Analytical prediction of quasi-static responses of transmission lines under moving downbursts: A nonlinear model with linear approximation

Downbursts wind are believed to be responsible for most of weather-related transmission line failures worldwide. Based on a theoretical model of a hinged single-span transmission line structure under moving downbursts, this paper studies downburst -induced vibration of a multi-span transmission line-insulator system (MSTLIS). Firstly, a nonlinear analytical framework for quasi-static responses of the MSTLIS under moving downbursts is established, and linearized equations of the MSTLIS under moving downbursts with time-varying mean wind speeds are derived. Then, the influence line functions of the insulator tension and displacement of the MSTLIS are derived, based on which the quasi-static responses of the MSTLIS under fluctuating wind is calculated. A case study on a six-span transmission line-insulator subsystem is conducted. The proposed nonlinear analytical model and the approximate linearization approach is verified by finite element model (FEM) results. The proposed analytical framework with linear approximation is accurate and more efficient than FEM, and hence has a great potential for real application.