Tower strain simulation method and system based on thermal coupling

Abstract

The application provides a tower strain simulation method and system based on thermal coupling, comprising the following steps: establishing a finite element model of a power transmission tower, discretizing the power transmission tower into units, setting several working conditions, obtaining the force load corresponding to each unit of the power transmission tower under each working condition, obtaining the thermal strain corresponding to each unit of the power transmission tower, taking the force load and the thermal strain corresponding to each unit of the power transmission tower as known quantities, solving the partial stress and the partial strain of each unit in each direction under each working condition, obtaining the partial stress ratio based on the ratio of the partial stress to the maximum value that can be borne by the unit for the partial stress of each unit in each direction under each working condition, selecting several weak units of the power transmission tower with the partial stress ratio exceeding the limit to install strain sensors, and judging the reliability of the selected weak units of the power transmission tower based on the partial strain of each unit in each direction under each working condition. The application comprehensively considers the force load and the thermal strain received by the power transmission tower, and the simulation effect is better.

Description

Technical Field

[0001] This invention relates to the field of transmission tower simulation technology, specifically to a method and system for simulating tower strain based on thermo-coupling. Background Technology

[0002] As a critical infrastructure of the power grid, transmission towers undertake core functions such as power transmission, regulation, and distribution. With the continuous expansion of the power grid coverage and the increasing voltage levels, the complexity of system operation has significantly increased, placing more stringent demands on intelligent monitoring technology for transmission lines. In the field of engineering mechanics research, mechanical simulation analysis of transmission towers based on the finite element method provides important theoretical basis for intelligent monitoring systems. In regions with extreme temperature differences, temperature changes directly lead to the thermal expansion and contraction of steel structures, severely affecting the deformation of transmission tower steel structures. Simulation calculations considering only mechanical properties have poor accuracy; therefore, improving the accuracy of mechanical simulation calculations for transmission towers has always been a key focus of theoretical research. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method and system for simulating transmission tower strain based on thermo-coupling, which comprehensively considers the force load and thermal strain received by the transmission tower, resulting in better simulation performance.

[0004] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0005] A method for simulating tower strain based on thermo-coupling includes:

[0006] Establish a finite element model of the transmission tower and discretize the transmission tower into elements;

[0007] Several operating conditions are set. Under each operating condition, gravity load, wind load and / or icing load are applied to the transmission tower. The force load corresponding to each unit of the transmission tower is obtained based on the gravity load, wind load and / or icing load. At the same time, temperature load is applied to the transmission tower. The thermal strain corresponding to each unit of the transmission tower is obtained based on the temperature load.

[0008] Using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, the component stress and component strain of each unit in each direction under each working condition are solved based on the control equation of elasticity.

[0009] For the stress components in each unit in each direction under each working condition, the stress component ratio is obtained based on the ratio of the stress component to the maximum value that the unit can withstand. Strain sensors are installed on several weak units of the transmission tower where the stress component ratio exceeds the limit.

[0010] The reliability of selecting weak elements of the transmission tower is determined based on the strain of each element in each direction under each working condition.

[0011] Furthermore, wind loads include horizontal wind loads perpendicular to the conductor or ground wire axis and / or unit horizontal wind loads on transmission towers:

[0012] Horizontal wind load W perpendicular to the axis of the conductor ground wire x The calculation formula is:

[0013] W x =0.625αμ sc β c (d+2δ)l H (K h v) 2 ×sin 2 θ×10 -3

[0014] In the formula, α is the wind pressure non-uniformity coefficient of the conductor or ground wire; μ sc β is the conductor or ground wire shape factor. c K is the wind load adjustment factor for 500kV power lines acting on transmission towers. h d is the wind speed height variation coefficient at the average height of the conductor or ground wire; d is the outer diameter of the conductor or ground wire; δ is the icing thickness of the conductor or ground wire; l H θ is the horizontal span of the transmission tower; θ is the angle between the wind direction and the axis of the conductor or ground wire.

[0015] Unit horizontal wind load F of transmission tower t The calculation formula is:

[0016]

[0017] In the formula, k is the wind shape coefficient; k z The wind pressure height variation coefficient; k T A is the wind load adjustment factor; c The wind-blocking area of ​​the steel structure of the transmission tower;

[0018] The formula for calculating icing load is:

[0019]

[0020] In the formula, n is the number of components connected at the component connection point; ρ is the density of the ice covering; g is the acceleration due to gravity; h z is the coefficient of variation of ice diameter with altitude; D is the diameter of the ice; l j The length of a single component.

[0021] Furthermore, the calculation formula for the thermal strain corresponding to each unit of the transmission tower based on temperature load is as follows:

[0022] ε t =α·ΔT

[0023] In the formula, ε t The thermal strain is caused by temperature change; α is the coefficient of thermal expansion of the material; ΔT = T - T0, where T is the current temperature and T0 is the reference temperature.

[0024] Furthermore, taking the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, the method for solving the component stress and component strain of each unit in each direction under each working condition based on the elasticity control equation is as follows:

[0025] The relationship between the stress matrix and the force load matrix corresponding to the element is established based on the equilibrium differential equations as follows:

[0026]

[0027] Where: σ x σ y σ z τ represents the stress along the x, y, and z axes of the element, with tensile stress being positive and compressive stress being negative; xy τ xz τ yz τ yx τ zx τ zy For shear stress, the subscript indicates the direction of the normal to the surface acting on the stress and the direction of the stress, where τ xy =τ yx τ xz =τ zx τ yz =τ zy X, Y, and Z are the force load components of the element in the x, y, and z axes;

[0028] The relationship between the stress matrix and strain matrix corresponding to the node is established based on the material constitutive equations:

[0029]

[0030] Where: ε x ε y ε z γ yz γ xz γ xy For the strain component, E and v represent Young's elastic modulus and Poisson's ratio, respectively.

[0031] Furthermore, the method for obtaining the tensile or compressive stress in each direction of each element is as follows:

[0032] The total strain of the element is obtained based on the finite element model of the transmission tower, and the calculation formula is as follows:

[0033] ε total =ε+εt

[0034] In the formula, ε total ε is the total strain; ε is the elastic strain; ε t Thermal strain;

[0035] The mechanical stress is obtained from the total stress, and the calculation formula is as follows:

[0036] σ=E(ε total -α·ΔT)

[0037] In the formula, σ is mechanical stress and E is Young's elastic modulus;

[0038] Decomposing mechanical stress can yield tensile or compressive stresses in various directions of the element.

[0039] Furthermore, the various operating conditions of the transmission tower include multiple operating conditions under uniform settlement and multiple operating conditions under non-uniform settlement. The multiple operating conditions under uniform settlement are obtained by settling one or more tower legs with a first settlement value sequence of uniform increments, and the multiple operating conditions under non-uniform settlement are obtained by settling one or more tower legs with a second settlement value sequence of non-uniform increments.

[0040] Furthermore, the method for selecting several weak elements of transmission towers with excessive stress ratios to install strain sensors is as follows:

[0041] A first sorting table is established by arranging the stress components in descending order. Units with stress components exceeding a first threshold are extracted from the first sorting table to establish a second sorting table. All units in the second sorting table that are repeated more than the second threshold are identified as weak units of the transmission tower.

[0042] A tower strain simulation system based on thermo-coupling includes:

[0043] The finite element model building module is used to build finite element models of transmission towers, discretizing the transmission towers into elements;

[0044] The load application module is used to set several working conditions. Under each working condition, gravity load, wind load and / or icing load are applied to the transmission tower. Based on the gravity load, wind load and / or icing load, the force load corresponding to each unit of the transmission tower is obtained. At the same time, temperature load is applied to the transmission tower, and the thermal strain corresponding to each unit of the transmission tower is obtained based on the temperature load.

[0045] The acquisition module is used to solve the component stress and component strain of each unit in each direction under each working condition based on the elasticity control equation, using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities.

[0046] The strain sensor installation module is used to obtain the stress ratio of each unit in each direction under each working condition based on the ratio of the stress ratio to the maximum value that the unit can withstand, and to select several weak units of the transmission tower with stress ratios exceeding the limit to install strain sensors.

[0047] The verification module is used to determine the reliability of the selection of weak elements in the transmission tower based on the strain of each element in each direction under each working condition.

[0048] An electronic device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the program to implement the above-described method for simulating tower strain based on thermo-coupling.

[0049] A non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method for simulating tower strain based on thermo-coupling.

[0050] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0051] This invention, by simultaneously considering the effects of gravity load, wind load and / or icing load and temperature load, obtains the force load and thermal strain corresponding to each unit of the transmission tower, enabling more accurate simulation of the real behavior of transmission towers in complex environments. Furthermore, based on the elasticity control equation, it solves for the component stresses and strains of each unit in each direction under each working condition. For the component stresses of each unit in each direction under each working condition, it obtains the component stress ratio based on the ratio of the component stress to the maximum value that the unit can withstand. Units whose component stress ratios exceed the limit a certain number of times are selected as weak units of the transmission tower. Strain sensors are installed at several installation positions in these weak units to identify potential risks and take preventative measures, thereby improving the safety of the transmission tower. This invention can simulate strain conditions under different environmental conditions, providing a reference for the performance of transmission towers under various climatic and geographical conditions. Attached Figure Description

[0052] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and are intended to explain the invention, but do not constitute an undue limitation thereof. In the drawings:

[0053] Figure 1 This is a flowchart of a tower strain simulation method based on thermo-coupling according to the present invention;

[0054] Figure 2 This is a schematic diagram of the finite element model of the transmission tower of the present invention;

[0055] Figure 3This is a cloud diagram showing the stress distribution of the tower-line unit in this invention;

[0056] Figure 4 This is a comparison of the strain distribution of transmission tower elements obtained by the mechanical simulation and thermo-mechanical coupling simulation method of this invention;

[0057] Figure 5 This is a cloud diagram showing the axial stress of the steel structure of the transmission tower according to the present invention;

[0058] Figure 6 This is a curve showing the variation of stress in the key steel structure of the tower leg as a function of settlement.

[0059] Figure 7 This is a schematic diagram of the distribution points of the strain sensors on the transmission towers according to the present invention;

[0060] Figure 8 This is a comparison chart of the strain data between the simulated and measured values ​​of this invention;

[0061] Figure 9 This is a schematic diagram of a tower strain simulation system based on thermo-coupling according to the present invention. Detailed Implementation

[0062] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0063] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the system or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0064] Example 1

[0065] Example 1 provides a method for simulating tower strain based on thermo-coupling, including the following steps:

[0066] Step S1: Establish a finite element model of the transmission tower and discretize the transmission tower into elements;

[0067] Step S2: Set several working conditions. Under each working condition, apply gravity load, wind load and / or icing load to the transmission tower. Obtain the force load corresponding to each unit of the transmission tower based on the gravity load, wind load and / or icing load. At the same time, apply temperature load to the transmission tower and obtain the thermal strain corresponding to each unit of the transmission tower based on the temperature load.

[0068] Step S3: Using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, solve the component stress and component strain of each unit in each direction under each working condition based on the control equation of elasticity.

[0069] Step S4: For the stress components in each direction of each unit under each working condition, obtain the stress component ratio based on the ratio of the stress component to the maximum value that the unit can withstand. Select the unit whose stress component ratio exceeds the limit a certain number of times as the weak unit of the transmission tower. Select several installation positions in the weak unit of the transmission tower to install strain sensors.

[0070] Step S5: Determine the reliability of the selection of weak elements of the transmission tower based on the strain of each unit in each direction under each working condition.

[0071] In the actual monitoring of transmission towers, temperature changes in extreme temperature ranges directly lead to the thermal expansion and contraction of steel structures. Under these conditions, thermal strain may be superimposed on mechanical loads, causing local stress to exceed material strength. Existing technologies that ignore thermal stress may lead to incorrect judgments about the safety of transmission towers. This embodiment provides a tower strain simulation method based on thermo-mechanical coupling, which not only considers the application of gravity loads, wind loads, and / or icing loads to the transmission tower, but also considers the application of temperature loads. Through thermo-mechanical coupling simulation, the stress state of the transmission tower under actual working conditions can be simulated more comprehensively, thereby obtaining the maximum value of the component stress of each unit under various working conditions of the transmission tower. The unit with the maximum value of the component stress exceeding the limit is selected as the weak unit of the transmission tower. Strain sensors are installed at several installation positions in the weak unit of the transmission tower, which can more accurately monitor the transmission tower and prevent damage to the transmission tower.

[0072] In one example, step S1, in establishing the finite element model of the transmission tower, requires defining the material properties of the steel structure of the transmission tower. Defining material properties refers to setting a set of properties for a material in the simulation. For example, steel comes in various specifications such as Q235, Q345, and Q420, and their material properties need to be set, including density, elastic modulus, Poisson's ratio, yield strength, stress-strain curve, etc.

[0073] In step S2 of this embodiment, gravity load, wind load and / or icing load will all exert mechanical loads on the units of the transmission tower. The transmission tower body is also connected to conductors and ground wires. The transmission tower body is composed of several steel structures fixedly connected together. In addition to the inherent load (i.e., its own gravity load), this part of the component must also bear the additional load (icing load, wind load). When conducting simulation studies, the load must be applied accurately to ensure the accuracy and effectiveness of the calculation results.

[0074] Wind loads include horizontal wind loads perpendicular to the axis of the conductor or ground wire and / or unit horizontal wind loads on the transmission tower body:

[0075] Horizontal wind load W perpendicular to the axis of the conductor or ground wire x The calculation formula is:

[0076] W x =0.625αμ sc β c (d+2δ)l H (K h v) 2 ×sin 2 θ×10 -3

[0077] In the formula, α is the wind pressure non-uniformity coefficient of the conductor or ground wire; μ sc β is the conductor or ground wire shape factor. c K is the wind load adjustment factor for the 500kV transmission line acting on the transmission tower body; h d is the wind speed height variation coefficient at the average height of the conductor or ground wire; d is the outer diameter of the conductor or ground wire; δ is the icing thickness of the conductor or ground wire; l H θ is the horizontal span of the transmission tower body; θ is the angle between the wind direction and the axis of the conductor or ground wire.

[0078] The unit horizontal wind load F of the transmission tower body t The calculation formula is:

[0079]

[0080] In the formula, k is the wind shape coefficient; k z The wind pressure height variation coefficient; k T A is the wind load adjustment factor; c The wind-blocking area of ​​the steel structure within the transmission tower body;

[0081] The formula for calculating icing load is:

[0082]

[0083] In the formula, n is the number of components connected at the component connection point; ρ is the density of the ice covering; g is the acceleration due to gravity; h z is the coefficient of variation of ice diameter with altitude; D is the diameter of the ice; l j The length of a single component.

[0084] In one example, temperatures are set for all elements of the transmission tower. Therefore, based on the aforementioned transmission tower mechanics theory, the influence of temperature on the tower's deformation is considered by adding temperature loads. Temperature-induced deformation is mainly achieved through the thermal expansion effect. The coefficient of thermal expansion of steel determines how physical quantities such as the material's length and volume change with temperature variations. First, the coefficient of thermal expansion of the material is defined to ensure that the material generates thermal stress and thermal deformation under temperature changes. A reference temperature is set as the initial temperature for zero thermal stress. Elements of the transmission tower are selected and their temperatures are set to simulate the actual temperature distribution. Static or thermal stress analysis is performed to solve for the thermal stress and thermal deformation caused by temperature changes.

[0085] According to the theory of thermal expansion, the coefficient of thermal expansion of steel is known, and temperature changes cause deformation of the material. Simply put, the coefficient of thermal expansion reflects the degree of expansion or contraction of a material when its temperature changes. The deformation of a material when its temperature changes can be described by the following formula:

[0086] ε t =α·ΔT

[0087] In the formula, ε t The thermal strain is caused by temperature change; α is the coefficient of thermal expansion of the material; ΔT = T - T0, where T is the current temperature and T0 is the reference temperature.

[0088] The total strain of each element is obtained based on the finite element model, and the calculation formula is as follows:

[0089] ε total =ε+ε t

[0090] In the formula, ε total ε is the total strain; ε is the elastic strain; ε t This is thermal strain.

[0091] σ=E(ε total -α·ΔT)

[0092] In the formula, σ is mechanical stress and E is Young's elastic modulus.

[0093] By decomposing the mechanical stress, we can obtain the tensile or compressive stress in each direction of the unit. Then, using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, we can solve the component stress and component strain in each direction of each unit under each working condition based on the control equation of elasticity.

[0094] In one example, in the finite element-based mechanical simulation calculation, it is assumed that the bottom four points of the transmission tower body are stably connected to the foundation, and the displacement of the connection points between the legs of the transmission tower body and the foundation does not change during the operation of the line. All translational and rotational degrees of freedom in the three coordinate directions need to be fixed.

[0095] In one example, for a specific transmission tower, a finite element model of the transmission tower is established using the finite element method. Material properties are defined, and the force load and thermal strain corresponding to each element of the transmission tower are taken as known quantities. The unknown variables such as displacement, strain and stress of each element are obtained, and the reliability of the transmission tower is determined accordingly.

[0096] Specifically, taking the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, the method for solving the component stress and component strain of each unit in each direction under each working condition based on the elasticity control equation is as follows:

[0097] The relationship between the stress matrix and the force load matrix corresponding to the element is established based on the equilibrium differential equations as follows:

[0098]

[0099] Where: σ x σ y σ z τ represents the stress along the x, y, and z axes of the node, with tensile stress being positive and compressive stress being negative; xy τ xz τ yz τ yx τ zx τ zy For shear stress, the subscript indicates the direction of the normal to the surface acting on the stress and the direction of the stress, for example, τ xy Let τ be the shear stress acting on a plane perpendicular to the x-axis along the y-direction, where τ xy =τ yx τ xz =τ zx τ yz =τ zy X, Y, and Z are the force load components of the element in the x, y, and z axis directions.

[0100] The relationship between the stress matrix and strain matrix corresponding to the node is established based on the material constitutive equations:

[0101]

[0102] Where: ε x ε y ε z γ yz γ xz γxy Let E be the strain component, representing the relationship between the displacement and strain of any point within an object after it has been subjected to force and deformed. Let E and v represent Young's elastic modulus and Poisson's ratio, respectively, and satisfy Hooke's law.

[0103] By inputting the force load and thermal strain corresponding to each node, the displacement of each node into the relationship between the stress matrix and the gravity matrix, the relationship between the strain matrix and the displacement matrix, and the relationship between the stress matrix and the strain matrix, the stress component in each direction of each node can be obtained.

[0104] Various operating conditions of transmission towers include multiple operating conditions under uniform settlement of the transmission tower body and multiple operating conditions under non-uniform settlement of the transmission tower body. Multiple operating conditions under uniform settlement of the transmission tower are obtained by settling one or more tower legs with a first settlement value sequence of uniform increments, and multiple operating conditions under non-uniform settlement of the transmission tower are obtained by settling one or more tower legs with a second settlement value sequence of non-uniform increments.

[0105] In one example, the method for selecting the element with the maximum value of the component stress exceeding the limit as the weak point of the transmission tower is as follows:

[0106] A first sorting table is established by arranging the stress components in descending order. Units with stress components exceeding a first threshold are extracted from the first sorting table to establish a second sorting table. All units in the second sorting table that are repeated more than the second threshold are identified as weak units of the transmission tower.

[0107] In one example, the strain sensor is a fiber Bragg grating sensor, but this embodiment does not limit this to a specific type.

[0108] The following is a detailed description of a strain simulation method for towers based on thermo-coupling provided in this embodiment, using a specific implementation method.

[0109] The modeling object is a 500kV transmission tower, 41m high with a total height of 43.4m. The monitoring system installed on this tower mainly includes: a solar and battery power supply module; a strain measurement and acquisition module; a remote host monitoring and data transmission module; and a rainproof box and clamp fixing components. Modeling results. Figure 2 As shown, the transmission tower is constrained by its legs, left-end conductor, and right-end conductor.

[0110] Performing steps S1 to S5 above, setting the wind speed to 5 m / s, the icing thickness to 10 mm, and the steel structure temperature to -2 °C in the thermo-mechanical coupling simulation model, the following results are obtained: Figure 3 The stress distribution cloud diagram of the tower-line element is shown. Figure 4The results show a comparison of strain distribution of transmission tower units obtained by mechanical simulation and thermo-mechanical coupling simulation. The simulation data shows that the strain fields obtained by the two methods have significant spatial consistency. The strain amplitude of the thermo-mechanical coupling model is smaller than that of the mechanical simulation. This is because the reference temperature is 20℃ and the steel structure temperature is -2℃. At this temperature, the steel structure produces shrinkage thermal strain. This negative thermal strain and mechanical strain form a superposition effect, which reduces the total strain value. This further proves the feasibility of the tower strain simulation method based on thermo-mechanical coupling provided in this embodiment.

[0111] When simulating uneven settlement of the tower foundations, it is assumed that foundation A does not settle, and the settlement ratio of foundations B, C, and D is 2:5:10. The settlement of foundation D gradually increases from 10mm in increments of 10mm. For ease of description, the settlement figures in this specific embodiment refer to the settlement displacement of the foundation with the largest settlement, i.e., foundation D. Under uneven settlement conditions, when the settlement reaches 100mm, the axial stress cloud diagram of the transmission tower steel structure is as follows. Figure 5 As shown.

[0112] The axial stress of the key steel structures on the tower legs connected to the first transverse diaphragm, namely, unit 1636 of leg A, unit 789 of leg B, unit 724 of leg C, and unit 1571 of leg D, varies with settlement as shown in the curves below. Figure 6 As shown.

[0113] Under uneven settlement of the tower foundation, legs A and C bear significant axial compressive stress, while legs B and D bear significant axial tensile stress. This indicates that legs A and C are compressed inward, while legs B and D are stretched outward, causing displacement and deformation of the diagonal root of the tower foundation. In this situation, the transverse diaphragms at the bottom and top of the tower body will fail first, followed by the failure of the connected diagonal and main members at the bottom of the tower body. When the settlement reaches 54 mm, the main members of the legs that have not yet settled will be the first to reach their yield stress value.

[0114] Location of Weak Points and Layout of Measuring Points on Transmission Towers: Finite element calculations reveal that while the stress component ratios vary across different locations on the transmission tower under varying operating conditions, the locations of elements with larger stress component ratios are repetitive under certain conditions. For example, under uniform icing conditions, the element number with the peak stress ratio is consistently element 1266. Under non-uniform icing conditions, elements 1266 and 1208 also repeatedly exhibit stress ratio exceeding limits. This indicates that, under different operating conditions, steel structures with repeatedly exceeding stress ratio limits are more prone to yielding compared to other locations; these steel structures are considered weak points on the transmission tower.

[0115] Based on the calculation results of various working conditions, the 100 units with the largest stress ratios were extracted and arranged in descending order according to the stress ratio of the steel structure. The units with the most repeated stress ratios and those that were prone to exceeding the limit were statistically analyzed, and their frequency of occurrence was calculated. The units with a frequency exceeding 50% were selected. Table 1 below shows the corresponding transmission tower structure units with the top 35 frequencies.

[0116] Table 1 Frequency of occurrence of weak units

[0117]

[0118] Under foundation settlement conditions, the main tower leg members will bear significant tensile and compressive stresses. Therefore, a strain sensor is installed on the tower leg to monitor the deformation of the main tower leg members. Considering that transmission line towers are spatially statically indeterminate structures, the damage to a single steel structure does not lead to the failure of the entire structure. The failure degree of auxiliary materials or inclined auxiliary materials has a smaller impact on the stability of the transmission tower than the instability of the main steel structure. Therefore, the stress and strain of the main steel structure should be the focus of monitoring. The data demodulator in the monitoring system has four channels, each containing four strain sensors. Sixteen monitoring points can be selected for strain data monitoring. The top 16 structural units with the highest frequency are selected as monitoring points, and the point layout is shown in Table 2 below.

[0119] Table 2 Sensor Placement Scheme

[0120]

[0121] Real-time strain monitoring data of the transmission tower steel structure is obtained by an online strain monitoring system. This system uses distributed fiber optic sensors to sense the mechanical state of the transmission tower structure in real time. There are 16 key stress monitoring points on the transmission tower structure, and their locations are distributed as follows: Figure 7 As shown, strain sensors are installed at monitoring points to measure the strain values ​​of the steel structure, and the data is transmitted to the online monitoring system through a data acquisition system.

[0122] When comparing and analyzing simulated strain data with measured strain data, zeroing the measurement system is crucial. In actual measurements, the strain measurement system undergoes zeroing calibration to eliminate initial errors caused by equipment deviations, environmental influences, and other factors. The measured strain data after zeroing represents the strain value relative to the initial zero point, i.e., the strain value after zeroing correction. Therefore, the simulated operating conditions also require corresponding relative operating condition processing.

[0123] Table 3 Meteorological conditions during the monitoring period

[0124]

[0125] The wind load and temperature at the zero-adjustment time were added to the model simulation to obtain the simulated strain values ​​of the steel structure at each measuring point. These strain simulation data were then used as the zero-adjustment benchmark for the simulation values. The simulation results for other working conditions were subtracted from the benchmark value to obtain the relative strain values. Finally, the simulated relative strain values ​​and measured data were compared and analyzed to verify the accuracy of the simulation results. The following data were obtained by comparing and analyzing simulation results without considering temperature, simulation results considering temperature, and simulation results with separate temperature settings for the upper and lower parts of the steel structure. Under the weather conditions of February 13, 2024, the measurement system included two temperature sensors, located at the upper and lower parts of the transmission tower structure, respectively. The temperatures measured by the temperature sensors under the specific working conditions were 5.03℃ and 4.67℃, respectively set at the upper and lower parts of the overall steel structure of the transmission tower.

[0126] Table 42 Comparison of Simulation Results

[0127]

[0128] The analysis of the above results shows that the strain values ​​corresponding to the simulation results without considering temperature are generally too large. This is because the temperature corresponding to the steel structure material property parameters is set to a standard 20℃ when temperature is not considered, while the actual temperature of the steel structure under this condition is about 5℃. The material parameters of the steel structure differ significantly from the actual properties, with the maximum error between the simulated and measured values ​​reaching 38.64με and the average relative error being 51.91%. Considering temperature, the error between the simulated and measured values ​​when the overall temperature of the steel structure is set is within 16.55με, with an average relative error of 15.03%. The error between the simulated and measured values ​​when the upper and lower temperatures of the steel structure are set is within 16.62με, with an average relative error of 15.24%. The overall error between the two is almost the same because the upper and lower temperatures of the steel structure are set to 5.03℃ and 4.67℃, respectively, with a temperature difference of only 0.36℃, resulting in minimal change in the simulation results. After considering the influence of temperature, the mechanical simulation accuracy of the transmission tower is improved by 36%. Figure 8 It can be seen that the method proposed in this invention can more accurately simulate the mechanical structure of transmission towers. This further demonstrates the accuracy of the thermo-mechanical coupling method.

[0129] Example 2

[0130] Example 2 provides a tower strain simulation system based on thermo-coupling, such as Figure 9 As shown, it includes:

[0131] The finite element model building module is used to build finite element models of transmission towers, discretizing the transmission towers into elements;

[0132] The load application module is used to set several working conditions. Under each working condition, gravity load, wind load and / or icing load are applied to the transmission tower. Based on the gravity load, wind load and / or icing load, the force load corresponding to each unit of the transmission tower is obtained. At the same time, temperature load is applied to the transmission tower, and the thermal strain corresponding to each unit of the transmission tower is obtained based on the temperature load.

[0133] The acquisition module is used to solve the component stress and component strain of each unit in each direction under each working condition based on the elasticity control equation, using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities.

[0134] The strain sensor installation module is used to obtain the stress ratio of each unit in each direction under each working condition based on the ratio of the stress ratio to the maximum value that the unit can withstand, and to select several weak units of the transmission tower with stress ratios exceeding the limit to install strain sensors.

[0135] The verification module is used to determine the reliability of the selection of weak elements in the transmission tower based on the strain of each element in each direction under each working condition.

[0136] Example 3

[0137] Example 3 provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the above-described method for simulating tower strain based on thermo-coupling.

[0138] Example 4

[0139] Example 4 provides a non-transitory computer-readable storage medium storing a computer program thereon, which, when executed by a processor, implements the above-described method for simulating tower strain based on thermo-coupling.

[0140] The memory in this embodiment of the invention is used to store various types of data to support the operation of the electronic device. Examples of such data include any computer program used to operate on the electronic device.

[0141] The strain simulation method for poles based on thermo-coupling disclosed in this invention can be applied to or implemented by a processor. The processor may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the strain simulation method based on thermo-coupling can be completed by integrated logic circuits in the processor's hardware or by instructions in software form. The processor can be a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The processor can implement or execute the methods, steps, and logic block diagrams disclosed in this invention. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly represented as execution by a hardware decoding processor, or as execution by a combination of hardware and software modules in the decoding processor. The software modules can be located in a storage medium, specifically a memory. The processor reads information from the memory and, in conjunction with its hardware, completes the steps of the strain simulation method for poles based on thermo-coupling provided in this invention.

[0142] In an exemplary embodiment, the electronic device may be implemented by one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), FPGAs, general-purpose processors, controllers, microcontrollers (MCUs), microprocessors, or other electronic components to perform the aforementioned methods.

[0143] It is understood that memory can be volatile or non-volatile, or both. Non-volatile memory can be read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), ferromagnetic random access memory (FRAM), flash memory, magnetic surface memory, optical disc, or compact disc read-only memory (CD-ROM); magnetic surface memory can be disk storage or magnetic tape storage. Volatile memory can be random access memory (RAM), which is used as an external cache. By way of example, but not limitation, many forms of RAM are available, such as Static Random Access Memory (SRAM), Synchronous Static Random Access Memory (SSRAM), Dynamic Random Access Memory (DRAM), Synchronous Dynamic Random Access Memory (SDRAM), Double Data Rate Synchronous Dynamic Random Access Memory (DDRSDRAM), Enhanced Synchronous Dynamic Random Access Memory (ESDRAM), SyncLink Dynamic Random Access Memory (SLDRAM), and Direct Rambus Random Access Memory (DRRAM). The memories described in the embodiments of the present invention are intended to include, but are not limited to, these and any other suitable types of memory.

[0144] The above embodiments are merely illustrative examples of the technical solutions of the present invention. The methods involved in the present invention are not limited to those described in the above embodiments, but are defined by the scope of the claims. Any modifications, additions, or equivalent substitutions made by those skilled in the art based on these embodiments are within the scope of protection claimed by the claims of the present invention.

Claims

1. A method for simulating tower strain based on thermo-mechanical coupling, characterized in that, include: Establish a finite element model of the transmission tower and discretize the transmission tower into elements; Several operating conditions are set. Under each condition, gravity load, wind load, and / or icing load are applied to the transmission tower. Based on the gravity load, wind load, and / or icing load, the force load corresponding to each unit of the transmission tower is obtained. Simultaneously, a temperature load is applied to the transmission tower, and based on the temperature load, the thermal strain corresponding to each unit of the transmission tower is obtained. The calculation formula is as follows: In the formula, Thermal strain caused by temperature change; The coefficient of thermal expansion of the material. , The current temperature. For reference temperature; Using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities, the component stresses and strains of each unit in each direction under each working condition are solved based on the governing equations of elasticity. The relationship between the stress matrix and the force load matrix corresponding to each unit is established based on the equilibrium differential equations: In the formula: , , Units , , In the axial direction, tensile stress is positive and compressive stress is negative; , , , , , For shear stress, the subscript indicates the direction of the normal to the surface acting on the stress and the direction of the stress, where , , , , , For the unit in , , Force load component in the axial direction; The relationship between the stress matrix and strain matrix corresponding to the node is established based on the material constitutive equations: In the formula: , , , , , For strain components, and These represent Young's modulus and Poisson's ratio, respectively. For the stress components in each unit in each direction under each working condition, the stress component ratio is obtained based on the ratio of the stress component to the maximum value that the unit can withstand. Strain sensors are installed on several weak units of the transmission tower where the stress component ratio exceeds the limit. The reliability of selecting weak elements of the transmission tower is determined based on the strain of each element in each direction under each working condition.

2. The strain simulation method for towers based on thermo-coupling according to claim 1, characterized in that, Wind loads include horizontal wind loads perpendicular to the conductor or ground wire axis and / or unit horizontal wind loads on transmission towers: Horizontal wind load perpendicular to the conductor ground wire axis The calculation formula is: In the formula, This is the coefficient for uneven wind pressure in conductors or ground wires; This is the shape factor for the conductor or ground wire; The wind load adjustment factor for 500kV power lines acting on transmission towers; The wind speed variation coefficient at the average height of the conductor or ground wire; The outer diameter of the conductor or ground wire; The thickness of ice covering the conductor or ground wire; The horizontal span of the transmission tower; The angle between the wind direction and the axis of the conductor or ground wire; Unit horizontal wind load of transmission tower The calculation formula is: In the formula, The wind shape coefficient; This is the coefficient for wind pressure height variation; This is the wind load adjustment factor; The wind-blocking area of ​​the steel structure of the transmission tower; The formula for calculating icing load is: In the formula, This refers to the number of components connected at the component connection point; The density of the ice covering; It is the acceleration due to gravity; This is the coefficient for the variation of ice diameter with altitude; The diameter of the ice layer; The length of a single component.

3. The strain simulation method for towers based on thermo-coupling according to claim 1, characterized in that, The method for measuring tensile or compressive stress in each direction of each element is as follows: The total strain of the element is obtained based on the finite element model of the transmission tower, and the calculation formula is as follows: In the formula, For total strain; For elastic strain; Thermal strain; Mechanical stress is obtained from the total strain, and the calculation formula is as follows: In the formula, Mechanical stress, It is Young's modulus of elasticity; Decomposing mechanical stress can yield tensile or compressive stresses in various directions of the element.

4. The strain simulation method for towers based on thermo-coupling according to claim 1, characterized in that: Various operating conditions of transmission towers include multiple operating conditions under uniform settlement and multiple operating conditions under non-uniform settlement. The multiple operating conditions under uniform settlement are obtained by settling one or more tower legs with a first settlement value sequence of uniform increments, and the multiple operating conditions under non-uniform settlement are obtained by settling one or more tower legs with a second settlement value sequence of non-uniform increments.

5. The strain simulation method for towers based on thermo-coupling according to claim 1, characterized in that, The method for selecting several weak elements of transmission towers with stress ratios exceeding the limit and installing strain sensors is as follows: A first sorting table is established by arranging the stress components in descending order. Units with stress components exceeding a first threshold are extracted from the first sorting table to establish a second sorting table. All units in the second sorting table that are repeated more than the second threshold are identified as weak units of the transmission tower.

6. A tower strain simulation system based on thermo-coupling, characterized in that, include: The finite element model building module is used to build finite element models of transmission towers, discretizing the transmission towers into elements; The load application module is used to set several working conditions. Under each working condition, gravity load, wind load and / or icing load are applied to the transmission tower. Based on the gravity load, wind load and / or icing load, the force load corresponding to each unit of the transmission tower is obtained. At the same time, temperature load is applied to the transmission tower, and the thermal strain corresponding to each unit of the transmission tower is obtained based on the temperature load. The acquisition module is used to solve the component stress and component strain of each unit in each direction under each working condition based on the elasticity control equation, using the force load and thermal strain corresponding to each unit of the transmission tower as known quantities. The strain sensor installation module is used to obtain the stress ratio of each unit in each direction under each working condition based on the ratio of the stress to the maximum value that the unit can withstand, and to select several weak units of the transmission tower with stress ratios exceeding the limit to install strain sensors. The verification module is used to determine the reliability of the selection of weak elements of the transmission tower based on the strain of each unit in each direction under each working condition. The thermo-coupling-based tower strain simulation system is used to execute the thermo-coupling-based tower strain simulation method according to any one of claims 1 to 5.

7. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the strain simulation method for towers based on thermo-coupling as described in any one of claims 1 to 5.

8. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that, When the computer program is executed by the processor, it implements the strain simulation method for towers based on thermo-coupling as described in any one of claims 1 to 5.

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