A Modified Droop based Decentralized Control Strategy for an Islanded AC Microgrid

Abstract

Microgrid is gaining more attention as a new solution for meeting progressive power demand because of its smooth and reliable integration into main grid. Various system characteristics are greatly affected in a microgrid due to a sudden load disruption. These features include current sharing, voltage and frequency variation, and real and reactive power sharing among many inverters. To accomplish autonomous voltage and frequency regulation, a droop-based decentralized control technique for parallel functioning inverters is studied in this article. There is also adequate power sharing among the inverters. Conventional P-f/Q-V and P-V/Q-f droop laws are used in the suggested control technique. In stand-alone mode, both simple and modified droop laws are simulated for control of two parallel inverters. The new operating values for frequency and voltage in simplified droop control are dependent on real and reactive power respectively, whereas in case of modified droop control, these set points are function of both real and reactive power. The time domain simulation is performed in both the MATLAB/SIMULINK and OPAL-RT digital environments. The performance assessment of the system along with the aforesaid control strategy effectively maintain the voltage synchronization, current sharing accuracy, frequency stability, and active power sharing of both the inverters. Also under varying load condition, this control scheme distribute the active power and restores the frequency more efficiently.