Fuzzy secondary controller based virtual synchronous generator control scheme for microgrids

In a microgrid with distributed generation (DG) units, proper control of the grid interfacing inverter is critical to facilitate safe and stable operation of the system. The droop control mechanism is a widely accepted control method in a microgrid operation. However, a droop controller is unable to provide inertia support in such systems, and thus, cannot contribute in primary frequency control during disturbances. The virtual synchronous generator (VSG) method was introduced in 2007 for the grid interfacing inverter control, this approach can provide virtual inertia support along with emulation of steady-state droop characteristics of synchronous generators. In this paper, a fuzzy secondary controller (FSC) based VSG control scheme is proposed for voltage and frequency regulation in microgrids. The proposed control scheme shows significantly improved dynamic performance when compared with conventional droop and conventional VSG control through several case studies. Its effectiveness and robustness is further evaluated through sensitivity studies.