Wilson Negrão Macêdo

Assessment of Harmonic Distortion in small grid-connected photovoltaic systems

This paper aims to analyze the interaction between three different solar inverters, coupled to a small grid-connected photovoltaic system (located at north of Brazil). Total Harmonic Distortions of voltage (THDv) and current (THDi) are analyzed, and thus, the power quality delivered by each of these equipment to local distribution grid is evaluated. It is found, through operational data collected, that the analyzed small solar inverters results in considerable THDis levels when subjected to power levels below its rated value but, the resulting THDvs, in all analyzed inverters, are within the acceptable range according to technical standards. Finally, another important point analyzed is the installation power factor that can change significantly depending on the PV system production capacity and the installation demand profile.

Implementation and Validation of Energy Conversion Efficiency Inverter Models for Small PV Systems in the North of Brazil

The increasing amount of distributed photovoltaic (PV) system components into distribution networks involves the development of accurate simulation models that take into account an increasing number of factors that influence the output power from the distributed generation systems. The modeling of PV system components in power systems and the relative control architecture is an important part of the introduction of a relevant quantity of renewable energy to the future development of the smart grid. Therefore, it is essential to have proper validated models to help operators perform improved studies and be more confident with the results. We present two energy conversion efficiency inverter models developed for two small PV systems using the Jantsch inverter models (Jantsch, Schmidt, Schmid, Results of the concerted actions on power conditioning and control. XI European Photovoltaic Solar Energy Conference, Swiss, 1992) and Sandia inverter model (King, Gonzalez, Galbraith, Boyson,Performance model for grid-connected photovoltaic inverters, Sandia National Laboratory Report, New Mexico, 2007). The component models were implemented in MATLAB software and the simulation results were compared, firstly, with the datasheet values of the inverter Xantrex GT2.8-NA-240/208 UL-05 model and then with the microinverter Enphase® Energy (M215) model. To confirm the strong dependency on ambient conditions and to validate the simulation models, operation data from two small PV systems using the Xantrex and Enphase Energy inverters located in the north of Brazil were used and statistical analysis and comparison of the results was performed.