In-plane free vibrations of multi-span transmission lines

2019 ◽  
Vol 46 (12) ◽  
pp. 1114-1127
Author(s):  
Liming Qi ◽  
Ameng Xu ◽  
Xiaohui Liu
Keyword(s):  
Transmission Line ◽  
Natural Frequency ◽  
Transmission Lines ◽  
Geometrical Parameter ◽  
Main Idea ◽  
Vertical Motion ◽  
Theoretical Method ◽  
Free Vibrations ◽  
Theoretical Expression ◽  
Theoretical Formulation

A theoretical method of in-plane mode and natural frequency of multi-span transmission lines is presented. The main idea is to establish moment balance equations of each insulator string and in-plane vertical motion equation of each span in multi-span section when the effect of conductor inertia component parallel to the chord on the additional horizontal tension of conductor is considered. The validity of theoretical mode and natural frequency is demonstrated by consistency with the numerical results of a typical five-span transmission line based on ABAQUS. It is shown that the mode of the five-span transmission line with a larger elasto-geometrical parameter exhibits asymmetrical shape that differed from those of single-span conductor. Considering the complexity of the theoretical expression, a simplified theoretical formulation of the modes and natural frequencies of multi-span transmission lines is obtained. Based on the curve of the frequency changing with the elasto-geometrical parameter, the various internal resonance conditions are discussed.

Electromagnetic Power Extraction of Transmission Lines

2013 ◽  
Vol 339 ◽  
pp. 595-601
Author(s):  
Eden L. Carvalho Junior ◽  
Germano Lambert-Torres ◽  
Erik L. Bonaldi ◽  
Levy E.L. de Oliveira ◽  
Jonas G. Borges da Silva ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Transmission Line ◽  
Transmission Lines ◽  
Laboratory Tests ◽  
Main Idea ◽  
Physical Contact ◽  
Power Lines ◽  
Power Extraction ◽  
Electromagnetic Power ◽  
Small Powers

The main idea of this project is to feed small loads along the lines of the TBE - Brazilian Energy Transmission with retreat directly from power lines without any physical contact. This paper presents the system for extracting small powers of the transmission line through electromagnetic effects. Initially, the mathematical modeling of extraction is presented, to then show some aspects of construction and prototype control. Some results of laboratory tests of the prototype are presented with various operating situations analysis. This equipment was installed experimentally in one of the lines of TBE and the current results are shown in this paper.

An Evaluation of Pneumatic Transmission Line Propagation Functions

1974 ◽  
Vol 96 (1) ◽  
pp. 77-87 ◽  
Author(s):  
A. E. Churches ◽  
E. C. Hind ◽  
R. A. A. Bryant
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Line Length ◽  
Theoretical Expression ◽  
Working Fluid ◽  
Frequency Range ◽  
Wide Range ◽  
Gauge Pressure ◽  
Propagation Function ◽  
Best Fit

The results of pressure response tests are given for a wide range of dead-ended pneumatic transmission lines. The tests were conducted on lines of commercial quality PVC tubing of length 1 ft to 50 ft, inside diameter 1/8 to 3/8 in., and over a frequency range from 2Hz to 1000Hz. Air at approximately 60 deg F and a mean gauge pressure of 1.0 lb/in.2 was used as the working fluid, with input signal amplitudes of ±0.1 lb/in2. The resulting data have been used to calculate the propagation function and hence to determine best-fit values of the constants which appear in the approximate theoretical expression of F. T. Brown. While the performance of many lines of interest may be predicted accurately by using Brown’s theoretical constants, the tests have shown significant changes in the experimentally determined values of the constants as line length decreases. These changes may be due, at least in part, to the increasing significance of wall elasticity at higher frequencies, an effect which is not included in Brown’s analysis. The data are given in a form which is directly applicable to calculating transmission line response.

Laboratory Tests Study on the Power Dissipation Characteristics of Conductor Self-Damping and Aeolian Vibration Dampers

2010 ◽  
Vol 29-32 ◽  
pp. 2290-2295 ◽  
Author(s):  
Yuan Kun Chen ◽  
Li Li ◽  
Kun Ye ◽  
Peng Yin
Keyword(s):  
Transmission Line ◽  
Natural Frequency ◽  
Vibration Frequency ◽  
Power Dissipation ◽  
Laboratory Tests ◽  
Theoretical Method ◽  
Test Results ◽  
Vibration Effect ◽  
Aeolian Vibration ◽  
Line Engineering

In this paper, laboratory tests on conductor aeolian vibration were designed and carried out, through which the power dissipation characteristics of conductor self-damping and wire dampers(bretelles) were investigated. In addition, the theoretical method was established to estimate the power dissipated by wire damper. The results show that conductor tension and vibration frequency have great influences on its self-damping property; furthermore, the results present that the natural frequency of wire damper is related with its length and the length of wire damper has significant impact on its anti-vibration effect. The theoretical method for calculating the power dissipated by wire damper was verified to be reliable by the test results. These conclusions can provide references for the research and anti-vibration design of transmission line engineering.

Composite right/left-handed transmission line with array of thermocouples for generating terahertz radiation

2020 ◽  
Vol 92 (2) ◽  
pp. 20502
Author(s):  
Behrokh Beiranvand ◽  
Alexander S. Sobolev ◽  
Anton V. Kudryashov
Keyword(s):  
Transmission Line ◽  
Terahertz Radiation ◽  
Transmission Lines ◽  
Software Package ◽  
Optical Pulses ◽  
Capacitively Coupled ◽  
Voltage Difference ◽  
Left Handed ◽  
Microwave Transmission ◽  
Commercial Software Package

We present a new concept of the thermoelectric structure that generates microwave and terahertz signals when illuminated by femtosecond optical pulses. The structure consists of a series array of capacitively coupled thermocouples. The array acts as a hybrid type microwave transmission line with anomalous dispersion and phase velocity higher than the velocity of light. This allows for adding up the responces from all the thermocouples in phase. The array is easily integrable with microstrip transmission lines. Dispersion curves obtained from both the lumped network scheme and numerical simulations are presented. The connection of the thermocouples is a composite right/left-handed transmission line, which can receive terahertz radiation from the transmission line ports. The radiation of the photon to the surface of the thermocouple structure causes a voltage difference with the bandwidth of terahertz. We examined a lossy composite right/left-handed transmission line to extract the circuit elements. The calculated properties of the design are extracted by employing commercial software package CST STUDIO SUITE.

scholarly journals Time-Multiplexed Self-Powered Wireless Current Sensor for Power Transmission Lines

Energies ◽  
2021 ◽  
Vol 14 (6) ◽  
pp. 1561
Author(s):  
Hao Chen ◽  
Zhongnan Qian ◽  
Chengyin Liu ◽  
Jiande Wu ◽  
Wuhua Li ◽  
...  
Keyword(s):  
Energy Harvesting ◽  
Transmission Line ◽  
Transmission Lines ◽  
Power Transmission ◽  
Current Measurement ◽  
Current Sensor ◽  
Power Transmission Line ◽  
Power Transmission Lines ◽  
Current Sensing ◽  
Self Powered

Current measurement is a key part of the monitoring system for power transmission lines. Compared with the conventional current sensor, the distributed, self-powered and contactless current sensor has great advantages of safety and reliability. By integrating the current sensing function and the energy harvesting function of current transformer (CT), a time-multiplexed self-powered wireless sensor that can measure the power transmission line current is presented in this paper. Two operating modes of CT, including current sensing mode and energy harvesting mode, are analyzed in detail. Through the design of mode-switching circuit, harvesting circuit and measurement circuit are isolated using only one CT secondary coil, which eliminates the interference between energy harvesting and current measurement. Thus, the accurate measurement in the current sensing mode and the maximum energy collection in the energy harvesting mode are both realized, all of which simplify the online power transmission line monitoring. The designed time-multiplexed working mode allows the sensor to work at a lower transmission line current, at the expense of a lower working frequency. Finally, the proposed sensor is verified by experiments.

Study on the characteristics of secondary arc current of UHV high compensation degree TCSC line under the fine-tuning mode

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Baina He ◽  
Yadi Xie ◽  
Jingru Zhang ◽  
Nirmal-Kumar C. Nair ◽  
Xingmin He ◽  
...  
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Stability Margin ◽  
Transmission Capacity ◽  
Fine Tuning ◽  
Series Compensation ◽  
Arc Current ◽  
Compensation Device ◽  
The Stability ◽  
Recovery Voltage

Abstract In the transmission line, the series compensation device is often used to improve the transmission capacity. However, when the fixed series capacitor (FSC) is used in high compensation series compensation device, the stability margin cannot meet the requirements. Therefore, thyristor controlled series compensator (TCSC) is often installed in transmission lines to improve the transmission capacity of the line and the stability of the system. For cost considerations, the hybrid compensation mode of FSC and TCSC is often adopted. However, when a single-phase grounding fault occurs in a transmission line with increased series compensation degree, the unreasonable distribution of FSC and TCSC will lead to the excessive amplitude of secondary arc current, which is not conducive to rapid arc extinguishing. To solve this problem, this paper is based on 1000 kV Changzhi-Nanyang-Jingmen UHV series compensation transmission system, using PSCAD simulation program to established UHV series compensation simulation model, The variation law of secondary arc current and recovery voltage during operation in fine tuning mode after adding TCSC to UHV transmission line is analyzed, and the effect of increasing series compensation degree on secondary arc current and recovery voltage characteristics is studied. And analyze the secondary arc current and recovery voltage when using different FSC and TCSC series compensation degree schemes, and get the most reasonable series compensation configuration scheme. The results show that TCSC compensation is more beneficial to arc extinguishing under the same series compensation. Compared with several series compensation schemes, it is found that with the increase of the proportion of TCSC, the amplitude of secondary arc current and recovery voltage vary greatly. Considering various factors, the scheme that is more conducive to accelerating arc extinguishing is chosen.

scholarly journals A Vibration-Based Structural Health Monitoring System for Transmission Line Towers

Electronics ◽  
2019 ◽  
Vol 8 (5) ◽  
pp. 515 ◽  
Author(s):  
Long Zhao ◽  
Xinbo Huang ◽  
Ye Zhang ◽  
Yi Tian ◽  
Yu Zhao
Keyword(s):  
Structural Health Monitoring ◽  
Transmission Line ◽  
Natural Frequency ◽  
Health Monitoring ◽  
Structural Changes ◽  
Natural Frequencies ◽  
Transmission Tower ◽  
Health Monitoring System ◽  
Wind Speeds ◽  
Before And After

In this paper, we present a vibration-based transmission tower structural health monitoring system consisting of two parts that identifies structural changes in towers. An accelerometer group realizes vibration response acquisition at different positions and reduces the risk of data loss by data compression technology. A solar cell provides the power supply. An analyser receives the data from the acceleration sensor group and calculates the transmission tower natural frequencies, and the change in the structure is determined based on natural frequencies. Then, the data are sent to the monitoring center. Furthermore, analysis of the vibration signal and the calculation method of natural frequencies are proposed. The response and natural frequencies of vibration at different wind speeds are analysed by time-domain signal, power spectral density (PSD), root mean square (RMS) and short-time Fouier transform (STFT). The natural frequency identification of the overall structure by the stochastic subspace identification (SSI) method reveals that the number of natural frequencies that can be calculated at different wind speeds is different, but the 2nd, 3rd and 4th natural frequencies can be excited. Finally, the system was tested on a 110 kV experimental transmission line. After 18 h of experimentation, the natural frequency of the overall structure of the transmission tower was determined before and after the tower leg was lifted. The results show that before and after the tower leg is lifted, the natural frequencies of each order exhibit obvious changes, and the differences in the average values can be used as the basis for judging the structural changes of the tower.

Development on Environmental Geotechnology for Overhead Transmission Line Foundation Engineering in China

2012 ◽  
Vol 610-613 ◽  
pp. 2813-2818
Author(s):  
Xian Long Lu ◽  
Zeng Zhen Qian
Keyword(s):  
Transmission Line ◽  
Environmental Protection ◽  
Transmission Lines ◽  
Water Conservation ◽  
Design Method ◽  
Foundation Engineering ◽  
Foundation Construction ◽  
Overhead Transmission Line ◽  
Tower Foundation ◽  
Soil And Water

This paper presents the concept and the fundamental issues and the development on the environmental geotechnology in transmission lines foundation engineering. Namely, environmental geotechnology and theory is to study the restriction effects of environment on the transmission line routes, foundation selection and reliability, to predict the results of transmission line foundation construction on the environment, and to study on countermeasures of environmental protection in transmission foundation engineering. And then, from the above three aspects, the design method combined strength and displacement for tower foundation, the selection on foundation types and technical scheme for transmission line tower, and the countermeasures for soil and water conservation, the author introduces the development and practice of environmental geotechnology for transmission lines foundation engineering in China.

Study the Effect of Radio Interference of the EHV Transmission Line on GNSS Signals

2013 ◽  
Vol 805-806 ◽  
pp. 851-854
Author(s):  
Zhi Ge Jia ◽  
Zhao Sheng Nie ◽  
Wei Wang ◽  
Xiao Guan ◽  
Di Jin Wang
Keyword(s):  
Transmission Line ◽  
Transmission Lines ◽  
Internal Noise ◽  
Field Testing ◽  
Satellite System ◽  
Field Analysis ◽  
Radio Interference ◽  
Gnss Receiver ◽  
Global Navigation Satellite ◽  
Gnss Data

This work describes the field testing process of Global Navigation Satellite System (GNSS) receiver under 220KV, 500KV UHV transmission line and standard calibration field. Analysis for GNSS data results shows that the radio interference generated by EHV transmission lines have no effect on GNSS receiver internal noise levels and valid GNSS observation rate. Within 50 meters of the EHV transmission lines, the multi-path effects (mp1 and mp2 value) significantly exceeded the normal range and becomes larger with the increase of the voltage .outside 50 meters of the EHV transmission line, the multi-path effects have almost no effect on the high-precision GNSS observations.

Free vibration analysis and post-critical free vibrations of nanocomposite rotating beams reinforced with graphene platelet

2021 ◽  
pp. 107754632110511
Author(s):  
Arameh Eyvazian ◽  
Chunwei Zhang ◽  
Farayi Musharavati ◽  
Afrasyab Khan ◽  
Mohammad Alkhedher
Keyword(s):  
Natural Frequency ◽  
Thermal Environment ◽  
Rotational Velocity ◽  
Equations Of Motion ◽  
Free Vibration Analysis ◽  
Beam Theory ◽  
Weight Fraction ◽  
Free Vibrations ◽  
Graphene Platelet ◽  
The Impact

Treatment of the first natural frequency of a rotating nanocomposite beam reinforced with graphene platelet is discussed here. In regard of the Timoshenko beam theory hypothesis, the motion equations are acquired. The effective elasticity modulus of the rotating nanocomposite beam is specified resorting to the Halpin–Tsai micro mechanical model. The Ritz technique is utilized for the sake of discretization of the nonlinear equations of motion. The first natural frequency of the rotating nanocomposite beam prior to the buckling instability and the associated post-critical natural frequency is computed by means of a powerful iteration scheme in reliance on the Newton–Raphson method alongside the iteration strategy. The impact of adding the graphene platelet to a rotating isotropic beam in thermal ambient is discussed in detail. The impression of support conditions, and the weight fraction and the dispersion type of the graphene platelet on the acquired outcomes are studied. It is elucidated that when a beam has not undergone a temperature increment, by reinforcing the beam with graphene platelet, the natural frequency is enhanced. However, when the beam is in a thermal environment, at low-to-medium range of rotational velocity, adding the graphene platelet diminishes the first natural frequency of a rotating O-GPL nanocomposite beam. Depending on the temperature, the post-critical natural frequency of a rotating X-GPL nanocomposite beam may be enhanced or reduced by the growth of the graphene platelet weight fraction.

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