CN114239332A - Cable grounding wire heating research and treatment method based on magnetic adjacent three-phase reactor - Google Patents
Cable grounding wire heating research and treatment method based on magnetic adjacent three-phase reactor Download PDFInfo
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Abstract
The invention relates to the technical field of reactors, in particular to a cable grounding wire heating research and treatment method based on a magnetic adjacent three-phase reactor. Which comprises the following steps: calculating to obtain a current value of the armor layer grounding wire; obtaining the temperature distribution of the cable terminal; laying a novel magnetic isolation plate in a region with dense magnetic lines of force, and verifying the effect of the novel magnetic isolation plate on the heating research and treatment through an electric reactor and a cable armor layer electromagnetic field model; and a magnetic isolation groove box is additionally arranged on the cable armor layer. According to the invention, the novel magnetic isolation plate is laid and the magnetic isolation groove box is additionally arranged, so that double magnetic isolation is carried out on heating of a cable grounding wire adjacent to the three-phase reactor, the safety is improved, the heating of a nearby metal structural member is avoided, the influence on the performance of electrical equipment is avoided, the current value of the grounding wire of the armor layer is loaded to the cable terminal as excitation, and the obtained temperature calculation result of the cable terminal is closer to the actual result.
Description
Technical Field
The invention relates to the technical field of reactors, in particular to a cable grounding wire heating research and treatment method based on a magnetic adjacent three-phase reactor.
Background
The dry-type air-core reactor is used as one of main inductive elements of an alternating current transmission system, has the advantages of low loss, low noise, simple maintenance, good linearity of reactance value, long design life and the like, and is applied to power grids more and more widely. However, due to the special structure of the air reactor, a symmetrical and divergent magnetic field can be generated during normal operation, which causes the heating of nearby metal structural members and influences the performance of electrical equipment.
At present, aiming at the research of abnormal heating treatment of equipment near a reactor, various treatment measures are mainly provided on the heating problem of the adjacent equipment under the action of a leakage magnetic field of a single-phase reactor, such as increasing the distance between the reactor and a closed metal loop, eliminating the closed metal loop, additionally arranging a shielding body on the reactor, and the like; however, in the problem of heating of adjacent cable grounding wires caused by combined action of three-phase reactors in a transformer substation with determined layout of each electrical device, a measure for changing the position of the device cannot be realized, and a measure for installing a shielding body on the reactor is difficult to construct, low in economic efficiency and capable of influencing safe operation of the reactor.
Disclosure of Invention
The invention aims to provide a cable grounding wire heating research and treatment method based on a magnetic adjacent three-phase reactor, so as to solve the problems in the background technology.
In order to achieve the aim, the invention provides a cable grounding wire heating research and treatment method based on a magnetic adjacent three-phase reactor, which comprises the following steps:
s1, establishing an electromagnetic field model of the reactor and the cable armor layer according to the actual structural data of the reactor and the cable, forming a closed loop between the armor layer and the ground, and calculating by finite element numerical values to obtain a current value of the armor layer grounding wire;
s2, establishing a finite element model of the cable terminal, and loading the current value of the grounding wire of the armor layer as excitation to the cable terminal for flow field and temperature field coupling numerical calculation to obtain the temperature distribution of the cable terminal;
s3, conducting finite element numerical analysis on a large-area magnetic shield plate established on the surface of the ground on the basis of an electric reactor and a cable armor layer electromagnetic field model to obtain the current value of the grounding wire of the armor layer with the magnetic shield plate and the distribution situation of the magnetic lines of force on the magnetic shield plate, laying a novel magnetic shield plate in a magnetic line intensive area according to the distribution situation of the magnetic lines of force on the magnetic shield plate, and verifying the heating research and treatment effect of the novel magnetic shield plate through the electric reactor and the cable armor layer electromagnetic field model;
s4, installing the magnetic isolation groove boxes on the cable armor layer according to the temperature distribution of the cable terminal, and verifying the heating research and treatment effect by installing the magnetic isolation groove boxes through the electric reactor and the cable armor layer electromagnetic field model.
When the device is used specifically, the electric reactor and the cable armor layer electromagnetic field model are established in advance, the current value of the armor layer grounding wire is obtained conveniently through finite element numerical calculation, then the current value of the armor layer grounding wire is loaded to a cable terminal as excitation to carry out flow field and temperature field coupling numerical calculation, and the heating research and treatment effects are verified on laying of the novel magnetic isolation plate and installing of the magnetic isolation groove box, so that the heating of the cable grounding wire adjacent to the three-phase electric reactor is doubly isolated, the safety is improved, and the heating of adjacent metal structural parts and the influence on the performance of electrical equipment are avoided.
As a further improvement of the present technical solution, in S1, the expression of the closed loop formed between the armor layer and the ground is:
Re＝RgL
wherein R isg0.0000493 Ω/m is ground resistance per unit length, and L is the cable line length.
As a further improvement of the technical solution, in S1, a calculation formula of the current value of the armor layer ground wire obtained by finite element numerical calculation is as follows:
wherein the content of the first and second substances,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density, i.e. the current density loaded by the reactor; v1An eddy current area, namely a cable armor layer, can generate induced eddy current due to the influence of an alternating magnetic field; v2Is the source current region, i.e. the reactor envelope.
As a further improvement of the present technical solution, the calculating of the temperature distribution of the cable termination in S2 includes:
electromagnetic field control equation:
in the formula (I), the compound is shown in the specification,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density is the current density loaded on the end face of the armor layer at the bottom of the cable terminal head; j is the current density of the conductor; q is the electromagnetic loss; v3The eddy current zone is a conductor except for an armor layer, and can generate induced eddy current due to the influence of an alternating magnetic field; v4Is a source current area, namely an armor layer; omega is the conductor area which generates electromagnetic loss in calculation;
natural convection momentum differential equation:
where ρ is the air density; v. ofx、vy、vzIs the velocity component of air in the x, y, z directions; alpha is alphaVIs the coefficient of air expansion; g is the acceleration of gravity; t is the solved air temperature; t is∞Is a temperature value at which the temperature tends to be steady; η is the dynamic viscosity of air;
temperature field control equation:
where ρ is the air density; c is the air specific heat capacity; k is the air thermal conductivity;
is the laplacian operator; t is the solved air temperature; q is heat; k is a radical ofx、ky、kzAnisotropy parameters respectively representing thermal conductivity; t is the solved air temperature.
As a further improvement of the technical solution, the new magnetic shield in S3 includes the following steps:
establishing a large-area magnetic shield on the surface of the ground in the electromagnetic field model to perform electromagnetic field finite element numerical calculation to obtain the current value of the armor layer grounding wire after the magnetic shield is additionally arranged and the distribution condition of the magnetic lines of force of the three-phase reactor on the magnetic shield;
and reserving the region with dense magnetic lines of force and removing the region with sparse magnetic lines of force according to the density degree of the magnetic lines of force on the magnetic shield, thereby obtaining the novel magnetic shield.
As a further improvement of the technical scheme, the S4 magnetic isolation slot box is made of an iron material.
As a further improvement of the technical solution, the verification of the treatment effect of the heating research by adding the magnetism isolating groove box in S4 includes the following steps:
firstly, a magnetic isolation groove box is additionally arranged on the cable armor layer on the established reactor and cable armor layer electromagnetic field model for electromagnetic field finite element numerical calculation, the current value of the grounding wire of the armor layer after the groove box is additionally arranged is obtained and is compared with the current value of the actually measured grounding wire, and if the current value is reduced, the effect of inhibiting the current of the grounding wire by additionally arranging the magnetic isolation groove box is good.
Compared with the prior art, the invention has the beneficial effects that:
1. according to the cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor, the novel magnetic isolation plate is laid and the magnetic isolation groove box is additionally arranged, so that the cable grounding wire adjacent to the three-phase reactor is heated to perform double magnetic isolation, the safety is improved, and the heating of nearby metal structural parts and the influence on the performance of electrical equipment are avoided.
2. According to the cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor, the current value of the grounding wire of the armor layer is loaded to the cable terminal as excitation, the obtained temperature calculation result of the cable terminal is closer to the actual result, and the accuracy of temperature calculation is improved.
Drawings
FIG. 1 is an overall flow chart of example 1 of the present invention;
fig. 2 is a reactor-cable three-dimensional simulation model according to embodiment 1 of the present invention;
FIG. 3 is a diagram of a magnetic shield simulation model according to embodiment 1 of the present invention;
fig. 4 is a schematic view of a magnetic isolation slot box installed on a cable armor layer in embodiment 1 of the invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments 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.
Examples
Referring to fig. 1 to 4, the present embodiment provides a method for researching and managing heating of a cable grounding wire based on a magnetic proximity three-phase reactor, including the following steps:
s1, establishing an electromagnetic field model of the reactor and the cable armor layer according to the actual structural data of the reactor and the cable, forming a closed loop between the armor layer and the ground, and calculating by finite element numerical values to obtain a current value of the armor layer grounding wire;
the reactor and the cable armor layer electromagnetic field model are an integral three-dimensional model, when the reactor model is established, the thickness of end insulation and outer insulation of an envelope is ignored, according to a surface current density equivalent principle, the annular columns with the same size are adopted to represent the envelope, a plurality of coaxial annular columns are established to represent the reactor, the cable armor layer three-dimensional model is established for an annular tube structure according to the cable armor layer, and according to the reactor position, the height, the cable line trend, the cable length, the cable buried depth and other factors, the integral three-dimensional model of the three-phase reactor and the cable armor layer is established, specifically, as shown in figure 2, the three-dimensional model sequentially comprises a cold-shrinkage three-finger sleeve, a PVC belt, an outer sheath, an armor layer and an inner sheath from outside to inside, and the outer wall of the armor layer is connected with a grounding wire.
Specifically, in S1, the expression of the closed loop formed between the armor layer and the ground is:
Re＝RgL
wherein R isg0.0000493 omega/m is the ground resistance under the unit length, and L is the cable line length;
and setting ground resistance according to ground resistance data measured at two ends of the armor layer on site, calculating the ground resistance Re through the length of the cable and a ground resistance band human expression, and then carrying out equivalence on the ground resistance and the ground resistance by adopting an equivalent resistance to form a closed loop between the armor layer and the ground.
Further, in S1, the formula for calculating the current value of the ground wire of the armor layer through finite element numerical calculation is as follows:
wherein the content of the first and second substances,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density, i.e. the current density loaded by the reactor; v1An eddy current area, namely a cable armor layer, can generate induced eddy current due to the influence of an alternating magnetic field; v2A source current region, namely a reactor envelope;
and loading the encapsulation loading phase and the current density with the same size of each phase reactor in the three-phase reactor group according to the phase and the actually measured current data of each reactor of the three-phase reactor in the transformer substation, and carrying out finite element numerical calculation on the calculation formula to obtain the current value of the grounding wire of the armor layer.
S2, establishing a finite element model of the cable terminal, and loading the current value of the grounding wire of the armor layer as excitation to the cable terminal for flow field and temperature field coupling numerical calculation to obtain the temperature distribution of the cable terminal;
specifically, the cable terminal finite element model is established according to the actual structure of the cable terminal, namely the cable terminal finite element three-dimensional model, the reactor is loaded and calculated according to the actual operation power frequency current provided by the transformer substation, the obtained calculation result of the grounding wire current of the armor layer is closer to the actual result, the current value of the grounding wire of the armor layer is loaded to the cable terminal as excitation, the obtained calculation result of the temperature of the cable terminal is closer to the actual result, and the accuracy of temperature calculation is improved.
In order to improve the accuracy of the temperature calculation, the calculation of the temperature distribution of the cable termination in S2 includes:
electromagnetic field control equation:
in the formula (I), the compound is shown in the specification,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density is the current density loaded on the end face of the armor layer at the bottom of the cable terminal head; j is the current density of the conductor; q is the electromagnetic loss; v3The eddy current zone is a conductor except for an armor layer, and can generate induced eddy current due to the influence of an alternating magnetic field; v4Is a source current area, namely an armor layer; omega is the conductor area which generates electromagnetic loss in calculation;
natural convection momentum differential equation:
where ρ is the air density; v. ofx、vy、vzIs the velocity component of air in the x, y, z directions; alpha is alphaVIs the coefficient of air expansion; g is the acceleration of gravity; t is the solved air temperature; t is∞Is a temperature value at which the temperature tends to be steady; η is the dynamic viscosity of air;
temperature field control equation:
where ρ is the air density; c is the air specific heat capacity; k is the air thermal conductivity;
is the laplacian operator; t is the solved air temperature; q is heat; k is a radical ofx、ky、kzAnisotropy parameters respectively representing thermal conductivity; t is the solved air temperature.
Because the cable terminal is about 1.5m away from the ground, the surface of the cable terminal is in contact with the air, the heat dissipation form is natural convection of the air, the current of the grounding wire is converted into current density which is used as excitation and loaded on the end surface of the armor layer at the bottom of the cable terminal, the bottom end of the copper braided belt exposed outside is arranged as grounding, and the temperature distribution condition caused by the electromagnetic loss of the cable terminal is obtained by carrying out finite element calculation on an electromagnetic field control equation, a natural convection momentum differential equation and a temperature field control equation.
S3, conducting finite element numerical analysis on a large-area magnetic isolation plate established on the surface of the ground on the basis of an electric reactor and a cable armor layer electromagnetic field model to obtain the current value of an armor layer grounding wire with the magnetic isolation plate and the distribution situation of magnetic lines of force on the magnetic isolation plate, laying a novel magnetic isolation plate in a magnetic line dense area according to the distribution situation of the magnetic lines of force on the magnetic isolation plate, verifying the heating research and treatment effect of the novel magnetic isolation plate through the electric reactor and the cable armor layer electromagnetic field model, and binding a magnetic field below a three-phase electric reactor through laying the magnetic isolation plate to provide a new solution idea and theoretical basis for the heating problem of a cable grounding wire adjacent to the three-phase electric reactor;
in order to enable the new-type magnetic shield plate to be more effective in research and treatment of heating of a cable grounding wire, the new-type magnetic shield plate in S3 comprises the following steps:
establishing a large-area magnetic shield on the surface of the ground in the electromagnetic field model to perform electromagnetic field finite element numerical calculation to obtain the current value of the armor layer grounding wire after the magnetic shield is additionally arranged and the distribution condition of the magnetic lines of force of the three-phase reactor on the magnetic shield;
and reserving the region with dense magnetic lines of force and removing the region with sparse magnetic lines of force according to the density degree of the magnetic lines of force on the magnetic shield, thereby obtaining the novel magnetic shield.
S4, installing the magnetism isolating groove box on the cable armor layer according to the temperature distribution of the cable terminal, verifying the effect of installing the magnetism isolating groove box on the research and treatment of heating through the electric reactor and the electromagnetic field model of the cable armor layer, and further performing magnetism isolating treatment on the cable armor layer through installing the magnetism isolating groove box, thereby providing a new solution idea and a theoretical basis for the heating problem of the cable grounding wire adjacent to the three-phase electric reactor.
The S4 magnetic isolation groove box is made of iron materials, known cable lines are arranged adjacent to the three-phase reactor, the cable lines are represented as cable armor layer three-dimensional models, and the magnetic isolation groove box is sleeved on the outer wall of the cable armor layer to achieve the effect of an isolation magnetic field.
Specifically, the verification of the treatment effect of the additionally-installed magnetism isolating groove box on the heating research in the S4 includes the following steps:
firstly, the magnetic isolation groove box is additionally arranged on the cable armor layer on the established electric reactor and cable armor layer electromagnetic field model for electromagnetic field finite element numerical calculation, the current value of the grounding wire of the armor layer after the groove box is additionally arranged is obtained and is compared with the current value of the actually measured grounding wire, if the current value is reduced, the effect of additionally arranging the magnetic isolation groove box for restraining the current of the grounding wire is good, and therefore the effect of the additionally arranged magnetic isolation groove box for researching and treating the heating of the cable grounding wire adjacent to the three-phase electric reactor is good.
When the device is used specifically, the electric reactor and the cable armor layer electromagnetic field model are established in advance, the current value of the armor layer grounding wire is obtained conveniently through finite element numerical calculation, then the current value of the armor layer grounding wire is loaded to a cable terminal as excitation to carry out flow field and temperature field coupling numerical calculation, and the heating research and treatment effects are verified on laying of the novel magnetic isolation plate and installing of the magnetic isolation groove box, so that the heating of the cable grounding wire adjacent to the three-phase electric reactor is doubly isolated, the safety is improved, and the heating of adjacent metal structural parts and the influence on the performance of electrical equipment are avoided.
For example: selecting a cable grounding wire heating example, firstly establishing 11 coaxial circular ring column representation reactors with the same size as the encapsulation according to the fact that the number of the reactors is 11, the width of an air passage is 25mm, the inner diameter of a coil is 1800mm, the outer diameter of the coil is 2700mm, and the ground clearance is 3591mm, establishing a cable armor layer three-dimensional model for a circular tube with the thickness of 2mm according to a cable armor layer, and then establishing a three-phase reactor and cable armor layer integral three-dimensional model according to multiple factors such as the position, the height, the cable line trend, the cable buried depth and the like of a three-phase reactor on site of a transformer substation, as shown in figure 2;
the grounding resistance measured on site is 1 omega, the length of the cable is 18 meters, so the ground resistance is 0.0008874 calculated according to a ground resistance formula; carrying out equivalence on the grounding resistor and the earth resistor by adopting equivalent resistance;
then, performing electromagnetic field finite element numerical calculation by taking the encapsulation loading current density of each single-phase reactor in the three-phase reactors as excitation to obtain a current value of 54.34A of the grounding wire of the armor layer, wherein the relative error between the current value and the actual measured value of 53.3A of the grounding wire is 1.8%;
the method comprises the steps of establishing a cable terminal finite element model according to an actual structure of the cable terminal, considering that the surface of the cable terminal is naturally subjected to convection and heat dissipation by air, taking the grounding wire current as an excitation condition to load the cable terminal, and adopting a finite element method to carry out direct coupling calculation of an electric field, a flow field and a temperature field to obtain the temperature distribution condition of the cable terminal, wherein under the condition that the environment temperature and the grounding wire current are the same, the actually measured error of the highest temperature of 73.8 ℃ is 3.6%, and the positions where the highest temperature occurs are the same.
Constructing a magnetic shield plate with the radius of 5m on the established reactor and cable armor layer electromagnetic field model to carry out electromagnetic field finite element numerical calculation, obtaining that the current value of the grounding wire of the armor layer is 3.938A after the magnetic shield plate is added, and the current value is reduced by 92.6 percent compared with the actually measured current value of the grounding wire of 53.3A, proving that the effect of the magnetic shield plate for inhibiting the current of the grounding wire is good, and obtaining the distribution condition of the magnetic lines of force of the three-phase reactor on the magnetic shield plate;
specifically, as shown in fig. 3, the magnetic lines of force are mainly concentrated in the middle area of the magnetic shield, the farther the magnetic shield is from the center of the magnetic shield, the more sparse the magnetic lines of force are, the magnetic shield area with dense magnetic lines of force is reserved, and the magnetic shield area with sparse magnetic lines of force is removed, so that the obtained novel magnetic shield can be used as a heating treatment measure for a cable grounding wire near a three-phase reactor;
meanwhile, as shown in fig. 4, electromagnetic field finite element numerical calculation is performed on the cable armor layer with the iron material groove box, the current value of the grounding wire of the armor layer after the groove box is added is 4.654a, and is reduced by 91.3% compared with the actually measured current value of the grounding wire of 53.3A, the effect of adding the magnetic shield to inhibit the current of the grounding wire is proved to be good, and the obtained groove box added to the cable armor layer can be used as a heating control measure for the grounding wire of the cable near the three-phase reactor.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. A cable grounding wire heating research and treatment method based on a magnetic adjacent three-phase reactor is characterized by comprising the following steps:
s1, establishing an electromagnetic field model of the reactor and the cable armor layer according to the actual structural data of the reactor and the cable, forming a closed loop between the armor layer and the ground, and calculating by finite element numerical values to obtain a current value of the armor layer grounding wire;
s2, establishing a finite element model of the cable terminal, and loading the current value of the grounding wire of the armor layer as excitation to the cable terminal for flow field and temperature field coupling numerical calculation to obtain the temperature distribution of the cable terminal;
s3, conducting finite element numerical analysis on a large-area magnetic shield plate established on the surface of the ground on the basis of an electric reactor and a cable armor layer electromagnetic field model to obtain the current value of the grounding wire of the armor layer with the magnetic shield plate and the distribution situation of the magnetic lines of force on the magnetic shield plate, laying a novel magnetic shield plate in a magnetic line intensive area according to the distribution situation of the magnetic lines of force on the magnetic shield plate, and verifying the heating research and treatment effect of the novel magnetic shield plate through the electric reactor and the cable armor layer electromagnetic field model;
s4, installing the magnetic isolation groove boxes on the cable armor layer according to the temperature distribution of the cable terminal, and verifying the heating research and treatment effect by installing the magnetic isolation groove boxes through the electric reactor and the cable armor layer electromagnetic field model.
2. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: the expression of the closed loop formed between the armor layer and the ground in the S1 is as follows:
Re＝RgL
wherein R isg0.0000493 Ω/m is ground resistance per unit length, and L is the cable line length.
3. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: in the step S1, the calculation formula of the current value of the armor layer grounding wire obtained through finite element numerical calculation is as follows:
wherein the content of the first and second substances,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density, i.e. the current density loaded by the reactor; v1An eddy current area, namely a cable armor layer, can generate induced eddy current due to the influence of an alternating magnetic field; v2Is the source current region, i.e. the reactor envelope.
4. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: the calculation of the temperature distribution of the cable termination in S2 includes:
electromagnetic field control equation:
in the formula (I), the compound is shown in the specification,
is a Hamiltonian, i.e. a differential operator of a vector;
phasor form of vector magnetic potential;
a phasor form of a scalar potential; j is the imaginary unit of the complex number; omega is frequency, and the frequency of the power grid is 50 Hz; σ is the conductivity; μ is the relative permeability of the conductor region;
the source current density is the current density loaded on the end face of the armor layer at the bottom of the cable terminal head; j is the current density of the conductor; q is the electromagnetic loss; v3The eddy current zone is a conductor except for an armor layer, and can generate induced eddy current due to the influence of an alternating magnetic field; v4Is a source current area, namely an armor layer; omega is the conductor area which generates electromagnetic loss in calculation;
natural convection momentum differential equation:
where ρ is the air density; v. ofx、vy、vzIs the velocity component of air in the x, y, z directions; alpha is alphaVIs the coefficient of air expansion; g is the acceleration of gravity; t is the solved air temperature; t is∞Is a temperature value at which the temperature tends to be steady; η is the dynamic viscosity of air;
temperature field control equation:
where ρ is the air density; c is the air specific heat capacity; k is the air thermal conductivity;
is the laplacian operator; t is the solved air temperature; q is heat; k is a radical ofx、ky、kzAnisotropy parameters respectively representing thermal conductivity; t is the solved air temperature.
5. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: the new magnetic isolation plate in the S3 comprises the following steps:
establishing a large-area magnetic shield on the surface of the ground in the electromagnetic field model to perform electromagnetic field finite element numerical calculation to obtain the current value of the armor layer grounding wire after the magnetic shield is additionally arranged and the distribution condition of the magnetic lines of force of the three-phase reactor on the magnetic shield;
and reserving the region with dense magnetic lines of force and removing the region with sparse magnetic lines of force according to the density degree of the magnetic lines of force on the magnetic shield, thereby obtaining the novel magnetic shield.
6. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: and the magnetic partition box in the S4 is made of an iron material.
7. The cable grounding wire heating research and treatment method based on the magnetic adjacent three-phase reactor as claimed in claim 1, wherein the method comprises the following steps: the verification of the effect of the magnetic isolation groove box on the heat generation research treatment in S4 comprises the following steps:
firstly, a magnetic isolation groove box is additionally arranged on the cable armor layer on the established reactor and cable armor layer electromagnetic field model for electromagnetic field finite element numerical calculation, the current value of the grounding wire of the armor layer after the groove box is additionally arranged is obtained and is compared with the current value of the actually measured grounding wire, and if the current value is reduced, the effect of inhibiting the current of the grounding wire by additionally arranging the magnetic isolation groove box is good.
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