LCL-Filter Design to Suppress Transient Overshoots of Grid-Connected Inverters under Grid Voltage Fluctuations or Faults

Grid-connected inverters are widely used in the distributed power generation systems (DPGSs). The grid voltage fluctuations or grid faults are considerably harmful to the inverter and even the DPGSs. To cope with the demand of high- or low-voltage ride-through, many fault voltage support strategies were proposed. Note that an important issue, i.e., the current or voltage overshoot before the supporting strategy took over, was not deeply discussed. Instead, the system elements including the capacitors and switches with high voltage or current ratings have to be used, which might not be cost-effective. Hence, this study analyzes the transient behavior of a grid-connected LCL-filtered inverter while the grid voltage varies. The impacts of system parameters on the overshoots have been discussed. It has been shown that the LCL filter parameters can have considerable impacts. Consequently, a novel design method has been proposed to suppress the transient overshoots. Hence, because of the reduced overshoots, the voltage or current level of inverter components can be reduced.