Wind Turbine Failures - Tackling current Problems in Failure Data Analysis

The wind industry has been growing significantly over the past decades, resulting in a remarkable increase in installed wind power capacity. Turbine technologies are rapidly evolving in terms of complexity and size, and there is an urgent need for cost effective operation and maintenance (O&M) strategies. Especially unplanned downtime represents one of the main cost drivers of a modern wind farm. Here, reliability and failure prediction models can enable operators to apply preventive O&M strategies rather than corrective actions. In order to develop these models, the failure rates and downtimes of wind turbine (WT) components have to be understood profoundly. This paper is focused on tackling three of the main issues related to WT failure analyses. These are, the non-uniform data treatment, the scarcity of available failure analyses, and the lack of investigation on alternative data sources. For this, a modernised form of an existing WT taxonomy is introduced. Additionally, an extensive analysis of historical failure and downtime data of more than 4300 turbines is presented. Finally, the possibilities to encounter the lack of available failure data by complementing historical databases with Supervisory Control and Data Acquisition (SCADA) alarms are evaluated

SCADA alarms processing for wind turbine component failure detection

Wind turbine failure and downtime can often compromise the profitability of a wind farm due to their high impact on the operation and maintenance (O&M) costs. Early detection of failures can facilitate the changeover from corrective maintenance towards a pre- dictive approach. This paper presents a cost-effective methodology to combine various alarm analysis techniques, using data from the Supervisory Control and Data Acquisition (SCADA) system, in order to detect component failures. The approach categorises the alarms according to a reviewed taxonomy, turning overwhelming data into valuable information to assess component status. Then, different alarms analysis techniques are applied for two purposes: the evaluation of the SCADA alarm system capability to detect failures, and the investigation of the relation between components faults being followed by failure occurrences in others. Various case studies are presented and discussed. The study highlights the relationship between faulty behaviour in different components and between failures and adverse environmental conditions

Accurate recovery-based error upper bounds for the extended finite element framework

[EN] This paper introduces a recovery-type error estimator yielding upper bounds of the error in energy norm for linear elastic fracture mechanics problems solved using the extended finite element method (XFEM) The paper can be considered as an extension and enhancement of a previous work in which the upper bounds of the error were developed in a FEM framework The upper bound property requires the recovered solution to be equilibrated and continuous The proposed technique consists of using a recovery technique, especially adapted to the XFEM framework that yields equilibrium at a local level (patch by patch) Then a postprocess based on the partition of unity concept is used to obtain continuity The result is a very accurate but only nearly-statically admissible recovered stress field, with small equilibrium defaults introduced by the postprocess Sharp upper bounds are obtained using a new methodology accounting for the equilibrium defaults, as demonstrated by the numerical testsThis work has been carried out within the framework of the research projects DPI2007-66773-C02-01, DPI2007-66995-C03-02 and DPI2007-62395 of the Ministerio de Educacion y Ciencia (Spain). The financial support of the Generalitat Valenciana and the Universidad Politecnica de Valencia is also acknowledged.Ródenas, J.; Gonzalez-Estrada, O.; Díez, P.; Fuenmayor Fernández, F. (2010). Accurate recovery-based error upper bounds for the extended finite element framework. Computer Methods in Applied Mechanics and Engineering. 199(37-40):2607-2621. https://doi.org/10.1016/j.cma.2010.04.010S2607262119937-4

Optical Particle Detection in Liquid Suspensions with a Hybrid Integrated Microsystem

AbstractA compact, robust and portable system for optical particle detection in liquid suspensions, achieved through the hybrid integration of commercial components, such as VCSELs and microlenses, in a silicon micromachined structure is presented. We demonstrate the feasibility of fabricating a device providing up to 4 collimated laser beams, with the ability of detecting and distinguishing microparticles of several diameters, even in mixed suspensions. This optical microsystem represents an alternative design for microflow cytometers based on optical fibres, and is aligned with the current tendency set by the Point-of-care devices

Apparent digestibility and metabolizable energy content of lipid sources in poultry

A trial was conducted to determine the apparent digestibility (ATTD) and AME content of different lipid sources in 21d-old broilers. There were a control diet based on corn and soybean meal without any supplemental fat and 6 additional diets forming a 3x2 factorial with 3 sources of fat (soy oil, SBO; reconstituted monoglyceride oil, RMG; and reconstituted triglyceride oil, RTG) included in the diet (3 or 6%) at expenses (wt:wt) of the basal diet

Kinetic Roughening in Deposition with Suppressed Screening

Models of irreversible surface deposition of k-mers on a linear lattice, with screening suppressed by disallowing overhangs blocking large gaps, are studied by extensive Monte Carlo simulations of the temporal and size dependence of the growing interface width. Despite earlier finding that for such models the deposit density tends to increase away from the substrate, our numerical results place them clearly within the standard KPZ universality class.Comment: nine pages, plain TeX (4 figures not included

Dense panoramic stereovision : camera calibration and image rectification

The particular geometry of panoramic cameras defines complex epipolar lines equations. In this paper, we present a way to warp images from a panoramic stereovision bench, so that the epipolar lines become parallel straight lines, thus allowing the use of an optimized fast pixel correlation based stereovision algorithm. The paper first introduces the geometric characterization of panoramic camera composed of parabolic and spherical mirrors, that computes both the intrinsic parameters of the system (mirror surfaces and intrinsic camera parameters) and the errors alignment between the mirrors. Then, it presents the warping equations that allow to generate rectified images. Calibration and stereovision results are presented.La stéréovision panoramique est une fonctionnalité très intéressante, particulièrement en robotique. Cependant, la géométrie particulière des caméras panoramiques définit des épipolaires dont les équations ne sont pas triviales. Dans cet article, nous présentons un moyen de rectifier les images d’un banc stéréoscopique panoramique, qui fournit des images dans lesquelles les épipolaires sont des lignes parallèles, ce qui permet l’application d’un algorithme optimisé de stéréovision par corrélation des pixels. La première partie de l’article présente un modèle géométrique de formation des images pour une caméra catadioptrique composée d’un miroir parabolique et d’un miroir sphérique, qui inclut les paramètres intrinsèques du système (surfaces des miroirs et paramètres intrinsèques de la caméra), et aussi les erreurs d’alignement entre les miroirs. Une procédure qui permet de rectifier les images panoramiques est ensuite présentée, et des résultats de calibrage et de stéréovision panoramique illustrent l’article

Statistical evaluation of SCADA data for wind turbine condition monitoring and farm assessment

Operational data from wind farms is crucial for wind turbine condition monitoring and performance assessment. In this paper, we analyse three wind farms with the aim to monitor environmental and operational conditions that might result in underperformance or failures. The assessment includes a simple wind speed characterisation and wake analysis. The evolution of statistical parameters is used to identify anomalous turbine behaviour. In total, 88 turbines and 12 failures are analysed, covering different component failures. Notwithstanding the short period of data available, several operational parameters are found to deviate from the farm trend in some turbines affected by failures. As a result, some parameters show better monitoring capabilities than others, for the detection of certain failures. However, the limitations of SCADA statistics are also shown as not all failures showed anomalies in the observed parameters

Catalogue des habitats forestiers de Guyane

Grâce à de nombreux efforts de prospections et d'inventaires naturalistes, la biodiversité guyanaise est de mieux en mieux connue et les listes d'espèces nouvelles ne cessent de s'allonger années après années. Cependant l'écosystème forestier ne se résume pas à une juxtaposition d'individus et d'espèces : de complexes relations interspécifiques régissent le fonctionnement des communautés qui sont elles-mêmes influencées par les conditions environnementales. dans lesquelles elles se développent. Gérer et conserver la biodiversité guyanaise implique de mieux cerner ces interactions entre faune, flore et environnement ; interactions qui façonnent toute une diversité d'habitats forestiers avec des dynamiques propres et des compositions originales. Plusieurs programmes de recherche se sont attelés à démêler cet écheveau écologique en se concentrant tout d'abord sur quelques plateformes scientifiques (Paracou, Nouragues, Piste de Saint-Elie) puis en élargissant la focale à l'ensemble de notre territoire sous l'impulsion des gestionnaires publics et des associations naturalistes guyanaises (programmes de recherche DIME, ECOTROP, HABITATS, etc.). Ce catalogue des habitats forestiers présente une synthèse de ces résultats sous la forme de fiches descriptives dressant un portrait précis des différents habitats naturels rencontrés en forêt guyanaise et des mécanismes qui les ont peu à peu façonnés. Un travail collectif important a été accompli pour fournir des éléments précis concernant les cortèges de grande faune, les peuplements d'arbres qui les abritent et la qualité des sols qui les supportent