Control based power quality improvement in microgrids

Power quality issue is one of the major concerns in modern power grids due to higher penetration of renewable energy based distributed generation sources. In this thesis, advanced inverter control mechanisms are developed to improve power quality, specifically 1) voltage and frequency regulation, and 2) reactive power sharing in microgrids. The virtual synchronous generator (VSG) control method is employed as a primary control mechanism in this research work, and several advanced control techniques are developed. The incorporation of a fuzzy secondary controller (FSC) and an adaptive virtual impedance loop in the VSG control scheme is proposed to improve voltage and frequency regulation, and reactive power sharing performance in microgrids, respectively. A systematic approach of the control system design is presented in details, and dynamic models of test microgrids are developed using MATLAB/Simulink. Extensive simulation studies are carried out to verify the effectiveness of the proposed methods through case and sensitivity studies. It is found that the proposed methods offer significantly improved performance compared to existing techniques, and dynamic characteristics of microgrids under disturbance conditions are enhanced. Furthermore, in this study a new data driven analytics approach is proposed for determination of Q-V (reactive power-voltage) curve of grid connected wind farms, which can provide useful information for voltage control action