Modeling and Quantifying the Aerodynamic Characteristics of Transmission Line Structures to Avoid and Mitigate Aeolian-Induced Vibrations

There has been a significant increase in the number of EHV (345 kV and above) tubular transmission lines in the United States in the last decade. At EHV levels, these structures are tall (for clearance reasons) and slender (for economic reasons and lack of appropriate criteria) structures. These structures are often located in rural areas with flat terrain and significant wind exposure and their dynamic behavior is not well understood by transmission line designers. For these reasons, there have been more reported incidents of wind-induced vibrations and damage to transmission line structures, substation A-frame structures, and static masts. This study focuses on lines and stations in the midwest and Texas areas that are relatively flat and exposed to steady-state winds. Historically, those that have experienced these phenomena have had to seek assistance from aeronautical experts outside our industry or consider the expensive option of wind-tunnel testing. However, with the advent of commercially available super-computing, this is no longer the case. Software providers now offer Cloud based computing platforms wherein a user pays hourly for computation time on a 32-core computer. The computation allows a transient airflow analysis on the subject structure to study the flow characteristics in the wake region. With this computational fluid dynamic (CFD) analysis, aeronautical damping (strakes or other geometrical additions) can be designed and implemented. Within the same software, once the aeroelastic response is found, the model can be analyzed with the finite element method to provide vibration amplitudes and stress levels in various members.