122 research outputs found
Optimized implementation of power dispatch in the OPA model and its implications for dispatch sensitivity for the WECC power network
The social and economic costs of large blackouts in power transmission networks make it critical to properly understand their dynamics. The OPA model was developed with this objective in mind and has previously been applied to power grids of small and medium size, some of them properly modeling realistic cases such as the simplified WECC network, covering the Western region of the US. The bulk of the OPA model's computational cost comes from the repeated solution of a linear programming problem using the Simplex method which is difficult to parallelize. In this paper we introduce important improvements to the modeling part of the linear problem, accelerating the previous implementation by a factor of up to 200, depending on the network. These improvements make it possible, from a practical point of view, to simulate the largest, most detailed, WECC network consisting of 19,402 nodes, reducing the wall-clock time of the simulation from two years to only 10 days. The first simulations show an interesting result: the detailed 19,402 nodes network displays a reduced sensitivity of the dynamics to the dispatch, when compared to the previously used simplified WECC models containing only 1553 and 2504 nodes.This research was sponsored by Ministerio de Economía y
Competitividad of Spain under Projects No. ENE2012-31753, ENE2012-
33219, ENE2015-68265-P and ENE2015-68265-P. Simulations have
been run in the supercomputer cluster Uranus located at Universidad
Carlos III de Madrid (Spain), funded by the Spanish Government via the
national projects UNC313-4E-2361, ENE2012-33219 and ENE2012-
31753
Fusion Plasma simulation in the Interactive Grid
Within the framework of the int.eu.grid project, IVISDEP, which stands for Interactive Visualizer of an Integrator of Stochastic Differential Equations for Plasmas, has been successfully ported and executed. It is an example of integration of many of the innovative features that this grid infrastructure offers. The application itself simulates and visualizes the evolution of the plasma inside a stellarator fusion device. The followed approach implies the simulation of a great number of trajectories of particles, whose positions are calculated among a large number of nodes in the Grid. The graphical interface allows the user to see and modify the physical and computational parameters of the simulation interactively, making this application a valuable tool for researchers in plasma physics
A positioning algorithm for SPH ghost particles in smoothly curved geometries
An algorithm to place ghost particles across the domain boundary in the context of
Smoothed Particle Hydrodynamics (SPH) is derived from basic principles, and constructed
for several simple, three-dimensional, geometries. The performance of the algorithm is
compared against the more commonly used ‘‘mirrored with respect to the local tangent
plane" approach and shown to converge to it whenever the distance of the particles to the
reflecting boundary is much smaller than a local measure of the surface’s curvature. The
algorithm is demonstrated, tested and compared against the usual approach via simulations of a compressible flow around a cylinder, and the numerical cost of implementing it
is addressed. We conclude that use of ghost particles to enforce boundary conditions is not
only viable in the presence of smoothly curved boundaries, but more robust than the usual
method for low-resolution scenarios.This research was sponsored in part by the DGICYT (Dirección General de Investigaciones Científicas y Tecnológicas)
of Spain under National Project No. ENE2015-68265. Research was also funded in part by the Erasmus Mundus Program:
International Doctoral College in Fusion Science and Engineering FUSION-DC, Spain
Obtaining statistics of cascading line outages spreading in an electric transmission network from standard utility data
We show how to use standard transmission line outage historical data to obtain the network topology in such a way that cascades of line outages can be easily located on the network. Then we obtain statistics quantifying how cascading outages typically spread on the network. Processing real outage data is fundamental for understanding cascading and for evaluating the validity of the many different models and simulations that have been proposed for cascading in power networks.This work was supported in part by NSF grant CPS-1135825. Paper no. TPWRS-01019-2015. We gratefully thank Bonneville Power Administration for making publicly available the outage data that made this paper possible. The analysis and any conclusions are strictly those of the authors and not of Bonneville Power Administratio
Fourier signature of filamentary vorticity structures in two-dimensional turbulence
It is shown that coherent regions of isotropic two-dimensional (2D) turbulence can be clearly identified in the phase part of the Fourier spectrum. Certain spectral phase events are particularly prominent, and are much stronger in the range of wave numbers corresponding to the dissipation range. It is shown that these events are associated with spatially localized filamentary structures in the 2D vorticity field that historically have been related to the intermittency of dissipation. The identified phase signature provides a particularly transparent diagnostic of the temporal evolution of the coherent coupling of disparate scales in anisostropic intermittent dissipative events. These results open the possibility of using the phase of the Fourier transform as a new turbulence diagnostic that identifies and quantitatively characterizes details pertaining to dissipative events.Research supported in part by the Spanish national
projects No. ENE2009-12213-C03-03, ENE2012-33219,
UNC313-4E-2361 and ENE2012-31753 and the US DOE
Office of Science Grants No. DE-FG02-04ER54741 and
DE-FG02-89ER53291. Simulations run at the Uranus
supercomputer cluster at Universidad Carlos III de
Madrid
Effect of vertical shoot-positioned, Scott-Henry, Geneva Double-Curtain, Arch-cane, and Parral Training Systems on the volatile composition of Albariño Wines
Viticultural practices influence both grape and wine quality. The influence of training systems on volatile composition was investigated for Albariño wine from Rías Baixas AOC in Northwest Spain. The odoriferous contribution of the compounds to the wine aroma was also studied. Volatile compounds belonging to ten groups (alcohols, C6-compounds, ethyl esters, acetates, terpenols, C13-norisoprenoids, volatile phenols, volatile fatty acids, lactones and carbonyl compounds)
were determined in Albariño wines from different training systems, Vertical Shoot-Positioned (VSP), Scott-Henry (SH), Geneva Double-Curtain (GDC), Arch-Cane (AC), and Parral (P) during 2010 and 2011 vintages. Wines from GDC showed the highest total volatile composition with the highest concentrations of alcohols, ethyl esters, fatty acids, and lactones families. However, the highest levels of terpenes and C13-norisoprenoids were quantified in the SH system. A fruitier aroma was observed in Albariño wines from GDC when odor activity values were calculated.The authors thank to Xunta de Galicia (PGIDIT06RAG018E) for the financial support and Sara Buceta, Viticulture technician in Martín Códax Winery, for technical assistance.info:eu-repo/semantics/publishedVersio
Analysis of the blackout risk reduction when segmenting large power systems using lines with controllable power flow
Large electrical transmission networks are susceptible to undergo very large blackouts due to cascading failures, with a very large associated economical cost. In this work we propose segmenting large power grids using controllable lines, such as high-voltage direct-current lines, to reduce the risk of blackouts. The method consists in modifying the power flowing through the lines interconnecting different zones during cascading failures in order to minimize the load shed. As a result, the segmented grids have a substantially lower risk of blackouts than the original network, with reductions up to 60% in some cases. The control method is shown to be specially efficient in reducing blackouts affecting more than one zone.DG and PC acknowledge funding from project PACSS RTI2018-093732-B-C22 and APASOS PID2021-122256NB-C22 of the MCIN/AEI/10.13039/501100011033/ and by EU through FEDER funds (A way to make Europe), from the Maria de Maeztu program MDM-2017-0711 of the MCIN/AEI/10.13039/501100011033/, and also from the European Union's Horizon 2020 research and innovation programme (Grant Agreement No. 957852, VPP4Islands). B.A.C. and J.M.R.-B. acknowledge access to Uranus, a supercomputer cluster located at Universidad Carlos III de Madrid (Spain) funded jointly by EU FEDER funds and by the Spanish Government via the National Research Project Nos. UNC313-4E-2361, ENE2009-12213-C03-03, ENE2012-33219, and ENE2012-31753. OGB was supported in part by FEDER/Ministerio de Ciencia, Innovacion y Universidades - Agencia Estatal de Investigación, Project RTI2018-095429-B-I00 and in part by FI-AGAUR Research Fellowship Program, Generalitat de Catalunya. The work of OGB is supported by the ICREA Academia program
Magneto-hydrodynamical nonlinear simulations of magnetically confined plasmas using smooth particle hydrodynamics (SPH)
The successful application of techniques inspired in Smoothed Particle Hydrodynamics (SPH) to magnetohydrodynamical (MHD) nonlinear simulations of magnetically confined plasmas requires the previous solution to a number of challenging issues that are still not fully resolved, namely, the construction of precise, arbitrary initial conditions in complicated geometries, the formulation of adequate boundary conditions for the magnetic field, and the correct treatment of three-dimensional toroidal boundaries of the arbitrary shape. In this paper, we present an SPH implementation of the nonlinear MHD equations that include our proposed solution to these issues and test its performance on a broad selection of nonlinear MHD problems: (1) the propagation of circularly polarized Alfven waves, (2) the occurrence of magnetic reconnection for a Harris current-sheet, and (3) the nonlinear MHD stability properties of various cylindrical pinches.This research was sponsored by DGICYT (Dirección General de Investigación Científica y Técnica) under Project No. ENE2015-68265, MINECO (Ministerio de Economía y Competitividad) under Project No. UNC313-4E-2361, and the Erasmus Mundus Program: International Doctoral College in Fusion Science and Engineering FUSION-DC
A novel efficient solver for Ampere's equation in general toroidal topologies based on singular value decomposition techniques
A new method is proposed to solve Ampere's equation in an arbitrary toroidal domain in which all currents are known, given proper boundary conditions for the magnetic vector potential. The novelty of the approach lies in the application of singular value decomposition (SVD) techniques to tackle the difficulties caused by the kernel associated by the curl operator. This kernel originates physically due to the magnetic field gauge. To increase the efficiency of the solver, the problem is represented by means of a dual finite difference-spectral scheme in arbitrary generalized toroidal coordinates, which permits to take advantage of the block structure exhibited by the matrices that describe the discretized problem. The result is a fast and efficient solver, up to three times faster than the double-curl method in some cases, that provides an accurate solution of the differential form of Ampere law while guaranteeing a zero divergence of the resulting magnetic field down to machine precision.This research has been sponsored in part by the Ministerio de Economía y Competitividad (MINECO) of Spain under
Project No. ENE2015-68265-P. Use have also been made of Uranus, a supercomputer cluster located at Universidad Carlos
III de Madrid (Spain) funded jointly by EU FEDER Project No. UNC313-4E-2361, by the Ministerio de Economía, Industria y
Competitividad (MICINN) via the National Research Project No. ENE2009-12213-C03-03 and by the Ministerio de Economía
y Competitividad (MINECO) via the National Research Project Nos. ENE2012-33219 and ENE2012-31753
The potential impact of climate change on the efficiency and reliability of solar, hydro, and wind energy sources
Climate change impacts the electric power system by affecting both the load and generation. It is paramount to understand this impact in the context of renewable energy as their market share has increased and will continue to grow. This study investigates the impact of climate change on the supply of renewable energy through applying novel metrics of intermittency, power production and storage required by the renewable energy plants as a function of historical climate data variability. Here we focus on and compare two disparate locations, Palma de Mallorca in the Balearic Islands and Cordova, Alaska. The main results of this analysis of wind, solar radiation and precipitation over the 1950–2020 period show that climate change impacts both the total supply available and its variability. Importantly, this impact is found to vary significantly with location. This analysis demonstrates the feasibility of a process to evaluate the local optimal mix of renewables, the changing needs for energy storage as well as the ability to evaluate the impact on grid reliability regarding both penetration of the increasing renewable resources and changes in the variability of the resource. This framework can be used to quantify the impact on both transmission grids and microgrids and can guide possible mitigation paths.P.C. and D.G. acknowledge financial support from Ministerio de Ciencia e Innovación (Spain), the Agencia Estatal de Investigación (AEI, Spain), and the Fondo Europeo de Desarrollo Regional (FEDER, EU) under grant PACSS (RTI2018-093732-B-C22) and the Maria de Maeztu program for Units of Excellence in R&D (MDM-2017-0711). D.N. gratefully acknowledges support from DOE Project GMLC 1.5.02—Resilient Alaskan Distribution system Improvements using Automation, Network analysis, Control, and Energy storage (RADIANCE). U.S.B. acknowledges support from the National Science Foundation under award #OIA-1753748 and by the State of Alaska for material which this work is based upon
- …