The widespread use of distributed generation (DG), which is installed in medium-voltage distribution networks, impacts the future development of modern electrical systems that must evolve towards smart grids. A fundamental topic for smart grids is automatic distributed voltage control (ADVC). The voltage is now regulated at the MV busbar acting on the on-load tap changer of the HV/MV transformer. This method does not guarantee the correct voltage value in the network nodes when the distributed generators deliver their power. In contrast, the ADVC allows control of the voltage acting on a single generator; therefore, a better voltage profile can be obtained. In this paper, an approach based on sensitivity theory is shown to control the node voltages regulating the reactive power injected by the generators. After the theoretical analysis, a numerical example is presented to validate the theory. The proposed voltage regulation method has been developed in collaboration with Enel Distribuzione S.p.A. (the major Italian DSO), and it will be applied in the Smart Grids POI-P3 pilot project, which is financed by the Italian Economic DevelopmentMinistry. Before the real field application in the pilot project, a real-time digital simulation has been used to validate the algorithm presented. Moving in this direction, Enel Distribuzione S.p.A. built a new test center in Milan equipped with a real-time digital simulator (from RTDS Technologies)

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In the last years the European Union has actively promoted the renewable energies and the Combined Heat and Power (CHP) also for residential and tertiary buildings. The exploitation of renewable sources and cogeneration seems hampered by the regulatory wall that prohibit for residential, tertiary and commercial buildings the constitution of users clusters. In fact, the unification up to a threshold value of some tens of kVA, at least, can facilitate the installation of renewable energy power plants as solar PV modules or CHP systems (cogeneration) or CCHP systems (tri-generation), overcoming technical and economical barriers and combining several load profiles. The actual distribution system for low voltage LV customers appears inadequate to comply with these goals. At this aim the authors propose the design of a Sustainable Energy Microsystem (SEM) for the integration of different subsystems, currently independent, as final users and high efficiency buildings, dispersed generation from renewable and Combined Heat and Power (CHP) units and subsystems for the urban mobility: metro-transit, trams and recharging of plug-in hybrid and electric vehicles (PHEV) for the surface mobility. The integration is analyzed in the direction of a smart city concept, with the optimized and integrated management of many services. These activities are about the general topic of design and construction of nearly zero energy buildings with the use of innovative technologies as home and building automation. The buildings integrated in energy hub with dispersed generation and urban mobility systems, constitute the energy islands of the future smart grid. © 2012 IEEE

Electric railway power systems (ERPS) as one of the most critical and high-power end-user loads of utility grids are characterized by outlandish power quality (PQ) problems all over the world. The extension and evolution of different supply topologies for these systems has resulted in significant and various forms of distortions in network voltage and current in all ERPS, the connected power system, and adjacent consumers. During the last years, numerous studies have been offered to investigate various aspects of PQs in a specific supplying topology. Variation in the supply structure of the ERPS and different types of locomotives has propelled the observation of different PQ phenomena. This versatility and development have led to confront considerable types of two-way interactive interfaces as well as reliability and PQ problems in ERPS. In addition, the lack of standards explicitly dedicated to ERPS has added to the ambiguity and complexity of this issue. In this paper, an extensive review of PQ distortions and phenomena in different configurations of ERPS is proposed and a systematic classification is presented. More than 140 scientific papers and publications are studied and categorized which can provide a fast review and a perfect perspective on the status of PQ indexes for researchers and experts.

Many different types of electric vehicle (EV) charging technologies are described in literature and implemented in practical applications. This paper presents an overview of the existing and proposed EV charging technologies in terms of converter topologies, power levels, power flow directions and charging control strategies. An overview of the main charging methods is presented as well, particularly the goal is to highlight an effective and fast charging technique for lithium ions batteries concerning prolonging cell cycle life and retaining high charging efficiency. Once presented the main important aspects of charging technologies and strategies, in the last part of this paper, through the use of genetic algorithm, the optimal size of the charging systems is estimated and, on the base of a sensitive analysis, the possible future trends in this field are finally valued.

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