UPS ( Uninterruptible Power Systems )
Uninterruptible Power Systems (UPS) are another important application of ESSs in renewable microgrids, especially for the islanded renewable microgrids. Renewable sources, such as solar panels and wind turbines, may suddenly stop generating power due to clouds and shading, nightfall or lack of wind. However, start-up of backup generators may take about 10 s . During this period, outages may occur in the microgrid. However, if there is ESS in the microgrid, the loads can be supplied by ESS to ride through the power shortage.
Figure shows an example of a PV microgrid. It has a diesel generator as the backup power and an ESS as the UPS. There is a voltage detector installed at the output of the PV. The voltage detector senses the output voltage of the PV. If the solar panels stop generating power, the output voltage will drop to zero. Then, the voltage detector will send a command to the backup generator and ESS immediately. The switches S1 and S2 will close, so the ESS can replace the PV as the power source to supply the microgrid, and in the meantime the diesel generator will start up. When the start-up process is completed, the diesel generator begins to supply the microgrid. Now, the ESS can be removed from the microgrid by breaking the switch S1.
The PV may start to generate power again. So the diesel generator can be shut off when the output of PV is stable to supply the microgrid. Then, the microgrid goes back to the normal operation. Since the ESS was discharged before, its SOC is not at the maximum. Thus, the microgrid controller can close switch S1 and the ESS is charged by PV.
ترجمه متن و نکات گرامری در پارت آخر ارایه داده خواهد شد.
ups for PV microgrid