Control strategy for autonomous operation of three-phase inverters dominated microgrid under different line impedance

The traditional power droop controllers are commonly used in distributed generation (DG) units to share the loads among the parallel inverters. However, the parameters of the power transmission and distribution line in microgrid are small and generally presented high resistance-to-inductance (R/X) ratio which will seriously influence the performance of the traditional power droop controller, even leading to instability. In this paper, the control strategies for parallel inverters under the inductive and resistance line impedance are researched contrastively based on the small signal models of the power loop. The employed droop scheme can maintain the load sharing capability under different line impedance. These theoretical findings are eventually verified experimentally on laboratory prototypes.