A Synchronous-Reference-Frame I-V Droop Control Method for Parallel-Connected Inverters

Abstract

A simple and fast decentralized Current-Voltage (I-V) droop control method under the Synchronous-Reference-Frame (SRF) is proposed to share output current for parallel three-phase inverters with LC filter. The I-V droop characteristic is derived in accordance with the virtual impedance in SRF. Thus, each inverter enables to work in a voltage controlled mode where it controls the filter capacitor voltage. Moreover, a detailed state-space model of two parallel inverters is derived to analyze the control performance. Through the simulation and experiment validation, the proposed method provides accurate current sharing and faster transient response under inverter connection in comparison with the conventional droop control.