1,720,988 research outputs found
Local DC Distribution System in Presence of RES and Storage Devices: Multiport Converters Application
No full textModern distribution grids need to satisfy strict standards in terms of voltage quality and continuity. Furthermore, RES should be integrated at different levels in distribution systems, which can lead to non-negligible problems in terms of energy dispatch and protection systems. These considerations contributed to a new interest for direct current in distribution systems. Among different possible solutions, it may be of interest to introduce multiport converters: their centralized control allows to coordinate the various ports in order to maximize voltage quality and continuity. In this paper two types of multiport converters will be considered. For each topology power flow control will be developed to obtain consistent operation in steady state and under heavy load variation or grid connection loss and pole-to-pole fault behavior will be analyzed for the two considered topologies. Criteria to choose between the examined configurations for a specific application will be provided
Integrated control strategy for islanded operation in smart grids: Virtual inertia and ancillary services
Get PDFDistributed generation has become a consolidated phenomenon in distribution grids in the last few years. Even though the matter is very articulated and complex, islanding operation of distribution grids is being considered as a possible measure to improve service continuity. In this paper, a novel static converter control strategy to obtain frequency and voltage regulation in an islanded distribution grid is proposed. Two situations are investigated: in the former, one electronic converter and one synchronous generator are present, while in the latter only static generation is available. In the first case, converter control will realize virtual inertia and efficient frequency regulation bymean of a PID regulator; this approach allows to emulate high equivalent inertia, hence limiting the rate of change of frequency and maximum frequency deviation, and, in the meantime, to obtain faster frequency regulation, which could not be possible with traditional regulators. In the second situation, a Master-Slave approach will be adopted to maximize frequency and voltage stability. Even though the presented results are obtained in a grid with only two generators, the proposed approach can be extended to more general configurations with few generation units. Simulation results confirm that the proposed control allows islanded operation with high frequency and voltage stability under heavy load variations
Economic and Environmental Impact of Electric Vehicles Trends on Jointly-Acting Renewable Self-Consumers Groups
Get PDFExtended forms of self-consumption, including jointly-acting renewable self-consumers and renewable energy communities, are extremely promising instruments for the dissemination of renewable energies and the achievement of European targets regarding sustainability and reduction of greenhouse emissions. At the same time, electrification in the transportation sector is developing faster and faster, with great success also among private users. In this paper, we will consider an apartment building, the inhabitants of which, thanks to the installation of a photovoltaic and storage system, acts as a group of jointly-acting renewable self consumers, with the aim of gaining advantages in economic and environmental terms. In particular, the impact of the foreseen increase of electric vehicles owned by inhabitants in terms of costs and CO2 emissions is investigated. A range of possible scenarios will be considered, including different sizing and management criteria of the photovoltaic and storage system, with and without the establishment of a jointly-acting renewable self consumers group
Investigation of Controlled Fault Interruption Strategies in Isolated MV Distribution Systems
No full textThe paper presents an investigation of the applicability of controlled fault interruption techniques in radial, isolated, medium voltage distribution networks. In particular, when single phase-to-earth faults occur in isolated distribution systems, it is necessary to mitigate switching overvoltages. A comprehensive set of simulations has been carried out to evaluate the sensitivity of overvoltage phenomena to different switching strategies, with the aim of highlighting the possible methods to mitigate them and, thus, avoid harmful effects on electrical systems. The presented results show slight benefits in reducing overvoltages in the primary substation by independently controlling each pole of the switching device, regardless of the considered switching strategy. The inherent limitations of this approach are hence discussed, highlighting the current technological limitations, and alternative mitigation strategies are suggested
Non-Intrusive Measurement of Two-Port Impedance Parameters by Clamp-on Inductive Probes
Get PDFMany applications in the field of power electronics benefit from in-circuit impedance measurements, including modelling of electromagnetic interference and stability analysis of control systems. Noteworthy, a non-intrusive characterization of a system can be obtained, in real operating condition, by clamp-on inductive probes. Unfortunately, the characterization of a multiport system requires the measurement of an impedance matrix, which cannot be obtained by currently known one-port in-circuit impedance measurement techniques. Recently, the introduction of a novel inductively coupled technique allowed non-intrusive measurements of admittance matrices. Though the impedance matrix can be found by inversion of the admittance matrix, this operation is subject to numerical errors. Hence, an alternative formulation allowing direct measurement of impedance parameters is presented in this paper. The proposed method is validated using one set of passive networks, and comparing results with those obtained by direct measurement from a vector network analyser, showing good accuracy from 150 kHz to 30 MHz
Accuracy Assessment of Non-Intrusive Measurement of Two-Port Impedance and Admittance Parameters by Inductive Couplers
Get PDFMany applications, ranging from power electronics to electromagnetic interference modelling, take advantage of in-circuit impedance and admittance measurements, that is, carried out while equipment is operating. Single-port literature methods, based on the use of clamp-on inductive probes to couple the ports of a vector network analyser (VNA) with the system under test, are advantageous due to their non-intrusive setup, but are not suitable for multiport systems. Just recently, two-port inductively-coupled methods were proposed in two different formulations, namely, for measurement of the full 2x2 admittance and impedance matrix, respectively. In this paper, a comparative investigation on the accuracy provided by the inductively-coupled admittance and impedance measurement methods is presented. Both methods are tested using a suitable set of passive networks in the 150 kHz - 30 MHz frequency range. The obtained results are compared versus an accurate (yet intrusive) reference result, that is, impedance and admittance parameters mathematically converted from scattering parameters directly measured at VNA ports without using inductive couplers. The accuracy of both methods is quantified and discussed, providing useful insights on how to possibly improve the measurement setup
Techno-Economic Analysis of Electric Vehicles Charging Hubs in a Renewable Energy Community
Get PDFThis study conducts a technical and economic assessment of a renewable energy community (REC) including multiple electric vehicle charging hubs powered by photovoltaic canopies. The analysis covers the criteria for the sizing of the photovoltaic systems, the evaluation of the energy production profiles, and the estimation of the aggregated consumption profile of the vehicle charging hubs. It provides a discussion of the technical feasibility of the proposed solution and a preliminary economic analysis, considering net present value and investment payback periods. Additionally, on the basis of a recent and comprehensive database of electric vehicles in the Italian fleet, energy flows are accurately determined considering each vehicle characteristics, and their arrival and departure patterns. As a case study, the performance of a renewable energy community comprising eleven parking lots in the city of Milan, Italy, is analysed. The presented results offer an overview of the value of RECs based on charging hubs and highlight potential challenges in their technical and economic management
Behavioral Model of Inductors via Physics-Informed Circuit Synthesis and Modified Vector Fitting
Get PDFThis paper proposes a physics-informed circuit synthesis method to obtain behavioral models of inductors, the parameters of which are determined by a modified vector fitting (MVF) routine. Although the vector fitting (VF) algorithm provides accurate numerical approximation of virtually any frequency response in form of poles and residues, the most common circuit synthesis methods often lead to unphysical electrical parameters (e.g. negative resistances), which correctly fit frequency responses, but cannot be used in common time-domain simulators such as Matlab Simulink. On the contrary, the methodology here proposed specifically for inductors produces circuit models with physical, easily interpretable circuit elements, such as the low-frequency functional inductance, the winding capacitance responsible for self-resonance frequency (SRF), and additional physical components to correctly fit multiple resonances. The proposed method is experimentally compared with a straightforward equation-based method and the original VF method in terms of accuracy, simplicity, and compatibility with common, commercial circuit solvers
Inductively Coupled in-Circuit Measurement of Two-Port Admittance Parameters
Get PDFIn-circuit impedance and admittance measurements are widely exploited in power electronics, from control stability analysis to electromagnetic interference modelling. In particular, the use of clamp-on inductive probes allows non-intrusive measurements of systems in real operating conditions. However, available methods are limited to a single port and cannot evaluate mutual impedances or admittances, hence they cannot properly characterize multiport systems described by impedance or admittance matrices. In this paper, a two-port inductively coupled in-circuit measurement method is proposed. Specifically, two inductive probes connected to a vector network analyzer define two longitudinal ports along the clamped wires of the system under test and allow measurement of its two-by-two admittance matrix. The proposed method is firstly verified with a set of known passive loads, then applied to measure the unknown admittance matrix of a single-phase motor drive system. Experimental results prove the effectiveness of the proposed method in providing accurate measurement of admittance parameters, including mutual terms, both for active and passive two-port devices. Additionally, such two-port admittance matrix measurements are suitable for the identification of the behavioral circuit model of a system, in general for any number of ports
Full Modal-Admittance Matrix In-Circuit Measurement by Multiple Inductive Probes
Get PDFIn past years, the use of clamp-on inductive probes was proposed for measuring the impedance or admittance at radio frequencies while the equipment under test (e.g., power electronic converters) is in operation. However, previous one-port methods (involving either one or two probes) allow only an approximate determination of the common-mode (CM) or differential-mode (DM) self-impedance, depending on how the probe/s is/are clamped on wires, and requesting (for DM) the disconnection of the CM return wire. Furthermore, with a single port it is not possible to determine the mutual-modal impedance parameter related to mode conversion. In this paper, a recently proposed multiport measurement method, originally intended for physical admittance measurement, is adapted to modal admittance measurements, resulting in a fast and effective solution for the characterization of full admittance matrices in the modal domain. By experimental tests on passive test networks, it is shown that the proposed method provides accurate results of the true CM/DM self and mutual admittances
- …
