The smart grid is conceived of as an electric grid that can deliver electricity in a controlled, smart way from points of generation to active consumers. Demand response (DR), by promoting the interaction and responsiveness of the customers, may offer a broad range of potential benefits on system operation and expansion and on market efficiency. Moreover, by improving the reliability of the power system and, in the long term, lowering peak demand, DR reduces overall plant and capital cost investments and postpones the need for network upgrades. In this paper a survey of DR potentials and benefits in smart grids is presented. Innovative enabling technologies and systems, such as smart meters, energy controllers, communication systems, decisive to facilitate the coordination of efficiency and DR in a smart grid, are described and discussed with reference to real industrial case studies and research projects.

Demand response and smart grids—A survey

This paper addresses to some of the latest contributions on the application of Finite Control Set Model Predictive Control (FCS-MPC) in Power Electronics. In FCS-MPC , the switching states are directly applied to the power converter, without the need of an additional modulation stage. The paper shows how the use of FCS-MPC provides a simple and efficient computational realization for different control objectives in Power Electronics. Some applications of this technology in drives, active filters, power conditioning, distributed generation and renewable energy are covered. Finally, attention is paid to the discussion of new trends in this technology and to the identification of open questions and future research topics.

State of the Art of Finite Control Set Model Predictive Control in Power Electronics

The authors discuss high-voltage power conversion. Conventional series connection and three-level voltage source inverter techniques are reviewed and compared. A novel versatile multilevel commutation cell is introduced: it is shown that this topology is safer and more simple to control, and delivers purer output waveforms. The authors show how this technique can be applied to either choppers or voltage-source inverters and generalized to any number of switches.<<ETX>>

Multi-level conversion : high voltage choppers and voltage-source inverters

The paper reviews different approaches, technologies, and strategies to manage large-scale schemes of variable renewable electricity such as solar and wind power. We consider both supply and demand side measures. In addition to presenting energy system flexibility measures, their importance to renewable electricity is discussed. The flexibility measures available range from traditional ones such as grid extension or pumped hydro storage to more advanced strategies such as demand side management and demand side linked approaches, e.g. the use of electric vehicles for storing excess electricity, but also providing grid support services. Advanced batteries may offer new solutions in the future, though the high costs associated with batteries may restrict their use to smaller scale applications. Different “P2Y”-type of strategies, where P stands for surplus renewable power and Y for the energy form or energy service to which this excess in converted to, e.g. thermal energy, hydrogen, gas or mobility are receiving much attention as potential flexibility solutions, making use of the energy system as a whole. To “functionalize” or to assess the value of the various energy system flexibility measures, these need often be put into an electricity/energy market or utility service context. Summarizing, the outlook for managing large amounts of RE power in terms of options available seems to be promising.

https://research.aalto.fi/files/6557604/lund_et_al_review.pdf

Review of energy system flexibility measures to enable high levels of variable renewable electricity

A communication infrastructure is an essential part to the success of the emerging smart grid. A scalable and pervasive communication infrastructure is crucial in both construction and operation of a smart grid. In this paper, we present the background and motivation of communication infrastructures in smart grid systems. We also summarize major requirements that smart grid communications must meet. From the experience of several industrial trials on smart grid with communication infrastructures, we expect that the traditional carbon fuel based power plants can cooperate with emerging distributed renewable energy such as wind, solar, etc, to reduce the carbon fuel consumption and consequent green house gas such as carbon dioxide emission. The consumers can minimize their expense on energy by adjusting their intelligent home appliance operations to avoid the peak hours and utilize the renewable energy instead. We further explore the challenges for a communication infrastructure as the part of a complex smart grid system. Since a smart grid system might have over millions of consumers and devices, the demand of its reliability and security is extremely critical. Through a communication infrastructure, a smart grid can improve power reliability and quality to eliminate electricity blackout. Security is a challenging issue since the on-going smart grid systems facing increasing vulnerabilities as more and more automation, remote monitoring/controlling and supervision entities are interconnected.

https://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1315&context=electricalengineeringfacpub

A Survey on Smart Grid CommunicationInfrastructures: Motivations, Requirements andChallenges

This work deals with the characterization of the extremely low frequency (ELF) magnetic field inside the new Italian high speed train with alternate current (a.c.) electrification, which will be realized in the next future. In the proposed model the magnetic field sources are assumed to be the 50 Hz currents flowing in the conductors of the railway line, which are calculated by a circuit analysis of the electrified traction line. The magnetic field in a railway car is then calculated by a CAD field simulator. The computed results in two-dimensional (2D) and three-dimensional (3D) configurations are compared and discussed. The calculated field level are also compared with the magnetic field measured inside an existent European high speed train with a.c. electrification.

Three dimensional magnetic field computation inside a high speed train with a.c. electrification

A new model of numerical dosimetry is proposed for RF exposure. First, the specific absorption rate (SAR) is computed. Then, the heat transfer governed by the bio-heat equation with convection term is numerically solved by a finite-element method (FEM) procedure considering the discrete vascular model of the perfused tissue. By some manipulations of the FEM equations and by generating an adequate FEM mesh, it is possible to solve the thermal convection in the blood vessels considering a one-dimensional domain embedded in the fully three-dimensional domain where only the thermal diffusion is analyzed.

Finite-Element Analysis of Temperature Increase in Vascularized Biological Tissues Exposed to RF Sources

A deterministic algorithm aiming at reduction of harmonic content in three phase, five-level cascaded inverters is proposed. The procedure starts from a non-linear system consisting of disequations and, using Chebyshev polynomials and Waring's formula, for any assigned modulation index computes those switching angles α 1 and α 2 reducing harmonics amplitude such as to fulfill grid code specifications. Simulation and experimental results demonstrate the achievable results.

A deterministic harmonics mitigation technique for five-level inverters

Mathematical proof of a harmonic elimination procedure for multilevel inverters

This paper considers single phase seven-level cascaded H-bridge (CHB) inverters for Uninterruptible Power Supplies (UPS) applications and proposes a fundamental switching frequency procedure, based on graphic analysis, to improve the output waveform quality. It fixes the first switching angle and gets the other two by intersection of harmonics functions set to zero. The performances of the proposed procedure, in terms of total harmonic distortion (THD), are compared with those obtained by a procedure that identifies the two remain optimal switching angles through a THD minimization algorithm. Experimental results are obtained by measurements performed on a prototype built at DigiPower laboratory. The agreement between computed and experimental results confirms the accuracy of the presented procedure.

Concettina Buccella

Papers

Three dimensional magnetic field computation inside a high speed train with a.c. electrification

Finite-Element Analysis of Temperature Increase in Vascularized Biological Tissues Exposed to RF Sources

A deterministic harmonics mitigation technique for five-level inverters

Mathematical proof of a harmonic elimination procedure for multilevel inverters

Seven-level cascaded inverters for Uninterruptible Power Supply (UPS) applications