H∞ Robust Control of a Grid-Connected Inverter

In this article, implementation of a $H_{\infty}$ controller is carried out to achieve seamless power transfer in a grid-connected inverter. To achieve this objective, a detailed mathematical model of the inverter system in the synchronous reference frame is presented. Considering higher-order nature of $H_{\infty}$ controllers, selection of weighting functions is done such that robust reference tracking and disturbance rejection is achieved. Performance wise, the $H_{\infty}$ controller achieves fast settling, minimal power fluctuation and high disturbance rejection capability when compared with the conventional inverter $dq$-based proportional-integral (PI) control strategy under various test conditions involving grid voltage and load disturbances.