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In this paper a deep investigation of supercapacitor device modeling is performed with specific reference to hybrid energy storage modules, suitable to support both all electric /hybrid propulsion and on board MVDC distribution marine systems. In those applications, the combination of batteries and supercapacitors in realizing energy storage hybrid devices overtakes the intrinsic disadvantages of single use of electrochemical batteries and supercapacitors. On the other hand, proper design and management strategies of hybrid architecture are required in order to achieve the best performance in terms of dynamic and life cycle assessment on load profile of marine applications. In this way, the main results presented in this paper consists in a simple quadratic mathematical model of supercapacitor, evaluated as a quadratic function of the ultra-capacitor voltage, which is validated experimentally on the base of operative-cycle-based loading profiles, representative of marine application. The results and comparison reported in this work confirm the validity of the proposed model for preliminary design of hybrid energy storage systems and management strategies evaluation on the electrification of ship power systems.

This study is devoted to a proper modeling and estimation method of battery capacity fading under the widely adopted exponential decay model, in view of an efficient lifetime assessment of battery. The method is based upon recursive online Bayes estimation of capacity fading. It is also shown how a degradation-based modeling of battery reliability can be adopted, leading to a Bernstein lifetime distribution. The performances of the proposed method are successfully evaluated by means of extensive Monte Carlo simulations based upon available literature and experimental data. A brief account is also given of a robustness analysis of the proposed methodology with respect to departures from the assumption of Gaussian noise.

This paper proposes a new methodological approach in the field of studies devoted to proper and accurate selection of a reliability model for battery systems. The study is performed with particular emphasis on the modeling and estimation of the Conditional Reliability Function, conceived as a key analytical tool in predicting the "Remaining useful life" of the battery, which is in turn an important information in order to identify the best maintenance strategy selection, or for inspection optimization, and also spare parts provision. Estimation of the Conditional Reliability Function is developed by means of a method based on the Inverse Gaussian Distribution and its Bayes Estimation. The performances of this estimation are developed and validated by means of extensive simulations and available experimental data. A brief account is reported of robustness analyses of the method with respect to the assumed prior Distribution.

The containment of voltage variation within admissible ranges is one of the most challenging power quality issue to address in modern low voltage distribution networks. This is due to the widespread use of highly intermittent distributed generators as well as the increasing presence of some types of loads which imply severe variability (e.g., plug-in electric vehicles). The complexity of the voltage regulation is also emphasized by the integration of different devices able to participate at the voltage regulation. An emerging solution is the use of on-load tap changers for the transformers supplying low voltage networks. Due the high fluctuation of the voltages, the main drawback in using the on-load tap changer is the increased number of operation and the corresponding reduction of the lifetime duration. To address this issue., in this paper a new technique is proposed which allows controlling the on-load tap changer by improving the network voltage profile and, at the same time, preserving the lifetime of the tap changer. To do that, a control strategy is formulated in terms of optimization problem whose objective is the minimization of bus voltage fluctuation while limiting the number of operation of the tap changer and satisfying other constraints related to the network and its components. The results of a numerical application are reported and discussed to show the feasibility of the proposed approach.

In this paper the hardware implementation of a PV microinverter based on dual coupled-inductors dc-dc converters is presented. Coupled-inductors were sized to ensure a high coupling factor, as well as to reach the desiderate voltage gain. Moreover, wide Band-Gap devices allowed to reduce weight and volume of the overall system. The control technique was optimized by adding a PI regulator to a sliding mode controller. Preliminary experimental tests are shown to demonstrate that the circuit is fully-functional and that the design approach was well-conceived.

In the last years a great interest has been paid in the relevant literature to the benefits deriving from the use of direct current for ship power systems. This is in compliance with the most recent concept about all-electric-ship and smart electrical distribution for achieving better performances by exploiting as far as possible the potentiality of integrated power systems. In this context the storage devices play a crucial role in improving the reliability, the efficiency and the dynamic performances of the whole electric system. Moreover, compared to conventional ship propulsion plants, this approach has a significant impact on ship design (particularly when combined to azimuthing thruster or podded thrust units) as regards comfortable (noise and vibrations), flexibility (for general plan), consumption and environment protection. The variety of pulsed and intermittent loads also requires a proper choice of the storage devices and of the techniques for the optimal system design. Focusing on DC ship power systems, in this paper two different methodologies for the design of combined storage systems constituted by batteries and supercapacitors are proposed. Based on some typical loads, some relevant case studies are analyzed and discussed.

Aiming to explore the applicability of Gas-Insulated Lines (GILs) over long distances, in this paper we perform a technical comparison between a GIL and a three-conductor bundled, traditional overhead line (OHL), for a 400 kV, 200 km long connection. The technical comparison is based upon transmission capacity and power losses. We derive the transmission capacity of the two systems from the relevant loadability curves, for the selected line length L=200 km. For this length, OHLs loadability curves are normally determined by the voltage drop limit, ΔVMAX (i.e. the maximum voltage drop allowed across the line), whereas the GIL loadability can be determined – according to the selected GIL parameters – by the thermal limit. In addition to power losses in the conductors, Gil losses include losses in the enclosures. The results point out remarkable advantages for the GIL solution.

The paper deals with the issue of achieving a dynamic equivalent for large scale power systems with particular reference to the European Network of Transmission System Operators for Electricity (ENTSO-E) Continental Synchronous European Area (CESA). In this paper some essential aspects of the dynamic reduction process are deepened while others are faced according some practical considerations, in some cases derived from other studies in ENSTO-E community. Broadly speaking therefore, it deals with a preliminary study which leads to the deployment of a reduced order model able to describe the electromechanical phenomena occurring on the European Continental Synchronous network.