No abstract

Shading on photovoltaic (PV) modules induces disproportionate impacts on power production. This paper presents a fault detection method able to identify anomalies on PV systems such as shading problems. The presence of localized shading on PV modules leads to an overheating of the shaded PV cells despite the activation of bypass diodes. The temperature increase reduces considerably PV module performances and its lifetime. The presented method uses a simple equation, which corresponds to the normalized error (DE) of the comparison between the I-V curve in normal operation and the I-V curve in shading condition. The first derivative calculation gives the area of the detection in function of the PV voltage of the module (DE/DV). This defines whether one or several PV cells dissipate power. This phenomenon essentially occurs in the case of non-uniform irradiance received on PV modules and could impact PV modules performances. The detection method is explained in detail through the study of specific shadows simulations on PV modules. The results are validated through experimental tests on PV modules.

No abstract

This study presents the analysis and design of a sliding-mode control of a buck converter operating in continuous conduction mode that minimises the energy during start-up and provides output voltage regulation in front of input voltage perturbations and load disturbances. A linear combination of inductor current and capacitor voltage errors with respect to their corresponding equilibrium values is analysed as a switching surface. A linear matrix inequalities (LMI)-based analysis to\ud obtain optimum coefficients of the linear combination reveals that the best compromise between inrush current and output response rapidity is the current control given by the switching surface S(x) = iL − IE, where IE is the current coordinate of the equilibrium point. This surface is proposed for start-up and for rejecting input voltage perturbations, because it is demonstrated that the current control is inherently insensitive to input voltage variations. Output voltage regulation in front of\ud load perturbations or input voltage variations is achieved once the converter is in a steady state by modifying S(x) with the\ud insertion of a PI-correcting network. The resulting controller is implemented analogically and employs two switching\ud surfaces, that is, one surface for start-up and another one for output voltage regulation. The theoretical predictions are verified by means of simulation and experimental results.Postprint (published version

A perturb and observe algorithm based on both the power-current characteristic of a photovoltaic (PV) panel and the sliding-mode control of the input inductor current of an associated converter is investigated in a static application. A single ended primary inductance converter (SEPIC) converter charging a battery from a PV generator illustrates the procedure whose effectiveness is proved with experimental results. The reported technique is appropriate for distributed maximum power point tracking of PV systems with output series connected DC-DC switching converters. In these systems, each converter is supplied by an independent PV panel at the input port whereas its output port is connected in series with the output ports of the other converters. The proposed converter interconnection is based on a transformer-less SEPIC because of the capability of this converter to step-up or step-down the input voltage. The resulting system allows maximum power extraction from each PV source even in cases of non-uniform irradiance.

The paper analyses extremum-seeking control technique for maximum power point tracking circuits in PV systems. Specifically, the paper describes and analyses the sinusoidal extremum-seeking control considering stability issues by means a Lyapunov function. Based on this technique, a new architecture of MPPT for PV generation is proposed. In order to assess the proposed solution, the paper provides some experimental measurements in a 100 W prototype which corroborate the effectiveness of the approach.

The integration of passive components on silicon for future DC-DC converters applications is still a challenging area of research. This paper reports the microfabrication of a fully integrated filter containing a spiral inductor on top of a 3D capacitor. A thin magnetic shielding layer is introduced between the two components demonstrating that losses caused by the inductor in the capacitor area are reduced, thus increasing the maximum working frequency of the whole component. The fabricated filter was characterized in a test circuit (buck-type converter).

This paper proposes a system analysis focused on finding the optimal operating conditions (nominal capacity, cycle depth, current rate, state of charge level) of a lithium battery energy storage system. The purpose of this work is to minimize the cost of the storage system in a renewable DC microgrid. Thus, main stress factors influencing both battery lifetime (calendar and cycling) and performances are described and modelled. Power and energy requirements are also discussed through a probabilistic analysis on some years of real data from the ADREAM photovoltaic building of the LAAS-CNRS in Toulouse, FRANCE.