Operation of Single-phase Grid-Connected Inverters with Large DC Bus Voltage Ripple

Large electrolytic capacitors are usually employed in single-phase grid-connected voltage source inverters (VSI) of distributed energy resources (DER). They are bulky and have a relatively short life time what motivates their replacement by smaller film type capacitors. Resulting issues such as the increased dc bus voltage ripple and smaller inertia to active power variations are discussed in this paper. The former tends to increase the low order harmonics of the injected current, what becomes an even more challenging matter when the bandwidth of the voltage loop is increased to compensate for the latter. A solution based on a voltage ripple estimator is presented and is verified by means of simulation results.