Search results for "CONNECTION"
showing 10 items of 489 documents
Decoupled control scheme of the grid-connected split-source inverter for renewable energy sources
2016
Grid-connected power conversion systems for renewable energy sources must fulfill several requirements, including high efficiency, reduced cost and complexity, and, quite often, also boost capabilities from the dc sources to the ac power grid. For such applications, single-stage power converters with boost capabilities offer some potential advantages. Among several proposed options, split-source inverter (SSI) has been recently investigated. This paper proposes a decoupled control scheme for the SSIs, where the common mode term of the ac modulation signals is used to control the dc input current. Thus, the dc input current and ac output current can be controlled independently. The proposed …
A new model for a safety analysis in a system of earthing systems interconnected through bare‐buried conductors
2009
PurposeThe purpose of this paper is to present a mathematical model for studying the effects of the interconnection through bare‐buried conductors (BBC) of the secondary substations' earthing system of an urban area.Design/methodology/approachThe developed methodology is based on three main points: the solution of the transmission lines' equations for the formulation of a lumped parameters model of a BBC considering the conductive effect; the division of the distribution network into simpler sub‐systems; and the calculation of all the voltages and currents of the medium voltage (MV) network and of the earthing systems using a multiport approach.FindingsThe methodology has been applied to va…
Investigating the effect of distributed generators on traditional protection in radial distribution systems
2013
The recent changes in power network structure, development in green energy technologies and increased attention on environmental concerns have led to increase the installation of renewable energy based distributed generations (DG) in distribution networks. The increasing penetration of distributed generation in the distribution power system creates new technical and economical challenges; protection is one important topic of these challenges. High penetration of DG will have unfavorable impact on the traditional protection methods; the impact depends on the number, location and size of injected DG. To ensure safe and selective protection devices coordination, the impact of DG should be take…
DOUBLE EARTH FAULT EFFECTS IN PRESENCE OF INTERCONNECTED EARTH ELECTRODES
2009
The paper presents a study on the effects of double earth faults in Medium Voltage (MV) networks, in presence of electrical interconnection of the earthing systems of the secondary substations. In urban areas, indeed, the earth electrodes of the secondary substations are interconnected and, in many cases, they are also connected to the earth electrodes of the primary stations, in order to realize quasi-equipotential surfaces, intrinsically safe against electric shocks, named Global Earthing Systems (GES). The concept of GES has been introduced in the technical literature ten years ago in the Document HD 637 S1 by CENELEC, with the aim of providing a solution to the problems of designing and…
The Quest for Global Safety
2007
The authors present a systematic study on the factors that have influence on the establishment of the safety conditions ensuring the rise of Global Earthing Systems. Starting from the definition of Global Earthing System given by CENELEC Document HD 637 SI and from the results of the studies done on the last years on the interconnected earthing systems inside MV networks, the paper proposes some directions of deepening on the topic of Global Safety. Some of the themes whom the paper deals with are: the correct definition of proximity, interconnection and quasi-equipotentiality of the earth electrodes belonging to a Global Earthing System; the influence of the presence of HV/MV stations on h…
On the effects of HV/MV stations on global grounding systems
2016
The METERGLOB project has faced the issue of the identification of Global Grounding Systems. One of the main point of the problem is to define if an interconnection of single grounding systems gives place to a Global Grounding System in any condition and for every kind of ground fault. This paper focuses the attention on what happens in the case of single line to ground fault inside a HV/MV station whose ground electrode is connected to the cable' shields of the MV lines outgoing the station and supplying the secondary substations of a given area.
Photovoltaic plant array reconfiguration: Design of a new device
2014
An efficient strategy to improve unequally irradiated PV plants performances is based on the reconfiguration of the connections between the modules. In this paper, an algorithm, for this purpose conceived, is presented. Moreover, the design, realization and finally also the set up of a new reconfiguration system device is fully shown and discussed. The algorithm conceived simulates several possible series-parallel connections under varying irradiation conditions, and determines the optimal modules connection in order to get the maximum output power. In this way, the reconfiguration system may set up the reconfiguration strategy. The reconfiguration system prototype set up, basically consist…
Performance comparison of tubular linear induction motors with different primary winding connections
2014
This paper presents an experimental characterization and comparison of the performances achieved by a tubular linear induction motor (TLIM) prototype with different typologies of primary winding connections. In particular, three configurations are described: full-pitch star, 5/6 shortened pitch star and 5/6 shortened pitch double star. For this purpose, an experimental test bench at the SDESLAB laboratory (University of Palermo) has been set-up and the results obtained from the tests have allowed to identify which type of winding configuration can be chosen in dependence of the type of application intended for the motor. In addition, this experimental study is suitable for TLIM winding desi…
An Innovative Conversion Device to the Grid Interface of Combined RES-Based Generators and Electric Storage Systems
2015
This paper is focused on the development of an innovative device, which is based on a bidirectional converter, for the interface to the supply utility grid of combined renewable-energy-source-based generators and electric storage systems. The device can be controlled so as to ease the interface between the low-voltage grid and photovoltaic or wind generators combined with lithium-ion $\hbox{LiFePO}_{4} $ batteries, taking into account the requirements of the reference technical standards for users connection and offering different ancillary services. The operational functioning of the device, the architecture, and its electronic components, as well as laboratory and field test activities an…
On the sway stability improvement of car–caravan systems by articulated connections
2015
The present analysis is addressed to some promising connection arrangements between the towing vehicles and the towed trailers, where the two units are linked by four-bar isosceles trapeziums in place of the conventional pintle hitch. Two types of instability, of the divergent type or the oscillating type, may be analysed by the Routh–Hurwitz criterion or by the direct analysis of the characteristic equation. The constant term of this equation vanishes at the divergent instability threshold (zero of a real root), whereas the equation splits into two lower degree algebraic ‘sub-equations’ when the oscillating instability arises (pair of pure imaginary roots). A large field of geometrical con…