A method and system for determining the electric field strength at a line online monitoring device

Abstract

The present invention discloses a method and system for determining the electric field strength at a line online monitoring device, including: establishing a three-dimensional model of a shared iron tower according to parameter information of a transmission iron tower and a communication equipment antenna; based on the three-dimensional model of the shared iron tower, taking the transmission iron tower and the transmission wire as metal scatterers, loading a power supply according to the transmission power of the communication equipment antenna, and determining a mathematical model of electromagnetic interference of the shared iron tower; determining an electric field integral equation at the line online monitoring device according to the mathematical model of electromagnetic interference of the shared iron tower; calculating the induced current generated on the surface of the shared iron tower, and solving the electric field integral equation using the induced current to determine the electric field strength at the line online monitoring device. The method for determining the electric field strength at the line online monitoring device of the present invention can provide data support for the radio frequency electromagnetic field radiation immunity requirements of the line online monitoring device of the shared iron tower.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic compatibility technology of high-voltage power transmission and transformation engineering, and more specifically, to a method and system for determining the electric field strength at a line online monitoring device. Background Art

[0002] Power and communication shared towers refer to the installation of communication equipment on power towers, and the attachment of communication facilities such as cables, antennas and RRU to the power tower itself, so as to realize the sharing of power and communication infrastructure resources. Shared towers are a new model of social resource sharing. First, using power towers to carry communication facilities can effectively reduce the land resources occupied by newly built communication tower base stations, protect the environment, beautify the landscape, and help build a beautiful China; second, using the densely distributed power towers in the country for communication construction can promote the rapid and wide coverage of communication networks such as 4G and 5G; third, forming a sharing and cooperation model between power and communication companies, promoting power grid companies to improve asset utilization, improve economic benefits, and realize the preservation and appreciation of state-owned assets and amplify functions. Shared towers have great promotion value and broad application prospects. Currently, there are a small number of trials of shared towers, which have verified the feasibility of shared tower technology. However, the trial towers and communication equipment are relatively simple and cannot adapt to scenarios such as power lines in complex environments and various types of communication equipment. The antennas on the shared towers generate high-strength electromagnetic fields in their vicinity, which may cause spatial radiation interference to the online monitoring equipment of the power lines, thereby affecting the monitoring of the power line status. It is urgent to determine the radiation immunity requirements for the online monitoring equipment of the power lines used on shared towers.

[0003] For the communication base station system, the antenna is installed on the tower. The height and inclination of the antenna are determined according to the business scope to be covered. The communication uses the electromagnetic waves in the far field of the antenna, and its intensity meets the minimum intensity of the terminal mobile phone and does not exceed the requirements of GB 8702-2014 "Electromagnetic Environment Control Limits". There is no limit on the field strength near the antenna installation, but this field strength is relatively high. When power and communication share the tower, the communication antenna is installed on the power pole tower, which is usually equipped with line online monitoring equipment. Q / GDW 242-2010 "General Technical Specifications for Transmission Line Status Monitoring Devices" stipulates that the radio frequency electromagnetic field radiation immunity test level of the line monitoring equipment is level 3, that is, the field strength is 10V / m. At present, the test only considers the radio frequency electromagnetic field of 80-1000MHz. There are many types of communication antennas with different frequencies and powers. The field strength nearby locally exceeds 10V / m, which exceeds the electromagnetic interference resistance of the existing line online monitoring equipment. At the same time, the tower scatters and reflects electromagnetic waves, and the electromagnetic field at the line online monitoring equipment is more complicated. Therefore, in order to ensure the normal operation of the line online monitoring equipment, it is necessary to clarify the interference field strength of the communication equipment to the line online monitoring equipment, determine the electric field strength at the line online monitoring equipment of the shared tower, and thus determine the RF electromagnetic field radiation immunity requirements of the line online monitoring equipment. Summary of the invention

[0004] The present invention provides a method and system for determining the electric field strength at a line online monitoring device, so as to solve the problem of how to determine the interference field strength at the line online monitoring device sharing an iron tower.

[0005] In order to solve the above problem, according to one aspect of the present invention, a method for determining the electric field strength at a line online monitoring device is provided, wherein the line online monitoring device is installed on a shared iron tower or a transmission line connected to the shared iron tower, and the shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower; the method includes:

[0006] According to the parameter information of the transmission tower and the communication equipment antenna, a three-dimensional model of the shared tower is established;

[0007] Based on the three-dimensional model of the shared iron tower, the transmission iron tower and the transmission wire are regarded as metal scatterers, the power supply is loaded according to the transmission power of the communication equipment antenna, and the mathematical model of electromagnetic interference of the shared iron tower is determined;

[0008] Determine the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model;

[0009] The induced current generated on the surface of the shared tower is calculated according to the physical optics (PO) method and the matrix (MOM) method, and the electric field integral equation is solved by using the induced current to determine the electric field strength at the line online monitoring device.

[0010] Preferably, the step of establishing a three-dimensional model of a shared tower according to parameter information of a transmission tower and a communication equipment antenna includes:

[0011] Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

[0012] Preferably, the method further comprises:

[0013] The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

[0014] Preferably, the shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

[0015] Preferably, the step of determining the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model comprises:

[0016]

[0017] Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the tower surface.

[0018] Preferably, the step of calculating the induced current generated on the surface of the shared tower and solving the electric field integral equation using the induced current to determine the electric field strength at the line online monitoring device comprises:

[0019] According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area;

[0020] The Galerkin (Rao-Witton-Glisson, RWG) basis function based on triangular surface elements is used to discretize the integral equations of the induced current in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM Expressions include:

[0021]

[0022]

[0023] Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and βn are the total number of subdivided bins and current coefficients in the PO region, respectively. n Unknown; n is the RWG basis function;

[0024] Introducing the unit vector t k +、t k -, two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ;

[0025] The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including:

[0026] L E J MoM +L E J PO =-Ei (4)

[0027] Among them, L E is the electric field operator;

[0028] According to the induced current J PO The expression of the induced current J MOM The expression and electric field relationship of α n , Induction current J PO The value of the induced current J MOM The value of

[0029] The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0030] According to another aspect of the present invention, a system for determining the electric field strength at a line online monitoring device is provided, wherein the line online monitoring device is installed on a shared iron tower or a transmission line connected to the shared iron tower, and the shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower; the system includes:

[0031] A shared tower three-dimensional model building unit is used to build a shared tower three-dimensional model according to parameter information of the transmission tower and the communication equipment antenna;

[0032] A mathematical model determination unit for electromagnetic interference of a shared iron tower is used to determine a mathematical model for electromagnetic interference of a shared iron tower based on the three-dimensional model of the shared iron tower, taking the transmission iron tower and the transmission wire as metal scatterers, loading the power supply according to the transmission power of the antenna of the communication device, and determining the mathematical model for electromagnetic interference of the shared iron tower;

[0033] An electric field integral equation determination unit, used to determine the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model;

[0034] The electric field strength determination unit is used to calculate the induced current generated on the surface of the shared iron tower, and use the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0035] Preferably, the shared tower three-dimensional model establishing unit establishes the shared tower three-dimensional model according to the parameter information of the transmission tower and the communication equipment antenna, including:

[0036] Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

[0037] Preferably, the shared tower three-dimensional model building unit further comprises:

[0038] The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

[0039] Preferably, the shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

[0040] Preferably, the electric field integral equation determining unit determines the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model, including:

[0041]

[0042] Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the surface of the tower.

[0043] Preferably, the electric field strength determination unit calculates the induced current generated on the surface of the shared tower, and uses the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device, including:

[0044] According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area;

[0045] The Galerkin RWG basis function based on triangular facets is used to discretize the integral equations of the induced currents in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM ,include:

[0046]

[0047]

[0048] Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and β n are the total number of subdivided bins and current coefficients in the PO region, β n Unknown; n is the RWG basis function;

[0049] Introducing the unit vector t k +、t k -, two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ;

[0050] The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including:

[0051] L E J MoM +L E J PO =-E i (4)

[0052] Among them, L E is the electric field operator;

[0053] According to the induced current J PO The expression of the induced current J MOM The expression and electric field relationship of αn , Induction current J PO The value of the induced current J MOM The value of

[0054] The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0055] The present invention provides a method and system for determining the electric field strength at a line online monitoring device, determining a mathematical model of electromagnetic interference of a shared iron tower based on a three-dimensional model of a shared iron tower, thereby determining the electric field integral equation at the line online monitoring device, and calculating the induced current generated on the surface of the shared iron tower according to the physical optics PO method and the matrix MOM method, solving the electric field integral equation using the induced current, and determining the electric field strength at the line online monitoring device. The present invention performs near-field equivalence in accordance with the principles and general performance requirements of the antenna of a communication device, combined with the antenna size, studies the scattering effect of the transmission line as a large metal frame and a slender structure of a transmission conductor on the electromagnetic field near the antenna of the communication device, and adopts a method combining the moment method and physical optics to determine the field strength at the line online monitoring device near the antenna of the communication device, providing data support for the radio frequency electromagnetic field radiation immunity requirements of the line online monitoring device of the shared iron tower, and can further ensure the electromagnetic compatibility of the line online monitoring device. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0057] Figure 1 A flowchart of a method 100 for determining the electric field strength at a line online monitoring device according to an embodiment of the present invention;

[0058] Figure 2 A schematic diagram of the antenna direction of a communication device according to an embodiment of the present invention;

[0059] Figure 3 is a schematic diagram of a half-wave dipole antenna according to an embodiment of the present invention;

[0060] Figure 4 A schematic diagram of interference between an antenna of a communication device on a shared tower and a line online detection device according to an embodiment of the present invention;

[0061] Figure 5 A schematic diagram of a mathematical model of electromagnetic interference of a shared iron tower according to an embodiment of the present invention;

[0062] Figure 6 A schematic diagram of solving the induced current based on the PO-MOM hybrid algorithm according to an embodiment of the present invention;

[0063] Figure 7 A schematic diagram of an iron tower model with different tower head types according to an embodiment of the present invention;

[0064] Figure 8 Schematic diagram of the effect of tower head type on electric field strength according to an embodiment of the present invention;

[0065] Fig. 9 A schematic diagram of a change in the tilt angle of an antenna of a communication device according to an embodiment of the present invention;

[0066] Fig.10 A schematic diagram showing the effect of the antenna tilt angle on the electric field strength according to an embodiment of the present invention;

[0067] Fig.11 A schematic diagram showing the effect of antenna power on electric field strength according to an embodiment of the present invention;

[0068] Fig.12 1 is a schematic diagram of the structure of a system 1200 for determining the electric field strength at a line online monitoring device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0069] Now, exemplary embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to disclose the present invention in detail and completely and to fully convey the scope of the present invention to those skilled in the art. The terms used in the exemplary embodiments shown in the accompanying drawings are not intended to limit the present invention. In the accompanying drawings, the same units / elements are marked with the same reference numerals.

[0070] Unless otherwise specified, the terms (including technical terms) used herein have the commonly understood meanings to those skilled in the art. In addition, it is understood that the terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0071] Figure 1 FIG. 1 is a flow chart of a method 100 for determining the electric field strength at a line online monitoring device according to an embodiment of the present invention. Figure 1As shown, the method for determining the electric field strength at the line online monitoring device provided by the embodiment of the present invention is based on the principle and general performance requirements of the communication equipment antenna, combined with the antenna size for near-field equivalence, and the scattering effect of the transmission line as a large metal frame and the slender structure of the transmission line on the electromagnetic field near the communication equipment antenna is studied. The method of combining the moment method and physical optics is used to determine the field strength at the line online monitoring device in the near field of the communication equipment antenna, which provides data support for the radio frequency electromagnetic field radiation immunity requirements of the line online monitoring device of the shared iron tower, and can further ensure the electromagnetic compatibility of the line online monitoring device. Among them, the line online monitoring device is installed on a shared iron tower or a transmission line connected to the shared iron tower, and the shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower. The method 100 for determining the electric field strength at the line online monitoring device provided by the embodiment of the present invention starts from step 101. In step 101, a three-dimensional model of the shared iron tower is established according to the parameter information of the transmission iron tower and the communication equipment antenna.

[0072] Preferably, the step of establishing a three-dimensional model of a shared tower according to parameter information of a transmission tower and a communication equipment antenna includes:

[0073] Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

[0074] Preferably, the method further comprises:

[0075] The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

[0076] In the embodiment of the present invention, the communication device antenna direction is as follows: Figure 2As shown, the length of the half-wave dipole antenna is determined to be 1 / 2 wavelength according to the operating frequency f of the communication equipment antenna, and the number of half-wave dipoles is determined according to the maximum gain of the antenna; wherein, if the antenna gain is below 15dB, the number of half-wave dipoles is 4 units; if the antenna gain is above 15, the number of half-wave dipoles is 8 units. The size of the antenna reflector is determined according to the outer dimensions of the antenna. For example, according to the operating frequency f=800MHz of the communication equipment antenna and the wavelength of 0.375m, it can be determined that the length of the half-wave dipole antenna is 1 / 2 wavelength, that is, 0.1875m. According to the direction of the antenna, the maximum gain is 15dB, so the number of half-wave dipoles is determined to be 4 units. The structure of the half-wave dipole antenna is shown in the figure. Figure 3 As shown, the size of the antenna reflector is determined according to the outer dimensions of the antenna. For example, if the antenna has a length of 1.3 m, a width of 0.28 m, and a depth of 0.08 m, then the reflector has a length of 1.3 m, a width of 0.28 m, and a depth of 0.08 m.

[0077] In an embodiment of the present invention, a three-dimensional model of a shared tower is established according to the installation height and antenna downtilt angle of the communication equipment antenna on the shared tower. Specifically, the center of the tower leg of the shared tower on the ground is taken as the origin o, the direction perpendicular to the ground is the Z direction, and the direction parallel to the wire is the X direction. A three-dimensional model of the tower is established according to the actual size of the tower, the antenna model position is placed according to the antenna installation position, and the downtilt angle is set according to the actual downtilt angle. The communication equipment antenna (communication antenna) refers to a low-power wireless antenna for communicating with the user's mobile phone. When it selects a transmission tower as the bearing body, it is usually hung on the tower body 20-50m above the ground. In order to meet the requirements of the communication signal transmission rate, the operating frequency band of the communication antenna on the shared tower is generally ultra-high frequency and above.

[0078] Transmission line online monitoring equipment generally consists of a data acquisition module and a wireless transmission module, which are usually hung on the line tower or on the conductor. The data acquisition module is responsible for monitoring various states of the line operation, while the wireless transmission module sends the monitored information to the system background monitoring system far away from the line through wireless transmission. Figure 4As shown in the figure, the shared iron tower is the common carrier of the communication antenna and the transmission line online monitoring equipment. Since the communication antenna and the line online monitoring equipment are arranged in close proximity, the time-varying electromagnetic waves continuously emitted by the communication antenna will inevitably cause radiation interference to the adjacent line online monitoring equipment. Especially in the context of the large-sized metal scatterer of the iron tower angle steel truss structure, the electromagnetic waves emitted by the communication antenna will form an induced current on the angle steel, causing the iron tower to passively generate a secondary radiation electromagnetic field, which will inevitably form a high-density, high-intensity complex time-varying electromagnetic field in the space adjacent to the line centered on the iron tower. For the line online monitoring equipment, its equipment casing and electronic components will generate high-frequency noise current under the action of the additional complex time-varying field radiation coupling and invade the internal circuit of the component through the feeder, thereby interfering with the normal operation of the equipment and the input and output of the signal, reducing the signal-to-noise ratio of the line online monitoring equipment, and even causing its working failure in severe cases. Therefore, it is necessary to study the electric field strength processed by the line online monitoring equipment.

[0079] In step 102, based on the three-dimensional model of the shared tower, the transmission tower and the transmission line are regarded as metal scatterers, the power supply is loaded according to the transmission power of the communication device antenna, and the mathematical model of electromagnetic interference of the shared tower is determined.

[0080] Preferably, the shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

[0081] In step 103, the electric field integral equation at the line online monitoring device is determined according to the shared tower electromagnetic interference mathematical model.

[0082] Preferably, the step of determining the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model comprises:

[0083]

[0084] Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the tower surface.

[0085] In the implementation of the present invention, the transmission line is regarded as a metal scatterer, and the power supply is loaded according to the transmission power of the communication device antenna to obtain the mathematical model of electromagnetic interference of the shared iron tower. Figure 5 As shown, there are two coordinate systems, one is the rectangular coordinate system (x, y, z) and the other is the spherical coordinate system Assume that the tower is an ideal conductor located at the origin o of the coordinate system, and the base station antenna is the source of the electromagnetic field located at r′, emitting electromagnetic waves E uniformly into the surrounding space. i (r′). i (r′) is incident on the transmission tower at an angle, and the induced current density distribution generated on the tower surface is J(rT′), which generates a secondary radiation field in space. The line online monitoring equipment is located at the field point r, and its scattered electric field is Es(r), which is the electric field intensity at the online monitoring device. In this mathematical model, E i (r′) is a known quantity, Es(r) is a quantity to be determined, and J(rT′) is an intermediate variable. It can be seen that the solution to the time-varying electromagnetic field of a shared tower is actually the solution to the electric field scattered by an electrically large scatterer with a known field source at any point in space.

[0086] according to Figure 5 The model shown can obtain the electric field integral equation at the line online monitoring device as follows:

[0087]

[0088] Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the tower surface.

[0089] It can be seen from formula (1) that the key to solving the scattered electric field Es(r) lies in the calculation of the induced current J(rT′) on the tower surface.

[0090] In step 104, the induced current generated on the surface of the shared tower is calculated, and the electric field integral equation is solved using the induced current to determine the electric field strength at the line online monitoring device.

[0091] Preferably, the step of calculating the induced current generated on the surface of the shared tower and solving the electric field integral equation using the induced current to determine the electric field strength at the line online monitoring device comprises:

[0092] According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area;

[0093] The Galerkin RWG basis function based on triangular facets is used to discretize the integral equations of the induced currents in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM Expressions include:

[0094]

[0095]

[0096] Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and β n are the total number of subdivided bins and current coefficients in the PO region, β n Unknown; n is the RWG basis function;

[0097] Introducing the unit vector t k + ,t k - , two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ;

[0098] The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including:

[0099] L E J MoM +L E J PO =-E i (4)

[0100] Among them, L E is the electric field operator;

[0101] According to the induced current JPO The expression of the induced current J MOM The expression and electric field relationship of α n , Induction current J PO The value of the induced current J MOM The value of

[0102] The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0103] In an embodiment of the present invention, the electric field strength at the installation location of the line online monitoring device is determined according to a hybrid algorithm of MOM and PO. Considering that the transmission tower is a large-sized scatterer, it is impossible to obtain an accurate solution result by simply using a traditional high-frequency approximation algorithm to solve its surface induced current. For this reason, a hybrid algorithm combining physical optics (PO) and method of moments (MoM) is used to calculate the surface induced current of the transmission tower.

[0104] The premise of using the PO and MoM hybrid algorithm to calculate the induced current on the tower surface is to clarify the respective application areas of the PO and MoM algorithms. Combining the algorithm characteristics of PO and MoM, the area division is as follows Figure 6 As shown in the figure, when the electromagnetic waves emitted by the antenna of the communication equipment irradiate the angle steel of the iron tower, an illuminated area and a shadow area will be formed on the surface of the angle steel. At this time, the illuminated area is calculated using the PO method, and the shadow area and the edge of the angle steel are calculated using the MoM method.

[0105] After completing the area division, the Galerkin (Rao-Witton-Glisson, RWG) basis function based on triangular facets is used to discretize the integral equations of the two calculation areas to solve the induced currents in each area. The induced currents in the discretized MoM area and PO area can be expressed as:

[0106]

[0107]

[0108] Among them, N MoM and α n The total number of subdivided elements and current coefficients of the MoM region, respectively, where α n Unknown; N PO and β n are the total number of subdivided bins and current coefficients in the PO region, respectively, where βn Unknown; n is the RWG basis function.

[0109] To solve the surface current J in the PO region PO , we must first obtain β n Therefore, the introduction of Figure 6 The unit vector t shown k + ,t k - , these two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and β n Solve for β n Then, according to formula (3), we can get J PO expression.

[0110] RWG basis function is also called generalized roof basis function. Usually, the weight function is selected in the same form as the basis function, that is, the Galerkin method is used. This basis and weight function can better simulate the distribution of induced current on the surface of the scatterer, will not cause artificial charge accumulation, and ensure the continuity of the current. Since the plane triangle patch can flexibly simulate any complex three-dimensional geometric model, such as sharp points, grooves and protrusions on the target surface, the plane triangle and RWG basis function are widely used in the electromagnetic scattering analysis of complex shape targets. The definition of RWG basis function is:

[0111]

[0112] in, are the two adjacent triangles corresponding to the nth basis function; l n is the length of the common side; The triangle area; (ie t k + ), (ie t k - ) are triangles The vertices point to the field points of the triangle and the triangle The field point on the triangle points to the vector of the vertex. From equation (6), we can get the basis function f n (r) divergence. It can be seen that The charge density is uniform, the total charge of adjacent triangles is zero, and there is no accumulation of line charges, which ensures the continuity of the current on both sides of the adjacent triangular units.

[0113] Then, according to the boundary conditions at the edge of the MoM zone and the PO zone, the relationship can be obtained:

[0114] L E J MoM +L E J PO =-E i (4)

[0115] Among them, L E is the electric field operator.

[0116] Finally, substituting formulas (2) and (3) into formula (4), we can obtain α n and the induced current in each area, the two are superimposed to obtain the total induced current J(r T ′), J(r T Substituting ′) into formula (1) can obtain the electric field strength Es(r) at the line online monitoring device.

[0117] The fundamental reason why the antenna of the communication equipment generates electromagnetic interference to the line online monitoring equipment is the radiation coupling effect of the electromagnetic wave on the line online monitoring equipment under the background of the angle steel conductor of the tower. Therefore, the possible factors affecting the electric field strength at the line online monitoring equipment, in addition to the dominant factor of the distance between the two, are nothing more than the parameters of the transmission tower and the base station antenna, which are specifically reflected in the tower head type, antenna power and antenna tilt angle. In the embodiment of the present invention, the influence of these three working conditions on the electric field strength at the line online monitoring equipment is also studied separately.

[0118] A simulation model is established by taking a 35kV shared iron tower as an example. The tower is 48m high and three base station antennas are distributed on the main material of the tower body 20m above the ground. According to the possible installation positions of the line online monitoring equipment, the most dangerous situation is selected, that is, it is installed on the tower body. At this time, compared with the line online monitoring equipment installed on the cross arm or conductor of the iron tower, the distance between the two is the closest. Set the vertical distance between the base station antenna and the line online monitoring equipment, starting with 5m, setting the step length to 3m, moving the position of the line online monitoring equipment, and linearly increasing the vertical distance between the two to 20m in turn. Considering that the working frequency band of the base station antenna is 800MHz.

[0119] (1) Calculation of different tower head types

[0120] In order to study the influence of tower head type on electromagnetic interference, the other two factors are kept unchanged, the tower body height is 40m and the tower head height is 8m. Figure 7 As shown, the electric field strength at the line online monitoring equipment is calculated by using the dry-shaped tower head, cat-head-shaped tower head and wine glass-shaped tower head respectively.

[0121] The simulation results are shown in the attached Figure 8As shown in the figure, it can be seen that as the spacing increases, the electric field strength at the line online monitoring equipment shows a downward trend, and the trend is relatively stable without any sudden changes. Figure 8 It can be seen that the influence of the three tower head types on the electric field strength at the line online monitoring equipment is relatively consistent, and the values ​​are basically the same. Therefore, it can be considered that the tower head type has little effect on the electric field strength at the line online monitoring equipment.

[0122] (2) Calculation results for different antenna tilt angles

[0123] In order to study the most serious interference situation, three antennas are selected to rotate at the same angle for simulation. Fig. 9 As shown, the antenna is generally fixed to the main material of the tower body through a bracket and a holding pole. The bracket is arranged horizontally and the holding pole is arranged vertically. The angle between the antenna and the holding pole in the vertical direction is the antenna tilt angle.

[0124] From the above research, it can be seen that the tower head type has little effect on the electric field strength at the line online monitoring equipment, so the dry-shaped tower is uniformly selected for modeling. Considering that the maximum antenna tilt angle in actual projects does not exceed 28°, the antenna tilt angles are taken as 0°, 15° and 28°, and the influence of the change of antenna tilt angle at different frequencies on the electric field strength at the line online monitoring equipment is calculated.

[0125] The simulation results are as follows Fig.10 As shown in the figure, it can be seen that as the antenna tilt angle increases, the electric field strength at the line online monitoring equipment also increases. When the spacing is 5m and the antenna tilt angle is 0°, the electric field strength at the line online monitoring equipment is 18V / m. When the antenna tilt angle increases to 28°, the electric field strength increases to 23V / m. The reason for this phenomenon is that as the antenna tilt angle increases, the main radiation direction of the antenna gradually changes from the horizontal direction to the vertical direction. At the same time, from Fig.10 It can be seen that since the line online monitoring equipment is located above the antenna, the radiation area of ​​the antenna to the line online monitoring equipment changes from the side lobe area to the main lobe area. According to the antenna working characteristics, the radiation energy of the antenna is mainly concentrated in the main lobe area. At this time, the RF radiation intensity of the antenna to it gradually increases. Therefore, whether the line online monitoring equipment is located in the main lobe area of ​​the antenna will have a greater impact on the electric field strength.

[0126] (3) Calculation results of different antenna powers

[0127] Considering that the base station antenna transmission power generally does not exceed 20W, the antenna power is taken as 5W, 10W and 20W, and the impact of the change of antenna power on the electric field strength at the line online monitoring equipment at different frequencies is calculated. The calculation results are shown in the attached figure. Fig.11 shown.

[0128] From the attached Fig.11It can be seen that the antenna power directly affects the electric field strength at the line online monitoring equipment, and the greater the power, the greater the field strength. When the spacing is 5m and the power is 5W, the electric field strength at the line online monitoring equipment is 18V / m, and when the antenna power increases to 20W, the electric field strength at the line online monitoring equipment increases to 22V / m. This is because the antenna's transmission power determines the field strength value of its electromagnetic radiation source, thereby affecting the scattered electric field value of the observation point, so the antenna power will have a greater impact on the electric field strength at the line online monitoring equipment.

[0129] Therefore, the embodiments of the present invention establish an antenna model according to the parameter information of the communication device antenna, and determine the electric field strength at the line online monitoring device accordingly, with high accuracy.

[0130] Fig.12 FIG. 1 is a schematic diagram of a system 1200 for determining the electric field strength at a line online monitoring device according to an embodiment of the present invention. Fig.12 As shown, the system 1200 for determining the electric field strength at the line online monitoring device provided by the embodiment of the present invention includes: a shared iron tower three-dimensional model establishing unit 1201, a shared iron tower electromagnetic interference mathematical model determining unit 1202, an electric field integral equation determining unit 1203 and an electric field strength determining unit 1204. The line online monitoring device is installed on the shared iron tower or the transmission line connected to the shared iron tower, and the shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower.

[0131] Preferably, the shared tower three-dimensional model establishing unit 1201 is used to establish a shared tower three-dimensional model according to parameter information of the transmission tower and the communication equipment antenna.

[0132] Preferably, the shared tower three-dimensional model establishing unit 1201 establishes a shared tower three-dimensional model according to parameter information of the transmission tower and the communication equipment antenna, including:

[0133] Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

[0134] Preferably, the shared tower three-dimensional model building unit 1201 further includes:

[0135] The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

[0136] Preferably, the shared tower electromagnetic interference mathematical model determination unit 1202 is used to take the transmission tower and the transmission line as metal scatterers based on the shared tower three-dimensional model, load the power supply according to the transmission power of the communication equipment antenna, and determine the shared tower electromagnetic interference mathematical model.

[0137] Preferably, the shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

[0138] Preferably, the electric field integral equation determining unit 1203 is used to determine the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model.

[0139] Preferably, the electric field integral equation determining unit 1203 determines the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model, including:

[0140]

[0141] Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the tower surface.

[0142] Preferably, the electric field strength determination unit 1204 is used to calculate the induced current generated on the surface of the shared tower, and use the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0143] Preferably, the electric field strength determination unit 1204 calculates the induced current generated on the surface of the shared tower, and uses the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device, including:

[0144] According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area;

[0145] The Galerkin RWG basis function based on triangular facets is used to discretize the integral equations of the induced currents in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM ,include:

[0146]

[0147]

[0148] Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and β n are the total number of subdivided bins and current coefficients in the PO region, β n Unknown; n is the RWG basis function;

[0149] Introducing the unit vector t k + ,t k - , two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ;

[0150] The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including:

[0151] L E J MoM +L E J PO =-E i (4)

[0152] Among them, L E is the electric field operator;

[0153] According to the induced current J PO The expression of the induced current J MOM The expression and electric field relationship of α n , Induction current J PO The value of the induced current J MOM The value of

[0154] The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

[0155] The system 1200 for determining the electric field strength at an online line monitoring device according to an embodiment of the present invention corresponds to the method 100 for determining the electric field strength at an online line monitoring device according to another embodiment of the present invention, and will not be described in detail herein.

[0156] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0157] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / said / the [means, components, etc.]" are to be openly interpreted as at least one instance of the means, components, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily have to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0158] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0159] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0160] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0161] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0162] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for determining the electric field strength at a line online monitoring device, characterized in that: The line online monitoring device is installed on a shared iron tower or a transmission line connected to the shared iron tower, and the shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower; the method includes: According to the parameter information of the transmission tower and the communication equipment antenna, a three-dimensional model of the shared tower is established; Based on the three-dimensional model of the shared iron tower, the transmission iron tower and the transmission wire are regarded as metal scatterers, the power supply is loaded according to the transmission power of the communication equipment antenna, and the mathematical model of electromagnetic interference of the shared iron tower is determined; Determine the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model; Calculating the induced current generated on the surface of the shared iron tower, and using the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device; The shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

2. The method according to claim 1, characterized in that The method of establishing a three-dimensional model of a shared tower according to parameter information of a transmission tower and a communication equipment antenna includes: Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

3. The method according to claim 2, characterized in that The method further comprises: The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

4. The method according to claim 1, characterized in that: The step of determining the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model comprises: Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the surface of the tower.

5. The method according to claim 1, characterized in that: The step of calculating the induced current generated on the surface of the shared iron tower and using the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device includes: According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area; The Galerkin RWG basis function based on triangular facets is used to discretize the integral equations of the induced currents in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM Expressions include: Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and β n are the total number of subdivision elements and current coefficient in the PO region, β n Unknown; n is the RWG basis function; Introducing the unit vector t k +、t k -, two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ; The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including: L E I MoM +L E I PO =-E i (4) Among them, L E is the electric field operator; According to the induced current J PO The expression of the induced current J MOM The expression and electric field relationship of α n , Induction current J PO The value of the induced current J MOM The value of The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

6. A system for determining the electric field strength at a line online monitoring device, characterized in that: The line online monitoring device is installed on a shared iron tower or a transmission line connected to a shared iron tower. The shared iron tower includes: a transmission iron tower and a communication device installed on the transmission iron tower; the system includes: A shared tower three-dimensional model building unit is used to build a shared tower three-dimensional model according to parameter information of the transmission tower and the communication equipment antenna; A mathematical model determination unit for electromagnetic interference of a shared iron tower is used to determine a mathematical model for electromagnetic interference of a shared iron tower based on the three-dimensional model of the shared iron tower, taking the transmission iron tower and the transmission wire as metal scatterers, loading the power supply according to the transmission power of the antenna of the communication device, and determining the mathematical model for electromagnetic interference of the shared iron tower; An electric field integral equation determination unit, used to determine the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model; An electric field strength determination unit, used to calculate the induced current generated on the surface of the shared iron tower, and solve the electric field integral equation using the induced current to determine the electric field strength at the line online monitoring device; The shared tower electromagnetic interference mathematical model includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system The tower is an ideal conductor and is located at the origin o of the coordinate system. The antenna of the communication equipment is located at r′ as the source of the electromagnetic field and emits electromagnetic waves E uniformly to the surrounding space. i (r′), E i (r′) is incident on the transmission tower at an angle θ, and the induced current density distribution generated on the tower surface is J(r T ′), J(r T ′) generates a secondary radiation field into space; the angle between the position r′ of the communication equipment and the x-axis is The line online monitoring device is located at the field point r, and the electric field strength at r is Es(r), that is, the electric field strength at the line online monitoring device; where E i (r′) is a known quantity, Es(r) is a quantity to be determined, J(r T ′) is an intermediate variable.

7. The system according to claim 6, characterized in that The shared tower three-dimensional model building unit builds a shared tower three-dimensional model according to parameter information of the transmission tower and the communication equipment antenna, including: Taking the center of the tower leg of the transmission tower on the ground as the origin o, the direction perpendicular to the ground as the Z direction, and the direction parallel to the conductor as the X direction, a transmission tower model is established according to the actual size information of the transmission tower, and an antenna model is set on the transmission tower model according to the actual installation height and downtilt angle of the communication equipment antenna to establish a three-dimensional model of the shared tower.

8. The system according to claim 7, characterized in that The shared tower three-dimensional model building unit also includes: The length of the half-wave dipole antenna in the antenna model is determined according to the operating frequency of the communication device antenna; the number of half-wave dipoles in the antenna model is determined according to the maximum gain of the communication device antenna; and the size of the antenna reflector in the antenna model is determined according to the size of the communication device antenna.

9. The system according to claim 6, characterized in that The electric field integral equation determining unit determines the electric field integral equation at the line online monitoring device according to the shared tower electromagnetic interference mathematical model, including: Where Es(r) is the electric field strength at the line online monitoring device; ω is the incident wave angular frequency; μ is the magnetic permeability; S is the surface integral domain of the tower; g(r,r T ′) is the Green function; ε is the dielectric constant; J(r T ′) is the induced current density generated on the surface of the tower.

10. The system according to claim 6, characterized in that The electric field strength determination unit calculates the induced current generated on the surface of the shared iron tower, and uses the induced current to solve the electric field integral equation to determine the electric field strength at the line online monitoring device, including: According to the position where the electromagnetic waves emitted by the communication equipment antenna irradiate the iron tower angle steel, the surface of the iron tower angle steel is divided into the lighting area and the shadow area, and the induced current in the lighting area and the shadow area is calculated using the PO method and the MOM method respectively; among them, the edge of the angle steel belongs to the shadow area; The Galerkin RWG basis function based on triangular facets is used to discretize the integral equations of the induced currents in the illuminated area and the shadow area to obtain the induced current J in the discretized PO area. PO and the induced current J in the MOM region MOM ,include: Among them, N MoM and α n The total number of subdivision elements and current coefficients in the MoM region, α n Unknown; N PO and β n are the total number of subdivision elements and current coefficient in the PO region, β n Unknown; n is the RWG basis function; Introducing the unit vector t k +、t k -, two vectors are perpendicular to the common side of the triangle, and the RWG basis function f is established n The relationship between the normal vector of the common edge and the β n ; The electric field relationship is determined according to the boundary conditions at the edge of the MoM region and the PO region, including: L E I MoM +L E I PO =-E i (4) Among them, L E is the electric field operator; According to the induced current J PO The expression of the induced current J MOM The expression and electric field relationship of α n , Induction current J PO The value of the induced current J MOM The value of The induced current J PO The value of the induced current J MOM The values ​​of are superimposed to determine the induced current J(r T ′), and according to the induced current J(r T ′) and the electric field integral equation to determine the electric field strength at the line online monitoring device.

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