Power sharing between parallel inverters by using droop control with a secondary control loop

Analysis of power sharing between parallel grid-connected inverters is a popular topic in the microgrid research area. In this paper, droop control with a secondary control loop is presented for an AC microgrid, to improve the accuracy of power sharing performance between parallel inverters. The secondary control loop calculates the reference active power and reactive power input to P-f/Q-V droop control. The proposed method can be used in microgrids which contain many micro sources and loads variations for both islanding and grid-connected operation modes. A simulation model for a microgrid with three generators is built to test the performance of the proposed control method using MATLAB/SIMULINK platform. Results of the new method are compared with the virtual impedance droop control method to illustrate the advantages of the proposed power-sharing method.