Search results for "Grid"
showing 10 items of 792 documents
Polynomial Smoothing Splines
2014
Interpolating splines is a perfect tool for approximation of a continuous-time signal \(f(t)\) in the case when samples \(x[k]=f(k),\;k\in \mathbb {Z}\) are available. However, frequently, the samples are corrupted by random noise. In such case, the so-called smoothing splines provide better approximation. In this chapter we describe periodic smoothing splines in one and two dimensions. The SHA technique provides explicit expression of such splines and enables us to derive optimal values of the regularization parameters.
Real-space grids and the Octopus code as tools for the development of new simulation approaches for electronic systems.
2015
This Open Access Article is licensed under a Creative Commons Attribution 3.0 Unported Licence.
A coupled Finite Volume–Smoothed Particle Hydrodynamics method for incompressible flows
2016
Abstract An hybrid approach is proposed which allows to combine Finite Volume Method (FVM) and Smoothed Particle Hydrodynamics (SPH). The method is based on the partitioning of the computational domain into a portion discretized with a structured grid of hexahedral elements (the FVM-domain ) and a portion filled with Lagrangian particles (the SPH-domain ), separated by an interface made of triangular elements. A smooth transition between the solutions in the FVM and SPH regions is guaranteed by the introduction of a layer of grid cells in the SPH-domain and of a band of virtual particles in the FVM one (both neighboring the interface), on which the hydrodynamic variables are obtained throug…
Distributed Learning Automata-based S-learning scheme for classification
2019
This paper proposes a novel classifier based on the theory of Learning Automata (LA), reckoned to as PolyLA. The essence of our scheme is to search for a separator in the feature space by imposing an LA-based random walk in a grid system. To each node in the grid, we attach an LA whose actions are the choices of the edges forming a separator. The walk is self-enclosing, and a new random walk is started whenever the walker returns to the starting node forming a closed classification path yielding a many-edged polygon. In our approach, the different LA attached to the different nodes search for a polygon that best encircles and separates each class. Based on the obtained polygons, we perform …
A resilient distributed measurement system for smart grid application
2020
Since the production of energy from renewable energy sources is strongly increasing, the migration from the classical electric grid toward the smart grid is becoming a reality. Distribution System Operators, along with the control of the entire network and its stability, need to address the security and the reliability of the communication channels and the data itself. In this paper a solution is proposed to address these issues. It is based on a distributed measurement system that relies on a wireless network as well as a redundant Power Line communication system in order to transfer the electrical measures to a centralized SCADA server. The collected data are used to run a power flow algo…
A review of health assessment techniques for distribution transformers in smart distribution grids
2020
Due to the large number of distribution transformers in the distribution grid, the status of distribution transformers plays an important role in ensuring the safe and reliable operation of the these grids. To evaluate the distribution transformer health, many assessment techniques have been studied and developed. These tools will support the transformer operators in predicting the status of the distribution transformer and responding effectively. This paper will review the literature in the area, analyze the latest techniques as well as highlight the advantages and disadvantages of current methodologies.
Querying Dynamic and Context-Sensitive Metadata in Semantic Web
2005
RDF (core Semantic Web standard) is not originally appropriate for context representation, because of its initial focus on the ordinary Web resources, such as web pages, files, databases, services, etc., which structure and content are more or less stable. However, on the other hand, emerging industrial applications consider e.g. machines, processes, personnel, services for condition monitoring, remote diagnostics and maintenance, etc. to be specific classes of Web resources and thus a subject for semantic annotation. Such resources are naturally dynamic, not only from the point of view of changing values for some attributes (state of resource), but also from the point of view of changing “…
Performance of grid-connected PV system in Southern Norway
2015
This paper presents performance results from one of the first grid-connected photovoltaic (PV) systems in Norway. The 45 kWp system is mounted on top of a flat roof at the headquarters of a local utility company, Agder Energi, in the coastal town of Kristiansand. The system consists mainly of multi-crystalline silicon modules, with one thin film array. The system has been in operation since May 2011 and is instrumented for research and monitoring purposes. Data recorded include global and diffuse horizontal irradiation, tilted irradiation and other weather parameters, PV module temperatures, DC and AC current and voltage for three arrays, in addition to inverter power data and voltage quali…
Minimum power losses by using droop coefficients regulation method with voltage and frequency constraints in islanded microgrids
2018
In this paper, a droop coefficients regulation methodology is proposed for an islanded microgrid to optimize the power losses. Based on the P-f and Q-V relations to adjust the droop coefficients at every loading condition, the optimized operating set point generates minimum power losses operation while satisfying the constraints of voltage and frequency limitation. A 9-bus case study is here implemented to show the effectiveness of this new approach as well as the improved operation quality of the system.
Optimal power flow for technically feasible energy management systems in islanded microgrids
2016
This paper presents a combined optimal energy and power flow management for islanded microgrids. The highest control level in this case will provide a feasible and optimized operating point around the economic optimum. In order to account for both unbalanced and balanced loads, the optimal power flow is carried out using a Glow-worm Swarm Optimizer. The control level is organized into two different sub-levels, the highest of which accounts for minimum cost operation and the lowest one solving the optimal power flow and devising the set points of inverter interfaced generation units and rotating machines with a minimum power loss. A test has been carried out for 6 bus islanded microgrids to …