Low-voltage ride through capability of three-phase grid-connected photovoltaic inverters with slim film capacitors

In grid-connected photovoltaic (PV) power stations, improving the life expectancy and long-term reliability of three-phase PV inverters is urgently needed to match the significantly higher lifetime of the PV modules. A key contribution towards such improvement is replacing the conventional electrolytic film capacitors inside the inverter with metallized polypropylene film ones. With more and more PV power generation systems being installed, the utilities require these generation systems to remain connected to the ac grid during grid faults/voltage sags to ensure the operating stability of the ac power system. This paper presents a detailed analysis of how the control of PV inverters deploying film capacitors can be improved to enable them comply with the low voltage ride through capability demanded by the stringent current grid codes in the events of voltage sags/grid faults. The simulation and experimental results obtained in this study confirm that this modified inverter configuration can meet the grid codes and retain longer lifetimes expected from the use of slim film capacitors.