Nicola Femia

Prof. Nicola Femia

orcid

Research Focus & Metrics

Academic Career Length

36Years (1991-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 July 2005 in IEEE Transactions on Power Electronics
Verified
Journal Article
Closed access
NFNicola Femia
Nicola Femia
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panels temperature and on irradiance conditions. The issue of MPPT has been addressed in different ways in the literature but, especially for low-cost implementations, the perturb and observe (P&O) maximum power point tracking algorithm is the most commonly used method due to its ease of implementation. A drawback of P&O is that, at steady state, the operating point oscillates around the MPP giving rise to the waste of some amount of available energy; moreover, it is well known that the P&O algorithm can be confused during those time intervals characterized by rapidly changing atmospheric conditions. In this paper it is shown that, in order to limit the negative effects associated to the above drawbacks, the P&O MPPT parameters must be customized to the dynamic behavior of the specific converter adopted. A theoretical analysis allowing the optimal choice of such parameters is also carried out. Results of experimental measurements are in agreement with the predictions of theoretical analysis.

24 June 2008 in IEEE Transactions on Industrial Electronics
Verified
Journal Article
Closed access
NFNicola Femia
Nicola Femia
GLGianpaolo Lisi
Gianpaolo Lisi
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
One of the major drawbacks of photovoltaic (PV) systems is represented by the effect of module mismatching and of partial shading of the PV field. Distributed maximum power point tracking (DMPPT) is a very promising technique that allows the increase of efficiency and reliability of such systems. Modeling and designing a PV system with DMPPT is remarkably more complex than implementing a standard MPPT technique. In this paper, a DMPPT system for PV arrays is proposed and analyzed. A dc and small-signal ac model is derived to analyze steady-state behavior, as well as dynamics and stability, of the whole system. Finally, simulation results are reported and discussed.

28 August 2009 in IEEE Transactions on Industrial Electronics
Verified
Journal Article
Closed access
NFNicola Femia
Nicola Femia
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
In double-stage grid-connected photovoltaic (PV) inverters, the dynamic interactions among the DC/DC and DC/AC stages and the maximum power point tracking (MPPT) controller may reduce the system performances. In this paper, the detrimental effects, particularly in terms of system efficiency and MPPT performances, of the oscillations of the PV array voltage, taking place at the second harmonic of the grid frequency are evidenced. The use of a proper compensation network acting on the error signal between a reference signal provided by the MPPT controller and a signal that is proportional to the PV array voltage is proposed. The guidelines for the proper joint design of the compensation network (which is able to cancel out the PV voltage oscillations) and of the main MPPT parameters are provided in this paper. Simulation results and experimental measurements confirm the effectiveness of the proposed approach.

20 November 2006 in IEEE Transactions on Aerospace and Electronic Systems
Verified
Journal Article
Closed access
NFNicola Femia
Nicola Femia
DGD. Granozio
D. Granozio
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
The use of one-cycle control (OCC) for maximum power point tracking (MPPT) and power factor correction (PFC) in grid connected photovoltaic (PV) applications is discussed. Circuit and operating parameters of the one cycle-based controller of a cost-effective single-stage inverter are optimized in order to obtain the best performances of the system under different irradiance levels. Firstly, design constraints are formulated which allow to get a very efficient OCC operation in terms of power extracted from the PV array, stability, and PFC. Afterwards, such constraints are used to perform the parametric optimization of the one cycle controller by means of suitable heuristic approaches. Various selection criteria of the best parameters set under different conditions are discussed and applied. Finally, a customized perturb and observe (P&O) control is applied to the optimized one cycle controlled single-stage inverter in order to perform a real MPPT in presence of varying irradiance conditions. Subjects described here are covered by the Italian Patent Application SA2005A000014-13.07.2005 and PCT Application PCT/IT2005/000747-20.12.2005

1 January 2004
Verified
Conference Paper
Closed access
NFNicola Femia
Nicola Femia
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
In presence of rapidly changing atmospheric conditions, the Perturb and Observe (P&O) maximum power point tracking (MPPT) algorithm can be confused due to the fact that it is not able to distinguish the variations of the photovoltaic array output power caused by the duty cycle modulation from those ones caused by the irradiance variation. In this paper, it is shown that the negative effects associated to such a drawback can be greatly reduced if the magnitude of the duty-cycle perturbations is customized to the dynamic behavior of the specific dc-dc converter adopted to realize the P&O MPPT. As an example, a boost battery charger has been studied

1 January 2004
Verified
Conference Paper
Closed access
NFNicola Femia
Nicola Femia
Giovanni PetroneGiovanni Petrone
Giovanni Petrone
Giovanni SpagnuoloGiovanni Spagnuolo
Giovanni Spagnuolo
MVMassimo Vitelli
Massimo Vitelli
This paper shows that the efficiency of the Perturb and Observe (P&O) maximum power point tracking (MPPT) control technique can be improved by optimizing its sampling interval T, according to the converter's dynamics. During sunny days, when the maximum power point of the photovoltaic (PV) array moves very slowly, the sampling interval T, must be set as short as possible without causing instability. If the algorithm samples the array voltage and current too quickly, it is subjected to possible mistakes caused by the transient behavior of the PV array+converter system, thus missing temporarily the MPP. As a consequence, the algorithm can be confused, the energy efficiency decays, and the operating point can become unstable, entering disordered behaviors. The solution proposed in this paper lies in choosing T, according to the converter's dynamics. The choice of the value of T, according to the proposed approach ensures a three-level steady-state duty-cycle swing around the MPP, whatever the duty-cycle step-size and the irradiance level are. As an example, a boost MPPT battery charger has been studied.