Characterization of Ice and Concurrent Wind for Loading of Transmission Line Structures in Iran

Document Type : Research Article


1 Faculty of Niroo Research Institute (NRI), Tehran, Iran

2 Electric Power Structural Research Group, Niroo Research Institute (NRI), Tehran, Iran


In this paper, the parameters required for the ice and concurrent wind loading case, including the radial equivalent ice thickness and the concurrent wind speed for the return periods in the structures of the power transmission lines, are determined according to the standard criteria of IEC 60826. Loading parameters have been calculated using two-variable hazard curves and compared with simplified methods in IEC 60826. Ice and concurrent wind hazard curves are prepared using data recorded in 15 selected meteorological stations in the cold regions of the country (including heavy and ultra- heavy areas according to the climate-zoning map of the transmission lines). Numerical simulations (CRREL model for Freezing Rain and Cylindrical Growth of Wet Snow Sleeves model for Wet Snow) have been used to determine the thickness of ice formed around the conductor of the transmission lines due to the lack of direct data from the measurement. The results show significant conservatism of the reduction factors of the ice and concurrent wind in IEC 60826 standards at most of the studied meteorological stations. Accordingly, using the ice and wind hazard curves at the stations, the reduction factors are determined and presented to calculate the values of loading parameters in ice and wind loading case in terms of their reference values (which are available in the zoning maps). The proposed reduction factors are consistent with the standards of IEC 60826 and are suitable for use in loading and designing the structures of transmission lines with different return periods in the cold regions of the country.


Main Subjects

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