Method for holistic wind turbine drivetrain comparison exemplarily applied to geared and direct drive systems (original) (raw)
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In order to identify holistically better drivetrain concepts for onshore wind turbine application, their operational behavior needs to be considered in an early design phase. In this paper, a validated approach for estimating drivetrain-concept-specific unplanned operational effort and risk based on open-access data is presented. Uncertain influencing factors are described with distribution functions. This way, the poor data availability in the early design phase can be used to give an indication of the concept's choice influence on the unplanned operational wind turbine behavior. In order to obtain representative comparisons, a Monte Carlo method is applied. Technical availability and drivetrain-influenced unplanned operational effort are defined as evaluation criteria. The latter is constituted by labor, material and equipment expenses. By calculating the range of fluctuation in the evaluation criteria mean values, this approach offers an indication of the inherent risk in the operational phase induced by the drivetrain concept choice. This approach demonstrates that open-access data or expert estimations are sufficient for comparing different drivetrain concepts over the operational phase in an early design stage when using the right methodology. The approach is applied on the five most common state-of-the-art drivetrain concepts. The comparison shows that among those concepts the drivetrain concept without a gearbox and with a permanent magnet synchronous generator performs the best in terms of absolute drivetrain-influenced unplanned operational effort over the drivetrain's lifetime as well as in terms of the inherent risk for the assumptions made. It furthermore makes it possible to give insights into how the different drivetrain concepts might perform in future applications in terms of unplanned operational effort. Exemplarily the impacts of higher torque density in gearboxes, a change to moment bearings and adjusted coil design in electrically excited generators have been analyzed. This analysis shows that the superiority of synchronous-generator concepts manifested in historic data is not entirely certain in future applications. Concluding, this approach will help to identify holistically better wind turbine drivetrain concepts by being able to estimate the inherent risks and effort in the operational phase.
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Clean Technologies and Environmental Policy, 2019
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Techno-Economic Comparison of Operational Aspects for Direct Drive and Gearbox-Driven Wind Turbines
The majority of wind turbines currently in operation have the conventional Danish concept design-that is, the threebladed rotor of such turbines is indirectly coupled with an electrical generator via a gearbox. Recent technological developments have enabled direct drive wind turbines to become economically feasible. Potentially, direct drive wind turbines may enjoy higher levels of availability due to the removal of the gearbox from the design. However, this is only a theory: so far not substantiated by detailed analytic calculation. By providing such a calculation, this paper enables us to quantitatively evaluate technical and economic merits of direct drive and gearbox-driven wind turbines.
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In the context of industrial competitiveness, taking into account the process design throughout the product life cycle is inevitable, from the expression of the need to recycle, the capitalization and knowledge management increasingly a target much sought after companies because of increased knowledge. Indeed, during the approval phase and use studies and scientific researches make have generated knowledge especially that concerning the reliability of system components. Methods of the knowledge structuring in mechanical design, based on functional approaches are analyzed and compared. We propose an energy approach based on the Law of System Completeness, which decomposes a system specific entity. This article provides help in the choice of solutions to the phase of preliminary design between direct-drive and geared drive wind turbine concepts, based an analytical reliability methods. Reliability data from field surveys will be used in this study in particular the failure rate. First, we propose a model of reliability of both existing and modified concepts, using a decomposition of systems at a detailed level, then qualification will be carried out of the global model is done with respect to the need expressed by the user, and which is the reason for its existence. Such a tool is intended to help designers make decisions about the choices inherent in comparison between these concepts.
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Development of a quantitative analysis system for greener and economically sustainable wind farms
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The eco-conscious wind turbine: bringing societal value to design
Wind turbines are designed to minimize the cost of energy, a metric aimed at making wind competitive with other energyproducing technologies. However, now that wind energy is competitive, how can we increase its value for society? And how much would a societal gain cost other stakeholders, such as investors or consumers? This paper tries to answer these questions from the perspective of wind turbine design. Although wind turbines produce green renewable energy, they also generate various impacts on the environment, as all human endeavours. Among all impacts, the present work adopts the environmental effects produced by a turbine over its entire life cycle, expressed in terms of CO 2-equivalent emissions. A new approach to design is proposed, whereby Pareto fronts of solutions are computed to define optimal trade-offs between economic and environmental goals. The new proposed methodology is demonstrated on the redesign of a baseline 3 MW wind turbine at two locations in Germany, differing for typical wind speeds. Among other results, it is found that, in these conditions, a 1% increase in the cost of energy can buy about a 5% decrease in the environmental impact of the turbine. Additionally, it is also observed that in the specific case of Germany, very low specific-power designs are typically favored, because they produce more energy at low wind speeds, where both the economic and environmental values of wind are higher. Although limited to the sole optimization of wind-generating assets at two different locations, these results suggest the existence of new opportunities for the future development of wind energy where, by shifting the focus slightly away from a purely cost-driven short-term perspective, longer-term benefits for the environment (and, in turn, for society) may be obtained.
A review of life cycle assessments on wind energy systems
The International Journal of Life Cycle Assessment, 2012
Purpose Several life cycle assessments (LCA) of wind energy published in recent years are reviewed to identify methodological differences and underlying assumptions. Methods A full comparative analysis of 12 studies were undertaken (10 peer-reviewed papers, 1 conference paper, 1 industry report) regarding six fundamental factors (methods used, energy use accounting, quantification of energy production, energy performance and primary energy, natural resources, and recycling). Each factor is discussed in detail to highlight strengths and shortcomings of various approaches. Results Several potential issues are found concerning the way LCA methods are used for assessing energy performance and environmental impact of wind energy, as well as dealing with natural resource use and depletion. The potential to evaluate natural resource use and depletion impacts from wind energy appears to be poorly exploited or elaborated on in the reviewed studies. Estimations of energy performance and environmental impacts are critically analyzed and found to differ significantly. Conclusions and recommendations A continued discussion and development of LCA methodology for wind energy and other energy resources are encouraged. Efforts should be made to standardize methods and calculations. Inconsistent use of terminology and concepts among the analyzed studies are found and should be remedied. Different methods are generally used and the results are presented in diverse ways, making it difficult to compare studies with each other, but also with other renewable energy sources.