Impact of Extreme Weather on Transmission Line Structures

摘要

High Intensity Wind (HIW) associated with tornadoes and microbursts pose a major threat to transmission line networks in Ontario and many other regions around the world. Almost all transmission structures failures in Ontario in the last 15 years can be attributed to HIW, particularly microbursts. However, when assessing the structural adequacy in accordance to current designs codes, the codes assume that synoptic wind profile provides the basis of wind loading in the design process and does not consider the HIW components associated with severe thunderstorms. Such assumptions may be leaving transmission networks exposed to an unquantified level of threat to a meteorological events associated with severe thunderstorms. In this paper, the models for tornadoes and microbursts are discussed and a case study is presented to demonstrate the destructive effects of these extreme wind events. Recommendations for revising the design criteria for extreme weather are given.