Current Control of a Grid-Connected Converter with an LCL Filter Using Small-Signal Analysis Considering Grid Impedance

In a three-phase grid-connected converter with an LCL filter, the impact of grid impedance on the current control loop is a crucial factor that cannot be overlooked in control system design. Grid impedance influences the phase-frequency characteristics of the system, which affects its stability. This paper analyzes the configuration of a three-phase grid-connected converter and develops its small-signal model in detail. The impact of grid impedance on the stability of the converter is examined using a Bode-based analysis model. The paper provides a detailed explanation of how to perform such small-signal analyses in the PLECS simulation environment without the need for manually deriving the system's transfer functions. At the final stage, a simulation model was developed using the power electronic switch libraries available in the simulation software PLECS to assess the performance of the designed current regulation system.