Overhead conductor transient sag monitoring method and device, terminal equipment and storage medium

Abstract

The invention discloses an overhead conductor transient sag monitoring method and device, terminal equipment and a storage medium, and belongs to the technical field of conductor sag monitoring, and the method comprises the steps: obtaining the physical parameters of a to-be-detected conductor, and the current environment parameters of an area where the to-be-detected conductor is located; calculating to obtain the current conductor temperature and knee point temperature; under the condition that the current wire temperature is larger than the knee point temperature, the current wire stress is calculated according to the steel core thermal expansion coefficient, the steel core elastic modulus, the steel core specific load, the initial operation temperature, the wire elastic modulus, the wire thermal expansion coefficient, the initial wire stress, the wire specific load and the current wire temperature; and finally, calculating the current conductor sag according to the current conductor stress. Through implementation of the method and the device, the problems that in the prior art, due to the fact that the overall temperature of the wire is uniformly used for calculating the sag of the wire, the calculated sag of the wire has a large error, and the operation stability of a power system is reduced can be solved.

Description

Technical Field

[0001] This invention relates to the field of conductor sag monitoring technology, and in particular to a method, device, terminal equipment, and storage medium for monitoring transient sag of overhead conductors. Background Technology

[0002] Overhead transmission lines, serving as the backbone and framework of the power system, are widely used in high-voltage and ultra-high-voltage long-distance transmission systems due to their advantages such as high economic efficiency, large transmission capacity, strong environmental adaptability, and ease of installation and expansion. As the primary carrier of electricity transmission, their transmission capacity is a crucial indicator of power supply economics. In the operation and maintenance of overhead lines, the temperature of the overhead conductors is a vital indicator of the power transmission system's operational status. Monitoring the temperature of the overhead conductors allows for a better understanding of their real-time condition, contributing to the stable operation of the power system. Conductor heating causes thermal expansion and contraction, affecting the sag of the transmission line. The higher the conductor temperature, the more significant the increase in sag. Increased sag can potentially cause electrical discharges to tall buildings or trees, posing a threat to life and property. Therefore, monitoring and calculating the sag of overhead conductors is extremely important.

[0003] Current sag calculation methods treat the steel core and aluminum strands as a single unit. However, as the conductor temperature rises, the tension in the aluminum strands gradually transfers to the steel core. When the conductor temperature reaches a certain level, the mechanical properties of the entire conductor are fully reflected in the steel core. At this point, if the overall mechanical parameters of the conductor are still used for calculation, the results will contain errors. Therefore, current technology relies on uniformly using the overall conductor temperature to calculate conductor sag. This leads to significant errors in the calculated sag when the conductor temperature causes the mechanical properties to be fully reflected in the steel core, resulting in the inability to detect sag increase in a timely manner and reducing the stability of the power system. Summary of the Invention

[0004] This invention provides a method, device, terminal equipment, and storage medium for monitoring transient sag of overhead conductors. It can solve the problem in the prior art where the overall temperature of the conductor is used to calculate the conductor sag, which leads to a large error in the calculated conductor sag when the conductor temperature fully reflects the mechanical properties of the steel core. This error makes it impossible to detect the increase in sag in time, thus reducing the stability of the power system operation.

[0005] One embodiment of the present invention provides a method for monitoring transient sag of overhead conductors, comprising:

[0006] Obtain the physical parameters of the conductor under test, as well as the current environmental parameters of the area where the conductor is located; wherein, the physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus;

[0007] Based on the above-mentioned conductor unit mass, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, and current environmental parameters, the current conductor temperature of the above-mentioned conductor under test is calculated.

[0008] Based on the initial operating temperature, thermal expansion coefficient of the steel core, elastic modulus of the steel core, stress of the steel core, cross-sectional area of ​​the steel core, thermal expansion coefficient of the aluminum strand, and elastic modulus of the aluminum strand, the knee temperature of the conductor under test is calculated.

[0009] If the current conductor temperature is not less than the knee point temperature mentioned above, then the current conductor stress is calculated based on the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the specific load of the steel core, the initial operating temperature, the elastic modulus of the conductor, the thermal expansion coefficient of the conductor, the initial conductor stress, the specific load of the conductor, and the current conductor temperature; otherwise, the current conductor stress is calculated based on the initial operating temperature, the elastic modulus of the conductor, the thermal expansion coefficient of the conductor, the initial conductor stress, the specific load of the conductor, and the current conductor temperature.

[0010] Based on the current conductor stress, the current conductor sag of the conductor under test is calculated.

[0011] Furthermore, the current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity.

[0012] Based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, diameter, surface emissivity, surface absorptivity, and current environmental parameters, the current conductor temperature is calculated, including:

[0013] Based on the above conductor diameter, surface emissivity, and current ambient temperature, a formula for calculating solar heat absorption power is constructed.

[0014] Based on the above conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity, and current air thermal conductivity, a formula for calculating the convective heat dissipation power of the conductor is constructed.

[0015] Based on the above conductor diameter, current solar radiation intensity, and surface absorptivity, the formula for calculating the conductor's radiative heat dissipation power is obtained;

[0016] Based on the above formulas for calculating conductor unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power, conductor convective heat dissipation power, and conductor radiative heat dissipation power, the transient thermal balance equation for overhead lines is constructed.

[0017] The current conductor temperature of the conductor under test is obtained by solving the transient thermal balance equation of the above overhead line.

[0018] Furthermore, the current conductor temperature of the conductor under test is obtained by solving the transient thermal balance equation of the overhead line, including:

[0019] The transient thermal balance equation of the above overhead line is processed by difference to obtain the differential transient thermal balance equation of the overhead line.

[0020] The wire temperature calculation operation is repeated according to the preset time step. When the current total number of iterations is not less than the preset iteration threshold, the wire temperature at the current iteration number is taken as the current wire temperature of the wire to be tested.

[0021] The above-mentioned conductor temperature calculation operation includes:

[0022] Obtain the conductor temperature at the current iteration number; where the initial conductor temperature is the initial operating temperature mentioned above;

[0023] If the current total number of iterations is less than the preset iteration threshold, the conductor temperature for the next iteration is calculated based on the conductor temperature at the current iteration, the preset time step, and the differential transient thermal balance equation of the overhead line.

[0024] Furthermore, if the current conductor temperature is greater than the knee point temperature, the current conductor stress is calculated based on the core thermal expansion coefficient, core elastic modulus, core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature; otherwise, the current conductor stress is calculated based on the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature, including:

[0025] Obtain the height difference between the two suspension points of the conductor under test, as well as the span of the conductor under test.

[0026] Based on the aforementioned height difference and span, the elevation angle of the conductor to be measured is calculated.

[0027] If the current conductor temperature is greater than the above-mentioned knee point temperature, the first overhead transmission line inclined parabolic equation is constructed based on the above-mentioned span, elevation angle, steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature. After solving the above-mentioned first overhead transmission line inclined parabolic equation, the current conductor stress is obtained.

[0028] If the current conductor temperature is not greater than the above-mentioned knee point temperature, based on the above-mentioned span, elevation angle, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature, the second overhead transmission line inclined parabolic equation is constructed, and the above-mentioned second overhead transmission line inclined parabolic equation is solved to obtain the current conductor stress.

[0029] Furthermore, based on the current conductor stress, the current conductor sag of the conductor under test is calculated, including:

[0030] If the current conductor temperature is not lower than the above knee point temperature, the current conductor sag is calculated based on the above steel core specific load, span, and current conductor stress.

[0031] If the current conductor temperature is lower than the knee point temperature mentioned above, the current conductor sag is calculated based on the conductor specific load, span, and current conductor stress.

[0032] Furthermore, after calculating the current conductor sag, the calculation also includes:

[0033] An early warning is issued when the current conductor sag exceeds a preset conductor sag threshold.

[0034] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments;

[0035] This invention provides a monitoring device for transient sag of overhead conductors, comprising:

[0036] The module includes a parameter acquisition module, a conductor temperature calculation module, a knee point temperature calculation module, a conductor stress calculation module, and a conductor sag calculation module.

[0037] The parameter acquisition module is used to acquire the physical parameters of the conductor under test and the current environmental parameters of the area where the conductor under test is located. The physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus.

[0038] The aforementioned conductor temperature calculation module is used to calculate the current conductor temperature of the conductor under test based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, wire diameter, surface emissivity, surface absorptivity, and current environmental parameters.

[0039] The knee temperature calculation module described above is used to calculate the knee temperature of the conductor under test based on the initial operating temperature, the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the stress of the steel core, the cross-sectional area of ​​the steel core, the thermal expansion coefficient of the aluminum strand, and the elastic modulus of the aluminum strand.

[0040] The aforementioned conductor stress calculation module is used to calculate the current conductor stress based on the aforementioned steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature if the current conductor temperature is not less than the aforementioned knee point temperature; otherwise, it calculates the current conductor stress based on the aforementioned initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature.

[0041] The aforementioned conductor sag calculation module is used to calculate the current conductor sag of the conductor under test based on the current conductor stress.

[0042] Furthermore, the current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity.

[0043] The aforementioned conductor temperature calculation module includes:

[0044] The system includes a solar heat absorption power calculation unit, a conductor convection heat dissipation power calculation unit, a conductor radiation heat dissipation power calculation unit, an overhead line transient thermal balance equation construction unit, and an equation solving unit.

[0045] The aforementioned solar heat absorption power calculation formula construction unit is used to construct a solar heat absorption power calculation formula based on the aforementioned conductor diameter, surface emissivity, and current ambient temperature.

[0046] The above-mentioned conductor convection heat dissipation power calculation formula construction unit is used to construct the conductor convection heat dissipation power calculation formula based on the above-mentioned conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity and current air thermal conductivity.

[0047] The above-mentioned conductor radiation heat dissipation power calculation formula construction unit is used to calculate the conductor radiation heat dissipation power calculation formula based on the conductor diameter, the current solar radiation intensity and the surface absorptivity.

[0048] The above-mentioned overhead line transient heat balance equation construction unit is used to construct the overhead line transient heat balance equation based on the above-mentioned conductor unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power calculation formula, conductor convective heat dissipation power calculation formula and conductor radiative heat dissipation power calculation formula.

[0049] The above equation solving unit is used to solve the transient thermal balance equation of the above overhead line to obtain the current conductor temperature of the conductor under test.

[0050] Based on the above method embodiments, the present invention provides a corresponding terminal device embodiment;

[0051] The present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the monitoring method for transient sag of an overhead conductor as described in any embodiment of the present invention.

[0052] Based on the above method embodiments, the present invention provides a corresponding storage medium embodiment;

[0053] The present invention provides a storage medium including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the monitoring method for transient sag of an overhead conductor as described in any embodiment of the present invention.

[0054] The embodiments of the present invention have the following beneficial effects:

[0055] This invention provides a method, apparatus, terminal equipment, and storage medium for monitoring transient sag of overhead conductors. The method includes: acquiring the physical parameters of the conductor under test and the current environmental parameters of the area where the conductor is located; wherein the physical parameters include: the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, conductor unit mass per unit length, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, steel core thermal expansion coefficient, steel core elastic modulus, steel core stress, steel core cross-sectional area, steel core specific load, aluminum strand thermal expansion coefficient, and aluminum strand elastic modulus; subsequently, based on the conductor unit mass, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, and current... Based on the environmental parameters, the current conductor temperature of the conductor under test is calculated. Then, based on the initial operating temperature, the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the stress of the steel core, the cross-sectional area of ​​the steel core, the thermal expansion coefficient of the aluminum strand, and the elastic modulus of the aluminum strand, the knee temperature of the conductor under test is calculated. If the current conductor temperature is not less than the knee temperature, the current conductor stress is calculated based on the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the specific load of the steel core, the initial operating temperature, the elastic modulus of the conductor, the thermal expansion coefficient of the conductor, the initial conductor stress, the specific load of the conductor, and the current conductor temperature. Otherwise, the current conductor stress is calculated based on the initial operating temperature, the elastic modulus of the conductor, the thermal expansion coefficient of the conductor, the initial conductor stress, the specific load of the conductor, and the current conductor temperature. Finally, based on the current conductor stress, the current conductor sag of the conductor under test is calculated. Therefore, this invention calculates the knee temperature of the conductor under test so that the two can be compared after the conductor temperature is calculated. If the conductor temperature is greater than the knee temperature, it means that the mechanical properties of the entire conductor are fully reflected in the mechanical properties of the steel core. Therefore, when calculating the conductor stress, the relevant parameters of the steel core are used, so that the obtained conductor sag result fully takes into account the mechanical properties of the steel core, and the obtained sag result is more accurate, thus improving the stability of the power system operation. Attached Figure Description

[0056] To more clearly illustrate the technical solution of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0057] Figure 1 This is a flowchart illustrating a method for monitoring transient sag of overhead conductors according to an embodiment of the present invention.

[0058] Figure 2This is a schematic diagram of the structure of a monitoring device for transient sag of an overhead conductor provided in an embodiment of the present invention. Detailed Implementation

[0059] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0061] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0062] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0063] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0064] In the description of the embodiments of this application, the term "multiple" refers to two or more (including two), similarly, "multiple sets" refers to two or more (including two sets), and "multiple pieces" refers to two or more (including two pieces).

[0065] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0066] See Figure 1 To address the problem in existing technologies where conductor sag is calculated using the overall conductor temperature, which leads to significant errors in the calculated sag when the conductor's mechanical properties are fully reflected in the steel core, thus failing to detect sag increase in a timely manner and reducing the stability of the power system, this invention provides a method for monitoring transient sag of overhead conductors, comprising:

[0067] Step S101: Obtain the physical parameters of the conductor under test, and the current environmental parameters of the area where the conductor under test is located; wherein, the physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's unit mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus;

[0068] Specifically, if the current period is the first time the conductor under test has just been put into operation, the ambient temperature before the conductor under test is put into operation is taken as the initial operating temperature, in °C; the initial conductor stress is the overall stress of the conductor before the conductor under test is put into operation; the conductor specific load is the overall specific load of the conductor under test, which, along with the conductor elastic modulus, conductor thermal expansion coefficient, and initial conductor stress, can be directly measured and are fixed values ​​in this invention; the unit mass of the conductor per unit length is kg, and the unit of specific heat capacity is J / (kg·K). The conductor unit mass, specific heat capacity, conductor cross-sectional area, resistivity, and conductor diameter can all be obtained by referring to tables based on the structure and material of the conductor under test; the current operating current is the current currently passing through the conductor under test, in A; the values ​​of surface emissivity and surface absorptivity are equal; the conductor elastic modulus, conductor thermal expansion coefficient, conductor specific load, steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, aluminum strand thermal expansion coefficient, and aluminum strand elastic modulus are all fixed values ​​in the calculation process of this invention.

[0069] Step S102: Based on the above-mentioned conductor unit mass, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, and current environmental parameters, calculate the current conductor temperature of the conductor to be tested.

[0070] In a preferred embodiment, the current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity.

[0071] Based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, diameter, surface emissivity, surface absorptivity, and current environmental parameters, the current conductor temperature is calculated, including:

[0072] Based on the above conductor diameter, surface emissivity, and current ambient temperature, a formula for calculating solar heat absorption power is constructed.

[0073] Specifically, the formula for calculating the solar heat absorption power mentioned above is:

[0074] q r =πD0ε c σ[(Ts+273) 4 -(T a +273) 4 ]

[0075] In the formula, q r The value represents the solar heat absorption power, D0 represents the wire diameter, and ε represents the conductor diameter. c σ represents the surface emissivity, σ represents the Stefan-Boltzmann constant, and Ts represents the conductor temperature in °C. a This indicates the current ambient temperature.

[0076] Based on the above conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity, and current air thermal conductivity, a formula for calculating the convective heat dissipation power of the conductor is constructed.

[0077] Specifically, the formula for calculating the convective heat dissipation power of the aforementioned conductor is as follows:

[0078]

[0079] In the formula, q c q represents the convective heat dissipation power of the conductor. cn ρ represents the convective heat dissipation power generated by natural convection. f This indicates the current air density, expressed in kg / (m³). 3 ), q c1 K represents the convective heat dissipation power at low wind speeds. angleRe represents the wind direction factor, which in this invention takes a value of 1. c V represents the Reynolds number of the conductor. w Indicates the current wind speed, μ f k represents the current aerodynamic viscosity. f q represents the current thermal conductivity of the air. c2 This indicates the convective heat dissipation power at high wind speeds.

[0080] Based on the above conductor diameter, current solar radiation intensity, and surface absorptivity, the formula for calculating the conductor's radiative heat dissipation power is obtained;

[0081] Specifically, the formula for calculating the heat dissipation power of the conductor radiation is:

[0082] q s =α c Q s D0

[0083] In the formula, q s α represents the heat dissipation power radiated by the conductor. c Q represents the surface absorptivity. s This represents the current solar radiation intensity, expressed in W / m². 2 .

[0084] Based on the above formulas for calculating conductor unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power, conductor convective heat dissipation power, and conductor radiative heat dissipation power, the transient thermal balance equation for overhead lines is constructed.

[0085] Specifically, the constructed transient thermal balance equation for the overhead line is as follows:

[0086]

[0087] In the formula, q c (n) represents the convective heat dissipation power of the wire in the nth iteration, q r (n) represents the solar heat absorption power in the nth iteration, m s C represents the unit mass of the conductor. ps Indicates specific heat capacity. The differential term representing the temperature of the conductor, q s R(n) represents the radiative heat dissipation power of the conductor in the nth iteration, I represents the current operating current, R represents the AC resistance per unit length of the conductor under test, R(n) represents the AC resistance in the nth iteration, and ρ s Represents resistivity, S represents the cross-sectional area of ​​the conductor, Y represents resistivity. s α represents the skin effect coefficient of the conductor under test. 20 This represents the temperature coefficient of the conductor being tested.

[0088] The current conductor temperature of the conductor under test is obtained by solving the transient thermal balance equation of the above overhead line.

[0089] In this preferred embodiment, the current conductor temperature of the conductor under test is calculated by constructing a transient thermal balance equation for the overhead line based on the conductor's unit mass, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, and current environmental parameters.

[0090] In another preferred embodiment, solving the transient thermal balance equation of the overhead line to obtain the current conductor temperature of the conductor under test includes:

[0091] The transient thermal balance equation of the above overhead line is processed by difference to obtain the differential transient thermal balance equation of the overhead line.

[0092] Specifically, the conductor steady-state differential terms in the above-mentioned overhead line transient heat balance equation are differentially processed and integrated to obtain the differential overhead line transient heat balance equation for iterative calculation:

[0093]

[0094] In the formula, T s (n+1) represents the conductor temperature at the (n+1)th iteration, I(n) represents the operating current at the nth iteration, and T s (n) represents the wire temperature at the nth iteration, q c [T s [(n)] represents the convective heat dissipation power of the conductor when the conductor temperature is the same as that in the nth iteration, q r [T s [(n)] represents the solar heat absorption power when the conductor temperature is the same as the conductor temperature at the nth iteration, and Δt represents the preset time step.

[0095] The wire temperature calculation operation is repeated according to the preset time step. When the current total number of iterations is not less than the preset iteration threshold, the wire temperature at the current iteration number is taken as the current wire temperature of the wire to be tested.

[0096] The above-mentioned conductor temperature calculation operation includes:

[0097] Obtain the conductor temperature at the current iteration number; where the initial conductor temperature is the initial operating temperature mentioned above;

[0098] If the current total number of iterations is less than the preset iteration threshold, the conductor temperature for the next iteration is calculated based on the conductor temperature at the current iteration, the preset time step, and the differential transient thermal balance equation of the overhead line.

[0099] Specifically, the initial values ​​of the iterative algorithm are set, and the conductor unit mass, specific heat capacity, current operating current, conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, and current environmental parameters are input at each iteration time. Temperature iterative calculation is performed to obtain the conductor temperature value. When the preset time step approaches 0, it can be assumed that the operating current and environmental parameters of the conductor under test remain unchanged within this preset time step. Schematic, the environmental parameters, conductor unit mass, specific heat capacity, current operating current (i.e., the operating current corresponding to this minute), conductor cross-sectional area, resistivity, conductor diameter, surface emissivity, and surface absorptivity of a certain conductor under test are obtained minute by minute. It is assumed that within one minute, among the parameters used to construct the transient thermal balance equation of the overhead line, all parameters except the conductor temperature remain unchanged. Let the initial conductor temperature Ts(0) be the ambient temperature. During the calculation, the preset iteration number threshold is set to 60, that is, 60 iterations are performed per minute. After the iteration is completed, the conductor temperature value Ts(60) is output, which is the conductor temperature corresponding to this minute, i.e., the current conductor temperature. If real-time monitoring of conductor temperature is required, this value is used as the initial operating temperature for the next minute and substituted into the differential transient thermal balance equation for the overhead line to perform the next round of calculation. Therefore, for different measured parameters per minute, only the initial operating temperature for each round, the corresponding operating current per minute, and other relevant parameters need to be input to calculate the real-time temperature of the conductor.

[0100] In this preferred embodiment, the current conductor temperature of the conductor under test is obtained by iteratively solving the transient thermal balance equation of the overhead line.

[0101] Step S103: Calculate the knee temperature of the conductor to be tested based on the initial operating temperature, thermal expansion coefficient of the steel core, elastic modulus of the steel core, stress of the steel core, cross-sectional area of ​​the steel core, thermal expansion coefficient of the aluminum strand, and elastic modulus of the aluminum strand.

[0102] Specifically, to simplify the calculation, the following assumptions are made regarding the knee temperature model of the conductor under test: (1) The radial temperature distribution of the conductor under test is ignored, and the conductor under test is considered to be an isothermal body. (2) The creep effect during the long-term operation of the conductor under test is ignored, and the elongation of the conductor under test is considered to come entirely from thermal expansion and elastic deformation. (3) The internal and external forces of the conductor under test are balanced, and residual deformation is ignored. Subsequently, based on the steel core stress, aluminum strand stress, steel core cross-sectional area, and aluminum strand cross-sectional area corresponding to the steel core and aluminum strand in the conductor under test, the internal force balance equation of the steel-core aluminum stranded wire is established:

[0103] δ s A s +δ a A a =δS

[0104] In the formula, δ s Indicates the stress in the steel core, A s δ represents the cross-sectional area of ​​the steel core. a Indicates the stress in aluminum strands, A a δ represents the cross-sectional area of ​​the aluminum strand, and δ represents the overall conductor stress of the conductor under test.

[0105] Specifically, due to the tight connection between the steel core and the aluminum strands, it is assumed that the steel core and the aluminum strands have the same elongation during the elastic deformation and thermal expansion of the conductor under test. This change is expressed by the following formula:

[0106] α s (T s -T0)+δ s / E s =α a (T s -T0)+δ a / E a

[0107] In the formula, α s T0 represents the coefficient of thermal expansion of the steel core, and E represents the initial operating temperature. s α represents the elastic modulus of the steel core. a E represents the coefficient of thermal expansion of aluminum. a This indicates the elastic modulus of aluminum.

[0108] Specifically, when the knee temperature is reached, all the forces in the conductor are transferred to the steel core. At this point, assuming the stress in the aluminum strands is zero, and combining the above-mentioned internal force balance equations for steel-cored aluminum stranded wire with the formulas corresponding to the elastic deformation and thermal expansion processes of the conductor under test, the formula for calculating the knee temperature of steel-cored aluminum stranded wire can be derived, as shown in the following formula:

[0109]

[0110] In the formula, KPT represents the knee temperature.

[0111] Step S104: If the current conductor temperature is not less than the above-mentioned knee point temperature, then the current conductor stress is calculated based on the above-mentioned steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature; otherwise, the current conductor stress is calculated based on the above-mentioned initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature.

[0112] Specifically, when the conductor temperature under test is higher than the knee point temperature, the mechanical properties of the entire conductor will be entirely reflected in the mechanical properties of the steel core. Therefore, it is necessary to introduce the mechanical parameters of the steel core (i.e., the thermal expansion coefficient, elastic modulus, and specific load of the steel core) at this time to calculate the current conductor stress.

[0113] In a preferred embodiment, if the current conductor temperature is greater than the knee point temperature, the current conductor stress is calculated based on the core thermal expansion coefficient, core elastic modulus, core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature; otherwise, the current conductor stress is calculated based on the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature, including:

[0114] Obtain the height difference between the two suspension points of the conductor under test, as well as the span of the conductor under test.

[0115] Based on the aforementioned height difference and span, the elevation angle of the conductor to be measured is calculated.

[0116] Specifically, the elevation angle is calculated using the following formula:

[0117]

[0118] In the formula, β represents the elevation angle, h represents the elevation difference, and l represents the span.

[0119] If the current conductor temperature is greater than the above-mentioned knee point temperature, the first overhead transmission line inclined parabolic equation is constructed based on the above-mentioned span, elevation angle, steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature. After solving the above-mentioned first overhead transmission line inclined parabolic equation, the current conductor stress is obtained.

[0120] If the current conductor temperature is not greater than the above-mentioned knee point temperature, based on the above-mentioned span, elevation angle, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature, the second overhead transmission line inclined parabolic equation is constructed, and the above-mentioned second overhead transmission line inclined parabolic equation is solved to obtain the current conductor stress.

[0121] Specifically, the calculation formulas for the two cases of solving the conductor stress mentioned above can be expressed by the following formula:

[0122]

[0123] In the formula, δ 01 Let E represent the initial conductor stress, E represent the conductor's elastic modulus, γ represent the conductor's specific load, α represent the conductor's coefficient of thermal expansion, and δ represent the conductor's coefficient of thermal expansion. 02 E represents the current conductor stress. 02 γ represents the current elastic modulus. 02 Indicates the current load ratio, α 02 This represents the current coefficient of thermal expansion.

[0124] Specifically, if the current conductor temperature is higher than the knee point temperature mentioned above, then the elastic modulus of the steel core is used as the current elastic modulus E in the above formula. 02 The steel core specific load is taken as the current specific load γ. 02 The coefficient of thermal expansion of the steel core is used as the current coefficient of thermal expansion α. 02 Otherwise, the above-mentioned elastic modulus of the conductor is used as the current elastic modulus E in the above formula. 02 The above-mentioned conductor load ratio is taken as the current load ratio γ. 02 The thermal expansion coefficient of the above-mentioned conductor is taken as the current thermal expansion coefficient α. 02 The current conductor stress is then obtained by solving the problem.

[0125] In this preferred embodiment, the current conductor stress is calculated by combining the result of the magnitude difference between the knee temperature and the current conductor temperature, along with the core thermal expansion coefficient, core elastic modulus, core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature.

[0126] Step S105: Calculate the current sag of the conductor under test based on the current conductor stress.

[0127] In a preferred embodiment, the calculation of the current conductor sag of the conductor under test based on the current conductor stress includes:

[0128] If the current conductor temperature is not lower than the above knee point temperature, the current conductor sag is calculated based on the above steel core specific load, span, and current conductor stress.

[0129] If the current conductor temperature is lower than the knee point temperature mentioned above, the current conductor sag is calculated based on the conductor specific load, span, and current conductor stress.

[0130] Specifically, the calculation formulas for the two cases mentioned above for solving conductor sag can be expressed by the following formula: In the formula, Indicates conductor sag. This indicates the specific load. If the current conductor temperature is higher than the aforementioned knee point temperature, the aforementioned steel core specific load will be used as this specific load. If the value is not specified, then the above conductor load ratio will be used as this load ratio. The value of .

[0133] Preferably, the calculation process for transient sag of overhead conductors in this invention is based on the transient thermal balance equation of overhead lines, combined with real-time environmental parameters and the operating current of the conductor under test, and considers the knee temperature of the conductor under test, thus realizing the corrective calculation of overhead line sag. This method has the advantages of fast calculation speed, low cost, wide applicability, and high calculation accuracy. Compared with existing sag calculation methods, this method is simpler and saves economic costs; it is less affected by external environmental factors and less susceptible to interference; it has a wide range of applications, and some commonly used overhead conductors can be calculated using this method; the calculation accuracy is high, considering knee temperature and environmental parameter changes, which is more consistent with the actual operating conditions of the conductor. This method can greatly reduce operating costs and improve the efficiency of sag calculation, which is of great significance for conductor sag calculation and can provide a reference for relevant operation and maintenance departments.

[0134] In this preferred embodiment, the current sag of the conductor under test is calculated using the current conductor stress.

[0135] In another preferred embodiment, after calculating the current conductor sag, the method further includes:

[0136] An early warning is issued when the current conductor sag exceeds a preset conductor sag threshold.

[0137] Preferably, since excessive conductor sag may discharge onto tall buildings or trees, causing harm to life and property and affecting the stable operation of the power system, it is necessary to issue an early warning when the current conductor sag exceeds the preset conductor sag threshold, so as to remind relevant personnel to inspect and maintain the line.

[0138] In this preferred embodiment, by comparing the current conductor sag with a preset conductor sag threshold, an early warning is issued to relevant personnel when the current conductor sag exceeds the preset conductor sag threshold.

[0139] Based on the above method embodiments, the present invention provides corresponding apparatus embodiments.

[0140] like Figure 2 As shown, an embodiment of the present invention provides a monitoring device for transient sag of an overhead conductor, comprising:

[0141] The module includes a parameter acquisition module, a conductor temperature calculation module, a knee point temperature calculation module, a conductor stress calculation module, and a conductor sag calculation module.

[0142] The parameter acquisition module is used to acquire the physical parameters of the conductor under test and the current environmental parameters of the area where the conductor under test is located. The physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus.

[0143] The aforementioned conductor temperature calculation module is used to calculate the current conductor temperature of the conductor under test based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, wire diameter, surface emissivity, surface absorptivity, and current environmental parameters.

[0144] The knee temperature calculation module described above is used to calculate the knee temperature of the conductor under test based on the initial operating temperature, the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the stress of the steel core, the cross-sectional area of ​​the steel core, the thermal expansion coefficient of the aluminum strand, and the elastic modulus of the aluminum strand.

[0145] The aforementioned conductor stress calculation module is used to calculate the current conductor stress based on the aforementioned steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature if the current conductor temperature is not less than the aforementioned knee point temperature; otherwise, it calculates the current conductor stress based on the aforementioned initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature.

[0146] The aforementioned conductor sag calculation module is used to calculate the current conductor sag of the conductor under test based on the current conductor stress.

[0147] In a preferred embodiment, the current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity.

[0148] The aforementioned conductor temperature calculation module includes:

[0149] The system includes a solar heat absorption power calculation unit, a conductor convection heat dissipation power calculation unit, a conductor radiation heat dissipation power calculation unit, an overhead line transient thermal balance equation construction unit, and an equation solving unit.

[0150] The aforementioned solar heat absorption power calculation formula construction unit is used to construct a solar heat absorption power calculation formula based on the aforementioned conductor diameter, surface emissivity, and current ambient temperature.

[0151] The above-mentioned conductor convection heat dissipation power calculation formula construction unit is used to construct the conductor convection heat dissipation power calculation formula based on the above-mentioned conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity and current air thermal conductivity.

[0152] The above-mentioned conductor radiation heat dissipation power calculation formula construction unit is used to calculate the conductor radiation heat dissipation power calculation formula based on the conductor diameter, the current solar radiation intensity and the surface absorptivity.

[0153] The above-mentioned overhead line transient heat balance equation construction unit is used to construct the overhead line transient heat balance equation based on the above-mentioned conductor unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power calculation formula, conductor convective heat dissipation power calculation formula and conductor radiative heat dissipation power calculation formula.

[0154] The above equation solving unit is used to solve the transient thermal balance equation of the above overhead line to obtain the current conductor temperature of the conductor under test.

[0155] It should be noted that the device embodiments described above are merely illustrative. The modules described as separate components may or may not be physically separate, and the components shown as modules may or may not be physical modules; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationship between modules indicates that they have a communication connection, which can be implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without creative effort. The above schematic diagram is merely an example of a monitoring device for transient sag of overhead conductors and does not constitute a limitation on a monitoring device for transient sag of overhead conductors. It may include more or fewer components than shown, or combine certain components, or use different components.

[0156] Based on the above method embodiments, the present invention provides corresponding terminal device embodiments.

[0157] Another embodiment of the present invention provides a terminal device, including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor. When the processor executes the computer program, it implements the monitoring method for transient sag of an overhead conductor as described in any embodiment of the present invention.

[0158] For example, in this embodiment, the computer program can be divided into one or more modules, which are stored in the memory and executed by the processor to complete the present invention. The one or more modules may be a series of computer program instruction segments capable of performing a specific function, which describe the execution process of the computer program in the device.

[0159] The aforementioned terminal devices may be computing devices such as desktop computers, laptops, handheld computers, and cloud servers. These devices may include, but are not limited to, processors and memory.

[0160] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. This processor is the control center of the device, connecting various parts of the device via various interfaces and lines.

[0161] The aforementioned memory can be used to store the aforementioned computer programs and / or modules. The aforementioned processor implements various functions of the aforementioned device by running or executing the computer programs and / or modules stored in the aforementioned memory, and by calling data stored in the memory. The aforementioned memory may mainly include a program storage area and a data storage area, wherein the program storage area may store the operating system, at least one application program required for a function, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0162] Based on the above method embodiments, the present invention provides corresponding storage medium embodiments.

[0163] Another embodiment of the present invention provides a storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the monitoring method for transient sag of overhead conductors described in any embodiment of the present invention.

[0164] In this embodiment, the storage medium is a computer-readable storage medium, and the computer program includes computer program code, which may be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium may include any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc.

[0165] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method of monitoring the transient sag of an overhead conductor, characterized by, include: The physical parameters of the conductor under test and the current environmental parameters of the area where the conductor is located are obtained. The physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus. The current temperature of the conductor under test is calculated based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, diameter, surface emissivity, surface absorptivity, and current environmental parameters. The knee temperature of the conductor under test is calculated based on the initial operating temperature, the coefficient of thermal expansion of the steel core, the elastic modulus of the steel core, the stress of the steel core, the cross-sectional area of ​​the steel core, the coefficient of thermal expansion of the aluminum strand, and the elastic modulus of the aluminum strand. If the current conductor temperature is not less than the knee point temperature, the current conductor stress is calculated based on the steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature; otherwise, the current conductor stress is calculated based on the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature. The current sag of the conductor under test is calculated based on the current conductor stress.

2. The method of claim 1, wherein, Current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity. The calculation of the current conductor temperature based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, diameter, surface emissivity, surface absorptivity, and current environmental parameters includes: Based on the conductor diameter, surface emissivity, and current ambient temperature, a formula for calculating solar heat absorption power is constructed. Based on the conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity, and current air thermal conductivity, a formula for calculating the convective heat dissipation power of the conductor is constructed. Based on the conductor diameter, the current solar radiation intensity, and the surface absorptivity, the formula for calculating the conductor's radiative heat dissipation power is obtained. Based on the conductor's unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power calculation formula, conductor convective heat dissipation power calculation formula, and conductor radiative heat dissipation power calculation formula, the transient thermal balance equation of the overhead line is constructed. The current conductor temperature of the conductor under test is obtained by solving the transient thermal balance equation of the overhead line.

3. The method of claim 2, wherein, The process of solving the transient thermal balance equation of the overhead line to obtain the current conductor temperature of the conductor under test includes: The transient thermal balance equation of the overhead line is processed by difference to obtain the differential transient thermal balance equation of the overhead line. The wire temperature calculation operation is repeated according to the preset time step. When the current total number of iterations is not less than the preset iteration threshold, the wire temperature at the current iteration number is taken as the current wire temperature of the wire to be tested. The conductor temperature calculation operation includes: Obtain the conductor temperature at the current iteration number; wherein, the initial conductor temperature is the initial operating temperature; If the current total number of iterations is less than the preset iteration threshold, the conductor temperature for the next iteration is calculated based on the conductor temperature at the current iteration, the preset time step, and the differential transient thermal balance equation of the overhead line.

4. The method of claim 3, wherein, If the current conductor temperature is not less than the knee point temperature, then the current conductor stress is calculated based on the steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature. Otherwise, based on the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature, the current conductor stress is calculated, including: Obtain the height difference between the two suspension points of the conductor under test, and the span of the conductor under test; The elevation angle of the conductor to be measured is calculated based on the height difference and the span. If the current conductor temperature is greater than the knee point temperature, the first overhead transmission line inclined parabolic equation is constructed based on the span, elevation angle, steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and the current conductor temperature. After solving the first overhead transmission line inclined parabolic equation, the current conductor stress is obtained. If the current conductor temperature is not greater than the knee point temperature, the second overhead transmission line inclined parabolic equation is constructed based on the span, elevation angle, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature. The second overhead transmission line inclined parabolic equation is then solved to obtain the current conductor stress.

5. The method of claim 4, wherein, The step of calculating the current conductor sag of the conductor under test based on the current conductor stress includes: If the current conductor temperature is not less than the knee point temperature, the current conductor sag is calculated based on the steel core specific load, span, and current conductor stress. If the current conductor temperature is lower than the knee point temperature, the current conductor sag is calculated based on the conductor specific load, span, and current conductor stress.

6. The method of claim 5, wherein, After calculating the current conductor sag, the following steps are also included: An early warning is issued when the current conductor sag exceeds a preset conductor sag threshold.

7. A device for monitoring the transient sag of an overhead conductor, characterized in that include: The module includes a parameter acquisition module, a conductor temperature calculation module, a knee point temperature calculation module, a conductor stress calculation module, and a conductor sag calculation module. The parameter acquisition module is used to acquire the physical parameters of the conductor under test and the current environmental parameters of the area where the conductor under test is located; wherein, the physical parameters include: the initial operating temperature of the conductor under test, the conductor's elastic modulus, the conductor's coefficient of thermal expansion, the initial conductor stress, the conductor's specific load, the conductor's unit mass per unit length, its specific heat capacity, the current operating current, the conductor's cross-sectional area, resistivity, conductor diameter, surface emissivity, surface absorptivity, the steel core's coefficient of thermal expansion, the steel core's elastic modulus, the steel core's stress, the steel core's cross-sectional area, the steel core's specific load, the aluminum strand's coefficient of thermal expansion, and the aluminum strand's elastic modulus; The conductor temperature calculation module is used to calculate the current conductor temperature of the conductor under test based on the conductor's unit mass, specific heat capacity, current operating current, cross-sectional area, resistivity, wire diameter, surface emissivity, surface absorptivity, and current environmental parameters. The knee temperature calculation module is used to calculate the knee temperature of the conductor under test based on the initial operating temperature, the thermal expansion coefficient of the steel core, the elastic modulus of the steel core, the stress of the steel core, the cross-sectional area of ​​the steel core, the thermal expansion coefficient of the aluminum strand, and the elastic modulus of the aluminum strand. The conductor stress calculation module is used to calculate the current conductor stress based on the steel core thermal expansion coefficient, steel core elastic modulus, steel core specific load, initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature if the current conductor temperature is not less than the knee point temperature; otherwise, it calculates the current conductor stress based on the initial operating temperature, conductor elastic modulus, conductor thermal expansion coefficient, initial conductor stress, conductor specific load, and current conductor temperature. The conductor sag calculation module is used to calculate the current conductor sag of the conductor under test based on the current conductor stress.

8. The device for monitoring the transient sag of an overhead conductor according to claim 7, characterized in that, Current environmental parameters include: current ambient temperature, current air density, current wind speed, current aerodynamic viscosity, current air thermal conductivity, and current solar radiation intensity. The conductor temperature calculation module includes: The system includes a solar heat absorption power calculation unit, a conductor convection heat dissipation power calculation unit, a conductor radiation heat dissipation power calculation unit, an overhead line transient thermal balance equation construction unit, and an equation solving unit. The solar heat absorption power calculation formula construction unit is used to construct a solar heat absorption power calculation formula based on the conductor diameter, surface emissivity and current ambient temperature. The conductor convection heat dissipation power calculation formula construction unit is used to construct the conductor convection heat dissipation power calculation formula based on the conductor diameter, current air density, current ambient temperature, current wind speed, current aerodynamic viscosity, and current air thermal conductivity. The conductor radiation heat dissipation power calculation formula construction unit is used to calculate the conductor radiation heat dissipation power calculation formula based on the conductor diameter, the current solar radiation intensity and the surface absorptivity. The overhead line transient heat balance equation construction unit is used to construct the overhead line transient heat balance equation based on the conductor unit mass, specific heat capacity, current operating current, resistivity, conductor cross-sectional area, solar heat absorption power calculation formula, conductor convective heat dissipation power calculation formula, and conductor radiative heat dissipation power calculation formula. The equation solving unit is used to solve the transient thermal balance equation of the overhead line to obtain the current conductor temperature of the conductor under test.

9. A terminal device, comprising: The system includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements a method for monitoring transient sag of an overhead conductor as described in any one of claims 1 to 6.

10. A storage medium, characterized by The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device containing the storage medium to perform a monitoring method for transient sag of an overhead conductor as described in any one of claims 1 to 6.

Images