Search results for "Networks"
showing 10 items of 3260 documents
An analytical model for PQ sources in backward/forward methods for distribution networks analysis
2004
In this paper a model of PQ sources useful for distribution systems analysis is developed. In the considered systems there are, in addition to HV/MV sources, other PQ buses, namely active and reactive power supply nodes (Vδ nodes). The general solution strategy is an iterative forward/backward method, in which the state variables are the node voltages. If it is weakly meshed, the network is turned into radial by means of cuts and compensation currents. After the presentation of the general problem, the equations expressing the unknowns for the PQ nodes are treated in detail. These equations belong to the backward sweep of the algorithm. The methodology has been implemented and applied so as…
Constrained Robust MultiObjective Optimization for Reactive Design in Distribution Systems
2006
This paper presents a new formulation including robustness of solution of constrained multiobjective design or reactive power compensation. The algorithm used for optimization is the NSGA-II (Non dominated Sorting Genetic Algorithm II) with a special crowded comparison operator for constraints handling. The need for including the issue of robustness of solutions derives from the simple observation that loads are uncertain in distribution systems and their estimation is often affected by errors. In design problems it is desirable to consider the loads with a certain range of variation. In this paper the NSGA-II algorithm is applied to efficiently solve the issue and the solutions attained co…
Comparing the Impact of Electric Vehicles on Urban and Insular Networks
2022
Transport sector is moving towards clean and green transportation with the growing market of electric vehicles globally. Electric vehicles are independent fossil fuels consumption, but the massive adoption of electric vehicles soon can lead to a significant burden on the power distribution networks. In this paper, a study on the potential impact of electric vehicles on the power distribution networks of two different regions with totally different realities of population density, an average number of cars per inhabitant, and travel habits has been carried out. The first region is the island of Favignana having an insular power distribution network, while the other region, the city of Palerm…
Load Flow Solution of radial distribution networks with ZI loads
2008
In this paper, a methodology to solve radial distribution networks, with constant current and/or impedance loads, is proposed. The techniques currently available to solve such systems are based either on iterative methods or on the bus impedance matrix. The method developed is the extension of a technique that is valid to solve networks made of impedances with one supply point. The methodology can be applied to directly and rapidly solve large distribution systems in which the loads are modeled as constant current/impedance. It is also able to solve meshed systems having voltage-dependent loads, inside an iterative backward/forward method.
A Multi-Port Approach to Solve Distribution Networks with Meshes and PV Nodes
2007
A new methodology based on the backward/forward (b/f) technique for the load flow solution in distribution systems is here proposed. The methodology takes efficiently into account the fixed voltage nodes and uses a reduced bus impedance matrix. In this way, it is possible to attain, for the unknowns at the PV nodes, the same values that are attainable solving the network with the methods adopted for transmission systems. With the same methodology it is possible to take into account also the meshes. If the network contains only meshes, the relevant model is linear and it is the one including the compensation currents. The presence of PV nodes introduces non linearity in the model and an iter…
Revealing Transmit Diversity Mechanisms in Commercial IEEE 802.11 Cards
2008
Service differentiation in WLAN has been traditionally faced at the MAC layer. However, some PHY layer parameters, such as the transmission power, the antenna, and the modulation/coding scheme, have a deep impact on network performance. Since the criterion for selecting these parameters is left to the vendor specific implementations, the performance spread of most experimental results about 802.11 WLAN could be affected by vendor proprietary schemes. The focus of this paper is an experimental analysis of the undisclosed antenna diversity mechanisms employed by some widely used cards (namely, the Atheros and Intel based cards), and a thorough understanding of the optimization goals which gui…
An Embedded System for the integration of a Combined Photovoltaic Solar (CPS) system into a ZigBee Home Area Network
2011
In this paper is reported the design and implementation of an electronic system capable of communicating over a standard ZigBee network in order to let a residential gateway collector, named agent, gain access to the parameters of a Combined Photovoltaic and Solar thermal (CPS) plant, thus realizing a networked energy production appliance . The system is made of three parts: a PV metering device, a boiler metering device also capable of controlling a heating resistor embedded within the boiler tank, and a data collector acting as a ZigBee node. The data collector device periodically retrieves the following parameters from the metering devices: instantaneous photovoltaic power production, ac…
The FP7 BeyWatch European scientific project: general features and design criteria of the Combined Photovoltaic Solar (CPS) system within the BEYWATC…
2011
This paper includes the general features and design criteria of a combined photovoltaic solar system (CPS) and its allocation within the entire architecture of the BeyWatch system. The CPS main functionalities and characteristics, the description of the CPS main components and the CPS electronic control and monitoring subsystem, together with the description of the Firmware design and communication protocols are here reported. The Combined Photovoltaic and Solar system (CPS) is a Renewable Energy system that produces thermal and electrical energy and the design has been based on a modular approach.
Realizing airtime allocations in multi-hop Wi-Fi networks: A stability and convergence study with testbed evaluation
2019
Abstract REACT is a distributed resource allocation protocol used to negotiate a max–min allocation of airtime for multi-hop ad hoc wireless networks. Two approaches are proposed for a node to realize its REACT allocation in a contention-based MAC protocol. This is achieved by tuning its contention window to a value that corresponds to its allocation. Only a change in the allocation, due to a change in local traffic requirements or local network views, results in re-tuning. The approaches for tuning are implemented in commercial Wi-Fi devices and their stability and convergence are studied experimentally in the w-iLab.t wireless network testbed. These properties are also studied analyticall…
A Survey on LoRa for Smart Agriculture: Current Trends and Future Perspectives
2023
This paper provides a survey on the adoption of LoRa in the agricultural field, and reviews state-of-the-art solutions for Smart Agriculture, analyzing the potential of this technology in different infield applications. In particular, we consider four reference scenarios, namely irrigation systems, plantation and crop monitoring, tree monitoring, and livestock monitoring, which exhibit heterogeneous requirements in terms of network bandwidth, density, sensors’ complexity, and energy demand, as well as latency in the decision process. We discuss how LoRa-based solutions can work in these scenarios, analyzing their scalability, interoperability, network architecture, and energy-efficiency. Fi…