Method and device for calculating power frequency magnetic field in transformer substation

Abstract

The invention provides a method and a device for calculating a power frequency magnetic field in a transformer substation, and belongs to the field of electromagnetic environment calculation of a power system. The method comprises the following steps: establishing a power frequency magnetic field calculation model considering geomagnetic permeability and any erection mode of a power transmission line; calculating the current element magnetic induction intensity generated by the current element at any point in the space based on the model; through coordinate translation and rotation transformation, a coordinate transformation relation corresponding to the power transmission line erected at any angle is obtained, and the power frequency magnetic field intensity generated by the power transmission line erected at any angle at any point in the space is calculated; for a three-phase AC power transmission line, power frequency magnetic field intensity generated by each phase line at any point in space is superposed, and the total power frequency magnetic field intensity of the point is obtained. According to the method, the model containing the geomagnetic permeability and any line erection mode is established, and the power frequency magnetic field adaptive to the line at any angle is calculated based on the model, so that the calculation accuracy of the power frequency magnetic field distribution of the transformer substation is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic environment calculation technology for power systems, specifically relating to a method and apparatus for calculating power frequency magnetic fields in substations. Background Technology

[0002] With the ever-increasing demand for electricity in modern society, power systems are continuously developing towards higher voltage and larger capacity. In this development process, substations, as key hubs of the power system, are increasingly facing prominent electromagnetic environment issues. Among these, power frequency magnetic fields, as an important component of the electromagnetic environment, have a significant impact on the surrounding environment and equipment.

[0003] While power frequency magnetic fields don't produce the same noticeable electric shock as power frequency electric fields, prolonged exposure to strong power frequency magnetic fields can pose potential threats to human health and may also interfere with the normal operation of secondary equipment in substations, such as relay protection devices and automation equipment. Therefore, accurately calculating the intensity and spatial distribution of the power frequency magnetic field within a substation is crucial. Currently, numerous methods exist for calculating power frequency magnetic fields, such as the Biot-Savart law method, the finite element method, and the finite difference method, all of which are applied in various engineering scenarios.

[0004] However, in the unique environment of a substation, due to the non-constant permeability of the earth, the diverse installation angles of transmission lines, and the phase differences in three-phase currents, existing calculation methods struggle to comprehensively and accurately calculate the distribution of the power frequency magnetic field. For instance, common calculation methods based on the Biot-Savart law typically treat the earth as an ideal conductor, neglecting variations in its actual permeability and assuming that transmission lines are installed parallel to the ground. Furthermore, they are not accurate enough in handling the phase of three-phase currents, all of which lead to significant deviations between the calculated results and the actual situation. Summary of the Invention

[0005] In view of this, the present invention provides a method and apparatus for calculating the power frequency magnetic field in a substation, aiming to solve the problems existing in the prior art when calculating the power frequency magnetic field distribution in a substation, such as ignoring the influence of the earth's magnetic permeability, not considering the arbitrary erection of transmission lines, and insufficient consideration of the phase of the three-phase current, thereby improving the accuracy of the calculation results, comprehensively reflecting the distribution law of the power frequency magnetic field, and providing a reliable calculation basis for related work in substations.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows:

[0007] In a first aspect, the present invention provides a method for calculating the power frequency magnetic field in a substation, comprising the following steps:

[0008] Establish a calculation model for the power frequency magnetic field that takes into account the geomagnetic permeability and the arbitrary erection method of transmission lines;

[0009] Based on the power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic induction intensity of the current element generated at any point in space by the current element.

[0010] By using coordinate translation and rotation transformations, the coordinate transformation relationship corresponding to the transmission line erected at any angle is obtained. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field intensity generated by the transmission line erected at any angle at any point in space is calculated.

[0011] For a three-phase AC transmission line, the total power frequency magnetic field intensity at any point in space is obtained by superimposing the power frequency magnetic field intensity generated by each phase line at any point in space.

[0012] Furthermore, a calculation model for the power frequency magnetic field, considering the Earth's magnetic permeability and arbitrary transmission line erection methods, is established, including:

[0013] The model is set with the following assumptions: the earth is considered as an infinitely large magnetic medium; the transmission line is located above the earth and its direction is arbitrary; the magnetic permeability on both sides of the interface is the air magnetic permeability and the earth magnetic permeability, respectively.

[0014] Decompose any current element vector in space into the sum of three components of the coordinate axes;

[0015] Based on the model assumptions and current element components, determine the current in any direction in space and its corresponding mirror current.

[0016] Furthermore, based on the power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic induction intensity of the current element generated at any point in space, including:

[0017] The calculation boundary and environmental parameters of the current element are determined based on the power frequency magnetic field calculation model;

[0018] Based on the computational boundary and environmental parameters, and combined with the current element components, a magnetic field infinitesimal element calculation formula including the contribution of the image current is constructed using the Biot-Savart law.

[0019] Based on the magnetic field element calculation formula, the magnetic field element including the contribution of the mirror current is integrated along the length of the conductor, and the variable substitution is performed in combination with the line erection scenario to obtain the magnetic induction intensity of the current element generated by the conductor current element at the target point.

[0020] Furthermore, through coordinate translation and rotation transformations, the coordinate transformation relationship corresponding to the transmission line erected at any angle is obtained. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field intensity generated by the transmission line erected at any angle at any point in space is calculated, including:

[0021] After translating the origin of the original coordinate system to a turning point of the transmission line, the coordinate system is rotated around the new origin so that the extension direction of the line segment coincides with the x' axis of the new coordinate system, thus obtaining the local coordinate system corresponding to the line segment.

[0022] Based on matrix transformation theory, a coordinate transformation matrix from the original coordinate system to the local coordinate system is constructed by using the orientation angles of each axis of the local coordinate system in the original coordinate system.

[0023] The transformation relationship between the local coordinate system and the original coordinate system is established based on the coordinate transformation matrix. Based on the transformation relationship and the magnetic induction intensity of the current element, the magnetic field components of the target point in the original coordinate system are determined.

[0024] Obtain the coordinates of all inflection points of the transmission line, calculate the magnetic field components generated by each straight conductor segment at the target point, and perform vector superposition to obtain the power frequency magnetic field intensity generated by the entire transmission line erected at any angle at the target point.

[0025] Furthermore, for a three-phase AC transmission line, the total power frequency magnetic field intensity at any point in space is obtained by superimposing the power frequency magnetic field intensity generated by each phase line at that point, including:

[0026] Calculate the power frequency magnetic field strength generated at any point in space by the A-phase, B-phase, and C-phase transmission lines, respectively.

[0027] Based on the principle of magnetic field superposition, the power frequency magnetic field intensities of each phase are vector-superimposed to obtain the total power frequency magnetic field intensity at the target point in space.

[0028] In a second aspect, the present invention provides a power frequency magnetic field calculation device for a substation, comprising:

[0029] The model building module is used to establish a power frequency magnetic field calculation model that takes into account the geomagnetic permeability and arbitrary erection methods of transmission lines;

[0030] The magnetic flux density calculation module is used to calculate the magnetic flux density of the current element generated at any point in space based on the power frequency magnetic field calculation model and the Biot-Savart law.

[0031] The first power frequency magnetic field strength calculation module is used to obtain the coordinate transformation relationship corresponding to the transmission line erected at any angle through coordinate translation and rotation transformation, and to calculate the power frequency magnetic field strength generated at any point in space by the transmission line erected at any angle based on the coordinate transformation relationship and the magnetic induction intensity of the current element.

[0032] The second power frequency magnetic field strength calculation module is used to superimpose the power frequency magnetic field strength generated by each phase line at any point in space for a three-phase AC transmission line, and obtain the total power frequency magnetic field strength at that point.

[0033] Furthermore, in the model building module, a power frequency magnetic field calculation model considering the Earth's magnetic permeability and arbitrary transmission line erection methods is established, including:

[0034] The model is set with the following assumptions: the earth is considered as an infinitely large magnetic medium; the transmission line is located above the earth and its direction is arbitrary; the magnetic permeability on both sides of the interface is the air magnetic permeability and the earth magnetic permeability, respectively.

[0035] Decompose any current element vector in space into the sum of three components of the coordinate axes;

[0036] Based on the model assumptions and current element components, determine the current in any direction in space and its corresponding mirror current.

[0037] Furthermore, in the magnetic flux density calculation module, based on the power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic flux density of the current element generated at any point in space, including:

[0038] The calculation boundary and environmental parameters of the current element are determined based on the power frequency magnetic field calculation model;

[0039] Based on the computational boundary and environmental parameters, and combined with the current element components, a magnetic field infinitesimal element calculation formula including the contribution of the image current is constructed using the Biot-Savart law.

[0040] Based on the magnetic field element calculation formula, the magnetic field element including the contribution of the mirror current is integrated along the length of the conductor, and the variable substitution is performed in combination with the line erection scenario to obtain the magnetic induction intensity of the current element generated by the conductor current element at the target point.

[0041] Furthermore, in the first power frequency magnetic field strength calculation module, the coordinate transformation relationship corresponding to the transmission line erected at any angle is obtained through coordinate translation and rotation transformation. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field strength generated by the transmission line erected at any angle at any point in space is calculated, including:

[0042] After translating the origin of the original coordinate system to a turning point of the transmission line, the coordinate system is rotated around the new origin so that the extension direction of the line segment coincides with the x' axis of the new coordinate system, thus obtaining the local coordinate system corresponding to the line segment.

[0043] Based on matrix transformation theory, a coordinate transformation matrix from the original coordinate system to the local coordinate system is constructed by using the orientation angles of each axis of the local coordinate system in the original coordinate system.

[0044] The transformation relationship between the local coordinate system and the original coordinate system is established based on the coordinate transformation matrix. Based on the transformation relationship and the magnetic induction intensity of the current element, the magnetic field components of the target point in the original coordinate system are determined.

[0045] Obtain the coordinates of all inflection points of the transmission line, calculate the magnetic field components generated by each straight conductor segment at the target point, and perform vector superposition to obtain the power frequency magnetic field intensity generated by the entire transmission line erected at any angle at the target point.

[0046] Furthermore, in the second power frequency magnetic field strength calculation module, for a three-phase AC transmission line, the power frequency magnetic field strength generated by each phase line at any point in space is superimposed to obtain the total power frequency magnetic field strength at that point, including:

[0047] Calculate the power frequency magnetic field strength generated at any point in space by the A-phase, B-phase, and C-phase transmission lines, respectively.

[0048] Based on the principle of magnetic field superposition, the power frequency magnetic field intensities of each phase are vector-superimposed to obtain the total power frequency magnetic field intensity at the target point in space.

[0049] Thirdly, the present invention also provides a computer device, the device including a processor and a memory:

[0050] The memory is used to store computer programs and send the instructions of the computer programs to the processor;

[0051] The processor executes instructions from the computer program, such as the first aspect, a method for calculating the power frequency magnetic field within a substation.

[0052] Fourthly, the present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements a method for calculating the power frequency magnetic field in a substation as described in the first aspect.

[0053] In summary, this invention provides a method and apparatus for calculating the power frequency magnetic field in a substation. The method includes establishing a power frequency magnetic field calculation model considering the Earth's magnetic permeability and arbitrary transmission line installation methods; calculating the magnetic induction intensity of a current element at any point in space using the Biot-Savart law based on the power frequency magnetic field calculation model; obtaining the coordinate transformation relationship corresponding to transmission lines installed at arbitrary angles through coordinate translation and rotation transformations; and calculating the power frequency magnetic field intensity generated at any point in space by transmission lines installed at arbitrary angles based on the coordinate transformation relationship and the magnetic induction intensity of the current element; and for three-phase AC transmission lines, superimposing the power frequency magnetic field intensities generated by each phase at any point in space to obtain the total power frequency magnetic field intensity at that point. This invention significantly improves the accuracy of calculating the power frequency magnetic field distribution in substations by establishing a model that includes the Earth's magnetic permeability and arbitrary line installation methods, and by calculating the power frequency magnetic field adapted to lines at arbitrary angles based on this model. It comprehensively reflects the distribution law of the power frequency magnetic field and provides a reliable basis for related work in substations. Attached Figure Description

[0054] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 A flowchart of a method for calculating the power frequency magnetic field in a substation, provided as an embodiment of the present invention;

[0056] Figure 2 A diagram illustrating the power frequency magnetic field calculation model provided in this embodiment of the invention;

[0057] Figure 3 This is a schematic diagram of coordinate system translation provided in an embodiment of the present invention;

[0058] Figure 4 This is a schematic diagram of coordinate system rotation provided in an embodiment of the present invention;

[0059] Figure 5 A block diagram of a power frequency magnetic field calculation device in a substation provided in an embodiment of the present invention;

[0060] Figure 6 This is a block diagram of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0061] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0062] Please see Figure 1 This embodiment provides a method for calculating the power frequency magnetic field in a substation, including the following steps:

[0063] S11: Establish a power frequency magnetic field calculation model that considers the geomagnetic permeability and the arbitrary erection method of transmission lines.

[0064] It should be noted that the power frequency magnetic field is an alternating magnetic field with the standard frequency for industrial electricity, which is widely present around power facilities such as substations and transmission lines.

[0065] The magnetic permeability of the earth is a characteristic of the earth's ability to conduct magnetic fields. It is an environmental parameter that affects the propagation and distribution of power frequency magnetic fields (the earth is not an ideal vacuum, and its magnetic permeability will change the attenuation law and distribution pattern of the magnetic field). This step incorporates it into the model to improve the realism of the calculation.

[0066] The arbitrary erection method of transmission lines refers to the fact that transmission lines can be arranged in various spatial forms such as horizontal, vertical, inclined, and triangular arrangement to suit the complex actual scenarios of line layout within substations.

[0067] Traditional power frequency magnetic field calculation models often neglect the earth's magnetic permeability (assuming it to be vacuum permeability) or only consider a single erection method such as horizontal or vertical, resulting in significant deviations between the calculation results and actual scenarios. This step constructs a multi-factor coupled power frequency magnetic field calculation model by considering the earth's magnetic permeability (reflecting the earth's influence on the magnetic field) and arbitrary erection methods of transmission lines (covering complex spatial arrangements).

[0068] S12: Based on the power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic induction intensity of the current element generated at any point in space.

[0069] It should be noted that the Biot-Savart law is the fundamental law in electromagnetism for calculating the magnetic field generated by a constant current. Its core is to decompose the current-carrying conductor into countless current elements, calculate the magnetic induction intensity generated by a single current element at a certain point in space through the law, and then obtain the magnetic field distribution of the entire conductor through integration.

[0070] A current element refers to an infinitesimally small segment (with a length approaching zero) in a current-carrying conductor, whose current is a constant value. It is the differential unit for analyzing the magnetic field of a current-carrying conductor. The magnetic field of the entire conductor can be obtained by superimposing (integrating) the magnetic fields of all current elements.

[0071] Magnetic flux density is a physical quantity (unit: Tesla T) that describes the strength and direction of a magnetic field.

[0072] This step discretizes the transmission line into countless current elements, calculates the differential magnetic flux density dB generated by each current element at any target point in space using this law, and then obtains the total magnetic flux density B of a single conductor through integration.

[0073] S13: By using coordinate translation and rotation transformations, the coordinate transformation relationship corresponding to the transmission line erected at any angle is obtained. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field intensity generated by the transmission line erected at any angle at any point in space is calculated.

[0074] It should be noted that coordinate translation and rotation transformation is a method of transforming a spatial coordinate system. Coordinate translation is used to adjust the calculation origin to adapt to different line positions, while coordinate rotation is used to convert lines erected at arbitrary angles into calculation models under a standard coordinate system, thereby achieving a unified calculation logic for different erection angles.

[0075] When transmission lines are erected at non-standard angles such as inclined or triangular arrangements, the spatial direction of their current elements does not coincide with the standard coordinate system (such as the xyz axes), making direct calculation difficult. This step establishes a mapping relationship between the line erected at any angle and the standard coordinate system through coordinate translation (adjusting the calculation origin to the vicinity of the line's starting point or target point) and rotation transformation (converting the line direction to the standard coordinate axis direction). Then, combined with the magnetic induction intensity of the current element, B is transformed back to the original coordinate system using the coordinate transformation formula, and finally, the magnetic field intensity of the line erected at any angle at the target point is obtained by integration.

[0076] S14: For a three-phase AC transmission line, the total power frequency magnetic field strength at that point is obtained by superimposing the power frequency magnetic field strength generated by each phase line at any point in space.

[0077] It should be noted that a three-phase AC transmission line refers to the A, B, and C phase conductors of a substation, with a phase difference of 120° between the currents in each phase, and the magnetic field generated by them has the characteristics of vector superposition.

[0078] Magnetic field strength superposition refers to the vector synthesis of the power frequency magnetic field strength generated by each of the three phase lines at a certain point in space, based on the vector characteristics of the magnetic field, to obtain the actual total magnetic field strength at that point.

[0079] The three-phase currents (A, B, and C) of a three-phase AC transmission line have a phase difference of 120°, and the conductors of each phase are located in different spatial positions. The magnetic field strength they generate is a vector (including magnitude and direction). This step involves vector superposition of the magnetic field strength of each conductor based on the phase relationship of the three-phase currents and the spatial coordinates of each conductor (considering the directional cancellation or enhancement caused by the phase difference), ultimately obtaining the total power frequency magnetic field strength at the target point.

[0080] This embodiment provides a method for calculating the power frequency magnetic field in a substation. This method establishes a model that includes the geomagnetic permeability and arbitrary line erection methods, and calculates the power frequency magnetic field adapted to lines at arbitrary angles based on the model. This significantly improves the accuracy of calculating the power frequency magnetic field distribution in substations, fully reflects its distribution law, and provides a reliable basis for related work in substations.

[0081] In one embodiment of the present invention, a power frequency magnetic field calculation model considering the earth's magnetic permeability and arbitrary transmission line erection methods is established, including:

[0082] S21: Set the model assumptions; the assumptions include treating the earth as an infinitely large magnetic medium; the transmission line is located above the earth and its direction is arbitrary; the magnetic permeability on both sides of the interface is the air magnetic permeability and the earth magnetic permeability, respectively.

[0083] S22: Decompose any current element vector in space into the sum of three components of the coordinate axis;

[0084] S23: Based on the model assumptions and current element components, determine the current in space with arbitrary direction and its corresponding mirror current.

[0085] Please see Figure 2 , Figure 2 A power frequency magnetic field calculation model is presented. Substations have high line voltage levels, generating strong magnetic fields. Since the metal shielding of 5G equipment provides almost no shielding against power frequency magnetic fields, magnetic field strength is one of the factors causing interference to 5G equipment and secondary equipment. Because the transmission lines within substations are relatively short, the effects of line sag and long-distance transmission spans on the power frequency magnetic field calculation are not considered. Before analyzing the influencing factor of geomagnetic permeability, the following assumptions are made:

[0086] 1. The Earth is considered an infinitely large magnetic medium;

[0087] 2. The transmission line is located above the ground and its direction is arbitrary. The height of the transmission line above the ground is h.

[0088] 3. The permeabilities on both sides of the interface are respectively (air permeability) and (Magnetic permeability of the earth).

[0089] according to Figure 2 The computational model shown decomposes the current element vector at a point in space into the sum of three components of the coordinate axes, as shown in Equation 1.

[0090] (1)

[0091] In the formula, IdI represents the current element vector, I is the current intensity, dx, dy, and dz are the components of the current element line segment in the spatial rectangular coordinate system along the x, y, and z axes, respectively, and e is the current element vector. x e y e z It is a unit vector in the x, y, z coordinate axes.

[0092] If the current element remains unchanged within the effective region, the uniqueness of the magnetic field solution can be determined. Therefore, the expressions for the current and the image current in space with arbitrary directions are shown in Equation 2.

[0093] (2)

[0094] In the formula, This is the mirror current.

[0095] In one embodiment of the present invention, based on a power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic induction intensity of the current element generated at any point in space by the current element, including:

[0096] S31: Determine the calculation boundary and environmental parameters of the current element based on the power frequency magnetic field calculation model.

[0097] For any segment of length in space For a current-carrying conductor, the start and end range (boundary conditions) and permeability parameters (environmental parameters) of the current element are determined based on the power frequency magnetic field calculation model.

[0098] S32: Based on the computational boundary and environmental parameters, and combined with the current element components, a magnetic field infinitesimal element calculation formula including the contribution of the mirror current is constructed using the Biot-Savart law.

[0099] For example, according to the Biot-Savart law and Figure 2 The calculation model shown, by substituting the mirror current, yields the magnetic field generated by the current element at any point in space as follows:

[0100] (3)

[0101] In the formula, It is a line element that provides the source current. The permeability of free space, Let p be the position vector of the current element from point p. For current element and The angle between them It is the unit vector of the direction of magnetic induction intensity.

[0102] S33: Based on the magnetic field element calculation formula, the magnetic field element including the contribution of the mirror current is integrated along the length of the conductor, and the variable substitution is performed in combination with the line erection scenario to obtain the magnetic induction intensity of the current element generated by the conductor current element at the target point.

[0103] For example, integrating Equation 3 and substituting the variables yields the magnetic field strength generated at point p in space, as shown in Equation 4:

[0104] (4)

[0105] In the formula, The magnetic induction intensity of the current element. Let p be the perpendicular distance from point p to the current-carrying conductor. and These are the angles between the current elements at both ends of the conductor and the position vector at point p, respectively.

[0106] In one embodiment of the present invention, the coordinate transformation relationship corresponding to a transmission line erected at an arbitrary angle is obtained through coordinate translation and rotation transformations. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field intensity generated by the transmission line erected at an arbitrary angle at any point in space is calculated, including:

[0107] S41: After translating the origin of the original coordinate system to a turning point of the transmission line, rotate the coordinate system around the new origin so that the extension direction of the line segment coincides with the x' axis of the new coordinate system, thus obtaining the local coordinate system corresponding to the line segment.

[0108] For example, to calculate the power frequency magnetic field of a transmission line at any angle within a substation, the coordinate system O-xyz in the calculation model is first translated to point A of the current-carrying conductor as the origin. After coordinate transformation, P(x,y,z) becomes P(xx,yy,zz). Then, the coordinate system is rotated so that AB coincides with the o'x' direction. The model diagram for coordinate translation and rotation is shown below. Figure 3 and 4 As shown.

[0109] Specifically, coordinate translation is as follows: Figure 3 As shown, the origin of the original coordinate system (O-xyz) is translated to a turning point of the transmission line (e.g., Figure 3 Intermediate current-carrying conductor endpoint A(x) a ,y a ,z a This gives us an intermediate coordinate system (O'-xyz) with a new origin A.

[0110] Coordinate rotation Figure 4 As shown, rotate the intermediate coordinate system (O'-xyz) around the new origin, so that the extension direction of this section of the conductor (as shown) Figure 4 The AB direction in the coordinate system is completely aligned with the x' axis of the new coordinate system after rotation, and the resulting O'-x'y'z' is the local coordinate system.

[0111] S42: Based on matrix transformation theory, construct a coordinate transformation matrix from the original coordinate system to the local coordinate system by utilizing the orientation angles of each axis of the local coordinate system in the original coordinate system.

[0112] According to matrix transformation theory, the relationship of point P after coordinate system transformation is shown in Equation 5:

[0113] (5)

[0114] In the formula, It is the orientation angle of the new coordinate system o'x' in o'-xyz. It is the direction angle of o'y' in the coordinate system o'-xyz. It is the direction angle of o'z' in the coordinate system o'-xyz, and (x,y,z) and (x1,y1,z1) are the coordinates of the target point P in the original coordinate system and the coordinates of the inflection point in the original coordinate system, respectively.

[0115] S43: Establish the transformation relationship between the local coordinate system and the original coordinate system based on the coordinate transformation matrix, and determine the magnetic field components of the target point in the original coordinate system based on the transformation relationship and the magnetic induction intensity of the current element.

[0116] Let the magnetic field components at point P in the coordinate system 0-x'y'z' be... The relationship between the magnetic field transformations between the two coordinate systems is shown in Equation 6:

[0117] (6)

[0118] Straight current-carrying conductor in space With the x-axis coinciding and the current direction along the positive x-axis, the expression for the magnetic field at any point p in space is shown in Equation 7:

[0119] (7)

[0120] S44: Obtain the coordinates of all inflection points of the transmission line, calculate the magnetic field components generated by each straight conductor segment at the target point, and perform vector superposition to obtain the power frequency magnetic field strength generated by the entire transmission line erected at any angle at the target point.

[0121] Transmission lines are typically composed of multiple straight conductors (including multiple inflection points). Therefore, when calculating the power frequency magnetic field strength in the spatial range of several transmission lines and transmission lines erected at arbitrary angles, it is only necessary to know the coordinates of each inflection point in the transmission line, calculate the magnetic field component at any point, and then superimpose them to obtain the power frequency magnetic field strength.

[0122] In one embodiment of the present invention, for a three-phase AC transmission line, the total power frequency magnetic field intensity at that point is obtained by superimposing the power frequency magnetic field intensity generated by each phase line at any point in space, including:

[0123] S51: Calculate the power frequency magnetic field strength generated at any point in space by the A-phase, B-phase, and C-phase transmission lines, respectively;

[0124] S52: Based on the principle of magnetic field superposition, the power frequency magnetic field strength of each phase is vector-superimposed to obtain the total power frequency magnetic field strength of the target point in space.

[0125] Most power transmission methods within substations employ three frequencies with identical potential amplitudes but phase differences of 120°. This refers to a three-phase AC power transmission method. Therefore, when calculating the magnetic field strength of three-phase current-carrying conductors in space, it is necessary to set the phase angle for the current-carrying conductors in the transmission line. The total magnetic field strength at the target point is obtained by superposition theorem.

[0126] (8)

[0127] In the formula B jN Let be the power frequency magnetic field strength generated by the j-phase conductor at any target point in space.

[0128] Based on the same inventive concept, this application also provides a substation power frequency magnetic field calculation device for implementing the above-mentioned substation power frequency magnetic field calculation method. The solution provided by this device is similar to the solution described in the above method. Therefore, the specific limitations in the substation power frequency magnetic field calculation device embodiments provided below can be found in the limitations of the substation power frequency magnetic field calculation method above, and will not be repeated here.

[0129] Please see Figure 5 This invention provides a power frequency magnetic field calculation device for substations, comprising:

[0130] The model building module is used to establish a power frequency magnetic field calculation model that takes into account the geomagnetic permeability and arbitrary erection methods of transmission lines;

[0131] The magnetic flux density calculation module is used to calculate the magnetic flux density of the current element generated at any point in space based on the power frequency magnetic field calculation model and the Biot-Savart law.

[0132] The first power frequency magnetic field strength calculation module is used to obtain the coordinate transformation relationship corresponding to the transmission line erected at any angle through coordinate translation and rotation transformation, and to calculate the power frequency magnetic field strength generated at any point in space by the transmission line erected at any angle based on the coordinate transformation relationship and the magnetic induction intensity of the current element.

[0133] The second power frequency magnetic field strength calculation module is used to superimpose the power frequency magnetic field strength generated by each phase line at any point in space for a three-phase AC transmission line, and obtain the total power frequency magnetic field strength at that point.

[0134] Furthermore, in the model building module, a power frequency magnetic field calculation model considering the Earth's magnetic permeability and arbitrary transmission line erection methods is established, including:

[0135] The model is set with the following assumptions: the earth is considered as an infinitely large magnetic medium; the transmission line is located above the earth and its direction is arbitrary; the magnetic permeability on both sides of the interface is the air magnetic permeability and the earth magnetic permeability, respectively.

[0136] Decompose any current element vector in space into the sum of three components of the coordinate axes;

[0137] Based on the model assumptions and current element components, determine the current in any direction in space and its corresponding mirror current.

[0138] Furthermore, in the magnetic flux density calculation module, based on the power frequency magnetic field calculation model, the Biot-Savart law is used to calculate the magnetic flux density of the current element generated at any point in space, including:

[0139] The calculation boundary and environmental parameters of the current element are determined based on the power frequency magnetic field calculation model;

[0140] Based on the computational boundary and environmental parameters, and combined with the current element components, a magnetic field infinitesimal element calculation formula including the contribution of the image current is constructed using the Biot-Savart law.

[0141] Based on the magnetic field element calculation formula, the magnetic field element including the contribution of the mirror current is integrated along the length of the conductor, and the variable substitution is performed in combination with the line erection scenario to obtain the magnetic induction intensity of the current element generated by the conductor current element at the target point.

[0142] Furthermore, in the first power frequency magnetic field strength calculation module, the coordinate transformation relationship corresponding to the transmission line erected at any angle is obtained through coordinate translation and rotation transformation. Based on the coordinate transformation relationship and the magnetic induction intensity of the current element, the power frequency magnetic field strength generated by the transmission line erected at any angle at any point in space is calculated, including:

[0143] After translating the origin of the original coordinate system to a turning point of the transmission line, the coordinate system is rotated around the new origin so that the extension direction of the line segment coincides with the x' axis of the new coordinate system, thus obtaining the local coordinate system corresponding to the line segment.

[0144] Based on matrix transformation theory, a coordinate transformation matrix from the original coordinate system to the local coordinate system is constructed by using the orientation angles of each axis of the local coordinate system in the original coordinate system.

[0145] The transformation relationship between the local coordinate system and the original coordinate system is established based on the coordinate transformation matrix. Based on the transformation relationship and the magnetic induction intensity of the current element, the magnetic field components of the target point in the original coordinate system are determined.

[0146] Obtain the coordinates of all inflection points of the transmission line, calculate the magnetic field components generated by each straight conductor segment at the target point, and perform vector superposition to obtain the power frequency magnetic field intensity generated by the entire transmission line erected at any angle at the target point.

[0147] Furthermore, in the second power frequency magnetic field strength calculation module, for a three-phase AC transmission line, the power frequency magnetic field strength generated by each phase line at any point in space is superimposed to obtain the total power frequency magnetic field strength at that point, including:

[0148] Calculate the power frequency magnetic field strength generated at any point in space by the A-phase, B-phase, and C-phase transmission lines, respectively.

[0149] Based on the principle of magnetic field superposition, the power frequency magnetic field intensities of each phase are vector-superimposed to obtain the total power frequency magnetic field intensity at the target point in space.

[0150] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is merely an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the system can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units and modules are only for easy differentiation and are not intended to limit the scope of protection of this application. The specific working process of the units and modules in the above system can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0151] Reference Figure 6 The present invention also provides a computer device, including: a memory and a processor, and a computer program stored in the memory. When the computer program is executed on the processor, it implements the substation power frequency magnetic field calculation method as described in any of the above methods.

[0152] The computer device may be a desktop computer, laptop, handheld computer, or cloud server, etc. This computer device may include, but is not limited to, a processor and memory. Those skilled in the art will understand that... Figure 6 The examples of computer devices are merely examples and do not constitute a limitation on computer devices. They may include more or fewer components than shown in the illustration, or combinations of certain components, or different components. For example, they may also include input / output devices, network access devices, etc.

[0153] The processor referred to can be a Central Processing Unit (CPU), but it can also be other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor.

[0154] In some embodiments, the memory may be an internal storage unit of the computer device, such as a hard drive or RAM. In other embodiments, the memory may be an external storage device of the computer device, such as a plug-in hard drive, Smart Media Card (SMC), Secure Digital (SD) card, or Flash Card. Furthermore, the memory may include both internal and external storage units of the computer device. The memory is used to store the operating system, applications, boot loader, data, and other programs, such as the program code of the computer program. The memory can also be used to temporarily store data that has been output or will be output.

[0155] This invention also provides a computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the substation power frequency magnetic field calculation method as described in any of the above methods.

[0156] In this embodiment, if the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or certain intermediate forms. The computer-readable medium can include at least: any entity or device capable of carrying computer program code to a photographing device / terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical carrier signal, a telecommunication signal, and a software distribution medium. Examples include USB flash drives, portable hard drives, magnetic disks, or optical disks. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electrical carrier signals or telecommunication signals.

[0157] This invention provides a computer program product, including a computer program that, when executed by a processor, implements the substation power frequency magnetic field calculation method as described in any of the above methods.

[0158] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0159] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0160] In the embodiments disclosed in this application, it should be understood that the disclosed devices / terminal equipment and methods can be implemented in other ways. For example, the device / terminal equipment embodiments described above are merely illustrative. For instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling or direct coupling or communication connection may be through some interfaces; the indirect coupling or communication connection between devices or units may be electrical, mechanical, or other forms.

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating power frequency magnetic fields in a substation, characterized by, The method comprises the following steps: A power frequency magnetic field calculation model considering the earth magnetic permeability and arbitrary erection mode of the power transmission line is established; Based on the power frequency magnetic field calculation model, the current element magnetic induction intensity generated by the current element at an arbitrary point in space is calculated by using the Biot-Savart law; Through coordinate translation and rotation transformation, the coordinate transformation relationship corresponding to the power transmission line erected at an arbitrary angle is obtained, and based on the coordinate transformation relationship and the current element magnetic induction intensity, the power frequency magnetic field intensity generated by the power transmission line erected at an arbitrary angle at an arbitrary point in space is calculated; For a three-phase alternating current power transmission line, the power frequency magnetic field intensities generated by each phase line at an arbitrary point in space are superimposed to obtain the total power frequency magnetic field intensity at the point.

2. The method of claim 1, wherein, A power frequency magnetic field calculation model considering the earth magnetic permeability and arbitrary erection mode of the power transmission line is established, comprising: Assumption conditions of the model are set; the assumption conditions include regarding the earth as an infinite magnetic medium, the power transmission line being located above the earth and being in an arbitrary direction, and the magnetic permeabilities on both sides of the interface being the air magnetic permeability and the earth magnetic permeability respectively; An arbitrary current element vector in space is decomposed into the sum of three components of the coordinate axes; Based on the model assumption conditions and the current element components, the current in an arbitrary direction in space and the mirror current corresponding to the current are determined.

3. The method of claim 2, wherein, Based on the power frequency magnetic field calculation model, the current element magnetic induction intensity generated by the current element at an arbitrary point in space is calculated by using the Biot-Savart law, comprising: Based on the power frequency magnetic field calculation model, the calculation boundary and the environmental parameters of the current element are determined; Based on the calculation boundary and the environmental parameters, the magnetic field microelement calculation formula containing the mirror current contribution is constructed by using the Biot-Savart law in combination with the current element components; Based on the magnetic field microelement calculation formula, the magnetic field microelement containing the mirror current contribution is integrated along the length of the wire, and variable replacement is performed in combination with the line erection scene to obtain the current element magnetic induction intensity generated by the wire current element at the target point.

4. The method of claim 1, wherein, Through coordinate translation and rotation transformation, the coordinate transformation relationship corresponding to the power transmission line erected at an arbitrary angle is obtained, and based on the coordinate transformation relationship and the current element magnetic induction intensity, the power frequency magnetic field intensity generated by the power transmission line erected at an arbitrary angle at an arbitrary point in space is calculated, comprising: The origin of the original coordinate system is translated to a fold point of the power transmission wire, and then the coordinate system is rotated around the new origin so that the extension direction of the wire coincides with the x' axis of the new coordinate system to obtain a local coordinate system corresponding to the wire; According to the matrix transformation theory, the coordinate transformation matrix from the original coordinate system to the local coordinate system is constructed by using the direction angles of the axes of the local coordinate system in the original coordinate system; The transformation relationship of the magnetic field components between the local coordinate system and the original coordinate system is established according to the coordinate transformation matrix, and the magnetic field components of the target point in the original coordinate system are determined according to the transformation relationship in combination with the current element magnetic induction intensity; The coordinates of all fold points of the power transmission line are obtained, the magnetic field components generated by each straight wire at the target point are calculated respectively, and vector superposition is performed to obtain the power frequency magnetic field intensity generated by the entire power transmission line erected at an arbitrary angle at the target point.

5. The method for calculating power frequency magnetic fields inside a substation according to any of claims 1 to 4, characterized in that, The total power frequency magnetic field intensity of a spatial target point is obtained by vector superposition of the power frequency magnetic field intensities of the three phases according to the magnetic field superposition principle. The power frequency magnetic field intensities generated by the A-phase, B-phase and C-phase transmission lines at an arbitrary point in space are calculated respectively. The total power frequency magnetic field intensity of a spatial target point is obtained by vector superposition of the power frequency magnetic field intensities of the three phases according to the magnetic field superposition principle.

6. A device for calculating a power frequency magnetic field in a substation, characterized by The model construction module is configured to establish a power frequency magnetic field calculation model considering the ground magnetic permeability and the arbitrary erection mode of the transmission line. The magnetic induction intensity calculation module is configured to calculate the current element magnetic induction intensity generated by a current element at an arbitrary point in space based on the power frequency magnetic field calculation model and by using the Biot-Savart law. The first power frequency magnetic field intensity calculation module is configured to obtain the coordinate transformation relationship corresponding to the transmission line erected at an arbitrary angle by coordinate translation and rotation transformation, and to calculate the power frequency magnetic field intensity generated by the transmission line erected at the arbitrary angle at an arbitrary point in space based on the coordinate transformation relationship and the current element magnetic induction intensity. The second power frequency magnetic field intensity calculation module is configured to obtain the total power frequency magnetic field intensity of a point by superimposing the power frequency magnetic field intensities generated by the three-phase transmission lines at the point. In the model construction module, the power frequency magnetic field calculation model considering the ground magnetic permeability and the arbitrary erection mode of the transmission line is established, including:

7. The substation internal power frequency magnetic field calculation device according to claim 6, characterized in that, The model assumption conditions are set, including regarding the ground as an infinite magnetic medium, the transmission line being located above the ground and being oriented arbitrarily, and the magnetic permeabilities on both sides of the interface being the air magnetic permeability and the ground magnetic permeability respectively; The vector of an arbitrary current element in space is decomposed into the sum of three components of the coordinate axes; The direction of an arbitrary current in space and the mirror current corresponding to the current are determined based on the model assumption conditions and the current element components. In the magnetic induction intensity calculation module, the current element magnetic induction intensity generated by a current element at an arbitrary point in space is calculated based on the power frequency magnetic field calculation model and by using the Biot-Savart law, including:

8. The substation internal power frequency magnetic field calculation device according to claim 7, characterized in that, The calculation boundary and environmental parameters of the current element are determined based on the power frequency magnetic field calculation model; The magnetic field microelement calculation formula including the contribution of the mirror current is constructed based on the calculation boundary and environmental parameters, the current element components and the Biot-Savart law; The current element magnetic induction intensity generated by the current element at the target point is obtained by integrating the magnetic field microelement including the contribution of the mirror current along the length of the wire and by substituting the variables in combination with the line erection scenario. In the first power frequency magnetic field intensity calculation module, the coordinate transformation relationship corresponding to the transmission line erected at an arbitrary angle is obtained by coordinate translation and rotation transformation, and the power frequency magnetic field intensity generated by the transmission line erected at the arbitrary angle at an arbitrary point in space is calculated based on the coordinate transformation relationship and the current element magnetic induction intensity, including:

9. The substation internal power frequency magnetic field calculation device according to claim 6, characterized in that, The origin of the original coordinate system is translated to a fold point of the transmission wire, and then the coordinate system is rotated around the new origin so that the extension direction of the wire coincides with the x' axis of the new coordinate system, thereby obtaining a local coordinate system corresponding to the wire segment; ​ According to the matrix transformation theory, a coordinate transformation matrix from the original coordinate system to the local coordinate system is constructed by using the direction angles of each axis of the local coordinate system in the original coordinate system; A transformation relationship of magnetic field components between the local coordinate system and the original coordinate system is established according to the coordinate transformation matrix, and a magnetic field component of a target point in the original coordinate system is determined according to the transformation relationship and the current element magnetic induction intensity; The coordinates of all the inflection points of the power transmission line are obtained, the magnetic field components generated by each straight-line conductor at the target point are calculated respectively, and vector superposition is performed to obtain the power frequency magnetic field intensity generated by the entire power transmission line erected at an arbitrary angle at the target point.

10. The device for calculating power frequency magnetic fields inside a substation according to any of claims 6 to 9, characterized in that, In the second power frequency magnetic field intensity calculation module, for a three-phase alternating current power transmission line, the power frequency magnetic field intensities generated by each phase line at an arbitrary point in space are superimposed to obtain the total power frequency magnetic field intensity at the point, including: The power frequency magnetic field intensities generated by the A-phase, B-phase and C-phase power transmission lines at an arbitrary point in space are calculated respectively; According to the magnetic field superposition principle, the power frequency magnetic field intensities of each phase are subjected to vector superposition to obtain the total power frequency magnetic field intensity at the target point in space.

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