Optimum PR Control Applied to LCL Filters With Low Resonance Frequency

A control strategy for LCL grid-connected voltage source inverters is proposed. Using the injected grid current measurement exclusively, the proposal allows the use of the proportional plus resonant regulator optimum design, regardless of the filter resonance frequency. Simulation and experimental results that demonstrate the validity and effectiveness of the proposal for different LCL filter resonance frequency values are presented. Also its superiority compared with a control method recently proposed in the literature is shown.