of the three-phase core wire to obtain corresponding circumferential magnetic field calculation data；
S5, calculating the data of the circumferential magnetic fieldAnd the circumferential magnetic field measurement data +.>And (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
The embodiment of the invention provides a non-contact rapid measurement method for three-phase cable current, which takes the physical knowledge of a multi-conductor system as a basis, embeds the coordinate relation between a three-phase superimposed magnetic field and a three-phase cable core wire as priori knowledge into an optimization algorithm program, guides the algorithm to quickly converge to an optimal solution, and improves the stability and rapidity of a solving result. Firstly, taking the center of a three-phase cable to be measured as the origin of a polar coordinate system, constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be measured according to the Piaor-Saval law, the cosine theorem and the superposition theorem, and obtaining circumferential magnetic field calculation dataDeducing a relationship between the polar angle coordinate of the maximum value of the circumferential magnetic field and the polar angle coordinate of the three-phase cable core wire, and embedding the relationship as priori knowledge into an optimization algorithm program; then, obtaining a discrete measurement result of the magnetic field in the cable adjacent space to be measured through the annular magnetic sensing array, and reconstructing and expanding the discrete value of the circumferential magnetic field into circumferential magnetic field measurement data by utilizing an interpolation algorithm in combination with the spatial position information of the magnetic sensing array>Constructing a circumferential magnetic field measurement data waveform diagram, and obtaining three continuous circumferential magnetic field peaks of a circumferential magnetic field; then, through analysis of the measured value of the circumferential magnetic field, the position coordinates of the inner core wire of the three-phase cable are determined by adopting the peak coordinates of the reconstructed and expanded circumferential magnetic field; finally, the position data obtained by the method is taken as an initial value of a three-phase core wire coordinate parameter, and is brought into calculation of a circumferential magnetic field analysis calculation model and algorithm solution, when different parameter conditions are obtained, the calculated value of the circumferential magnetic field is searched and determined by utilizing an intelligent optimization algorithm, and the three-phase core wire which minimizes the difference between the calculated value of the circumferential magnetic field of the cable and the measured value of the circumferential magnetic field is searched and determinedAnd outputting the optimal parameters of the wire electrode diameter and the three-phase current as measurement results, and completing the measurement of the three-phase cable core wire current. The number of unknown variables is effectively reduced, the search space is greatly reduced, the algorithm can quickly and accurately converge to the optimal solution, the problem of misalignment of the measurement result of the existing algorithm is solved, and the stability and the rapidity of the solution result are improved.
Furthermore, the method provided by the embodiment only depends on the magnetic field outside the cable to solve, and is irrelevant to the type selection of the sensor, so that the method can be applied to the calculation of various magnetic sensor arrays, and has better universality on the basis of improving the accuracy and convergence speed of the algorithm.
Optionally, the constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be tested includes:
based on the Biaoh-Saval law and the cosine theorem, calculating the calculated strength of a circumferential magnetic field generated by a single core wire in the three-phase cable to be measured on the surface of the cable, wherein the calculated strength is as follows:
in the method, in the process of the invention,is of vacuum permeability->For the polar parameter corresponding to the measuring point in the magnetic field data acquired by the magnetic sensor, < >>For the polar parameters of the core wire, < >>Is the cable current; according to the superposition theorem, calculating the circumferential magnetic field calculation intensity generated by the three-phase core wire in the three-phase cable to be measured on the surface of the cable>The method comprises the following steps:
；
in the method, in the process of the invention,core polar coordinate parameters of A phase, B phase and C phase respectively, +.>The current of the phase A, the phase B and the phase C are respectively.
According to the magnetic field superposition principle, combining the geometric parameters of the three-phase cableAnd constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be tested. Firstly, establishing a circumferential magnetic field calculation formula generated by a single core wire on the surface of a cable, and then establishing the circumferential magnetic field calculation strength +.>The calculation formula of the circumferential magnetic field is a circumferential magnetic field analysis calculation model.
Analysis of the circumferential magnetic field analytical calculation model shows that the polar coordinate parameters at the measurement pointsPolar angle>Polar coordinates to the three-phase core wire->Polar angle>When the magnetic fields are equal, the circumferential magnetic field is the maximum value, and the relation of the position information of the inner core wires of the three-phase cable (the polar angle of the polar coordinates of the maximum value of the circumferential magnetic field is equal to the polar angle of the polar coordinates of the core wires of the three-phase cable) is used as priori knowledge to be embedded into an optimization algorithm program.
Optionally, the circumferential magnetic field measurement data of the three-phase cable to be measured is obtained by measurement through an annular magnetic sensor array arranged on the three-phase cable to be measuredComprising:
the annular magnetic sensor array measures and obtains discrete magnetic field data;
reconstructing and expanding the discrete magnetic field data through an interpolation algorithm to obtain circumferential magnetic field measurement data of the three-phase cable to be measuredAnd based on said circumferential magnetic field measurement data +.>A maximum measurement of the circumferential magnetic field is determined.
When an annular magnetic sensor array is arranged, the center of the annular magnetic sensor array is coincident with the center of the three-phase cable to be tested, and the number N of magnetic field sensors of the annular magnetic sensor array meets the following conditions:
where n is the number of supply phases.
The present embodiment uses a three-phase cable, so that the number of magnetic field sensors is greater than 9, and preferably evenly distributed around the three-phase cable to be tested.
By additionally arranging the annular magnetic sensing array on the cable to be tested and collecting the measured values of all the magnetic sensors in the magnetic sensor array, the discrete measured values of the circumferential magnetic field of the cable to be tested can be synchronously obtainedReconstructing and expanding the discrete value of the circumferential magnetic field into circumferential magnetic field measurement data by utilizing an interpolation algorithm in combination with the spatial position information of the magnetic sensing arrayWherein the expanded circumferential magnetic field measurement data +.>The more measurements are included, the better, but too much data affects the performance and time of the calculation, so the number of measurements is preferably no less than +.>One measured value corresponds to one measured point, N is the number of magnetic sensors in the annular magnetic sensing array, and the circumferential magnetic field measured data are enriched on the premise of not affecting the calculation performance.
According to priori knowledge, when the circumferential magnetic field measurement has a peak value, the polar angle in the polar coordinate of the measurement point is equal to the polar angle in the polar coordinate of the three-phase core wire; in the circumferential magnetic field measurement data of the three-phase cable, when the polar angle in the polar coordinates of each single-phase core wire is equal to the polar angle in the polar coordinates of the measurement point, a peak value is corresponding; based on circumferential magnetic field measurement dataPerforming data fitting to construct a circumferential magnetic field measurement data waveform diagram, determining three continuous circumferential magnetic field peaks, and obtaining circumferential angles corresponding to the three peaks>Thereby determining the initial value of the polar angle of the three-phase core coordinates.
The method provided by the embodiment converts the current inverse calculation problem into a single-objective optimization problem, and solves the optimal parameters through an intelligent optimization algorithm.
A polar coordinate system is established by taking the center of the cable as the origin O of coordinates, and magnetic field measurement data can be obtained through the annular magnetic field sensor arrayAnd magnetic field sensor position->At the same time, the position of the core wire->And current parameter->Unknown. Converting the current inverse calculation problem into calculation +.>And->To obtain the optimal parametersThereby converting the inverse current calculation into a single objective optimization problem. Formula of single-objective optimization problem:
wherein X and n are the number of measuring points and the number of cable conductors, respectively,and->The magnetic field measurement value and the calculated value of the j-th measurement point are respectively.
According to the circumferential magnetic field analysis calculation model, deriving the circumferential magnetic field intensity generated on the cable surface by a single core wire in the three-phase cable to obtain the derivative of the circumferential magnetic field intensity，
；
From the above formula, the following can be obtainedOr->When (I)>The sensor must be +_ because it is arranged outside the cable>It can be derived that->At->When reaching the maximum value inWhen a minimum is reached.
When the three-phase core wires in the three-phase cable to be tested are completely symmetrical, namely，/>Andwhen (I)>The maximum value of (2) occurs at +.>Where it is located. For the general case, whenAnd->When (I)>The maximum value of (2) appearing at
Where it is located. Wherein (1)>Is a small fluctuation range.
Calculated strength of circumferential magnetic fieldCorresponds to the circumferential angle of the measuring point +.>The circumference angle +.>Respectively used as the initial value of the polar angle of the three-phase core wire, and the initial value of the coordinates of the three-phase core wire is respectively。
Based on the maximum measured value of the circumferential magnetic field obtainedDue to the polar parameter corresponding to the measuring pointIt is known that the calculation formula of the circumferential magnetic field analysis calculation model only contains the polar diameters of the unknown A phase, the unknown B phase and the unknown C phaseAnd the currents of phase A, phase B, phase C +.>. Setting proper parameter values into a formula to obtain corresponding calculated values of the circumferential magnetic field, obtaining X calculated values of each group of parameters, respectively calculating average numbers of differences between the X calculated values and corresponding measured values, and calculating circumferential magnetic field calculation data corresponding to different parameter groups>And circumferential magnetic field measurement data->And (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire pole diameters and three-phase current parameters which are set correspondingly to the calculation data. The position data of the maximum measured value is taken as an initial value of the three-phase core wire coordinate parameter and is brought into calculation of a model and algorithm solving, so that the number of unknown variables is effectively reduced, the search space is greatly reduced, and the algorithm can be conveniently and rapidly converged to an optimal solution.
The method provided by the embodiment is not only suitable for the situation that the inner core wire conductors of the three-phase cable are symmetrical, but also suitable for the situation that the inner core wire conductors of the three-phase cable are asymmetrical. The accuracy of the algorithm provided by the invention on the measurement of the current in the inner core wire of the three-phase cable under the electrified working conditions of the four three-phase cables is compared with various common algorithms. Therefore, the method provided by the invention can be better than other algorithms in searching to obtain the optimal solution under various electrified working conditions.
In the embodiment, the following basic information is kept consistent under the electrified working condition of four three-phase cables, 10kV three-phase cables in a certain area are selected as an example, the radius R of each cable is 25mm, and the radius of each phase core is 25mm4mm, wherein the angle is expressed in radians.
Working condition one:
distance between cable center and each phase corer10mm rated current600A.
Assuming that the three-phase cable is an infinitely long straight conductor, taking the center of the cable as the origin of coordinates O, constructing a three-phase cable circumferential magnetic field calculation and analysis model as shown in figure 2, and settingThe axis coincides with OA, in->Shaft angle->. Can determine the polar coordinates of each core wire as、/>。
Working condition II:
distance between phase A and cable centerrAt a distance of 12mm between phase B and phase C and the cable centerrIs 10mm. Rated current600A.
Assuming that the three-phase cable is an infinitely long straight conductor, taking the center of the cable as the origin of coordinates O, constructing a three-phase cable circumferential magnetic field calculation and analysis model as shown in figure 3, and settingThe axis coincides with OA, in->Shaft angle->. Can determine the polar coordinates of each core wire as、/>。
And (3) working condition III:
distance between cable center and each phase corer10mm, rated current of A phase600A, B phase rated current +.>700A, C phase rated current +.>500A.
Assuming that the three-phase cable is an infinitely long straight conductor, taking the center of the cable as the origin of coordinates O, constructing a three-phase cable circumferential magnetic field calculation and analysis model as shown in figure 2, and settingThe axis coincides with OA, in->Shaft angle->. Can determine the polar coordinates of each core wire as、/>。
And (4) working condition four:
distance between phase A and cable centerrAt a distance of 12mm between phase B and phase C and the cable centerrIs 10mm. Rated current of A phase600A, B phase rated current +.>700A, C phase rated current +.>500A.
Assuming that the three-phase cable is an infinitely long straight conductor, taking the center of the cable as the origin of coordinates O, constructing a three-phase cable circumferential magnetic field calculation and analysis model as shown in figure 3, and settingThe axis coincides with OA, in->Shaft angle->. Can determine the polar coordinates of each core wire as、/>。
Taking the first working condition as an example for interpolation analysis, discrete circumferential magnetic field measurement values can be obtained by collecting measurement values of all magnetic sensors in the magnetic sensor array, and a magnetic field amplitude matrix can be obtained by analysis:
determining the spatial position of each magnetic sensor by using a polar coordinate system to obtain a magnetic sensor spatial angle matrixWherein the space angle is expressed in radians:
after combining the values of the space angle matrix, using a Spline cubic Spline interpolation algorithm to the discrete circumferential magnetic field, the discrete value of the circumferential magnetic field can be reconstructed and expanded into a circumferential magnetic field measured value。
By reconstructing the data of the expanded circumferential magnetic field under the four working conditionsThe analysis can result in a circumferential angle corresponding to the maximum value of the magnetic field measurement value +.>Wherein the circumferential angle is expressed in radians.
Working condition one:
working condition II:
and (3) working condition III:
and (4) working condition four:
circumference angle in four three-phase cable live working conditionsSubstituting initial values of polar angles of three-phase core wires into the circumferential magnetic field analysis calculation model constructed by the invention, respectively solving and averaging each working condition for multiple times to obtain measurement average values of three-phase currents in four working conditions, taking working condition one as an example, and measuring current data as follows:。
according to the measured data of the annular magnetic sensor array, actual values are obtained, and the relative errors between the A, B, C three-phase current measured values and the calculated values are respectively 0.75%, 0.21% and 0.25%.
Table 1 is a three-phase current measurement average relative error data table under different working conditions, three-phase current measurement average relative error data of the other three working conditions are shown in table 1, and it can be seen that the relative error between the three-phase current measurement result calculated by the algorithm and the actual value is lower than 1.5%, and the three-phase current measurement accuracy is higher;
；
further, each three-phase cable live working condition uses a differential evolution algorithm, a genetic algorithm, a multi-operator differential algorithm and a particle swarm algorithm to carry out optimization solution on the three-phase cable live working condition, and finally a result graph taking the minimum difference value of a circumferential magnetic field calculated value and a circumferential magnetic field measured value as a vertical axis and the evaluation frequency as a horizontal axis is obtained, wherein the result graphs of the four working conditions are respectively shown in fig. 4, 5, 6 and 7. The method can observe that all the other four algorithms can not converge to the optimal result, the algorithm provided by the invention can converge to the optimal parameter, and the calculation speed is better than that of the other four algorithms.
On the basis of the embodiment, the invention also provides a three-phase cable current non-contact rapid measuring device, which comprises:
the magnetic field calculation data acquisition module is used for constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be measured by taking the center of the three-phase cable to be measured as the origin of the polar coordinate system;
the magnetic field measurement data acquisition module is used for measuring and obtaining circumferential magnetic field measurement data of the three-phase cable to be measured through an annular magnetic sensor array arranged on the three-phase cable to be measured；
An initial value determining module for measuring data according to the circumferential magnetic fieldThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
the magnetic field calculation data module is used for substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, changing the polar diameter and the three-phase current of the three-phase core wire, and obtaining corresponding circumferential magnetic field calculation data；
An optimal parameter determining module for calculating the circumferential magnetic field dataAnd the circumferential magnetic field measurement data +.>And solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, wherein the difference value is the minimum as the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
On the basis of the embodiment, the invention also provides a three-phase cable current non-contact rapid measurement system, which comprises: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions;
the processor is configured to read executable instructions stored in the computer readable storage medium and perform the method according to any one of the above embodiments.
It will be readily appreciated by those skilled in the art that the foregoing description is merely a preferred embodiment of the invention and is not intended to limit the invention, but any modifications, equivalents, improvements or alternatives falling within the spirit and principles of the invention are intended to be included within the scope of the invention.
Claims (8)
1. The non-contact rapid measurement method for the three-phase cable current is characterized by comprising the following steps of:
taking the center of the three-phase cable to be measured as the origin of a polar coordinate system, and constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be measured;
the circumferential magnetic field measurement data of the three-phase cable to be measured is obtained through measurement through an annular magnetic sensor array arranged on the three-phase cable to be measured；
According to the circumferenceTo magnetic field measurement dataThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, and changing the polar diameter and the three-phase current of the three-phase core wire to obtain corresponding circumferential magnetic field calculation data；
Calculating the data of the circumferential magnetic fieldAnd the circumferential magnetic field measurement data +.>And (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
2. The method of claim 1, wherein constructing a circumferential magnetic field analytical calculation model of the three-phase cable under test comprises:
based on the Biaoh-Saval law and the cosine theorem, calculating the calculated strength of a circumferential magnetic field generated by a single core wire in the three-phase cable to be measured on the surface of the cable, wherein the calculated strength is as follows:
；
in the method, in the process of the invention,is of vacuum permeability->For the polar parameter corresponding to the measuring point in the magnetic field data acquired by the magnetic sensor, < >>For the polar parameters of the core wire, < >>Is the cable current;
according to the superposition theorem, calculating the calculated intensity of the circumferential magnetic field generated on the cable surface by the three-phase core wire in the three-phase cable to be testedThe method comprises the following steps:
；
in the method, in the process of the invention,core polar coordinate parameters of A phase, B phase and C phase respectively, +.>The current of the phase A, the phase B and the phase C are respectively.
3. The method of claim 1, wherein the circumferential magnetic field measurement data of the three-phase cable under test is measured by an annular magnetic sensor array disposed on the three-phase cable under testComprising:
discrete magnetic field data are obtained through measurement of an annular magnetic sensor array arranged on the three-phase cable to be measured;
reconstructing and expanding the discrete magnetic field data through an interpolation algorithm to obtain circumferential magnetic field measurement data of the three-phase cable to be measured。
4. The method of claim 1, wherein a center of the annular magnetic sensor array coincides with a center of the three-phase cable under test.
5. The method of claim 4, wherein the number of magnetic field sensors N of the annular magnetic sensing array satisfies the following condition:
；
where n is the number of supply phases.
6. The method of claim 1, wherein the circumferential magnetic field measurement dataThe number of the contained measured values is not less than +.>Wherein N is the number of magnetic sensors in the annular magnetic sensing array.
7. A three-phase cable current non-contact rapid measurement device, comprising:
the model construction module is used for constructing a circumferential magnetic field analysis calculation model of the three-phase cable to be tested by taking the center of the three-phase cable to be tested as the origin of the polar coordinate system;
a magnetic field measurement data acquisition module forThe circumferential magnetic field measurement data of the three-phase cable to be measured is obtained through measurement through an annular magnetic sensor array arranged on the three-phase cable to be measured；
An initial value determining module for measuring data according to the circumferential magnetic fieldThree consecutive circumferential magnetic field peaks are determined and the circumferential angles corresponding to the three peaks are obtained +.>The circumference angle +.>Respectively taking the initial values of polar angles of three-phase core wires in the three-phase cable to be tested;
the magnetic field calculation data acquisition module is used for substituting the initial value of the polar angle of the three-phase core wire into the circumferential magnetic field analysis calculation model, changing the polar diameter and the three-phase current of the three-phase core wire, and obtaining corresponding circumferential magnetic field calculation data；
An optimal parameter determining module for calculating the circumferential magnetic field dataWith the circumferential magnetic field measurement dataAnd (3) taking the minimum difference value as an optimal target, solving by using an intelligent optimization algorithm to obtain target circumferential magnetic field calculation data corresponding to the optimal target, and obtaining three-phase core wire polar diameters and three-phase currents corresponding to the target circumferential magnetic field calculation data.
8. A three-phase cable current non-contact rapid measurement system, comprising: a computer readable storage medium and a processor;
the computer-readable storage medium is for storing executable instructions;
the processor is configured to read executable instructions stored in the computer readable storage medium and perform the method of any one of claims 1-6.
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