CN116184117A - Cable local defect positioning method, system, equipment and medium - Google Patents
Cable local defect positioning method, system, equipment and medium Download PDFInfo
- Publication number
- CN116184117A CN116184117A CN202310158905.0A CN202310158905A CN116184117A CN 116184117 A CN116184117 A CN 116184117A CN 202310158905 A CN202310158905 A CN 202310158905A CN 116184117 A CN116184117 A CN 116184117A
- Authority
- CN
- China
- Prior art keywords
- unit length
- cable
- cable body
- per unit
- positioning
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000007547 defect Effects 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 68
- 238000001228 spectrum Methods 0.000 claims abstract description 65
- 238000004364 calculation method Methods 0.000 claims abstract description 49
- 238000009413 insulation Methods 0.000 claims abstract description 13
- 238000011426 transformation method Methods 0.000 claims abstract description 11
- 230000006870 function Effects 0.000 claims description 75
- 239000002609 medium Substances 0.000 claims description 48
- 239000004020 conductor Substances 0.000 claims description 44
- 229910052751 metal Inorganic materials 0.000 claims description 37
- 239000002184 metal Substances 0.000 claims description 37
- 239000000463 material Substances 0.000 claims description 24
- 238000003860 storage Methods 0.000 claims description 16
- 238000004458 analytical method Methods 0.000 claims description 14
- 230000014509 gene expression Effects 0.000 claims description 14
- 238000004590 computer program Methods 0.000 claims description 12
- 230000004807 localization Effects 0.000 claims description 10
- 230000035699 permeability Effects 0.000 claims description 10
- 230000008859 change Effects 0.000 claims description 7
- 239000002131 composite material Substances 0.000 claims description 6
- 230000021615 conjugation Effects 0.000 claims description 6
- 239000007062 medium k Substances 0.000 claims description 6
- 230000035515 penetration Effects 0.000 claims description 6
- 230000005684 electric field Effects 0.000 claims description 5
- 238000004088 simulation Methods 0.000 claims description 5
- 230000006698 induction Effects 0.000 claims description 4
- 239000011810 insulating material Substances 0.000 claims description 3
- 230000008569 process Effects 0.000 abstract description 6
- 238000010586 diagram Methods 0.000 description 13
- 230000005540 biological transmission Effects 0.000 description 7
- 238000001514 detection method Methods 0.000 description 7
- 238000009826 distribution Methods 0.000 description 6
- 238000012545 processing Methods 0.000 description 6
- 230000005855 radiation Effects 0.000 description 6
- 230000005672 electromagnetic field Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 238000002224 dissection Methods 0.000 description 2
- 230000002500 effect on skin Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 230000009471 action Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 239000004703 cross-linked polyethylene Substances 0.000 description 1
- 229920003020 cross-linked polyethylene Polymers 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000002310 reflectometry Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/081—Locating faults in cables, transmission lines, or networks according to type of conductors
- G01R31/083—Locating faults in cables, transmission lines, or networks according to type of conductors in cables, e.g. underground
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/08—Locating faults in cables, transmission lines, or networks
- G01R31/088—Aspects of digital computing
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y04—INFORMATION OR COMMUNICATION TECHNOLOGIES HAVING AN IMPACT ON OTHER TECHNOLOGY AREAS
- Y04S—SYSTEMS INTEGRATING TECHNOLOGIES RELATED TO POWER NETWORK OPERATION, COMMUNICATION OR INFORMATION TECHNOLOGIES FOR IMPROVING THE ELECTRICAL POWER GENERATION, TRANSMISSION, DISTRIBUTION, MANAGEMENT OR USAGE, i.e. SMART GRIDS
- Y04S10/00—Systems supporting electrical power generation, transmission or distribution
- Y04S10/50—Systems or methods supporting the power network operation or management, involving a certain degree of interaction with the load-side end user applications
- Y04S10/52—Outage or fault management, e.g. fault detection or location
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Mathematical Physics (AREA)
- Theoretical Computer Science (AREA)
- Locating Faults (AREA)
Abstract
The invention discloses a method, a system, equipment and a medium for locating local defects of a cable, wherein the method comprises the following steps: positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; when the frequency domain reflection spectrum is used for positioning the local defects of the cable, in the process of acquiring a kernel function in a high-voltage cable local defect positioning spectrum function based on an integral transformation method of generalized orthogonal theory, the unit length resistance of the cable body and the unit length inductance of the cable body are acquired through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration. The invention particularly discloses a novel method for acquiring the cable local defect positioning kernel function, which can acquire an accurate positioning kernel function and finally can improve the positioning accuracy of the cable local defect.
Description
Technical Field
The invention belongs to the technical field of cable fault detection, and particularly relates to a method, a system, equipment and a medium for locating local defects of a cable.
Background
Cables (e.g., high voltage cables; high voltage cables are one type of power cable, generally referred to as power cables for transmitting between 1kV and 1000kV, and are commonly used for power transmission and distribution) are key power equipment of urban power transmission networks, and play an extremely important role in smart grids and extra-high voltage engineering. The cable may have various latent insulation defects in the production process, and the cable is also affected by various factors after being put into operation, and the combined action of the factors causes various faults to be easily caused by the cable, so that the safe and stable operation of the power system is affected. In summary, how to quickly and accurately discover faults and determine fault locations is a major problem faced by the current cable operation and maintenance.
In addition, in recent years, a novel cable fault occurs in XLPE insulation corrugated aluminum sheath cables with voltage levels of 110kV and above which are widely used at home and abroad, and the fault position is not a high-voltage cable accessory or a main insulation part but between a metal shielding layer and an insulation shielding layer of the high-voltage cable, namely, a buffer layer defect. Such latent defects cannot be detected using conventional cable fault detection methods (e.g., state detection techniques based on electrical parameters such as breakdown voltage, dielectric loss, leakage current, insulation resistance, etc., withstand voltage tests, partial discharge monitoring techniques, time domain reflectometry, etc.). Illustratively, high voltage cables are typical coaxial transmission lines on which electromagnetic wave transmission problems are commonly analyzed using transmission line theory.
In recent years, researchers at home and abroad apply the frequency domain reflection spectrum detection technology based on the transmission line theory to the fault detection of the high-voltage cable line, and the frequency domain reflection spectrum detection technology can detect and position the defect of the buffer layer of the high-voltage cable; wherein, the accurate positioning spectrum function must be established for the local defect positioning of the high-voltage cable, wherein the kernel function is crucial, and the high-voltage cable must be constructed through the distribution parameters of the high-voltage cable body. The existing kernel function acquisition method has larger error, so that an accurate result cannot be obtained when the frequency domain reflection spectrum detection technology is applied to detect and position the defects of the buffer layer of the high-voltage cable.
Disclosure of Invention
The invention aims to provide a method, a system, equipment and a medium for locating local defects of a cable, which are used for solving one or more technical problems. According to the technical scheme provided by the invention, a novel method for acquiring the cable local defect positioning kernel function is disclosed, an accurate positioning kernel function can be obtained, and finally the positioning accuracy of the cable local defect can be improved.
In order to achieve the above purpose, the invention adopts the following technical scheme:
the invention provides a cable local defect positioning method, which comprises the following steps:
Positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein,
when the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
the expression of the kernel function is that,
K(f,x)＝e -2γx ；
where gamma is the propagation constant of the cable body,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body;
the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration.
The invention further improves that the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained by combining a finite element calculation method and an analytic calculation method, and the method comprises the following steps:
Based on a finite element calculation method, establishing and acquiring a two-dimensional geometric model of the cable body; the cable body two-dimensional geometric model comprises a central conductor, a conductor shielding layer, an insulating shielding layer, a buffer layer, a metal shielding layer and an outer sheath, and material types and material parameters are arranged according to the change rule of each structural material type and material physical parameter of the cable along with temperature and frequency;
carrying out vortex field analysis on the obtained two-dimensional geometric model of the cable body; adding an infinite element domain to the two-dimensional geometric model of the cable body to obtain a two-dimensional finite element model; performing mesh subdivision on the obtained two-dimensional finite element model to obtain a two-dimensional finite element simulation model of mesh subdivision;
calculating by using a frequency domain solving method, obtaining a field solution by calculating through a two-dimensional finite element simulation model, and then converting the field solution obtained by calculation into a resistance and an inductance of a cable body in unit length to obtain a finite element calculation result;
comparing the finite element calculation result with the analysis solution of the resistance and the inductance of the unit length of the cable body, and obtaining the final resistance and the inductance of the unit length of the cable body when the analysis solution meets the preset error requirement.
A further improvement of the invention is that the infinite field is used to simulate an open surface, the descriptive expression at the boundary of the infinite field being,
wherein r is the distance between the source point and the field point; k (k) 0 Is wave number; a is that z Is the component of the magnetic vector in the z-axis; x is x 1 Is the abscissa of the field point; y is 1 Is the ordinate of the field point.
The invention is further improved in that when the frequency domain solving method is used for calculation, the parameterized scanning frequency is set to be 1 Hz-100 MHz.
A further development of the invention is characterized in that, in the step of converting the calculated field solution into a resistance per unit length and an inductance of the cable body,
the calculated expression of the resistance per unit length of the cable body is,
in the formula ,I0 And
the total current and potential difference through the face s, respectively; j (J) * Is the conjugation of the current density vector; e is the electric field intensity vector;
the calculated expression of the inductance per unit length of the cable body is,
wherein B is a magnetic induction intensity vector; w (W) m Is the magnetic field energy; h * Is the conjugation of the magnetic field intensity vector; i 0 Is the total current through the face s.
The invention further improves that in the step of obtaining the analytic solution of the resistance and the inductance of the unit length of the cable body,
The expressions of the resistance and the inductance of the unit length of the cable body are respectively,
R＝real(Z c +Z s) and 
wherein ,
in the formula ,Zc The internal impedance of the central conductor unit length of the cable body; r is (r) 1 Is the radius of the center conductor; m is m c The reciprocal of the composite penetration depth of the center conductor; ρ c Resistivity for the center conductor; a is that c Is the nominal cross-sectional area of the center conductor; j is an imaginary unit; mu (mu) 3 Magnetic permeability for the center conductor; omega is the angular frequency; i 0 (x) Correcting the Bessel function for the first class of 0 th order; i 1 (x) Correcting the Bessel function for the first class of 1; z is Z s The inner impedance of the unit length of the metal shielding layer of the cable body is; m is m s The reciprocal of the composite penetration depth of the metal shielding layer; ρ s Is the resistivity of the metal shielding layer; r is (r) 2 Is the inner radius of the metal shielding layer; r is (r) 3 Is the outer radius of the metal shielding layer; mu (mu) 2 Is the magnetic permeability of the metal shielding layer; k (K) 0 (x) Correcting the Bessel function for the 0 th order second class; k (K) 1 (x) Correcting the Bessel function for the first class of the first order; l (L) e An external inductance per unit length from the central conductor of the cable body to the metal shielding layer; mu (mu) 3 Is the magnetic permeability of the insulating material.
The invention further improves that the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of a cable insulation medium considering a semiconductive layer, and the method comprises the following steps:
The admittance of the unit length of the cable is that the capacitance and the conductance of each layer of insulating medium are firstly connected in parallel, and then the admittances of all layers of insulating medium are connected in series; wherein,
capacitance C per unit length of k-th layer insulating medium k And conductance G k The two kinds of the materials are respectively that,
in the formula ：εk A dielectric constant of the k-th insulating medium; sigma (sigma) k Conductivity of the k-th insulating medium; r is (r) k+1 An outer radius of the k-th insulating medium; r is (r) k Is the inner radius of the k-th insulating medium;
admittance per unit length Y of k-th layer insulating medium k In order to achieve this, the first and second,
admittance Y per unit length of the insulating medium containing N layers between the cable central conductor and the metal shielding layer is,
the conductance per unit length of the cable body and the capacitance per unit length of the cable body are g=re (Y) and c=im (Y)/ω, respectively.
The invention provides a cable local defect positioning system, which comprises:
the positioning module is used for positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein,
when the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
the expression of the kernel function is that,
K(f,x)＝e -2γx ；
where gamma is the propagation constant of the cable body,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body;
the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration.
The invention provides an electronic device, comprising:
at least one processor; the method comprises the steps of,
a memory communicatively coupled to the at least one processor; wherein,
the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the cable partial defect localization method as described in any one of the present invention.
The invention provides a computer readable storage medium storing a computer program which when executed by a processor implements any one of the cable local defect positioning methods described above.
Compared with the prior art, the invention has the following beneficial effects:
in the cable local defect positioning method provided by the invention, the frequency domain reflection spectrum is used for positioning the cable local defect; the method comprises the steps of carrying out conversion from a frequency domain to a space domain through an integral transformation method based on a generalized orthogonal theory, and establishing a positioning spectrum function; the kernel function plays a decisive role in locating the spectral function. According to the technical scheme, a novel method for acquiring the cable local defect positioning kernel function is disclosed, so that an accurate positioning kernel function can be obtained, and finally the positioning accuracy of the cable local defect can be improved; the method comprises the steps of calculating the resistance and inductance of a cable body in a wide frequency domain unit length by adopting a method combining a finite element calculation method and an analytic calculation method; the insulating medium structure of the cable is complex, a layering model of the cable insulating medium considering the semiconductive layer is built, and the conductance and capacitance of the cable body in the wide frequency domain are calculated. In conclusion, the method has great significance for improving the positioning accuracy of the local defects of the cable and has great engineering value.
According to the invention, the calculation method of the resistance and the inductance of the unit length of the cable is suitable for the high-voltage cable with any voltage class, and is simple to operate and convenient to solve; the method for calculating the resistance and the inductance of the unit length of the cable can simultaneously consider the influence of factors such as temperature, frequency and the like on the dielectric parameters of the cable material, can accurately calculate the resistance and the inductance of the unit length of the wide frequency domain of the high-voltage cable body, and solves the problem of calculation accuracy of the resistance and the inductance of the unit length of the wide frequency domain of the high-voltage cable body.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following description of the embodiments or the drawings used in the description of the prior art will make a brief description; it will be apparent to those of ordinary skill in the art that the drawings in the following description are of some embodiments of the invention and that other drawings may be derived from them without undue effort.
FIG. 1 is a flow chart of a kernel acquisition process according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a calculation flow of a resistor per unit length and an inductance per unit length of a high-voltage cable body according to an embodiment of the present invention;
Fig. 3 is a schematic structural view of a high-voltage cable body according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of meshing of a high voltage cable body in an embodiment of the invention;
FIG. 5 is a diagram of meshing of an infinite element field in an embodiment of the invention;
FIG. 6 is a schematic diagram showing a comparison of a result of calculating a finite element of resistance per unit length of a high-voltage cable body and an analytical solution in an embodiment of the present invention;
FIG. 7 is a schematic diagram showing a comparison of the result of calculating the inductance finite element per unit length of the high-voltage cable body and the analytical solution in the embodiment of the present invention;
fig. 8 is a schematic diagram of an equivalent circuit between a high voltage cable center conductor and a metallic shield in an embodiment of the invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
The invention is described in further detail below with reference to the attached drawing figures:
in the embodiment of the invention, when the frequency domain reflection spectrum is used for positioning the local defect of the cable, the conversion from the frequency domain to the space domain is needed by an integral transformation method based on a generalized orthogonal theory, and a positioning spectrum function is established; wherein the kernel function plays a decisive role in locating the spectral function. In order to improve the positioning accuracy, it is necessary to accurately calculate the distributed electrical parameters of the high-voltage cable in the transmission line model, including the resistance per unit length, the inductance per unit length, the conductance per unit length and the capacitance per unit length of the cable body.
In the embodiment of the invention, more analysis algorithms are used in the calculation of the resistance and the inductance of the high-voltage cable body in unit length at the present stage, and the skin effect of the whole frequency band under the broadband is considered; however, the current is uniformly distributed in the very low frequency band, and the skin effect is not generated, so that the current has a large error in the low frequency band. In addition, the structure of the high-voltage cable body is complex, the influence of factors such as the structure of the high-voltage cable body and the characteristics of each layer of medium is required to be considered, particularly, the semiconductor layer of the high-voltage cable body has frequency-dependent characteristics under high frequency, when the dielectric property changes, certain influence is generated on the distribution of the magnetic field in the high-voltage cable body, the analysis and calculation result precision of the unit length resistance and the inductance of the high-voltage cable body can be influenced, and certain error is generated. The finite element calculation method is adopted in the technical scheme of the embodiment, the influence of factors such as temperature, frequency and the like on the dielectric parameters of the materials of each layer of the cable can be simultaneously considered, and the complex physical field can be accurately calculated efficiently according to the set conditions. In summary, the embodiment of the invention establishes a method for accurately calculating the distribution parameters of the high-voltage cable body, and further can obtain an accurate positioning kernel function.
The embodiment of the invention provides a cable local defect positioning method, which comprises the following steps:
positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein when the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is that,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
wherein the kernel function K (F, x) in the cable local defect localization spectrum function F (x) is a function of the frequency F and the cable space position x, and the expression is that,
K(f,x)＝e -2γx ；
where γ is the propagation constant of the cable body.
In the embodiment of the invention, the calculation formula of the propagation constant gamma of the cable body is as follows,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body.
Referring to fig. 1, in the embodiment of the present invention, when obtaining a kernel function K (F, x) in a cable local defect localization spectrum function F (x), taking a high voltage cable local defect localization as an example, the method specifically includes the following steps:
Obtaining the unit length resistance and inductance of the high-voltage cable body in a wide frequency domain; acquiring the conductance and the capacitance of the high-voltage cable body in a wide frequency domain unit length;
calculating and obtaining the propagation constant of the high-voltage cable body based on the obtained parameters;
based on the obtained propagation constant of the high-voltage cable body, a high-voltage cable local defect positioning kernel function K (f, x) is established.
Referring to fig. 2, in the step of obtaining the resistance and inductance of the high-voltage cable body in a wide frequency domain in unit length, the change rule of the physical parameters of each structural material of the high-voltage cable along with the temperature and the frequency is fully considered, and the resistance and the inductance of the unit length are calculated by a mode of combining a finite element calculation method and an analysis method; exemplary specific steps include:
the method comprises the following steps of (1) establishing a two-dimensional geometric model of a high-voltage cable body by using a finite element calculation method, wherein the model comprises a central conductor, a conductor shielding layer, an insulating shielding layer, a buffer layer, a metal shielding layer and an outer sheath; further specific examples thereof include the geometric parameters of the high-voltage cable body including the effective cross-sectional area and radius of the center conductor and the inner and outer radii of the conductor shielding layer, insulating shielding layer, buffer layer (semiconductive water-resistant tape and metallic shielding tape), metallic shielding layer, outer sheath;
Setting material types and material parameters for each layer of the two-dimensional geometric model of the high-voltage cable body according to the change rule of each structural material type and material physical parameter of the high-voltage cable along with temperature and frequency; the material parameters of the high-voltage cable body include conductivity, relative dielectric constant, relative magnetic permeability and dielectric loss, and also include the change rule of the high-voltage cable body along with temperature and frequency;
step (3), carrying out vortex field analysis on the two-dimensional geometric model of the high-voltage cable body, wherein a central conductor and a metal shielding layer in the vortex field are used as a coil group, current 1A is applied to the central conductor, and reverse current flows in the metal shielding layer; adding an infinite element domain to the two-dimensional geometric model, wherein the radius is twice that of the cable body, and establishing a two-dimensional finite element model; wherein,
further exemplary, in step (3) of an embodiment of the present invention, the infinite element field (radiation boundary) is used to extend to an outer boundary at infinity, simulating an open surface, i.e., wave energy is radiated away toward the radiation boundary; the radiation boundaries may be of any shape and close to the model structure; thus, the solution area becomes a limited area.
At the boundary of the infinite element field, the magnetic field is neither parallel nor perpendicular to the boundary, which can be described by equations (1) and (2).
Wherein r is the distance between the source point and the field point; k (k) 0 Is wave number; a is that z Is the component of the magnetic vector in the z-axis; x is x 1 Is the abscissa of the field point; y is 1 Is the ordinate of the field point.
Step (4), performing free triangle mesh dissection on the established two-dimensional finite element model, and establishing a two-dimensional finite element simulation model of mesh dissection; wherein, the grid division needs to be added with boundary layer grids, which is a very typical subdivision method in grid division, and is particularly suitable for eddy current effect in electromagnetic fields;
step (5), setting the parameterized scanning frequency to be 1 Hz-100 MHz by using a frequency domain solving method, and calculating;
step (6), after the field solution is calculated through the high-voltage cable finite element model, converting the calculated field solution into the resistance and the inductance of the high-voltage cable body in unit length; wherein,
the resistance of the high-voltage cable body in unit length is mainly determined by the current distribution of the central conductor and the metal shielding layer, can be obtained by integrating the product of the current density and the electric field intensity, is obtained by the theory of an electromagnetic field,
in the formula ,I0 And
a total current and potential difference across the surface s; j (J) * Is the conjugation of the current density vector; e is the electric field strength vector.
Therefore, the calculation formula of the resistance R per unit length is as follows,
the inductance of the high-voltage cable body in unit length is mainly determined by a magnetic field, an annular magnetic field is generated around the electrified cable, the magnetic induction intensity vector of the annular magnetic field is B, and the magnetic field energy W m The magnetic field energy density can be integrated or the effective value and the inductance value of the cable center wire current can be obtained, the calculation formulas are respectively as follows,
in the formula ,H* Is the conjugation of the magnetic field intensity vector; i 0 Total current passed by the surface s; l is the inductance per unit length.
Therefore, the inductance L per unit length is calculated by the following formula,
step (7), comparing the finite element calculation result with the analysis solution of the resistance and the inductance of the unit length of the high-voltage cable body within 1 Hz-10 MHz, and if the relative error of the two is less than 0.05%, obtaining the resistance and the inductance of the unit length of the high-voltage cable body by the finite element calculation; if the relative error of the two is more than 0.05%, carrying out finite element calculation again, repeating the steps 4-7 until the error is less than 0.05%, and finally obtaining the accurate resistance and inductance of the unit length of the wide-frequency high-voltage cable body; wherein,
The analysis solution of the resistance and inductance of the high-voltage cable body per unit length is as follows:
internal impedance Z of unit length of high-voltage cable body center conductor c The method comprises the following steps:
in the formula ,r1 Is the radius of the center conductor; m is m c The reciprocal of the composite penetration depth of the center conductor; ρ c Resistivity for the center conductor; a is that c Is the nominal cross-sectional area of the center conductor; j is an imaginary unit; mu (mu) 1 Magnetic permeability for the center conductor; omega is the angular frequency; i 0 (x) Correcting the Bessel function for the first class of 0 th order; i 1 (x) Correcting the Bessel function for the first class of 1;
the internal impedance of the unit length of the metal shielding layer of the high-voltage cable body is as follows:
in the formula ,ms The reciprocal of the composite penetration depth of the metal shielding layer; ρ s Is the resistivity of the metal shielding layer; r is (r) 2 Is the inner radius of the metal shielding layer; r is (r) 3 Is the outer radius of the metal shielding layer; mu (mu) 2 Is the magnetic permeability of the metal shielding layer; k (K) 0 (x) Correcting the Bessel function for the 0 th order second class; k (K) 1 (x) Correcting the Bessel function for the first class of the first order;
outer inductance L per unit length from central conductor of high-voltage cable body to metal shielding layer e The method comprises the following steps:
in the formula ,μ3 Is the magnetic permeability of the insulating material;
the analytical calculation formulas of the resistance R and the inductance L of the unit length of the high-voltage cable body are respectively as follows:
R＝real(Z c +Z s )；
In the embodiment of the invention, the insulating medium structure of the high-voltage cable is complex, a layering model of the insulating medium of the high-voltage cable taking the semiconductive layer into consideration is established, and the conductance and the capacitance of the high-voltage cable body in a wide frequency domain unit length are calculated; the specific process may include:
the admittance of the unit length of the high-voltage cable is that the capacitance and the conductance of each layer of insulating medium are firstly connected in parallel, and then the admittances of all layers of insulating medium are connected in series, and the calculation formula is as follows:
capacitance C per unit length of k-th layer insulating medium k And conductance G k The method comprises the following steps of:
in the formula ：εk A dielectric constant of the k-th insulating medium; sigma (sigma) k Conductivity of the k-th insulating medium; r is (r) k+1 An outer radius of the k-th insulating medium; r is (r) k Is the inner radius of the k-th insulating medium.
Admittance per unit length Y of k-th layer insulating medium k The method comprises the following steps:
admittance Y of unit length between the high-voltage cable central conductor and the metal shielding layer containing N layers of insulating mediums is,
the conductance G and the capacitance C of the high-voltage cable in unit length are respectively,
G＝Re(Y)；
C＝Im(Y)/ω。
in the embodiment of the invention, the propagation constant gamma calculation formula of the high-voltage cable body is as follows,
wherein R is the resistance per unit length of the high-voltage cable body; l is inductance per unit length of the high-voltage cable body; g is the conductance per unit length of the high-voltage cable body; c is the capacitance per unit length of the high-voltage cable body.
In the embodiment of the invention, the integral transformation method based on the generalized orthogonal theory has the localized defect positioning spectrum function F (x) of the high-voltage cable as follows
Wherein: z (f) is the frequency domain reflection spectrum of the head end of the high-voltage cable; k (f, x) isLocating a kernel function of the spectral function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the spatial position of the high-voltage cable;
the kernel function K (F, x) in the high-voltage cable local defect localization spectrum function F (x) is a function of the frequency F and the high-voltage cable spatial position x, which plays a decisive role in the localization spectrum function, expressed as,
K(f,x)＝e -2γx 。
the method for acquiring the high-voltage cable local defect positioning kernel function can accurately establish the kernel function in the high-voltage cable local defect positioning spectrum function, and can improve the positioning accuracy of the high-voltage cable local defect; the calculation method of the resistance and the inductance of the unit length of the high-voltage cable is suitable for the high-voltage cable with any voltage class, and is simple to operate and convenient to solve; the method for calculating the resistance and the inductance of the high-voltage cable in unit length can simultaneously consider the influence of factors such as temperature, frequency and the like on the dielectric parameters of the cable material, can accurately calculate the resistance and the inductance of the high-voltage cable body in unit length in wide frequency domain, and solves the problem of calculation accuracy of the resistance and the inductance of the high-voltage cable body in unit length in wide frequency domain.
The specific exemplary steps of the embodiment of the invention for calculating the wide frequency domain resistance and inductance of the high-voltage cable body in unit length specifically comprise the following steps:
(1) Establishing a two-dimensional geometric model of the high-voltage cable body, wherein the model comprises a central conductor, a conductor shielding layer, an insulating shielding layer, a buffer layer, a metal shielding layer and an outer sheath; the geometric parameters comprise the effective sectional area and radius of the central conductor, and the inner and outer radii of a conductor shielding layer, an insulating shielding layer, a buffer layer (a semiconductor water-resistance belt and a metal shielding cloth belt), a metal shielding layer and an outer sheath; specifically, a schematic structural diagram of the high-voltage cable body is shown in fig. 3.
(2) According to the change rule of each structural material type and material physical parameter of the high-voltage cable along with temperature and frequency, setting material types and material parameters for each layer of the two-dimensional geometric model of the high-voltage cable body, wherein the material parameters of the high-voltage cable body comprise conductivity, relative dielectric constant, relative magnetic conductivity and dielectric loss, and meanwhile comprise the change rule of the high-voltage cable body along with temperature and frequency.
(3) Carrying out eddy field analysis on the two-dimensional geometric model of the high-voltage cable body, wherein a central conductor and a metal shielding layer in the eddy field are used as a coil group, current 1A is applied to the central conductor, and reverse current flows in the metal shielding layer; and adding an infinite element domain to the two-dimensional geometric model, wherein the radius is twice as large as that of the cable body, and establishing a two-dimensional finite element model. The infinite element field (radiation boundary) is used to extend to an outer boundary at infinity, simulating an open surface, i.e. wave energy is radiated out towards the radiation boundary. The radiation boundaries may be of any shape and close to the model structure. Thus, the solution area becomes a limited area. At the boundary of the infinite element field, the magnetic field is neither parallel nor perpendicular to the boundary, as shown by the formula in the above embodiment.
(4) Performing free triangle mesh generation on the established two-dimensional finite element model, and establishing a two-dimensional finite element model of mesh generation; the boundary layer grid is required to be added during grid division, which is a very typical subdivision method in grid division, and is particularly suitable for eddy current effect in electromagnetic fields; specifically, the meshing is shown in fig. 4 and 5.
(5) And setting the parameterized scanning frequency to be 1 Hz-100 MHz by using a frequency domain solving method, and calculating.
(6) And after the field solution is calculated through the high-voltage cable finite element model, converting the calculated field solution into the resistance and the inductance of the high-voltage cable body in unit length. The resistance per unit length of the high-voltage cable body is mainly determined by the current distribution of the central conductor and the metal shielding layer, and can be obtained by integrating the product of the current density and the electric field intensity.
The inductance of the high-voltage cable body in unit length is mainly determined by a magnetic field, an annular magnetic field is generated around the electrified cable, the magnetic induction intensity vector of the annular magnetic field is B, and the magnetic field energy W m Can be obtained by integrating the magnetic field energy density or the effective value and the inductance value of the current of the central conductor of the cable.
(7) Within 1 Hz-10 MHz, finite element calculation is performed Comparing the result with the analysis solution of the resistance and the inductance of the unit length of the high-voltage cable body, and if the relative error of the resistance and the inductance of the unit length of the high-voltage cable body is smaller than 0.05%, calculating the resistance and the inductance of the unit length of the high-voltage cable body by using a finite element to obtain the resistance and the inductance of the unit length of the high-voltage cable body; and (3) if the relative error between the two is greater than 0.05%, carrying out finite element calculation again, and repeating the steps (4) to (7) until the error is less than 0.05%, so as to finally obtain the accurate resistance and inductance of the wide-frequency-domain high-voltage cable body in unit length. FIGS. 6 and 7 are 330kV 1X 2000mm, respectively 2 The high-voltage cable is the unit length resistance and inductance of the high-voltage cable body calculated by an example.
The insulating medium structure of the high-voltage cable is complex, a layering model of the insulating medium of the high-voltage cable taking the semiconductive layer into consideration is established, and the conductance and the capacitance of the high-voltage cable body in a wide frequency domain unit length are calculated. The admittance of the unit length of the high-voltage cable is that the capacitance and the conductance of each layer of insulating medium are firstly connected in parallel, and then the admittances of the insulating mediums of each layer are connected in series, as shown in fig. 8.
In summary, the technical scheme provided by the embodiment of the invention can accurately calculate the resistance per unit length, the inductance per unit length, the conductance per unit length and the capacitance per unit length of the wide frequency domain of the high-voltage cable body, so that the propagation constant of the high-voltage cable is obtained, the local defect positioning kernel function of the high-voltage cable can be accurately established, the positioning precision of the local defect of the high-voltage cable can be improved to a great extent, and the method has great reference value and important guiding significance for engineering application. Further specifically explaining, positioning the local defect of the high-voltage cable by using the frequency domain reflection spectrum, converting the frequency domain into the space domain by an integral transformation method based on a generalized orthogonal theory, and establishing a positioning spectrum function, wherein a kernel function K (f, x) plays a decisive role in the positioning spectrum function; the method for acquiring the locating kernel function of the local defect of the high-voltage cable has important significance for improving the locating precision of the local defect of the high-voltage cable and has great engineering value.
The following are device embodiments of the present invention that may be used to perform method embodiments of the present invention. For details of the device embodiment that are not careless, please refer to the method embodiment of the present invention.
The embodiment of the invention provides a cable local defect positioning system, which comprises:
the positioning module is used for positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein,
when the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
the expression of the kernel function is that,
K(f,x)＝e -2γx ；
where gamma is the propagation constant of the cable body,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body;
the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration.
In yet another embodiment of the present invention, a computer device is provided that includes a processor and a memory for storing a computer program including program instructions, the processor for executing the program instructions stored by the computer storage medium. The processor may be a central processing unit (Central Processing Unit, CPU), but may also be other general purpose processor, digital signal processor (Digital Signal Processor, DSP), application specific integrated circuit (Application Specific Integrated Circuit, ASIC), off-the-shelf programmable gate array (Field-Programmable Gate Array, FPGA) or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, etc., which are the computational core and control core of the terminal adapted to implement one or more instructions, in particular to load and execute one or more instructions within a computer storage medium to implement a corresponding method flow or a corresponding function; the processor provided by the embodiment of the invention can be used for the operation of the cable local defect positioning method.
In yet another embodiment of the present invention, a storage medium, specifically a computer readable storage medium (Memory), is a Memory device in a computer device, for storing a program and data. It is understood that the computer readable storage medium herein may include both built-in storage media in a computer device and extended storage media supported by the computer device. The computer-readable storage medium provides a storage space storing an operating system of the terminal. Also stored in the memory space are one or more instructions, which may be one or more computer programs (including program code), adapted to be loaded and executed by the processor. The computer readable storage medium herein may be a high-speed RAM memory or a non-volatile memory (non-volatile memory), such as at least one magnetic disk memory. One or more instructions stored in a computer-readable storage medium may be loaded and executed by a processor to implement the respective steps of the method for localized defect localization in a cable of the above-described embodiments.
It will be appreciated by those skilled in the art that embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical aspects of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those of ordinary skill in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (10)
1. The cable local defect positioning method is characterized by comprising the following steps of:
positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein,
when the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
the expression of the kernel function is that,
K(f,x)＝e -2γx ；
where gamma is the propagation constant of the cable body,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body;
the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration.
2. The method of claim 1, wherein the step of obtaining the resistance per unit length of the cable body and the inductance per unit length of the cable body by a combination of a finite element calculation method and a analytic calculation method comprises:
based on a finite element calculation method, establishing and acquiring a two-dimensional geometric model of the cable body; the cable body two-dimensional geometric model comprises a central conductor, a conductor shielding layer, an insulating shielding layer, a buffer layer, a metal shielding layer and an outer sheath, and material types and material parameters are arranged according to the change rule of each structural material type and material physical parameter of the cable along with temperature and frequency;
carrying out vortex field analysis on the obtained two-dimensional geometric model of the cable body; adding an infinite element domain to the two-dimensional geometric model of the cable body to obtain a two-dimensional finite element model; performing mesh subdivision on the obtained two-dimensional finite element model to obtain a two-dimensional finite element simulation model of mesh subdivision;
calculating by using a frequency domain solving method, obtaining a field solution by calculating through a two-dimensional finite element simulation model, and then converting the field solution obtained by calculation into a resistance and an inductance of a cable body in unit length to obtain a finite element calculation result;
Comparing the finite element calculation result with the analysis solution of the resistance and the inductance of the unit length of the cable body, and obtaining the final resistance and the inductance of the unit length of the cable body when the analysis solution meets the preset error requirement.
3. The method of claim 2, wherein the infinite field is used to simulate an open surface, the descriptive expression at the boundary of the infinite field being,
wherein r is the distance between the source point and the field point; k (k) 0 Is wave number; a is that z Is the component of the magnetic vector in the z-axis; x is x 1 Is the abscissa of the field point; y is 1 Is the ordinate of the field point.
4. The method of claim 2, wherein the frequency of the parametric sweep is set to 1Hz to 100MHz when the calculation is performed using a frequency domain solving method.
5. The method of claim 2, wherein in the step of converting the calculated field solution into a resistance per unit length and an inductance of the cable body,
the calculated expression of the resistance per unit length of the cable body is,
in the formula ,I0 And
the total current and potential difference through the face s, respectively; j (J) * Is the conjugation of the current density vector; e is the electric field intensity vector;
the calculated expression of the inductance per unit length of the cable body is,
Wherein B is a magnetic induction intensity vector; w (W) m Is the magnetic field energy; h * Is the conjugation of the magnetic field intensity vector; i 0 Is the total current through the face s.
6. The method according to claim 2, wherein in the step of obtaining the analytical solution of the resistance and inductance of the unit length of the cable body,
the expressions of the resistance and the inductance of the unit length of the cable body are respectively,
R＝real(Z c +Z s) and 
wherein ,
in the formula ,Zc The internal impedance of the central conductor unit length of the cable body; r is (r) 1 Is the radius of the center conductor; m is m c The reciprocal of the composite penetration depth of the center conductor; ρ c Resistivity for the center conductor; a is that c Is the nominal cross-sectional area of the center conductor; j is an imaginary unit; mu (mu) 3 Magnetic permeability for the center conductor; omega is the angular frequency; i 0 (x) Correcting the Bessel function for the first class of 0 th order; i 1 (x) Correcting the Bessel function for the first class of 1; z is Z s The inner impedance of the unit length of the metal shielding layer of the cable body is; m is m s The reciprocal of the composite penetration depth of the metal shielding layer; ρ s Is the resistivity of the metal shielding layer; r is (r) 2 Is the inner radius of the metal shielding layer; r is (r) 3 Is the outer radius of the metal shielding layer; mu (mu) 2 Is the magnetic permeability of the metal shielding layer; k (K) 0 (x) Correcting the Bessel function for the 0 th order second class; k (K) 1 (x) Correcting the Bessel function for the first class of the first order; l (L) e An external inductance per unit length from the central conductor of the cable body to the metal shielding layer; mu (mu) 3 Is the magnetic permeability of the insulating material.
7. The method of claim 1, wherein the step of obtaining the conductance per unit length of the cable body and the capacitance per unit length of the cable body by creating a layered model of the cable insulation medium taking into account the semiconductive layer comprises:
the admittance of the unit length of the cable is that the capacitance and the conductance of each layer of insulating medium are firstly connected in parallel, and then the admittances of all layers of insulating medium are connected in series; wherein,
capacitance C per unit length of k-th layer insulating medium k And conductance G k The two kinds of the materials are respectively that,
in the formula ：εk A dielectric constant of the k-th insulating medium; sigma (sigma) k Conductivity of the k-th insulating medium; r is (r) k+1 An outer radius of the k-th insulating medium; r is (r) k Is the inner radius of the k-th insulating medium;
admittance per unit length Y of k-th layer insulating medium k In order to achieve this, the first and second,
admittance Y per unit length of the insulating medium containing N layers between the cable central conductor and the metal shielding layer is,
the conductance per unit length of the cable body and the capacitance per unit length of the cable body are g=re (Y) and c=im (Y) ω, respectively.
8. A cable local defect localization system, comprising:
the positioning module is used for positioning the local defects of the cable by using the frequency domain reflection spectrum to obtain a positioning result; wherein,
When the frequency domain reflection spectrum is used for positioning the local defects of the cable, the function F (x) of the positioning spectrum of the local defects of the high-voltage cable based on the integral transformation method of the generalized orthogonal theory is,
wherein Z (f) is the frequency domain reflection spectrum of the head end of the cable; k (f, x) is a kernel function of the location spectrum function; f (f) 1 The upper frequency limit of the frequency domain reflection spectrum; f (f) 2 A lower frequency limit for the frequency domain reflection spectrum; x is the cable space position;
the expression of the kernel function is that,
K(f,x)＝e -2γx ；
where gamma is the propagation constant of the cable body,
wherein R is the resistance per unit length of the cable body; l is inductance per unit length of the cable body; g is the conductance per unit length of the cable body; c is the capacitance per unit length of the cable body;
the resistance per unit length of the cable body and the inductance per unit length of the cable body are obtained through a mode of combining a finite element calculation method and an analytic calculation method; the conductance per unit length of the cable body and the capacitance per unit length of the cable body are obtained by establishing a layering model of the cable insulation medium taking the semiconductive layer into consideration.
9. An electronic device, comprising:
at least one processor; the method comprises the steps of,
a memory communicatively coupled to the at least one processor; wherein,
The memory stores instructions executable by the at least one processor to enable the at least one processor to perform the cable partial defect localization method of any one of claims 1-7.
10. A computer readable storage medium storing a computer program, characterized in that the computer program, when executed by a processor, implements the cable local defect localization method according to any one of claims 1 to 7.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310158905.0A CN116184117A (en) | 2023-02-23 | 2023-02-23 | Cable local defect positioning method, system, equipment and medium |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310158905.0A CN116184117A (en) | 2023-02-23 | 2023-02-23 | Cable local defect positioning method, system, equipment and medium |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN116184117A true CN116184117A (en) | 2023-05-30 |
Family
ID=86445982
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202310158905.0A Pending CN116184117A (en) | 2023-02-23 | 2023-02-23 | Cable local defect positioning method, system, equipment and medium |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN116184117A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116879683A (en) * | 2023-09-04 | 2023-10-13 | 湖南华菱线缆股份有限公司 | Method and device for identifying local defects of high-voltage power cable |
-
2023
- 2023-02-23 CN CN202310158905.0A patent/CN116184117A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116879683A (en) * | 2023-09-04 | 2023-10-13 | 湖南华菱线缆股份有限公司 | Method and device for identifying local defects of high-voltage power cable |
| CN116879683B (en) * | 2023-09-04 | 2023-11-10 | 湖南华菱线缆股份有限公司 | Method and device for identifying local defects of high-voltage power cable |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Zhou et al. | Local degradation diagnosis for cable insulation based on broadband impedance spectroscopy | |
| Gudmundsdottir et al. | Field test and simulation of a 400-kV cross-bonded cable system | |
| CN114019309B (en) | Cable defect positioning method based on frequency domain reflection technology | |
| Zhou et al. | A study on the propagation characteristics of partial discharge in cable joints based on the FDTD method | |
| Behrmann et al. | UHF PD signal transmission in GIS: Effects of 90° bends and an L-shaped CIGRE step 1 test section | |
| CN116184117A (en) | Cable local defect positioning method, system, equipment and medium | |
| Pu et al. | Analysis of voltage distribution characteristics in UHVDC converter transformer winding based on the reduced-scale model | |
| Guardado et al. | A three-phase model for surge distribution studies in electrical machines | |
| Ganjavi et al. | Mathematical model of common-mode sources in long-cable-fed adjustable speed drives | |
| CN117434386A (en) | High-voltage cable sheath defect positioning method based on sheath grounding loop broadband impedance spectrum | |
| CN109799391B (en) | Conductor alternating current resistance measuring method, system and computer storage medium | |
| Reykherdt et al. | Effects of test cable ground extensions on repeatability of frequency response analysis measurements on power transformers | |
| Maier et al. | A high-frequency simulation model of a MV cable joint | |
| CN116859182A (en) | Method and system for positioning defects of high-voltage cable by considering frequency domain reflection spectrum of cable connector | |
| Bai et al. | Comparison of calculation methods of braided shield cable transfer impedance using FSV method | |
| Dalarsson et al. | Using multiple modes to reconstruct conductor locations in a cylindrical model of a power transformer winding | |
| CN106124989A (en) | Turbine generators machines under rotor winding faults diagnostic method based on diagnostic cast and device | |
| Wang et al. | Cable insulation aging simulation | |
| Wunsch et al. | Broadband models of high voltage power transformers and their use in EMC system simulations of high voltage substations | |
| del-Pino-López et al. | Experimental validation of ultra-shortened 3D finite element models for frequency-domain analyses of three-core armored cables | |
| Hou et al. | A novel high frequency circuit model of power cable joint | |
| Li et al. | Feasibility Study on Online Diagnosis of Aging and Deterioration of Medium Voltage (MV) Three-Core Cable Based on Impedance Spectroscopy | |
| Arentsen et al. | MVAC submarine cable, impedance measurements and analysis | |
| Mo et al. | Fault location for coaxial cables based on broadband impedance spectroscopy | |
| Wang et al. | Leakage Currents Separation of Cross-bonded Cables Based on Sheath Current Vector Difference |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |