Abstract-This paper presents a set of experimental investigations related to the dynamic behavior of supercapacitors (SCs). The experimentally observed results are then used as inputs for the development of an improved version of one of the most common SC RC-equivalent circuit models. The key improvement concerns the accurate modeling of the diffusion phenomenon of the SC residual charge during charging/discharging and rest phases. The experimental procedure needed for evaluating the parameters of the proposed model is also given. The accuracy of the obtained model is then experimentally validated for different cycles characterized by different dynamics.

a b s t r a c tThe paper presents a network partitioning strategy for the optimal voltage control of Active Distribution Networks (ADNs) actuated by means of a limited number of Distributed Energy Storage Systems (DESSs). The proposed partitioning uses a linear programming approach by means of the known concept of voltage sensitivities. Then, two decentralized optimal control algorithms are proposed relying, respectively, on the Thévenin equivalents and a recursive approach. These algorithms are developed using the MultiAgent System (MAS) concept. With respect to a centralized control algorithm, the aim of the network clustering is to reduce the number of exchanged messages among the clusters when one of the two proposed decentralized control algorithms is adopted. The effectiveness of the two proposed controls is assessed with respect to the performances of the equivalent centralized control using numerical examples composed by the IEEE 13 and IEEE 123 buses distribution test feeders adapted to include stochastic generation and DESSs.

Abstract-In this paper, we consider an active distribution network (ADN) that performs primary voltage control using real-time demand response via a broadcast low-rate communication signal. The ADN also owns distributed electrical energy storage. We show that it is possible to use the same broadcast signal deployed for controlling loads to manage the distributed storage. To this end, we propose an appropriate control law to be embedded into the distributed electrical storage controllers that reacts to the defined broadcast signal in order to control both active and reactive power injections. We analyze, in particular, the case where electrical storage systems consist of supercapacitor arrays and where the ADN uses the grid explicit congestion notification (GECN) for real-time demand response that the authors have developed in a previous contribution. We estimate the energy reserve required for successfully performing voltage control depending on the characteristics of the network. The performance of the scheme is numerically evaluated on the IEEE 34-node test feeder. We further evaluate the effect, depending on the line characteristics, of reactive versus active power controlled injections. We find that without altering the demand-response signal, a suitably designed controller implemented in the storage devices enables them to successfully contribute to primary voltage control.Index Terms-Active distribution network (ADN), ancillary services, broadcast signals, demand response, electrical energy storage systems, primary voltage control.

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Abstract-This paper presents a network partitioning strategy for the optimal voltage control of Active Distribution Networks (ADNs) by means of Dispersed Energy Storage Systems (DESSs). The proposed partitioning is based on the concept of voltage sensitivity coefficients and is adopted for a decentralized voltagecontrol strategy specifically developed for radial ADNs. The aim of the partitioning is to decompose the network into quasiautonomous areas and to limit the information exchange only at the interfacing nodes between adjacent areas. The information exchange relies on Thévenin equivalents to represent the external grids of each cluster/area. The effectiveness of the proposed decentralized control approach is assessed with respect to an equivalent centralized control approach. Such an assessment is carried out using a numerical example referring to IEEE 123 buses distribution test feeder suitably adapted to include stochastic generation and DESSs.

Abstract-Within the context of the electrical circuit modeling of batteries, this paper proposes an improvement of the most common electric equivalent circuit used for Lithium cells. The main improvement is based on the modeling of the so-called charge redistribution phenomenon that characterizes the dynamic voltage during charging/discharging and relaxation phases. In particular, the aim of the paper is to prove that the model recently proposed by the Authors to represent the same phenomenon in supercapacitors, can be extended also to Lithium batteries. The proposed model is validated by means of experimental results carried out on a 30 Ah 2.3 V LithiumTitanate cell with reference to different charge/discharge cycles.

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