Wind Energy

8
Power Performance via Nacelle Anemometry
on Complex Terrain
Etienne Bibor and Christian Masson
8.1 Introduction and Objectives
In order to improve the performance of wind turbines (WT) and to reduce
discrepancies between concerned parties, testing standards have been developed.
Those proposed by the International Electrotechnical Commission
(IEC 61400-12) constitute an international reference. However, several aspects
treated in these standards are not perfectly well understood or are based on
inappropriate assumptions. For example, the power performance verification
of a wind park on complex terrain raises significant difficulties related to the
technique of nacelle anemometry [1]. The goal of the present study is to evaluate
the precision of this technique on complex terrain.
8.2 Experimental Installations
To perform this study, experimental installations have been deployed on a very
complex site in Eastern Canada. Three WTs are present at the Riviere-Au-
Renard Wind Farm (PER). The WT have a nominal power of 750 kW, with a
rotor diameter of 48 m and a hub height of 46 m. They are active control WT,
with variable speed and fixed pitch angle. The rotational speed, with a range
between 8.5 and 24.8 rpm, is adjusted in order to operate as often as possible
at the optimal point, CP,max. This CP,max of 0.425 occurs approximately at a
tip speed λ of 7.2 (λ = ΩR/V∞, where Ω represents the rotational speed and
R is the rotor radius)
8.3 Experimental Analysis
An experimental analysis has been undertaken. The first step was to perform a
site calibration. For every valid sectors of 10 ◦ , a correlation between Vref ⇔ V∞