Search results for "grid"
showing 10 items of 792 documents
EA as a tool in change and coherency management - A case of a local government
2010
In order to lead a local government towards its politically set strategic objectives, the vision of the overall status quo, as well as of the desired target state of the complex multi-agent system have to be clear. To encounter the challenges of the change management in merging six former local governments into one, in forming a new NPM related operation model, in planning and leading strategic political objectives, and in order to leverage on the information usability produced in everyday governance practices, a Government Enterprise Architecture (GEA) method has been adopted in the city of Kouvola in Finland. The study is a case study by action research adopting the Finnish GEA method in …
Graphical THD minimization procedure for single phase five-level converters
2017
This paper proposes two graphycal procedure to mitigate h harmonics and to minimize the total harmonic distortion (THD), respectively. The paper considers a five-level inverter and fundamental frequency modulation: it computes the two switching angles able to reduce low order harmonics and able to minimize the THD. Simulation results are obtained and, in order to validate the proposed procedure, an experimental prototype is built and experimental results are carried out. The comparison between simulation and experimental results confirms the accuracy of the proposed graphycal procedure. It is shown that the switching angles to mitigate the third-fifth and the third-fifth-seventh harmonics e…
GRID STABILITY IMPROVEMENT BY RES-BASED GENERATORS AND BATTERY ENERGY STORAGE SYSTEMS IN SMALL ISLANDS
2021
The integration of Renewable Energy Sources (RES) with power electronics interface to the grid, without the back-up of rotating inertia, endangers frequency stability. This issue becomes particularly critical in isolated power systems, like those of small islands not supplied by the main grid, in the case of high shares of production from unpredictable renewables such as photovoltaic and wind sources. Consequently, to preserve the security and the reliability of these systems, it is necessary to adopt new frequency adjustments mechanisms. In this context, the thesis investigates the transition toward an economically and technically feasible generating system based on RES, to achieve specifi…
Decoupled Control Scheme of Grid-Connected Split-Source Inverters
2017
During the last few years, single-stage power conversion systems has undergone a fast evolution to replace the conventional two-stage architecture, which includes a front-end dc-dc boost converter (BC) and an output voltage source inverter (VSI) [1]. This evolution has grown up to improve the overall system performance in terms of reducing its size, weight, and complexity. Most of these single-stage topologies and their different modulation schemes have been reviewed in [1]. Among these different single-stage options, the split-source inverter (SSI), shown in Figure 1, has been recently proposed in [2] as a single-stage dc-ac power converter topology to overcome some demerits in the other s…
Design of Photovoltaic System for Rural Electrification in Rwanda
2017
Master's thesis Renewable Energy ENE500 - University of Agder 2017 In this century of accelerated development in various domains, some African countries are still facing a challenge of lack of power due to its scarce in some places, where by the main source of power (generation of electricity) is hydro since thermal and fuel are still on a small scale. This problem results in less productivity and economic decline of some countries like Rwanda which is among African countries that are at a very high speed in development, the grid lines from distant places are stack and they are few compared to the need of electricity in all corners of the country, especially in rural areas whereby each hous…
Review of detection, assessment and mitigation of security risk in smart grid
2017
The integration of Information and Communication Technology (ICT) into the existing power grid has created new problems to the grid. The grid network has become more vulnerable to security threats and risk which is a corollary to the modern data network. Smart Grid has strict latency requirement for data communication and the violation of this latency is very costly. This paper assesses the threats and vulnerabilities associated with the Smart Grid network and reviews the methods to mitigate these security risks.
Load mismatch of grid-connected photovoltaic systems: Review of the effects and analysis in an urban context
2013
Abstract The mismatch between generated and consumed electricity is a relevant topic of the energy and economic assessment of photovoltaic (PV) systems. Due to the load mismatch some amount of PV electricity may be exported to the grid because the electrical demand is temporarily lower than production, whereas a consumption, which is higher than production and/or that does not match the available PV generation, will require to be supplemented by the public grid electricity. The presence of the load mismatch can cause the effect of disadvantageously purchasing electricity from the grid and/or squandering the unexploited PV energy. If only a very small part of the PV generation is used to sup…
A Gridlocked World
2016
A Symposium on "Gridlock: Why Global Cooperation is Failing When We Need It Most" by Held, Hale and Young
The Role of Technology in Participative Processes
2016
Smart city is more and more, in the common feeling, the crossroad of technologies, but first and foremost, the place where humans, contexts and technologies meet and must interact. Technological systems thanks to the deep human interaction acquire an uncertain behaviour that can be hardly modelled and controlled. The resulting complexity, cannot be easily handled with the tools that are available to separate scientific fields. The interdisciplinarity that comes from the implementation of technologies and the dialogue between these and the territories requires new tools for classification and design. New urban design tools are needed allowing to identify in a standardized way adequate suppor…
Searches for beyond the Standard Model physics with boosted topologies in the ATLAS experiment using the Grid-based Tier-3 facility at IFIC-Valencia
2013
Tesis leída en la Universidad de Valencia, Departamento de Física Atóomica, Molecular y Nuclear, para optar al grado de Doctor en Física.-- 181 páginas