Search results for "elettrici"
showing 10 items of 959 documents
The Global Grounding System: Definitions and guidelines
2015
The present paper presents the preliminary results of the ongoing Italian METERGLOB project on the contribution given by the exposed conductive parts to a Global Grounding System. One of the expected results of METERGLOB is to carry out guidelines for the identification of a Global Grounding System. These guidelines must be defined on the basis of the definitions and methods present in the current international standards on grounding and safety. In the paper some definitions and elements to be taken into account for the identification of a Global Grounding System are given.
Effects of electrical and mechanical parameters on the transient voltage stability of a fixed speed wind turbine
2011
Abstract In this paper the dynamic behaviour of a wind turbine connected to the grid is examined. The model of the fixed speed wind turbine has been developed with the Simulink simulation tool (Matlab Inc.) It is composed of the induction generator, the shaft system, an aerodynamic model of the wind turbine rotor and the pitch control system. Using this model, a three-phase fault is applied close to the wind turbine and cleared by disconnecting the faulty line. The rigorous implementation of the simulink model allowed the authors to evaluate the exact dependence of various electrical parameters for the induction generator on voltage stability. Furthermore, the effects of wind turbine mechan…
Power tracking with maximum efficiency for wireless charging of E-bikes
2014
Wireless charging techniques, based on Inductive Power Transfer (IPT), are attractive for Electric Vehicles (EV), due to benefits such as convenience and safety. An accurate valuation of the maximum achievable efficiency in an IPT system is extremely unlikely due to the high sensitivity to parasitic elements variations. Therefore, an “on site” procedure of power efficiency characterization is useful to get a precise description of the efficiency curve and obtain the actual maximum efficiency. In this paper, a power tracking algorithm aiming at efficiency maximization is proposed for a Wireless Charging system. The algorithm aims at finding the maximum power transfer efficiency with respect …
A bidirectional converter for the integration of LiFePO4 batteries with RES-based generators. Part II: Laboratory and field tests
2014
This paper presents a device for controlling and connecting combined Renewable Energy Sources (RES)-based generators and electric storage systems to the supply utility grid. The device is a bidirectional converter that can be controlled in order to facilitate the interface between the low voltage grid and small generators combined with Li-ion batteries, contemporary addressing the requirements of the reference technical standards for users connection and providing different ancillary services. The paper describes the laboratory and field test activities carried out by the DEIM of the University of Palermo and ENEA during 2013.
Optimal power flow based on glow worm-swarm optimization for three-phase islanded microgrids
2014
This paper presents an application of the Glowworm Swarm Optimization method (GSO) to solve the optimal power flow problem in three-phase islanded microgrids equipped with power electronics dc-ac inverter interfaced distributed generation units. In this system, the power injected by the distributed generation units and the droop control parameters are considered as variables to be adjusted by a superior level control. Two case studies with different optimized parameters have been carried out on a 6-bus test system. The obtained results showed the effectiveness of the proposed approach and overcomes the problem of OPF in islanded microgrids showing loads unbalance.
Measurement-based load modelling for power supply system design
2008
Load modelling is essential to simulate system features as closely as possible to the effective behaviour. In spite of model complexity, the need for accuracy often leads to a component-based approach, i.e. the analysis of load internal subsystems. It is a common belief that measurement-based load models lead to low accuracy. This paper presents a new, high-accuracy measurement-based load modelling approach to define a power consumption profile load model for power systems design. The load modeling technique is described by an application. Simulation and experimental results are compared. The efficiency and portability of the proposed modelling approach is discussed. ©2008 IEEE.
A Perspective on the Future of Distribution: Smart Grids, State of the Art, Benefits and Research Plans
2013
Currently, the design and operation criteria for electrical distribution networks are fastly changing due to some factors; among these, the progressive penetration of Distributed Generation (DG) is destined to cause deep changes in the existing networks, no longer considered as passive terminations of the whole electrical system. Moreover, the increasing application of Information Communication Technologies (ICT) will allow the implementation of the so called “smart grids”, determining new interesting scenarios. In the paper the problems and the potential benefits of DG, the possible new electrical distribution system models and the major research projects on smart grids are faced and repor…
Smart renewable generation for an islanded system. Technical and economic issues of future scenarios
2012
The subject addressed in this paper is the analytical study of the transition of an energy generation system for a real MV/LV distribution system from one that is “fuel-based” to a distributed and smart “renewables-based” system. The paper outlines both the technical and the economic issues related to such a transition from one type of system to the other. The study is carried out for a real islanded network located in the Island of Pantelleria (Mediterranean Sea). The results obtained are presented and discussed, putting into evidence the technical, environmental and economic benefits of using smart technologies and renewable energy sources.
A Simple Method to Assess Loadability of Radial Distribution Networks
2005
This paper proposes a simple method to asses loadability in radial distribution systems. The relevant problem of voltage stability has been dealt with in past times with reference to higher voltage systems for generation and transmission. In more recent papers, the problem has been considered also at distribution level, since the new electrical energy market requirements and the increasing loadings are now more and more influencing these systems. The proposed method is based on a static approach and proceeds by first evaluating the stability indices and then the different loadability factors (related to real, reactive and apparent power). These calculations are carried out by identifying, s…
An economic study about the installation of PV plants reconfiguration systems in Italy
2014
This paper shows the economic convenience of the application of a reconfiguration system for photovoltaic plants, considering the incentives system in Italy and its recent modifications. The reconfiguration is an alternative to the Distributed Maximum Power Point Tracking, DMPPT, technique used to overcome the mismatch problem in Photovoltaic, PV, plants. The reconfiguration techniques employ a microprocessor-based system that modifies the layout of the PV plant by physically changing the connections among modules. After the explanation of the working principle of the PV reconfiguration system allowing the improvement of the efficiency of the same plant and the relevant installation, the ma…