Analysis of Extreme Winds at Pacific Northwest Wind Energy Survey Sites.

Abstract

The purpose of this report is to examine extreme winds at wind energy survey sites in the Pacific Northwest and to forecast future extremes. Additionally this report reviews previous estimates of extreme winds in the Pacific Northwest and evaluates available statistical approaches to extreme wind estimates. A review of the literature on wind indicated the most widely used extreme wind statistic is the one minute mean fastest wind speed. However, in this study the data that were available for use were hourly average extreme winds and peak 2 second gusts or instantaneous gusts. This information was collected as part of Bonneville Power Administrations Wind Energy Resource Assessment Program. Among the problems encountered in extreme wind estimation is the lack of long term continuous, uniform data sets. Frequent changes in anemometer height and location have plagued analysis of extreme winds. Conventional methods of estimating extreme winds requires data collected over 20 to 30 years. However in this study, data records seldom exceed two to three years and the longest are only 10 years. Different averaging times and data collection techniques have been noted as significant obstacles to uniform data sets. Another significant problem with many data sets is the problem ofmore » the dynamic range of the measuring instrument being insufficient to record the strongest winds. 45 refs., 32 figs., 23 tabs.« less