Passivity-Based Design of Repetitive Controller for $LCL$-Type Grid-Connected Inverters Suitable for Microgrid Applications

A repetitive controller (RC) is one of the most promising candidates for harmonic compensation when designing current grid-connected inverters. The discrete-time closed-loop transfer function based frequency response method can be used to shape RC, which applicable a single inverter connecting well-known inductive-impedance grids, but cannot guarantee stability in case capacitive-impedance grids or complex systems, such as microgrids. To address this issue, article presents new passivity-based design an RC LCL-type inverters with either inverter-side grid-side control. With proposed guidelines, output admittance RC-controlled tuned passive all frequencies, so that it plug and play connected grid regardless impedance. Meanwhile, thanks infinite gains at fundamental its multiples high-quality injected accordance IEC 61000-3-4 standard ensured even presence distorted conditions. Finally, experimental results established lab prototype are provided verify effectiveness approach.