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When a converter is used to interface an ac distribution system and a low voltage (LV) dc micro-grid, several combined options for ac and for dc grounding can be used. According to the selected grounding scheme, zero-sequence dc or high frequency currents may flow in specific sections of the circuit. These, in turn, can cause EMC issues, unwanted protection trips and other problems. In the present...
The correct operating mode of protection systems is a fundamental aspect in order to guarantee a good quality of service to loads connected to a distribution grid. This paper deals with naval plants that, being dominated by power electronic converters can lead to malfunctioning of protection systems due to limited fault currents. The solution proposed by the authors consists in introducing a storage...
A modular multilevel converter based on MosFET half bridge modules has been recently proposed for the energy management and the drivetrain control of electric vehicles. This topology provides an active balancing of the cells in addition to the control of the propulsion motor, thus integrating into the same controller also the function of a battery management system. This paper analyses the possibilities...
The rail traffic in Europe is increasing in frequency. As a result of this, all the countries are updating their power supply system involving the use of high-power static converters. Moreover, the high required power implies the use of medium voltage (MV) supply chains (i.e. 15–25 kV) while the traction drives are operated at voltages of some kV. In order to adapt the two voltage levels, an on board...
In the recent years, there has been a considerable increment of diffused generators connected to distribution grids by means of power converters. These converters operate frequently below their rated power due to the fluctuation of the power generated by the renewable sources. In this scenario, power electronics interfaces could be also used as active harmonic compensators for other converters or...
In recent years, DC/DC converters have become more and more widespread due to the development of new DC energy sources. This has led to intensive studies of DC/DC converters and new configurations have been proposed in the literature. In particular, there are very interesting high efficiency configurations. The current fed, DC/DC push-pull converter with two input inductances was thoroughly analyzed...
In recent years the always increasing demand for storage action lead to the development of many different storage technologies. The choice of the most suitable technology for realizing a storage unit is, obviously, dependent on the peculiarities of the application. Anyway, the problem of a correct choice, at present, has never been analyzed from a rigorous point of view. In this paper a method for...
In the paper some of the battery models proposed in literature are analysed in order to predict the battery performance and, then, make sure that the Battery Management System (BMS) that is a key component to check and control the status of the batteries within their specified safe operating conditions, works in best conditions.
The paper suggests a novel architecture of PV-powered Modular Multilevel Converter for building integrated photovoltaics. A grid-tied single-star configuration has been proposed. In particular, three different cell topologies have been analyzed and compared in terms of number of PV modules and rated voltages of semiconductor devices. Finally, a control strategy has been suggested in order to deliver...
New topologies of switching power converters could improve the efficiency of the energy conversion of battery electric vehicles, by achieving low cell unbalance and reduced harmonic content of the output currents. This article proposes a modular multi-cell converter with embedded cell balancing for battery electric vehicles. In this new topology, the series connection of the cell is obtained by means...
According to recent studies by 2020 a share of almost 12% of the worldwide electricity demand will be provided by the wind. Offshore wind farms are expected to have a significant growth to meet these targets, but higher procurement and operating costs are still limiting factors for their development. Several configurations based on internal DC collection have been proposed with the aim of reducing...
Power quality is becoming more and more important for different kind of users. In particular, for industrial customers it represents a key factor for the productiveness and the efficiency. Also, the wide diffusion of electronic loads implies a spread use of power electronics. In this scenario, DC distribution networks are a suitable solution for solving problems of power quality both for the customer...
The phenomenon of the self-synchronisation in line-start synchronous machines can be suitably used in distributed generation plants. With a simple control equipment based on contactors, it is possible to overcome the restrictions imposed to the synchronous generators in some countries. The paper shows that synchronous machines can be suitable also when both stand-alone and grid-connected operations...
In this paper, we propose a new method for the accurate estimation of frequencies and magnitudes of harmonics and interharmonics caused on the supply-side currents by an adjustable-speed drive. The proposed method consists of a three-step procedure in which Estimation of Signal Parameters by Rotational Invariance Technique (ESPRIT) and Prony high-resolution methods are properly applied together with...
In the technical literature many models capable of representing the behavior of the induction machine have been presented. The traditional Park model is very easy to be implemented but it does not take into account the flux density space harmonics. It is well known that it can be modified in order to consider stator and rotor asymmetries. However for some applications such as the study and the development...
Compliancy to grid codes has been a driving force behind the development of variable-speed technologies for wind generation. This resulted in the doubly-fed induction generator (DFIG) to become a common technology. The operational benefits of the DFIG derive from the possibility of controlling the operating speed of the generator from the rotor windings. Even if constructively different, the Dual-Excited...
The DC distribution networks can easily benefit from integration of electrical storage systems, such as batteries and supercapacitors, to manage the network operations. A proper combination of these two storage units can lead to a storage system able to satisfy power requests lasting from seconds to hours. However, the use of more than one storage unit gives rise to the problem of deciding how to...
The growing diffusion of distributed energy sources is making higher and higher the attention for DC distribution networks, that present some advantages related to an easier integration of renewable energy sources, storage systems and electrical drives. The DC network has to be connected to the traditional AC network by means of a converter interface whose main scope is the regulation of the power...
This paper deals with the use of grid-connected photovoltaic (PV) power plants for supplying the ancillary service of reactive power compensation to the distribution grid. A control strategy has been developed for controlling both real and reactive power exchanged with the distribution network. The paper suggests how the real and reactive power references should be selected in order to maximize the...
The large number of high power conversion applications has brought to the development of complex power converter configurations. A wide class of such converters are based on Power Electronic Building Block (PEBB) constituted of two level modules. Modulation strategies can take advantage of the modularity of these power converter topologies proposing modular and general control strategies. The present...
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