CN111710025A - Method and system for determining electric field intensity of line on-line monitoring equipment - Google Patents

Method and system for determining electric field intensity of line on-line monitoring equipment Download PDF

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CN111710025A
CN111710025A CN202010346291.5A CN202010346291A CN111710025A CN 111710025 A CN111710025 A CN 111710025A CN 202010346291 A CN202010346291 A CN 202010346291A CN 111710025 A CN111710025 A CN 111710025A
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iron tower
electric field
antenna
line
induced current
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刘兴发
张建功
刘华钢
黄锐
路遥
干喆渊
贺伟
齐道坤
张业茂
谢辉春
李妮
周兵
梨园
王延召
赵军
胡静竹
刘震寰
万皓
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State Grid Corp of China SGCC
China Electric Power Research Institute Co Ltd CEPRI
State Grid Henan Electric Power Co Ltd
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China Electric Power Research Institute Co Ltd CEPRI
State Grid Henan Electric Power Co Ltd
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Abstract

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

Description

Method and system for determining electric field intensity of line on-line monitoring equipment
Technical Field
The invention relates to the technical field of electromagnetic compatibility of high-voltage power transmission and transformation engineering, in particular to a method and a system for determining electric field intensity at a line online monitoring device.
Background
The power and communication sharing iron tower is characterized in that communication equipment is additionally arranged on the power iron tower, and communication facilities such as cables, antennas, RRUs and the like are attached to a power iron tower body, so that power and communication infrastructure resource sharing is realized. The shared iron tower is a new social resource sharing mode, and firstly, the land resource occupied by a newly-built communication iron tower base station can be effectively reduced by utilizing an electric iron tower to carry a communication facility, the environment is protected, the landscape is beautified, and beautiful Chinese construction is assisted; secondly, the densely-distributed nationwide electric power iron towers are used for communication construction, so that fast coverage and wide coverage of communication networks such as 4G and 5G can be promoted; and thirdly, a sharing cooperation mode of power and communication enterprises is formed, so that high asset utilization rate of power grid enterprises is promoted, economic benefits are improved, and value-added and function amplification of national assets are realized. The shared iron tower has great popularization value and wide application prospect. At present, a small number of shared towers are tried, the feasibility of a shared iron tower technology is verified, the tried towers and communication equipment are single and cannot adapt to scenes such as power lines in complex environments, communication equipment in various systems and the like, an antenna on the shared iron tower generates a high-field-intensity electromagnetic field nearby the shared iron tower and may generate space radiation interference on-line monitoring equipment of the power lines, so that the monitoring of the state of the power lines is influenced, and the radiation immunity requirement of the on-line monitoring equipment of the power lines for the shared iron tower is to be determined urgently.
For a communication base station system, an antenna is erected on an iron tower, the hanging height and the inclination angle of the antenna are determined according to a service range to be covered, and the communication utilizes electromagnetic waves of an antenna far field, wherein the strength of the electromagnetic waves meets the lowest strength of a terminal mobile phone and does not exceed the requirements of GB 8702 plus 2014 electromagnetic environment control limit. There is no limitation on the field strength at or near the location of the antenna mounting, which is relatively high. After the power and communication sharing iron tower, the communication antenna is erected on the power tower, the tower is usually provided with a line online monitoring device, the Q/GDW 242-2010 universal technical specification for the transmission line state monitoring device specifies that the radio frequency electromagnetic field radiation immunity test grade of the line on the monitoring device is 3 grade, namely the field intensity is 10V/m, and only 80-1000MHz radio frequency electromagnetic field is considered in the current test. The communication antennas are various in types, different in frequency and different in power, the field intensity nearby locally exceeds 10V/m, the electromagnetic interference resistance of the existing on-line monitoring equipment is exceeded, and meanwhile, due to the scattering and refraction and reflection effects of the iron tower on electromagnetic waves, the electromagnetic field at the on-line monitoring equipment is more complex. Therefore, in order to ensure the normal operation of the line on-line monitoring device, it is necessary to specify the interference field intensity of the communication device to the line on-line monitoring device, and determine the electric field intensity at the line on-line monitoring device of the shared iron tower, so as to determine the radio frequency electromagnetic field radiation immunity requirement of the line on-line monitoring device.
Disclosure of Invention
The invention provides a method and a system for determining electric field intensity at a line online monitoring device, which are used for solving the problem of how to determine the interference field intensity at the line online monitoring device of a shared iron tower.
In order to solve the above-mentioned problems, according to an aspect of the present invention, there is provided a method of determining an electric field strength at an on-line monitoring device installed on a shared iron tower or a transmission line connected to the shared iron tower, the shared iron tower including: the system comprises a power transmission iron tower and communication equipment installed on the power transmission iron tower; the method comprises the following steps:
establishing a three-dimensional model of a shared iron tower according to parameter information of the power transmission iron tower and the communication equipment antenna;
based on the three-dimensional model of the shared iron tower, taking the power transmission iron tower and the power transmission conductor as metal scatterers, loading a power supply according to the transmitting power of the communication equipment antenna, and determining an electromagnetic interference mathematical model of the shared iron tower;
determining an electric field integral equation at the line on-line monitoring equipment according to the electromagnetic interference mathematical model of the shared iron tower;
and calculating induced current generated on the surface of the shared iron tower according to a Physical Optics (PO) method and a matrix (Methods of MoMents, MOM) method, solving an electric field integral equation by using the induced current, and determining the electric field intensity at the on-line monitoring equipment of the line.
Preferably, the establishing a three-dimensional model of a shared iron tower according to parameter information of the power transmission iron tower and the communication device antenna includes:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
Preferably, wherein the method further comprises:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
Preferably, the mathematical model of electromagnetic interference of shared iron tower includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure BDA0002470225430000031
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission iron tower at an angle theta, and induced current generated on the surface of the iron tower is denseDegree distribution is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure BDA0002470225430000032
The line on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
Preferably, the determining an electric field integral equation at the line on-line monitoring device according to the mathematical model of electromagnetic interference of the shared iron tower includes:
Figure BDA0002470225430000033
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
Preferably, the calculating induced current generated on the surface of the shared iron tower, and solving the electric field integral equation by using the induced current to determine the electric field strength at the line online monitoring equipment includes:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
respectively carrying out discrete approximation of integral equations on the induced currents of the illumination area and the shadow area by adopting a Rao-Witton-Glisson (RWG) basis function based on a triangular surface element to obtain the induced current J of the dispersed PO areaPOAnd induced current J of MOM regionMOMIncludes:
Figure BDA0002470225430000041
Figure BDA0002470225430000042
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd β n are the total number of subdivision bins and the current coefficient of the PO region, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk+、tkTwo vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
According to another aspect of the present invention, there is provided a system for determining an electric field strength at an on-line monitoring device mounted on a shared iron tower or a transmission line connected to the shared iron tower, the shared iron tower comprising: the system comprises a power transmission iron tower and communication equipment installed on the power transmission iron tower; the system comprises:
the shared iron tower three-dimensional model establishing unit is used for establishing a shared iron tower three-dimensional model according to the power transmission iron tower and the parameter information of the communication equipment antenna;
the shared iron tower electromagnetic interference mathematical model determining unit is used for loading a power supply according to the transmitting power of the communication equipment antenna by taking the power transmission iron tower and the power transmission conducting wire as metal scatterers based on the shared iron tower three-dimensional model and determining the shared iron tower electromagnetic interference mathematical model;
the electric field integral equation determining unit is used for determining an electric field integral equation at the line on-line monitoring equipment according to the shared iron tower electromagnetic interference mathematical model;
and the electric field intensity determining unit is used for calculating induced current generated on the surface of the shared iron tower, solving the electric field integral equation by using the induced current and determining the electric field intensity of the line on-line monitoring equipment.
Preferably, the establishing unit of the three-dimensional model of the shared iron tower establishes the three-dimensional model of the shared iron tower according to parameter information of the power transmission iron tower and the communication device antenna, and includes:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
Preferably, the shared iron tower three-dimensional model building unit further includes:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
Preferably, the mathematical model of electromagnetic interference of shared iron tower includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure BDA0002470225430000051
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission tower at an angle theta, and the induced current density distribution generated on the surface of the tower is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure BDA0002470225430000052
The line on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
Preferably, the electric field integral equation determining unit determines the electric field integral equation at the line online monitoring device according to the shared iron tower electromagnetic interference mathematical model, and includes:
Figure BDA0002470225430000061
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
Preferably, the determining unit of the electric field strength calculates an induced current generated on the surface of the shared iron tower, and determines the electric field strength at the line online monitoring device by solving the electric field integral equation using the induced current, and includes:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
galois gold RWG base based on triangular surface elementThe function respectively carries out discrete approximation of integral equation on the induced current of the illumination area and the shadow area to obtain the induced current J of the PO area after the dispersionPOAnd induced current J of MOM regionMOMThe method comprises the following steps:
Figure BDA0002470225430000062
Figure BDA0002470225430000063
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient, respectively, of PO area, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk+、tkTwo vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
The invention provides a method and a system for determining electric field intensity at a line on-line monitoring device, which are characterized in that a mathematical model of electromagnetic interference of a shared iron tower is determined based on a three-dimensional model of the shared iron tower, so that an electric field integral equation at the line on-line monitoring device is determined, induced current generated on the surface of the shared iron tower is calculated according to a physical optics PO method and a matrix MOM method, the electric field integral equation is solved by utilizing the induced current, and the electric field intensity at the line on-line monitoring device is determined. According to the principle and the general performance requirements of the communication equipment antenna, near field equivalence is carried out by combining the size of the antenna, the scattering influence of a power transmission line serving as a large metal framework and a power transmission lead slender structure on an electromagnetic field near the communication equipment antenna is researched, a moment method and a physical optics combined method are adopted, the field intensity of the near-field line online monitoring equipment of the communication equipment antenna is determined, data support is provided for the radiation immunity requirement of a radio frequency electromagnetic field of the line online monitoring equipment of a shared iron tower, and the electromagnetic compatibility of the line online monitoring equipment can be further guaranteed.
Drawings
A more complete understanding of exemplary embodiments of the present invention may be had by reference to the following drawings in which:
FIG. 1 is a flow chart of a method 100 of determining electric field strength at a line-on-line monitoring device according to an embodiment of the present invention;
FIG. 2 is a schematic view of an antenna orientation of a communication device according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a half-wave dipole antenna according to an embodiment of the present invention;
fig. 4 is a schematic diagram illustrating interference between an antenna of a communication device and a line on-line detection device on a shared iron tower according to an embodiment of the present invention;
fig. 5 is a schematic diagram of a mathematical model of electromagnetic interference of a shared iron tower according to an embodiment of the invention;
FIG. 6 is a schematic diagram of inductive current solving based on a PO-MOM hybrid algorithm according to an embodiment of the present invention;
fig. 7 is a schematic view of a model of a tower with different tower head types according to an embodiment of the invention;
FIG. 8 is a schematic diagram of the effect of a tower head version on electric field strength according to an embodiment of the present invention;
fig. 9 is a schematic diagram illustrating a change in the tilt angle of an antenna of a communication device according to an embodiment of the present invention;
FIG. 10 is a schematic diagram illustrating the effect of antenna tilt angle on electric field strength according to an embodiment of the present invention;
FIG. 11 is a diagram illustrating the effect of antenna power on electric field strength according to an embodiment of the present invention;
fig. 12 is a schematic diagram of a system 1200 for determining electric field strength at a line-on-line monitoring device according to an embodiment of the present invention.
Detailed Description
The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.
Unless otherwise defined, terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.
Fig. 1 is a flow chart of a method 100 of determining electric field strength at a line-on-line monitoring device according to an embodiment of the present invention. As shown in fig. 1, the method for determining the electric field strength at the line on-line monitoring device according to the embodiment of the present invention performs near-field equivalence by combining the antenna size according to the principle and general performance requirements of the communication device antenna, studies the scattering influence of the electric transmission line as a large metal framework and a transmission line elongated structure on the electromagnetic field near the communication device antenna, and determines the field strength at the line on-line monitoring device near the communication device antenna by using a method combining a moment method and physical optics, thereby providing data support for the radiation immunity requirement of the radio frequency electromagnetic field of the line on-line monitoring device sharing the iron tower, and further ensuring the electromagnetic compatibility of the line on-line monitoring device. Wherein, line on-line monitoring equipment installs on sharing iron tower or the power transmission line that is connected with sharing iron tower, and sharing iron tower includes: the power transmission tower comprises a power transmission tower and communication equipment installed on the power transmission tower. The method 100 for determining the electric field strength of the line on-line monitoring equipment provided by the embodiment of the invention starts from step 101, and establishes a shared iron tower three-dimensional model according to the parameter information of the power transmission iron tower and the communication equipment antenna in step 101.
Preferably, the establishing a three-dimensional model of a shared iron tower according to parameter information of the power transmission iron tower and the communication device antenna includes:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
Preferably, wherein the method further comprises:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
In the embodiment of the invention, the direction of the communication device antenna is as shown in fig. 2, the length of the half-wave oscillator antenna is determined to be 1/2 wavelengths according to the working frequency f of the communication device antenna, and the number of half-wave oscillators is determined according to the maximum gain of the antenna; if the antenna gain is below 15dB, the number of the half-wave oscillators is 4 units; if the antenna gain is more than 15, the number of the half-wave oscillators is 8 units. The size of the antenna reflector plate is determined according to the external dimension of the antenna. For example, according to the operating frequency f of the communication device antenna being 800MHz and the wavelength being 0.375m, the half-wave oscillator antenna length is determined to be 1/2 wavelengths, that is, 0.1875m, and the number of half-wave oscillators is determined to be 4 units when the maximum gain is 15dB according to the antenna direction. The structure of the half-wave element antenna is shown in fig. 3, and the size of the antenna reflector plate is determined according to the external dimension of the antenna. For example, if the antenna length is 1.3m, the width is 0.28m, and the thickness is 0.08m, the reflector length is 1.3m, the width is 0.28m, and the thickness is 0.08 m.
In the implementation mode of the invention, a three-dimensional model of the shared iron tower is established according to the installation height and the downward inclination angle of the antenna of the communication equipment on the shared iron tower. Specifically, a three-dimensional model of the iron tower is established according to the actual size of the iron tower by taking the center of a tower leg of the shared iron tower on the ground as an origin o, the direction perpendicular to the ground as a Z direction and the direction parallel to a lead as an X direction, the antenna model is placed according to the antenna installation position, and the downward inclination angle is set according to the actual downward inclination angle. A communication device antenna (communication antenna) refers to a low-power wireless antenna for communicating with a user's mobile phone, and is usually hung at a tower body 20-50m away from the ground when a power transmission tower is selected as a carrying body. In order to meet the requirement of the transmission rate of communication signals, the working frequency band of the communication antenna on the shared iron tower is generally ultrahigh frequency or above.
The on-line monitoring equipment for the power transmission line generally comprises a data acquisition module and a wireless transmission module, and is usually hung at the tower body of a line iron tower or on a wire. The wireless transmission module is used for transmitting the monitored information to a system background monitoring system far away from the line in a wireless transmission mode. As shown in fig. 4, the shared iron tower is a common carrier for the communication antenna and the transmission line online monitoring device. Due to the close arrangement between the communication antenna and the line online monitoring equipment, the time-varying electromagnetic waves continuously emitted by the communication antenna inevitably generate radiation interference on the adjacent line online monitoring equipment. Particularly, in the context of large-sized metal scatterers of an angle iron truss structure of an iron tower, electromagnetic waves emitted by a communication antenna can form induced currents on the angle iron, so that the iron tower passively generates a secondary radiation electromagnetic field, and a high-density and high-strength complex time-varying electromagnetic field is inevitably formed in a space adjacent to a line with the iron tower as a center. For the on-line monitoring device, under the additional complex time-varying field radiation coupling action, the device housing and the electronic component thereof generate high-frequency noise current and invade the internal circuit of the component through the feeder line, thereby interfering the normal operation of the device and the input and output of signals, reducing the signal-to-noise ratio of the on-line monitoring device, and even causing the working failure thereof in severe cases, therefore, the research of the electric field intensity processed by the on-line monitoring device is needed.
In step 102, based on the three-dimensional model of the shared iron tower, the power transmission iron tower and the power transmission conductor are used as metal scatterers, a power supply is loaded according to the transmitting power of the communication equipment antenna, and a mathematical model of electromagnetic interference of the shared iron tower is determined.
Preferably, the mathematical model of electromagnetic interference of shared iron tower includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure BDA0002470225430000101
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission tower at an angle theta, and the induced current density distribution generated on the surface of the tower is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure BDA0002470225430000102
The line on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
In step 103, an electric field integral equation at the line on-line monitoring equipment is determined according to the electromagnetic interference mathematical model of the shared iron tower.
Preferably, the determining an electric field integral equation at the line on-line monitoring device according to the mathematical model of electromagnetic interference of the shared iron tower includes:
Figure BDA0002470225430000111
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
In the implementation mode of the invention, the power transmission line is taken as a metal scatterer, and a power supply is loaded according to the transmitting power of the antenna of the communication equipment, so that the electromagnetic interference mathematical model of the shared iron tower is obtained. The mathematical model of the electromagnetic interference of the shared iron tower according to the embodiment of the present invention is shown in fig. 5, and includes 2 coordinate systems, one is a rectangular coordinate system (x, y, z), and the other is a spherical coordinate system
Figure BDA0002470225430000112
An iron tower is an ideal conductor and is positioned at the origin o of a coordinate system, a base station antenna is an electromagnetic field source point and is positioned at the r', and electromagnetic waves E are uniformly emitted to the surrounding spacei(r′)。Ei(r ') is incident on the power transmission iron tower at an angle, the induced current density generated on the surface of the iron tower is distributed to J (rT '), and the J (rT ') generates a secondary radiation field to the space. The line on-line monitoring equipment is positioned at a field point r, and the scattering electric field of the line on-line monitoring equipment is Es (r), namely the electric field intensity of the on-line monitoring device. In this mathematical model, Ei(r ') is a known quantity, Es (r) is a quantity to be sought, and J (rT') is an intermediate variable. Therefore, it can be seen that the solution of the time-varying electromagnetic field of the shared iron tower is actually the solution of the scattering electric field of the electrically large scatterer of a known field source at any point in space.
The electric field integral equation at the line on-line monitoring equipment can be obtained according to the model shown in fig. 5 as follows:
Figure BDA0002470225430000113
wherein Es (r) is line on-line monitoringThe electric field strength at the device; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
As can be seen from the formula (1), the key to solve the scattering electric field es (r) is to calculate the iron tower surface induced current J (rT').
In step 104, calculating an induced current generated on the surface of the shared iron tower, solving an electric field integral equation by using the induced current, and determining the electric field intensity at the line online monitoring equipment.
Preferably, the calculating induced current generated on the surface of the shared iron tower, and solving the electric field integral equation by using the induced current to determine the electric field strength at the line online monitoring equipment includes:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
respectively carrying out discrete approximation of integral equations on the induced currents of the illumination area and the shadow area by adopting a Galois gold RWG basis function based on a triangular surface element to obtain the induced current J of the dispersed PO areaPOAnd induced current J of MOM regionMOMIncludes:
Figure BDA0002470225430000121
Figure BDA0002470225430000122
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient, respectively, of PO area, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk +、tk -Two vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
In an embodiment of the invention, the electric field strength at the installation of the on-line monitoring equipment is determined according to an algorithm of MOM and PO mixing. Considering that a power transmission iron tower is taken as an electrically large scatterer, the surface induced current of the power transmission iron tower is solved by only adopting a traditional high-frequency approximation algorithm, and an accurate solving result cannot be obtained. For this purpose, a hybrid algorithm combining a Physical Optics method (PO) and a moment method (MoM) is adopted to calculate the induced current on the surface of the power transmission tower.
The premise of calculating the induced current on the surface of the iron tower by using the PO and MoM hybrid algorithm is to define the respective use areas of the PO and MoM algorithms. Combining the algorithm characteristics of PO and MoM, the area division is as shown in fig. 6, and when the electromagnetic wave emitted by the antenna of the communication device is irradiated onto the angle iron of the iron tower, an illumination area and a shadow area are formed on the surface of the angle iron. At the moment, the illumination area is calculated by adopting a PO method, and the shadow area and the edge of the angle steel are calculated by adopting a MoM method.
After the region division is completed, discrete approximation of an integral equation is carried out on the 2 calculation regions by adopting a Rao-Witton-Glisson (RWG) basis function based on a triangular surface element so as to solve the induced current of each region. The induced current of the discretized MoM and PO regions can be expressed as:
Figure BDA0002470225430000131
Figure BDA0002470225430000132
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficient of respective MoM zones, wherein αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient of PO area, wherein βnUnknown; f. ofnIs the RWG basis function.
To solve for surface current J in PO regionPOβ must first be obtainedn. Thus, the unit vector t shown in FIG. 6 is introducedk +、tk -The two vectors are perpendicular to the common edge of the triangle, establishing the RWG basis function fnβ is obtained by using a relation with the normal vector of the common edgenSolved to βnThen, J can be obtained according to the formula (3)POIs described in (1).
The RWG basis functions are also called generalized roof basis functions, and usually the weight functions are chosen to be in the same form as the basis functions, i.e. a galileo method is used. The basis and weight functions can better simulate the induced current distribution on the surface of the scattering body, can not cause artificial charge accumulation, and ensure the continuity of the current. Because the planar triangular patch can flexibly simulate any complex three-dimensional geometric model, such as sharp points, concave grooves and bulges on the surface of a target, the planar triangular patch and the RWG basis function are widely applied to electromagnetic scattering analysis of the target with the complex shape. The RWG basis function is defined as:
Figure BDA0002470225430000141
wherein,
Figure BDA0002470225430000142
two adjacent triangles corresponding to the nth basis function; lnIs the common edge length;
Figure BDA0002470225430000143
are respectively triangular
Figure BDA0002470225430000144
The area of (d);
Figure BDA0002470225430000145
(i.e. t)k +)、
Figure BDA0002470225430000146
(i.e. t)k -) Are respectively triangular
Figure BDA0002470225430000147
Points to the field point of the triangle and the triangle
Figure BDA0002470225430000148
The upper field points point to the vector of the triangle vertices. The basis function f is obtained from the formula (6)nDivergence of (r). It can be seen that
Figure BDA0002470225430000149
Figure BDA00024702254300001410
The upper charges are uniform in density, the total charges of the adjacent triangles are zero, and no line charges are accumulated, so that the continuity of the current between the upper charges and the two sides of the adjacent triangle units is ensured.
Then, the relationship can be obtained according to the boundary condition at the edge of the MoM region and the PO region:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEIs an electric field operator.
Finally, substituting equations (2) and (3) into equation (4) canTo obtain αnAnd the induced current of each area is superposed to obtain the total induced current J (r) on the surface of the iron towerT') and J (r)T' is substituted into the formula (1) to obtain the electric field intensity Es (r) of the on-line monitoring equipment of the line.
The fundamental reason that the antenna of the communication equipment generates electromagnetic interference on the line on-line monitoring equipment is the radiation coupling effect of electromagnetic waves on the line on-line monitoring equipment under the background of the angle iron conductor of the iron tower. Therefore, possible factors influencing the electric field intensity at the on-line monitoring equipment of the line have no self parameters of the transmission tower and the base station antenna except for the dominant factor of the distance between the two factors, and are specifically embodied as the tower head type of the tower, the antenna power, the antenna inclination angle and the like. In the embodiment of the invention, the influence rule of the 3 working conditions on the electric field intensity at the line online monitoring equipment is also respectively researched.
A simulation model is established by taking a certain 35kV sharing iron tower as an example, the tower height is 48m, and 3 base station antennas are distributed at a tower body main material position which is 20m away from the ground. According to the possible installation position of the line on-line monitoring equipment, the most dangerous condition is selected, namely the most dangerous condition is installed at the position of a tower body of an iron tower, and the most dangerous condition is closest to the line on-line monitoring equipment installed on a cross arm or a wire of the iron tower. And setting the vertical distance between the base station antenna and the line on-line monitoring equipment, starting with 5m, setting the step length to be 3m, moving the position of the line on-line monitoring equipment, and sequentially linearly increasing the vertical distance between the base station antenna and the line on-line monitoring equipment to 20 m. Consider a base station antenna operating at 800 MHz.
(1) Calculation of different tower head types
In order to study the influence rule of the tower head type on electromagnetic interference, control other 2 factors to be unchanged, unify the tower body height of 40m and the tower head height of 8m, as shown in figure 7, respectively adopt a dry-shaped tower head, a cat-head type tower head and a wine glass type tower head, and calculate the electric field intensity at the line on-line monitoring equipment.
The simulation result is shown in fig. 8, and it can be seen that the electric field intensity at the line on-line monitoring device shows a decreasing trend with the increase of the distance, and the trend is relatively stable without sudden change. As can be seen from fig. 8, the 3 types of tower head forms have relatively consistent rule of influence on the electric field intensity at the line on-line monitoring device, and the values are basically overlapped, so that it can be considered that the tower head forms have little influence on the electric field intensity at the line on-line monitoring device.
(2) Calculation results of different antenna tilt angles
In order to research the most serious interference situation, a method of rotating 3 antennas at the same angle is selected for simulation. As shown in fig. 9, the antenna is generally fixed on a main material of an iron tower body through a bracket and a pole, the bracket is horizontally arranged, the pole is vertically arranged, and an included angle between the antenna and the pole in the vertical direction is an antenna inclination angle.
According to the research, the influence of the tower head type on the electric field intensity of the on-line monitoring equipment is small, so that the tower in the shape of a Chinese character 'gan' is uniformly selected for modeling. Considering that the maximum inclination angle of the antenna in the current practical engineering does not exceed 28 degrees, the inclination angles of the antenna are 0 degree, 15 degrees and 28 degrees, and the influence of the change of the inclination angle of the antenna under different frequencies on the electric field intensity of the on-line monitoring equipment is calculated.
The simulation result is shown in fig. 10, and it can be seen that as the inclination angle of the antenna increases, the electric field intensity at the on-line monitoring device of the line also increases. When the distance is 5m and the inclination angle of the antenna is 0 degrees, the electric field intensity at the on-line monitoring equipment of the line is 18V/m, and when the inclination angle of the antenna is increased to 28 degrees, the electric field intensity is increased to 23V/m. This phenomenon is caused because the main radiation direction of the antenna gradually changes from the horizontal direction to the vertical direction as the tilt angle of the antenna increases. Meanwhile, as can be seen from fig. 10, since the line on-line monitoring device is located above the antenna, the radiation area of the line on-line monitoring device by the antenna is changed from the side lobe area to the main lobe area. According to the working characteristics of the antenna, the radiation energy of the antenna is mainly concentrated in the main lobe area, and at the moment, the radio frequency radiation intensity of the antenna to the antenna is gradually enhanced, so that whether the line online monitoring equipment is positioned in the main lobe area of the antenna can have great influence on the electric field intensity.
(3) Calculation results of different antenna powers
Considering that the transmitting power of the base station antenna does not exceed 20W, the antenna powers of 5W, 10W and 20W are taken to calculate the influence of the change of the antenna power on the electric field intensity at the line on-line monitoring equipment under different frequencies, and the calculation result is shown in fig. 11.
It can be seen from fig. 11 that the antenna power directly affects the electric field strength at the on-line monitoring equipment of the line, and the higher the power, the higher the field strength. When the spacing is 5m and the power is 5W, the electric field strength at the in-line monitoring device is 18V/m, and when the antenna power is increased to 20W, the electric field strength at the in-line monitoring device is increased to 22V/m. This is because the transmission power of the antenna determines the field intensity value of its electromagnetic radiation source, thereby affecting the scattered electric field value of the observation field point, so the power of the antenna will have a great influence on the electric field intensity at the line on-line monitoring equipment.
Therefore, the embodiment of the invention establishes the antenna model according to the parameter information of the communication equipment antenna, and determines the electric field intensity at the line online monitoring equipment according to the electric field model, thereby having higher accuracy.
Fig. 12 is a schematic diagram of a system 1200 for determining electric field strength at a line-on-line monitoring device according to an embodiment of the present invention. As shown in fig. 12, a system 1200 for determining an electric field strength of a line at a line monitoring device according to an embodiment of the present invention includes: the device comprises 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. Wherein, line on-line monitoring equipment installs on sharing iron tower or the power transmission line that is connected with sharing iron tower, and sharing iron tower includes: the power transmission tower comprises a power transmission tower and communication equipment installed on the power transmission tower.
Preferably, the shared iron tower three-dimensional model establishing unit 1201 is configured to establish a shared iron tower three-dimensional model according to parameter information of the power transmission iron tower and the communication device antenna.
Preferably, the shared iron tower three-dimensional model establishing unit 1201 establishes a shared iron tower three-dimensional model according to parameter information of an electric power iron tower and a communication device antenna, and includes:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
Preferably, the shared iron tower three-dimensional model establishing unit 1201 further includes:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
Preferably, the shared iron tower electromagnetic interference mathematical model determining unit 1202 is configured to load a power supply according to a transmission power of a communication device antenna, and determine the shared iron tower electromagnetic interference mathematical model, with the power transmission iron tower and the power transmission conductor as metal scatterers based on the shared iron tower three-dimensional model.
Preferably, the mathematical model of electromagnetic interference of shared iron tower includes: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure BDA0002470225430000171
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission tower at an angle theta, and the induced current density distribution generated on the surface of the tower is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure BDA0002470225430000173
The line on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
Preferably, the electric field integral equation determining unit 1203 is configured to determine an electric field integral equation at the line online monitoring device according to the shared iron tower electromagnetic interference mathematical model.
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 iron tower electromagnetic interference mathematical model, including:
Figure BDA0002470225430000172
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
Preferably, the electric field strength determining unit 1204 is configured to calculate an induced current generated on the surface of the shared iron tower, solve the electric field integral equation by using the induced current, and determine the electric field strength at the line online monitoring device.
Preferably, the determining unit 1204 for electric field strength calculates an induced current generated on the surface of the shared iron tower, and solves the electric field integral equation by using the induced current to determine the electric field strength at the line online monitoring device, including:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
respectively carrying out discrete approximation of integral equations on the induced currents of the illumination area and the shadow area by adopting a Galois gold RWG basis function based on a triangular surface element to obtain the induced current J of the dispersed PO areaPOAnd induced current J of MOM regionMOMThe method comprises the following steps:
Figure BDA0002470225430000181
Figure BDA0002470225430000182
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient, respectively, of PO area, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk +、tk -Two vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
The system 1200 for determining the electric field strength at the line on line monitoring device according to the embodiment of the present invention corresponds to the method 100 for determining the electric field strength at the line on line monitoring device according to another embodiment of the present invention, and is not described herein again.
The invention has been described with reference to a few embodiments. However, other embodiments of the invention than the one disclosed above are equally possible within the scope of the invention, as would be apparent to a person skilled in the art from the appended patent claims.
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/an/the [ device, component, etc ]" are to be interpreted openly as referring to at least one instance of said device, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not have to be performed in the exact order disclosed, unless explicitly stated.
As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, system, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The present application is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the application. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.

Claims (12)

1. A method of determining an electric field strength at an on-line monitoring device mounted on a shared iron tower or a power transmission line connected to the shared iron tower, the shared iron tower comprising: the system comprises a power transmission iron tower and communication equipment installed on the power transmission iron tower; the method comprises the following steps:
establishing a three-dimensional model of a shared iron tower according to parameter information of the power transmission iron tower and the communication equipment antenna;
based on the three-dimensional model of the shared iron tower, taking the power transmission iron tower and the power transmission conductor as metal scatterers, loading a power supply according to the transmitting power of the communication equipment antenna, and determining an electromagnetic interference mathematical model of the shared iron tower;
determining an electric field integral equation at the line on-line monitoring equipment according to the electromagnetic interference mathematical model of the shared iron tower;
and calculating induced current generated on the surface of the shared iron tower, solving the electric field integral equation by using the induced current, and determining the electric field intensity of the line on-line monitoring equipment.
2. The method according to claim 1, wherein the establishing a three-dimensional model of a shared iron tower according to parameter information of the power transmission iron tower and the communication equipment antenna comprises:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
3. The method of claim 2, further comprising:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
4. The method of claim 1, wherein the shared tower electromagnetic interference mathematical model comprises: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure FDA0002470225420000011
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission tower at an angle theta, and the induced current density distribution generated on the surface of the tower is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure FDA0002470225420000021
LineThe on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
5. The method of claim 1, wherein determining an electric field integral equation at the line on-line monitoring device from the mathematical model of shared tower electromagnetic interference comprises:
Figure FDA0002470225420000022
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
6. The method of claim 1, wherein the calculating induced current generated on the surface of the shared iron tower and solving the electric field integral equation by using the induced current to determine the electric field intensity at the on-line monitoring equipment comprises:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
respectively carrying out discrete approximation of integral equations on the induced currents of the illumination area and the shadow area by adopting a Galois gold RWG basis function based on a triangular surface element to obtain the induced current J of the dispersed PO areaPOAnd induced current J of MOM regionMOMIncludes:
Figure FDA0002470225420000023
Figure FDA0002470225420000024
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient, respectively, of PO area, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk+、tkTwo vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
7. A system for determining an electric field strength at a line on-line monitoring device mounted on a shared iron tower or a power transmission line connected to the shared iron tower, the shared iron tower comprising: the system comprises a power transmission iron tower and communication equipment installed on the power transmission iron tower; the system comprises:
the shared iron tower three-dimensional model establishing unit is used for establishing a shared iron tower three-dimensional model according to the power transmission iron tower and the parameter information of the communication equipment antenna;
the shared iron tower electromagnetic interference mathematical model determining unit is used for loading a power supply according to the transmitting power of the communication equipment antenna by taking the power transmission iron tower and the power transmission conducting wire as metal scatterers based on the shared iron tower three-dimensional model and determining the shared iron tower electromagnetic interference mathematical model;
the electric field integral equation determining unit is used for determining an electric field integral equation at the line on-line monitoring equipment according to the shared iron tower electromagnetic interference mathematical model;
and the electric field intensity determining unit is used for calculating induced current generated on the surface of the shared iron tower, solving the electric field integral equation by using the induced current and determining the electric field intensity of the line on-line monitoring equipment.
8. The system according to claim 7, wherein the shared iron tower three-dimensional model building unit builds a shared iron tower three-dimensional model according to parameter information of the power transmission iron tower and the communication equipment antenna, and includes:
the method comprises the steps of taking the center of a tower leg of a power transmission iron tower on the ground as an original point o, taking the direction vertical to the ground as a Z direction, taking the direction parallel to a lead as an X direction, establishing a power transmission iron tower model according to actual size information of the power transmission iron tower, and setting an antenna model on the power transmission iron tower model according to the actual installation height and the downward inclination angle of a communication equipment antenna so as to establish a shared iron tower three-dimensional model.
9. The system according to claim 8, wherein the shared iron tower three-dimensional model building unit further comprises:
determining the length of a half-wave dipole antenna in the antenna model according to the working frequency of the communication equipment antenna; determining the number of half-wave oscillators in the antenna model according to the maximum gain of the communication equipment antenna; and determining the size of an antenna reflector plate in the antenna model according to the size of the communication equipment antenna.
10. The system of claim 7, wherein the shared tower electromagnetA mathematical model of interference comprising: a rectangular coordinate system (x, y, z) and a spherical coordinate system
Figure FDA0002470225420000041
The iron tower is used as an ideal conductor and is positioned at the origin o of the coordinate system; the communication device antenna is located at r' as an electromagnetic field source point and uniformly emits an electromagnetic wave E to the surrounding spacei(r′)，Ei(r') incident on the power transmission tower at an angle theta, and the induced current density distribution generated on the surface of the tower is J (r)T′)，J(rT') generating a secondary radiation field into space; the position r' of the communication device is at an angle to the x-axis
Figure FDA0002470225420000042
The line on-line monitoring equipment is positioned at a field point r, and the electric field intensity at the field point r is Es (r), namely the electric field intensity at the line on-line monitoring device; wherein E isi(r') is a known quantity, Es (r) is a quantity to be sought, J (r)T') is an intermediate variable.
11. The system of claim 7, wherein the electric field integral equation determining unit determines the electric field integral equation at the line on-line monitoring device according to the shared tower electromagnetic interference mathematical model, and comprises:
Figure FDA0002470225420000043
wherein es (r) is the electric field intensity at the line online monitoring equipment; omega is the angular frequency of the incident wave; mu is magnetic conductivity; s is the surface area sub-region of the iron tower; g (r, r)T') is a Green function; is the dielectric constant; j (r)T') the induced current density generated on the surface of the iron tower.
12. The system of claim 7, wherein the electric field strength determining unit calculates an induced current generated on the surface of the shared iron tower, and determines the electric field strength at the line on-line monitoring device by solving the electric field integral equation using the induced current, and comprises:
dividing the surface of the angle iron tower into an illumination area and a shadow area according to the position of the electromagnetic wave emitted by the antenna of the communication equipment on the angle iron tower, and calculating the induced current of the illumination area and the shadow area by using a PO method and an MOM method respectively; wherein, the edge of the angle steel belongs to a shadow area;
respectively carrying out discrete approximation of integral equations on the induced currents of the illumination area and the shadow area by adopting a Galois gold RWG basis function based on a triangular surface element to obtain the induced current J of the dispersed PO areaPOAnd induced current J of MOM regionMOMThe method comprises the following steps:
Figure FDA0002470225420000051
Figure FDA0002470225420000052
wherein N isMoMAnd αnTotal number of subdivision elements and current coefficients of respective MoM regions, αnUnknown; n is a radical ofPOAnd βnTotal number of subdivision elements and current coefficient, respectively, of PO area, βnUnknown; f. ofnIs a RWG basis function;
introducing a unit vector tk+、tkTwo vectors perpendicular to the common edge of the triangle, establishing the RWG basis function fnRelation to common edge normal vector to determine βn；
Determining an electric field relation according to boundary conditions at the edges of the MoM region and the PO region, wherein the electric field relation comprises the following steps:
LEJMoM+LEJPO＝-Ei(4)
wherein L isEAn electric field operator;
according to the induced current JPOExpression of (1), induced current JMOMα and the electric field relationshipnInduced current JPOValue of (d) and induced current JMOMA value of (d);
will induce current JPOValue of (d) and induced current JMOMAre added to determine the induced current J (r) generated on the surface of the iron towerT') and based on the induced current J (r)T') and the electric field integral equation, determining the electric field strength at the line on-line monitoring device.
CN202010346291.5A 2020-04-27 2020-04-27 Method and system for determining electric field intensity of line on-line monitoring equipment Pending CN111710025A (en)

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