This paper presents modeling approaches for step-up grid-connected photovoltaic systems intended to provide analytical tools for control design. The first approach is based on a voltage source representation of the bulk capacitor interacting with the grid-connected inverter, which is a common model for large DC buses and closed-loop inverters. The second approach considers the inverter of a double-stage PV system as a Norton equivalent, which is widely accepted for open-loop inverters. In addition, the paper considers both ideal and realistic models for the DC/DC converter that interacts with the PV module, providing four mathematical models to cover a wide range of applications. The models are expressed in state space representation to simplify its use in analysis and control design, and also to be easily implemented in simulation software, e.g., Matlab. The PV system was analyzed to demonstrate the non-minimum phase condition for all the models, which is an important aspect to select the control technique. Moreover, the system observability and controllability were studied to define design criteria. Finally, the analytical results are illustrated by means of detailed simulations, and the paper results are validated in an experimental test bench

In this paper a novel multi variable maximum power point tracking algorithm is introduced. The method is suitable for distributed photovoltaic applications and, in contrast with the concept of using a power optimizer for each module working independently from the others, the architecture used in this paper is based on the adoption of a centralized controller for distributed DC/DC converters. The technique uses a vectorial control of the converters that perturbs the operating points of all the DC/DC converters at one time and observes the power transferred to the DC link. Simulation results confirm that the proposed technique performs better than other multi variable controls presented in recent literature.

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The integration of renewable energy sources to create microgrids is drawing growing interest to address current energy-related challenges around the globe. Nevertheless, microgrids must be analyzed using specialized tools that allow to conduct operation, technical and economic studies. In that regard, this paper presents a case study in which the software HOMER Energy Pro was implemented to design and analyze the performance of a microgrid. Such microgrid comprises a photovoltaic system, a wind system and a diesel plant. The parameters of the energy systems are based on information about local weather conditions available in databases. Finally, this analysis is performed under two conditions: stand-alone and grid-tied.