Control Scheme with Zero Cancellation for Grid-Connected Inverters with LCL Filter

Distributed generation contributes to the decar-bonization by integrating more renewable sources. Voltage-source inverters (VSI) are typically used to control the energy produced by this type of sources and inject it into the grid. Inductive- capacitive-inductive (LCL) filters are one of the preferred options for connecting the VSI to the grid due to their high attenuation at high frequencies and compact size. However, a proper control system must be designed to ensure an appropriate time response of the current injected into the grid. Many existing control systems employ multiple control loops and require a high number of sensors or, alternatively, estimators, which introduce zeros that can negatively affect the time response. This work proposes a control design method based on the transfer function concept, measuring only the grid -side current and the grid voltage. The design is implemented in discrete time, allowing for the selection of the closed-loop system's poles and the cancellation of all zeros with moduli less than one. Experimental validation demonstrates the excellent performance of the proposed control scheme.