Grid generation methods

CERN Document Server

Liseikin, Vladimir D

2010-01-01

This book is an introduction to structured and unstructured grid methods in scientific computing, addressing graduate students, scientists as well as practitioners. Basic local and integral grid quality measures are formulated and new approaches to mesh generation are reviewed. In addition to the content of the successful first edition, a more detailed and practice oriented description of monitor metrics in Beltrami and diffusion equations is given for generating adaptive numerical grids. Also, new techniques developed by the author are presented, in particular a technique based on the inverted form of Beltrami’s partial differential equations with respect to control metrics. This technique allows the generation of adaptive grids for a wide variety of computational physics problems, including grid clustering to given function values and gradients, grid alignment with given vector fields, and combinations thereof. Applications of geometric methods to the analysis of numerical grid behavior as well as grid ge...

Overview of Grid Codes for Photovoltaic Integration

DEFF Research Database (Denmark)

Zheng, Qianwei; Li, Jiaming; Ai, Xiaomeng

2017-01-01

The increasing grid-connected photovoltaic (PV) power stations might threaten the safety and stability of power system. Therefore, the grid code is developed for PV power stations to ensure the security of PV integrated power systems. In this paper, requirements for PV power integration in differ......The increasing grid-connected photovoltaic (PV) power stations might threaten the safety and stability of power system. Therefore, the grid code is developed for PV power stations to ensure the security of PV integrated power systems. In this paper, requirements for PV power integration...

Grid Code Requirements for Wind Power Integration

DEFF Research Database (Denmark)

Wu, Qiuwei

2018-01-01

This chapter reviews the grid code requirements for integration of wind power plants (WPPs). The grid codes reviewed are from the UK, Ireland, Germany, Denmark, Spain, Sweden, the USA, and Canada. Transmission system operators (TSOs) around the world have specified requirements for WPPs under...

WinGridder - An interactive grid generator for TOUGH - A user's manual (Version 1.0)

International Nuclear Information System (INIS)

Pan, Lehua; Hinds, Jennifer; Haukwa, Charles; Wu, Yu-Shu; Bodvarsson, Gudmundur

2001-01-01

WinGridder is a Windows-based software package for designing, generating, and visualizing at various spatial scales numerical grids used in reservoir simulations and groundwater modeling studies. Development of this software was motivated by the requirements of the TOUGH (Transport of Unsaturated Groundwater and Heat) family of codes (Pruess 1987, 1991) for simulating subsurface processes related to high-level nuclear waste isolation in partially saturated geological media. Although the TOUGH family of codes has great flexibility in handling the variety of grid information required to describe complex objects, designing and generating a suitable irregular grid can be a tedious and error-prone process, even with the help of existing grid generating programs. This is especially true when the number of cells and connections is very large. The processes of inspecting the quality of the grid or extracting sub-grids or other specific grid information are also complex. The mesh maker embedded within TOUGH2 generates only uniform numerical grids and handles only one set of uniform fracture and matrix properties throughout the model domain. This is not suitable for grid generation in complex flow and transport simulations (such as those of Yucca Mountain, which have heterogeneity in both fracture and matrix media). As a result, the software program Amesh (Haukwa 2000) was developed to generate irregular, effective-continuum (ECM) grids

Geometrical Approach to the Grid System in the KOPEC Pilot Code

International Nuclear Information System (INIS)

Lee, E. J.; Park, C. E.; Lee, S. Y.

2008-01-01

KOPEC has been developing a pilot code to analyze two phase flow. The earlier version of the pilot code adopts the geometry with one-dimensional structured mesh system. As the pilot code is required to handle more complex geometries, a systematic geometrical approach to grid system has been introduced. Grid system can be classified as two types; structured grid system and unstructured grid system. The structured grid system is simple to apply but is less flexible than the other. The unstructured grid system is more complicated than the structured grid system. But it is more flexible to model the geometry. Therefore, two types of grid systems are utilized to allow code users simplicity as well as the flexibility

Development of NPP Safety Requirements into Kenya's Grid Codes

Energy Technology Data Exchange (ETDEWEB)

Ndirangu, Nguni James; Koo, Chang Choong [KEPCO International Nuclear Graduate School, Ulsan (Korea, Republic of)

2015-10-15

As presently drafted, Kenya's grid codes do not contain any NPP requirements. Through case studies of selected grid codes, this paper will study frequency, voltage and fault ride through requirements for NPP connection and operation, and offer recommendation of how these requirements can be incorporated in the Kenya's grid codes. Voltage and frequency excursions in Kenya's grid are notably frequently outside the generic requirement and the values observed by the German and UK grid codes. Kenya's grid codes require continuous operation for ±10% of nominal voltage and 45.0 to 52Hz on the grid which poses safety issues for an NPP. Considering stringent NPP connection to grid and operational safety requirements, and the importance of the TSO to NPP safety, more elaborate requirements need to be documented in the Kenya's grid codes. UK and Germany have a history of meeting high standards of nuclear safety and it is therefore recommended that format like the one in Table 1 to 3 should be adopted. Kenya's Grid code considering NPP should have: • Strict rules for voltage variation, that is, -5% to +10% of the nominal voltage • Strict rules for frequency variation, that is, 48Hz to 52Hz of the nominal frequencyand.

Development of NPP Safety Requirements into Kenya's Grid Codes

International Nuclear Information System (INIS)

Ndirangu, Nguni James; Koo, Chang Choong

2015-01-01

As presently drafted, Kenya's grid codes do not contain any NPP requirements. Through case studies of selected grid codes, this paper will study frequency, voltage and fault ride through requirements for NPP connection and operation, and offer recommendation of how these requirements can be incorporated in the Kenya's grid codes. Voltage and frequency excursions in Kenya's grid are notably frequently outside the generic requirement and the values observed by the German and UK grid codes. Kenya's grid codes require continuous operation for ±10% of nominal voltage and 45.0 to 52Hz on the grid which poses safety issues for an NPP. Considering stringent NPP connection to grid and operational safety requirements, and the importance of the TSO to NPP safety, more elaborate requirements need to be documented in the Kenya's grid codes. UK and Germany have a history of meeting high standards of nuclear safety and it is therefore recommended that format like the one in Table 1 to 3 should be adopted. Kenya's Grid code considering NPP should have: • Strict rules for voltage variation, that is, -5% to +10% of the nominal voltage • Strict rules for frequency variation, that is, 48Hz to 52Hz of the nominal frequencyand

SAGE - MULTIDIMENSIONAL SELF-ADAPTIVE GRID CODE

Science.gov (United States)

Davies, C. B.

1994-01-01

SAGE, Self Adaptive Grid codE, is a flexible tool for adapting and restructuring both 2D and 3D grids. Solution-adaptive grid methods are useful tools for efficient and accurate flow predictions. In supersonic and hypersonic flows, strong gradient regions such as shocks, contact discontinuities, shear layers, etc., require careful distribution of grid points to minimize grid error and produce accurate flow-field predictions. SAGE helps the user obtain more accurate solutions by intelligently redistributing (i.e. adapting) the original grid points based on an initial or interim flow-field solution. The user then computes a new solution using the adapted grid as input to the flow solver. The adaptive-grid methodology poses the problem in an algebraic, unidirectional manner for multi-dimensional adaptations. The procedure is analogous to applying tension and torsion spring forces proportional to the local flow gradient at every grid point and finding the equilibrium position of the resulting system of grid points. The multi-dimensional problem of grid adaption is split into a series of one-dimensional problems along the computational coordinate lines. The reduced one dimensional problem then requires a tridiagonal solver to find the location of grid points along a coordinate line. Multi-directional adaption is achieved by the sequential application of the method in each coordinate direction. The tension forces direct the redistribution of points to the strong gradient region. To maintain smoothness and a measure of orthogonality of grid lines, torsional forces are introduced that relate information between the family of lines adjacent to one another. The smoothness and orthogonality constraints are direction-dependent, since they relate only the coordinate lines that are being adapted to the neighboring lines that have already been adapted. Therefore the solutions are non-unique and depend on the order and direction of adaption. Non-uniqueness of the adapted grid is

GENIE - Generation of computational geometry-grids for internal-external flow configurations

Science.gov (United States)

Soni, B. K.

1988-01-01

Progress realized in the development of a master geometry-grid generation code GENIE is presented. The grid refinement process is enhanced by developing strategies to utilize bezier curves/surfaces and splines along with weighted transfinite interpolation technique and by formulating new forcing function for the elliptic solver based on the minimization of a non-orthogonality functional. A two step grid adaptation procedure is developed by optimally blending adaptive weightings with weighted transfinite interpolation technique. Examples of 2D-3D grids are provided to illustrate the success of these methods.

Network Coding Protocols for Smart Grid Communications

DEFF Research Database (Denmark)

Prior, Rui; Roetter, Daniel Enrique Lucani; Phulpin, Yannick

2014-01-01

We propose a robust network coding protocol for enhancing the reliability and speed of data gathering in smart grids. At the heart of our protocol lies the idea of tunable sparse network coding, which adopts the transmission of sparsely coded packets at the beginning of the transmission process b...

Comparison of control strategies for Doubly fed induction generator under recurring grid faults

DEFF Research Database (Denmark)

Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

2014-01-01

The new grid codes demand the wind turbine systems to ride through recurring grid faults. Many control strategies have been proposed for the Doubly Fed Induction Generator under single grid fault, but their performance under recurring grid faults have not been studied yet. In this paper, five...... different control strategies for DFIG to ride through single grid faults are presented, and their performance under recurring grid faults are analyzed. The controllable range, stator time constant and torque fluctuations of the DFIG with different control strategies are compared. The results are verified...

Suggested Grid Code Modifications to Ensure Wide-Scale Adoption of Photovoltaic Energy in Distributed Power Generation Systems

DEFF Research Database (Denmark)

Yang, Yongheng; Enjeti, Prasad; Blaabjerg, Frede

2013-01-01

Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults. However, in case of a wide-scale penetration of single......-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy...... and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for single-phase PV power systems under grid faults along with reactive power injection is studied in this paper. Three...

A gridding method for object-oriented PIC codes

International Nuclear Information System (INIS)

Gisler, G.; Peter, W.; Nash, H.; Acquah, J.; Lin, C.; Rine, D.

1993-01-01

A simple, rule-based gridding method for object-oriented PIC codes is described which is not only capable of dealing with complicated structures such as multiply-connected regions, but is also computationally faster than classical gridding techniques. Using, these smart grids, vacant cells (e.g., cells enclosed by conductors) will never have to be stored or calculated, thus avoiding the usual situation of having to zero electromagnetic fields within conductors after valuable cpu time has been spent in calculating the fields within these cells in the first place. This object-oriented gridding technique makes use of encapsulating characteristics of actual physical objects (particles, fields, grids, etc.) in C ++ classes and supporting software reuse of these entities through C ++ class inheritance relations. It has been implemented in the form of a simple two-dimensional plasma particle-in-cell code, and forms the initial effort of an AFOSR research project to develop a flexible software simulation environment for particle-in-cell algorithms based on object-oriented technology

Progress in Grid Generation: From Chimera to DRAGON Grids

Science.gov (United States)

Liou, Meng-Sing; Kao, Kai-Hsiung

1994-01-01

Hybrid grids, composed of structured and unstructured grids, combines the best features of both. The chimera method is a major stepstone toward a hybrid grid from which the present approach is evolved. The chimera grid composes a set of overlapped structured grids which are independently generated and body-fitted, yielding a high quality grid readily accessible for efficient solution schemes. The chimera method has been shown to be efficient to generate a grid about complex geometries and has been demonstrated to deliver accurate aerodynamic prediction of complex flows. While its geometrical flexibility is attractive, interpolation of data in the overlapped regions - which in today's practice in 3D is done in a nonconservative fashion, is not. In the present paper we propose a hybrid grid scheme that maximizes the advantages of the chimera scheme and adapts the strengths of the unstructured grid while at the same time keeps its weaknesses minimal. Like the chimera method, we first divide up the physical domain by a set of structured body-fitted grids which are separately generated and overlaid throughout a complex configuration. To eliminate any pure data manipulation which does not necessarily follow governing equations, we use non-structured grids only to directly replace the region of the arbitrarily overlapped grids. This new adaptation to the chimera thinking is coined the DRAGON grid. The nonstructured grid region sandwiched between the structured grids is limited in size, resulting in only a small increase in memory and computational effort. The DRAGON method has three important advantages: (1) preserving strengths of the chimera grid; (2) eliminating difficulties sometimes encountered in the chimera scheme, such as the orphan points and bad quality of interpolation stencils; and (3) making grid communication in a fully conservative and consistent manner insofar as the governing equations are concerned. To demonstrate its use, the governing equations are

Demonstration of Automatically-Generated Adjoint Code for Use in Aerodynamic Shape Optimization

Science.gov (United States)

Green, Lawrence; Carle, Alan; Fagan, Mike

1999-01-01

Gradient-based optimization requires accurate derivatives of the objective function and constraints. These gradients may have previously been obtained by manual differentiation of analysis codes, symbolic manipulators, finite-difference approximations, or existing automatic differentiation (AD) tools such as ADIFOR (Automatic Differentiation in FORTRAN). Each of these methods has certain deficiencies, particularly when applied to complex, coupled analyses with many design variables. Recently, a new AD tool called ADJIFOR (Automatic Adjoint Generation in FORTRAN), based upon ADIFOR, was developed and demonstrated. Whereas ADIFOR implements forward-mode (direct) differentiation throughout an analysis program to obtain exact derivatives via the chain rule of calculus, ADJIFOR implements the reverse-mode counterpart of the chain rule to obtain exact adjoint form derivatives from FORTRAN code. Automatically-generated adjoint versions of the widely-used CFL3D computational fluid dynamics (CFD) code and an algebraic wing grid generation code were obtained with just a few hours processing time using the ADJIFOR tool. The codes were verified for accuracy and were shown to compute the exact gradient of the wing lift-to-drag ratio, with respect to any number of shape parameters, in about the time required for 7 to 20 function evaluations. The codes have now been executed on various computers with typical memory and disk space for problems with up to 129 x 65 x 33 grid points, and for hundreds to thousands of independent variables. These adjoint codes are now used in a gradient-based aerodynamic shape optimization problem for a swept, tapered wing. For each design iteration, the optimization package constructs an approximate, linear optimization problem, based upon the current objective function, constraints, and gradient values. The optimizer subroutines are called within a design loop employing the approximate linear problem until an optimum shape is found, the design loop

Doubly fed induction generator based wind turbine systems subject to recurring grid faults

DEFF Research Database (Denmark)

Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

2014-01-01

New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the Doubly Fed Induction Generator wind turbine system under recurring grid faults is analyzed. The stator natural flux produced by the voltage recovery after the first grid fault...... may be superposed on the stator natural flux produced by the second grid fault, and it may result in large current and voltage transient. The damping of the stator natural flux can be accelerated with a rotor natural current in its opposite direction after voltage recovery, but larger torque....... The performance of DFIG under recurring grid faults is verified by the simulation and experiments....

Workshop on Future Generation Grids

CERN Document Server

Laforenza, Domenico; Reinefeld, Alexander

2006-01-01

The Internet and the Web continue to have a major impact on society. By allowing us to discover and access information on a global scale, they have created entirely new businesses and brought new meaning to the term surf. In addition, however, we want processing, and increasingly, we want collaborative processing within distributed teams. This need has led to the creation of the Grid - an infrastructure that enables us to share capabilities, and integrate services and resources within and across enterprises. "Future Generation Grids" is the second in the "CoreGRID" series. This edited volume brings together contributed articles by scientists and researchers in the Grid community in an attempt to draw a clearer picture of the future generation Grids. This book also identifies some of the most challenging problems on the way to achieving the invisible Grid ideas

Mixing in 3D Sparse Multi-Scale Grid Generated Turbulence

Science.gov (United States)

Usama, Syed; Kopec, Jacek; Tellez, Jackson; Kwiatkowski, Kamil; Redondo, Jose; Malik, Nadeem

2017-04-01

Flat 2D fractal grids are known to alter turbulence characteristics downstream of the grid as compared to the regular grids with the same blockage ratio and the same mass inflow rates [1]. This has excited interest in the turbulence community for possible exploitation for enhanced mixing and related applications. Recently, a new 3D multi-scale grid design has been proposed [2] such that each generation of length scale of turbulence grid elements is held in its own frame, the overall effect is a 3D co-planar arrangement of grid elements. This produces a 'sparse' grid system whereby each generation of grid elements produces a turbulent wake pattern that interacts with the other wake patterns downstream. A critical motivation here is that the effective blockage ratio in the 3D Sparse Grid Turbulence (3DSGT) design is significantly lower than in the flat 2D counterpart - typically the blockage ratio could be reduced from say 20% in 2D down to 4% in the 3DSGT. If this idea can be realized in practice, it could potentially greatly enhance the efficiency of turbulent mixing and transfer processes clearly having many possible applications. Work has begun on the 3DSGT experimentally using Surface Flow Image Velocimetry (SFIV) [3] at the European facility in the Max Planck Institute for Dynamics and Self-Organization located in Gottingen, Germany and also at the Technical University of Catalonia (UPC) in Spain, and numerically using Direct Numerical Simulation (DNS) at King Fahd University of Petroleum & Minerals (KFUPM) in Saudi Arabia and in University of Warsaw in Poland. DNS is the most useful method to compare the experimental results with, and we are studying different types of codes such as Imcompact3d, and OpenFoam. Many variables will eventually be investigated for optimal mixing conditions. For example, the number of scale generations, the spacing between frames, the size ratio of grid elements, inflow conditions, etc. We will report upon the first set of findings

Characterization of a Power Electronic Grid Simulator for Wind Turbine Generator Compliance Testing

DEFF Research Database (Denmark)

Glasdam, Jakob Bærholm; Gevorgian, V.; Wallen, R.

2014-01-01

This paper presents the commissioning results and testing capabilities of a multi-megawatt power electronic grid simulator situated in National Renewable Energy Laboratory’s (NREL’s) new testing facility. The commissioning is done using a commercial type 4 multi-megawatt sized wind turbine...... generator (WTG) installed in NREL’s new 5 MW dynamometer and a kilowatt sized type 1 WTG connected to the existing 2.5 MW dynamometer at NREL. The paper demonstrates the outstanding testing capability of the grid simulator and its application in the grid code compliance evaluation of WTGs including balanced...

Smart Grids and Distributed Generation

Directory of Open Access Journals (Sweden)

Dorin BICĂ

2018-06-01

Full Text Available This paper describes the main characteristics of Smart Grids and distributed generation. Smart Grids can be defined as a modernization of the power system so it monitors, protects and automatically optimizes the operation of its interconnected elements (power plants, transmission and distribution system, industrial and residential loads. Distributed generation (DG refers to the production of electricity near the consumption place using renewable energy sources. A load flow analysis is performed for the IEEE14 system in which a DG source (a 5MW wind turbine is added that is on-grid or off-grid. The power losses are determined for these two cases.

An Empirical Model for Vane-Type Vortex Generators in a Navier-Stokes Code

Science.gov (United States)

Dudek, Julianne C.

2005-01-01

An empirical model which simulates the effects of vane-type vortex generators in ducts was incorporated into the Wind-US Navier-Stokes computational fluid dynamics code. The model enables the effects of the vortex generators to be simulated without defining the details of the geometry within the grid, and makes it practical for researchers to evaluate multiple combinations of vortex generator arrangements. The model determines the strength of each vortex based on the generator geometry and the local flow conditions. Validation results are presented for flow in a straight pipe with a counter-rotating vortex generator arrangement, and the results are compared with experimental data and computational simulations using a gridded vane generator. Results are also presented for vortex generator arrays in two S-duct diffusers, along with accompanying experimental data. The effects of grid resolution and turbulence model are also examined.

Doubly Fed Induction Generator Wind Turbine Systems Subject to Recurring Symmetrical Grid Faults

DEFF Research Database (Denmark)

Chen, Wenjie; Blaabjerg, Frede; Zhu, Nan

2016-01-01

New grid codes demand the wind turbine systems to ride through recurring grid faults. In this paper, the performance of the doubly Ffed induction generator (DFIG) wind turbine system under recurring symmetrical grid faults is analyzed. The mathematical model of the DFIG under recurring symmetrical...... grid faults is established. The analysis is based on the DFIG wind turbine system with the typical low-voltage ride-through strategy-with rotor-side crowbar. The stator natural flux produced by the voltage recovery after the first grid fault may be superposed on the stator natural flux produced...... by the second grid fault, so that the transient rotor and stator current and torque fluctuations under the second grid fault may be influenced by the characteristic of the first grid fault, including the voltage dips level and the grid fault angle, as well as the duration between two faults. The mathematical...

Modeling Vortex Generators in a Navier-Stokes Code

Science.gov (United States)

Dudek, Julianne C.

2011-01-01

A source-term model that simulates the effects of vortex generators was implemented into the Wind-US Navier-Stokes code. The source term added to the Navier-Stokes equations simulates the lift force that would result from a vane-type vortex generator in the flowfield. The implementation is user-friendly, requiring the user to specify only three quantities for each desired vortex generator: the range of grid points over which the force is to be applied and the planform area and angle of incidence of the physical vane. The model behavior was evaluated for subsonic flow in a rectangular duct with a single vane vortex generator, subsonic flow in an S-duct with 22 corotating vortex generators, and supersonic flow in a rectangular duct with a counter-rotating vortex-generator pair. The model was also used to successfully simulate microramps in supersonic flow by treating each microramp as a pair of vanes with opposite angles of incidence. The validation results indicate that the source-term vortex-generator model provides a useful tool for screening vortex-generator configurations and gives comparable results to solutions computed using gridded vanes.

Network Coding Opportunities for Wireless Grids Formed by Mobile Devices

DEFF Research Database (Denmark)

Nielsen, Karsten Fyhn; Madsen, Tatiana Kozlova; Fitzek, Frank

2008-01-01

Wireless grids have potential in sharing communication, computational and storage resources making these networks more powerful, more robust, and less cost intensive. However, to enjoy the benefits of cooperative resource sharing, a number of issues should be addressed and the cost of the wireless...... link should be taken into account. We focus on the question how nodes can efficiently communicate and distribute data in a wireless grid. We show the potential of a network coding approach when nodes have the possibility to combine packets thus increasing the amount of information per transmission. Our...... implementation demonstrates the feasibility of network coding for wireless grids formed by mobile devices....

A comparative study of the parabolized Navier-Stokes code using various grid-generation techniques

Science.gov (United States)

Kaul, U. K.; Chaussee, D. S.

1985-01-01

The parabolized Navier-Stokes (PNS) equations are used to calculate the flow-field characteristics about the hypersonic research aircraft X-24C. A comparison of the results obtained using elliptic, hyperbolic and algebraic grid generators is presented. The outer bow shock is treated as a sharp discontinuity, and the discontinuities within the shock layer are captured. Surface pressures and heat-transfer results at angles of attack of 6 deg and 20 deg, obtained using the three grid generators, are compared. The PNS equations are marched downstream over the body in both Cartesian and cylindrical base coordinate systems, and the results are compared. A robust marching procedure is demonstrated by successfully using large marching-step sizes with the implicit shock fitting procedure. A correlation is found between the marching-step size, Reynolds number and the angle of attack at fixed values of smoothing and stability coefficients for the marching scheme.

Modeling and Grid Generation of Iced Airfoils

Science.gov (United States)

Vickerman, Mary B.; Baez, Marivell; Braun, Donald C.; Hackenberg, Anthony W.; Pennline, James A.; Schilling, Herbert W.

2007-01-01

SmaggIce Version 2.0 is a software toolkit for geometric modeling and grid generation for two-dimensional, singleand multi-element, clean and iced airfoils. A previous version of SmaggIce was described in Preparing and Analyzing Iced Airfoils, NASA Tech Briefs, Vol. 28, No. 8 (August 2004), page 32. To recapitulate: Ice shapes make it difficult to generate quality grids around airfoils, yet these grids are essential for predicting ice-induced complex flow. This software efficiently creates high-quality structured grids with tools that are uniquely tailored for various ice shapes. SmaggIce Version 2.0 significantly enhances the previous version primarily by adding the capability to generate grids for multi-element airfoils. This version of the software is an important step in streamlining the aeronautical analysis of ice airfoils using computational fluid dynamics (CFD) tools. The user may prepare the ice shape, define the flow domain, decompose it into blocks, generate grids, modify/divide/merge blocks, and control grid density and smoothness. All these steps may be performed efficiently even for the difficult glaze and rime ice shapes. Providing the means to generate highly controlled grids near rough ice, the software includes the creation of a wrap-around block (called the "viscous sublayer block"), which is a thin, C-type block around the wake line and iced airfoil. For multi-element airfoils, the software makes use of grids that wrap around and fill in the areas between the viscous sub-layer blocks for all elements that make up the airfoil. A scripting feature records the history of interactive steps, which can be edited and replayed later to produce other grids. Using this version of SmaggIce, ice shape handling and grid generation can become a practical engineering process, rather than a laborious research effort.

Control of Doubly-Fed Induction Generator to Ride-Through Recurring Grid Faults

DEFF Research Database (Denmark)

Chen, Wenjie; Xu, Dehong; Zhu, Nan

2016-01-01

The wind turbine system (WTS) is required to ride-through recurring grid faults by the new grid codes. Under single grid faults, the fault ride-through (FRT) strategy with rotor-side crowbar is normally used for the doubly-fed induction generator (DFIG) WTS. However, under recurring faults, larger...... transient current and voltage may be produced, and the DFIG may fail to ride-through the second fault even with the rotor-side crowbar. The crowbar can be active again during the voltage recovery, but large electromagnetic torque (EM-torque) fluctuations will be introduced. The reliability of the mechanical...... system will be influenced. In this paper, an FRT strategy for the DFIG WTS to ride-through recurring symmetrical grid faults is investigated. An improved control strategy is introduced and it is applied during the voltage recovery of the grid faults. The decay of the stator natural flux can...

Emissions & Generation Resource Integrated Database (eGRID), eGRID2012

Data.gov (United States)

U.S. Environmental Protection Agency — The Emissions emissions rates; net generation; resource mix; and many other attributes. eGRID2012 Version 1.0 is the eighth edition of eGRID, which contains the...

Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

Energy Technology Data Exchange (ETDEWEB)

Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong [Kookmin Univ., Seoul (Korea, Republic of)

2007-03-15

The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow.

Development of 3-D Flow Analysis Code for Fuel Assembly using Unstructured Grid System

International Nuclear Information System (INIS)

Myong, Hyon Kook; Kim, Jong Eun; Ahn, Jong Ki; Yang, Seung Yong

2007-03-01

The flow through a nuclear rod bundle with mixing vanes are very complex and required a suitable turbulence model to be predicted accurately. Final objective of this study is to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system. In order to develop a CFD code for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system, the following researches are made: - Development of numerical algorithm for CFD code's solver - Grid and geometric connectivity data - Development of software(PowerCFD code) for fluid flow and heat transfer analysis in a nuclear fuel assembly using unstructured grid system - Modulation of software(PowerCFD code) - Development of turbulence model - Development of analysis module of RANS/LES hybrid models - Analysis of turbulent flow and heat transfer - Basic study on LES analysis - Development of main frame on pre/post processors based on GUI - Algorithm for fully-developed flow

Schnek: A C++ library for the development of parallel simulation codes on regular grids

Science.gov (United States)

Schmitz, Holger

2018-05-01

A large number of algorithms across the field of computational physics are formulated on grids with a regular topology. We present Schnek, a library that enables fast development of parallel simulations on regular grids. Schnek contains a number of easy-to-use modules that greatly reduce the amount of administrative code for large-scale simulation codes. The library provides an interface for reading simulation setup files with a hierarchical structure. The structure of the setup file is translated into a hierarchy of simulation modules that the developer can specify. The reader parses and evaluates mathematical expressions and initialises variables or grid data. This enables developers to write modular and flexible simulation codes with minimal effort. Regular grids of arbitrary dimension are defined as well as mechanisms for defining physical domain sizes, grid staggering, and ghost cells on these grids. Ghost cells can be exchanged between neighbouring processes using MPI with a simple interface. The grid data can easily be written into HDF5 files using serial or parallel I/O.

Development of a multi-grid FDTD code for three-dimensional simulation of large microwave sintering experiments

Energy Technology Data Exchange (ETDEWEB)

White, M.J.; Iskander, M.F. [Univ. of Utah, Salt Lake City, UT (United States). Electrical Engineering Dept.; Kimrey, H.D. [Oak Ridge National Lab., TN (United States)

1996-12-31

The Finite-Difference Time-Domain (FDTD) code available at the University of Utah has been used to simulate sintering of ceramics in single and multimode cavities, and many useful results have been reported in literature. More detailed and accurate results, specifically around and including the ceramic sample, are often desired to help evaluate the adequacy of the heating procedure. In electrically large multimode cavities, however, computer memory requirements limit the number of the mathematical cells, and the desired resolution is impractical to achieve due to limited computer resources. Therefore, an FDTD algorithm which incorporates multiple-grid regions with variable-grid sizes is required to adequately perform the desired simulations. In this paper the authors describe the development of a three-dimensional multi-grid FDTD code to help focus a large number of cells around the desired region. Test geometries were solved using a uniform-grid and the developed multi-grid code to help validate the results from the developed code. Results from these comparisons, as well as the results of comparisons between the developed FDTD code and other available variable-grid codes are presented. In addition, results from the simulation of realistic microwave sintering experiments showed improved resolution in critical sites inside the three-dimensional sintering cavity. With the validation of the FDTD code, simulations were performed for electrically large, multimode, microwave sintering cavities to fully demonstrate the advantages of the developed multi-grid FDTD code.

Direct numerical simulation of turbulent mixing in grid-generated turbulence

International Nuclear Information System (INIS)

Nagata, Kouji; Suzuki, Hiroki; Sakai, Yasuhiko; Kubo, Takashi; Hayase, Toshiyuki

2008-01-01

Turbulent mixing of passive scalar (heat) in grid-generated turbulence (GGT) is simulated by means of direct numerical simulation (DNS). A turbulence-generating grid, on which the velocity components are set to zero, is located downstream of the channel entrance, and it is numerically constructed on the staggered mesh arrangement using the immersed boundary method. The grid types constructed are: (a) square-mesh biplane grid, (b) square-mesh single-plane grid, (c) composite grid consisting of parallel square-bars and (d) fractal grid. Two fluids with different temperatures are provided separately in the upper and lower streams upstream of the turbulence-generating grids, generating the thermal mixing layer behind the grids. For the grid (a), simulations for two different Prandtl numbers of 0.71 and 7.1, corresponding to air and water flows, are conducted to investigate the effect of the Prandtl number. The results show that the typical grid turbulence and shearless mixing layer are generated downstream of the grids. The results of the scalar field show that a typical thermal mixing layer is generated as well, and the effects of the Prandtl numbers on turbulent heat transfer are observed.

Direct numerical simulation of turbulent mixing in grid-generated turbulence

Energy Technology Data Exchange (ETDEWEB)

Nagata, Kouji; Suzuki, Hiroki; Sakai, Yasuhiko; Kubo, Takashi [Department of Mechanical Science and Engineering, Nagoya University, Nagoya 464-8603 (Japan); Hayase, Toshiyuki [Institute of Fluid Science, Tohoku University, Sendai 980-8577 (Japan)], E-mail: nagata@nagoya-u.jp, E-mail: hsuzuki@nagoya-u.jp, E-mail: ysakai@mech.nagoya-u.ac.jp, E-mail: t-kubo@nagoya-u.jp, E-mail: hayase@ifs.tohoku.ac.jp

2008-12-15

Turbulent mixing of passive scalar (heat) in grid-generated turbulence (GGT) is simulated by means of direct numerical simulation (DNS). A turbulence-generating grid, on which the velocity components are set to zero, is located downstream of the channel entrance, and it is numerically constructed on the staggered mesh arrangement using the immersed boundary method. The grid types constructed are: (a) square-mesh biplane grid, (b) square-mesh single-plane grid, (c) composite grid consisting of parallel square-bars and (d) fractal grid. Two fluids with different temperatures are provided separately in the upper and lower streams upstream of the turbulence-generating grids, generating the thermal mixing layer behind the grids. For the grid (a), simulations for two different Prandtl numbers of 0.71 and 7.1, corresponding to air and water flows, are conducted to investigate the effect of the Prandtl number. The results show that the typical grid turbulence and shearless mixing layer are generated downstream of the grids. The results of the scalar field show that a typical thermal mixing layer is generated as well, and the effects of the Prandtl numbers on turbulent heat transfer are observed.

Near-Body Grid Adaption for Overset Grids

Science.gov (United States)

Buning, Pieter G.; Pulliam, Thomas H.

2016-01-01

A solution adaption capability for curvilinear near-body grids has been implemented in the OVERFLOW overset grid computational fluid dynamics code. The approach follows closely that used for the Cartesian off-body grids, but inserts refined grids in the computational space of original near-body grids. Refined curvilinear grids are generated using parametric cubic interpolation, with one-sided biasing based on curvature and stretching ratio of the original grid. Sensor functions, grid marking, and solution interpolation tasks are implemented in the same fashion as for off-body grids. A goal-oriented procedure, based on largest error first, is included for controlling growth rate and maximum size of the adapted grid system. The adaption process is almost entirely parallelized using MPI, resulting in a capability suitable for viscous, moving body simulations. Two- and three-dimensional examples are presented.

Grid generation for the solution of partial differential equations

Science.gov (United States)

Eiseman, Peter R.; Erlebacher, Gordon

1989-01-01

A general survey of grid generators is presented with a concern for understanding why grids are necessary, how they are applied, and how they are generated. After an examination of the need for meshes, the overall applications setting is established with a categorization of the various connectivity patterns. This is split between structured grids and unstructured meshes. Altogether, the categorization establishes the foundation upon which grid generation techniques are developed. The two primary categories are algebraic techniques and partial differential equation techniques. These are each split into basic parts, and accordingly are individually examined in some detail. In the process, the interrelations between the various parts are accented. From the established background in the primary techniques, consideration is shifted to the topic of interactive grid generation and then to adaptive meshes. The setting for adaptivity is established with a suitable means to monitor severe solution behavior. Adaptive grids are considered first and are followed by adaptive triangular meshes. Then the consideration shifts to the temporal coupling between grid generators and PDE-solvers. To conclude, a reflection upon the discussion, herein, is given.

Overview of Recent Grid Codes for Wind Power Integration

DEFF Research Database (Denmark)

Altin, Müfit; Göksu, Ömer; Teodorescu, Remus

2010-01-01

As wind power penetration level increases, power system operators are challenged by the penetration impacts to maintain reliability and stability of power system. Therefore, grid codes are being published and continuously updated by transmission system operators of the countries. In this paper...

Grid Compatibility of Variable Speed Wind Turbines with Directly Coupled Synchronous Generator and Hydro-Dynamically Controlled Gearbox

Energy Technology Data Exchange (ETDEWEB)

Mueller, H.; Poeller, M. [DIgSILENT GmbH, 72810 Gomaringen (Germany); Basteck, A.; Tilscher, M.; Pfister, J. [Voith Turbo GmbH and Co. KG, 74564 Crailsheim (Germany)

2006-07-01

This paper analyzes grid integration aspects of a new type of variable-speed wind turbine, the directly coupled synchronous generator with hydro-dynamically controlled gearbox. In contrast to existing wind generators using synchronous generators, the generator of this concept is directly connected to the AC grid, without the application of any power electronics converter. Variable speed operation of the turbine is mechanically achieved by a gear box with continuously controllable variable gear box ratio. For this purpose, a detailed dynamic model of a 2 MW wind turbine with a Voith WinDrive has been implemented using the modelling environment of the simulation software DIgSILENT PowerFactory. For investigating grid compatibility aspects of this new wind generator concept, a model of a 50 MW wind farm, with typical layout, based on 25 wind turbines of the 2 MW-class has been analyzed. This paper focuses on the compatibility of the new concept with existing connection standards, such as the E.ON grid code. Of special interest are typical stability phenomena of synchronous generators, such as transient and oscillatory stability as well as power quality issues like voltage flicker. The results of stability studies are presented and possible advantages of the new concept with special focus on offshore applications are discussed.

Grid generation method to calculate the flow field in a three-dimensional cascade of blades. Sanjigen yokuretsu nagare keisan no tame no koshi keisei

Energy Technology Data Exchange (ETDEWEB)

Inoue, K [National Aerospace Laboratory, Tokyo (Japan)

1992-05-01

For the purpose of developing a fan for an engine with ultra-high by-pass ratio, the design code of three-dimensional cascade of blades based on the Navier-Stokes equation has already been developed. This paper describes a method created by calculation grids which are part of this design code. This method is to generate boundary fitted grids to calculate the flow field across a cascade of blades placed radially in the axially symmetric space between hub and casing. In this method, one-period domain of the cascade of blades is mapped on a box in computational space by a series of combined streching transformation and conformal mapping. The grid in physical space is then obtained by successive inverse conformal mapping on the grid points in computational space. The grid obtained in this method is H-type and has a periodicity which includes the inclination of grid lines at the periodic boundary. As an example of the grid generated by this method, grids for primary and secondary models of the fan with ultra-high by-pass ratio are shown. 6 refs., 12 figs.

Grid generation method to calculate the flow field in a three-dimensional cascade of blades; Sanjigen yokuretsu nagare keisan no tame no koshi keisei

Energy Technology Data Exchange (ETDEWEB)

Inoue, K [National Aerospace Laboratory, Tokyo (Japan)

1992-05-01

For the purpose of developing a fan for an engine with ultra-high by-pass ratio, the design code of three-dimensional cascade of blades based on the Navier-Stokes equation has already been developed. This paper describes a method created by calculation grids which are part of this design code. This method is to generate boundary fitted grids to calculate the flow field across a cascade of blades placed radially in the axially symmetric space between hub and casing. In this method, one-period domain of the cascade of blades is mapped on a box in computational space by a series of combined streching transformation and conformal mapping. The grid in physical space is then obtained by successive inverse conformal mapping on the grid points in computational space. The grid obtained in this method is H-type and has a periodicity which includes the inclination of grid lines at the periodic boundary. As an example of the grid generated by this method, grids for primary and secondary models of the fan with ultra-high by-pass ratio are shown. 6 refs., 12 figs.

Cost on Reliability and Production Loss for Power Converters in the Doubly Fed Induction Generator to Support Modern Grid Codes

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

2016-01-01

As wind farms are normally located in remote areas, many grid codes have been issued especially related to the reactive power support. Although the Doubly-Fed Induction Generator (DFIG) based power converter is able to control the active power and reactive power independently, the effects...... of providing reactive power on the lifetime of the power converter and the cost-of-energy of the whole system are seldom evaluated, even though it is an important topic. In this paper, the loss models of the DFIG system are established at various conditions of the reactive power injection. If the mission...... profile is taken into account, the lifespan of the power semiconductors as well as the cost of the reactive power can be calculated. It is concluded that an over-excited reactive power injection significantly reduces the power converter lifetime, only 1/4 of the case that there is no reactive power...

Stoplight Grid: a color-coded visual system for per diem staff assignment.

Science.gov (United States)

Ernst, P

1989-02-01

What is the best way to appropriately assign per diem nursing personnel? The author describes a systematic approach to per diem staff assignment called the Stoplight Grid. The Stoplight Grid correlates staff skills and preferences with unit needs and integrates this data into a color-coded system for staff assignment.

Modelling of Diesel Generator Sets That Assist Off-Grid Renewable Energy Micro-grids

Directory of Open Access Journals (Sweden)

Johanna Salazar

2015-08-01

Full Text Available This paper focuses on modelling diesel generators for off-grid installations based on renewable energies. Variations in Environmental Variables (for example, Solar Radiation and Wind Speed make necessary to include these auxiliary systems in off-grid renewable energy installations, in order to ensure minimal services when the produced renewable energy is not sufficient to fulfill the demand. This paper concentrates on modelling the dynamical behaviour of the diesel generator, in order to use the models and simulations for developing and testing advanced controllers for the overall off-grid system. The Diesel generator is assumed to consist of a diesel motor connected to a synchronous generator through an electromagnetic clutch, with a flywheel to damp variations. Each of the components is modelled using physical models, with the corresponding control systems also modelled: these control systems include the speed and the voltage regulation (in cascade regulation.

Distributed Generation Integration in the Electric Grid: Energy Storage System for Frequency Control

Directory of Open Access Journals (Sweden)

Maurizio Delfanti

2014-01-01

Full Text Available During the last few years generation from renewable energy sources (RESs has grown considerably in European electrical networks. Transmission system operators are greatly concerned about the impact of RESs on the operational security and efficiency of their networks and more in general of the ENTSO-E interconnected system. Grid codes are to be revised in order to harmonise the rules regarding the connection of RES power plants. A main issue concerns frequency control: frequency is greatly affected by RESs intermittency and its deviations must be limited as much as possible in order to guarantee a suitable level of power quality. To improve frequency stability, in the future, Grid codes could extend frequency control requirements also to RES units, whereas today they are applied only to conventional power plants. Energy storage systems can be a possible solution to increase the flexibility and performance of RES power plants: they allow generators to modulate their power injections without wasting renewable energy. In this paper, the authors studied the suitability of extending frequency control to RES units integrating them with energy storage systems. In particular, the paper focuses on the impact of frequency control on the storage lifetime by analysing the power charge/discharge in response to real frequency oscillations.

Code Shift: Grid Specifications and Dynamic Wind Turbine Models

DEFF Research Database (Denmark)

Ackermann, Thomas; Ellis, Abraham; Fortmann, Jens

2013-01-01

Grid codes (GCs) and dynamic wind turbine (WT) models are key tools to allow increasing renewable energy penetration without challenging security of supply. In this article, the state of the art and the further development of both tools are discussed, focusing on the European and North American e...

A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

OpenAIRE

Yoo, Cheol-Hee; Chung, Il-Yop; Yoo, Hyun-Jae; Hong, Sung-Soo

2014-01-01

Grid codes in many countries require low-voltage ride-through (LVRT) capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (P...

Application of a non-contiguous grid generation method to complex configurations

International Nuclear Information System (INIS)

Chen, S.; McIlwain, S.; Khalid, M.

2003-01-01

An economical non-contiguous grid generation method was developed to efficiently generate structured grids for complex 3D problems. Compared with traditional contiguous grids, this new approach generated grids for different block clusters independently and was able to distribute the grid points more economically according to the user's specific topology design. The method was evaluated by applying it to a Navier-Stokes computation of flow past a hypersonic projectile. Both the flow velocity and the heat transfer characteristics of the projectile agreed qualitatively with other numerical data in the literature and with available field data. Detailed grid topology designs for 3D geometries were addressed, and the advantages of this approach were analysed and compared with traditional contiguous grid generation methods. (author)

Overview of Recent Grid Codes for PV Power Integration

DEFF Research Database (Denmark)

Craciun, Bogdan-Ionut; Kerekes, Tamas; Sera, Dezso

2012-01-01

The challenge to bring down the cost of produced photovoltaic (PV) power had a major impact on the PV market and in consequence the grid operators experienced higher and higher PV power penetration. The growing share of this decentralized generation plants started to affect the grid stability...

Turbulent premixed flames on fractal-grid-generated turbulence

Energy Technology Data Exchange (ETDEWEB)

Soulopoulos, N; Kerl, J; Sponfeldner, T; Beyrau, F; Hardalupas, Y; Taylor, A M K P [Mechanical Engineering Department, Imperial College London, London SW7 2AZ (United Kingdom); Vassilicos, J C, E-mail: ns6@ic.ac.uk [Department of Aeronautics, Imperial College London, London SW7 2AZ (United Kingdom)

2013-12-15

A space-filling, low blockage fractal grid is used as a novel turbulence generator in a premixed turbulent flame stabilized by a rod. The study compares the flame behaviour with a fractal grid to the behaviour when a standard square mesh grid with the same effective mesh size and solidity as the fractal grid is used. The isothermal gas flow turbulence characteristics, including mean flow velocity and rms of velocity fluctuations and Taylor length, were evaluated from hot-wire measurements. The behaviour of the flames was assessed with direct chemiluminescence emission from the flame and high-speed OH-laser-induced fluorescence. The characteristics of the two flames are considered in terms of turbulent flame thickness, local flame curvature and turbulent flame speed. It is found that, for the same flow rate and stoichiometry and at the same distance downstream of the location of the grid, fractal-grid-generated turbulence leads to a more turbulent flame with enhanced burning rate and increased flame surface area. (paper)

Grid-Connected Inverter for Distributed Generation in Microgrid

DEFF Research Database (Denmark)

Naderipour, Amirreza; Miveh, Mohammad Reza; Guerrero, Josep M.

for power generation. DGS units can operate in parallel to the main grid or in a Microgrid (MG) mode. An MG is a discrete energy system consisting of DGSs and loads capable of operating in parallel with, or independently from, the main grid. Meanwhile, Grid-Connected Inverters (GCIs) are typically used...

Emission & Generation Resource Integrated Database (eGRID)

Data.gov (United States)

U.S. Environmental Protection Agency — The Emissions & Generation Resource Integrated Database (eGRID) is an integrated source of data on environmental characteristics of electric power generation....

Emissions & Generation Resource Integrated Database (eGRID), eGRID2010

Data.gov (United States)

U.S. Environmental Protection Agency — The Emissions emissions rates; net generation; resource mix; and many other attributes. eGRID2010 contains the complete release of year 2007 data, as well as years...

Generating Free-Form Grid Truss Structures from 3D Scanned Point Clouds

Directory of Open Access Journals (Sweden)

Hui Ding

2017-01-01

Full Text Available Reconstruction, according to physical shape, is a novel way to generate free-form grid truss structures. 3D scanning is an effective means of acquiring physical form information and it generates dense point clouds on surfaces of objects. However, generating grid truss structures from point clouds is still a challenge. Based on the advancing front technique (AFT which is widely used in Finite Element Method (FEM, a scheme for generating grid truss structures from 3D scanned point clouds is proposed in this paper. Based on the characteristics of point cloud data, the search box is adopted to reduce the search space in grid generating. A front advancing procedure suit for point clouds is established. Delaunay method and Laplacian method are used to improve the quality of the generated grids, and an adjustment strategy that locates grid nodes at appointed places is proposed. Several examples of generating grid truss structures from 3D scanned point clouds of seashells are carried out to verify the proposed scheme. Physical models of the grid truss structures generated in the examples are manufactured by 3D print, which solidifies the feasibility of the scheme.

Parallel grid generation algorithm for distributed memory computers

Science.gov (United States)

Moitra, Stuti; Moitra, Anutosh

1994-01-01

A parallel grid-generation algorithm and its implementation on the Intel iPSC/860 computer are described. The grid-generation scheme is based on an algebraic formulation of homotopic relations. Methods for utilizing the inherent parallelism of the grid-generation scheme are described, and implementation of multiple levELs of parallelism on multiple instruction multiple data machines are indicated. The algorithm is capable of providing near orthogonality and spacing control at solid boundaries while requiring minimal interprocessor communications. Results obtained on the Intel hypercube for a blended wing-body configuration are used to demonstrate the effectiveness of the algorithm. Fortran implementations bAsed on the native programming model of the iPSC/860 computer and the Express system of software tools are reported. Computational gains in execution time speed-up ratios are given.

Scaling Up Renewable Energy Generation: Aligning Targets and Incentives with Grid Integration Considerations, Greening The Grid

Energy Technology Data Exchange (ETDEWEB)

Katz, Jessica; Cochran, Jaquelin

2015-05-27

Greening the Grid provides technical assistance to energy system planners, regulators, and grid operators to overcome challenges associated with integrating variable renewable energy into the grid. This document, part of a Greening the Grid toolkit, provides power system planners with tips to help secure and sustain investment in new renewable energy generation by aligning renewable energy policy targets and incentives with grid integration considerations.

Grid Synchronization for Distributed Generations

DEFF Research Database (Denmark)

Peyghami, Saeed; Mokhtari, Hossein; Blaabjerg, Frede

2017-01-01

Distributed generators (DGs) like photovoltaic arrays, wind turbines, and fuel cell modules, as well as distributed storage (DS) units introduce some advantages to the power systems and make it more reliable, flexible, and controllable in comparison with the conventional power systems. Grid inter...

Automatic Overset Grid Generation with Heuristic Feedback Control

Science.gov (United States)

Robinson, Peter I.

2001-01-01

An advancing front grid generation system for structured Overset grids is presented which automatically modifies Overset structured surface grids and control lines until user-specified grid qualities are achieved. The system is demonstrated on two examples: the first refines a space shuttle fuselage control line until global truncation error is achieved; the second advances, from control lines, the space shuttle orbiter fuselage top and fuselage side surface grids until proper overlap is achieved. Surface grids are generated in minutes for complex geometries. The system is implemented as a heuristic feedback control (HFC) expert system which iteratively modifies the input specifications for Overset control line and surface grids. It is developed as an extension of modern control theory, production rules systems and subsumption architectures. The methodology provides benefits over the full knowledge lifecycle of an expert system for knowledge acquisition, knowledge representation, and knowledge execution. The vector/matrix framework of modern control theory systematically acquires and represents expert system knowledge. Missing matrix elements imply missing expert knowledge. The execution of the expert system knowledge is performed through symbolic execution of the matrix algebra equations of modern control theory. The dot product operation of matrix algebra is generalized for heuristic symbolic terms. Constant time execution is guaranteed.

MESH2D Grid generator design and use

Energy Technology Data Exchange (ETDEWEB)

Flach, G. P. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-10-31

Mesh2d is a Fortran90 program originally designed to generate two-dimensional structured grids of the form [x(i),y(i,j)] where [x,y] are grid coordinates identified by indices (i,j). x-coordinates depending only on index i implies strictly vertical x-grid lines, whereas the y-grid lines can undulate. Mesh2d also assigns an integer material type to each grid cell, mtyp(i,j), in a user-specified manner. The complete grid is specified through three separate input files defining the x(i), y(i,j), and mtyp(i,j) variations. Since the original development effort, Mesh2d has been extended to more general two-dimensional structured grids of the form [x(i,j),(i,j)].

Grid-connected inverter for wind power generation system

Institute of Scientific and Technical Information of China (English)

YANG Yong; RUAN Yi; SHEN Huan-qing; TANG Yan-yan; YANG Ying

2009-01-01

In wind power generation system the grid-connected inverter is an important section for energy conversion and transmission, of which the performance has a direct influence on the entire wind power generation system. The mathematical model of the grid-connected inverter is deduced firstly. Then, the space vector pulse width modulation (SVPWM) is analyzed. The power factor can be controlled close to unity, leading or lagging, which is realized based on PI-type current controller and grid voltage vector-oriented control. The control strategy is verified by the simulation and experimental results with a good sinusoidal current, a small harmonic component and a fast dynamic response.

Mapping of grid faults and grid codes

DEFF Research Database (Denmark)

Iov, F.; Hansen, Anca Daniela; Sørensen, Poul Ejnar

loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need...... challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads......The present report is a part of the research project ''Grid fault and designbasis for wind turbine'' supported by Energinet.dk through the grant PSO F&U 6319. The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme...

Examples of grid generation with implicitly specified surfaces using GridPro (TM)/az3000. 1: Filleted multi-tube configurations

Science.gov (United States)

Cheng, Zheming; Eiseman, Peter R.

1995-01-01

With examples, we illustrate how implicitly specified surfaces can be used for grid generation with GridPro/az3000. The particular examples address two questions: (1) How do you model intersecting tubes with fillets? and (2) How do you generate grids inside the intersected tubes? The implication is much more general. With the results in a forthcoming paper which develops an easy-to-follow procedure for implicit surface modeling, we provide a powerful means for rapid prototyping in grid generation.

Schwarz-Christoffel Conformal Mapping based Grid Generation for Global Oceanic Circulation Models

Science.gov (United States)

Xu, Shiming

2015-04-01

We propose new grid generation algorithms for global ocean general circulation models (OGCMs). Contrary to conventional, analytical forms based dipolar or tripolar grids, the new algorithm are based on Schwarz-Christoffel (SC) conformal mapping with prescribed boundary information. While dealing with the conventional grid design problem of pole relocation, it also addresses more advanced issues of computational efficiency and the new requirements on OGCM grids arisen from the recent trend of high-resolution and multi-scale modeling. The proposed grid generation algorithm could potentially achieve the alignment of grid lines to coastlines, enhanced spatial resolution in coastal regions, and easier computational load balance. Since the generated grids are still orthogonal curvilinear, they can be readily 10 utilized in existing Bryan-Cox-Semtner type ocean models. The proposed methodology can also be applied to the grid generation task for regional ocean modeling when complex land-ocean distribution is present.

Mapping of grid faults and grid codes

DEFF Research Database (Denmark)

Iov, Florin; Hansen, A.D.; Sørensen, P.

loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need...... challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads......The present report is a part of the research project "Grid fault and design basis for wind turbine" supported by Energinet.dk through the grant PSO F&U 6319. The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme...

Online Optimization Method for Operation of Generators in a Micro Grid

Science.gov (United States)

Hayashi, Yasuhiro; Miyamoto, Hideki; Matsuki, Junya; Iizuka, Toshio; Azuma, Hitoshi

Recently a lot of studies and developments about distributed generator such as photovoltaic generation system, wind turbine generation system and fuel cell have been performed under the background of the global environment issues and deregulation of the electricity market, and the technique of these distributed generators have progressed. Especially, micro grid which consists of several distributed generators, loads and storage battery is expected as one of the new operation system of distributed generator. However, since precipitous load fluctuation occurs in micro grid for the reason of its smaller capacity compared with conventional power system, high-accuracy load forecasting and control scheme to balance of supply and demand are needed. Namely, it is necessary to improve the precision of operation in micro grid by observing load fluctuation and correcting start-stop schedule and output of generators online. But it is not easy to determine the operation schedule of each generator in short time, because the problem to determine start-up, shut-down and output of each generator in micro grid is a mixed integer programming problem. In this paper, the authors propose an online optimization method for the optimal operation schedule of generators in micro grid. The proposed method is based on enumeration method and particle swarm optimization (PSO). In the proposed method, after picking up all unit commitment patterns of each generators satisfied with minimum up time and minimum down time constraint by using enumeration method, optimal schedule and output of generators are determined under the other operational constraints by using PSO. Numerical simulation is carried out for a micro grid model with five generators and photovoltaic generation system in order to examine the validity of the proposed method.

New challenges in grid generation and adaptivity for scientific computing

CERN Document Server

Formaggia, Luca

2015-01-01

This volume collects selected contributions from the “Fourth Tetrahedron Workshop on Grid Generation for Numerical Computations”, which was held in Verbania, Italy in July 2013. The previous editions of this Workshop were hosted by the Weierstrass Institute in Berlin (2005), by INRIA Rocquencourt in Paris (2007), and by Swansea University (2010). This book covers different, though related, aspects of the field: the generation of quality grids for complex three-dimensional geometries; parallel mesh generation algorithms; mesh adaptation, including both theoretical and implementation aspects; grid generation and adaptation on surfaces – all with an interesting mix of numerical analysis, computer science and strongly application-oriented problems.

Battery Storage Systems as Grid-Balancing Measure in Low-Voltage Distribution Grids with Distributed Generation

Directory of Open Access Journals (Sweden)

Bernhard Faessler

2017-12-01

Full Text Available Due to the promoted integration of renewable sources, a further growth of strongly transient, distributed generation is expected. Thus, the existing electrical grid may reach its physical limits. To counteract this, and to fully exploit the viable potential of renewables, grid-balancing measures are crucial. In this work, battery storage systems are embedded in a grid simulation to evaluate their potential for grid balancing. The overall setup is based on a real, low-voltage distribution grid topology, real smart meter household load profiles, and real photovoltaics load data. An autonomous optimization routine, driven by a one-way communicated incentive, determines the prospective battery operation mode. Different battery positions and incentives are compared to evaluate their impact. The configurations incorporate a baseline simulation without storage, a single, central battery storage or multiple, distributed battery storages which together have the same power and capacity. The incentives address either market conditions, grid balancing, optimal photovoltaic utilization, load shifting, or self-consumption. Simulations show that grid-balancing incentives result in lowest peak-to-average power ratios, while maintaining negligible voltage changes in comparison to a reference case. Incentives reflecting market conditions for electricity generation, such as real-time pricing, negatively influence the power quality, especially with respect to the peak-to-average power ratio. A central, feed-in-tied storage performs better in terms of minimizing the voltage drop/rise and shows lower distribution losses, while distributed storages attached at nodes with electricity generation by photovoltaics achieve lower peak-to-average power ratios.

Simulation of a flexible wind turbine response to a grid fault

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Cutululis, Nicolaos Antonio; Sørensen, Poul Ejnar

2007-01-01

The purpose of this work is to illustrate the impact of a grid fault on the mechanical loads of a wind turbine. Grid faults generate transients in the generator electromagnetic torque, which are propagated in the wind turbine, stressing its mechanical components. Grid faults are normally simulated...... in power system simulation tools applying simplified mechanical models of the drive train. This paper presents simulations of the wind turbine load response to grid faults with an advanced aeroelastic computer code (HAWC2). The core of this code is an advanced model for the flexible structure of the wind...... turbines, taking the flexibility of the tower, blades and other components of the wind turbines into account. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator....

Impact of wind power plant reactive current injection during asymmetrical grid faults

DEFF Research Database (Denmark)

Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

2013-01-01

As more renewable energy sources, especially more wind turbines (WTs) are installed in the power system; grid codes for wind power integration are being generated to sustain stable power system operation with non-synchronous generation. Common to most of the grid codes, wind power plants (WPPs...... faults, is investigated, which was not considered in the wind power impact studies before....

Parallel Implementation of the Multi-Dimensional Spectral Code SPECT3D on large 3D grids.

Science.gov (United States)

Golovkin, Igor E.; Macfarlane, Joseph J.; Woodruff, Pamela R.; Pereyra, Nicolas A.

2006-10-01

The multi-dimensional collisional-radiative, spectral analysis code SPECT3D can be used to study radiation from complex plasmas. SPECT3D can generate instantaneous and time-gated images and spectra, space-resolved and streaked spectra, which makes it a valuable tool for post-processing hydrodynamics calculations and direct comparison between simulations and experimental data. On large three dimensional grids, transporting radiation along lines of sight (LOS) requires substantial memory and CPU resources. Currently, the parallel option in SPECT3D is based on parallelization over photon frequencies and allows for a nearly linear speed-up for a variety of problems. In addition, we are introducing a new parallel mechanism that will greatly reduce memory requirements. In the new implementation, spatial domain decomposition will be utilized allowing transport along a LOS to be performed only on the mesh cells the LOS crosses. The ability to operate on a fraction of the grid is crucial for post-processing the results of large-scale three-dimensional hydrodynamics simulations. We will present a parallel implementation of the code and provide a scalability study performed on a Linux cluster.

Study of the integration of distributed generation systems in the grid: application in micro-grids

International Nuclear Information System (INIS)

Gaztanaga Arantzamendi, H.

2006-12-01

The present PhD deals with an original micro-grid concept and its application as a Renewable Energy Source's (RES) grid integration scheme. This micro-grid is composed of RES generators as well as support systems that incorporate additional functionalities in order to improve RES integration into the grid. According to this concept, two practical micro-grid applications have been studied in detail: a residential micro-grid and a wind farm supported by DFACTS systems (STATCOM and DVR). In both applications, the control structures which are implemented at different levels and applied to the different micro-grid elements have been developed, analyzed by means of off-line simulations and finally validated in real-time conditions with physical reduced-scale prototypes. (author)

Integration issues of distributed generation in distribution grids

NARCIS (Netherlands)

Coster, E.J.; Myrzik, J.M.A.; Kruimer, B.; Kling, W.L.

2011-01-01

In today’s distribution grids the number of distributed generation (DG) units is increasing rapidly. Combined heat and power (CHP) plants and wind turbines are most often installed. Integration of these DG units into the distribution grid leads to planning as well as operational challenges. Based on

Middleware for the next generation Grid infrastructure

CERN Document Server

Laure, E; Prelz, F; Beco, S; Fisher, S; Livny, M; Guy, L; Barroso, M; Buncic, P; Kunszt, Peter Z; Di Meglio, A; Aimar, A; Edlund, A; Groep, D; Pacini, F; Sgaravatto, M; Mulmo, O

2005-01-01

The aim of the EGEE (Enabling Grids for E-Science in Europe) project is to create a reliable and dependable European Grid infrastructure for e-Science. The objective of the EGEE Middleware Re-engineering and Integration Research Activity is to provide robust middleware components, deployable on several platforms and operating systems, corresponding to the core Grid services for resource access, data management, information collection, authentication & authorization, resource matchmaking and brokering, and monitoring and accounting. For achieving this objective, we developed an architecture and design of the next generation Grid middleware leveraging experiences and existing components essentially from AliEn, EDG, and VDT. The architecture follows the service breakdown developed by the LCG ARDA group. Our strategy is to do as little original development as possible but rather re-engineer and harden existing Grid services. The evolution of these middleware components towards a Service Oriented Architecture ...

Coding Model and Mapping Method of Spherical Diamond Discrete Grids Based on Icosahedron

Directory of Open Access Journals (Sweden)

LIN Bingxian

2016-12-01

Full Text Available Discrete Global Grid(DGG provides a fundamental environment for global-scale spatial data's organization and management. DGG's encoding scheme, which blocks coordinate transformation between different coordination reference frames and reduces the complexity of spatial analysis, contributes a lot to the multi-scale expression and unified modeling of spatial data. Compared with other kinds of DGGs, Diamond Discrete Global Grid(DDGG based on icosahedron is beneficial to the spherical spatial data's integration and expression for much better geometric properties. However, its structure seems more complicated than DDGG on octahedron due to its initial diamond's edges cannot fit meridian and parallel. New challenges are posed when it comes to the construction of hierarchical encoding system and mapping relationship with geographic coordinates. On this issue, this paper presents a DDGG's coding system based on the Hilbert curve and designs conversion methods between codes and geographical coordinates. The study results indicate that this encoding system based on the Hilbert curve can express space scale and location information implicitly with the similarity between DDG and planar grid put into practice, and balances efficiency and accuracy of conversion between codes and geographical coordinates in order to support global massive spatial data's modeling, integrated management and all kinds of spatial analysis.

An Evaluation of Automated Code Generation with the PetriCode Approach

DEFF Research Database (Denmark)

Simonsen, Kent Inge

2014-01-01

Automated code generation is an important element of model driven development methodologies. We have previously proposed an approach for code generation based on Coloured Petri Net models annotated with textual pragmatics for the network protocol domain. In this paper, we present and evaluate thr...... important properties of our approach: platform independence, code integratability, and code readability. The evaluation shows that our approach can generate code for a wide range of platforms which is integratable and readable....

An overset grid approach to linear wave-structure interaction

DEFF Research Database (Denmark)

Read, Robert; Bingham, Harry B.

2012-01-01

A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form. This sof......A finite-difference based approach to wave-structure interaction is reported that employs the overset approach to grid generation. A two-dimensional code that utilizes the Overture C++ library has been developed to solve the linear radiation problem for a floating body of arbitrary form...

New Boundary Constraints for Elliptic Systems used in Grid Generation Problems

Science.gov (United States)

Kaul, Upender K.; Clancy, Daniel (Technical Monitor)

2002-01-01

This paper discusses new boundary constraints for elliptic partial differential equations as used in grid generation problems in generalized curvilinear coordinate systems. These constraints, based on the principle of local conservation of thermal energy in the vicinity of the boundaries, are derived using the Green's Theorem. They uniquely determine the so called decay parameters in the source terms of these elliptic systems. These constraints' are designed for boundary clustered grids where large gradients in physical quantities need to be resolved adequately. It is observed that the present formulation also works satisfactorily for mild clustering. Therefore, a closure for the decay parameter specification for elliptic grid generation problems has been provided resulting in a fully automated elliptic grid generation technique. Thus, there is no need for a parametric study of these decay parameters since the new constraints fix them uniquely. It is also shown that for Neumann type boundary conditions, these boundary constraints uniquely determine the solution to the internal elliptic problem thus eliminating the non-uniqueness of the solution of an internal Neumann boundary value grid generation problem.

Effect of wind generation system types on Micro-Grid (MG) fault performance during both standalone and grid connected modes

International Nuclear Information System (INIS)

Kamel, Rashad M.

2014-01-01

Highlights: • This paper evaluated the effects of different wind system types on fault performance of Micro-Grid. • Both standalone and grid connected modes are considered. • The MG earthing system configuration is taken in consideration. - Abstract: Recently, there are three wind generation (WG) system types. The first type is called Fixed Speed Wind Generation (FSWG) system, which employs squirrel cage induction generators. Double Fed Induction Generator (DFIG) is utilized in the second type. The third type is called Full Converter Wind Generation (FCWG) system, which is interfaced with Micro-Grid (MG) through a back to back converter. During fault occurrence, each WG has its performance and characteristics which are determined by the generator physical characteristics and the MG earthing system configuration. For some WG types, the fault current depends also on the control algorithm of the power converter. The main target of this paper is to investigate and estimate how the fault performance of MG during both standalone and grid-connected modes is influenced by the type of WG. It is found during standalone mode that the type of the employed WG has a dominant impact on the MG performance under fault disturbance. On the contrary, the type of the employed WG has a negligible effect on the MG fault performance during grid-connected mode. This is because the main grid contributes most of the fault current. Effects of earthing system type on MG performance are highlighted

Evaluation of the efficiency and fault density of software generated by code generators

Science.gov (United States)

Schreur, Barbara

1993-01-01

Flight computers and flight software are used for GN&C (guidance, navigation, and control), engine controllers, and avionics during missions. The software development requires the generation of a considerable amount of code. The engineers who generate the code make mistakes and the generation of a large body of code with high reliability requires considerable time. Computer-aided software engineering (CASE) tools are available which generates code automatically with inputs through graphical interfaces. These tools are referred to as code generators. In theory, code generators could write highly reliable code quickly and inexpensively. The various code generators offer different levels of reliability checking. Some check only the finished product while some allow checking of individual modules and combined sets of modules as well. Considering NASA's requirement for reliability, an in house manually generated code is needed. Furthermore, automatically generated code is reputed to be as efficient as the best manually generated code when executed. In house verification is warranted.

Expected Range of Cooperation Between Transmission System Operators and Distribution System Operators After Implementation of ENTSO-E Grid Codes

Directory of Open Access Journals (Sweden)

Tomasz Pakulski

2015-06-01

Full Text Available The authors present the prospects of cooperation between transmission system operators (TSO and distribution system operators (DSO after entry into force ENTSO-E (European Network of Transmission System Operators for Electricity grid codes. New areas of DSO activities, associated with offering TSO aggregated services for national power system regulation based on the regulation resources connected to the distribution grid, and services on the distribution system level as part of the creation of local balancing areas (LBA are presented. The paper also presents the possibilities of providing ancillary services by different types of distributed generation sources in the distribution network. The LBA concept, which involves integrated management of local regulation resources including generation, demand, and energy storage is described. The options of the renewable energy sources (RES using for voltage and reactive power control in the distribution network with the use of wind farms (WF connected to the distribution system are characterized.

Impact of Rural Grid-Connected Photovoltaic Generation Systems on Power Quality

Directory of Open Access Journals (Sweden)

Rita Pinto

2016-09-01

Full Text Available Photovoltaic (PV generation systems have been increasingly used to generate electricity from renewable sources, attracting a growing interest. Recently, grid connected PV micro-generation facilities in individual homes have increased due to governmental policies as well as greater attention by industry. As low voltage (LV distribution systems were built to make energy flow in one direction, the power feed-in of PV generation in rural low-voltage grids can influence power quality (PQ as well as facility operation and reliability. This paper presents results on PQ analysis of a real PV generation facility connected to a rural low-voltage grid. Voltage fluctuations and voltage harmonic contents were observed. Statistical analysis shows a negative impact on PQ produced by this PV facility and also that only a small fraction of the energy available during a sunny day is converted, provoking losses of revenue and forcing the converter to work in an undesirable operating mode. We discuss the disturbances imposed upon the grid and their outcome regarding technical and economic viability of the PV system, as well as possible solutions. A low-voltage grid strengthening has been suggested and implemented. After that a new PQ analysis shows an improvement in the impact upon PQ, making this facility economically viable.

Radiation Coupling with the FUN3D Unstructured-Grid CFD Code

Science.gov (United States)

Wood, William A.

2012-01-01

The HARA radiation code is fully-coupled to the FUN3D unstructured-grid CFD code for the purpose of simulating high-energy hypersonic flows. The radiation energy source terms and surface heat transfer, under the tangent slab approximation, are included within the fluid dynamic ow solver. The Fire II flight test, at the Mach-31 1643-second trajectory point, is used as a demonstration case. Comparisons are made with an existing structured-grid capability, the LAURA/HARA coupling. The radiative surface heat transfer rates from the present approach match the benchmark values within 6%. Although radiation coupling is the focus of the present work, convective surface heat transfer rates are also reported, and are seen to vary depending upon the choice of mesh connectivity and FUN3D ux reconstruction algorithm. On a tetrahedral-element mesh the convective heating matches the benchmark at the stagnation point, but under-predicts by 15% on the Fire II shoulder. Conversely, on a mixed-element mesh the convective heating over-predicts at the stagnation point by 20%, but matches the benchmark away from the stagnation region.

A Survey on Next-generation Power Grid Data Architecture

Energy Technology Data Exchange (ETDEWEB)

You, Shutang [University of Tennessee, Knoxville (UTK); Zhu, Dr. Lin [University of Tennessee (UT); Liu, Yong [ORNL; Liu, Yilu [ORNL; Shankar, Mallikarjun (Arjun) [ORNL; Robertson, Russell [Grid Protection Alliance; King Jr, Thomas J [ORNL

2015-01-01

The operation and control of power grids will increasingly rely on data. A high-speed, reliable, flexible and secure data architecture is the prerequisite of the next-generation power grid. This paper summarizes the challenges in collecting and utilizing power grid data, and then provides reference data architecture for future power grids. Based on the data architecture deployment, related research on data architecture is reviewed and summarized in several categories including data measurement/actuation, data transmission, data service layer, data utilization, as well as two cross-cutting issues, interoperability and cyber security. Research gaps and future work are also presented.

Towards Product Lining Model-Driven Development Code Generators

OpenAIRE

Roth, Alexander; Rumpe, Bernhard

2015-01-01

A code generator systematically transforms compact models to detailed code. Today, code generation is regarded as an integral part of model-driven development (MDD). Despite its relevance, the development of code generators is an inherently complex task and common methodologies and architectures are lacking. Additionally, reuse and extension of existing code generators only exist on individual parts. A systematic development and reuse based on a code generator product line is still in its inf...

Virtual laboratory of electrical mini-grids with distributed generation

International Nuclear Information System (INIS)

Menezes Ramos, Vanessa; Barros Galhardo, Marcos André; Oliveira Barbosa, Claudomiro Fábio de; Tavares Pinho, João

2015-01-01

This paper presents a computing tool called Virtual Laboratory de Minirredes (Virtual Laboratory of Mini-grids). Using the virtual environment of the developed tool, it is possible to make remote connection/disconnection of switches and loads (resistive, inductive, capacitive and non-linear) at strategic points of the electric mini-grid with hybrid distributed generation systems (solar photovoltaic-diesel). The mini-grid has a length of about 1 km and is installed in the test area of the Grupo de Estudios e Desenvolvimento de Alternativas Exergética (GEDAE) of the Universidade Federal do Pará, located in the city of Belém, Pará, Brazil. The developed tool has communication functions with electric parameters transducers and programmable logic controllers (PLCs). This communication enables the opening and closing of contactors, resulting in different settings for the mini-grid. In addition to that, based on the proposed configuration by the user, the real-time operation status of mini-grid is presented in a graphic interface (for example, monitored electric parameters, distributed generators connected, status of disconnected switches, etc.) and the acquired data is stored. The use of the computing tool also focuses on the construction of a database, in order to obtain knowledge about the mini-grid performance under various conditions that can be set, depending on the operational strategy adopted, based on the choice of the layout, loads and power sources used in the mini-grid. (full text)

Distributed generation incorporated with the thermal generation for optimum operation of a smart grid considering forecast error

International Nuclear Information System (INIS)

Howlader, Harun Or Rashid; Matayoshi, Hidehito; Senjyu, Tomonobu

2015-01-01

Highlights: • Optimal operation of the thermal generation for the smart grid system. • Different distributed generations are considered as the power generation sources. • Forecast error of the renewable energy systems is considered. • Controllable loads of the smart houses are considered to achieve the optimal operation. • Economical benefits can be achieved for the smart grid system. - Abstract: This paper concentrates on the optimal operation of the conventional thermal generators with distributed generations for a smart grid considering forecast error. The distributed generations are considered as wind generators, photovoltaic generators, battery energy storage systems in the supply side and a large number of smart houses in the demand side. A smart house consists of the electric vehicle, heat pump, photovoltaic generator and solar collector. The electric vehicle and heat pump are considered as the controllable loads which can compensate the power for the forecast error of renewable energy sources. As a result, power generation cost of the smart grid can reduce through coordinated with distributed generations and thermal units scheduling process. The electric vehicles of the smart house are considered as the spinning reserve in the scheduling process which lead to lessen the additional operation of thermal units. Finally, obtained results of the proposed system have been compared with the conventional method. The conventional method does not consider the electric vehicle in the smart houses. The acquired results demonstrate that total power generation cost of the smart grid has been reduced by the proposed method considering forecast error. Effectiveness of the proposed method has been verified by the extensive simulation results using MATLAB® software

HypGrid2D. A 2-d mesh generator

Energy Technology Data Exchange (ETDEWEB)

Soerensen, N N

1998-03-01

The implementation of a hyperbolic mesh generation procedure, based on an equation for orthogonality and an equation for the cell face area is described. The method is fast, robust and gives meshes with good smoothness and orthogonality. The procedure is implemented in a program called HypGrid2D. The HypGrid2D program is capable of generating C-, O- and `H`-meshes for use in connection with the EllipSys2D Navier-Stokes solver. To illustrate the capabilities of the program, some test examples are shown. First a series of C-meshes are generated around a NACA-0012 airfoil. Secondly a series of O-meshes are generated around a NACA-65-418 airfoil. Finally `H`-meshes are generated over a Gaussian hill and a linear escarpment. (au)

Automatic code generation in practice

DEFF Research Database (Denmark)

Adam, Marian Sorin; Kuhrmann, Marco; Schultz, Ulrik Pagh

2016-01-01

-specific language to specify those requirements and to allow for generating a safety-enforcing layer of code, which is deployed to the robot. The paper at hand reports experiences in practically applying code generation to mobile robots. For two cases, we discuss how we addressed challenges, e.g., regarding weaving......Mobile robots often use a distributed architecture in which software components are deployed to heterogeneous hardware modules. Ensuring the consistency with the designed architecture is a complex task, notably if functional safety requirements have to be fulfilled. We propose to use a domain...... code generation into proprietary development environments and testing of manually written code. We find that a DSL based on the same conceptual model can be used across different kinds of hardware modules, but a significant adaptation effort is required in practical scenarios involving different kinds...

Three-Phase Grid-Connected of Photovoltaic Generator Using Nonlinear Control

DEFF Research Database (Denmark)

Yahya, A.; El Fadil, H.; Guerrero, Josep M.

2014-01-01

This paper proposes a nonlinear control methodology for three phase grid connected of PV generator. It consists of a PV arrays; a voltage source inverter, a grid filter and an electric grid. The controller objectives are threefold: i) ensuring the Maximum power point tracking (MPPT) in the side...... stability analysis and simulation results that the proposed controller meets all the objectives....

Issues and prospects in opting for new off-grid in favor to grid-integrated wind power generation systems : the case of Ethiopia

Energy Technology Data Exchange (ETDEWEB)

Wolde-Ghiorgis, W. [Addis Ababa Univ., Addis Ababa (Ethiopia). Dept. of Electrical and Computer Engineering

2008-07-01

This presentation addressed issues and prospects that help resolve constraints facing wind energy development in developing countries, with particular reference to on grid-integrated, and possibly off-grid power generation. The limitations to wind energy-development include a lack of a sizable and interconnected grids and a lack of financing. As such, even if harnessable wind energy potential is discovered at conveniently located inland sites, producing electricity would still be a challenge. This is the situation faced by less developed countries such as Ethiopia where the population and energy demands are increasing. There are also additional constraints to be addressed, recognized and resolved. This paper demonstrated that the use of clean development mechanisms (CDM) could attract support from interested industrialized countries to initiate off-grid wind power generation schemes. Off-grid wind power generation is considered to be a viable option for CDM financing. Cost comparisons and operational safety favour off-grid wind power generation. 5 refs., 3 tabs.

Mapping of grid faults and grid codes[Wind turbines

Energy Technology Data Exchange (ETDEWEB)

Iov, F. [Aalborg Univ., Inst. of Energy Technology (Denmark); Hansen, Anca D.; Soerensen, Poul; Cutululis, N.A. [Risoe National Lab. - DTU, Wind Enegy Dept., Roskilde (Denmark)

2007-06-15

The objective of this project is to investigate into the consequences of the new grid connection requirements for the fatigue and extreme loads of wind turbines. The goal is also to clarify and define possible new directions in the certification process of power plant wind turbines, namely wind turbines, which participate actively in the stabilisation of power systems. Practical experience shows that there is a need for such investigations. The grid connection requirements for wind turbines have increased significantly during the last 5-10 years. Especially the requirements for wind turbines to stay connected to the grid during and after voltage sags, imply potential challenges in the design of wind turbines. These requirements pose challenges for the design of both the electrical system and the mechanical structure of wind turbines. An overview over the frequency of grid faults and the grid connection requirements in different relevant countries is done in this report. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. The goal of this report is to present a mapping of different grid fault types and their frequency in different countries. The report provides also a detailed overview of the Low Voltage Ride-Through Capabilities for wind turbines in different relevant countries. The most relevant study cases for the quantification of the loads' impact on the wind turbines' lifetime are defined. (au)

Thermo-economic optimization of the impact of renewable generators on poly-generation smart-grids including hot thermal storage

International Nuclear Information System (INIS)

Rivarolo, M.; Greco, A.; Massardo, A.F.

2013-01-01

Highlights: ► We model a poly-generation grid including thermal storage and renewable generators. ► We analyze the impact of random renewable generators on the grid performance. ► We carry out the grid optimization using a time-dependent thermo-economic approach. ► We present the importance of the storage system to optimize the RES impact. - Abstract: In this paper, the impact of not controllable renewable energy generators (wind turbines and solar photovoltaic panels) on the thermo-economic optimum performance of poly-generation smart grids is investigated using an original time dependent hierarchical approach. The grid used for the analysis is the one installed at the University of Genoa for research activities. It is based on different prime movers: (i) 100 kWe micro gas turbine, (ii) 20 kWe internal combustion engine powered by gases to produce both electrical and thermal (hot water) energy and (iii) a 100 kWth adsorption chiller to produce cooling (cold water) energy. The grid includes thermal storage tanks to manage the thermal demand load during the year. The plant under analysis is also equipped with two renewable non-controllable generators: a small size wind turbine and photovoltaic solar panels. The size and the management of the system studied in this work have been optimized, in order to minimize both capital and variable costs. A time-dependent thermo-economic hierarchical approach developed by the authors has been used, considering the time-dependent electrical, thermal and cooling load demands during the year as problem constraints. The results are presented and discussed in depth and show the strong interaction between fossil and renewable resources, and the importance of an appropriate storage system to optimize the RES impact taking into account the multiproduct character of the grid under investigation.

Grid-code of Croatian power system

International Nuclear Information System (INIS)

Toljan, I.; Mesic, M.; Kalea, M.; Koscak, Z.

2003-01-01

Grid Rules by the Croatian Electricity Utility deal with the control and usage of the Croatian power system's transmission and distribution grid. Furthermore, these rules include obligations and permissions of power grid users and owners, with the aim of a reliable electricity supply.(author)

Current Control Method for Distributed Generation Power Generation Plants under Grid Fault Conditions

DEFF Research Database (Denmark)

Rodriguez, Pedro; Luna, Alvaro; Hermoso, Juan Ramon

2011-01-01

The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less s...

Improving nuclear generating station response for electrical grid islanding

International Nuclear Information System (INIS)

Chou, Q.B.; Kundur, P.; Acchione, P.N.; Lautsch, B.

1989-01-01

This paper describes problems associated with the performance characteristics of nuclear generating stations which do not have their overall plant control design functions co-ordinated with the other grid controls. The paper presents some design changes to typical nuclear plant controls which result in a significant improvement in both the performance of the grid island and the chances of the nuclear units staying on-line following the disturbance. This paper focuses on four areas of the overall unit controls and turbine governor controls which could be modified to better co-ordinate the control functions of the nuclear units with the electrical grid. Some simulation results are presented to show the performance of a typical electrical grid island containing a nuclear unit with and without the changes

Integrating Renewable Generation into Grid Operations: Four International Experiences

Energy Technology Data Exchange (ETDEWEB)

Weimar, Mark R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Mylrea, Michael E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Levin, Todd [Argonne National Lab. (ANL), Argonne, IL (United States); Botterud, Audun [Argonne National Lab. (ANL), Argonne, IL (United States); O' Shaughnessy, Eric [National Renewable Energy Lab. (NREL), Golden, CO (United States); Bird, Lori [National Renewable Energy Lab. (NREL), Golden, CO (United States)

2016-04-22

International experiences with power sector restructuring and the resultant impacts on bulk power grid operations and planning may provide insight into policy questions for the evolving United States power grid as resource mixes are changing in response to fuel prices, an aging generation fleet and to meet climate goals. Australia, Germany, Japan and the UK were selected to represent a range in the level and attributes of electricity industry liberalization in order to draw comparisons across a variety of regions in the United States such as California, ERCOT, the Southwest Power Pool and the Southeast Reliability Region. The study draws conclusions through a literature review of the four case study countries with regards to the changing resource mix and the electricity industry sector structure and their impact on grid operations and planning. This paper derives lessons learned and synthesizes implications for the United States based on answers to the above questions and the challenges faced by the four selected countries. Each country was examined to determine the challenges to their bulk power sector based on their changing resource mix, market structure, policies driving the changing resource mix, and policies driving restructuring. Each countries’ approach to solving those changes was examined, as well as how each country’s market structure either exacerbated or mitigated the approaches to solving the challenges to their bulk power grid operations and planning. All countries’ policies encourage renewable energy generation. One significant finding included the low- to zero-marginal cost of intermittent renewables and its potential negative impact on long-term resource adequacy. No dominant solution has emerged although a capacity market was introduced in the UK and is being contemplated in Japan. Germany has proposed the Energy Market 2.0 to encourage flexible generation investment. The grid operator in Australia proposed several approaches to maintaining

On the use of Schwarz-Christoffel conformal mappings to the grid generation for global ocean models

Science.gov (United States)

Xu, S.; Wang, B.; Liu, J.

2015-10-01

In this article we propose two grid generation methods for global ocean general circulation models. Contrary to conventional dipolar or tripolar grids, the proposed methods are based on Schwarz-Christoffel conformal mappings that map areas with user-prescribed, irregular boundaries to those with regular boundaries (i.e., disks, slits, etc.). The first method aims at improving existing dipolar grids. Compared with existing grids, the sample grid achieves a better trade-off between the enlargement of the latitudinal-longitudinal portion and the overall smooth grid cell size transition. The second method addresses more modern and advanced grid design requirements arising from high-resolution and multi-scale ocean modeling. The generated grids could potentially achieve the alignment of grid lines to the large-scale coastlines, enhanced spatial resolution in coastal regions, and easier computational load balance. Since the grids are orthogonal curvilinear, they can be easily utilized by the majority of ocean general circulation models that are based on finite difference and require grid orthogonality. The proposed grid generation algorithms can also be applied to the grid generation for regional ocean modeling where complex land-sea distribution is present.

Grid-based Parallel Data Streaming Implemented for the Gyrokinetic Toroidal Code

International Nuclear Information System (INIS)

Klasky, S.; Ethier, S.; Lin, Z.; Martins, K.; McCune, D.; Samtaney, R.

2003-01-01

We have developed a threaded parallel data streaming approach using Globus to transfer multi-terabyte simulation data from a remote supercomputer to the scientist's home analysis/visualization cluster, as the simulation executes, with negligible overhead. Data transfer experiments show that this concurrent data transfer approach is more favorable compared with writing to local disk and then transferring this data to be post-processed. The present approach is conducive to using the grid to pipeline the simulation with post-processing and visualization. We have applied this method to the Gyrokinetic Toroidal Code (GTC), a 3-dimensional particle-in-cell code used to study microturbulence in magnetic confinement fusion from first principles plasma theory

Flames in fractal grid generated turbulence

Energy Technology Data Exchange (ETDEWEB)

Goh, K H H; Hampp, F; Lindstedt, R P [Department of Mechanical Engineering, Imperial College, London SW7 2AZ (United Kingdom); Geipel, P, E-mail: p.lindstedt@imperial.ac.uk [Siemens Industrial Turbomachinery AB, SE-612 83 Finspong (Sweden)

2013-12-15

Twin premixed turbulent opposed jet flames were stabilized for lean mixtures of air with methane and propane in fractal grid generated turbulence. A density segregation method was applied alongside particle image velocimetry to obtain velocity and scalar statistics. It is shown that the current fractal grids increase the turbulence levels by around a factor of 2. Proper orthogonal decomposition (POD) was applied to show that the fractal grids produce slightly larger turbulent structures that decay at a slower rate as compared to conventional perforated plates. Conditional POD (CPOD) was also implemented using the density segregation technique and the results show that CPOD is essential to segregate the relative structures and turbulent kinetic energy distributions in each stream. The Kolmogorov length scales were also estimated providing values {approx}0.1 and {approx}0.5 mm in the reactants and products, respectively. Resolved profiles of flame surface density indicate that a thin flame assumption leading to bimodal statistics is not perfectly valid under the current conditions and it is expected that the data obtained will be of significant value to the development of computational methods that can provide information on the conditional structure of turbulence. It is concluded that the increase in the turbulent Reynolds number is without any negative impact on other parameters and that fractal grids provide a route towards removing the classical problem of a relatively low ratio of turbulent to bulk strain associated with the opposed jet configuration. (paper)

Research on a New Control Scheme of Photovoltaic Grid Power Generation System

Directory of Open Access Journals (Sweden)

Dong-Hui Li

2014-01-01

Full Text Available A new type of photovoltaic grid power generation system control scheme to solve the problems of the conventional photovoltaic grid power generation systems is presented. To aim at the oscillation and misjudgment of traditional perturbation observation method, an improved perturbation observation method comparing to the next moment power is proposed, combining with BOOST step-up circuit to realize the maximum power tracking. To counter the harmonic pollution problem in photovoltaic grid power generation system, the deadbeat control scheme in fundamental wave synchronous frequency rotating coordinate system of power grid is presented. A parameter optimization scheme based on positive feedback of active frequency shift island detection to solve the problems like the nondetection zone due to the import of disturbance in traditional island detection method is proposed. Finally, the results in simulation environment by MATLAB/Simulink simulation and experiment environment verify the validity and superiority of the proposed scheme.

A Grid Voltage Measurement Method for Wind Power Systems during Grid Fault Conditions

Directory of Open Access Journals (Sweden)

Cheol-Hee Yoo

2014-11-01

Full Text Available Grid codes in many countries require low-voltage ride-through (LVRT capability to maintain power system stability and reliability during grid fault conditions. To meet the LVRT requirement, wind power systems must stay connected to the grid and also supply reactive currents to the grid to support the recovery from fault voltages. This paper presents a new fault detection method and inverter control scheme to improve the LVRT capability for full-scale permanent magnet synchronous generator (PMSG wind power systems. Fast fault detection can help the wind power systems maintain the DC-link voltage in a safe region. The proposed fault detection method is based on on-line adaptive parameter estimation. The performance of the proposed method is verified in comparison to the conventional voltage measurement method defined in the IEC 61400-21 standard.

Emissions & Generation Resource Integrated Database (eGRID), eGRID2002 (with years 1996 - 2000 data)

Data.gov (United States)

U.S. Environmental Protection Agency — The Emissions emissions rates; net generation; resource mix; and many other attributes. eGRID2002 (years 1996 through 2000 data) contains 16 Excel spreadsheets and...

Self-organizing hybrid Cartesian grid generation and application to external and internal flow problems

Energy Technology Data Exchange (ETDEWEB)

Deister, F.; Hirschel, E.H. [Univ. Stuttgart, IAG, Stuttgart (Germany); Waymel, F.; Monnoyer, F. [Univ. de Valenciennes, LME, Valenciennes (France)

2003-07-01

An automatic adaptive hybrid Cartesian grid generation and simulation system is presented together with applications. The primary computational grid is an octree Cartesian grid. A quasi-prismatic grid may be added for resolving the boundary layer region of viscous flow around the solid body. For external flow simulations the flow solver TAU from the ''deutsche zentrum fuer luft- und raumfahrt (DLR)'' is integrated in the simulation system. Coarse grids are generated automatically, which are required by the multilevel method. As an application to an internal problem the thermal and dynamic modeling of a subway station is presented. (orig.)

A two-dimensional adaptive numerical grids generation method and its realization

International Nuclear Information System (INIS)

Xu Tao; Shui Hongshou

1998-12-01

A two-dimensional adaptive numerical grids generation method and its particular realization is discussed. This method is effective and easy to realize if the control functions are given continuously, and the grids for some regions is showed in this case. For Computational Fluid Dynamics, because the control values of adaptive grids-numerical solution is given in dispersed form, it is needed to interpolate these values to get the continuous control functions. These interpolation techniques are discussed, and some efficient adaptive grids are given. A two-dimensional fluid dynamics example was also given

mGrid: A load-balanced distributed computing environment for the remote execution of the user-defined Matlab code

Directory of Open Access Journals (Sweden)

Almeida Jonas S

2006-03-01

Full Text Available Abstract Background Matlab, a powerful and productive language that allows for rapid prototyping, modeling and simulation, is widely used in computational biology. Modeling and simulation of large biological systems often require more computational resources then are available on a single computer. Existing distributed computing environments like the Distributed Computing Toolbox, MatlabMPI, Matlab*G and others allow for the remote (and possibly parallel execution of Matlab commands with varying support for features like an easy-to-use application programming interface, load-balanced utilization of resources, extensibility over the wide area network, and minimal system administration skill requirements. However, all of these environments require some level of access to participating machines to manually distribute the user-defined libraries that the remote call may invoke. Results mGrid augments the usual process distribution seen in other similar distributed systems by adding facilities for user code distribution. mGrid's client-side interface is an easy-to-use native Matlab toolbox that transparently executes user-defined code on remote machines (i.e. the user is unaware that the code is executing somewhere else. Run-time variables are automatically packed and distributed with the user-defined code and automated load-balancing of remote resources enables smooth concurrent execution. mGrid is an open source environment. Apart from the programming language itself, all other components are also open source, freely available tools: light-weight PHP scripts and the Apache web server. Conclusion Transparent, load-balanced distribution of user-defined Matlab toolboxes and rapid prototyping of many simple parallel applications can now be done with a single easy-to-use Matlab command. Because mGrid utilizes only Matlab, light-weight PHP scripts and the Apache web server, installation and configuration are very simple. Moreover, the web

mGrid: a load-balanced distributed computing environment for the remote execution of the user-defined Matlab code.

Science.gov (United States)

Karpievitch, Yuliya V; Almeida, Jonas S

2006-03-15

Matlab, a powerful and productive language that allows for rapid prototyping, modeling and simulation, is widely used in computational biology. Modeling and simulation of large biological systems often require more computational resources then are available on a single computer. Existing distributed computing environments like the Distributed Computing Toolbox, MatlabMPI, Matlab*G and others allow for the remote (and possibly parallel) execution of Matlab commands with varying support for features like an easy-to-use application programming interface, load-balanced utilization of resources, extensibility over the wide area network, and minimal system administration skill requirements. However, all of these environments require some level of access to participating machines to manually distribute the user-defined libraries that the remote call may invoke. mGrid augments the usual process distribution seen in other similar distributed systems by adding facilities for user code distribution. mGrid's client-side interface is an easy-to-use native Matlab toolbox that transparently executes user-defined code on remote machines (i.e. the user is unaware that the code is executing somewhere else). Run-time variables are automatically packed and distributed with the user-defined code and automated load-balancing of remote resources enables smooth concurrent execution. mGrid is an open source environment. Apart from the programming language itself, all other components are also open source, freely available tools: light-weight PHP scripts and the Apache web server. Transparent, load-balanced distribution of user-defined Matlab toolboxes and rapid prototyping of many simple parallel applications can now be done with a single easy-to-use Matlab command. Because mGrid utilizes only Matlab, light-weight PHP scripts and the Apache web server, installation and configuration are very simple. Moreover, the web-based infrastructure of mGrid allows for it to be easily extensible over

FCG: a code generator for lazy functional languages

NARCIS (Netherlands)

Kastens, U.; Langendoen, K.G.; Hartel, Pieter H.; Pfahler, P.

1992-01-01

The FCGcode generator produces portable code that supports efficient two-space copying garbage collection. The code generator transforms the output of the FAST compiler front end into an abstract machine code. This code explicitly uses a call stack, which is accessible to the garbage collector. In

Use of thermoelectric generators for improve power dependability over grid power

Energy Technology Data Exchange (ETDEWEB)

Archer, Jack [Global Thermoelectric, Calgary (Canada)

2005-07-01

A natural gas transportation company was experiencing extensive pipeline corrosion on some sections of their pipeline protected by impressed current using grid power and rectifiers. After determining that grid power was being interrupted on the affected sections, the gas transporter began looking for a more dependable power supply and chose thermoelectric generators. Since installing thermoelectric generators in 2002, the pipeline potentials have stabilized and transporter was able to experience 100% operational time on affected sections. (author)

ASP - Grid connections of large power generating units; ASP - Anslutning av stoerre produktionsanlaeggningar till elnaetet

Energy Technology Data Exchange (ETDEWEB)

Larsson, Aake; Larsson, Richard [Vattenfall Power Consultants, Stockholm (Sweden)

2006-12-15

Grid connections of large power generating units normally require more detailed studies compared to small single units. The required R and D-level depends on the specific characteristics of the production units and the connecting grid. An inquiry for a grid connection will raise questions for the grid owner regarding transmission capability, losses, fault currents, relay protection, dynamic stability etc. Then only a few larger wind farms have been built, the experiences from these types of grid connections are limited and for that reason it can be difficult to identify issues appropriate for further studies. To ensure that electric power generating units do not have unacceptable impact on the grid, directions from the Swedish TSO (Svenska Kraftnaet) have been stated. The directions deal, for example, with power generation in specific ranges of voltage level and frequency and the possibility to remain connected to the grid when different faults occur. The requirements and the consequences of these directions are illustrated. There are three main issues that should be considered: Influence on the power flow from generating units regarding voltage level, currents, losses etc.; Different types of electric systems in generating units contribute to different levels of fault currents. For that reason the resulting fault current levels have to be studied; It is required that generating units should remain connected to the grid at different modes of operation and faults. These modes have to be verified. Load flow and dynamic studies normally demand computer models. Comprehensive models, for instance of wind farms, can bee difficult to design and normally large computer capacity is required. Therefore simplified methods to perform relevant studies are described. How to model an electric power generating unit regarding fault currents and dynamic stability is described. An inquiry for a grid connection normally brings about a discussion concerning administration. To make it

A brief overview of the distribution test grids with a distributed generation inclusion case study

Directory of Open Access Journals (Sweden)

Stanisavljević Aleksandar M.

2018-01-01

Full Text Available The paper presents an overview of the electric distribution test grids issued by different technical institutions. They are used for testing different scenarios in operation of a grid for research, benchmarking, comparison and other purposes. Their types, main characteristics, features as well as application possibilities are shown. Recently, these grids are modified with inclusion of distributed generation. An example of modification and application of the IEEE 13-bus for testing effects of faults in cases without and with a distributed generator connection to the grid is presented. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. III 042004: Smart Electricity Distribution Grids Based on Distribution Management System and Distributed Generation

Efficient identification of opportunities for Distributed Generation based on Smart Grid Technology

DEFF Research Database (Denmark)

Mutule, Anna; Obushevs, Artjoms; Lvov, Aleksandr

2013-01-01

The paper presents the main goals and achievements of the Smart Grids ERA-NET project named “Efficient identification of opportunities for Distributed Generation based on Smart Grid Technology (SmartGen)” during the second stage of project implementation. A description of Smart Grid Technology (S......) models developed within the framework of the project is given. The performed study cases where the SGT-models were implemented to analyze the impact of the electrical grid are discussed....

New GOES satellite synchronized time code generation

Science.gov (United States)

Fossler, D. E.; Olson, R. K.

1984-01-01

The TRAK Systems' GOES Satellite Synchronized Time Code Generator is described. TRAK Systems has developed this timing instrument to supply improved accuracy over most existing GOES receiver clocks. A classical time code generator is integrated with a GOES receiver.

Simulation of off-grid generation options for remote villages in Cameroon

International Nuclear Information System (INIS)

Nfah, E.M.; Ngundam, J.M.; Vandenbergh, M.; Schmid, J.

2008-01-01

Off-grid generation options have been simulated for remote villages in Cameroon using a load of 110 kWh/day and 12 kWp. The energy costs of proposed options were simulated using HOMER, a typical village load profile, the solar resource of Garoua and the flow of river Mungo. For a 40% increase in the cost of imported power system components, the cost of energy was found to be 0.296 EUR/kWh for a micro-hydro hybrid system comprising a 14 kW micro-hydro generator, a 15 kW LPG generator and 36 kWh of battery storage. The cost of energy for photovoltaic (PV) hybrid systems made up of an 18 kWp PV generator, a 15 kW LPG generator and 72 kWh of battery storage was also found to be 0.576 EUR/kWh for remote petrol price of 1 EUR/l and LPG price of 0.70 EUR/m 3 . The micro-hydro hybrid system proved to be the cheapest option for villages located in the southern parts of Cameroon with a flow rate of at least 200l/s, while the PV hybrid system was the cheapest option for villages in the northern parts of Cameroon with an insolation level of at least 5.55 kWh/m 2 /day. For a single-wire grid extension cost of 5000 EUR/km, operation and maintenance costs of 125 EUR/yr/km and a local grid power price of 0.1 EUR/kWh, the breakeven grid extension distances were found to be 15.4 km for micro-hydro/LPG generator systems and 37.4 km for PV/LPG generator systems respectively. These results could be used in Cameroon's National Energy Action Plan for the provision of energy services in the key sectors involved in the fight against poverty. (author)

The research on multi-projection correction based on color coding grid array

Science.gov (United States)

Yang, Fan; Han, Cheng; Bai, Baoxing; Zhang, Chao; Zhao, Yunxiu

2017-10-01

There are many disadvantages such as lower timeliness, greater manual intervention in multi-channel projection system, in order to solve the above problems, this paper proposes a multi-projector correction technology based on color coding grid array. Firstly, a color structured light stripe is generated by using the De Bruijn sequences, then meshing the feature information of the color structured light stripe image. We put the meshing colored grid intersection as the center of the circle, and build a white solid circle as the feature sample set of projected images. It makes the constructed feature sample set not only has the perceptual localization, but also has good noise immunity. Secondly, we establish the subpixel geometric mapping relationship between the projection screen and the individual projectors by using the structure of light encoding and decoding based on the color array, and the geometrical mapping relation is used to solve the homography matrix of each projector. Lastly the brightness inconsistency of the multi-channel projection overlap area is seriously interfered, it leads to the corrected image doesn't fit well with the observer's visual needs, and we obtain the projection display image of visual consistency by using the luminance fusion correction algorithm. The experimental results show that this method not only effectively solved the problem of distortion of multi-projection screen and the issue of luminance interference in overlapping region, but also improved the calibration efficient of multi-channel projective system and reduced the maintenance cost of intelligent multi-projection system.

Research on Primary Shielding Calculation Source Generation Codes

Science.gov (United States)

Zheng, Zheng; Mei, Qiliang; Li, Hui; Shangguan, Danhua; Zhang, Guangchun

2017-09-01

Primary Shielding Calculation (PSC) plays an important role in reactor shielding design and analysis. In order to facilitate PSC, a source generation code is developed to generate cumulative distribution functions (CDF) for the source particle sample code of the J Monte Carlo Transport (JMCT) code, and a source particle sample code is deveoped to sample source particle directions, types, coordinates, energy and weights from the CDFs. A source generation code is developed to transform three dimensional (3D) power distributions in xyz geometry to source distributions in r θ z geometry for the J Discrete Ordinate Transport (JSNT) code. Validation on PSC model of Qinshan No.1 nuclear power plant (NPP), CAP1400 and CAP1700 reactors are performed. Numerical results show that the theoretical model and the codes are both correct.

Online Detection and Estimation of Grid Impedance Variation for Distributed Power Generation

DEFF Research Database (Denmark)

Jebali-Ben Ghorbal, Manel; Ghzaiel, Walid; Slama-Belkhodja, Ilhem

2012-01-01

A better knowledge of the grid impedance is essential in order to improve power quality and control of the Distributed Power Generation Systems (DPGS) and also for a safe connection or reconnection to the utility grid. An LCL-filter associated to a Voltage Source Inverter (VSI) is usually used...... to disconnect the DPG systems of the network. This work presents a rapid and simple technique to detect the grid impedance variation and to determine the grid impedance before and after grid faults accurs. Implementation on FPGA control board, simulations and experimental results are presented to validate...

PetriCode: A Tool for Template-Based Code Generation from CPN Models

DEFF Research Database (Denmark)

Simonsen, Kent Inge

2014-01-01

Code generation is an important part of model driven methodologies. In this paper, we present PetriCode, a software tool for generating protocol software from a subclass of Coloured Petri Nets (CPNs). The CPN subclass is comprised of hierarchical CPN models describing a protocol system at different...

Code Generation from Pragmatics Annotated Coloured Petri Nets

DEFF Research Database (Denmark)

Simonsen, Kent Inge

limited work has been done on transforming CPN model to protocol implementations. The goal of the thesis is to be able to automatically generate high-quality implementations of communication protocols based on CPN models. In this thesis, we develop a methodology for generating implementations of protocols...... third party libraries and the code should be easily usable by third party code. Finally, the code should be readable by developers with expertise on the considered platforms. In this thesis, we show that our code generation approach is able to generate code for a wide range of platforms without altering...... such as games and rich web applications. Finally, we conclude the evaluation of the criteria of our approach by using the WebSocket PA-CPN model to show that we are able to verify fairly large protocols....

Study of the integration of distributed generation systems in the grid: application in micro-grids; Etude de structures d'integration des systemes de generation decentralisee: application aux microreseaux

Energy Technology Data Exchange (ETDEWEB)

Gaztanaga Arantzamendi, H

2006-12-15

The present PhD deals with an original micro-grid concept and its application as a Renewable Energy Source's (RES) grid integration scheme. This micro-grid is composed of RES generators as well as support systems that incorporate additional functionalities in order to improve RES integration into the grid. According to this concept, two practical micro-grid applications have been studied in detail: a residential micro-grid and a wind farm supported by DFACTS systems (STATCOM and DVR). In both applications, the control structures which are implemented at different levels and applied to the different micro-grid elements have been developed, analyzed by means of off-line simulations and finally validated in real-time conditions with physical reduced-scale prototypes. (author)

Alternatives to the grid : distributed generation

Energy Technology Data Exchange (ETDEWEB)

Kline, R.H. [Mercury Electric Corp., Calgary, AB (Canada)

2001-07-01

This presentation highlighted the merits of distributed generation. The author began by discussing energy drivers, touching on issues such as reliability, power quality, and the confusion resulting from the energy market, and energy costs. It was pointed out that the deregulation of the electricity market in Alberta was implemented on January 1, 1996 which has resulted in steady price increases ever since. A review of the options available to the customer begin by understanding baseload and peaking. The options then available are buying from the utility, buying through a reputable marketer, buying direct from a large scale independent power producer, on-site generation, and finally, distributed generation. The emphasis was placed on distributed generation defined as small scale on-site power generation and offers advantages such as the reduction/elimination of peak strain on grid, and offset/defer utility capital costs, therefore reducing total energy costs. Regulatory changes are making it easier than ever before to make the transition to distributed generation. The author briefly reviewed the advantages of microturbines then presented the Honeywell Parallon 75 TurboGenerator{sup TM}, reviewing its characteristics, operating modes and commercial applications. Examples were provided of successful microturbines installations throughout the country. figs.

Rating Requirements of the UPQC to Integrate the FSIG Type Wind Generation to the Grid

OpenAIRE

Jayanti, N.; Basu, Malabika; Conlon, Michael; Gaughan, Kevin

2009-01-01

The ability of wind generation to remain connected to the grid in the event of system faults and dynamic reactive power compensation are two aspects of grid integration, which have received particular attention. The wind driven, fixed-speed induction generator (FSIG) on its own fails to fulfil these requirements of grid integration. The application of a unified power quality conditioner (UPQC) to overcome the grid integration problems of the FSIG is investigated. The role of the UPQC in enhan...

Study of DFIG Wind Turbine Fault Ride-Through According to The Danish Grid Code

DEFF Research Database (Denmark)

Abulanwar, Elsayed; Chen, Zhe; Bak-Jensen, Birgitte

2013-01-01

of the DC link voltage and the reactive power, and counteract the DC link voltage runaway. Moreover, the GSC is dedicated to inject more reactive power during voltage dips to satisfy the grid code reactive power support obligation. A conventional PI controller is devoted to control the rotor side converter...

Identification of Synchronous Generator Electric Parameters Connected to the Distribution Grid

Directory of Open Access Journals (Sweden)

Frolov M. Yu.

2017-04-01

Full Text Available According to modern trends, the power grids with distributed generation will have an open system architecture. It means that active consumers, owners of distributed power units, including mobile units, must have free access to the grid, like when using internet, so it is necessary to have plug and play technologies. Thanks to them, the system will be able to identify the unit type and the unit parameters. Therefore, the main aim of research, described in the paper, was to develop and research a new method of electric parameters identification of synchronous generator. The main feature of the proposed method is that parameter identification is performed while the generator to the grid, so it fits in the technological process of operation of the machine and does not influence on the connection time of the machine. For the implementation of the method, it is not necessary to create dangerous operation modes for the machine or to have additional expensive equipment and it can be used for salient pole machines and round rotor machines. The parameter identification accuracy can be achieved by more accurate account of electromechanical transient process, and making of overdetermined system with many more numbers of equations. Parameter identification will be made with each generator connection to the grid. Comparing data obtained from each connection, the middle values can be find by numerical method, and thus, each subsequent identification will accurate the machine parameters.

Grid support by power electronic converters of distributed generation units

NARCIS (Netherlands)

Morren, J.

2006-01-01

An increasing number of small Distributed Generation (DG) units are connected to the grid. The introduction of DG causes several problems, which are mainly related to the differences between DG units and conventional generators. Four problems have been considered in this thesis: damping of

Research on simulated devices for Solar photovoltaic grid-connected generation system

Directory of Open Access Journals (Sweden)

quan-zhu Zhang

2017-01-01

Full Text Available On the standpoint of energy conservation and emission reduction, one device simulated photovoltaic grid-connected generation system based on SPWM was designed in the paper. And DC/AC inverter could transduce efficiently direct current to alternating current. The MCU(Micro-Control-Unit, in this system could achieve the control method for maximum-power-point and tracking for frequency and phase. Moreover, the MCU could implement PWM (Plus-Width Modulating through programming. The system showed clearly the whole photovoltaic grid-connected generation system using simulated methods and ways.

SmartGrid: Future networks for New Zealand power systems incorporating distributed generation

International Nuclear Information System (INIS)

Nair, Nirmal-Kumar C.; Zhang Lixi

2009-01-01

The concept of intelligent electricity grids, which primarily involves the integration of new information and communication technologies with power transmission lines and distribution cables, is being actively explored in the European Union and the United States. Both developments share common technological developmental goals but also differ distinctly towards the role of distributed generation for their future electrical energy security. This paper looks at options that could find relevance to New Zealand (NZ), in the context of its aspiration of achieving 90% renewable energy electricity generation portfolio by 2025. It also identifies developments in technical standardization and industry investments that facilitate a pathway towards an intelligent or smart grid development for NZ. Some areas where policy can support research in NZ being a 'fast adapter' to future grid development are also listed. This paper will help policy makers quickly review developments surrounding SmartGrid and also identify its potential to support NZ Energy Strategy in the electricity infrastructure. This paper will also help researchers and power system stakeholders for identifying international standardization, projects and potential partners in the area of future grid technologies.

Active and reactive power neurocontroller for grid-connected photovoltaic generation system

Directory of Open Access Journals (Sweden)

I. Abadlia

2016-03-01

Full Text Available Many researchers have contributed to the development of a firm foundation for analysis and design of control applications in grid-connected renewable energy sources. This paper presents an intelligent control algorithm fond on artificial neural networks for active and reactive power controller in grid-connected photovoltaic generation system. The system is devices into two parts in which each part contains an inverter with control algorithm. A DC/DC converter in output voltage established by control magnitude besides maximum power point tracker algorithm always finds optimal power of the PV array in use. A DC/AC hysteresis inverter designed can synchronize a sinusoidal current output with the grid voltage and accurate an independent active and reactive power control. Simulation results confirm the validation of the purpose. Neurocontroller based active and reactive power presents an efficiency control that guarantees good response to the steps changing in active and reactive power with an acceptable current/voltage synchronism. In this paper the power circuit and the control system of the presented grid-connected photovoltaic generation system is simulated and tested by MatLab/Simulink.

Surface Modeling, Grid Generation, and Related Issues in Computational Fluid Dynamic (CFD) Solutions

Science.gov (United States)

Choo, Yung K. (Compiler)

1995-01-01

The NASA Steering Committee for Surface Modeling and Grid Generation (SMAGG) sponsored a workshop on surface modeling, grid generation, and related issues in Computational Fluid Dynamics (CFD) solutions at Lewis Research Center, Cleveland, Ohio, May 9-11, 1995. The workshop provided a forum to identify industry needs, strengths, and weaknesses of the five grid technologies (patched structured, overset structured, Cartesian, unstructured, and hybrid), and to exchange thoughts about where each technology will be in 2 to 5 years. The workshop also provided opportunities for engineers and scientists to present new methods, approaches, and applications in SMAGG for CFD. This Conference Publication (CP) consists of papers on industry overview, NASA overview, five grid technologies, new methods/ approaches/applications, and software systems.

SmaggIce 2.0: Additional Capabilities for Interactive Grid Generation of Iced Airfoils

Science.gov (United States)

Kreeger, Richard E.; Baez, Marivell; Braun, Donald C.; Schilling, Herbert W.; Vickerman, Mary B.

2008-01-01

The Surface Modeling and Grid Generation for Iced Airfoils (SmaggIce) software toolkit has been extended to allow interactive grid generation for multi-element iced airfoils. The essential phases of an icing effects study include geometry preparation, block creation and grid generation. SmaggIce Version 2.0 now includes these main capabilities for both single and multi-element airfoils, plus an improved flow solver interface and a variety of additional tools to enhance the efficiency and accuracy of icing effects studies. An overview of these features is given, especially the new multi-element blocking strategy using the multiple wakes method. Examples are given which illustrate the capabilities of SmaggIce for conducting an icing effects study for both single and multi-element airfoils.

COSINE software development based on code generation technology

International Nuclear Information System (INIS)

Ren Hao; Mo Wentao; Liu Shuo; Zhao Guang

2013-01-01

The code generation technology can significantly improve the quality and productivity of software development and reduce software development risk. At present, the code generator is usually based on UML model-driven technology, which can not satisfy the development demand of nuclear power calculation software. The feature of scientific computing program was analyzed and the FORTRAN code generator (FCG) based on C# was developed in this paper. FCG can generate module variable definition FORTRAN code automatically according to input metadata. FCG also can generate memory allocation interface for dynamic variables as well as data access interface. FCG was applied to the core and system integrated engine for design and analysis (COSINE) software development. The result shows that FCG can greatly improve the development efficiency of nuclear power calculation software, and reduce the defect rate of software development. (authors)

Enhanced Local Grid Voltage Support Method for High Penetration of Distributed Generators

DEFF Research Database (Denmark)

Demirok, Erhan; Sera, Dezso; Rodriguez, Pedro

2011-01-01

Grid voltage rise and thermal loading of network components are the most remarkable barriers to allow high number of distributed generator (DG) connections on the medium voltage (MV) and low voltage (LV) electricity networks. The other barriers such as grid power quality (harmonics, voltage...

Optimized Reactive Power Flow of DFIG Power Converters for Better Reliability Performance Considering Grid Codes

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

2015-01-01

. In order to fulfill the modern grid codes, over-excited reactive power injection will further reduce the lifetime of the rotor-side converter. In this paper, the additional stress of the power semiconductor due to the reactive power injection is firstly evaluated in terms of modulation index...

Grid faults' impact on wind turbine structural loads

Energy Technology Data Exchange (ETDEWEB)

Hansen, A.D.; Cutululis, N.A.; Soerensen, P.; Larsen, T.J. [Risoe National Lab., DTU, Wind Energy Dept. (Denmark); Iov, F.

2007-11-15

The objective of this work is to illustrate the impact of the grid faults on the wind turbine structural loads. Grid faults are typically in detailed power system simulation tools, which by applying simplified mechanical models, are not able to provide a throughout insight on the structural loads caused by sudden disturbances on the grid. On the other hand, structural loads of the wind turbine are typically assessed in advanced aeroelastic computer codes, which by applying simplified electrical models do not provide detailed electrical insight. This paper presents a simulation strategy, where the focus is on how to access a proper combination of two complementary simulation tools, such as the advanced aeroelastic computer code HAWC2 and the detailed power system simulation tool DIgSILENT, in order to provide a whole overview of both the structural and the electrical behaviour of the wind turbine during grid faults. The effect of a grid fault on the wind turbine flexible structure is assessed for a typical fixed speed wind turbine, equipped with an induction generator. (au)

Optimized Method for Generating and Acquiring GPS Gold Codes

Directory of Open Access Journals (Sweden)

Khaled Rouabah

2015-01-01

Full Text Available We propose a simpler and faster Gold codes generator, which can be efficiently initialized to any desired code, with a minimum delay. Its principle consists of generating only one sequence (code number 1 from which we can produce all the other different signal codes. This is realized by simply shifting this sequence by different delays that are judiciously determined by using the bicorrelation function characteristics. This is in contrast to the classical Linear Feedback Shift Register (LFSR based Gold codes generator that requires, in addition to the shift process, a significant number of logic XOR gates and a phase selector to change the code. The presence of all these logic XOR gates in classical LFSR based Gold codes generator provokes the consumption of an additional time in the generation and acquisition processes. In addition to its simplicity and its rapidity, the proposed architecture, due to the total absence of XOR gates, has fewer resources than the conventional Gold generator and can thus be produced at lower cost. The Digital Signal Processing (DSP implementations have shown that the proposed architecture presents a solution for acquiring Global Positioning System (GPS satellites signals optimally and in a parallel way.

Alternatives to the grid : distributed generation

Energy Technology Data Exchange (ETDEWEB)

Kline, R.H. [Mercury Electric Co., Calgary, AB (Canada)

2002-07-01

This presentation outlines the benefits of distributed generation with reference to energy drivers, reliability, power quality, and the impact of open energy markets. Deregulation in Alberta's electric power industry has created options and imposed responsibilities on both industrial and commercial consumers. Customers have the option to self-generate a portion or all of their energy needs. The options are to buy energy from a power marketer, to buy energy from the Power Pool of Alberta, to develop one's own power, or to contract with an independent power producer. It is important to understand base load and peaking requirements in order to determine which option is best, where power quality and reliability will not be compromised. Small scale on-site power generation offers advantages such as reduced peak strain on the transmission grid, and reduced total energy costs. Regulatory changes are making it easier than ever to make the transition to distributed generation. The author briefly reviews the advantages of reciprocating engines and turbine-based generators. He notes that fuel cells, solar, and wind generators are not currently economically viable options. Mercury Electric's conventional turbine systems are illustrated as a potential viable option for self-generation. 2 figs.

Grid Integration Issues for Large Scale Wind Power Plants (WPPs)

DEFF Research Database (Denmark)

Wu, Qiuwei; Xu, Zhao; Østergaard, Jacob

2010-01-01

transmission system operators (TSOs) over the world have come up the grid codes to request the wind power plants (WPPs) to have more or less the same operating capability as the conventional power plants. The grid codes requirements from other TSOs are under development. This paper covers the steady state......The penetration level of wind power into the power system over the world have been increasing very fast in the last few years and is still keeping the fast growth rate. It is just a matter of time that the wind power will be comparable to the conventional power generation. Therefore, many...

The Application of Stationary VOC-PR with PLL for Grid side Converter-based Wind Power Generation System

DEFF Research Database (Denmark)

Guo, Yougui; Zeng, Ping; Li, Lijuan

2010-01-01

Voltage oriented control PR is combined with space vector modulation and phase locked loop to control the grid side converter in wind power generation system in this paper. First the mathematical models of grid side converter and LCL filter as well as grid are given. Then the control strategy...... of grid side converter-based wind power generation system is given in detail. Finally the simulation model consisting of the grid side converter wind power generation system is set up. The simulation results have verified that the control strategy is feasible to be used for control of gird currents......, active power, reactive power and DC-link voltage in wind power generation system. It has laid a good basis for the real system development....

High Order Sliding Mode Control of Doubly-fed Induction Generator under Unbalanced Grid Faults

DEFF Research Database (Denmark)

Zhu, Rongwu; Chen, Zhe; Wu, Xiaojie

2013-01-01

This paper deals with a doubly-fed induction generator-based (DFIG) wind turbine system under grid fault conditions such as: unbalanced grid voltage, three-phase grid fault, using a high order sliding mode control (SMC). A second order sliding mode controller, which is robust with respect...

Free piston linear generator for low grid power generation

Directory of Open Access Journals (Sweden)

Abdalla Izzeldin

2017-01-01

Full Text Available Generating power is of great importance nowadays across the world. However, recently, the world became aware of the climatic changes due to the greenhouse effect caused by CO2 emissions and began seeking solutions to reduce the negative impact on the environment. Besides, the exhaustion of fossil fuels and their environmental impact, make it is crucial to develop clean energy sources, and efforts are focused on developing and improving the efficiency of all energy consuming systems. The tubular permanent magnet linear generators (TPMLGs are the best candidate for energy converters. Despite being suffering problem of attraction force between permanent magnets and stator teeth, to eliminate such attraction force, ironless-stator could be considered. Thus, they could waive the presence of any magnetic attraction between the moving and stator part. This paper presents the design and analysis of ironless -cored TPMLG for low grid power generation. The main advantages of this generator are the low cogging force and high efficiency. Therefore, the magnetic field computation of the proposed generator has been performed by applying a magnetic vector potential and utilizing a 2-D finite element analysis (FEA. Moreover, the experimental results for the current profile, pressure profile and velocity profile have been presented.

A new solution-adaptive grid generation method for transonic airfoil flow calculations

Science.gov (United States)

Nakamura, S.; Holst, T. L.

1981-01-01

The clustering algorithm is controlled by a second-order, ordinary differential equation which uses the airfoil surface density gradient as a forcing function. The solution to this differential equation produces a surface grid distribution which is automatically clustered in regions with large gradients. The interior grid points are established from this surface distribution by using an interpolation scheme which is fast and retains the desirable properties of the original grid generated from the standard elliptic equation approach.

DC micro-grid with distributed generation for rural electrification

NARCIS (Netherlands)

Sarker, M.J.; Asare-Bediako, B.; Alipuria, B.; Slootweg, J.G.; Kling, W.L.

2012-01-01

This paper investigates the use of low voltage DC distribution network for rural electrification within an intelligent grid concept. The goal is to provide local communities in sparsely populated areas with electricity supply generated from renewable energy sources. Since these communities subsist

Application of Load Compensation in Voltage Controllers of Large Generators in the Polish Power Grid

Directory of Open Access Journals (Sweden)

Bogdan Sobczak

2014-03-01

Full Text Available The Automatic Voltage Regulator normally controls the generator stator terminal voltage. Load compensation is used to control the voltage which is representative of the voltage at a point either within or external to the generator. In the Polish Power Grid (PPG compensation is ready to use in every AVR of a large generator, but it is utilized only in the case of generators operating at the same medium voltage buses. It is similar as in most European Power Grids. The compensator regulating the voltage at a point beyond the machine terminals has significant advantages in comparison to the slower secondary Voltage and Reactive Power Control System (ARNE1. The compensation stiffens the EHV grid, which leads to improved voltage quality in the distribution grid. This effect may be particularly important in the context of the dynamic development of wind and solar energy.

Control strategies for gas turbine generators for grid connected and islanding operations

DEFF Research Database (Denmark)

Mahat, Pukar; Chen, Zhe; Bak-Jensen, Birgitte

2010-01-01

fine while a DG is connected to a grid, might not work as desired while it is islanded and vise versa. This paper presents a strategy to operate distribution systems with a small gas turbine generator (GTG), which is capable of supplying local loads, in both islanding and grid connected conditions...

Operation strategy for a lab-scale grid-connected photovoltaic generation system integrated with battery energy storage

International Nuclear Information System (INIS)

Jou, Hurng-Liahng; Chang, Yi-Hao; Wu, Jinn-Chang; Wu, Kuen-Der

2015-01-01

Highlights: • The operation strategy for grid-connected PV generation system integrated with battery energy storage is proposed. • The PV system is composed of an inverter and two DC-DC converter. • The negative impact of grid-connected PV generation systems on the grid can be alleviated by integrating a battery. • The operation of the developed system can be divided into nine modes. - Abstract: The operation strategy for a lab-scale grid-connected photovoltaic generation system integrated with battery energy storage is proposed in this paper. The photovoltaic generation system is composed of a full-bridge inverter, a DC–DC boost converter, an isolated bidirectional DC–DC converter, a solar cell array and a battery set. Since the battery set acts as an energy buffer to adjust the power generation of the solar cell array, the negative impact on power quality caused by the intermittent and unstable output power from a solar cell array is alleviated, so the penetration rate of the grid-connected photovoltaic generation system is increased. A lab-scale prototype is developed to verify the performance of the system. The experimental results show that it achieves the expected performance

A chimera grid scheme. [multiple overset body-conforming mesh system for finite difference adaptation to complex aircraft configurations

Science.gov (United States)

Steger, J. L.; Dougherty, F. C.; Benek, J. A.

1983-01-01

A mesh system composed of multiple overset body-conforming grids is described for adapting finite-difference procedures to complex aircraft configurations. In this so-called 'chimera mesh,' a major grid is generated about a main component of the configuration and overset minor grids are used to resolve all other features. Methods for connecting overset multiple grids and modifications of flow-simulation algorithms are discussed. Computational tests in two dimensions indicate that the use of multiple overset grids can simplify the task of grid generation without an adverse effect on flow-field algorithms and computer code complexity.

Radionuclide daughter inventory generator code: DIG

International Nuclear Information System (INIS)

Fields, D.E.; Sharp, R.D.

1985-09-01

The Daughter Inventory Generator (DIG) code accepts a tabulation of radionuclide initially present in a waste stream, specified as amounts present either by mass or by activity, and produces a tabulation of radionuclides present after a user-specified elapsed time. This resultant radionuclide inventory characterizes wastes that have undergone daughter ingrowth during subsequent processes, such as leaching and transport, and includes daughter radionuclides that should be considered in these subsequent processes or for inclusion in a pollutant source term. Output of the DIG code also summarizes radionuclide decay constants. The DIG code was developed specifically to assist the user of the PRESTO-II methodology and code in preparing data sets and accounting for possible daughter ingrowth in wastes buried in shallow-land disposal areas. The DIG code is also useful in preparing data sets for the PRESTO-EPA code. Daughter ingrowth in buried radionuclides and in radionuclides that have been leached from the wastes and are undergoing hydrologic transport are considered, and the quantities of daughter radionuclide are calculated. Radionuclide decay constants generated by DIG and included in the DIG output are required in the PRESTO-II code input data set. The DIG accesses some subroutines written for use with the CRRIS system and accesses files containing radionuclide data compiled by D.C. Kocher. 11 refs

Grid-Connected Distributed Generation: Compensation Mechanism Basics

Energy Technology Data Exchange (ETDEWEB)

Aznar, Alexandra Y [National Renewable Energy Laboratory (NREL), Golden, CO (United States); ; ; ; Zinaman, Owen R [National Renewable Energy Laboratory (NREL), Golden, CO (United States)

2017-10-02

This short report defines compensation mechanisms for grid-connected, behind-the-meter distributed generation (DG) systems as instruments that comprise three core elements: (1) metering and billing arrangements, (2) sell rate design, and (3) retail rate design. This report describes metering and billing arrangements, with some limited discussion of sell rate design. We detail the three possible arrangements for metering and billing of DG: net energy metering (NEM); buy all, sell all; and net billing.

Chimera Grid Tools

Science.gov (United States)

Chan, William M.; Rogers, Stuart E.; Nash, Steven M.; Buning, Pieter G.; Meakin, Robert

2005-01-01

Chimera Grid Tools (CGT) is a software package for performing computational fluid dynamics (CFD) analysis utilizing the Chimera-overset-grid method. For modeling flows with viscosity about geometrically complex bodies in relative motion, the Chimera-overset-grid method is among the most computationally cost-effective methods for obtaining accurate aerodynamic results. CGT contains a large collection of tools for generating overset grids, preparing inputs for computer programs that solve equations of flow on the grids, and post-processing of flow-solution data. The tools in CGT include grid editing tools, surface-grid-generation tools, volume-grid-generation tools, utility scripts, configuration scripts, and tools for post-processing (including generation of animated images of flows and calculating forces and moments exerted on affected bodies). One of the tools, denoted OVERGRID, is a graphical user interface (GUI) that serves to visualize the grids and flow solutions and provides central access to many other tools. The GUI facilitates the generation of grids for a new flow-field configuration. Scripts that follow the grid generation process can then be constructed to mostly automate grid generation for similar configurations. CGT is designed for use in conjunction with a computer-aided-design program that provides the geometry description of the bodies, and a flow-solver program.

Optimal Operation of Micro-grids Considering the Uncertainties of Demand and Renewable Energy Resources Generation

Directory of Open Access Journals (Sweden)

Malek Jasemi

2016-11-01

Full Text Available Nowadays, due to technical and economic reasons, the distributed generation (DG units are widely connected to the low and medium voltage network and created a new structure called micro-grid. Renewable energies (especially wind and solar based DGs are one of the most important generations units among DG units. Because of stochastic behavior of these resources, the optimum and safe management and operation of micro-grids has become one of the research priorities for researchers. So, in this study, the optimal operation of a typical micro-grid is investigated in order to maximize the penetration of renewable energy sources with the lowest operation cost with respect to the limitations for the load supply and the distributed generation resources. The understudy micro-grid consists of diesel generator, battery, wind turbines and photovoltaic panels. The objective function comprises of fuel cost, start-up cost, spinning reserve cost, power purchasing cost from the upstream grid and the sales revenue of the power to the upstream grid. In this paper, the uncertainties of demand, wind speed and solar radiation are considered and the optimization will be made by using the GAMS software and mixed integer planning method (MIP. Article History: Received May 21, 2016; Received in revised form July 11, 2016; Accepted October 15, 2016; Available online How to Cite This Article: Jasemi, M.,  Adabi, F., Mozafari, B., and Salahi, S. (2016 Optimal Operation of Micro-grids Considering the Uncertainties of Demand and Renewable Energy Resources Generation, Int. Journal of Renewable Energy Development, 5(3,233-248. http://dx.doi.org/10.14710/ijred.5.3.233-248

Two-Level Semantics and Code Generation

DEFF Research Database (Denmark)

Nielson, Flemming; Nielson, Hanne Riis

1988-01-01

A two-level denotational metalanguage that is suitable for defining the semantics of Pascal-like languages is presented. The two levels allow for an explicit distinction between computations taking place at compile-time and computations taking place at run-time. While this distinction is perhaps...... not absolutely necessary for describing the input-output semantics of programming languages, it is necessary when issues such as data flow analysis and code generation are considered. For an example stack-machine, the authors show how to generate code for the run-time computations and still perform the compile...

Improved side information generation for distributed video coding

DEFF Research Database (Denmark)

Huang, Xin; Forchhammer, Søren

2008-01-01

As a new coding paradigm, distributed video coding (DVC) deals with lossy source coding using side information to exploit the statistics at the decoder to reduce computational demands at the encoder. The performance of DVC highly depends on the quality of side information. With a better side...... information generation method, fewer bits will be requested from the encoder and more reliable decoded frames will be obtained. In this paper, a side information generation method is introduced to further improve the rate-distortion (RD) performance of transform domain distributed video coding. This algorithm...

Design and analysis of active power control strategies for distributed generation inverters under unbalanced grid faults

NARCIS (Netherlands)

Wang, F.; Duarte, J.L.; Hendrix, M.A.M.

2010-01-01

Distributed power generation systems are expected to deliver active power into the grid and support it without interruption during unbalanced grid faults. Aiming to provide grid-interfacing inverters the flexibility to adapt to the coming change of grid requirements, an optimised active power

Dynamic analysis of combined photovoltaic source and synchronous generator connected to power grid

Science.gov (United States)

Mahabal, Divya

In the world of expanding economy and technology, the energy demand is likely to increase even with the global efforts of saving and increasing energy efficiency. Higher oil prices, effects of greenhouse gases, and concerns over other environmental impacts gave way to Distributed Generation (DG). With adequate awareness and support, DG's can meet these rising energy demands at lower prices compared to conventional methods. Extensive research is taking place in different areas like fuel cells, photovoltaic cells, wind turbines, and gas turbines. DG's when connected to a grid increase the overall efficiency of the power grid. It is believed that three-fifth of the world's electricity would account for renewable energy by middle of 21st century. This thesis presents the dynamic analysis of a grid connected photovoltaic (PV) system and synchronous generator. A grid is considered as an infinite bus. The photovol-taic system and synchronous generator act as small scale distributed energy resources. The output of the photovoltaic system depends on the light intensity, temperature, and irradiance levels of sun. The maximum power point tracking and DC/AC converter are also modeled for the photovoltaic system. The PV system is connected to the grid through DC/AC system. Different combinations of PV and synchronous generator are modeled with the grid to study the dynamics of the proposed system. The dynamics of the test system is analyzed by subjecting the system to several disturbances under various conditions. All modules are individually modeled and con-nected using MATLAB/Simulink software package. Results from the study show that, as the penetration of renewable energy sources like PV increases into the power system, the dynamics of the system becomes faster. When considering cases such as load switching, PV cannot deliver more power as the performance of PV depends on environmental conditions. Synchronous generator in power system can produce the required amount of

Grid-Forming-Mode Operation of Boost-Power-Stage Converter in PV-Generator-Interfacing Applications

Directory of Open Access Journals (Sweden)

Jukka Viinamäki

2017-07-01

Full Text Available The application of constant power control and inclusion of energy storage in grid-connected photovoltaic (PV energy systems may increase the use of two-stage system structures composed of DC–DC-converter-interfaced PV generator and grid-connected inverter connected in cascade. A typical PV-generator-interfacing DC–DC converter is a boost-power-stage converter. The renewable energy system may operate in three different operation modes—grid-forming, grid-feeding, and grid-supporting modes. In the last two operation modes, the outmost feedback loops are taken from the input terminal of the associated power electronic converters, which usually does not pose stability problems in terms of their input sources. In the grid-forming operation mode, the outmost feedback loops have to be connected to the output terminal of the associated power electronic converters, and hence the input terminal will behave as a negative incremental resistor at low frequencies. This property will limit the operation of the PV interfacing converter in either the constant voltage or constant current region of the PV generator for ensuring stable operation. The boost-power-stage converter can be applied as a voltage or current-fed converter limiting the stable operation region accordingly. The investigations of this paper show explicitly that only the voltage-fed mode would provide feasible dynamic and stability properties as a viable interfacing converter.

A simplified approach to detect undervoltage tripping of wind generators

Energy Technology Data Exchange (ETDEWEB)

Sigrist, Lukas; Rouco, Luis [Universidad Pontificia Comillas, Madrid (Spain). Inst. de Investigacion Tecnologica

2012-07-01

This paper proposes a simplified but fast approach based on a Norton equivalent of wind generators to detect undervoltage tripping of wind generators. This approach is successfully applied to a real wind farm. The relevant grid code requires the wind farm to withstand a voltage dip of 0% retained voltage. The ability of the wind generators to raise the voltage supplying reactive current and to avoid undervoltage tripping is investigated. The obtained results are also compared with the results obtained from detailed dynamic simulations, which make use of wind generator models complying with the relevant grid code. (orig.)

Solar photovoltaic systems and their use as grid-connected generators in the United Kingdom

Energy Technology Data Exchange (ETDEWEB)

Munro, D K; Hacker, R J; Thornycroft, J M [Halcrow Gilbert Associates Ltd., Swindon (United Kingdom)

1995-10-01

There is an increasing interest in the use of building-integrated solar photovoltaic generators as grid-connected generators. This paper discusses the experience with this technology in Europe. Typical systems and their integration into domestic and non-domestic buildings are described. Information is provided on the energy output that can be expected from the systems and the economics of their use. The paper provides an overview of the requirements for photovoltaic systems as grid-connected generation plant in the United Kingdom. (Author)

Experimental evaluation of square bar and fractal grid-generated turbulent flow inside recirculating water tunnel

Science.gov (United States)

Bornemeier, Matthew; Luznik, Luksa

2017-11-01

High resolution, two dimensional PIV measurements of grid-generated turbulence in the US Naval Academy's recirculating water tunnel (1.8m test section with 0.41m x 0.41m cross sectional area) are presented for two different grid designs. The first grid is a uniform square bar grid with mesh width, M =3.9cm, bar thickness t0 = 1cm, a streamwise thickness of 1cm and resulting solidity of 44%, similar to the conventional grid used by Krogstad and Davidson (2012). The other is Mazellier & Vassilicos' (2010) square fractal grid, SFG17, with fractal iteration count, N =4, thickness ratio tr = 17 and length ratio Lr = 8. Grid patterns differ from the published designs by a circular hole with 4.30cm diameter in the middle that will accept, in future experiments, a shaft connected to an axisymmetric rotating wake generator with diameter, D. Grids were designed to generate turbulence of specific integral length scale of O(D) and intensity of 6% at the prescribed downstream location. Mean tunnel centerline velocity is 2 m/s and measurements are made in a streamwise vertical center plane with nominal individual field of view (FOV) of 12x8 cm2. Spatial coverage in the test section is accomplished by ``tiling'' individual FOV with approximately 2cm overlap. Results will focus on characterizing resulting turbulence in the test section and discussion will include comparison between published results and the present measurements.

Operation Optimization in a Smart Micro-Grid in the Presence of Distributed Generation and Demand Response

Directory of Open Access Journals (Sweden)

Yongli Wang

2018-03-01

Full Text Available With the application of distributed generation and the development of smart grid technology, micro-grid, an economic and stable power grid, tends to play an important role in the demand side management. Because micro-grid technology and demand response have been widely applied, what Demand Response actions can realize the economic operation of micro-grid has become an important issue for utilities. In this proposed work, operation optimization modeling for micro-grid is done considering distributed generation, environmental factors and demand response. The main contribution of this model is to optimize the cost in the context of considering demand response and system operation. The presented optimization model can reduce the operation cost of micro-grid without bringing discomfort to the users, thus increasing the consumption of clean energy effectively. Then, to solve this operational optimization problem, genetic algorithm is used to implement objective function and DR scheduling strategy. In addition, to validate the proposed model, it is employed on a smart micro-grid from Tianjin. The obtained numerical results clearly indicate the impact of demand response on economic operation of micro-grid and development of distributed generation. Besides, a sensitivity analysis on the natural gas price is implemented according to the situation of China, and the result shows that the natural gas price has a great influence on the operation cost of the micro-grid and effect of demand response.

Decentralized electricity generation by using photovoltaic grid-connected solar system

International Nuclear Information System (INIS)

Tyutyundziev, N.; Vitanov, P.; Radkov, R.; Grottke, M.

2006-01-01

AcadPV is the first demonstration installation connected permanently to LV grid in Sofia, Bulgaria aiming at assessment of PV efficiencies and cost-effectiveness. A thorough analysis has been carried out in order to select PV system site, supporting construction design and orientation. The PV generator is divided to 3 PV subfields equipped by 3 SUNPOWER inverters connected to 3 separated phases of the grid. The performance of 10kWp PV system has been evaluated during the first year of operation and compared to PV simulation software results

SWAAM code development, verification and application to steam generator design

International Nuclear Information System (INIS)

Shin, Y.W.; Valentin, R.A.

1990-01-01

This paper describes the family of SWAAM codes developed by Argonne National Laboratory to analyze the effects of sodium/water reactions on LMR steam generators. The SWAAM codes were developed as design tools for analyzing various phenomena related to steam generator leaks and to predict the resulting thermal and hydraulic effects on the steam generator and the intermediate heat transport system (IHTS). The theoretical foundations and numerical treatments on which the codes are based are discussed, followed by a description of code capabilities and limitations, verification of the codes by comparison with experiment, and applications to steam generator and IHTS design. (author). 25 refs, 14 figs

A Parallel Multiblock Structured Grid Method with Automated Interblocked Unstructured Grids for Chemically Reacting Flows

Science.gov (United States)

Spiegel, Seth Christian

An automated method for using unstructured grids to patch non- C0 interfaces between structured blocks has been developed in conjunction with a finite-volume method for solving chemically reacting flows on unstructured grids. Although the standalone unstructured solver, FVFLO-NCSU, is capable of resolving flows for high-speed aeropropulsion devices with complex geometries, unstructured-mesh algorithms are inherently inefficient when compared to their structured counterparts. However, the advantages of structured algorithms in developing a flow solution in a timely manner can be negated by the amount of time required to develop a mesh for complex geometries. The global domain can be split up into numerous smaller blocks during the grid-generation process to alleviate some of the difficulties in creating these complex meshes. An even greater abatement can be found by allowing the nodes on abutting block interfaces to be nonmatching or non-C 0 continuous. One code capable of solving chemically reacting flows on these multiblock grids is VULCAN, which uses a nonconservative approach for patching non-C0 block interfaces. The developed automated unstructured-grid patching algorithm has been installed within VULCAN to provide it the capability of a fully conservative approach for patching non-C0 block interfaces. Additionally, the FVFLO-NCSU solver algorithms have been deeply intertwined with the VULCAN source code to solve chemically reacting flows on these unstructured patches. Finally, the CGNS software library was added to the VULCAN postprocessor so structured and unstructured data can be stored in a single compact file. This final upgrade to VULCAN has been successfully installed and verified using test cases with particular interest towards those involving grids with non- C0 block interfaces.

PSG: Peer-to-Peer semantic grid framework architecture

Directory of Open Access Journals (Sweden)

Amira Soliman

2011-07-01

Full Text Available The grid vision, of sharing diverse resources in a flexible, coordinated and secure manner, strongly depends on metadata. Currently, grid metadata is generated and used in an ad-hoc fashion, much of it buried in the grid middleware code libraries and database schemas. This ad-hoc expression and use of metadata causes chronic dependency on human intervention during the operation of grid machinery. Therefore, the Semantic Grid is emerged as an extension of the grid in which rich resource metadata is exposed and handled explicitly, and shared and managed via grid protocols. The layering of an explicit semantic infrastructure over the grid infrastructure potentially leads to increase interoperability and flexibility. In this paper, we present PSG framework architecture that offers semantic-based grid services. PSG architecture allows the explicit use of semantics and defining the associated grid services. PSG architecture is originated from the integration of Peer-to-Peer (P2P computing with semantics and agents. Ontologies are used in annotating each grid component, developing users/nodes profiles and organizing framework agents. While, P2P is responsible for organizing and coordinating the grid nodes and resources.

The performance test of anti-scattering x-ray grid with inclined shielding material by MCNP code simulation

Energy Technology Data Exchange (ETDEWEB)

Bae, Jun Woo; Kim, Hee Reyoung [Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2016-06-15

The scattered photons cause reduction of the contrast of radiographic image and it results in the degradation of the quality of the image. In order to acquire better quality image, an anti-scattering x-ray gird should be equipped in radiography system. The X-ray anti-scattering grid of the inclined type based on the hybrid concept for that of parallel and focused type was tested by MCNP code. The MCNPX 2.7.0 was used for the simulation based test. The geometry for the test was based on the IEC 60627 which was an international standard for diagnostic X-ray imaging equipment-Characteristics of general purpose and mammographic anti-scatter grids. The performance of grids with four inclined shielding material types was compared with that of the parallel type. The grid with completely tapered type the best performance where there were little performance difference according to the degree of inclination.

Auto Code Generation for Simulink-Based Attitude Determination Control System

Science.gov (United States)

MolinaFraticelli, Jose Carlos

2012-01-01

This paper details the work done to auto generate C code from a Simulink-Based Attitude Determination Control System (ADCS) to be used in target platforms. NASA Marshall Engineers have developed an ADCS Simulink simulation to be used as a component for the flight software of a satellite. This generated code can be used for carrying out Hardware in the loop testing of components for a satellite in a convenient manner with easily tunable parameters. Due to the nature of the embedded hardware components such as microcontrollers, this simulation code cannot be used directly, as it is, on the target platform and must first be converted into C code; this process is known as auto code generation. In order to generate C code from this simulation; it must be modified to follow specific standards set in place by the auto code generation process. Some of these modifications include changing certain simulation models into their atomic representations which can bring new complications into the simulation. The execution order of these models can change based on these modifications. Great care must be taken in order to maintain a working simulation that can also be used for auto code generation. After modifying the ADCS simulation for the auto code generation process, it is shown that the difference between the output data of the former and that of the latter is between acceptable bounds. Thus, it can be said that the process is a success since all the output requirements are met. Based on these results, it can be argued that this generated C code can be effectively used by any desired platform as long as it follows the specific memory requirements established in the Simulink Model.

Reliability and Energy Loss in Full-scale Wind Power Converter Considering Grid Codes and Wind Classes

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Franke, Toke

2014-01-01

With the increasing penetration of the wind power, reliable operation and cost-effective wind energy production are of more and more importance. As one of the promising configurations, the cost on reliability and production losses of permanent-magnet synchronous generator based full-scale wind......, if the specific designed wind turbine system operates at different wind classes, it can be seen that higher wind class level results in lower lifetime of the power converter. In respect to the cost of the reactive power, either the OE or the UE reactive power increases the energy loss per year significantly...... power converter is studied considering the grid code with reactive power production as well as the annual wind profile. Regarding the reliability, it is found that either the Over-Excited (OE) or the Under-Excited (UE) reactive power injection threatens the lifespan under all wind classes. Meanwhile...

Improved mesh generator for the POISSON Group Codes

International Nuclear Information System (INIS)

Gupta, R.C.

1987-01-01

This paper describes the improved mesh generator of the POISSON Group Codes. These improvements enable one to have full control over the way the mesh is generated and in particular the way the mesh density is distributed throughout this model. A higher mesh density in certain regions coupled with a successively lower mesh density in others keeps the accuracy of the field computation high and the requirements on the computer time and computer memory low. The mesh is generated with the help of codes AUTOMESH and LATTICE; both have gone through a major upgrade. Modifications have also been made in the POISSON part of these codes. We shall present an example of a superconducting dipole magnet to explain how to use this code. The results of field computations are found to be reliable within a few parts in a hundred thousand even in such complex geometries

Nuclear Power as an Option in Electrical Generation Planning for Small Economy and Electricity Grid

International Nuclear Information System (INIS)

Tomsic, Z.

2012-01-01

Implementing a NPP in countries with relatively small total GDP (small economy) and usually with small electricity grid face two major problems and constrains: the ability to obtain the considerable financial resources required on reasonable terms and to connect large NPP to small electricity grid. Nuclear generation financing in developing countries involves complex issues that need to be fully understood and dealt with by all the parties involved. The main topics covered by paper will be the: special circumstances related to the financing of NPP, costs and economic feasibility of NPP, conventional approaches for financing power generation projects in developing countries, alternative approaches for mobilizing financial resources. The safe and economic operation of a nuclear power plant (NPP) requires the plant to be connected to an electrical grid system that has adequate capacity for exporting the power from the NPP, and for providing a reliable electrical supply to the NPP for safe start-up, operation and normal or emergency shut-down of the plant. Connection of any large new power plant to the electrical grid system in a country may require significant modification and strengthening of the grid system, but for NPPs there may be added requirements to the structure of the grid system and the way it is controlled and maintained to ensure adequate reliability. Paper shows the comparative assesment of differrent base load technologies as an option in electrical generation planning for small economy and electricity grid.(author).

MAGNETOHYDRODYNAMIC EQUATIONS (MHD GENERATION CODE

Directory of Open Access Journals (Sweden)

Francisco Frutos Alfaro

2017-04-01

Full Text Available A program to generate codes in Fortran and C of the full magnetohydrodynamic equations is shown. The program uses the free computer algebra system software REDUCE. This software has a package called EXCALC, which is an exterior calculus program. The advantage of this program is that it can be modified to include another complex metric or spacetime. The output of this program is modified by means of a LINUX script which creates a new REDUCE program to manipulate the magnetohydrodynamic equations to obtain a code that can be used as a seed for a magnetohydrodynamic code for numerical applications. As an example, we present part of the output of our programs for Cartesian coordinates and how to do the discretization.

On-grid and Off-grid Operation of Multi-Input Single-Output DC/DC Converter based Fuel Cell Generation System

Directory of Open Access Journals (Sweden)

Noroozian

2009-06-01

Full Text Available This paper presents the modeling and simulation of a proton exchange membrane fuel cell (PEMFC generation system for off-grid and on-grid operation and configuration. A fuel cell DG system consists of a fuel cell power plant, a DC/DC converter and a DC/AC inverter. The dynamic model for fuel cell array and its power electronic interfacing are presented also a multi-input single output (MISO DC/DC converter and its control scheme is proposed and analyzed. This DC/DC converter is capable of interfacing fuel cell arrays to the DC/AC inverter. Also the mathematical model of the inverter is obtained by using average technique. Then the novel control strategy of DC/AC inverter for different operating conditions is demonstrated. The simulation results show the effectiveness of the suggested control systems under both on-grid and off-grid operation modes.

On the generation of coastline-following grids for ocean models—trade-off between orthogonality and alignment to coastlines

Science.gov (United States)

Liu, Xiaonan; Ma, Jialiang; Xu, Shiming; Wang, Bin

2017-08-01

Regional ocean models usually utilize orthogonal curvilinear grids that are fit to the coastline of the modeled regions. While the orthogonality of the grid is required from the perspective of the numerical algorithms, the alignment to the irregular coastlines improves the characterization of the land-sea distribution and the ocean simulation. In this article, we carry out fractal analysis of two representative coastal regions and discuss the trade-offs between the orthogonality and coastline alignment during the grid generation of these regions. A new grid generation method based on Schwarz-Christoffel conformal mappings is proposed, with automatic coastal boundary retrieval algorithm that generates resolution dependent boundary for grid generation and alleviates the human efforts involved in traditional methods. We show that for the southeastern Pacific region, the coastline is smooth with low fractal dimension and there exists effective trade-off with a coastline boundary that adjusts to the desired grid resolution. On the contrary, there is no effective trade-off for southeast China seas where the coastline is of higher fractal dimension, and a coarser coastline boundary is recommended for better orthogonality with little loss in coastline alignment. Further numerical study of coastal trapped Kelvin waves for the typical regions demonstrate that the new coastline-fitting grids achieve smaller error in numerical dispersion and higher accuracy. Through analysis, we conclude that for grid generation for regional ocean modeling, modelers should bring into consideration of the multi-scale fractal characteristics of the coastline.

High-resolution subgrid models: background, grid generation, and implementation

Science.gov (United States)

Sehili, Aissa; Lang, Günther; Lippert, Christoph

2014-04-01

The basic idea of subgrid models is the use of available high-resolution bathymetric data at subgrid level in computations that are performed on relatively coarse grids allowing large time steps. For that purpose, an algorithm that correctly represents the precise mass balance in regions where wetting and drying occur was derived by Casulli (Int J Numer Method Fluids 60:391-408, 2009) and Casulli and Stelling (Int J Numer Method Fluids 67:441-449, 2010). Computational grid cells are permitted to be wet, partially wet, or dry, and no drying threshold is needed. Based on the subgrid technique, practical applications involving various scenarios were implemented including an operational forecast model for water level, salinity, and temperature of the Elbe Estuary in Germany. The grid generation procedure allows a detailed boundary fitting at subgrid level. The computational grid is made of flow-aligned quadrilaterals including few triangles where necessary. User-defined grid subdivision at subgrid level allows a correct representation of the volume up to measurement accuracy. Bottom friction requires a particular treatment. Based on the conveyance approach, an appropriate empirical correction was worked out. The aforementioned features make the subgrid technique very efficient, robust, and accurate. Comparison of predicted water levels with the comparatively highly resolved classical unstructured grid model shows very good agreement. The speedup in computational performance due to the use of the subgrid technique is about a factor of 20. A typical daily forecast can be carried out in less than 10 min on a standard PC-like hardware. The subgrid technique is therefore a promising framework to perform accurate temporal and spatial large-scale simulations of coastal and estuarine flow and transport processes at low computational cost.

SWAAM-code development and verification and application to steam generator designs

International Nuclear Information System (INIS)

Shin, Y.W.; Valentin, R.A.

1990-01-01

This paper describes the family of SWAAM codes which were developed by Argonne National Laboratory to analyze the effects of sodium-water reactions on LMR steam generators. The SWAAM codes were developed as design tools for analyzing various phenomena related to steam generator leaks and the resulting thermal and hydraulic effects on the steam generator and the intermediate heat transport system (IHTS). The paper discusses the theoretical foundations and numerical treatments on which the codes are based, followed by a description of code capabilities and limitations, verification of the codes and applications to steam generator and IHTS designs. 25 refs., 14 figs

Intelligent voltage control in a DC micro-grid containing PV generation and energy storage

OpenAIRE

Rouzbehi, Kumars; Miranian, Arash; Candela García, José Ignacio; Luna Alloza, Álvaro; Rodríguez Cortés, Pedro

2014-01-01

This paper proposes an intelligent control scheme for DC voltage regulationin a DC micro-grid integrating photovoltaic (PV) generation, energy storage and electric loads. The maximum power generation of the PV panel is followed using the incremental conductance (IC) maximum power point tracking (MPPT) algorithm while a high-performance local linear controller (LLC)is developed for the DC voltage control in the micro-grid.The LLC, as a data-driven control strategy, controls the bidirectional c...

User's manual for the HYPGEN hyperbolic grid generator and the HGUI graphical user interface

Science.gov (United States)

Chan, William M.; Chiu, Ing-Tsau; Buning, Pieter G.

1993-01-01

The HYPGEN program is used to generate a 3-D volume grid over a user-supplied single-block surface grid. This is accomplished by solving the 3-D hyperbolic grid generation equations consisting of two orthogonality relations and one cell volume constraint. In this user manual, the required input files and parameters and output files are described. Guidelines on how to select the input parameters are given. Illustrated examples are provided showing a variety of topologies and geometries that can be treated. HYPGEN can be used in stand-alone mode as a batch program or it can be called from within a graphical user interface HGUI that runs on Silicon Graphics workstations. This user manual provides a description of the menus, buttons, sliders, and typein fields in HGUI for users to enter the parameters needed to run HYPGEN. Instructions are given on how to configure the interface to allow HYPGEN to run either locally or on a faster remote machine through the use of shell scripts on UNIX operating systems. The volume grid generated is copied back to the local machine for visualization using a built-in hook to PLOT3D.

PUFF-IV, Code System to Generate Multigroup Covariance Matrices from ENDF/B-VI Uncertainty Files

International Nuclear Information System (INIS)

2007-01-01

1 - Description of program or function: The PUFF-IV code system processes ENDF/B-VI formatted nuclear cross section covariance data into multigroup covariance matrices. PUFF-IV is the newest release in this series of codes used to process ENDF uncertainty information and to generate the desired multi-group correlation matrix for the evaluation of interest. This version includes corrections and enhancements over previous versions. It is written in Fortran 90 and allows for a more modular design, thus facilitating future upgrades. PUFF-IV enhances support for resonance parameter covariance formats described in the ENDF standard and now handles almost all resonance parameter covariance information in the resolved region, with the exception of the long range covariance sub-subsections. PUFF-IV is normally used in conjunction with an AMPX master library containing group averaged cross section data. Two utility modules are included in this package to facilitate the data interface. The module SMILER allows one to use NJOY generated GENDF files containing group averaged cross section data in conjunction with PUFF-IV. The module COVCOMP allows one to compare two files written in COVERX format. 2 - Methods: Cross section and flux values on a 'super energy grid,' consisting of the union of the required energy group structure and the energy data points in the ENDF/B-V file, are interpolated from the input cross sections and fluxes. Covariance matrices are calculated for this grid and then collapsed to the required group structure. 3 - Restrictions on the complexity of the problem: PUFF-IV cannot process covariance information for energy and angular distributions of secondary particles. PUFF-IV does not process covariance information in Files 34 and 35; nor does it process covariance information in File 40. These new formats will be addressed in a future version of PUFF

Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System with Optimized Grid Filter

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Franke, Toke

2014-01-01

The modern grid requirement has caused that the wind power system behaves more like conventional rotating generators and it is able to support certain amount of the reactive power. For a typical doubly-fed induction generator wind turbine system, the reactive power can be supported either through...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterwards, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...... the rotor-side converter or the grid-side converter. This paper firstly compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...

Reduced Cost of Reactive Power in Doubly Fed Induction Generator Wind Turbine System With Optimized Grid Filter

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Franke, Toke

2015-01-01

The modern grid requirement has caused that the wind power system behaves more like conventional rotating generators, and it is able to support certain amount of the reactive power. For a typical doubly fed induction generator (DFIG) wind turbine system, the reactive power can be supported either...... for the generator and the wind power converter in terms of the reactive power done by the rotor-side converter or the grid-side converter with various grid filters. Afterward, the annual energy loss is also estimated based on yearly wind profile. Finally, experimental results of the loss distribution are performed...... through the rotor-side converter or the grid-side converter. This paper first compares the current ripples and supportive reactive power ranges between the conventional L and optimized LCL filter, if the reactive power is injected from the grid-side converter. Then, the loss distribution is evaluated both...

Active power control strategies for inverter-based distributed power generation adapted to grid-fault ride-through requirements

NARCIS (Netherlands)

Wang, F.; Duarte, J.L.; Hendrix, M.A.M.

2009-01-01

Distributed power generation is expected to deliver power into the grid without interruption during voltage dips. To improve system ride-through capabilities, a generalized active power control strategy is proposed for grid-interfacing inverters. Specifically, a current reference generation strategy

Global Renewable Energy-Based Electricity Generation and Smart Grid System for Energy Security

Science.gov (United States)

Islam, M. A.; Hasanuzzaman, M.; Rahim, N. A.; Nahar, A.; Hosenuzzaman, M.

2014-01-01

Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration. PMID:25243201

Global renewable energy-based electricity generation and smart grid system for energy security.

Science.gov (United States)

Islam, M A; Hasanuzzaman, M; Rahim, N A; Nahar, A; Hosenuzzaman, M

2014-01-01

Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration.

Global Renewable Energy-Based Electricity Generation and Smart Grid System for Energy Security

Directory of Open Access Journals (Sweden)

M. A. Islam

2014-01-01

Full Text Available Energy is an indispensable factor for the economic growth and development of a country. Energy consumption is rapidly increasing worldwide. To fulfill this energy demand, alternative energy sources and efficient utilization are being explored. Various sources of renewable energy and their efficient utilization are comprehensively reviewed and presented in this paper. Also the trend in research and development for the technological advancement of energy utilization and smart grid system for future energy security is presented. Results show that renewable energy resources are becoming more prevalent as more electricity generation becomes necessary and could provide half of the total energy demands by 2050. To satisfy the future energy demand, the smart grid system can be used as an efficient system for energy security. The smart grid also delivers significant environmental benefits by conservation and renewable generation integration.

Control of power converters in distributed generation applications under grid fault conditions

DEFF Research Database (Denmark)

Rodriguez, Pedro; Luna, Alvaro; Munoz-Aguilar, Raul

2011-01-01

The operation of distributed power generation systems under grid fault conditions is a key issue for the massive integration of renewable energy systems. Several studies have been conducted to improve the response of such distributed generation systems under voltage dips. In spite of being less s...

Next generation Zero-Code control system UI

CERN Multimedia

CERN. Geneva

2017-01-01

Developing ergonomic user interfaces for control systems is challenging, especially during machine upgrade and commissioning where several small changes may suddenly be required. Zero-code systems, such as *Inspector*, provide agile features for creating and maintaining control system interfaces. More so, these next generation Zero-code systems bring simplicity and uniformity and brake the boundaries between Users and Developers. In this talk we present *Inspector*, a CERN made Zero-code application development system, and we introduce the major differences and advantages of using Zero-code control systems to develop operational UI.

Development and Evaluation of a Methodology for the Generation of Gridded Isotopic Datasets

International Nuclear Information System (INIS)

Argiriou, A.A.; Salamalikis, V; Lykoudis, S.P.

2013-01-01

The accurate knowledge of the spatial distribution of stable isotopes in precipitation is necessary for several applications. Since the number of rain sampling stations is small and unevenly distributed around the globe, the global distribution of stable isotopes can be calculated via the generation of gridded isotopic data sets. Several methods have been proposed for this purpose. In this work a methodology is proposed for the development of 10'x 10' gridded isotopic data from precipitation in the central and eastern Mediterranean. Statistical models are developed taking into account geographical and meteorological parameters as regressors. The residuals are interpolated onto the grid using ordinary kriging and thin plate splines. The result is added to the model grids, to obtain the final isotopic gridded data sets. Models are evaluated using an independent data set. the overall performance of the procedure is satisfactory and the obtained gridded data reproduce the isotopic parameters successfully. (author)

Development and Evaluation of a Methodology for the Generation of Gridded Isotopic Datasets

Energy Technology Data Exchange (ETDEWEB)

Argiriou, A. A.; Salamalikis, V [University of Patras, Department of Physics, Laboratory of Atmospheric Physics, Patras (Greece); Lykoudis, S. P. [National Observatory of Athens, Institute of Environmental and Sustainable Development, Athens (Greece)

2013-07-15

The accurate knowledge of the spatial distribution of stable isotopes in precipitation is necessary for several applications. Since the number of rain sampling stations is small and unevenly distributed around the globe, the global distribution of stable isotopes can be calculated via the generation of gridded isotopic data sets. Several methods have been proposed for this purpose. In this work a methodology is proposed for the development of 10'x 10' gridded isotopic data from precipitation in the central and eastern Mediterranean. Statistical models are developed taking into account geographical and meteorological parameters as regressors. The residuals are interpolated onto the grid using ordinary kriging and thin plate splines. The result is added to the model grids, to obtain the final isotopic gridded data sets. Models are evaluated using an independent data set. the overall performance of the procedure is satisfactory and the obtained gridded data reproduce the isotopic parameters successfully. (author)

Common Envelope Light Curves. I. Grid-code Module Calibration

Energy Technology Data Exchange (ETDEWEB)

Galaviz, Pablo; Marco, Orsola De; Staff, Jan E.; Iaconi, Roberto [Department of Physics and Astronomy, Macquarie University, Sydney, NSW (Australia); Passy, Jean-Claude, E-mail: Pablo.Galaviz@me.com [Argelander-Institut für Astronomie, Auf dem Hügel 71, D-53121 Bonn (Germany)

2017-04-01

The common envelope (CE) binary interaction occurs when a star transfers mass onto a companion that cannot fully accrete it. The interaction can lead to a merger of the two objects or to a close binary. The CE interaction is the gateway of all evolved compact binaries, all stellar mergers, and likely many of the stellar transients witnessed to date. CE simulations are needed to understand this interaction and to interpret stars and binaries thought to be the byproduct of this stage. At this time, simulations are unable to reproduce the few observational data available and several ideas have been put forward to address their shortcomings. The need for more definitive simulation validation is pressing and is already being fulfilled by observations from time-domain surveys. In this article, we present an initial method and its implementation for post-processing grid-based CE simulations to produce the light curve so as to compare simulations with upcoming observations. Here we implemented a zeroth order method to calculate the light emitted from CE hydrodynamic simulations carried out with the 3D hydrodynamic code Enzo used in unigrid mode. The code implements an approach for the computation of luminosity in both optically thick and optically thin regimes and is tested using the first 135 days of the CE simulation of Passy et al., where a 0.8  M {sub ⊙} red giant branch star interacts with a 0.6  M {sub ⊙} companion. This code is used to highlight two large obstacles that need to be overcome before realistic light curves can be calculated. We explain the nature of these problems and the attempted solutions and approximations in full detail to enable the next step to be identified and implemented. We also discuss our simulation in relation to recent data of transients identified as CE interactions.

New grid-planning and certification approaches for the large-scale offshore-wind farm grid-connection systems

Energy Technology Data Exchange (ETDEWEB)

Heising, C.; Bartelt, R. [Avasition GmbH, Dortmund (Germany); Zadeh, M. Koochack; Lebioda, T.J.; Jung, J. [TenneT Offshore GmbH, Bayreuth (Germany)

2012-07-01

Stable operation of the offshore-wind farms (OWF) and stable grid connection under stationary and dynamic conditions are essential to achieve a stable public power supply. To reach this aim, adequate grid-planning and certification approaches are a major advantage. Within this paper, the fundamental characteristics of the offshore-wind farms and their grid-connection systems are given. The main goal of this research project is to study the stability of the offshore grid especially in terms of subharmonic stability for the likely future extension stage of the offshore grids i.e. having parallel connection of two or more HVDC links and for certain operating scenarios e.g. overload scenario. The current requirements according to the grid code are not the focus of this research project. The goal is to study and define potential additional grid code requirements, simulations, tests and grid planning methods for the future. (orig.)

A three-dimensional algebraic grid generation scheme for gas turbine combustors with inclined slots

Science.gov (United States)

Yang, S. L.; Cline, M. C.; Chen, R.; Chang, Y. L.

1993-01-01

A 3D algebraic grid generation scheme is presented for generating the grid points inside gas turbine combustors with inclined slots. The scheme is based on the 2D transfinite interpolation method. Since the scheme is a 2D approach, it is very efficient and can easily be extended to gas turbine combustors with either dilution hole or slot configurations. To demonstrate the feasibility and the usefulness of the technique, a numerical study of the quick-quench/lean-combustion (QQ/LC) zones of a staged turbine combustor is given. Preliminary results illustrate some of the major features of the flow and temperature fields in the QQ/LC zones. Formation of co- and counter-rotating bulk flow and shape temperature fields can be observed clearly, and the resulting patterns are consistent with experimental observations typical of the confined slanted jet-in-cross flow. Numerical solutions show the method to be an efficient and reliable tool for generating computational grids for analyzing gas turbine combustors with slanted slots.

A Synchronization Method for Single-Phase Grid-Tied Inverters

DEFF Research Database (Denmark)

Hadjidemetriou, Lenos; Kyriakides, Elias; Yang, Yongheng

2016-01-01

The controllers of single-phase grid-tied inverters require improvements to enable distribution generation systems to meet the grid codes/standards with respect to power quality and the fault ride through capability. In that case, the response of the selected synchronization technique is crucial...... for the performance of the entire grid-tied inverter. In this paper, a new synchronization method with good dynamics and high accuracy under a highly distorted voltage is proposed. This method uses a Multi-Harmonic Decoupling Cell (MHDC), which thus can cancel out the oscillations on the synchronization signals due...... to the harmonic voltage distortion while maintaining the dynamic response of the synchronization. Therefore, the accurate and dynamic response of the proposed MHDC-PLL can be beneficial for the performance of the whole single-phase grid-tied inverter....

Power Quality Improvement Utilizing Photovoltaic Generation Connected to a Weak Grid

Energy Technology Data Exchange (ETDEWEB)

Muljadi, Eduard [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Tumbelaka, Hanny H. [Petra Christian University; Gao, Wenzhong [UNiversity of Denver

2017-11-07

Microgrid research and development in the past decades have been one of the most popular topics. Similarly, the photovoltaic generation has been surging among renewable generation in the past few years, thanks to the availability, affordability, technology maturity of the PV panels and the PV inverter in the general market. Unfortunately, quite often, the PV installations are connected to weak grids and may have been considered as the culprit of poor power quality affecting other loads in particular sensitive loads connected to the same point of common coupling (PCC). This paper is intended to demystify the renewable generation, and turns the negative perception into positive revelation of the superiority of PV generation to the power quality improvement in a microgrid system. The main objective of this work is to develop a control method for the PV inverter so that the power quality at the PCC will be improved under various disturbances. The method is to control the reactive current based on utilizing the grid current to counteract the negative impact of the disturbances. The proposed control method is verified in PSIM platform. Promising results have been obtained.

Second-Generation High-Temperature Superconductor Wires for the Electric Power Grid

Science.gov (United States)

Malozemoff, A. P.

2012-08-01

Superconductors offer major advantages for the electric power grid, including high current and power capacity, high efficiency arising from the lossless current flow, and a unique current-limiting functionality arising from a superconductor-to-resistive transition. These advantages can be brought to bear on equipment such as underground power cables, fault current limiters, rotating machinery, transformers, and energy storage. The first round of significant commercial-scale superconductor power-equipment demonstrations, carried out during the past decade, relied on a first-generation high-temperature superconductor (HTS) wire. However, during the past few years, with the recent commercial availability of high-performance second-generation HTS wires, power-equipment demonstrations have increasingly been carried out with these new wires, which bring important advantages. The foundation is being laid for commercial expansion of this important technology into the power grid.

Smart grid technologies in local electric grids

Science.gov (United States)

Lezhniuk, Petro D.; Pijarski, Paweł; Buslavets, Olga A.

2017-08-01

The research is devoted to the creation of favorable conditions for the integration of renewable sources of energy into electric grids, which were designed to be supplied from centralized generation at large electric power stations. Development of distributed generation in electric grids influences the conditions of their operation - conflict of interests arises. The possibility of optimal functioning of electric grids and renewable sources of energy, when complex criterion of the optimality is balance reliability of electric energy in local electric system and minimum losses of electric energy in it. Multilevel automated system for power flows control in electric grids by means of change of distributed generation of power is developed. Optimization of power flows is performed by local systems of automatic control of small hydropower stations and, if possible, solar power plants.

Modified Perfect Harmonics Cancellation Control of a Grid Interfaced SPV Power Generation

Science.gov (United States)

Singh, B.; Shahani, D. T.; Verma, A. K.

2015-03-01

This paper deals with a grid interfaced solar photo voltaic (SPV) power generating system with modified perfect harmonic cancellation (MPHC) control for power quality improvement in terms of mitigation of the current harmonics, power factor correction, control of point of common coupling (PCC) voltage with reactive power compensation and load balancing in a three phase distribution system. The proposed grid interfaced SPV system consists of a SPV array, a dc-dc boost converter and a voltage source converter (VSC) used for the compensation of other connected linear and nonlinear loads at PCC. The reference grid currents are estimated using MPHC method and control signals are derived by using pulse width modulation (PWM) current controller of VSC. The SPV power is fed to the common dc bus of VSC and dc-dc boost converter using maximum power point tracking (MPPT). The dc link voltage of VSC is regulated by using dc voltage proportional integral (PI) controller. The analysis of the proposed SPV power generating system is carried out under dc/ac short circuit and severe SPV-SX and SPV-TX intrusion.

An electrical betweenness approach for vulnerability assessment of power grids considering the capacity of generators and load

Science.gov (United States)

Wang, Kai; Zhang, Bu-han; Zhang, Zhe; Yin, Xiang-gen; Wang, Bo

2011-11-01

Most existing research on the vulnerability of power grids based on complex networks ignores the electrical characteristics and the capacity of generators and load. In this paper, the electrical betweenness is defined by considering the maximal demand of load and the capacity of generators in power grids. The loss of load, which reflects the ability of power grids to provide sufficient power to customers, is introduced to measure the vulnerability together with the size of the largest cluster. The simulation results of the IEEE-118 bus system and the Central China Power Grid show that the cumulative distributions of node electrical betweenness follow a power-law and that the nodes with high electrical betweenness play critical roles in both topological structure and power transmission of power grids. The results prove that the model proposed in this paper is effective for analyzing the vulnerability of power grids.

A Case for Dynamic Reverse-code Generation to Debug Non-deterministic Programs

Directory of Open Access Journals (Sweden)

Jooyong Yi

2013-09-01

Full Text Available Backtracking (i.e., reverse execution helps the user of a debugger to naturally think backwards along the execution path of a program, and thinking backwards makes it easy to locate the origin of a bug. So far backtracking has been implemented mostly by state saving or by checkpointing. These implementations, however, inherently do not scale. Meanwhile, a more recent backtracking method based on reverse-code generation seems promising because executing reverse code can restore the previous states of a program without state saving. In the literature, there can be found two methods that generate reverse code: (a static reverse-code generation that pre-generates reverse code through static analysis before starting a debugging session, and (b dynamic reverse-code generation that generates reverse code by applying dynamic analysis on the fly during a debugging session. In particular, we espoused the latter one in our previous work to accommodate non-determinism of a program caused by e.g., multi-threading. To demonstrate the usefulness of our dynamic reverse-code generation, this article presents a case study of various backtracking methods including ours. We compare the memory usage of various backtracking methods in a simple but nontrivial example, a bounded-buffer program. In the case of non-deterministic programs such as this bounded-buffer program, our dynamic reverse-code generation outperforms the existing backtracking methods in terms of memory efficiency.

A sparse grid based method for generative dimensionality reduction of high-dimensional data

Science.gov (United States)

Bohn, Bastian; Garcke, Jochen; Griebel, Michael

2016-03-01

Generative dimensionality reduction methods play an important role in machine learning applications because they construct an explicit mapping from a low-dimensional space to the high-dimensional data space. We discuss a general framework to describe generative dimensionality reduction methods, where the main focus lies on a regularized principal manifold learning variant. Since most generative dimensionality reduction algorithms exploit the representer theorem for reproducing kernel Hilbert spaces, their computational costs grow at least quadratically in the number n of data. Instead, we introduce a grid-based discretization approach which automatically scales just linearly in n. To circumvent the curse of dimensionality of full tensor product grids, we use the concept of sparse grids. Furthermore, in real-world applications, some embedding directions are usually more important than others and it is reasonable to refine the underlying discretization space only in these directions. To this end, we employ a dimension-adaptive algorithm which is based on the ANOVA (analysis of variance) decomposition of a function. In particular, the reconstruction error is used to measure the quality of an embedding. As an application, the study of large simulation data from an engineering application in the automotive industry (car crash simulation) is performed.

Parametric Geometry, Structured Grid Generation, and Initial Design Study for REST-Class Hypersonic Inlets

Science.gov (United States)

Ferlemann, Paul G.; Gollan, Rowan J.

2010-01-01

Computational design and analysis of three-dimensional hypersonic inlets with shape transition has been a significant challenge due to the complex geometry and grid required for three-dimensional viscous flow calculations. Currently, the design process utilizes an inviscid design tool to produce initial inlet shapes by streamline tracing through an axisymmetric compression field. However, the shape is defined by a large number of points rather than a continuous surface and lacks important features such as blunt leading edges. Therefore, a design system has been developed to parametrically construct true CAD geometry and link the topology of a structured grid to the geometry. The Adaptive Modeling Language (AML) constitutes the underlying framework that is used to build the geometry and grid topology. Parameterization of the CAD geometry allows the inlet shapes produced by the inviscid design tool to be generated, but also allows a great deal of flexibility to modify the shape to account for three-dimensional viscous effects. By linking the grid topology to the parametric geometry, the GridPro grid generation software can be used efficiently to produce a smooth hexahedral multiblock grid. To demonstrate the new capability, a matrix of inlets were designed by varying four geometry parameters in the inviscid design tool. The goals of the initial design study were to explore inviscid design tool geometry variations with a three-dimensional analysis approach, demonstrate a solution rate which would enable the use of high-fidelity viscous three-dimensional CFD in future design efforts, process the results for important performance parameters, and perform a sample optimization.

Coupling an analytical description of anti-scatter grids with simulation software of radiographic systems using Monte Carlo code

International Nuclear Information System (INIS)

Rinkel, J.; Dinten, J.M.; Tabary, J.

2004-01-01

The use of focused anti-scatter grids on digital radiographic systems with two-dimensional detectors produces acquisitions with a decreased scatter to primary ratio and thus improved contrast and resolution. Simulation software is of great interest in optimizing grid configuration according to a specific application. Classical simulators are based on complete detailed geometric descriptions of the grid. They are accurate but very time consuming since they use Monte Carlo code to simulate scatter within the high-frequency grids. We propose a new practical method which couples an analytical simulation of the grid interaction with a radiographic system simulation program. First, a two dimensional matrix of probability depending on the grid is created offline, in which the first dimension represents the angle of impact with respect to the normal to the grid lines and the other the energy of the photon. This matrix of probability is then used by the Monte Carlo simulation software in order to provide the final scattered flux image. To evaluate the gain of CPU time, we define the increasing factor as the increase of CPU time of the simulation with as opposed to without the grid. Increasing factors were calculated with the new model and with classical methods representing the grid with its CAD model as part of the object. With the new method, increasing factors are shorter by one to two orders of magnitude compared with the second one. These results were obtained with a difference in calculated scatter of less than five percent between the new and the classical method. (authors)

Perspectives on the development of next generation reactor systems safety analysis codes

International Nuclear Information System (INIS)

Zhang, H.

2015-01-01

'Full text:' Existing reactor system analysis codes, such as RELAP5-3D and TRAC, have gained worldwide success in supporting reactor safety analyses, as well as design and licensing of new reactors. These codes are important assets to the nuclear engineering research community, as well as to the nuclear industry. However, most of these codes were originally developed during the 1970s', and it becomes necessary to develop next-generation reactor system analysis codes for several reasons. Firstly, as new reactor designs emerge, there are new challenges emerging in numerical simulations of reactor systems such as long lasting transients and multi-physics phenomena. These new requirements are beyond the range of applicability of the existing system analysis codes. Advanced modeling and numerical methods must be taken into consideration to improve the existing capabilities. Secondly, by developing next-generation reactor system analysis codes, the knowledge (know how) in two phase flow modeling and the highly complex constitutive models will be transferred to the young generation of nuclear engineers. And thirdly, all computer codes have limited shelf life. It becomes less and less cost-effective to maintain a legacy code, due to the fast change of computer hardware and software environment. There are several critical perspectives in terms of developing next-generation reactor system analysis codes: 1) The success of the next-generation codes must be built upon the success of the existing codes. The knowledge of the existing codes, not just simply the manuals and codes, but knowing why and how, must be transferred to the next-generation codes. The next-generation codes should encompass the capability of the existing codes. The shortcomings of existing codes should be identified, understood, and properly categorized, for example into model deficiencies or numerical method deficiencies. 2) State-of-the-art models and numerical methods must be considered to

Perspectives on the development of next generation reactor systems safety analysis codes

Energy Technology Data Exchange (ETDEWEB)

Zhang, H., E-mail: Hongbin.Zhang@inl.gov [Idaho National Laboratory, Idaho Falls, ID (United States)

2015-07-01

'Full text:' Existing reactor system analysis codes, such as RELAP5-3D and TRAC, have gained worldwide success in supporting reactor safety analyses, as well as design and licensing of new reactors. These codes are important assets to the nuclear engineering research community, as well as to the nuclear industry. However, most of these codes were originally developed during the 1970s', and it becomes necessary to develop next-generation reactor system analysis codes for several reasons. Firstly, as new reactor designs emerge, there are new challenges emerging in numerical simulations of reactor systems such as long lasting transients and multi-physics phenomena. These new requirements are beyond the range of applicability of the existing system analysis codes. Advanced modeling and numerical methods must be taken into consideration to improve the existing capabilities. Secondly, by developing next-generation reactor system analysis codes, the knowledge (know how) in two phase flow modeling and the highly complex constitutive models will be transferred to the young generation of nuclear engineers. And thirdly, all computer codes have limited shelf life. It becomes less and less cost-effective to maintain a legacy code, due to the fast change of computer hardware and software environment. There are several critical perspectives in terms of developing next-generation reactor system analysis codes: 1) The success of the next-generation codes must be built upon the success of the existing codes. The knowledge of the existing codes, not just simply the manuals and codes, but knowing why and how, must be transferred to the next-generation codes. The next-generation codes should encompass the capability of the existing codes. The shortcomings of existing codes should be identified, understood, and properly categorized, for example into model deficiencies or numerical method deficiencies. 2) State-of-the-art models and numerical methods must be considered to

Optimization of the cooling circuit and thermo-mechanical analysis for the extraction grid of ELISE

International Nuclear Information System (INIS)

Nocentini, R.; Gutser, R.; Heinemann, B.; Froeschle, M.; Riedl, R.

2011-01-01

The NNBI test facility ELISE ('Extraction from a Large Ion Source Experiment'), presently under construction at IPP, will have an extraction area with the same width and half the height of the ITER source, acceleration up to 60 kV, for 10 s, every 180 s, and plasma generation up to 1 h. Electrons are co-extracted from the ion source. Suppression magnets in the extraction grid deflect the electrons onto the extraction grid surface. For 30 mA/cm 2 extracted electron current density and 10 kV extraction voltage, localized power density is in the order of 39 MW/m 2 near the grid apertures and a total heat load of 150 kW is deposited onto each extraction grid segment. Heat removal is provided by a water circuit inside the grid. For ELISE, a new cooling circuit has been developed to provide a more reliable operation. The optimization of the cooling circuit and the thermo-mechanical analysis of the extraction grid of ELISE, considering maximum grid temperature, mechanical stresses and grid deformation, has been performed using the codes KOBRA3, TrajAn, the ANSYS finite element package and the fluid dynamics code CFX.

pix2code: Generating Code from a Graphical User Interface Screenshot

OpenAIRE

Beltramelli, Tony

2017-01-01

Transforming a graphical user interface screenshot created by a designer into computer code is a typical task conducted by a developer in order to build customized software, websites, and mobile applications. In this paper, we show that deep learning methods can be leveraged to train a model end-to-end to automatically generate code from a single input image with over 77% of accuracy for three different platforms (i.e. iOS, Android and web-based technologies).

Synchronization in single-phase grid-connected photovoltaic systems under grid faults

DEFF Research Database (Denmark)

Yang, Yongheng; Blaabjerg, Frede

2012-01-01

The highly increasing penetration of single-phase photovoltaic (PV) systems pushes the grid requirements related to the integration of PV power systems to be updated. These upcoming regulations are expected to direct the grid-connected renewable generators to support the grid operation and stabil......The highly increasing penetration of single-phase photovoltaic (PV) systems pushes the grid requirements related to the integration of PV power systems to be updated. These upcoming regulations are expected to direct the grid-connected renewable generators to support the grid operation...

Gene-Auto: Automatic Software Code Generation for Real-Time Embedded Systems

Science.gov (United States)

Rugina, A.-E.; Thomas, D.; Olive, X.; Veran, G.

2008-08-01

This paper gives an overview of the Gene-Auto ITEA European project, which aims at building a qualified C code generator from mathematical models under Matlab-Simulink and Scilab-Scicos. The project is driven by major European industry partners, active in the real-time embedded systems domains. The Gene- Auto code generator will significantly improve the current development processes in such domains by shortening the time to market and by guaranteeing the quality of the generated code through the use of formal methods. The first version of the Gene-Auto code generator has already been released and has gone thought a validation phase on real-life case studies defined by each project partner. The validation results are taken into account in the implementation of the second version of the code generator. The partners aim at introducing the Gene-Auto results into industrial development by 2010.

Conducting grids to stabilize MHD generator plasmas against ionization instabilities

International Nuclear Information System (INIS)

Veefkind, A.

1972-09-01

Ionization instabilities in MHD generators may be suppressed by the use of grids that short circuit the AC electric field component corresponding to the direction of maximum growth. An analysis of the influence of the corresponding boundary conditions has been performed in order to obtain more quantitative information about the stabilizing effect of this system

MUXS: a code to generate multigroup cross sections for sputtering calculations

International Nuclear Information System (INIS)

Hoffman, T.J.; Robinson, M.T.; Dodds, H.L. Jr.

1982-10-01

This report documents MUXS, a computer code to generate multigroup cross sections for charged particle transport problems. Cross sections generated by MUXS can be used in many multigroup transport codes, with minor modifications to these codes, to calculate sputtering yields, reflection coefficients, penetration distances, etc

(U) Ristra Next Generation Code Report

Energy Technology Data Exchange (ETDEWEB)

Hungerford, Aimee L. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Daniel, David John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2017-09-22

LANL’s Weapons Physics management (ADX) and ASC program office have defined a strategy for exascale-class application codes that follows two supportive, and mutually risk-mitigating paths: evolution for established codes (with a strong pedigree within the user community) based upon existing programming paradigms (MPI+X); and Ristra (formerly known as NGC), a high-risk/high-reward push for a next-generation multi-physics, multi-scale simulation toolkit based on emerging advanced programming systems (with an initial focus on data-flow task-based models exemplified by Legion [5]). Development along these paths is supported by the ATDM, IC, and CSSE elements of the ASC program, with the resulting codes forming a common ecosystem, and with algorithm and code exchange between them anticipated. Furthermore, solution of some of the more challenging problems of the future will require a federation of codes working together, using established-pedigree codes in partnership with new capabilities as they come on line. The role of Ristra as the high-risk/high-reward path for LANL’s codes is fully consistent with its role in the Advanced Technology Development and Mitigation (ATDM) sub-program of ASC (see Appendix C), in particular its emphasis on evolving ASC capabilities through novel programming models and data management technologies.

Compensating customer-generators: a taxonomy describing methods of compensating customer-generators for electricity supplied to the grid

International Nuclear Information System (INIS)

Hughes, Larry; Bell, Jeff

2006-01-01

The increasing popularity of on-site power generation is driving the demand for methods to compensate customer-generators that supply electricity to the grid. Although many practices exist for providing such compensation, confusion surrounds the terms often used to describe such practices (notably, net metering and net billing). To help clarify this situation, the following paper proposes a taxonomy that distinguishes between 16 distinct compensation practices

On the integration of wind generators on weak grids and island grids

International Nuclear Information System (INIS)

Laverdure, N.

2005-12-01

Wind energy is now an energy that can not be ignored. Because of intrinsic characteristics (scattered primary energy, generators with different technologies, use of power electronics interface), wind energy system integration in distribution grids leads to real problems in terms of impacts. With recent standard changes, it is necessary to study the possibilities of each technology of wind turbines to answer or not to these new constraints. This PhD thesis focuses on a comparison of the main present wind turbines concerning three points of discussion: energy quality, fault ride through, ancillary services (voltage and frequency). It insists on the possibilities in terms of control laws for variable speed wind turbines. (author)

Economic Power Dispatch of Distributed Generators in a Grid-Connected Microgrid

DEFF Research Database (Denmark)

Hernández, Adriana Carolina Luna; Aldana, Nelson Leonardo Diaz; Andrade, Fabio

2015-01-01

Grid-connected microgrids with storage systems are reliable configurations for critical loads which can not tolerate interruptions of energy supply. In such cases, some of the energy resources should be scheduled in order to coordinate optimally the power generation according to a defined objective...

Geometry Laboratory (GEOLAB) surface modeling and grid generation technology and services

Science.gov (United States)

Kerr, Patricia A.; Smith, Robert E.; Posenau, Mary-Anne K.

1995-01-01

The facilities and services of the GEOmetry LABoratory (GEOLAB) at the NASA Langley Research Center are described. Included in this description are the laboratory functions, the surface modeling and grid generation technologies used in the laboratory, and examples of the tasks performed in the laboratory.

Impact of Converter Interfaced Generation and Load on Grid Performance

Science.gov (United States)

Ramasubramanian, Deepak

Alternate sources of energy such as wind, solar photovoltaic and fuel cells are coupled to the power grid with the help of solid state converters. Continued deregulation of the power sector coupled with favorable government incentives has resulted in the rapid growth of renewable energy sources connected to the distribution system at a voltage level of 34.5kV or below. Of late, many utilities are also investing in these alternate sources of energy with the point of interconnection with the power grid being at the transmission level. These converter interfaced generation along with their associated control have the ability to provide the advantage of fast control of frequency, voltage, active, and reactive power. However, their ability to provide stability in a large system is yet to be investigated in detail. This is the primary objective of this research. In the future, along with an increase in the percentage of converter interfaced renewable energy sources connected to the transmission network, there exists a possibility of even connecting synchronous machines to the grid through converters. Thus, all sources of energy can be expected to be coupled to the grid through converters. The control and operation of such a grid will be unlike anything that has been encountered till now. In this dissertation, the operation and behavior of such a grid will be investigated. The first step in such an analysis will be to build an accurate and simple mathematical model to represent the corresponding components in commercial software. Once this bridge has been crossed, conventional machines will be replaced with their solid state interfaced counterparts in a phased manner. At each stage, attention will be devoted to the control of these sources and also on the stability performance of the large power system. This dissertation addresses various concerns regarding the control and operation of a futuristic power grid. In addition, this dissertation also aims to address the issue

Grid-generated He II turbulence in a finite channel - experiment

International Nuclear Information System (INIS)

Niemela, J.J.; Skrbek, L.; Stalp, S.R.

2001-01-01

We present experimental data on decaying turbulence, generated by towing a grid through a stationary sample of He II. We describe in detail the experimental apparatus and physical principles that allow observation of up to six orders of magnitude of decaying vortex line density over three orders of magnitude in time using the second sound attenuation technique. (orig.)

Adaptive Hysteresis Band Current Control (AHB) with PLL of Grid Side Converter-Based Wind Power Generation System

DEFF Research Database (Denmark)

Guo, Yougui; Zeng, Ping; Li, Lijuan

2011-01-01

Adaptive hysteresis band current control(AHB CC) is used to control the three-phase grid currents by means of grid side converter in wind power generation system in this paper. AHB has reached the good purpose with PLL (Lock phase loop). First the mathematical models of each part are given......, transformer and grid, and control parts, etc. The simulation results have verified that the control strategy is feasible to fit for control of gird currents, active power, reactive power and DC-link voltage in wind power generation system....

Renewable energy technology for off-grid power generation solar hybrid system

International Nuclear Information System (INIS)

Mohd Azhar Abd Rahman

2006-01-01

Off-grid power generation is meant to supply remote or rural area, where grid connection is almost impossible in terms of cost and geography, such as island, aborigine's villages, and areas where nature preservation is concern. Harnessing an abundance renewable energy sources using versatile hybrid power systems can offer the best, least-cost alternative solution for extending modern energy services to remote and isolated communities. The conventional method for off-grid power generation is using diesel generator with a renewable energy (RE) technology utilizing solar photovoltaic, wind, biomass, biogas and/or mini/micro hydro. A hybrid technology is a combination of multiple source of energy; such as RE and diesel generator and may also include energy storage such as battery. In our design, the concept of solar hybrid system is a combination of solar with diesel genset and battery as an energy storage. The main objective of the system are to reduce the cost of operation and maintenance, cost of logistic and carbon dioxide (CO 2 ) emission. The operational concept of solar hybrid system is that solar will be the first choice of supplying load and excess energy produced will be stored in battery. Genset will be a secondary source of energy. The system is controlled by a microprocessor-based controlled to manage the energy supplied and load demand. The solar hybrid system consists of one or two diesel generator with electronic control system, lead-acid battery system, solar PV, inverter module and system controller with remote monitoring capability. The benefits of solar hybrid system are: Improved reliability, Improved energy services, reduced emissions and pollution, provide continuous power supply, increased operational life, reduced cost, and more efficient use of power. Currently, such system has been installed at Middle and Top Station of Langkawi Cable Car, Langkawi and Aborigines Village Kg Denai, Rompin, Pahang. The technology is considered new in Malaysia

Fulfilment of Grid Code Obligations by Large Offshore Wind Farms Clusters Connected via HVDC Corridors

OpenAIRE

Attya, A.B.; Anaya-Lara, Olimpo; Ledesma, P.; Svendsen, Harald Georg

2016-01-01

- The foreseen high penetration levels of wind power will force the systems operators to apply restrictive constraints on wind power plants. The ability of offshore wind clusters, which are connected via HVDC, to fulfill the grid codes, especially those related to voltage stability is investigated. This came in the frame of a project to develop an integrated and practical tool to design offshore wind clusters (EERA-DTOC). The applied case studies examine the system stability during and aft...

Unbalanced voltage control of virtual synchronous generator in isolated micro-grid

Science.gov (United States)

Cao, Y. Z.; Wang, H. N.; Chen, B.

2017-06-01

Virtual synchronous generator (VSG) control is recommended to stabilize the voltage and frequency in isolated micro-grid. However, common VSG control is challenged by widely used unbalance loads, and the linked unbalance voltage problem worsens the power quality of the micro-grid. In this paper, the mathematical model of VSG was presented. Based on the analysis of positive- and negative-sequence equivalent circuit of VSG, an approach was proposed to eliminate the negative-sequence voltage of VSG with unbalance loads. Delay cancellation method and PI controller were utilized to identify and suppress the negative-sequence voltages. Simulation results verify the feasibility of proposed control strategy.

Solar Energy Grid Integration Systems (SEGIS): adding functionality while maintaining reliability and economics

Science.gov (United States)

Bower, Ward

2011-09-01

An overview of the activities and progress made during the US DOE Solar Energy Grid Integration Systems (SEGIS) solicitation, while maintaining reliability and economics is provided. The SEGIS R&D opened pathways for interconnecting PV systems to intelligent utility grids and micro-grids of the future. In addition to new capabilities are "value added" features. The new hardware designs resulted in smaller, less material-intensive products that are being viewed by utilities as enabling dispatchable generation and not just unpredictable negative loads. The technical solutions enable "advanced integrated system" concepts and "smart grid" processes to move forward in a faster and focused manner. The advanced integrated inverters/controllers can now incorporate energy management functionality, intelligent electrical grid support features and a multiplicity of communication technologies. Portals for energy flow and two-way communications have been implemented. SEGIS hardware was developed for the utility grid of today, which was designed for one-way power flow, for intermediate grid scenarios, AND for the grid of tomorrow, which will seamlessly accommodate managed two-way power flows as required by large-scale deployment of solar and other distributed generation. The SEGIS hardware and control developed for today meets existing standards and codes AND provides for future connections to a "smart grid" mode that enables utility control and optimized performance.

INGEN: a general-purpose mesh generator for finite element codes

International Nuclear Information System (INIS)

Cook, W.A.

1979-05-01

INGEN is a general-purpose mesh generator for two- and three-dimensional finite element codes. The basic parts of the code are surface and three-dimensional region generators that use linear-blending interpolation formulas. These generators are based on an i, j, k index scheme that is used to number nodal points, construct elements, and develop displacement and traction boundary conditions. This code can generate truss elements (2 modal points); plane stress, plane strain, and axisymmetry two-dimensional continuum elements (4 to 8 nodal points); plate elements (4 to 8 nodal points); and three-dimensional continuum elements (8 to 21 nodal points). The traction loads generated are consistent with the element generated. The expansion--contraction option is of special interest. This option makes it possible to change an existing mesh such that some regions are refined and others are made coarser than the original mesh. 9 figures

CFD code verification and the method of manufactured solutions

International Nuclear Information System (INIS)

Pelletier, D.; Roache, P.J.

2002-01-01

This paper presents the Method of Manufactured Solutions (MMS) for CFD code verification. The MMS provides benchmark solutions for direct evaluation of the solution error. The best benchmarks are exact analytical solutions with sufficiently complex solution structure to ensure that all terms of the differential equations are exercised in the simulation. The MMS provides a straight forward and general procedure for generating such solutions. When used with systematic grid refinement studies, which are remarkably sensitive, the MMS provides strong code verification with a theorem-like quality. The MMS is first presented on simple 1-D examples. Manufactured solutions for more complex problems are then presented with sample results from grid convergence studies. (author)

Aspects of a generic photovoltaic model examined under the German grid code for medium voltage

Energy Technology Data Exchange (ETDEWEB)

Theologitis, Ioannis-Thomas; Troester, Eckehard; Ackermann, Thomas [Energynautics GmbH, Langen (Germany)

2011-07-01

The increasing peneration of photovoltaic power systems into the power grid has attached attention to the issue of ensuring the smooth absorbance of the solar energy, while securing the normal and steady operation of the grid as well. Nowadays, the PV systems must meet a number of technical requirements to address this issue. This paper investigates a generic grid-connected photovoltaic model that was developed by DIgSILENT and is part of the library in the new version of PowerFactory v.14.1 software that is used in this study. The model has a nominal rated peak power of 0.5 MVA and a designed power factor cos{phi}0.95. The study focuses on the description of the model, its control system and its ability to reflect important requirements that a grid-connected PV system should have by January 2011 according to the German grid code for medium voltage. The model undergoes various simulations. Static voltage support, active power control and dynamic voltage support - Fault Ride Through (FRT) is examined. The results show that the generic model is capable for active power reduction under over-frequency occasions and FRT behavior in cases of voltage dips. The reactive power control that is added in the model improves the control system and makes the model capable for static voltage support in sudden active power injection changes at the point of common coupling. Beside the simplifications and shortcomings of this generic model, basic requirements of the modern PV systems can be addressed. Further improvements could make it more complete and applicable for more detailed studies. (orig.)

Application of DC-AC Hybrid Grid and Solar Photovoltaic Generation with Battery Storage Using Smart Grid

Directory of Open Access Journals (Sweden)

Shoaib Rauf

2017-01-01

Full Text Available Smart grid for the past few years has been the prime focus of research in power systems. The aim is to eliminate load shedding and problematic blackout conditions, further offering cheap and continuous supply of electricity for both large and small consumers. Another benefit is to integrate renewable energy resources with existing dump grid in more efficient and cost-effective manner. In past few years, growing demand for sustainable energy increases the consumption of solar PV. Since generation from solar PV is in DC and most of the appliances at home could be operated on DC, AC-DC hybrid distribution system with energy management system is proposed in this paper. EMS helps to shift or control the auxiliary load and compel the users to operate specific load at certain time slots. These techniques further help to manage the excessive load during peak and off peak hours. It demonstrates the practical implementation of DC-AC network with integration of solar PV and battery storage with existing infrastructure. The results show a remarkable improvement using hybrid AC-DC framework in terms of reliability and efficiency. All this functioning together enhances the overall efficiency; hence, a secure, economical, reliable, and intelligent system leads to a smart grid.

Analysis and MPPT control of a wind-driven three-phase induction generator feeding single-phase utility grid

Directory of Open Access Journals (Sweden)

Krishnan Arthishri

2017-05-01

Full Text Available In this study, a three-phase diode bridge rectifier and a single-phase voltage source inverter topology has been proposed for feeding single-phase utility grid employing a three-phase induction generator fed from wind energy. A self-excited induction generator configuration has been chosen for wide speed operation of wind turbine system, which gives the scope for extracting maximum power available in the wind. In addition to maximum power point tracking (MPPT, the generator can be loaded to its rated capacity for feeding single-phase utility grid using a three-phase induction machine, whereas it is not possible with existing configurations because of the absence of power converters. For the proposed system, MPPT algorithm has been devised by continuously monitoring the grid current and a proportional resonant controller has been employed for grid synchronisation of voltage source inverter with single-phase grid. A MATLAB/Simulink model of the proposed system has been developed to ascertain its successful working by predetermining the overall performance characteristics. The present proposal has also been tested with sag, swell and distortion in the grid voltage. The control strategy has been implemented using field programmable gate array (FPGA controller with modularised programming approach. The efficacy of the system has been demonstrated with the results obtained from an experimental set-up in the laboratory.

Generation of Efficient High-Level Hardware Code from Dataflow Programs

OpenAIRE

Siret , Nicolas; Wipliez , Matthieu; Nezan , Jean François; Palumbo , Francesca

2012-01-01

High-level synthesis (HLS) aims at reducing the time-to-market by providing an automated design process that interprets and compiles high-level abstraction programs into hardware. However, HLS tools still face limitations regarding the performance of the generated code, due to the difficulties of compiling input imperative languages into efficient hardware code. Moreover the hardware code generated by the HLS tools is usually target-dependant and at a low level of abstraction (i.e. gate-level...

Inflow turbulence generation for eddy-resolving simulations of turbomachinery flows

OpenAIRE

Arolla, Sunil K.

2014-01-01

A simple variant of recycling and rescaling method to generate inflow turbulence using unstructured grid CFD codes is presented. The method has been validated on large eddy simulation of spatially developing flat plate turbulent boundary layer. The proposed rescaling algorithm is based on the momentum thickness which is more robust and essentially obviates the need of finding the edge of the turbulent boundary layer in unstructured grid codes. Extension of this algorithm to hybrid RANS/LES ty...

A Vertical-Axis Off-Grid Squirrel-Cage Induction Generator Wind Power System

Directory of Open Access Journals (Sweden)

Peifeng Xu

2016-10-01

Full Text Available In order to broaden the limited utilization range of wind power and improve the charging and discharging control performance of the storage battery in traditional small wind power generation systems, a wind power system based on a vertical-axis off-grid induction generator is proposed in this paper. The induction generator not only can run in a wide wind speed range but can also assist the vertical-axis wind turbine to realize self-starting at low wind speed. Combined with the maximum power point tracking method, the slip frequency control strategy is employed to regulate the pulse width modulation (PWM converter to control the output power of the proposed system when the wind speed and load change. The charge and discharge of the storage battery is realized by the segmented current-limiting control strategy by means of an electric power unloader device connected to the DC bus. All these implement a balanced and stable operation of the proposed power generation system. The experimental research on the 5.5 kW prototype system is developed, and the corresponding results verify the correctness and feasibility of the system design and control strategy. Some comparison experiments with a magnetic suspension permanent magnet synchronous generator (PMSG demonstrate the application prospect of the proposed vertical-axis off-grid induction generator wind power system.

Statistics for PV, wind and biomass generators and their impact on distribution grid planning

NARCIS (Netherlands)

Nykamp, Stefan; Molderink, Albert; Hurink, Johann L.; Smit, Gerardus Johannes Maria

2012-01-01

The integration of renewable energy generation leads to major challenges for distribution grid operators. When the feed-in of photovoltaic (PV), biomass and wind generators exceed significantly the local consumption, large investments are needed. To improve the knowledge on the interaction between

gCSP occam Code Generation for RMoX

NARCIS (Netherlands)

Groothuis, M.A.; Liet, Geert K.; Broenink, Johannes F.; Roebbers, H.W.; Sunter, J.P.E.; Welch, P.H.; Wood, D.C.

2005-01-01

gCSP is a graphical tool for creating and editing CSP diagrams. gCSP is used in our labs to generate the embedded software framework for our control systems. As a further extension to our gCSP tool, an occam code generator has been constructed. Generating occam from CSP diagrams gives opportunities

Improved diffusion coefficients generated from Monte Carlo codes

International Nuclear Information System (INIS)

Herman, B. R.; Forget, B.; Smith, K.; Aviles, B. N.

2013-01-01

Monte Carlo codes are becoming more widely used for reactor analysis. Some of these applications involve the generation of diffusion theory parameters including macroscopic cross sections and diffusion coefficients. Two approximations used to generate diffusion coefficients are assessed using the Monte Carlo code MC21. The first is the method of homogenization; whether to weight either fine-group transport cross sections or fine-group diffusion coefficients when collapsing to few-group diffusion coefficients. The second is a fundamental approximation made to the energy-dependent P1 equations to derive the energy-dependent diffusion equations. Standard Monte Carlo codes usually generate a flux-weighted transport cross section with no correction to the diffusion approximation. Results indicate that this causes noticeable tilting in reconstructed pin powers in simple test lattices with L2 norm error of 3.6%. This error is reduced significantly to 0.27% when weighting fine-group diffusion coefficients by the flux and applying a correction to the diffusion approximation. Noticeable tilting in reconstructed fluxes and pin powers was reduced when applying these corrections. (authors)

Distributed voltage control coordination between renewable generation plants in MV distribution grids

DEFF Research Database (Denmark)

Petersen, Lennart; Iov, Florin

2017-01-01

This study focuses on distributed voltage control coordination between renewable generation plants in medium-voltage distribution grids (DGs). A distributed offline coordination concept has been defined in a previous publication, leading to satisfactory voltage regulation in the DG. However, here...

Forced circulation type steam generator simulation code: HT4

International Nuclear Information System (INIS)

Okamoto, Masaharu; Tadokoro, Yoshihiro

1982-08-01

The purpose of this code is a understanding of dynamic characteristics of the steam generator, which is a component of High-temperature Heat Transfer Components Test Unit. This unit is a number 4th test section of Helium Engineering Demonstration Loop (HENDEL). Features of this report are as follows, modeling of the steam generator, a basic relationship for the continuity equation, numerical analysis techniques of a non-linear simultaneous equation and computer graphics output techniques. Forced circulation type steam generator with strait tubes and horizontal cut baffles, applied in this code, have be designed at the Over All System Design of the VHTRex. The code is for use with JAERI's digital computer FACOM M200. About 1.5 sec required for each time step reiteration, then about 40 sec cpu time required for a standard problem. (author)

Analysis of visual coding variables on CRT generated displays

International Nuclear Information System (INIS)

Blackman, H.S.; Gilmore, W.E.

1985-01-01

Cathode ray tube generated safety parameter display systems in a nuclear power plant control room situation have been found to be improved in effectiveness when color coding is employed. Research has indicated strong support for graphic coding techniques particularly in redundant coding schemes. In addition, findings on pictographs, as applied in coding schemes, indicate the need for careful application and for further research in the development of a standardized set of symbols

Simulation of ROCOM Experiment using CUPID Code

Energy Technology Data Exchange (ETDEWEB)

Cho, Yun Je; Lee, Jae Ryong; Yoon, Han Young [KAERI, Daejeon (Korea, Republic of)

2016-10-15

KAERI has developed CUPID, which is a three dimensional thermal hydraulics code for the transient analysis of two-phase flows in nuclear reactor components. To validate the capability of CUPID for simulation of multi-dimensional flow mixing behavior, ROCOM (ROssenforf COolant Mixing) test was simulated. ROCOM test has been conducted in the OECD PKL2 Project to investigate in more detail the thermal hydraulic behavior inside the RPV. Thus far, many researchers used the ROCOM data to validate the CFD code capability of thermal mixing behavior. In this study, a hybrid grid was generated using SALOME software and the ROCOM simulation was performed using CUPID. In addition, the effect of turbulence model was also investigated. Test ROCOM 2.1 and 1.2 cases were simulated using the CUPID code. It was shown that CUPID had capabilities to properly simulate the thermal mixing behavior in the case where the cold water is injected asymmetrically. As the result of calculations, it was found that the mixing efficiency in the downcomer and lower plenum was varied according to the turbulence model. In particular, the calculation results showed that the low Reynolds number turbulence model resulted in good agreement with the experimental data. The further works may involve the finer grid generation and the test of other turbulence models.

Code Generation with Templates

CERN Document Server

Arnoldus, Jeroen; Serebrenik, A

2012-01-01

Templates are used to generate all kinds of text, including computer code. The last decade, the use of templates gained a lot of popularity due to the increase of dynamic web applications. Templates are a tool for programmers, and implementations of template engines are most times based on practical experience rather than based on a theoretical background. This book reveals the mathematical background of templates and shows interesting findings for improving the practical use of templates. First, a framework to determine the necessary computational power for the template metalanguage is presen

Automatic ID heat load generation in ANSYS code

International Nuclear Information System (INIS)

Wang, Zhibi.

1992-01-01

Detailed power density profiles are critical in the execution of a thermal analysis using a finite element (FE) code such as ANSYS. Unfortunately, as yet there is no easy way to directly input the precise power profiles into ANSYS. A straight-forward way to do this is to hand-calculate the power of each node or element and then type the data into the code. Every time a change is made to the FE model, the data must be recalculated and reentered. One way to solve this problem is to generate a set of discrete data, using another code such as PHOTON2, and curve-fit the data. Using curve-fitted formulae has several disadvantages. It is time consuming because of the need to run a second code for generation of the data, curve-fitting, and doing the data check, etc. Additionally, because there is no generality for different beamlines or different parameters, the above work must be repeated for each case. And, errors in the power profiles due to curve-fitting result in errors in the analysis. To solve the problem once and for all and with the capability to apply to any insertion device (ID), a program for ED power profile was written in ANSYS Parametric Design Language (APDL). This program is implemented as an ANSYS command with input parameters of peak magnetic field, deflection parameter, length of ID, and distance from the source. Once the command is issued, all the heat load will be automatically generated by the code

Code generation of RHIC accelerator device objects

International Nuclear Information System (INIS)

Olsen, R.H.; Hoff, L.; Clifford, T.

1995-01-01

A RHIC Accelerator Device Object is an abstraction which provides a software view of a collection of collider control points known as parameters. A grammar has been defined which allows these parameters, along with code describing methods for acquiring and modifying them, to be specified efficiently in compact definition files. These definition files are processed to produce C++ source code. This source code is compiled to produce an object file which can be loaded into a front end computer. Each loaded object serves as an Accelerator Device Object class definition. The collider will be controlled by applications which set and get the parameters in instances of these classes using a suite of interface routines. Significant features of the grammar are described with details about the generated C++ code

Controllable Grid Interface for Testing Ancillary Service Controls and Fault Performance of Utility-Scale Wind Power Generation: Preprint

Energy Technology Data Exchange (ETDEWEB)

Gevorgian, Vahan; Koralewicz, Przemyslaw; Wallen, Robb; Muljadi, Eduard

2017-02-01

The rapid expansion of wind power has led many transmission system operators to demand modern wind power plants to comply with strict interconnection requirements. Such requirements involve various aspects of wind power plant operation, including fault ride-through and power quality performance as well as the provision of ancillary services to enhance grid reliability. During recent years, the National Renewable Energy Laboratory (NREL) of the U.S. Department of Energy has developed a new, groundbreaking testing apparatus and methodology to test and demonstrate many existing and future advanced controls for wind generation (and other renewable generation technologies) on the multimegawatt scale and medium-voltage levels. This paper describes the capabilities and control features of NREL's 7-MVA power electronic grid simulator (also called a controllable grid interface, or CGI) that enables testing many active and reactive power control features of modern wind turbine generators -- including inertial response, primary and secondary frequency responses, and voltage regulation -- under a controlled, medium-voltage grid environment. In particular, this paper focuses on the specifics of testing the balanced and unbalanced fault ride-through characteristics of wind turbine generators under simulated strong and weak medium-voltage grid conditions. In addition, this paper provides insights on the power hardware-in-the-loop feature implemented in the CGI to emulate (in real time) the conditions that might exist in various types of electric power systems under normal operations and/or contingency scenarios. Using actual test examples and simulation results, this paper describes the value of CGI as an ultimate modeling validation tool for all types of 'grid-friendly' controls by wind generation.

Multi-pole permanent magnet synchronous generator wind turbines' grid support capability in uninterrupted operation during grid faults

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Michalke, G.

2009-01-01

Emphasis in this paper is on the fault ride-through and grid support capabilities of multi-pole permanent magnet synchronous generator (PMSG) wind turbines with a full-scale frequency converter. These wind turbines are announced to be very attractive, especially for large offshore wind farms...... and discussed by means of simulations with the use of a transmission power system generic model developed and delivered by the Danish Transmission System Operator Energinet.dk. The simulation results show how a PMSG wind farm equipped with an additional voltage control can help a nearby active stall wind farm....... A control strategy is presented, which enhances the fault ride-through and voltage support capability of such wind turbines during grid faults. Its design has special focus on power converters' protection and voltage control aspects. The performance of the presented control strategy is assessed...

Artificial Bee Colony Algorithm for Transient Performance Augmentation of Grid Connected Distributed Generation

Science.gov (United States)

Chatterjee, A.; Ghoshal, S. P.; Mukherjee, V.

In this paper, a conventional thermal power system equipped with automatic voltage regulator, IEEE type dual input power system stabilizer (PSS) PSS3B and integral controlled automatic generation control loop is considered. A distributed generation (DG) system consisting of aqua electrolyzer, photovoltaic cells, diesel engine generator, and some other energy storage devices like flywheel energy storage system and battery energy storage system is modeled. This hybrid distributed system is connected to the grid. While integrating this DG with the onventional thermal power system, improved transient performance is noticed. Further improvement in the transient performance of this grid connected DG is observed with the usage of superconducting magnetic energy storage device. The different tunable parameters of the proposed hybrid power system model are optimized by artificial bee colony (ABC) algorithm. The optimal solutions offered by the ABC algorithm are compared with those offered by genetic algorithm (GA). It is also revealed that the optimizing performance of the ABC is better than the GA for this specific application.

Development of stable Grid service at the next generation system of KEKCC

Science.gov (United States)

Nakamura, T.; Iwai, G.; Matsunaga, H.; Murakami, K.; Sasaki, T.; Suzuki, S.; Takase, W.

2017-10-01

A lot of experiments in the field of accelerator based science are actively running at High Energy Accelerator Research Organization (KEK) by using SuperKEKB and J-PARC accelerator in Japan. In these days at KEK, the computing demand from the various experiments for the data processing, analysis, and MC simulation is monotonically increasing. It is not only for the case with high-energy experiments, the computing requirement from the hadron and neutrino experiments and some projects of astro-particle physics is also rapidly increasing due to the very high precision measurement. Under this situation, several projects, Belle II, T2K, ILC and KAGRA experiments supported by KEK are going to utilize Grid computing infrastructure as the main computing resource. The Grid system and services in KEK, which is already in production, are upgraded for the further stable operation at the same time of whole scale hardware replacement of KEK Central Computer System (KEKCC). The next generation system of KEKCC starts the operation from the beginning of September 2016. The basic Grid services e.g. BDII, VOMS, LFC, CREAM computing element and StoRM storage element are made by the more robust hardware configuration. Since the raw data transfer is one of the most important tasks for the KEKCC, two redundant GridFTP servers are adapted to the StoRM service instances with 40 Gbps network bandwidth on the LHCONE routing. These are dedicated to the Belle II raw data transfer to the other sites apart from the servers for the data transfer usage of the other VOs. Additionally, we prepare the redundant configuration for the database oriented services like LFC and AMGA by using LifeKeeper. The LFC servers are made by two read/write servers and two read-only servers for the Belle II experiment, and all of them have an individual database for the purpose of load balancing. The FTS3 service is newly deployed as a service for the Belle II data distribution. The service of CVMFS stratum-0 is

Numerical Analysis for IFM Grid Effect on 5x5 Rods Bundle

International Nuclear Information System (INIS)

Kim, Seong Jin; Cha, Jeong Hun; Seo, Kyong Won; Kim, Tae Woo; Kwon, Hyuk; Hwang, Dae Hyun

2011-01-01

Generally, the fuel assembly consists of fuel rods, bottom and top grids, spacer grids, mixing vane, etc. The mixing vane with spacer grid is used to increase the thermal mixing between subchannels and to increase CHF(Critical Heat Flux). IFM(Intermediate Flow Mixer) grids are used to induce lateral flow between adjacent channels and are well-known as improving CHF, also. A numerical analysis using CFD code(ANSYS CFX, version 12.1) and subchannel code(MATRA-S) was conducted to investigate the influence of IFM grid on the subchannel temperature in 5x5 rods bundle with and without the IFM grid, thermohydraulically. In this study, the quantitative improvement of the mixing effect of the IFM grid is presented from the results of CFX and MATRA-S code. Moreover, capacity of predicting subchannel temperature of MATRA-S code is compared with CFX result

Economic aspects of grid connected solar electricity generation

International Nuclear Information System (INIS)

Pharabod, F.

1993-01-01

Experience gained with available solar thermal technologies enlighten on options for research and development on solar electricity generation. The proposed analysis of new solar technologies concerns market, costs and profit viewpoint: - Systems under development have to fit with consumers' needs and utilities' specifications, technology is not the only item to study. - Expense headings depend on technological options and operation procedures such as size of the plant, solar only or hybrid concept. - Anticipation of revenues highly depends on direct insolation quality and on local conditions for introducing the electric power generated into the network: daily direct insolation measurements and annual local load curve are prerequisite data. Strategic advantages regarding environment and sustainable development are to be pointed out, specially in industrialized countries or for projects including financing institutions. As far as generating electric power on the grid is a major challenge in the development of a number of countries in the sun belt, cooperation between industrialized and developing countries, under the auspices of international organization, has to be promoted. (Author) 12 refs

Coordinated control of a DFIG-based wind-power generation system with SGSC under distorted grid voltage conditions

DEFF Research Database (Denmark)

Yao, Jun; Li, Qing; Chen, Zhe

2013-01-01

in the multiple synchronous rotating reference frames. In order to counteract the adverse effects of the voltage harmonics upon the DFIG, the SGSC generates series compensation control voltages to keep the stator voltage sinusoidal and symmetrical, which allows the use of the conventional vector control strategy......This paper presents a coordinated control method for a doubly-fed induction generator (DFIG)-based wind-power generation system with a series grid-side converter (SGSC) under distorted grid voltage conditions. The detailed mathematical models of the DFIG system with SGSC are developed...

ONIX results: Comparison of grid geometry (BATMAN - ELISE - flat grid)

Science.gov (United States)

Revel, Adrien; Mochalskyy, Serhiy; Wünderlich, Dirk; Fantz, Ursel; Minea, Tiberiu

2017-08-01

The 3D PIC-MCC code ONIX is dedicated to the modelling of negative hydrogen or deuterium ion extraction and the co-extracted electrons from the plasma in radio-frequency driven sources. The extraction process highly depends on the plasma characteristics close to the plasma grid where it is difficult to obtain experimental data. ONIX brings valuable insights on the plasma behavior in this area. In the code, the numerical treatment of the boundaries have been improved in order to describe with more accuracy the potential and the electric field in this vicinity. The computation time has been reduced by a factor of 2 and the parallelization efficiency has been highly improved. The influence of the magnetic field in BATMAN on the plasma behaviour has been investigated by comparing two different configurations of the magnet bars producing the filter field (internal magnets: x = 3 cm; external magnets: x = 9 cm). A flat grid geometry for the PG instead of the usual conical grid geometry has been studied to evaluate its impact on the extracted current, especially for the negative ions emitted from the surface of the PG. Finally, the ONIX code has been used for the first 3D PIC calculations ever performed for the ELISE experiment.

MEMOPS: data modelling and automatic code generation.

Science.gov (United States)

Fogh, Rasmus H; Boucher, Wayne; Ionides, John M C; Vranken, Wim F; Stevens, Tim J; Laue, Ernest D

2010-03-25

In recent years the amount of biological data has exploded to the point where much useful information can only be extracted by complex computational analyses. Such analyses are greatly facilitated by metadata standards, both in terms of the ability to compare data originating from different sources, and in terms of exchanging data in standard forms, e.g. when running processes on a distributed computing infrastructure. However, standards thrive on stability whereas science tends to constantly move, with new methods being developed and old ones modified. Therefore maintaining both metadata standards, and all the code that is required to make them useful, is a non-trivial problem. Memops is a framework that uses an abstract definition of the metadata (described in UML) to generate internal data structures and subroutine libraries for data access (application programming interfaces--APIs--currently in Python, C and Java) and data storage (in XML files or databases). For the individual project these libraries obviate the need for writing code for input parsing, validity checking or output. Memops also ensures that the code is always internally consistent, massively reducing the need for code reorganisation. Across a scientific domain a Memops-supported data model makes it easier to support complex standards that can capture all the data produced in a scientific area, share them among all programs in a complex software pipeline, and carry them forward to deposition in an archive. The principles behind the Memops generation code will be presented, along with example applications in Nuclear Magnetic Resonance (NMR) spectroscopy and structural biology.

Online Energy Management System for Distributed Generators in a Grid-Connected Microgrid

DEFF Research Database (Denmark)

Hernández, Adriana Carolina Luna; Aldana, Nelson Leonardo Diaz; Graells, Moises

2015-01-01

A microgrid is an energy subsystem composed of generation units, energy storage, and loads that requires power management in order to supply the load properly according to defined objectives. This paper proposes an online energy management system for a storage based grid-connected microgrid...

Demand response impacts on off-grid hybrid photovoltaic-diesel generator microgrids

Directory of Open Access Journals (Sweden)

Aaron St. Leger

2015-08-01

Full Text Available Hybrid microgrids consisting of diesel generator set(s and converter based power sources, such as solar photovoltaic or wind sources, offer an alternative to generator based off-grid power systems. The hybrid approach has been shown to be economical in many off-grid applications and can result in reduced generator operation, fuel requirements, and maintenance. However, the intermittent nature of demand and renewable energy sources typically require energy storage, such as batteries, to properly operate the hybrid microgrid. These batteries increase the system cost, require proper operation and maintenance, and have been shown to be unreliable in case studies on hybrid microgrids. This work examines the impacts of leveraging demand response in a hybrid microgrid in lieu of energy storage. The study is performed by simulating two different hybrid diesel generator—PV microgrid topologies, one with a single diesel generator and one with multiple paralleled diesel generators, for a small residential neighborhood with varying levels of demand response. Various system designs are considered and the optimal design, based on cost of energy, is presented for each level of demand response. The solar resources, performance of solar PV source, performance of diesel generators, costs of system components, maintenance, and operation are modeled and simulated at a time interval of ten minutes over a twenty-five year period for both microgrid topologies. Results are quantified through cost of energy, diesel fuel requirements, and utilization of the energy sources under varying levels of demand response. The results indicate that a moderate level of demand response can have significant positive impacts to the operation of hybrid microgrids through reduced energy cost, fuel consumption, and increased utilization of PV sources.

Impedance-Based Stability Analysis in Grid Interconnection Impact Study Owing to the Increased Adoption of Converter-Interfaced Generators

Directory of Open Access Journals (Sweden)

Youngho Cho

2017-09-01

Full Text Available This study investigates the emerging harmonic stability concerns to be addressed by grid planners in generation interconnection studies, owing to the increased adoption of renewable energy resources connected to the grid via power electronic converters. The wideband and high-frequency electromagnetic transient (EMT characteristics of these converter-interfaced generators (CIGs and their interaction with the grid impedance are not accurately captured in the typical dynamic studies conducted by grid planners. This paper thus identifies the desired components to be studied and subsequently develops a practical process for integrating a new CIG into a grid with the existing CIGs. The steps of this process are as follows: the impedance equation of a CIG using its control dynamics and an interface filter to the grid, for example, an LCL filter (inductor-capacitor-inductor type, is developed; an equivalent impedance model including the existing CIGs nearby and the grid observed from the point of common coupling are derived; the system stability for credible operating scenarios is assessed. Detailed EMT simulations validate the accuracy of the impedance models and stability assessment for various connection scenarios. By complementing the conventional EMT simulation studies, the proposed analytical approach enables grid planners to identify critical design parameters for seamlessly integrating a new CIG and ensuring the reliability of the grid.

Texture side information generation for distributed coding of video-plus-depth

DEFF Research Database (Denmark)

Salmistraro, Matteo; Raket, Lars Lau; Zamarin, Marco

2013-01-01

We consider distributed video coding in a monoview video-plus-depth scenario, aiming at coding textures jointly with their corresponding depth stream. Distributed Video Coding (DVC) is a video coding paradigm in which the complexity is shifted from the encoder to the decoder. The Side Information...... components) is strongly correlated, so the additional depth information may be used to generate more accurate SI for the texture stream, increasing the efficiency of the system. In this paper we propose various methods for accurate texture SI generation, comparing them with other state-of-the-art solutions...

Fair division of generation profile and fuel consumption in isolated micro-grids

DEFF Research Database (Denmark)

Kosek, Anna Magdalena; Heussen, Kai

2014-01-01

leads to more stressed loading conditions of diesel generators. We propose a control strategy employing fair division of generator allocation using a compensation procedure based on social choice methods. A co-simulation set up with separate power system and control strategy simulators is used...... to provide a proof-of-concept case study of an isolated micro-grid with two wind turbines and three diesel generators. In comparison with a simple master- slave allocation, the proposed coordination scheme improves the distribution of fuel allocation by 27,5%, reduces under-load time by 43,5% and decreases...

Wavelet-Coded OFDM for Next Generation Mobile Communications

DEFF Research Database (Denmark)

Cavalcante, Lucas Costa Pereira; Vegas Olmos, Juan José; Tafur Monroy, Idelfonso

2016-01-01

In this work, we evaluate the performance of Wavelet-Coding into offering robustness for OFDM signals against the combined effects of varying fading and noise bursts. Wavelet-Code enables high diversity gains with a low complex receiver, and, most notably, without compromising the system’s spectr......-wave frequencies in future generation mobile communication due to its robustness against multipath fading....

Forecasting Wind and Solar Generation: Improving System Operations, Greening the Grid (Spanish Version)

Energy Technology Data Exchange (ETDEWEB)

Tian, Tian; Chernyakhovskiy, Ilya; Brancucci Martinez-Anido, Carlo

2016-04-01

This document is the Spanish version of 'Greening the Grid- Forecasting Wind and Solar Generation Improving System Operations'. It discusses improving system operations with forecasting with and solar generation. By integrating variable renewable energy (VRE) forecasts into system operations, power system operators can anticipate up- and down-ramps in VRE generation in order to cost-effectively balance load and generation in intra-day and day-ahead scheduling. This leads to reduced fuel costs, improved system reliability, and maximum use of renewable resources.

Active current control in wind power plants during grid faults

DEFF Research Database (Denmark)

Martinez, Jorge; Kjær, Phillip C.; Rodriguez, Pedro

2010-01-01

Modern wind power plants are required and designed to ride through faults in electrical networks, subject to fault clearing. Wind turbine fault current contribution is required from most countries with a high amount of wind power penetration. In order to comply with such grid code requirements......, wind turbines usually have solutions that enable the turbines to control the generation of reactive power during faults. This paper addresses the importance of using an optimal injection of active current during faults in order to fulfil these grid codes. This is of relevant importance for severe...... faults, causing low voltages at the point of common coupling. As a consequence, a new wind turbine current controller for operation during faults is proposed. It is shown that to achieve the maximum transfer of reactive current at the point of common coupling, a strategy for optimal setting of the active...

C code generation applied to nonlinear model predictive control for an artificial pancreas

DEFF Research Database (Denmark)

Boiroux, Dimitri; Jørgensen, John Bagterp

2017-01-01

This paper presents a method to generate C code from MATLAB code applied to a nonlinear model predictive control (NMPC) algorithm. The C code generation uses the MATLAB Coder Toolbox. It can drastically reduce the time required for development compared to a manual porting of code from MATLAB to C...

A novel proposal of cooperation between a cage induction generator and the three-phase grid

Directory of Open Access Journals (Sweden)

Szular Zbigniew

2016-01-01

Full Text Available In the paper, a new concept of the cooperation between a cage induction generator and the three-phase grid is presented. The induction generator is excited by a capacitor battery connected to the stator winding terminals. In order to ensure a stable operation, the battery capacity should be continuously adjusted. Three appropriate selected capacitors are connected to the stator winding terminals by means of two bi-directional controlled switches. The generator output voltage is stabilized by a suitable control of these switches. The stator winding terminals are also connected to the diode bridge rectifier. Energy in the DC bus is converted to the parameters of the three-phase grid (400 V, 50 Hz by means of a three-phase voltage source inverter. Examples of numerical calculation results of the proposed energy generation system are presented in the end part of the paper.

BOT3P5.2, 3D Mesh Generator and Graphical Display of Geometry for Radiation Transport Codes, Display of Results

International Nuclear Information System (INIS)

Orsi, Roberto; Bidaud, Adrien

2007-01-01

1 - Description of program or function: BOT3P was originally conceived as a set of standard FORTRAN 77 language programs in order to give the users of the DORT and TORT deterministic transport codes some useful diagnostic tools to prepare and check their input data files. Later versions extended the possibility to produce the geometrical, material distribution and fixed neutron source data to other deterministic transport codes such as TWODANT/THREEDANT of the DANTSYS system, PARTISN and, potentially, to any transport code through BOT3P binary output files that can be easily interfaced (see, for example, the Russian two-dimensional (2D) and three-dimensional (3D) discrete ordinates neutron, photon and charged particle transport codes KASKAD-S-2.5 and KATRIN-2.0). As from Version 5.1 BOT3P contained important additions specifically addressed to radiation transport analysis for medical applications. BOT3P-5.2 contains new graphics capabilities. Some of them enable users to select space sub-domains of the total mesh grid in order to improve the zoom simulation of the geometry, both in 2D cuts and in 3D. Moreover the new BOT3P module (PDTM) may improve the interface of BOT3P geometrical models to transport analysis codes. The following programs are included in the BOT3P software package: GGDM, DDM, GGTM, DTM2, DTM3, RVARSCL, COMPARE, MKSRC, CATSM, DTET, and PDTM. The main features of these different programs are described. 2 - Methods: GGDM and GGTM work similarly from the logical point of view. Since the 3D case is more general, the following description refers to GGTM. All the co-ordinate values that characterise the geometrical scheme at the basis of the 3D transport code geometrical and material model are read, sorted and all stored if different from the neighbouring ones more than an input tolerance established by the user. These co-ordinates are always present in the fine-mesh boundary arrays independently of the mesh grid refinement options, because they

Integrated Design Engineering Analysis (IDEA) Environment Automated Generation of Structured CFD Grids using Topology Methods

Science.gov (United States)

Kamhawi, Hilmi N.

2012-01-01

This report documents the work performed from March 2010 to March 2012. The Integrated Design and Engineering Analysis (IDEA) environment is a collaborative environment based on an object-oriented, multidisciplinary, distributed framework using the Adaptive Modeling Language (AML) as a framework and supporting the configuration design and parametric CFD grid generation. This report will focus on describing the work in the area of parametric CFD grid generation using novel concepts for defining the interaction between the mesh topology and the geometry in such a way as to separate the mesh topology from the geometric topology while maintaining the link between the mesh topology and the actual geometry.

A unified grid current control for grid-interactive DG inverters in microgrids

DEFF Research Database (Denmark)

Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

2015-01-01

This paper proposes a unified grid current control for grid-interactive distributed generation inverters. In the approach, the grid-side current, instead of inverter-side current, is controlled as an inner loop, while the filter capacitor voltage is indirectly regulated through a virtual admittan...... locus analyses in the discrete z-domain are performed for elaborating the controller design. Simulations and experimental results demonstrate the performances of the proposed approach.......This paper proposes a unified grid current control for grid-interactive distributed generation inverters. In the approach, the grid-side current, instead of inverter-side current, is controlled as an inner loop, while the filter capacitor voltage is indirectly regulated through a virtual admittance...... in the outer loop. It, therefore, provides several superior features over traditional control schemes: 1) high-quality grid current in the grid-connected mode, 2) inherent derivative-less virtual output impedance control, and 3) the unified active damping for both grid-connected and islanded operations. Root...

Novel power saving architecture for FBG based OCDMA code generation

Science.gov (United States)

Osadola, Tolulope B.; Idris, Siti K.; Glesk, Ivan

2013-10-01

A novel architecture for generating incoherent, 2-dimensional wavelength hopping-time spreading optical CDMA codes is presented. The architecture is designed to facilitate the reuse of optical source signal that is unused after an OCDMA code has been generated using fiber Bragg grating based encoders. Effective utilization of available optical power is therefore achieved by cascading several OCDMA encoders thereby enabling 3dB savings in optical power.

Application of the FUN3D Unstructured-Grid Navier-Stokes Solver to the 4th AIAA Drag Prediction Workshop Cases

Science.gov (United States)

Lee-Rausch, Elizabeth M.; Hammond, Dana P.; Nielsen, Eric J.; Pirzadeh, S. Z.; Rumsey, Christopher L.

2010-01-01

FUN3D Navier-Stokes solutions were computed for the 4th AIAA Drag Prediction Workshop grid convergence study, downwash study, and Reynolds number study on a set of node-based mixed-element grids. All of the baseline tetrahedral grids were generated with the VGRID (developmental) advancing-layer and advancing-front grid generation software package following the gridding guidelines developed for the workshop. With maximum grid sizes exceeding 100 million nodes, the grid convergence study was particularly challenging for the node-based unstructured grid generators and flow solvers. At the time of the workshop, the super-fine grid with 105 million nodes and 600 million elements was the largest grid known to have been generated using VGRID. FUN3D Version 11.0 has a completely new pre- and post-processing paradigm that has been incorporated directly into the solver and functions entirely in a parallel, distributed memory environment. This feature allowed for practical pre-processing and solution times on the largest unstructured-grid size requested for the workshop. For the constant-lift grid convergence case, the convergence of total drag is approximately second-order on the finest three grids. The variation in total drag between the finest two grids is only 2 counts. At the finest grid levels, only small variations in wing and tail pressure distributions are seen with grid refinement. Similarly, a small wing side-of-body separation also shows little variation at the finest grid levels. Overall, the FUN3D results compare well with the structured-grid code CFL3D. The FUN3D downwash study and Reynolds number study results compare well with the range of results shown in the workshop presentations.

Generating grid states from Schrödinger-cat states without postselection

Science.gov (United States)

Weigand, Daniel J.; Terhal, Barbara M.

2018-02-01

Grid (or comb) states are an interesting class of bosonic states introduced by Gottesman, Kitaev, and Preskill [D. Gottesman, A. Kitaev, and J. Preskill, Phys. Rev. A 64, 012310 (2001), 10.1103/PhysRevA.64.012310] to encode a qubit into an oscillator. A method to generate or "breed" a grid state from Schrödinger cat states using beam splitters and homodyne measurements is known [H. M. Vasconcelos, L. Sanz, and S. Glancy, Opt. Lett. 35, 3261 (2010), 10.1364/OL.35.003261], but this method requires postselection. In this paper we show how postprocessing of the measurement data can be used to entirely remove the need for postselection, making the scheme much more viable. We bound the asymptotic behavior of the breeding procedure and demonstrate the efficacy of the method numerically.

Crowbar System in Doubly Fed Induction Wind Generators

Directory of Open Access Journals (Sweden)

Maurício B. C. Salles

2010-04-01

Full Text Available In the last 15 years, the use of doubly fed induction machines in modern variable-speed wind turbines has increased rapidly. This development has been driven by the cost reduction as well as the low-loss generation of Insulated Gate Bipolar Transistors (IGBT. According to new grid code requirements, wind turbines must remain connected to the grid during grid disturbances. Moreover, they must also contribute to voltage support during and after grid faults. The crowbar system is essential to avoid the disconnection of the doubly fed induction wind generators from the network during faults. The insertion of the crowbar in the rotor circuits for a short period of time enables a more efficient terminal voltage control. As a general rule, the activation and the deactivation of the crowbar system is based only on the DC-link voltage level of the back-to-back converters. In this context, the authors discuss the critical rotor speed to analyze the instability of doubly fed induction generators during grid faults.

Integration of permanent magnet synchronous generator wind turbines into power grid

Science.gov (United States)

Abedini, Asghar

The world is seeing an ever-increasing demand for electrical energy. The future growth of electrical power generation needs to be a mix of technologies including fossil fuels, hydro, nuclear, wind, and solar. The federal and state energy agencies have taken several proactive steps to increase the share of renewable energy in the total generated electrical power. In 2005, 11.1% of the total 1060 GW electricity generation capacity was from Renewable Energy Sources (RES) in the US. The power capacity portfolio included 9.2% from hydroelectric, 0.87% from wind, and 0.7% from biomass. Other renewable power capacity included 2.8 GW of geothermal, 0.4 GW of solar thermal, and 0.2 GW of solar PV. Although the share of renewable energy sources is small compared with the total power capacity, they are experiencing a high and steady growth. The US is leading the world in wind energy growth with a 27% increase in 2006 and a projected 26% increase in 2007, according to the American Wind Energy Association (AWEA). The US Department of Energy benchmarked a goal to meet 5% of the nation's energy need by launching the Wind Powering America (WPA) program. Although renewable energy sources have many benefits, their utilization in the electrical grid does not come without cost. The higher penetration of RES has introduced many technical and non-technical challenges, including power quality, reliability, safety and protection, load management, grid interconnections and control, new regulations, and grid operation economics. RES such as wind and PV are also intermittent in nature. The energy from these sources is available as long as there is wind or sunlight. However, these are energies that are abundant in the world and the power generated from these sources is pollution free. Due to high price of foundation of wind farms, employing variable speed wind turbines to maximize the extracted energy from blowing wind is more beneficial. On the other hand, since wind power is intermittent

Modal analysis of a grid-connected direct-drive permanent magnet synchronous generator wind turbine system

DEFF Research Database (Denmark)

Tan, Jin; Wang, Xiao Ru; Chen, Zhe

2013-01-01

In order to study the stability of a grid-connected direct-drive permanent magnet synchronous generator (PMSG) wind turbine systems, this paper presents the modal analysis of a PMSG wind turbine system. A PMSG model suitable for small signal stability analysis is presented. The modal properties...... of a grid-connected PMSG wind turbine system are studied. Then the comprehensive impacts of the shaft model, shaft parameters, operation points and lengths of the transmission line on the modal characteristic of the system are investigated by the eigenvalue analysis method. Meanwhile, the corresponding...... analysis. It offers a better understanding about the essence of the stability of grid-connected PMSG wind turbine system....

Research on grid connection control technology of double fed wind generator

Science.gov (United States)

Ling, Li

2017-01-01

The composition and working principle of variable speed constant frequency doubly fed wind power generation system is discussed in this thesis. On the basis of theoretical analysis and control on the modeling, the doubly fed wind power generation simulation control system is designed based on a TMS320F2407 digital signal processor (DSP), and has done a large amount of experimental research, which mainly include, variable speed constant frequency, constant pressure, Grid connected control experiment. The running results show that the design of simulation control system is reasonable and can meet the need of experimental research.

Grid support capabilities of wind turbines

DEFF Research Database (Denmark)

Michalke, Gabriele; Hansen, Anca Daniela

2013-01-01

Wind power has gained a significant penetration level in several power systems all over the world. Due to this reason modern wind turbines are requested to contribute to power system support. Power system operators have thus introduced grid codes, which specify a set of requirements for wind...... turbines, such as fault ride-through and reactive power supply during voltage sags. To date different wind turbine concepts exist on the market comprising different control features in order to provide ancillary services to the power system. In the first place the present chapter emphasizes the most...... important issues related to wind power grid integration. Then different wind turbine concepts are characterized and their grid support capabilities are analysed and compared. Simulation cases are presented in which the respective wind turbine concepts are subjected to a voltage dip specified in a grid code....

A UML profile for code generation of component based distributed systems

International Nuclear Information System (INIS)

Chiozzi, G.; Karban, R.; Andolfato, L.; Tejeda, A.

2012-01-01

A consistent and unambiguous implementation of code generation (model to text transformation) from UML (must rely on a well defined UML (Unified Modelling Language) profile, customizing UML for a particular application domain. Such a profile must have a solid foundation in a formally correct ontology, formalizing the concepts and their relations in the specific domain, in order to avoid a maze or set of wildly created stereotypes. The paper describes a generic profile for the code generation of component based distributed systems for control applications, the process to distill the ontology and define the profile, and the strategy followed to implement the code generator. The main steps that take place iteratively include: defining the terms and relations with an ontology, mapping the ontology to the appropriate UML meta-classes, testing the profile by creating modelling examples, and generating the code. This has allowed us to work on the modelling of E-ELT (European Extremely Large Telescope) control system and instrumentation without knowing what infrastructure will be finally used

Automatic Structure-Based Code Generation from Coloured Petri Nets

DEFF Research Database (Denmark)

Kristensen, Lars Michael; Westergaard, Michael

2010-01-01

Automatic code generation based on Coloured Petri Net (CPN) models is challenging because CPNs allow for the construction of abstract models that intermix control flow and data processing, making translation into conventional programming constructs difficult. We introduce Process-Partitioned CPNs...... (PP-CPNs) which is a subclass of CPNs equipped with an explicit separation of process control flow, message passing, and access to shared and local data. We show how PP-CPNs caters for a four phase structure-based automatic code generation process directed by the control flow of processes....... The viability of our approach is demonstrated by applying it to automatically generate an Erlang implementation of the Dynamic MANET On-demand (DYMO) routing protocol specified by the Internet Engineering Task Force (IETF)....

Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations.

Science.gov (United States)

Crăciun, Cora

2014-08-01

CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids' EPR behaviour, for different spin system symmetries. The metrics' efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method. Copyright © 2014 Elsevier Inc. All rights reserved.

Solution of Poisson equations for 3-dimensional grid generations. [computations of a flow field over a thin delta wing

Science.gov (United States)

Fujii, K.

1983-01-01

A method for generating three dimensional, finite difference grids about complicated geometries by using Poisson equations is developed. The inhomogenous terms are automatically chosen such that orthogonality and spacing restrictions at the body surface are satisfied. Spherical variables are used to avoid the axis singularity, and an alternating-direction-implicit (ADI) solution scheme is used to accelerate the computations. Computed results are presented that show the capability of the method. Since most of the results presented have been used as grids for flow-field computations, this is indicative that the method is a useful tool for generating three-dimensional grids about complicated geometries.

Adaptive grid generation in a patient-specific cerebral aneurysm

Science.gov (United States)

Hodis, Simona; Kallmes, David F.; Dragomir-Daescu, Dan

2013-11-01

Adapting grid density to flow behavior provides the advantage of increasing solution accuracy while decreasing the number of grid elements in the simulation domain, therefore reducing the computational time. One method for grid adaptation requires successive refinement of grid density based on observed solution behavior until the numerical errors between successive grids are negligible. However, such an approach is time consuming and it is often neglected by the researchers. We present a technique to calculate the grid size distribution of an adaptive grid for computational fluid dynamics (CFD) simulations in a complex cerebral aneurysm geometry based on the kinematic curvature and torsion calculated from the velocity field. The relationship between the kinematic characteristics of the flow and the element size of the adaptive grid leads to a mathematical equation to calculate the grid size in different regions of the flow. The adaptive grid density is obtained such that it captures the more complex details of the flow with locally smaller grid size, while less complex flow characteristics are calculated on locally larger grid size. The current study shows that kinematic curvature and torsion calculated from the velocity field in a cerebral aneurysm can be used to find the locations of complex flow where the computational grid needs to be refined in order to obtain an accurate solution. We found that the complexity of the flow can be adequately described by velocity and vorticity and the angle between the two vectors. For example, inside the aneurysm bleb, at the bifurcation, and at the major arterial turns the element size in the lumen needs to be less than 10% of the artery radius, while at the boundary layer, the element size should be smaller than 1% of the artery radius, for accurate results within a 0.5% relative approximation error. This technique of quantifying flow complexity and adaptive remeshing has the potential to improve results accuracy and reduce

Improved Control Strategies for a DFIG-Based Wind-Power Generation System with SGSC under Unbalanced and Distorted Grid Voltage Conditions

DEFF Research Database (Denmark)

Yao, Jun; Yu, Mengting; Hu, Weihao

2016-01-01

This paper investigates an improved control strategy for a doubly-fed induction generator (DFIG) based wind-power generation system with series grid-side converter (SGSC) under network unbalance and harmonic grid voltage distortion conditions. The integrated mathematical modeling of the DFIG system...... with SGSC is established by taking both the negative-sequence and harmonic components of the grid voltages into consideration with multiple synchronous rotating reference frames. Under network unbalance and harmonic distortion situations, stator voltage can be kept symmetrical and sinusoidal by the control...

Visualization of grid-generated turbulence in He II using PTV

Science.gov (United States)

Mastracci, B.; Guo, W.

2017-12-01

Due to its low viscosity, cryogenic He II has potential use for simulating large-scale, high Reynolds number turbulent flow in a compact and efficient apparatus. To realize this potential, the behavior of the fluid in the simplest cases, such as turbulence generated by flow past a mesh grid, must be well understood. We have designed, constructed, and commissioned an apparatus to visualize the evolution of turbulence in the wake of a mesh grid towed through He II. Visualization is accomplished using the particle tracking velocimetry (PTV) technique, where μm-sized tracer particles are introduced to the flow, illuminated with a planar laser sheet, and recorded by a scientific imaging camera; the particles move with the fluid, and tracking their motion with a computer algorithm results in a complete map of the turbulent velocity field in the imaging region. In our experiment, this region is inside a carefully designed He II filled cast acrylic channel measuring approximately 16 × 16 × 330 mm. One of three different grids, which have mesh numbers M = 3, 3.75, or 5 mm, can be attached to the pulling system which moves it through the channel with constant velocity up to 600 mm/s. The consequent motion of the solidified deuterium tracer particles is used to investigate the energy statistics, effective kinematic viscosity, and quantized vortex dynamics in turbulent He II.

Efficient Eulerian gyrokinetic simulations with block-structured grids

International Nuclear Information System (INIS)

Jarema, Denis

2017-01-01

Gaining a deep understanding of plasma microturbulence is of paramount importance for the development of future nuclear fusion reactors, because it causes a strong outward transport of heat and particles. Gyrokinetics has proven itself as a valid mathematical model to simulate such plasma microturbulence effects. In spite of the advantages of this model, nonlinear radially extended (or global) gyrokinetic simulations are still extremely computationally expensive, involving a very large number of computational grid points. Hence, methods that reduce the number of grid points without a significant loss of accuracy are a prerequisite to be able to run high-fidelity simulations. At the level of the mathematical model, the gyrokinetic approach achieves a reduction from six to five coordinates in comparison to the fully kinetic models. This reduction leads to an important decrease in the total number of computational grid points. However, the velocity space mixed with the radial direction still requires a very fine resolution in grid based codes, due to the disparities in the thermal speed, which are caused by a strong temperature variation along the radial direction. An attempt to address this problem by modifying the underlying gyrokinetic set of equations leads to additional nonlinear terms, which are the most expensive parts to simulate. Furthermore, because of these modifications, well-established and computationally efficient implementations developed for the original set of equations can no longer be used. To tackle such issues, in this thesis we introduce an alternative approach of blockstructured grids. This approach reduces the number of grid points significantly, but without changing the underlying mathematical model. Furthermore, our technique is minimally invasive and allows the reuse of a large amount of already existing code using rectilinear grids, modifications being necessary only on the block boundaries. Moreover, the block-structured grid can be

Efficient Eulerian gyrokinetic simulations with block-structured grids

Energy Technology Data Exchange (ETDEWEB)

Jarema, Denis

2017-01-20

Gaining a deep understanding of plasma microturbulence is of paramount importance for the development of future nuclear fusion reactors, because it causes a strong outward transport of heat and particles. Gyrokinetics has proven itself as a valid mathematical model to simulate such plasma microturbulence effects. In spite of the advantages of this model, nonlinear radially extended (or global) gyrokinetic simulations are still extremely computationally expensive, involving a very large number of computational grid points. Hence, methods that reduce the number of grid points without a significant loss of accuracy are a prerequisite to be able to run high-fidelity simulations. At the level of the mathematical model, the gyrokinetic approach achieves a reduction from six to five coordinates in comparison to the fully kinetic models. This reduction leads to an important decrease in the total number of computational grid points. However, the velocity space mixed with the radial direction still requires a very fine resolution in grid based codes, due to the disparities in the thermal speed, which are caused by a strong temperature variation along the radial direction. An attempt to address this problem by modifying the underlying gyrokinetic set of equations leads to additional nonlinear terms, which are the most expensive parts to simulate. Furthermore, because of these modifications, well-established and computationally efficient implementations developed for the original set of equations can no longer be used. To tackle such issues, in this thesis we introduce an alternative approach of blockstructured grids. This approach reduces the number of grid points significantly, but without changing the underlying mathematical model. Furthermore, our technique is minimally invasive and allows the reuse of a large amount of already existing code using rectilinear grids, modifications being necessary only on the block boundaries. Moreover, the block-structured grid can be

Architectural and Algorithmic Requirements for a Next-Generation System Analysis Code

Energy Technology Data Exchange (ETDEWEB)

V.A. Mousseau

2010-05-01

This document presents high-level architectural and system requirements for a next-generation system analysis code (NGSAC) to support reactor safety decision-making by plant operators and others, especially in the context of light water reactor plant life extension. The capabilities of NGSAC will be different from those of current-generation codes, not only because computers have evolved significantly in the generations since the current paradigm was first implemented, but because the decision-making processes that need the support of next-generation codes are very different from the decision-making processes that drove the licensing and design of the current fleet of commercial nuclear power reactors. The implications of these newer decision-making processes for NGSAC requirements are discussed, and resulting top-level goals for the NGSAC are formulated. From these goals, the general architectural and system requirements for the NGSAC are derived.

Distributed generation, storage, demand response and energy efficiency as alternatives to grid capacity enhancement

International Nuclear Information System (INIS)

Poudineh, Rahmatallah; Jamasb, Tooraj

2014-01-01

The need for investment in capital intensive electricity networks is on the rise in many countries. A major advantage of distributed resources is their potential for deferring investments in distribution network capacity. However, utilizing the full benefits of these resources requires addressing several technical, economic and regulatory challenges. A significant barrier pertains to the lack of an efficient market mechanism that enables this concept and also is consistent with business model of distribution companies under an unbundled power sector paradigm. This paper proposes a market-oriented approach termed as “contract for deferral scheme” (CDS). The scheme outlines how an economically efficient portfolio of distributed generation, storage, demand response and energy efficiency can be integrated as network resources to reduce the need for grid capacity and defer demand driven network investments. - Highlights: • The paper explores a practical framework for smart electricity distribution grids. • The aim is to defer large capital investments in the network by utilizing and incentivising distributed generation, demand response, energy efficiency and storage as network resources. • The paper discusses a possible new market model that enables integration of distributed resources as alternative to grid capacity enhancement

Modeling Guidelines for Code Generation in the Railway Signaling Context

Science.gov (United States)

Ferrari, Alessio; Bacherini, Stefano; Fantechi, Alessandro; Zingoni, Niccolo

2009-01-01

Modeling guidelines constitute one of the fundamental cornerstones for Model Based Development. Their relevance is essential when dealing with code generation in the safety-critical domain. This article presents the experience of a railway signaling systems manufacturer on this issue. Introduction of Model-Based Development (MBD) and code generation in the industrial safety-critical sector created a crucial paradigm shift in the development process of dependable systems. While traditional software development focuses on the code, with MBD practices the focus shifts to model abstractions. The change has fundamental implications for safety-critical systems, which still need to guarantee a high degree of confidence also at code level. Usage of the Simulink/Stateflow platform for modeling, which is a de facto standard in control software development, does not ensure by itself production of high-quality dependable code. This issue has been addressed by companies through the definition of modeling rules imposing restrictions on the usage of design tools components, in order to enable production of qualified code. The MAAB Control Algorithm Modeling Guidelines (MathWorks Automotive Advisory Board)[3] is a well established set of publicly available rules for modeling with Simulink/Stateflow. This set of recommendations has been developed by a group of OEMs and suppliers of the automotive sector with the objective of enforcing and easing the usage of the MathWorks tools within the automotive industry. The guidelines have been published in 2001 and afterwords revisited in 2007 in order to integrate some additional rules developed by the Japanese division of MAAB [5]. The scope of the current edition of the guidelines ranges from model maintainability and readability to code generation issues. The rules are conceived as a reference baseline and therefore they need to be tailored to comply with the characteristics of each industrial context. Customization of these

Electric Grid Expansion Planning with High Levels of Variable Generation

Energy Technology Data Exchange (ETDEWEB)

Hadley, Stanton W. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); You, Shutang [Univ. of Tennessee, Knoxville, TN (United States); Shankar, Mallikarjun [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liu, Yilu [Univ. of Tennessee, Knoxville, TN (United States); Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

2016-02-01

Renewables are taking a large proportion of generation capacity in U.S. power grids. As their randomness has increasing influence on power system operation, it is necessary to consider their impact on system expansion planning. To this end, this project studies the generation and transmission expansion co-optimization problem of the US Eastern Interconnection (EI) power grid with a high wind power penetration rate. In this project, the generation and transmission expansion problem for the EI system is modeled as a mixed-integer programming (MIP) problem. This study analyzed a time series creation method to capture the diversity of load and wind power across balancing regions in the EI system. The obtained time series can be easily introduced into the MIP co-optimization problem and then solved robustly through available MIP solvers. Simulation results show that the proposed time series generation method and the expansion co-optimization model and can improve the expansion result significantly after considering the diversity of wind and load across EI regions. The improved expansion plan that combines generation and transmission will aid system planners and policy makers to maximize the social welfare. This study shows that modelling load and wind variations and diversities across balancing regions will produce significantly different expansion result compared with former studies. For example, if wind is modeled in more details (by increasing the number of wind output levels) so that more wind blocks are considered in expansion planning, transmission expansion will be larger and the expansion timing will be earlier. Regarding generation expansion, more wind scenarios will slightly reduce wind generation expansion in the EI system and increase the expansion of other generation such as gas. Also, adopting detailed wind scenarios will reveal that it may be uneconomic to expand transmission networks for transmitting a large amount of wind power through a long distance

Homogeneity and EPR metrics for assessment of regular grids used in CW EPR powder simulations

Science.gov (United States)

Crăciun, Cora

2014-08-01

CW EPR powder spectra may be approximated numerically using a spherical grid and a Voronoi tessellation-based cubature. For a given spin system, the quality of simulated EPR spectra depends on the grid type, size, and orientation in the molecular frame. In previous work, the grids used in CW EPR powder simulations have been compared mainly from geometric perspective. However, some grids with similar homogeneity degree generate different quality simulated spectra. This paper evaluates the grids from EPR perspective, by defining two metrics depending on the spin system characteristics and the grid Voronoi tessellation. The first metric determines if the grid points are EPR-centred in their Voronoi cells, based on the resonance magnetic field variations inside these cells. The second metric verifies if the adjacent Voronoi cells of the tessellation are EPR-overlapping, by computing the common range of their resonance magnetic field intervals. Beside a series of well known regular grids, the paper investigates a modified ZCW grid and a Fibonacci spherical code, which are new in the context of EPR simulations. For the investigated grids, the EPR metrics bring more information than the homogeneity quantities and are better related to the grids’ EPR behaviour, for different spin system symmetries. The metrics’ efficiency and limits are finally verified for grids generated from the initial ones, by using the original or magnetic field-constraint variants of the Spherical Centroidal Voronoi Tessellation method.

SPAGETTA: a Multi-Purpose Gridded Stochastic Weather Generator

Science.gov (United States)

Dubrovsky, M.; Huth, R.; Rotach, M. W.; Dabhi, H.

2017-12-01

SPAGETTA is a new multisite/gridded multivariate parametric stochastic weather generator (WG). Site-specific precipitation occurrence and amount are modelled by Markov chain and Gamma distribution, the non-precipitation variables are modelled by an autoregressive (AR) model conditioned on precipitation occurrence, and the spatial coherence of all variables is modelled following the Wilks' (2009) approach. SPAGETTA may be run in two modes. Mode 1: it is run as a classical WG, which is calibrated using weather series from multiple sites, and only then it may produce arbitrarily long synthetic series mimicking the spatial and temporal structure of the calibration data. To generate the weather series representing the future climate, the WG parameters are modified according to the climate change scenario, typically derived from GCM or RCM simulations. Mode 2: the user provides only basic information (not necessarily to be realistic) on the temporal and spatial auto-correlation structure of the weather variables and their mean annual cycle; the generator itself derives the parameters of the underlying AR model, which produces the multi-site weather series. Optionally, the user may add the spatially varying trend, which is superimposed to the synthetic series. The contribution consists of following parts: (a) Model of the WG. (b) Validation of WG in terms of the spatial temperature and precipitation characteristics, including characteristics of spatial hot/cold/dry/wet spells. (c) Results of the climate change impact experiment, in which the WG parameters representing the spatial and temporal variability are modified using the climate change scenarios and the effect on the above spatial validation indices is analysed. In this experiment, the WG is calibrated using the E-OBS gridded daily weather data for several European regions, and the climate change scenarios are derived from the selected RCM simulations (CORDEX database). (d) The second mode of operation will be

AMZ, multigroup constant library for EXPANDA code, generated by NJOY code from ENDF/B-IV

International Nuclear Information System (INIS)

Chalhoub, E.S.; Moraes, Marisa de

1985-01-01

It is described a library of multigroup constants with 70 energy groups and 37 isotopes to fast reactor calculation. The cross sections, scattering matrices and self-shielding factors were generated by NJOY code and RGENDF interface program, from ENDF/B-IV'S evaluated data. The library is edited in adequated format to be used by EXPANDA code. (M.C.K.) [pt

Power Electronic Drives, Controls, and Electric Generators for Large Wind Turbines - An Overview

DEFF Research Database (Denmark)

Ma, Ke; Tutelea, L.; Boldea, Ion

2015-01-01

and exceed a power rating of 10 MW are discussed. The role of power electronics for improving the operation of wind turbines and ensuring compliance with power grid codes is analyzed with a view at producing fully controllable generation units suitable for tight integration into the power grid and large...

Developments in the Generation and Interpretation of Wire Codes (invited paper)

International Nuclear Information System (INIS)

Ebi, K.L.

1999-01-01

Three new developments in the generation and interpretation of wire codes are discussed. First, a method was developed to computer generate wire codes using data gathered from a utility database of the local distribution system and from tax assessor records. This method was used to wire code more than 250,000 residences in the greater Denver metropolitan area. There was an approximate 75% agreement with field wire coding. Other research in Denver suggests that wire codes predict some characteristics of a residence and its neighbourhood, including age, assessed value, street layout and traffic density. A third new development is the case-specular method to study the association between wire codes and childhood cancers. Recent results from applying the method to the Savitz et al and London et al studies suggest that the associations between childhood cancer and VHCC residences were strongest for residences with a backyard rather than street service drop, and for VHCC residences with LCC speculars. (author)

Recent advances in neutral particle transport methods and codes

International Nuclear Information System (INIS)

Azmy, Y.Y.

1996-01-01

An overview of ORNL's three-dimensional neutral particle transport code, TORT, is presented. Special features of the code that make it invaluable for large applications are summarized for the prospective user. Advanced capabilities currently under development and installation in the production release of TORT are discussed; they include: multitasking on Cray platforms running the UNICOS operating system; Adjacent cell Preconditioning acceleration scheme; and graphics codes for displaying computed quantities such as the flux. Further developments for TORT and its companion codes to enhance its present capabilities, as well as expand its range of applications are disucssed. Speculation on the next generation of neutron particle transport codes at ORNL, especially regarding unstructured grids and high order spatial approximations, are also mentioned

Verification of 3-D generation code package for neutronic calculations of WWERs

International Nuclear Information System (INIS)

Sidorenko, V.D.; Aleshin, S.S.; Bolobov, P.A.; Bolshagin, S.N.; Lazarenko, A.P.; Markov, A.V.; Morozov, V.V.; Syslov, A.A.; Tsvetkov, V.M.

2000-01-01

Materials on verification of the 3 -d generation code package for WWERs neutronic calculations are presented. The package includes: - spectral code TVS-M; - 2-D fine mesh diffusion code PERMAK-A for 4- or 6-group calculation of WWER core burnup; - 3-D coarse mesh diffusion code BIPR-7A for 2-group calculations of quasi-stationary WWERs regimes. The materials include both TVS-M verification data and verification data on PERMAK-A and BIPR-7A codes using constant libraries generated with TVS-M. All materials are related to the fuel without Gd. TVS-M verification materials include results of comparison both with benchmark calculations obtained by other codes and with experiments carried out at ZR-6 critical facility. PERMAK-A verification materials contain results of comparison with TVS-M calculations and with ZR-6 experiments. BIPR-7A materials include comparison with operation data for Dukovany-2 and Loviisa-1 NPPs (WWER-440) and for Balakovo NPP Unit 4 (WWER-1000). The verification materials demonstrate rather good accuracy of calculations obtained with the use of code package of the 3 -d generation. (Authors)

Fast calculation method of computer-generated hologram using a depth camera with point cloud gridding

Science.gov (United States)

Zhao, Yu; Shi, Chen-Xiao; Kwon, Ki-Chul; Piao, Yan-Ling; Piao, Mei-Lan; Kim, Nam

2018-03-01

We propose a fast calculation method for a computer-generated hologram (CGH) of real objects that uses a point cloud gridding method. The depth information of the scene is acquired using a depth camera and the point cloud model is reconstructed virtually. Because each point of the point cloud is distributed precisely to the exact coordinates of each layer, each point of the point cloud can be classified into grids according to its depth. A diffraction calculation is performed on the grids using a fast Fourier transform (FFT) to obtain a CGH. The computational complexity is reduced dramatically in comparison with conventional methods. The feasibility of the proposed method was confirmed by numerical and optical experiments.

An Infrastructure for UML-Based Code Generation Tools

Science.gov (United States)

Wehrmeister, Marco A.; Freitas, Edison P.; Pereira, Carlos E.

The use of Model-Driven Engineering (MDE) techniques in the domain of distributed embedded real-time systems are gain importance in order to cope with the increasing design complexity of such systems. This paper discusses an infrastructure created to build GenERTiCA, a flexible tool that supports a MDE approach, which uses aspect-oriented concepts to handle non-functional requirements from embedded and real-time systems domain. GenERTiCA generates source code from UML models, and also performs weaving of aspects, which have been specified within the UML model. Additionally, this paper discusses the Distributed Embedded Real-Time Compact Specification (DERCS), a PIM created to support UML-based code generation tools. Some heuristics to transform UML models into DERCS, which have been implemented in GenERTiCA, are also discussed.

Camera Coverage Estimation Based on Multistage Grid Subdivision

Directory of Open Access Journals (Sweden)

Meizhen Wang

2017-04-01

Full Text Available Visual coverage is one of the most important quality indexes for depicting the usability of an individual camera or camera network. It is the basis for camera network deployment, placement, coverage-enhancement, planning, etc. Precision and efficiency are critical influences on applications, especially those involving several cameras. This paper proposes a new method to efficiently estimate superior camera coverage. First, the geographic area that is covered by the camera and its minimum bounding rectangle (MBR without considering obstacles is computed using the camera parameters. Second, the MBR is divided into grids using the initial grid size. The status of the four corners of each grid is estimated by a line of sight (LOS algorithm. If the camera, considering obstacles, covers a corner, the status is represented by 1, otherwise by 0. Consequently, the status of a grid can be represented by a code that is a combination of 0s or 1s. If the code is not homogeneous (not four 0s or four 1s, the grid will be divided into four sub-grids until the sub-grids are divided into a specific maximum level or their codes are homogeneous. Finally, after performing the process above, total camera coverage is estimated according to the size and status of all grids. Experimental results illustrate that the proposed method’s accuracy is determined by the method that divided the coverage area into the smallest grids at the maximum level, while its efficacy is closer to the method that divided the coverage area into the initial grids. It considers both efficiency and accuracy. The initial grid size and maximum level are two critical influences on the proposed method, which can be determined by weighing efficiency and accuracy.

Strong normalization by type-directed partial evaluation and run-time code generation

DEFF Research Database (Denmark)

Balat, Vincent; Danvy, Olivier

1998-01-01

We investigate the synergy between type-directed partial evaluation and run-time code generation for the Caml dialect of ML. Type-directed partial evaluation maps simply typed, closed Caml values to a representation of their long βη-normal form. Caml uses a virtual machine and has the capability...... to load byte code at run time. Representing the long βη-normal forms as byte code gives us the ability to strongly normalize higher-order values (i.e., weak head normal forms in ML), to compile the resulting strong normal forms into byte code, and to load this byte code all in one go, at run time. We...... conclude this note with a preview of our current work on scaling up strong normalization by run-time code generation to the Caml module language....

Strong Normalization by Type-Directed Partial Evaluation and Run-Time Code Generation

DEFF Research Database (Denmark)

Balat, Vincent; Danvy, Olivier

1997-01-01

We investigate the synergy between type-directed partial evaluation and run-time code generation for the Caml dialect of ML. Type-directed partial evaluation maps simply typed, closed Caml values to a representation of their long βη-normal form. Caml uses a virtual machine and has the capability...... to load byte code at run time. Representing the long βη-normal forms as byte code gives us the ability to strongly normalize higher-order values (i.e., weak head normal forms in ML), to compile the resulting strong normal forms into byte code, and to load this byte code all in one go, at run time. We...... conclude this note with a preview of our current work on scaling up strong normalization by run-time code generation to the Caml module language....

A method for generating subgroup parameters from resonance tables and the SPART code

International Nuclear Information System (INIS)

Devan, K.; Mohanakrishnan, P.

1995-01-01

A method for generating subgroup or band parameters from resonance tables is described. A computer code SPART was written using this method. This code generates the subgroup parameters for any number of bands within the specified broad groups at different temperatures by reading the required input data from the binary cross section library in the Cadarache format. The results obtained with SPART code for two bands were compared with that obtained from GROUPIE code and a good agreement was obtained. Results of the generation of subgroup parameters in four bands for sample case of 239 Pu from resonance tables of Cadarache Ver.2 library is also presented. 6 refs, 2 tabs

A Novel Grid Impedance Estimation Technique based on Adaptive Virtual Resistance Control Loop Applied to Distributed Generation Inverters

DEFF Research Database (Denmark)

Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem

2013-01-01

and to take the decision of either keep the DG connected, or disconnect it from the utility grid. The proposed method is based on a fast and easy grid fault detection method. A virtual damping resistance is used to drive the system to the resonance in order to extract the grid impedance parameters, both...... the power quality and even damage some sensitive loads connected at the point of the common coupling (PCC). This paper presents detection-estimation method of the grid impedance variation. This estimation tehnique aims to improve the dynamic of the distributed generation (DG) interfacing inverter control...

Generating Importance Map for Geometry Splitting using Discrete Ordinates Code in Deep Shielding Problem

International Nuclear Information System (INIS)

Kim, Jong Woon; Lee, Young Ouk

2016-01-01

When we use MCNP code for a deep shielding problem, we prefer to use variance reduction technique such as geometry splitting, or weight window, or source biasing to have relative error within reliable confidence interval. To generate importance map for geometry splitting in MCNP calculation, we should know the track entering number and previous importance on each cells since a new importance is calculated based on these information. If a problem is deep shielding problem such that we have zero tracks entering on a cell, we cannot generate new importance map. In this case, discrete ordinates code can provide information to generate importance map easily. In this paper, we use AETIUS code as a discrete ordinates code. Importance map for MCNP is generated based on a zone average flux of AETIUS calculation. The discretization of space, angle, and energy is not necessary for MCNP calculation. This is the big merit of MCNP code compared to the deterministic code. However, deterministic code (i.e., AETIUS) can provide a rough estimate of the flux throughout a problem relatively quickly. This can help MCNP by providing variance reduction parameters. Recently, ADVANTG code is released. This is an automated tool for generating variance reduction parameters for fixed-source continuous-energy Monte Carlo simulations with MCNP5 v1.60

Energy solutions in rural Africa: mapping electrification costs of distributed solar and diesel generation versus grid extension

Energy Technology Data Exchange (ETDEWEB)

Szabo, S; Bodis, K; Huld, T [European Commission Joint Research Centre, Institute for Energy, Renewable Energy Unit, 2749 via Enrico Fermi, TP450, 21027 Ispra (Vatican City State, Holy See) (Italy); Moner-Girona, M, E-mail: Sandor.Szabo@ec.europa.eu [UNEP Energy Branch Division of Technology, Industry and Economics, 15 rue de Milan, F-75441, Paris CEDEX09 (France)

2011-07-15

Three rural electrification options are analysed showing the cost optimal conditions for a sustainable energy development applying renewable energy sources in Africa. A spatial electricity cost model has been designed to point out whether diesel generators, photovoltaic systems or extension of the grid are the least-cost option in off-grid areas. The resulting mapping application offers support to decide in which regions the communities could be electrified either within the grid or in an isolated mini-grid. Donor programs and National Rural Electrification Agencies (or equivalent governmental departments) could use this type of delineation for their program boundaries and then could use the local optimization tools adapted to the prevailing parameters.

Energy solutions in rural Africa: mapping electrification costs of distributed solar and diesel generation versus grid extension

International Nuclear Information System (INIS)

Szabo, S; Bodis, K; Huld, T; Moner-Girona, M

2011-01-01

Three rural electrification options are analysed showing the cost optimal conditions for a sustainable energy development applying renewable energy sources in Africa. A spatial electricity cost model has been designed to point out whether diesel generators, photovoltaic systems or extension of the grid are the least-cost option in off-grid areas. The resulting mapping application offers support to decide in which regions the communities could be electrified either within the grid or in an isolated mini-grid. Donor programs and National Rural Electrification Agencies (or equivalent governmental departments) could use this type of delineation for their program boundaries and then could use the local optimization tools adapted to the prevailing parameters.

The NIMROD Code

Science.gov (United States)

Schnack, D. D.; Glasser, A. H.

1996-11-01

NIMROD is a new code system that is being developed for the analysis of modern fusion experiments. It is being designed from the beginning to make the maximum use of massively parallel computer architectures and computer graphics. The NIMROD physics kernel solves the three-dimensional, time-dependent two-fluid equations with neo-classical effects in toroidal geometry of arbitrary poloidal cross section. The NIMROD system also includes a pre-processor, a grid generator, and a post processor. User interaction with NIMROD is facilitated by a modern graphical user interface (GUI). The NIMROD project is using Quality Function Deployment (QFD) team management techniques to minimize re-engineering and reduce code development time. This paper gives an overview of the NIMROD project. Operation of the GUI is demonstrated, and the first results from the physics kernel are given.

Planning in Smart Grids

NARCIS (Netherlands)

Bosman, M.G.C.

2012-01-01

The electricity supply chain is changing, due to increasing awareness for sustainability and an improved energy efficiency. The traditional infrastructure where demand is supplied by centralized generation is subject to a transition towards a Smart Grid. In this Smart Grid, sustainable generation

A solar PV augmented hybrid scheme for enhanced wind power generation through improved control strategy for grid connected doubly fed induction generator

Directory of Open Access Journals (Sweden)

Adikanda Parida

2016-12-01

Full Text Available In this paper, a wind power generation scheme using a grid connected doubly fed induction generator (DFIG augmented with solar PV has been proposed. A reactive power-based rotor speed and position estimation technique with reduced machine parameter sensitivity is also proposed to improve the performance of the DFIG controller. The estimation algorithm is based on model reference adaptive system (MRAS, which uses the air gap reactive power as the adjustable variable. The overall generation reliability of the wind energy conversion system can be considerably improved as both solar and wind energy can supplement each other during lean periods of either of the sources. The rotor-side DC-link voltage and active power generation at the stator terminals of the DFIG are maintained constant with minimum storage battery capacity using single converter arrangement without grid-side converter (GSC. The proposed scheme has been simulated and experimentally validated with a practical 2.5 kW DFIG using dSPACE CP1104 module which produced satisfactory results.

Geodynamo and mantle convection simulations on the Earth Simulator using the Yin-Yang grid

International Nuclear Information System (INIS)

Kageyama, Akira; Yoshida, Masaki

2005-01-01

We have developed finite difference codes based on the Yin-Yang grid for the geodynamo simulation and the mantle convection simulation. The Yin-Yang grid is a kind of spherical overset grid that is composed of two identical component grids. The intrinsic simplicity of the mesh configuration of the Yin-Yang grid enables us to develop highly optimized simulation codes on massively parallel supercomputers. The Yin-Yang geodynamo code has achieved 15.2 Tflops with 4096 processors on the Earth Simulator. This represents 46% of the theoretical peak performance. The Yin-Yang mantle code has enabled us to carry out mantle convection simulations in realistic regimes with a Rayleigh number of 10 7 including strongly temperature dependent viscosity with spatial contrast up to 10 6

Grid simulator for power quality assessment of micro-grids

DEFF Research Database (Denmark)

Carrasco, Joaquin Eloy Garcia; Vasquez, Juan Carlos; Guerrero, Josep M.

2013-01-01

voltages, low-order harmonics and flicker. The aim of this equipment is to test the performance of a given system under such distorted voltages. A prototype of the simulator, consisting of two inverters connected back-to-back to a 380 V three-phase grid and feeding a micro-grid composed of two......-inverter interfaced distributed generators and a critical load was built and tested. A set of experimental results for linear purely resistive loads, non-linear loads and current-controlled inverters is presented to prove the capabilities of the simulator. Finally, a case study is presented by testing a micro-grid.......In this study, a grid simulator based on a back-to-back inverter topology with resonant controllers is presented. The simulator is able to generate three-phase voltages for a range of amplitudes and frequencies with different types of perturbations, such as voltage sags, steady-state unbalanced...

Generation-Side Power Scheduling in a Grid-Connected DC Microgrid

DEFF Research Database (Denmark)

Hernández, Adriana Carolina Luna; Aldana, Nelson Leonardo Diaz; Meng, Lexuan

2015-01-01

In this paper, a constrained mixed-integer programming model for scheduling the active power supplied by the generation units in storage-based DC microgrids is presented. The optimization problem minimizes operating costs taking into account a two-stage mode operation of the energy storage system...... so that a more accurate model for optimization of the microgrid operation can be obtained. The model is used in a particular grid-connected DC microgrid that includes two renewable energy sources and an energy storage system which supply a critical load. The results of the scheduling process...

A dynamic power management strategy of a grid connected hybrid generation system using wind, photovoltaic and Flywheel Energy Storage System in residential applications

International Nuclear Information System (INIS)

Boukettaya, Ghada; Krichen, Lotfi

2014-01-01

A global supervisory strategy for a micro-grid power generation system that comprises wind and photovoltaic generation subsystems, a flywheel storage system, and domestic loads connected both to the hybrid power generators and to the grid, is developed in this paper. The objectives of the supervisor control are, firstly, to satisfy in most cases the load power demand and, secondly, to check storage and grid constraints to prevent blackout, to reduce energy costs and greenhouse gas emissions, and to extend the life of the flywheel. For these purposes, the supervisor determines online the operation mode of the different generation subsystems, switching from maximum power conversion to power regulation. Decision criteria for the supervisor based on actual variables are presented. Finally, the performance of the supervisor is extensively assessed through computer simulation using a comprehensive nonlinear model of the studied system. - Highlights: • We supervise a micro-grid power generation system with an objective to produce clipping grid consumption. • The supervisor switch online from maximum power conversion to power regulation. • We provide services both for domestic users and for the distribution network manager. • The developed algorithm is tested and validated for different scenarios

Smart grid security and firmware roll back capabilities

Energy Technology Data Exchange (ETDEWEB)

Katzir, Liran [Better Place Inc., Rosh-Ha' ayin (Israel); Beck, Yuval; Golan, Gady [Holon Institute of Technology, Holon (Israel)

2012-07-01

With the widespread use of smart metering and industrial control devices, a new challenge has emerged - that of allowing the utility companies and hardware manufactures to develop and deploy devices running operation code (''firmware'') that can be updated remotely, but in a way does not endanger the electrical grid. While modern cryptography provides tools for addressing this challenge, it may not be enough. We propose here a method for securely updating the software controlling devices connected to an Alternating Current network that offers an added, stronger layer of protection against malicious code updates. This is achieved by allowing only the power generating authority to open a special ''window'' within which the devices accept such updates. (orig.)

GAMERA - The New Magnetospheric Code

Science.gov (United States)

Lyon, J.; Sorathia, K.; Zhang, B.; Merkin, V. G.; Wiltberger, M. J.; Daldorff, L. K. S.

2017-12-01

The Lyon-Fedder-Mobarry (LFM) code has been a main-line magnetospheric simulation code for 30 years. The code base, designed in the age of memory to memory vector ma- chines,is still in wide use for science production but needs upgrading to ensure the long term sustainability. In this presentation, we will discuss our recent efforts to update and improve that code base and also highlight some recent results. The new project GAM- ERA, Grid Agnostic MHD for Extended Research Applications, has kept the original design characteristics of the LFM and made significant improvements. The original de- sign included high order numerical differencing with very aggressive limiting, the ability to use arbitrary, but logically rectangular, grids, and maintenance of div B = 0 through the use of the Yee grid. Significant improvements include high-order upwinding and a non-clipping limiter. One other improvement with wider applicability is an im- proved averaging technique for the singularities in polar and spherical grids. The new code adopts a hybrid structure - multi-threaded OpenMP with an overarching MPI layer for large scale and coupled applications. The MPI layer uses a combination of standard MPI and the Global Array Toolkit from PNL to provide a lightweight mechanism for coupling codes together concurrently. The single processor code is highly efficient and can run magnetospheric simulations at the default CCMC resolution faster than real time on a MacBook pro. We have run the new code through the Athena suite of tests, and the results compare favorably with the codes available to the astrophysics community. LFM/GAMERA has been applied to many different situations ranging from the inner and outer heliosphere and magnetospheres of Venus, the Earth, Jupiter and Saturn. We present example results the Earth's magnetosphere including a coupled ring current (RCM), the magnetospheres of Jupiter and Saturn, and the inner heliosphere.

Parallel Reservoir Simulations with Sparse Grid Techniques and Applications to Wormhole Propagation

KAUST Repository

Wu, Yuanqing

2015-09-08

In this work, two topics of reservoir simulations are discussed. The first topic is the two-phase compositional flow simulation in hydrocarbon reservoir. The major obstacle that impedes the applicability of the simulation code is the long run time of the simulation procedure, and thus speeding up the simulation code is necessary. Two means are demonstrated to address the problem: parallelism in physical space and the application of sparse grids in parameter space. The parallel code can gain satisfactory scalability, and the sparse grids can remove the bottleneck of flash calculations. Instead of carrying out the flash calculation in each time step of the simulation, a sparse grid approximation of all possible results of the flash calculation is generated before the simulation. Then the constructed surrogate model is evaluated to approximate the flash calculation results during the simulation. The second topic is the wormhole propagation simulation in carbonate reservoir. In this work, different from the traditional simulation technique relying on the Darcy framework, we propose a new framework called Darcy-Brinkman-Forchheimer framework to simulate wormhole propagation. Furthermore, to process the large quantity of cells in the simulation grid and shorten the long simulation time of the traditional serial code, standard domain-based parallelism is employed, using the Hypre multigrid library. In addition to that, a new technique called “experimenting field approach” to set coefficients in the model equations is introduced. In the 2D dissolution experiments, different configurations of wormholes and a series of properties simulated by both frameworks are compared. We conclude that the numerical results of the DBF framework are more like wormholes and more stable than the Darcy framework, which is a demonstration of the advantages of the DBF framework. The scalability of the parallel code is also evaluated, and good scalability can be achieved. Finally, a mixed

Synchronization of grid-connected renewable energy sources under highly distorted voltages and unbalanced grid faults

DEFF Research Database (Denmark)

Hadjidemetriou, Lenos; Kyriakides, Elias; Blaabjerg, Frede

2013-01-01

Renewable energy sources require accurate and appropriate performance not only under normal grid operation but also under abnormal and faulty grid conditions according to the modern grid codes. This paper proposes a novel phase-locked loop algorithm (MSHDC-PLL), which can enable the fast...... and dynamic synchronization of the interconnected renewable energy system under unbalanced grid faults and under highly harmonic distorted voltage. The outstanding performance of the suggested PLL is achieved by implementing an innovative multi-sequence/harmonic decoupling cell in order to dynamically cancel...... renewable energy systems. Therefore, the performance of the new PLL can increase the quality of the injected power under abnormal conditions and in addition enable the renewable energy systems to provide the appropriate support to the grid under balanced and unbalanced grid faults....

Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems

Science.gov (United States)

Andrade, Xavier; Strubbe, David; De Giovannini, Umberto; Larsen, Ask Hjorth; Oliveira, Micael J. T.; Alberdi-Rodriguez, Joseba; Varas, Alejandro; Theophilou, Iris; Helbig, Nicole; Verstraete, Matthieu J.; Stella, Lorenzo; Nogueira, Fernando; Aspuru-Guzik, Alán; Castro, Alberto; Marques, Miguel A. L.; Rubio, Angel

Real-space grids are a powerful alternative for the simulation of electronic systems. One of the main advantages of the approach is the flexibility and simplicity of working directly in real space where the different fields are discretized on a grid, combined with competitive numerical performance and great potential for parallelization. These properties constitute a great advantage at the time of implementing and testing new physical models. Based on our experience with the Octopus code, in this article we discuss how the real-space approach has allowed for the recent development of new ideas for the simulation of electronic systems. Among these applications are approaches to calculate response properties, modeling of photoemission, optimal control of quantum systems, simulation of plasmonic systems, and the exact solution of the Schr\\"odinger equation for low-dimensionality systems.

Steam generator and circulator model for the HELAP code

International Nuclear Information System (INIS)

Ludewig, H.

1975-07-01

An outline is presented of the work carried out in the 1974 fiscal year on the GCFBR safety research project consisting of the development of improved steam generator and circulator (steam turbine driven helium compressor) models which will eventually be inserted in the HELAP (1) code. Furthermore, a code was developed which will be used to generate steady state input for the primary and secondary sides of the steam generator. The following conclusions and suggestions for further work are made: (1) The steam-generator and circulator model are consistent with the volume and junction layout used in HELAP, (2) with minor changes these models, when incorporated in HELAP, could be used to simulate a direct cycle plant, (3) an explicit control valve model is still to be developed and would be very desirable to control the flow to the turbine during a transient (initially this flow will be controlled by using the existing check valve model); (4) the friction factor in the laminar flow region is computed inaccurately, this might cause significant errors in loss-of-flow accidents; and (5) it is felt that HELAP will still use a large amount of computer time and will thus be limited to design basis accidents without scram or loss of flow transients with and without scram. Finally it may also be used as a test bed for the development of prototype component models which would be incorporated in a more sophisticated system code, developed specifically for GCFBR's

Interpretation and code generation based on intermediate languages

DEFF Research Database (Denmark)

Kornerup, Peter; Kristensen, Bent Bruun; Madsen, Ole Lehrmann

1980-01-01

The possibility of supporting high level languages through intermediate languages to be used for direct interpretation and as intermediate forms in compilers is investigated. An accomplished project in the construction of an interpreter and a code generator using one common intermediate form...

A testing procedure for wind turbine generators based on the power grid statistical model

DEFF Research Database (Denmark)

Farajzadehbibalan, Saber; Ramezani, Mohammad Hossein; Nielsen, Peter

2017-01-01

In this study, a comprehensive test procedure is developed to test wind turbine generators with a hardware-in-loop setup. The procedure employs the statistical model of the power grid considering the restrictions of the test facility and system dynamics. Given the model in the latent space...

ADGEN: An automated adjoint code generator for large-scale sensitivity analysis

International Nuclear Information System (INIS)

Pin, F.G.; Oblow, E.M.; Horwedel, J.E.; Lucius, J.L.

1987-01-01

This paper describes a new automated system, named ADGEN, which makes use of the strengths of computer calculus to automate the costly and time-consuming calculation of derivatives in FORTRAN computer codes, and automatically generate adjoint solutions of computer codes

Equivalent Simplification Method of Micro-Grid

OpenAIRE

Cai Changchun; Cao Xiangqin

2013-01-01

The paper concentrates on the equivalent simplification method for the micro-grid system connection into distributed network. The equivalent simplification method proposed for interaction study between micro-grid and distributed network. Micro-grid network, composite load, gas turbine synchronous generation, wind generation are equivalent simplification and parallel connect into the point of common coupling. A micro-grid system is built and three phase and single phase grounded faults are per...

BBU code development for high-power microwave generators

International Nuclear Information System (INIS)

Houck, T.L.; Westenskow, G.A.; Yu, S.S.

1992-01-01

We are developing a two-dimensional, time-dependent computer code for the simulation of transverse instabilities in support of relativistic klystron-two beam accelerator research at LLNL. The code addresses transient effects as well as both cumulative and regenerative beam breakup modes. Although designed specifically for the transport of high current (kA) beams through traveling-wave structures, it is applicable to devices consisting of multiple combinations of standing-wave, traveling-wave, and induction accelerator structures. In this paper we compare code simulations to analytical solutions for the case where there is no rf coupling between cavities, to theoretical scaling parameters for coupled cavity structures, and to experimental data involving beam breakup in the two traveling-wave output structure of our microwave generator. (Author) 4 figs., tab., 5 refs

Development, validation and application of NAFA 2D-CFD code

International Nuclear Information System (INIS)

Vaidya, A.M.; Maheshwari, N.K.; Vijayan, P.K.; Saha, D.

2010-01-01

A 2D axi-symmetric code named NAFA (Version 1.0) is developed for studying the pipe flow under various conditions. It can handle laminar/ turbulent flows, with or without heat transfer, under sub-critical/super-critical conditions. The code solves for momentum, energy equations with standard k-ε turbulence model (with standard wall functions). It solves pipe flow subjected to 'velocity inlet', 'wall', 'axis' and 'pressure outlet' boundary conditions. It is validated for several cases by comparing its results with experimental data/analytical solutions/correlations. The code has excellent convergence characteristics as verified from fall of equation residual in each case. It has proven capability of generating mesh independent results for laminar as well as turbulent flows. The code is applied to supercritical flows. For supercritical flows, the effect of mesh size on prediction of heat transfer coefficient is studied. With grid refinement, the Y + reduces and reaches the limiting value of 11.63. Hence the accuracy is found to increase with grid refinement. NAFA is able to qualitatively predict the effect of heat flux and operating pressure on heat transfer coefficient. The heat transfer coefficient matches well with experimental values under various conditions. (author)

Coarse Grid Modeling of Turbine Film Cooling Flows Using Volumetric Source Terms

Science.gov (United States)

Heidmann, James D.; Hunter, Scott D.

2001-01-01

The recent trend in numerical modeling of turbine film cooling flows has been toward higher fidelity grids and more complex geometries. This trend has been enabled by the rapid increase in computing power available to researchers. However, the turbine design community requires fast turnaround time in its design computations, rendering these comprehensive simulations ineffective in the design cycle. The present study describes a methodology for implementing a volumetric source term distribution in a coarse grid calculation that can model the small-scale and three-dimensional effects present in turbine film cooling flows. This model could be implemented in turbine design codes or in multistage turbomachinery codes such as APNASA, where the computational grid size may be larger than the film hole size. Detailed computations of a single row of 35 deg round holes on a flat plate have been obtained for blowing ratios of 0.5, 0.8, and 1.0, and density ratios of 1.0 and 2.0 using a multiblock grid system to resolve the flows on both sides of the plate as well as inside the hole itself. These detailed flow fields were spatially averaged to generate a field of volumetric source terms for each conservative flow variable. Solutions were also obtained using three coarse grids having streamwise and spanwise grid spacings of 3d, 1d, and d/3. These coarse grid solutions used the integrated hole exit mass, momentum, energy, and turbulence quantities from the detailed solutions as volumetric source terms. It is shown that a uniform source term addition over a distance from the wall on the order of the hole diameter is able to predict adiabatic film effectiveness better than a near-wall source term model, while strictly enforcing correct values of integrated boundary layer quantities.

Control of Wind Turbines during Symmetrical and Asymmetrical Grid Faults

DEFF Research Database (Denmark)

Göksu, Ömer

As installed capacity of the wind power plants (WPPs) in power system of certain countries increases, stability of the power system becomes more critical. In order to sustain stable power system operation with high share of wind power, system operators of some countries are enforcing more stringent...... grid code requirements, which are targeting to make the WPPs operate in a closer manner to the conventional power plants. Common to most of the grid codes, WPPs are required to stay connected during short-circuit grid faults, and also inject reactive current in order to support the grid voltage...... type wind turbines (WTs), in an AC connected WPP, is investigated and control algorithms are designed for minimum disrupted operation and improved grid support, for both symmetrical and asymmetrical grid faults. WTs’ response with conventional control algorithms is studied regarding the impact...

Towards Qualifiable Code Generation from a Clocked Synchronous Subset of Modelica

Directory of Open Access Journals (Sweden)

Bernhard Thiele

2015-01-01

Full Text Available So far no qualifiable automatic code generators (ACGs are available for Modelica. Hence, digital control applications can be modeled and simulated in Modelica, but require tedious additional efforts (e.g., manual reprogramming to produce qualifiable target system production code. In order to more fully leverage the potential of a model-based development (MBD process in Modelica, a qualifiable automatic code generator is needed. Typical Modelica code generation is a fairly complex process which imposes a huge development burden to any efforts of tool qualification. This work aims at mapping a Modelica subset for digital control function development to a well-understood synchronous data-flow kernel language. This kernel language allows to resort to established compilation techniques for data-flow languages which are understood enough to be accepted by certification authorities. The mapping is established by providing a translational semantics from the Modelica subset to the synchronous data-flow kernel language. However, this translation turned out to be more intricate than initially expected and has given rise to several interesting issues that require suitable design decisions regarding the mapping and the language subset.

Power Quality Improvement Of Grid Integrated Type I Wind Turbine Generation System Operating as DSTATCOM by d-q Control Method

Directory of Open Access Journals (Sweden)

S V S Phani Kumar.Ch

2016-06-01

Full Text Available In recent years with the excessive consumption of electrical energy, the incongruity between generation and demand, the irrational structure of World’s energy as well as the environmental pollution have become progressively more evident. It has become crucial for ecological development to reduce the consumption of conventional energy and to enhance the development and utilization of renewable energy. Wind energy and Solar are unlimited supply of renewable energy and it has no pollution. But this concept suffer from the power quality issues from grid and generator side, this paper presents a control strategy for achieving maximum benefits from these grid-interfacing inverter when installed in 3-phase 4-wire distribution systems. The inverter can be controlled to perform as a multi-function device by incorporating active power filter functionality. The inverter can thus be utilized as: 1 power converter to inject power generated from RES to the grid and 2 shunt APF (Active Power Filter to compensate current unbalance, load current harmonics, load reactive power demand and load neutral current. All of these functions may be accomplished either individually or simultaneously. With such a control, the combination of grid-interfacing inverter and the 3-phase 4-wire linear/non-linear unbalanced load at point of common coupling appears as balanced linear load to the grid. The Paper propose design of 500kW Type I Wind Generation System 250kW each with Four Leg Inverter Controlled by d-q technique operated as DSTATCOM connected to 415V 4 wire Grid and also the results are compared with conventional Unit Vector Control. The proposed d-q method reduces the %THD of system to 1.97% from 24.12% where Unit Vector Control is of 3.94% which was on higher side , this is simulated in MATLAB/SIMULINK.

New Generation GridPix: Development and characterisation of pixelated gaseous detectors based on the Timepix3 chip

CERN Document Server

AUTHOR|(CDS)2082958; Hessey, Nigel

Due to the increasing demands of high energy physics experiments there is a need for particle detectors which enable high precision measurements. In this regard, the GridPix detector is a novel detector concept which combines the benefits of a pixel chip with an integrated gas amplification structure. The resulting unit is a detector sensitive to single electrons with a great potential for particle tracking and energy loss measurements. This thesis is focusing on the development of a new generation of GridPix detectors based on the Timepix3 chip, which implements a high resolution Time to Digital Converter (TDC) in each pixel. After an introductory chapter describing the motivation behind GridPix, the manuscript presents the physics of gaseous detectors in chapter 2 along with the gaseous detectors used for particle tracking in chapter 3. Chapters 4 and 5 are focusing on the tracking performance of GridPix detectors. Chapter 4 presents results obtained with a GridPix detector based on a small scale prototy...

Thermal Behavior of Doubly-Fed Induction Generator Wind Turbine System during Balanced Grid Fault

DEFF Research Database (Denmark)

Zhou, Dao; Blaabjerg, Frede; Lau, Mogens

2014-01-01

Ride-through capabilities of the doubly-fed induction generator (DFIG) during grid fault have been studied a lot. However, the thermal performance of the power device during this transient period is seldom investigated. In this paper, the dynamic model for the DFIG and the influence of the rotor...

An Optimal Integrated Control Scheme for Permanent Magnet Synchronous Generator-Based Wind Turbines under Asymmetrical Grid Fault Conditions

Directory of Open Access Journals (Sweden)

Dan Wang

2016-04-01

Full Text Available In recent years, the increasing penetration level of wind energy into power systems has brought new issues and challenges. One of the main concerns is the issue of dynamic response capability during outer disturbance conditions, especially the fault-tolerance capability during asymmetrical faults. In order to improve the fault-tolerance and dynamic response capability under asymmetrical grid fault conditions, an optimal integrated control scheme for the grid-side voltage-source converter (VSC of direct-driven permanent magnet synchronous generator (PMSG-based wind turbine systems is proposed in this paper. The optimal control strategy includes a main controller and an additional controller. In the main controller, a double-loop controller based on differential flatness-based theory is designed for grid-side VSC. Two parts are involved in the design process of the flatness-based controller: the reference trajectories generation of flatness output and the implementation of the controller. In the additional control aspect, an auxiliary second harmonic compensation control loop based on an improved calculation method for grid-side instantaneous transmission power is designed by the quasi proportional resonant (Quasi-PR control principle, which is able to simultaneously restrain the second harmonic components in active power and reactive power injected into the grid without the respective calculation for current control references. Moreover, to reduce the DC-link overvoltage during grid faults, the mathematical model of DC-link voltage is analyzed and a feedforward modified control factor is added to the traditional DC voltage control loop in grid-side VSC. The effectiveness of the optimal control scheme is verified in PSCAD/EMTDC simulation software.

MeshVoro: A Three-Dimensional Voronoi Mesh Building Tool for the TOUGH Family of Codes

Energy Technology Data Exchange (ETDEWEB)

Freeman, C. M.; Boyle, K. L.; Reagan, M.; Johnson, J.; Rycroft, C.; Moridis, G. J.

2013-09-30

Few tools exist for creating and visualizing complex three-dimensional simulation meshes, and these have limitations that restrict their application to particular geometries and circumstances. Mesh generation needs to trend toward ever more general applications. To that end, we have developed MeshVoro, a tool that is based on the Voro (Rycroft 2009) library and is capable of generating complex threedimensional Voronoi tessellation-based (unstructured) meshes for the solution of problems of flow and transport in subsurface geologic media that are addressed by the TOUGH (Pruess et al. 1999) family of codes. MeshVoro, which includes built-in data visualization routines, is a particularly useful tool because it extends the applicability of the TOUGH family of codes by enabling the scientifically robust and relatively easy discretization of systems with challenging 3D geometries. We describe several applications of MeshVoro. We illustrate the ability of the tool to straightforwardly transform a complex geological grid into a simulation mesh that conforms to the specifications of the TOUGH family of codes. We demonstrate how MeshVoro can describe complex system geometries with a relatively small number of grid blocks, and we construct meshes for geometries that would have been practically intractable with a standard Cartesian grid approach. We also discuss the limitations and appropriate applications of this new technology.

Generation of cross-sections and reference solutions using the code Serpent

International Nuclear Information System (INIS)

Gomez T, A. M.; Delfin L, A.; Del Valle G, E.

2012-10-01

Serpent is a code that solves the neutron transport equations using the Monte Carlo method that besides generating reference solutions in stationary state for complex geometry problems, has been specially designed for physical applications of cells, what includes the generation of homogenized cross-sections for several energy groups. In this work a calculation methodology is described using the code Serpent to generate the necessary cross-sections to carry out calculations with the code TNXY, developed in 1993 in the Nuclear Engineering Department of the Instituto Politecnico Nacional (Mexico) by means of an interface programmed in Octave. The computation program TNXY solves the neutron transport equations for several energy groups in stationary state and geometry X Y using the Discreet Ordinates method (S N ). To verify and to validate the methodology the results of TNXY were compared with those calculated by Serpent giving minor differences to 0.55% in the value of the multiplication factor. (Author)

A Study of Wind Farm Stabilization Using DFIG or STATCOM Considering Grid Requirements

Directory of Open Access Journals (Sweden)

K. E Okedu

2010-01-01

Full Text Available Recently, the grid codes require taking into account the reactive power of the wind farm in order to contribute to the networkstability, thus operating the wind farm as active compensator devices. This paper presents a comparative study of stabilizinga wind farm using (Doubly Fed Induction Generators DFIGs or using a (Static Synchronous Compensator STATCOM duringwind speed change and grid fault. Simulation results show that the wind farm could be effectively stabilized with bothsystems, but at a reduced cost with the DFIGs system because it can provide reactive power through its frequency converterswithout an external reactive power compensation unit like the STATCOM system significant.

Development of a smart DC grid model

Energy Technology Data Exchange (ETDEWEB)

Dalimunthe, Amty Ma’rufah Ardhiyah; Mindara, Jajat Yuda; Panatarani, Camellia; Joni, I. Made, E-mail: imadejoni@phys.unpad.ac.id [Lab. of Instrumentation System and Functional Material Processing, Physics Department, Faculty of Mathematics and Natural Sciences, Padjadjaran University, Jl. Raya Bandung-Sumedang KM21, Jatinangor 45363, Jawa Barat (Indonesia)

2016-03-11

Smart grid and distributed generation should be the solution of the global climate change and the crisis energy of the main source of electrical power generation which is fossil fuel. In order to meet the rising electrical power demand and increasing service quality demands, as well as reduce pollution, the existing power grid infrastructure should be developed into a smart grid and distributed power generation which provide a great opportunity to address issues related to energy efficiency, energy security, power quality and aging infrastructure systems. The conventional of the existing distributed generation system is an AC grid while for a renewable resources requires a DC grid system. This paper explores the model of smart DC grid by introducing a model of smart DC grid with the stable power generation give a minimal and compressed circuitry that can be implemented very cost-effectively with simple components. The PC based application software for controlling was developed to show the condition of the grid and to control the grid become ‘smart’. The model is then subjected to a severe system perturbation, such as incremental change in loads to test the performance of the system again stability. It is concluded that the system able to detect and controlled the voltage stability which indicating the ability of power system to maintain steady voltage within permissible rangers in normal condition.

Development of a smart DC grid model

International Nuclear Information System (INIS)

Dalimunthe, Amty Ma’rufah Ardhiyah; Mindara, Jajat Yuda; Panatarani, Camellia; Joni, I. Made

2016-01-01

Smart grid and distributed generation should be the solution of the global climate change and the crisis energy of the main source of electrical power generation which is fossil fuel. In order to meet the rising electrical power demand and increasing service quality demands, as well as reduce pollution, the existing power grid infrastructure should be developed into a smart grid and distributed power generation which provide a great opportunity to address issues related to energy efficiency, energy security, power quality and aging infrastructure systems. The conventional of the existing distributed generation system is an AC grid while for a renewable resources requires a DC grid system. This paper explores the model of smart DC grid by introducing a model of smart DC grid with the stable power generation give a minimal and compressed circuitry that can be implemented very cost-effectively with simple components. The PC based application software for controlling was developed to show the condition of the grid and to control the grid become ‘smart’. The model is then subjected to a severe system perturbation, such as incremental change in loads to test the performance of the system again stability. It is concluded that the system able to detect and controlled the voltage stability which indicating the ability of power system to maintain steady voltage within permissible rangers in normal condition.

Integration of Hybrid PV/Wind Generation System Using Fuzzy MPPT in Grid Connected System for Remote Area

Directory of Open Access Journals (Sweden)

Soedibyo

2016-01-01

Full Text Available Photovoltaic and wind are renewable energy resources that widely used and grow rapidly in fulfilling electricity demand. Powers from both technologies depend on sunlight intensity and wind speed. For small scale power generation, DC voltage from both technologies is low and requires step-up converter to raise DC voltage ratio before converted into AC voltage. To optimize this system, step-up converter must have high ratio and efficiency to a distance of wide voltage input. This paper proposed an operation simulation and arrangement of DC-DC converter along with DC-AC from hybrid source PV-Wind which integrated to grid utilities without using storage device. High Gain Integrated Cascade Boost (HGICB is DC-DC converter that has quadratic voltage ratio and used in this research. Then DC link connected to Voltage Source Inverter (VSI which interconnected with utility grid and controlled by current control method. The total installed capacity of hybrid source is 4.4 kW. Wind turbine uses PMSG along with full bridge rectifier. To maximize and stabilize the generated power, MPPT fuzzy is used. Result from the simulation shows that converter capable to maintain maximum power whether from PV and wind turbine which canalized to utility grid in various irradiation condition, wind speed, and grid load alteration.

Presenting a multi-objective generation scheduling model for pricing demand response rate in micro-grid energy management

International Nuclear Information System (INIS)

Aghajani, G.R.; Shayanfar, H.A.; Shayeghi, H.

2015-01-01

Highlights: • Using DRPs to cover the uncertainties resulted from power generation by WT and PV. • Proposing the use of price-offer packages and amount of DR for implement DRPs. • Considering a multi-objective scheduling model and use of MOPSO algorithm. - Abstract: In this paper, a multi-objective energy management system is proposed in order to optimize micro-grid (MG) performance in a short-term in the presence of Renewable Energy Sources (RESs) for wind and solar energy generation with a randomized natural behavior. Considering the existence of different types of customers including residential, commercial, and industrial consumers can participate in demand response programs. As with declare their interruptible/curtailable demand rate or select from among different proposed prices so as to assist the central micro-grid control in terms of optimizing micro-grid operation and covering energy generation uncertainty from the renewable sources. In this paper, to implement Demand Response (DR) schedules, incentive-based payment in the form of offered packages of price and DR quantity collected by Demand Response Providers (DRPs) is used. In the typical micro-grid, different technologies including Wind Turbine (WT), PhotoVoltaic (PV) cell, Micro-Turbine (MT), Full Cell (FC), battery hybrid power source and responsive loads are used. The simulation results are considered in six different cases in order to optimize operation cost and emission with/without DR. Considering the complexity and non-linearity of the proposed problem, Multi-Objective Particle Swarm Optimization (MOPSO) is utilized. Also, fuzzy-based mechanism and non-linear sorting system are applied to determine the best compromise considering the set of solutions from Pareto-front space. The numerical results represented the effect of the proposed Demand Side Management (DSM) scheduling model on reducing the effect of uncertainty obtained from generation power and predicted by WT and PV in a MG.

A General Constant Power Generation Algorithm for Photovoltaic Systems

DEFF Research Database (Denmark)

Tafti, Hossein Dehghani; Maswood, Ali Iftekhar; Konstantinou, Georgios

2018-01-01

Photovoltaic power plants (PVPPs) typically operate by tracking the maximum power point in order to maximize conversion efficiency. However, with the continuous increase of installed grid-connected PVPPs, power system operators have been experiencing new challenges, like overloading, overvoltages...... on a hysteresis band controller in order to obtain fast dynamic response under transients and low power oscillation during steady-state operation. The performance of the proposed algorithm for both single- and two-stage PVPPs is examined on a 50-kVA simulation setup of these topologies. Moreover, experimental...... and operation during grid voltage disturbances. Consequently, constant power generation (CPG) is imposed by grid codes. An algorithm for the calculation of the photovoltaic panel voltage reference, which generates a constant power from the PVPP, is introduced in this paper. The key novelty of the proposed...

On the use of SERPENT Monte Carlo code to generate few group diffusion constants

Energy Technology Data Exchange (ETDEWEB)

Piovezan, Pamela, E-mail: pamela.piovezan@ctmsp.mar.mil.b [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), Sao Paulo, SP (Brazil); Carluccio, Thiago; Domingos, Douglas Borges; Rossi, Pedro Russo; Mura, Luiz Felipe, E-mail: fermium@cietec.org.b, E-mail: thiagoc@ipen.b [Fermium Tecnologia Nuclear, Sao Paulo, SP (Brazil); Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

The accuracy of diffusion reactor codes strongly depends on the quality of the groups constants processing. For many years, the generation of such constants was based on 1-D infinity cell transport calculations. Some developments using collision probability or the method of characteristics allow, nowadays, 2-D assembly group constants calculations. However, these 1-D and 2-D codes how some limitations as , for example, on complex geometries and in the neighborhood of heavy absorbers. On the other hand, since Monte Carlos (MC) codes provide accurate neutro flux distributions, the possibility of using these solutions to provide group constants to full-core reactor diffusion simulators has been recently investigated, especially for the cases in which the geometry and reactor types are beyond the capability of the conventional deterministic lattice codes. The two greatest difficulties on the use of MC codes to group constant generation are the computational costs and the methodological incompatibility between analog MC particle transport simulation and deterministic transport methods based in several approximations. The SERPENT code is a 3-D continuous energy MC transport code with built-in burnup capability that was specially optimized to generate these group constants. In this work, we present the preliminary results of using the SERPENT MC code to generate 3-D two-group diffusion constants for a PWR like assembly. These constants were used in the CITATION diffusion code to investigate the effects of the MC group constants determination on the neutron multiplication factor diffusion estimate. (author)

Generating Code with Polymorphic let: A Ballad of Value Restriction, Copying and Sharing

Directory of Open Access Journals (Sweden)

Oleg Kiselyov

2017-02-01

Full Text Available Getting polymorphism and effects such as mutation to live together in the same language is a tale worth telling, under the recurring refrain of copying vs. sharing. We add new stanzas to the tale, about the ordeal to generate code with polymorphism and effects, and be sure it type-checks. Generating well-typed-by-construction polymorphic let-expressions is impossible in the Hindley-Milner type system: even the author believed that. The polymorphic-let generator turns out to exist. We present its derivation and the application for the lightweight implementation of quotation via a novel and unexpectedly simple source-to-source transformation to code-generating combinators. However, generating let-expressions with polymorphic functions demands more than even the relaxed value restriction can deliver. We need a new deal for let-polymorphism in ML. We conjecture the weaker restriction and implement it in a practically-useful code-generation library. Its formal justification is formulated as the research program.

Study on random number generator in Monte Carlo code

International Nuclear Information System (INIS)

Oya, Kentaro; Kitada, Takanori; Tanaka, Shinichi

2011-01-01

The Monte Carlo code uses a sequence of pseudo-random numbers with a random number generator (RNG) to simulate particle histories. A pseudo-random number has its own period depending on its generation method and the period is desired to be long enough not to exceed the period during one Monte Carlo calculation to ensure the correctness especially for a standard deviation of results. The linear congruential generator (LCG) is widely used as Monte Carlo RNG and the period of LCG is not so long by considering the increasing rate of simulation histories in a Monte Carlo calculation according to the remarkable enhancement of computer performance. Recently, many kinds of RNG have been developed and some of their features are better than those of LCG. In this study, we investigate the appropriate RNG in a Monte Carlo code as an alternative to LCG especially for the case of enormous histories. It is found that xorshift has desirable features compared with LCG, and xorshift has a larger period, a comparable speed to generate random numbers, a better randomness, and good applicability to parallel calculation. (author)

Application of Chimera Composite Grid Scheme to Ship Appendages

National Research Council Canada - National Science Library

Lin, Cheng-Wen

1995-01-01

.... The chimera scheme of grid generation uses a system of relatively simple grids. The grids each define a particular component of the overall geometry, making the initial grid generation much simpler...

A Theoretical Secure Enterprise Architecture for Multi Revenue Generating Smart Grid Sub Electric Infrastructure

Science.gov (United States)

Chaudhry, Hina

2013-01-01

This study is a part of the smart grid initiative providing electric vehicle charging infrastructure. It is a refueling structure, an energy generating photovoltaic system and charge point electric vehicle charging station. The system will utilize advanced design and technology allowing electricity to flow from the site's normal electric service…

Smart Solar Grid. Integration of high penetration of photovoltaic in municipal low voltage distribution grids; Smart Solar Grid. Integration hoher Anteile von Photovoltaik in kommunalen Niederspannungsverteilnetzen

Energy Technology Data Exchange (ETDEWEB)

Ruf, Holger; Heilscher, Gerd [Hochschule Ulm (Germany); Meier, Florian [SWU Netze GmbH, Ulm (Germany)

2012-07-01

The high rate of decentralized generation in low voltage grids especially photovoltaic (PV) put the distribution grid operators to new challenges. Grid operation and grid planning have to respect the volatility and dynamic of decentralized generation now and in the future and adapt their previous proceedings. In the frame of the project Smart Solar Grid was a test site defined in the grid area of the DSO Stadtwerke Ulm/Neu-Ulm GmbH (SWU) to analyze the impact of the PV rise and possible solutions for the grid planning in the future. The first analysis based upon secondly measurements of the first test site. From this were statistical evaluation of the load flows and power variations done. Furthermore were the roof potential analysis results of the test site validated. These data are the base for the development of a forecast system for grid condition parameter. (orig.)

Design and Implementation of a High Quality Power Supply Scheme for Distributed Generation in a Micro-Grid

Directory of Open Access Journals (Sweden)

Mingchao Xia

2013-09-01

Full Text Available A low carbon, high efficiency and high quality power supply scheme for Distributed Generation (DG in a micro-grid is presented. A three-phase, four-leg DG grid-interfacing converter based on the improved structure of a Unified Power Quality Conditioner (UPQC, including a series converter and a parallel converter is adopted, and improved indirect and direct control strategies are proposed. It can be observed that these strategies effectively compensate for voltage sags, voltage swells and voltage distortion, as well as voltage power quality problems resulting from the nonlinear and unbalanced loads in a micro-grid. While solving the coupling interference from series–parallel, the grid-interfacing converter can achieve proper load power sharing in a micro-grid. In particular, an improved minimum-energy compensation method is proposed that can overcome the conventional compensation algorithm defects, ensure the load voltage’s phase angle stability, improve the voltage compensating ability and range, reduce the capacity and cost of converters, and reduce the shock of micro-grid switching between grid-connected mode and islanded mode. Moreover, the advantages/disadvantages and application situation of the two improved control strategies are analyzed. Finally, the performance of the proposed control strategies has been verified through a MATLAB/Simulink simulation under various operating conditions.

Parameterized Finite Element Modeling and Buckling Analysis of Six Typical Composite Grid Cylindrical Shells

Science.gov (United States)

Lai, Changliang; Wang, Junbiao; Liu, Chuang

2014-10-01

Six typical composite grid cylindrical shells are constructed by superimposing three basic types of ribs. Then buckling behavior and structural efficiency of these shells are analyzed under axial compression, pure bending, torsion and transverse bending by finite element (FE) models. The FE models are created by a parametrical FE modeling approach that defines FE models with original natural twisted geometry and orients cross-sections of beam elements exactly. And the approach is parameterized and coded by Patran Command Language (PCL). The demonstrations of FE modeling indicate the program enables efficient generation of FE models and facilitates parametric studies and design of grid shells. Using the program, the effects of helical angles on the buckling behavior of six typical grid cylindrical shells are determined. The results of these studies indicate that the triangle grid and rotated triangle grid cylindrical shell are more efficient than others under axial compression and pure bending, whereas under torsion and transverse bending, the hexagon grid cylindrical shell is most efficient. Additionally, buckling mode shapes are compared and provide an understanding of composite grid cylindrical shells that is useful in preliminary design of such structures.

Application of synchronous grid-connected controller in the wind-solar-storage micro grid

OpenAIRE

Li, Hua; Ren, Yongfeng; Li, Le; Luo, Zhenpeng

2016-01-01

Recently, there has been an increasing interest in using distributed generators (DG) not only to inject power into the grid, but also to enhance the power quality. In this study, a space voltage pulse width modulation (SVPWM) control method is proposed for a synchronous grid-connected controller in a wind-solar-storage micro grid. This method is based on the appropriate topology of the synchronous controller. The wind-solar-storage micro grid is controlled to reconnect to the grid synchronous...

Grids for Kids gives next-generation IT an early start

CERN Multimedia

2008-01-01

"Grids for Kids gives children a crash course in grid computing," explains co-organiser Anna Cook of the Enabling Grids for E-sciencE project. "We introduce them to concepts such as middleware, parallel processing and supercomputing, and give them opportunities for hands-on learning.

Renewable generation and demand response integration in micro-grids. Development of a new energy management and control system

Energy Technology Data Exchange (ETDEWEB)

Alvarez-Bel, C.; Escriva-Escriva, G.; Alcazar-Ortega, M. [Institute for Energy Engineering, Universitat Politecnica de Valencia, Valencia (Spain)

2013-11-15

The aim of this research resides in the development of an energy management and control system to control a micro-grid based on the use of renewable generation and demand resources to introduce the application of demand response concepts to the management of micro-grids in order to effectively integrate the demand side as an operation resource for the grid and improve energy efficiency of the elements. As an additional result, the evaluation of reductions in the total amount of CO2 emitted into the atmosphere due to the improvement of the energy efficiency of the system is assessed.

SCALEA-G: A Unified Monitoring and Performance Analysis System for the Grid

Directory of Open Access Journals (Sweden)

Hong-Linh Truong

2004-01-01

Full Text Available This paper describes SCALEA-G, a unified monitoring and performance analysis system for the Grid. SCALEA-G is implemented as a set of grid services based on the Open Grid Services Architecture (OGSA. SCALEA-G provides an infrastructure for conducting online monitoring and performance analysis of a variety of Grid services including computational and network resources, and Grid applications. Both push and pull models are supported, providing flexible and scalable monitoring and performance analysis. Source code and dynamic instrumentation are implemented to perform profiling and monitoring of Grid applications. A novel instrumentation request language for dynamic instrumentation and a standardized intermediate representation for binary code have been developed to facilitate the interaction between client and instrumentation services.

Short circuit signatures from different wind turbine generator types

DEFF Research Database (Denmark)

Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

2011-01-01

Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay...... of the protections. The following wind turbine generator during faults have been studied: (i) induction generator, (ii) induction generator with variable rotor resistance (iii) converter-fed rotor (often referred to as DFIG) and (iv) full scale converter. To make a clear comparison and performance analysis during...... faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant...

A Subdivision Method to Unify the Existing Latitude and Longitude Grids

Directory of Open Access Journals (Sweden)

Chengqi Cheng

2016-09-01

Full Text Available As research on large regions of earth progresses, many geographical subdivision grids have been established for various spatial applications by different industries and disciplines. However, there is no clear relationship between the different grids and no consistent spatial reference grid that allows for information exchange and comprehensive application. Sharing and exchange of data across departments and applications are still at a bottleneck. It would represent a significant step forward to build a new grid model that is inclusive of or compatible with most of the existing geodesic grids and that could support consolidation and exchange within existing data services. This study designs a new geographical coordinate global subdividing grid with one dimension integer coding on a 2n tree (GeoSOT that has 2n coordinate subdivision characteristics (global longitude and latitude subdivision and can form integer hierarchies at degree, minute, and second levels. This grid has the multi-dimensional quadtree hierarchical characteristics of a digital earth grid, but also provides good consistency with applied grids, such as those used in mapping, meteorology, oceanography and national geographical, and three-dimensional digital earth grids. No other existing grid codes possess these characteristics.

Simulation of vibration modes of the fuel rod damaged due to the grid-to-rod fretting wear

International Nuclear Information System (INIS)

Kim, Kyu Tae; Kim, Kyeong Koo; Jang, Young Ki; Lee, Kyou Seok

1997-01-01

The flow-induced fuel fretting wear observed in some PWRs mainly proceeds in the grid-to-rod contact positions. The grid-to-rod fretting wear in the PWR fuel assembly depends on grid-to-rod gap size, its axial profile and flow-induced vibration. This paper describes the GRIDFORCE program which generates the axially dependent grid-to-rod gap size as a function of burnup. The axially dependent grid-to-rod gap profiles are employed to predict the fuel rod vibration mode shapes by the ANSYS code. With the help of the Paidousis empirical formula, this paper also calculates the fuel rod vibration amplitudes under various supporting conditions, which indicates that the increase of the number of unsupported mid-grids will increase the fuel rod vibration amplitude. On the other hand, the comparison of the predicted vibration mode shapes and the observed mid-grid fretting wear pattern indicates that the 1st and 6th vibration mode shapes under the supporting inactive condition at the mid-grids can simulate the observed mid-grid fretting wear profile. This paper also proposes design guidelines against the grid-to-rod fretting wear. (author). 3 refs., 8 figs

Short-term hydro generation scheduling of Xiluodu and Xiangjiaba cascade hydropower stations using improved binary-real coded bee colony optimization algorithm

International Nuclear Information System (INIS)

Lu, Peng; Zhou, Jianzhong; Wang, Chao; Qiao, Qi; Mo, Li

2015-01-01

Highlights: • STHGS problem is decomposed into two parallel sub-problems of UC and ELD. • Binary coded BCO is used to solve UC sub-problem with 0–1 discrete variables. • Real coded BCO is used to solve ELD sub-problem with continuous variables. • Some heuristic repairing strategies are designed to handle various constraints. • The STHGS of Xiluodu and Xiangjiaba cascade stations is solved by IB-RBCO. - Abstract: Short-term hydro generation scheduling (STHGS) of cascade hydropower stations is a typical nonlinear mixed integer optimization problem to minimize the total water consumption while simultaneously meeting the grid requirements and other hydraulic and electrical constraints. In this paper, STHGS problem is decomposed into two parallel sub-problems of unit commitment (UC) and economic load dispatch (ELD), and the methodology of improved binary-real coded bee colony optimization (IB-RBCO) algorithm is proposed to solve them. Firstly, the improved binary coded BCO is used to solve the UC sub-problem with 0–1 discrete variables, and the heuristic repairing strategy for unit state constrains is applied to generate the feasible unit commitment schedule. Then, the improved real coded BCO is used to solve the ELD sub-problem with continuous variables, and an effective method is introduced to handle various unit operation constraints. Especially, the new updating strategy of DE/best/2/bin method with dynamic parameter control mechanism is applied to real coded BCO to improve the search ability of IB-RBCO. Finally, to verify the feasibility and effectiveness of the proposed IB-RBCO method, it is applied to solve the STHGS problem of Xiluodu and Xiangjiaba cascaded hydropower stations, and the simulating results are compared with other intelligence algorithms. The simulation results demonstrate that the proposed IB-RBCO method can get higher-quality solutions with less water consumption and shorter calculating time when facing the complex STHGS problem

Streamline integration as a method for two-dimensional elliptic grid generation

Energy Technology Data Exchange (ETDEWEB)

Wiesenberger, M., E-mail: Matthias.Wiesenberger@uibk.ac.at [Institute for Ion Physics and Applied Physics, Universität Innsbruck, A-6020 Innsbruck (Austria); Held, M. [Institute for Ion Physics and Applied Physics, Universität Innsbruck, A-6020 Innsbruck (Austria); Einkemmer, L. [Numerical Analysis group, Universität Innsbruck, A-6020 Innsbruck (Austria)

2017-07-01

We propose a new numerical algorithm to construct a structured numerical elliptic grid of a doubly connected domain. Our method is applicable to domains with boundaries defined by two contour lines of a two-dimensional function. Furthermore, we can adapt any analytically given boundary aligned structured grid, which specifically includes polar and Cartesian grids. The resulting coordinate lines are orthogonal to the boundary. Grid points as well as the elements of the Jacobian matrix can be computed efficiently and up to machine precision. In the simplest case we construct conformal grids, yet with the help of weight functions and monitor metrics we can control the distribution of cells across the domain. Our algorithm is parallelizable and easy to implement with elementary numerical methods. We assess the quality of grids by considering both the distribution of cell sizes and the accuracy of the solution to elliptic problems. Among the tested grids these key properties are best fulfilled by the grid constructed with the monitor metric approach. - Graphical abstract: - Highlights: • Construct structured, elliptic numerical grids with elementary numerical methods. • Align coordinate lines with or make them orthogonal to the domain boundary. • Compute grid points and metric elements up to machine precision. • Control cell distribution by adaption functions or monitor metrics.

Grid Transmission Expansion Planning Model Based on Grid Vulnerability

Science.gov (United States)

Tang, Quan; Wang, Xi; Li, Ting; Zhang, Quanming; Zhang, Hongli; Li, Huaqiang

2018-03-01

Based on grid vulnerability and uniformity theory, proposed global network structure and state vulnerability factor model used to measure different grid models. established a multi-objective power grid planning model which considering the global power network vulnerability, economy and grid security constraint. Using improved chaos crossover and mutation genetic algorithm to optimize the optimal plan. For the problem of multi-objective optimization, dimension is not uniform, the weight is not easy given. Using principal component analysis (PCA) method to comprehensive assessment of the population every generation, make the results more objective and credible assessment. the feasibility and effectiveness of the proposed model are validated by simulation results of Garver-6 bus system and Garver-18 bus.

Improvements to the COBRA-TF (EPRI) computer code for steam generator analysis. Final report

International Nuclear Information System (INIS)

Stewart, C.W.; Barnhart, J.S.; Koontz, A.S.

1980-09-01

The COBRA-TF (EPRI) code has been improved and extended for pressurized water reactor steam generator analysis. New features and models have been added in the areas of subcooled boiling and heat transfer, turbulence, numerics, and global steam generator modeling. The code's new capabilities are qualified against selected experimental data and demonstrated for typical global and microscale steam generator analysis

Grid pulser

International Nuclear Information System (INIS)

Jansweijer, P.P.M.; Es, J.T. van.

1990-01-01

This report describes a fast pulse generator. This generator delivers a high-voltage pulse of at most 6000 V with a rise time being smaller than 50 nS. this results in a slew rate of more than 120.000 volts per μS. The pulse generator is used to control the grid of the injector of the electron accelerator MEA. The capacity of this grid is about 60 pF. In order to charge this capacity up to 6000 volts in 50 nS a current of 8 ampere is needed. The maximal pulse length is 50 μS with a repeat frequency of 500 Hz. During this 50 μS the stability of the pulse amplitude is better than 0.1%. (author). 20 figs

Implementing the WebSocket Protocol Based on Formal Modelling and Automated Code Generation

DEFF Research Database (Denmark)

Simonsen, Kent Inge; Kristensen, Lars Michael

2014-01-01

with pragmatic annotations for automated code generation of protocol software. The contribution of this paper is an application of the approach as implemented in the PetriCode tool to obtain protocol software implementing the IETF WebSocket protocol. This demonstrates the scalability of our approach to real...... protocols. Furthermore, we perform formal verification of the CPN model prior to code generation, and test the implementation for interoperability against the Autobahn WebSocket test-suite resulting in 97% and 99% success rate for the client and server implementation, respectively. The tests show...

Code Generation for Protocols from CPN models Annotated with Pragmatics

DEFF Research Database (Denmark)

Simonsen, Kent Inge; Kristensen, Lars Michael; Kindler, Ekkart

software implementation satisfies the properties verified for the model. Coloured Petri Nets (CPNs) have been widely used to model and verify protocol software, but limited work exists on using CPN models of protocol software as a basis for automated code generation. In this report, we present an approach...... modelling languages, MDE further has the advantage that models are amenable to model checking which allows key behavioural properties of the software design to be verified. The combination of formally verified models and automated code generation contributes to a high degree of assurance that the resulting...... for generating protocol software from a restricted class of CPN models. The class of CPN models considered aims at being descriptive in that the models are intended to be helpful in understanding and conveying the operation of the protocol. At the same time, a descriptive model is close to a verifiable version...

Modern control strategies of doubly-fed induction generator based wind turbine system

DEFF Research Database (Denmark)

Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

2016-01-01

A doubly-fed induction generator (DFIG) based configuration is still preferred by wind turbine manufactures due to the cost-effective power converter and independent control of the active power and reactive power. To cope with stricter grid codes (e.g. reactive power compensation, low voltage ride......, with the control targets of the smooth active and reactive power or the balances and sinusoidal current of the rotor-side converter and the grid-side converter. Finally, a bandwidth based repetitive controller is evaluated to improve the DFIG system's robustness against grid frequency deviation....

Some advanced parametric methods for assessing waveform distortion in a smart grid with renewable generation

Science.gov (United States)

Alfieri, Luisa

2015-12-01

Power quality (PQ) disturbances are becoming an important issue in smart grids (SGs) due to the significant economic consequences that they can generate on sensible loads. However, SGs include several distributed energy resources (DERs) that can be interconnected to the grid with static converters, which lead to a reduction of the PQ levels. Among DERs, wind turbines and photovoltaic systems are expected to be used extensively due to the forecasted reduction in investment costs and other economic incentives. These systems can introduce significant time-varying voltage and current waveform distortions that require advanced spectral analysis methods to be used. This paper provides an application of advanced parametric methods for assessing waveform distortions in SGs with dispersed generation. In particular, the Standard International Electrotechnical Committee (IEC) method, some parametric methods (such as Prony and Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT)), and some hybrid methods are critically compared on the basis of their accuracy and the computational effort required.

The electricity grid as a marketplace. Mannheim tests virtual energy market for generators, consumers and grid operators; Das Stromnetz wird zum Marktplatz. Mannheim erprobt virtuellen Energiemarkt fuer Erzeuger, Verbraucher und Netzbetreiber

Energy Technology Data Exchange (ETDEWEB)

Friedrich, Uwe

2011-07-01

In future, electricity grids will have to transport large quantities of electricity from renewable energy sources fed centrally and decentrally. Plus, we need greater reserves, storage facilities and flexibility in the electricity market due to the fluctuating supply. In the ''Modellstadt Mannheim'' project, a virtual energy marketplace is being developed for energy generators, consumers and grid operators. Customers can see the source and price of their electricity and influence them directly via the timing and extent of their consumption and the delivery from their own generation systems. This approach also includes gas, water and district heating. (orig.)

SLGRID: spectral synthesis software in the grid

Science.gov (United States)

Sabater, J.; Sánchez, S.; Verdes-Montenegro, L.

2011-11-01

SLGRID (http://www.e-ciencia.es/wiki/index.php/Slgrid) is a pilot project proposed by the e-Science Initiative of Andalusia (eCA) and supported by the Spanish e-Science Network in the frame of the European Grid Initiative (EGI). The aim of the project was to adapt the spectral synthesis software Starlight (Cid-Fernandes et al. 2005) to the Grid infrastructure. Starlight is used to estimate the underlying stellar populations (their ages and metallicities) using an optical spectrum, hence, it is possible to obtain a clean nebular spectrum that can be used for the diagnostic of the presence of an Active Galactic Nucleus (Sabater et al. 2008, 2009). The typical serial execution of the code for big samples of galaxies made it ideal to be integrated into the Grid. We obtain an improvement on the computational time of order N, being N the number of nodes available in the Grid. In a real case we obtained our results in 3 hours with SLGRID instead of the 60 days spent using Starlight in a PC. The code has already been ported to the Grid. The first tests were made within the e-CA infrastrusture and, later, itwas tested and improved with the colaboration of the CETA-CIEMAT. The SLGRID project has been recently renewed. In a future it is planned to adapt the code for the reduction of data from Integral Field Units where each dataset is composed of hundreds of spectra. Electronic version of the poster at http://www.iaa.es/~jsm/SEA2010

Flexible voltage support control for three-phase distributed generation inverters under grid fault

DEFF Research Database (Denmark)

Camacho, Antonio; Castilla, Miguel; Miret, Jaume

2013-01-01

Operators describe the behavior of the energy source, regulating voltage limits and reactive power injection to remain connected and support the grid under fault. On the basis that different kinds of voltage sags require different voltage support strategies, a flexible control scheme for three phase grid...... connected inverters is proposed. In three phase balanced voltage sags, the inverter should inject reactive power in order to raise the voltage in all phases. In one or two phase faults, the main concern of the distributed generation inverter is to equalize voltages by reducing the negative symmetric...... sequence and clear the phase jump. Due to system limitations, a balance between these two extreme policies is mandatory. Thus, over-voltage and undervoltage can be avoided, and the proposed control scheme prevents disconnection while achieving the desired voltage support service. The main contribution...

Response of MV-connected Doubly-Fed Induction Generator Wind Turbines and CHP plants to Grid Disturbances

NARCIS (Netherlands)

Karaliolios, P.; Slootweg, J.G.; Kling, W.L.

2010-01-01

Notwithstanding the positive environmental impact, the increasing penetration of Distributed Generation (DG) units connected to the distribution network raises new topics concerning the expected response of these during outages. Grid disturbances especially at the transmission level can cause the

Approximation generation for correlations in thermal-hydraulic analysis codes

International Nuclear Information System (INIS)

Pereira, Luiz C.M.; Carmo, Eduardo G.D. do

1997-01-01

A fast and precise evaluation of fluid thermodynamic and transport properties is needed for the efficient mass, energy and momentum transport phenomena simulation related to nuclear plant power generation. A fully automatic code capable to generate suitable approximation for correlations with one or two independent variables is presented. Comparison in terms of access speed and precision with original correlations currently used shows the adequacy of the approximation obtained. (author). 4 refs., 8 figs., 1 tab

A Micro-Grid Battery Storage Management

DEFF Research Database (Denmark)

Mahat, Pukar; Escribano Jiménez, Jorge; Moldes, Eloy Rodríguez

2013-01-01

An increase in number of distributed generation (DG) units in power system allows the possibility of setting-up and operating micro-grids. In addition to a number of technical advantages, micro-grid operation can also reduce running costs by optimally scheduling the generation and/or storage...... systems under its administration. This paper presents an optimized scheduling of a micro-grid battery storage system that takes into account the next-day forecasted load and generation profiles and spot electricity prices. Simulation results show that the battery system can be scheduled close to optimal...

Machine-Checked Sequencer for Critical Embedded Code Generator

Science.gov (United States)

Izerrouken, Nassima; Pantel, Marc; Thirioux, Xavier

This paper presents the development of a correct-by-construction block sequencer for GeneAuto a qualifiable (according to DO178B/ED12B recommendation) automatic code generator. It transforms Simulink models to MISRA C code for safety critical systems. Our approach which combines classical development process and formal specification and verification using proof-assistants, led to preliminary fruitful exchanges with certification authorities. We present parts of the classical user and tools requirements and derived formal specifications, implementation and verification for the correctness and termination of the block sequencer. This sequencer has been successfully applied to real-size industrial use cases from various transportation domain partners and led to requirement errors detection and a correct-by-construction implementation.

Validation of the WIMSD4M cross-section generation code with benchmark results

International Nuclear Information System (INIS)

Deen, J.R.; Woodruff, W.L.; Leal, L.E.

1995-01-01

The WIMSD4 code has been adopted for cross-section generation in support of the Reduced Enrichment Research and Test Reactor (RERTR) program at Argonne National Laboratory (ANL). Subsequently, the code has undergone several updates, and significant improvements have been achieved. The capability of generating group-collapsed micro- or macroscopic cross sections from the ENDF/B-V library and the more recent evaluation, ENDF/B-VI, in the ISOTXS format makes the modified version of the WIMSD4 code, WIMSD4M, very attractive, not only for the RERTR program, but also for the reactor physics community. The intent of the present paper is to validate the WIMSD4M cross-section libraries for reactor modeling of fresh water moderated cores. The results of calculations performed with multigroup cross-section data generated with the WIMSD4M code will be compared against experimental results. These results correspond to calculations carried out with thermal reactor benchmarks of the Oak Ridge National Laboratory (ORNL) unreflected HEU critical spheres, the TRX LEU critical experiments, and calculations of a modified Los Alamos HEU D 2 O moderated benchmark critical system. The benchmark calculations were performed with the discrete-ordinates transport code, TWODANT, using WIMSD4M cross-section data. Transport calculations using the XSDRNPM module of the SCALE code system are also included. In addition to transport calculations, diffusion calculations with the DIF3D code were also carried out, since the DIF3D code is used in the RERTR program for reactor analysis and design. For completeness, Monte Carlo results of calculations performed with the VIM and MCNP codes are also presented

Validation of the WIMSD4M cross-section generation code with benchmark results

Energy Technology Data Exchange (ETDEWEB)

Deen, J.R.; Woodruff, W.L. [Argonne National Lab., IL (United States); Leal, L.E. [Oak Ridge National Lab., TN (United States)

1995-01-01

The WIMSD4 code has been adopted for cross-section generation in support of the Reduced Enrichment Research and Test Reactor (RERTR) program at Argonne National Laboratory (ANL). Subsequently, the code has undergone several updates, and significant improvements have been achieved. The capability of generating group-collapsed micro- or macroscopic cross sections from the ENDF/B-V library and the more recent evaluation, ENDF/B-VI, in the ISOTXS format makes the modified version of the WIMSD4 code, WIMSD4M, very attractive, not only for the RERTR program, but also for the reactor physics community. The intent of the present paper is to validate the WIMSD4M cross-section libraries for reactor modeling of fresh water moderated cores. The results of calculations performed with multigroup cross-section data generated with the WIMSD4M code will be compared against experimental results. These results correspond to calculations carried out with thermal reactor benchmarks of the Oak Ridge National Laboratory (ORNL) unreflected HEU critical spheres, the TRX LEU critical experiments, and calculations of a modified Los Alamos HEU D{sub 2}O moderated benchmark critical system. The benchmark calculations were performed with the discrete-ordinates transport code, TWODANT, using WIMSD4M cross-section data. Transport calculations using the XSDRNPM module of the SCALE code system are also included. In addition to transport calculations, diffusion calculations with the DIF3D code were also carried out, since the DIF3D code is used in the RERTR program for reactor analysis and design. For completeness, Monte Carlo results of calculations performed with the VIM and MCNP codes are also presented.

Observability of Low Voltage grids

DEFF Research Database (Denmark)

Martin-Loeches, Ruben Sánchez; Iov, Florin; Kemal, Mohammed Seifu

2017-01-01

Low Voltage (LV) distribution power grids are experiencing a transformation from a passive to a more active role due to the increasing penetration of distributed generation, heat pumps and electrical vehicles. The first step towards a smarter operation of LV electrical systems is to provide grid ...... an updated state of the art on DSSE-AMI based, adaptive data collection techniques and database management system types. Moreover, the ongoing Danish RemoteGRID project is presented as a realistic case study.......Low Voltage (LV) distribution power grids are experiencing a transformation from a passive to a more active role due to the increasing penetration of distributed generation, heat pumps and electrical vehicles. The first step towards a smarter operation of LV electrical systems is to provide grid....... It becomes unrealistic to provide near real time full observability of the LV grid by applying Distribution System State Estimation (DSSE) utilizing the classical data collection and storage/preprocessing techniques. This paper investigates up-todate the observability problem in LV grids by providing...

New coding technique for computer generated holograms.

Science.gov (United States)

Haskell, R. E.; Culver, B. C.

1972-01-01

A coding technique is developed for recording computer generated holograms on a computer controlled CRT in which each resolution cell contains two beam spots of equal size and equal intensity. This provides a binary hologram in which only the position of the two dots is varied from cell to cell. The amplitude associated with each resolution cell is controlled by selectively diffracting unwanted light into a higher diffraction order. The recording of the holograms is fast and simple.

On the use of the Serpent Monte Carlo code for few-group cross section generation

International Nuclear Information System (INIS)

Fridman, E.; Leppaenen, J.

2011-01-01

Research highlights: → B1 methodology was used for generation of leakage-corrected few-group cross sections in the Serpent Monte-Carlo code. → Few-group constants generated by Serpent were compared with those calculated by Helios deterministic lattice transport code. → 3D analysis of a PWR core was performed by a nodal diffusion code DYN3D employing two-group cross section sets generated by Serpent and Helios. → An excellent agreement in the results of 3D core calculations obtained with Helios and Serpent generated cross-section libraries was observed. - Abstract: Serpent is a recently developed 3D continuous-energy Monte Carlo (MC) reactor physics burnup calculation code. Serpent is specifically designed for lattice physics applications including generation of homogenized few-group constants for full-core core simulators. Currently in Serpent, the few-group constants are obtained from the infinite-lattice calculations with zero neutron current at the outer boundary. In this study, in order to account for the non-physical infinite-lattice approximation, B1 methodology, routinely used by deterministic lattice transport codes, was considered for generation of leakage-corrected few-group cross sections in the Serpent code. A preliminary assessment of the applicability of the B1 methodology for generation of few-group constants in the Serpent code was carried out according to the following steps. Initially, the two-group constants generated by Serpent were compared with those calculated by Helios deterministic lattice transport code. Then, a 3D analysis of a Pressurized Water Reactor (PWR) core was performed by the nodal diffusion code DYN3D employing two-group cross section sets generated by Serpent and Helios. At this stage thermal-hydraulic (T-H) feedback was neglected. The DYN3D results were compared with those obtained from the 3D full core Serpent MC calculations. Finally, the full core DYN3D calculations were repeated taking into account T-H feedback and

Advanced KSNP fuel, plus7 : grid-to-rod fretting wear resistance of the plus7 spacer grids

International Nuclear Information System (INIS)

Kim, Kyu Tae; Kim, Yong Hwan; Jang, Young Ki; Choi, Joon Hyung

2003-01-01

Vibration-induced grid-to-rod fretting wear initiates at a certain critical gap correlated with a critical work rate. A critical gap between grid and rod forms due to in-reactor performance of fuel, thermal relaxation of grid spring and irradiation growth of grid strap, etc. A critical work rate may be generated by three vibration mechanisms proposed in this paper. Three vibration mechanisms have been derived with various fretting wear experience in commercial reactors as well as various out-of-pile hydraulic test results. The first active vibration mechanism is high turbulence-induced excessive fuel rod vibration with the combination of excessive grid-to-rod gap. The second active vibration mechanism is self-excited fuel assembly vibration in a low frequency range caused by hydraulically unbalanced mixing vanes of the spacer grid assembly. The third active vibration mechanism is self-excited spacer grid strap vibration in quite a high frequency range caused by some spacer grid designs. In this study, each vibration mechanism on the grid-to-rod fretting wear damage is discussed. On the other hand, the effects of various grid designs on the fretting wear damage in the commercial reactors are predicted using the long-term fretting wear test results. It is found that the larger grid-to-rod initial contact area generates the less fretting wear damage. Consequently the conformal spring of PLUS7 is superior to typical convex shaped spring with regard to fretting wear resistance since the former generates relatively larger contact area than the latter

What is a smart grid?

NARCIS (Netherlands)

Kumar, A.

2017-01-01

The Indian Smart Grid Forum defines a smart grid as "a power system capable of two-way communication between all the entities of the network-generation, transmission, distribution and the consumers". Like most work on smart grids, this view is also mainly technical. This paper aims to progress the

Flexible Control of Small Wind Turbines With Grid Failure Detection Operating in Stand-Alone and Grid-Connected Mode

DEFF Research Database (Denmark)

Teodorescu, Remus; Blaabjerg, Frede

2004-01-01

nonlinear load and excess or deficit of generated power. Grid-connection mode with current control is also enabled for the case of isolated local grid involving other dispersed power generators such as other wind turbines or diesel generators. A novel automatic mode switch method based on a phase......-to-back power conversion configuration is chosen where the generator converter uses a built-in standard flux vector control to control the speed of the turbine shaft while the grid-side converter uses a standard pulse-width modulation active rectifier control strategy implemented in a DSP controller. The design...

Actual issues concerning nuclear power plants and interconnected grid

International Nuclear Information System (INIS)

Medjimorec, D.; Brkic, S.

2004-01-01

Nuclear power plants and transmission grid have always been mutually of special relevance. In countries and/or regions where nuclear power plants are located they are almost as a rule counted among strongest nodes of the grid. Hence, they are treated as such from grid point of view in various aspects (operational, planning). In interconnected high-voltage transmission grid of European mainland, usually called UCTE interconnected system, this importance could be shown in a range of issues and several cases, particularly under present situation in which there are numerous demanding and challenging tasks put on transmission system operators, largely due to the opening of electricity markets in the most of European countries. Among these issues definitely worth of mentioning is relevant influence to both commercial paths and physical power flows, and also to exchange programmes between control areas and blocks. In this context there is also relation to cross-border transactions and mechanism applied to them. In respect to security of supply issues and future of nuclear power generation under present regulative framework of most European countries it is needed to comply with connecting conditions (and other stipulations) from national grid codes where different approaches could be observed. Furthermore, nuclear issues significantly influence approach to extension of UCTE system. In certain extent this also applies to pending re-connection of present two synchronous zones of UCTE, particularly to area of broader region directly affected with this complex process. Some of these also reflect to Croatian high-voltage transmission grid as a part of UCTE interconnected system with certain peculiarities.(author)

There is need in new generation smart grid for the space and ground energy systems

Directory of Open Access Journals (Sweden)

Ageev Alexander

2018-01-01

Full Text Available The aim of the article is to considerate the opportunities of synchronization of the space and ground systems that generate and transfer energy on the basis of new generation smart grid using. The authors substantiate the necessity of new intellectual monitoring services that assess the processes took place in "generation-transportation-distribution-consumption" space and ground systems. This is made in order to improve the dynamic indicators of the energy system and to avoid the emergencies. The authors also give a prognosis of the dynamic indicators of the electric power super-system in analyzing metastable conditions in different energy modes.

Prospect of solar-PV/biogas/diesel generator hybrid energy system of an off-grid area in Bangladesh

Science.gov (United States)

Mandal, Soumya; Yasmin, Hosna; Sarker, M. R. I.; Beg, M. R. A.

2017-12-01

The study presents an analysis and suggests about how renewable sources of energy can be an alternative option to produce electricity in an off-grid area. A case study is done by surveying 235 households in an off-grid area. Techno-economic analysis of the hybrid energy system is employed by using Hybrid Optimization of Multiple Energy Resources (HOMER) software. Four solar-PV modules (each of 1kW), two biogas generators (each of 3kW), three diesel generators (each of 5kW), five batteries (each of 160 Ah) and 5kW converter is found to be the best configuration in terms of Cost of Energy (COE), environmental conditions and Renewable Fraction (RF). The Cost of Energy (COE), Net Present Cost (NPC), capital cost of this configuration is found BDT15.382, BDT10007224, and BDT2582433 respectively. The renewable fraction of this system is found 75% which indicates a lower emission compared with thegrid based system and stand-alone diesel system. Although the COE is higher than grid electricity, this system offers a cheaper option than using kerosene oil and solar home systems (SHSs).

High energy physics and grid computing

International Nuclear Information System (INIS)

Yu Chuansong

2004-01-01

The status of the new generation computing environment of the high energy physics experiments is introduced briefly in this paper. The development of the high energy physics experiments and the new computing requirements by the experiments are presented. The blueprint of the new generation computing environment of the LHC experiments, the history of the Grid computing, the R and D status of the high energy physics grid computing technology, the network bandwidth needed by the high energy physics grid and its development are described. The grid computing research in Chinese high energy physics community is introduced at last. (authors)

TIGER: A graphically interactive grid system for turbomachinery applications

Science.gov (United States)

Shih, Ming-Hsin; Soni, Bharat K.

1992-01-01

Numerical grid generation algorithm associated with the flow field about turbomachinery geometries is presented. Graphical user interface is developed with FORMS Library to create an interactive, user-friendly working environment. This customized algorithm reduces the man-hours required to generate a grid associated with turbomachinery geometry, as compared to the use of general-purpose grid generation softwares. Bezier curves are utilized both interactively and automatically to accomplish grid line smoothness and orthogonality. Graphical User Interactions are provided in the algorithm, allowing the user to design and manipulate the grid lines with a mouse.

Reliability Oriented Design Tool For the New Generation of Grid Connected PV-Inverters

DEFF Research Database (Denmark)

Sintamarean, Nicolae Cristian; Blaabjerg, Frede; Wang, Huai

2015-01-01

is achieved and is further used as an input to the lifetime model. The proposed reliability-oriented design tool is used to study the impact of mission profile (MP) variation and device degradation (aging) in the PV inverter lifetime. The obtained results indicate that the MP of the field where the PV...... inverter is operating has an important impact (up to 70%) on the converter lifetime expectation, and it should be considered in the design stage to better optimize the converter design margin. In order to have correct lifetime estimation, it is crucial to consider also the device degradation feedback (in......This paper introduces a reliability-oriented design tool for a new generation of grid-connected photovoltaic (PV) inverters. The proposed design tool consists of a real field mission profile (RFMP) model (for two operating regions: USA and Denmark), a PV panel model, a grid-connected PV inverter...

Multiplicative Structure and Hecke Rings of Generator Matrices for Codes over Quotient Rings of Euclidean Domains