The Experts below are selected from a list of 4197 Experts worldwide ranked by ideXlab platform
Peter J. Tavner - One of the best experts on this subject based on the ideXlab platform.
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wind turbine downtime and its importance for offshore deployment
Wind Energy, 2011Co-Authors: Stefan Faulstich, B Hahn, Peter J. TavnerAbstract:While the performance and the efficiency of wind turbines and their energy yields have been improved with time, their reliability still needs improvement, particularly when considering their deployment offshore. IWES has been gathering operational experience from wind turbines since 1989, being involved in different projects dealing with the topic of availability and reliability. This paper draws statistical data from Germany's ‘250 MW Wind’ programme, evaluated by IWES. The prime objective of the survey was to extract information about the reliability characteristics of wind turbines. The main purpose of this paper is to discuss the frequency of failures and duration of downtimes for different wind turbine Subassemblies based on existing onshore experience and point out the likely outcomes when turbines are deployed offshore. Copyright © 2010 John Wiley & Sons, Ltd.
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reliability availability of wind turbine electrical electronic components
Epe Journal, 2010Co-Authors: Peter J. Tavner, Stefan Faulstich, B Hahn, G J W Van BusselAbstract:AbstractRecent analysis of European onshore wind turbine reliability data has shown that whilst wind turbine mechanical Subassemblies tend to have relatively low failure rates but long downtimes, electrical and electronic Subassemblies have relatively high failure rates and short downtimes. For onshore wind turbines the higher failure rates of electrical and electronic Subassemblies can be managed by a maintenance regime that provides regular and frequent attendance to wind turbine sites. This regime will be costly or impossible to sustain in more remote onshore or offshore wind farm sites. This paper gathers data supporting the contention that electrical and electronic subassembly failure modes are a significant contributor to wind turbine unreliability, identifying some of their root causes, showing how they will play a more significant part in the availability of offshore wind turbines. The paper concludes by showing how more can be learnt to eliminate or mitigate some of these electrical and electroni...
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Reliability of wind turbine Subassemblies
IET Renewable Power Generation, 2009Co-Authors: F. Spinato, G.j.w. Van Bussel, Peter J. Tavner, E. KoutoulakosAbstract:We have investigated the reliability of more than 6000 modern onshore wind turbines and their Subassemblies in Denmark and Germany over 11 years and particularly changes in reliability of generators, gearboxes and converters in a subset of 650 turbines in Schleswig Holstein, Germany. We first start by considering the average failure rate of turbine populations and then the average failure rates of wind turbine Subassemblies. This analysis yields some surprising results about which Subassemblies are the most unreliable. Then we proceed to consider the failure intensity function variation with time for wind turbines in one of these populations, using the Power Law Process, of three Subassemblies; generator, gearbox and converter. This analysis shows that wind turbine gearboxes seem to be achieving reliabilities similar to gearboxes outside the wind industry. However, wind turbine generators and converters are both achieving reliabilities considerably below that of other industries but the reliability of these Subassemblies improves with time. The paper also considers different wind turbine concepts. Then we conclude by proposing that offshore wind turbines should be subject to more rigorous reliability improvement measures, such as more thorough subassembly testing, to eliminate early failures. The early focus should be on converters and generators.
Haruki Koyanagi - One of the best experts on this subject based on the ideXlab platform.
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integrated spatial optical system for compact 28 gb s times 4 lane transmitter optical Subassemblies
IEEE Photonics Technology Letters, 2014Co-Authors: Tadashi Murao, Nobuyuki Yasui, Takuro Shinada, Yudai Imai, Koichi Nakamura, Masaya Shimono, Hidekazu Kodera, Yoshimichi Morita, Asami Uchiyama, Haruki KoyanagiAbstract:A compact 28 Gb/s \(\times 4\) -lane transmitter optical subassembly is developed for 100Gb/s Ethernet (100 GbE)/OTU4 applications with a hybrid integrated spatial multiplexer optical system. The system simply comprises three bandpass filters and a mirror, despite the narrow guardband specification. Moreover, by an intensively improved precise lens manipulation technique acting in an upward direction in addition to horizontally and downward, high-coupled power into the single-mode output fiber can be achieved, with resolving the previously reported issue that the controllable direction was limited. Finally, we show that eye diagrams with adequate mask margins (≥15%) and high extinction ratio (≥8 dB) are obtained at 28 Gb/s with a low modulating voltage (≤1.6 V \(_{\mathrm {\mathbf {pp}}}\) ).
E. Koutoulakos - One of the best experts on this subject based on the ideXlab platform.
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Reliability of wind turbine Subassemblies
IET Renewable Power Generation, 2009Co-Authors: F. Spinato, G.j.w. Van Bussel, Peter J. Tavner, E. KoutoulakosAbstract:We have investigated the reliability of more than 6000 modern onshore wind turbines and their Subassemblies in Denmark and Germany over 11 years and particularly changes in reliability of generators, gearboxes and converters in a subset of 650 turbines in Schleswig Holstein, Germany. We first start by considering the average failure rate of turbine populations and then the average failure rates of wind turbine Subassemblies. This analysis yields some surprising results about which Subassemblies are the most unreliable. Then we proceed to consider the failure intensity function variation with time for wind turbines in one of these populations, using the Power Law Process, of three Subassemblies; generator, gearbox and converter. This analysis shows that wind turbine gearboxes seem to be achieving reliabilities similar to gearboxes outside the wind industry. However, wind turbine generators and converters are both achieving reliabilities considerably below that of other industries but the reliability of these Subassemblies improves with time. The paper also considers different wind turbine concepts. Then we conclude by proposing that offshore wind turbines should be subject to more rigorous reliability improvement measures, such as more thorough subassembly testing, to eliminate early failures. The early focus should be on converters and generators.
Faculty Of Engineering - One of the best experts on this subject based on the ideXlab platform.
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Experimental and numerical study of steel-timber composite beam-to-column connections with shear-tabs/double web-angles
University of New South Wales. Civil & Environmental Engineering, 2019Co-Authors: Civil Environmental & Engineering, Faculty Of EngineeringAbstract:Replacing concrete slabs with light-weight prefabricated timber panels reduce the embodied energy of the structures, increases speed of construction and provides opportunity for easy dismantling, recycling and reusing of the construction materials. The recent experimental and numerical studies conducted on simply support steel-timber composite (STC) beams and joints have demonstrated the feasibility, acceptable composite efficiency and structural performance of the STC systems under sagging bending moment. However, the structural behaviour of STC beam-to-column connections remains largely unexplored. Since details of connections and their stiffness and strength have major influence on structural performance and cost of steel and composite frames, this study focuses on STC beam-to-column connections with web-angles and fin-plate which are among the most popular connections in steel constructions. Sixteen cruciform Subassemblies are fabricated and tested to evaluate effect of different parameters on the stiffness, peak load carrying capacity, ductility and failure mode of nominally pinned STC connections. It is shown that preserving continuity of the timber slabs across the interior column significantly increases rotation stiffness and hogging bending moment resistance of the nominally pinned connections. Innovative methods such as spline joints with bolted steel plates and threaded rods mechanically anchored in the pocket of grout are proposed and their efficacy for preserving continuity of the timber slabs is tested. The timber slab acting compositely with steel beams also increase the rotation capacity and ductility of the connections, provided that the brittle failure of timber slab in tension and shear is prevented. Component-based approach is adopted to develop and calibrate simple models for predicting moment-rotation response of the STC connections with fin-plate and/or web-angles and the component-based models are used in conjunction with 1D finite element (FE) analysis to predict the structural response of the tested Subassemblies. Moreover, detailed nonlinear 3D continuum-based FE models of the Subassemblies are developed and verified against the experimental data. An extensive parametric study is carried out using the validated 3D FE models and nonlinear regression is employed to fit simple mathematical models to the bending moment-rotation diagrams of the STC connections obtained from the parametric study
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Assessment of beam-to-column joint behaviour in steel-timber composite systems
University of New South Wales. Civil & Environmental Engineering, 2019Co-Authors: Civil Environmental & Engineering, Faculty Of EngineeringAbstract:Reinforced concrete slabs are among the structural components with the highest levels of embodied energy and carbon. Accordingly, replacing conventional reinforced concrete slabs with timber slab can potentially reduce the embodied energy and carbon footprint and provide opportunities for effective carbon sequestration. The light-weight panelised timber slabs mechanically connected to structural frames reduce the self-weight, facilitate deconstruction, recycling and reusing of the structural members. Furthermore, lowering the self-weight of the structure leads to smaller sizes for beams and columns, and for the footings made from carbon-intensive construction materials. This study intends to investigate structural performance of the Steel-Timber Composite (STC) beam to column connections with the flush end-plate. In total, nineteen full-scale cruciform Subassemblies, including sixteen STC, two steel-concrete and one bare steel beam-to-column Subassemblies are fabricated and tested under a displacement-controlled push-down load. In addition to the laboratory experimentation, detailed nonlinear continuum-based finite element models of the tested Subassemblies are prepared and analysed. The validated finite element models are employed to conduct a parametric study and investigate effect of yield strength of flush end- plate and bolts, tensile and compressive strength of timber and level of composite action between the timber slabs and steel beams on the overall structural behaviour of the STC beam to column connections. The results of laboratory tests and finite element simulations demonstrate the vital role of slab-to-slab joints in loading capacity, stiffness and ductility of the STC beam to column connections and it is shown spline joints with bolted steel plates provide a good compromise between superior structural performance and ease of construction. It is confirmed that STC connections tend to develop complex failure modes that involve a tensile fracture, rolling shear, tear out and plug shear in timber slabs as well as yielding of steel end-plates and fasteners. The experimental results and numerical simulations show that flush end-plate STC beam to column connections have hogging bending moment and rotation capacity and ductility comparable to that of steel-concrete composite connections, however, the ductility of the STC connections with continuous timber slabs is less than the conventional steel-concrete composite system
F. Spinato - One of the best experts on this subject based on the ideXlab platform.
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Reliability of wind turbine Subassemblies
IET Renewable Power Generation, 2009Co-Authors: F. Spinato, G.j.w. Van Bussel, Peter J. Tavner, E. KoutoulakosAbstract:We have investigated the reliability of more than 6000 modern onshore wind turbines and their Subassemblies in Denmark and Germany over 11 years and particularly changes in reliability of generators, gearboxes and converters in a subset of 650 turbines in Schleswig Holstein, Germany. We first start by considering the average failure rate of turbine populations and then the average failure rates of wind turbine Subassemblies. This analysis yields some surprising results about which Subassemblies are the most unreliable. Then we proceed to consider the failure intensity function variation with time for wind turbines in one of these populations, using the Power Law Process, of three Subassemblies; generator, gearbox and converter. This analysis shows that wind turbine gearboxes seem to be achieving reliabilities similar to gearboxes outside the wind industry. However, wind turbine generators and converters are both achieving reliabilities considerably below that of other industries but the reliability of these Subassemblies improves with time. The paper also considers different wind turbine concepts. Then we conclude by proposing that offshore wind turbines should be subject to more rigorous reliability improvement measures, such as more thorough subassembly testing, to eliminate early failures. The early focus should be on converters and generators.
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condition monitoring of generators other Subassemblies in wind turbine drive trains
IEEE International Symposium on Diagnostics for Electric Machines Power Electronics and Drives, 2007Co-Authors: M R Wilkinso, F. Spinato, P J TavneAbstract:Offshore wind turbines, incorporating electrical generators and converters, operate in locations where accessibility can lead to long mean times to repair. Condition-based maintenance is therefore essential if cost-effective availability targets are to be reached. As yet the condition monitoring techniques appropriate for offshore wind turbines have not been resolved. Reliability studies have shown that the majority of failure modes in wind turbines are concentrated in drive train Subassemblies, including the electrical generator and converter, and are heavily affected by wind conditions. A 30 kW test rig has been constructed, with features similar to a wind turbine drive train, to enable the development of the signal processing techniques necessary for this variable speed, high torque variation application. The test rig includes a low speed shaft, high speed shaft, gearbox and an electrical generator and can be driven by simulated wind conditions. The test rig can also be used to inform the selection of appropriate monitoring instrumentation for offshore wind turbines. A series of condition monitoring approaches have been investigated on this test rig, using measured torque, speed, shaft displacement and gearbox vibration to detect faults. By the use of appropriate signal processing techniques, changes to load conditions, properties of the gearbox and coil faults can be detected.
