CN114818023A - Method and system for identifying electrified state of three-phase cable - Google Patents
Method and system for identifying electrified state of three-phase cable Download PDFInfo
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Abstract
The invention provides a method and a system for identifying the electrified state of a three-phase cable, comprising the following steps: constructing a three-phase cable circumferential magnetic field analytic model according to cable geometric parameters, calculating theoretical magnetic field amplitude and phases under different charged states to obtain a theoretical magnetic field phasor sequence, and constructing a circumferential magnetic field phasor database; measuring a circumferential magnetic field signal of the cable to be measured through the annular magnetic sensor array, and conditioning the signal to obtain a magnetic field signal of each sensor; obtaining a quasi-continuous observation phasor sequence of the cable to be measured by an interpolation method according to the magnetic field signal and the spatial position of each sensor; and calculating correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured and theoretical magnetic field phasor sequences in the database, sequencing the correlation coefficients, and selecting the theoretical charged state corresponding to the highest correlation as the actual charged state of the three-phase cable. By the scheme, the influence of a space interference source magnetic field on the collection of the cable magnetic field signals can be reduced, and the accuracy and reliability of the state identification of the three-phase cable can be improved.
Description
Technical Field
The invention belongs to the field of cable detection, and particularly relates to a method and a system for identifying the electrified state of a three-phase cable.
Background
With the increasing application of three-phase power cables in cable transmission and distribution projects of 35kV and below, the maintenance and overhaul of the operating state of the cable are increasingly emphasized. In power cable's routine maintenance, because the environment is complicated in the cable pit, when certain cable broke down or when needing to overhaul because of other reasons the outage, need cut the cable and handle, require to carry out accurate discernment to the electrified state of required cutting cable this moment, clearly distinguish whether electrified cable, if the actual operation supply cable of mistake header district, then not only can influence the normal power supply of regional interior power system, more serious then takes place serious accidents such as personal injury and death.
At present, for the determination of the electrified state of the three-phase cable, methods based on weak voltage signal determination and methods based on magnetic field signals around the cable are commonly used. In the former method, a non-contact electric field sensor is adopted to measure a weak voltage signal of a cable sheath to judge whether the cable is electrified, the non-contact electric field sensor is mainly based on the principle of capacitance voltage division, the measurement precision of the non-contact electric field sensor is influenced by capacitance calculation errors, when the cable is electrified, the voltage of the cable sheath is only 0.1-30 mV, and the accuracy of judging the electrified state of the cable by using the method is difficult to guarantee; in the latter method, firstly, a magnetic induction probe is used for respectively detecting magnetic field signals generated by each phase of current, and the magnetic field signals are compared with background signals to judge whether the cable is electrified or not; and secondly, the charged state of the cable is judged by inducing parameters such as the magnetic field direction, the phase sequence, the waveform and the like of the three-phase line of the tested cable through a magnetic rod in the induction clamp and a winding coil outside the iron core. However, the number of cables in the cable trench is large, the number and positions of cables in different spaces are different, the size of a magnetic field of a spatial interference source is not fixed, an interference magnetic field generated by the interference source around a cable to be detected has certain randomness, the interference resistance of a single magnetic sensor is improved, the influence of the magnetic field of the interference source in the whole cable trench space is difficult to reduce or offset, and the magnetic sensor still suffers from serious interference of the magnetic field of the interference source in the magnetic field space, so that misjudgment is easily caused.
Disclosure of Invention
In view of this, the embodiment of the invention provides a method and a system for identifying a three-phase cable electrified state, which are used for solving the problems that the existing three-phase cable electrified state judgment is not accurate and misjudgment is easy to occur.
In a first aspect of the embodiments of the present invention, a method for identifying a charged state of a three-phase cable is provided, including:
according to the geometric parameter information of the three-phase cable to be detected, a three-phase cable circumferential magnetic field analytic model is constructed, the circumferential theoretical magnetic field amplitude and the phase of the cable in different electrified states are analyzed and calculated, a cable circumferential theoretical magnetic field phasor sequence is obtained, and a cable circumferential magnetic field phasor database is constructed;
measuring a magnetic field signal in the circumferential direction of the cable to be measured through the annular magnetic sensor array, and conditioning a voltage signal output by the sensor to obtain a magnetic field signal at each sensor;
obtaining a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by an interpolation method according to the magnetic field signal and the spatial position information of each sensor;
and calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
In a second aspect of the embodiments of the present invention, there is provided a three-phase cable electrified state recognition system, including:
the database construction module is used for constructing a three-phase cable circumferential magnetic field analytic model according to the geometric parameter information of the three-phase cable to be detected, analyzing and calculating circumferential theoretical magnetic field amplitude and phases of the cable in different electrified states to obtain a cable circumferential theoretical magnetic field phasor sequence, and constructing a cable circumferential magnetic field phasor database;
the annular magnetic sensor array is used for synchronously measuring voltage analog signals representing the circumferential magnetic field intensity of the cable to be measured;
the conditioning circuit is used for receiving and conditioning the voltage signals output by the annular magnetic sensor array and outputting magnetic field signals at each sensor;
the data processing module is used for receiving the magnetic field signals and obtaining a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected by an interpolation method according to the magnetic field signals and the spatial position information of each sensor;
and the state identification module is used for calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
In the embodiment of the invention, the circumferential direction of the three-phase cable is taken as a reference dimension, the discrete measurement result of the magnetic field of the adjacent space is constructed into a quasi-continuous observation phasor sequence, and the charged state of the cable is judged by calculating the observation-theoretical correlation coefficient of the quasi-continuous observation phasor sequence and all theoretical magnetic field phasor sequences. Because the influence of external space magnetic field interference on each sensor in the annular magnetic sensor array is approximately equal, no influence is caused on the observation-theoretical correlation coefficient, and the influence of external electromagnetic interference on the judgment of the electrified state of the three-phase cable can be reduced by selecting the theoretical electrified state corresponding to the theoretical magnetic field phasor sequence with the highest observation-theoretical correlation as the actual electrified state of the cable, so that the accuracy and the reliability of the state identification of the three-phase cable are guaranteed.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments or the prior art descriptions will be briefly described below, and it is obvious that the drawings described below are only some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.
Fig. 1 is a schematic flow chart of a method for identifying a charged state of a three-phase cable according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a three-phase cable circumferential magnetic field analytic model according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of correlation coefficients of quasi-continuous observation amplitude sequences and theoretical magnetic field amplitude sequences with different numbers of magnetic sensors according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a system for identifying a charged state of a three-phase cable according to an embodiment of the present invention;
fig. 5 is a schematic structural diagram of a device for identifying a charged state of a three-phase cable according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a magnetic sensor provided in accordance with an embodiment of the present invention;
FIG. 7 is a schematic view of an end mechanical coupling plate provided in accordance with an embodiment of the present invention;
FIG. 8 is a schematic view of an end electro-mechanical connector plate provided in accordance with an embodiment of the present invention;
fig. 9 is a schematic view of a fixed connection provided by an embodiment of the present invention.
Detailed Description
In order to make the objects, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the embodiments described below are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be understood that the terms "comprises" and "comprising," when used in this specification or claims and in the accompanying drawings, are intended to cover a non-exclusive inclusion, such that a process, method or system, or apparatus that comprises a list of steps or elements is not limited to the listed steps or elements. In addition, "first" and "second" are used to distinguish different objects, and are not used to describe a specific order.
Referring to fig. 1, a flow chart of a method for identifying a charged state of a three-phase cable according to an embodiment of the present invention includes:
s101, according to geometric parameter information of a three-phase cable to be detected, constructing a three-phase cable circumferential magnetic field analytic model, analyzing and calculating circumferential theoretical magnetic field amplitude and phases of the cable in different electrified states to obtain a cable circumferential theoretical magnetic field phasor sequence, and constructing a cable circumferential magnetic field phasor database;
the geometric parameter information is the cross section geometric parameters of the three-phase cable, including the cable radius, the phase core radius, the distance from the cable center to the phase core center and the like.
As shown in fig. 2, in the three-phase cable circumferential magnetic field analytic model, the cable to be measured is set as an infinite straight conductor, a coordinate system is established with the cable center as the origin of coordinates O, and the cable radius is
The distance between the center of the phase core and the center O of the cable is r, and the tangential magnetic field intensity is B X ；
Phase A, phase B and phase C currents are respectively
The coordinates are respectively
，
，
。
Based on the Biao-Saval law and the superposition principle, the tangential magnetic field intensity generated by all core wires in the three-phase cable on the surface of the cable can be calculated as
Wherein the content of the first and second substances,
in the formula (I), the compound is shown in the specification,
、
、
phase A, phase B and phase C current phases,
、
、
the distances from the centers of the phase A, the phase B and the phase C to the surface of the cable can be obtained according to the following formula:
in the formula (I), the compound is shown in the specification,
the included angle between the straight line connecting the measuring point and the cable center and the y axis is measured.
the magnetic field amplitude and phase can be calculated according to the expression of the tangential magnetic field intensity on the surface of the cable, as follows:
the cable circumferential theoretical magnetic field phasor can be obtained by the cable circumferential theoretical magnetic field amplitude and phase:
the different electrified states comprise normal operation of three phases of the cable to be tested, phase-loss operation of the cable and power failure of a circuit.
Specifically, a three-phase cable circumferential magnetic field analytic model is constructed by taking a cable center as a coordinate origin according to the cable radius, the phase core radius and the distance between the cable center and each phase core, and coordinates of each core wire are calculated;
and calculating the amplitude and the phase of the circumferential theoretical magnetic field of the cable when the three phases of the cable to be detected normally run, the cable is in phase failure and the cable is in power failure based on the three-phase cable circumferential magnetic field analytic model to obtain a circumferential theoretical magnetic field phasor sequence of the cable.
Illustratively, a 10kV three-phase cable in a certain area is taken as an example, and the radius of the cable isρ25mm, rated currentI 0 600A, phase core radiusr 0 4mm, the distance between the cable center and each phase corerIs 10 mm.
Assuming the three-phase cable is an infinite straight conductorTaking the cable center as the origin of coordinates O, a three-phase cable circumferential magnetic field calculation analysis model is constructed as shown in FIG. 2, and the coordinates of each core wire can be determined to be A (0,10) and B (5) respectively by setting the y axis to coincide with OA
，-5)、C(-5
，-5)。
Based on the established model, the amplitude and the phase of a circumferential theoretical magnetic field of the cable are respectively calculated when the three phases of the cable to be measured normally run, the cable is in phase failure and the cable is in power failure, and a circumferential theoretical magnetic field phasor sequence of the cable is obtained, so that a circumferential magnetic field phasor database of the cable is formed.
S102, measuring a magnetic field signal in the circumferential direction of the cable to be measured through the annular magnetic sensor array, and conditioning a voltage signal output by the sensor to obtain a magnetic field signal at each sensor;
when the annular magnetic sensor array is installed, the center of the annular magnetic sensor array needs to be ensured to be superposed with the center of the cable. The center of the annular magnetic sensor array is connected with the fixed connecting piece, the centers of the annular magnetic sensor array and the fixed connecting piece are overlapped, the inner diameter of the fixed connecting piece is consistent with the outer diameter of the cable to be tested, and the fixed connecting piece is tightly attached to the surface of the cable to be tested during installation.
The annular magnetic sensor array consists of magnetic sensors, an end electromechanical connecting plate and an end mechanical connecting plate, wherein the magnetic sensors are fixed on the end mechanical connecting plate and the end electromechanical connecting plate, the magnetic sensors are multi-turn-aliasing PCB type hollow coils engraved with certain-shaped winding wires, and the number of the magnetic sensors is a multiple of 3;
the multi-turn aliasing PCB type hollow coil adopts a multi-turn close winding mode and a multi-layer board process, and all windings have the same direction.
The annular magnetic sensor array comprises N magnetic sensors, wherein N =3N (N is an integer), and N is the minimum value which can satisfy the correlation coefficient of a quasi-continuous observation amplitude sequence obtained by interpolation and a theoretical amplitude sequence to be larger than 0.99.
Illustratively, when n =1, 2, 3,4,5,6 are calculated separately, the interpolated quasi-continuous observed amplitudes areThe sequence is calculated and its correlation coefficient with the theoretical magnetic field amplitude sequence is calculated
As shown in fig. 3, the minimum value of the correlation coefficient between the quasi-continuous observed amplitude sequence obtained by satisfying the interpolation and the theoretical amplitude sequence is n =4, and in this case, the correlation coefficient is greater than 0.99
Therefore, get
I.e. 12 magnetic sensors.
Based on the electromagnetic induction principle, when the cable is electrified, under the action of a magnetic field on the surface of the cable, induced voltage is generated in the hollow coil due to the change of magnetic flux, and the following formula is as follows:
and (4) according to the output voltage of each magnetic sensor, conditioning and integrating to obtain a magnetic field signal of the magnetic sensor.
S103, obtaining a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected by an interpolation method according to the magnetic field signal and the spatial position information of each sensor;
the spatial position information may be determined from sensor position coordinates in a polar coordinate system. According to the magnetic field signals of the sensors and the positions of the sensors, a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured can be obtained.
Specifically, Fourier analysis is carried out on magnetic field signals of each sensor, and a magnetic field amplitude matrix and a phase matrix under power frequency are calculated; calculating a magnetic sensor space angle matrix according to the position of each sensor in the polar coordinate system; and respectively calculating a circumferential magnetic field quasi-continuous observation amplitude sequence and a phase sequence of the cable to be detected by an interpolation method, and calculating a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected according to the amplitude sequence and the phase sequence.
Illustratively, Fourier analysis is performed on each magnetic field signal to obtainCalculating the amplitude matrix of the actually measured magnetic field by the amplitude and phase of the magnetic field under power frequency
Phase matrix
Respectively as follows:
determining the spatial position of each magnetic sensor by using a polar coordinate system to obtain a magnetic sensor spatial angular matrix
The following are:
preferably, the circumferential magnetic field quasi-continuous observation amplitude sequence and the phase sequence of the cable to be detected are respectively calculated based on a spline interpolation method, so that the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected can be obtained.
S104, calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
The observation-theoretical correlation coefficient is used for representing the degree of correlation between the actual observation phasor sequence and the theoretical magnetic field phasor sequence, and can be described in the forms of ratio, Euclidean distance and the like. The observation-theoretical correlation coefficients are sequenced, and the theoretical charged state corresponding to the highest correlation coefficient is selected as the actual charged state, so that the charged state of the three-phase cable is detected.
Optionally, the euclidean distance is used to measure the correlation between the actual observed phasor sequence and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, that is, an observation-theoretical correlation coefficient is calculated based on the euclidean distance.
For example, a theoretical magnetic field phasor sequence is selected when three phases of a cable to be measured are electrified, and the Euclidean distance is 920.2094; selecting a theoretical magnetic field phasor sequence when the cable to be tested is out of phase, calculating Euclidean distances between all the theoretical magnetic field phasor sequences in the database and an actually measured observation phasor sequence, and comparing to obtain 14.6889 when the phases A and C of the cable are electrified and the phase B of the cable is in power failure; the smaller the Euclidean distance is, the higher the correlation is, so that the running state of the cable to be tested is the open-phase running state at the moment can be known.
In the embodiment, the multi-turn aliasing PCB type hollow coil is used as the magnetic sensor, so that the problem of inconsistent multi-turn winding uniformity of the traditional winding coil can be avoided, and the acquisition precision and accuracy of magnetic field signals are improved; because the influence of the external space magnetic field interference on each sensor is approximately equal, no influence is caused on an observation-theoretical correlation coefficient, and the theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation is selected as the actual charged state of the cable, so that the accuracy and the reliability of cable state identification can be guaranteed, and the cable with the abnormal state can be early warned.
It should be understood that, the sequence numbers of the steps in the foregoing embodiments do not imply an execution sequence, and the execution sequence of each process should be determined by its function and inherent logic, and should not constitute any limitation to the implementation process of the embodiments of the present invention.
Fig. 4 is a schematic structural diagram of a system for identifying a charged state of a three-phase cable according to an embodiment of the present invention, where the system includes:
the database construction module 410 is used for constructing a three-phase cable circumferential magnetic field analytic model according to the geometric parameter information of the three-phase cable to be detected, analyzing and calculating circumferential theoretical magnetic field amplitude and phases of the cable in different electrified states to obtain a cable circumferential theoretical magnetic field phasor sequence, and constructing a cable circumferential magnetic field phasor database;
wherein the database building module 410 comprises:
the model building unit is used for building a three-phase cable circumferential magnetic field analytic model by taking the cable center as a coordinate origin according to the cable radius, the phase core radius and the distance between the cable center and each phase core, and calculating the coordinates of each core wire;
and the magnetic field phasor calculation unit is used for calculating the amplitude and the phase of a circumferential theoretical magnetic field of the cable when the three phases of the cable to be detected normally run, the cable is in phase failure and the cable is in power failure based on the three-phase cable circumferential magnetic field analytic model to obtain a circumferential theoretical magnetic field phasor sequence of the cable.
The annular magnetic sensor array 420 is used for synchronously measuring voltage analog signals representing the circumferential magnetic field intensity of the cable to be measured;
the annular magnetic sensor array consists of magnetic sensors, an end electromechanical connecting plate and an end mechanical connecting plate, wherein the magnetic sensors are fixed on the end mechanical connecting plate and the end electromechanical connecting plate, the magnetic sensors are multi-turn-aliasing PCB type hollow coils engraved with certain-shaped winding wires, and the number of the magnetic sensors is a multiple of 3;
the multi-turn aliasing PCB type hollow coil adopts a multi-turn close winding mode and a multi-layer board process, and all windings have the same direction.
The conditioning circuit 430 is configured to receive and condition the voltage signal output by the annular magnetic sensor array, and output a magnetic field signal at each sensor;
preferably, the conditioning circuit is arranged on the electromechanical connecting plate at the end part, and the connecting plate is vertical to the magnetic field around the cable, so that the interference of components in the circuit to the magnetic field can be effectively reduced.
The data processing module 440 is configured to receive the magnetic field signal, and obtain a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by an interpolation method according to the magnetic field signal and the spatial position information of each sensor;
specifically, Fourier analysis is carried out on magnetic field signals of each sensor, and a magnetic field amplitude matrix and a phase matrix under power frequency are calculated; calculating a magnetic sensor space angle matrix according to the position of each sensor in the polar coordinate system; and respectively calculating a circumferential magnetic field quasi-continuous observation amplitude sequence and a phase sequence of the cable to be detected by an interpolation method, and calculating a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected according to the amplitude sequence and the phase sequence.
The state identification module 450 calculates observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, orders the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selects a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
In another embodiment, as shown in fig. 5, a schematic structural diagram of a three-phase cable electrified state recognition device is provided, which includes a magnetic sensor 2, an end mechanical connection board 3, an end electromechanical connection board 4, a fixed connection piece 5, a terminal 6, a conditioning circuit, and the like.
The cable to be tested 1 is positioned in the cable trench, and an annular magnetic sensor array is arranged around the cable to be tested 1 and used for synchronously measuring analog signals representing the magnetic field intensity of each sensor on the annular circumference; obtaining magnetic field phasors at each sensor by measuring magnetic field signals on the surface of the cable, and interpolating to obtain a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by combining spatial position information at each sensor; and selecting a theoretical magnetic field phasor sequence with the highest correlation with the quasi-continuous observation phasor sequence from the database, wherein the corresponding electrified state is the three-phase electrified state of the actual cable to be measured.
The magnetic sensor 2 is fixed on the end mechanical connecting plate 3 and the end electromechanical connecting plate 4, the magnetic sensor array is connected with the fixed connecting piece 5, and the fixed connecting piece 5 is tightly attached to the surface of the cable 1 to be measured.
As shown in fig. 6, a multi-turn aliasing PCB-type hollow coil engraved with rectangular windings is selected as a magnetic sensor 2, two ends of the multi-turn aliasing PCB-type hollow coil are provided with end heads 6 for mechanical connection, each layer is printed with a planar coil formed by connecting k rectangular turns in series, and the planar coils of different layers are connected together in series by using via holes between layers of a printed circuit board;
as shown in fig. 7 and 8, PCB is selected as the end mechanical connection plate 3 and the end electromechanical connection plate 4, with the insertion holes 7 evenly distributed on the annular circumference;
the two ends 6 of the magnetic sensor are respectively inserted into the jacks 7 of the end mechanical connecting plate 3 and the end electromechanical connecting plate 4 to complete mechanical fixation, so that the actual position of each magnetic sensor is accurately positioned.
As shown in fig. 8, the conditioning circuit module 8 is located on the end electromechanical connection board 4 of the magnetic sensor array, and is configured to receive and condition the voltage signal output by the annular magnetic sensor array, and output a magnetic field signal at each sensor.
The annular magnetic sensor array is fixed on a cable 1 to be tested through a fixed connecting piece 5, the fixed connecting piece 5 is opened through a screw, and the inner diameter of the fixed connecting piece is consistent with the outer diameter of the cable 1; the fixed connecting piece 5 and the end mechanical connecting plate 3 of the annular magnetic sensor array are fixed through screws so as to ensure that the center of the magnetic sensor array coincides with the center of the cable.
As shown in fig. 9, the fixing and mounting of the annular magnetic sensor array and the fixed connecting piece 5 are completed by inserting screws into the screw holes 10 of the fixed connecting piece 5 and the screw holes 10 of the end mechanical connecting plate 3; the two fixed connecting pieces 5 are connected by using the screws 11 and are arranged on the cable 1 to be tested, so that the annular magnetic sensor array can be arranged on the cable 1 to be tested.
Further, the device for identifying the electrified state of the three-phase cable further comprises:
the data processing module is used for receiving the magnetic field signals, and interpolating to obtain a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by combining position parameters of each sensor;
and the state identification module is used for calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as the actual charged state of the cable.
In the embodiment of the invention, the multi-turn-mixed type PCB hollow coil is selected as the magnetic sensor, so that the problem of inconsistent multi-turn winding uniformity of the traditional winding coil is solved, and the detection precision and accuracy of the magnetic field signal can be improved; the conditioning circuit module is positioned on the electromechanical connecting plate at the end part, and the connecting plate is vertical to the magnetic field around the cable, so that the interference of components in the circuit to the magnetic field is effectively reduced.
It can be clearly understood by those skilled in the art that, for convenience and brevity of description, the specific working processes of the system and the module described above may refer to corresponding processes in the foregoing method embodiments, and are not described herein again.
It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by using a program to instruct related hardware, where the program may be stored in a computer-readable storage medium, and when the program is executed, the program implements part or all of the processes in steps S101 to S104, and the storage medium includes, for example, ROM/RAM.
In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment.
The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A method for identifying the electrified state of a three-phase cable is characterized by comprising the following steps:
according to the geometric parameter information of the three-phase cable to be detected, a three-phase cable circumferential magnetic field analytic model is constructed, the circumferential theoretical magnetic field amplitude and the phase of the cable in different electrified states are analyzed and calculated, a cable circumferential theoretical magnetic field phasor sequence is obtained, and a cable circumferential magnetic field phasor database is constructed;
measuring a magnetic field signal in the circumferential direction of the cable to be measured through the annular magnetic sensor array, and conditioning a voltage signal output by the sensor to obtain a magnetic field signal at each sensor;
obtaining a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by an interpolation method according to the magnetic field signal and the spatial position information of each sensor;
and calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
2. The method according to claim 1, wherein the constructing of the analytic model of the circumferential magnetic field of the three-phase cable according to the geometric parameter information of the three-phase cable to be measured, and the analyzing and calculating of the circumferential theoretical magnetic field amplitude and phase of the cable in different electrified states to obtain the cable circumferential theoretical magnetic field phasor sequence comprises:
according to the radius of the cable, the radius of phase cores and the distance between the center of the cable and each phase core, constructing a three-phase cable circumferential magnetic field analytic model by taking the center of the cable as a coordinate origin, and calculating the coordinate of each core wire;
and calculating the amplitude and the phase of the circumferential theoretical magnetic field of the cable when the three phases of the cable to be detected normally run, the cable is in phase failure and the cable is in power failure based on the three-phase cable circumferential magnetic field analytic model to obtain a circumferential theoretical magnetic field phasor sequence of the cable.
3. The method according to claim 1, characterized in that the annular magnetic sensor array is composed of magnetic sensors, end electromechanical connection plates and end mechanical connection plates, the magnetic sensors are fixed on the end mechanical connection plates and the end electromechanical connection plates, the magnetic sensors are multi-turn-aliasing PCB type hollow coils engraved with shaped windings, and the number of the magnetic sensors is a multiple of 3;
the multi-turn aliasing PCB type hollow coil adopts a multi-turn close winding mode and a multi-layer board process, and all windings have the same direction.
4. The method according to claim 1, wherein the obtaining the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by interpolation according to the magnetic field signal and the spatial position information of each sensor comprises:
carrying out Fourier analysis on the magnetic field signals of each sensor, and calculating a magnetic field amplitude matrix and a phase matrix under power frequency;
calculating a magnetic sensor space angle matrix according to the position of each sensor in the polar coordinate system;
and respectively calculating a circumferential magnetic field quasi-continuous observation amplitude sequence and a phase sequence of the cable to be detected by an interpolation method, and calculating a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected according to the amplitude sequence and the phase sequence.
5. A three-phase cable electrified state recognition system, comprising:
the database construction module is used for constructing a three-phase cable circumferential magnetic field analytic model according to the geometric parameter information of the three-phase cable to be detected, analyzing and calculating circumferential theoretical magnetic field amplitude and phases of the cable in different electrified states to obtain a cable circumferential theoretical magnetic field phasor sequence, and constructing a cable circumferential magnetic field phasor database;
the annular magnetic sensor array is used for synchronously measuring voltage analog signals representing the circumferential magnetic field intensity of the cable to be measured;
the conditioning circuit is used for receiving and conditioning the voltage signals output by the annular magnetic sensor array and outputting magnetic field signals at each sensor;
the data processing module is used for receiving the magnetic field signals and obtaining a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by an interpolation method according to the magnetic field signals and the spatial position information of each sensor;
and the state identification module is used for calculating observation-theoretical correlation coefficients of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected and all theoretical magnetic field phasor sequences in the cable circumferential magnetic field phasor database, sequencing the theoretical magnetic field phasor sequences according to the observation-theoretical correlation coefficients, and selecting a theoretical charged state corresponding to the theoretical magnetic field phasor sequence with the highest correlation as an actual charged state of the three-phase cable.
6. The system of claim 5, wherein the database building module comprises:
the model building unit is used for building a three-phase cable circumferential magnetic field analytic model by taking the cable center as a coordinate origin according to the cable radius, the phase core radius and the distance between the cable center and each phase core, and calculating the coordinates of each core wire;
and the magnetic field phasor calculation unit is used for calculating the amplitude and the phase of a circumferential theoretical magnetic field of the cable when the three phases of the cable to be detected normally run, the cable is in phase failure and the cable is in power failure based on the three-phase cable circumferential magnetic field analytic model to obtain a circumferential theoretical magnetic field phasor sequence of the cable.
7. The system according to claim 5, characterized in that said annular magnetic sensor array is composed of magnetic sensors, end electromechanical connection plates and end mechanical connection plates, the magnetic sensors are fixed on the end mechanical connection plates and the end electromechanical connection plates, the magnetic sensors are multi-turn-aliasing PCB type hollow coils engraved with shaped windings, and the number of the magnetic sensors is a multiple of 3;
the multi-turn aliasing PCB type hollow coil adopts a multi-turn close winding mode and a multi-layer board process, and all windings have the same direction.
8. The system of claim 5, wherein the obtaining of the circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be measured by interpolation according to the magnetic field signal and the spatial position information of each sensor comprises:
carrying out Fourier analysis on the magnetic field signals of each sensor, and calculating a magnetic field amplitude matrix and a phase matrix under power frequency;
calculating a magnetic sensor space angle matrix according to the position of each sensor in the polar coordinate system;
and respectively calculating a circumferential magnetic field quasi-continuous observation amplitude sequence and a phase sequence of the cable to be detected by an interpolation method, and calculating a circumferential magnetic field quasi-continuous observation phasor sequence of the cable to be detected according to the amplitude sequence and the phase sequence.
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