Droop control with capacitive virtual impedance loop for single-phase parallel inverter systems

摘要

This work proposes a droop control strategy with a capacitive virtual impedance loop, with the aim to achieve parallel operation of single-phase double conversion UPS inverters. A comparison is made between different output impedance characteristics, demonstrating that capacitive output impedance achieves for the same value of circulating current, better voltage regulation than inductive or resistive output impedance characteristics. Experimental results from two single-phase 2-kVA inverters connected in parallel are presented in order to validate the practical application of the proposal..