Method and system for calculating electromagnetic emission along overhead transmission line and electronic equipment

Abstract

The invention discloses a calculation method and system for electromagnetic emission along an overhead transmission line and electronic equipment, and the method comprises the steps: carrying out the numerical calculation according to the first information of a target overhead transmission line and the second information of a target lossy ground, and obtaining a target electrical parameter; establishing a target transmission line model of the target overhead transmission line according to a transmission line theory and the target electrical parameters; obtaining current distribution on the target overhead transmission line according to the target transmission line model; and obtaining electromagnetic emission along the target overhead transmission line according to the current distribution. According to the method, the spatial electromagnetic emission value along the overhead transmission line is directly calculated, and the method has the beneficial effects that the calculation modeling is relatively simple and convenient, the calculation result error is relatively small, the applicable frequency band is wider, and the transverse and longitudinal electromagnetic emission characteristics of the overhead transmission line are simultaneously obtained.

Description

Technical Field

[0001] The present application relates to the field of electric power technology, and in particular to a calculation method, system and electronic equipment for electromagnetic emission along overhead transmission lines. Background Art

[0002] At present, the voltage level of overhead transmission lines is constantly increasing, from the previous 110kV to 220kV high voltage, to 500kV or even higher. The external electromagnetic emission of transmission lines increases accordingly, which may cause potential electromagnetic interference to surrounding radio communications or weak-current sensitive equipment. Therefore, it is necessary to predict and analyze the electromagnetic emission of overhead transmission lines themselves.

[0003] In the prior art, when calculating the electromagnetic emission of overhead transmission lines themselves, usually only the electromagnetic emission of overhead transmission lines at a typical frequency of 0.5 MHz is focused on. Although the lateral (perpendicular to the direction of the overhead transmission lines) electromagnetic emission characteristics of overhead transmission lines can be obtained, the electromagnetic emission characteristics of other frequencies cannot be obtained, let alone the longitudinal (parallel to the direction of the transmission lines) electromagnetic emission characteristics of overhead transmission lines. Summary of the invention

[0004] The main purpose of this application is to provide a calculation method, system and electronic equipment for electromagnetic emission along overhead transmission lines, aiming to solve the technical problem that the existing technical methods for electromagnetic emission along overhead transmission lines have low applicability.

[0005] In a first aspect, to achieve the above-mentioned purpose, the present application provides a method for calculating electromagnetic emission along an overhead transmission line, comprising the following steps:

[0006] Performing numerical calculations based on first information of a target overhead transmission line and second information of a target lossy earth to obtain target electrical parameters, wherein the target electrical parameters are configured as electrical parameters of the target overhead transmission line under the target lossy earth;

[0007] Establishing a target transmission line model of the target overhead transmission line according to transmission line theory and the target electrical parameters;

[0008] According to the target transmission line model, obtaining current distribution on the target overhead transmission line;

[0009] According to the current distribution, electromagnetic emission along the target overhead transmission line is obtained.

[0010] Optionally, the target electrical parameters include at least a first impedance, a second impedance, a first capacitor and a first inductor, wherein the first impedance Z i The second impedance Z is used to represent the impedance inside the target overhead transmission line. gUsed to represent the combined impedance of the target overhead transmission line and the target lossy earth, the first capacitor C is used to represent the combined capacitance of the target overhead transmission line and the target lossy earth, and the first inductor L is used to represent the combined external self-inductance of the target overhead transmission line and the target lossy earth.

[0011] Optionally, the step of performing numerical calculation to obtain target electrical parameters according to the first information of the target overhead transmission line and the second information of the target detrimental earth:

[0012] Obtaining first information parameters according to the first information, and obtaining second information parameters according to the second information, wherein the first information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target overhead transmission line, and the second information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target damaging earth;

[0013] The target electrical parameter is obtained according to the first information parameter and the second information parameter.

[0014] Optionally, the step of obtaining the target electrical parameter according to the first information parameter and the second information parameter includes:

[0015] Obtaining the first impedance according to a first radius of the target overhead transmission line, a first magnetic permeability of the target overhead transmission line, a first electrical conductivity of the target overhead transmission line, and a target frequency;

[0016] Obtaining the second impedance according to the target frequency, a first height between the target overhead transmission line and the target lossy ground, a first propagation constant of the target lossy ground, and a second magnetic permeability of air surrounding the target overhead transmission line;

[0017] Obtaining the first capacitance according to the first radius, the first height, and a first dielectric constant of air around the target overhead transmission line;

[0018] Obtaining the first inductance according to the first radius, the first height and the second magnetic permeability;

[0019] Among them, the expression of the first impedance is: The expression of the second impedance is: The expression of the first capacitance is The expression of the first inductance is r is the first radius, μ i is the first magnetic permeability, σ i is the first conductivity, f is the target frequency, h is the first height, γ g is the first propagation constant, μ0 is the second magnetic permeability, and ε0 is the first dielectric constant.

[0020] Optionally, the step of establishing a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters comprises:

[0021] A third impedance and a second propagation constant are obtained according to the first impedance, the second impedance, the first capacitance and the first inductance, wherein the third impedance is configured as a model characteristic impedance of the target transmission line model, the second propagation constant is configured as a model propagation constant of the target transmission line model, and the expression of the third impedance is: The expression of the second propagation constant is:

[0022] According to the third impedance and the second propagation constant, a first current and a target voltage are obtained and the first current and the target voltage are used as the target transmission line model, wherein the first current is configured as the total current on the target transmission line model, the target voltage is configured as the total voltage on the target transmission line model, and the expression of the first current is I=I + e -γy +I - e γy The target voltage is expressed as U=Z0(I + e -γy -I - e γy ), I + is the forward current on the target transmission line model, I - is the negative current on the target transmission line model, and y is the distance of the target transmission line model along the axial direction.

[0023] Optionally, the step of obtaining the current distribution on the target overhead transmission line according to the target transmission line model comprises:

[0024] Acquire a second current and a model length of the target transmission line model, wherein the second current is configured as an initial current of the target transmission line model, and the model length is configured as a model length of the target transmission line model. ;

[0025] The forward current and the negative current are obtained according to the second current, the model length, the third impedance and the second propagation constant, wherein the relationship between the second current, the model length, the third impedance and the second propagation constant and the forward current and the negative current is expressed as follows: I0 is the second current, y0 is the model length;

[0026] The current distribution is obtained according to the first current, the positive current and the negative current.

[0027] Optionally, the step of obtaining electromagnetic emission along the target overhead transmission line according to the current distribution includes:

[0028] Acquire a first distance from a test point to a first overhead transmission line and a second distance from a test point to a second overhead transmission line, wherein the first overhead transmission line is configured as the target overhead transmission line, and the second overhead transmission line is configured as a mirror image of the target overhead transmission line relative to the ground;

[0029] Acquire a first incident angle between the test point and the first overhead transmission line, and acquire a second incident angle between the test point and the second overhead transmission line;

[0030] The electromagnetic emission is obtained according to the vertical polarization reflection factor of the target lossy earth, the first distance, the second distance, the first incident angle and the second incident angle, wherein the expression of the electromagnetic emission is: d1 is the first distance, d2 is the second distance, is the first incident angle, is the second incident angle, R v is the vertical polarization reflection factor.

[0031] Optionally, the step of obtaining the vertical polarization reflection factor includes:

[0032] Obtaining a third dielectric constant according to a second electrical conductivity, a second dielectric constant, and a dielectric loss tangent of the target lossy earth, wherein the second dielectric constant is configured as a relative dielectric constant of the target lossy earth, and the third dielectric constant is configured as a complex dielectric constant of the target lossy earth;

[0033] According to the Fresnel formula and the third dielectric constant, a reflection coefficient is obtained;

[0034] The amplitude of the reflection coefficient is used as the vertical polarization reflection factor.

[0035] In a second aspect, to achieve the above-mentioned purpose, the present application also provides a calculation system for electromagnetic emission along an overhead transmission line, comprising:

[0036] A first operation module, the first operation module is used to perform numerical calculation according to first information of a target overhead transmission line and second information of a target lossy earth, to obtain a target electrical parameter, wherein the target electrical parameter is configured as an electrical parameter of the target overhead transmission line under the target lossy earth;

[0037] A second operation module, the second operation module is used to establish a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters;

[0038] A third operation module, the third operation module is used to obtain the current distribution on the target overhead transmission line according to the target transmission line model;

[0039] A fourth operation module is used to obtain the electromagnetic emission along the target overhead transmission line according to the current distribution.

[0040] In a third aspect, to achieve the above-mentioned purpose, the present application also provides an electronic device, including:

[0041] A processor and a memory, wherein the memory is used to store a computer program; the processor is used to load and execute the computer program so that the electronic device executes the calculation method of electromagnetic emission along an overhead transmission line as described in any one of the first aspects.

[0042] The beneficial effects that this application can achieve are as follows:

[0043] A method for calculating electromagnetic emission along an overhead transmission line proposed in an embodiment of the present application obtains electrical parameters required for modeling the overhead transmission line based on data from off-site tests by numerical calculation, then establishes a transmission line model based on transmission line theory and electrical parameters, then obtains current distribution on the overhead transmission line through the transmission line model, and finally obtains electromagnetic emission along the overhead transmission line;

[0044] It has realized the direct calculation of the spatial electromagnetic emission values ​​along the overhead transmission lines, and no longer needs to obtain the electromagnetic emission values ​​through field testing;

[0045] When modeling, the entire transmission line is cut off to shorten the model length, and the model disconnection problem caused by direct cutting is solved through impedance matching, making the calculation modeling relatively simple.

[0046] In the actual electromagnetic emission test of transmission lines, the electromagnetic emission on the transmission lines and the ground reflection are collected together. When calculating, not only the electromagnetic emission on the transmission lines is considered, but also the influence of the ground on the electromagnetic emission of the transmission lines is considered. By bringing in the vertical polarization reflection factor, the reflection of the ground on the electromagnetic waves is calculated. The calculation results are more consistent with the actual engineering measurements and can better guide engineering practice.

[0047] It is not only applicable to the 0.5MHz frequency band in the existing standard, but also applicable to the 50Hz to 50MHz frequency band, including the frequency points commonly used in the electromagnetic environment assessment of overhead transmission lines, with a wider frequency band and a wider scope of application;

[0048] The electromagnetic field distribution characteristics along the overhead transmission lines are given, which can not only obtain the lateral (perpendicular to the direction of the overhead transmission lines) electromagnetic emission characteristics of the overhead transmission lines, but also the longitudinal (parallel to the direction of the transmission lines) electromagnetic emission characteristics of the overhead transmission lines, supplementing the existing standards. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 A schematic diagram of a flow chart of a method for calculating electromagnetic emission along an overhead transmission line in the present application;

[0050] Figure 2 A schematic diagram of a method for calculating electromagnetic emission along an overhead transmission line in this application;

[0051] Figure 3 Schematic diagram of impedance calculation method in this application;

[0052] Figure 4 This is a schematic diagram of a system for calculating electromagnetic emissions along overhead transmission lines in this application.

[0054] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0055] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0056] Example 1

[0057] like Figures 1 to 4 As shown, an embodiment of a method for calculating electromagnetic emission along an overhead transmission line comprises the following steps:

[0058] S1. Perform numerical calculation according to first information of a target overhead transmission line and second information of a target lossy earth to obtain a target electrical parameter, wherein the target electrical parameter is configured as an electrical parameter of the target overhead transmission line under the target lossy earth;

[0059] Optionally, the target electrical parameters include at least a first impedance, a second impedance, a first capacitor and a first inductor, wherein the first impedance Z i The second impedance Z is used to represent the impedance inside the target overhead transmission line. g used to represent the combined impedance of the target overhead transmission line and the target lossy earth, the first capacitor C is used to represent the combined capacitance of the target overhead transmission line and the target lossy earth, and the first inductor L is used to represent the combined external self-inductance of the target overhead transmission line and the target lossy earth;

[0060] Further optionally, the step of performing numerical calculation according to the first information of the target overhead transmission line and the second information of the target detrimental earth to obtain the target electrical parameters includes:

[0061] Obtaining first information parameters according to the first information, and obtaining second information parameters according to the second information, wherein the first information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target overhead transmission line, and the second information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target damaging earth;

[0062] Obtaining the target electrical parameter according to the first information parameter and the second information parameter;

[0063] Further optionally, the step of obtaining the target electrical parameter according to the first information parameter and the second information parameter includes:

[0064] Obtaining the first impedance according to a first radius of the target overhead transmission line, a first magnetic permeability of the target overhead transmission line, a first electrical conductivity of the target overhead transmission line, and a target frequency;

[0065] Obtaining the second impedance according to the target frequency, a first height between the target overhead transmission line and the target lossy ground, a first propagation constant of the target lossy ground, and a second magnetic permeability of air surrounding the target overhead transmission line;

[0066] Obtaining the first capacitance according to the first radius, the first height, and a first dielectric constant of air around the target overhead transmission line;

[0067] Obtaining the first inductance according to the first radius, the first height and the second magnetic permeability;

[0068] Among them, the expression of the first impedance is: The expression of the second impedance is: The expression of the first capacitance is The expression of the first inductance is r is the first radius, μ i is the first magnetic permeability, σ i is the first conductivity, f is the target frequency, h is the first height, γ g is the first propagation constant, μ0 is the second magnetic permeability, and ε0 is the first dielectric constant;

[0069] Specifically, the first information may include directly obtainable relevant detailed information of the target overhead transmission line, such as the shape of the target overhead transmission line, the material type of the target overhead transmission line, the number of splits of the target overhead transmission line, the split spacing of the target overhead transmission line, the arrangement of the target overhead transmission line, the length of the target overhead transmission line, the tower specifications, the type of hardware, the distribution of hardware and the distribution of insulators, etc., which represent the physical characteristics of the target overhead transmission line; for example, in addition to the target electrical parameters, the resistivity of the target overhead transmission line, the temperature coefficient of resistance of the target overhead transmission line, the relative permeability of the target overhead transmission line, the surface coefficient of the target overhead transmission line, the corona loss of the target overhead transmission line, the capacitance coefficient between the target overhead transmission lines, the inductance coefficient of the target overhead transmission line and the insulator leakage loss, etc., which represent the electrical characteristics of the target overhead transmission line;

[0070] The first information parameter is a parameter that is acquired and processed from the first information according to the calculation requirements and can be numerically calculated;

[0071] The second information may include relevant detailed information of the target lossy earth that can be directly obtained, such as topographic information of the target lossy earth, building distribution, vegetation distribution, soil type, ambient temperature, ambient humidity, and other information representing physical characteristics of the target lossy earth, and information representing electrical characteristics of the target lossy earth, such as resistivity of the lossy earth, inductance coefficient of the lossy earth, conductivity of the lossy earth, propagation constant of the lossy earth, magnetic permeability of the air above the lossy earth, dielectric constant of the air above the lossy earth, and the like;

[0072] The second information parameter is a parameter that is acquired and processed from the second information according to the calculation requirements and can be numerically calculated;

[0073] In this embodiment, the target electrical parameter may include a first impedance Z i , the second impedance Z g , a first capacitor C and a first inductor L, the corresponding first information parameters may include a first radius r, a first magnetic permeability μ i , the first conductivity σ i , target frequency f and tower height h1, the corresponding second information parameters may include the first propagation constant γ g , the first dielectric constant ε0, the second dielectric constant ε g , the second conductivity σ g , the second magnetic permeability μ0 and the height h2 of the target lossy earth;

[0074] The first height h can be obtained by the tower height h1 and the target damaging ground height h2;

[0075] The first magnetic permeability μ i and the first conductivity σ iIt can be directly obtained by querying the material type of the target overhead transmission line in the first information, or directly obtained by querying the information of the electrical characteristics of the target overhead transmission line in the first information. The target frequency f refers to the frequency of the current of the target overhead transmission line. In the related art, usually only the current frequency of 0.5 MHz is considered as a typical frequency point. In this embodiment, there is no restriction on the target frequency f, and the calculation frequency band is 50 Hz to 50 MHz without affecting the calculation accuracy.

[0076] If the target overhead transmission line is a single conductor, the first radius r is the radius of the target overhead transmission line itself. If the target overhead transmission line is a split conductor, the first radius r is the equivalent radius of the target overhead transmission line. The equivalent radius may be directly queried from the first information, or the second radius of each sub-conductor of the queried split conductor may be obtained by transposing the second radius of each sub-conductor. The conversion relationship between the equivalent radius of the split conductor and the second radius of the sub-conductor is: Among them, r is the equivalent radius of the split wire, that is, the first radius, n is the number of splits of the split wire, r' is the radius of the neutron wire of the split wire, that is, the second radius, d 1i is the distance between the first and the i-th sub-conductors in one phase of the split conductor, i = 2, 3, 4...n;

[0077] If the first propagation constant γ can be directly queried from the second information g The queried values ​​can be used directly for calculation. If they cannot be obtained directly, the corresponding relative dielectric constant and conductivity can be obtained according to the soil type of the target lossy earth in the second information, and then the attenuation constant and phase constant of the target lossy earth can be calculated by combining the vacuum permeability and vacuum dielectric constant. The first propagation constant γ can be obtained according to the attenuation constant and phase constant. g , the expression of the decay constant is The expression of the phase constant is The expression of the first propagation constant is γ g =α+jβ, where ω is the angular frequency, μ is the vacuum permeability, ε is the vacuum dielectric constant, and ε g is the second dielectric constant, i.e. the relative dielectric constant of the target lossy earth, σ g is the second conductivity, i.e. the conductivity of the target damaging earth;

[0078] The second magnetic permeability μ0 is usually very close to the vacuum magnetic permeability μ, and is not sensitive to changes in temperature and humidity. Therefore, the second magnetic permeability μ0 can be considered to be a constant, namely, the vacuum magnetic permeability μ, while the first dielectric constant ε0 will be affected by temperature and humidity. When the calculation accuracy needs to be considered, the first dielectric constant ε0 can be corrected according to the ambient temperature and humidity in the second information to further improve the accuracy of the result.

[0079] S2. establishing a target transmission line model of the target overhead transmission line according to transmission line theory and the target electrical parameters;

[0080] Optionally, the step of establishing a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters comprises:

[0081] A third impedance and a second propagation constant are obtained according to the first impedance, the second impedance, the first capacitance and the first inductance, wherein the third impedance is configured as a model characteristic impedance of the target transmission line model, the second propagation constant is configured as a model propagation constant of the target transmission line model, and the expression of the third impedance is: The expression of the second propagation constant is:

[0082] According to the third impedance and the second propagation constant, a first current and a target voltage are obtained and the first current and the target voltage are used as the target transmission line model, wherein the first current is configured as the total current on the target transmission line model, the target voltage is configured as the total voltage on the target transmission line model, and the expression of the first current is I=I + e -γy +I - e γy The target voltage is expressed as U=Z0(I + e -γy -I - e γy ), I + is the forward current on the target transmission line model, I - is the negative current on the target transmission line model, and y is the distance of the target transmission line model along the axial direction;

[0083] Specifically, after obtaining the first impedance Z i , the second impedance Z g , the first capacitor C and the first inductor L, the transmission line model can be used to establish a target transmission line model of the target overhead transmission line;

[0084] Compared with the prior art, this embodiment does not need to construct a three-dimensional model, and does not need to use the finite element method (FEM) and finite difference method (FDM) when solving the problem, thereby reducing the difficulty of modeling and solving.

[0085] S3. Obtaining current distribution on the target overhead transmission line according to the target transmission line model;

[0086] Optionally, the step of obtaining the current distribution on the target overhead transmission line according to the target transmission line model comprises:

[0087] Acquire a second current and a model length of the target transmission line model, wherein the second current is configured as an initial current of the target transmission line model, and the model length is configured as a model length of the target transmission line model. ;

[0088] The forward current and the negative current are obtained according to the second current, the model length, the third impedance and the second propagation constant, wherein the relationship between the second current, the model length, the third impedance and the second propagation constant and the forward current and the negative current is expressed as follows: I0 is the second current, y0 is the model length;

[0089] Obtaining the current distribution according to the first current, the forward current and the negative current;

[0090] Model length refers to the length of the target transmission line model.

[0091] Specifically, y0 is configured as the model length of the target transmission line model.

[0092] Generally speaking, the length of a transmission line can reach several kilometers or even tens of kilometers. Since the magnetic field H decays freely in space, when constructing a transmission line model, the model length y0 does not need to be very long. According to the H electromagnetic wave spatial attenuation formula:

[0093] H a =32.45+20lg(f a ×d a )

[0094] Among them, H a is the attenuation of the magnetic field when it propagates in space, f a is the frequency at which attenuation is calculated, in MHz, d a is the distance that the magnetic field propagates in space, in km.

[0095] According to this formula, at 0.5MHz, the magnetic field propagates 0.2km in space and attenuates to 12.45dB, and the field strength is attenuated to 0.24 of the original value. The electromagnetic emission of the transmission line is not a strong electromagnetic emission. After attenuating by 12.45dB, it is submerged in the background environmental magnetic field and cannot be measured, so it can be ignored.

[0096] Therefore, when constructing the model, the model length y0 can be no greater than 0.2 km, but in order to ensure the accuracy of the model, the length of y0 is no less than 0.05 km. This greatly reduces the model length, reduces the amount of calculation, and shortens the solution time.

[0097] However, it is unreasonable to directly cut off the transmission line when constructing the model, which will cause the terminal of the model to be open-circuited and the impedance to approach infinity, resulting in a mismatch between the model and the actual situation. In order to solve this problem, a matching impedance Z is connected at the cutoff point of the model. m , the value is consistent with the third impedance, which is like Figure 4 As shown, at this time, due to impedance matching, the current on the model is in a traveling wave state, propagating from the starting end to the end, and no reflected wave will appear, which is consistent with the actual situation.

[0098] Specifically, refer to Figure 2 , just according to the first impedance Z i , the second impedance Z g , the first capacitance C and the first inductance L, the four target information parameters, the third impedance and the second propagation constant can be obtained, and then the second current, the model length, the third impedance and the second propagation constant are substituted into the corresponding relationship expressions to solve the positive current and the negative current, and then the positive current and the negative current are substituted into the expression of the total current in the target transmission line model to obtain the current distribution.

[0099] S4. Obtaining electromagnetic emission along the target overhead transmission line according to the current distribution;

[0100] Optionally, the step of obtaining electromagnetic emission along the target overhead transmission line according to the current distribution includes:

[0101] Acquire a first distance from a test point to a first overhead transmission line and a second distance from a test point to a second overhead transmission line, wherein the first overhead transmission line is configured as the target overhead transmission line, and the second overhead transmission line is configured as a mirror image of the target overhead transmission line relative to the ground;

[0102] Acquire a first incident angle between the test point and the first overhead transmission line, and acquire a second incident angle between the test point and the second overhead transmission line;

[0103] The electromagnetic emission is obtained according to the vertical polarization reflection factor of the target lossy earth, the first distance, the second distance, the first incident angle and the second incident angle, wherein the expression of the electromagnetic emission is: d1 is the first distance, d2 is the second distance, is the first incident angle, is the second incident angle, R v is the vertical polarization reflection factor;

[0104] Further optionally, the step of obtaining the vertical polarization reflection factor includes:

[0105] Obtaining a third dielectric constant according to a second electrical conductivity, a second dielectric constant, and a dielectric loss tangent of the target lossy earth, wherein the second dielectric constant is configured as a relative dielectric constant of the target lossy earth, and the third dielectric constant is configured as a complex dielectric constant of the target lossy earth;

[0106] According to the Fresnel formula and the third dielectric constant, a reflection coefficient is obtained;

[0107] Using the amplitude of the reflection coefficient as the vertical polarization reflection factor;

[0108] Specifically, for any test point P, it is only necessary to obtain the first distance d1 from P to the first overhead transmission line and the second distance d2 from the test point to the second overhead transmission line, as well as the corresponding first incident angle and the second incident angle The electromagnetic emission of any point on the target overhead transmission line to the test point P can be obtained according to the current distribution obtained previously, and the total electromagnetic emission of the target overhead transmission line to the test point P can be obtained after integration;

[0109] The vertical polarization reflection factor refers to the reflection coefficient when the electromagnetic wave is reflected from the interface, considering the vertical polarization (the electric field is perpendicular to the interface). The expression of the third dielectric constant is ε'=ε g ε(1-jtanδ), the expression of reflection coefficient is Among them, ε g is the relative dielectric constant of the target lossy earth, that is, the second dielectric constant, ε is the dielectric constant in vacuum, tanδ is the dielectric loss tangent of the soil, and the corresponding expression is σ g is the conductivity of the target lossy earth, that is, the second conductivity, ε0 ​​is the relative dielectric constant of air, that is, the first dielectric constant, and after obtaining the reflection coefficient R_⊥, the corresponding amplitude can be used as the vertical polarization reflection factor.

[0110] In summary, by adopting this embodiment, the electrical parameters required for modeling the overhead transmission line can be obtained by numerical calculation method based on the data of off-site test, and then the transmission line model is established by transmission line theory and electrical parameters, and then the current distribution on the overhead transmission line is obtained by the transmission line model, and finally the electromagnetic emission along the overhead transmission line is obtained;

[0111] It has realized the direct calculation of the spatial electromagnetic emission values ​​along the overhead transmission lines, and no longer needs to obtain the electromagnetic emission values ​​through field testing;

[0112] The calculation modeling is relatively simple, the calculation result error is small, and the maximum error does not exceed 3dB, which meets the electromagnetic emission test error requirements;

[0113] It is not only applicable to the 0.5MHz frequency band in the existing standard, but also applicable to the 50Hz to 50MHz frequency band, including the frequency points commonly used in the electromagnetic environment assessment of overhead transmission lines, with a wider frequency band and a wider scope of application;

[0114] The electromagnetic field distribution characteristics along the overhead transmission lines are given, which can not only obtain the lateral (perpendicular to the direction of the overhead transmission lines) electromagnetic emission characteristics of the overhead transmission lines, but also the longitudinal (parallel to the direction of the transmission lines) electromagnetic emission characteristics of the overhead transmission lines, supplementing the existing standards.

[0115] Example 2

[0116] like Figure 4 As shown, an embodiment of a system for calculating electromagnetic emissions along an overhead transmission line includes:

[0117] A first operation module, the first operation module is used to perform numerical calculation according to first information of a target overhead transmission line and second information of a target lossy earth, to obtain a target electrical parameter, wherein the target electrical parameter is configured as an electrical parameter of the target overhead transmission line under the target lossy earth;

[0118] A second operation module, the second operation module is used to establish a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters;

[0119] A third operation module, the third operation module is used to obtain the current distribution on the target overhead transmission line according to the target transmission line model;

[0120] A fourth operation module is used to obtain the electromagnetic emission along the target overhead transmission line according to the current distribution.

[0121] Example 3

[0122] An electronic device, comprising a processor and a memory, wherein the memory is used to store a computer program; the processor is used to load and execute the computer program, so that the electronic device executes the calculation method of electromagnetic emission along an overhead transmission line as described in any one of the above

[0123] In the above embodiments of the present disclosure, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0124] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0125] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed over multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0126] In addition, each functional unit in each embodiment of the present disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0127] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable non-volatile storage medium. Based on this understanding, the technical solution of the present disclosure is essentially or the part that contributes to the prior art or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a non-volatile storage medium, including a number of instructions to enable a computer device (which can be a personal computer, server or network device, etc.) to perform all or part of the steps of the various embodiments of the present disclosure. The aforementioned non-volatile storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, disk or optical disk and other media that can store program codes.

[0128] The above are only preferred embodiments of the present disclosure. It should be pointed out that, for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present disclosure. These improvements and modifications should also be regarded as the protection scope of the present disclosure.

Claims

1. A method for calculating electromagnetic emission along an overhead transmission line, characterized in that: The following steps are involved: Performing numerical calculations based on first information of a target overhead transmission line and second information of a target lossy earth to obtain target electrical parameters, wherein the target electrical parameters are configured as electrical parameters of the target overhead transmission line under the target lossy earth; Establishing a target transmission line model of the target overhead transmission line according to transmission line theory and the target electrical parameters; According to the target transmission line model, obtaining current distribution on the target overhead transmission line; According to the current distribution, electromagnetic emission along the target overhead transmission line is obtained.

2. The method for calculating electromagnetic emission along an overhead transmission line according to claim 1, characterized in that: The target electrical parameters include at least a first impedance, a second impedance, a first capacitance and a first inductance, wherein the first impedance Z i The second impedance Z is used to represent the impedance inside the target overhead transmission line. g Used to represent the combined impedance of the target overhead transmission line and the target lossy earth, the first capacitor C is used to represent the combined capacitance of the target overhead transmission line and the target lossy earth, and the first inductor L is used to represent the combined external self-inductance of the target overhead transmission line and the target lossy earth.

3. A method for calculating electromagnetic emission along an overhead transmission line as claimed in claim 2, characterized in that: The step of performing numerical calculation according to the first information of the target overhead transmission line and the second information of the target damaging earth to obtain the target electrical parameters comprises: Obtaining first information parameters according to the first information, and obtaining second information parameters according to the second information, wherein the first information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target overhead transmission line, and the second information parameters are configured as parameters representing electrical characteristics and physical characteristics of a target damaging earth; The target electrical parameter is obtained according to the first information parameter and the second information parameter.

4. A method for calculating electromagnetic emission along an overhead transmission line as claimed in claim 3, characterized in that: The step of obtaining the target electrical parameter according to the first information parameter and the second information parameter comprises: Obtaining the first impedance according to a first radius of the target overhead transmission line, a first magnetic permeability of the target overhead transmission line, a first electrical conductivity of the target overhead transmission line, and a target frequency; Obtaining the second impedance according to the target frequency, a first height between the target overhead transmission line and the target lossy ground, a first propagation constant of the target lossy ground, and a second magnetic permeability of air surrounding the target overhead transmission line; Obtaining the first capacitance according to the first radius, the first height, and a first dielectric constant of air around the target overhead transmission line; Obtaining the first inductance according to the first radius, the first height and the second magnetic permeability; Among them, the expression of the first impedance is: The expression of the second impedance is: The expression of the first capacitance is The expression of the first inductance is r is the first radius, μ i is the first magnetic permeability, σ i is the first conductivity, f is the target frequency, h is the first height, γ g is the first propagation constant, μ0 is the second magnetic permeability, and ε0 is the first dielectric constant.

5. A method for calculating electromagnetic emission along an overhead transmission line as claimed in claim 2, characterized in that: The step of establishing a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters comprises: A third impedance and a second propagation constant are obtained according to the first impedance, the second impedance, the first capacitance and the first inductance, wherein the third impedance is configured as a model characteristic impedance of the target transmission line model, the second propagation constant is configured as a model propagation constant of the target transmission line model, and the expression of the third impedance is: The expression of the second propagation constant is According to the third impedance and the second propagation constant, a first current and a target voltage are obtained and the first current and the target voltage are used as the target transmission line model, wherein the first current is configured as the total current on the target transmission line model, the target voltage is configured as the total voltage on the target transmission line model, and the expression of the first current is I=I + e -γy +I - e γy The target voltage is expressed as U=Z0(I + e -γy -I - e γy ), I + is the forward current on the target transmission line model, I - is the negative current on the target transmission line model, and y is the distance of the target transmission line model along the axial direction.

6. A method for calculating electromagnetic emission along an overhead transmission line as claimed in claim 5, characterized in that: The step of obtaining the current distribution on the target overhead transmission line according to the target transmission line model comprises: Acquire a second current and a model length of the target transmission line model, wherein the second current is configured as an initial current of the target transmission line model, and the model length is configured as a model length of the target transmission line model; The forward current and the negative current are obtained according to the second current, the model length, the third impedance and the second propagation constant, wherein the relationship between the second current, the model length, the third impedance and the second propagation constant and the forward current and the negative current is expressed as follows: I0 is the second current, y0 is the model length; The current distribution is obtained according to the first current, the positive current and the negative current.

7. A method for calculating electromagnetic emission along an overhead transmission line according to claim 6, characterized in that: The step of obtaining electromagnetic emission along the target overhead transmission line according to the current distribution comprises: Acquire a first distance from a test point to a first overhead transmission line and a second distance from a test point to a second overhead transmission line, wherein the first overhead transmission line is configured as the target overhead transmission line, and the second overhead transmission line is configured as a mirror image of the target overhead transmission line relative to the ground; Acquire a first incident angle between the test point and the first overhead transmission line, and acquire a second incident angle between the test point and the second overhead transmission line; The electromagnetic emission is obtained according to the vertical polarization reflection factor of the target lossy earth, the first distance, the second distance, the first incident angle and the second incident angle, wherein the expression of the electromagnetic emission is: d1 is the first distance, d2 is the second distance, is the first incident angle, is the second incident angle, R v is the vertical polarization reflection factor.

8. A method for calculating electromagnetic emission along an overhead transmission line according to claim 6, characterized in that: The step of obtaining the vertical polarization reflection factor comprises: Obtaining a third dielectric constant according to a second electrical conductivity, a second dielectric constant, and a dielectric loss tangent of the target lossy earth, wherein the second dielectric constant is configured as a relative dielectric constant of the target lossy earth, and the third dielectric constant is configured as a complex dielectric constant of the target lossy earth; According to the Fresnel formula and the third dielectric constant, a reflection coefficient is obtained; The amplitude of the reflection coefficient is used as the vertical polarization reflection factor.

9. A system for calculating electromagnetic emissions along an overhead transmission line, characterized in that: include: A first operation module, the first operation module is used to perform numerical calculation according to first information of a target overhead transmission line and second information of a target lossy earth, to obtain a target electrical parameter, wherein the target electrical parameter is configured as an electrical parameter of the target overhead transmission line under the target lossy earth; A second operation module, the second operation module is used to establish a target transmission line model of the target overhead transmission line according to the transmission line theory and the target electrical parameters; A third operation module, the third operation module is used to obtain the current distribution on the target overhead transmission line according to the target transmission line model; A fourth operation module is used to obtain the electromagnetic emission along the target overhead transmission line according to the current distribution.

10. An electronic device, characterized in that: include: A processor and a memory, wherein the memory is used to store a computer program; the processor is used to load and execute the computer program so that the electronic device executes the method for calculating electromagnetic emissions along an overhead transmission line as described in any one of claims 1-8.

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