A novel load flow method for islanded microgrids with optimum droop coefficients

Abstract

The integration of renewable energy resources into the power system has led to growing interest in the field of microgrids. These microgrids can operate in grid-connected or islanded modes.Load flow analysis is an important step for the operation and planning of the power system. The traditional load flow techniques, which use the concept of a reference bus, are not valid in microgrids, particularly when operating in islanded mode. Thus, in this study, a modified Gauss-Seidel method has been implemented in which to find the optimum values for droop coefficients, different optimisation techniques have been used. The value of droop gain impacts the load distribution among various DGs, as the fast action of droop is indicated by a higher value of droop gain. But the inappropriate value of droop gain affects the stability of the system, so typically the values are kept low due to steady state stability concerns. The optimum droop gain helps to keep the voltage and frequency within the permissible limits. The voltage profile has been improved with optimal gains for the droop coefficients, and about 4% loss reduction has been reported, proving the effectiveness of the proposed method. The method has been tested on 6-bus, 38-bus, and 40-bus islanded microgrid systems.