Spacer Dampers Research Articles

Design and Test of Quad-Bundle Spacer Damper Based on a New Rubber Structure

Aiming at improving the handling efficiency and acquiring the satisfactory antivibration effect and damping performance, a quad-bundle spacer damper of 500 kV extra high voltage transmission lines was designed and developed based on a new rubber structure. Firstly, a mathematical vibration model of the spacer damper was constructed, and the structures of the defect-prone parts of the spacer damper were analyzed. Then, the structure was optimized based on the defect analysis, the clamp with fast installation as well as removal and the damper joint with superior performance were designed. On this basis, a new quad-bundle spacer damper was developed. Last but not least, the handling efficiency of the new quad-bundle spacer damper was evaluated, and performance tests were conducted according to the IEC standards. The evaluation and test results show that the handling efficiency, antivibration effect, and damping performance of the new quad-bundle spacer damper are significantly improved compared with those of the regular quad-bundle spacer damper, which provides a guarantee for the safe operation of 500 kV extra high voltage transmission lines.

Study on a New Combined Anti-Galloping Device for UHV Overhead Transmission Lines

These years, galloping of bundle conductors has severely threatened the safety of overhead transmission lines and caused enormous losses of economy. So, it is noted that the studies on the development of effective anti-galloping devices, have a great significance for resisting the galloping disaster of a power system and for improving the safe and stable operation of the grids. In this paper, a new combined anti-galloping device, based on the principles of energy dissipation, restraining the torsion, and detuning, was developed for ultra-high voltage overhead transmission lines. To perform such analysis, the combined anti-galloping design method was presented and the new applicable device was developed on the rotation-free spacer damper. Then, the arrangement of this new anti-galloping device was detailed and the efficiency assessment was carried out for verifying its galloping deterrence effect. Finally, the elastic and damping tests, the high voltage tests as well as the fatigue tests were realized to prove that the device designed satisfies the necessary requirements of overhead transmission lines.

송전선 4도체용 Spacer 진동특성 분석

In General, transmission line occur various vibration due to wind speed, terrain and climate. Such vibration is that lead to electrical accident of wire wear or disconnection. Therefore we install spacer damper to protect transmission line. The spacer damper is an anti-vibration device installed by multi-conductor transmission line, which maintains the distance between conducts and reduces vibration. It is necessary to secure the vibration performance of the spacer damper and increase efficiency which absorb and reduce energy generated by the vibration. This paper, in order to determine the degree of conservation of the rubber damper attached to the clamp of the 4-conductor spacer damper, we investigate harmonic response analysis.

A pounding spacer damper and its application on transmission line subjected to fluctuating wind load

In this paper, a new pounding spacer damper (PSD) is proposed, and the control effect on the transmission line under the fluctuating wind load is validated. At first, the schematic of the proposed PSD is provided, and the mechanical models of elastic, damping, and pounding forces are then obtained. After that, the dynamic equations of transmission line equipped with the PSD are derived. On the basis, the finite element model of transmission line–PSD system with the ANSYS software is established, and the pounding force of the PSD is calculated and applied through the ANSYS Parametric Design Language. Then the response induced by the fluctuating wind load is simulated, and meanwhile, the control effects of the PSD and spacer damper without pounding force are compared, of which the results illustrate that the minimal reduction ratio for the conductor span can reach to 11.10%, indicating that the proposed PSD can effectively control the vibration of the conductor span under the fluctuating wind load. In addition, the parametric analysis of gap, frequency, and damping ratios is conducted and demonstrates that the gap and frequency ratio have great impact on the control effect while the influence of damping ratio is not very significant.

동역학 해석을 통한 송전선로 검사로봇 프레임 설계에 관한 연구

This study aims to improve the dynamic stiffness of an inspection robot frame to prevent derailment from transmission lines. Finite element models for the transmission lines and robot frame are developed for the multi-body dynamic simulation. Natural frequency analysis was conducted using the FE models. Three types of spacer damper clamps installed on 4-conductor transmission lines are used to evaluate the derailment of the robot. Multi-body dynamic simulations with FE models are demonstrated for sub-span oscillation. When the robot operates, derailment of inspection robot from the transmission lines is determined because of resonance. To prevent the resonance, body position was changed and thickness optimization was conducted. The results show that derailment was not occurred because of the natural frequency improvement.

Optimization Design on Subspan Oscillation of Multi-Conductor

This paper is mainly focused on the analysis of the subspan oscillation to bundled conductors.The mechanics of subspan oscillation were analyzed. Considering anti-adsorption conditions and the amplitude 1imitations of sub-conductors, the calculating methods of largest subspan distance of bundle conductors were given. The mechanics of anti-subspan oscillation of spacer dampers was analyzed and a mechanical model of damping spacer damper was established. By calculating an engineering example, a real problem was calculated and evaluated, which was validated to be reasonable. Finally, a suit of calculation and simulation software was developed to facilitate the designers.

Experimental Study on Mitigation Devices of Aeolian Vibration of Bundled Conductors

Aeolian vibration of transmission conductors could cause triggering off shares and broken due to fatigue damage and thus of concern. To ensure the safety of electrical transmission systems, mitigation devices are usually installed on the conductors to suppress the aeolian vibration. This paper investigates effects of three types of such devices on bundled conductors experimentally, including spacer dampers, damping lines and stockbridge dampers. For this purpose, vibration tests of twin and four bundled conductors were designed and carried out according to IEEE standards. Firstly, the vibration characteristic of the twin bundled conductors equipped with the spacer damper and stockbridge damper were tested with different installation configuration of wire damper sets. The vibration tests of four bundled conductors were also carried out, and the energy dissipation power calculation of spacer damper has been given. The calculation method of energy dissipation power calculation of spacer damper can reflect the properties of the energy dissipation and the method is proven to be reasonable according to the test.

Design of a New Spacer Damper for Bundle Power Transmission Lines Dynamic Behavior Monitoring Based on Fiber Bragg Grating Sensor

Galloping and ice shedding, two of significant dynamic damages to bundle conductors, are both typical three-degree-of-freedom vibrations, while few technique is studied on monitoring the torsion oscillation of the whole bundles and the sub-conductors. For the monitoring of the vertical, horizontal, and especially torsional oscillations, a novel type of spacer damper is developed, which can also detect the torsion motion of each sub-conductor, with consideration of the special configurations of bundle cables and integrated with fiber bragg grating sensors. Then, a distributed FBG network is introduced.

Modeling the dynamic effects of ice shedding on spacer dampers

Effects of ice-shedding-induced cable vibration on spacer dampers are studied by applying a dynamic model. The model is based on the authors' recent development, which is improved here by applying spacer properties obtained experimentally. The model simulates cable vibration and bundle rotation at mid-span, where the spacer is attached to the cables, as well as the spacer deformation and forces acting on the spacer during the vibration of twin, triple and quad conductor bundles. Ice accumulation on a spacer may change the latter's elastic and damping properties, whose influence on the vibration is considered in the model together with the effect of varying cable properties. Simulation results show how the risk of bundle collapse and the load on the spacer is reduced when the number of subconductors in the bundle is increased. The model also predicts that the most important property which can reduce forces acting on the spacer during vibration is spacer damping, whereas the bundle rotation is affected to the greatest extent by cable damping.

Mechanical Implementation and Simulation of MoboLab, A Mobile Robot for Inspection of Power Transmission Lines

This paper describes the first phase in development of a mobile robot that can navigate aerial power transmission lines completely unattended by human operator. Its ultimate purpose is to automate inspection of power transmission lines and their equipments. The authors have developed a scaled functional model of such a mobile robot with a preliminary simple computer based on-off controller. MoboLab (Mobile Laboratory) navigates a power transmission line between two strain towers. It can maneuver over obstructions created by line equipments such as insulators, warning spheres, dampers, and spacer dampers. It can also easily negotiate the towers by its three flexible arms. MoboLab has an internal main screw which enables the robot to move itself or its two front and rear arms independently through changing gripped points. When the front arm gets close to an obstacle, the arm detaches from the line and goes down, the robot moves forward, the arm passes the obstacle and grippes the line again. In a same way another arms pass the obstacle.

Different numerical techniques for the solution of transcendental eigenvalue problem in transmission line bundles

The problem of a bundled transmission line attached with many spacer dampers is formulated by considering the conductor as a continuous system. The formulation results in a complex transcendental eigenvalue problem (TEVP), which presents several numerical difficulties. Some approaches towards solving the TEVP and their respective difficulties in getting the solutions are discussed in detail. The solution of the TEVP gives the necessary input data for applying the energy balance, which is used in order to obtain the actual vibration amplitudes of the transmission line conductors.

On the numerical simulation of vortex-induced vibrations of oscillating conductors

Aeolian vibrations for electrical overhead transmission line conductors have been investigated for many decades. Special dampers, e.g., Stockbridge dampers or spacer dampers, are mounted on the conductors to suppress these vibrations, which may otherwise lead to the fatigue failure at the points of high strain values. Simulations are routinely carried out in order to estimate the vibration levels, to determine the need of dampers, and to optimize their locations and the impedances. The energy balance principle (EBP) is well established for estimating the vibration amplitudes, and hence, the strain levels in the transmission line conductors. Besides the parameters of the conductor and of the dampers, the aerodynamic forces acting on the vibrating conductor are the main input data required for the energy balance. For the wind power input, researchers still depend on the experimental data of drag and lift forces of a vibrating cylinder obtained from wind tunnel testing. In case of the bundled conductors, many combinations regarding the number of conductors, spacing of the conductors as well as their orientations are possible, which make wind tunnel tests very expensive and formidable. It may be useful to replace the wind tunnel tests by numerical simulations, as far as possible. However, it is indispensable to validate the numerical results first, for at least some special cases, so that they can be used with confidence in the general case. The present paper is a first step towards obtaining the wind power inputs for different configurations of bundled conductors. In the current work, the flow around a vibrating conductor is simulated with the finite-volume method, by considering it as a circular cylinder. The two-dimensional Navier–Stokes equations are solved first. The drag and the lift forces are then calculated by integrating the pressure and the shear values on the boundary of the cylinder, which ultimately cause the impartation of wind power. The numerically obtained wind power input is then compared with that obtained by different researchers in wind tunnel tests. A very good match between the experimental and the numerical values of wind power input is found.

6도체 무볼트형 스페이서 댐퍼의 중량변화에 따른 진동현상

Spacer dampers maintain the constant gaps between each conductor in a bundle conductor-transmission line, and are installed at proper intervals to keep a line from all sorts of damages derived from the vibration energy caused by mechanical or electrical external factors. It is most important to embody a technology which considers difficulties of maintenance and repair, and has optimum elements in order to prevent accidents such as destruction by fire or the snapping of a wire by the effect of vibration phenomenon coming from transmission line. In the present thesis, therefore, the analysis of vibratory characteristics of spacer damper is set up by analytical methods such as the analysis of conductor motion's governing equation, the equation of spacer damper's motion, spacer damper-fastened wire's motion in a span, and the numerical analysis of finite difference method. Furthermore, the installation distance between spacer dampers was scrutinized by simulations of various vibration phenomena which change at any time as actual conditions do, and hereafter we will be able to analyze all kinds of vibration phenomena coming from a boltless spacer damper with 6 bundle conductor for 765 k V transmission line based on new analytical methods.

VORTEX-EXCITED VIBRATIONS IN BUNDLED CONDUCTORS: A MATHEMATICAL MODEL

Wind-excited vibrations generated by vortex shedding are very common in high-voltage overhead transmission lines. Although such vibrations are barely perceptible due to their low amplitudes (less than a conductor diameter), they are, however, extremely important since they may lead to conductor fatigue. Mathematical models are therefore necessary for the computation of these vibrations, in order to evaluate the risk of potential damage to the line as well as for studying the efficiency of damping measures. For single conductor lines, the so-called energy-balance method gives good results in estimating the vibration amplitudes. However, the problem becomes more involved for bundled conductors with spacer dampers, commonly used in high-power transmission in many countries, and a modified form of the energy-balance method is presented here. Singular perturbation methods are employed, along with the energetically equivalent standing wave amplitudes obtained from the modified energy-balance methods, to determine the bending strains at critical points. This gives an estimate for the maximum strain levels in a conductor, which can be very useful in the design of transmission lines and for the optimization of the corresponding damping devices.

On the energy dissipation in spacer dampers in bundled conductors of overhead transmission lines

In high voltage overhead transmission lines, bundles of conductors are used frequently for mechanical and electrical reasons. These bundled conductors are particularly susceptible to wind excited vibrations in the frequency range approximately from 10 to 60 Hz, due to vortex shedding. The usual dampers of the Stockbridge or of a similar type located near the suspension clamp do not lead to pervasive damping of the whole bundle. In recent years self-damping spacers have therefore been used to limit the danger of conductor fatigue due to aeolian vibrations. The numerical treatment of the boundary value problem for bundles equipped with self-damping spacers leads to complicated and poorly conditioned equations. In the present paper, a self-damping spacer is considered in a bundle of four conductors. The energy dissipation associated with the mathematical model for this spacer can be expressed in the form of a symmetric matrix of dimension 16 × 16. By solving the relatively small eigenvalue problem defined by the corresponding 16 × 16 matrix, the spacer damper can be optimized with respect to mechanical energy dissipation by maximizing the smallest real part of its eigenvalues.

On the performance of spacer dampers in bundled conductors

AbstractIn bundled conductors of overhead transmission lines spacers are used to maintain the distance between the individual conductor cables. These spacers are often provided with elastic and damping properties with the intent to damp out the mechanical vibrations due to vortex shedding in the frequency range between 10 Hz and 60 Hz. The present paper deals with a simple mechanical model of spacer dampers, which permits the study of the influence of different mechanical parameters on their damping performance. The dynamical characteristics of industrial spacer dampers determined in laboratory experiments can thus be compared to the values which are optimal from the vibrations damping point of view.

Computational comparison of efficacies of aeolian vibration damping devices for multiconductor overhead power lines

Aeolian vibration in multiconductor overhead power transmission lines is usually controlled by one of two techniques, namely by a combination of rigid spacing elements and end point Stockbridge dampers, or suitably positioned spacer dampers. In this paper, a comparison based on theory and computation is provided. It is concluded, consistent with observations over many years, that both philosophies suffice when the conductors are moderately tensioned ACSRs (aluminium conductor steel reinforced). When the conductors are moderately/highly tensioned AAACs (all aluminium alloy conductors), neither philosophy is totally adequate. If the two philosophies are combined, good vibration control will result in many circumstances.

Spacer Damper Performance - A Function of In-Span Positioning

Work on widely different quad and triple conductor bundles has established a non-dimensional characteristic relating ratios of adjacent subspans to nodal positions for a fundamental mode of subconductor oscillation. A good correlation has also been shown between nodal positions relative to spacer dampers and their damping performance as measured by logarithmic decrements. The performance of a given spacer damper in a given mode was improved by a factor of four to five times by correct choice of spacings. Consequently, a method of comparative field testing for spacer dampers is indicated. The experimental results have been satisfactorily predicted by a theoretical approach.

Bundle-Conductor-Spacer Design Requirements and Development of ``Spacer-Vibration Damper''

The various factors to be considered in the design of spacers for bundled conductors and the performance of a combination spacer damper designed to fulfill the mechanical and electrical requirements for spacers and the vibration damping requirements for the conductors are discussed.