Showing papers by "Concettina Buccella published in 2013"

A Survey on Smart Grid Potential Applications and Communication Requirements

Abstract: Information and communication technologies (ICT) represent a fundamental element in the growth and performance of smart grids. A sophisticated, reliable and fast communication infrastructure is, in fact, necessary for the connection among the huge amount of distributed elements, such as generators, substations, energy storage systems and users, enabling a real time exchange of data and information necessary for the management of the system and for ensuring improvements in terms of efficiency, reliability, flexibility and investment return for all those involved in a smart grid: producers, operators and customers. This paper overviews the issues related to the smart grid architecture from the perspective of potential applications and the communications requirements needed for ensuring performance, flexible operation, reliability and economics.

Linearization of LLC resonant converter model based on extended describing function concept

Abstract: LLC resonant DC-DC converters are becoming increasingly popular due to their ability to work with zero voltage switching (ZVS) feature. The reduction in switching power losses, especially in high frequencies, greatly enhances the efficiency of these converters in comparison with conventional PWM boost converters. This paper presents theoretical details for modeling the LLC resonant converter, by which its characteristic and dynamic behavior can be analyzed. To obtain an accurate model, the extended describing function concept is used and the approximate nonlinear model derived. Then the derived model is linearized in vicinity of the steady state operating point and the state space matrices of the system are obtained. The accuracy and validity of the model is then verified using MATLAB/Simulink.

A grid-connected PV system with LLC resonant DC-DC converter

Abstract: This paper presents a grid-connected photovoltaic (PV) system with a three level voltage source converter (VSC) using double closed loop control strategy. The outer DC voltage control loop is to regulate the DC bus voltage, and the inner current control loop is to synchronize the output current with the grid voltage, thus ensuring unity power factor. A LLC resonant DC-DC converter is used in the proposed system to step-up the voltage of the PV array and to extract maximum power. It is intrinsically isolated by a high frequency transformer, then the parasitic capacitance of the PV panels to ground could not be of concern; furthermore, because of soft switching technique, it operates at high frequency with low switching losses. Size and cost of the magnetic components and DC-link capacitor are decreased compared with traditional boost converters. An incremental conductance method integrated within PI controller was used to extract maximum power by PV. Simulation results based on MATLAB/Simulink verify the validity and dynamic performance of the proposed system during fast solar irradiation changes and ensure DC bus voltage stability.

Smart charging infrastructure for electric vehicles

Abstract: In view of electro-mobility, charging infrastructure for electric vehicles needs to be deployed optimally to keep them powered up. This paper aims at developing a framework with novel aspects for deployment of charging infrastructure for EVs. This paper discusses the pros and cons of various proposed techniques for EVs charging infrastructure and also compares different available technologies in the current scenario. Moreover, various charging characteristics of battery electric vehicles and different charging methodologies and standards are investigated for practical realization of the facility infrastructure framework. Then, this paper presents a novel smart bidirectional interface equipped with multilevel cascaded power converter with embedded strategies of reverse energy flow management supporting enhanced expansion of renewable energy integration in order to keep stress on the power grid to a minimum. Moreover this paper proposes appropriate wireless communication technologies for deploying effective communication bridge among all nodes of the network in order to make the infrastructure smart. MatLab simulations are performed for provision of quality of service vs. operating cost of the charging facility. The simulation results show that the proposed technique prevails over the other available technologies in terms of cost and QoS. Future research work is also mentioned in this paper for the complete development of the proposed framework of smart charging station.

Optimal operation of Smart Grids with demand side management

Abstract: The integration of Distributed Generation (DG) based on renewable energy sources in Smart Grids (SGs) is considered a challenging task due to the intermittent nature of the renewable energy sources that are only partly predictable and to the requirement related to the consumers' participation in the electricity market. This paper proposes an Energy Management System (EMS) integrating demand side management and active management schemes for the optimal operation of a SG in presence of DG based on renewable energy sources. Simulation results demonstrate that a better integration of DG can be achieved with the proposed EMS allowing flexibility enhancement and energy costs reduction for customers.

Harmonics elimination in 5-level converters operating at very low switching frequency

Abstract: This paper deals with the problem of harmonics reduction in cascaded multilevel converters throught Selective Harmonic Elimination. The method consists of an analytical procedure for identifying a set of switching angles capable of eliminating the desired harmonics and a graphical analysis tool allowing the identification of all valid solutions. Because of their industrial interest, relatively complex 5-level inverters have been considered, however the proposed method can be easily extended to a higher number of levels, too. The main advantage of the proposed approach is its simple implemention, which can be accomplished by using low cost digital signal processors. Simulations and experiments are presented for demonstrating the achievable results.

An analytical algorithm for Selective Harmonic Elimination and efficient control in five-level inverters

Abstract: Traditional methods, such as Modulating-Functios, Space-Vectors and Feedback Methods present the disadvantage of high residual harmonics. Selective Harmonic Elimination (SHE) generates trains of pulses such as the fundamental component of the resulting waveform has a specified frequency and amplitude while selected order harmonics are eliminated. To achieve this goal, a set of nonlinear equations must be solved. SHE offers many distinctive features including high quality of the output waveform, low switching frequency at fundamental frequency ratios, possibility to select the harmonics to be deleted and the ability to leave triplen harmonics uncontrolled. On the other side, the main drawbacks of SHE methods are their computational burden and the subsequent need of complicated hardware. This paper proposes a new analytical algorithm for SHE in a 5-level cascaded inverter. The proposed method transforms the trascendental system in a polinomial one resulting that analytical solution can be easy obtained using a typical Digital Signal Controller. The achievable results are demonstrated by both simulation and experimental results.

Real-time Harmonics Elimination procedures for high-power converters

Abstract: This paper proposes a Selective Harmonic Elimination algorithm for multilevel power converters. Starting from an analysis of valid modulation index intervals, the algorithm computes those switching angles which eliminate the undesired harmonic. Differently by other approaches, it is based on the use of full analytical and numerical procedures, which can be easily executed in real-time. After a detailed description of the method, simulation and experimental results obtained with a five level cascaded multilevel inverter are shown demonstrating the quality of the achievable results.