Safety sag calculation method and system for power transmission tower wire

Abstract

The invention discloses a safety sag calculation method and system for a power transmission tower wire, and the method comprises the steps: constructing a wire stress change relation according to the elastic deformation of the wire under each control condition and the original wire length of the wire; wherein each control condition is set according to a preset environment parameter; based on the wire stress change relation and a preset nonlinear stress change relation, determining the wire tension characteristic under the actual working condition; and obtaining a safety sag meeting a preset lead safety requirement according to the tension characteristic of the lead, and adjusting the sag of the lead under an actual working condition according to the safety sag. According to the method, the nonlinear characteristic of the wire is considered when the tension characteristics of the wire of the power transmission tower in different environments are calculated, so that the calculated wire sag is more accurate and meets the safety requirement of an overhead power transmission line, and sufficient data support is provided for effectively evaluating and ensuring the safety of the power transmission line.

Description

Technical Field

[0001] The present application belongs to the field of safety assessment of power transmission line conductors, and specifically relates to a method and system for calculating the safety sag of power transmission tower conductors. Background Art

[0002] The conductors installed at both ends of the transmission towers need to withstand the test of harsh natural environments such as ice, wind, and low temperatures. Due to the weight of the conductors themselves and the external forces they are subjected to in the above natural environments, the conductors will be subject to a certain amount of tension. In order to ensure that the forces on the conductors under different working conditions can meet certain safety requirements, it is necessary to clarify the sag of the conductors in the above natural environments, and the calculation of sag involves the study of the tension characteristics of the conductors.

[0003] The study of the "stress-strain" relationship of the conductor is the key point in solving the conductor tension characteristics, and the linear and nonlinear characteristics of the conductor material have a significant impact on the conductor tension characteristics. The existing conductor tension characteristic calculation process only considers the linear characteristics of the conductor material, resulting in the lack of nonlinear influencing factors in the calculation of the conductor's "stress-strain" relationship, resulting in large errors in the calculation results, resulting in the sag of the conductor when laying out may not meet safety requirements. Summary of the invention

[0004] The present application proposes a method and system for calculating the safety sag of a transmission tower conductor. When calculating the tension characteristics of a transmission tower conductor under different environments, the nonlinear characteristics of the conductor are taken into account, so that the calculated conductor sag is more accurate and meets the safety requirements of the transmission line, providing sufficient data support for effectively evaluating and ensuring the safety of the transmission line.

[0005] The first aspect of the present application provides a method for calculating the safety sag of a transmission tower conductor, the method comprising:

[0006] According to the elastic deformation of the conductor under each control condition and the original length of the conductor, a conductor stress change relationship is constructed; wherein each control condition is set according to a preset environmental parameter;

[0007] Based on the conductor stress variation relationship and the preset nonlinear stress variation relationship, the conductor tension characteristics under the actual working conditions are determined;

[0008] A safety sag that meets predetermined safety requirements of the conductor is obtained according to the conductor tension characteristics, and the sag of the conductor under actual working conditions is adjusted according to the safety sag.

[0009] The above scheme first sets different control conditions suitable for the actual situation to provide background support for the subsequent research on the conductor tension characteristics. Then, according to the elastic deformation of the conductor under each of the control conditions and the original line length of the conductor, the relationship between the stress and deformation of the conductor under different control conditions is studied, and the conductor stress change relationship is constructed. Then, according to the nonlinear stress change formula, the conductor tension characteristics of the conductor under different working conditions are determined, so that according to the deformation of the conductor in the actual working condition, the stress of the conductor in the working condition can be determined, and the sag range under the working condition can be further determined to ensure that the conductor is in a safe operating state, and to prevent the conductor from collapsing due to excessive stress.

[0010] In a possible implementation method of the first aspect, each control condition is set according to a preset environmental parameter, specifically:

[0011] Selecting several control working conditions, and determining the environmental parameters of each control working condition; wherein the environmental parameters include specific load, tension and temperature;

[0012] According to the environmental parameters, a first curve and a first ratio corresponding to each control working condition are set; wherein the first ratio is the ratio of specific load to tension; and the first curve is a function related to the environmental parameters;

[0013] Comparing all the first curves and all the first ratios respectively, and determining the critical gear span of each control working condition according to the comparison results;

[0014] According to the critical gear span, the control operating condition is screened to determine the control condition.

[0015] The above scheme first determines the environmental parameters corresponding to each working condition according to the provided control working condition, and then sets the first curve and the first ratio according to the environmental parameters to measure the rationality of each working condition, and determines a more appropriate control working condition as the control condition, so that the wire tension characteristics under the control condition are more accurate. In addition, the control working conditions under different wire spans are screened through the critical span to obtain control conditions that are more in line with the actual working conditions.

[0016] In a possible implementation method of the first aspect, all first curves and all first ratios are compared respectively, and the critical gear span of each control condition is determined according to the comparison result, specifically:

[0017] Comparing all the first curves, and screening the first ratios according to the comparison results to obtain a first screening result;

[0018] Compare all first ratios, and screen the first variables according to the comparison results to obtain a second screening result;

[0019] Selecting a plurality of second curves from the first curves according to the first screening result and the second screening result;

[0020] According to the intersection point of any two second curves, the critical gear distance of the control condition corresponding to the second curve is determined.

[0021] In a possible implementation method of the first aspect, the first curve is specifically:

[0022] The specific expression of the first curve is:

[0023]

[0024] In the formula, F kx is the first curve, E is the elastic modulus of the wire, r k is the load ratio of the control condition, l is the gear spacing of the control condition, σ k To control the conductor tension under working conditions, α is the thermal expansion coefficient of the conductor, t is, t k To control the temperature of the working condition, F okx The first curve F kx The initial component, t kx is the temperature of the xth control condition.

[0025] In a possible implementation method of the first aspect, the control operating condition is screened according to the critical gear distance to determine the control condition, specifically:

[0026] If the actual gear span of the control condition is less than the critical gear span of the control condition, the control condition with the smallest first ratio is selected as the control condition;

[0027] If the actual gear span of the control condition is greater than the critical gear span of the control condition, the control condition with the largest first ratio is selected as the control condition.

[0028] In a possible implementation method of the first aspect, a wire stress change relationship is constructed according to the elastic deformation of the wire under each control condition and the original wire length of the wire, specifically:

[0029] According to the elastic deformation of the conductor under each control condition and the difference of the control conditions, constructing a derivation formula of the original wire length under each control condition;

[0030] Based on the fact that the original line lengths are equal under different control conditions, a wire stress variation relationship corresponding to each control condition is obtained according to a formula derived from the original line length.

[0031] The above scheme derives the original wire length of the wire according to the elastic deformation of the wire under each of the control conditions. No matter what kind of deformation the wire undergoes, its original wire length is the same. Based on this condition, the original wire length derivation formula is also equal. Therefore, the wire stress change relationship corresponding to each of the control conditions can be obtained, providing data support for subsequent research on the impact of different control conditions on stress changes.

[0032] In a possible implementation method of the first aspect, based on the conductor stress change relationship and the preset nonlinear stress change relationship, the conductor tension characteristic under actual working conditions is determined, specifically:

[0033] According to the conductor stress variation relationship and the actual working condition, the elastic deformation under the actual working condition is obtained;

[0034] The wire tension characteristics under the actual working condition are determined according to the elastic deformation under the actual working condition and the nonlinear stress variation relationship.

[0035] The above scheme studies the relationship between the elastic deformation of the conductor and the stress it is subjected to in actual working conditions based on the obtained conductor stress change relationship, and then determines the conductor tension characteristics under actual working conditions based on the nonlinear stress change relationship that describes the nonlinear "stress-strain" relationship of the conductor, thereby providing data support for the subsequent calculation of the sag that can ensure that the conductor is always in a safe operating state under actual working conditions.

[0036] In a possible implementation method of the first aspect, a safety sag that meets a predetermined safety requirement of the conductor is obtained according to the conductor tension characteristics, and the sag of the conductor under actual working conditions is adjusted according to the safety sag, specifically:

[0037] According to the conductor tension characteristics, determine the stress of the conductor under actual working conditions;

[0038] According to the stress and the predetermined conductor safety requirement, a safety sag that meets the conductor safety requirement under actual working conditions is obtained;

[0039] According to the safety sag, the sag of the conductor under actual working conditions is adjusted.

[0040] The above scheme can firstly accurately determine the stress of the conductor under actual working conditions according to the conductor tension characteristics under actual working conditions; then, according to the stress and the established conductor safety requirements, the sag of the conductor is adjusted to ensure that the conductor will not have excessive elastic deformation and cause safety problems for the conductor.

[0041] A second aspect of the present application provides a safety sag calculation system for a transmission tower conductor, the system comprising: a conductor stress change relationship construction module, a conductor tension characteristic calculation module and a sag adjustment module;

[0042] The conductor stress variation relationship construction module is used to construct a conductor stress variation relationship according to the elastic deformation of the conductor under each control condition and the original length of the conductor; wherein each control condition is set according to a preset environmental parameter;

[0043] The conductor tension characteristic calculation module is used to determine the conductor tension characteristic under actual working conditions based on the conductor stress change relationship and the preset nonlinear stress change relationship;

[0044] The sag adjustment module is used to obtain a safety sag that meets a predetermined safety requirement of the conductor according to the conductor tension characteristics, and to adjust the sag of the conductor under actual working conditions according to the safety sag.

[0045] A third aspect of the present application provides a storage medium storing computer-readable program code, which, when executed, implements the steps of a method for calculating the safety sag of a transmission tower conductor as described in any one of the embodiments of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the technical solution of the present application, the drawings required for use in the implementation manner will be briefly introduced below. Obviously, the drawings described below are only some implementation manners of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0047] Figure 1 It is a specific flow chart of a method for calculating the safety sag of a transmission tower conductor provided in a certain embodiment of the present application;

[0048] Figure 2 It is a stress-strain relationship diagram of a method for calculating the safety sag of a transmission tower conductor provided in a certain embodiment of the present application;

[0049] Figure 3 A structural diagram of a terminal device is provided for a certain embodiment of the present application. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0051] It should be understood that the step numbers used in this article are only for the convenience of description and are not intended to limit the order in which the steps are executed.

[0052] First embodiment

[0053] Changes in the natural environment will exert different external forces on the wires hanging on the transmission towers. Coupled with the weight of the wires themselves, if the tension on the wires exceeds a certain level, it will bring too much burden to the wires and the poles. Therefore, it is usually necessary to leave a certain amount of sag within a controllable range to ensure the stability of the transmission towers, thereby improving the safety of the transmission lines. Among them, sag refers to the vertical distance between the lowest point of the wire and the line connecting the two hanging points when the wires on two adjacent poles are hung at the same height on flat ground.

[0054] The study of sag is actually the study of the tension characteristics of the conductor. The relationship between stress and elastic deformation of the conductor under different environments is not just a pure linear change, but a complex nonlinear change. Only by clarifying the conductor tension characteristics when the "stress-strain" relationship is nonlinear can we obtain accurate conductor sag to ensure the stable operation of the transmission tower-line.

[0055] like Figure 1 As shown, Figure 1 A specific flow chart of a method for calculating the safety sag of a transmission tower conductor is provided for a certain embodiment of the present application. The method for calculating the safety sag of a transmission tower conductor of this embodiment includes steps S1 to S3, which are described in detail as follows:

[0056] Step S1, constructing a conductor stress change relationship according to the elastic deformation of the conductor under each control condition and the original length of the conductor.

[0057] In the embodiment of the present application, in order to simulate the influence of different environmental factors on the conductor tension characteristics, it is necessary to select appropriate and representative control conditions as the background conditions for studying the conductor tension characteristics. Moreover, according to the design requirements of the transmission line, the conductor needs to meet specific force requirements under characteristic meteorological conditions, and this specific meteorological condition is the control condition in the embodiment of the present application. Therefore, several control conditions are first selected to determine the environmental parameters of each control condition.

[0058] The control conditions include low temperature conditions, icing conditions, strong wind conditions, and average annual conditions. The environmental parameters of these conditions are given by the design requirements of the transmission line and are known quantities. The environmental parameters include specific load, tension, and temperature.

[0059] In order to facilitate the screening of control conditions, two intermediate variables are designed in the embodiment of the present application for comparing the suitability of each control condition, and these two intermediate variables are the first curve and the first ratio. According to the environmental parameters of each control condition, the first curve and the first ratio corresponding to each control condition are set. Among them, the first ratio is the ratio of specific load to tension.

[0060] Furthermore, the specific expression of the first curve is:

[0061]

[0062] In the formula, F kx is the first curve, E is the elastic modulus of the wire, r k is the load ratio of the control condition, l is the gear spacing of the control condition, σ k To control the conductor tension under working conditions, α is the thermal expansion coefficient of the conductor, the unit is ×10 -6 / ℃, t is the temperature of the working condition to be determined, t k To control the temperature of the working condition, F okx The first curve F kx The initial component, t kx is the temperature of the xth control condition, and the above four control conditions are numbered as a, b, c and d respectively. Wherein, the span is the horizontal distance between the wire suspension points of two adjacent towers in the overhead line.

[0063] In addition, F kx and F okx There are the following relationships between them:

[0064]

[0065] Then, by comparing the first curve and the first ratio, the comparison results of various control conditions are obtained.

[0066] Exemplarily, the comparison results of the first curve and the first ratio of the embodiment of the present application are sorted according to the following formula:

[0067]

[0068] The first row of formulas is the first ratio of the four control conditions a, b, c and d, γ ka , γ kb , γ kc and γ kd is the load ratio of the four control conditions a, b, c and d, σ ka , σ kb , σ kc and σ kd is the tension of four control conditions a, b, c and d, F oka 、F okb 、F okc and F okd It is the first curve of the four control conditions a, b, c and d.

[0069] According to the above formula, if If they are the same, then F okx The smaller control condition is discarded; if F okxThe same, then The smaller control conditions are discarded, and then the first curves of the remaining control conditions are called second curves, and the intersection points of each second curve are calculated two by two.

[0070] Specifically, when determining the second curve F ki =F kj After the intersection, the spacing l at the intersection ij It is called the critical gear distance between the i-th control condition and the j-th control condition. i = l j = l ij . From this, the following formulas for the i-th control condition and the j-th control condition can be obtained:

[0071]

[0072] In the formula, σ ki , σ kj are the tensions of the ith control condition and the jth control condition, in N / mm 2 , γ ki , γ kj are the load ratios of the ith control condition and the jth control condition, in N / mm 2 , t ki ,t kj They are the temperatures of the ith control condition and the jth control condition respectively, in ℃.

[0073] By calculating the above formula, we can get the calculation formula for the critical gear spacing, as follows:

[0074]

[0075] Wherein, (m) represents the critical gear distance in meters, m.

[0076] After determining the critical span of each control condition, the actual span of the corresponding control condition is judged by the critical span, the control conditions are screened, and control conditions that better meet the design requirements of the transmission line are determined.

[0077] For example, in the embodiment of the present application, if the actual gear distance of the i-th control condition is less than l ij , then the condition with the smallest first ratio between the i-th control condition and the j-th control condition is selected as the control condition; if the actual gear span of the i-th control condition is greater than l ij , then the condition with the largest ratio between the i-th control condition and the j-th control condition is selected as the control condition.

[0078] Then the stress and deformation relationship of the conductor under each control condition is studied in combination with the control conditions.

[0079] Firstly, after the elastic deformation of the conductor under each control condition is determined, the original wire length derivation formula for each control condition can be calculated according to the difference of the control conditions.

[0080] Because the original length of the wire is the length of the wire when it leaves the factory and has not been deformed by weather and other environmental factors, the original length is known and is consistent under any control conditions. Based on this principle, the following formula is available:

[0081]

[0082] Where l is any span, in m, t0 is the initial temperature, α is the thermal expansion coefficient of the conductor, E is the elastic modulus of the conductor, r k is the load ratio of the kth control condition, σ k is the stress of the kth control condition, t k is the temperature of the kth control condition, r is the specific load of the working condition to be determined, σ is the stress of the working condition to be determined, and t is the temperature of the working condition to be determined.

[0083] By arranging the above formula, we can get a cubic equation for the stress σ of the working condition to be determined, which is the stress change relationship of the conductor corresponding to the working condition to be determined. Based on this, the stress change relationship of the conductor corresponding to each control condition can be obtained, and the specific expression is as follows:

[0084]

[0085] Because the control condition is set, r k , σ k and t k are all known, and the stress under the desired working condition can be solved by controlling the environmental parameters of the conditions, and the wire tension characteristics under the desired working condition can be obtained.

[0086] Step S2, determining the conductor tension characteristics under actual working conditions based on the conductor stress variation relationship and the preset nonlinear stress variation relationship.

[0087] In the embodiment of the present application, in order to improve the accuracy of the data, a preset nonlinear stress change relationship is introduced to express the nonlinear stress-strain relationship of the wire in actual conditions.

[0088] Affected by the nonlinear characteristics of the conductor material, the "stress-strain" relationship of the conductor is nonlinear. The specific expression formula is as follows:

[0089] σ=a1ε+a2ε 2 +a3ε 3 +a4ε 4 ;

[0090] Where σ is the conductor stress, unit is N / mm 2 , a1, a2, a3 and a4 are stress coefficients, which are generally constants, and ε is the wire deformation, in %.

[0091] In the general stress-strain relationship of a conductor, this relationship is often assumed to be linear. Under this linear relationship, the deformation of the conductor is also linear, and the elongation of the conductor increases linearly with the increase of stress. But in fact, if the conductor is made of materials such as rubber, polymer or biological soft tissue, these materials will show nonlinear characteristics in the stress-strain relationship. This is because the stress distribution will be affected by the properties of the material itself. In some special materials, the stress will not be evenly distributed, which will cause the conductor to have nonlinear length changes due to uneven force. Moreover, the stress distribution is not only affected by the type of material, but also by the change of the geometric shape of the conductor, and this influence is also nonlinear. Therefore, when calculating the relationship between the length and stress of the conductor, it cannot be simply regarded as a linear relationship, but more complex nonlinear factors need to be considered to ensure the accuracy and practicality of the obtained conductor tension characteristics. It is also worth mentioning that in the analysis of transmission lines, the relationship between the sag, line length and stress of the conductor reflects this nonlinear relationship. Therefore, by studying the tension characteristics of the conductor, a more accurate conductor sag that ensures the safety of the transmission tower can be obtained.

[0092] In order to better represent the deformation of the conductor under linear and nonlinear "stress-strain" relationships, Figure 2 A stress-strain relationship diagram is provided. As shown in the figure, the upper figure is a linear "stress-strain" relationship. As the stress increases, the elongation of the wire also gradually increases at a fixed ratio, such as the formula σ=Eε; E is the elastic modulus of the wire. The lower figure is a nonlinear "stress-strain" relationship. As the stress increases, the change in the length of the wire is not uniform, but the elongation gradually decreases as the stress increases.

[0093] Therefore, in the embodiment of the present application, a preset nonlinear stress change relationship is introduced to more accurately calculate the wire tension characteristics in real life, so as to obtain a more accurate wire sag.

[0094] Because the cubic equation of the stress σ for the working condition to be determined obtained in step 1 actually assumes that the relationship between σ and the change of the conductor stress is linear, it is necessary to introduce the nonlinear stress change relationship to express σ in the embodiment of the present application, so as to highlight the nonlinear characteristics of the conductor.

[0095] First, obtain the specific information of the actual working conditions, and then analyze the relationship between the actual working conditions and the conductor stress change obtained in step 1. In fact, stress σ and stress σk The elastic deformation caused by the nonlinear stress change relationship can be expressed by ε and ε k Substitute these elastic deformations, and then substitute the replaced parameters into the cubic equation of stress σ for the working condition to be determined obtained in step 1, and obtain the cubic equation of stress σ for the actual working condition. The specific expression is:

[0096]

[0097] Then, the nonlinear stress variation relationship is combined with the cubic equation of stress σ under actual working conditions to obtain the following formula:

[0098]

[0099] To simplify the calculation, let:

[0100]

[0101] So we get the following formula:

[0102] (a1ε+a2ε 2 +a3ε 3 +a4ε 4 ) 2 ε+(a1ε+a2ε 2 +a3ε 3 +a4ε 4 ) 2 K2-K1=0;

[0103] By rewriting the formula and using b to replace the coefficient of ε, we can obtain a one-variable multi-time equation for elastic deformation under actual working conditions. The specific expression is:

[0104] b9ε 9 +b8ε 8 +b7ε 7 +b6ε 6 +b5ε 8 +b4ε 4 +b3ε 3 +b2ε 2 +b1ε+b0=0;

[0105] By solving this one-variable multi-time equation in combination with the environmental parameters of the actual working conditions, the stress of the actual working conditions can be obtained.

[0106] According to the stress of the actual working condition, the wire tension characteristics under the actual working condition can be obtained, and the changing relationship between the wire length and stress under the actual working condition can be determined.

[0107] Step S3, obtaining a safety sag that meets a predetermined safety requirement of the conductor according to the conductor tension characteristics, and adjusting the sag of the conductor under actual working conditions according to the safety sag.

[0108] In this step, after determining the conductor tension characteristics under actual working conditions, the changing relationship between the conductor length and stress under actual working conditions can be determined, and combined with the predetermined conductor safety requirements, the safety sag that meets the conductor safety requirements under actual working conditions can be obtained.

[0109] The safety sag is the maximum sag of the conductor within the controllable range. When the stress on the conductor is large, the sag of the conductor becomes smaller, and the temperature rise or ice on the conductor will increase the sag. Therefore, by adjusting the sag of the conductor under actual working conditions through the safety sag, it can be ensured that the stress on the conductor can always meet the safety requirements of the transmission line, and in extreme weather, it can also ensure that the conductor has a certain safety reserve, so that the transmission line can operate stably.

[0110] Implementing the embodiments of the present application has the following beneficial effects:

[0111] The embodiment of the present application first provides data support for studying the nonlinear conductor tension characteristics by setting control conditions that are in line with the actual situation and can represent different weather conditions. Then, according to the elastic deformation of the conductor under each of the control conditions and the original line length of the conductor, the stress-strain relationship of the conductor under the linear condition is first obtained, and then the nonlinear stress change formula is introduced, and the elastic deformation of the conductor with nonlinear changes is used to calculate the stress under the actual working conditions, and the nonlinear stress-strain relationship of the conductor is obtained, and the stress under the actual working conditions is obtained accurately. Finally, based on the stress under the actual working conditions, the safe sag of the conductor under the actual working conditions is obtained to adjust the sag of the conductor, so that the stress on the conductor is within the normal range under most weather conditions, providing data support for ensuring the safe operation of the transmission line; and the nonlinear stress-strain relationship of the conductor can also provide data support for real-time evaluation of the safety of the transmission line.

[0112] Second embodiment

[0113] Further, in order to execute the safety sag calculation system of the transmission tower conductor corresponding to the above method embodiment to achieve the corresponding functions and technical effects, Figure 3 A structural diagram of a safety sag calculation system for a transmission tower conductor is provided. For ease of description, only the parts related to this embodiment are shown. The safety sag calculation system for a transmission tower conductor provided in the embodiment of the present application includes:

[0114] The conductor stress variation relationship construction module 201 is used to construct a conductor stress variation relationship according to the elastic deformation of the conductor under each control condition and the original length of the conductor; wherein each control condition is set according to a preset environmental parameter.

[0115] In an embodiment of the present application, a suitable control condition is first selected, and the specific process is: select several control conditions and determine the environmental parameters of each control condition; wherein the environmental parameters include specific load, tension and temperature; according to the environmental parameters, set the first curve and the first ratio corresponding to each control condition; wherein the first ratio is the ratio of the specific load to the tension; the first curve is a function related to the environmental parameters; compare all the first curves and all the first ratios respectively, and determine the critical gear distance of each control condition according to the comparison result; according to the critical gear distance, screen the control condition to determine the control condition.

[0116] Then, according to the elastic deformation of the wire under each control condition and the difference of the control conditions, the original wire length derivation formula for each control condition is constructed. Based on the original wire length being equal under different control conditions, the wire stress change relationship corresponding to each control condition is obtained according to the original wire length derivation formula.

[0117] The conductor tension characteristic calculation module 202 is used to determine the conductor tension characteristic under actual working conditions based on the conductor stress variation relationship and the preset nonlinear stress variation relationship.

[0118] In the embodiment of the present application, the elastic deformation under the actual working condition is obtained according to the wire stress variation relationship and the actual working condition. The wire tension characteristic under the actual working condition is determined according to the elastic deformation under the actual working condition and the nonlinear stress variation relationship.

[0119] The sag adjustment module 203 is used to obtain a safety sag that meets a predetermined conductor safety requirement according to the conductor tension characteristics, and adjust the conductor sag under actual working conditions according to the safety sag.

[0120] In the embodiment of the present application, after determining the conductor tension characteristics under actual working conditions, the changing relationship between the conductor length and stress under actual working conditions can be determined, and combined with the predetermined conductor safety requirements, the safety sag that meets the conductor safety requirements under actual working conditions can be obtained. Because when the stress on the conductor is large, the sag of the conductor becomes smaller, and the temperature rise or ice on the conductor will increase the sag, so adjusting the sag of the conductor under actual working conditions through the safety sag can ensure that the stress on the conductor can always meet the safety requirements of the transmission line, and in extreme weather, it can also ensure that the conductor has a certain safety reserve, so that the transmission line can operate stably.

[0121] In some embodiments, the conductor stress variation relationship building module 201 further includes:

[0122] According to the design requirements of the transmission line, the conductor needs to meet specific force requirements under characteristic meteorological conditions, and this specific meteorological condition is the control condition in the embodiment of the present application. Therefore, several control conditions are first selected to determine the environmental parameters of each control condition. Among them, the control conditions include low temperature conditions, icing conditions, high wind conditions, and average annual conditions. The environmental parameters of these conditions are all given by the design requirements of the transmission line and are known quantities. The environmental parameters include specific load, tension and temperature.

[0123] In order to facilitate the screening of control conditions, two intermediate variables are designed in the embodiment of the present application for comparing the suitability of each control condition, and these two intermediate variables are the first curve and the first ratio. According to the environmental parameters of each control condition, the first curve and the first ratio corresponding to each control condition are set. Among them, the first ratio is the ratio of specific load to tension.

[0124] Furthermore, the specific expression of the first curve is:

[0125]

[0126] In the formula, F kx is the first curve, E is the elastic modulus of the wire, r k is the load ratio of the control condition, l is the gear spacing of the control condition, σ k To control the conductor tension under working conditions, α is the thermal expansion coefficient of the conductor, the unit is ×10 -6 / ℃, t is the temperature of the working condition to be determined, in ℃, t k To control the temperature of the working condition, F okx The first curve F kx The initial component, t kx is the temperature of the xth control condition, and the above four control conditions are numbered as a, b, c and d respectively. Wherein, the span is the horizontal distance between the wire suspension points of two adjacent towers in the overhead line.

[0127] In addition, F kx and F okx There are the following relationships between them:

[0128]

[0129] Then, by comparing the first curve and the first ratio, the comparison results of each control condition are obtained. According to the comparison results, a plurality of second curves are selected from the first curves, and then the critical span of the control condition corresponding to the second curve is determined according to the intersection of any two second curves. After determining the critical span of each control condition, the actual span of the corresponding control condition is judged by the critical span, and the control condition is screened to determine the control condition that better meets the design requirements of the transmission line.

[0130] For example, in the embodiment of the present application, if the actual gear distance of the i-th control condition is less than l ij , then the condition with the smallest first ratio between the i-th control condition and the j-th control condition is selected as the control condition; if the actual gear span of the i-th control condition is greater than l ij , then the condition with the largest ratio between the i-th control condition and the j-th control condition is selected as the control condition.

[0131] Then the stress and deformation relationship of the conductor under each control condition is studied in combination with the control conditions.

[0132] Firstly, after the elastic deformation of the conductor under each control condition is determined, the original wire length derivation formula for each control condition can be calculated according to the difference of the control conditions.

[0133] Because the original length of the wire is the length of the wire when it leaves the factory and has not been deformed by weather and other environmental factors, the original length is known and is consistent under any control conditions. Based on this principle, the following formula is available:

[0134]

[0135] Where l is any span, in m, t0 is the initial temperature, α is the thermal expansion coefficient of the conductor, E is the elastic modulus of the conductor, r k is the load ratio of the kth control condition, σ k is the stress of the kth control condition, t k is the temperature of the kth control condition, r is the specific load of the working condition to be determined, σ is the stress of the working condition to be determined, and t is the temperature of the working condition to be determined.

[0136] By arranging the above formula, we can get a cubic equation for the stress σ of the working condition to be determined, which is the stress change relationship of the conductor corresponding to the working condition to be determined. Based on this, the stress change relationship of the conductor corresponding to each control condition can be obtained, and the specific expression is as follows:

[0137]

[0138] Because the control condition is set, rk , σ k and t k are all known, and the stress under the desired working condition can be solved by controlling the environmental parameters of the conditions, and the wire tension characteristics under the desired working condition can be obtained.

[0139] In some embodiments, the conductor tension characteristic calculation module 202 further includes:

[0140] In the embodiment of the present application, in order to improve the accuracy of the data, a preset nonlinear stress change relationship is introduced to express the nonlinear stress-strain relationship of the wire in actual conditions. The specific expression of the nonlinear stress change relationship is:

[0141] σ=a1ε+a2ε 2 +a3ε 3 +a4ε 4 ;

[0142] Where σ is the conductor stress, unit is N / mm 2 , a1, a2, a3 and a4 are stress coefficients, which are generally constants, and ε is the wire deformation, in %.

[0143] Because the cubic equation of the stress σ of the working condition to be determined obtained in the conductor tension characteristic calculation module 201 actually assumes that the relationship between σ and the conductor stress is linear, it is necessary to introduce the nonlinear stress change relationship to express σ in the embodiment of the present application, so as to highlight the nonlinear characteristics of the conductor.

[0144] First, obtain the specific information of the actual working conditions, and then analyze the relationship between the actual working conditions and the conductor stress change obtained in step 1. In fact, stress σ and stress σ k The elastic deformation caused by the nonlinear stress change relationship can be expressed by ε and ε k These elastic deformations are replaced, and then the replaced parameters are substituted into the cubic equation of stress σ of the working condition to be calculated obtained in the wire tension characteristic calculation module 201, and the cubic equation of stress σ of the actual working condition is obtained. The specific expression is:

[0145]

[0146] Then, the nonlinear stress variation relationship is combined with the cubic equation of stress σ under actual working conditions to obtain the following formula:

[0147]

[0148] To simplify the calculation, let:

[0149]

[0150] So we get the following formula:

[0151] (a1ε+a2ε 2 +a3ε 3 +a4ε 4 ) 2 ε+(a1ε+a2ε 2 +a3ε 3 +a4ε 4 ) 2 K2-K1=0;

[0152] By rewriting the formula and using b to replace the coefficient of ε, we can obtain a one-variable multi-time equation for elastic deformation under actual working conditions. The specific expression is:

[0153] b9ε 9 +b8ε 8 +b7ε 7 +b6ε 6 +b5ε 8 +b4ε 4 +b3ε 3 +b2ε 2 +b1ε+b0=0;

[0154] By solving this one-variable multi-time equation in combination with the environmental parameters of the actual working conditions, the stress of the actual working conditions can be obtained.

[0155] According to the stress of the actual working condition, the wire tension characteristics under the actual working condition can be obtained, and the changing relationship between the wire length and stress under the actual working condition can be determined.

[0156] Implementing the embodiments of the present application has the following beneficial effects:

[0157] The embodiment of the present application first provides background support for the subsequent research on the conductor tension characteristics by setting different control conditions suitable for the actual situation. Then, according to the elastic deformation of the conductor under each of the control conditions and the original line length of the conductor, the relationship between the stress and deformation of the conductor under different control conditions is studied, and the conductor stress change relationship is constructed. Then, according to the nonlinear stress change formula, the conductor tension characteristics of the conductor under different working conditions are determined, so that according to the deformation of the conductor in the actual working condition, the stress of the conductor in the working condition can be determined, and the sag range under the working condition can be further determined to ensure that the conductor is in a safe operating state, providing sufficient data support for effectively evaluating and ensuring the safety of the transmission line.

[0158] An embodiment of the present application also provides a storage medium, which stores computer-readable program code. When the computer-readable program code is executed, the steps of the above-mentioned method for calculating the safety sag of a transmission tower conductor are implemented.

[0159] The specific embodiments described above further describe the purpose, technical solutions and beneficial effects of the present application in detail. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the scope of protection of the present application. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A method for calculating the safety sag of a transmission tower conductor, characterized in that: include: According to the elastic deformation of the conductor under each control condition and the original length of the conductor, a conductor stress change relationship is constructed; wherein each control condition is set according to a preset environmental parameter; Based on the conductor stress variation relationship and the preset nonlinear stress variation relationship, the conductor tension characteristics under the actual working conditions are determined; A safety sag that meets predetermined safety requirements of the conductor is obtained according to the conductor tension characteristics, and the sag of the conductor under actual working conditions is adjusted according to the safety sag.

2. The method for calculating the safety sag of a transmission tower conductor according to claim 1, characterized in that: Each control condition is set according to preset environmental parameters, specifically: Selecting several control working conditions, and determining the environmental parameters of each control working condition; wherein the environmental parameters include specific load, tension and temperature; According to the environmental parameters, a first curve and a first ratio corresponding to each control working condition are set; wherein the first ratio is the ratio of specific load to tension; and the first curve is a function related to the environmental parameters; Comparing all the first curves and all the first ratios respectively, and determining the critical gear span of each control working condition according to the comparison results; According to the critical gear span, the control operating condition is screened to determine the control condition.

3. The method for calculating the safety sag of a transmission tower conductor according to claim 2, characterized in that: The method of comparing all the first curves and all the first ratios respectively and determining the critical gear distance of each control condition according to the comparison results is specifically as follows: Comparing all the first curves, and screening the first ratios according to the comparison results to obtain a first screening result; Compare all first ratios, and screen the first variables according to the comparison results to obtain a second screening result; Selecting a plurality of second curves from the first curves according to the first screening result and the second screening result; According to the intersection point of any two second curves, the critical gear distance of the control condition corresponding to the second curve is determined.

4. The method for calculating the safety sag of a transmission tower conductor according to claim 2, characterized in that: The first curve is specifically: The specific expression of the first curve is: In the formula, F kx is the first curve, E is the elastic modulus of the wire, r k is the load ratio of the control condition, l is the gear spacing of the control condition, σ k To control the conductor tension under working conditions, α is the thermal expansion coefficient of the conductor, t is, t k To control the temperature of the working condition, F okx The first curve F kx The initial component, t kx is the temperature of the xth control condition.

5. The method for calculating the safety sag of a transmission tower conductor according to claim 2, characterized in that: The control conditions are screened according to the critical gear distance to determine the control conditions, specifically: If the actual gear span of the control condition is less than the critical gear span of the control condition, the control condition with the smallest first ratio is selected as the control condition; If the actual gear span of the control condition is greater than the critical gear span of the control condition, the control condition with the largest first ratio is selected as the control condition.

6. The method for calculating the safety sag of a transmission tower conductor according to claim 1, characterized in that: According to the elastic deformation of the wire under each control condition and the original wire length of the wire, a wire stress change relationship is constructed, specifically: According to the elastic deformation of the conductor under each control condition and the difference of the control conditions, constructing a derivation formula of the original wire length under each control condition; Based on the fact that the original line lengths are equal under different control conditions, a wire stress variation relationship corresponding to each control condition is obtained according to a formula derived from the original line length.

7. The method for calculating the safety sag of a transmission tower conductor according to claim 1, characterized in that: The conductor tension characteristics under actual working conditions are determined based on the conductor stress variation relationship and the preset nonlinear stress variation relationship, specifically: According to the conductor stress variation relationship and the actual working condition, the elastic deformation under the actual working condition is obtained; The wire tension characteristics under the actual working condition are determined according to the elastic deformation under the actual working condition and the nonlinear stress variation relationship.

8. The method for calculating the safety sag of a transmission tower conductor according to claim 1, characterized in that: The method of obtaining a safety sag that meets a predetermined safety requirement of the conductor according to the conductor tension characteristics, and adjusting the sag of the conductor under actual working conditions according to the safety sag, is specifically as follows: According to the conductor tension characteristics, determine the stress of the conductor under actual working conditions; According to the stress and the predetermined conductor safety requirement, a safety sag that meets the conductor safety requirement under actual working conditions is obtained; According to the safety sag, the sag of the conductor under actual working conditions is adjusted.

9. A safety sag calculation system for transmission tower conductors, characterized in that: include: Conductor stress variation relationship building module, conductor tension characteristic calculation module and sag adjustment module; The conductor stress variation relationship construction module is used to construct a conductor stress variation relationship according to the elastic deformation of the conductor under each control condition and the original length of the conductor; wherein each control condition is set according to a preset environmental parameter; The conductor tension characteristic calculation module is used to determine the conductor tension characteristic under actual working conditions based on the conductor stress change relationship and the preset nonlinear stress change relationship; The sag adjustment module is used to obtain a safety sag that meets a predetermined safety requirement of the conductor according to the conductor tension characteristics, and to adjust the sag of the conductor under actual working conditions according to the safety sag.

10. A storage medium, characterized in that: The storage medium stores computer-readable program codes, which, when executed, implement the steps of a method for calculating the safety sag of a transmission tower conductor according to any one of claims 1 to 8.

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