Unified Grid-Forming/Following Inverter Control

Abstract

The paper describes an inverter control scheme which incorporates both a phase-locked loop (PLL) for voltage synchronization and power-frequency droop for load sharing. As such, it is a hybrid grid-forming/following controller and offers beneficial characteristics of both. The model describing the dynamic behaviour of the inverter control scheme is presented and connections with grid-forming and grid-following control strategies are considered. A process for black-starting the PLL-based inverter control scheme is described. Case studies explore controller small- and large-disturbance performance under a variety of system conditions.