Real-time simulation of large-scale wind farms with detailed modeling can provide accurate insights into system transient behaviors,but entails challenges in computing *** paper develops a compact real-time simulator ...
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Real-time simulation of large-scale wind farms with detailed modeling can provide accurate insights into system transient behaviors,but entails challenges in computing *** paper develops a compact real-time simulator based on the field programmable gate array(FPGA)for large-scale wind farms,in which the spatial-temporal parallel design method is proposed to address the huge computation resource demand associated with detailed *** wind farm is decoupled into several subsystems based on model consistency,and the electrical system and control system of each subsystem are solved in *** the module-level pipeline technique and superscalar pipeline technique are introduced to the wind farms’simulation to effectively improve the utilization of hardware *** case studies,real-time simulations of two modified wind farms are separately carried out on a single FPGA,including one with 13 permanent magnet synchronous generators under a time-step of 11µs,and the other with 30 squirrel-cage induction generators under a time-step of 8µ*** tests,under different scenarios,are implemented to validate the numerical performance of the real-time simulator,and a comparison with the commercial tool PSCAD/EMTDC demonstrates the accuracy and effectiveness of the proposed design.
作者:
Gao, WuKavazanjian, Edward, Jr.Cardiff Univ
Sch Engn Geoenvironm Res Ctr Cardiff CF24 3AA Wales Zhejiang Univ
Dept Civil Engn MOE Key Lab Soft Soils & Geoenvironm Engn Hangzhou 310058 Peoples R China Arizona State Univ
Sch Sustainable Engn & Built Environm Ctr Biomediated & Bioinspired Geotech Tempe AZ 85287 USA
A constitutive model is developed to describe the stress-strain-time behavior for decomposing municipal solid waste (MSW) within a critical state soil mechanics framework. The model is an extension of the Modified Cam...
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A constitutive model is developed to describe the stress-strain-time behavior for decomposing municipal solid waste (MSW) within a critical state soil mechanics framework. The model is an extension of the Modified Cam-Clay plasticity model. In this model, three sources contribute to the hardening of MSW due to volumetric strain: time-independent plastic volumetric strain, time-dependent volumetric mechanical creep strain, and time-dependent volumetric strain due to the biodegradation (decomposition) of MSW. The MSW model was evaluated through numerical analyses of large-scale one-dimensional compression tests in the laboratory and the field and the reported vertical and horizontal deformations of a MSW landfill. The associated model parameters were obtained by compositional analysis of the waste, from values reported in the literature, and by fitting numerical results to observed behavior. For the laboratory compression test, the best-fit numericalsimulation over-predicted the early settlement but converged on the experimental values after 200 days. Initially, the calculated vertical strains in the field-scale test deviated from the measured strains by up to 10% over the 398-day period of the test. However, numerical results after adjusting model parameters to provide the best fit with the measured strains resulted in a maximum deviation of less than 3% over the test duration. The calculated vertical displacements of the MSW landfill were consistent with field measurements. However, the calculated horizontal displacements were significantly lower than the measured values. Sensitivity studies showed that the time-dependent settlement predicted by the model is highly sensitive to the biodegradation rate of MSW. The good agreement between numerical values and observed vertical deformations for the SWEAP section on the MSW landfill suggests that the model has the potential to assess the performance of subsystems in landfills (e.g., the performance of a side slope liner
Based on the coupling framework between OpenFAST and WEC-Sim (OWS), this study proposes a numerical model for a floating offshore wind turbine (FOWT) and wave energy converter (WEC) hybrid energy system and develops a...
Based on the coupling framework between OpenFAST and WEC-Sim (OWS), this study proposes a numerical model for a floating offshore wind turbine (FOWT) and wave energy converter (WEC) hybrid energy system and develops a multi-objective, multi-parameter configuration optimization solver to find the optimal power take-off (PTO) damping. The hybrid system consists of an IEA-15-MW reference wind turbine (RWT), a UMaine-VolturnUS-S semisubmersible platform, and three toroidal heaving WECs installed on the side columns of the platform. By introducing an artificial viscous damping coefficient tuned from the computational fluid dynamics (CFD) results, a corrected potential flow (PF) model is employed to avoid the overestimation of hydrodynamic coefficients caused by the gap resonance between the WECs and the side columns. The permanent magnet linear generators (PMLGs) for the direct-drive WECs are modelled as linear-damping PTO. Aiming at maximum wave energy extraction, the PTO damping is optimized in real sea states using the optimizer that integrates a global population-based metaheuristic scatter search algorithm and several local large-scale nonlinear programming methods. Compared with the single FOWT, the WECs provide additional power gain while positively contributing to the platform response in pitch. Moreover, the study reveals that the time difference in the relative heave motion between the platform and the WECs, determined by the environmental conditions, is a key factor that affects the overall power production of the WEC array.
A multiphase flow numerical approach for performing large-eddy simulations of three-dimensional (3D) wave-structure interaction is presented in this study. The approach combines a volume-of-fluid method to capture the...
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A multiphase flow numerical approach for performing large-eddy simulations of three-dimensional (3D) wave-structure interaction is presented in this study. The approach combines a volume-of-fluid method to capture the air-water interface and a Cartesian cut-cell method to deal with complex geometries. The filtered Navier-Stokes equations are discretised by the finite volume method with the PISO algorithm for velocity-pressure coupling and the dynamic Smagorinsky subgrid-scale model is used to compute the unresolved (subgrid) scales of turbulence. The versatility and robustness of the presented numerical approach are illustrated by applying it to solve various three-dimensional wave-structure interaction problems featuring complex geometries, such as a 3D travelling wave in a closed channel, a 3D solitary wave interacting with a vertical circular cylinder, a 3D solitary wave interacting with a horizontal thin plate, and a 3D focusing wave impacting on an FPSO-like structure. For all cases, convincing agreement between the numerical predictions and the corresponding experimental data and/or analytical or numerical solutions is obtained. In addition, for all cases, water surface profiles and turbulent vortical structures are presented and discussed. (C) 2020 The Author(s). Published by Elsevier Ltd.
Real-time simulation of large-scale active distribution networks exhibiting a wide range of time-scales puts forward higher requirements for simulation accuracy and efficiency. This paper presents an extendable method...
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Real-time simulation of large-scale active distribution networks exhibiting a wide range of time-scales puts forward higher requirements for simulation accuracy and efficiency. This paper presents an extendable method and design for the real-time simulation of active distribution networks utilising high-performance hardware field programmable gate arrays. In the aspect of numerical algorithm, a high-accuracy and stable multirate simulation algorithm is proposed. The entire active distribution network is decoupled into different subsystems by their inherent time-scales and distinct time steps are used to solve the subsystems. Then root-matching method is adopted to form the exponential difference equations that represent the behaviours of the electric distribution network being modelled, which eliminates the truncation errors and thus provides a highly accurate time-domain solution. To handle the interface between the subsystems, a multirate interfacing method is proposed. The hardware design of the multirate interfaces is presented as well. With the multirate algorithm, a fully functional extendable real-time simulator based on field programmable gate arrays is designed and implemented. Two modified IEEE 33-node systems with photovoltaics and energy storage are simulated on the 4-field-programmable-gate-arrays-based real-time simulator. simulation results are compared with the commercial simulation tool PSCAD/EMTDC to validate the correctness and effectiveness of the proposed method and design.
Power system electro-magnetic transient programs (EMTP) have been popular among researchers and practitioners due to their detailed component modeling and high simulation accuracy for complex system operations. Despit...
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Power system electro-magnetic transient programs (EMTP) have been popular among researchers and practitioners due to their detailed component modeling and high simulation accuracy for complex system operations. Despite broad applications in simulations with wide range of timescales, the small discretization step of these programs makes their use very time-consuming for system studies with long time span. Facing the increasingly complex power system transient characteristics and simulation demands, a multiscale algorithm that integrates the simulations of the electromagnetic and slower electromechanical transients is desirable. The multiscalesimulation algorithm preserves the high fidelity of the EMTP and attains higher efficiency for the overall transient simulation. In this paper, we achieve this goal by exploiting the unique properties of the matrix exponential function. The proposed algorithm is capable of utilizing large step sizes to speed up the simulation of slow dynamics, whereas the fast transients are accurately reconstructed through efficient dense output mechanism, which is built upon the matrix exponential function computation. numerical studies including a large-scale wind farm simulation are conducted to demonstrate the effectiveness of the proposed multiscale algorithm.
FSPM Plant and crop models are popular in the research community and there is increasing interest in their applications, from yield prediction to crop management optimization. A wide range of approaches and their soft...
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ISBN:
(纸本)9781509016600
FSPM Plant and crop models are popular in the research community and there is increasing interest in their applications, from yield prediction to crop management optimization. A wide range of approaches and their software implementation can be found in the literature, with a large diversity in modelling scale (from plant organ to plot levels) and scope (structural, functional or both), as well as generic or specific aim. However, most of these approaches rely on similar key assumptions and methods related to different disciplines: botany for plant structure, eco-physiology for production, statistics and dynamic system theory for parameter identification and estimation. Web disseminated plant and crop models learning supports are not numerous, often specific, and partial. We present here a set of e-learning resources, named “Plant growth architecture and production dynamics” which describes the main notions from plant morphology and architecture, eco-physiology and applied mathematics necessary to the understanding of most plant and crop models, and their typology. In this paper, after an overview of existing learning resources on plant and crop modelling which, we believe, might be of interest for the whole research community, we present the proposed resource, which uses the GreenLab model as illustration, organized as follows: Five standalone introductive disciplinary resources; botanical notions, assumptions in eco-physiology, basis in data processing, introduction to models, introduction to GreenLab : An FSPM example in more details: GreenLab positioning, its basis, structure modelling, production modelling, and applications including model fitting and a study case ; Tools: inline (for structure analysis and statistics), online (access to fitters for instance) and access to download simulators and their documentation ; Glossary, bibliography, web site collection, and a pedagogic kit for instructors Supported by the French Sustainable Development Virtual Universit
In this paper, Laplace-Beltrami equations are used to generate orthogonal curvilinear grids on the sphere for ocean models. In addition to overcoming the pole-problem, the grid configuration has quasi-uniform cell-siz...
In this paper, Laplace-Beltrami equations are used to generate orthogonal curvilinear grids on the sphere for ocean models. In addition to overcoming the pole-problem, the grid configuration has quasi-uniform cell-size on the whole sphere. Some quantities such as the grid length along two directions, the angle deviation from orthogonality, the area of the cell to evaluate the quality of the grid, which demonstrate the grid produced is fit to be a model grid on which the finite difference method or finite volume method can be implemented for numerical simulating of global atmosphere and ocean dynamics on largescale.
Floating Production, Drilling, Storage and Offloading units represent a new technology with a promising future in the offshore oil industry. An important role is played by risers, which are installed between the subse...
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Floating Production, Drilling, Storage and Offloading units represent a new technology with a promising future in the offshore oil industry. An important role is played by risers, which are installed between the subsea wellhead and the Tension Leg Deck located in the middle of the moon-pool in the hull. The inevitable heave motion of the floating hull causes a time-varying axial tension in the riser. This time dependent tension may have an undesirable influence on the lateral deflection response of the riser, with random wave forces in the frequency domain. To investigate this effect, a riser is modeled as a Bernoulli-Euler beam. The axial tension is expressed as a static part, along with a harmonic dynamic part. By linearizing the wave drag force, the riser's lateral deflection is obtained through a partial differential equation containing a time-dependent coefficient. Applying the Galerkin method, the equation is reduced to an ordinary differential equation that can be solved using the pseudo-excitation method in the frequency domain. Moreover, the Floquet-Liapunov theorem is used to estimate the stability of the vibration system in the space of parametric excitation. Finally, stability charts are obtained for some numerical examples, the correctness of the proposed method is verified by comparing with Monte-Carlo simulation and the influence of the parametric excitation on the frequency domain responses of the riser is discussed. (C) 2013 Elsevier Ltd. All rights reserved.
A large-eddy simulation study has been undertaken to investigate the turbulent structure of open-channel flow in an asymmetric compound channel. The dynamic sub-grid scale model has been employed in the model, with th...
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A large-eddy simulation study has been undertaken to investigate the turbulent structure of open-channel flow in an asymmetric compound channel. The dynamic sub-grid scale model has been employed in the model, with the partial cell treatment being implemented using a Cartesian grid structure to deal with the floodplain. The numerical model was used to predict the: primary velocity and secondary currents, boundary shear stress, turbulence intensities, turbulent kinetic energy, and Reynolds stresses. These parameters were compared with experimental measurements published in the literature, with relatively close agreement being obtained between both sets of results. Furthermore, instantaneous flow fields and large-scale vortical structures were predicted and are presented herein. These vortical structures were found to be responsible for the significant lateral exchange of mass and momentum in compound channels. Crown Copyright (C) 2012 Published by Elsevier Ltd. All rights reserved.
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