The power generated by photovoltaic solar systems is exposed to high variability of irradiance mainly due to weather conditions, which cause instability in the electrical networks connected to these systems. This study shows the typical behavior of solar irradiance in an Andean city, which presents considerable variations that can reach up to 63% of the nominal power of the photovoltaic system, at time intervals in the order of seconds. The study covers the application of 3 techniques to reduce power fluctuations at the point of common coupling (PCC), with the incorporation of energy storage systems, under the same irradiance conditions. Supercapacitors were used as the storage system, which were selected for their high efficiency and useful life. A state of charge control is also applied by means of a hysteresis band. The three algorithms studied show similar behaviors; however, the ramp control technique has the best performance. The storage system was dimensioned based on the photovoltaic system’s nominal power and the desired rate of change in the PCC, whose capacity can be estimated from Pnom/12 [kWh] and a maximum power that can reach up to 0.63 Pnom. The study determines that based on the storage capacity and the irradiance characteristics under study, the storage system could use at least 5.76 daily charge/discharge cycles. In the study, it is possible to reduce the rate of change of the photovoltaic energy injected into the PCC about 6.66 times with the use of the proposed energy storage system.
Although climate change is a reality, many off-grid communities continue to use diesel generators for electricity supply. This document presents a strategy to reduce diesel consumption in an out-of-grid system formed by renewable sources (PV-HKT-WT-DG). Three energy dispatch strategies have been proposed to verify the impact on diesel consumption and generator operating hours. In addition, different energy storage technologies (acid lead, lithium-ion, vanadium redox flow, pump storage and supercapacitor) have been considered. The HOMER software has been used to calculate the optimal size of the systems through technical-economic indicators.
The results show that it is possible to reduce diesel consumption progressively; however, the cost of energy increases. On the other hand, when using lithium-ion batteries under charge cycle control, the penetration of the diesel generator has been greatly reduced without affecting the cost of the system. Finally, sensitivity analyzes have shown that when demand increases, diesel consumption does not increase significantly by using redox vanadium flow batteries, whereas the diesel generator operating hours decrease significantly in all systems.
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