Statistical Study of Aeolian Vibration Characteristics of Overhead Conductor

Overhead transmission conductors are vulnerable to fretting fatigue due to aeolian vibrations. Accurate estimation of vibration severity is essential to determine the residual life of in-service lines and to schedule timely maintenance or replacement. For most transmission line networks, vibration monitoring systems are not available, and thus the vibration hazards must be derived from local wind conditions. The most widely accepted estimation procedure of the severity of aeolian vibration is by calculating the maximum oscillation amplitudes of the conductor based on the Energy Balance Principle (EBP), which establishes the balance between the energy transmitted to the conductor by the wind and the energy dissipated by self-damping of the conductor and dampers. 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 distribution of vibration amplitudes and number of cycles for each amplitude are required to calculate cumulative damage due to fretting fatigue. In this paper, vibration data from an experimental undamped ACSR test line in Quebec, Canada, is analyzed in conjunction with concurrent winds over a 2-month period. The first step of the analysis is to identify observations corresponding to aeolian vibrations in both the time and frequency domains. 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 understand the relationship between vibration profiles and wind input, taking into consideration the influence of wind speed and turbulence intensity, as well as the influence of conductor tension.