Critical evaluation of methods for wind-power appraisal

In the literature, several methods are being used to evaluate the contribution of wind energy conversion systems in a broader power-generating system. However, not all of them guarantee accurate results. This paper critically reviews several methods used in the literature for such reliability evaluations. There are three types of methods characterised by the details considered and the simplifications made: (1) methods using complete chronological data; measured or calculated; (2) methods using a truncated set of chronological data and (3) methods disregarding the chronology all together. In order to test the different possible simplifications, we calculate a case study for a potential wind farm. The result of the full chronological calculation is used as a benchmark to which the results of the simplified methods can be verified. The truncated method is found to be reliable when more than the top 25% chronological values are used. The methods in which the chronology is disregarded were not found accurate because of the significant correlation between consecutive wind-speed measurements embedded in the chronological data. We therefore conclude that the most accurate results are obtained when the full chronology of both the wind-power output and the power-generation requirement are used. Most simplifications considered with the aim to limit the amount of data needed and thus to save computation time and data-gathering effort are not really justified.