Methodology for Simulation of Combined EPS and TS Wind Field and Its Influence on the Dynamic Response of a Transmission Line Segment

Abstract

So far, wind loads on structures are almost exclusively evaluated by Extended Pressure Systems (EPS) cyclone models according to design codes. However, there is evidence that downburst wind fields, originating from thunderstorms (TSs) events, may have caused or contributed to the collapse of transmission line towers around the world. In this context, this work proposes a complete methodology to simulate a wind field from combined EPS (synoptic) and TS (nonsynoptic) storms. The proposed combined wind field model is applied to a real transmission line segment and the results are compared with those of the system subjected to the equivalent static loading method proposed in the IEC 60826/2003 code. The finite central differences explicit method is adopted for dynamic integration, taking into account nonlinearities. The assessment confirmed the localized and transient nature of the TS phenomenon. The results indicated that, for most of the elements analyzed, the equivalent static method for synoptic winds of IEC 60826/2003 resulted in a lower response than that obtained through the proposed combined model, which considers a TS carried by an EPS background wind. Thus, the proposed method to combine synoptic and nonsynoptic wind fields might be a useful tool to assist in the design of structures, such as transmission lines, which are susceptible to the effects of combined EPS and TS wind fields.