Method and device for monitoring conductor sag of overhead transmission line under mountain fire condition, terminal equipment and storage medium

Abstract

The invention discloses a conductor sag monitoring method and device for an overhead transmission line under a forest fire condition, terminal equipment and a storage medium. The method comprises the following steps: acquiring conductor parameters of the overhead transmission line; calculating inflection point temperature of the overhead transmission line according to the lead parameters; for the average temperature of the wire at each moment, if the average temperature of the wire at the current moment is smaller than the inflection point temperature, determining the sag of the wire at the current moment according to the stress of the steel core, the stress of the aluminum stranded wire, the average temperature of the wire, the length of the wire, the specific load of the wire, the span length, the fixed parameters of the steel core and the fixed parameters of the aluminum stranded wire at each moment; if the average temperature of the wire at the current moment is not less than the inflection point temperature, determining the sag of the wire at the current moment according to the steel core stress, the average temperature of the wire, the length of the wire, the specific load of the wire, the span length and the fixed parameters of the steel core at each moment; and when the wire sag at any moment breaks through the clearance distance to the ground of the wire, giving an alarm to operation and maintenance personnel of the overhead transmission line.

Description

Technical Field

[0001] The present invention relates to the field of electric power technology, and in particular to a method, device, terminal equipment and storage medium for monitoring sag of conductors of overhead power transmission lines under wildfire conditions. Background Art

[0002] Wildfires are common natural disasters in nature. Unlike the uniform temperature rise caused by the thermal effect of the uniformly distributed current load inside the conductor, the local high temperature of the wildfire causes uneven temperature rise in different positions of the conductor, and factors such as the flame heat flux density, flame height, wildfire area, and the position of the wildfire relative to the overhead conductor will further affect the degree of uneven temperature rise of the conductor. The increase in sag in the high temperature area not only leads to a decrease in the line-to-ground clearance distance, which may exceed the safe distance of the conductor to the ground, but also shortens the distance between the conductor and the flame, intensifies the heat conduction of the heat source to the conductor, and further increases the temperature of the conductor until the maximum sag and temperature field distribution reach a steady state. In severe cases, the flame directly covers the conductor, and the probability of short-circuit breakdown of the transmission line to the ground gap increases sharply, seriously affecting the stable operation of the power system. Therefore, accurately calculating the sag of the conductor under the condition of uneven temperature rise in wildfires is of great significance for monitoring and maintaining the safe and stable operation of the power system.

[0003] However, the conductor sag calculation of existing overhead transmission lines is difficult to exceed the inflection point temperature of steel-core aluminum stranded wire under normal operation because the relevant standards limit the maximum current carrying value of the conductor to limit the maximum operating temperature of the conductor. Therefore, when calculating the conductor sag, the influence of the inflection point temperature on the conductor sag calculation is not considered. This conductor sag calculation is not suitable for the calculation of conductor sag under wildfire conditions. Under wildfire conditions, the conductor temperature rises sharply and the inflection point temperature of steel-core aluminum stranded wire will be exceeded. Moreover, under wildfire conditions, the conductor temperature rises sharply. Since the thermal expansion coefficient of aluminum stranded wire is about twice that of steel core, the expansion of aluminum stranded wire under temperature The temperature of the conductor increases quickly, while the steel core expands slowly. In order to maintain deformation coordination between the steel core and the aluminum stranded wire, the steel core layer applies pressure to the aluminum stranded wire layer, while the aluminum stranded wire layer applies tension to the steel core layer. As a result, the tension borne by the steel core layer increases with the increase of temperature, while the tension borne by the aluminum stranded wire layer decreases with the increase of temperature. When the temperature reaches the inflection point temperature of the conductor, the tension borne by the aluminum stranded wire is zero, that is, the aluminum stranded wire is not under stress, and the steel core bears all the tension. That is, the sag analysis of the conductor before and after the inflection point temperature is different. Therefore, it is urgent to analyze the conductor sag more accurately in combination with the inflection point temperature, accurately monitor the changes in the conductor sag, and take emergency measures in time to maintain the safe and stable operation of the power system. Summary of the invention

[0004] The embodiments of the present invention provide a method, device, terminal equipment and storage medium for monitoring the sag of conductors of overhead transmission lines under wildfire conditions, which can accurately analyze and calculate the sag of conductors of overhead transmission lines under wildfire conditions, accurately monitor the changes in conductor sag, and then when the conductor sag exceeds the ground clearance distance of the current conductor, send an alarm to the operation and maintenance personnel of the overhead transmission line, so that the operation and maintenance personnel can take emergency measures in time to maintain the safe and stable operation of the power system.

[0005] An embodiment of the present invention provides a method for monitoring sag of overhead power transmission line conductors under wildfire conditions, comprising:

[0006] Obtain conductor parameters of an overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters, and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area, and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area, and aluminum stranded wire thermal expansion coefficient;

[0007] The inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length;

[0008] For the average temperature of the conductor at each moment, if the average temperature of the conductor at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the stress of the aluminum stranded wire at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length, the fixed parameters of the steel core and the fixed parameters of the aluminum stranded wire; if the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length and the fixed parameters of the steel core;

[0009] When the conductor sag exceeds the ground clearance of the conductor at any moment, an alarm is sent to the overhead transmission line operation and maintenance personnel.

[0010] Further, the inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the conductor load ratio and the span length, including:

[0011] The inflection point temperature of the overhead transmission line is calculated by the following formula:

[0012]

[0013] Among them, L k is the wire length at time k; L0 is the wire length at the initial time; σ Al,k is the stress of aluminum strand at time k; Al,0 is the stress of aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ k is the total stress of the conductor at time k.

[0014] Furthermore, if the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including:

[0015] If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0016]

[0017] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α Sis the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0018] Furthermore, if the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including:

[0019] If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0020]

[0021] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0022] Based on the above method embodiment, the present invention provides a corresponding device embodiment;

[0023] An embodiment of the present invention provides a conductor sag monitoring device for overhead power transmission lines under wildfire conditions, including: a conductor parameter acquisition module, an inflection point temperature determination module, a conductor sag calculation module and an alarm module;

[0024] The conductor parameter acquisition module is used to acquire conductor parameters of the overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area and aluminum stranded wire thermal expansion coefficient;

[0025] The inflection point temperature determination module is used to calculate the inflection point temperature of the overhead transmission line according to the steel core fixed parameters, the aluminum stranded wire fixed parameters, the steel core stress at the initial moment, the aluminum stranded wire stress at the initial moment, the conductor average temperature at the initial moment, the conductor length at the initial moment, the conductor load ratio and the span length;

[0026] The conductor sag calculation module is used for determining the conductor sag at the current moment according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters for the conductor average temperature at each moment if the conductor average temperature at the current moment is less than the inflection point temperature; if the conductor average temperature at the current moment is not less than the inflection point temperature, determining the conductor sag at the current moment according to the steel core stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length and the steel core fixed parameters;

[0027] The alarm module is used to send an alarm to the overhead power transmission line operation and maintenance personnel when the conductor sag exceeds the ground clearance distance of the conductor at any time.

[0028] Further, the inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the conductor load ratio and the span length, including:

[0029] The inflection point temperature of the overhead transmission line is calculated by the following formula:

[0030]

[0031] Among them, L k is the wire length at time k; L0 is the wire length at the initial time; σ Al,k is the stress of aluminum strand at time k; Al,0 is the stress of aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ kis the total stress of the conductor at time k.

[0032] Furthermore, if the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including:

[0033] If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0034]

[0035] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0036] Furthermore, if the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including:

[0037] If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0038]

[0039] Among them, L j+1 L is the length of the wire at time j+1; jis the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0040] 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, and when the processor executes the computer program, it implements the method for monitoring the sag of overhead transmission line conductors under forest fire conditions described in the above-mentioned embodiment of the invention.

[0041] Another embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the method for monitoring the sag of overhead transmission line conductors under wildfire conditions described in the above-mentioned embodiment of the invention.

[0042] The following beneficial effects are achieved by implementing the present invention:

[0043] The present invention provides a method, device, terminal equipment and storage medium for monitoring the sag of a conductor of an overhead transmission line under wildfire conditions. The conductor sag monitoring method obtains conductor parameters of the overhead transmission line, calculates the inflection point temperature of the overhead transmission line according to the obtained conductor parameters of the overhead transmission line, and is based on the fact that the tension borne by the aluminum stranded wire before the inflection point temperature is not zero, that is, the total stress of the conductor is determined by the stress of the aluminum stranded wire and the stress of the steel core when the tension is less than the inflection point temperature, and the tension borne by the aluminum stranded wire after the inflection point temperature is zero, that is, the total stress of the conductor when the tension is not less than the inflection point temperature is the characteristic of the stress of the aluminum stranded wire at this time. The average temperature of the conductor at each moment and the magnitude of the inflection point temperature are distinguished. For the average temperature of the conductor at each moment, if the average temperature of the conductor at the current moment is less than the inflection point temperature, the stress of the aluminum stranded wire and the stress of the steel core are considered when calculating the sag of the conductor, and if the average temperature of the conductor at the current moment is not less than the inflection point temperature, only the stress of the steel core is considered when calculating the sag of the conductor. By determining the inflection point temperature and comparing the average conductor temperature at each moment with the inflection point temperature, the conductor sag of the overhead transmission line can be accurately analyzed and calculated under forest fire conditions, and the change in conductor sag can be accurately monitored. When the conductor sag exceeds the current conductor's ground clearance distance, an alarm is issued to the overhead transmission line operation and maintenance personnel, allowing them to take emergency measures in a timely manner to maintain the safe and stable operation of the power system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a flow chart of a method for monitoring conductor sag of an overhead transmission line under wildfire conditions provided by one embodiment of the present invention.

[0045] Figure 2 It is a structural schematic diagram of a conductor sag monitoring device for overhead power transmission lines under forest fire conditions provided by one embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0049] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0050] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0051] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0052] In the description of the embodiments of the present application, the term "multiple" refers to more than two (including two). Similarly, "multiple groups" refers to more than two groups (including two groups), and "multiple pieces" refers to more than two pieces (including two pieces).

[0053] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0054] like Figure 1 As shown, a method for monitoring the sag of overhead power transmission line conductors under wildfire conditions is provided in one embodiment of the present invention, comprising:

[0055] Step S1: Obtaining conductor parameters of an overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters, and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area, and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area, and aluminum stranded wire thermal expansion coefficient;

[0056] Step S2: calculating the inflection point temperature of the overhead transmission line according to the steel core fixed parameters, the aluminum stranded wire fixed parameters, the steel core stress at the initial moment, the aluminum stranded wire stress at the initial moment, the conductor average temperature at the initial moment, the conductor length at the initial moment, the conductor load ratio and the span length;

[0057] Step S3: for the average temperature of the conductor at each moment, if the average temperature of the conductor at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the stress of the aluminum stranded wire at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length, the steel core fixed parameters and the fixed parameters of the aluminum stranded wire; if the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length and the steel core fixed parameters;

[0058] Step S4: When the conductor sag exceeds the ground clearance of the conductor at any time, an alarm is issued to the overhead transmission line operation and maintenance personnel.

[0059] For step S1, the conductor parameters of the overhead transmission line are obtained, including the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters; the steel core fixed parameters include: the steel core elastic modulus, the steel core cross-sectional area and the steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: the aluminum stranded wire elastic modulus, the aluminum stranded wire cross-sectional area and the aluminum stranded wire thermal expansion coefficient.

[0060] For step S2, based on the acquisition of the above-mentioned conductor parameters, the inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the steel core stress at the initial moment, the aluminum stranded wire stress at the initial moment, the average conductor temperature at the initial moment, the conductor length at the initial moment, the conductor load ratio and the span length.

[0061] In a preferred embodiment, the inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length, including:

[0062] The inflection point temperature of the overhead transmission line is calculated by the following formula:

[0063]

[0064] Among them, L k is the wire length at time k; L0 is the wire length at the initial time; v Al,k is the stress of aluminum strand at time k; Al,0 is the stress of aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ k is the total stress of the conductor at time k.

[0065] Specifically, to determine the calculation formula for the inflection point temperature of the overhead transmission line, it is necessary to obtain it through the following reasoning.

[0066] First, the span without height difference is analyzed. It is assumed that the conductor sag of the overhead transmission line composed of steel core and aluminum stranded wire before the wildfire is f0. The catenary equation for calculating the conductor sag at the initial moment is simplified and approximated as a parabola equation according to the Maclaurin expansion of the hyperbolic cosine, as shown in formula (2). Further, according to formula (3), the conductor horizontal stress at the initial moment corresponding to the conductor sag at the initial moment, that is, the total conductor stress at the initial moment, can be calculated. According to formula (4), the conductor length at the initial moment corresponding to the conductor sag at the initial moment can be calculated.

[0067]

[0068] Among them, the subscript 0 represents the initial moment, and the conductor temperature must be consistent with the ambient temperature at the initial moment; f0 is the conductor sag at the initial moment; σ0 is the total stress of the conductor at the initial moment; γ is the conductor load ratio; l is the span length; cosh is the hyperbolic cosine function; L0 is the conductor length at the initial moment.

[0069] It should be noted that in a multi-strand conductor containing steel core and aluminum strands, the typical value of creep strain is specified to represent the combined effect of settlement and deformation of the steel core aluminum strands, high tension load events, and elongation caused by continuous daily tension during overhead operation. Since the creep of the steel core wire is usually negligible, the overall creep is borne by the aluminum strands, which will cause the stress ratio of the aluminum strands to decrease and the stress ratio of the steel core to increase. At the same time, the overall tension of the conductor decreases, while the overall deformation, i.e., sag, increases. Therefore, long-term creep strain will affect the operating state of the conductor and the stress distribution between the steel core and aluminum wire layers. Due to the influence of initial creep, the stress distribution of the steel core aluminum strand is not completely determined by the ratio of the elastic modulus, so it needs to be calculated separately. This calculation is determined by GB 50545-2010, which stipulates that the creep strain elongation of the conductor after erection should be determined according to the data provided by the manufacturer or test.

[0070] The horizontal stress of the conductor is borne by the steel core and the aluminum stranded wire, and the overall strain of the two is always consistent. Formula (5) is the conductor stress formula, and formula (6) is the conductor strain formula.

[0071] σ0=σ Al,0 +σ S,0 (5)

[0072] ε0=ε Al,0 +ε C =ε S,0 (6)

[0073] Among them, ε0 represents the total strain of the wire at the initial moment; ε C represents creep plastic elongation; ε Al,0 represents the strain of the aluminum strand at the initial moment; ε S,0 Represents the steel core strain at the initial moment.

[0074] According to the theory of classical material mechanics and thermodynamics, considering the elastic deformation, thermal expansion and long-term creep strain of metal materials, formula (6) can be rewritten as shown in the following formula (7):

[0075]

[0076] Among them, T ref It is the reference temperature, generally taken as 15℃.

[0077] Based on this, the stress distribution of steel core and aluminum stranded wire considering long-term creep strain can be calculated, which is the basis for calculating the sag after uneven temperature rise of the conductor under wildfire conditions.

[0078] Under wildfire conditions, the temperature of the conductor rises sharply. Since the thermal expansion coefficient of the aluminum stranded wire is about twice that of the steel core, the aluminum stranded wire expands quickly under the action of temperature, while the steel core expands slowly. In order to maintain deformation coordination between the steel core and the aluminum stranded wire, the steel core layer applies pressure to the aluminum stranded wire layer, while the aluminum stranded wire layer applies tension to the steel core layer; thus, the tension borne by the steel core layer increases with the increase in temperature, while the tension borne by the aluminum stranded wire layer decreases with the increase in temperature. When the temperature reaches a certain critical temperature, that is, the inflection point temperature of the conductor, the tension borne by the aluminum stranded wire is zero, that is, the aluminum part is not subjected to force, and the steel core bears all the tension. After the inflection point temperature, the overall mechanical properties of the conductor are borne only by the steel core, which is reflected as a decrease in the thermal expansion coefficient and an increase in the elastic modulus, thus showing the characteristics of high temperature and low sag. Therefore, the stress of the aluminum stranded wire can be set as 0 as the judgment condition for whether the inflection point temperature has been reached.

[0079] In order to obtain the inflection point temperature of the sag considering the uneven temperature rise of the conductor under wildfire conditions, the conductor needs to be divided into n sections by length, and the temperature of each section of the conductor is monitored by a wildfire monitoring device, and then the average temperature of the conductor is calculated based on the temperature of the n sections of the conductor. Assuming that the conductor reaches the inflection point temperature at time k, the average temperature of the conductor is Then the thermodynamic and mechanical processes related to the average temperature of the conductor can be obtained as shown in formula (8).

[0080]

[0081] Among them, T i,k represents the temperature of the i-th conductor at time k; T i,0 represents the temperature of the i-th conductor at the initial moment; represents the average temperature of the conductor at time k; Represents the average temperature of the conductor at the initial moment.

[0082] According to formula (5), ignoring the high temperature creep during the conductor temperature rise process, the steel core and aluminum stranded wire have the same elastic strain and thermal expansion process, then the last expression of formula (8) can be rewritten as shown in formula (9).

[0083]

[0084] Based on formula (4) and formula (5), the calculation formula for the wire length and the calculation formula for the total wire stress at the time when the inflection point temperature is reached, i.e., at time k, can be obtained, as shown in formula (10) and formula (11), respectively.

[0085]

[0086] σ k =σ Al,k +σ S,k (11)

[0087] It should be noted that when the inflection point temperature is reached, the stress σ of the aluminum strand Al,k =0, based on this, by solving formula (9), formula (10) and formula (11) together, we can get formula (1), and then combine the stress σ of aluminum stranded wire Al,k = 0, the average temperature of the conductor corresponding to the inflection point temperature can be obtained, that is, the average temperature of the conductor at time k The temperature This is also called the inflection point temperature.

[0088] For step S3, when determining the inflection point temperature Based on the inflection point temperature As the dividing line, if the average temperature of the conductor at the current moment is lower than the inflection point temperature, the steel core and the aluminum stranded wire maintain the same strain for thermal expansion, then the corresponding conductor sag is determined by the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average temperature of the conductor at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters; if the average temperature of the conductor at the current moment is not lower than the inflection point temperature, it is determined according to the steel core stress at each moment, the average temperature of the conductor at each moment, the conductor length at each moment, the conductor load ratio, the span length and the steel core fixed parameters.

[0089] In a preferred embodiment, if the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including:

[0090] If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0091]

[0092] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0093] If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the tension on the aluminum stranded wire is zero, that is, the aluminum stranded wire is not under stress, and the steel core bears all the tension. The corresponding conductor sag is determined by the steel core stress at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the conductor load ratio, the span length, and the fixed parameters of the steel core.

[0094] In a preferred embodiment, if the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including:

[0095] If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0096]

[0097] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0098] For step S4, when the conductor sag calculated at any moment exceeds the ground clearance distance of the current conductor, that is, the conductor of the overhead transmission line is in a suspended state, and the vertical distance from its lowest point (i.e., the maximum sag point) to the ground is less than the specified safety distance, it is necessary to send an alarm message to the operation and maintenance personnel of the overhead transmission line of the power system in the form of text messages, voice alarms, etc., so as to notify the operation and maintenance personnel to take corresponding emergency measures in time to maintain the safe and stable operation of the power system.

[0099] Based on the above method embodiment, the present invention provides a corresponding device embodiment.

[0100] like Figure 2 As shown, an embodiment of the present invention provides a conductor sag monitoring device for overhead power transmission lines under wildfire conditions, including: a conductor parameter acquisition module, an inflection point temperature determination module, a conductor sag calculation module and an alarm module;

[0101] The conductor parameter acquisition module is used to acquire conductor parameters of the overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area and aluminum stranded wire thermal expansion coefficient;

[0102] The inflection point temperature determination module is used to calculate the inflection point temperature of the overhead transmission line according to the steel core fixed parameters, the aluminum stranded wire fixed parameters, the steel core stress at the initial moment, the aluminum stranded wire stress at the initial moment, the conductor average temperature at the initial moment, the conductor length at the initial moment, the conductor load ratio and the span length;

[0103] The conductor sag calculation module is used for determining the conductor sag at the current moment according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters for the conductor average temperature at each moment if the conductor average temperature at the current moment is less than the inflection point temperature; if the conductor average temperature at the current moment is not less than the inflection point temperature, determining the conductor sag at the current moment according to the steel core stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length and the steel core fixed parameters;

[0104] The alarm module is used to send an alarm to the overhead power transmission line operation and maintenance personnel when the conductor sag exceeds the ground clearance distance of the conductor at any time.

[0105] In a preferred embodiment, the inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length, including:

[0106] The inflection point temperature of the overhead transmission line is calculated by the following formula:

[0107]

[0108] Among them, L k is the wire length at time k; L0 is the wire length at the initial time; σ Al,k is the stress of aluminum strand at time k; Al,0 is the stress of aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ k is the total stress of the conductor at time k.

[0109] In a preferred embodiment, if the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including:

[0110] If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0111]

[0112] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Alis the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0113] In a preferred embodiment, if the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including:

[0114] If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula:

[0115]

[0116] Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

[0117] It should be noted that the device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the scheme of this embodiment. In addition, in the accompanying drawings of the device embodiments provided by the present invention, the connection relationship between the modules indicates that there is a communication connection between them, which may be specifically implemented as one or more communication buses or signal lines. A person of ordinary skill in the art may understand and implement it without paying any creative effort.

[0118] Those skilled in the art can clearly understand that for the sake of convenience and brevity, the specific working process of the device described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0119] Based on the above method item embodiments, the present invention provides corresponding terminal device item embodiments.

[0120] An 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, a method for monitoring the sag of overhead transmission line conductors under forest fire conditions as described in any one of the present invention is implemented.

[0121] The terminal device may be a computing device such as a desktop computer, a notebook, a PDA, a cloud server, etc. The terminal device may include, but is not limited to, a processor and a memory.

[0122] The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor, etc. The processor is the control center of the terminal device, and uses various interfaces and lines to connect various parts of the entire terminal device.

[0123] The memory can be used to store the computer program, and the processor realizes various functions of the terminal device by running or executing the computer program stored in the memory and calling the data stored in the memory. The memory can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, at least one application required for a function, etc.; the data storage area can store data created according to the use of the mobile phone, etc. In addition, the memory can include a high-speed random access memory, and can also include a non-volatile memory, such as a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Med ia Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk storage device, a flash memory device, or other volatile solid-state storage devices.

[0124] Based on the above method item embodiments, the present invention provides a corresponding storage medium item embodiment.

[0125] An embodiment of the present invention provides a storage medium, which includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute a method for monitoring the sag of overhead transmission line conductors under wildfire conditions as described in any one of the present inventions.

[0126] The storage medium is a computer-readable storage medium, and the computer program is stored in the computer-readable storage medium. When the computer program is executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may include: any entity or device capable of carrying the computer program code, recording medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electric carrier signal, telecommunication signal and software distribution medium.

[0127] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A method for monitoring the sag of overhead power transmission line conductors under wildfire conditions, characterized in that: include: Obtain conductor parameters of an overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters, and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area, and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area, and aluminum stranded wire thermal expansion coefficient; The inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length; For the average temperature of the conductor at each moment, if the average temperature of the conductor at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the stress of the aluminum stranded wire at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length, the fixed parameters of the steel core and the fixed parameters of the aluminum stranded wire; if the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the stress of the steel core at each moment, the average temperature of the conductor at each moment, the length of the conductor at each moment, the specific load of the conductor, the span length and the fixed parameters of the steel core; When the conductor sag exceeds the ground clearance of the conductor at any moment, an alarm is sent to the overhead transmission line operation and maintenance personnel.

2. A method for monitoring sag of overhead power line conductors under wildfire conditions as claimed in claim 1, characterized in that: The inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length, including: The inflection point temperature of the overhead transmission line is calculated by the following formula: Among them, L k is the wire length at time k; L0 is the wire length at the initial time; σ Al,k is the stress of aluminum strand at time k; Al,0 is the stress of aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ k is the total stress of the conductor at time k.

3. The method for monitoring sag of overhead power line conductors under wildfire conditions as claimed in claim 1, characterized in that: If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including: If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula: Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

4. The method for monitoring sag of overhead power line conductors under wildfire conditions according to claim 1, characterized in that: If the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including: If the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula: Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

5. A device for monitoring the sag of overhead power transmission line conductors under wildfire conditions, characterized in that: include: Conductor parameter acquisition module, inflection point temperature determination module, conductor sag calculation module and alarm module; The conductor parameter acquisition module is used to acquire conductor parameters of the overhead transmission line; wherein the conductor parameters include steel core stress at each moment, aluminum stranded wire stress at each moment, average conductor temperature at each moment, conductor length at each moment, conductor load ratio, span length, steel core fixed parameters and aluminum stranded wire fixed parameters; the steel core fixed parameters include: steel core elastic modulus, steel core cross-sectional area and steel core thermal expansion coefficient; the aluminum stranded wire fixed parameters include: aluminum stranded wire elastic modulus, aluminum stranded wire cross-sectional area and aluminum stranded wire thermal expansion coefficient; The inflection point temperature determination module is used to calculate the inflection point temperature of the overhead transmission line according to the steel core fixed parameters, the aluminum stranded wire fixed parameters, the steel core stress at the initial moment, the aluminum stranded wire stress at the initial moment, the conductor average temperature at the initial moment, the conductor length at the initial moment, the conductor load ratio and the span length; The conductor sag calculation module is used for determining the conductor sag at the current moment according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters for the conductor average temperature at each moment if the conductor average temperature at the current moment is less than the inflection point temperature; if the conductor average temperature at the current moment is not less than the inflection point temperature, determining the conductor sag at the current moment according to the steel core stress at each moment, the conductor average temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length and the steel core fixed parameters; The alarm module is used to send an alarm to the overhead power transmission line operation and maintenance personnel when the conductor sag exceeds the ground clearance distance of the conductor at any time.

6. The device for monitoring the sag of overhead power line conductors under wildfire conditions as claimed in claim 5, characterized in that: The inflection point temperature of the overhead transmission line is calculated according to the fixed parameters of the steel core, the fixed parameters of the aluminum stranded wire, the stress of the steel core at the initial moment, the stress of the aluminum stranded wire at the initial moment, the average temperature of the conductor at the initial moment, the length of the conductor at the initial moment, the specific load of the conductor and the span length, including: The inflection point temperature of the overhead transmission line is calculated by the following formula: Among them, L k is the wire length at time k; L0 is the wire length at the initial time; σ Al,k is the stress of aluminum strand at time k; Al,0 is the stress of the aluminum strand at the initial moment; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the inflection point temperature; is the average temperature of the conductor at the initial moment; σ S,k is the steel core stress at time k; σ S,0 is the steel core stress at the initial moment; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ k is the total stress of the conductor at time k.

7. The device for monitoring the sag of overhead power line conductors under wildfire conditions as claimed in claim 5, characterized in that: If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the aluminum stranded wire stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, the steel core fixed parameters and the aluminum stranded wire fixed parameters, including: If the average conductor temperature at the current moment is less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula: Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; Al,j is the stress of aluminum strand at time j; E Al is the elastic modulus of aluminum stranded wire; S Al is the cross-sectional area of ​​the aluminum stranded wire; α Al is the thermal expansion coefficient of aluminum stranded wire; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

8. The device for monitoring the sag of overhead power line conductors under wildfire conditions as claimed in claim 5, characterized in that: If the average conductor temperature at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is determined according to the steel core stress at each moment, the average conductor temperature at each moment, the conductor length at each moment, the conductor load ratio, the span length, and the steel core fixed parameters, including: If the average temperature of the conductor at the current moment is not less than the inflection point temperature, the conductor sag at the current moment is calculated using the following formula: Among them, L j+1 L is the length of the wire at time j+1; j is the wire length at time j; L0 is the wire length at the initial time; σ Al,j+1 is the stress of aluminum strand at time j+1; is the average temperature of the conductor at time j+1; is the average temperature of the conductor at time j; σ S,j+1 is the steel core stress at time j+1; σ S,j is the steel core stress at time j; E S is the elastic modulus of the steel core; S S is the cross-sectional area of ​​the steel core; α S is the thermal expansion coefficient of the steel core; l is the span length; γ is the conductor load ratio; σ j+1 is the total stress of the conductor at time j+1; Represents the conductor sag at time j+1.

9. A terminal device, characterized in that: It comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein when the processor executes the computer program, it implements a method for monitoring the sag of overhead power line conductors under wildfire conditions as described in any one of claims 1 to 4.

10. A storage medium, characterized in that: The storage medium includes a stored computer program, wherein when the computer program is running, the device where the storage medium is located is controlled to execute the method for monitoring the sag of overhead power line conductors under wildfire conditions as described in any one of claims 1 to 4.

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