Modeling and Stability Analysis of Grid-Connected Inverters with Different LCL Filter Parameters

Microgrid are gaining popularity due to several advantages like potential for fuel savings and resiliency in case of grid catastrophic failures. In a microgrid, many energy sources like wind and solar farms are connected to the grid through inverters with different power ratings and LCL filter parameters. The inverters incorporated in these systems might have a different frequency response and stability ranges than those inverters with identical LCL filter values. This paper establishes the model and analyzes the stability of a system with multiple paralleled-and grid-connected inverters with different LCL filter parameters using the grid-side currents as feedback signals. The analysis results showed that a method similar to the interactive and common current analysis technique used on inverters with identical LCL filters can be implemented on a system with different LCL filers to calculate the maximum values of the inverters' current controller gains without having to derive the complicated equations of the MIMO system.