Improvement of Control Method for Parallel Connected Inverter Systems Based on Improved Droop Control

Abstract

In this paper, the three phase static inverter coordinates were modeling and analysis, the effect of equivalent output impedance on the parallel system is also studied. and designed based on the virtual inductance control strategy. The realization method and design method of the virtual inductance in the DQ two-phase rotating coordinate system are given. The traditional droop control equation has been modified to solve the frequency distortion phenomenon of the traditional droop control equation and the output voltage drop caused by the virtual inductance. The new control equation introduces the dynamic differential term, the power quadratic term and the voltage peak feedback. Through steady and transient analysis of the system, the ideal experimental waveform proves that the improved droop control algorithm has better dynamic performance and current sharing effect.