Control and Instability Analysis of Multiple Inverters Parallel Based on Droop Control

As a power conversion interface for new energy generation into the power grid, grid-connected inverters are more and more widely used in modern power systems, and multiple inverters parallel technology has become one of the most mature technologies. When multiple inverters operate in parallel, droop control can be used to solve the problem of power sharing without relying on communication equipment. In order to ensure the stability of the inverter, three factors should be considered in the parameter design of the droop control, which are stability of drooping power outer loop, stability of voltage control double closed-loop and effects of current limiting on system stability. In this paper, the root locus method, bode diagram analysis method and simulation analysis method are used to theoretically analyze the stability problems caused by the above three factors. Meanwhile, the theoretical analysis is verified in Matlab/Simulink environment, which proves the correctness of the theoretical analysis.