Mitigation Control Against Partial Shading Effects in Large-Scale PV Power Plants

This study proposes a novel control strategy to allow partially shaded photovoltaic power plants (PV-PPs) to mitigate the detrimental effects on the frequency of power systems without the need for energy storage. The strategy divides the PV-PP into N sections operating in a deloaded mode with a specific reserve level. A central controller continually monitors each of these PV sections. When one or more sections are under shaded conditions, the control orders the unshaded sections to deploy their active power reserves to smooth the power output at the interconnection point of the PV-PP. The proposed control was tested in the isolated power system of northern Chile considering different PV scenarios and levels of deload. Results show that the control is effective in assisting frequency regulation, especially under large PV penetration scenarios. For these cases, and only on days with high irradiance variability, the benefits gained from the control strategy could be more valuable for the system than the forgone revenues due to the deloaded operation.