DYNAMIC RESPONSES OF TRANSMISSION TOWER-LINE SYSTEM UNDER ICE SHEDDING

2010 ◽  
Vol 10 (03) ◽  
pp. 461-481 ◽  
Author(s):  
FENGLI YANG ◽  
JINGBO YANG ◽  
JUNKE HAN ◽  
DONGJIE FU
Keyword(s):  
Transmission Lines ◽  
Element Model ◽  
Dynamic Responses ◽  
Ice Thickness ◽  
Transmission Tower ◽  
Line System ◽  
Calculated Load ◽  
Ice Shedding ◽  
Stress Ratios ◽  
Phase Conductors

Ice shedding from conductors may easily induce electrical and mechanical accidents, which cause a serious threat to the safe operation of transmission lines. In this paper, a 3D finite element model of tower-conductor-ground wire-insulator system was established in ANSYS, and the dynamic responses of ice shedding under different cases were analyzed for a transmission tower-line system. The computed jumping heights are in excellent agreement with the experimental values of a two span conductors model. Many variables were considered in the ice-shedding simulations that include tower-line coupled effect, phase combination of the ice-shedding conductors, thickness of the accreted ice, length of the ice-shedding span as well as elevation difference. Influences of all the variables on the dynamic responses of jumping heights, loads at the end of insulators and the forces of transmission tower were studied. Ice-shedding simulations of an actual 500 kV transmission line section which experience failure under ice shedding in 2008 were performed. The results show that stress ratios of members at the tower head under design ice thickness exceed the limiting values when the amount of shedding ice is large. For ice shedding at the top phase conductors, the jumping height and unbalanced tension at the end of insulator can be reduced by applying interphase spacers in triangular arrangement. The tower is in a safe state under the load of the design ice thickness. In order to prevent ice-shedding accidents, interphase spacers should be used, and the weak members at the tower head should be strengthened according to the calculated load values at the end of insulators.

scholarly journals Collapse Analysis of a Transmission Tower-Line System Induced by Ice Shedding

2021 ◽  
Vol 9 ◽  
Author(s):  
Jiaxiang Li ◽  
Biao Wang ◽  
Jian Sun ◽  
Shuhong Wang ◽  
Xiaohong Zhang ◽  
...  
Keyword(s):  
Finite Element ◽  
Transmission Lines ◽  
Progressive Collapse ◽  
Element Model ◽  
Transmission Tower ◽  
Line System ◽  
Finite Element Software ◽  
Transmission Towers ◽  
Ice Shedding ◽  
The Impact

Ice shedding causes transmission lines to vibrate violently, which induces a sharp increase in the longitudinal unbalanced tension of the lines, even resulting in the progressive collapse of transmission towers in serious cases, which is a common ice-based disaster for transmission tower-line systems. Based on the actual engineering characteristics of a 500 kV transmission line taken as the research object, a finite element model of a two-tower, three-line system is established by commercial ANSYS finite element software. In the modeling process, the uniform mode method is used to introduce the initial defects, and the collapse caused by ice shedding and its influencing parameters are systematically studied. The results show that the higher the ice-shedding height is, the greater the threat of ice shedding to the system; furthermore, the greater the span is, the shorter the insulator length and the greater the dynamic response of the line; the impact of ice shedding should be considered in the design of transmission towers.

Research on Dynamic Responses of a Transmission Tower under Monsoon Wind

2015 ◽  
Vol 744-746 ◽  
pp. 248-252
Author(s):  
Wen Ping Xie ◽  
Bo Chen ◽  
Peng Yun Li ◽  
Xiao Fen Gong
Keyword(s):  
Element Model ◽  
Dynamic Responses ◽  
Structural Performance ◽  
Wind Loading ◽  
Transmission Tower ◽  
Line System ◽  
Commercial Package ◽  
Structural Responses ◽  
Monsoon Wind ◽  
The Finite Element Model

The research on dynamic responses of a transmission tower under monsoon wind is actively carried out in this study. A real transmission tower-line system constructed in the southern coastal areas of China is taken as an example to investigate the structural performance subjected to monsoon wind. The finite element model of the transmission tower-line system is established with the aiding of commercial package. The equation of motion of the transmission tower-line system under monsoon wind is established. The dynamic wind loading are applied on the tower-line system to examine the structural responses.

Dynamic Behavior of Transmission Tower-Line Systems Subjected to Insulator Breakage

2018 ◽  
Vol 18 (03) ◽  
pp. 1850036 ◽  
Author(s):  
Jia-Xiang Li ◽  
Hong-Nan Li ◽  
Xing Fu
Keyword(s):  
Parametric Analysis ◽  
Failure Process ◽  
Element Model ◽  
Dynamic Responses ◽  
Span Length ◽  
Transmission Tower ◽  
Line System ◽  
Ice Load ◽  
Dynamic Analyses ◽  
Ice Loads

Ice loads attached to a transmission tower-line system can not only increase the vertical loads on the insulators, but also cause flashover to occur more easily. Both effects can lead to an increased probability of insulator breakage. In this paper, a finite-element model of a transmission tower-line system with three towers and four span lines under the ice loads is established. Dynamic analyses of the tower-line system after insulator breakage are performed to study the dynamic responses of the system and its failure process. In addition, a parametric analysis is conducted to investigate the influence of span length and insulator length on the vibration of the system and the failure mode. The results show that a larger ice load can lead to more severe vibration of the tower-line system due to the insulator breakage. Moreover, as the span length increases, the insulator breakage can result in more serious consequences and even the cascading collapse of the transmission tower-line system. This study provides crucial reference for preventing the failure of transmission tower-line systems in heavy ice regions.

Evaluation on Dynamic Responses of Transmission Lines Subjected to Wind Excitations

2015 ◽  
Vol 744-746 ◽  
pp. 82-87
Author(s):  
Peng Yun Li ◽  
Bo Chen ◽  
Wen Ping Xie ◽  
Hao Liu
Keyword(s):  
Transmission Lines ◽  
Structural Model ◽  
Dynamic Responses ◽  
Induced Response ◽  
Transmission Tower ◽  
Line System ◽  
Long Span ◽  
Commercial Package ◽  
Element Approach ◽  
Strong Winds

The evaluation on dynamic responses of transmission lines subjected to wind excitations is actively carried out in this study. A transmission tower-line system constructed in the southern coastal areas of China is taken as example to examine the wind induced response of the transmission lines. The structural model is established based on finite element approach by using commercial package. The displacement, velocity and acceleration responses of the transmission lines are computed to explore structural performance. The made observations indicate that the transmission lines vibrant substantially when subjected to strong winds. It is obvious that the dynamic responses of the ground wire are smaller than those of the wire and the responses in the long span are much larger than those in the short span.

scholarly journals The Effect Analysis of Strain Rate on Power Transmission Tower-Line System under Seismic Excitation

2014 ◽  
Vol 2014 ◽  
pp. 1-10
Author(s):  
Li Tian ◽  
Wenming Wang ◽  
Hui Qian
Keyword(s):  
Strain Rate ◽  
Power Transmission ◽  
Seismic Analysis ◽  
Three Dimensional ◽  
Element Model ◽  
Seismic Excitation ◽  
Transmission Tower ◽  
Base Shear ◽  
Effect Analysis ◽  
Line System

The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A three-dimensional finite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis and numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate the effect of strain rate on the nonlinear responses of the transmission tower and line. The results show that the effect of strain rate on the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear forces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect of strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines considering strain rate effect are larger than those of the conductors. The results could provide a reference for the seismic design of the transmission tower-line system.

Gust Response Factor of a Transmission Tower Under Typhoon

2020 ◽  
pp. 2150001
Author(s):  
Xing Fu ◽  
Wen-Long Du ◽  
Hong-Nan Li ◽  
Wen-Ping Xie ◽  
Kai Xiao ◽  
...  
Keyword(s):  
Wind Speed ◽  
Field Measurements ◽  
Element Model ◽  
Structural Safety ◽  
Transmission Tower ◽  
Response Factors ◽  
Line System ◽  
Transmission Towers ◽  
Synoptic Wind ◽  
Gust Response

The gust response factors (GRFs) of transmission towers in current standards are reviewed for synoptic winds. The collapse of most transmission towers has occurred under the high-intensity wind (HIW) caused by events such as typhoons, hurricanes, and downbursts. Thus, this paper studies the GRF of a transmission tower under the typhoon. First, the definition of GRF and its extended form for the transmission towers are developed. Then the wind speed simulation of a typhoon event is introduced. Based on the structural health monitoring (SHM) system installed on tower #32, the measured GRFs under the super typhoon Mangkhut are calculated. Then the finite element model (FEM) of the transmission tower-line system is established to simulate the dynamic response to further calculate the GRFs, which agrees well with the field measurements. Both the field measurement and simulation results show that the GRFs under the typhoon are larger than those under the synoptic wind and that the recommended GRFs in the Chinese standard underestimate the peak responses. Finally, a parametric analysis is performed, which demonstrates that the turbulence intensity, wind speed, and power-law exponent all have great effects on the GRFs of transmission towers. In the HIW-prone areas, it is recommended that the characteristics of the HIW can be considered in improving the GRF values to guarantee the structural safety of transmission towers.

Fragility analysis of a long-span transmission tower–line system under wind loads

2020 ◽  
Vol 23 (10) ◽  
pp. 2110-2120
Author(s):  
Li Tian ◽  
Xin Zhang ◽  
Xing Fu
Keyword(s):  
Damage Index ◽  
Element Model ◽  
Attack Angle ◽  
Fragility Analysis ◽  
Wind Loads ◽  
Collapse Mechanism ◽  
Ultimate Capacity ◽  
Transmission Tower ◽  
Line System ◽  
Long Span

Numerous transmission towers have collapsed due to experiencing strong winds; therefore, the purpose of this article is to investigate the collapse mechanism and the anti-collapse performance of a long-span transmission tower–line system. The detailed finite element model of a typical tower–line system is established in ABAQUS. A global damage index is proposed to quantitatively estimate the overall damage of the structure and define the collapse criteria. An incremental dynamic analysis is performed to obtain the collapse mechanism and the ultimate capacity of the structure. Subsequently, a fragility analysis for evaluating the anti-collapse performance is conducted due to the uncertainty of wind loads. Eventually, the influence of the wind attack angle and the length of the side spans on the fragility is discussed. The results demonstrate that the proposed global damage index is capable of quantitatively reflecting the overall damage and assessing the ultimate capacity of the structure. In addition, the uncertainty of the wind load has a significant influence on the ultimate capacity and the failure position. Furthermore, the results reveal that the wind attack angle and the length of the side spans have an apparent effect on the fragility of the structure.

A Bidirectional Pounding Tuned Mass Damper and Its Application to Transmission Tower-Line Systems under Seismic Excitations

2019 ◽  
Vol 19 (06) ◽  
pp. 1950056 ◽  
Author(s):  
Li Tian ◽  
Kunjie Rong ◽  
Kaiming Bi ◽  
Peng Zhang
Keyword(s):  
Element Model ◽  
Tuned Mass Damper ◽  
Seismic Intensity ◽  
Design Parameters ◽  
Seismic Responses ◽  
Transmission Tower ◽  
Control Effect ◽  
Seismic Excitations ◽  
Line System ◽  
Mass Damper

Failures of transmission tower-line systems have frequently occurred during large earthquakes. It is essential to control the excessive vibrations of transmission tower-line systems to ensure their safe operation in such events. This paper numerically investigates the effectiveness of using a novel bidirectional pounding tuned mass damper (BPTMD) to control the seismic responses of transmission tower-line system when subjected to earthquake ground motions. A finite element model of a typical transmission tower-line system with BPTMD is developed using the commercial software ABAQUS, with the accuracy of the results verified against a previous study. The seismic responses of the system with and without BPTMD are calculated. For comparison, the control effect of using the conventional bidirectional tuned mass damper is also calculated and discussed. Finally, a parametric study is performed to investigate the effects of the mass ratio, seismic intensity, gap size and frequency ratio on the seismic response of the system, while optimal design parameters are obtained.

Analysis on the Dynamic Responses of the Broken Conductors in Transmission Lines

2011 ◽  
Vol 50-51 ◽  
pp. 511-515 ◽  
Author(s):  
Feng Li Yang ◽  
Jing Bo Yang
Keyword(s):  
Transmission Lines ◽  
Element Model ◽  
Dynamic Responses ◽  
Impact Loads ◽  
Safe Operation ◽  
Rayleigh Damping ◽  
Fea Model ◽  
Insulator Element ◽  
Reaction Forces ◽  
Short Time

Impact loads from the broken conductors are common for transmission lines, which can bring threaten to the safe operation of the transmission lines. Dynamic analysis of the conductors in transmission lines under broken load was carried out. A finite element model of seven span conductors in transmission line was established in general software ANSYS. The insulator and the phase spacer were considered in the FEA model. The broken load case can be realized by the birth-death element method in ANSYS. Stiffness of the broken conductor or insulator element was changed to be a near zero value in a very short time. Effect of the damping property of the conductors was considered by the Rayleigh damping method. Dynamic responses of displacements at the broken points and the reaction forces of the insulators were obtained. Dynamic responses for the broken conductors with different damping ratios and bundle numbers were compared.

scholarly journals Nonlinear Seismic Behavior of Different Boundary Conditions of Transmission Line Systems under Earthquake Loading

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Li Tian ◽  
Xia Gai
Keyword(s):  
Boundary Conditions ◽  
Transmission Line ◽  
Transmission Lines ◽  
Seismic Analysis ◽  
Time History ◽  
Nonlinear Time History Analysis ◽  
Earthquake Loading ◽  
Transmission Tower ◽  
Line System ◽  
Different Boundary Conditions

Nonlinear seismic behaviors of different boundary conditions of transmission line system under earthquake loading are investigated in this paper. The transmission lines are modeled by cable element accounting for the nonlinearity of the cable. For the suspension type, three towers and two span lines with spring model (Model 1) and three towers and four span lines’ model (Model 2) are established, respectively. For the tension type, three towers and two span lines’ model (Model 3) and three towers and four span lines’ model (Model 4) are created, respectively. The frequencies of the transmission towers and transmission lines of the suspension type and tension type are calculated, respectively. The responses of the suspension type and tension type are investigated using nonlinear time history analysis method, respectively. The results show that the responses of the transmission tower and transmission line of the two models of the suspension type are slightly different. However, the responses of transmission tower and transmission line of the two models of the tension type are significantly different. Therefore, in order to obtain accurate results, a reasonable model should be considered. The results could provide a reference for the seismic analysis of the transmission tower-line system.

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