Search results for "elettrici"
showing 10 items of 959 documents
Analysis of the limitations of WiFi communications managed by the IEEE 802.11 protocol in data transmission in automated power distribution systems
2010
This paper presents a study on the performances of the IEEE 802.11 protocol used in a Medium Voltage networks management system, carried out using a model for the simulation of WiFi chains architectures. The results of the simulations give some practical indications for the use of the IEEE 802.11 protocol also in presence of transmissions characterized by rigid time intervals, for which this protocol is usually not suitable. Finally the whole communications system is presented.
Hydrogen Supplied Wireless Charging System for Electric Vehicles
2020
The aim of this work is the experimental characterization of a Wireless Charging System based on IPT (Inductive Power Transfer) supplied by a PEMFC (Proton Exchange Membrane Fuel Cell) in order to verify the possibility of its installation in not electrified areas. A hydrogen-based supply system is designed and assembled with the purpose of having an EV (electrical vehicle) charging station not connected to the main power grid. An efficiency analysis of the wireless transmission system is carried out taking into account external parameters such as distance and misalignment between the transmitter coil and the receiver coil, verifying the integration potentialities of both IPT and fuel cell …
Effects of post-filtering in grid-synchronization algorithms under grid faults
2018
Abstract The spread of distributed generation systems has reinforced concerns and requirements on grid-tied power converters. The synchronization with the utility voltage vector is a major concern. In the literature, algorithms based on Phase Locked Loops are extensively presented. In spite of adequate performances under ideal and balanced grid conditions, under grid faults great inaccuracies arise. Shortcomings are overcome by advanced algorithms at the expenses of the complexity and computational cost. In this paper, grid synchronization algorithms are addressed. A solution is proposed by introducing a new post-filter stage in a Decoupled Double Synchronous Reference Frame not affecting, …
Impact of RES penetration on the frequency dynamics of the 500 kV vietnamese power system
2019
The increase of renewable energy sources (RES) typically operating as converter-interfaced generation (CIG) is progressively causing a significant change of power systems operation paradigm. The reduction of the overall available kinetic energy and the consequent impact on the dynamic response of the system is a relevant issue currently under investigation in academic and industrial scopes. The work analyzes the impact of different CIG penetration in the three areas of the 500 kV Vietnamese power system, North, Center and South. The system is modified substituting conventional synchronous generation with converter-interfaced generation. The models of power converters and corresponding contr…
Inertial response of isolated power networks with wind power plants
2019
The constant increase of power generation provided by renewable energy source (RES) power plants is causing a progressive reduction of the overall inertia of the power systems. Especially in the case of small, isolated power networks, the replacement of conventional generation plants with RES power plants can affect significantly the frequency response of the system. The critical low-inertia conditions can be improved by the introduction of specific additional controls to the RES power converters. These control schemes are known as “synthetic inertia” or “virtual inertia” controls. The paper analyzes the impact of a derivative-based inertial control on a small, isolated power system, with a…
System Stability of a Small Island's Network with Different Levels of Wind Power Penetration
2018
The reduction of the inertial response of the generation system has been one of the main obstacles to the penetration of high sharing of renewable energy sources in islanded systems. This issue can be solved thanks to innovative control that makes wind turbines able to provide the so-named synthetic inertia. The paper investigates some scenarios with different levels of wind power penetration in a small island whose grid is not supplied by the main grid, by the use of the software NEPLAN 360, simulating the wind power plants accordingly to the standard IEC 61400-27. The aim of the paper is to assess the maximum level of penetration in the island of wind generation, with traditional control …
An Analysis of the Intertial Response of Small Isolated Power Systems in Presence of Generation from Renewable Energy Sources
2018
Renewable Energy Sources are posing critical issues related to the mining of power systems stability, essentially due to a decrement of the inertial response during system's contingencies. As a consequence, to preserve the security and the reliability of the system, it is necessary to adopt new frequency adjustments mechanisms. 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 renewabies such as photovoitaic and wind sources. In this framework, the present work deals with the analysis of the variation of the inertia time constant of a small island in vario…
Interconnections criteria of grounding grids in global grounding systems
2018
A Global Grounding System is defined as the combination of local grounding systems, obtained by their interconnection, which ensures, thanks to their proximity, that no dangerous touch voltages can arise. The interconnection of grounding systems via the armors of the MV cables, between secondary substations and HV/MV stations is herein analyzed to verify the effects on touch voltages in ground-fault conditions. In particular, two main issues are discussed: 1) the transfer of dangerous voltages to secondary substations, due to ground-faults occurring at the HV/MV station; 2) the reduction in the magnitude of the ground potential rise due to ground-fault conditions at secondary substations, t…
Integration Issues of Distributed Generators Considering Faults in Electrical Distribution Networks
2014
In the recent years there is a great interest in integration of distributed generation (DG) units at distribution level; this integration leads to planning as well as operational challenges. Some possibilities to handle grid planning issues are addressed in this paper. Effects on grid protection, fault current level, and voltage profile are investigated and described for different types of DG units; the classification of DG units is based on their terminal characteristics in terms of real and reactive power delivering capability. Different scenarios for mis-coordination problems caused by DG interconnection are discussed. The effect of the DG on the voltage profile of a distribution network…
Evaluation of the power quality from a seawave power farm for different interconnection schemes
2007
In this paper we present an approach to the interconnection of a seawave power farm to the grid The generator type used in the farm is a Permanent Magnet (PM) linear generator driven from the seawaves that generates, therefore, highly distorted emfs. We propose and compare two possible ways to interconnect the farm to the grid. One is based on an approach where for each generator there is a conversion subsystem that permits the direct connection of each generator to the a.c. network, the other one is based on an ac.-d.c. converter that is connected to the generator, the converter is connected to a dc link that can receive the power from every unit and that can supply a dc-ac converter direc…