VARIABILITY OF SOLAR IRRADIATION ON A SCALE OF MINUTES IN THE STATE OF ALAGOAS
DOI:
https://doi.org/10.59627/cbens.2016.1454Keywords:
Solar Irradiation, Power Ramp, Power VariabilityAbstract
The development of this research was performed from the collected data of global solar irradiation in five localities of Alagoas during the years of 2008 and 2009. They are: "Água Branca", Coruripe, "Pão de Açúcar", "Palmeira dos Índios" e "Santana do Ipanema". To obtain the data of each locality ( solarimetric station) it was used a global solar irradiation sensor, the black and white pyranometer. This sensor was mounted on a metal structure of three meters high on a fixed axis and positioned in north-south direction, avoiding possible shading. The storage of the global solar irradiance data was performed using a data acquisition system with storage capacity of about 50 days. Data were analyzed according to the power variability, called in this paper by the term "ramp rate". The results of this "ramp rate" can have positive or negative values. In this paper the negative results were analyzed, as are caused by shading due to clouds moving over the sensor. The negative results of ramp rates were operated on time scales 1,5,10,15,30,60,120 and 180 minutes. The higher power ramps are observed in smaller time scales, 1 to 5 minutes. For the time scales above 15 minutes, the ramps are concentrated in the range of 0 to 50 W/(m2.min). The locality of Pão de Açúcar presents the smallest totalized annual average of ramps. Therefore, it can be concluded that it is the best locality for a possible installation of a solar plant if this is the only aspect considered.
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