Porous GaP layers prepared by electrochemical anodization of (100)-oriented bulk material was found to exhibit blue and ultraviolet photoluminescence when excited by a KrF excimer laser. The energy position of the UV luminescence band (3.3 eV at 300 K) is explained on the basis of charge carrier confinement in crystalline quantum wires of about 25 Å in diameter. Additional evidence for quantum size effect in porous GaP was obtained by Raman scattering measurements.

Photoconductivity, quenching, thermally stimulated current and decay characteristics are studied in ZnIn2S4 single crystals. Evidence is obtained for the presence of three impurity levels taking part in the photoconductivity process. Optical quenching is attributed to a sensitization centre, which acts as a competitive recombination level. An exponential distribution of electron traps is revealed both by pulsed photoconductivity and by thermocurrent analysis. The two experimental techniques accordingly provide the value of 70 meV/decade for the trap distribution. Some aspects of the nature of the impurity centres are examined.

An optimal energy storage system (ESS) management procedure devoted to full renewable energy sources (RESs) exploitation is presented in this paper. It consists of an appropriate scheduling procedure and a real-time control strategy, which both aim to increase the RES penetration level as much as possible. In particular, the one-day-ahead scheduling procedure synthesizes the combined RES-ESS energy production profile with the aim of minimizing the RES energy production curtailments by means of ESS energy buffering. The real-time control strategy is developed in order to track the scheduled profile as well as possible by mitigating forecasting errors, thus improving RES reliability. The worth and effectiveness of the proposed management procedure is verified through a wide simulation study, which is carried out by means of the Matlab software package

A novel online discrete-time parameters identification algorithm suitable for surface-mounted permanent magnet synchronous machines (SPMs) is presented in this paper. It is developed by means of the Model Reference Adaptive System (MRAS) technique and the Popov Hyperstability Criterion in order to identify SPM discrete-time model parameters. In particular, good accuracy of discrete-time parameters is required by digital control systems, especially by predictive control algorithms, which present a low robustness against parameters mismatches. Hence, an extensive simulation study is firstly carried out in the Matlab Simulink environment with the aim of testing the effectiveness and robustness of the proposed identification algorithm against inverter un-idealities. Then, the proposed identification procedure is experimentally validated on a predictive controlled radial-flux SPM, driven by a Field Programmable Gate Arrays (FPGA) control board

Electric power systems are experiencing relevant changes involving the growing penetration of distributed generation and energy storage systems, the introduction of electric vehicles, the management of responsive loads, the proposals for new energy markets and so on. Such an evolution is pushing a paradigm shift that is one of the most important challenges in power network design: the management must move from traditional planning and manual intervention to full “smartization” of medium and low voltage networks. Peculiarities and criticalities of future power distribution networks originate from the complexity of the system which includes both the physical aspects of electric networks and the cyber aspects, like data elaboration, feature extraction, communication, supervision and control; only fully integrated advanced monitoring systems can foster this transition towards network automation. The design and development of such future networks require distinct kinds of expertise in the industrial and information engineering fields. In this context, this paper provides a comprehensive review of current challenges and multidisciplinary interactions in the development of smart distribution networks. The aim of this paper is to discuss, in an integrated and organized manner, the state of the art while focusing on the need for interaction between different disciplines and highlighting how innovative and future-proof outcomes of both research and practice can only emerge from a coordinated design of all the layers in the smart distribution network architecture.

A novel optimal power and energy management (OPEM) for centralized hybrid energy storage systems (HESS) in microgrids is presented in this paper. The proposed OPEM aims at providing multiple grid services by suitably exploiting the different power/energy features of electrochemical batteries (B) and supercapacitors (S). The first part of the paper focuses on the design and analysis of the proposed OPEM, by highlighting the advantages of employing hand-designed solutions based on Pontryagin's minimum principle rather than resorting to pre-defined optimization tools. Particularly, the B power profile is synthesized optimally over a given time horizon in order to provide both peak shaving and reduced grid energy buffering, while S is employed in order to compensate for short-term forecasting errors and to prevent B from handling sudden and high-frequency power fluctuations. Both the B and S power profiles are computed in real-time in order to benefit from more accurate forecasting, as well as to support each other. Then, the effectiveness of the proposed OPEM is tested through numerical simulations, which have been carried out based on real data from the German island of Borkum. Particularly, an extensive and detailed performance analysis is performed by comparing OPEM with a frequency-based management strategy (FBM) in order to highlight the superior performance achievable by the proposed OPEM in terms of both power and energy management and HESS exploitation.ESS in several applications, their use for providing energy and power services is still quite limited. Considering supercapacitors, flywheel and superconducting magnetic ESS, they are very suitable for power services due to their fast dynamic response. However, supercapacitors suffer from very poor energy content, while flywheel and superconducting magnetic ESS are characterized by safety and cost issues respectively. Despite the specific types of ESS, a literature review reveals that a single ESS technology may not be suitable for providing both energy and power services. Consequently, ESS economic viability is still an issue for grid applications, especially due to high investment costs.In this regard, hybrid energy storage systems (HESS) represent a very promising solution; these consist of suitable combinations of both high energy and high power density ESS and thus, of ESS technologies characterized by complementary features [15][16][17][18][19][20]. Consequently, HESS can benefit from the advantages of different ESS technologies, resulting in enhanced performance compared to single ESS. Regarding the high energy density storage unit of the HESS, electrochemical batteries (B), compressed-air or hydrogen-based ESS are generally considered, which are characterized by an adequate energy capacity but relatively slow dynamic performance. It is also possible to make an HESS by combining B with compressed-air or hydrogen-based ESS [16,17]; in these cases, B act as the high power density storage unit due to superior dynamic performances and lower energy density c...

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