Aeolian Vibration Research Articles

A probabilistic approach to the Poffenberger-Swart bending stress of conductors subject to aeolian vibrations

A probabilistic approach to the Poffenberger-Swart bending stress of conductors subject to aeolian vibrations

Predicting distribution of aeolian vibration amplitude of undamped overhead transmission lines

The most widely accepted estimation procedure of the severity of aeolian vibration is by calculating the maximum oscillation amplitudes of the conductor using Energy Balance Principle (EBP). However, the EBP is based on wind tunnel results where only one frequency is excited, while observations and experimental results show that multiple resonant modes are excited simultaneously. Furthermore, the required number of cycles of each amplitude level is not provided by current EBP-based methods. In this paper, vibration data from an experimental undamped ACSR Bersfort test line in Quebec, Canada, is recorded and analyzed. For each record of aeolian vibrations, amplitudes are fitted to a Rayleigh distribution based on the narrow-band assumption. The number of cycles and Rayleigh parameter are then related to wind conditions through a modified Strouhal frequency and EBP methodology. A statistical model is proposed to relate vibration profiles and wind input while considering wind turbulence intensity. The proposed method performs well and gives accurate estimates of both vibration amplitudes and number of cycles for ACSR Bersfort conductor. Physical and statistical theory is provided for each step of the method in order to extend the application of the method to other types of conductors or different line configurations.

Aeolian Liquid Vibrations in Conical Tanks with Baffles under Wind Loading with Fuzzy Parameters

The Aeolian liquid vibrations in conical reservoirs caused by low-velocity, steady winds have been under consideration. Both amplitudes and dominant frequencies of wind loadings have been constantly changed, so to adequately describe the vibration process, fuzzy logic methods have been applied. At the first stage, the crisp initial value problem for conical shells with and without baffles has been considered. The liquid inside the reservoirs has been supposed to be an incompressible and ideal one, and its flow induced by the forced harmonic excitation, has been considered as potential. So, there exists a potential to satisfy the Laplace equation. The impermeable condition has been used at wetted surface boundaries of the shell, whereas the dynamic and kinematic boundary conditions have been set on the free liquid surface. A system of singular integral equations has been obtained for values of the velocity potential and the function describing the free surface rise. Its solution has been gained by boundary element methods. The crisp boundary value problem has been reduced to the second-order system of differential equations. After receiving the crisp solution of this system, the initial data have been fuzzified, involving triangular fuzzy numbers, and the fuzzy initial value problem has been formulated. The numerical solution to this problem with uncertain intervals involved has been obtained and analyzed.

Aeolian Vibration Dynamic Analysis of Large-Span, Relaxed Antenna Cable Net Based on Finite Particle Method

The large-span, relaxed antenna network is a large deformation flexible structure due to its low pre-tension level of the wires. Its dynamic analysis under a wind load belongs to dynamic and geometric nonlinear problems, which is very complex to accurately calculate and solve. This paper explores the possibility of the finite particle method (FPM) to the aeolian vibration analysis of a large-span, low stress-tensioned antenna cable net. In the FPM, the antenna network structure is discretized into a group of finite particles, where the motions of all particles follow Newton’s second law and can be solved dynamically using a central difference scheme. The effectiveness and applicability of the FPM were verified by comparing the calculation results of the finite element method and FPM. The FPM was used to study the effects of wind speed and the distribution of vibration on the aeolian vibration of antenna cable nets. The results showed that this method is suitable for studying the aeolian vibration of a large-span, low stress-tensioned antenna network and has high computational efficiency and accuracy.

Self-powered system for environment and aeolian vibration monitoring in the high-voltage transmission system by multi-directional wind-driven triboelectric nanogenerator

The concentration of abundant wind energy on the high-voltage transmission tower with the feature of high height not only provides a promising solution for powering distributed sensors in smart grid, but also enables a potential feasibility for the real-time sensing of the multi-directional wind to evaluate the transmission line aeolian vibration induced by wind excitation. In this paper, the comprehensive strategy appropriately hybridizes the ingenious integration of a rotating-type TENG for efficient wind energy harvesting and a flapping-type TENG for multi-directional wind vector sensing to establish the self-powered multi-directional wind-driven triboelectric nanogenerator (SMW-TENG). The basic D-TENG and F-TENG in terms of structural parameters and response characteristics are systematically optimized to realize an efficient energy harvesting with the peak power of 3.9 mW, a smooth output in the wind speed of 3.7–16.3 m s−1 and sensitive response to eight-direction wind speed ranging from 2.6 to 13.5 m s−1. Hybrid power supply strategy based on collaborative working of UD-TENG as a standby power and LD-TENG as a main power is innovatively proposed to prolong the continues power supply of a Bluetooth temperature and humidity sensor by 70% and 126.7% compared to the single module, respectively. Importantly, the F-TENG equipped with an eight-channel signal acquisition and processing is developed to achieve the multi-directional wind vector information in response to the aeolian vibration. Furthermore, a self-powered ambient weather and multichannel wind vector sensing system based on the SMW-TENG, a hybrid power supply circuit, an eight-channel signal acquisition circuit and a Bluetooth module is developed to comprehensively realize the real-time monitoring of temperature, humidity, wind speed and direction. The abnormal wire vibration alarm can be realized through monitoring the wind direction angle on the transmission line cross-section, thereby exhibiting a great potential for developing self-powered sensing in the field of smart grids.

Anti‐Self‐Excited Oscillation Triboelectric Nanogenerators for Energy Harvesting of Aeolian Vibration in Transmission Line

Ensuring the reliability and stability of long‐distance power transmission requires monitoring the transmission lines' and grid environment's health. For this purpose, this study proposes a triboelectric nanogenerator (TENG) with anti‐self‐excited vibration. In case of aeolian vibration in the transmission line, the anti‐self‐excited oscillation triboelectric nanogenerator (AO‐TENG) generates electricity via cohesive work between the spring and the additional weight block that drives the TENG. As a result, this prevents excessive surge voltage from damaging the back‐end circuit, and the capacitor contributes significantly to voltage drop. This solution solves the issue that arises due to the TENG's high output voltage, making it difficult to power commercial sensors. This study presents a new design solution to facilitate smart grids that guarantee stable operation of distributed sensor nodes in the grids.

Hybridized Triboelectric-Electromagnetic Aeolian Vibration Generator as a Self-Powered System for Efficient Vibration Energy Harvesting and Vibration Online Monitoring of Transmission Lines.

In this work, based on the triboelectric-electromagnetic working principle, a comprehensive strategy appropriately hybridizes a multilayered elastic structure TENG (ME-TENG) and a double-electromagnetic generator (EMG) for efficient aeolian vibration energy harvesting and vibration state monitoring. The ME-TENG with the feature of elasticity is integrated with a movable plate embedded with a magnet as the counterweight, which acts as a spring-like mass system in response to external vibration excitation, making the inseparable integrity of the TENG and EMG. The basic hybridized triboelectric-electromagnetic aeolian vibration generator (HAVG) consisting of ME-TENG and double-EMGs in terms of structural parameters and response characteristics is first optimized and discussed, thereby the efficient vibration energy harvesting and effective vibration state response can be further improved through the mutual complementarity of TENG and EMG. Furthermore, the self-powered capacity of the HAVG in terms of LED arrays and a wireless ambient temperature and humidity monitoring system is verified through the hybrid charging strategy of TENG and EMG modules and the combination of HVAG and energy management circuits, benefiting from the sophisticated-designed structure and excellent output performance of the HAVG. Importantly, a self-powered aeolian vibration monitoring system is established and demonstrated for vibration-state sensing and abnormal vibration alarm. This work demonstrates a novel strategy for energy harvesting and state sensing of overhead transmission line aeolian vibration, which not only reveals TENG-EMG promising potential for energy harvesting for aeolian vibration, but also provides valuable guidance for the construction of a self-powered online-monitoring system for transmission lines.

Fatigue life prediction of aluminum-graphene nanocomposites: Application to high-capacity conductors

Fatigue fracture of aluminum wires due to Aeolian vibrations (high-cycle fatigue) is one of the severe problems in the high-capacity conductors of the power transmission lines. On the other hand, previous studies have shown that graphene can significantly increase aliminum’s mechanical and electrical properties. In this regard, this research has studied the high-cycle fatigue (HCF) of Al-0.5 wt% GNPs composite using experimental methods. Quasi static and high-cycle fatigue tests were performed at room and elevated temperatures and material parameters of the Basquin's equation were derived. Afractographicanalysis of the fracturedsamples was carried out using field emission scanning electron microscopy (FE-SEM). The results showed that composite has better hardness and tensile strength than pure aluminum, while its elongation was decreased. At room temperatures, the fatigue life of the composite was increased by 234 % and 44 % at low and high stress levels, respectively. While at elevated temperatures, 146 % and 130 % increase in fatigue life were obtained at low and high stress levels, respectively.

Study on anti-vibration optimization design of transmission line section with large span in Inner Mongolia

Affected by the cold wave process, eastern Inner Mongolia is easy to suffer from both of persistent low temperature and strong wind weather, which causes the dynamic bending strain of overhead conductors’ aeolian vibration to approach or even exceed the safety threshold frequently. The end position of the existing conductor and the conventional vibration damper are in high-intensity working state for a long time, which seriously threatens the operation safety of Inner Mongolia East power grid. In this paper, aiming at the optimization design of anti vibration scheme of large span line section in eastern Mongolia, taking the 500kV Kesha #1 and #2 line #119 ~ 120 line section with a span of 1043m as an example, according to the existing anti vibration design standards of large span line section, the effect evaluation test optimization research of anti vibration scheme is carried out, and the anti vibration scheme more suitable for large span line section in low temperature and strong wind area in eastern Mongolia is given. The recommended anti vibration scheme is obtained through simulation test, analysis and Optimization on the indoor test file, which meets the relevant technical requirements of anti vibration. It is of great significance to avoid fatal defects in large span line sections of transmission lines and ensure the long-term safe and stable operation of regional power grid.

Fatigue Behavior Analysis and Life Prediction of Overhead Conductors Subject to Narrowband Vibration

This paper aims to present a contribution to the study of the effect of random vibration on the useful life of overhead conductors. This study compares two approaches based on an acquired vibration signal. The first one is the time-domain approach (based on rainflow cycle counting), while the second one is the frequency-domain approach (based on power spectral density moments). Laboratory simulation of aeolian vibration was used in finding the fatigue characteristics of a ACSR 397,5MCM – IBIS conductor. The S-N diagram was generated by performing 9 fatigue tests under constant amplitude conditions and 13 fatigue tests in narrowband excitation conditions. The reported tests were performed to assess the effect of random loading on fatigue life considering the two approaches for estimating fatigue life. A good correlation was found between the estimated fatigue lives using the time-domain and frequency-domain approaches and the experimental data.

Uncertainties Propagation and Global Sensitivity Analysis of the Aeolian Vibration of OPGW Cables

AbstractThis paper is devoted to evaluating the quantification of uncertainty involved in the study of Aeolian vibrations of optical ground wire (OPGW) cable systems installed on overhead power transmission lines. The energy balance method (EBM) is widely used to estimate the severity of steady-state Aeolian vibrations. Although the EBM requires some experimental characterization of system parameters (as indicated by international standards), it is necessary to mention that such a procedure is connected with uncertainties which makes it difficult for the proper homologation of the cable systems. In this article, the parametric probabilistic approach is employed to quantify the level of uncertainty associated with the EBM in the study of Aeolian vibrations of OPGW. The relevant parameters of the EBM (damper properties, cable self-damping, and the power imparted by the wind) are assumed as random variables whose distribution is deduced by means of the maximum entropy principle. Then a Monte Carlo simulation is performed, and the input and output uncertainties are contrasted. Finally, a global sensitivity analysis is conducted to identify the Sobol' indices. Results indicate that parameters related to self-damping and damper are the most influential on uncertainty and output variability. In this sense, the present framework constitutes a powerful tool in the robust design of damper systems for OPGW cables.

Tensegrity-inspired triboelectric nanogenerator for broadband and impact-resistive vibration sensing

Vibration in the environment usually shows uncertainty with random changes in frequency and sudden acceleration impact. However, it is a huge challenge for existing vibration energy harvesters and sensors to work in random and even extreme vibration environments due to their rigid multi-component architecture with mechanical mismatches. Here, we propose a general design of vibration transduction with broadband response and high mechanical robustness that mimics the biological musculoskeletal system. Such design is based on a tensegrity structure, consisting of a rigid frame and soft strings, combined with triboelectric nanogenerator (TENG). The Tensegrity-inspired triboelectric nanogenerator is of broadband (0–200 Hz) frequency response and exhibits excellent impact resistance under high g acceleration impacts (105 g level). The device can still work normally after undergoing some structural damage. It has been successfully applied to the aeolian vibration monitoring of transmission lines and shows more reliable performance than commercial sensors when suffering the hail impact. Such tensegrity structure design has great potential in high-performance vibration monitoring in the industrial environment.

Structural Defect Detection Technology of Transmission Line Damper Based on UAV Image

Overhead transmission lines suffer from extended exposure to harsh weather conditions. Metal dampers, a crucial protective fitting in the line, can effectively suppress the conductor’s vibration energy and prevent Aeolian vibration and ice shedding. To ensure the safety of operation of the damper, we are proposing a detection method for structural defect damper based on spatial relationship. First, the unmanned aerial vehicle (UAV) aerial damper images are processed with relative total variation (RTV) transform to obtain an enhanced image with a smooth texture and prominent foreground main structure. Second, the enhanced image is corrected by rotation so that the conductor remains horizontal. Next, based on the endpoint coordinates of the conductor, a foreground preselection box for improved GrabCut segmentation is automatically generated to extract the object dampers. Finally, the spatial relationship between the damper components in the segmentation results is regarded as the motive force of the damper structural defect diagnosis model to detect damage, inversion, slight, and serious deformation defects in sequence. We analyzed the performance of the proposed method through actual field tests, and the results demonstrated that the identification accuracy of the method is 95.76% when applied to a small sample set, which is higher than other existing methods based on traditional image techniques and deep learning defect detection, and can effectively identify different structural defects of dampers and provide reliable data for transmission line condition monitoring.

Hourly wind data for aeolian vibration analysis of overhead transmission line conductors

Fretting fatigue of conductors due to aeolian vibrations is an important phenomenon for the design and maintenance of electric transmission networks. The evaluation of exposure and susceptibility of a given span to aeolian vibrations requires information on the distribution of hourly wind speed and direction. Interpolation has been used to obtain wind data at non-instrumented locations; however, their accuracy is not adequate at locations far from stations and at locations in mountainous regions. Numerical Weather Prediction data sets provide wind information on a regular grid covering equally all regions; however, the spatial resolution is not adequate. A procedure is proposed using a mass-conserving diagnostic model (WindNinja) that incorporates a detailed map of local topography to improve predictions of wind direction. A second correction is proposed to account for local surface roughness as a function of wind direction and average canopy height from high-resolution LiDAR data. The proposed procedure is applied to nine meteorological stations and two experiment sites over southern Quebec, Canada. WindNinja was found to provide good estimates for the effects of local topography in mountainous regions. Wind speed after correction provides good agreement with hourly observations as well as with Weibull distributions fitted to the actual observations.

NORMAL VIBRATIONS OF SAGGING CONDUCTORS OF OVERHEAD POWER LINES

The phenomenon of self-excitation of thermomechanical vibrations of current-carrying conductors, experimentally discovered by academician A.F. Ioffe, is of practical interest as a possible explanation of the phenomenon of galloping conductors of overhead power transmission lines (OHL) – low-frequency vibrations with frequencies of ~ 1 Hz and with amplitudes of the order of the static conductor sagging. To build the theoretical foundations of this phenomenon, as a special class of self-oscillating systems, it is necessary, first of all, a model of conductor vibrations in the OHL span. With regard to the most studied type of conductor vibrations, high-frequency aeolian vibration, excited by sign-alternating aerodynamic forces from the Karman vortex street, the classical model of a straight string is reasonably applied. However, to study low-frequency vibrations of the galloping type, it is necessary to take into account the effect of sagging of the conductor, the associated elastic tension and, in some cases, the nonlinear nature of the vibrations. The article presents two models for calculating the natural vibrations of sagging conductors (cables) within the framework of the technical theory of flexible threads, assuming the constancy of the tension force along the length. The first model describes linear oscillations of an elastic conductor in the sagging plane. For a system of equations with respect to the displacement components given in natural coordinates, an exact solution of the Sturm-Liouville problem with estimates of the frequency ranges arising is obtained. The second model describes nonlinear vibrations of an elastic conductor in the sagging plane and pendulum vibrations accompanied by an exit from it. The solution of the problem is based on the principle of possible displacements using the Ritz method. The structure of the frequency spectrum and the natural forms of transverse vibrations are studied. The developed models are intended for further investigation of thermomechanical vibrations of conductor and flexible cable systems.

Evaluating Aeolian Vibration Performance of High-Temperature Low-Sag OHL Conductors

High-Temperature Low-Sag (HTLS) conductor technologies are often implemented, among many approaches, for optimizing the overhead lines utilization. The advancements of HTLS conductors are based on the differences in core and aluminum properties and installation procedures. This non-linear conductor behavior, although considered in the sag-tension calculations, by implementing the knee-point temperature, is often omitted from the aeolian vibration calculations. To understand the implications of the complex HTLS conductor structure on vibrations, a new calculation approach is proposed in this paper to quantify the effect of installation and operating conditions on the performance of any HTLS conductor. The proposed method conceives a prediction lay area that estimates where the actual field data are expected to lay, and is validated with good accuracy against the field data from ACSR, ACCC, and GZTACSR. The developed model enables the prediction of non-homogeneous (composite) conductors and should be implemented at above knee-point operating temperatures with zero aluminum tensions

Multi‐Parameter Optimized Triboelectric Nanogenerator Based Self‐Powered Sensor Network for Broadband Aeolian Vibration Online‐Monitoring of Transmission Lines

AbstractOverhead transmission lines are vulnerable to aeolian vibrations that threaten the operation of the power grid. A triboelectric nanogenerator (TENG) based self‐powered system offers a desirable way for vibration online‐monitoring with potential for large‐scale deployment. In this work, a self‐powered sensor network constructed by active vibration sensor (AVS) units with a spring‐mass based TENG (S‐TENG) is reported for effective energy harvesting and broadband vibration sensing. The basic TENG with structural parameters is first discussed from the aspects of efficiency and response characteristics, then the spring constant and mass weight are also adjusted for S‐TENGs with different optimal operation regions, thus the overall vibration amplitude and frequency response are further enhanced by the mutual compensation of S‐TENGs with a weight allocation strategy. Furthermore, the S‐TENGs are combined with external circuits to compose the AVS units, which are deployed in a distributed manner on a simulated transmission line to demonstrate a self‐powered wireless warning system and an aeolian vibration mapping system, enabling abnormal vibration warnings and vibration distribution monitoring over the whole line. This work represents a novel strategy for utilizing TENG technology for transmission line aeolian vibration monitoring and provides valuable guidance for further sensor network construction and power grid visualization.

Numerical study of aeolian vibration characteristics and fatigue life estimation of transmission conductors.

The 2D computational fluid dynamics (CFD) model of transmission conductor is set up to simulate the aerodynamic forces varying with time on the conductor. Taking into account the geometrical nonlinearity of conductor lines, the finite element (FE) models of single span and two-span transmission lines discretized with beam elements are established. By means of the FE models, the aeolian vibrations of the conductor lines excited by the aerodynamic forces under different wind velocities are numerically simulated. The nonlinear resonant characteristics, the amplitude-frequency relations of the conductor lines during aeolian vibration are investigated, and the influences of the span length as well as the initial tension in conductors on the aeolian vibration characteristics are analyzed. Furthermore, a 3D FE model of a conductor segment and the suspension clamp is created to study the stress distributions of the 3D model corresponding to different lines during aeolian vibrations. Finally, based on the stress analysis of the 3D model, the fatigue lives of the transmission conductors during aeolian vibration under different wind velocities are estimated. The jump phenomenon induced by the nonlinear vibration is reflected by the numerical simulation considering the geometric nonlinearity, and it is found that the energy balance principle (EBP) overestimates the vibration amplitudes because it cannot take the influences of the geometrical nonlinearity and span length into account. The obtained results may provide some instructions for the prevention design of aeolian vibration.

Anti-vibration Measures of Ultrahigh Strength Steel Cored Aluminum Strand for Long-Span Overhead Line

It is the key issue for long-span overhead line to take anti-vibration measures for the ultrahigh strength steel cored aluminum strand. Taking the ultrahigh strength steel cored aluminum strand JLHA1/G6A-500/230 as the example, the aeolian vibration control measure for ultrahigh strength steel cored aluminum strand is tested based on the balance principle of conductor aeolian vibration. The result shows that the dynamic bending strain of the conductors exceeds120×l0-6 when the test frequencies are in the range of 14Hz~70 Hz. In order to reduce the dynamic bending strain of the conductors, the anti-vibration measure of the β damping wires combined with vibration dampers is used. The β damping wires have very good energy dissipation capacity within wide frequencies. The layout of the damping wires is designed as combinations of 3.8 m , 3.2 m, 2.7 m...0.9msingle lace damping lines respectively, two vibration dampers are arranged in the mid span of the first and second damping wires. After taking the anti-vibration measure, the maximum dynamic bending strains of the conductors is controlled below 120×l0-6, which meet the standard requirements. This study provides useful reference for long-span overhead line.

Harvesting the aeolian vibration energy of transmission lines using an omnidirectional broadband triboelectric nanogenerator in smart grids

An omnidirectional broadband triboelectric nanogenerator is proposed for harvesting the aeolian vibration energy of transmission lines. The harvester supplied 109.8 V RMS voltage and 4.02 mW RMS power.