A modified droop control method for parallel operation of VSI's in microgrid

The methods based on the droop characteristics have inherent advantages in parallel operation of voltage source inverters (VSI's). The droop control method requires information of voltage and current only at point of common coupling without any communication link between individual inverters. In conventional droop method, the active and reactive power are shared in linear relation to frequency and voltage, hence, the performance of the controller is imprecise under different loading conditions. In this paper, a modified droop characteristics has been proposed for sharing power among the VSI's in order to achieve better frequency and voltage regulation. This modified method has the ability to regulate the frequency even at low power outputs while preventing overloading during peak power demand. The modelling and simulation of the proposed method has been performed in MATLAB/SIMULINK to validate the approach.