Typhoon Haikui captured through Dual Doppler Radar measurements

The safety and performance of wind turbines depend on assumption about the wind they experience. This study examines whether those assumptions which are defined in the International Electrotechnical Commission (IEC) standard 61400-1¹ remain valid under typhoon conditions through analysis of Dual Doppler Radar measurements from a case study. The IEC standards include simplified representations of wind behaviour which is widely used within turbine design and load calculations. However, it is unclear if these assumptions are still applicable during typhoons conditions. A case study of Typhoon Haikui in the Western Pacific is presented. In late August 2023 the typhoon approached Taiwan from the east, crossed the southern part of the island before reaching the Formosa strait, it then crossed the strait and continued toward mainland China. As the typhoon passed over Taiwan, a dual Dopper radar system captured high-resolution wind measurements. This provides a unique opportunity to analyse the wind field of a nearby typhoon.

Using these observations, several wind field characteristics are examined and evaluated against the assumption used in the IEC standards. The assumptions include the logarithmic vertical wind profile, a constant shear exponent, prescribed gust characteristics and a spatially uniform wind field. The high spatial and temporal resolution of the dataset allows these assumptions to be examined throughout the evolution of the storm and across different spatial locations. The exploration of how these parameters vary relative to the proximity to the coastline of Taiwan, and the phase of the typhoon shows that the wind characteristics can be unsteady and inhomogeneous.

Preliminary analysis suggests that several wind field characteristics exhibit spatial and temporal variability during the typhoon, indicating that some of the simplified assumptions may not fully represent the wind behaviour during typhoon conditions. These findings contribute to an improved understanding of extreme wind feature and provide insight relevant for the risk assessment and design of wind turbines operating in typhoon-prone regions.

We thank Ørsted for making the data available and Smart Wind Technologies for their development of products and services related to this research².

 

¹International Electrotechnical Commission: Design Requirements, Wind Energy Generation Systems / International Electrotechnical Commission, International Electrotechnical Commission, Geneva, Switzerland, edition 4.0 edn., ISBN 978-2-8322-6253-5, 2019.

² EU Patent 2877741:  System and Method for Evaluating Wind Flow Fields using Remote Sensing Devices.  John L. Schroeder, Brian D. Hirth, and Jerry G. Guynes.  Issued March 28, 2019