1,721,373 research outputs found
How to comply with Megatrend Requirements : Increasing Efficiency of Wind Turbine Generators by Choice of the Right Lubricant
No full textHow to comply with Megatrend Requirements : Increasing Efficiency of Wind Turbine Generators by Choice of the Right Lubricant
No full textDevelopment of hierarchical testing workflows to support virtual verification of technical systems
No full textThe increasing complexity of technical systems requires more powerful system development approaches to withstand or further reduce cost pressure and time-to-market. Model-Based Systems Engineering (MBSE) is a promising approach for increasing the efficiency of system development processes. MBSE relies on virtual system models as central development artifacts. The modeling methods use formal system models to describe system requirements, functions, as well as solutions, and link the input/output data of the system with each other. System models can generally be used to test physical system behavior at early stages by integrating domain simulation models. The virtual verification process sequentially performs activities to support design decisions before prototypes. However, there is a lack of methods for building structured, reusable, and efficient workflows and integrating these workflows into system models to support the virtual verification process. The goal of this work is the development of executable virtual test workflows across hierarchy levels of the system, allowing for the testing of modeled solution architectures based on specific requirements while ensuring data consistency between the hierarchical levels of the system. The workflows contain activities as modules that automatically execute simulation models within the individual domains. Test workflows are carried out according to various test scenarios concerning system scopes, model purposes, and model fidelities. The developed method for designing workflows is tested using a case study, the system development process for wind turbine (WT) systems. The modularity and efficiency improvement of the process design are discussed using the case study, and generalizations are derived
Simulative Ermittlung des Belastungszustandes im Antriebsstrang von Windenergieanlagen im Betrieb
No full textThe increasing use of wind turbines (WTs) and the growing share of wind power in the electricity mix require high reliability of the turbines and early detection of faults. This can be achieved, among other things, by continuous monitoring of the technical condition of the plants. An analysis of reliability studies shows that bearings and gears in the gearbox as well as the main bearing are responsible for the largest share of WT downtimes. The main objective of this work is to develop a system performance indicator that describes the degradation of wind turbines taking into account the real loads, using the same means that are applied in the design calculation. A model for the calculation of local loads on machine elements of the drive train is constructed. The quality of the results is evaluated using a validated multi-body simulation model. Based on the fatigue calculation, degradation performance indicators are determined for the relevant components and the WT as a system. To demonstrate the real applicability, three identical, neighboring turbines of a wind farm are examined. It can be shown that the developed performance indicator allows a clear differentiation of the degradation states
Auslegung von auf Drehschub belasteten Elastomerkupplungen unter thermisch-mechanischer Beanspruchung
No full textThe presented work deals with the dimensioning of highly dynamically loaded elastomer couplings under a combined thermal and mechanical load. For this, firstly a state-of-the-art is given. Based on the works of Bauermeister and Mödder and in recourse on own pre-publications the behavior of elastomer in high cycle fatigue is subsequently examined and the application of the linear damage accumulation hypothesis according to Palmgren-Miner for combined thermal and mechanical loads is proven. Additionally, a procedure to synthesize temperature specific S-N-curves for Natural Rubber (NR) is developed. Lastly, the results are combined into a calculation method for highly elastic couplings and used to determine the influence of location on the lifetime of couplings using the example of trams. Results of this publication are • the systematic expansion of knowledge of high cycle fatigue (>10^7 LC) as well as the proof of a bend in the S-N-curve when transitioning into continuous load range, • the proof of applicability of the linear damage accumulation hypothesis according to Palmgren-Miner for mechanical and thermal load collectives, with a very good match between calculation and experiment for Silicon (Si) and Natural rubber (NR), • the development of a functional equation for the calculation of activation energy for NR, which allows synthesizing a S-N-curve for any temperature based on an available curve as well as • the development and demonstration of a method for a realistic lifetime prediction of elastomer couplings under consideration of thermal and mechanical loads
Einfluss der Stelldynamik der Rotorblätter auf die Lasten der Blattverstellsysteme von Windenergieanlagen
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MKS-basierte Gesamtanlagenmodelle zur Lastrechnung für WEA-Getriebe
No full textIncreasing cost pressure on the wind energy sector leads to the necessity of developing more reliable wind turbines in a cost and time optimized design process. Yet, current deficiencies in the load calculation methods for the gearbox and its components still impair the cost efficiency of the gearbox design process. The before mentioned deficiencies originate especially in the disregarding of system wide dependencies and interactions of the turbines drive train components. Thus, the main objective of this contribution was to develop modelling methods that can capture the effect of said correlations onto the loads. Therefore, a MBS based entire system simulation model was developed, validated extensively with measurements und finally evaluated using internationally accepted state of the art methods. The validation was carried out using measurement results of a generic research turbine that was operated under realistic conditions on a system test bench. The results of the validation were presented and the resulting conse-quences for the modelling methods were discussed and evaluated. The concluding evaluation of the method was carried out by comparing the results to those of a design load calculations according to the IEC 61400 as well as to a model implemented according to the recommendation of the Germanischer Llyod. The benefits of the method were elaborated and evaluated in the context of the overall objective
Systematische Bewertung der Akustik von getriebelosen Windenergieanlagen am Beispiel des elektromagnetischen Betriebsverhaltens des Generators
No full textThe proportion of electrical energy producers that use regenerative energy sources will increase steadily in the course of the energy transition. Onshore wind turbines are increasingly opening up inhabited areas. In this context, the acoustic emission represents an essential metric for the distance dimensioning and localization of the wind turbines. Standards and guidelines define specifications with regard to limit values that must be observed for field measurements as part of the certification. The aim of this work is to contribute to the systematic and efficient evaluation of the noise emissions of gearless wind turbines using the example of tonal magnetic noise caused by the generator. Various methods for modeling relevant phenomena are used for this purpose. Based on a new hybrid approach to magnetic field calculation, the above effects are analyzed and evaluated using a modally reduced structural dynamics model in an elastic multi-body simulation. The electrical current forms are determined on the basis of simulations of a numerical field-circuit coupling of the generator. Measurement results, which are collected on a 4 MW system test bench, are used for model validation and experimental analysis. The structure-borne noise behavior of the generator's stator structure is evaluated using exemplary individual effects and operation with different generator characteristics. The obtained systematics represents an analysis tool for comparing wind turbine concepts and in the design process for model-based product improvement. With the approach presented, the current standards and technical guidelines with regard to acoustics can be checked and evaluated
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