Method for improving train wind-induced vibration resistance of overhead line system additional wire

Abstract

According to the method for improving the train wind-induced vibration resistance of the overhead line system additional wire, the tension setting of the additional wire is adjusted by generating the installation curve of the additional wire, and it is ensured that the safety coefficient about the maximum breaking force within the service temperature range reaches the standard; the train wind power spectrum is applied to an additional wire simulation model considering tension setting and wire clamp setting; the tension of the additional wire is adjusted with the purpose of reducing the maximum stress in the wind-induced vibration process of the additional wire; then optimizing the type of the additional wire clamp; obtaining optimization results of the tension and the wire clamp type; the train wind-induced vibration resistance of the additional wire can be enhanced, so that the risk of fatigue accidents of the high-speed contact network additional wire and parts thereof is reduced, and the safety and reliability of high-speed rail operation are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of improving the anti-vibration ability of catenary additional conductors, in particular to a method for improving the anti-wind-induced vibration ability of catenary additional conductors caused by trains. Background Technique

[0002] As an important part of the catenary system without a backup, the additional conductors mainly composed of the positive feeder, protection wire, etc. will be affected by the train wind when the train passes, resulting in large-amplitude vibrations. The additional conductors and their components will accumulate fatigue damage during the vibration process, which will further lead to serious faults such as wire breakage and component failure, posing a serious threat to the safe and efficient operation of electrified railways. Therefore, it is urgent to improve the anti-wind-induced vibration ability of the additional conductors caused by trains.

[0003] At present, there are few studies on the vibration of the additional conductor system caused by train wind. Although many scholars have conducted relevant research on the buffeting or galloping phenomenon of the catenary suspension system caused by environmental wind and given various suggestions, such as increasing the tension of the suspension system, shortening the catenary span, setting up windbreak walls, etc., the above studies are all carried out under constant temperature conditions. With the change of the service temperature, the system parameters such as the tension of the uncompensated additional conductor will change significantly, which will further lead to a significant change in the anti-wind ability. Therefore, there is an urgent need for a method for improving the anti-wind ability of additional conductors considering the service temperature to comprehensively improve the reliability of additional conductors during service, thereby reducing the risk of fatigue accidents of high-speed catenary additional conductors and their components, and improving the safety and reliability of high-speed rail operation and the efficiency of operation and maintenance work. Summary of the Invention

[0004] Aiming at the problem that the anti-wind ability of the additional conductors of the high-speed railway catenary system needs to be improved in a complex service environment, the present invention proposes a method for improving the anti-wind-induced vibration ability of catenary additional conductors, taking the minimum tension of the additional conductor and the type of clamp as optimization parameters, and coordinating two optimization objectives of the safety factor of the maximum breaking force and the maximum stress to carry out an improvement design on the anti-wind ability of the additional conductor.

[0005] The present invention proposes a method for improving the anti-wind-induced vibration ability of catenary additional conductors, and the method includes the following steps: S1. Determine the installation curve of the catenary additional conductor, and obtain the maximum tension of the additional conductor within the service temperature range according to the installation curve T max and the minimum tension T min ; S2. Judge the additional conductor regarding the maximum breaking force F breakWhether the safety factor is greater than 2.5. If not, reduce the minimum tension corresponding to the additional conductor at the highest temperature, return to step S1, and re-determine the installation curve of the additional conductor with the reduced minimum tension; if so, uniformly select tension value calculation points within the range of T min , T max , and establish a simulation model of the additional conductor within the full service temperature range; S3. Obtain the train wind force spectrum, substitute the train wind force spectrum into the additional conductor simulation model, reproduce the train wind-induced vibration process of the additional conductor, and extract the maximum stress ε that appears in the additional conductor during this process max ; S4. Determine whether ε max exceeds the tensile strength ε of each strand of the additional conductor break . If not, execute step S5; if so, determine whether there is further adjustment margin for the minimum tension. If there is, further adjust the minimum tension, return to step S1, and re-determine the installation curve of the additional conductor with the adjusted minimum tension; if there is no further adjustment margin for the minimum tension, execute step S5; S5. Replace the clamp of the additional conductor and find the clamp type that minimizes ε max .

[0006] Furthermore, the method for determining the installation curve of the catenary additional conductor is as follows: ; In the formula, T is the installation curve of the additional conductor, θ is the temperature, θ 0 is the given temperature, T 0 is the given tension of the additional conductor corresponding to the given temperature, is the linear expansion coefficient of the additional conductor; E is the final elastic modulus of the additional conductor; S is the calculated cross-sectional area of the additional conductor; g is the self-weight load of the additional conductor; L D is the equivalent span of the additional conductor.

[0007] Furthermore, the additional conductor simulation model is established using the finite element method. The additional conductor is simulated using Timoshenko beam elements, and the clamp type setting is simulated by the end constraint method of the additional conductor simulation model to obtain the dynamic characteristics of the additional conductor under its own gravity and train wind.

[0008] Furthermore, the method for obtaining the train wind force spectrum is as follows: Obtain the train length L trThe extreme values of the train wind speed at the nose and tail of the train when passing through the installation location of the additional conductor V pn and V pt form the train wind speed spectrum; Obtain the train running speed v and air density ρ and the resistance coefficient of the additional conductor C D to form the train wind force spectrum of the additional conductor in combination with the train wind speed spectrum.

[0009] Furthermore, the train wind speed spectrum is given by the following formula: ; wherein, x' is the position coordinate with the nose of the train as the origin and the forward direction of the nose as the positive direction.

[0010] Furthermore, the train wind force spectrum D ( x ) is given by the following formula: ; wherein, t is time. Taking the end of the additional conductor closer to the nose of the train at the initial moment as the proximal end of the additional conductor, L 0 is the initial distance between the nose of the train and the proximal end of the additional conductor at the initial moment, x is the position coordinate with the proximal end of the additional conductor as the origin and the train running direction as the positive direction, A is the windward area of the additional conductor, represents the train wind speed spectrum at a distance of from the nose of the train during the train running process.

[0011] Furthermore, when initially determining the installation curve of the overhead contact line additional conductor in step S1, the given temperature θ 0 is the typical service temperature or the lowest service temperature, and the corresponding given additional conductor tension T 0 are the tension at the typical service temperature and the maximum tension corresponding to the lowest service temperature respectively.

[0012] Furthermore, the method for judging whether there is a further adjustment margin for the minimum tension is as follows: Adjust the minimum tension and judge whether the safety factor of the additional conductor with respect to the maximum breaking force F break is greater than 2.5 within the service temperature range, and whether ε max is less than ε break hold simultaneously. If so, it means that there is a further adjustment margin for the minimum tension.

[0013] Further, the safety factor of the additional conductor with respect to the maximum breaking force F break is the ratio of the maximum breaking force of the additional conductor of this type F break to its maximum tension within the service temperature range T max .

[0014] The advantages and positive effects of the present invention are as follows: The method for improving the anti-train-wind-induced vibration ability of the catenary additional conductor provided by the present invention coordinates two optimization objectives, namely the safety factor of the maximum breaking force and the maximum stress during the train-wind-induced vibration of the additional conductor. By adjusting the minimum tension of the additional conductor at the highest service temperature and the type of the clamp of the additional conductor, it is ensured that the anti-train-wind-induced vibration ability of the additional conductor is improved within the entire service temperature range, and the safety and reliability of the catenary system are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The technical solutions of the present invention will be further described in detail below in conjunction with the drawings and embodiments. However, it should be understood that these drawings are only designed for the purpose of explanation and therefore do not limit the scope of the present invention. In addition, unless otherwise specified, these drawings are only intended to conceptually illustrate the structural configurations described herein and are not necessarily drawn to scale.

[0016] Figure 1 is a flowchart of the method for improving the anti-train-wind-induced vibration ability of the catenary additional conductor provided by the embodiment of the present invention; Figure 2 is the installation curve of the additional conductor provided by the embodiment of the present invention; Figure 3 is a comparison schematic diagram of the parametric train-wind velocity spectrum model and the CFD calculation results provided by the embodiment of the present invention; Figure 4 is a simulation reproduction schematic diagram of the train-wind-induced vibration process of the additional conductor provided by the embodiment of the present invention; Figure 5 is a schematic diagram of the safety factor and the maximum stress of the maximum breaking force with only tension optimization provided by the embodiment of the present invention; Figure 6 is a schematic diagram of the optimization effect of the comparative example provided by the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To make the purpose, technical solutions, and advantages of the present invention more clear, the following will describe the technical solutions in the embodiments of the present invention in more detail with reference to the accompanying drawings in the embodiments of the present invention. In the drawings, the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions from beginning to end. The described embodiments are some embodiments of the present invention, not all of them. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present invention and should not be construed as a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0018] The following will describe the embodiments of the present invention in detail with reference to the accompanying drawings.

[0019] This embodiment provides a method for improving the anti-wind-induced vibration ability of catenary additional conductors, and the method includes the following steps: S1. Determine the installation curve of the catenary additional conductor, and obtain the maximum tension of the additional conductor within the service temperature range according to the installation curve T max and the minimum tension T min ; S2. Judge whether the safety factor of the additional conductor with respect to the maximum breaking force F break is greater than 2.5. If not, reduce the minimum tension corresponding to the additional conductor at the highest temperature T min , return to step S1, and re-determine the installation curve of the additional conductor with the reduced minimum tension; if so, within T min , T max uniformly select tension value calculation points, and establish a simulation model of the additional conductor within the full service temperature range; It should be noted that the safety factor of the additional conductor with respect to the maximum breaking force F break is the ratio of the maximum breaking force F break of this type of additional conductor and its maximum tension within the service temperature range T max ; the additional conductor simulation model is established by the finite element method, the additional conductor is simulated by Timoshenko beam elements, and the type of clamp is set by simulating the end constraint method of the additional conductor simulation model, so as to obtain the dynamic characteristics of the additional conductor under its own gravity and train wind action; S3. Obtain the train wind force spectrum, substitute the train wind force spectrum into the simulation model of the additional conductor within the full service temperature range, reproduce the train wind-induced vibration process of the additional conductor, and extract the maximum stress ε that appears in the additional conductor during this process. max ; S4. Judge whether ε max exceeds the tensile strength ε break of each strand of the additional conductor. If not, execute step S5; if so, judge whether there is room for further adjustment of the minimum tension. If there is, further adjust the minimum tension, return to step S1, and re-determine the installation curve of the additional conductor with the adjusted minimum tension; if not, execute step S5. It should be noted that the method for judging whether there is room for further adjustment of the minimum tension is as follows: adjust the minimum tension, and judge that within the service temperature range, the safety factor of the additional conductor with respect to the maximum breaking force F break is greater than 2.5, and whether ε max is less than ε break hold simultaneously. If so, it means that there is room for further adjustment of the minimum tension.

[0020] S5. Replace the clamp of the additional conductor, find the clamp type that makes ε max the smallest, so as to obtain the optimization result.

[0021] Specifically, the method for determining the installation curve of the catenary additional conductor described in step S1 is as follows: ; In the formula, T is the installation curve of the additional conductor, θ 0 is the given temperature, T 0 is the given additional conductor tension corresponding to the given temperature, θ is the temperature, is the linear expansion coefficient of the additional conductor; E is the final elastic coefficient of the additional conductor; S is the calculated cross-sectional area of the additional conductor; g is the self-weight load of the additional conductor; L D is the equivalent span of the additional conductor; it should be noted that when initially determining the installation curve of the catenary additional conductor, the given temperature θ 0 is the typical service temperature or the lowest service temperature, and the corresponding given additional conductor tension T 0 are the tensions at the typical service temperature and the maximum tension corresponding to the lowest service temperature respectively. These two sets of data are both inherent parameters of the catenary additional conductor; The method for obtaining the train wind force spectrum described in step S3 is as follows: Obtain the train length Ltr The extreme values of the train wind speed at the nose and tail of the train when passing through the installation location of the additional conductor V pn and V pt form the train wind speed spectrum; Obtain the train running speed v and ρ the air density C D and the resistance coefficient of the additional conductor, and combine with the train wind speed spectrum to form the train wind force spectrum of the additional conductor; Among them, the train wind speed spectrum is given by the following formula: ; In the formula, x' is the position coordinate with the nose of the train as the origin and the forward direction of the nose as the positive direction; It can be considered that there are three ways to obtain the extreme values of the train wind speed at the nose and tail of the train when passing through the installation location of the additional conductor V pn and V pt : Method 1 is to extract the V pn and V pt at the installation position of the additional conductor according to the CFD simulation calculation results; Method 2 is to give the V pn and V pt according to the on-site measured results of the train wind speed at the installation position of the additional conductor; Method 3 is to reverse deduce the V pn and V pt from the measured results such as the displacement amplitude during the vibration of the additional conductor caused by the train wind. The specific process is as follows: continuously adjust the V pn and V pt to conduct a finite element simulation calculation of the vibration of the additional conductor caused by the train wind, and finally calibrate the V pn and V pt with a high degree of coincidence between the simulation results and the measured results of the displacement amplitude; of course, to consider the occurrence of extreme situations, a certain coefficient can be multiplied on the basis of the given V pn and V pt original values; The train wind force spectrum D ( x ) is given by the following formula: ; In the formula, t is time. Taking the end of the additional wire closer to the nose of the train at the initial moment ( t = 0 s) as the proximal end of the additional wire, L 0 is the initial distance between the nose of the train and the proximal end of the additional wire at the initial moment, x is the position coordinate with the proximal end of the additional wire as the origin and the train running direction as the positive direction, A is the windward area of the additional wire, represents the train wind speed spectrum at a distance of from the nose of the train during the train running; in this embodiment, the windward area of the additional wire is the product of the cross-sectional diameter of the additional wire and the length of the beam element of the finite element model; As an example, in this embodiment, when initially determining the installation curve of the additional wire, as Figure 2 shown, the installation curve corresponding to θ 0 = 20 °C and T 0 = 4 kN is given; when the safety factor of the additional wire with respect to the maximum breaking force F break is not greater than 2.5, it is necessary to reduce the minimum tension T min corresponding to the additional wire at the highest temperature. Regarding the adjustment strategy of T min corresponding to the additional wire at the highest temperature, T max = 0.4 F break can be substituted into the obtained installation curve of the additional wire to calculate the upper limit of the value of T min , and on this basis, T min is reduced, and the installation curve of the additional wire is re-determined with the reduced minimum tension; when establishing the simulation model of the additional wire within the full service temperature range, this embodiment is at T min , T maxWithin the range of [], 11 tension value calculation points were evenly selected, and for each tension value calculation point, a simulation model of the additional conductor was established using the finite element method. In the simulation model of the additional conductor, the additional conductor was simulated using Timoshenko beam elements, and the parameters of the beam elements were determined by parameters such as the calculated cross-sectional area, cross-sectional diameter, line mass, and ultimate elastic modulus of the additional conductor. The clamps of the additional conductor were equivalent to the constraints at both ends of the additional conductor. In this example, referring to the traditional boat-shaped clamp, full constraints were applied to both ends of the additional conductor; when obtaining the train wind spectrum, the construction of the train wind speed spectrum was based on the analysis and feature extraction of the CFD simulation numerical calculation results of the train wind speed. The CFD numerical calculation results of the train wind speed showed that there were significant wind speed peaks in the nose region and the tail region of the train, while the wind speed in the middle section of the train was very small. The nose peak wind speed V pn and the tail peak wind speed V pt Two key characteristic parameters were used to construct a parametric train wind speed spectrum , and the comparison between the CFD calculation results of the train wind speed spectrum and the parametric model is as Figure 3 shown; when reproducing the train wind-induced vibration process of the additional conductor, the time term t , the coordinate values of each node in the simulation model of the additional conductor, and the average value of the lengths of the two elements connected by the node were substituted into the train wind spectrum, and the time history curve of the train wind load for each node could be obtained. Based on dynamic integration methods such as NEWMARK-β, the vibration process of the additional conductor with different tensions under the train wind load could be reproduced. Figure 4 Figure 14 is a schematic diagram of the vibration process of the finite element model of the additional conductor at a certain tension value point. It should be noted that the maximum stress ε max during the train wind-induced vibration process of the additional conductor mostly occurs at the outer grid points of the beam element cross-section near the clamp; in this example, the initial clamp type is the boat-shaped clamp, which is equivalent to the full constraint condition. The preferred clamps include pre-hinged armored clamps with a certain torsional stiffness and pre-hinged rotatable anti-fatigue support clamps with full rotational freedom release. The optimization parameters are the T min of the additional conductor and the clamp type. The optimization goal is to reduce ε max and ensure that the safety factor regarding the maximum breaking force F break is greater than 2.5. Through the method of this embodiment, as shown in Table 1, the T min and the preferred results of the clamp type for three typical models of additional conductors are given; Table 1

[0022] In the optimization process of the present invention, the optimal tension setting of the additional conductor is given first, and on this basis, the optimal type of the clamp for the additional conductor is given. As a comparison, Figure 5 the maximum stress of the additional conductor and the safety factor with respect to the maximum breaking force are given after only adopting the optimal tension result, and the additional conductors of three typical models still satisfy ε max < ε break and with respect to the maximum breaking force F break the safety factor is greater than 2.5, that is, only optimizing the tension can improve the wind resistance of the additional conductor; Figure 6 The maximum stress time history curves of the original design and the optimized design are compared, which proves that the method of this embodiment can greatly reduce the maximum stress of the additional conductor during the train-induced vibration process and significantly improve the wind resistance of the additional conductor.

[0023] Finally, it should be pointed out that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting it. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. Method for enhancing the anti-wind-induced vibration ability of overhead catenary additional conductors, characterized in that, The method includes the following steps: S1. Determine the installation curve of the OCS additional conductor, and obtain the maximum tension and minimum tension of the additional conductor within the service temperature range according to the installation curve. T max T min ; S2. Determine the safety factor of the additional conductor with respect to the maximum breaking force F break Is it greater than 2.5? If not, reduce the minimum tension corresponding to the additional conductor at the highest temperature, return to step S1, and re-determine the installation curve of the additional conductor with the reduced minimum tension; if so, in T min , T max , uniformly select tension value calculation points within the range, and establish a simulation model of the additional conductor within the full service temperature range; S3. Obtain the train wind spectrum, substitute the train wind spectrum into the additional conductor simulation model, reproduce the train wind-induced vibration process of the additional conductor, and extract the maximum stress ε that appears in the additional conductor during this process max ; S4. Determine ε max whether it exceeds the tensile strength ε break of each strand of the additional conductor. If not, execute step S5; if so, determine whether there is room for further adjustment of the minimum tension. If there is, further adjust the minimum tension, return to step S1, and re-determine the installation curve of the additional conductor with the adjusted minimum tension; if there is no room for further adjustment of the minimum tension, execute step S5; S5. Replace the clamp of the additional conductor and find the clamp type that minimizes ε max to the minimum.

2. The method for improving the anti-wind-induced vibration ability of the catenary additional conductor according to claim 1, wherein, The method for determining the installation curve of the OCS additional wire is as follows: ； Wherein, T is the installation curve of the additional conductor; θ is the temperature; θ 0 is the given temperature; T 0 is the given additional conductor tension corresponding to the given temperature; is the coefficient of linear expansion of the additional conductor; E is the ultimate elastic modulus of the additional conductor; S is the calculated cross-sectional area of the additional conductor; g is the self-weight load of the additional conductor; L D is the equivalent span of the additional conductor.

3. The method for improving the anti-train-wind-induced vibration ability of the overhead contact line's additional conductor according to claim 1, characterized in that, The additional wire simulation model is established by the finite element method. The additional wire is simulated by Timoshenko beam elements, and the type setting of the clamp is simulated by the end constraint method of the additional wire simulation model to obtain the dynamic characteristics of the additional wire under its own gravity and train wind action.

4. The method for improving the anti-wind-induced vibration ability of the overhead contact line's additional conductor according to claim 1, wherein The method for obtaining the train wind force spectrum is as follows: Obtain the train length L tr , the extreme values of the train wind speed at the nose and the tail of the train when passing through the additional wire installation location V pn and V pt , to form a train wind speed spectrum Obtain the train running speed v , air density ρ and additional wire resistance coefficient C D , and combine with the train wind speed spectrum to form the train wind force spectrum of the additional wire.

5. The method for enhancing the anti-wind-induced vibration ability of the catenary additional conductor according to claim 4, wherein The train wind speed spectrum is given by the following formula: ； In the formula, x' is the position coordinate with the train nose as the origin and the forward direction of the nose as the positive direction.

6. The method for improving the anti-train-wind-induced vibration ability of the catenary additional conductor according to claim 5, characterized in that The train wind spectrum D ( x ) is given by the following formula: ； Wherein, t is the time. Taking the end of the additional conductor closer to the nose of the train at the initial moment as the proximal end of the additional conductor, L 0 is the initial distance between the nose of the train and the proximal end of the additional conductor at the initial moment, x is the position coordinate with the proximal end of the additional conductor as the origin and the train running direction as the positive direction, A is the windward area of the additional conductor, represents the train wind speed spectrum at a distance of from the nose of the train during the train running.

7. The method for enhancing the anti-wind-induced vibration ability of the additional conductor of the overhead catenary according to claim 2, wherein When initially determining the installation curve of the OCS additional conductor in step S1, the given temperature θ 0 is the typical service temperature or the lowest service temperature, and the corresponding given additional conductor tension T 0 are the tension at the typical service temperature and the maximum tension corresponding to the lowest service temperature respectively.

8. The method for enhancing the anti-wind-induced vibration ability of the additional conductor of the catenary according to claim 1, characterized in that, The method for judging whether there is a further adjustment margin for the minimum tension is as follows: Adjust the minimum tension and determine whether the safety factor of the additional conductor with respect to the maximum breaking force within the service temperature range is greater than 2.5 and whether ε F break is less than ε max If both conditions are satisfied simultaneously, it indicates that there is room for further adjustment of the minimum tension. break ​ 9. The method for improving the anti-wind-induced vibration ability of the additional conductor of the catenary according to claim 1, characterized in that The safety factor of the additional conductor with respect to the maximum breaking force F break is the ratio of the maximum breaking force of the additional conductor F break to the maximum tension of the additional conductor within the service temperature range T max of the ratio.

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