Wear and life prediction of the U-shaped connecter of transmission line system under strong wind load
Introduction
Wind-induced vibration of transmission line is a common phenomenon, which is caused by the shedding of vortices on both sides of the line as the wind passes across the line. The wind-induced vibration of transmission line can lead to the wear of lines and fittings [1], [2], [3], [4]. U-shaped connecter is one kind of fittings in transmission line system, which is used to connect the transmission tower and line. In the process of maintenance and repair of transmission lines, it is often found that the U-shaped connecter is seriously worn. The Xinjiang region always suffers from strong winds above the level of 5th grade (average wind speed ranges from 8.0 to10.7 m/s). The U-shaped connecter in the 750 kV Urumqi-Turpan-Hami transmission line system was found to be severely worn after a year of operation, which has seriously threatened the safety of the transmission lines. Thus, the study on the wear behavior and life prediction of the U-shaped connecter in the strong wind environment is of great importance.
Wear of the U-shaped connecter is the result of the relative motion between the upper and lower U-shaped connecters. It causes the debris formation from the friction surface, resulting in the dimensional changes and weight loss on the contact surface. Kim et al.[5] investigated the effects of the material characteristics on the wear behavior of contact surfaces. Currently, the research on the wear of transmission line system was mainly limited to the wear of the conductor [6], [7], [8], [9], [10]. Azevedo et al.[11] focused on the failure of the conductor of the 460 kV overhead transmission line located along the crossing of the ParanáRiver. The typical static deformation and dynamic fretting wear tangential were observed on fracture cross-section. Cruzado et al.[12] explored the dynamic wear behavior and the developing process of the vibrating transmission line through the finite element method. It was found that the finite element method can well predict the wear life of line. Zhou et al.[13], [14] studied the fretting fatigue behaviors of the transmission lines. It showed that the fretting caused plastic deformation, wear and cracking, and then finally fatigue failure. Chen et al.[15] revealed that the abrasive fretting are the mechanism of fretting damage and the propagation of fatigue crack in the aluminum wire. FachriP et al.[16] carried out the experiment and finite element simulation research on the wear and fatigue of the conductor with a cross-section of 300 mm2. The finite element simulation results were in good agreement with that of the experiment. Marco et al.[17] investigated the failure characteristics of the aluminum alloy conductor under aeolian vibration. It revealed that the fractured wires shown typical static deformation marks and dynamic fretting wear tangential marks. Ma et al.[18] also studied the fretting wear behavior of aluminum cable steel reinforced conductors in different atmospheric conditions by experiment. It showed that the corrosive medium has a certain influence on the fretting transition phase.
There are some studies on the wear of the fittings of transmission line system. It is found that aeolian vibration, galloping, subspan vibration and ice jump of the line were the main causes of the wear of transmission line fittings [19], [20]. Refsnaes [21] carried out practical investigation and analysis on the operation of conductor support fittings on transmission lines in Norway in the past decades. It indicated that the prevailing wind direction affected the wear rates and the wear loss of the fittings was proportional to the insulator swing. You et al.[22] investigated the wear of the UB hanging plate of the ground line suspension string clamp under the continuous stable wind area. It revealed that the strong wind causes the side of hanging plate to contact with the bottom of the connecting angle steel, and the strong wind intensified the wear of fittings. In addition to the influence of wind-induced vibration on the wear of the fittings, the influence of wind-sand two-phase flow on the wear of the fittings has also been investigated [23]. It showed that the sandstorm can accelerate the wear of fittings.
A large number of wind-induced vibration experiments and analyses of transmission line system have been performed [24], [25], [26]. However, the influence of swing angle on the wear loss of U-shaped connecter is still lacking. The wind load acting on the lines makes the fittings move, and the relative motion of the fittings eventually leads to the wear of the fittings. The further study of the motion and wear law of U-shaped connecter is needed when the line is subjected to wind load. The current research and analysis of fittings wear did not consider the wind load environment. To investigate the wear behavior of fittings under strong winds, the wear experiment of the U-shaped connecter was carried out by the self-developed wear tester. The corresponding relationship among the swing cycles, experiment load, and residual strength was obtained. Based on the statistical data of the wind field in Xinjiang region, the finite element model of the transmission line-fittings system was established. The motion law of the fittings under various wind speed was explored, and the method for predicting the wear life of the fittings under the strong wind environment was proposed.
Section snippets
Experimental setup
The wear experiment of U-shaped connecter was carried out by the swing wear tester independently developed by the State Grid Xinjiang Electric Power Research Institute of China. The machine is shown in Fig. 1(a). It mainly includes mechanical power, mechanical transmission, mechanical execution and weight loading, as shown in Fig. 1(b). In the mechanical transmission part, the motor drives the crank to rotate, and then the connecting rod transmits the kinetic energy of the crank to the swing
Numerical simulation of wear experiment
The finite element software ANSYS is used for numerical simulation. The type of the U-shaped connecter in the experiment is U-12, which is made of Q235 carbon structural steel. It can be seen from the experiment that the lower U-shaped connecter will rotate around the upper U-shaped connecter under wind load, causing relative wear. The results show that the wear loss of the upper U-shaped connecter is greater than that of the lower one. In order to improve the accuracy of numerical simulation
Statistics of wind field
At present, many countries in the world use the annual maximum wind speed as the sample for probability statistics. The maximum or the basic wind speed for the region is obtained from the return period and the probability distributions of wind speeds. The function of Extreme-Value Type I Distribution is used to analyze the basic wind speed [29]. The expression of Extreme-Value Type I Distribution is as followsWhere and are respectively the position and scale parameters,
Conclusions
The wear experiment and the finite element simulation of the U-shaped connecter were carried out, and the influencing factors of wear were discussed. The Harmonic Synthesis Method was applied to simulate the wind field of the boundary layer, and a three-span transmission line model was established to investigate the wear behavior of the fittings under strong wind conditions. The safe service life of U-shaped connecter was predicted and the following conclusions are obtained:
- (1)
The wear experiment
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This study is supported by the National Natural Science Foundation of China (Grant No.: 51778097), Natural Science Foundation of Chongqing Science and Technology Commission (Grant No.: cstc2017jcyjB0210).
References (29)
- et al.
Influence of the catenary parameter(H/w) on the fatigue life of overhead conductors
Tribol. Int.
(2017) - et al.
Effect of high mean tensile stress on the fretting fatigue life of an Ibis steel reinforced aluminium conductor
Int. J. Fatigue
(2012) - et al.
Fretting fatigue in overhead conductors: Rig design and failure analysis of a Grosbeak aluminium cable steel reinforced conductor
Eng. Fail. Anal.
(2009) - et al.
Effect of atmospheric pollutants on the corrosion of high power electrical conductors: Part 1. Aluminium and AA6201 alloy
Corros. Sci.
(2006) - et al.
Effects of surface texturing on the frictional behavior of cast iron surfaces
Tribol. Int.
(2014) - et al.
Assessment of the fatigue failure of an All Aluminium Alloy Cable (AAAC) for a 230 kV transmission line in the Center-West of Brazil
Eng. Fail. Anal.
(2016) - et al.
Failure analysis of aluminum cable steel reinforced (ACSR) conductor of the transmission line crossing the Paraná River
Eng. Fail. Anal.
(2002) - et al.
Finite element simulation of fretting wear and fatigue in thin steel wires
Int. J. Fatigue
(2013) - et al.
Single wire fretting fatigue tests for electrical conductor bending fatigue evaluation
Wear
(1995) - et al.
Effect of lubricant in electrical conductor fretting fatigue
Wear
(1995)
Damage investigation of the aged aluminium cable steel reinforced (ACSR) conductors in a high-voltage transmission line
Eng. Fail. Anal.
Experimental and finite element analysis of fatigue strength for 300 mm2 copper power conductor
Mar. struct.
Mechanics and materials in fretting
Wear
A boundary element formulation for wear modeling on 3D contact and rolling-contact problems
Int. J. Solids Struct.
Cited by (4)
Analysis of the quality of aluminum overhead conductors after 30 years of operation
2023, Engineering Failure AnalysisGeometric Nonlinear Analysis of Self-Supporting Structures for Overhead Transmission Lines
2023, Practice Periodical on Structural Design and ConstructionNumerical Investigation on the Dynamic Response and Fatigue Analysis of the Tension Insulator String Under Stochastic Wind
2022, IEEE Transactions on Power DeliveryStudy on the Inefficiency of Transmission Lines Under the Condition of Severe Ice Wind
2022, Lecture Notes in Electrical Engineering