A reliability analysis method and system for conductors in transmission lines

Abstract

The present invention provides a reliability analysis method and system for conductors in transmission lines, including: calculating the horizontal tension and horizontal tension increment of the conductor based on the acquired basic variables; calculating the tension at any point of the conductor based on the horizontal tension and horizontal tension increment; obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation; the basic variables include: conductor load, initial sag and temperature change amplitude. When analyzing the reliability of the conductor of a transmission line, the present invention takes into account the conductor load in the transmission line, i.e., geometric nonlinearity, and the influence of ambient temperature changes on the internal force and deformation of the conductor, which can significantly improve the accuracy and precision of the reliability calculation of the conductor of the transmission line, improve the ability of the transmission line to resist disasters from the design link, and enhance the ability of the transmission line to resist natural disasters, which has very important practical significance for the safe and economical operation of the transmission line.

Description

Technical Field

[0001] The present invention relates to the field of power transmission lines, and in particular to a reliability analysis method and system for conductors in power transmission lines. Background Art

[0002] As an important part of the transmission line system, the safety and reliability of the conductor (ground) wire is an important guarantee for the long-distance transmission of electric energy. The conductor (ground) wire is a typical suspension cable structure, and the catenary formula should be used to solve the reliability. However, due to the complexity of the catenary formula, when solving the reliability of the transmission line conductor (ground) wire, only the variability of the conductor under ice and wind loads is considered, and the calculation is simply approximated as an axial tension member, and only the reliability contained in the single safety factor K of the conductor (ground) wire design is calculated. Due to the limitations of the single safety factor method, the existing reliability analysis is inaccurate. Summary of the invention

[0003] In order to solve the problem of inaccurate reliability analysis in the prior art, the present invention provides a reliability analysis method and system for conductors in a transmission line. On the basis of considering the geometric deformation characteristics of the conductor (ground) wire of the transmission line, the influence of the ambient temperature on the deformation and stress of the conductor (ground) wire is also considered, and a reliability analysis model of the conductor (ground) wire of the transmission line is established, thereby analyzing and determining the reliability of the conductor (ground) wire of the transmission line. The method provided by the present invention can significantly improve the accuracy and precision of the reliability calculation of the conductor (ground) wire of the transmission line, improve the ability of the transmission line to resist disasters from the design link, ensure the safe and stable operation of the transmission line under severe meteorological conditions such as rain, snow, and freezing, and enhance the ability of the transmission line to resist natural disasters, which has very important economic value and practical significance for the safe and economical operation of the transmission line.

[0004] The present invention provides a reliability analysis method for a conductor in a power transmission line, comprising: calculating the horizontal tension and the horizontal tension increment of the conductor based on the acquired basic variables; calculating the tension at any point of the conductor based on the horizontal tension and the horizontal tension increment; obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation;

[0005] The basic variables include: conductor load, initial sag and temperature change amplitude.

[0006] Compared with the prior art, the present invention has the following beneficial effects:

[0007] The technical solution provided by the present invention calculates the horizontal tension and the horizontal tension increment of the conductor based on the obtained basic variables; calculates the tension at any point of the conductor based on the horizontal tension and the horizontal tension increment; obtains the reliability of the conductor based on the tension and the pre-constructed limit state equation; when analyzing the reliability of the conductor of the transmission line, the conductor load in the transmission line, that is, the geometric nonlinearity of the conductor, and the influence of the ambient temperature change on the internal force and deformation of the conductor are considered, which can significantly improve the accuracy and precision of the reliability calculation of the conductor of the transmission line, improve the ability of the transmission line to resist disasters from the design link, ensure the safe and stable operation of the transmission line under severe meteorological conditions such as rain, snow, and freezing, and enhance the ability of the transmission line to resist natural disasters, which has very important economic value and practical significance for the safe and economical operation of the transmission line.

[0008] The technical solution provided by the present invention uses the established limit state equation of the transmission line to analyze the reliability, takes into account the material properties of the line and the discreteness of various loads or effects acting on the line, and improves the accuracy of the reliability.

[0009] In the technical solution provided by the present invention, the reliability index of the analysis is directly expressed by the statistical parameters of the basic variables, which is simple to calculate and convenient for practical application. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A flow chart of a reliability analysis method for a conductor in a power transmission line according to the present invention;

[0011] Figure 2 It is a schematic diagram of deformation of a conductor subjected to a uniformly distributed load along the length of the conductor in an embodiment of the present invention;

[0012] Figure 3 It is a schematic diagram of deformation of a conductor subjected to a uniformly distributed load in the span direction in an embodiment of the present invention;

[0013] Figure 4 Schematic diagram of the difference in deformation and internal force between a catenary and a parabola in an embodiment of the present invention;

[0014] Figure 5 Schematic diagram of the variation trend of the tension increment h of the transmission wire under different temperature differences Δt in an embodiment of the present invention;

[0015] Figure 6 Schematic diagram of the variation trend of the sag increment w of the transmission line under different temperature differences Δt in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the accompanying drawings and examples.

[0017] Embodiment 1:

[0018] At present, the research on the reliability of power transmission line conductors (ground wires) all considers the conductors (ground wires) as approximately axial tension components, and does not consider the influence of the geometric nonlinearity of the conductors (ground wires) on the deformation and internal forces of the conductors (ground wires). The present invention first studies the deformation and internal forces of the power transmission line conductors (ground wires) under ice and wind loads according to the parabolic equation, and then uses a primary reliability analysis method to analyze the reliability of the power transmission line conductors (ground wires) under the combination of self-weight, ice load, wind load and temperature. Figure 1 As shown, the present invention provides a reliability analysis method for a conductor in a transmission line, comprising:

[0019] Step S1, calculating the horizontal tension and horizontal tension increment of the conductor based on the acquired basic variables;

[0020] Step S2, calculating the tension at any point of the wire based on the horizontal tension and the horizontal tension increment;

[0021] Step S3, obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation;

[0022] The basic variables include: conductor load, initial sag and temperature change amplitude.

[0023] The specific content of the invention is as follows:

[0024] Step S1, calculating the horizontal tension and horizontal tension increment of the conductor based on the acquired basic variables, specifically comprising:

[0025] (1) Establish Figure 2 The coordinate system shown in Figure 1 takes into account the geometric nonlinearity of the transmission line conductor (ground line). The catenary formula of the gravity load g acting along the conductor (ground line) is shown in formula (1). According to the coordinates of the calculation point, the internal force at any point of the conductor (ground line) can be determined according to formula (1):

[0026]

[0027] when z=f, the horizontal component H of the conductor (ground line) can be calculated according to formula (2):

[0028]

[0029] In the formula: z: the component of the conductor in the vertical direction; x: the horizontal coordinate of the conductor; l: the span of the conductor; f: the initial sag of the conductor; H: the horizontal tension of the conductor; g: the gravity load of the conductor; h: the horizontal tension increment.

[0030] Since the catenary equation and the equations derived from it all involve hyperbolic functions, that is, these equations are transcendental equations about related variables, their calculations are very complicated. Figure 3As shown, the present invention adopts the parabolic equation of the uniformly distributed load acting along the span direction of the conductor, that is, the external load q instead. The parabolic equation of the transmission line conductor (ground) is shown in formula (3):

[0031]

[0032] The horizontal component force H can be calculated according to formula (4):

[0033]

[0034] In the formula: z: the component of force on the conductor in the vertical direction; x: the horizontal coordinate of the conductor.

[0035] When the midpoint deflection f of the catenary and the parabola is equal, the deformation difference and horizontal force difference of each point are calculated according to the catenary and the parabola respectively: ΔH=H c -H p (H c , H p are the horizontal components of the transmission line calculated according to the catenary and parabola, respectively. The results are shown in Tables 1 and Figure 4 shown.

[0036] Table 1 Maximum differences in deformation and horizontal force calculated for catenary and parabola

[0037] f / l 0.05 0.1 0.15 0.2 0.25 0.30 δ / f 0.08％ 0.32％ 0.70％ 1.19％ 1.75％ 2.37％ ΔH / gl 0.83％ 1.63％ 2.39％ 3.09％ 3.72％ 4.28％

[0038] It can be seen from Table 1 that the difference between the two methods is relatively small, whether it is deformation or the horizontal component of conductor tension. The smaller the sag of the conductor, the smaller the difference. When the length of the suspension cable is slightly larger than the span, the parabola formula with relatively simple calculation can be used to replace the catenary formula with higher nonlinearity. In actual engineering, since the conductor (ground) wire is always relatively flat, if the actual load distribution is regarded as horizontal distribution, the error caused by this is very small.

[0039] (2) The length and internal force of the transmission line conductor (ground wire) are greatly affected by the ambient temperature. The present invention can take the influence of the ambient temperature into consideration.

[0040] When the ambient temperature change is taken into account, the dimensionless form h of the horizontal component force increment of the conductor (ground) wire under the combined effect of the external uniformly distributed load q and temperature can be calculated according to formula (5).

[0041]

[0042] Where h = h / H, q = q / g L e ≈l[1+8(f / l) 2 ], L t =l[1+16(f / l) 2 / 3];

[0043] Where α is the temperature linear expansion coefficient of the conductor (ground); Δt is the temperature change amplitude; E S is the elastic modulus of the wire; λ: the first intermediate parameter; L e : The second intermediate parameter; L t : The third intermediate parameter; q: dimensionless external load; q is the external load; A is the cross-sectional area of ​​the conductor (ground); h: dimensionless horizontal tension increment; h: horizontal tension increment.

[0044] The first intermediate parameter λ is calculated as follows:

[0045]

[0046] From this, the dimensionless form w of the sag increment at the midpoint of the transmission line conductor (ground wire) under external load can be further obtained:

[0047]

[0048] Where w = w / (ql 2 / H), w is the sag increment.

[0049] Under the action of load g+q, the geometric nonlinearity of the conductor is mainly reflected by w:

[0050] ① At a given initial sag, i.e., intermediate deflection f, the initial tension H of the conductor under its own gravity is calculated by formula (4);

[0051] ② Due to the obvious geometric nonlinearity, the external load q is generally loaded in stages. Under the first level of external load, according to the initial sag f and initial tension H under the gravity load g, the horizontal tension increment h of the conductor under the first level of external load is calculated by formula (5);

[0052] ③ The sag increment w of the conductor under the first level load is calculated by formula (7). The geometric deformation of the conductor changes. The sag increment w is incorporated into the total deflection f, and the initial horizontal tension H is recalculated;

[0053] ④ According to the gravity load g and the sag f under the first level external load q (including the sag increment w under the first level external load) and the horizontal tension H (including the horizontal tension increment h under the first level external load), repeat steps ② and ③ until all levels of external loads q are loaded, and the final sag increment w and horizontal tension increment h are obtained.

[0054] By cyclically incorporating the sag increments w under all external loads into the initial sag f, the accuracy of the initial tension H is improved, and the accuracy of the reliability is further improved.

[0055] When the ambient temperature change is not considered, that is, Δt = 0, the dimensionless form h (see formula (5)) of the horizontal component force increment of the transmission line conductor (ground) under the action of the external load q can be simplified.

[0056] Step S2, calculating the tension at any point of the wire based on the horizontal tension and the horizontal tension increment, comprising:

[0057] According to the parabolic calculation formula of the transmission line conductor (ground) line tension and considering its geometric nonlinearity, the limit state equation of the transmission line conductor (ground) line is established, and the reliability of the transmission line conductor (ground) line is calculated using the currently more mature primary reliability analysis method.

[0058] The Cardano method is used to solve the above cubic equation (5) to obtain the horizontal component of the conductor (ground) tension. The tension T at any point of the transmission conductor (ground) with equal heights at both ends can be calculated as follows:

[0059]

[0060] when Conductor (ground) wire tension T = H + h.

[0061] From this, the limit state equation of any point in the cable structure can be established as:

[0062] Z = g(x i )=RS=f y AT=0 (9)

[0063] This method can be used not only for reliability calculation of power transmission lines (ground lines), but also for reliability calculation of cable suspension structures or cable membrane structures.

[0064] According to the parabolic calculation formula of the transmission line conductor (ground) tension, considering its geometric nonlinearity, the conductor (ground) tension is calculated, and the limit state equation of the transmission line conductor (ground) is established. The reliability of the transmission line conductor (ground) is calculated using the more mature primary reliability analysis method.

[0065] Solution of Geometric Nonlinear Problems

[0066] Step S3, obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation, comprises:

[0067] Determine the performance function Z for each basic random variable x i The reaction gradient can be used to calculate the reliability of the transmission conductor (ground) line using the classical first-order second-order method (FOSM).

[0068] With the basic variable f y 、E S , A, qw ,q i The average value of g and the value of the midpoint deflection f in the initial state are taken as the initial verification point x * , x * Substituting into formulas (4), (5), (7) and (9), the initial tension H, tension increment h, sag f and sag increment w of the conductor (ground wire) are calculated by geometric nonlinear analysis. is the limit state equation Z = g(x i )=0, then

[0069] g(x * )=0 (10)

[0070] Calculate the function g(x * ) With respect to the partial derivatives of each basic variable, the structural reliability index β is calculated by the verification point method as follows:

[0071]

[0072] Calculate the sensitivity coefficient of the basic variable xi:

[0073]

[0074] According to the iterative principle of the verification point method, the new verification point x is obtained. * for:

[0075]

[0076] Calculate by iterative method until the two vectors ‖x * The difference between ‖ and ﹤the allowable error ε is finally calculated to obtain the corresponding reliability index and failure probability.

[0077] In this embodiment, the calculation formula for the line length and additional tension of the transmission line (ground line) under the influence of ambient temperature is deduced, and the influence of different ambient temperatures on the line length and internal force of the transmission line (ground line) is calculated and analyzed in combination with engineering examples.

[0078] This embodiment takes an overhead transmission line with a span of l = 300m, equal height at both ends, and a voltage level of 330kV as an example to analyze the influence of different ambient temperatures on the length and internal force of the transmission conductor (ground) line. The steel core aluminum stranded wire JL-G1A240 / 30 is used, and its unit length gravity is g = 9.04N / m, the cross-sectional diameter is d = 21.6mm, and the cross-sectional area is A = 275.96mm. 2 , conductor elastic modulus E S =73000N / mm 2 , linear expansion coefficient α = 1.96·10 -5 / ℃. Assuming that the midpoint deflection caused by gravity is f = 7.5m, the uniformly distributed load q includes wind load and ice load, and the wind load on the transmission line is q w =7.21N / m, the ice load is q i =23.07N / m. The initial horizontal tension of the transmission line under the action of its own weight is obtained by formula (4) = 13.560kN; considering the influence of wind deflection, the initial horizontal tension of the transmission line under the action of its own weight is H = 13.216kN. Further, the tension increment h and sag increment w of the transmission line under external load and different temperature difference Δt are obtained by formula (5) to formula (7) as shown in Table 2.

[0079] If the tension increment h and sag increment w at temperature difference Δt=0 are taken as the benchmark, Table 2 also shows the variation range of the tension increment h and sag increment w at other temperature differences compared with the tension increment h and sag increment w at temperature difference Δt=0.

[0080] like Figure 5 and Figure 6 As shown in Figure 2, the changes in the tension increment h and sag increment w of the transmission line under different temperature differences.

[0081] Table 2 Tension increment h and sag increment w of transmission line under external load and different temperature difference Δt

[0082]

[0083] The results under different temperature change ranges show that in extreme climates, the temperature drop will cause the conductor to shrink and the tension inside the conductor to increase; when the conductor is covered with ice to a certain extent, the tension of the conductor will reach or even exceed the comprehensive breaking force.

[0084] The traditional reliability calculation of transmission line conductors (ground lines) is based only on the provisions of current relevant specifications, and the following limit state equation is established:

[0085] Z=R k -KS k =0 (14)

[0086] Where K is the safety factor of the transmission line conductor (ground) wire. k , S k They are respectively the standard values ​​of resistance and load of the transmission line conductor (ground) wire.

[0087] When calculating the reliability of the conductor (ground line) according to formula (14), the calculation result of the reliability index is different from the load standard value S k The value of S is irrelevant and can be given arbitrarily k Then, according to the limit state equation (14), considering the safety factor K of the transmission line conductor (ground wire) specified in the current specification, the resistance value R of the conductor (ground wire) is calculated. k, and then consider the statistical characteristics of resistance and load effect respectively, and use the primary reliability analysis method to calculate the reliability of the conductor (ground) line. In the reliability calculation, the reliability index cannot be calculated for a specific conductor (ground) line, and in the calculation, due to the geometric nonlinear characteristics of the transmission conductor (ground) line, the statistical characteristics of the load are used to approximate the statistical characteristics of the load effect, and the resulting calculation error is also relatively large.

[0088] In the present invention, the reliability of the conductor (ground) line is calculated according to the limit state equation (9). First, the statistical parameters of the corresponding variables are substituted into the equation (4) to calculate the initial horizontal tension H of the conductor (ground) line under the deadweight g of the structure; then, the Cardano method is used to solve the cubic equation of one variable, and the tension increment h of the conductor (ground) line under the external load q is calculated by the equation (5); secondly, the tension T of any point of the transmission conductor (ground) line with equal height at both ends is calculated by the equation (8); finally, the tension T of the conductor (ground) line is substituted into the limit state equation (9), and the reliability of the conductor (ground) line is calculated by the primary reliability analysis method.

[0089] Taking the overhead transmission line in this embodiment as an example, it is verified that the reliability analysis of the transmission line provided by the present invention is accurate and reliable. The statistical characteristics of each basic variable are shown in Table 3. Other variables, such as the span l of the conductor, the midpoint deflection f, and the conductor elastic modulus E S Consider them as fixed values, that is, the randomness of these variables is not taken into account.

[0090] Table 3 Statistical characteristics of basic variables

[0091]

[0092] According to the statistical characteristics of the above basic variables, considering the geometric nonlinear characteristics of the transmission line, the internal force of the midpoint section of the line is calculated by equations (5) to (8), and then the reliability of the transmission line under different temperature differences Δt is calculated by the limit state equation (9). The calculation results are shown in Table 4. Table 4 also gives the actual safety factor Kc of the transmission line under different temperature differences Δt.

[0093] Since the geometric nonlinearity of the transmission line is taken into account in the reliability calculation, the nonlinearity of the limit state equation of the transmission line is relatively high. In order to verify the accuracy of the calculation results of the present invention, the present invention uses the optimized Monte-Carlo method to simulate the reliability of the transmission line when the temperature difference is 0°C, and the calculation results are also listed in Table 4. The results show that the reliability index of the transmission line obtained by the present invention is very different from the calculation results of the optimized Monte-Carlo method simulation, and the difference between the two results is smaller as the number of simulations increases. Therefore, it can be considered that the reliability index of the transmission line obtained by the present invention using the primary reliability analysis method is accurate and reliable.

[0094] Table 4 Reliability index β of transmission lines calculated by different methods and corresponding failure probability p f

[0095]

[0096] When calculating according to the limit state equation (14), it is not convenient to consider the influence of temperature difference. In order to compare with the calculation results of the present invention, the safety factor Kc of the transmission line when the temperature difference effect Δt=0 is taken as Kc=2.014, and the reliability of the transmission line is calculated according to the limit state equation (14). The calculation results are shown in Table 4. It can be seen from the calculation results in Table 4 that the reliability of the transmission line calculated according to the limit state equation (14) is much lower than the calculation result according to the limit state equation (9) under the same safety factor Kc, that is, the reliability of the structure estimated by the original calculation method is conservative.

[0097] Example 2

[0098] Based on the same inventive concept, the present invention also provides a reliability analysis system for conductors in a transmission line, comprising:

[0099] A first calculation module, used for calculating the horizontal tension and the horizontal tension increment of the conductor based on the acquired basic variables;

[0100] A second calculation module, used for calculating the tension at any point of the wire based on the horizontal tension and the horizontal tension increment;

[0101] A third calculation module, used for obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation;

[0102] The basic variables include: conductor load, initial sag and temperature change amplitude.

[0103] In an embodiment, the first calculation module includes:

[0104] A first calculation unit is used to obtain the horizontal tension of the wire under the gravity load based on the acquired gravity load and initial sag of the wire;

[0105] A second calculation unit is used to calculate the dimensionless increment of the horizontal tension of the conductor under the current external load based on the initial sag, the temperature change amplitude and the horizontal tension, and obtain the dimensionless increment of the sag at the midpoint of the conductor under the current external load based on the dimensionless increment of the horizontal tension and the current external load;

[0106] An updating unit, configured to update the initial sag based on the sag increment and recalculate the horizontal tension of the conductor under the gravity load;

[0107] A result unit, used for judging whether all external loads have been loaded. If all external loads have been loaded, the loop is terminated, and the current horizontal tension and horizontal tension increment are obtained based on the dimensionless value of the horizontal tension increment. Otherwise, the external load is updated and the second calculation unit is executed;

[0108] Among them, the conductor load includes: gravity load and external load.

[0109] Obviously, the described embodiments are only some embodiments of the present invention, but not all 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.

[0110] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application may adopt the form of a computer program product implemented in one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) that include computer-usable program code.

[0111] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0112] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0114] The above are merely embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention to be approved.

Claims

1. A reliability analysis method for conductors in a transmission line, characterized in that: include: Calculate the horizontal tension and horizontal tension increment of the conductor based on the obtained basic variables; Calculate the tension at any point of the wire based on the horizontal tension and the horizontal tension increment; Obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation; The basic variables include: conductor load, initial sag and temperature change amplitude; The method of calculating the horizontal tension and the horizontal tension increment of the conductor based on the acquired basic variables includes: S101, based on the acquired wire gravity load and initial sag, obtaining the horizontal tension of the wire under the gravity load; S102, calculating the dimensionless increment of the horizontal tension of the conductor under the current external load based on the initial sag, the temperature change amplitude and the horizontal tension, and obtaining the dimensionless increment of the sag at the midpoint of the conductor under the current external load based on the dimensionless increment of the horizontal tension and the current external load; S103, updating the initial sag based on the sag increment, and recalculating the horizontal tension of the wire under the gravity load; S104, judging whether all external loads have been loaded, if all external loads have been loaded, ending the loop, and obtaining the current horizontal tension and horizontal tension increment based on the dimensionless value of the horizontal tension increment, otherwise updating the external loads and executing S102; Among them, the conductor load includes: gravity load and external load; The dimensionless horizontal tension increment is calculated as follows: Where: h: dimensionless horizontal tension increment; λ: first intermediate parameter; E S : elastic modulus of the conductor; A: cross-sectional area of ​​the conductor; H: horizontal tension; L e : The second intermediate parameter; α: The expansion coefficient of the wire; Δt: The temperature variation; L t : The third intermediate parameter; q: dimensionless external load; Wherein, the first intermediate parameter λ is calculated as follows: Where, g: gravity load of the conductor; l: span of the conductor; The dimensionless sag increment is calculated as follows: Where w is the dimensionless sag increment at the midpoint of the conductor under external load.

2. The method according to claim 1, characterized in that The horizontal tension is calculated as follows: Where: H: horizontal tension of the conductor; g: gravity load of the conductor; l: span of the conductor; f: Initial sag of the conductor.

3. The method according to claim 1, characterized in that The pulling force is calculated as follows: Where: T: tension; H: horizontal tension of the conductor; h: horizontal tension increment; g: gravity load of the conductor; q: external load; l: span; x: horizontal coordinate of the conductor; Wherein, the horizontal tension increment h is calculated as follows: h=h·H Where: h: dimensionless increment of horizontal tension.

4. The method according to claim 1, characterized in that The limit state equation is shown as follows: Z=f y A-T=0 Where: Z: structural force of the conductor; f y : Ultimate tensile strength of the conductor; A: cross-sectional area of ​​the conductor; T: tensile force.

5. The method according to claim 1, characterized in that The obtaining of the reliability of the conductor based on the tension and the pre-constructed limit state equation comprises: The reliability of the transmission line is calculated using a first order second order method based on the tension and a pre-constructed limit state equation.

6. The method according to claim 1, characterized in that The external loads include wind loads and ice loads.

7. A system for implementing the reliability analysis method of a conductor in a power transmission line as claimed in claim 1, characterized in that: include: A first calculation module, used for calculating the horizontal tension and the horizontal tension increment of the conductor based on the acquired basic variables; A second calculation module, used for calculating the tension at any point of the wire based on the horizontal tension and the horizontal tension increment; A third calculation module, used for obtaining the reliability of the conductor based on the tension and a pre-constructed limit state equation; The basic variables include: conductor load, initial sag and temperature change amplitude.

8. The system according to claim 7, characterized in that The first computing module comprises: A first calculation unit is used to obtain the horizontal tension of the wire under the gravity load based on the acquired gravity load and initial sag of the wire; A second calculation unit is used to calculate the dimensionless increment of the horizontal tension of the conductor under the current external load based on the initial sag, the temperature change amplitude and the horizontal tension, and obtain the dimensionless increment of the sag at the midpoint of the conductor under the current external load based on the dimensionless increment of the horizontal tension and the current external load; An updating unit, configured to update the initial sag based on the sag increment and recalculate the horizontal tension of the conductor under the gravity load; A result unit, used for judging whether all external loads have been loaded. If all external loads have been loaded, the loop is terminated, and the current horizontal tension and horizontal tension increment are obtained based on the dimensionless value of the horizontal tension increment. Otherwise, the external load is updated and the second calculation unit is executed; Among them, the conductor load includes: gravity load and external load.

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