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Validation de la technique d'anémométrie à la nacelle en terrain complexe

Bibor, Étienne (2005). Validation de la technique d'anémométrie à la nacelle en terrain complexe. Mémoire de maîtrise électronique, Montréal, École de technologie supérieure.

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Résumé

Dans l'industrie éolienne, les normes proposées par l'International Electrotechnical Commission (IEC) constituent la référence internationale. Cependant, certains aspects demeurent encore mal définis, notamment la vérification des performances d'un parc éolien sur terrain complexe. Cette étape soulève des difficultés importantes reliées à l'anémométrie à la nacelle. Le but de la présente étude est d'évaluer la précision de cette technique sur des terrains complexes. Afin d'analyser cette problématique, des installations expérimentales ont été déployées sur le site très complexe de Rivière-Au-Renard en Gaspésie. Une analyse expérimentale y fut menée afm d'obtenir les corrélation entre les vitesses à la nacelle V nac et les vitesses non perturbées de l'écoulement V inf . L'influence du terrain a ainsi pu être analysée. Finalement, un modèle numérique a été développé en utilisant le logiciel commercial FLUENT afin de mieux comprendre l'effet des différents paramètres présents dans la problématique de l'anémométrie à la nacelle.

Titre traduit

Power performance via nacelle anemometry on complex terrain

Résumé anglais

Various critical factors of our time explain the great popularity that the wind power industry has experienced in the last decades. In order to improve the performance of this type of energy and to reduce the discrepancies between concerned parties, standards have been developed. Those proposed by the International Electrotechnical Commission (IEC) constitute the international reference. However, several aspects treated in these standards are not perfectly well understood or are based on inappropriate assumptions. For example, the power performances verification of a wind park on complex terrain raises significant difficulties related to the technique of nacelle anemometry. The basis of this technique is to establish a relationship between the nacelle wind speed (Vnac) and the free-stream wind speed (Voo) of the reference wind turbine. The assumption stipulating that this correlation can be applied to all the other machines in the park is only valid for flat terrain. The goal of this study is to evaluate the precision of this technique on complex terrain.

To perform this study, experimental installations have been deployed on a very complex site in Rivière-Au-Renard in Gaspésie. More precisely, three meteorological masts, instrumented at four different heights, were installed around the reference wind turbine of the Wind Park Rivière-Au-Renard (PÉR). In addition, a reference tower was already present on the site. To complement the data from the four meteorological masts, those of the reference wind turbine were also available.

Initially, a summary of the current procedures of power performance verification has been carried out. Thereafter, an experimental analysis has been realized in order to obtain a correlation between Vnac and Voo, which is the base of nacelle anemometry. The latter was compared with the correlation provided by the manufacturer, measured on flat terrain. Considerable differences up to 1.59m/s were measured. This variation illustrates the significant influence of the terrain and the environment on this correlation. During power performance testing, the use of the manufacturer's correlation leads to unrealistic results, with power coefficients (Cp) higher than the theoretical limit. These results confirm the inappropriateness in using a common correlation for all wind turbines of the same type, in complex terrain. This difference involves errors during the estimate of Voo, having significant repercussions in the active control of the wind turbine (WT). This sequence of problems explains partly why the performances of the WT are lower than those predicted.

In the second stage, the influence of the ground was investigated by calculating correlations for each valid sector of 10 deg, rather than using only one general correlation. lt is thus possible to quantify the effect of the ground on nacelle anemometry. Between the sectors, significant differences were found. Then, two power curves have been calculated by using the correlations by sectors, or by taking the general correlation, as carried out in industry. Once again, considerable differences were observed, varying between -10% and 10%. However, during the calculation of the annual energy production (AEP), the variations were reduced to 0.65%. This is explained by a compensatory effect due to the fact that certain variations are positive and other negative. Although involving very marked specific errors, the use of a general correlation does not generate major errors over a long period.

Finally, a numerical model was developed using the commercial software FLUENT. This numerical approach allows a better understanding of the effect of the different parameters present in nacelle anemometry. One of the conclusions of this analysis, is that the correlation is largely influenced by the section at the root of the blade, and very little by the airfoils located higher. Another conclusion is that one of the major causes influencing the correlation comes from the acceleration of the flow caused by the attachment unit of the anemometer. If such a system cannot be avoided, then the calibration of the anemometer should be done with the whole system.

Type de document: Mémoire ou thèse (Mémoire de maîtrise électronique)
Renseignements supplémentaires: "Mémoire de maîtrise présenté à l'École de technologie supérieure comme exigence partielle à l'obtention de la maîtrise en génie mécanique". Bibliogr : f. [136]-138.
Mots-clés libres: Énergie éolienne. Analyse, Anemometrie. Complexe, Experimental, Mathematique, Methode, Modele, Nacelle, Numerique, Technique, Terrain, Validation
Directeur de mémoire/thèse:
Directeur de mémoire/thèse
Masson, Christian
Programme: Maîtrise en ingénierie > Génie mécanique
Date de dépôt: 26 janv. 2011 14:53
Dernière modification: 31 oct. 2016 23:50
URI: http://espace.etsmtl.ca/id/eprint/385

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