Wind induced tonal noise from electrical power transmission infrastructure

Electrical power is often generated far from where it is used, resulting in a vast transmission system. Large outdoor infrastructure such as transmission towers are exposed to high winds which can interact with components to generate tonal noise at problematic sound levels. This paper reviews mechanisms of flow induced tonal sound and components of electrical power transmission infrastructure known to produce tonal noise when excited by wind, including flexible cables and electrical insulators. Investigations are often challenging given the electrical safety concerns, scale of infrastructure, remote locations, and the intermittent nature of the precise atmospheric conditions required for sound generation. A case study is also presented in which a noise issue involving towers of a 230 kV transmission line was diagnosed and resolved. A loud tonal noise was reported to cause significant disturbances nearby and to be audible up to about one mile distant. A structural component was analyzed as an acoustic resonator using the transfer matrix method to model the impedance of branches and holes. Mitigation measures were applied that did not adversely affect operation of the line, and the efficacy of noise controls confirmed the sound generating mechanism.